Diversity and physiological and biochemical properties of heterotrophic bacteria isolated from Lake Baikal neuston

For heterotrophic microorganisms (44 strains) isolated from the surface film of Lake Baikal, identification was carried out and their physiological and biochemical characteristics were determined. Compared to the water column, diversity of cultured heterotrophs was low, indicating formation of stable microbial communities at the air–water interface. Heterotrophic bacteria isolated from the surface microlayer exhibited the enzymatic activity comparable to that for strains from other biofilm associations. Deinococcus ficus strain NA202 was the most active component of the community, capable of utilization of the broadest spectrum of mono- and disaccharides, sugars, and amino acids. This strain possessed the highest diversity of extracellular enzymes and was the most resistant to UV radiation. The physiological and biochemical properties of this strain may be responsible for its adaptation to survival in extreme conditions of the surface microlayer. These results improve our understanding of occurrence of UV-resistant strains in freshwater ecosystems.     

Ecophysiological properties of cultivable heterotrophic bacteria and yeasts dominating in phytocenoses of Galindez Island,maritime Antarctica

Antarctic plants are stable specific microenvironments for microbial colonization that are still less explored. In this study, we investigated cultivable heterotrophic bacteria and yeasts dominating in plant samples collected from different terrestrial biotopes near Ukrainian Antarctic Base on Galindez Island, maritime Antarctica. Phylogenetic analysis revealed affiliation of the bacterial isolates to genera Pseudomonas, Stenotrophomonas, Brevundimonas, Sporosarcina, Dermacoccus, Microbacterium, Rothia and Frondihabitans, and the yeast isolates to genera Rhodosporidium, Cryptococcus, Leucosporidiella, Candida and Exophiala. Some ecophysiological properties of isolated strains were determined that are important in response to different stresses such as psychro- and halotolerance, UV-resistance and production of hydrolytic enzymes. The majority of isolates (88 %) was found to be psychrotolerant; all are halotolerant. Significant differences in survival subsequent to UV-C radiation were observed among the isolates, as measured by culturable counts. For the bacterial isolates, lethal doses in the range 80–600 J m^?2 were determined, and for the yeast isolates—in the range 300–1,000 J m^?2. Dermacoccus profundi U9 and Candida davisiana U6 were found as most UV resistant among the bacterial and yeast isolates, respectively. Producers of caseinase, gelatinase, β-glucosidase, and cellulase were detected. To the best of our knowledge, this is the first report on isolation of UV resistant strain D. profundi, and Frondihabitans strain from Antarctica, and on detection of cellulase activity in Antarctic yeast strain C. davisiana. The results obtained contribute to clarifying adaptation strategies of Antarctic microbiota and its possible role in functional stability of Antarctic biocenoses. Stress tolerant strains were detected that are valuable for ecological and applied studies.     

MicroRNA-199b targets the nuclear kinase Dyrk1a in an auto-amplification loop promoting calcineurin/NFAT signalling

MicroRNAs (miRs) are a class of single-stranded, non-coding RNAs of about 22 nucleotides in length. Increasing evidence implicates miRs in myocardial disease processes. Here we show that miR-199b is a direct calcineurin/NFAT target gene that increases in expression in mouse and human heart failure, and targets the nuclear NFAT kinase dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1a (Dyrk1a), constituting a pathogenic feed forward mechanism that affects calcineurin-responsive gene expression. Mutant mice overexpressing miR-199b, or haploinsufficient for Dyrk1a, are sensitized to calcineurin/NFAT signalling or pressure overload and show stress-induced cardiomegaly through reduced Dyrk1a expression. In vivo inhibition of miR-199b by a specific antagomir normalized Dyrk1a expression, reduced nuclear NFAT activity and caused marked inhibition and even reversal of hypertrophy and fibrosis in mouse models of heart failure. Our results reveal that microRNAs affect cardiac cellular signalling and gene expression, and implicate miR-199b as a therapeutic target in heart failure.     

Young@Heart: empowering the next generation of cardiovascular researchers

In recognition of the increasing health burden of cardiovascular disease, the Dutch CardioVascular Alliance (DCVA) was founded with the ambition to lower the cardiovascular disease burden by 25% in 2030. To achieve this, the DCVA is a platform for all stakeholders in the cardiovascular field to align policies, agendas and research. An important goal of the DCVA is to guide and encourage young researchers at an early stage of their careers in order to help them overcome challenges and reach their full potential. Young@Heart is part of the DCVA that supports the young cardiovascular research community. This article illustrates the challenges and opportunities encountered by young cardiovascular researchers in the Netherlands and highlights Young@Heart’s vision to benefit from these opportunities and optimise collaborations to contribute to lowering the cardiovascular disease burden together as soon as possible.