Bioassay of Pesticide Lindane Using Yeast-DNA Microarray Technology

Influence of tetraconazole on the proteome profile of Saccharomyces cerevisiae Lalvin T73™ strain

This work aimed to evaluate the modifications on the proteome profile of Saccharomyces cerevisiae T73™ strain as a consequence of its adaptive response to the presence of tetraconazole molecules in the fermentation medium. Pasteurised grape juices were separately supplemented with tetraconazole or a commercial formulation containing 12.5% w/v of tetraconazole at two concentration levels. In addition, experiments without fungicides were developed for comparative purposes. Proteome profiles of yeasts cultured in the presence or absence of fungicide molecules were different. Independently of the fungicide treatment applied, the highest variations concerning the control sample were observed for those proteins involved in metabolic processes, especially in the metabolism of nitrogen compounds. Tetraconazole molecules altered the abundance of several enzymes involved in the biosynthesis of amino acids, purines, and ergosterol. Moreover, differences in the abundance of several enzymes of the TCA cycle were found. Changes observed were different between the active substance and the commercial formulation. SIGNIFICANCE: The presence of fungicide residues in grape juice has direct implications on the development of the aromatic profile of the wine. These alterations could be related to changes in the secondary metabolism of yeasts. However, the molecular mechanisms involved in the response of yeasts to fungicide residues remains quite unexplored. Through this exhaustive proteomic study, alterations in the amino acids biosynthesis pathways due to the presence of the tetraconazole molecules were observed. Amino acids are precursors of some important higher alcohols and ethyl acetates (such as methionol, 2-phenylethanol, isoamyl alcohol or 2-phenylacetate). Besides, the effect of tetraconazole on the ergosterol biosynthesis pathway could be related to a higher production of medium-chain fatty acids and their corresponding ethyl acetates.

Astaxanthin supplementation reduces dichlorvos-induced cytotoxicity in Saccharomyces cerevisiae

This study evaluates the protective effect of astaxanthin against dichlorvos cytotoxicity in yeast Saccharomyces cerevisiae. Dichlorvos induce a dose-dependent cytotoxicity in yeast cells, which is mediated by oxidative stress. Our experimental results showed pre-treatment with astaxanthin enhances cell viability by 20-30% in yeast cells exposed to dichlorvos. A decrease in DCF fluorescence intensity and lipid peroxidation, increased SOD activity, and glutathione levels in astaxanthin-treated cells indicate that astaxanthin protected the cells against dichlorvos-induced oxidative stress. Reduced chromatin condensation and nuclear fragmentation in astaxanthin pre-treated cells also indicate that astaxanthin rescued the cells from dichlorvos-induced apoptosis. Our overall results suggest that dichlorvos induces oxidative stress-mediated cytotoxicity in yeast cells, and that was rescued by astaxanthin pre-treatment.

Saccharomyces cerevisiae as a model in ecotoxicological studies: A post-genomics perspective

The budding yeast Saccharomyces cerevisiae represents a well-consolidated and widely used eukaryotic model, with a number of features that make it an ideal organism to carry out functional toxicological studies. Several advantages are permitted by the use of yeast cells, as the possibility to identify molecular biomarkers, unknown mechanisms of action and novel potential targets. Thanks to the evolutionary conservation, yeast can provide also useful clues allowing the prioritization of more complex analyses and toxicity predictions in higher eukaryotes. The last two decades were incredibly fruitful for yeast "omics", but referring to the analysis of the effects of pesticides on yeast much still remains to be done. Furthermore, a deeper knowledge of the effects of environmental pollutants on biotechnological processes associated with the use of yeasts is to be hoped.

Insights into the mechanisms of toxicity and tolerance to the agricultural fungicide mancozeb in yeast, as suggested by a chemogenomic approach

Abstract Saccharomyces cerevisiae was used to uncover the mechanisms underlying tolerance and toxicity of the agricultural fungicide mancozeb, linked to cancer and Parkinson's disease development. Chemogenomics screening of a yeast deletion mutant collection revealed 286 genes that provide protection against mancozeb toxicity. The most significant Gene Ontology (GO) terms enriched in this dataset are associated to transcriptional machinery, vacuolar organization and biogenesis, intracellular trafficking, and cellular pH regulation. Clustering based on physical and genetic interactions further highlighted the role of oxidative stress response, protein degradation and carbohydrate/energy metabolism in mancozeb stress tolerance. Mancozeb was found to act in yeast as a thiol-reactive compound, but not as a free radical or reative oxygen species (ROS) inducer, leading to massive oxidation of protein cysteins, consistent with the requirement of genes involved in glutathione biosynthesis and reduction and in protein degradation to provide mancozeb resistance. The identification of Botrytis cinerea homologues of yeast mancozeb tolerance determinants is expected to guide studies on mancozeb mechanisms of action and tolerance in phytopathogenic fungi. The generated networks of protein-protein associations of yeast mancozeb tolerance determinants and their human orthologues share a high degree of similarity. This toxicogenomics analysis may, thus, increase the understanding of mancozeb toxicity and adaptation mechanisms in humans.

