Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Location and properties of some of the major loci affecting the segregation distortion phenomenon in… Sharp, Cecil Bert 1977

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1977_A6_7 S38.pdf [ 4.16MB ]
Metadata
JSON: 831-1.0094064.json
JSON-LD: 831-1.0094064-ld.json
RDF/XML (Pretty): 831-1.0094064-rdf.xml
RDF/JSON: 831-1.0094064-rdf.json
Turtle: 831-1.0094064-turtle.txt
N-Triples: 831-1.0094064-rdf-ntriples.txt
Original Record: 831-1.0094064-source.json
Full Text
831-1.0094064-fulltext.txt
Citation
831-1.0094064.ris

Full Text

THE LOCATION AND PROPERTIES OF SOME OF THE MAJOR LOCI AFFECTING THE SEGREGATION  DISTORTION  PHENOMENON IN DROSOPHILA MELANOGASTER  by  CECIL BERT SHARP B.Sc,  University  o f B r i t i s h Columbia, 1975  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in  THE FACULTY OF GRADUATE STUDIES (Department of Zoology)  We accept t h i s t h e s i s as conforming t o the required  standard  THE UNIVERSITY OF BRITISH COLUMBIA October, 1977 ©  C e c i l Bert  Sharp  In  presenting  this  an a d v a n c e d  degree  the L i b r a r y  shall  I  further  for  scholarly  by h i s of  agree  this  written  at  thesis  make i t  freely  that permission  for  It  University  financial  British  Oct. 4,  1977  of  Columbia,  British  by  for  gain  Columbia  shall  the  requirements  reference copying  of  I agree and this  that  not  copying  or  for that  study. thesis  t h e Head o f my D e p a r t m e n t  is understood  Zoology of  of  for extensive  permission.  of  fulfilment  available  p u r p o s e s may be g r a n t e d  2075 Wesbrook Place Vancouver, Canada V6T 1W5  Date  in p a r t i a l  the U n i v e r s i t y  representatives.  Department The  thesis  or  publication  be a l l o w e d w i t h o u t  my  ii ABSTRACT  There has  r e c e n t l y been renewed i n t e r e s t c o n c e r n i n g  major l o c i r e s p o n s i b l e melanogaster. and  Rsp.  to be Rsp  Rsp  f o r the S e g r e g a t i o n D i s t o r t i o n phenomenon i n  H a r t l (1974) has confers  shown t h a t two  both are  i n s e n s i t i v i t y to S>D chromosomes, w h i l e S<1 i s  l o c a t e d between T f t and  these f i n d i n g s by deleted  on a SD  the Sd^ s i t e .  cn.  ^d  Ganetzky (1977) has  d i s t o r t i o n and  that, i f deleted  of  extended  i s a locus that, i f he  argues t h a t t h i s i s  from a SD  reduces the a b i l i t y of t h a t chromosome to d i s t o r t and i s an enhancer of J3D,  The  considered  Ganetzky (1977) a l s o uncovered another important l o c u s , i n or  near the h e t e r o c h r o m a t i n of 2L,  located very  Drosophila  i s l o c a t e d to the l e f t  showing t h a t j u s t d i s t a l to ;p_r t h e r e  chromosome, e l i m i n a t e s  the  major s i t e s are i n v o l v e d : Sci  the major l o c u s t h a t i n i t i a t e s d i s t o r t i o n ,  and  the l o c a t i o n of  E(SD).  he  chromosome, g r e a t l y  argued t h a t t h i s  Ganetzky (1977) , a l s o suggests t h a t Rsp  might  c l o s e to the centromere i n the p r o x i m a l h e t e r o c h r o m a t i n of  r e s u l t s p r e s e n t e d here demonstrate the presence of an important  of J5D l o c a t e d w i t h i n the p r o x i m a l h e t e r o c h r o m a t i n of 2L. show t h a t t h e r e  site be  2R.  component  These r e s u l t s a l s o  i s another important s i t e l o c a t e d j u s t d i s t a l to _p_r_.  However,  when t h i s s i t e i s removed by r e c o m b i n a t i o n from a JSD chromosome, a c e r t a i n l e v e l of r e s i d u a l d i s t o r t i o n remains. (1977) c a l l e d E(SD)  I t i s argued t h a t the s i t e t h a t Ganetzky  i s l i k e l y responsible  absence o f the s i t e j u s t d i s t a l to J D T . and  the s i t e near JLt i s c a l l e d Sd^,.  r e d u c t i o n , but not chromosome.  and  Sd^  Loss of e i t h e r s i t e r e s u l t s i n a l a r g e  complete e l i m i n a t i o n , of the d i s t o r t i n g a b i l i t y of a  t h a t Rsp  c l o s e to the  Miklos  Thus the s i t e near _p_r i s c a l l e d  Other d a t a are p r e s e n t e d t h a t , on  (1977) p r o p o s a l very  f o r t h i s r e s i d u a l d i s t o r t i o n i n the  SD  the whole, agree w i t h Ganetzky's  i s l o c a t e d i n the c e n t r o m e r i c h e t e r o c h r o m a t i n of  centromere.  Smith-White (1971) have suggested t h a t k  (the  segregation  2R,  r a t i o observed from a given mating) i s a d e c e p t i v e measure of the degree of d i s t o r t i o n and they have proposed another method of measuring d i s t o r t i o n based on t h e i r model o f sperm d y s f u n c t i o n .  Some of the weak assumptions o f t h i s  model a r e d i s c u s s e d and a s i m p l e r a l t e r n a t i v e i s p r e s e n t e d .  The a l t e r n a t i v e  model assumes t h a t the p o t e n t i a l s e g r e g a t i o n r a t i o s o f a p o p u l a t i o n o f SD males f o l l o w a t r u n c a t e d normal d i s t r i b u t i o n . n e c e s s a r i l y inconsistent with likely of  t h i s assumption.  Data a r e presented  The same data show t h a t i t i s  t h a t c e r t a i n SJJ chromosomes d i f f e r i n t h e i r s u s c e p t i b i l i t y I t i s concluded  distortion.  t h a t a r e not  that at present k provides  to m o d i f i e r s  the c l e a r e s t measure o f  XV  TABLE OF CONTENTS PAGE  ABSTRACT  i i  TABLE OF CONTENTS  iv  LIST OF TABLES  v  LIST OF FIGURES  vi  ACKNOWLEDGEMENT  viii  GENERAL INTRODUCTION CHAPTER I .  1  ON MEASURING DISTORTED SEGREGATION RATIOS Introduction  . . . . .  8  •  28  M a t e r i a l s and Methods Results  and D i s c u s s i o n  30  Conclusion CHAPTER I I .  46  ON THE LOCATION AND PROPERTIES OF SOME OF THE LOCI AFFECTING SEGREGATION DISTORTION Introduction  •  50  M a t e r i a l s and Methods  54  Results  55  and D i s c u s s i o n  Conclusion 86 LITERATURE CITED  87  LIST OF TABLES TABLE I. II. III.  PAGE The distorting abilities of the b SD-5 recombinants.  60  The distorting abilities of the b pr SD-5 recombinants.  62  The distorting abilities of miscellaneous SD-5 recombinants.  IV.  64  The distorting abilities of R(SD-5)-x/SMl males mated to homozygous cn bw females.  V.  The distorting abilities of R(SD-5) b pr-5 under various circumstances.  VI.  68  Tests to determine i f Sd_ , on b pr It pk cn is semi+  active. VII.  71  The distorting abilities of R(SD-72) b pr-x/cn bw males mated to cn bw/cn bw females.  VIII.  67  75  The sensitivites of b-bearing recombinants, from Or-R/b pr rl cn females, when heterozygous with R(SD-5) pk cn.  IX.  The sensitivities of cn-bearing recombinants, from Or-R/b pr rl cn, when heterozygous with R(SD-5)b-8.  X.  79  80  The sensitivities of cn bw chromosomes with JT-ray induced lethals on them.  82  VI  LIST OF FIGURES FIGURE 1.  PAGE The relationships between k and k at various values c  m  of k .  12  f  2.  The relationships between k and c  at various values  of k . m 3.  14  The relationships between the distribution of make values within a male (m), the threshold of dysfunction (P), the proportion of Sp_ sperm that dysfunction (e), and the +  make level of a male (m ).  21  1  4.  The relationship between dk/dm and mean k.  5.  A model similar to Miklos and Smith-White's, except P  1  is allowed to vary and 0^ e q u a l s ^ . 6.  3 5  A diagrammatic test for normality of the distributions df arc sin 7k" of the 6 "SD" chromosomes tested.  9.  3 2  A diagrammatic test for normality of the k distributions of the 6 "SD" chromosomes tested.  8.  26  The observed k distributions of the 6 "SD" chromosomes tested.  7.  23 •  37  The observed and predicted relationships between the variance of k (without the binomial component) and mean k.  43  vii  FIGURE 10.  PAGE The complementation relationships between the putative SD-5 deficiencies and Hilliker's  (1976) groups of lethal  mutations in the proximal heterochromatin of 2L. 11.  57  The complementation relationships between the cn bw chromosomes bearing putative deficiencies and Hilliker's (1976) groups of lethal mutations in the proximal heterochromatin of 2R.  84  ACKNOWLEDGEMENT  I would like to thank Dr. David G. Holm for his support of and interest in the present study.  Thanks are also due to Mr. Steve Borden  for analysing some of the data with a computer and to Dr. Conrad F. Wehrhahn for providing useful statistical advice.  The technical assist-  ance of Loren Caira was most helpful, as were the many suggestions of Dr. Arthur J .  Hilliker.  1  GENERAL INTRODUCTION  Segregation d i s t o r t e r S a n d l e r i n 1959.  (SD) was  first  r e p o r t e d by S a n d l e r , H i r a i z u m i , and  They noted t h a t some second chromosomes taken from a n a t u r a l  p o p u l a t i o n near Madison,  W i s c o n s i n , showed abnormal s e g r e g a t i o n r a t i o s .  p a r t i c u l a r , these chromosomes were r e c o v e r e d f a r i n excess of the 1:1 expected from the c r o s s of SD/cn bw males mated to cn bw/cn bw c i n n a b a r eyes, and bw,  brown eyes, t o g e t h e r produce  The r e c o v e r y r a t i o , d e f i n e d as the number of ^D number of progeny  and g i v e n the symbol k, was  males, was  (cn,  phenotype).  d i v i d e d by the  o f t e n i n excess of 0.9.  the v a l u e o f k f o r the r e c i p r o c a l c r o s s , SD/cn bw  ratio  females.  a white-eyed  progeny  In  total However,  females mated to cn bw/cn bw  0.5.  These r e s u l t s suggested t h a t the mechanism of jSD r e s i d e d i n some abnorma l i t y of e i t h e r male spermatogenesis  fragments  Sandler, H i r a i z u m i ,  t h a t SD induced a break i n i t s homologue d u r i n g  and S a n d l e r (1959) proposed prophase  or s p e r m i o g e n e s i s .  I and t h a t t h i s break fused to form a d i c e n t r i c b r i d g e and d u r i n g anaphase I I .  acentric  P r e l i m i n a r y c y t o l o g i c a l evidence i n d i c a t e d  d i c e n t r i c b r i d g e s and a c e n t r i c fragments  that  c o u l d be observed d u r i n g male m e i o s i s  ( S a n d l e r , H i r a i z u m i , and Sandler 1959); however, these o b s e r v a t i o n s c o u l d not be v e r i f i e d  (Peacock and E r i c k s o n 1965).  Although t h i s h y p o t h e s i s does not have d i r e c t does have i n d i r e c t g e n e t i c evidence i n i t s f a v o u r . t h a t r a r e cn bw viabilities  c y t o l o g i c a l support, i t H i r a i z u m i (1961) observed  chromosomes r e c o v e r e d from SD/cn bw males had lower homozygous  than d i d cn bw  chromosomes r e c o v e r e d from SD"*"/cn bw males.  In  a d d i t i o n , Crow, Thomas, and S a n d l e r (1962) found t h a t the response o f male r e combination t o r a d i a t i o n was heterozyous males.  much g r e a t e r i n SD heterozyous males than i n  SD  +  Both of these experiments were c o n s i s t e n t w i t h the hypo-  t h e s i s t h a t SD induces chromosome breaks i n i t s homologue.  Peacock and E r i c k s o n (1965) were unable t o d e t e c t any c y t o l o g i c a l abnorm-  3 a l i t i e s i n the m e i o t i c d i v i s i o n s o f STJ males.  Because o f t h i s and  the  indirect  n a t u r e of the e v i d e n c e i n support of the breakage h y p o t h e s i s , they m o d i f i e d the f u n c t i o n a l p o l e h y p o t h e s i s of N o v i t s k i and  Sandler (1957) to e x p l a i n SD.  The  f u n c t i o n a l p o l e h y p o t h e s i s h o l d s t h a t i n male m e i o s i s t h e r e are two p o l e s and that the p r o d u c t s of one p o l e f u n c t i o n i n f e r t i l i z a t i o n , w h i l e the p r o d u c t s of the o t h e r p o l e are r e g u l a r l y n o n f u n c t i o n a l , a l t h o u g h m o t i l e and t r a n s f e r r e d the female.  Peacock and E r i c k s o n (1965) proposed  e n t i a l l y o r i e n t i n g the SD chromosome toward  t h a t SD o p e r a t e s by  the f u n c t i o n a l p o l e .  prefer-  In support  of t h i s model, Peacock and E r i c k s o n (1965) showed t h a t w i t h both SD/cn bw w i l d type males the number of progeny a female y i e l d e d was  and  equal to approxi-  mately o n e - h a l f the number o f sperm t r a n s f e r r e d t o the female. Zimmering and Fowler  to  However,  (1968) have shown t h a t the e f f i c i e n c y of sperm u t i l i z a t i o n  v a r i e s between females, depending  upon t h e i r genotype.  The  c o l o u r ) females used by Peacock and E r i c k s o n n o r m a l l y u t i l i z e  ( y e l l o w body o n l y about  one-  h a l f of t h e i r s t o r e d sperm, whereas Oregon-R ( w i l d type) females use up to e i g h t y per cent of the sperm t r a n s f e r r e d by Oregon-R males. appear t h a t because of the type of female used  Thus i t would  to o b t a i n progeny to sperm  r a t i o s , Peacock and E r i c k s o n ' s (1965) r e s u l t s were  atypical.  The  functional  p o l e h y p o t h e s i s does not appear to apply g e n e r a l l y t o D r o s o p h i l a males and c o n s e q u e n t l y i t i s a poor s t a r t i n g p o i n t from which to develop an h y p o t h e s i s f o r e x p l a i n i n g mechanisms f o r the a c t i o n o f  SD.  A much more r e a s o n a b l e s t a r t i n g p o i n t i s p r o v i d e d by the r e s u l t s of H a r t l , . H i r a i z u m i , and Crow (1967).  They demonstrated  t h a t i f both SD/cn bw  and cn  bw/  cn bw males were p r o v i d e d w i t h an excess o f v i r g i n females u n t i l the males became s t e r i l e , and i f the females were re-brooded  u n t i l they ceased to l a y  f e r t i l i z e d eggs, then the cn bw/cn bw males produced d i d the SD/cn bw males.  T h i s f i n d i n g suggested  males, a SD/cn bw male can produce  twice as many progeny as  t h a t , compared to cn bw/cn bw  o n l y o n e - h a l f the number of  functional  4 sperm. cn bw  T h i s i n t u r n suggested  that i n SD/cn bw males the sperm which  chromosomes are somehow rendered  carry  dysfunctional.  Some of the s t e p s i n v o l v e d i n t h i s d y s f u n c t i o n p r o c e s s have r e c e n t l y been elucidated.  Tokuyasu, Peacock,  and Hardy (1977) have r e p o r t e d a d e t a i l e d  study of spermiogenesis i n SD/cn bw males and they have compared those r e s u l t s w i t h e a r l i e r o b s e r v a t i o n s they made on spermiogenesis i n normal males Tokuyasu, and Hardy 1972;  Tokuyasu 1974).  (Peacock,  The e a r l i e s t d i f f e r e n c e s between  normal males and SD/cn bw males are observed d u r i n g the t r a n s f o r m a t i o n of the e a r l y s p h e r i c a l spermatid n u c l e u s i n t o the h i g h l y condensed n u c l e u s o f the mature s p e r m a t i d .  and  compact  In a SD/cn bw male the chromatin of cn  bw  b e a r i n g spermatids f a i l s t o condense to the same degree as e i t h e r the chromat i n of S>D b e a r i n g spermatids or the chromatin of a l l the spermatids i n a male.  L a t e r i n spermiogenesis these spermatids w i t h i m p r o p e r l y condensed  w i l l frequently f a i l brane  normal heads  to become i n d i v i d u a l i z e d by the i n d i v i d u a l i z a t i o n mem-  t h a t d e l i m i t s the o t h e r spermatids from the syncytium i n which they were  formerly located.  In normal males,  a f t e r i n d i v i d u a l i z a t i o n the sperm undergo  a c o i l i n g p r o c e s s p r i o r to r e l e a s e i n t o the t e s t i c u l a r lumen. males,  In SD/cn bw  those sperm which are i m p r o p e r l y i n d i v i d u a l i z e d are f r e q u e n t l y not  c o i l e d w i t h the r e s t of the bundle and  subsequently degenerate.  i n SD/cn bw males that have k v a l u e s near 1.0,  However, even  one f r e q u e n t l y observes among  the c o i l e d sperm of a s i n g l e c y s t a few sperm that have i m p r o p e r l y chromatin.  Thus, a l t h o u g h the m a j o r i t y o f the cn bw-bearing  condensed  sperm are  d u r i n g s p e r m i o g e n e s i s , a few a r e l i k e l y t r a n s f e r r e d t o females, but  lost  their  a b i l i t y to f u n c t i o n i n f e r t i l i z a t i o n i s s e v e r e l y l i m i t e d , p r o b a b l y owing to t h e i r abnormally condensed  nuclei.  Improper c o n d e n s a t i o n of chromatin suggests t h a t the t r a n s i t i o n  from  l y s i n e - r i c h to a r g i n i n e - r i c h h i s t o n e s observed d u r i n g spermiogenesis i n normal  5 D r o s o p h i l a males (Das, Kaufmann, and Gay 1964) cn bw-bearing  spermatids of SD/cn bw males.  