Date of Award:

5-1-1971

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Zoology

Committee Chair(s)

James T. Bowman

Committee

James T. Bowman

Committee

J. R. Simmons

Committee

P. B. Carter

Committee

H. P. Stanley

Committee

E. J. Gardner

Abstract

The unstable Drosophila melanogaster mutants f3n (1-56.7 and wi (1-1.5) have been observed to revert frequently to wild type with similar parameters of reversion. Therefore, it was the objective of this investigation to critically compare the properties of the f3n reversion event to previously reported data on wi reversion and to determine if the two phenomena are truly similar. After confirming the previously reported spontaneous and X-ray-induced f3n reversion frequencies, it was determined that f3n reversion events in homozygous females are independent of recombination of outside markers. This is consistent with the properties of wi reversion. Furthermore, like wi, the spontaneous f3n reversion frequency in males is significantly lower than its frequency in females. In contrast to wi, a critical study indicated that a synaptic partner is not essential for reversion of f3n. Spontaneous and X-ray-induced reversions were observed in females heterozygous for the deficiency, Df(1)B263-20. Therefore, it seems unlikely that reversion of the two mutants occurs by the same mechanisms. The data from this study indicated that the frequent reversion of f3n is not a result of events peculiar to the gene itself. A sex-linked mutator gene apparently affects f3n reversion events, the f3n reversion frequency in females being reduced significantly by replacement of the mutator. This mutator gene apparently is located in the X-chromosome region B (1-57.0) to the right end of the X-chromosome, and it does not seem to affect f3n reverison events in males.

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