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The genetic control of maternal effects on mutations recovered from X-rayed mature Drosophila sperm
Abstract:
Drosophila melanogaster males carrying a ring-X-chromosome were X-rayed and crossed to virgin females of 7 stocks, which had their second and third chromosomes systematically substituted. In the same experiment dominant lethals, sex-chromosome losses, and reciprocal translocations were recorded. Maternal effects on mutation fixation were observable as differences in the mutation frequencies observed with the different types of females. With the set of substitution stocks studied it was found that the maternal genotype strongly influences the frequencies of chromosome losses. The influences on classical chromosome-breakage phenomena, such as dominant lethals and translocations, however, are weak. The differences in the chromosome-loss frequencies may result either from different time intervals between insemination and the beginning of chromosome replication, and/or the efficiency of a repair system. One or more strong genetic factors responsible for such modifications could be located on the third chromosome. On the second chromosome, at best only weak factors are present.
Insights
Maternal genotype significantly impacts chromosome loss frequency in Drosophila melanogaster, while having minimal effect on dominant lethals and translocations. Genetic factors on the third chromosome appear most influential.
Area of Science:
- Genetics
- Developmental Biology
- Molecular Biology
Background:
- The maternal genotype can influence offspring mutation frequencies.
- Understanding these maternal effects is crucial for interpreting genotoxicity studies.
Purpose of the Study:
- To investigate maternal genotypic effects on mutation fixation in Drosophila melanogaster.
- To determine the influence of specific chromosomes (second and third) on mutation frequencies.
Main Methods:
- Irradiation of Drosophila melanogaster males with ring-X chromosomes.
- Crossing irradiated males to virgin females from 7 stocks with systematically substituted second and third chromosomes.
- Quantification of dominant lethals, sex-chromosome losses, and reciprocal translocations.
Main Results:
- Maternal genotype strongly influences sex-chromosome loss frequencies.
- Maternal genotype shows weak influence on dominant lethals and reciprocal translocations.
- Potential genetic factors modifying chromosome loss frequencies are located on the third chromosome.
Conclusions:
- Maternal genotype plays a significant role in modulating chromosome loss rates.
- The third chromosome harbors strong genetic factors influencing these rates, while the second chromosome has weaker effects.
- Differences in chromosome loss may relate to DNA replication timing or repair system efficiency.