[A comparative genetic analysis of the role of the brain dopaminergic systems in the regulation of behavioral elements in the "open field" test in DBA/2J and C57BL/6J mice]. / Sravnitel'no-geneticheskii analiz roli dofaminergicheskikh sistem mozga v kontrole élementov povedeniia v teste "otkrytoe pole" u myshei DBA/2J i C57BL/6J.

The effects of intraperitoneal injections of sulpiride (10 mg/kg), bromocriptine (5 mg/kg), and alaptide (1 mg/kg) on the behavior of male C57BL/6J (C57BL) and DBA/2J (DBA) mice in the open-field test were studied. In this test, C57BL mice exhibited a significantly higher horizontal locomotor activity than DBA mice, whereas DBA mice moved in place substantially longer than C57BL mice. Dopaminergic agents had different effects on the open-field behavior in different mouse strains. Alaptide increased horizontal locomotor activity in DBA, but not in C57BL mice; all the three agents decreased the duration of movement in place in DBA but not in C57BL mice; bromocriptine suppressed vertical locomotor activity and the act of looking into holes in C57BL but not in DBA mice. Thus, interstrain differences in dopaminergic functions were demonstrated. The revealed strain-specific characteristics largely contribute to the determination of open-field behavior in the studied mouse strains.

[Genetic recombination and steroid metabolism in Drosophila]. / Geneticheskaia rekombinatsiia i steroidnyi metabolizm u Drozofily.

A double-species ecologo-genetical model, including Drosophila and yeast, has been used as a new methodological instrument for investigation of the physiological mechanism of recombination. Incubation of Drosophila females in the medium containing yeast of the strain mutant for ergosterol synthesis leads to suppression of temperature-induced crossing over. The mass-spectrum analysis of steroid fraction from Drosophila females has shown that incubation of the yeast medium without ergosterol results in arrest of ecdysterone synthesis. These data are explained by the absence of ecdysterone synthesis precursor in the fly organism. The endocrinal control of crossing over is discussed in the light of hormonal regulation of meiosis.

[The effect of sterol metabolism in a model ecological system Drosophila-yeasts on the crossing-over in Drosophila]. / Vliianie sterinovogo metabolizma v model'noi ékologicheskoi sisteme drozofila-drozhzhi na krossingover u drozofily.

The absence of sterols available for metabolism causes the death of Drosophila larva. Addition of suboptimal cholesterol doses to this medium allows the portion of larvae to survive. Sterol-deficient diet at the preimaginal stages leads to suppression of both spontaneous and high-temperature induced crossingover in Drosophila females. Two possible explanations for dependence of recombination process on sterol metabolism are suggested: 1) the shortage of precursor for ecdisons biosynthesis was the cause of discordance of meiotic events; 2) suppression of crossingover occurs, due to alteration of cell membrans' structure.

[Effect on the fertility of female Drosophila of sterol metabolism in an ecological-genetic yeast-Drosophila system]. / Vliianie na plodovitost' samok drozofily metabolizma sterinov v ékologo-geneticheskoi sisteme drozhzhi--drozofila.

The consequences of sterol deficiency in feeding of adult Drosophila females have been studied. Feeding of Drosophila on nys 1 mutant strain yeast leads to significant increase of non-developed eggs in Drosophila females. The effect of sterol deficiency on oogenesis in virgin and fertilized females has been estimated using different regimens of feeding. Possible mechanisms of arising of fertility defects are discussed.

[Effect of sterol metabolism in the yeast-Drosophila system on the frequency of radiation-induced aneuploidy in Drosophila melanogaster oocytes]. / Vliianie metabolizma sterinov v sisteme drozhzhi-drozofila na chastotu radiatsionno-indutsirovannoi aneuploidii v ootsitakh Drosophila melanogaster.

The influence of sterol metabolism upon mutagenesis in Drosophila melanogaster was investigated using ecological-genetic yeast - drosophila system. Sterol deficiency in the organism of Drosophila was caused by using the strain of Saccharomyces cerevisiae 9-2P712 with a mutation in the nysr1 locus which blocks synthesis of ergosterol as a nutrition substrate for flies. It was concluded that maintenance of females on the mutant yeast strain causes an increase of radiation-induced X-chromosome loss in mature oocytes. Resistance of oocytes to X-ray irradiation is restored, reaching the control level, when 0,1% cholesterol solution in 10% ethanol is added to the yeast biomass. The possible membrane and hormonal mechanisms of elevation of induced aneuploidy and the role of sterol metabolism in ensuring resistance of insects to damaging factors are discussed.