Results of the second stage of the investigation of the radiation mechanism of chiral influence (RAMBAS-2 experiment).

Results of the second stage of the RAMBAS (RAdiation Mechanism of Biomolecular ASymmetry) experiment on investigation of the radiation mechanism of the influence on chiral molecules are presented. Optical activity of samples of racemic mixtures of amino acids with heavy metals was compared prior to and after irradiation by electron flux from a radioactive source. It is found that the irradiation results in asymmetric degradation of both complexes and amino acids and in production of chiral asymmetry of the samples under study. These results confirm the conclusions inferred from the first stage of the RAMBAS experiment and could be important for the solution of the origin-of-life and biological homochirality problems.

First results of the RAMBAS experiment on investigation of the radiation mechanism of chiral influence.

The first results of the RAdiation Mechanism of Biomolecular ASymmetry (RAMBAS) experiment on investigation of the radiation mechanism of the influence on chiral molecules, as a factor leading to origination of chiral asymmetry are presented. It was found that irradiation of simple achiral materials by a flux of electrons from radioactive source initiated the synthesis of amino acids, and it resulted in asymmetric degradation and chiral asymmetry in a racemic mixture of amino acids. The results obtained can be important for the solution of the origin-of-life and biological homochirality problems.

[Variability and dynamics of micronuclei rate in participants of transatlantic march of the VIIth Ukranian Antarctic expedition]. / Izmenchivost' i dinamika chastoty mikroiader uchastnikov transatlanticheskogo perekhoda VII Ukrainskoi antarkticheskoi ékspeditsii.

The estimation of individual variability and group dynamics of micronuclei rate in buccal cells of participants of transatlantic march of the VIIth Ukrainian Antarctic expedition (Sevastopol--UAS "Akademik Vernadsky"--Sevastopol) was carried out. The general average rate of micronuclei was 2.20 per thousand. Individual values of micronuclei frequencies varied in wide limits. The maximum value of CV was 92.4% and the minimal one was 48.4%. Individual averages of micronuclei rates varied from 1.70 to 2.78 per thousand. Dependence of individual and group dynamics of micronuclei rates on environmental factors (temperature, atmospheric pressure and storm activity) was tested. No significant correlation of these parameters was found.

[The readaptation of the respiration, blood circulation and body oxygen regimen in aquanauts after saturation dives to depths of up to 450 m]. / Readaptatsiia dykhaniia, krovoobrashcheniia i kislorodnogo rezhima organizma akvanavtov posle saturatsionnykh pogruzhenii na glubiny do 450 m.

Main trace posthyperbaric and postdecompression responses to respiration, circulation and oxygen profiles, dynamics of their reduction in 99 aquanauts at pressure of 46 kgs/cm2 (0.46 mPa) during 14-30 day period have been studied. The respiratory changes were found to be characterized by: ventilatory function disorders which followed the obstructive-restrictive pattern; discoordination of ventilation regulation and slowing down of respiratory gas transport through aerohematic barrier. The hemodynamic shifts have been manifested as cardiac rhythm instability, heart pump function followed by decreased cardiac contractions on exercise exposures. The economy and efficiency of body oxygen profiles in a respiration loop become lower than that in hemodynamic loop. The rate of the alveolar oxygen supply is decreased to the levels lower than the rates of oxygen supply by arterial and mixed venous blood. The long-term functional rearrangement of respiratory gas transport followed by the phase changes combined with the specific and nonspecific reactions persisting over a period of 30-60 days and more longer after decompression, is existed.

[The dynamics of functional heart volumes in the descents of divers to depths of up to 15 m]. / Dinamika funktsional'nykh ob''emov serdtsa pri pogruzheniiakh vodolazov na glubiny do 15 m.

In an underwater environment at a depth up to 15 m the cardiodynamic parameters of resting and exercising man were recorded echocardiographically. Increased functional volumes of the heart and decreased ejection fraction (EF) have been noted. Underwater reactions of the cardiac functional volumes in response to exercise were characterized by: a maximum rise in systolic volume on exposure to low level loading; decreases of end diastolic and end systolic blood volumes; an elevation of EF lower than on the surface. With an increase in diving depth the functional reserves of the heart of exercising man are exhausted more rapidly.

