Functional Role for Transporter Isoforms in Optimizing Membrane Transport

Quantitative analysis of carrier parameters demonstrates that with decreasing substrate concentration the optimal strength of substrate-carrier interaction which maximizes the flux across the membrane increases and requires less fine-tuning than at higher concentrations of the substrate.     

Induced autolysis ofSaccharomyces cerevisiae: Morphological effects,rheological effects,and dynamics of accumulation of extracellular hydrolysis products

Changes in the internal structure ofSaccharomyces cerevisiae cells and accumulation of proteins and nucleic components in extracellular fluid as decomposition products were studied in the 40–75°C temperature range under the effect of various membranotrophic additives. Autolysis was shown to be a two-step process: The first step consists of the restructuring of cell endostructures and the activation of lytic enzymes, which is accompanied by reduction of cell volume and system viscosity; the second step directly follows the first step and consists of hydrolysis of cell components and release of hydrolysis products into extracellular space. Duration of the first step depends on the temperature and the plasmolyzer. Hydrophilic additives (ethanol, ethyl acetate) were most effective during the first step at 60–65°C, whereas hydrophobic additives (lecithin, lauric acid) were most effective at 55°C. In the second step, the temperature optimum of protease activity in the control (without additives) was 60°C, that of nuclease activity was 70°C. Additives reduce the temperature optimum of endoenzymatic activity. Cell morphology was studied at various stages of autolysis by electron and phase-contrast microscopy.     

ARADEEPOPSIS,an Automated Workflow for Top-View Plant Phenomics using Semantic Segmentation of Leaf States

Linking plant phenotype to genotype is a common goal to both plant breeders and geneticists. However, collecting phenotypic data for large numbers of plants remain a bottleneck. Plant phenotyping is mostly image based and therefore requires rapid and robust extraction of phenotypic measurements from image data. However, because segmentation tools usually rely on color information, they are sensitive to background or plant color deviations. We have developed a versatile, fully open-source pipeline to extract phenotypic measurements from plant images in an unsupervised manner. ARADEEPOPSIS (https://github.com/Gregor-Mendel-Institute/aradeepopsis) uses semantic segmentation of top-view images to classify leaf tissue into three categories: healthy, anthocyanin rich, and senescent. This makes it particularly powerful at quantitative phenotyping of different developmental stages, mutants with aberrant leaf color and/or phenotype, and plants growing in stressful conditions. On a panel of 210 natural Arabidopsis (Arabidopsis thaliana) accessions, we were able to not only accurately segment images of phenotypically diverse genotypes but also to identify known loci related to anthocyanin production and early necrosis in genome-wide association analyses. Our pipeline accurately processed images of diverse origin, quality, and background composition, and of a distantly related Brassicaceae. ARADEEPOPSIS is deployable on most operating systems and high-performance computing environments and can be used independently of bioinformatics expertise and resources.     

Activity of amino acids as a function of their hydrophobicity in the process of the autolysis of theSaccharomyces cerevisiae yeast

The effect of amino acids on the process of autolysis of baker’s yeast was studied. It is shown that the addition of amino acids inhibits the increase in concentration of amino nitrogen during the process of autolysis. The effect of the inhibition is connected with the hydrophobicity of amino acids, the relationship being of the symbasis nature; it is especially obvious at high concentrations of the latter. The deviation from the symbasis as a result of the effect of low concentrations is the most typical for the highly hydrophobic amino acids (tyrosine, phenylalanine, isoleucine, tryptophan), which can be explained by their solubilization in lipid components of the cell. Hydrophilic glutamic acid suppresses both protease activity and nuclease activity of endoenzymes, which can be explained by its membranotrophic effect.