Abudureyimu MAIHEBUBAI has just completed her PhD from Gazi University and preparing her postdoctoral program in abroad. During her graduate studying, she has published 6 papers in reputed journals and has attended many international congresses.
Yeasts not only play an important role in flavor and texture development during the production of cheese, also have shown probiotic effects on human health. In this study, four yeast isolates from Turkish cheeses were characterized to species level by phenotypic criteria using API ID 32 microbial identification kits and 18S rRNA sequence analysis. Three of them identified as Pichia kudriavzeii (M16, M17, M57), while another one was Kluyveromyces marxianus (M29). Yeast strains were tested for their ability to survive in simulated gastric juice and intestinal environment. The survival of all tested yeasts was 88.9-145% after 4 hours of incubation in media with the addition of 1g/L pancreatin and 46.3-80.4% after 3 hours of incubation in media with the addition of 3g/L pepsin (pH 1.5). All yeast strains were able to assimilate cholesterol in the range of 9,3-28,8% over a 48 h incubation. The DPPH radical scavenging activity of yeast strains was ranging between 75.1-80.5%. According to these results, the yeast strains could be considered as co-culture or probiotic in the preparation of fermented dairy products for contributing to the quality and health related functional properties of products.
Alexia Muguet has a master in marine ecology from the Université Pierre et Marie Curie - Paris VI (France) (2014) and a master in microbiology from the Université de Bretagne Occidentale (France) (2015). She previously worked on microalgae ecophysiology before starting studying microorganisms at molecular level. During her master internship, she worked on the replication helicase MCM from Pyrococcus abyssi, an Euryarchaeota. As PhD student at Université de Sherbrooke (Québec), she is studying DNA repair mechanisms and chromatin on Saccharomyces cerevisiae. Her main work is analyzing the rRNA gene proteome linked to UV radiation and Nucleotide Excision Repair to highlight proteins involved in chromatin repair-dependent modifications. Alexia participated in two published papers and in in-redaction one.
The chemotherapeutic agent Hydroxyurea (HU) inhibits the ribonucleotide reductase preventing the synthesis of dNTPs. Consequently, DNA replication is inhibited and cells arrest in G1/early S-phase of the cell cycle. Additionally, yeast exposed to the natural pheromone ?-factor arrest cell division in G1. Cell growth hinges on the tightly regulated processes of ribosome biogenesis and rRNA synthesis. Thus, expression of rRNA genes and rRNA processing were analyzed in cell cycle arrested cells by both the chemotherapeutic agent HU and the pheromone ?-factor. Chromatin endogenous cleavage, chromatin immuno-precipitation, chromatin spreading and Northern blotting were employed to investigate the effect of HU on the expression of rRNA genes and rRNA synthesis. The results indicate that in yeast arrested by HU the overall number of active promoters remains unchanged, and that rRNA genes chromatin stay poised for transcription. However, distribution of RNAPI on individual rRNA gene and rRNA processing are disturbed, lowering rRNA synthesis. Conversely, in ?-factor arrested cells rRNA transcription was not affected. These results point out a hitherto unnoticed cellular response to HU that might participate in the inhibition of cell division.
Hae Young Chung has completed his PhD at the age of 30 years from Toyama University and postdoctoral study from University of Texas Health Science Center at San Antonio. He is the director of Molecular Inflammation Research Center for Aging Intervention. He has published more than 400 papers in reputed journals and has been serving as an editorial board member of AGE.
Aging is a physiological process caused by time-dependent, progressive changes in multiple biological systems, which induces the increased incidence of age-related diseases. Among anti-aging strategies, calorie restriction (CR) is a widely accepted anti-aging paradigm. Recently, high-throughput technologies are applied to find aging/CR-associated genes. Given that high-throughput methods generate huge amounts of data, it is necessary to study how these CR-related bio-molecules work, interact, and exert their influence in terms of systemic view. Here, we propose database of aging and calorie restriction (CR) related genes. We first screened mouse genes that are related to both aging and CR. We then investigated the orthologs of the common genes in yeast and used these results to confirm and measure functions and life-spans using yeast knockout strains. We suggested a systematic framework and database for further understanding of aging process.
