Molecular and biochemical characterizations of a novel arthropod endo-β-1,3-glucanase from the Antarctic springtail,Cryptopygus antarcticus,horizontally acquired from bacteria

Collembolan species have been known to have β-1,3-glucanase activity and yet the genes coding such enzymes have not been demonstrated. We report here a novel arthropod endo-β-1,3-glucanase gene CaLam from the Antarctic springtail, Cryptopygus antarcticus. The open reading frame consists of 813 bp encoding 270 amino acids with a putative signal peptide and a typical motif of glycosyl hydrolase family 16 (GHF16), E–I–D–I–T–E. The recombinant protein expressed in E. coli shows the hydrolytic activity toward laminarin (K_m ～ 9.98 mg/mL) with an optimal temperature 50 °C and an optimal pH 6.0. CaLam digests laminarin and laminarioligosaccharides except laminaribiose as an endo-β-1,3-glucanase, releasing glucose, laminaribiose and laminaritriose as the major products. Analyses of molecular phylogeny of CaLam and its protein structure reveal that CaLam is closely related with bacterial β-1,3-glucanases more than with the eukaryotic homologues. Even so, the genomic structure of the CaLam gene consisting of six exons interspersed with approximately 57 to 63 bp introns confirms that it is endogenous in the genome of the Antarctic springtail. These results suggest that CaLam should have been transferred from bacteria to the lineage of the Collembolan species by horizontal gene transfer.     

Low-Cost Fabrication of Pt Thin Films with Controlled Nanostructures and Their Effects on SERS

We fabricated nanostructured Pt thin films with two different morphologies and studied their effects on the Raman spectrum of rhodamine 6G. The syntheses were achieved by templating mesoporous silica thin films which are characterized by 8-nm-sized pore channels and 3–4-nm-thick walls in two different orientations of the channels. Therefore, the resultant nanostructured Pt thin films are composed of Pt nanorods of 8 nm in diameter vertically standing in one morphology and horizontally lying in the other. The latter produced stronger Raman signals than the former. Simulations based the discrete-dipole approximation on model nanostructures showed that the horizontally lying nanorods produce stronger local electromagnetic field than the vertically standing ones, in agreement with the experimental observations.     

Production of adipic acid by short- and long-chain fatty acid acyl-CoA oxidase engineered in yeast Candida tropicalis

Bioprocess and Biosystems Engineering - In this study, to produce adipic acid, mutant strains of Candida tropicalis KCTC 7212 deficient of AOX genes encoding acyl-CoA oxidases which are important...