The effect of single-stranded DNA binding proteins on template/primer-independent DNA synthesis in the presence of nicking endonuclease Nt.BspD6I

Nt.BspD6I nicking endonuclease stimulates template/primer-independent DNA synthesis by Bst DNA polymerase. Template/primer-independent DNA synthesis may be one of the reasons for the formation of nonspecific products in certain DNA amplification reactions, especially those involving nicking endonucleases. Expansion of the range of DNA amplification procedures performed in the presence of nicking endonucleases makes the search for template/primer-independent DNA synthesis inhibitors highly relevant. The present work has shown that a single-strand DNA binding protein from E. coli does not affect template/primer-independent DNA synthesis regardless of the presence or absence of Nt.BspD6I. A single-stranded DNA-binding protein coded by gene 32 from bacteriophage T4 completely inhibits template/primer-independent DNA synthesis in the absence of nicking endonuclease. If nicking endonuclease is present, the protein does not suppress the synthesis of the specific product but causes a significant decrease of the amount of template/primer-independent DNA synthesis products.     

Histological characteristics of the reactions of cerebral neuroglia in laboratory animals

Literature data and the authors' results, concerning structural and functional peculiarities of all varieties of the cerebral neuroglia under effect of a cranial-cerebral trauma, neurotropic chemical products and oxygen insufficiency have been considered. Ideas that neuroglial reactions under the conditions mentioned are proved to be constant and in dependence of certain peculiarities of each case are either progressive or regressive. The reaction degree is mainly proportional to the disturbance power. Nevertheless, certain discrepancies (ariactivity including) can be observed; this is also determined by a combination of prerequisites and by a peculiarity of individual reactivity of the CNS. The greatest stability of astroglia has been stated. Possible variations in relation between changes of neurons and gliocytes are mentioned. Suggestions are made that diffuse-focal progressive reactions of macroglia under conditions of neurotoxicoses can be determined not by proliferation of cells, but by their migration.     

Isolation and some properties of the site-specific endonuclease and methylase Bme2161 from Bacillus megaterium 216

The site-specific endonuclease Bme2161 was isolated as a homogeneous preparation by chromatography on phosphocellulose, hydroxyapatite and heparin-agarose. The molecular mass of the enzyme, determined by gel filtration and by electrophoresis under denaturing conditions, was found to be 60 kDa and 30 kDa respectively. These data indicate that the native enzyme consists of two identical subunits. The enzyme recognized the decreases pentanucleotide sequence 5'-GGACC-3' X 3'-CCTGG-5' and cleaves the sequence as indicated by arrows. The increases optimal concentration for endonuclease reaction is 6-7 mM Mg2+. The endonuclease relaxes its specificity in the presence of glycerol or dimethyl sulfoxide at low Mg2+ concentration (1-3 mM). Methylase Bme2161, which protects DNA against endonuclease Bme2161 action by DNA methylation, was isolated from the same bacterial strain.     

Electron microscopic study of conjugative plasmids from serologically typed E. coli AP1]

The plasmid DNAs isolated from E. coli AP1 were studied by electron microscopy. Two plasmid DNA forms (FB1-1 and FB1--2) with the mol wt of 35.9 +/- 0.5 x x 10(6) and 51.5 +/- 0.6 x 10(6) daltons, respectively, were revealed.     

BspLS2I--a new site-specific endonuclease from the thermophilic bacteria Bacillus species LS2]

A new restriction endonuclease BspLS2I was isolated from the thermophilic bacterium Bacillus species LS2 and purified by blue sepharose and hydroxyapatite chromatographies. The enzyme is an isoschizomer of SduI from Streptococcus durans. BspLS2I recognizes the sequence 5' G(G/A/T)GC(C/T/A) decreases C 3' on double-stranded DNA and cleaves it is indicated by the arrow to yield sticky-ended DNA fragments. Maximum catalytic activity of endonuclease was found in 10 mM tris-HCl (pH 7.9) in the presence of 15-30 mM MgCl2 at 50 degrees C. The phage T4 glucosylated DNA is not cleaved by the enzyme.     

Site-Specific Nickase from Bacillus Species Strain D6

Three site-specific endonucleases were found in thermophilic strain Bacillus species D6. One of them, BspD6II, is an isoschizomer of Eco57I. The second, BspD6III, is present in the strain in very small amount; therefore, it has not been characterized. This paper is devoted to the third, BspD6I, which recognizes pentanucleotide site 5'-GAGTC-3' and cleaves only one DNA strand at a distance of 4 nucleotides from the site in the 3'-direction in the chain with the GAGTC sequence, i.e., it behaves as a site-specific nickase. Nickase N.BspD6I cleaves one DNA strand only in double-stranded DNA and does not cleave single-stranded DNA. Site-specific methylase SscL1I (an isohypectomer of M·HinfI) that methylates adenine in the sequence 5'-GANTC-3' prevents DNA hydrolysis by nickase BspD6I.     

Hypotensive activity of the plasma proteins in a normovolemic blood exchange transfusion

The effect of post-hemotransfusion protein fractions on blood pressure, microcirculation and physiologically active substances has been studied in stimulated blood replacement by homologous animal blood. The in vivo and in vitro experiments have revealed that subfraction of hemotransfusion plasma macromolecular proteins has a prominent antihypertensive effect, leading to blood flow slowing in the microvascular bed. Hemotransfusion plasma proteins possess high serotonin-releasing activity. The involvement of blood proteins and physiologically active substances into the generation of the recepient's response to homologous blood transfusion from several donors and its role in the genesis of post-transfusion complications are discussed.     

A new type of cleavage of the recognition site by the site-specific endonuclease Bst 4.4I from Bacillus stearothermophilus 4.4

A site-specific endonuclease Bst 4.4I was isolated from the cell extract of Bacillus stearothermophilus 4.4 and partially purified by chromatography on Ultragel AcA-44 and heparin-Sepharose. It was shown that the endonuclease cleaves lambda and M13 DNA yielding distinct fragments just as endonucleases of II and III types but, in contrast to them can produce two two-strand cuts separated with 30 to 32 nucleotides in the region of the recognition site.     

Site-specific endonuclease BstM6I from Bacillus stearothermophilus M6]

A site-specific endonuclease activity was found in extract of Bacillus stearothermophilus M6 isolated from molasses. The functionally pure enzyme designated as BstM6I was obtained by consecutive chromatographies on blue sepharose, hydroxyapatite, and heparin-sepharose. The endonuclease recognizes the nucleotide sequence CC decreases WGG in double-stranded DNA and cleaves it as indicated by the arrow to give one-nucleotide 5'-protruding ends. Consequently, the site-specific endonuclease BstM6I is an isoshizomer of BstNI.