Cloning and nucleotide sequence of the isoamylase gene from Pseudomonas amyloderamosa SB-15

The gene (iam) coding for isoamylase (glycogen 6-glucanohydrolase) of Pseudomonas amyloderamosa SB-15 was cloned. Its nucleotide sequence contained an open reading frame of 2313 nucleotides (771 amino acids) encoding a precursor of secreted isoamylase. The precursor contained a signal peptide of 26 amino acid residues at its amino terminus and three regions homologous with those conserved in alpha-amylases (1,4-alpha-D-glucan 4-glucanohydrolase) of species ranging from prokaryotes to eukaryotes. These homologous regions were also found in another debranching enzyme, pullulanase (pullulan 6-glucanohydrolase) from Klebsiella aerogenes. Sequences of the isoamylase also showed significant homology with those between positions 300 and the carboxyl terminus of pullulanase. The regions required for the specificity of isoamylase were discussed on the basis of a comparison of its amino acid sequence with those of alpha-amylases, cyclomaltodextrin glucanotransferases, and pullulanase.     

Isolation of adenosine 5'-diphosphate-L-glycero-D-mannoheptose, the assumed substrate of heptose transferase(s), from Salmonella minnesota R595 and Shigella sonnei Re mutants

From heptose transferase-less Re mutants of Salmonella minnesota and Shigella sonnei, a mixture of nucleotide-linked heptoses was isolated. After paper chromatography in different solvent systems, ADP derivatives of D-glycero-D-mannoheptose and L-glycero-D-mannoheptose could be isolated in pure form. The structure of ADP-L-glycero-D-mannoheptose was verified by analytical methods and by transformation of ADP-D-glycero-D-mannoheptose with ADP-D-glycero-D-mannoheptose-6-epimerase.     

Tau, sigma, and delta. A family of repeated elements in yeast

We report here the isolation and structure of a new repeated DNA element, tau. This element, from Saccharomyces cerevisiae, is 371 base pairs long and is flanked on either end by the same invertedly repeated sequence found at the ends of some Ty and sigma elements in yeast, copia elements in Drosophila and spleen necrosis virus. The tau inverted repeats are themselves flanked by a 5-base pair directly repeated genomic sequence that is present only once in a cognate tau-allele. These structural characteristics, the presence of multiple copies of tau in the genome, and the isolation of tau+ and tau- allelic pairs suggest that tau may be capable of transposition either alone or in association with some larger element. Detailed sequence analysis of the tau, sigma, and delta elements revealed that all three contain significant regions of homology, suggesting that they are probably members of a single family derived from a common progenitor.     

An innovative lattice Boltzmann model for simulating Michaelis–Menten-based diffusion–advection kinetics and its application within a cartilage cell bioreactor

Lattice Boltzmann models (LBM) are rapidly showing their ability to simulate a lot of fluid dynamics problems that previously required very complex approaches. This study presents a LBM for simulating diffusion–advection transport of substrate in a 2-D laminar flow. The model considers the substrate influx into a set of active cells placed inside the flow field. A new innovative method was used to simulate the cells activity using the LBM by means of Michaelis–Menten kinetics. The model is validated with some numerical benchmark problems and proved highly accurate results. After validation the model was used to simulate the transport of oxygen substrates that diffuse in water to feed a set of active cartilage cells inside a new designed bioreactor.     

Dominating species of entomophilous ascomycetes anamorphs in West Siberia,Primorsky krai,and Kyrgyzstan

The paper studies mycobiota of the dead insects in West Siberia, Primorsky krai, and Kyrgyzstan. Ascomycetes anamorphs of 13 genera are revealed. In all regions Beauveria bassiana (Bals.-Criv.) Vuill. dominated comprising on average 68% of the total number of isolates. The fungus hosts list the insects of 7 orders and 32 families with Coleoptera, Lepidoptera, and Hemiptera dominating. The rarely found entomopathogens include Tolypocladium inflatum Gams (primarily on Lepidoptera), Metarhizium anisopliae (Metschn.) Sorokin (on Coleoptera). The mortality rate of the insects due to micromycetes is observed mainly on enzootic level. The study of the pathogenic properties of the dominating species (B. bassiana) show the absence of specificity of its environmental isolates for a number of representatives of Orthoptera, Lepidoptera, Coleoptera, and Diptera.     

Characteristics of adenosine activity on adenine nucleotide metabolism of rat thymocytes

The effects of adenosine on adenine nucleotide metabolism in [14C]adenine-labeled rat thymocytes were studied. It was shown that adenosine increases the intracellular pool of adenine nucleotides, predominantly ATP, which is accompanied by marked acceleration of their catabolism and a release of labeled products (especially inosine, hypoxanthine and adenosine) from the thymocytes. The effect of adenosine depends on its concentration and manifests itself already at 10(-6) M. 2-Deoxycoformycin partly relieves the effect of adenosine on adenine nucleotide metabolism. Exogenous deoxyadenosine, inosine, hypoxanthine and adenine, unlike adenosine, do not significantly affect the adenine nucleotide catabolism and the label release from the cells. All the effectors under study strongly increase inosine transport from the thymocytes, and inhibit, with the exception of adenosine, the hypoxanthine release from the cells.