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UBC Theses and Dissertations

A study of the autonomous behaviour of sex-linked temperature-sensitive lethal mutants in drossophila melanogaster Hayashi, Shizu


The autonomous behaviour of sex-linked recessive temperature-sensitive lethal mutants in Drosophila melanogaster could be demonstrated by the presence of mosaic patches of tissue hemizygous for the mutant created by loss of a ring X chromosome in cells at the permissive temperature (21.5°C) and the absence of such patches at the restrictive temperature (29°C), The presence of patches at both temperatures indicated that the mutant was non-autonomous. Such non-autonomous behaviour might be attributed to the existence of a substance capable of diffusing from the wild type tissue to supplement the mutant tissue. The experiments carried out showed that the presence or absence of mosaic patches could not be directly interpreted as demonstration of autonomous or non-autonomous properties of the mutant. Other factors such as the time of activity of the ts mutant and the type of tissue undergoing ring X loss affected mosaic tissue production. Therefore, the mere presence of mosaic tissue at 29°C could not be used as a criterion for the non-autonomous behaviour of the ts mutants. However, these mutants can be graded according to the degree of autonomy of ts lethality after alterations due to XO survival frequencies, lethal periods, and temperature-sensitive periods have been placed onmosaic frequencies at 29°C. Of the thirteen ts mutants studied, six can he classed as autonomous lethals. The others are equally autonomous as lethals but only in specific tissues, while others do not appear to be as autonomous. In fact, one of these may be considered non-autonomous.

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