[The puzzle of Wolbachia spreading out through natural populations of Drosophila melanogaster].

The endosymbiotic bacteria Wolbachia are widely spread in natural populations of arthropods all over the world. This phenomenon, according to the current views, may be due either to so called reproductive parasitism (modification of sexual reproduction) or to mutualistic interrelationships with the host organism, since the bacteria are transmitted transovarially. Wolbachia are extremely widespread in natural populations and laboratory lineages of Drosophila melanogaster though they do not cause any known modifications of this insect sexual reproduction that could influence the bacteria frequency in the populations. It is found out that Wolbachia effects on drosophila reproductive processes can only consist in low-level of cytoplasmic incompatibility within laboratory lineages; in natural drosophila populations even such an effect has not been detected. The attempts to explain the wide spread of Wolbachia among representatives of D. melanogaster through fitness increasing of infected individuals were not successful either. Data obtained thereupon are contradictive and the results are not versatile. Meanwhile, there are some incomplete data on the bacteria affecting drosophila sexual behavior, expression of certain genes, ferrum metabolism. It is shown that the bacteria enhance individual resistance to RNA-viruses that, under natural conditions, infect fruit flies rather frequently, but the mechanisms of the phenomenon remain uncertain as well as the commonness of the phenomenon itself. Thus, at the one hand, it can be stated that infection by Wolbachia leads to a rather complex effect on D. melanogaster while, at the other hand, the reasons behind the wide spread of Wolbachia in natural populations of D. melanogaster still remain unclear.

[Symbiotic bacteria, which modify reproduction processes of Drosophila melanogaster].

Cytoplasmic bacteria-symbionts are actively investigated all over the world for the last ten years. The scale of their spreading in natural and laboratory populations of invertebrates, especially arthropods, is impressing scientists' imagination. Ways of their intraspecific and interspecific transmission are various. The nature and mechanisms of their interaction both between themselves and with their hosts are extremely diverse. Cytoplasmic incompatibility, parthenogenesis, male-killing, feminization, tissue degeneration and others are those phenotypic effects, which intracellular bacteria can cause in their hosts. Moreover, the same bacterium can have diverse influences on different hosts. So it is possible to talk about many-sidedness of endosymbiont interaction with a host, which is determined both by bacterium and host biology. However, majority of phenotypic effects is directed to the successful colonization of hosts' populations by increasing the number of infected females. Alas, the mechanisms of interaction are still not enough investigated. Besides, intracellular bacteria-symbionts can be one of the factors of the so-called "infectious species formation". In any investigation, model organisms, Drosophila melanogaster belonging to them, take a special place. Among drosophila's endosymbionts, only bacteria from genera Wolbachia, Spiroplasma and Cardinium were broadly investigated: their spreading in Drosophila melanogaster populations all over the world, the infecting level and those phenotypic effects, which they can cause. So this review is dedicated to analysis of these studies.

[Infection with Wolbachia does not influence crossing over in Drosophila melanogaster].

The influence of infection with endosymbiotic bacteria Wolbachia on crossingover in Drosophila melanogaster between the white and cut genes in the X chromosome was studied. Reciprocal crosses have been conducted between infected and non-infected fruit fly strains. The results showed no significant effect of Wolbachia infection on the crossingover rates in D. melanogaster between the white and cut genes in X-chromosome.

[The dynamics of P-mobile Drosophila melanogaster element activation in controlled terms of protracted irradiation].

Verification of hypothesis about mobile element activation radiosensitivity change in the conditions of the prolonged irradiation was the research goal. The estimation of orientation of these changes depending on the accumulated dose and their characteristic times were conducted. Two Drosophila melanogaster strains (Canton-S and P-lines) for 20 generations were in the controlled terms of chronic irradiation with 3-dose rate (1.2 x 10(-8), 0.6 x 10(-8) and 0.12 x 10(-8) Gy/c). The dynamics of hybrid dysgenese frequency was explored for each generation of F1 descendants from Canton-S and P-lines crossing. The gradual change of dose response of hybrid disgenesis depending on duration of irradiation of ancestors and dose rate was shown. The complex dynamics of hybrid dysgenese frequency depending on irradiation duration of ancestors and dose rate was shown. The cumulative effect of the prolonged irradiation shows up as adaptation at the lowest dose rate and as exhaustion at the highest dose rate. Question comes into discussion about the features of transitional process and including of protective and adaptive reactions hierarchy at the conditions of radiation factor chronic action.

[Mutation processes in the natural populations of Drosophila and Hirundo rustica from Ukrainian radiation contaminated territories].

Natural populations of Drosophila melanogaster and Hirundo rustica that reside at the territories with different levels of radioactive pollution were investigated. The levels of visible mutations, sex-linked mutations and gonad reduction of Drosophila and the rate of interphase markers of chromosomal instability in erythrocytes of birds were selected as parameters for population monitoring. The results point out to possible reverse dependence among the level of chromosomal instability of birds, the rate of lethal mutations in sex chromosome of Drosophila and the density of radioactive pollution.

[Novel miniature-like m42 mutant of Drosophila virilis. Unusual microstructure of wing fibres]. / Novyi miniature-podobnyi mutant m42 u Drosophila virilis. Neobychnaia mikrostruktura zhilok kryla.

Distinctive defects of cuticular wing vein microstructure in Drosophila virilis miniature-like m42 allele and the possible role of m42 locus in cytoskeleton reorganization during of wing morphogenesis are discussed.

[Genetic characteristics of the wing mutation Odd(22) and its interaction with alleles of the Delta locus in Drosophila virilis]. / Geneticheskaia kharakteristika krylovoi mutatsii Odd(22) i ee vzaimodeistvii s alleliami lokusa Delta u Drosophila virilis.

The dominant sex-linked semilethal mutation Odd22 was isolated from progeny of a dysgenic cross of Drosophila virilis lines. Flies homozygous, heterozygous, and hemizygous for Odd22 displayed multiple wing defects, including enlargements and gaps on the veins; irregularly thickened, branched, shortened, or completely reduced veins; and cuts on the wing margin. The most remarkable feature of the Odd22 expression was a combination of both an increase and a reduction of the wing vein material simultaneously present in the same wing, which is commonly associated with suppression and hyperfunction, respectively, of genes of the Notch (N) signaling system. Phenotypic analysis revealed the interaction of Odd22 with alleles of the Delta (Dl) locus, which codes for the ligand of the NOTCH receptor. Based on these data, Odd22 was assumed to directly or indirectly affect the activity of the genes involved in Dl-N signaling.