Molecular phylogenetic study of the systematic position of Baikalian oligochaetes in the system Clitellata

Phylogenetic relationships within the class Clitellata were examined using nucleotide sequences of nuclear 18S ribosomal RNA gene fragments. In the analysis, the already determined sequences for the individual species representing the class members Hirudinea, Acanthobdellida, Branchiobdellida, and Oligochaeta were included. Furthermore, newly determined sequences of the thirteen representatives of the family Lumbriculidae. including 12 Baikalian endemic species, were analyzed. The hypothesis on the close relatedness of these four groups of Clitellata was supported. Leeches, branchiobdellidans, and lumbriculides form three independent parallel branches of evolution. These results were consistent with the hypothesis on the role of the family Lumbriculidae as a connecting link, or the transition form between the parasitic and free-living groups of Clitellata. At the same time, these data refute the suggestion that Lumbriculidae could be the ancestral lineage of other Oligochaeta. Moreover, polymorphic group of Baikalian lumbriculides clustered independently from the other representatives of the family, pointing to the uniqueness of the Baikalian fauna of oligochaetes, which was formed within relatively closed system of this ancient lake.     

Double-strand break repair in bacteriophage T4: coordination of DNA ends and effects of mutations in recombinational genes

Coordination of DNA ends during double-strand break (DSB) repair was studied in crosses of bacteriophage T4 in which DSBs were induced site-specifically by SegC endonuclease in the DNA of only one of the parents. Coupling of the genetic exchanges to the left and to the right of the DSB was measured in the wild-type genetic background as well as in T4 strains bearing mutations in several recombination genes: 47, uvsX, uvsW, 59, 39 and 61. The observed quantitative correlation between the degree of coupling and position of the recombining markers in relation to the DSB point implies that the two variants of the splice/patch-coupling (SPC) pathway, the "sequential SPC" and the "SPC with fork collision", operate during DSB repair. In the 47 mutant with or without a das suppressor, coupling of the exchanges was greatly reduced, indicating a crucial role of the 47/46 complex in coupling of the genetic exchanges on the two sides of the DSB. From the observed dependence of the apparent coupling on the intracellular ratio of breakable and unbreakable chromosomes in different genetic backgrounds it is inferred that linking of the DNA ends by 47/46 protein is the mechanism that accounts for their concerted action during DSB repair. A mechanism of replicative resolution of D-loop intermediate (RR pathway) is suggested to explain the phenomenology of DSB repair in DNA arrest and uvsW mutants. A "left"-"right" bias in the recombinogenic action of two DNA ends of the broken chromosome was observed which was particularly prominent in the 59 (41-helicase loader) and 39 (topoisomerase) mutants. Phage topoisomerase II (gp39-52-60) is indispensable for growth in the DNA arrest mutants: the doubles 47(-)39(-), uvsX 39(-) and 59(-)39(-) are lethal.     

Differentiation of capripoxvirus species and strains by polymerase chain reaction

A fast and simple method for capripoxvirus species identification has been developed. The method is based on multiplex polymerase chain reaction (MPCR) with species-specific primers and does not require nucleotide sequencing or restriction analysis of PCR products. To differentiate vaccine strains used in Russia and countries of the former Soviet Union from epizootic isolates of sheeppox virus, a method based on restriction analysis of the ankyrin-repeat protein gene fragment amplified by PCR has been developed. Being highly specific, both methods may be used for routine diagnosis of capripoxvirus-associated diseases.     

Recombinant non-structural 3A, 3B and 3AB proteins of foot-and-mouth disease virus: use for differentiation of vaccinated and infected cattle

Recombinant proteins 3A, 3B and 3AB were obtained by expression in Escherichia coli and purified by metal-chelate chromatography. The proteins were used as antigens in indirect ELISA to differentiate vaccinated and infected cattle. While testing 200 sera from cattle 3A-ELISA was more sensitive and specific than 3B- and 3AB-ELISA. Compared with "Chekit FMD-3ABC", 3A-ELISA showed the same level of specificity and higher level of sensitivity.     

