A filamentous fungus, Pythium ultimum TROW var. ultimum, isolated from moribund moss colonies from Svalbard, northern islands of Norway

A fungus, Pythium ultimum TROW var. ultimum, was isolated from colonies of moribund moss, Sanionia uncinata (HEDW.) LOESKE, in Svalbard. This is the first report of isolation of P. ultimum var. ultimum from the Arctic Zone. This fungus showed possible moss pathogenic activity. The taxonomic, morphological and ecological characteristics are described here. In addition, the mycelial growth of this isolate is compared with that of isolates from the Temperate Zone, and its physiological characteristics are discussed

Determination of Serum Spermidine by High-Performance Liquid Chromatography after Fluorescence Derivatization with Orthophthalaldehyde

Repor

Catalytically important amino-acid residues of abalone alginate lyase HdAly assessed by site-directed mutagenesis

Alginate lyase is an enzyme that degrades alginate chains via β-elimination and has been used for the production of alginate oligosaccharides and protoplasts from brown algae. Previously, we deduced the amino-acid sequence of an abalone alginate lyase, HdAly, from its cDNA sequence and, through multiple amino-acid sequence alignment, found that several basic amino-acid residues were highly conserved among the polysaccharide-lyase family 14 (PL-14) enzymes including HdAly. In the present study, we assessed the functional importance of the conserved basic amino-acid residues in HdAly by using sitedirected mutants that were produced with a cold-inducible yeast expression system consisting of an expression vector pLTex321sV5H and a host Saccharomyces cerevisiae BY4743. At first, we prepared wildtype HdAly with the yeast expression system and confirmed that this recombinant possesses nearly the same properties as native HdAly with respect to specific activity (1300 U/mg), optimal pH (7.8), optimal temperature (35℃), and protoplast-producing ability from the brown alga Laminaria japonica. Then, we prepared a series of site-directed mutants by replacing the conserved basic amino-acid residues of HdAly with Ala and determined the alginate-degrading activity of these mutants. As a result, we found that the replacement of Lys95 caused complete inactivation of HdAly and those of Arg92, Arg110, and Arg119 caused 65% or more inactivation. These results indicate that the region spanning Arg92 to Arg119 is closely related to the catalytic activity of HdAly

Detection of Cluster Boundary in Microarray Data by Reference to MIPS Functional Catalogue Database

DNA microarray has made it possible to determine expression levels of thousands of genes in parallel under multiple experiment conditions. An important step in an analysis of gene expression data is to classify genes with similar expression patterns into same groups. Hierarchical clustering has been extensively used to explore genes with similar expression patterns from large amounts of gene expression data in microarra

Systematic optimization of gene expression of pentose phosphate pathway enhances ethanol production from a glucose/xylose mixed medium in a recombinant Saccharomyces cerevisiae

Abstract The pentose phosphate pathway (PPP) plays an important role in the synthesis of ribonucleotides and aromatic amino acids. During bioethanol production from cellulosic biomass composed mainly of d-glucose and d-xylose, the PPP is also involved in xylose metabolism by engineered Saccharomyces cerevisiae. Although the activities and thermostabilities of the four PPP enzymes (transaldolase: TAL1, transketolase: TKL1, ribose-5-phosphate ketol-isomerase: RKI1 and d-ribulose-5-phosphate 3-epimerase: RPE1) can affect the efficiency of cellulosic ethanol production at high temperatures, little is known about the suitable expression levels of these PPP genes. Here, we overexpressed PPP genes from S. cerevisiae and the thermotolerant yeast Kluyveromyces marxianus either singly or in combination in recombinant yeast strains harboring a mutant of xylose isomerase (XI) and evaluated xylose consumption and ethanol production of these yeast transformants in glucose/xylose mixed media at 36 °C. Among the PPP genes examined, we found that: (1) strains that overexpressed S. cerevisiae TKL1 exhibited the highest rate of xylose consumption relative to strains that overexpressed other PPP genes alone; (2) overexpression of RKI1 and TAL1 derived from K. marxianus with S. cerevisiae TKL1 increased the xylose consumption rate by 1.87-fold at 24 h relative to the control strain (from 0.55 to 1.03 g/L/h); (3) the strains with XI showed higher ethanol yield than strains with xylose reductase and xylitol dehydrogenase and (4) PHO13 disruption did not improve xylose assimilation under the experimental conditions. Together these results indicated that optimization of PPP activity improves xylose metabolism in genetically engineered yeast strains, which could be useful for commercial production of ethanol from cellulosic material