s i n c e Kettanah and H a r t l  i s somehow impaired i n the  In f a c t , t h i s i s l i k e l y  the case,  (1976) have found that the l y s i n e - r i c h to a r g i n i n e -  r i c h t r a n s i t i o n cannot be d e t e c t e d c y t o c h e m i c a l l y i n _SD homozygotes.  Although the f i r s t  c y t o c h e m i c a l and m o r p h o l o g i c a l m a n i f e s t a t i o n s of seg-  r e g a t i o n d i s t o r t i o n occur d u r i n g the n u c l e a r c o n d e n s a t i o n phase of  spermiogene-  s i s , Mange (1968) has shown t h a t the s e g r e g a t i o n r a t i o s of SD/cn bw males are s e n s i t i v e to temperature  shocks a p p l i e d d u r i n g the e a r l y stages of m e i o s i s .  However, t h i s o b s e r v a t i o n i s not n e c e s s a r i l y i n c o n s i s t e n t w i t h the h y p o t h e s i s t h a t the mechanism of s e g r e g a t i o n d i s t o r t i o n i n v o l v e s m o d i f i c a t i o n of the t r a n s i t i o n from l y s i n e - r i c h to a r g i n i n e - r i c h sperm h i s t o n e s , s i n c e Gould-Somero and H o l l a n d (1974) have demonstrated  by means of a u t o r a d i o g r a p h y t h a t RNA  t h e s i s ceases p r e - m e i o t i c a l l y i n D r o s o p h i l a males. ceases p r e - m e i o t i c a l l y i t i s not unreasonable mediate  the improper  t h a t temperature  Because RNA s y n t h e s i s  to assume that the f a c t o r s which  c o n d e n s a t i o n of chromatin i n SD  also present p r e - m e i o t i c a l l y .  Furthermore,  +  b e a r i n g spermatids are  i t i s not unreasonable  shocks can a f f e c t these f a c t o r s i n such a way  a l t e r the frequency of S D  +  syn-  sperm w i t h i m p r o p e r l y condensed  to assume  t h a t they w i l l  chromatin.  In s p i t e of the r e c e n t advances e l u c i d a t i n g the g e n e r a l mechanism by which s e g r e g a t i o n d i s t o r t i o n o p e r a t e s , t h e r e i s s t i l l t i o n c o n c e r n i n g the l o c i i n v o l v e d i n the p r o c e s s . undertaken  to s o l v e t h i s problem;  been amazingly ambivalent.  a l a c k of s o l i d  informa-  Numerous s t u d i e s have been  however, the r e s u l t s of these s t u d i e s have  The purpose  of the p r e s e n t study was  to  approach  t h i s mapping problem by u s i n g methods that d i f f e r e d somewhat from those used by p r e v i o u s workers,  i n the hope that a f i r m e r c o n c l u s i o n c o u l d be made con-  c e r n i n g the l o c i i n v o l v e d .  T h i s i n t u r n s h o u l d c e r t a i n l y h e l p to complement  b i o c h e m i c a l s t u d i e s determine  a more d e t a i l e d u n d e r s t a n d i n g of the mechanisms  involved i n segregation  distortion.  P r e v i o u s s t u d i e s have examined the p r o p e r t i e s of SD recombinants r e c o v e r ed between pr  ( p u r p l e eyes) and  cn  ( c i n n a b a r eyes) (Sandler and  1960b, H i r a i z u m i and Nakazima 1967), Cy_ ( c u r l y wings) and Sandler 1962), and  T f t ( t u f t e d wings) and  cn ( H a r t l 1974).  markers p r o v i d e one  l o c u s i n the euchromatin of 2L and  euchromatin of 2R.  S i n c e the c e n t r o m e r i c h e t e r o c h r o m a t i n  i n the e a r l i e r s t u d i e s , one  c o u l d not p o s i t i o n the SD  cn  Hiraizumi  (Crow, Thomas and These p a i r s o f  the other i n the had  not been marked  l o c i r e l a t i v e to  this  b l o c k of h e t e r o c h r o m a t i n .  In the p r e s e n t study the marker chromosome used to  o b t a i n SD recombinants was  b p r I t pk cn.  T h i s chromosome c a r r i e d l j :  e y e s ) , a l o c u s l o c a t e d i n the c e n t r o m e r i c h e t e r o c h r o m a t i n Holm 1975).  In a d d i t i o n to r e c o m b i n a t i o n ,  of 2L  (Hilliker  gation  I will  some c o n s i d e r a t i o n s p e r t a i n i n g to the measurement of d i s t o r t e d ratios.  and  I a l s o employed d e l e t i o n mapping.  However, b e f o r e examining the r e s u l t s of these mapping experiments, present  (light  segre-  7  CHAPTER I ON MEASURING DISTORTED SEGREGATION RATIOS  INTRODUCTION  One  o f t h e most  important  when e s t i m a t i n g a g e n e t i c different  genotypes  two  different  the  frequencies  factors  segregation  involved.  In  a l l e l e s o f a s i n g l e gene a r e of the  relative of  two a l l e l e s i n t h e  the  the v i a b i l i t y  If  segregation  males,  problem with  but  is  progeny  SP"*" c h r o m o s o m e .  one  t h a t J5D o p e r a t e s i n m a l e s , b u t n o t  that  reflect  occur i n  T h u s SD and c n bw p r o g e n y r e c o v e r e d  a l l e v i a t e d to a c e r t a i n extent  the  chromosomes.  r e c o m b i n a t i o n does n o t  r e c o v e r e d from female  in  then  from  n o t be g e n o t y p i c a l l y i d e n t i c a l t o p r o g e n y o f  right  is  One m e t h o d  r a n d o m i n , f o r e x a m p l e , S D / c n bw f e m a l e s ,  does o c c u r i n f e m a l e s .  S D / c n bw p a r e n t s .  the  However,  this  b e c a u s e m o s t JSD chromosomes h a v e  one  a r m o f chromosome 2 , w h i c h g r e a t l y r e d u c e  the  o f r e c o m b i n a t i o n between  Another problem w i t h viability  property  t h i s method i s  more i n v e r s i o n s , i n t h e  frequency  equal  o f p r o g e n y b e a r i n g t h e ^ D chromosome  of progeny b e a r i n g these  same v i s i b l e p h e n o t y p e s problem i s  the  randomly,  r e c o v e r e d p r o g e n y may n o t b e  of progeny b e a r i n g the  m a l e S D / c n bw p a r e n t s w i l l  or  l o c a t e d may be s e g r e g a t i n g  r e c o v e r y o f SD a n d c n b w - b e a r i n g p r o g e n y s h o u l d a p p r o x i m a t e l y  relative viability  One  of  chromosomes on w h i c h  a l l e l e s may b e l e s s v i a b l e t h a n  i n d e t e r m i n i n g the v i a b i l i t y  d o i n g t h i s makes u s e o f t h e  relative  the r e l a t i v e v i a b i l i t y  case of Segregation D i s t o r t e r i n D r o s o p h i l a melanogaster,  to  females.  is  consideration  other.  the  interested  ratio  For example, although the  b e c a u s e p r o g e n y b e a r i n g one o f t h e b e a r i n g the  w h i c h must be t a k e n i n t o  cn. and b w .  t h i s method i s  that  it  i s possible that  o f SD a n d c n bw b e a r i n g p r o g e n y may d i f f e r  t h e m a l e o r f e m a l e p a r e n t was S D / c n b w . t i v e v i a b i l i t y may b e a s s o c i a t e d w i t h  That i s ,  a maternal  it  the  relative  depending upon whether is  effect.  conceivable that  rela-  9 However, I do not f e e l t h a t the p o s s i b l e e f f e c t s of e i t h e r o f the above problems would be s u f f i c i e n t l y l a r g e t o n u l l i f y the advantages o f a t t e m p t i n g to measure the r e l a t i v e v i a b i l i t y o f SD and S D the r e c i p r o c a l c r o s s , i . e . w i t h SD/SD  +  as the female p a r e n t .  t h a t the method i s a p p r o x i m a t e l y v a l i d , determined  b e a r i n g progeny by p e r f o r m i n g  +  I f one assumes  then one can use the s e g r e g a t i o n r a t i o  from a c r o s s where the female parent i s SD/SD , g i v e n the symbol k^, +  to c o r r e c t the s e g r e g a t i o n r a t i o determined i s SD/SD , g i v e n the symbol k ^  from a c r o s s where the male p a r e n t  T h i s c o r r e c t e d s e g r e g a t i o n r a t i o , g i v e n the  +  symbol k^, i s o b t a i n e d as f o l l o w s : k k  c  / k  m +  k  K)  f  I T  T h i s formula, however, does n o t take i n t o account v a r i a t i o n i n k and k_. m r One  can use t h e means o f k and k^ i n o r d e r t o o b t a i n an e s t i m a t e of k , but m f c  t h i s e s t i m a t e w i l l n o t be the mean o f k , i t w i l l be the mode o f k . c c g e n e r a l l y p r e f e r a b l e to use the mean o f k c  g i v e the f o l l o w i n g method f o r approximating  It is  Mood, G r a y b i l l , and Boes (1974) the mean o f a d e r i v e d v a r i a b l e  such as k : c  a  2k  E(k ) c  k  +  c  I t i s a l s o of i n t e r e s t  h Var(k ) m  d \ 2  c  +  ->> 2 k m  3  % Var(kJ  2  a  k  2  t o know the v a r i a n c e of k , i n order t h a t c o n f i d e n c e c  l i m i t s can be e s t i m a t e d f o r E ( k ). c  Mood, G r a y b i l l , and Boes (1974) g i v e the  f o l l o w i n g as an e s t i m a t e o f the v a r i a n c e o f k :  c V a r ( k ) ^=  \  k  m  | /  Var(k ) m  +  w  c  Var(k ) f  \<5k  10 T h i s method of e s t i m a t i n g the mean and v a r i a n c e of a d e r i v e d v a r i a b l e , f ( x ) , depends upon expanding the approximation Taylor series curves of k  m  The  depends upon the magnitude of the remainder  (Johnson versus k  of k^ between 0.3  f ( x ) i n a T a y l o r s e r i e s about E ( x ) .  c  and Kotz  1969).  accuracy of  term i n the  As can be seen from F i g u r e 1, the  c o u l d be e a s i l y e s t i m a t e d by a T a y l o r s e r i e s a t v a l u e s  and 0.7,  s i n c e the curves are c l o s e to b e i n g l i n e a r .  Figure  2 shows t h a t the same h o l d s f o r curves of k,. v e r s u s k at v a l u e s of k between f c m 0.3  and 0.7.  Thus, I would conclude  these approximations  if  t h a t i t would.be q u i t e r e a s o n a b l e  and k^ are both between 0.3  The r e q u i r e d p a r t i a l d e r i v a t i v e s are g i v e n below:  and  0.7.  to use  FIGURE 1  The relationships between k and k at various values of k . c  m  f  12  FIGURE 2  The relationships between k and k at various values of k f  15  The d i f f e r e n c e between  and E ( k ) c  mal p l a c e ) and consequently k  c  I  s  u s u a l l y q u i t e s m a l l ( i n the t h i r d  f o r most purposes  deci-  i t would be s a t i s f a c t o r y t o use  i n p l a c e of E(k ). c The  suggested  phenomenon c a l l e d i n s t a b i l i t y by Sandler and H i r a i z u m i (1960a) has t o some ( M i k l o s and  Smith-White 1971)  t h a t p o s s i b l y other problems  are a s s o c i a t e d w i t h u s i n g k as a measure of the degree of  Sandler and H i r a i z u m i (1960a) noted such as SD-5 0.99)  and  t h a t unrecombined  chromosomes,  SD-72, i n v a r i a b l y had v e r y h i g h mean k v a l u e s  as w e l l as v e r y s m a l l v a r i a n c e s of k.  chromosomes had  distortion.  Because these unrecombined  s m a l l v a r i a n c e s , they were c a l l e d  bw-bearing SD recombinants, were found to have lowered  (approximately  d e r i v e d from SD/cn bw  stable.  However, whenever  females, were t e s t e d , they  mean k v a l u e s , the lowest of these b e i n g about  In a d d i t i o n , these recombinants  always had  i n c r e a s e d v a r i a n c e s of k,  and  a c c o r d i n g l y were c a l l e d e i t h e r s e m i s t a b l e or u n s t a b l e , depending upon g r e a t the v a r i a n c e of k was. than s e m i s t a b l e  U n s t a b l e l i n e s always had  0.82.  how  lower mean k v a l u e s  lines.  Sandler and H i r a i z u m i (1960a) a l s o observed combinants, d e r i v e d from SD/cn bw  t h a t i f the c n - b e a r i n g r e -  females, were made heterozygous  with  bw-  b e a r i n g s e m i s t a b l e recombinants,  then the s e m i s t a b l e recombinant  U n s t a b l e bw-bearing recombinants  c o u l d be made more s t a b l e i n t h i s manner, but  c o u l d not be made c o m p l e t e l y  stable.  became s t a b l e .  These o b s e r v a t i o n s suggested  to these  authors  One  t h a t a s t a b i l i z e r o f jSD was l o c a t e d i n 2R.  r a t h e r p e r p l e x i n g o b s e r v a t i o n was t h a t by s e l e c t i n g males w i t h low k  v a l u e s a s e m i s t a b l e l i n e c o u l d be made u n s t a b l e and the mean k c o u l d be r e duced, but by s e l e c t i n g males w i t h h i g h k v a l u e s an u n s t a b l e l i n e c o u l d n o t be made s e m i s t a b l e .  However, s e l e c t i o n f o r o n l y one g e n e r a t i o n was e f f e c t i v e i n  e i t h e r s l i g h t l y i n c r e a s i n g or s l i g h t l y d e c r e a s i n g the mean k v a l u e s of an uns t a b l e l i n e , depending upon the d i r e c t i o n o f s e l e c t i o n .  Sandler and H i r a i z u m i (1960a) reasoned showed some evidence  of h e r i t a b i l i t y  t h a t , s i n c e male v a r i a t i o n i n k  f o r one g e n e r a t i o n , s e l e c t i o n f o r h i g h k  v a l u e s should have made an u n s t a b l e l i n e s e m i s t a b l e . not produce t h i s e f f e c t , they suggested l i n e s have a h i g h mutation  Because s e l e c t i o n c o u l d  t h a t the h i g h k " s t a t e s " of u n s t a b l e  r a t e back to low k " s t a t e s " .  That  i s , although a  number of g e n e t i c m o d i f i e r s may combine i n a male t o produce a h i g h l e v e l of d i s t o r t i o n i n t h a t male, the m o d i f i e r s c o u l d n o t m a i n t a i n s e l e c t e d , because they mutated, a t a high' frequency, did  not c o n t r i b u t e to a high l e v e l of d i s t o r t i o n .  t h e i r e f f e c t when  t o an a l l e l i c  state that  I assume t h a t t h e i r model  i m p l i e s t h a t s e l e c t i o n was e f f e c t i v e i n the o p p o s i t e d i r e c t i o n because there were c e r t a i n a l l e l i c  s t a t e s of the m o d i f i e r s p r e s e n t  p o p u l a t i o n s t h a t mutated a t a v e r y low frequency of  i n the cn bw and  and d i d not enhance the degree  distortion.  Sandler and H i r a i z u m i (1960a) made i t q u i t e c l e a r t h a t they c o u l d conc e i v e of two p o s s i b l e r o l e s o f the s t a b i l i z e r t h a t were c o n s i s t e n t w i t h data.  One r o l e would be simply t o i n c r e a s e the degree of d i s t o r t i o n a s s o c i a t -  ed w i t h any g i v e n SD s t a t e .  T h i s would cause s t a b i l i z a t i o n because almost a l l  s t a t e s would then have k v a l u e s of 1.0 and consequently o p p o r t u n i t y f o r male to male v a r i a t i o n . is  their  to decrease  the mutation  there would be no  The other p o s s i b l e r o l e they  r a t e to the lower k s t a t e s .  suggest  T h i s would r e s u l t i n  an accumulation  of males w i t h h i g h k states'.  v i o u s paragraph,  However, as I s t a t e d i n the p r e -  I f e e l t h a t i n order t o e x p l a i n the s e l e c t i o n o f an u n s t a b l e  l i n e from a s e m i s t a b l e l i n e t h e r e must e x i s t c e r t a i n a l l e l i c m o d i f i e r s t h a t do not mutate and do n o t enhance k. the s t a b i l i z e r operated by p r e v e n t i n g mutation l i n e s should have bimodal k d i s t r i b u t i o n s .  forms o f the  I f t h i s were the case and  t o low k s t a t e s , then  S i n c e they do n o t , t h i s l a s t  s i b l e r o l e f o r the s t a b i l i z e r i s n o t c o n s i s t e n t w i t h the d a t a  M i k l o s and Smith-White (1971) have c r i t i c i z e d and  Sandler  stable pos-  available.  the h y p o t h e s i s o f H i r a i z u m i  (1960a) on the grounds t h a t i t " i n v o l v e s the i n t r o d u c t i o n of new  concepts; o f jSD s t a t e s , SD-state mutation, t h i s mutation".  and a s t a b i l i z e r which c o n t r o l s  As an a l t e r n a t i v e to these new concepts, M i k l o s and Smith-  White (1971) propose a model t h a t p r e d i c t s i n c r e a s i n g v a r i a n c e s of k w i t h dec r e a s i n g mean v a l u e s o f k, i n the range of k's observed by Sandler and Hiraizumi  (1960a).  Acceptance  o f t h i s model a l s o r e q u i r e s t h a t one accept  t h a t mean k i s a d e c e p t i v e measure o f the degree o f d i s t o r t i o n o f a g i v e n T h i s i s why t h i s model i s b e i n g examined i n t h i s  line.  chapter.  B e f o r e p r o c e e d i n g t o d e s c r i b e the model, I should p o i n t out t h a t the model does not i n any way attempt  t o e x p l a i n the p e r t i n e n t o b s e r v a t i o n s o f  Sandler and H i r a i z u m i (1960a) t h a t l e d them to h y p o t h e s i z e 'SD s t a t e o f SiD s t a t e mutations  The  concept  i s the o n l y r e a l l y n o v e l concept  and  Smith-White s h o u l d have c r i t i c i z e d .  The concept  should n o t be c o n s t r u e d as b e i n g n o v e l . and H i r a i z u m i (1960a),  mutations. that Miklos  o f SD s t a t e s i t s e l f  The term _SD s t a t e , as used by Sandler  i s s u r e l y meant t o imply t h e p o t e n t i a l  distorting  a b i l i t y of a g i v e n male, depending upon t h a t males genotype w i t h r e s p e c t t o the m o d i f i e r s of SD.  