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The results of large-scale radiation, genetic, cytogenetic, and molecular genetic studies on the nature and frequency of heritable mutations of two sex-linked and three autosomal genes of Drosophila melanogaster after exposure to 60Co γ-rays and 0.85 MeV neutrons are presented. Regularities were established for the studied genes and radiations in the induction of five different types of recessively inherited mutations, which can be combined into two main classes—the class of chromosomal mutations in one way or another affecting the gene under study (changes leading to sterility of F1 mutants, multilocus deletions, inversion or translocation breakpoint chromosome in the region of gene localization) and a class of "point" gene mutations with a complex spectrum of DNA changes detected by PCR and sequencing. In this report, the results of classical genetic and cytogenetic analysis of these classes of mutations are considered in detail and the frequency of their induction by γ-rays or neutrons is estimated per locus per dose unit (1 Gy). An important and unexpected result of the assessment was the fact that the frequency of "point" mutations turned out to be invariant (on average, 1.15 E-06/locus/Gy) for the studied genes and radiation, in contrast to chromosomal mutations, where a pronounced locus-specificity is observed for individual types of mutations. At the same time, neutrons are two or more times more effective than γ-rays in inducing this class of mutations. It is significant that the average frequency of "point" mutations induction correlates with the average cDNA length of these genes (1.62 kb), but not with their average size (6.07 kb), indicating that the target for "point" mutations is, obviously, not the entire DNA of the gene, but only the informational part of its exons. The dependence of the frequency of chromosomal mutations of one type or another on the position of the gene on the chromosome and in the three-dimensional space of the genome is discussed. [ABSTRACT FROM AUTHOR]

Wolbachia pipientis is an obligately intracellular bacterium infecting a number of arthropod and nematode species. At the body level, Wolbachia infection may cause parthenogenesis, feminization of genetic males, male killing, or cytoplasmic incompatibility; it may also be asymptomatic. Of special interest is DNA transfer from Wolbachia to the host insect genome, which was discovered recently. At the cellular level, the effects caused by Wolbachia have been studied more poorly. Only one of the known insect cell lines has been obtained from an insect species (the mosquito Aedes albopictus) infected by Wolbachia. In this study, a continuous cell line Dm2008Wb1 has been obtained from embryos of Drosophila melanogaster infected under natural conditions. Wolbachia both persists in a primary cell culture and is retained upon its transformation into a continuous culture. The presence of this bacterium in cells in a free form is evidenced by the fact that tetracycline treatment can cure the cells of Wolbachia and by successful transfer of Wolbachia to another cell line (S2), where it has not been detected before. [ABSTRACT FROM AUTHOR]

To understand specific symbiotic relationships ensuring stable existing of the bacterium Wolbachia in laboratory strains of Drosophila melanogaster, the imago lifespan and senescence rate, as well as competitiveness, have been evaluated as components of fitness in females from the following laboratory strains: (1) inbred strain 95 infected with Wolbachia; (2) two uninfected strains obtained by tetracycline treatment that were genetically similar to strain 95; and (3) two control, uninfected, wild-type laboratory strains that were used to assess the possible effects of the antibiotic on the studied characters in the absence of Wolbachia. The results have shown that infected females have longer lifespan and competitiveness than females with the same genotype uninfected with Wolbachia. The increase in the senescence and mortality rates with age was also slower in infected females. It is noteworthy that tetracycline does not affect the lifespan of females from the two control, uninfected, wild-type strains. Therefore, the antibiotic is not the cause of the positive changes in fitness that were observed in infected females. The obtained results are the first direct evidence that the relationships in the Wolbachia-D. melanogaster symbiotic system are mutualistic rather than parasitic, at least in micropopulations adapted to laboratory conditions. [ABSTRACT FROM AUTHOR]

The article discusses a study of interchromosomal gene conversion in early zygotic stage of diploid cleavage nucleus of Drosophila melanogaster. The study examines the molecular analysis of DNA heteroduplexes and the characteristics of molecular markers. The study also explores the gene conversion of diploid nucleus leading to reconstitution of homozygosity (ROH).