Comparative Genomic Screen in Two Yeasts Reveals Conserved Pathways in the Response Network to Phenol Stress

Two-Omics Probe on the Potential of Pseudomonas sp. GDMCC 1.1703 Under Phenol Stress

Pseudomonas sp. harbors genetic diversity and readily adapts to environmental challenges, conferring upon it the ability to remediate. It is important to genetically determine the effects of bacterial application. The two-omics integration approach may shed more light on Pseudomonas isolates, filling the knowledge gap between genetic potential and dynamic function. In the present study, a strain from the Xi River was isolated using benzene-selective enrichment medium and phylogenetically identified as Pseudomonas sp. GDMCC 1.1703 by 16S rRNA gene sequencing. Its phenol degradability was optimally assessed at a rate of 45.7% (by statistics P < 0.05) in 12 h with a 200 mg/L concentration. Genomics and transcriptomics analyses were successively used to identify the genes and pathways responsible for phenol degradation. At least 42 genes were genomically identified to be involved in xenobiotic biodegradation. The degradative genes clustered into operons were hypothesized to have evolved through horizontal gene transfer. On the basis of genomic authentication, transcriptome analysis dynamically revealed that phenol degradation and responsive mechanisms were both upregulated as defense between the Ctrl (control) and PS (phenol-stressed) groups. Quantitative reverse transcription-PCR not only validated the key genes identified via RNA sequencing but also consistently confirmed the realistic intracellular expression. The approach of omics integration, which is effective in exploring the potential of isolates, will hopefully become an established method for determining the remediation potential of a candidate for development.

Expression of Mug14 is regulated by the transcription factor Rst2 through the cAMP-dependent protein kinase pathway in Schizosaccharomyces pombe

The cAMP-dependent protein kinase (Pka1) regulates many cellular events, including sexual development and glycogenesis, and response to the limitation of glucose, in Schizosaccharomyces pombe. Despite its importance in many cellular events, the targets of the cAMP/PKA pathway have not been fully investigated. Here, we demonstrate that the expression of mug14 is induced by downregulation of the cAMP/PKA pathway and limitation of glucose. This regulation is dependent on the function of Rst2, a transcription factor that regulates transition from mitosis to meiosis. The loss of the C2H2-type zinc finger domain in Rst2, termed Rst2 (C2H2∆), abolished the induction of Mug14 expression. Upon deletion of the stress starvation response element of the S. pombe (STREP: CCCCTC) sequence, which is a potential binding site of Rst2 on mug14, in the pka1∆ strain, its induction was abolished. The expression of Mug14 was significantly reduced and delayed by the limitation of glucose and also by nitrogen starvation in the rst2∆ strain. Mug14 is known to share a common function with Mde1 and Mta3 in the methionine salvage pathway, but the expression of mde1 and mta3 mRNAs was not enhanced by pka1 deletion and limitation of glucose. We conclude that the expression of Mug14 is upregulated by Rst2 under the control of the cAMP/PKA signaling pathway, which senses the limitation of glucose.

Fission Yeast Schizosaccharomyces pombe: A Unicellular "Micromammal" Model Organism

The fission yeast Schizosaccharomyces pombe is a rod-shaped unicellular eukaryote, well known for its contributions as a model organism for our understanding of regulation and conservation of the eukaryotic cell cycle. As a yeast divergent from the budding yeast Saccharomyces cerevisiae, S. pombe shares more common features with humans including gene structures, chromatin dynamics, and the prevalence of introns, as well as the control of gene expression through pre-mRNA splicing, epigenetic gene silencing, and RNAi pathways. With the advent of new methodologies for research, S. pombe has become an increasingly used model to investigate various molecular and cellular processes over the last 50 years. Also, S. pombe serves as an excellent system for undergraduate students to obtain hands-on research experience. Versatile experimental approaches are amenable using the fission yeast system due to its relative ease of maintenance, its inherent cellular properties, its power in classic and molecular genetics, and its feasibility in genomics and proteomics analyses. This article provides an overview of S. pombe's rise as a valuable model organism and presents examples to highlight the significance of S. pombe as a unicellular "micromammal" in investigating biological questions. We especially focus on the advantages of and the advancements in using fission yeast for studying biological processes that are characteristic of metazoans to decipher the underlining molecular mechanisms fundamental to all eukaryotes. © 2021 Wiley Periodicals LLC.

Endocrine-Independent Cytotoxicity of Bisphenol A Is Mediated by Increased Levels of Reactive Oxygen Species and Affects Cell Cycle Progression

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.