A l s o , one cannot  criticize  e n t i r e model on t h e b a s i s of the proposed the frequency  of mutation  Sandler and H i r a i z u m i ' s  r o l e o f the s t a b i l i z e r i n r e d u c i n g  t o lower k s t a t e s , s i n c e an a l t e r n a t i v e r o l e f o r the  s t a b i l i z e r was c l e a r l y proposed, t h a t i s , i n c r e a s i n g the k v a l u e states.  This leaves  o n l y the concept o f SD s t a t e mutation t o be c r i t i c i z e d .  SD s t a t e m u t a t i o n was proposed i n order semistable  l i n e c o u l d be made u n s t a b l e  not be made s e m i s t a b l e discuss  by s e l e c t i o n .  t h i s issue at a l l ,  t o e x p l a i n the o b s e r v a t i o n  that a  by s e l e c t i o n , b u t an u n s t a b l e Miklos  line  could  and Smith-White (1971) do n o t  i n s t e a d they c o n c e n t r a t e  r e l a t i o n s h i p between mean k and the v a r i a n c e  Miklos  o f a l l SD  s o l e l y on d e s c r i b i n g the  o f k.  and Smith-White (1971) use the concept o f "make" i n d e v e l o p i n g  t h e i r model.  T h i s concept i s o u t l i n e d i n Rendel's  development o f s c u t e l l a r b r i s t l e s .  (1967) a n a l y s i s o f the  Rendel d e f i n e d make (m) as the r e s u l t a n t  of a l l f a c t o r s l e a d i n g t o the development o f a s c u t e l l a r b r i s t l e .  The u t i l i t y  of such a concept i s t h a t i t f o r c e s one's a t t e n t i o n upon the r e s u l t a n t , and i n so d o i n g does n o t r e q u i r e unnecessary s p e c u l a t i o n about the magnitude o f v a r i a b l e s t h a t one cannot measure.  Miklos  and Smith-White (1971) d e f i n e make  as the " t o t a l l e v e l o f a l l systems l e a d i n g t o the e x t i n c t i o n 'of S D zygous males".  The p r o p o r t i o n  i s r e l a t e d t o k as f o l l o w s : t i o n or n o n - e x t i n c t i o n  of S D  of SD  +  sperm t h a t f a i l  e = 2 - (^). . +  They f u r t h e r r e a s o n t h a t  "Extinc-  i n v o l v e s a l t e r n a t i v e r e s p o n s e s , and t h e r e f o r e point.  This  i s denoted P, and the e x t i n c t i o n c o e f f i c i e n t measures the p r o p o r t i o n  of gametes i n which m exceeds P".  However, i t would appear t h a t they have not  used the term make as Rendel (1967) proposed t h a t i t should they have r e s o l v e d threshold  i n hetero-  t o f u n c t i o n , c a l l e d e,  there must be some l e v e l of m which a c t s as a t h r e s h o l d or s w i t c h threshold  +  be used, because  two f a c t o r s c o n t r i b u t i n g t o sperm d y s f u n c t i o n , make and  o f make.  They next assume t h a t the make v a l u e s  o f the sperm w i t h i n a g i v e n male  are n o r m a l l y d i s t r i b u t e d and t h a t the t h r e s h o l d s male do n o t v a r y .  o f make o f a l l sperm w i t h i n a  (The l a t t e r assumption I f i n d r a t h e r d i f f i c u l t  t o accept.  T h i s p o i n t w i l l be returned•'to l a t e r . ) coefficient  Given these assumptions the e x t i n c t i o n  i s d e f i n e d by:  I f one measures P i n standard d e v i a t i o n u n i t s from the mean, then one can d e a l w i t h a normal d i s t r i b u t i o n w i t h  a mean o f zero and a standard d e v i a t i o n of  one.  I.e.  -h m^ e  \  S, P-m  / yjr-  dm .  See F i g u r e 3 f o r a diagram showing the r e l a t i o n s h i p between  P-m e and Q, . m  One can see t h a t i f e v a r i e s between males, then the b e s t v a r i a b l e „ — P-m f o r measuring t h i s v a r i a t i o n w i l l be i . e . , the number o f standard d e v i a nt — P-m t i o n s o f P from the mean o f the make d i s t r i b u t i o n . The v a l u e -pycan be ^m c a l l e d m', the make l e v e l of an i n d i v i d u a l male. I f m' v a l u e s between males a r e assumed t o have a normal d i s t r i b u t i o n , then one can examine the d i s t r i b u t i o n of k v a l u e s between males a t d i f f e r e n t  mean k v a l u e s , w h i l e m a i n t a i n i n g the v a r i a n c e o f m' c o n s t a n t . e a s i e r , however, t o j u s t examine the v a r i a n c e o f k. v a r i a n c e o f m' a r e approximately  I t w i l l be  The v a r i a n c e of k and the  r e l a t e d as f o l l o w s :  Var k = (dk/dm') Var m' 2  where dk/dm' = k  1 e ^  2  m  i 2 ^  .  The r e l a t i o n s h i p between dk/dm' and mean k i s  STfr shown i n F i g u r e 4. i s reduced  t h a t the v a r i a n c e of k w i l l  i n c r e a s e as k  to 0.77, then the v a r i a n c e o f k w i l l b e g i n t o decrease  should note here sampling  I t i s apparent  t h a t these v a r i a n c e s do n o t take i n t o account  variance.  again.  binomial  One  FIGURE 3  The relationships between the distribution of make values within a male (m), the threshold of dysfunction (P), the proportion of SD  +  sperm that dysfunction (e), and the make level of a male (m ). 1  Make (m) is measured in standard deviations from the mean of the distri bution.  T2  22  FIGURE 4  The relationship between dk/dm and mean k. 1  E  24 M i k l o s and Smith-White (1971) proposed  t h i s model i n order t o d e s c r i b e  the i n c r e a s e d v a r i a b i l i t y of bw-bearing SD recombinants, combined £>D l i n e s , without  as compared t o unre-  the n e c e s s i t y o f h y p o t h e s i z i n g mutable _SD s t a t e s .  However, Sandler and H i r a i z u m i (1960a)  d i d n o t h y p o t h e s i z e mutable &D s t a t e s  i n order to d e s c r i b e the i n c r e a s e d v a r i a b i l i t y o f bw-bearing SD r a t h e r they were h y p o t h e s i z e d  i n order t o e x p l a i n the o b s e r v a t i o n t h a t un-  s t a b l e l i n e s c o u l d not be made s e m i s t a b l e by s e l e c t i o n . (1960a) had a l r e a d y proposed  recombinants,  Sandler and H i r a i z u m i  a p e r f e c t l y r e a s o n a b l e h y p o t h e s i s t o e x p l a i n the  i n c r e a s e d v a r i a b i l i t y o f bw-bearing SD recombinants.  T h i s h y p o t h e s i s was t h a t  the s t a b i l i z e r o f SD operated by simply i n c r e a s i n g the k v a l u e s o f a l l SD states. lowered  When the s t a b i l i z e r was absent  the k v a l u e s of a l l JSD s t a t e s would be  so t h a t v a r i a b i l i t y between the s t a t e s c o u l d then be observed.  I t i s c l e a r l y o f importance acceptance  t o choose between these two hypotheses,  since  o f M i k l o s and Smith-White's h y p o t h e s i s r e q u i r e s t h a t one should  measure k as m'.  In order t o make a c h o i c e one must f i r s t examine the weak  p o i n t s o f these hypotheses. White's assumption  I n t h i s r e s p e c t , I f e e l t h a t M i k l o s and Smith-  t h a t the t h r e s h o l d s of m w i t h i n a male a r e c o n s t a n t , w h i l e  m may v a r y n o r m a l l y , i s d e f i n i t e l y suspect.  I cannot  t h i n k o f any a_ p r i o r i  reason why the t h r e s h o l d s of m s h o u l d be any l e s s v a r i a b l e than m.  Since  t h e r e i s no way o f measuring e i t h e r P o r m, a t p r e s e n t , i n order t o e v a l u a t e the g e n e r a l i t y o f the model one should ask: what a r e the e f f e c t s o f P v a r y i n g w i t h i n males?  I f the v a r i a n c e o f P equaled  the v a r i a n c e of m, as i n F i g u r e 5,  then one can see i n t u i t i v e l y t h a t the v a r i a n c e of k w i l l be s m a l l e s t a t k e q u a l t o 0.5, but w i l l be g r e a t e s t c l o s e t o a k of 1.0.  However, a t some  p o i n t c l o s e t o 1.0 a c e r t a i n p r o p o r t i o n o f males w i l l have k e q u a l t o e x a c t l y 1.0,  i . e . a l l m a r e g r e a t e r than P.  T h i s t r u n c a t i o n e f f e c t w i l l b e g i n to r e -  duce the v a r i a n c e o f k a g a i n as mean k approaches 1.0.  N e v e r t h e l e s s , the way  i n which v a r i a n c e o f k changes w i t h mean k w i l l be c o n s i d e r a b l y d i f f e r e n t i f  FIGURE 5  A model similar to Miklos and Smith-White's, except P is allowed to vary and ^  equals (f^. The units on the abscissa are standard  deviations of m from the mean of each distribution.  one  relaxes  the assumption t h a t P i s c o n s t a n t .  the r e l a t i o n s h i p between k amd m', as d e f i n e d  In a d d i t i o n , i f P v a r i e s , then by M i k l o s and Smith-White (1971) ,  w i l l be a l t e r e d .  In the remainder of t h i s chapter I w i l l p r e s e n t some r e s u l t s from l a r g e s c a l e experiments t h a t demonstrate how the v a r i a n c e and  then I w i l l  o f k i s r e l a t e d t o mean k  compare these r e s u l t s w i t h p r e d i c t i o n s made by the model of  M i k l o s and Smith-White (1971) as w e l l as w i t h p r e d i c t i o n s made by a model I s h a l l d e v e l o p , based on my i n t e r p r e t a t i o n of Sandler and H i r a i z u m i ' s discussion of i n s t a b i l i t y .  (1960a)  28 MATERIALS AND METHODS  The d i s t r i b u t i o n  of s e g r e g a t i o n r a t i o s o f s i x d i f f e r e n t  types o f SD  second chromosomes were determined when the chromosomes were heterozygous w i t h a cn bw chromosome.  A l l s i x chromosomes were o r i g i n a l l y m a i n t a i n e d as b a l a n c e d  s t o c k s over In(2LR)SMl,Cy, and G r e l l 1968). different  an e f f e c t i v e b a l a n c e r f o r chromosome 2 (see L i n d s l e y  In o r d e r t o approximate i s o g e n i c backgrounds  between the  s t o c k s , a l l o f the b a l a n c e d l i n e s were b a c k c r o s s e d as males t o cn bw/ :  cn bw females f o r f o u r g e n e r a t i o n s .  A f t e r the f o u r t h b a c k c r o s s g e n e r a t i o n  males t h a t were from two to f o u r days o l d were c o l l e c t e d t h a t were homozygous f o r the g e n e t i c markers,  and mated t o females  cn bw; K i pP bx s r e . s  these females were homozygous f o r K i pP bx s r e , one c o u l d e a s i l y s  a white-eyed S D  +  f l y , which would be heterozygous f o r K i p  white-eyed f l y t h a t arose from a n o n - v i r g i n  p  Since  distinguish  bx s r e , from a s  female.  S i n g l e "SD"/cn bw males were p l a c e d w i t h two homozygous cn bw; K i pP bx sr e  s  v i r g i n females i n s h e l l v i a l s c o n t a i n i n g s t a n d a r d D r o s o p h i l a medium.  The p a r e n t s were l e f t  i n the v i a l s f o r f o u r days and then d i s c a r d e d .  geny were s c o r e d 12 t o 13 days l a t e r . 24+1  The p r o -  The temperature was m a i n t a i n e d a t  C dur i n g the experiment.  The m o d i f i e d SD_ chromosomes used were d e r i v e d from SD mapping experiments t h a t w i l l be d e s c r i b e d i n the next c h a p t e r .  The f o l l o w i n g £>D chromosomes were  examined: 1.  SD-5, an unrecombined  SD chromosome.  2.  R(SD-5) pk cn, a recombinant  o f SD-5 w i t h almost a l l o f 2R r e p l a c e d  by the r i g h t arm o f a b pr I t pk cn chromosome.  This  recombinant  s h o u l d have l o s t the s t a b i l i z e r o f Sandler and H i r a i z u m i 3.  (1960a).  D f ( 2 L ) ( S D - 5 ) - 8 , a 2L h e t e r o c h r o m a t i c d e f i c i e n c y on SD-5 f o r Group  VIII  ( I t ) and the Group V I I s i t e  i n c l u d i n g EMS 56-4 (see H i l l i k e r  1976) . RR(SD-5)It,  a double recombinant  of SD-5 i n which the c e n t r o m e r i c  h e t e r o c h r o m a t i n of SD-5 was r e p l a c e d by t h a t o f the b p r I t pk cn chromosome. R(SD-5) b p r - 5 , a recombinant  d e r i v e d from SD-5 and b p r I t pk cn.  RR(SD-5) p r I t , a double recombinant  of SD-5 and b pr I t pk cn.  RESULTS AND DISCUSSION  The  observed  frequency  d i s t r i b u t i o n s of k f o r the s i x d i f f e r e n t "SD"  chromosomes a r e shown i n F i g u r e 6.  I t i s apparent t h a t as mean k  decreases  the v a r i a n c e o f k i n c r e a s e s f o r the f o u r chromosomes w i t h mean k above 0.5 and then  the v a r i a n c e of k again decreases  Sandler operate  and H i r a i z u m i  i s by simply  f o r the two low k chromosomes.  (1960a) suggested  t h a t one way the s t a b i l i z e r might  i n c r e a s i n g the k of a l l SD s t a t e s such t h a t most s t a t e s  would then have k's of 1.0 and thus v a r i a b i l i t y would n o t be observed. o r d e r to examine t h i s p r o p o s a l more c a r e f u l l y , I s h a l l develop  In  i t quantita-  tively.  One can s t a r t by assuming t h a t a number o f m o d i f i e r s of d i s t o r t i o n , g e n e t i c and e n v i r o n m e n t a l ,  both  a c t i n such a way t h a t the p o t e n t i a l k's o f a g i v e n  p o p u l a t i o n o f males w i l l be n o r m a l l y  distributed.  Furthermore, assume t h a t  t h i s d i s t r i b u t i o n of p o t e n t i a l k's i s u n a f f e c t e d by changes i n mean k.  This  w i l l undoubtedly n o t be t r u e as mean k approaches 0.5, because when mean k e q u a l s 0.5, SD i s n o t o p e r a t i n g and one would riot expect have any e f f e c t upon the p o t e n t i a l s e g r e g a t i o n r a t i o . k's  another  Sandler  m o d i f i e r s o f SD t o  However, at h i g h mean  f a c t o r comes i n t o p l a y , and i t i s t h i s f a c t o r which I b e l i e v e  and H i r a i z u m i  (1960a) a l l u d e d t o . S i n c e the v a r i a n c e o f p o t e n t i a l  s e g r e g a t i o n r a t i o s i s u n a f f e c t e d by mean k, at h i g h mean k's a c e r t a i n  per-  centage of the males w i l l have p o t e n t i a l s e g r e g a t i o n r a t i o s g r e a t e r than o r e q u a l t o 1.0.  C l e a r l y a l l p o t e n t i a l s e g r e g a t i o n r a t i o s g r e a t e r than or e q u a l  to 1.0 should be p l a c e d t o g e t h e r  i n t o one group w i t h a p o t e n t i a l  r a t i o o f 1.0 i . e . no chance of r e c o v e r i n g an S D normal d i s t r i b u t i o n o f p o t e n t i a l k v a l u e s .  +  sperm.  segregation  T h i s t r u n c a t e s the  As the mean o f the untruncated  d i s t r i b u t i o n i n c r e a s e s , a g r e a t e r percentage o f the p o p u l a t i o n f a l l s i n t o the  FIGURE 6  The observed k distributions of the 6 "SD" chromosomes tested The unit of measurement on the ordinate is the percentage of males having k's within a given interval.  The unit of the abscissa is k  k interval is 0.03. n = the number of males tested H = the harmonic mean number of males n  = the unweighted mean of k's of all the males &> •= the standard deviation of the k's  32  9070-  n = 1148  H =.985  H =61.3  CT =.022  n  cn  R(SD-5)pk  SD-5  100-i  k  n =1156  40H  H -"60.4  k  n  r.932  (T = k  056  30-1 5020-J 30-  10^ 10-  o+  .9 1j0  Df(2L)(SD-5)-8  25-1 20-  15-  J  .3  0 .1  JJ =.879  H =65.2  =.067  n  5-^  5H  .7  .3  >V  H =70.5  .  n  h  15H  = .713  "k  <r =.n8 k  HrH~n I .9 1.0  R(SD"5)bpr-5  n = 825  20-  11=1142  H =55.8  1510J  25-4  RR(SD-5)lt  20H  k  10H  0 .1  9 1.0  25n  n*1143 n  yt-rffl T"  0 .1  n = 1145  20-  (JT =.064  k  15-  10H  .9  1.0  T9  ilo  R R ( S D - 5 ) p r If  25.506  I  .7  0 .1  Mk  .463  H -55.2 n  105-  0-T—r  0 .1  .3  •5  .7  !I  i*.o  0 .1  tk  t r u n c a t e d p o r t i o n and tribution.  t h i s i n t u r n reduces the v a r i a n c e of the t r u n c a t e d  Thus, on t h i s model the s t a b i l i z e r i s o n l y a s t r o n g  m o d i f i e r of  t h a t s h i f t s up  the m a j o r i t y are t r u n c a t e d at  T h i s model p r e d i c t s  1.0.  that p o t e n t i a l  i n t o account when o b s e r v i n g a c t u a l  However, observed  distributions  In order to check i f the p o t e n t i a l  Rohlf  (1969).  s e g r e g a t i o n r a t i o s w i l l be  component to t h e i r d i s t r i b u t i o n s  normal d i s t r i b u t i o n s  one  can use  and  t h i s must be  been m o d i f i e d  The  i n d i v i d u a l k v a l u e s were ranked from the  of o b s e r v a t i o n s was  s u b j e c t e d to the i n v e r s e normal i n t e g r a l  these v a l u e s were i n d i v i d u a l l y p l o t t e d  The p o i n t s were then j o i n e d a PDP  11 computer.  structed  The  by s t r a i g h t  lines.  versus  t h a t k was  I have h y p o t h e s i z e d  transformation  performed  on  F i g . - 8' shows graghs con-  measured as a r c s i n Vk The  mation i s e f f e c t i v e i n n o r m a l i z i n g a b i n o m i a l d i s t r i b u t i o n .  