INTERACTIONS BETWEEN SEX-TRANSFORMATION MUTANTS OF DROSOPHILA MELANOGASTER. I. HEMOLYMPH VITELLOGENINS AND GONAD MORPHOLOGY

[摘要] In Drosophila, vitellogenins (yolk protein precursors) are synthesized by the female fat body, secreted into the hemolymph and subsequently taken up by the developing oocytes. The male fat body, on the other hand, does not do this even when immature ovaries are transplanted into the body cavity and grow. Thus, the hemolymph vitellogenins serve as an easily detectable sexually dimorphic biochemical marker.——We have examined hemolymph vitellcgenins by SDS polyacrylamide gel electrophoresis in flies carrying various sex-transformation mutants ( dsx, tra, tra-2 and tra-20TF ) singly and in all possible combinations. Chromosomal females homozygous for tra or tra-2 have no detectable hemolymph vitellogenins, while those homozygous for tra-20TR exhibit appreciable levels of these proteins. Flies homozygous for dsz, both X / X and X / Y , have hemolymph vitellogenins, although the amount is consistently smaller in the latter. Indeed, X / Y; dsx/dsx is the only genotype in which hemolymph vitellogenins are detected in the X/Y flies. A clear hierarchy of epistasis exists among these sex-transformation mutants when they are examined in various combinations: dsx > tra, tra-2 > tra-20TF . Moreover, an interaction between tra-20TF and tra was seen in these experiments: X / X; tra-20TF/tra-20TF flies show the presence of only a trace of hemolymph vitellogenins when they are made heterozygous for tra . These results, combined with observations on gonad morphology, are discussed with respect to the BAKERa nd RIDGE (1980) hypothesis of sex determination.

[学科分类] 医学（综合）