In Trajectories of genetics, 150 years after Mendel / Trajectoire de la genetique, 150 apres Mendel Guest Editors / Redacteurs en chef invites : Bernard Dujon, Georges Pelletier, Comptes rendus - Biologies July-August 2016 339(7-8):324-328
In Trajectories of genetics, 150 years after Mendel / Trajectoire de la genetique, 150 apres Mendel Guest Editors / Redacteurs en chef invites : Bernard Dujon, Georges Pelletier, Comptes rendus - Biologies July-August 2016 339(7-8):284-288
Polčic, Peter, Pakosová, Lucia, Chovančíková, Petra, and Machala, Zdenko
Canadian Journal of Microbiology. Jun2018, Vol. 64 Issue 6, p367-375. 9p.
OXIDATIVE stress, SACCHAROMYCES cerevisiae, GENE expression, CELL death, and REACTIVE oxygen species
Interactions of living cells with cold plasma of electrical discharges affect cell physiology, often resulting in the loss of viability. However, the mechanisms involved in cell killing are poorly understood, and dissection of cellular pathways or structures affected by plasma using simple eukaryotic models is needed. Using selected genetic mutants of yeast ( Saccharomyces cerevisiae), we investigated the role of oxidative stress and yeast apoptosis in plasma-induced cell killing. Increased sensitivity of yeast strains deficient in superoxide dismutases indicated that reactive oxygen species generated in the plasma are among the most prominent factors involved in killing of yeast cells. In mutant strains with a deletion of the key components of yeast apoptotic pathway, the sensitivity of cells towards the plasma treatment remained unaffected. Yeast apoptosis, thus, does not appear to play a significant role in plasma-induced cell killing of yeast. [ABSTRACT FROM AUTHOR]
Background: Invasive fungal diseases (IFDs) are opportunistic infections associated with significant mortality in paediatric patients, especially in those with compromised immune system and neonates with very low birth weight (VLBW). The objectives of this study are to determine the prevalence, clinical features and fungi isolates of neonatal sepsis in three hospitals in Egypt. Methodology: The study is a cross sectional survey of 176 neonates with clinical sepsis admitted to the neonatal intensive care units (NICU) of the three hospitals over a period of one year (February 2015 to January 2016). A minimum of two blood samples (collected within 24 hours) from each neonate were cultured for bacteria in automated BacT/AlerT and conventional culture bottles, while Saboraud-Brain Heart Infusion broth was inoculated for fungi culture. Positive growths from the broth were sub-cultured on Sabouraud Dextrose Agar (SDA) plates for aerobic incubation at 25oC and 37oC for 2 weeks. Identification of fungi colonies on SDA was by conventional morphology and confirmation on chromogenic agar media. Phylogenetic analysis of representative fungi isolates was done by partial nucleotide sequencing of D1-D2 domain of the large subunit rRNA gene. Results: Of the 176 neonates, blood culture was positive for pathogens in 55 (31.3%) samples and fungi were isolated in 26 (14.8%); yeast (25) and mould (1). The commonly isolated yeasts were Candida albicans, Candida tropicalis, and Candida krusei representing 34.6%, 30.8% and 23.1%, respectively of the total fungi isolated. The phylogenetic analysis in comparison to Genbank data showed defined clades for Candida tropicalis, Candida parapsilosis, Candida albicans and Pichia kudriavzevii. Conclusion: This current study highlights the changing pattern of neonatal infections in Egypt caused by Candida, with increasing incidence of infections caused by non-albicans Candida species. [ABSTRACT FROM AUTHOR]
Canadian Journal of Microbiology. 2017, Vol. 63 Issue 2, p153-159. 7p. 1 Diagram, 5 Graphs.
CADMIUM, CYTOLOGICAL research, YEAST, MITOCHONDRIAL membranes, and ETHYLENE glycol
Cadmium (Cd) is one of the most toxic heavy metals. It is of great environmental concern and its toxicity has been investigated in a variety of cells. In this study, we elucidated the toxic effects of Cd in cells of yeast ( Saccharomyces cerevisiae). Our results showed that Cd2+ (0.05-5.0 mmol·L−1) significantly inhibited yeast cell growth, and the inhibitory effect was positively correlated with Cd2+ concentrations. Cd2+ caused loss of yeast cell viability in a concentration- and duration-dependent manner. Intracellular reactive oxygen species (ROS) and Ca2+ levels increased in yeast cells after exposure to 5.0 mmol·L−1 Cd for 6 h. Cd2+-caused cell viability loss was blocked by antioxidants (0.5 mmol·L−1 ascorbic acid or 500 U·mL−1 catalase) or Ca2+ antagonists (0.5 mmol·L−1 ethylene glycol tetraacetic acid or 0.5 mmol·L−1 LaCl3). Moreover, a collapse of mitochondrial membrane potential (ΔΨm) was observed in Cd2+-treated yeast cells. These results indicate that Cd-induced yeast cell killing was associated with the elevation of intracellular ROS and Ca2+ levels and also the loss of ΔΨm. [ABSTRACT FROM AUTHOR]
Wedge, Marie-Ève, Naruzawa, Erika Sayuri, Nigg, Martha, and Bernier, Louis
Canadian Journal of Microbiology. 2016, Vol. 62 Issue 6, p525-529. 5p. 1 Black and White Photograph, 1 Graph.
