ABSTRACT
Bisphenol A (BPA) is used for the production of plastics and epoxy resins, which are part of packaging materials for food and beverages, and can migrate into food and the environment, thus exposing human beings to its effects. Exposure to BPA has been associated with oxidative stress, cell cycle changes, and genotoxicity, and is mediated by its known endocrine-disrupting activity. Possible BPA cytotoxicity without mediation by estrogen receptors has been reported in the literature. Here, we show the toxic effects of BPA by live-cell imaging on the fission yeast Schizosaccharomyces pombe, an experimental model lacking estrogen receptors, which were in line with data from flow cytometry on intracellular oxidation (76.4 ± 14.4 and 19.4 ± 16.1% of fluorescent cells for BPA treatment and control, respectively; p < 0.05) as well as delay in cell cycle progression (after 90 min of experiment, 48.4 ± 4.30 and 64.6 ± 5.46% of cells with a 4C DNA content for BPA treatment and control, respectively; p < 0.05) upon exposure to BPA. These results strongly support the possibilities that BPA-induced cell cycle changes can be independent of estrogen receptors and that live-cell imaging is a powerful tool for genotoxic analysis.
Subject(s)
Benzhydryl Compounds/toxicity , Cell Cycle/drug effects , Phenols/toxicity , Reactive Oxygen Species/metabolism , Schizosaccharomyces/drug effects , DNA Damage/drug effects , Endocrine Disruptors/toxicity , Oxidative Stress/drug effects , Schizosaccharomyces/cytology , Schizosaccharomyces/genetics , Schizosaccharomyces/metabolismABSTRACT
OBJECTIVES: Bisphenol A (BPA) is an endocrine disruptor which has been shown to be a harmful compound for living organisms. It is the main component of the most commonly used plastic products such as plastic bottles, food cans and containers or dental fillings, and other medical aids. Recently, it has become a new environmental pollutant. The current knowledge about the BPA effects (including genotoxic one) on different cells is in many cases contradictory. Thus, the aim of the paper is to study the potential genotoxic effect of BPA. METHODS: An observation of the genotoxic activity of BPA on human lymphocytes was evaluated by using the alkaline comet assay and a modified comet assay with bacterial DNA repair enzyme Fpg. The potential DNA-protective effect of BPA was tested by using the DNA-topology assay. RESULTS: The results show that rising concentrations of BPA increase the risk of DNA double-strand breaks and modified purines in human lymphocytes. Interestingly, BPA shows an ability to protect plasmid DNA from the damage of iron ions in cell-free system. CONCLUSIONS: BPA itself does not induce genotoxic effect to DNA. However, BPA treatment of human lymphocytes leads to the induction of DNA damage. The proposed mechanism of BPA action in the human lymphocytes could be mediated by cell metabolism that induces an oxidative stress and ROS formation. ROS subsequently attack DNA and thus induce DNA damage. According to our results, BPA can be included in the group of substances with dual effects involving genotoxic and DNA-protective activity.
Subject(s)
Benzhydryl Compounds/toxicity , DNA Breaks, Double-Stranded/drug effects , DNA Damage/drug effects , DNA/drug effects , Environmental Pollutants/toxicity , Lymphocytes/drug effects , Oxidative Stress/drug effects , Phenols/toxicity , Plasmids/drug effects , Comet Assay , DNA/genetics , DNA Damage/genetics , Endocrine Disruptors/toxicity , Estrogens, Non-Steroidal/toxicity , Free Radical Scavengers/toxicity , Humans , Lymphocytes/metabolism , Plasmids/genetics , Purines/metabolism , Reactive Oxygen Species/metabolismABSTRACT
As future scientists, university students need to learn how to avoid making errors in their own manuscripts, as well as how to identify flaws in papers published by their peers. Here we describe a novel approach on how to promote students' ability to critically evaluate scientific articles. The exercise is based on instructing teams of students to write intentionally flawed manuscripts describing the results of simple experiments. The teams are supervised by instructors advising the students during manuscript writing, choosing the 'appropriate' errors, monitoring the identification of errors made by the other team and evaluating the strength of their arguments in support of the identified errors. We have compared the effectiveness of the method with a journal club-type seminar. Based on the results of our assessment we propose that the described seminar may effectively complement the existing approaches to teach critical scientific thinking. © 2017 by The International Union of Biochemistry and Molecular Biology, 46(1):22-30, 2018.
