Laboratory rat selection for the trait “the absence of audiogenic seizure proneness”

The hybrids between Krushinsky-Molodkina (KM) inbred strain, selected for high predisposition to audiogenic epilepsy (AE), and Wistar rats non-prone to audiogenic seizure were the initial population for selection. Rats were selected for the trait ??the absence of audiogenic seizure proneness??. The creation of such strain in which the significant proportion of animals develop no AE in response to sound and share partly the genetic background of the KM strain is very important for the correct use of KM strain as the laboratory model of seizure states. As alleles which determine the AE proneness are recessive the selection for the ??opposite?? trait proceeds necessarily slow.     

Specific Features of Nitrogen Fixation and Denitrification in Termites Neotermes castaneus, Zootermopsis angusticollis, and Reticulitermes lucifugus

We studied specific features of microbial nitrogen fixation and denitrification in laboratory cultures of the termites Neotermes castaneus, Zootermopsis angusticollis, and Reticulitermes lucifugus, as well as in their nest materials. The nitrogenase activity in the termites was much higher than in the materials of termitarium. Denitrification was found only in the nest materials of termitarium. Studies of the bacterial community of gut nitrogen fixers Neotermes castaneus have shown the predominance of anaerobic and facultatively anaerobic bacteria that amount to up to 60% of the total number of gut bacteria. In the materials of termitarium, aerobic cellulose-destroying myxobacteria predominated, which are typical inhabitants of plant substrates, a food for the termites.     

TaqMan probes based on oligonucleotide-hairpin minor groove binder conjugates

Hybridization of TaqMan probes derived from oligonucleotides containing fluorophores (fluorescein, FAM, or tetramethylrhodamine, (Tamra)), fluorescence quenchers (BHQ1 or BHQ2), and a conjugated hairpin binder (MGB) composed of two tripyrrolcarboxamide residues connected through an aminobutyric acid residue were proposed for discrimination of single base mismatch using the real time PCR technique. Identification of A/C mismatch was shown to be highly specific for hepatitis C virus subtypes 1a and 1b with two variants of the probe (5′-3′): Tamra-ATTGAGCGGGTTTAp-BHQ2-MGB for subtype 1a and FAMATTGAGCGGGTTGAp-BHQ1-MGB for subtype 1b. Perfect duplexes (A·T-and G·C pairs) increase fluorescence in the process of amplification, whereas imperfect duplexes (A·G-and T·C pairs) induce no fluorescence changes. This phenomenon enables simultaneous genotyping of hepatitis C virus subtypes 1a and 1b.     

Oligonucleotide conjugates with minor groove ligands as probes for hybridization microarray chips

A possibility of using oligonucleotide conjugates with minor groove ligands as probes for hybridization microarray chips was studied. The oligonucleotide conjugates contain a hairpin ligand (MGB) composed of two tripyrrolcarboxamide residues with an aminocaproic acid residue as a linker and bound to the oligonucleotide duplex AT tract in a site-specific manner. We used as (5′-3′)-probes: GACAAGAp, GACAAAAp, GACAAGA-MGB, and GACAAAA-MGB. The oligonucleotides labeled with the Cy3 cyanine dye, Cy3-ACTAATTTTGTC and Cy3-ACTAATCTTGTC, were used as targets. The maximal MGB effect on the fluorescence level of microarray chip spots, which caused its fourfold increase as compared with the initial unmodified duplex, was observed for the duplex containing only AT pairs in the ligand binding site. The presence of AC and GT mutations in the binding site (imperfect duplexes) or a CG pair (perfect duplex) affect the change in fluorescence level to a considerably lesser degree.     

Subtyping of influenza virus A hemagglutinine with hybridization microarray

An oligonucleotide microarray for influenza A hemagglutinine subtyping was presented. The number of probes for determination of each subtype hemagglutinine (H1-H13, H15, H16, pandemic flu H1N1)varied from 13 to 28. When testing of the microarray using 40 type A influenza virus isolates the hemagglutinin subtypes were unambiguously determined for 36 specimens.     