nent.  lowest  t h e i r r e s p e c t i v e k's.  to attempt to remove the e f f e c t s of b i n o m i a l sampling.  are a mixture  has  by the t o t a l number  A l l of t h i s was  graphs are shown i n F i g u r e 7.  i n the same manner, except  distributions  transformation  For the p r e s e n t purposes, t h i s technique  then the q u o t i e n t of the rank d i v i d e d  then  Such a  l i n e i f the d i s t r i b u -  to the h i g h e s t , and  and  and  I f , i n s t e a d of cumula-  then the p l o t w i l l f o l l o w a s t r a i g h t  somewhat.  by S o k a l  the mean v a l u e of the i n t e r v a l .  t i v e f r e q u e n c i e s of s u c c e s s i v e i n t e r v a l s , one uses the p r o b i t  distributed.  ratios.  f r e q u e n c i e s of s u c c e s s i v e  p l o t w i l l be s-shaped i f the d i s t r i b u t i o n i s normal.  t i o n i s normally  taken  segregation r a t i o s follow truncated  a s e m i g r a p h i c a l method o u t l i n e d  i n t e r v a l s of a d i s t r i b u t i o n v e r s u s  distributed  s e g r e g a t i o n r a t i o s have  of s e g r e g a t i o n  T h i s i n v o l v e s p l o t t i n g the cumulative  of t h a t frequency,  positive  the d i s t r i b u t i o n of p o t e n t i a l k v a l u e s such t h a t  as t r u n c a t e d normal d i s t r i b u t i o n s . a b i n o m i a l sampling  dis-  of a b i n o m i a l component, and  angular  i n order transfor-  However, these  a b i o l o g i c a l compo-  t h a t the b i o l o g i c a l component f o l l o w s a t r u n c a t e d  k  FIGURE 7  A diagrammatic test for normality of the k distributions of the 6 "SD_" chromosomes tested.  The unit on the ordinate is standard  deviations and the unit on the abscissa is k.  35  +4n  +4T  RfSD-5)pk cn  SD-5 + 2-  -2H  -2H  -1  H .2  1.0  f  + 4-  1 4  1 .6  1 .8  1 1.0  4-1  RRfSD-5) /f  Df(2t)(SD-5)-8 + 2H  + 2-  OH  -2H  2H  -  4-  + 4-  -4  -T  .2  R(SD-5)b pr-5  +  + 2-  10  .6  1.0  4 T  RR(SD-5)pr /f  + 2H  OH  -2H  -4-  -2H  T  .2  .4  -1  1.0  -4-  .8  1.0  36  FIGURE 8  A diagrammatic test for normality of the distributions of arc sin  of the 6 "SD" chromosomes tested.  The unit on the ordinate  is standard deviations and the unit on the abscissa is arc s i n V T .  37 + 4-|  +4  R(SD-5)pk cn  SD-5 + 2H  +2-  oH  OH  •2H  -2H  20  40  60  -4-  80  20  90  + 4-i  90  + 2H  OH  OH  -2H  -2H -4-  20  40  60  80  90  R(SD-5)b -5  20  + 4-,  p r  + 2H  1  -1  40  RR(SD-5)pr  60  1 — 1  80  90  It  + 2H  OH  OH  2H  -4.  80  RR(SD-5)/f  + 2H  + 4-t  60  + 4.  Df(2L)(SD-5)-8  •4 + 0  40  -2H  r  20  4 0  60  80  90  -4-  20  40  60  "~I 80  1  90  38 normal d i s t r i b u t i o n .  Because the angular  t r a n s f o r m a t i o n i s a p p l i e d to the  h y b r i d d i s t r i b u t i o n , i t w i l l o n l y be approximately e f f e c t s of binomial  sampling.  The d i s t r i b u t i o n s  8 a r e t r u n c a t e d normal d i s t r i b u t i o n s . sis  of a r c s i n >/k shown i n F i g u r e  These o b s e r v a t i o n s  t h a t the b i o l o g i c a l component of v a r i a t i o n  t r i b u t i o n , b u t the support  should n o t be c o n s i d e r e d  t r a n s f o r m a t i o n i n t h i s case.  support  the hypothe-  f o l l o w s a t r u n c a t e d normal d i s -  of the p r e v i o u s l y mentioned r e s e r v a t i o n s c o n c e r n i n g angular  e f f e c t i v e i n removing the  t o be too s t r o n g , because the e f f e c t i v e n e s s of the  From F i g u r e 8 i t i s a l s o apparent t h a t  the s l o p e s o f the r e s o l v e d p o r t i o n s o f the d i s t r i b u t i o n s  of the f o u r "SD"  s t o c k s w i t h mean k's above 0.5 a r e approximately  Although  tempted t o suggest potential  equal.  one might be  t h a t t h i s i n d i c a t e s t h a t the v a r i a n c e s of the untruncated  k distributions  o f the f o u r "SD" s t o c k s w i t h k's above 0.5 a r e  e q u a l , I would h e s i t a t e to do s o , a g a i n because o f r e s e r v a t i o n s c o n c e r n i n g the e f f i c a c y o f the angular sampling  t r a n s f o r m a t i o n i n removing the e f f e c t s o f b i n o m i a l  from an observed  k distribution.  From the d i s t r i b u t i o n s to assume t h a t the p o t e n t i a l normal d i s t r i b u t i o n s .  shown i n F i g u r e 8, i t i s n o t a t a l l unreasonable s e g r e g a t i o n r a t i o s approximately  follow truncated  I f t h i s assumption i s made, then one can determine  whether or n o t t r u n c a t i o n alone  can account f o r changes i n the observed  ance o f k between the "SD" s t o c k s w i t h mean k g r e a t e r than 0.5. potential  s e g r e g a t i o n r a t i o o f a male.  served s e g r e g a t i o n r a t i o k.  Binomial  sampling  vari-  L e t j be the  from j g i v e s the ob-  The v a r i a b l e j has a normal d i s t r i b u t i o n :  Since j i s an a b s t r a c t i o n , i t can possess what seem t o be r a t h e r p e c u l i a r properties.  One o f these p e c u l i a r p r o p e r t i e s i s t h a t i t can have v a l u e s  less  than 0 or g r e a t e r than 1, exceeds 1,  as w e l l as the u s u a l range from 0 to 1.  the "more i m p o s s i b l e "  chromosome.  P r a c t i c a l l y , however, one  degrees of i m p o s s i b i l i t y . distribution, with  a f l y with  SD  +  i n a b s t r a c t terms j f o l l o w s a normal  i n p r a c t i c a l terms j f o l l o w s a t r u n c a t e d normal truncated  the  cannot d i s t i n g u i s h between d i f f e r e n t  Thus, although  the d i s t r i b u t i o n b e i n g  mine i s how  i t becomes to r e c o v e r  The more j  at 0 and  1.  distribution,  What one wishes to d e t e r -  the mean and v a r i a n c e of the t r u n c a t e d d i s t r i b u t i o n v a r y , when the  mean of the u n t r u n c a t e d  distribution  i s a l t e r e d but  t r u n c a t e d d i s t r i b u t i o n i s maintained  In order  at a c o n s t a n t  the v a r i a n c e of the  un-  value.  to s i m p l i f y the mathematics of the problem, I s h a l l t r a n s f o r m  i - &i xnto z, where z = — — —  te.  .  Now  the v a r i a b l e z w i l l  f o l l o w a normal d i s t r i b u z  3  t i o n w i t h a mean of 0 and  a standard  j  d e v i a t i o n of 1;  f(z) = e  2  .  Instead  Jrfr iof b e i n g t r u n c a t e d  at 1,  w i l l be d e s i g n a t e d  as z'*".  be determined by d i v i d i n g z*- and  t h i s d i s t r i b u t i o n w i l l be  truncated  the o t h e r p a r t g r e a t e r than z .  i n t o two  The  fc  at — — —  p a r t s , one  part less  , can than  p a r t g r e a t e r than z " w i l l , because 1  of t r u n c a t i o n , have a v a l u e of z ". The p r o p o r t i o n of the t o t a l c o n t a i n e d i n t h i s component i s g i v e n by 1  z  , which  z d i s t r i b u t i o n , /J.  The mean of the t r u n c a t e d the d i s t r i b u t i o n  Mi  distribution  2  ~2 ^  dz  Z  Thus, t h i s component w i l l  the t r u n c a t e d  contribute  z distribution.  z  e  fc  2  2 dz towards the mean of  The p a r t of the d i s t r i b u t i o n w i t h v a l u e s of z  l e s s z' w i l l c o n s t i t u t e : fc  z2  "2  e  -oo  ,  dz  =  \  Z dz  of the t o t a l d i s t r i b u t i o n .  I n order  t o c a l c u l a t e the mean o f t h i s p a r t o f the  d i s t r i b u t i o n one must d e f i n e t h i s p a r t i n such a way t h a t the area under t h i s p a r t o f the d i s t r i b u t i o n i s equal by  /  t o 1.  T h i s can be done by m u l t i p l y i n g f ( z )  -1  ^  [a.  z dz  lzI  f ( x ) dx, i f ^  .  The mean o f a d i s t r i b u t i o n  f ( x ) dx = 1.  can be g i v e n by  ^  (x) •  Thus the mean o f the p a r t of the z d i s t r i b u t i o n  l e s s than z*" i s g i v e n by: ,t z  N-l Z dz /  \  \  z • Z  dz / .  Since  this  J~ 00 t  constitutes  ^  Z dz  -00  c  zt  bution contributes distribution.  o f the t o t a l d i s t r i b u t i o n , t h i s p a r t o f the d i s t r i -  \  U-o°  z . Z  dz  towards the mean of the t r u n c a t e d z  Thus the mean o f the t r u n c a t e d  Z dz /  z d i s t r i b u t i o n i s given by:  +  t2 2 z  The  s o l u t i o n of the i n t e g r a l on the r i g h t  oo  The v a r i a n c e  the same manner, i . e . by d i v i d i n g l e s s than z  c  =  C*  3  t h i s procedure:  .t2  =  ,  therefore  __z  z distribution the d i s t r i b u t i o n  and the other p a r t g r e a t e r  r e l a t i o n s h i p O"^  -e YTTF  .t2  \  of the t r u n c a t e d  is  than z . t  f ( x ) ( x - A * ) ^ dx, where x  can be determined i n much i n t o two p a r t s , one p a r t In t h i s case one uses the f ( x ) dx = 1.  Using  One  now  knows how  meters are JU ^ = M  t t2 to c a l c u l a t e fj( and (J .  Z  CT.  fc  +  JU.  and  parameters p r e d i c t e d i n terms of j  In terms of j  3  =  .  these p a r a -  In order to compare  w i t h parameters measured i n terms of k  ' must attempt T h i s was  t o remove the e f f e c t s of b i n o m i a l sampling  from yU  and  one  2  £7^  done by e s t i m a t i n g the v a r i a n c e of a b i n o m i a l d i s t r i b u t i o n w i t h 6  equal to jU  , and  the number of progeny per v i a l  the same as i n the  observed •<r 2 experiment, and then s u b t r a c t i n g t h i s v a r i a n c e from the observed v a l u e of . t2 T h i s should g i v e an e s t i m a t e of (T. . The component of v a r i a t i o n c o n t r i b u t e d ^k (1-^k) by b i n o m i a l sampling was c a l c u l a t e d as , where H r e p r e s e n t s the H n n J  harmonic mean number of progeny per v i a l . necessary  One  f o r M^,  can now  correction  s i n c e j U ^ should e q u a l jU.'r .  compare c o r r e c t e d v a l u e s of jU ^ and t . and  2  w i t h the p r e d i c t e d  2 , g i v e n some c o n s t a n t v a l u e of CT . . One J j 3 2 choose what the v a l u e of C should be. F i g u r e s 7 and 8 show t h a t  r e l a t i o n s h i p between must now  There should be no  O  t2  RR(SD-5) l t / c n bw males had no v a l u e s of k equal to 1.0.  Since the k  distri-  2 t2 b u t i o n of these males i s not t r u n c a t e d (3 . should e q u a l 0 . . Accordingly, _,2 2 t h i s c o r r e c t e d v a l u e of O, was used as an e s t i m a t e of O . . T h i s v a l u e of 2 Cf _. was  t used t o p r e d i c t the r e l a t i o n s h i p between JU. and  the model I have proposed. curve l a b e l l e d a.  t2 (J^ a c c o r d i n g to  T h i s r e l a t i o n s h i p i s shown i n F i g u r e 9 by  the  A l s o shown i n F i g u r e 9 are the observed v a l u e s of M ^  and  2 the c o r r e c t e d v a l u e s of CT^  .  Because of the r e s u l t s shown i n F i g u r e 8, where  the s l o p e s of the r e s o l v e d p o r t i o n s of the d i s t r i b u t i o n of a r c s i n s i m i l a r f o r RR(SD-5) l t / c n bw males, Df(2L)(SD-5)-8/cn cn bw males and  SD-5/cn bw males, I expected  f o l l o w the observed  were  bw males, R(SD-5) pk  t h a t curve a i n F i g u r e 9 would  d a t a p o i n t s f o r the above males.  C l e a r l y i t does n o t .  T h i s demonstrates t h a t one must be c a u t i o u s when i n t e r p r e t i n g F i g u r e 8. Curve b of F i g u r e 9 shows the p r e d i c t i o n made by M i k l o s and  Smith-White's  cn/  FIGURE 9  The observed and predicted relationships between the variance of k (without the binomial component) and mean k. Curve a i s my prediction with C? . constant at 0.01.  Curve b i s the prediction made by 2 Miklos and Smith-White's model (1971) with 0 . = 0.27. Curve c i s m 2 my prediction with C7. = 0.047 (}Ji. - 0.5).  ^3  c ro  £  >l 10 aoueueA  (1971) model.  The  agreement between t h i s p r e d i c t i o n and  p o i n t s i s not much b e t t e r .  the observed  data  In p a r t i c u l a r , the v a r i a n c e of Df(2L)(SD-5)-8/cn  males i s f a r below the p r e d i c t i o n of e i t h e r model. .Since the v a r i a n c e mean of RR(SD-5) l t / c n bw males was the curves  i n RR(SD-5) l t / c n bw  and  used as the r e f e r e n c e p o i n t through which  of both models passed, i t i s j u s t as l i k e l y  males w i t h mean k's  bw  t h a t , as compared to  above the mean k of RR(SD-5) l t / c n bw males, the SD_ system males was  abnormally  s e n s i t i v e to m o d i f i e r s of  SD.  2 Curve a i n F i g u r e 9 was s t a n t f o r a l l v a l u e s of / U j . near 0.5  c o n s t r u c t e d on the assumption t h a t Cf ^ was  con-  However, as I p r e v i o u s l y mentioned, when >Uj i s  the E!D system i s e i t h e r not o p e r a t i n g , or o n l y o p e r a t i n g at a v e r y  low l e v e l .  Under such circumstances m o d i f i e r s of s e g r e g a t i o n d i s t o r t i o n should 2 have no e f f e c t , i . e . U . should be z e r o . The o b s e r v a t i o n s shown i n F i g u r e 9 2 support t h i s c o n t e n t i o n . Thus i t would appear t h a t CT . must i n c r e a s e as /-(_. _2 i n c r e a s e s above 0.5.  Curve a i n F i g u r e 9 i s based on the assumption that CT  does not change a f t e r i t reaches e q u a l to 0.7.  a v a l u e of 0.01  at some p o i n t l e s s than jU..  S i n c e curve a i n F i g u r e 9 does not f i t the d a t a , the  used to c o n s t r u c t i t must be i n c o r r e c t .  Perhaps the model would be  assumption improved  2 if  2  O . was  i n some manner dependent upon jU...  i s d i r e c t l y p r o p o r t i o n a l to (M j ~ 0'5),  The i.e.  s i m p l e s t assumption i s t h a t 2 Cf ^ = ( / U j C  -  0.5).  Again,  the v a r i a n c e and mean of RR(SD-5) l t / c n bw males can be used to e s t i m a t e e q u a l to 0.047.  Curve c i n F i g u r e 9 shows the p r e d i c t i o n when t h i s  i s a p p l i e d to the model used to c o n s t r u c t curve a. renders  Although  the model more r e a l i s t i c at low v a l u e s of jU^>  c as  assumption  this modification  I t does not  f i t the  o b s e r v a t i o n s any b e t t e r at h i g h v a l u e s of JJ, ^. S i n c e none of the p r e d i c t i o n s shown i n F i g u r e 9 f i t the o b s e r v a t i o n s , i t i s l i k e l y t h a t the JSD chromosomes examined i n t h i s study d i f f e r sitivities  to m o d i f i e r s of s e g r e g a t i o n d i s t o r t i o n .  in their  sen-  I f t h i s i s the case, i t  must be a consequence of the particular mutations on each of these chromosomes. In this regard, i t i s interesting to note that RR(SD-5)lt and Df(2L)(SD-5)-8 differ in that the former chromosome was constructed by recombination, while the latter chromosome bears a deficiency of the heterochromatin close to, and including, the Lt locus.  CONCLUSION  Although the d a t a o b t a i n e d  i n t h i s study  between the models I have proposed and I favour my  t h a t of M i k l o s  t i o n , but, efficacy  t h i s assumption, as shown i n F i g u r e 8.  arc s i n  k i s distributed  transformation  j f o l l o w s a t r u n c a t e d normal d i s t r i b u t i o n .  accordingly, I  of the assumption t h a t  t h a t one  point i s  c o u l d compute the  exact  d i s t r i b u t i o n of k expected f o r a t r u n c a t e d normal d i s t r i b u t i o n of j  a g i v e n d i s t r i b u t i o n of numbers of progeny per v i a l .  although  not r i g o u r o u s l y t e s t e d here,  the o t h e r hand, M i k l o s and  upon t h r e e b a s i c assumptions.  The  w i t h i n a g i v e n male a l l v a l u e s t h a t the v a l u e s of m' distribution.  The  Thus t h i s  i s at l e a s t p o t e n t i a l l y  Smith-White's first  assumption,  verifiable.  (1971) model i s p r e d i c a t e d  assumption i s t h a t the v a l u e s  w i t h i n a male f o l l o w a normal d i s t r i b u t i o n .  and  i n support  and,  the  However, the important  t h a t , g i v e n enough time, i t i s c o n c e i v a b l e frequency  F i g u r e 8 shows  as a t r u n c a t e d normal d i s t r i b u -  in this situation,  c o n s i d e r F i g u r e 8 to be r a t h e r weak evidence  direct  distribution.  as p r e v i o u s l y i n d i c a t e d , I have r e s e r v a t i o n s c o n c e r n i n g  of the angular  (1971),  segregation  ( j ) i n a p o p u l a t i o n of SD males f o l l o w a t r u n c a t e d normal  t h a t i n a l l cases  On  Smith-White  T h i s common b a s i c assumption i s t h a t the p o t e n t i a l  I attempted to t e s t  and  and  to choose  models because t h e i r common b a s i c assumption i s open to  refutation. ratios  do not enable one  The  of m  second assumption i s t h a t  of P are i n v a r i a n t .  