[Effects of weak magnetic fields on different phases of planarian regeneration].

We analyzed the effects of weak combined magnetic fields, tuned to the cyclotron resonance condition for calcium ions, obtained in different phases of planarian regeneration. We showed that the result of regeneration in 72 hours after decapitation depends on the length of exposure, and the time between decapitation and initiation of a half-hour exposure. The experimental dependence can be explained by a multiplicity of enzymatic targets activated in different phases of the regeneration process.

[Synthesis and immunogenic properties of peptides--fragments of the immunodominant regions of the VP1 protein of the Asia-1 type of foot- and-mouth disease virus]. / Sintez i immunogennye svoistva peptidov--fragmentov immunodominantnykh raionov belka VP1 virusa iashchura tipa Aziia-1.

Potential immunodominant epitopes were predicted on the basis of a theoretical analysis of the antigenic structure of the VP1 protein of the type Asia-1 foot-and-mouth disease virus. Peptides corresponding to the 140-153, 136-153, 132-153, 143-157, 137-157, and 193-208 fragments of the VP1 protein sequence were synthesized by the solid phase method, and the immunogenic properties of the peptides were studied on guinea pigs. The shortest peptide exhibiting the protective effect was found to correspond to the, 140-153 fragment of the VP1 sequence. The Plm-(Gly)3-(140-153)-(Gly)2-Lys(Plm)-Leu and [Ac-(140-153)-(Gly)3]8-(Lys)7-Gly synthetic constructions in combination with adjuvants provided up to 80% protection of immunized animals against infection with the foot-and-mouth disease virus.

[The use of synthetic peptides for detection of antibodies against foot-and-mouth disease virus in the blood from convalescent animals]. / Ispol'zovanie sinteticheskikh peptidov dlia vyiavleniia antitel k virusu iashchura v syvorotkakh krovi perebolevshikh zhivotnykh.

Peptides were synthesized, which, according to theoretical analysis of the antigenic structure of protein VP1 of foot-and-mouth disease (FMD) virus types A, 0, and Asia 1, corresponded to potential immunodominant protein sites. Activities of the peptides were studied by solid-phase indirect radioimmunoassay on polyethylene film with purified immunoglobulins against intact FMD virus. Virtually no cross reactions were observed. Blood sera of cattle convalescent after FMD were tested with the FMD virus and peptides containing VP1 fragments 141-160 (A22 No. 550), 140-160 (O1 No. 194), and 140-153 (Asia 1 No. 48). The specificity of interactions between the sera and peptides and the virus was uniform, this permitting the identification of the virus type which caused the disease.

[A further study of the mutation process in Chinese hamster cells in vitro]. / Dal'neishee izuchenie mutatsionnogo protsessa v kletkakh kitaiskogo khomiachka in vitro

Spontaneous mutagenesis and mutagenesis induced by chemical mutagens in culture Chinese hamster cells were investigated. Appearance of mutations controlling the resistance to 6-mercaptopurine (6M) and reverse mutations to sensitivity was studied. The rate of spontaneous mutations of 6M resistance in cells studied was found to be sufficiently stable: it was independent on the repeated freezing of these cells and the duration of their cultivation. 5-bromodeoxyuridine (BUdR) has been shown to induce mutations to 6M resistance in cells of the 237i clone; the rate of induced mutations in some experiments as compared to the rate of spontaneous mutations was 1-2 orders higher. No clear-cut delay of phenotypic expression of BUdR-induced mutations was found. Seven independently arisen mutant clones were isolated. Five of them appeared spontaneously and two clones were induced by BUdR. Three spontaneously arisen clones were found to be reversible to sensitivity. The rate of reverse mutations in cells of the other four clones, did not exceed (2,3-3,5)-10(-6) per cell per generation. The rate of spontaneous reverse mutations in these clones was less at least one order lower as compared to the rate of spontaneous mutations to 6M-resistance. The attempts to induce reverse mutations to sensitivity by N-nitrosomethylurea in spontaneously reversible resistant cells and by BUdR in mutant cells arisen as a result of the treatment with the same agent proved unsuccessful. A method of estimation of experiment's resolving power is described for cases, when no expected events (in our study reverse mutations) were observed.

