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Published on: July 10, 2018
Investigation of coffee in Drosophila genotoxicity tests
Abstract:
Two preparations of coffee (instant coffee and freeze-dried home-brew coffee) were tested in different mutagenicity assays in germ cells as well as in somatic cells of Drosophila melanogaster. The three end-points assayed in germ cells were sex-linked recessive lethals (mainly gene mutations and small chromosome aberrations), dominant lethals (cytotoxic effects as well as genotoxic effects) and sex-chromosome losses (chromosome breakage and non-disjunction). The aqueous coffee solutions were fed either to adult male flies for 3 days or to growing larvae during the whole larval development. Treated males were crossed with appropriately marked females, and the different genetic end-points were analysed in the F1 or F2 generation. The test concentrations (instant coffee 4% (w/v), home-brew coffee 3%) were acutely toxic in adult males (killing approximately 75 and 90% of the exposed flies, respectively). No increase in deaths was caused in larvae by the same concentrations. Only cytotoxic effects were observed in the test for dominant lethals. No conclusive genotoxic effects could be detected in any of the three germ cell assays. The coffee preparations were also tested for induction of mutation and mitotic recombination in somatic cells of the wing imaginal disc. Larvae trans-heterozygous for two recessive wing hair markers were fed high concentrations of the coffees for varying periods of time. Wings of surviving adult flies were analysed for mosaic spots. Twin spots exhibiting both mutant phenotypes are produced by mitotic recombination; single spots showing one or the other phenotype are the result of somatic mutation, such as gene mutation or deletion, or of mitotic recombination. Both coffees had weak effects on normal (repair-proficient) cells as well as on excision repair-defective cells in this assay. Additional experiments with pure caffeine and decaffeinated coffee show that these weak effects in somatic cells were most probably caused by the caffeine present in the two coffees.
Insights
Coffee consumption was evaluated for mutagenicity in Drosophila melanogaster. While toxic to adult flies, neither instant nor home-brew coffee showed conclusive genotoxic effects in germ cells, though weak somatic cell effects were observed, likely due to caffeine.
Area of Science:
- Toxicology
- Genetics
- Drosophila melanogaster research
Background:
- Coffee is a widely consumed beverage with potential health implications.
- Previous studies on coffee's genotoxicity have yielded mixed results.
- Drosophila melanogaster serves as a model organism for assessing mutagenicity.
Purpose of the Study:
- To investigate the mutagenic and genotoxic potential of instant and home-brew coffee.
- To evaluate effects on both germ and somatic cells in Drosophila melanogaster.
- To determine if observed effects are attributable to caffeine.
Main Methods:
- Two coffee preparations (instant and freeze-dried home-brew) were tested.
- Mutagenicity assays in Drosophila melanogaster germ cells: sex-linked recessive lethals, dominant lethals, and sex-chromosome losses.
- Somatic cell assays in Drosophila melanogaster wing imaginal discs for mutation and mitotic recombination.
- Administration via feeding to adult males or larvae.
- Analysis of F1/F2 generations for germ cell effects and mosaic spots in wings for somatic cell effects.
Main Results:
- Coffee preparations were acutely toxic to adult male flies but not to larvae at tested concentrations.
- No conclusive genotoxic effects were observed in germ cell assays (recessive lethals, dominant lethals, sex-chromosome losses).
- Weak mutagenic and mitotic recombination effects were detected in somatic cells, linked to caffeine content.
Conclusions:
- Coffee consumption, at the tested concentrations, did not demonstrate significant genotoxic effects in Drosophila melanogaster germ cells.
- Observed weak effects in somatic cells are likely attributed to caffeine.
- Further research may be needed to fully elucidate the complex interactions of coffee components with cellular processes.