The  t h i r d assumption i s  between males of a g i v e n p o p u l a t i o n f o l l o w a normal  first  two  assumptions cannot be  l i k e l y they never w i l l be a b l e to be  t e s t e d d i r e c t l y at  tested d i r e c t l y .  cannot a s c e r t a i n the d i s t r i b u t i o n of a v a r i a b l e l i k e m' a f f i r m s the v a l i d i t y of the v a r i a b l e , and o n l y way  to t e s t  Furthermore,  u n t i l one  I have j u s t p o i n t e d out  cannot be done.  The  t i o n s i s to t e s t  the p r e d i c t i o n s of the e n t i r e  present, one  first that  this  the v a l i d i t y of t h i s t r i a d of assumpmodel.  In support o f t h e i r model M i k l o s and Smith-White (1971) compared  calcu-  l a t e d frequency d i s t r i b u t i o n s o f k, which they generated u s i n g t h e i r model, w i t h observed  frequency d i s t r i b u t i o n s of k.  The comparison they made was i n -  c o r r e c t , however, because t h e i r p r e d i c t e d d i s t r i b u t i o n s o f k d i d n o t take  into  account b i n o m i a l sampling, w h i l e the observed' k d i s t r i b u t i o n s n e c e s s a r i l y had a b i n o m i a l component.  I f one d i s r e g a r d s t h i s gross o v e r s i g h t , i t i s apparent  from t h e i r p u b l i s h e d diagrams t h a t the observed agreed  reasonably w e l l .  and " p r e d i c t e d " d i s t r i b u t i o n s  As f u r t h e r support f o r t h e i r model, M i k l o s and Smith-  White (1971) compared the p r e d i c t e d r e l a t i o n s h i p between the standard d e v i a t i o n o f k and the mean of k w i t h the observed  relationship.  Their prediction  2 imposed another  assumption  on t h e i r model, the assumption  c o n s t a n t f o r a l l v a l u e s o f jU ^. r e l a t i o n s h i p agreed  t h a t Cf  m  , remained  From the d a t a they p r e s e n t e d , the observed  r e a s o n a b l y w e l l w i t h the p r e d i c t e d r e l a t i o n s h i p .  However,  t h e i r model, w i t h a l l f o u r assumptions, d i d not agree w i t h my o b s e r v a t i o n s , as  2 shown iri F i g u r e 9.  Thus the assumption  t h a t Cf' , remains constant i n f l i e s  w i t h s i m i l a r g e n e t i c backgrounds i s n o t g e n e r a l l y v a l i d .  Proof f o r the  v a l i d i t y o f t h e i r model must r e s t on p r e d i c t i o n s made by the o r i g i n a l t r i a d o f assumptions.  T h i s b o i l s down t o comparing observed  d i s t r i b u t i o n s of k with  p r e d i c t e d d i s t r i b u t i o n s o f k and as I have a l r e a d y p o i n t e d out, they f a i l e d t o do t h i s  adequately.  Because my model has o n l y one b a s i c assumption, White's simpler.  (1971) model has t h r e e b a s i c assumptions, F o r t h i s reason, f u r t h e r experiments  w h i l e M i k l o s and Smith-  my model i s i n h e r e n t l y  should c o n c e n t r a t e upon  i n g to r e f u t e my h y p o t h e s i s , i n p r e f e r e n c e t o M i k l o s and Smith-White's. c o u l d be adequately v e r i f i e d  attemptIf i t  t h a t j f o l l o w s a t r u n c a t e d normal d i s t r i b u t i o n ,  2 then one c o u l d c o n f i d e n t l y examine changes o f Cf .. between d i f f e r e n t SD s t o c k s and t h i s might enable one to use fj.  as a measure o f d i s t o r t i o n , i n l i e u o f k.  However, a t p r e s e n t , not enough i s known about d i s t r i b u t i o n s o f k i n order t o  justify any measure of distortion other than k. I w i l l use either k or k  Accordingly, in what follows  as the measure of distortion.  CHAPTER II ON THE LOCATION AND PROPERTIES OF SOME OF THE LOCI AFFECTING SEGREGATION DISTORTION  50 INTRODUCTION  To i n t r o d u c e the r e a d e r to my  r e s u l t s on the l o c a t i o n of some of the  components of the SD system, I s h a l l f i r s t  d i s c u s s the r e s u l t s of H a r t l  s i n c e h i s experiments have a v o i d e d some of the c o m p l i c a t i o n s that had ed  e a r l i e r studies  examined  on t h i s t o p i c  the p r o p e r t i e s  females.  ( H a r t l and H i r a i z u m i 1976).  into three classes  were: 1) i n s e n s i t i v e d i s t o r t e r s  distorters. c l a s s was  (unrecombined  2) i n s e n s i t i v e n o n d i s t o r t e r s ,  The cn recombinants a l s o  fell  These  The r e -  three  chromosomes are i n and  3) s e n s i t i v e  i n t o three c l a s s e s .  composed of i n s e n s i t i v e d i s t o r t e r s .  were s e n s i t i v e n o n d i s t o r t e r s .  0.95.  based on t h e i r a b i l i t y to d i s -  t o r t cn__bw and t h e i r s e n s i t i v i t y to another J3D chromosome.  sensitive distorters),  (1974)  s p e c i f i c a l l y chosen as i t c a r r i e s no  The k v a l u e of R ( S D - 3 6 ) - l / T f t cn males was  combinants b e a r i n g T f t f e l l  classes  confound-  of recombinants r e c o v e r e d from R ( S D - 3 6 ) - l / T f t cn  The T f t cn chromosome was  s u p p r e s s o r s of SD.  Hartl  (1974),  The  The second and t h i r d  These s e n s i t i v e n o n d i s t o r t e r s  non-  first classes  c o u l d be  further  s u b d i v i d e d depending upon t h e i r response to the i n s e n s i t i v e n o n d i s t o r t e r recombinants. tained Tft  One  c l a s s of the s e n s i t i v e n o n d i s t o r t e r  cn recombinants con-  chromosomes t h a t were themselves d i s t o r t e d by i n s e n s i t i v e  recombinants.  Tft  The chromosomes of the o t h e r c l a s s of s e n s i t i v e  cn recombinants were not d i s t o r t e d by the i n s e n s i t i v e n o n d i s t o r t e r  nondistorter nondistorter T f t recom-  binants .  These r e s u l t s suggest that  two _SD l o c i are l o c a t e d  One of these i s c a l l e d Sd_ and i s l o c a t e d ed Rsp  (Responder).  A Rsp  +  +  have a Sd_ a l l e l e ,  to the l e f t o f the second l o c u s  call-  a l l e l e responds to a £>d a l l e l e , r e s u l t i n g i n the  d y s f u n c t i o n of sperm b e a r i n g R s p . not  between T f t and cn.  I f a male b e a r s a R s p  +  a l l e l e , but  does  then t h e r e i s n o t h i n g to cause the Rsp"*" a l l e l e to r e s -  pond, and a g a i n s e g r e g a t i o n w i l l appear normal.  I f s e g r e g a t i o n i s to appear  51 abnormal, t h e r e must be  at l e a s t one  Thus the recombinants can be  a l l e l e and  classified  one  each of Rsp  g e n o t y p i c a l l y as f o l l o w s :  s i t i v e d i s t o r t e r s are Sd Rsp,  Tft insensitive nondistorters  sensitive nondistorters  +  and  are S d  cn s e n s i t i v e n o n d i s t o r t e r s  i s d i s t o r t e d by T f t Sd  +  Rsp  can be  w h i l e Sd  d i v i d e d i n t o two  +  Rsp  +  i s not  t h e r e f o r e , i s Sd  extended H a r t l ' s  Ganetzky (1977) i r r a d i a t e d SD-5  Rsp,  +  cn bw.  +  these had  corrected k values  c o r r e c t e d k's  near  the  components of  A  SD. source cn  bw. to  were r e p e a t e d  using  found t h a t t h r e e  w h i l e the other  five  of  had  0.5.  a l s o a l l mutant f o r I t .  t h a t had  Kc's  ( c o r r e c t e d k v a l u e s ) near 0.7  were  Furthermore, when they were complemented w i t h a  s e r i e s of p r o x i m a l d e l e t i o n s i n 2L somes behaved as i f they a l l had Group IX l e t h a l s to Group VII t h a t an enhancer of SD  The  Rsp.  that e v i d e n t l y f a i l e d  i n Chapter I) i t was  of a p p r o x i m a t e l y 0.7,  Those SJJ s e m i - r e v e r t a n t s  Ganetzky  +  .  males w i t h 5000 rads from a c o b a l t 60  (as I have d i s c u s s e d  Rsp  +  Rsp  However, when t e s t s f o r d i s t o r t i o n of cn bw  female c o n t r o l s  Rsp,  c l a s s e s s i n c e Sd  then t e s t e d the t r e a t e d chromosomes f o r t h e i r a b i l i t y to d i s t o r t  distort  Tft  (1974) a n a l y s i s by u s i n g r a d i a t i o n  From 4,000 t e s t e d chromosomes, e i g h t were r e c o v e r e d  (1977) d e s i g n a t e d  ( H i l l i k e r and  Holm 1975), these SD  chromo-  d e l e t i o n s e x t e n d i n g from the p o s i t i o n of  lethals (Hilliker  1976).  These r e s u l t s suggest-  i s l o c a t e d i n the c e n t r o m e r i c h e t e r o c h r o m a t i n of  2L.  t h i s l o c u s as E(SD).  f i v e complete SD r e v e r t a n t s were t e s t e d f o r t h e i r a b i l i t y to induce  s e l f d i s t o r t i o n of a Sd R s p cause Sd Rsp not  insen-  d i s t o r t e d by T f t Sd  induced d e l e t i o n s r a t h e r than recombinants to map  ed  Tft  +  +  4-  and  Sd  Rsp .  R s p , cn i n s e n s i t i v e d i s t o r t e r s are Sd  s e n s i t i v e chromosome such" as cn bw,  Ganetzky (1977) has  are  and  +  to d y s f u n c t i o n ,  chromosome. but  one  induce s e l f d i s t o r t i o n of Sd R s p  I t was  d i d not. +  was  found t h a t f o u r of them d i d Supposedly the one  that d i d  a p o w e r f u l suppressor of SD.  How-  ever, the other f o u r were c a n d i d a t e s f o r mutations  a t the SD_ l o c u s .  These  f o u r chromosomes were complemented w i t h a s e r i e s of d e l e t i o n s c o v e r i n g the base of 2L from p o l y t e n e chromosome band 36F cytologically. t i o n s and  failed  observed  to show any new  c y t o l o g i c a l abberations.  on t h i s chromosome t h a t extended  i t suggests  The  f o u r t h chromo-  l e t h a l w i t h some of the d e l e t i o n s and i n a d d i t i o n a d e l e t i o n  37D2-7 on the l e f t . and  They were a l s o examined  Three of the f o u r chromosomes were f u l l y v i a b l e w i t h the d e l e -  some, however, was was  to 40A.  from 38A6-B2 on the r i g h t  T h i s d e l e t i o n i s l o c a t e d between the s i t e s of T f t and  t h a t the JJd. s i t e of H a r t l  i n males, of 5,160  chromosomes t h a t were i r r a d i a t e d w i t h 5000 rads of gamma r a y s .  cn  r e c e s s i v e l e t h a l and  t e s t s r e v e a l e d the t h r e e l e t h a l s to be a l l e l i c . induced i n s e n s i t i v i t y s i t e was  This i s approximately  the r e g i o n where H a r t l  (1974) p l a c e d Rsp.  +  l e t h a l i n common, i t was  found  chromosomes had  the same r e c e s s i v e  d e c i d e d t h a t mapping t h i s l e t h a l should p r o v i d e i n -  f o r m a t i o n on the l o c a t i o n of Rsp.  A c c o r d i n g l y , these three chromosomes were  complemented w i t h a s e r i e s o f d e l e t i o n s and p o i n t mutations ( H i l l i k e r and Holm 1975;  t h a t the common r e c e s s i v e l e t h a l was  t i o n s , one  Ganetzky  these  case.  S i n c e t h r e e of the i n s e n s i t i v e cn bw  chromosomes was  I f the  a l l e l e s , then  i n s e n s i t i v e chromosomes should cause d i s t o r t i o n of Sd R s p .  of 2R  the newly  cn.  newly induced i n s e n s i t i v i t y a l l e l e s are newly induced Rsp  heterochromatin  Three of  complementation  By r e c o m b i n a t i o n  p l a c e d between p r and  bw  F i v e chromo-  somes were r e c o v e r e d t h a t were i n s e n s i t i v e to d i s t o r t i o n by SD-72. these chromosomes had a c q u i r e d a new  pr  (1974) i s l o c a t e d t h e r e a l s o .  Ganetzky (1977) a l s o t e s t e d the s e n s i t i v i t y ,  t h i s indeed t o be the  to  Hilliker  a mutation  1976).  at the r l l o c u s .  mutant o n l y a t _ r l , w h i l e the o t h e r two  e x t e n d i n g i n t o Group I l e t h a l s and  of the  appeared  centromeric  I t was One  found of  these  to be d e l e -  the o t h e r e x t e n d i n g both  into  Group I and i n t o Group I I I l e t h a l s  ( H i l l i k e r 1976).  These d a t a a l o n e suggest t h a t Rsp i s l o c a t e d near i r i . ( p e r s o n a l communication)  has t e s t e d h i s p r o x i m a l 2L and 2R d e f i c i e n c i e s  has found t h a t a t l e a s t one d e f i c i e n c y tion.  from each Group i s s e n s i t i v e  and  to d i s t o r -  Furthermore, D f ( 2 R ) M - S 2 ^ , which appears to be both c y t o l o g i c a l l y  genetically  deficient  results,  and  f o r a l l of the 2R c e n t r o m e r i c h e t e r o c h r o m a t i n ( H i l l i k e r  and Holm 1975), i s s e n s i t i v e  to d i s t o r t i o n  (Ganetzky 1977).  I n view of these  i t i s most unreasonable to m a i n t a i n t h a t Rsp i s l o c a t e d near r _ l .  o r d e r to e x p l a i n h i s r e s u l t s proposes t h a t the Rsp the  However, H i l l i k e r  i n view of H i l l i k e r ' s f i n d i n g s ,  s i t e may  case, then the i n s e n s i t i v e  Ganetzky  be l o c a t e d p r o x i m a l to Group I . cn bw  chromosome t h a t was  In  (1977)  I f t h i s were  l e t h a l o n l y f o r Group  I I would have to be the r e s u l t of a double " h i t " o f some type, one h i t c a u s i n g l e t h a l i t y a t Group I I and the o t h e r h i t m u t a t i n g the Rsp s i t e which i s p r o x i mal t o Group I . different  Ganetzky a l s o  s i t e s on d i f f e r e n t  p o i n t s out t h a t , c o n c e i v a b l y , Rsp might  chromosomes.  In the remainder of t h i s c h a p t e r I s h a l l p r e s e n t the r e s u l t s i n g s on the l o c a t i o n  occupy  and p r o p e r t i e s of j3d, E(SD) , and  Rsp.  o f my  find-  54 MATERIALS AND METHODS  The SD chromosomes used i n t h i s study were SD-5 and SD-72.  These chromo-  somes were o b t a i n e d by David Holm from the Pasadena s t o c k c e n t r e about t e n y e a r s ago.  SD-5 has been m a i n t a i n e d as a b a l a n c e d s t o c k over In(2LR)SMI, Cy  and SD-72 over In(2LR)SM5, Cy s i n c e t h a t time. In(2R)45C-F;  SD-5 has two i n v e r s i o n s ,  49A and In(2R)NS, w h i l e SD-72 has In(2R)NS and a p e r i c e n t r i c i n -  v e r s i o n , In(2LR)39-40;  42A (Lewis  1962).  A l l e x p e r i m e n t a l c r o s s e s were performed D r o s o p h i l a medium.  i n s h e l l v i a l s c o n t a i n i n g standard  S e g r e g a t i o n r a t i o s from males were always determined  the mean o f a number o f i n d i v i d u a l males each mated to two females. t i o n r a t i o s from females were always  determined  i n d i v i d u a l females each mated t o two males.  from  Segrega-  from the mean o f a number of  U s u a l l y p a r e n t a l f l i e s were a l l o w -  ed t o mate and l a y eggs f o r t h r e e to f o u r days and then they were d i s c a r d e d .  A c o b a l t - 6 0 source was used f o r r a d i a t i o n treatment.  Mature males were  t r e a t e d w i t h 2000 rads and then mated w i t h females immediately,  i n order that  mature, i r r a d i a t e d sperm were sampled.  A l l k v a l u e s a r e c a l c u l a t e d as the p r o p o r t i o n o f the t o t a l progeny i n g the chromosome t h a t i s w r i t t e n f i r s t o r on t o p .  bear-  For example, f o r the  a b c r o s s — mated t o — (a/b mated t o b/b) k r e f e r s t o the number o f progeny b b  bear-  i n g a d i v i d e d by the t o t a l number o f progeny.  For a d e s c r i p t i o n of any v i s i b l e g e n e t i c markers used i n t h i s study, see L i n d s l e y and G r e l l  (1968).  55 RESULTS AND  DISCUSSION  In order to t e s t i f t h e r e were any components of SD i n the c e n t r o m e r i c h e t e r o c h r o m a t i n o f 2L, I wanted to induce a number o f d e l e t i o n s i n that r e g i o n of a SD chromosome.  S i n c e I t ( l i g h t eyes) has an e a s i l y d e t e c t a b l e phenotype  and i s l o c a t e d i n the c e n t r o m e r i c h e t e r o c h r o m a t i n o f 2L ( H i l l i k e r and Holm 1975) I d e c i d e d t o use ^ - r a y s t o induce mutations done by i r r a d i a t i n g SD-5/SMI males, mating  o f JLt on SD-5.  them to homozygous b pr l t pk cn  females and then s c o r i n g the n o n - c u r l y winged progeny f o r I t eyes chromosome c a r r i e s the dominant gene Cy_, c u r l y w i n g s ) .  The SD-5  w i t h newly induced l t ^ mutations were then b a l a n c e d over SMI. being balanced  T h i s was  the " I t " SD-5 chromosomes were checked  (the SMI chromosomes  Immediately  f o r l e t h a l i t y with  Df(2L)PR31, a d e f i c i e n c y of p r o x i m a l 2L t h a t i n c l u d e s the l o c u s f o r l i t . it  i s known t h a t d e f i c i e n c i e s o f rt a r e r e c e s s i v e l e t h a l s  1975), those " l t "  after  Since  ( H i l l i k e r and Holm  SD-5 chromosomes t h a t were l e t h a l w i t h Df(2L)PR31 were r e -  t a i n e d f o r f u r t h e r examination, have h e t e r o c h r o m a t i c  s i n c e i t was l i k e l y t h a t some of them would  deficiencies.  