[Qualitative and quantitative analyses of the transpositions of P element--based genetic construction into the region of Drosophila melanogaster hsp70 genes].

The hsp70 genes is among the main systems underlying the adaptation of organisms to adverse environmental factors. The ever increasing amount of data in literature demonstrates an important adaptive role of mobile genetic elements in microevolution. Drosophila hsp70 genes are potential target for transpositions of various mobile elements in natural populations. We have analyzed the frequency and localization of a P element-based genetic construction, EPgy2, in the region of Drosophila melanogaster hsp70 genes. A hot spot for the transposition was discovered in the promoter regions of genes hsp70Aa and hsp70Ab. No insertions of this construction in the coding or 3'-flanking regions of hsp70 genes have been recorded. It was demonstrated that the region of 161 to 7800 bp adjacent to the original construction is in certain cases also involved in the transposition. No transpositions of any other mobile elements have been observed. The inserts were shown to change the activity of hsp70 genes and the thermotolerance of transgenic strains.

[Fertility of Drosophila melanogaster females affected by mutation l(2)M167DTS].

We studied the fertility of D. melanogaster females heterozygous for the dominant temperature sensitive mutation l(2)M167DTS, which exerts a recessive lethal effect at 25 degrees C, under the conditions of stable temperature regimes 25, 28, and 29 degrees C and changing regimes 25-->29 degrees C and 29-->25 degrees C. It was shown that inhibition of total activity of oogenesis due to a decreased number of functioning ovarioles is one of the mechanisms underlying the decreased fertility of l(2)M167DTS /+ females. Analysis of individual fertility of each female confirmed also the role of sterility as a component of fertility of the females. Sterilization was realized due both to full depletion of functioning ovarioles and disturbed mechanism of laying the mature eggs onto a substrate as a result of violation of the feedback blocking normal ovulation, which led to the breakdown of ovarioles and filling of the abdominal cavity with mature oocytes. A significant polymorphism of heterozygous females by their fertility was observed. The intensity of sterilization and mortality of l(2)M167DTS/+ females sharply increased at an elevated temperature (29 degrees C), especially at the pupal stage.

[An electron microscopic analysis of the structure of the indirect flight musculature in heterozygotes for a new Mhc gene mutation of Drosophila melanogaster]. / Elektronno-mikroskopicheskii analiz stroeniia nepriamoi letatel'noi muskulatury u geterozigot po novoi mutatsii gena Mhc u Drosophila melanogaster.

The ultrastructure of indirect flight muscle was studied in flies (imago) heterozygous for a new allele of the gene of heavy myosin chain. Analysis of the observed defects of myofibrils suggests that in the mutants completion of differentiation of the flight muscle is disturbed.

[An electron microscopic study of the structure of the indirect flight musculature at the pupal stage in the muscle mutant of Drosophila melanogaster]. / Elektronno-mikroskopicheskoe issledovanie struktury nepriamoi letatel'noi muskulatury na stadii kukolki u myshechnogo mutanta Drosophila melanogaster.

Ultrastructure of indirect flight muscles was analyzed in Drosophila pupae heterozygous for the mutation l(2)MhcM66, which is an allele of the locus Mhc (Myosin heavy chain). It is demonstrated that the initial stages of muscle fiber differentiation in mutants proceed normally. First visible changes (elimination of individual thick protofibrils) are observed when myofibrils attain a certain size. Disintegration of the contractile apparatus progresses with growth of myofibrils. Mechanisms responsible for onset and development of these destructive processes during ontogeny are discussed.

[The effect of the dominant heat-sensitive mutation l(2)M167(DTS) on the fitness of Drosophila melanogaster heterozygotes at preimaginal stages]. / Vliianie dominantnoi teplochuvstvitel'noi mutatsii l(2)M167(DTS) na prisposoblennost' geterozigot Drosophila melanogaster na prdimaginal'nykh stadiiakh.

Relative viability of Drosophila melanogaster flies heterozygous for the lethal autosomal temperature-sensitive mutation l(2) M167DTS was studied under permissive conditions. The effect of environmental and genotypic factors on segregation was examined in progeny of reciprocal crosses between the lines l(2)M167DTS SM1 and D-32 (wild type). Comparisons of mass and individual crosses and tests for homogeneity of families and in individual cultures within the total sample imply existence of a complex system of modifiers influenced by culture density and direction of crossing. Correlation analysis of the relationship between larval density and segregation in progeny suggests a threshold level of viability at high density. This causes differences in the composition of progeny of the same parents in mass and individual cultures. These results agree well with the hypothesis on the relationship of population genetic structure and population density.

[The characteristics of the expression of temperature-dependent dominant lethal mutations in Drosophila melanogaster]. / Nekotorye osobennosti ékspressii temperaturozavisimykh dominantnykh letal'nykh mutatsii u Drosophila melanogaster.

