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Sterilizing effects of trimethylphosphate in Drosophila melanogaster
Abstract:
Trimethylphosphate (TMP) causes aspermia in D. melanogaster males. If larvae are allowed to develop on standard maize-meal medium containing 0.002 M TMP or greater, the enclosing adult males, when placed on uncontaminated medium, exhibit a period of temporary sterility. Between test groups the period of sterility is most variable at the doses of 0.002-0.004 M, but at 0.005 M or greater is approximately 11-12 days. Near-lethal doses of about 20 g/kg by abdominal injection produces a temporary sterility in adults, whereas oral doses up to 0.02 M are ineffective. Oogenesis in females is not affected by doses which cause temporary sterility in males. In adult male D. melanogaster, which were treated as larvae with 0.01 M TMP in the food medium, the basal region of testes and seminal vesicles do not contain spermatozoa. Cytological examinations of the spermatids reveal ultrastructural changes which are characteristic of those seen in X/O and sterile-mutant males; they contain incomplete axial fibre complexes, abnormal development of the mitochondrial derivatives, and nuclei which fail to elongate and condense. Evidence from cytological studies of larval testes suggests that the chemosterilizing effect of TMP is upon early primary spermatocytes. This is also supported by mating data.
Insights
Trimethylphosphate (TMP) induces temporary sterility in male fruit flies (D. melanogaster) by disrupting sperm development. This chemical exposure affects early spermatocytes, leading to abnormal sperm and infertility.
Area of Science:
- Toxicology
- Developmental Biology
- Genetics
Background:
- Trimethylphosphate (TMP) is a chemical agent with known biological effects.
- Understanding the mechanisms of chemical-induced sterility is crucial for reproductive biology research.
- Drosophila melanogaster serves as a model organism for studying genetic and developmental processes.
Purpose of the Study:
- To investigate the effects of Trimethylphosphate (TMP) on the reproductive system of adult male Drosophila melanogaster.
- To determine the specific developmental stage and cellular mechanisms underlying TMP-induced aspermia.
- To assess the impact of TMP on spermatogenesis and sperm ultrastructure.
Main Methods:
- Larval exposure to varying concentrations of TMP in the food medium.
- Administration of TMP via abdominal injection to adult males.
- Cytological examination of testes and spermatids from treated male D. melanogaster.
- Ultrastructural analysis of sperm development, including axial fiber complexes and mitochondrial derivatives.
- Mating assays to evaluate male fertility.
Main Results:
- Dietary TMP concentrations of 0.002 M or higher induced temporary sterility in adult male D. melanogaster that developed from treated larvae.
- Sterility period lasted approximately 11-12 days at TMP concentrations of 0.005 M or greater.
- Near-lethal doses (20 g/kg) via injection caused temporary sterility, while oral doses up to 0.02 M were ineffective.
- Cytological examination revealed ultrastructural changes in spermatids, including incomplete axial fiber complexes and abnormal mitochondrial derivatives.
- TMP exposure affected early primary spermatocytes, leading to abnormal sperm development and aspermia.
Conclusions:
- Trimethylphosphate (TMP) acts as a chemosterilant in male Drosophila melanogaster, primarily by affecting early spermatocytes.
- The observed ultrastructural changes in spermatids provide insights into the mechanism of TMP-induced male infertility.
- TMP-induced sterility in males does not affect oogenesis in females, suggesting a sex-specific effect.