[Hybridization of Chinese hamster cells sensitive to ultraviolet irradiation]. / Gibridizatsii kletok kitaiskogo khomiachka, chuvstvitel'nykh k ul'trafioletovomu oblucheniiu.

Resistance to UV-light was studied in two UV-sensitive aneuploid Chinese hamster cell clones to different origin and degree of sensitivity, their respective polyploids and somatic cell hybrids. The karyotype of the parental clones, cell hybrids and polyploids was analyzed in parallel. A great variability of karyotypes was detected in hybrid cells. Serial cultivation of hybrids was accompanied by chromosome loss. Soon after fusion the hybrid clones proved to be more resistant to UV than the parental sensitive cells. However, their sensitivity increased with passages. The comparison of UV-sensitivity with data on karyotype analysis allowed to assume that the increase in sensitivity was correlated with the loss of particular chromosomes or chromosome regions. The results obtained indicated the existence of a polygenic control of UV-sensitivity, the multiple genes being assigned to different chromosomes. A reverse effect of ploidy was detected, i.e. a decrease in the resistance to the lethal action of UV-light in polyploids as compared to the parental clones.

[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]. / Issledovanie kletok kitaiskogo khomiachka, mutantnykh po lokusu gipoksantin-guanin-fosforiboziltransferzay. Soobshchenie IV. Biokhimicheskaia kharakteristika gipoksantin-guanin-fosforiboziltransferazy gibridnykh klonov, poluchennykh pri vnutrigennoi komplementatsii.

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.

[Chinese hamster cells with mutation in the hypoxanthine-guanine phosphoribosyltransferase locus. III. The biochemical characteristics of the hypoxanthine-guanine phosphoribosyltransferase of complementing mutants]. / Issledovanie kletok kitaiskogo khomiachka, mutantnykh po lokusu gipoksantin-guaninfosforiboziltransferazy. Soobshchenie III. Biokhmicheskaia kharakteristika gipoksantin-guaninfosforiboziltransferazy komplementiruiushchikh mutantov.

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.

[Chinese hamster cells mutant for the hypoxanthine-guanine phosphoribosyltransferase locus. II. Characteristics of the hybrids revealing intragenic complementation]. / Issledovanie kletok kitaiskogo khomiachka, mutantnykh po lokusu gipoksantin-guaninfosboriboziltransferazy. Soobshchenie II. Nekotorye kharakteristiki gibridov, vyiavivshikh vnutrigennuiu komplementatsiiu.

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.

[Chinese hamster cell mutant at the hypoxanthine-guanine phosphoribosyltransferase locus. I. The collection of mutants and intragene complementation experiments]. / Issledovanie kletok kitaiskogo khomiachka, mutantnykh po lokusu gipoksantin-guaninfosforiboziltransferazy. Soobshchenie I. Kollektsiia mutantov i éksperimenty po vnutrigennoi komplementatsii.

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.

African swine fever in the Russian Federation: spatio-temporal analysis and epidemiological overview.

African swine fever is viral disease of domestic and wild pigs which leads to almost total mortality and causes great economic losses due to absence of vaccine. Having been introduced into the Russian Federation in 2007 the disease has spread widely in the southern region of the country and since 2011 has demonstrated a tendency to form a secondary endemic zone in the central part of the country. In the present study spatio-temporal patterns of ASF diffusion in the populations of wild and domestic pigs are analyzed. The structure of the domestic swine population is conventionally divided into a sub-population at low biosecurity (77% of the total number of outbreaks in domestic pigs) and a population at high biosecurity (23%). The statistics of ASF cases registered in each of these sub-populations is presented. The possible causes of ASF diffusion across the country are discussed. The use of geo-information technologies (GIS) enabled confirmation of the conclusion that an epidemic center has shifted into the central part of Russia. The main conclusions of this study are that: (1) anthropogenic factors play the leading role in the spread of ASF across the territory of the RF; (2) small-scale private holdings (low biosecurity population) are more exposed to ASF virus introduction; (3) there is a high risk of diffusion of ASFV from the secondary endemic zone in the central part of the RF to neighboring regions.