The results of a series of investigations on obtaining and analysing dominant temperature-sensitive lethals (DTS-lethals) are summarized. Using EMS, both cold- and heat sensitive mutations of this type were induced in large autosomes. The cold-sensitive mutations of chromosome 3 were revealed for the first time. The effect of genetic phone on DTS lethal penetrance and expressivity was studied. The character of expression of two mutations possessing a pleiotropic action was examined. The heat-sensitive 1(2)M90DTS mutation disturbed the structure of abdominal tergites in all imago and, besides, caused an abrupt decrease in the female reproductive period. The pattern of alterations observed in oogenesis along with the result of phenogenetic analysis suggest that this gene takes part in the genetic control over the proliferation of stem oogonial cells. The cold-sensitive 1(2)M66DCS mutation caused a number of disturbances in imago thoracic structures: inability to flight, raised up wings, extremity fracture, etc. Mutant flies showed serious disorders of indirect flight muscles both at morphological and at ultrastructural levels. It was established that this mutation was a cold-sensitive allele of Mhc gene which controls the synthesis of myosine heavy chains in drosophila.

[Determination of the lethal phase in homo- and heterozygotes for a dominant lethal cold-sensitive mutation of Drosophila melanogaster at permissive temperature]. / Opredelenie letal'noi fazy u gomo- i geterozigot po dominantnoi letal'noi kholodochuvstvitel'noi mutatsii Drosophila melanogaster pri permessivnoi temperature.

The lethal phase in homo- and heterozygotes for dominant cold-sensitive lethal mutation 1(2)M66DCS at permissive temperature (25 degrees C) was determined. The effective lethal phase was only revealed for homozygotes. 100% of them died during the first larval instar. In heterozygotes the mutation under study proved to be aphasic semi-lethal with 31.9% penetrance. It was localized on the left arm of chromosome 2, in position 51.2. The penetrance of some other phenotypes caused in heterozygotes at 25 degrees C was also studied.

[Temperature-sensitive autosomal dominant lethal mutations in Drosophila melanogaster induced by ethylmethane sulfonate]. / Temperaturochuvstvitel'nye autosomnye dominantnye letal'nye mutatsii u Drosophila melanogaster, indutsirovannye étilmetansul'fonatom.

Cold- and heat-sensitive dominant autosome and recessive sex-linked lethals were scored using C(1)RM, y; vg bw; e ss tester stock. The frequencies of heat-sensitive mutations were 1.43, 0.30, 0.07% and of cold-sensitive ones were 0.39, 0.16 and 0.09% in the 1-st, 2-nd and 3-rd chromosomes, respectively. For the first time, dominant cold-sensitive lethals were obtained in chromosome 3. The data from genetic analysis point to the fact that penetrance of such mutations strongly depends on the genetic background. That may be the reason, why they were not obtained using some of the balancer-3 chromosomes. Also, "cryptic" dominant autosome mutants were found which were not conditional but only revealed in the F2 generation. Their possible origin as gonado-somatic mosaics is discussed.

[Mitotic recombination in cleavage divisions of Drosophila melanogaster. IV. Effect induced by radiation in female parents]. / Mitoticheskaia rekombinatsiia v deleniiakh drobleniia Drosophila melanogaster. Soobshchenie IV. Effekt, vyzvannyi oblucheniem samok-roditel'nits.

The premutational changes induced by X-irradiation (3 kr or 1 kr) in X-chromosomes of female gametes gave rise to mitotic recombination between irradiated female X-chromosomes and non-irradiated male X-chromosomes in early cleavage nuclei of F1 daughters. Most of the recombinants were non-mosaic females. It can be concluded from the analysis of their phenotypes as well as their offsprings that all nuclei of somatic and germinal tissues of these females were descendants of one from the four first cleavage nuclei (the recombinant one). There were differences in rates and in patterns of recombination between experiments with different stocks. The recombination induced by treatment of female parents usually occurred in the proximal part of X-chromosomes.

[Mitotic recombination in cleavage divisions of Drosophila melanogaster. V. Effect of ethylmethane sulfonate on female parents]. / Mitoticheskaia rekombinatsiia v deleniiakh drobleniia Drosophilia melanogaster. Soobshchenie V. Deistvie étilmetansul'fonata na samok-roditel'nits.

The data obtained show that after ethylmethanesulfonate treatment of Drosophila females and their crossing with untreated males the mitotic recombinants can be found among F1 offsprings. The recombination took place in cleavage division nuclei between treated female and intact male X-chromosomes. The rates of recombinations were lower than those caused by treatment of males with the same doses of EMS. The patterns of recombination were similar in both cases. Most of the recombinants were mosaic females. The results of present study as well as data obtained in previous experiments suggest that distribution of breaks along X-chromosome depends on sex of the treated gametes and does not depend on the mutagen used. In heterozygotes carrying treated mother's X-chromosome the recombination usually occurs in the proximal part of X-chromosome while the treatment of male parents frequently causes the recombination in the distal region of X-chromosomes of their daughters.