Nine l t SD-5 chromosomes were r e c o v e r e d t h a t were l e t h a l w i t h Df(2L)PR31. A l l n i n e chromosomes were t e s t e d f o r t h e i r a b i l i t y t o d i s t o r t cn bw.  In  a d d i t i o n , they were complemented w i t h a s e r i e s of d e l e t i o n s of the h e t e r o c h r o matin  of 2L ( H i l l i k e r and Holm 1975) as w e l l as w i t h some r e c e s s i v e l e t h a l  p o i n t mutations  t h a t comprise  Group V I I ( H i l l i k e r 1976).  The r e s u l t s o f the  complementation  and d i s t o r t i o n t e s t s a r e shown i n F i g u r e 10.  Four of the  chromosomes have reduced k v a l u e s , w h i l e t h e r e m a i n i n g f i v e have k v a l u e s that are u n a f f e c t e d by the mutations it  i s apparent  around  lt^.  From the complementation  patterns  t h a t a component o f SD i s l o c a t e d between EMS 56-4 and the  Group VI l e t h a l s of H i l l i k e r  (1976).  The l o s s of t h i s component r e s u l t s i n  r e d u c i n g k from c l o s e t o 1.0 to a p p r o x i m a t e l y 0.6.  L i k e l y the reason  that  FIGURE 10  The complementation relationships between the putative SD-5 deficiencies and Hilliker's (1976) proximal heterochromatin of 2L.  groups of lethal mutations in the  The centromere is to the right of  Group VI, as drawn in the diagram.  Df(2L)(SD-5)-27 was unfortunately  lost before its ability to survive with EMS 56-24 was confirmed and a female.control to determine k^ was made.  The only other chromosomes for  which female controls were made were Df(2L)(SD-5)-2 and DF(2L)(SD-5)-61. The mean k shown for these is E(k ) and the error term is the 95 per c  cent confidence limits of E(k ) .  57  Gp IX  GpVIII  G VII  GpVI  P  EMS 56-4  SD-5  mean  del. no.  k  EMS 56-24  - -\  ^  2  _|  61  27  .595 ^ 0 2 7 1  -607 i °  .53  8  .883  45  .997  47 . 9 9 5  44  .988  10  .984  40  LO  2 6 8  Df(2L)(SD-5)-8  has  an i n t e r m e d i a t e k of 0.88  component to f u n c t i o n has deletion  to i t , but  i s t h a t the a b i l i t y of t h i s  o n l y been s l i g h t l y a f f e c t e d by the p r o x i m i t y of  the d e l e t i o n has not removed the SD s i t e .  SD-5  t h a t Df(2L).(SD-5)-8  has d e l e t e d  d e f i c i e n c i e s w i t h reduced  fewer of these than the other  Group V I I l o c i of H i l l i k e r  s p e c i f i e d by EMS  56-4  (1976).  I t i s apparent  as E(SD), was  here  the e x i s t e n c e of E(SD)  proximal heterochromatin  of  l o c a t e d i n heterochromatin. and  The d a t a  b pr I t pk cn.  T h i s chromosome was  the s u i t a b l e l o c a t i o n of i t s markers and  uncovered  the  r e s u l t s i n some o t h e r manner.  A c c o r d i n g l y , I undertook a r e c o m b i n a t i o n a l a n a l y s i s of SD-5.  The marker  chosen both because of  a l s o because i t i s v e r y s e n s i t i v e to  (from a c r o s s of SD-5/b pr I t pk cn males mated to homozygous b pr I t pk  cn females, 156  presented  2L.  component of jSD near r t , I wanted to c o n f i r m my  SD-5  56-24.  a l s o shows t h a t i t i s l o c a t e d i n the  As I d i d not know of Ganetzky's (1977) work when I had  chromosome used was  t h a t the l o c u s  d i d not, however, prove t h a t the component, which  he d e s i g n a t e d confirm  to  component of SID  Ganetzky (1977) a l s o r e p o r t e d d i s c l o s i n g an important He  three  has p e r m i t t e d me  must be d i s t a l to the l o c u s s p e c i f i e d by EMS  l o c a t e d i n p r o x i m a l 2L.  Group  k's.  I t i s a l s o i n t e r e s t i n g to note t h a t Df(2L)(SD-5)-8 order the two  the  However, i t i s  a l s o p o s s i b l e t h a t more than one jSD_ s i t e r e s i d e s between Group V I I I and VI and  SD  out of 16,008 t o t a l progeny, o n l y s i x were b pr I t pk c n ) .  s i n g l e SD-5/b pr I t pk cn females  each mated w i t h two homozygous b ;>pr I t  pk cn males the f o l l o w i n g progeny were r e c o v e r e d : b pr I t pk cn, 554 b_, 467 guished without  I t pk cn or pr I t pk cn  7,058 w i l d t y p e ,  of apparent jvr double  2 b pr I t pk,  I t i s i n t e r e s t i n g to note  crossovers.  6,711  (these c o u l d not be  f u r t h e r t e s t s ) , 4 pk cn, 46 b p r , 2 cn,  I t , 18 p_r, 2 b pk cn, 1 pr I t .  From  These w i l l be d i s c u s s e d  the h i g h later.  distin5 b pr  frequency  F i f t e e n o f the bj-bearing recombinants d i s t o r t both cn bw and b p r I t pk cn.  were t e s t e d f o r t h e i r a b i l i t y t o  The r e s u l t s a r e shown i n Table 1.  E l e v e n o f the 15 had h i g h k's over b o t h cn bw and b p r I t pk cn. had reduced k's.  However, f o u r  When heterozygous w i t h cn bw these f o u r had k's of about  and when heterozygous w i t h b p r I t pk cn they had k's o f about 0.8.  0.55  This  suggests t h a t some component o f SD i s l o c a t e d between b_ and p r .  T a b l e I I g i v e s the r e s u l t s o f t e s t s t o determine b p r - b e a r i n g recombinants  to d i s t o r t  the a b i l i t i e s o f the  cn bw and b p r I t pk cn.  F o u r t e e n chromo-  somes were t e s t e d and 13 had k's of about 0.55 over cn bw and 0.58 - 0.84 over b p r I t pk cn. For  One chromosome had a h i g h k over b o t h cn bw and b pr I t pk cn.  reasons t o be p r e s e n t e d l a t e r , i t i s assumed t h a t t h i s b p r chromosome was  not the r e s u l t o f a s i n g l e exchange between p_r and r t . anomaly, then a l l o f the b pr recombinants  I f one d i s r e g a r d s t h i s  had reduced k ' s .  This result i s i n  agreement w i t h the p r o p o s i t i o n t h a t t h e r e i s a component of SD l o c a t e d between b_ and _pjr.  B e f o r e examining more c a r e f u l l y the p r o p e r t i e s o f t h i s component, I  s h a l l p r e s e n t the d i s t o r t i n g a b i l i t i e s o f some o f the o t h e r  recombinants.  T a b l e I I I shows the a b i l i t i e s o f some of these recombinants cn bw and b p r I t pk cn.  to d i s t o r t  The k v a l u e s of R(SD-5) b p r I t - 1, R(SD-5) b pr I t  pk - 1, and R(SD-5) b pr I t pk - 2 a r e q u i t e v a r i a b l e but they tend t o be near 0.5 over both cn bw and b p r I t pk cn.  These chromosomes would be expected to  have k v a l u e s near 0.5, s i n c e they s h o u l d not have e i t h e r the S I D component between b_ and £r_ or t h e component near I t . has a v a l u e near 0.5.  The pr I t double recombinant  also  The two p r SD-5 chromosomes that were t e s t e d both had  high k values.  I t was r a t h e r p e c u l i a r t h a t these pr SD chromosomes s h o u l d have h i g h k ' s . I t was a l s o r a t h e r p e c u l i a r t h a t such a h i g h frequency o f _p_r "double o v e r s " were o b t a i n e d fromSD-5/b p r I t pk cn females.  cross-  Because I c o u l d not  60  TABLE I The d i s t o r t i n g a b i l i t i e s of the b SD-5 recombinants.  Recombinant  Cross*  Number of males tested  Total progeny  Mean k  95% confidence l i m i t s of k  b-20  1 2  5 12  348 729  .99 .98  b-8  1 2  4 11  344 664  .96 1.00  _  b-14  1 2  5 10  494 426  .99 1.00  _  b-7  1 2  5 12  350 765  1.00 1.00  b-13  1 2  5 12  481 1077  1.00 1.00  _  b-5  1 2  4 12  325 835  , .97 1.00  _  b-10  1 2  5 12  424 778  .98 .98  —  b-2  1 2  5 11  443 890  1.00 1.00  —  b-1  1 2  5 12  484 1123  1.00 1.00  b-3  1 2  5 11  487 889  1.00 1.00  _  b-6  1 2  5 12  546 1018  1.00 1.00  _  b-12  1 2  11 21  1153 1553  .56 .79 **  .53 - .59 .72 - .85 **  b-4  1 2  11 22  1119 1490  .54 .82 **  .50 - .58 .75 - .88 **  b-11  1 2  10 20  973 1618  .54 .80 **  .50 - .58 .74 - .86 **  b-9  1 2  6 19  538 1288  .55 .79 .**  .50 - .60 .72 - .85 **  TABLE I *  1-  2.  R(SD-5)b-x cn bw  male mated to  R(SD-5)b-x male mated to b pr It pk cn  (Continued)  cn bw females, cn bw b pr It pk cn females, b pr 1t pk cn  ** Calculated from arc sinv/k". Note:  None of these k values have been corrected for relative viability of SD and SD_ progeny. +  TABLE  II  62  The d i s t o r t i n g a b i l i t i e s of the b pr SD-5 recombinants.  Recombinant  Cross*  Number of males tested  Total progeny  Mean k**  95% confidence l i m i t s of k'  b pr-8  1 2  5 10  330 412  1.00 .97  b pr-7  1 2  11 24  866 2136  .51 .70  .47 .66  - .55 - .74  b pr-1  1 2  11 16  958 1185  .54 .66  .50 .59  - .58 - .73  b pr-9  1 2  10 14  687 1147  .55 .70  .48 .64  - .62 - .76  b pr-4  1 2  11 19  1003 1833  .59 .81  .55 .75  - .63 - .86  b pr-12  1 2  10 23  971 2299  .57 .65  .53 .61  - .61 - .67  1 2  10 21  739 1701  .54 ..78  .49 .71  - .59 - .84  b pr-15  1 2  11 23  956 2184  .57 .58  .53 .53  - .61 - .63  b pr-3  1 2  10 19  856 1256  .54 .79  .50 .70  - .58 - .87  b pr-14  1 2  11 22  1215 2221  .55 .71  .52 .65  - .58 - .76  b pr-5  1 2  9 18  836 1479  , .60 .75  .53 .70  - .67 - .80  b pr-2  1 2  11 23  1062 2047  .54 .71  .51 .64  - .57 - .78  b pr-16  1 2  11 24  1023 2321  .58 .71  .55 .68  - .61 - .74  b pr-6  1 2  10 16  742 1371  .56 .84  .50 .76  - .62 - .90  b pr-10 •  -  63  TABLE II *  **  1.  R(SD-5)b pr-x cn bw  male mated to  2.  R(SD-5)b pr-x b pr It pk cn  males mated to  (Continued)  cn bw cn bw  females,  b pr l t pk cn females, b pr It pk cn  Calculated from arc sin 7k .  Note:  None of these k values have been corrected for relative viability of SD and SD_ progeny. +  TABLE  III  64  The d i s t o r t i n g a b i l i t i e s of miscellaneous SD-5 recombinants.  Recombinant  Cross*  Number of males tested  Total progeny  Unweighted Mean k  95% confidence l i m i t s of F  b pr l t - 1  1 2  11 17  1046 1162  .48 .38  .46 - .51 .33 - .42  b pr I t pk-1  1 2  11 11  1121 941  .56 .48  .52 - .60 .44 - .52  b pr I t pk-2  1 2  11 13  1107 1011  .50 .39  .47 - .53 .31 - .48  pr l t - 1  1 2  11 18  995 1127  .49 .55  .45 - .52 .52 - .57  pr-3  1 2  5 10  445 578  .99 1.00  _  pr-6  1 2  4 11  369 583  1.00 1.00  _  *  1.  2.  Note:  R(SD-5)-x cn bw  male mated to  R(SD-5)-x b pr I t pk cn  cn bw cn bw  male mated to  females.  b pr I t pk cn b pr I t pk cn  females.  None of these k values have been corrected f o r r e l a t i v e v i a b i l i t y of SD and SD progeny. +  -  p h e n o t y p i c a l l y d i s t i n g u i s h pr l t pk cn and l t pk cn progeny,  from the above  c r o s s , I cannot c a l c u l a t e e x a c t l y what the observed frequency of recombination was  between b_ and £r and p_r' and l t ^ .  However, s i n c e t h e r e were 554 b_'s, 46  b pr' s, 467 pr I t pk cn' s or l t pk cn's, and 17 p_r' s, I can approximate  these  f r e q u e n c i e s o f exchange as: i, b - pr  =  554 + 18 +  L 1554 + 46  x  .. 100  =  _ 100  =  n  , 6.750%  14,870 and pr  i-  - lt =  46 + 18 +  1  \ 554 + 46^  x  1 A  _  0.67%  14,870 The number o f observed double exchanges between b_ and j>£ and j>r and _ l t should have been a p p r o x i m a t e l y e q u a l t o the product which i s 6.74. were r e c o v e r e d . duced  Thus I should have r e c o v e r e d about  14,870,  f o u r £ r ' s , when i n f a c t  18  Moreover, a l t h o u g h the numbers were s m a l l , f o u r females p r o -  one 2J£_ each, one  female produced  two '_p_r' s, and f o u r females  t h r e e p r ' s each, and these _p_r' s appeared of  of 0.0675, 0.0067, and  produced  to be r e c o v e r e d as c l u s t e r s .  Because  the h i g h frequency of observed n_r's and the i n d i c a t i o n of c l u s t e r i n g , i t i s  q u i t e p o s s i b l e t h a t these p_r' s were not the r e s u l t of a double exchange, i n s t e a d they might have been the r e s u l t of mutation. why  T h i s would a l s o  explain  the two p_r' s t e s t e d f o r t h e i r a b i l i t y to d i s t o r t cn bw had h i g h k's.  This  h y p o t h e s i s a l s o p r o v i d e s a r e a s o n a b l e e x p l a n a t i o n f o r the o b s e r v a t i o n t h a t R(SD-5) b pr -8/cn bw males had h i g h k v a l u e s .  Perhaps  R(SD-5) b pr - 8  was  the r e s u l t of a s i n g l e exchange between b_ and _p_r, a l o n g w i t h a mutation a t p r . If  t h i s were the case, then i t would be q u i t e l i k e l y t h a t R(SD)-5 b pr - 8  would s t i l l be capable of s t r o n g l y d i s t o r t i n g cn  In  bw.  o r d e r to f u r t h e r c h a r a c t e r i z e the component of SD between b_ and £r_, I  examined the s e g r e g a t i o n a l p r o p e r t i e s of the pr l t pk cn, I t pk cn, and pk cn recombinants  when heterozygous w i t h SMI.  Hartl  (1975) had  shown t h a t  In(2L + 2R)Cy c a r r i e d Rsp, and s i n c e SMI was d e r i v e d from In(2L + 2R)Cy ( L i n d s l e y and G r e l l 1968), I f e l t t h a t i t was r e a s o n a b l e t o assume t h a t SMI might a l s o have Rsp.  The r e s u l t s o f the experiment a r e shown i n T a b l e IV.  A l l o f the p r I t pk cn recombinants had k v a l u e s near 0.5. I t pk cn recombinants had k's o f about 0.3.  However, both the  T h i s suggests t h a t the sperm  b e a r i n g R(SD-5) I t pk cn were d y s f u n c t i o n i n g .  I t i s most r e a s o n a b l e t o assume  t h a t t h i s i s because t h e R(SD-5) I t pk cn chromosomes have the component o f SD between b_ and j>r, but they a l s o must have Rsp" ", i . e . they have t h e genotype 1  Sd R s p  and SMI i s S d Rsp, which t o g e t h e r i s a " s u i c i d e combination"  +  +  1974).  (Hartl  T h i s i n d i c a t e s t h a t the component between b_ and p r can o p e r a t e i n c i s  and t r a n s t o cause d i s t o r t i o n , p r o v i d i n g one chromosome has Rsp and the o t h e r has R s p . +  I have avoided c a l l i n g the component between b'and p r , Sd, and the component near I t E(SD) because t h e l o c i I have examined do not appear to behave i n e x a c t l y the same manner as the l o c i d e s c r i b e d by Ganetzky d i f f e r e n c e r e s i d e s i n the p r o p e r t i e s o f E(SD).  When Ganetzky  (1977).  The  (1977) d e l e t e s  Sd, which i s l o c a t e d between b_ and p r , t h e d e l e t e d SD chromosome i s no l o n g e r capable of d i s t o r t i n g cn bw.  However, when I r e p l a c e d the Sd s i t e w i t h a w i l d  type r e g i o n from the b pr I t pk cn chromosome, t h e r e s u l t i n g R(SD-5) b p r -  chromosomes s t i l l  appeared t o have a s l i g h t c a p a c i t y f o r d i s t o r t i n g cn bw (see  Table I I ) .  In  o r d e r t o t e s t more c a r e f u l l y f o r any r e s i d u a l d i s t o r t i o n i n the b p r  recombinants, I performed  the c r o s s e s shown i n T a b l e V.  S i n c e i t would  have  r e q u i r e d too much work t o t e s t a l l o f the recombinants, I s e l e c t e d o n l y one recombinant, R(SD-5) b p r - 5 , f o r e x t e n s i v e examination. 0.5,  When k i s c l o s e t o  i t i s important t o c o r r e c t f o r r e l a t i v e v i a b i l i t y of the two progeny  c l a s s e s , i f one wishes t o demonstrate  a s i g n i f i c a n t amount of d i s t o r t i o n i n  TABLE IV The d i s t o r t i n g a b i l i t i e s of R(SD-5)-x/SMl  67  males mated to homozygous  cn bw females.  n  f  E  ( c^ k  95% confidence l i m i t s of k c  pr l t pk cn-14  .50  12  .50  12  .50  .46 - .55  pr I t pk cn-15  .50  12  .56  12  .43  .38 - .49  pr l t pk cn-16  .50  12  .54  12  .46  .40 - .52  pr 1t pk cn-17  .48  12  .54  12  .44  .41 - .47  pr l t pk cn-18  .51  12  .55  12  .47  .41 - .53  pr l t pk cn-19  .47  11  .50  12  .47  .42 - .53  pr l t pk cn-20  .53  12  .54  10  .49  .43 - .55  pr l t pk cn-22  .48  11  .55  10  .48  .43 - .52  pr l t pk cn-23  .49  12  .57  10  .42  .36 - .49  pr l t pk cn-24  .51  11  .52  12  .49  .43 - .55  1t pk cn-1  .29  12  .53  11  .26  .18 - .35  I t pk cn-2  .26  12  .48  10  .28  .19 - .37  pk cn-1  .46  12  .49  12  .47  .42 - .52  TABLE V  68  The distorting abilities of R(SD-5) b pr-5 under various circumstances,  Experiment  b pr-5 cn bw b pr-5 cn bw  k  m  cn bw cn bw b pr It pk cn b pr It pk cn  b pr-5 „ cn bw b pr It pk cn cn bw  n  m  n^  )  95% confidence limits of E(k ) c  .560  49  .508  48  .551  .518 - .584  .530  49  .473  48  .555  . 5 2 6 - .584  .637  48  .506  49  .630  .586 - .674  .794  45  .608  45  .715  .666 - .764  b pr-5 b pr It pk cn x b pr It pk cn b pr It pk cn  the s e g r e g a t i o n r a t i o .  As I d e s c r i b e d a t the b e g i n n i n g of Chapter I , I f e e l  t h a t the b e s t way of doing t h i s i s by e x e c u t i n g a r e c i p r o c a l c r o s s .  However,  I noted t h e r e t h a t one drawback to t h i s technique i s t h a t c o n c e i v a b l y t h e r e c o u l d be v i a b i l i t y m a t e r n a l e f f e c t s a s s o c i a t e d w i t h one of the progeny  classes.  