Who ar e t he Myt i l us t r ossul us? • The M. t r os s ul us a r e c ommon ma r i ne mus s e l s • Found a l ong r oc ky s hor e l i ne s of Nor t h Ame r i c a i n t he i n t e r t i da l z one a nd s pa n f r om hi gh t i da l z one t o l owe s t t i da l poi n t . • Col oni z e i n c l umps on r oc ks • Ar e a f ounda t i on s pe c i e s - a domi na nt s pe c i e s i n a ha bi t a t t ha t a r e a bunda nt a nd ha ve ma j or i nf l ue nc e on t he e c os ys t e m • Ar e a l s o I ndi c a t or s pe c i e s – a s t he y r e pr e s e nt t he ove r a l l he a l t h of a n e c os ys t e m a nd a r e i nf l ue nc e d by e nvi r onme nt a l c ondi t i ons : d i s e a s e out br e a k, pol l u t i on, s pe c i e s c ompe t i t i on or c l i ma t e c ha nge . Who ar e t he Myt i l us t r ossul us Phyl um Mol l us c a Cl a s s Bi va l vi a Subc l a s s Pt e r i omor phi a Or de r Myt i l o i da Fa mi l y Myt i l i da e Ge nus Myt i l us Spe c i e s t r os s ul us Mussel s: An i deal model t o st udy oxygen met abol i sm • Re s i de i n i n t e r t i da l z one – s ubj e c t e d da i l y t o e xt r e me f l uc t ua t i ons i n oxyge n l e ve l s • Se s s i l e or ga ni s ms - e a s i e r t o mi ni mi z e s t r e s s on a ni ma l s r e s ul t i ng f r om c a pt i vi t y a nd t e s t i ng pr oc e dur e s . No move me nt = no i nt e r f e r e nc e wi t h e qui pme nt • Mus s e l s c a n l i ve f or e xt r e me l y l ong pe r i ods i n t he pr e s e nc e of a noxi a ( no oxyge n) . – 35 da ys a t 10 oC ! ! ! ! ! Mussel s: Over comi ng adver si t y • Mus s e l s a r e we l l a da pt e d t o t he pr obl e ms f a c e i n l ow a nd hi gh t i de s : – Fi l t e r f e e di ng or ga ni s ms t ha t us e de l i c a t e gi l l s t o t r a p nut r i e nt s i nc l udi ng oxyge n – I n t he s ubme r ge d s t a t e , oxyge n mus t be di s s ol ve d i n wa t e r i n or de r t o be t a ke n up by gi l l s – Low t i de mus s e l s wi l l c l a m up a nd e mpl oy s t r a t e gi e s t o s ur vi ve hypoxi a ( l ow oxyge n l e ve l s ) Over comi ng Chal l enges i n Oxygen Fl uct uat i ons • Low t i de pos e s s pe c i a l pr obl e ms f or or ga ni s ms . • Gi l l r e s pi r i ng a ni ma l s ha ve di f f i c ul t y e xt r a c t i ng oxyge n f r om a i r • For t hos e l uc ky e nough t o ha ve wa t e r , t i da l pool s a r e wa r me r – oxyge n s a t ur a t i on i n wa t e r i s muc h l owe r , c a r bon d i oxi de di s s ol ve s r e a di l y i n t o t he pool a nd oxyge n e s c a pe s i t . - c o- i nha bi t a nt s c ompe t e f or a va i l a bl e oxyge n How do Mussel go wi t hout ? How do t hey sur vi ve t he dr y spel l ? Wi t h l e s s oxyge n, t he r e c ome s a poi nt whe r e t he c os t of r e s pi r a t i on e xc e e ds t he be ne f i t of e xt r a c t i ng oxyge n. The t ur ni ng poi nt i s c a l l e d t he Pc r i t – t he c r i t i c a l oxyge n pr e s s ur e The Pc r i t r e pr e s e nt s t he poi nt whe r e e nvi r ome nt a l oxyge n i s t oo l ow f or a n or ga ni s m t o ma i nt a i n c ur r e nt oxyge n me t a bol i s m Whe n f a c e d wi t h oxyge n s hor t a ge , a n or ga ni s m ha s a c hoi c e : - To obt a i n e ne r gy f r om ot he r s our c e s - To de pr e s s me t a bol i s m - To do bot h of t he a bove I nvest i gat i ng Hypoxi a Tol er ance • The pur pos e of t h i s e xpe r i me nt i s t o f ur t he r knowl e dge a bout t he me c ha ni s ms mus s e l s us e t o s ur vi ve hypoxi c c ondi t i ons NORMOXI A= nor ma l oxyge n l e ve l s HYPOXI A = l owe r t ha n nor ma l oxyge n l e ve l s ANOXI A = no oxyge n pr e s e nt Met hods • 35 mus s e l s we r e ha r ve s t e d i n Oc t obe r 15 t h, 2007 t o a s s e s s t he Pc r i t f r om mi d- t i da l z one s a t Loc a r no Be a c h • 40 we r e c ol l e c t e d Fe b 1 s t , 2008 f or t he s e c ond pha s e of t he e xpe r i me nt • Mus s e l i de nt i f i e d ba s e d on pr e vi ous mol e c ul a r ge ne t i c s t