MYCELIUM, DUTCH elm disease, OPHIOSTOMA, CELL populations, and QUORUM sensing
Dutch elm disease (DED) is caused by the dimorphic fungi Ophiostoma ulmi, Ophiostoma novo-ulmi, and Ophiostoma himal-ulmi. A cell population density-dependent phenomenon related to quorum sensing was previously shown to affect the reversible transition from yeast-like to mycelial growth in liquid shake cultures of O. novo-ulmi NRRL 6404. Since the response to external stimuli often variesamongDEDfungal strains, we evaluated the effect of inoculum size on 8 strains of the 3 species of DED agents by determining the proportion of yeast and mycelium produced at different spore inoculum concentrations in defined liquid shake medium. The results show that not all DED fungi strains respond similarly to inoculum size effect, since variations were observed among strains. It is thus possible that the different strains belonging to phylogenetically close species use different signalling molecules or molecular signalling pathways to regulate their growth mode via quorum-sensing mechanisms. [ABSTRACT FROM AUTHOR]
Ramos-Garza, Juan, Bustamante-Brito, Rafael, Ángeles de Paz, Gabriela, Medina-Canales, Ma. Gabriela, Vásquez-Murrieta, María Soledad, Wang, En Tao, and Rodríguez-Tovar, Aída Verónica
Canadian Journal of Microbiology. 2016, Vol. 62 Issue 4, p307-319. 13p.
ENDOPHYTES, SOIL pollution, PLANT fibers, REGOLITH, and RADIOACTIVE substances
Yeasts were quantified and isolated from the rhizospheres of 5 plant species grown at 2 sites of a Mexican region contaminated with arsenic, lead, and other heavy metals. Yeast abundance was about 102 CFU/g of soil and 31 isolates were obtained. On the basis of the phylogenetic analysis of 26S rRNA and internal transcribed spacer fragment, 6 species were identified within the following 5 genera: Cryptococcus (80.64%), Rhodotorula (6.45%), Exophiala (6.45%), Trichosporon (3.22%), and Cystobasidium (3.22%). Cryptococcus spp. was the predominant group. Pectinases (51.6%), proteases (51.6%), and xylanases (41.9%) were the enzymes most common, while poor production of siderophores (16.1%) and indole acetic acid (9.67%) was detected. Isolates of Rhodotorula mucilaginosa and Cystobasidium sloffiae could promote plant growth and seed germination in a bioassay using Brassica juncea. Resistance of isolates by arsenic and heavy metals was as follows: As3+ ≥ 100 mmol/L, As5+ ≥ 30 mmol/L, Zn2+ ≥ 2 mmol/L, Pb2+ ≥ 1.2 mmol/L, and Cu2+ ≥ 0.5 mmol/L. Strains of Cryptococcus albidus were able to reduce arsenate (As5+) into arsenite (As3+), but no isolate was capable of oxidizing As3+. This is the first study on the abundance and identification of rhizosphere yeasts in a heavy-metal- and arsenic-contaminated soil, and of the reduction of arsenate by the species C. albidus. [ABSTRACT FROM AUTHOR]
Naruzawa, Erika Sayuri, Malagnac, Fabienne, and Bernier, Louis
Botany. 2016, Vol. 94 Issue 1, p31-39. 9p.
