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L V Volkova

Publications and source records attributed to L V Volkova.

At least 19 recordsLinked to original sources
PubMed2006

[Retroviral-mediated gene transfer as an effective tool for the in vitro genetic transformation of chicken embryonic cells and production of transgenic chickens].

The data on the in vitro and in vivo (into embryonic disk) retroviral-mediated transfer of genetic information into chicken embryonic cells are presented. The estimated transformation frequency of the cultured target cells constituted 8 x 10(-4) to 5 x 10(-3). A transgenic rooster, carrying recombinant DNA in blood, heart, liver, and intestine cells, was obtained.

Animals↗
PubMed2005

[Modification of the sunflower defensin SD2 gene sequence and its expression in bacterial and yeast cells].

To achieve broader range of the defensin antimicrobial activity, based on the sd2 gene sequence, the modified gene, sd2mod, was constructed. Hybrid genes, sd2-licBM2, licBM2-sd2, licBM2-sd2mod, and sd2mod-licBM2, in which the wild-type and modified gene sequences were fused in frame with the reporter gene encoding thermostable lichenase, were constructed. Expression of the wild-type, modified, and hybrid genes was examined in the cells of pro- and eukaryotes. It was demonstrated that these genes were efficiently expressed in the cells of lower eukaryotes, the yeast. Inhibiting effect of the SD2 and SDmod proteins as the components of the hybrid proteins, SD2-LicBM2 and SD2mod-LicBM2, on the growth of the Fusarium culmorum hyphae was similar to that of the wild-type and modified proteins. It was shown that the presence of lichenase in the hybrid proteins facilitated selection and analysis of the hybrid proteins expression in transgenic organisms.

Amino Acid Sequence↗
PubMed1996

[Construction and analysis of transgenic plants of Nicotiana tabacum L. expressing a bacterial gene for beta-1,3-glucanase. I. Construction of vector plasmids for transfer into plants and expression of a modified gene for beta-1,3-glucanase from Clostridium thermocellum in tobacco protoplasts].

We constructed two vectors, pC27-glc and pC29-glc, that allow expression of the beta-1,3-glucanase gene (glc) in plant cells. The glc gene was previously cloned from anaerobic thermophilous bacterium Clostridium thermocellum. To increase the efficiency of expression, the N-terminal fragment of the glc gene encoding bacterial transient peptide was deleted, and hybrid variants of lacZ-glc were obtained. Analysis of expression of the hybrid genes in Escherichia coli showed that deletion of the fragment corresponding to 31 amino acids (a.a.) of beta-glucanase affected neither activity nor thermostability of the enzyme. The modified gene was subcloned into two vectors, pC27 and pC29, in which its expression was controlled by the TR2' promoter of the 2' gene of T-DNA and the rbcS promoter from Arabidopsis, respectively. Each of the resulting plasmids, pC27-glc and pC29-glc, was transfected into protoplasts of Nicotiana plumbaginifolia. Both the plasmids were shown to allow a high level of activity of the thermostable beta-1,3-glucanase. We plan to use the vectors obtained for transformation of agrobacteria and construction of transgenic plants.

Base Sequence↗
PubMed1993

[The effect of physical loads of differing intensities on the lymphoid tissue elements of the thymus and spleen].

The amounts of blast, large lymphocytes and mitotically divided cells were histologically and morphometrically studied in the thymus and spleen in 24 BALB/c female mice during exercises of varying intensity which were induced by swimming and during restricted mobility. The latter was found to cause a greater increase in the above cells in the spleen. The similar changes, though less pronounced, were noted in the thymus during intensive exercises. Moderate exercises and restricted mobility led to a reduction of the number of divided cells in the thymus, but doubled blasts and large lymphocytes.

Animals↗
PubMed1988

[Chinese hamster cells mutant at the hypoxanthine-guanine phosphoribosyltransferase (GPRT) locus. V. Complementation analysis of ts mutants].

Four temperature-sensitive HPRT clones were used for hybridological analysis, which led to increase in complementation rate about 5 times. The probability of complementation, in respect of the HPRT locus proved to be rather high: 14 of 45 hybridization-tested mutants had complementation ability (including 3 ts mutants). Analysis of the complementation rate among mutants revealed clear-cut dependence on the selection conditions: clones grown in a medium with 8-azaguanine showed most frequent complementation. The use of mutants with a new phenotype in hybridization analysis revealed four additional complementation groups, three of which are made of temperature-sensitive clones. Biochemical analysis revealed the presence of hybrid forms of the HPRT enzyme in all hybrids tested. This confirms the intragenic character of complementation. At present, the functional map of the HPRT locus is represented by 9 groups, including a group of mutants with no complementation ability.

Animals↗
PubMed1987

[Regional graft vs host reaction to H-Y antigen (immunological mechanisms)].