A Saccharomyces cerevisiae-based bioassay for assessing pesticide toxicity

This study evaluates the toxic effect of three pesticides (Azoxystrobin, Cymoxanil, and Diuron) on the yeast Saccharomyces cerevisiae for the development of a new bioassay based on inhibition of S. cerevisiae metabolic activity at the level of adenosine-5-triphosphate (ATP) synthesis, as compared with two different toxicity tests based on inhibition of Daphnia magna mobility (NF EN ISO 6341) and inhibition of Vibrio fisheri activity (NF EN ISO 11348). The S. cerevisiae bioassay is cheaper and 96 times faster than the D. magna toxicity bioassay, but has lower sensitivity. It is as fast as the V. fisheri bioassay and more sensitive. Thus, this new toxicity test can be proposed for rapid detection of pesticide residues in environmental samples as a complement to the more expensive and time-consuming D. magna toxicity test.

Identification of genes expressed as a result of lindane exposure in Oreochromis niloticus using differential display

In order to assess the effect of lindane exposure on gene expression in tilapia (Oreochromis niloticus), twenty male fish were individually weighted and injected intraperitoneally with a single dose of lindane (19.09 mg/kg bw) using corn oil as a carrier vehicle, while a second group of twenty male fish (controls) was only injected with the carrier vehicle. Groups of four fish each were then sacrificed at 3, 6, 12, 18 and 24h after treatment application and total RNA was extracted from liver tissue. The differential display (DD) technique was then used to identify differentially expressed cDNA fragments between treatment and control fish. A total of fifty cDNA fragments were isolated and sequenced, from which only four showed homology with genes previously described in other fish species, namely the immunoglobulin heavy chain (IgH), coagulation factor V (FV), casein kinase 2 alpha (CK2a), and the receptor protein-tyrosine-like phosphatase (RPT-LP). The expression of such genes was confirmed using quantitative real time-polymerase chain reaction (QRT-PCR). Results showed that lindane exposure triggered the differential expression of these genes during the first 6, 18 and 24h subsequent to treatment application, suggesting that lindane exposure can trigger a rapid immune system response in tilapias.

Environmental genomics: mechanistic insights into toxicity of and resistance to the herbicide 2,4-D

Genomic information and tools are beginning to be used to increase our understanding of how organisms of all types interact with their environment. The study of the expression of all genes, at the genome, transcriptome, proteome and metabolome level, in response to exposure to a toxicant, is known as toxicogenomics. Here, we show how this new field of environmental genomics has enhanced the development of fundamental knowledge on the mechanisms behind the toxicity of and resistance to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Although 2,4-D is one of the most successfully and widely used herbicides, its intensive use has led to the emergence of resistant weeds and might give rise to several toxicological problems when present in concentrations above those recommended. This review summarizes recent mechanistic insights into 2,4-D toxicity and the corresponding adaptive responses based on studies carried out using Saccharomyces cerevisiae and Arabidopsis thaliana as model organisms.

Genome-wide analysis of the response to protein glycosylation deficiency in yeast

Protein modification by glycosylation occurs through an essential biochemical pathway that produces mannosyl side chain substrates, which are covalently attached to proteins in the endoplasmic reticulum. We used DNA microarray analysis to characterize the cellular response to a conditional defect (pmi40-101) in the protein glycosylation pathway. Expression profiles were obtained from DNA microarrays containing essentially every gene from Saccharomyces cerevisiae. We validated the microarray analysis by examining the expression patterns of induced genes using transcriptional lacZ fusions. The major class of genes differentially expressed in the glycosylation mutant overlapped significantly with that of a starvation response and included those required for gluconeogenesis, the tricarboxylic acid and glyoxylate cycles, and protein and amino acid biosynthesis. Two mitogen-activated protein (MAP) kinase pathways were also activated in the mutant, the filamentous growth and protein kinase C pathways. Taken together, our results suggest that a checkpoint is activated in response to a protein glycosylation defect, allowing the cell to mount an adaptive response by the activation of multiple MAP kinase pathways.