[Method for determining the functional state of the human respiratory and circulatory systems in underwater conditions]. / Metodika opredeleniia funktsional'nogo sostoianiia sistem dykhaniia i krovoobrashcheniia cheloveka v podvodnykh usloviiakh.

An original device has been worked out which permits registering parameters of respiration, gas exchange and circulation in man during diving and performance of some tests under water (graduated exercise, respiration with changed gas mixture, etc.). The correction coefficients have been experimentally determined to calculate the gas exchange and cardiohemodynamics indices in underwater conditions. The indices of human work capacity under water are determined using the above device.

[Adaptive reactions in humans during repeated exposure to deep-water saturation immersion]. / Adaptivnye reaktsii u cheloveka pri mnogokratnom deistvii glubokovodnykh saturatsionnykh pogruzhenii.

Evaluation of changes in respiration circulation and respiratory gas transport has shown that long-term influence of hyperbaria gives rise to phase changes and promotes a shift to a new level of the functional state of aquanauts. It is established that the postdecompression syndrome is characterized by the lability of main parameters of breathing and circulation, depression of gas exchange, disorders of bronchial permeability, relaxation of the cardiac pump function, decrease of physical workability against the background of inhibition of the adrenal cortex and weakening of the non-specific immunoresistance. Examination of 145 deep divers has revealed regularities of readaptation dynamics and has permitted a conclusion on an increase of unfavourable tendencies in the ventilatory pulmonary function and cardiac pump function under repeated effect of saturated diving. The normative values of external respiration are worked out as applied to divers. Some new approaches to the technology of medical providing of deep divings and correction of non-specific professional pathology of acquanauts are physiologically substantiated proceeding from tendencies of shifts in the periods between divings and diving norms.

[Chinese hamster cells mutant at the hypoxanthine-guanine phosphoribosyltransferase (GPRT) locus. V. Complementation analysis of ts mutants]. / Issledovanie kletok kitaiskogo khomiachka, mutantnykh po lokusu gipoksantin-gunainfosforiboziltransferazy (GFRT). Soobshchenie V. Komplementatsionnyi analiz ts-mutantov.

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.

[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.

[Resistance of a line of Djungarian hamster cells to 6-mercaptopurine]. / Rezistentnaia k 6-merkaptopurinu liniia kletok dzhungarskogo khomiachka.

A cell line resistant to 6-mercaptopurine (6-MP) is isolated from Djungarian hamster embryonic fibroblasts transformed with SV-40, 6-MP resistance is due to the absence or complete inhibition of GGPRT activity. Initial and resistant cell cultures are similar in the growth rate and in the inoculation efficiency. Caryological analysis (differential chromosome staining--S-bands) revealed considerable caryotype rearrangements in both resistant and sensitive lines as compared with Djungarian hamster normal chromosome set, and also the appearance of specific chromosome markers.

[Characteristics of somatic cell hybrids (mouse X Chinese hamster) with different ratios of parental species chromosome sets. IV. Electrophoretic analysis of several enzymes of the dehydrogenase class]. / Kharakteristika gibridov somaticheskikh kletok (mysh' X kitaiskii khomiachok) s raznym sootnosheniem khromosomnykh naborov roditel'skikh vidov. Soobshchenie IV. Elektroforeticheskii analiz neskol'kikh fermentov klassa degidrogenaz

Electrophoretic mobilities in polyacrylamide gel of five dehydrogenases: NADP-dependent malate dehydrogenase (NADP-MDH), 6-phosphogluconate dehydrogenase (6PGD), alcohol dehydrogenase (ADH), glucose-6-phosphate dehydrogenase (G6PD) and glutamate dehydrogenase (GDH) were investigated in a series of mouse X Chinese hamster somatic cell hybrids. Seven hybrid lines with different ratio of chromosome sets of hamster and mouse: 1:1, 2:1, 3:1 and 1:2 respectively were studied. NADP-MDH and 6PGD of both parental species and intermediate hybrid bands were present in all hybrids except two lines. These lines had only hamster MDH due to the elimination of mouse chromosomes. A correlation was found between the gene dose and the intensity of the expression of the MDH bands. The mouse type ADH was detected in all hybrids. The hamster ADH was found in one of the hybrid lines that lost all mouse chromosomes during cultivation. It is suggested that hamster ADH activity was suppressed in hybrids by the mouse genome. The species origin of GDH and G6PD could not be established due to similarity of electrophoretic mobilities of respective enzymes in parental cells.