Bioactive Components in Methyl tert-Butyl Ether Extract of Sea Buckthorn (Hippophae rhamnoides L.) Green Waste

Russian Journal of Bioorganic Chemistry - Lipophilic constituents of sea buckthorn leafy shoots, which is a large-scale waste product of sea buckthorn oil production and rejuvenating pruning of...     

Nanocrystaline ceria based materials--perspectives for biomedical application

Nanocrystalline ceria possesses a unique complex of physical and chemical properties making it highly bioactive material. In this review, modern data on the action of nanocrystalline ceria on cells, micro- and macroorganisms are analyzed. Special attention is paid to the analysis of the factors affecting protective properties of CeO2 with respect to the living systems.     

Genetic reconstruction of protozoan rRNA decoding sites provides a rationale for paromomycin activity against Leishmania and Trypanosoma

Aminoglycoside antibiotics target the ribosomal decoding A-site and are active against a broad spectrum of bacteria. These compounds bind to a highly conserved stem-loop-stem structure in helix 44 of bacterial 16S rRNA. One particular aminoglycoside, paromomycin, also shows potent antiprotozoal activity and is used for the treatment of parasitic infections, e.g. by Leishmania spp. The precise drug target is, however, unclear; in particular whether aminoglycoside antibiotics target the cytosolic and/or the mitochondrial protozoan ribosome. To establish an experimental model for the study of protozoan decoding-site function, we constructed bacterial chimeric ribosomes where the central part of bacterial 16S rRNA helix 44 has been replaced by the corresponding Leishmania and Trypanosoma rRNA sequences. Relating the results from in-vitro ribosomal assays to that of in-vivo aminoglycoside activity against Trypanosoma brucei, as assessed in cell cultures and in a mouse model of infection, we conclude that aminoglycosides affect cytosolic translation while the mitochondrial ribosome of trypanosomes is not a target for aminoglycoside antibiotics.     

Double-strand break repair and recombination-dependent replication of DNA in bacteriophage T4 in the absence of UvsX recombinase: replicative resolution pathway

The effects of mutations in bacteriophage T4 genes uvsX and 49 on the double-strand break (DSB)-promoted recombination were studied in crosses, in which DSBs were induced site-specifically within the rIIB gene by SegC endonuclease in the DNA of only one of the parents. Frequency of rII+ recombinants was measured in two-factor crosses of the type i×ets1 and in three-factor crosses of the type i×ets1 a6, where ets1 is an insertion in the rIIB gene carrying the cleavage site for SegC; i's are rIIB or rIIA point mutations located at various distances (12-2040 bp) from the ets1 site, and a6 is rIIA point mutation located at 2040 bp from ets1. The frequency/distance relationships were obtained in crosses of the wild-type phage and of the amber mutant S17 (gene uvsX) and the double mutant S17 E727 (genes uvsX and 49). These data provide information about the frequency and distance distribution of the single-exchange (splices) and double-exchange (patches) events. The extended variant of the splice/patch coupling (SPC) model of recombination, which includes transition to the replication resolution (RR) alternative is substantiated and used for interpretation of the frequency/distance relationships. We conclude that the uvsX mutant executes recombination-dependent replication but does it by a qualitatively different way. In the absence of UvsX function, the DSB repair runs largely through the RR subpathway because of inability of the mutant to form a Holliday junction. In the two-factor crosses, the double uvsX 49- is recombinationally more proficient than the single uvsX mutant (partial suppression of the uvsX deficiency), while the patch-related double exchanges are virtually eliminated in this background.     

Phytotoxic Activities of Chernozem Saprotrophic Micromycetes: Specificity,Sorption, and Stability of Phytotoxins in Soil

Micromycetes of the complex of typical chernozem saprotrophic fungi released phytotoxic metabolites into their growth medium. The metabolites displayed their phytotoxic activities directly in soil. Evaluation of the toxicity, range of biological effects, activity, and stability of the phytotoxins in soil, as well as of the rates of their biodegradation, made it possible to select species that can serve as indicators of microbial toxicosis of chernozem (Aspergillus clavatus, Fusarium solani, Talaromyces flavus, Penicillium rubrum, and P. funiculosum).