ISSN:
0002-9106
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The aberrant sex-ratio mutation in D. simulans used for this study is a temperature-sensitive autosomal recessive. Homozygous males raised at 16°C produce about 2% in F1, but those raised at 26°C, have a normal sex ratio. Ultrastructural studies of spermatogenesis have revealed many anomalies in the germ cells of flies raised at 16°C, but the same flies raised at 26°C had few anomalies. The earliest spermatogenic stage with noticeable abnormalities was the primary spermatocyte. In later stages there were pronounced abnormalities in nucleoli, chromatin condensation, nuclear shape, Golgi complex, acrosome, and microtubules. There is asynchronous differentiation of spermatids within a bundle. Some of the abnormalities encountered are disorganization or loss of microtubules of the axoneme, degenerating nebenkern derivatives, and increased numbers of lysosomes, multilamellate bodies, and multivesicular bodies. At the lower temperature, more than half of the sperm within the same bundle were found in different stages of degeneration. Genetic analysis suggests that the sex-ratio gene causes abnormalities and degeneration of most of the Y-bearing sperm. However, counts of abnormal sperm at the ultrastructural level indicate that some X-bearing sperm must also undergo degeneration. These observations show that the sex-ratio gene is of variable penetrance at different temperatures in the primary spermatocyte and of differential penetrance in X- and Y-bearing sperm.
Additional Material:
20 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aja.1001570208
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