[Natural resistance of Drosophila melanogaster cells to 6-mercaptopurine and 8-azaguanine]. / O prirodnoi rezistentnosti kletok Drosophila melanogaster k 6-merkaptopurinu i 8-azaguaninu

The growth of cells and the activity of some enzymes in diploid embryonic cells of Drosophila and Mosquito which cultivated for a long time in the presence of 6-mercaptopurine and 8-azaguanine were studied. It is shown on the culture of Drosophila cells that a high level of the resistance to 6-mercaptopurine and 8-azaguanine correlates with the absence of hypoxanthine-guanine phyosphorybosyltransferase (HGPRT) in them. HGPRT activity was not also revealed in extracts obtained from flies of different lines, which draws to the conclusion on the natural resistance of Drosophila cells to hypoxanthine and quanine analogues. Similar resistance was found out in Mosquito cell lines Mos 20 A. The second enzyme of such a type, adenine phosphoribosyltransferase, is present in the cells of all investigated lines. This fact explaines the retention of the sensitivity to adenine analogues in these cells.

[Characteristics of somatic cell hybrids (mouse x Chinese hamster) with a different ratio of chromosome sets from the parent species. II. Thymidine kinase activity]. / Kharakteristika gibridov somaticheskikh kletok (mysh' x kitaiskii khomiachok) s raznym sootnosheniem khromosomynykh naborov roditel'skikh vidov. Soobshchenie II. Aktivnost'timidinkinazy

The activity of thymidine kinase (TK) was studied in series of somatic cell hybrids between the mouse cell line 3T3-4E (TK-) and Chinese hamster cells M-15-1 (HGPRT-). Four groups of hybrid lines with different ratio of parental chromosome sets have been investigated: 1) three lines containing one hamster and one mouse chromosome set (1 hs+1 ms); 2) one line with 2 hs+1 ms; 3) one line containing 3 hs+1 ms and 4) one line containing 1 hs+2 ms. Mixtures of extracts from the parental cells were shown to possess the expected TK activity. The calculation of the activity per cell revealed that the 1 hs+1 ms and 2 hs+1 ms hybrid lines possessed about 50% of the initial hamster cell TK activity. The decreased TK activity in these hybrids might be due either to a loss of hamster chromosomes or to some inhibitory effect of mouse genome in cells with the studied ratio of parental sets. The enzyme activity in the 3 hs+1 ms hybrid was as expected, about three times greater than that of hamster cells.

[Characteristics of somatic cell hybrids (mouse X Chinese hamster) with ratios of chromosome sets different from the parent species. IV. An electrophoretic analysis of several enzymes of the dehydrogenase class]. / Kharakteristika gibridov somaticheskikh kletok (mysh' x kitaiskii khomiachok) a raznym sootnoshe niem khromosomykh naborov roditel'skikh vidov. Soobshchenie. IV. Elektroforeticheski analiz neskol'kikh fermentov klassa degidrogenaz

Electrophoretic mobilities in polyacrylamide gel of five dehydrogenases: NADP-dependent malate dehydrogenase (NADP-MDH), 6-phosphogluconate dehydrogenase (6PGD), alcohol dehydrogenase (ADH), glucose-6-phosphate dehydrogenase (G6PD) and glutamate dehydrogenase (GDH) were investigated in a series of mouse X Chinese hamster somatic cell hybrids. Seven hybrid lines with different ratio of chromosome sets of hamster and mouse: 1 : 1, 2 : 1, 3 : 1 and 1 : 2 respectively were studied. NADP-MDH and 6PGD of both parental species and intermediate hybrid hands were present in all hybrids except two lines. These lines had only hamster MDH due to the elimination of mouse chromosomes. A correlation was found between the gene dose and the intensity of the expression of the MDH bands. The mouse type ADH was detected in all hybrids. The hamster ADH was found in one of the hybrid lines that lost all mouse chromosomes during cultivation. It is suggested that hamster ADH activity was suppressed in hybrids by the mouse genome. The species origin of GDH and G6PD could not be established due to similarity of electrophoretic mobilities of respective enzymes in parenteral cells.