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Biomedical subjects

A A Zharkikh

Publications and source records attributed to A A Zharkikh.

At least 19 recordsLinked to original sources
PubMed2005

Structure of equine 2'-5'oligoadenylate synthetase (OAS) gene family and FISH mapping of OAS genes to ECA8p15-->p14 and BTA17q24-->q25.

Mammalian 2'-5' oligoadenylate (2-5A) synthetases are important mediators of the antiviral activity of interferons. Both human and mouse 2-5A synthetase gene families encode four forms of enzymes: small, medium, large and ubiquitin-like. In this study, the structures of four equine OAS genes were determined using DNA sequences derived from fifteen cDNA and four BAC clones. Composition of the equine OAS gene family is more similar to that of the human OAS family than the mouse Oas family. Two OAS-containing bovine BAC clones were identified in GenBank. Both equine and bovine BAC clones were physically assigned by FISH to horse and cattle chromosomes, ECA8p15-->p14 and BTA17q24--> q25, respectively. The comparative mapping data confirm conservation of synteny between ungulates, humans and rodents.

2',5'-Oligoadenylate Synthetase↗
PubMed1999

[Effect of the cytoskeleton dynamic condition on the neuronal plasticity].

Infringement of the Lymnaea stagnalis cytoskeleton condition affected preservation and repeated development of plastic responses. Stabilising of the microtubules led to a dependence of the development and preservation dynamics of the plastic responses. Stabilising of the microfilaments transformed short-term plastic responses into long-term ones. The findings suggest a key role of reorganisation of the cytoskeleton in neuronal plasticity.

Action Potentials↗
PubMed1993

Statistical analysis of L-tuple frequencies in eubacteria and organelles.

This work is an attempt to study the structural features and evolutionary patterns of nucleotide sequences by analyzing their 1- through 4-plet frequencies and statistical relations between them. We present mathematical apparatus for this analysis. In particular, we introduce criteria to estimate the degree of homogeneity of L-plet composition in a given set of sequences and the dependence of the L-plet frequencies on the composition of lower orders. We apply these criteria to the study of eubacteria, mitochondria and chloroplasts. We demonstrate that L-plet frequencies are quite useful for revealing evolutionary relationship between DNA sequences and that the non-random distribution is more typical for doublets than to triplets. Non-randomness of triplet composition is more characteristic to coding than to non-coding regions, while no significant differences in dinucleotide composition can be observed. The obtained results can be used for revealing possible mechanisms of the codon usage phenomena.

Analysis of Variance↗
PubMed1993

[Sequences resembling fragments of mitochondrial DNA in the human genome: features of evolution].

Mitochondrial-like sequences and their homologues from primate mitochondria are investigated to define direction and rate of evolution, time of integration into nuclear genome. The analysis showed that mito-like sequences differ from mitochondrial homologues by high level of symmetria of two chains of DNA. Besides that, difference between mito-like and Homo sapiens sequences in their GC-contents is found. Apparently there is GC-pressure of nuclear genome region, being the place of integration of mito-like sequence, that brings about equalization of GC-contents in nuclear region and mito-like sequences. Properties of descent mitochondrial sequence play important role in the difference of mito-like and Homo sapiens sequences also.

Base Composition↗
PubMed1991

VOSTORG: a package of microcomputer programs for sequence analysis and construction of phylogenetic trees.

VOSTORG is a new, versatile package of programs for the inference and presentation of phylogenetic trees, as well as an efficient tool for nucleotide (nt) and amino acid (aa) sequence analysis (sequence input, verification, alignment, construction of consensus, etc.). On appropriately equipped systems, these data can be displayed on a video monitor or printed as required. They are implemented on IBM PC/XT/AT/PS-2 or compatible computers and hardware graphic support is recommended. The package is designed to be easily handled by occasional computer users and yet it is powerful enough for experienced professionals.

Amino Acid Sequence↗
PubMed1984

The template RNAs of RNA polymerases can have compact secondary structure, formed by long double helices with partial violations of the complementarity.

A new method of contextual analysis was used to search the long non-random inverted repeats and the complementary palindromes in the genes of E. coli and T7 RNA polymerases. These genes were found to contain from 25% to 50% of all the nucleotides involved in such helices. The 5' -and 3' -ends of mRNA can be protected by neighbouring double helices from the nuclease attack. Some double helices are competing and very similar to the attenuator of E. coli trp-operon.

Base Composition↗
PubMed1984

Fine cytogenetical analysis of the band 10A1-2 and the adjoining regions in the Drosophila melanogaster X chromosome. III. The fate mapping of the lethal focus of the l(1)BP4 gene.

Focuses of the l(1)BP4, vermilion and sevenless genes located in the same band 10A1-2 of Drosophila melanogaster X-chromosome, have been compared. For this purpose first the fate map of the blastoderm for 60 pairs of adult cuticular landmarks has been built based on scoring 612 gynandromorphs. The location of the legs and antenna primordia has been defined more exactly as compared to analogous maps by other authors. The location of new landmarks has been carried out: mesosternal bristle, sex-comb and first tergite primordia. The focus of the l(1)BP4 gene has been determined with the help of this map on the basis of analysis of 321 mosaics. The data obtained show that the lethal focus of the gene belongs to the "bilateral domineering" type and is located in the blastula area giving rise to the nervous system, behind the region of the third thoracic ganglia origin. Beside, there is a pair of autonomous nonlethal focuses of the same gene limited by the wings' zone. The focuses of the l(1)BP4 gene do not coincide with the known focuses of vermilion and sevenless genes, which means that all three genes are active in different tissues.

