Evolutionary engineering and molecular characterization of a caffeine-resistant Saccharomyces cerevisiae strain

Caffeine is a naturally occurring alkaloid, where its major consumption occurs with beverages such as coffee, soft drinks and tea. Despite a variety of reports on the effects of caffeine on diverse organisms including yeast, the complex molecular basis of caffeine resistance and response has yet to be understood. In this study, a caffeine-hyperresistant and genetically stable Saccharomyces cerevisiae mutant was obtained for the first time by evolutionary engineering, using batch selection in the presence of gradually increased caffeine stress levels and without any mutagenesis of the initial population prior to selection. The selected mutant could resist up to 50 mM caffeine, a level, to our knowledge, that has not been reported for S. cerevisiae so far. The mutant was also resistant to the cell wall-damaging agent lyticase, and it showed cross-resistance against various compounds such as rapamycin, antimycin, coniferyl aldehyde and cycloheximide. Comparative transcriptomic analysis results revealed that the genes involved in the energy conservation and production pathways, and pleiotropic drug resistance were overexpressed. Whole genome re-sequencing identified single nucleotide polymorphisms in only three genes of the caffeine-hyperresistant mutant; PDR1, PDR5 and RIM8, which may play a potential role in caffeine-hyperresistance. Graphic abstrac

Evolutionary Engineering of an Iron-Resistant Saccharomyces cerevisiae Mutant and Its Physiological and Molecular Characterization

Iron plays an essential role in all organisms and is involved in the structure of many biomolecules. It also regulates the Fenton reaction where highly reactive hydroxyl radicals occur. Iron is also important for microbial biodiversity, health and nutrition. Excessive iron levels can cause oxidative damage in cells. Saccharomyces cerevisiae evolved mechanisms to regulate its iron levels. To study the iron stress resistance in S. cerevisiae, evolutionary engineering was employed. The evolved iron stress-resistant mutant “M8FE” was analysed physiologically, transcriptomically and by whole genome re-sequencing. M8FE showed cross-resistance to other transition metals: cobalt, chromium and nickel and seemed to cope with the iron stress by both avoidance and sequestration strategies. PHO84, encoding the high-affinity phosphate transporter, was the most down-regulated gene in the mutant, and may be crucial in iron-resistance. M8FE had upregulated many oxidative stress response, reserve carbohydrate metabolism and mitophagy genes, while ribosome biogenesis genes were downregulated. As a possible result of the induced oxidative stress response genes, lower intracellular oxidation levels were observed. M8FE also had high trehalose and glycerol production levels. Genome re-sequencing analyses revealed several mutations associated with diverse cellular and metabolic processes, like cell division, phosphate-mediated signalling, cell wall integrity and multidrug transporters

Maternal plasma and placenta microRNAs expression profiling of preeclamptic pregnancies by microarray technology

Preeclampsia (PE) is one of the leading causes of maternal and fetal morbidity and mortality, occurring usually in the second half of pregnancy and affecting approximately 5-8% of pregnancies in the world. miRNAs play critical role in the regulation of placental development processes. We aimed to determine specific novel miRNAs for early diagnosis of preeclampsia which is one of the most dangerous pregnancy diseases. In this study 72 samples, maternal age 22 2-fold) in maternal plasma were differentially expressed in PE and control group. However, five miRNAs were validated by qRT-PCR. Once validated miRNAs have been searched in databases for their target genes and function, it has been shown that there are some preeclampsia related pathways as a target such as angiogenesis, cardiovascular, hypertension, placental abruption and preeclampsia disorders. Differentially expressed and validated plasma miRNAs might be used as notable biomarkers for non-invasive early diagnosis of preeclampsia and treatment of disease. (C) 2017 Elsevier Ltd. All rights reserved

The Effect of CYP1A1 and GSTM1 Gene Polymorphisms in Bladder Cancer Development in a Turkish Population

Background: The aim of this study was to investigate a possible association of the CYP1A1 Ile462Val and GSTM1 null polymorphisms with the risk of developing bladder cancer in a Turkish population. Patients and Methods: The study constituted 176 patients with bladder cancer and 97 healthy individuals. Evaluation of CYP1A1 Ile462Val gene polymorphism was performed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). GSTM1 null gene polymorphism was exclusively determined by PCR. Our results were examined by statistical analyses. Results: There were no significant differences in CYP1A1 genotype frequencies between patients and controls. Furthermore, the frequency of GSTM1 null genotype was higher in patients compared to controls, but it did not reach significance (p=0.622 chi(2)=0.243 OR=0.94 95% CI=0.75-1.18). Significance was discovered in combined analysis of CYP1A1 and GSTM1 genotypes. In the present study, GSTM1 null genotype with CYP1A1 Ile/Ile genotype combination was significantly more frequent in the patient group than in controls (p=0,04, chi(2)=4.217). At the same time, possessing both GSTM1 null genotype and CYP1A1 Val variants (Ile/Val+Val/Val) were significantly higher in control group than in patients (p=0.017, chi(2)=5.468). When the pathological tumor grades were assessed, the frequency of CYP1A1 Val mutant variant with GSTM1 null genotype combination was higher in patients with medium and high-grade tumors than in those with low-grade tumors (p=0.06, chi(2)=3.527, OR=1.36 95% CI=1.03-1.78). Conclusion: We suggest that the CYP1A1 Ile/lle genotype with GSTM1 null genotype combination may contribute to the development of bladder cancer in this Turkish population

Genomic, transcriptomic and physiological analyses of silver‐resistant Saccharomyces cerevisiae obtained by evolutionary engineering

International audienceSilver is a non-essential metal used in medical applications as an antimicrobial agent, but it is also toxic for biological systems. To investigate the molecular basis of silver resistance in yeast, we employed evolutionary engineering using successive batch cultures at gradually increased silver stress levels up to 0.25-mM AgNO(3)in 29 populations and obtained highly silver-resistant and genetically stableSaccharomyces cerevisiaestrains. Cross-resistance analysis results indicated that the silver-resistant mutants also gained resistance against copper and oxidative stress. Growth physiological analysis results revealed that the highly silver-resistant evolved strain 2E was not significantly inhibited by silver stress, unlike the reference strain. Genomic and transcriptomic analysis results revealed that there were mutations and/or significant changes in the expression levels of the genes involved in cell wall integrity, cellular respiration, oxidative metabolism, copper homeostasis, endocytosis and vesicular transport activities. Particularly the missense mutation in theRLM1gene encoding a transcription factor involved in the maintenance of cell wall integrity and with 707 potential gene targets might have a key role in the high silver resistance of 2E, along with its improved cell wall integrity, as confirmed by the lyticase sensitivity assay results. In conclusion, the comparative physiological, transcriptomic and genomic analysis results of the silver-resistantS. cerevisiaestrain revealed potential key factors that will help understand the complex molecular mechanisms of silver resistance in yeast