Related Experiment Videos
The role of feeding rejection in Drosophila mutation assays
Abstract:
The frequencies of sex-linked recessive lethal mutations recovered in the male post-meiotic germ cells of Drosophila after feeding on solutions containing a mutagen (either 1 mM methyl methanesulfonate, MMS or 2 mM ethyl methanesulfonate, EMS) and 5-bromo-2-deoxyuridine (BUdR) were significantly lower than the frequencies observed after treatment with the mutagen alone. In an attempt to explain the apparent 'protective' effect of BUdR, the feeding behavior of the flies was monitored for differences in the uptake of the mutagen-containing solution in the presence and absence of BUdR. This was accomplished by measuring the uptake of [14C]sucrose. The results indicated that the uptake of the feeding solution is inhibited by the presence of the selected concentration of BUdR (1.0 or 32.5 mM). Such a reduced uptake of the mutagen could alone account for the reduction in mutational yields noticed in treatments containing mutagen + BUdR compared to the ones with the mutagen alone. These results emphasize the need to monitor the feeding behavior of flies in experiments involving adult feeding.
Insights
5-bromo-2-deoxyuridine (BUdR) reduces mutagen uptake in Drosophila, lowering mutation rates. This highlights the importance of monitoring feeding behavior in mutagenicity studies.
Area of Science:
- Genetics
- Toxicology
- Drosophila melanogaster research
Background:
- Sex-linked recessive lethal mutations are studied to assess mutagenicity.
- 5-bromo-2-deoxyuridine (BUdR) is a thymidine analog that can be incorporated into DNA.
- Previous studies suggested potential interactions between BUdR and mutagens.
Purpose of the Study:
- To investigate the effect of BUdR on the frequency of sex-linked recessive lethal mutations induced by methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS) in Drosophila.
- To determine if BUdR exhibits a protective effect against mutagen-induced mutations.
- To elucidate the mechanism behind any observed protective effect, focusing on mutagen uptake.
Main Methods:
- Drosophila melanogaster males were fed solutions containing MMS or EMS, with or without BUdR.
- Mutation frequencies were assessed by scoring sex-linked recessive lethal mutations in post-meiotic germ cells.
- [14C]sucrose was used to quantify the uptake of feeding solutions by the flies.
- Feeding behavior and solution uptake were compared between treatment groups.
Main Results:
- The presence of BUdR significantly reduced the frequency of induced mutations compared to mutagens alone.
- BUdR significantly inhibited the uptake of the feeding solution containing mutagens.
- Reduced mutagen uptake due to BUdR can explain the observed decrease in mutation rates.
Conclusions:
- BUdR appears to reduce mutagenicity not by direct chemical interaction, but by decreasing the flies' intake of the mutagen.
- These findings underscore the critical need to assess and control for feeding behavior in adult feeding studies involving mutagens.
- The study provides a mechanistic explanation for the apparent protective effect of BUdR in mutagenicity assays.