Animals↗
PubMed1984

An estimation of the degree of the genetic divergence of sibling species Microtus arvalis and Microtus subarvalis (Rodentia) based on electrophoretic analysis.

The electrophoretic mobilities of 52 enzymes and proteins were used as measures of the genetic similarity between the sibling species Microtus arvalis and M. subarvalis. The two vole species differed in the electrophoretic mobilities of seven (glucose-6-phosphate dehydrogenase, adenylate kinase, diaphorase, lactate dehydrogenase-A, alpha-galactosidase, 6-phosphogluconate dehydrogenase, and hemoglobin) of these markers. This allowed us to accept the seven markers assayed as species-specific markers. Based on the frequency distribution of the genes at the polymorphic loci of M. arvalis and M. subarvalis, the degree of their genetic similarity was estimated as 0.312 and the genetic distance as 1.164 by Nei's formula. The estimates for genetic similarity were close to those obtained for species recognized as distinct.

Animals↗
PubMed1984

Conformational changes in the globin family during evolution. 1. Analysis of the evolutionary role of insertions and deletions.

Conformational restrictions imposed on the fixation of insertions and deletions by the three-dimensional structure of globins during evolution are analyzed. An evolutionary tree for the primary structure of 38 taxonomically distant globins was constructed by a computer method. Based on this tree, the calculated fixation frequency of point mutations was 50-fold higher than that established jointly for deletions and insertions, and the fixation frequency of deletions was more than three times that established for insertions. It was also found that deletions and insertions are predominantly fixed in the interhelical sections and at the ends of the alpha-helices of the globin molecules. Conformational analysis of the packing of the alpha-helices in the spatial structure of globins demonstrated that the fixation of deletions and insertions in the center of an alpha-helix produces a marked distortion of their normal packing. The possible role of deletions and insertions in the evolution of protein families is discussed.

Animals↗
PubMed1984

[Evaluation of the degree of genetic divergence in the twin species of the common vole Microtus arvalis and Microtus subarvalis (Rodentia)].

By means of starch electrophoresis, 52 proteins and enzymes of Microtus arvalis and M. subarvalis were studied to establish the extent of their similarity. Out of 52 markers studied, 7 proteins and enzymes had different electrophoretic mobility: glucose-6-phosphate dehydrogenase (G6PD), phosphogluconate dehydrogenase (PGD), diaphorase (DP), adenylate kinase (AK), lactate dehydrogenase B (LDHB), alpha-galactosidase (GAL) and hemoglobin (Hb), which make up to 13% of all the enzymes and proteins studied. The differences found between the two species studied by electrophoretic mobility of G6PD, AK, GAL and Hb, as well as the absence of intraspecific polymorphism for the above proteins permit to consider these proteins as species-specific markers, with the help of which M. arvalis and M. subarvalis can be distinguished. It should be emphasized that intraspecific polymorphism was found for PGD, LDHB and DP in M. arvalis, while in M. subarvalis these proteins were monomorphic and identical, in their electrophoretic mobility, to one of electrophoretic variants of M. arvalis. Therefore, only one of allelic variants of PGD, LDHB and DP is species-specific. Estimation of the extent of genetic similarity based on analysis of distribution of gene frequencies for polymorphic loci of M. arvalis and M. subarvalis by means of Nei's method gave the value of 0.312, the genetic distance being 1.164. The data obtained, together with the known cytogenetic data, point to a species rank of the species studied. Moreover, in spite of the morphological similarity between M. arvalis and M. subarvalis, the estimation of genetic similarity proved to be close to that for morphologically contrasting species.

Alleles↗
PubMedDate not supplied

Effects of changes in dynamic equilibrium in microtubule and microfilament systems on the plastic responses of neurons.

Studies were carried out on the effects of disruption and stabilization of microtubules and microfilaments on the formation of neuronal plastic responses in isolated nerve cells of the mollusk Lymnaea stagnalis. Disruption of these cytoskeletal elements prevented the development of neuronal plastic responses. Microtubule stabilization produced a dynamic relationship between the development and retention of neuronal plastic responses and series of stimuli. Stabilization of microfilaments blocked the development but promoted the retention of these neuronal responses.

Actin Cytoskeleton↗
PubMedDate not supplied

The effects of the dynamic state of the cytoskeleton on neuronal plasticity.

The effects of degrading and stabilizing microtubules and microfilaments on the formation of plastic reactions were studied in isolated nerve cells from the mollusk Lymnaea stagnalis. Degradation of the cytoskeleton affected the performance, retention, and repeated acquisition of plastic reactions. Stabilization of microtubules led to the appearance of a relationship between the dynamics of the development and retention of plastic reactions and the series of stimulation. Stabilization of microfilaments led to transient plastic reaction, along with long-term reactions. These results show that rearrangements of the cytoskeleton have a key role in the processes of neuronal plasticity.

Actin Cytoskeleton↗