LINOLEIC acid, DIMORPHISM in plants, OPHIOSTOMA, DUTCH elm disease, XYLEM, and MICROBIAL virulence
Elm populations from North America and Europe were devastated by Dutch elm disease (DED), which is a vascular disease caused by fungi from the genus Ophiostoma (Ascomycota). These pathogens feature a yeast-mycelium dimorphism that may be related to virulence by facilitating colonization of the host xylem. Cyclooxygenases (COX) have been proposed to modulate yeast-mycelium dimorphism of DED fungi, and homologs of cox genes have been found in the nuclear genome of O. novo-ulmi subsp. novo-ulmi. Linoleic acid, a substrate for COX, was reported to stimulate the formation of asexual and sexual reproduction structures in DED strains grown on complex media. We hypothesized that linoleic acid also induced mycelium production in liquid shake culture conditions. Linoleic acid was found to enhance the production of reproductive structures in sexual crosses conducted on a complex medium (elm sapwood agar), but was not sufficient for these structures to form on a minimal medium. In liquid shake cultures grown in a minimal medium, the addition of linoleic acid stimulated mycelial formation. Our results suggest that linoleic acid plays a role in reproduction and dimorphism in the DED pathogens. [ABSTRACT FROM AUTHOR]
Mantil, Elisabeth, Daly, Grace, and Avis, Tyler J.
Canadian Journal of Microbiology. Jan2015, Vol. 61 Issue 1, p82-88. 7p. 8 Charts.
TEA tree oil, ANTI-infective agents, REGULATION of microbial growth, PERSONAL care products, PHARMACEUTICAL chemistry, and THERAPEUTICS
There has been increased interest surrounding the use of tea tree oil (TTO) as a natural antimicrobial. In this study, the antimicrobial activity of TTO and its components were investigated in vitro and in a predominantly lipid-based personal care formulation. In vitro, TTO showed minimal inhibitory concentrations of 0.2% (for Saccharomyces cerevisiae and Pythium sulcatum), 0.4% (for Escherichia coli, Bacillus subtilis, and Rhizopus stolonifer), and 0.8% (for Botrytis cinerea). TTO at 0.08%-0.8% was often as efficient as parabens. Comparison of the antimicrobial activities of TTO components showed that terpinen-4-ol and γ-terpinene were generally most effective in inhibiting microbial growth. TTO activity in a personal care product was evaluated through air and water exposure, artificial inoculation, and shelf life studies. While TTO did not increase shelf life of unopened products, it decreased microbial load in products exposed to water and air. Results from this study support that antimicrobial activity of TTO can be attributed to varying levels of its components and that low levels of TTO were effective in reducing microbial growth during the use of the product. This study showed that TTO can act as a suitable preservative system within an oil-based formulation. [ABSTRACT FROM AUTHOR]
Liu, Yun-Hua, Zhang, Meiping, Wu, Chengcang, Huang, James J., Zhang, Hong-Bin, and Gulick, P.
Genome. Jan2014, Vol. 57 Issue 1, p9-19. 11p.
ARABIDOPSIS thaliana, RETROTRANSPOSONS, MICROSATELLITES (Genetics), DNA, CHEMOGENOMICS, and EVOLUTIONARY theories
Knowledge of how a genome is structured and organized from its constituent elements is crucial to understanding its biology and evolution. Here, we report the genome structuring and organization pattern as revealed by systems analysis of the sequences of three model species, Arabidopsis, rice and yeast, at the whole-genome and chromosome levels. We found that all fundamental function elements (FFE) constituting the genomes, including genes (GEN), DNA transposable elements (DTE), retrotransposable elements (RTE), simple sequence repeats (SSR), and (or) low complexity repeats (LCR), are structured in a nonrandom and correlative manner, thus leading to a hypothesis that the DNA of the species is structured as a linear 'jigsaw puzzle'. Furthermore, we showed that different FFE differ in their importance in the formation and evolution of the DNA jigsaw puzzle structure between species. DTE and RTE play more important roles than GEN, LCR, and SSR in Arabidopsis, whereas GEN and RTE play more important roles than LCR, SSR, and DTE in rice. The genes having multiple recognized functions play more important roles than those having single functions. These results provide useful knowledge necessary for better understanding genome biology and evolution of the species and for effective molecular breeding of rice. [ABSTRACT FROM AUTHOR]
AUTOPHAGY (Cytology), RAPAMYCIN, BIODEGRADATION, HELICASES, SACCHAROMYCES cerevisiae, IMMUNOSUPPRESSIVE agents, and PROTEIN kinases
In yeast Saccharomyces cerevisiae, the immunosuppressant rapamycin mimics starvation by inhibiting the kinase Tor1. We recently documented that this treatment triggers a rapid degradation of Sgs1, a helicase involved in several biological processes such as the prevention of genomic instability. Herein, we show that yeast strains deleted for genes ATG2, ATG9, and PEP4, encoding components of the autophagy pathway, prevent rapamycin-induced degradation of Sgs1. We propose that defects in the autophagy pathway prevent degradation of key proteins in the rapamycin response pathway and as a consequence cause resistance to the drug. [ABSTRACT FROM AUTHOR]