In o r d e r to check i f such a problem might be o c c u r r i n g , R(SD-5) b pr-5 was made heterozygous both w i t h cn bw and- w i t h b p r I t pk cn and then both  classes  of heterozygous males and females were mated w i t h homozygous cn bw and w i t h homozygous b p r I t pk cn males or females, as shown i n T a b l e V. b pr-5 was heterozygous w i t h cn bw, ECk^)  When R(SD-5)  was e s s e n t i a l l y the same, w i t h both  cn bw and b p r I t pk cn homozygous p a r e n t s (0.551 and 0.555 r e s p e c t i v e l y ) . However, when R(SD-5) b pr-5 was heterozygous w i t h b p r I t pk cn, ^ ( k ^ ) was 0.630 w i t h cn bw as the homozygous p a r e n t and 0.715 w i t h b p r I t pk cn as the homozygous p a r e n t .  T h i s l a r g e d i f f e r e n c e i n E ( k ) must be due e i t h e r to a c  v i a b i l i t y m a t e r n a l e f f e c t , or to a female genotype different  e f f e c t on the a b i l i t y of  sperm c l a s s e s t o f u n c t i o n d u r i n g f e r t i l i z a t i o n .  Without  experiments i t i s i m p o s s i b l e to say what causes t h i s d i f f e r e n c e . demonstrates ity  further This  result  t h a t one must not f o r g e t the drawbacks of t h i s type of a v i a b i l -  control.  In Chapter I , I d e s c r i b e d the r e s u l t s of a l a r g e s c a l e experiment w i t h R(SD-5) b pr-5/cn bw males mated to homozygous cn bw; K i pP bx s r e  s  The mean k v a l u e o f the experiment was 0.506, from 825 males t e s t e d . s t a n d a r d d e v i a t i o n of k was 0.064.  females. The  In o r d e r to check f o r any v i a b i l i t y p r o -  blems the r e c i p r o c a l c r o s s of R(SD-5) b pr-5/cn bw females mated to homozygous cn bw; K i pP bx s r e  s  males was performed.  In t h i s experiment,  females t e s t e d , k^ was 0.478 w i t h a s t a n d a r d d e v i a t i o n of 0.047. appear  t h a t one r e a s o n why k  was below 0.55 was because  from 31 I t would  of reduced  viability  m of progeny w i t h both the R(SD-5) b pr-5 chromosome and the K i pP bx s r e chromosome.  s  A f t e r c o r r e c t i n g f o r v i a b i l i t y , E(k ) equaled 0.529 and the 95  per cent c o n f i d e n c e i n t e r v a l of the mean was  0.509 to 0.546.  r e c t i o n s f o r v i a b i l i t y E(k^) was  s l i g h t l y l e s s than 0.55,  s i g n i f i c a n t l y g r e a t e r than 0.5.  Perhaps  because  of a m a t e r n a l v i a b i l i t y  Although t h e r e does appear or female genotype  ECk^)  s l i g h t l y l e s s than  t o be a problem w i t h e i t h e r m a t e r n a l  effects  shown i n T a b l e  s h o u l d c e r t a i n l y be taken as r e a s o n a b l e evidence  chromosome has r e p l a c e d Ganetzky's  o c c u r r i n g w i t h R(SD-5) b pr-5.  This  (1977) Sd_ s i t e , l o c a t e d between b_ and p r ,  w i t h the w i l d type s i t e from b pr I t pk cn. d e l e t e d t h i s s i t e on h i s SD-5  0.55  effect.  that segregation d i s t o r t i o n i s s t i l l  However, when Ganetzky  chromosome, t h e r e was  (1977)  no evidence f o r r e s i d u a l  The d i f f e r e n c e i s t h a t I used r e c o m b i n a t i o n , w h i l e Ganetzky  used d e l e t i o n s . t h a t the S d  a l t h o u g h i t was  e f f e c t s , the f a c t t h a t a l l f o u r experiments  V have E(k^) g r e a t e r than 0.5  distortion.  was  Even a f t e r c o r -  +  One  p o s s i b i l i t y which might  (1977)  account f o r t h i s d i f f e r e n c e i s  s i t e on b' pr l t pk cn c o u l d be s e m i a c t i v e .  In o r d e r to check i f t h i s was  the case, I examined a w i l d - t y p e  recombin-  ant r e c o v e r e d from a c r o s s of R(SD-5') b pr-5/cn bw  females mated to b pr l t pk  cn males.  pr -5.  T h i s recombinant  I w i l l c a l l R(SD-5) b  +  +  It w i l l likely  be  g e n o t y p i c a l l y the same as R(SD-5) b p r - 5 , except i t w i l l have most of euchromatic 2L from b pr l t pk cn r e p l a c e d w i t h euchromatic i n T a b l e VI, R(SD-5) b  +  p r - 5 appears +  0.543.  S i n c e t h i s recombinant  because  Sd  +  on both cn bw  to d i s t o r t  can a l s o d i s t o r t  2L from cn bw.  cn bw, cn bw,  g i v i n g E(k^) e q u a l t o i t must be  site,  either  and b pr I t pk cn are s e m i - a c t i v e , or because  s i t e between b_ and p_r i s not the o n l y Sd_ s i t e on the p a r t i c u l a r some used i n t h i s study.  As shown  SD-5  the S>d_  chromo-  I f the Sd_ s i t e between b_ and _p_r i s not the o n l y S<1  then I f e e l t h a t the component near I t i s a l i k e l y c a n d i d a t e f o r the  other Sd_ s i t e .  H e n c e f o r t h I s h a l l r e f e r to the s i t e between b_ and p_r_ as  and the s i t e near l t as S d . 0  Sd^  Each of these s i t e s alone p r o v i d e s a c e r t a i n  TABLE VI  71  Tests to determine i f Sd , on b pr It pk cn is semi-active. +  Experiment  E(k )  95% confidence limits of E(k )  40  .543  .520 - .567  .370  43  .464  .407 - .522  .355  49  .572  .547 - .597  k  n  ,515  50  .472  ,337  43  .424  45  m  m  k  f  n  f  c  c  RR(SD-5)b pr -5 cn bw +  +  x cn bw R(SD-5) b pr It b pr It pk cn x b pr It pk cn b pr It pk cn SMI x b pr It pk cn  72  c a p a c i t y to d i s t o r t , w h i l e b o t h t o g e t h e r enable maximal d i s t o r t i o n .  It  i s now  necessary  semi-active  (Sd^ ).  Sd^  s  A good t e s t would be to observe  s  Rsp/Sd^  S  Rsp  .  +  t o d e c i d e whether or not Sd*, on b pr I t pk cn i s  T h i s should have a k g r e a t e r than 0.5.  R(SD-5) b pr l t - 1 (see T a b l e I I I ) i s Sd-^ Rsp discussed l a t e r . determined  E(k ) c  the s e g r e g a t i o n r a t i o of  The  .  That  chromosome b pr I t pk cn i s S d ^  f o r R(SD-5) b pr l t - l / b  The  chromosome  i t c a r r i e s Rsp w i l l Rsp* .  s  pr I t pk cn.  I t was  be  Accordingly, I 0.464 and  the  95  per cent c o n f i d e n c e l i m i t s of t h i s mean were 0.407 - 0.522,(see T a b l e V I ) . The  t e s t d i d not show any s i g n i f i c a n t d i s t o r t i o n and  Sd*^ , on b pr I t pk cn i s not s e m i - a c t i v e ( S d ^ ) . s  unlikely  t h a t the c r o s s o v e r which produced  red between jLt and  Sd^.  i t i s very  R(SD-5) b pr l t - 1 would have o c c u r -  5d^~  +  t o r t i o n when heterozygous  2R of  Furthermore,  that  I f t h i s were the case, then the genotype of  R(SD-5) b pr l t - 1 c o u l d have been SD-^  the r e s i d u a l  a c c o r d i n g l y suggests  Rsp.  S i n c e i t d i d not show d i s -  w i t h b pr I t pk cn, i t i s r e a s o n a b l e t o  attribute  d i s t o r t i o n of R(SD-5) b pr-5 t o Sd^ and not to some other s i t e i n  SD-5.  As another  approach to determine  i f Sd*,  on the b pr I t pk cn chromosome,  is. s e m i - a c t i v e , I examined the s e g r e g a t i o n r a t i o of b pr I t pk cn/SMl when mated t o b pr I t pk cn homozygotes. Sd^  s  Sd  expect  + 2  +  /Sd^  +  Sd^  bility  Rsp  .  I f Sd^  s  E  c  was  not l e s s  than 0.5  E  c  as  was  of the mean d i d not o v e r l a p t h a t Sd*,  I t i s p e c u l i a r , however, t h a t ( k ) was  I t might be  symbolized  As shown i n T a b l e VI, ( k )  t h i s evidence a l s o suggests E  c  I f e e l that i t i s q u i t e reasonable effect.  c o u l d be  i s t r u l y s e m i - a c t i v e , then one would  the 95 per cent c o n f i d e n c e l i m i t s  I t pk cn i s not a c t i v e . 0.5.  +  t h a t ( k ) would be l e s s than 0.5.  0.572 and Since  Rsp  The h e t e r o z y g o t e  to a t t r i b u t e  0.5.  on b pr  g r e a t e r than  t h i s to a maternal  t h a t progeny which are homozygous b pr I t pk  viacn  are l e s s v i a b l e i f the female p a r e n t i s homozygous f o r b pr I t pk cn r a t h e r  than i f the female parent i s heterozygous  f o r b pr l t pk cn.  This hypothesis  i s a l s o i n agreement w i t h the o b s e r v a t i o n t h a t E(k ) f o r R(SD-5) b pr l t - 1 / c * b pr l t pk cn mated to b pr I t pk cn/b pr l t pk cn was  s l i g h t l y l e s s than  0.5  and a l s o w i t h the o b s e r v a t i o n t h a t Mk^)  f o r R(SD-5) b pr-5/b  mated to b pr l t pk cn/b p r l t pk cn was  g r e a t e r than E(k^) f o r R(SD-5) b p r - 5 /  b pr l t pk cn mated to cn bw/cn  pr l t pk cn  bw.  The evidence p r e s e n t e d here suggests t h a t both Sd^ and Sd^, are capable of i n d u c i n g a c e r t a i n amount of d i s t o r t i o n , p r o v i d i n g one chromosome has Rsp the o t h e r has Rsp*.  On the o t h e r hand, Ganetzky  s u g g e s t i n g t h a t o n l y Sd^ can operate on i t s own r e s u l t s l e a d him  to c a l l Sd.^  a  n  enhancer  (1977) has p r e s e n t e d evidence to induce d i s t o r t i o n .  of SD, E(SD).  p o s s i b i l i t i e s that could explain t h i s discrepancy. t h a t the SD-5  chromosome used by Ganetzky  not d i s t o r t a l o n e .  Secondly, perhaps  d e l e t e d behaves d i f f e r e n t l y  and  His  There are two  obvious  F i r s t l y , i t i s possible  (1977) had a Sd^, a l l e l e that c o u l d  an SD chromosome t h a t has had  Sd^  than an SD chromosome t h a t has had Sd^ r e p l a c e d  w i t h Sd* by r e c o m b i n a t i o n .  T h i s l a s t p o s s i b i l i t y would appear T h i s was  demonstrated  of the genotype  by r e p l a c i n g Sd^ w i t h Sd* from b pr l t pk cn.  Females  R(SD-5) b pr lt/R(SD-5) pk cn were mated to b pr l t pk cn  males and recombinants  t h a t were rt and pr I t were r e t a i n e d .  ed RR(SD-5) l t and RR(SD-5) pr l t . R(SD-5) pk cn i s Sd^ Sd^ Rsp, pr l t recombinant of 1,145  to be the case w i t h r e s p e c t to Sd^,.  These were  S i n c e R(SD-5) b pr I t i s Sd* Sd* Rsp  the J^t recombinant  would be Sd* Sd* Rsp.  would be Sd^ S d ^  +  Rsp  calland  and  the  As shown i n Chapter I the d i s t r i b u t i o n  RR(SD-5) pr l t / c n bw males mated to cn bw;  K i pP bx s r e  gave a mean k of 0.463 and a standard d e v i a t i o n of .076.  s  females  A r e c i p r o c a l cross  i n v o l v i n g 33 females gave a mean k of 0.467 and a standard d e v i a t i o n of 0.063. These r e s u l t s g i v e an ( k ) E  c  of .504 w i t h 95 per cent c o n f i d e n c e l i m i t s of  .481  to .528.  T h i s chromosome does not d i s t o r t , as one would expect.  RR(SD-5) I t /  cn bw males, on the other hand, had a mean k o f 0.713 and a standard of 0.118 (the sample s i z e was e q u a l t o 1,142).  deviation  A r e c i p r o c a l c r o s s had a k^ o f  0.47. k  m  S i n c e o n l y 17 females were examined, I w i l l not c a l c u l a t e k . The mean c of 0.713 was f a r g r e a t e r than one would expect from the r e s u l t s w i t h d e l e -  t i o n s of Sd„, which had k 's o f about 0.6. —2 c  Since the d e l e t i o n o f S d had a —2 0  d i f f e r e n t k than the recombinant t h a t r e p l a c e d Sd_^ w i t h  Sd*, i t i s apparent  t h a t , w i t h r e s p e c t t o SD, a d e l e t i o n does not n e c e s s a r i l y behave the same as an a l l e l i c  The capable  s u b s t i t u t i o n through  reason  recombination.  t h a t i t i s o f some importance t o know whether o r not Sd^ i s  o f o p e r a t i n g without  Sd^ i s t h a t Holm ( p e r s o n a l communication) has  observed t h a t compound 2R chromosomes c o n s t r u c t e d  from SD-72/cn bw a r e capable  of d i s t o r t i n g compound 2L chromosomes from'the I t stw s t r a i n .  SD-72 has a  p e r i c e n t r i c i n v e r s i o n w i t h break p o i n t s a t 39-40 and 42A (Lewis 1962) and because o f t h i s , a compound 2R chromosome c o n s t r u c t e d good chance o f h a v i n g  from SD-72 has a f a i r l y  Sd^,, but i t c o u l d n o t have Sd^, s i n c e Sd^ i s d i s t a l t o  the l e f t break p o i n t of the i n v e r s i o n .  Since an SD-72 compound 2R can d i s t o r t  a compound 2L, i t would be most r e a s o n a b l e  to assume t h a t i t i s Sd^, t h a t i s  o p e r a t i n g i n the compound 2R, e s p e c i a l l y i n view o f the evidence presented  t h a t has been  here.  Some SD-72 compound 2R's can cause almost t o t a l e l i m i n a t i o n o f c e r t a i n compound 2L's (Holm, p e r s o n a l  communication).  that some l o c i i n 2R o r p r o x i m a l  This observation  2L o f SD-72 a r e capable  l e v e l o f d i s t o r t i o n under c e r t a i n c o n d i t i o n s .  In o r d e r  SD-72/b pr I t pk cn females.  of inducing a high  T h i s suggests t h a t i t should be  p o s s i b l e t o exchange most o f 2L on SD-72 without of the recombinant.  demonstrates  a p p r e c i a b l y a f f e c t i n g the k  t o t e s t t h i s I o b t a i n e d b p r recombinants from F i v e o f these recombinants were r e t a i n e d and  t e s t e d f o r t h e i r a b i l i t y t o d i s t o r t ' cn bw.  The r e s u l t s a r e shown i n Table V I I  TABLE VII  75  The distorting abilities of R(SD-72) b pr-x/cn bw males mated to cn bw/cn bw females.  Recombinant  k  m  n  m  k  f  n  f  E(k )  95% confidence limits of k  c  c  b pr-1  .493  48  .507  43  .489  .462 - .512  b pr-2  .513  49  .499  47  .514  .490 - .538  b pr-3  .503  49  .505  43  .498  .477 - .518  b pr-4  .497  50  .499  49  .498  .476 - .520  b pr-5  .504  50  .500  45  .504  .478 - .530  In a l l f i v e cases E ( k ) was c  c l o s e to 0.5  v a l o f the mean i n c l u d e d 0.5. This r e s u l t  c l e a r l y p r e s e n t s a paradox.  SD-72 can d i s t o r t My  results  residual  There was  and the 95 per cent c o n f i d e n c e  a b s o l u t e l y no evidence f o r d i s t o r t i o n . I f a compound 2R c o n s t r u c t e d from  a compound 2L, then why  have shown t h a t under c e r t a i n  amount of d i s t o r t i o n  inter-  can't R(SD-72) b pr d i s t o r t  cn  bw?  circumstances Sd^, alone can cause  i n the SD-5  chromosome s t u d i e d h e r e .  a  In o r d e r  to r e s o l v e the p r e v i o u s l y mentioned paradox one must determine what the c i r c u m s t a n c e s are t h a t a l l o w s e g r e g a t i o n d i s t o r t i o n 2R's.  The r e s u l t s  to i n i t i a t e t h i s  Another  to operate i n SD-72 compound  p r e s e n t e d here suggest t h a t Sd^, i s a l i k e l y s i t e on which  study.  s i t e of i n t e r e s t  i s Rsp.  As mentioned i n the i n t r o d u c t i o n t o  t h i s c h a p t e r , Ganetzky (1977) has p r e s e n t e d evidence which suggests t h a t i s l o c a t e d near what H i l l i k e r and Holm (1975) have c a l l e d p r o x i m a l h e t e r o c h r o m a t i n of 2R. placement  t h a t such a  i s i n c o n s i s t e n t w i t h the s e n s i t i v i t y of a l a r g e h e t e r o c h r o m a t i c  i s most l i k e l y t h a t Rsp  Ganetzky (1977) concludes by i n f e r r i n g  that  i s l o c a t e d p r o x i m a l to Group I and t h a t h i s d e f i -  c i e n c y mapping of the s i t e was hit  Group I I , i n the  However, Ganetzky (1977) r e a l i z e s  d e l e t i o n such as Df(2R) M-S2~*"^. it  Rsp  somewhat m i s l e a d i n g because of p o s s i b l e m u l t i p l e  events.  I had planned  to determine  the s e n s i t i v i t i e s of the SD-5  t h a t I r e c o v e r e d , but t h i s proved d i f f i c u l t of s e m i - s t e r i l i t y  to do because of a p e c u l i a r  i n males of the genotype SD-5/SD-72.  combinants a l s o showed t h i s s e m i - s t e r i l i t y  recombinants  Many of the SD-5  re-  i n combination w i t h SD-72 and  s e q u e n t l y i n s u f f i c i e n t progeny were r e c o v e r e d to warrant  r e p o r t i n g the  A l t h o u g h I s h a l l not r e p o r t the s e n s i t i v i t i e s of a l l of the SD-5 I s h a l l d i s c u s s two p a r t i c u l a r  type  recombinants.  con-  results.  recombinants,  R(SD-5) pr l t - l / S D - 7 2 males  mated to b pr l t pk cn females gave a mean k of 1.0.  Ten males were t e s t e d  and  680 progeny r e c o v e r e d .  On the other hand R(SD-5) b pr l t - l / S D - 7 2 males  mated to b p r l t pk cn females  gave a mean k of 0.593 w i t h a 95 per cent  f i d e n c e i n t e r v a l from 0.529 to 0.657. geny were r e c o v e r e d .  Although,  E l e v e n males were t e s t e d and 842 p r o -  f o r some reason, the l a t t e r k was  l y g r e a t e r than 0.5, i t i s apparent  con-  t h a t R(SD-5) b pr l t - 1 was  significant-  essentially  i n s e n s i t i v e to SD-72, w h i l e R(SD-5) p r l t - 1 was v e r y s e n s i t i v e to SD-72. S i n c e Ganetzky (1977) has shown by r e c o m b i n a t i o n  t h a t Rsp l i e s between _p_r and  cn, i t i s u n l i k e l y t h a t the d i f f e r e n c e i n the s e n s i t i v i t i e s of these two r e combinants c o u l d be a r e s u l t of an exchange d i s t a l t o p r .  