DNA Damage in Yeast Cells Exposed to Pollutants

Jenn Hoskins
27th April, 2024

DNA Damage in Yeast Cells Exposed to Pollutants

Baker's yeast (Saccharomyces cerevisiae)

Photo adapted from: Austin 0201 / CC BY (Source)

Key Findings

  • In a Lebanese study, yeast cells exposed to penconazole and benzo(a)pyrene formed DNA adducts without showing cell toxicity
  • Penconazole caused peak DNA adduct formation during yeast's exponential growth, while benzo(a)pyrene caused adducts consistently
  • Yeast's ability to detect DNA adducts without cell death suggests it can reveal low-level genotoxicity that might be missed in other assays
Understanding the impact of environmental pollutants on living organisms is a critical aspect of modern toxicology. One of the tools used to assess this impact is the model organism Saccharomyces cerevisiae, commonly known as baker's yeast. Yeast has long been a staple in scientific research due to its simplicity and the ease with which it can be manipulated in the lab. A recent study by the Lebanese Agricultural Research Institute (LARI)[1] has further validated the use of yeast in molecular toxicity studies by examining the effects of the fungicide penconazole and the well-known carcinogen benzo(a)pyrene on yeast DNA. DNA adducts are segments of DNA bound to cancer-causing chemicals. Their formation is a critical step in the process that can lead to cancer, as these adducts can cause mutations when the DNA replicates. The LARI study aimed to detect the formation of these adducts in yeast cells when exposed to environmental toxicants. In the study, yeast cultures were exposed to two different concentrations of benzo(a)pyrene and a fixed concentration of penconazole. Benzo(a)pyrene is a polycyclic aromatic hydrocarbon known to be a potent mutagen and carcinogen, which forms DNA adducts as a part of its action. Penconazole, on the other hand, is a fungicide used to protect crops, but its impact on non-target organisms and potential genotoxicity is not fully understood. The researchers monitored the yeast's growth kinetics to see if the chemicals would slow down or stop the growth of the yeast, a sign of cytotoxicity, which means the chemical is toxic to cells. Surprisingly, no cytotoxicity was detected in any of the experiments, meaning that the yeast cells continued to grow despite the presence of the toxicants. However, both chemicals did induce the formation of DNA adducts, with penconazole showing a peak formation during the exponential growth phase and benzo(a)pyrene causing adducts across various tests. These findings are significant because they demonstrate that yeast can be a reliable bioindicator of DNA damage due to environmental pollutants. The ability to detect DNA adduct formation without cytotoxicity is particularly useful because it suggests that yeast can reveal sub-lethal levels of genotoxicity, which might go unnoticed in assays that only measure cell death or growth inhibition. The LARI study builds on previous research that has established yeast as a valuable model for studying DNA damage and repair. For instance, earlier studies have shown that UV irradiation causes dipyrimidine dimers to form in yeast DNA, and the roles of specific DNA polymerases in repairing these lesions have been examined[2]. These findings underscore the utility of yeast in understanding the mechanisms of DNA damage and repair, which are pertinent to assessing the mutagenic potential of environmental toxicants. Moreover, the use of yeast has been contrasted with other methods that rely on whole organisms to assess toxicity[3]. These whole-organism methods can be more complex and less convenient than using a simple model like yeast. The study by LARI further supports the notion that yeast can provide rapid and convenient measurements of cytotoxicity and genotoxicity, complementing more traditional toxicological assays. In the context of environmental monitoring, the ability to detect DNA adduction in yeast offers a promising avenue for early detection of potential genotoxic agents. Given that some chemicals can induce specific types of genetic damage without causing chromosome loss[4], the specificity of yeast assays could be instrumental in discerning the precise nature of genetic alterations induced by environmental pollutants. In conclusion, the LARI study has demonstrated that yeast can serve as an effective tool for detecting DNA adducts caused by environmental toxicants, such as penconazole and benzo(a)pyrene. This research not only reinforces the relevance of yeast in toxicological studies but also suggests that yeast could play a critical role in environmental biomonitoring, helping to identify potential genotoxic agents before they pose a significant risk to human health and the environment.

GeneticsBiochemEcology

References

Main Study

1) DNA adduct formation in Saccharomyces cerevisiae following exposure to environmental pollutants, as in vivo model for molecular toxicity studies.

Published 26th April, 2024

https://doi.org/10.1007/s11274-024-03989-x

Related Studies

2) The in vivo characterization of translesion synthesis across UV-induced lesions in Saccharomyces cerevisiae: insights into Pol zeta- and Pol eta-dependent frameshift mutagenesis.

Journal: Genetics, Issue: Vol 172, Issue 3, Mar 2006

3) Yeast Cell as a Bio-Model for Measuring the Toxicity of Fish-Killing Flagellates.

https://doi.org/10.3390/toxins13110821

4) Reevaluation of the 9 compounds reported conclusive positive in yeast Saccharomyces cerevisiae aneuploidy test systems by the Gene-Tox Program using strain D61.M of Saccharomyces cerevisiae.

Journal: Mutation research, Issue: Vol 260, Issue 2, Jun 1991


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