Thermophilic Myceliophthora thermophila decomposes cellulose

A thermophilic microscopic fungus was isolated from cattle rumen and identified as Myceliophthora thermophila (Apinis) van Oorschot. The culture synthesized cellulolytic enzymes and xylanase when it was grown in media containing cellulase at 50 degrees C under the conditions of submerged cultivation. The morphological and physiological characteristics of the culture are described and its taxonomic position is discussed.     

Theory of integrating cellular tension and consequences from it

Tensegrity model and implications from it have been reviewed. Experimental data confirming the model are shown. While signal vectorization is well confirmed and well depicted by the model, the vectorization of expression implied by the model has not yet been elaborated. Molecular mechanisms of functional connection between the nuclear matrix and the cytoskeleton need further observations.     

The correcting role of autonomous 3'-->5' exonucleases in mammalian multienzyme DNA polymerase complexes

A study was made of the correcting role of autonomous 3'-->5' exonucleases (AE) contained in multienzyme DNA polymerase complexes of rat hepatocytes or calf thymocytes. DNA was synthesized on phage psi X174 amber3 or M13mp2 primer-templates, and used to transfect Escherichia coli spheroplasts. Frequencies were estimated for direct and reverse mutations resulting from mistakes made in the course of in vitro DNA synthesis. The mistake rate of the hepatocytic complex was estimated at 3 x 10(-6) with equimolar dNTP, and increased tenfold when proteins accounting for 70% of the total 3'-->5' exonuclease activity of the complex were removed. The fidelity of DNA synthesis was completely restored in the presence of exogenous AE (epsilon subunit of E. coli DNA polymerase III). Nuclear (Pol delta n) and cytosolic (Pol delta c) forms of DNA polymerase delta were isolated from calf thymocytes. The former was shown to contain an AE (TREX2) absent from the latter. As compared with Pol delta c, Pol delta n had a 20-fold higher exo/pol ratio and allowed 4-5 times higher fidelity of DNA synthesis. The mistake rate of DNA polymerase complexes changed when dNTP were used in nonequimolar amounts.     

Description of Desulfotomaculum nigrificans subsp. salinus as a new species, Desulfotomaculum salinum sp. nov

This study focused on the physiological, chemotaxonomic, and genotypic characteristics of two thermophilic spore-forming sulfate-reducing bacterial strains, 435T and 781, of which the former has previously been assigned to the subspecies Desulfotomaculum nigrificans subsp. salinus. Both strains reduced sulfate with the resulting production of H2S on media supplemented with H2 + CO2, formate, lactate, pyruvate, malate, fumarate, succinate, methanol, ethanol, propanol, butanol, butyrate, valerate, or palmitate. Lactate oxidation resulted in acetate accumulation; butyrate was oxidized completely, with acetate as an intermediate product. Growth on acetate was slow and weak. Sulfate, sulfite, thiosulfate, and elemental sulfur, but not nitrate, served as electron acceptors for growth with lactate. The bacteria performed dismutation of thiosulfate to sulfate and hydrogen sulfide. In the absence of sulfate, pyruvate but not lactate was fermented. Cytochromes of b and c types were present. The temperature and pH optima for both strains were 60-65 degrees C and pH 7.0. Bacteria grew at 0 to 4.5-6.0% NaCl in the medium, with the optimum being at 0.5-1.0%. Phylogenetic analysis based on a comparison of incomplete 16S rRNA sequences revealed that both strains belonged to the C cluster of the genus Desulfotomaculum, exhibiting 95.5-98.3% homology with the previously described species. The level of DNA-DNA hybridization of strains 435T and 781 with each other was 97%, while that with closely related species D. kuznetsovii 17T was 51-52%. Based on the phenotypic and genotypic properties of strains 435T and 781, it is suggested that they be assigned to a new species: Desulfotomaculum salinum sp. nov., comb. nov. (type strain 435T = VKM B 1492T).     

Characteristics of DNA isolated from a complex form of DNA-polymerase alpha from the rat liver

A complex from of DNA polymerase alpha was isolated from the nuclear membrane of hepatocytes. DNA fragments were shown to be among components of the complex under study. In this paper we present evidence that DNA from the alpha-polymerase complex from quiescent hepatocytes (DNA-G) differs in its nucleotide composition from its counterpart (DNA-S) isolated from hepatocytes synthesizing DNA. As judged by dot hybridization, DNA-G0 does not contain nucleotide sequences which are complementary to ribosomal or messenger RNA, whereas the abovementioned sequences are present in DNA-S. At the same time DNA-G0 is found to contain sequences which are homologous to both SV40 DNA and yeast TRPI-ARS1 DNA. The difference in nucleotide sequences between DNA-G0 and DNA-S indicates that in the process of replication DNA is being stretched across the multienzyme complex located on the nuclear membrane.     

Cryotransformation of Bacillus anthracis by the DNA of pUB110 plasmid

Possibility of cryotransformation of Bacillus anthracis cells by the DNA of pUB110 plasmid has been established. The parameters of cryotransformation process have been optimized permitting one to increase the efficiency of transformation up to 3.1 . 10(2) transformants per 1 mkg of transforming DNA. The factors affecting the efficiency of cryotransformation and its reproducibility have been studied including the treatment of recipient cells by glycine, the procedure of freeze-thawing, the composition of freezing medium. The recipient activity of Bacillus anthracis cells has been shown to depend on the set of their own plasmids.