Subtyping of influenza virus A hemagglutinin with a hybridization microarray

An oligonucleotide microarray for influenza A hemagglutinin subtyping was presented. The number of probes for the determination of each subtype of hemagglutinin (H1-H13, H15, H16, pandemic flu H1N1) varied from 13 to 28. When testing the microarray using 40 type-A influenza virus isolates, the hemagglutinin subtypes were unambiguously determined for 36 specimens.     

Limited Proteolysis of Bacillus thuringiensis CryIG and CryIVB δ-Endotoxins Leads to Formation of Active Fragments That Do Not Coincide with the Structural Domains

Bacillus thuringiensis true toxins consist of three domains: the N-terminal, -helical domain followed by two -structural domains. Their limited proteolysis does not proceed at the domain boundaries, but is directed to the loops within the domains. There are at least two patterns of the limited proteolysis of true toxins. The first pattern, observed for CryIA and CryIVD -endotoxins, results in the proteolysis of the loops connecting -strands of the second domain. The second pattern, detected for CryIG and CryIVB proteins, consists in the cleavage of the loop connecting the fifth and the sixth -helixes of the first domain. The choice between the routes depends on the size, sequence, and dynamics of the loop that define its accessibility to a proteinase. Bioassay of CryIG and CryIVB -endotoxin fragments indicates that only two -helixes, the sixth and the seventh within the first domain, followed by the two -structural domains are sufficient for the insecticidal activity.     

Limited Proteolysis of Bacillus thuringiensis CryIG and CryIVB δ-Endotoxins Leads to Formation of Active Fragments That Do Not Coincide with the Structural Domains

Bacillus thuringiensis “true” toxins consist of three domains: the N-terminal, α-helical domain followed by two β-structural domains. Their limited proteolysis does not proceed at the domain boundaries, but is directed to the loops within the domains. There are at least two patterns of the limited proteolysis of “true” toxins. The first pattern, observed for CryIA and CryIVD δ-endotoxins, results in the proteolysis of the loops connecting β-strands of the second domain. The second pattern, detected for CryIG and CryIVB proteins, consists in the cleavage of the loop connecting the fifth and the sixth α-helixes of the first domain. The choice between the routes depends on the size, sequence, and dynamics of the loop that define its accessibility to a proteinase. Bioassay of CryIG and CryIVB δ-endotoxin fragments indicates that only two α-helixes, the sixth and the seventh within the first domain, followed by the two β-structural domains are sufficient for the insecticidal activity.     

Novel antibacterial proteins from entomocidal crystals of Bacillus thuringiensis ssp. israelensis

Proteins with molecular masses of 36 and 34 kDa (Bti36 and Bti34) were isolated from entomocidal crystals formed by Bacillus thuringiensis ssp. israelensis cells. The samples of Bti36 contained the admixture of a protein with a molecular mass of 33 kDa (Bti33), apparently a product of proteolysis of Bti36. These 3 proteins are significantly different in N-terminal sequences from known delta-endotoxins of B. thuringiensis and show antibacterial activity toward Micrococcus luteus. The combination of Bti36 and Bti33 also suppresses the growth of some other microorganisms including Streptomyces chrysomallus. The effects of the mixture of Bti36 and Bti33 on the M. luteus cell surface and on the surface of S. chrysomallus cells and exospores are similar, but they are different from the effect of endotoxin Cry11A on micrococcal cells.     

Spatial peculiarities of rhizoplane colonization by microscopic fungi

Spatial peculiarities in the colonization of the tomato, cucumber, and barley rhizoplanes by microscopic fungi were studied. The apical zone of roots was colonized with a limited number of R strategists (the order Mucorales, Fusarium sp., Aspergillus niger, and Mycelia sterilia). The fungal population of the root hairs and the basal zone of roots was 2- to 3-fold more dense due to the prevalence of K strategists. Fusaria, Fusarium oxysporum in particular, colonized roots in earlier terms than the genera Trichoderma, Penicillium, Gliocladium, and others. The F. oxysporum population was at a maximum in the rhizoplane zone nearest the root tip.