Structural changes in the regional popliteal lymph nodes have been studied in C57Bl/6 male mice at the peak of the reaction "graft-versus-host" to H-Y antigen. Morphological and morphometrical investigations have been carried out in three groups of males (10 animals in each group). The first group includes intact animals (the first control group). To the males of the second group (the second control group) lymphoid cells are inoculated from intact C57Bl/6 females. To the males of the third group (experimental group) lymphoid cells are inoculated from H-Y antigen immunized C57Bl/6 females (anti-H-Y effector lymphocytes). The popliteal lymph nodes of the male mice from the third group twice increase in their size comparing to those in the control (the first and the second groups). Miotic activity increases in them 4.5 times, amount of cellular blast forms in medullary cords--4 times and 10 times--in the light zone of the cortical substance. Ratio of macrophages and eosinophils in structural components of the lymph nodes studied changes; this is, evidently, connected with massive destructive progresses, that take place in the lymph nodes of the animals from the third group. The results of the morphological investigations are in agreement with the hypothesis suggested, explaining the mechanism of development of the regional reaction "graft-versus-host" to H-Y antigen, basing on idiotype-antiidiotype interaction (the idiotypic network in the immune system).

Animals↗
PubMed1986

[Structural changes in popliteal lymph nodes in the graft vs. host reaction to H-Y antigen in male C57BL/6-strain mice].

Regional popliteal lymph nodes in intact, control and experimental (I, II, III groups, respectively) have been studied by means of the morphometric method in male C57Bl/6 line mice at the pick of the reaction produced by injection of spleen cells and mesenteric lymph nodes obtained from syngenic females and repeatedly immunized to H-Y antigen (10 animals in each group). Injection of the cell suspensions from the immunized and intact females of the C57Bl/6 mice result nearly in two-fold increasing mass of the regional popliteal node at the expense of enlarged size of all its zones. Changes in cytoarchitectonics of the node structural components result from redistribution of certain cellular elements. The essential changes in the cell composition of the lymph nodes in the II and III male groups are accompanied with an increasing part of the stromal reticular cells. Simultaneously, content of small lymphocytes decreases significantly. In the III group of mice there is a sharp increase in the content of young forms of the lymphoid line cells in all structural components of the node, as well as in eosinophilic granulocytes in medullary cords. In the dark cortical zone of the nodes (III group) there occur tissue basophils (mast cells), that, together with increasing number of acidophilic granulocytes and appearance of neutrophilic cells, demonstrates that there is an inflammatory reaction in the organ studied as a response to the lymphocytic suspension injected. In the experimental group of the animals a complete disappearance of plasma cells is noted in the node cortex, but some increase of their part takes place in the medullary cords.

Animals↗
PubMed1985

Complementation analysis of locus for hypoxanthine guanine phosphoribosyltransferase in Chinese hamster cells.

The study deals with intragenic complementation between clones of Chinese hamster cells carrying mutations in the HPRT gene. All clones were of independent origin, selected in media containing one of three purine bases: 8-azaguanine (8 AG), 6-mercaptopurine (6MP), or 6-thioguanine (6TG). Some of the clones were spontaneous, others were induced by various mutagens. To make the study less time-consuming, an experimental set-up was proposed for simultaneous complementation testing of up to 10 clones. As a result, about 400 combinations of clones have been analyzed. Twelve pairs of complementating mutants have been identified in HAT medium. A linear complementation map has been constructed for the HPRT locus, showing five complementation groups. The changes in kinetic and other characteristics observed for mutant HPRT show that all the mutants studied carry structural gene mutations. Analysis of the biochemical characteristics of HPRT has revealed considerable differences between mutant enzymes in clones belonging to different complementation groups (three groups were examined). At the same time, the four mutant clones of complementation group II show similar HPRT characteristics, suggesting a relative similarity of their structural variants of the enzyme. The hybrid nature of HPRT in clones resulting from the fusion of mutant cells confirms the intragenic nature of complementation.

Animals↗
PubMed1983

[Chinese hamster cells mutant for the hypoxanthine-guanine phosphoribosyltransferase locus. IV. The biochemical characteristics of the hypoxanthine-guanine phosphoribosyltransferase of hybrid clones obtained by intragenic complementation].

A biochemical study of hypoxanthine-guanine-phosphoribosyltransferase (HPRT) has been carried out in hybrid clones of Chinese hamster cells obtained in complementation experiments. A wide range of biochemical characteristics made it possible to identify a hybrid form of HPRT differing from the enzyme of parental clones in virtually every hybrid tested. The presence of hybrid HPRT was detected by the changed kinetic properties of temperature sensitivity and electrophoretic mobility compared to the enzyme in mutant cells. Since HPRT consists of identical subunits, the hybrid nature of the enzyme in cells obtained through hybridization of HPRT-mutant clones may be regarded as evidence for intragenic complementation. None of the hybrid clones contained an enzyme with the normal properties. Groups of hybrids with similar biochemical characteristics of HPRT can be obtained, if one of the mutant partners involved in hybridization belongs to one and the same complementation group; the major characteristics of hybrid HPRT are then determined by the partner having the higher level of enzyme activity. The series of studies of intragenic complementation in the HPRT gene is summarized.