I t i s most  reason-  a b l e to a t t r i b u t e the s e n s i t i v i t y d i f f e r e n c e to d i f f e r e n c e s i n the s i t e of exchange between lt_ and pk, i . e . t h i s data suggests and pk.  Furthermore,  heterochromatin  s i n c e the frequency of exchange i n the c e n t r o m e r i c  of 2R i s v e r y low ( H i l l i k e r 1975), the r e s u l t suggests t h a t  Rsp l i e s i n the euchromatin  I found  t h a t Rsp l i e s between l t  of 2R p r o x i m a l to pk.  t h i s r e s u l t extremely  p e r p l e x i n g i n view of the o b s e r v a t i o n t h a t  a compound 2R c o n s t r u c t e d from SD-72 can d i s t o r t c e r t a i n compound 2L's (Holm, p e r s o n a l communication).  I f £>D compound autosomes behave the same as standard  SD autosomes, then C(2R)SD s h o u l d have Rsp and C(2L) should have R s p .  Since  +  compound autosomes r a r e l y have d u p l i c a t i o n s or d e f i c i e n c i e s of p r o x i m a l euchromatic  r e g i o n s ( H i l l i k e r and Holm 1975) , i f Rsp and R s p  the p r o x i m a l euchromatin have R s p . +  chromatin  +  are l o c a t e d i n  of 2R, i t i s v e r y u n l i k e l y t h a t a compound 2L c o u l d  On the other hand, i f R s p  +  were l o c a t e d i n the c e n t r o m e r i c h e t e r o -  of 2R, i t would be q u i t e l i k e l y t h a t a compound 2L c o u l d have R s p . +  In order to more c a r e f u l l y examine the l o c a t i o n of Rsp, I sought chromosome t h a t was rl  cn appeared  f r e e of i n v e r s i o n s , but c a r r i e d Rsp.  a  The chromosome b pr  to be i n s e n s i t i v e t o SD-72, s i n c e Sd-72/b pr r l cn males mated  to cn bw females  gave a mean k of 0.5 w i t h the 95 per cent c o n f i d e n c e  interval  78 of the mean b e i n g 0.46-0.54.  E l e v e n males were t e s t e d and 719 progeny  recovered.  i n s e n s i t i v e because  I f b pr r l cn was  i t c a r r i e d Rsp,  were  then i t  should be a b l e t o induce s e l f - d i s t o r t i o n of R(SD-5) I t pk cn, which i s Sd^ Sd^ Rsp E(k^) was  .  In the c r o s s R(SD-5) I t pk c n - l / b pr r l cn mated to b pr r l cn,  0.266 and  the 95 per cent c o n f i d e n c e i n t e r v a l of t h i s mean extended  from 0.222 to 0.309.  The mean k of the male c r o s s was  and the mean k of the female c r o s s was  0.250 (25 males t e s t e d )  0.480 (25 females t e s t e d ) .  b pr r l cn can induce s e l f - d i s t o r t i o n of R(SD-5) I t pk cn-1. it  i s q u i t e l i k e l y t h a t b pr r l cn c a r r i e d  I f b pr r l cn c a r r i e d Rsp, map  Rsp,  Because of  then i t was  recombined  from the w i l d - t y p e Oregon-R s t o c k .  this,  Rsp.  a s u i t a b l e chromosome to use to  s i n c e I have observed t h a t b pr r l cn does not have any  A c c o r d i n g l y , b pr r l cn was  Clearly  w i t h a s e n s i t i v e second  S i x s e p a r a t e recombinants  inversions.  chromosome of every geno-  type r e s u l t i n g from a s i n g l e exchange were r e t a i n e d and t e s t e d f o r s e n s i t i v i t y to an SD chromosome. sensitivity  A l l recombinants  to R(SD-5) pk cn.  the b_ and b pr recombinants  t h a t d i d not have cn were t e s t e d f o r  The r e s u l t s are shown i n T a b l e V I I I .  were more or l e s s s e n s i t i v e , s i n c e they a l l had  mean k's s i g n i f i c a n t l y g r e a t e r than 0.5. rl  recombinants  0.5.  The r e s u l t s are shown i n T a b l e IX.  had h i g h mean k's o f about  and pr r l cn recombinants The  0.97.  The  A l l but one of the r l cn  had mean k's whose 95 per cent c o n f i d e n c e i n t e r v a l s  one e x c e p t i o n was  Although I do not know why  included  of those shown i n T a b l e V I I I were t e s t e d  f o r t h e i r s e n s i t i v i t y to R(SD-5) b-8.  i n c l u d e d 0.5.  On the other hand, a l l of the b pr  had mean k's whose 95 per cent c o n f i d e n c e i n t e r v a l s  The r e c i p r o c a l recombinants  cn recombinants  A l l of  r l cn-2  and i t had a mean k of  i t had a mean k s i g n i f i c a n t l y  c e r t a i n l y d i d not show any e v i d e n c e of  These r e s u l t s suggest t h a t Rsp  0.43.  l e s s than 0.5, i t  sensitivity.  i s t i g h t l y l i n k e d to r l on the b pr r l cn  TABLE VIII  79  The sensitivities of b-bearing recombinants, from Or - R/b pr rl cn females, when heterozygous with R(SD-5) pk cn.  Number of males tested  Total progeny  Mean k  b-5 b-6  10 10 10 10 10 9  1222 1272 1190 1127 1191 1072  .71 .70 .76 .66 .71 .75  .65 .64 .67 .56 .67 .66  -  .77 .76 .85 .76 .75 .84  b b b b b b  pr-1 pr-2 pr-3 pr-4 pr-5 pr-6  10 10 10 10 10 9  848 920 1081 1467 1416 1005  .80 .61 .78 .59 .75 .71  .72 .54 .69 .56 .68 .62  _  .88 .68 .87 .62 .82 .80  b b b b b b  pr pr pr pr pr pr  10 9 10 10 10 9  1026 947 1347 1053 699 581  .50 .54 .50 .52 .47 .51  .47 .48 .45 .50 .42 .44  Recombinant  b-1 b-2 b-3 b-4  Note:  rl-1 rl-2 rl-3 rl-4 rl-5 rl-6  95% confidence limits of mean k  _  -  .53 .60 .55 .54 .52 .58  None of these k values have been corrected for relative viability of SD and SD progeny. +  TABLE IX  £  The sensitivities of on-bearing recombinants, from Or-R/b pr rl cn, when heterozygous with R(SD-5)b-8.  Number of males tested  Total progeny  Mean k  cn-1 cn-2 cn-3 cn-4 cn-5 cn-6  10 10 10 10 10 9  1426 1387 1313 1348 1404 1372  .95 .97 .95 .97 .97 .99  rl rl rl rl rl rl  cn-1 cn-2 cn-3 cn-4 cn-5 cn-6  9 9 10 10 10 10  1134 1215 1612 1464 1625 1625  .48 .43 .49 .47 .50 .47  .44 .39 .47 .44 .48 .44  .52 .47 .51 .50 .52 .50  pr pr pr pr pr pr  rl rl rl rl rl rl  10 10 10 10 10 10  1297 1763 1593 1600 1639 1334  .51 .49 .48 .50 .49 .49  .47 .45 .46 .46 .46 .45  .55 .53 .50 .54 .52 .54  Note:  cn-1 cn-2 cn-3 cn-4 cn-5 cn-6  95% confidence limits of mean k  None of these k values have been corrected for relative viability of SD and SD* progeny.  81 chromosome.  This i n turn implies  t h a t Rsp  c o u l d be  located i n heterochromatin,  s i n c e exchange between h e t e r o c h r o m a t i c l o c i i s v e r y However, t h i s p r o p o s a l  c o n t r a d i c t s the o b s e r v a t i o n  s e n s i t i v e , w h i l e R(SD-5) b pr l t - 1 was c o n t r a d i c t i o n one t i n and any  i t was  chance t h a t prevented me  of the 12 recombinants between r l and  b pr l t - 1 was  (Hilliker  In order  from s e p a r a t i n g Rsp  cn, or one  communication) o b s e r v a t i o n  from SD-72 can d i s t o r t a compound 2L, t h a t R(SD—5) b pr l t - 1 was  to a v o i d  from r l i n  must assume that R(SD-5) In view of  t h a t a compound 2R  constructed  I f e e l t h a t i t would be b e s t  to assume  the r e s u l t of a r a r e h e t e r o c h r o m a t i c exchange.  In an attempt to o b t a i n f i r m e r evidence on the l o c a t i o n of Rsp, covered f o u r  c f - r a y induced l e t h a l mutations of Group I I on cn bw  mutations were induced i n sperm).  I f any  one  + d e l e t i o n t h a t a l s o d e l e t e d Rsp  cause cn bw  to be  t h a t the t h r e e  , and  i f Rsp  was  avoided by  k was  1.0.  A d e l e t i o n of R s p  i n s e n s i t i v e (Ganetzky 1977).  s t e r i l e w i t h SD-5  The  i n both males and  females and  1,139  Ten  not be used to p r o v i d e  any  females.  not  located.  The  The  chromosome ( r l ) - l - c n bw-1  information  r e s u l t i n g complementation p a t t e r n s appears to be  (1976) EMS  - 4  The mean  they  on the l o c a t i o n of  could provide  fourth  T h i s problem  S D - 7 2 / ( r l ) - l - c n bw  complementing these l e t h a l s w i t h H i l l i k e r ' s  bw  of  The  progeny were r e c o v e r e d .  p o s i t i v e information  l e t h a l s i n the h e t e r o c h r o m a t i n of 2R  on cn  I t i s appar-  Thus a l l f o u r l e t h a l s of Group I I were s e n s i t i v e and  Nevertheless,  +  sensitivity  i s shown i n Table X.  t e s t i n g i t s s e n s i t i v i t y t o SD-72.  males were mated to cn bw  a  l o c a t e d p r o x i m a l to Group I,  chromosomes r e t a i n e d t h e i r s e n s i t i v i t y to SD-5.  Group I I l e t h a l was was  (these  +  three of the f o u r Group I I l e t h a l s to SD-5 ent  I re-  of these Group I I l e t h a l s was  then Group I would n e c e s s a r i l y a l s o be d e l e t e d . should  the  i s i n f a c t l o c a t e d i n euchroma-  the r e s u l t of a r a r e h e t e r o c h r o m a t i c exchange.  Holm's ( p e r s o n a l  1975).  t h a t R(SD-5) pr l t - 1 was  insensitive.  must e i t h e r assume t h a t Rsp  only  rare  could  Rsp. induced  on where Rsp  are shown i n F i g u r e  is  11.  a d e l e t i o n e x t e n d i n g from Group I I  82  TABLE X The sensitivities of cn bw chromosomes with c^-ray induced lethals on them.  A.  B  SD-5 ( r l ) - l - c n bw-x  x  cn bw  ¥  *  Lethal Number  Number of males tested  Total progeny  Mean k  1  44  2746  .993  2  47  2934  .980  3  42  2773  .982  '  Lethal Number  SD-5 ( r l ) - l - c n bw-x *  x  cnbw cn bw  ^  95% confidence 1imits of mean k  Number of females tested  Total progeny  Mean k  10  1006  .52  .50 - .54  10  1044  .52  .49 - .55  10  951  .49  .46 - .52  FIGURE 11 The complementation relationships between the cn bw chromosomes bearing putative deficiencies and Hilliker's (1976) groups of lethal mutations in the proximal heterochromatin of 2R. of Group I.  This is to the left  Gpl t *" EMS 45-10  \  »  Gpll  Gp III  GpIV  GpV  V  lethal n a  EMS 31  j  I  I  j——1  1  — r — i  j  j  ,  j  i  i—A  j  r  1  :  !  :  I  i  I  j  j  i  i—I  i  1  2  j  3  I  4  to the Group I s i t e s p e c i f i e d by EMS lethals  (EMS 45-10, EMS  Group I.  45-84, EMS  31.  I t complements w i t h a l l  45-91, and EMS  45-87) i n the other s i t e of  Thus Rsp would not appear to be l o c a t e d between Group I I and the  s i t e s p e c i f i e d by EMS  31.  T h i s r e s u l t a l s o demonstrates that the EMS  i s d i s t a l to the o t h e r Group I s i t e s p e c i f i e d by EMS 45-91, and EMS little  f o u r of the  45-87.  45-10, EMS 45-84,  31 s i t e EMS  The o t h e r % - r a y induced l e t h a l s on cn bw p r o v i d e  i n f o r m a t i o n of any s o r t .  The chromosome ( r l ) - l - c n bw-4  was p e c u l i a r i n  t h a t i t was the r e s u l t of a m u l t i p l e h i t event, even though o n l y 2000 rads were used to generate these  lethals.  CONCLUSION  T h i s £!D mapping study was  p a r a l l e l to Ganetzky's (1977) work i n many ways.  Both s t u d i e s have demonstrated the e x i s t e n c e SD-5  t h a t i s l o c a t e d j u s t d i s t a l to _p_r.  tence of another component, on SD-5, have c o n t r i b u t e d Rsp  of an important component  They a l s o have demonstrated the  t h a t i s l o c a t e d near l t ^ .  the c r e d i b i l i t y of the p o i n t s agreed upon.  ence between our  Both  studies  r e s u l t s i s that my  T h i s agreement The  o n l y major  differ-  f i n d i n g s suggest t h a t the component of SD_  component l o c a t e d j u s t d i s t a l to _p_r, p r o v i d i n g one chromosome has  Rsp . +  to pr_, I have c a l l e d Sd.. and  that  serves  l o c a t e d near L t i s capable of i n d u c i n g d i s t o r t i o n i n the absence of the  other  exis-  a meagre amount of e v i d e n c e i n support of the c o n t e n t i o n  i s l o c a t e d i n the p r o x i m a l h e t e r o c h r o m a t i n of 2R.  to i n c r e a s e  on  Accordingly,  chromosome has  Rsp  the s i t e t h a t i s l o c a t e d j u s t  SD  and  the  distal  the s i t e that i s l o c a t e d near L t , I have c a l l e d  87  LITERATURE CITED Crow, J . F . , C. Thomas, and L. Sandler, 1962 Evidence that the segregationdistortion phenomenon in Drosophila involves chromosome breakage. Proc. Nat. Acad. Sci. U.S.A. 48: 1307 - 1314, Das, C C , B.P. Kaufmann, and H. Gay, 1964 Histone protein transition in Drosophila malanogaster. I. Changes during spermiogenesis. Exp. Cell Res. 35: 507 - 514. Ganetzky, B., 1977 On the components of segregation distortion in Drosophila melanogaster. Genetics 86_: 321 - 355. Gould-Somero, M. and L. Holland, 1974 The timing of RNA synthesis for spermiogenesis in organ cultures of Drosophila melanogaster testes. Wilhelm Roux Archiv. 174: 133 - 148. 1  Hartl, D.L., 1974 Genetic dissection of segregation distortion. combinations of SD genes. Genetics 76: 477 - 486.  I.  Suicide  Hartl, D.L., 1975 Genetic dissection of segregation distortion. II. Mechanism of suppression of distortion by certain inversions. Genetics 8TJ: 539 - 547. Hartl, D.L. and Y. Hiraizumi, 1976 Segregation distortion. In: The genetics and biology of Drosophila. Edited by M. Ashburner and E. Novitski, Academic Press, Londbrr: Hartl, D.L., Y. Hiraizumi, and J.F. Crow, 1967 Evidence for sperm dysfunction as the mechanism of segregation distortion in Drosophila melanogaster. Proc. Nat. Acad. Sci. U.S.A. 58: 2240 - 2245. Hilliker, A . J . , 1976 Genetic analysis of the centromeric heterochromatin of chromosome 2^ of Drosophila melanogaster: Deficiency mapping of EMSinduced lethal complementation groups. Genetics 83_: 765 - 782. Hilliker, A.J. 1975 Genetic analysis of the proximal heterochromatin of chromosome 2^ of Drosophila melanogaster. Ph.D. Thesis, University of British Columbia. Hilliker, A.J. and D.G. Holm, 1975 Genetic analysis of the proximal region of chromosome 2 of Drosophila melanogaster. I. Detachment products of compound autosomes. Genetics 81: 705 - 721. Hiraizumi, Y., 1961 Lethality and low viability induced by the segregation distorter locus (symbol SDj in Drosophila melanogaster. Ann. Rep. Nat. Inst. Genet. Jap. 12: 1-2. Hiraizumi, Y. and K. Nakazima, 1967 Deviant sex ratio associated with segregation distortion in Drosophila melanogaster. Genetics 55: 681-697. Johnson, N.I. and S. Kotz, 1969 Discrete distributions. Co., Boston.  Houghton Mifflin  88  Kettanah, N.P. and D.L. Hartl, 1976 Histone transition during spermiogenesis is absent in segregation distorter males of Drosophila melanogaster. Science 193: 1020 - 1021. Lewis, E.B., 1962 Salivary gland chromosome analysis of segregation distorter lines. Dros. Inf. Ser. 36_: 87. Lindsley, D.L. and E.H. Grell, 1968 Genetic variations of Drosophila melanogaster. Carnegie Institute of Washington Publ. No. 627^ Mange, E.J., 1968 Temperature sensitivity of segregation-distortion Drosophila melanogaster. Genetics 58: 399 - 413.  in  Miklos, G.L.G. and S. Smith-White, 1971 An analysis of the instability of segregation-distorter in Drosophila melanogaster. Genetics 67_: 305-317. Mood, A.M., F.A. Graybill, and D.C. Boes, 1974 Introduction to the theory of statistics. McGraw-Hill, New York. Novitski, E. and I. Sandler, 1957 Are all products of spermatogenesis regularily functional? Proc. Nat. Acad. Sci. U.S.A. 43: 318 - 324. Peacock, W.J. and J. Erickson, 1965 Segregation-distortion and regularily nonfunctional products of spermatogenesis in Drosophila melanogaster. Genetics 51: 313 - 328. Peacock, W.J., K. Tokuyasu, and R.W. Hardy, 1972 Spermiogenesis and meiotic drive in Drosophila. In: Edinburgh symposium on the genetics of the spermatozoon. Edited by R.A. Beatty and S. Gluecksohn-Waelsch, Bogtrykkeriet Forum, Copenhagen. Rendel, J.M., 1967 Canalisation and gene control.  Logos Press, London.  Sandler, L. and Y. Hiraizumi, 1960a Meiotic drive in natural populations of Drosophila melanogaster. IV. Instability at the segregationdistorter locus. Genetics 45: 1269 - 1287. Sandler, L. and Y. Hiraizumi, 1960b Meiotic drive in natural populations of Drosophila melanogaster. V. On the nature of the SD region. Genetics 45: 1671 - 1689. Sandler, L., Y. Hiraizumi, and I. Sandler, 1959 Meiotic drive in natural populations of Drosophila melanogaster. I. The cytogenetic basis of segregation-distortion. Genetics 44_: 233 - 250. Sokal, R.R. and F.J. Rohlf, 1969 Biometry. Francisco.  W.H. Freeman and Co., San  Tokuyasu, K.T., 1974 Dynamics of spermiogenesis in Drosophila melanogaster. IV. Nuclear transformation. J. Ultrastruct. Res. 48: 284 - 303.  89 Tokuyasu, K.T., W.J. Peacock, and R.W. Hardy, 1977 Dynamics of spermiogenesis in Drosophila melanogaster. VII. Effects of segregation distorter (SD) chro~mosome. J. Ultrastruct. Res. 58: 96 - 107. Zimmering, S. and G.L. Fowler, 1968 Progeny: sperm ratios and nonfunctional sperm in Drosophila melanogaster. Genet. Res. (Camb.) 12: 359 - 363.  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0094064/manifest

Comment

Related Items