udy of p53 ge ne ( Mut t r a y a nd Cox, 2005) Met hods cont i nued • Mus s e l s we r e t r a ns por t e d ba c k t o t he Ri c ha r ds La b a t UBC: – Ba r na c l e s r e move d a nd s he l l s c l e a ne d f r om de br i s – Pl a c e d i n a l a r ge a qua r i um a nd a l l owe d t o a c c l i ma t e f or a mont h a t 12 oC a nd 30ppt s a l i ni t y . – 15 mus s e l s f r om t he f i r s t ba t c h us e d t o t e s t s e t up a nd 16 we r e us e d t o a s s e s s t he Pc r i t . Met hods cont i nued • Mus s e l s we r e t r a ns por t e d ba c k t o t he Ri c ha r ds La b a t UBC: – Ba r na c l e s r e move d a nd s he l l s c l e a ne d f r om de br i s – Pl a c e d i n a l a r ge a qua r i um a nd a l l owe d t o a c c l i ma t e f or a mont h a t 12 oC a nd 30ppt s a l i ni t y . – 15 mus s e l s f r om t he f i r s t ba t c h us e d t o t e s t s e t up a nd 16 we r e us e d t o a s s e s s t he Pc r i t . Measur i ng Oxygen Consumpt i on • Mus s e l s we r e p l a c e d i n r e s pi r ome t e r a nd a l l owe d a 24h r e c ove r y t o de - s t r e s s pr i or t o c ol l e c t i ng da t a • Re s pi r ome t e r wa s c onne c t e d t o a Foxy Pr obe – t r a ns mi t s b l ue LED l i ght a t ~470nm a nd que nc hi ng of s i gna l i s r e a d by a s pe c t r ome t e r , USB2000- FL Fl uor e s c e nc e Spe c t r ome t e r , • Us i ng OOI Se ns or s Sof t wa r e oxyge n c ons umpt i on wa s a s s e s s e d us i ng t he St e r n- Vol me r e qua t i on. • Mus s e l s we r e a l l owe d a 24h r e c ove r y t o de - s t r e s s pr i or t o c ol l e c t i ng da t a Appar at us Set up Resul t s on Oxygen Consumpt i on Time Chart 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Time (min) W at er P O 2 (t or r) • 16 mus s e l s we r e t e s t e d i n a c l os e d r e s pi r ome t e r a nd a l l owe d t o c ons ume t he l i mi t e d a va i l a bl e oxyge n unt i l t he y c e a s e d t o r e s pi r e • The a bove gr a ph s hows t he c ons umpt i on of oxyge n whe n a mus s e l i s pl a c e d i n a s e a l e d r e s pi r ome t e r . •For r e f e r e nc e , 125 t or r ~ 16% O2 , whi c h i s t he a mount of oxyge n i n a i r . Conver t i ng Oxygen Consumpt i on Rat e t o cal cul at e Pcr i t Time Chart 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.02 0.00 20.00 40.00 60.00 80.00 100.00 120.00 Water PO2 (torr) M O 2 um ol /g /h r • The a bove gr a ph s hows t he mol e c ul a r oxyge n c ons umpt i on r a t e c a l c ul a t e d f r om t he pr e vi ous s l i de . • Cons umpt i on of Mol e c ul a r Oxyge n Cons umpt i on Ra t e r e l a t i ve t o Oxyge n Pr e s s ur e yi e l ds t he Pc r i t us i ng r e gr e s s i on l i ne s . Conver t i ng Oxygen Consumpt i on Rat e t o cal cul at e Pcr i t • Us i ng r e gr e s s i on l i ne s t o de t e r mi ne t he c ons umpt i on of Mol e c ul a r Oxyge n Cons umpt i on Ra t e r e l a t i ve t o oxyge n pr e s s ur e . Resul t s of Pcr i t Assessment s • Pc r i t i s t he t hr e s hol d pr e s s ur e of oxyge n i n whi c h t he mus s e l c a nnot s us t a i n us ua l me t a bol i c c ons umpt i on r a t e of oxyge n • Fr om da t a r e s ul t s , i t wa s a s s e s s e d t ha t t he mus s e l s ha d a me a n c r i t i c a l oxyge n t e ns i on of 20. 94± 2. 09 t or r ~ 2 . 7% a t mos phe r i c oxyge n What does t hi s mean? What happens af t er Pcr i t Phase I I of Mussel Hypoxi a St udy • Now t ha t we ha ve da t a on t he t r a ns i t i on poi n t i n t he oxyge n me t a bol i s m a nd we know wha t t he i r t hr e s hol d i s . • Ve r y l i t t l e i s known a bout t he e me r ge nc y me c ha ni s ms t ha t mus s e l s e mpl oy whe n f a c e d wi t h a n oxyge n c r i s e s • St udi e s ha ve f oc us e d on l ong t e r m e f f e c t whi c h s how t ha t Mus s e l s wi l l r e duc e me t a bol i c a c t i v i t y – r e qui r i ng f e we r r e s our c e s a nd pr oduc i ng l e s s t oxi c bypr oduc t s The Emer gency Response • The s e c ond por t i on i s t o a s s e s s me t a bol i c ma r ke r s me a s ur e ATP, Phos phoa r gi ni ne , Oc t opi ne ( t he i nve r t e br a t e e qui va l e nt of l a c t a t e ) . • Thi s wi l l s how whe t he r t he mus s e l ’ s pr i ma r y s ur vi va l me c ha ni s m i s t o i mme di a t e l y l owe r me t a bol i s m or s wi t c h t o a l t e r na t e pa t hwa ys t o ge t t he i r e ne r gy • For e xa mpl e , i f ATP l e ve l s a r e t he s a me be f or e a nd a f t e r Pc r i t , t he mus c l e ha s not l owe r e d me t a bol i c a c t i v i t y . The Emer gency Response • At t h i s poi nt 40 mus s e l s ha ve be e n a c c l i ma t i ng: – 10 wi l l be us e d a t nor moxi a - c ont r ol – 10 wi l l be s ubj e c t e d a t 20 t or r – 10 wi l l be s ubj e c t e d t o 12 t or r ( 2 s t a nda r d de vi a t i ons be l ow me a n) – 10 s ubj e c t e d t o c ompl e t e a noxi a • St udy i s ongoi ng t o a c qui r e da t a t o de t e r mi ne ATP, Phos phoa r gi ni ne , Oc t opi ne i n Mus s e l Ti s s ue s • Da t a wi l l a l l ow f ur t he r or unde r s t a ndi ng i n t o how t he Myt i l us t r os s ul us ’ s us e s e me r ge nc y me t a bol i c c opi ng me c ha ni s ms t o hypoxi a s t r e s s e s Acknowl edgment • I woul d l i ke t o t ha nk t he a udi e nc e f or t he i r a t t e nt i on • The Ri c ha r ds La bs f or us e of t he i r f a c i l i t i e s • Dr . J e f f Ri c ha r ds PhD f or hi s pa t i e nc e a nd gui da nc e . I ma ge s of mus s e l s a r e a l t e r e d pi c t ur e s . Or i gi na l s we r e obt a i ne d f r om t he i nde x f ound on ht t p: / / www. wa l l a wa l l a . e du/ a c a de mi c s / de pa r t me nt s / bi ol ogy/ r os a r i o/ i nve r t s . D. Cowl e s ( 2002) I ma ge f or OOSe ns or Foxy pr obe c a n be f ound a t : ht t p: / / www. i ns t r ume nt r e gi s t e r . c om/ 2006/ 09/ oxi me t e r - bl ood- i nf r a r e d. ht ml . ( 2006)
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Assessing hypoxia tolerance in the Mytilus trossulus Mader, Heidi 2008-03-08
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Title | Assessing hypoxia tolerance in the Mytilus trossulus |
Creator |
Mader, Heidi |
Date Issued | 2008-03-08 |
Description | Presented at the Multidisciplinary Undergraduate Research Conference on March 8, 2008 in the Irving K. Barber Learning Centre, University of British Columbia. Abstract: Organisms that reside in the intertidal zone are routinely subjected to extreme fluctuations of oxygen levels. To cope with subnormal available oxygen in an environment, organisms must either reduce their metabolic activity, switch to alternate biochemical pathways to generate cellular energy, or use a combination of the two. Using the marine mussel, Mytilus trossulus, in a two-part investigation, the critical oxygen tension (Pcrit) was assessed to determine the point at which the animal could no longer maintain normal metabolic activity. With this information, the metabolic responses were analyzed for the second part of the experiment to gain further insight into how alternate biochemical pathways aid the mussel to overcome prolonged oxygen deprivation. |
Extent | 8728576 bytes |
Genre |
Presentation |
Type |
Text |
FileFormat | application/vnd.ms-powerpoint |
Language | eng |
Series |
University of British Columbia. Multidisciplinary Undergraduate Research Conference (MURC) |
Date Available | 2008-08-05 |
Provider | Vancouver : University of British Columbia Library |
Rights | Attribution-NonCommercial-NoDerivatives 4.0 International |
DOI | 10.14288/1.0081273 |
URI | http://hdl.handle.net/2429/1266 |
Affiliation |
Science, Faculty of |
Campus |
UBCV |
Peer Review Status | Unreviewed |
Scholarly Level | Undergraduate |
Copyright Holder | Heidi Mader |
Rights URI | http://creativecommons.org/licenses/by-nc-nd/4.0/ |
AggregatedSourceRepository | DSpace |
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