J.C. Argüelles has completed his Ph.D. in Biology in 1987 at the University of Murcia and postdoctoral studies from Institute of Biomedicine (CSIC, Madrid, Spain) and from the Lab. of Molecular Cellbiologie at the Catholic University of Leuven (Belgium). He is currently Professor of Microbiology and has published more than 50 papers in reputed journals and has been serving as an editorial board member. Furthermore, he is also engaged in the social and humanistic features of Science, has published two books on scientific historiography, has participated on forums on the dissemination of Science and is a writer of popular science articles in some leading newspapers.
Candida albicans still remains the most prevalent fungal pathogen in humans. The MAP-kinase HOG1 pathway plays an essential role in the pathobiology of this opportunistic yeast, including the colonization of the gastrointestinal tract in mouse or the defensive response against several environmental injuries. The latter, encompass mechanisms to face both oxidative and osmotic stress treatments. Here we show that one of the main components of this defensive response consists of the intracellular protective accumulation of the non-reducing disaccharide trehalose and two polyols, glycerol and D-arabitol, an accumulation that occurs in a stress-specific dependent manner. Thus, oxidative exposures promoted a marked increase in both trehalose and D-arabitol in the wild type strain, RM-100 (and several standard genetic backgrounds), whereas the glycerol content remained virtually unaffected with respect to basal (untreated) levels. In contrast, osmotic challenges induced the significant storage of glycerol accompanied by minor changes, or even a slight drop, in the intracellular content of trehalose and D-arabitol. We examined the hypothetical role in this process of the MAP kinase Hog1, which regulates the protective responses in C. albicans against both oxidative and osmotic stress. Interestingly, unlike glycerol synthesis, the stress-induced trehalose accumulation was always Hog1-independent, whereas the ability to synthesize D-arabitol was only partially dependent on a functional Hog1 pathway, at least under our experimental conditions.
Povilas Šimonis has finished master studies Biochemistry (Vilnius University) and started his Chemistry PhD (Center for Physical Sciences and Technology) in 2016. During his scientific career he participated in various schools related to application of pulsed electric fields including: EBTT – international scientific workshop and postgraduate course, school on applications of Pulsed Electric Fields for food processing. He is a member of ISEBTT (International Society of Electroporation – Based Technologies and Treatments). Presented his working results in more than 10 local and international conferences. Currently his scientific data is already published in Bioelectrochemistry Journal.
Saccharomyces cerevisiae is one of the most well-studied and understood eukaryotic organisms. The studies of yeast cell allow reconstitution of possible molecular mechanisms of various abiotic effects. Pulsed electric field has been one of the most intensively investigated abiotic effects on biological tissues and cell suspensions for a past decade. It has been previously shown that a nanosecond pulsed electric field (nsPEF) permeabilize the plasma membrane, alter gene expression, cause phosphatidylserine translocation, affect the distribution of intracellular ions and even lead to the death of mammalian cells. There is still a lack of sufficient data related to the effects of nsPEF on yeast cells yet. In our study we analyzed the effects of square shaped electrical pulses of different duration (?= 10-90 ns) and pulse number (pn= 1-5) with electric field strength (E) up to 220 kV/cm and showed that nanosecond pulses can induce the cell death, which in turn is dependent on the electric field pulse parameters and increase with the rise in E, ? and pulse number. Exposure of yeast cells to nsPEFs was accompanied by metacaspase activation, membrane permeability to propidium iodide and the externalization of phosphatidylserine. Furthermore, the investigation of yeast cells permeabilization to tetraphenylphosphonium ions (TPP+), which was induced by high power nanosecond duration electrical pulses, had demonstrated the following features: (i) The study of TPP+ ions absorption rate by yeast cells is an effective method for detection of short duration electric pulse influence on yeast cell wall properties; (ii) Shortening of the electric pulse duration makes it possible to achieve more homogeneous electrical treatment of yeast cell clusters and by this way to increase the effectiveness of single cell permeabilization; (iii) The significant acceleration of TPP+ ions absorption rate (up to 65 times) can be achieved without any influence on the vitality of the cells. We conclude that square shaped electric field pulses with nanosecond durations induce wide variety of effects including caspase-dependent apoptosis, oxidative stress, cell wall permeabilization, and that such abiotic treatment can be used in various applications starting from food safety ensurance and ending in medicine field.