Animals↗
PubMed1983

[Centriolar complex in somatic cell hybrids (mouse X Chinese hamster)].

The ultrastructure of centriolar complex in interphase cells and in for a long time dividing somatic hybrid cells (mouse X Chinese hamster) has been investigated. It was found that in the majority of hybrid cells (about 80%) the centriolar complex consists of a higher quantity of centrioles than in the parent cells; the fine structure of the centriolar complex has features characteristic of the centrioles of both the parents; the numerous centrioles have a capacity of organizing individual poles of the spindle of division to constitute the ground for multipolar mitosis in the hybrid cells. Besides that, hybrid cells were found with the centriole number corresponding to that in diploid cells. According to our preliminary data, the ultrastructure of these hybrid centrioles is like that in murine cells.

Animals↗
PubMed1982

[Chinese hamster cells with mutation in the hypoxanthine-guanine phosphoribosyltransferase locus. III. The biochemical characteristics of the hypoxanthine-guanine phosphoribosyltransferase of complementing mutants].

The paper presents a biochemical study of hypoxanthine-guanine phosphoribozyltransferase (HRPT) in mutant clones of Chinese hamster cells showing an ability for complementation. In order to characterize HPRT, its kinetic properties, temperature sensitivity and electrophoretic mobility in polyacrylamide gel were assayed. According to the complementation map, the nine mutant clones studied can be divided into four complementation groups. All these clones have been shown to be mutants with respect to the HPRT structural gene, as they synthesize the structurally and functionally altered enzyme. A comparative biochemical analysis of HPRT in the four complementation groups revealed substantial differences in mutant enzymes from different groups; hence, the possibility of complementation on the molecular level. All biochemical characteristics of HPRT tested are similar in clones belonging to one and the same complementation group, which could indicate that they have the same structural variant of the enzyme, regardless of the manner in which the mutants were obtained. Having revealed the similarity and the distinctive features of mutant enzymes within complementation groups, the biochemical analysis confirmed the results of complementation analysis and added the structural information concerning mutant variants of the enzyme. Thus, the complementation map of the HPRT gene yielded by hybridological analysis has been tested and confirmed by an independent biochemical study. Complementation analysis applied to the HPRT mutants made it possible to identify qualitatively distinct groups. Each of these groups may be regarded as an allele of the gene, and the sum of the groups may be regarded as a series of multiple alleles.

Animals↗
PubMed1981

[Chinese hamster cell mutant at the hypoxanthine-guanine phosphoribosyltransferase locus. I. The collection of mutants and intragene complementation experiments].

A group of 59 Chinese hamster cell clones mutant for hypoxanthine-guanine phosphoribozyl-transferase (HGPRT) is described. The clones were collected from selective media containing three purine analogs, 8-azaguanine, 6-mercaptopurine and 6-thioguanine. Spontaneous mutants of an independent origin induced by different mutagens were studied. They differed by the degree of the HGPRT enzyme activity and their ability to grow in the presence of purine analogs and on a counter-selective HAT medium. Mutant clones showed "abnormal" combinations of resistance to both types of selective media and also lacked cross-resistance to different analogs of hypoxanthine and guanine. A possibility of intragenics complementation between various clones was studied. The scheme of experiments on complementation is proposed to make the work less time-consuming by virtue of a simultaneous testing of a clone group. Having used the method, 383 clone combinations were analyzed and 13 complementing pairs of mutants. were found.

Animals↗
PubMed1981

[Chinese hamster cells mutant for the hypoxanthine-guanine phosphoribosyltransferase locus. II. Characteristics of the hybrids revealing intragenic complementation].

After polyethylene glycol treatment of GPRT- mutant cells, 12 clones were isolated on the ATG medium showing intragenic complementation. Karyological analysis confirmed the hybrid nature of the clones isolated. The GPRT activity in the hybrid clones, as assessed in vitro, exceeded the sum of parental activities. In vivo incorporation of 14C-hypoxanthine showed the GPRT activity in the hybrids to be an order of magnitude higher than in the mutant parental cells. Moreover, the GPRT activity in the hybrid clones was found to increase considerably during cultivation on the ATG medium; hence, their ability to multiply on this selective medium. All hybrid cells surviving and multiplying on the ATG medium were shown to maintain a high enough resistance to 8-AG, 6-MP and, to somewhat less extent, to 6-TG. The frequency of complementation was determined for the cells of mutant clones selected on media with different purine base analogues. The complementation map for the GPRT locus was constructed and proved to be linear. Five groups of complementation were specified.

Animals↗