Transcription factor DREF regulates expression of the microRNA gene bantam in Drosophila melanogaster.

The bantam gene encodes a vital microRNA and has a complex expression pattern in various tissues at different stages of Drosophila development. This microRNA is involved in the control of normal development of the ocular and wing imaginal discs, the central nervous system, and also in maintaining the undifferentiated state of stem cells in the ovaries of adult females. At the cellular level, bantam stimulates cell proliferation and prevents apoptosis. The bantam gene is a target of several conserved signaling cascades, in particular, Hippo. At the moment, at least ten proteins are known to directly regulate the expression of this gene in different tissues of Drosophila. In this study, we found that the bantam regulatory region contains motifs characteristic of binding sites for DREF, a transcription factor that regulates the expression of Hippo cascade genes. Using transgenic lines containing a full-length bantam lethality-rescuing deletion fragment and a fragment with a disrupted DREF binding site, we show that these motifs are functionally significant because their disruption at the bantam locus reduces expression levels in the larvae and ovaries of homozygous flies, which correlates with reduced vitality and fertility. The effect of DREF binding to the promoter region of the bantam gene on its expression level suggests an additional level of complexity in the regulation of expression of this microRNA. A decrease in the number of eggs laid and a shortening of the reproductive period in females when the DREF binding site in the regulatory region of the bantam gene is disrupted suggests that, through bantam, DREF is also involved in the regulation of Drosophila oogenesis.

Different Protein Groups Involved in Transcription Regulation in Development and Housekeeping Genes in Drosophila.

Antibodies to histone modifications and an insulator protein involved in the processes of transcription initiation and elongation are mapped in Drosophila polytene chromosomes. The CHRIZ protein (chromatin insulator) and H3K36me3 histone modification (RNA elongation) are detected only in the localization of housekeeping genes (interbands and gray bands of polytene chromosomes) and never in the regions of developmental genes (black bands and large puffs arising from them). Antibodies to H3S10P histone modification, which is associated with the initial elongation of the RNA strand during transcription, are found exclusively in small puffs, but not in housekeeping gene localization sites or large ecdysone-induced puffs, where housekeeping genes are localized. Antibodies to H4R3me2 histone modification (a co-repressor of the ecdysone receptor) are detected only in large ecdysone-induced puffs.

[MicroRNA Expression Profiling of Diffuse Large B-Cell Lymphoma].

Non-Hodgkin lymphoma (NHL) is a heterogeneous group of cancers that differ in pathogenesis and prognosis. The main methods of treating NHL include chemotherapy, immunochemotherapy, and radiation therapy. However, a significant proportion of these tumors are chemoresistant or rapidly recur after a short chemotherapy-induced remission. In this regard, the search for alternative cytoreductive therapeutic methods is relevant. Aberrant expression of microRNA (miRNA) is one of the mechanisms responsible for the emergence and progression of malignant lymphoid neoplasms. We analyzed the profile of miRNA expression in the biopsy material from lymph nodes affected by diffuse large B-cell lymphoma (DLBCL). The key material of the study was histological preparations of lymph nodes obtained by excisional diagnostic biopsy and treated using conventional histomorphological formalin fixation methods. The study group consisted of patients with DLBCL (n = 52); the control group consisted of patients with reactive lymphadenopathy (RL) (n = 40). It was shown that the miR-150 expression level in DLBCL was reduced by more than 12 times (p = 3.6 x 10^(-15)) compared with RL. Bioinformatics analysis revealed the involvement of miR-150 in the regulation of hematopoiesis and lymphopoiesis. The data we obtained allow us to consider miR-150 as a promising therapeutic target with great potential in clinical practice.

CHARACTERISTIC OF THE CHROMATIN TYPE CORRESPONDING TO THIN «GREY¼ BANDS IN POLYTHENE CHROMOSOMES OF DROSOPHILA MELANOGASTER.

Recently, we developed a bioinformatic algorithm dividing drosophila genome into 4 types of chromatin which differ in protein composition. This allows us to propose a model of structural and functional organization of interphase chromosomes which postulates an existence of correlation between the chromatin types and morphological structures of polytene chromosomes. So, constantly and everywhere open chromatin type named «aquamarine¼ is characteristic of interbands, while the combinations of the other three types («lazurite¼, «malachite¼ and «ruby¼) form the bands. In this study, we characterized protein composition, genetic organization and morphological features of 39 «lazurite¼-chromatin regions in polytene chromosomes. We found out that «lazurite¼-chromatin usually form thin «grey¼ bands and more rarely ­ boundary portions of large bands. This type of chromatin contains coding parts and 3R-ends of genes and is enriched with proteins and histone modifications associated with active transcription at the stage of elongation. The expression patterns of these genes differ greatly depending on the type of chromatin in their 5R-regions.

[Patterns of transposable elements distribution on the Drosophila melanogaster polytene chromosomes before and after selection for a quantitative trait].

The effect of selection for radius vein length on the distribution of hybridization sites of the P and hobo transposons and the mdgl and mdg2 retrotransposons on polytene chromosomes of Drosophila melanogaster salivary glands was studied. The patterns of these transposable elements (TEs) distribution were polymorphic in both the parental strain and selected strains. The similarity in mdg1 and mdg2 patterns between strains selected in one direction was closer than between strains selected in opposite directions, but the selected strains were closer to each other than to the parental strain regardless of selection direction. No mdg2 hybridization sites that would be absent in the control were found in the selected strains. There were more mdg2 and hobo hybridization sites in the strains selected in the (+) direction than in the (-) direction. The mobility of hobo copies in the strains studied correlated with the presence of its full-sized copy in the genome. The polymorphism of all TEs studied except for mdgl was greater for strains selected in the (+) direction that in the (-) direction. These facts suggest that some TEs migrate over the genome independently of selection, and others are markers of evolutionary events rather than their causes.

[The response of the genomic pattern of transposable elements TE412 to quantitative trait selection in Drosophila melanogaster].

The results of four selection-genetic experiments aimed at the genetic transformation of the quantitative trait controlled by the radius incompletus gene of Drosophila melanogaster are given. Directional (s+) and (s-)-selection was conducted. At the of end all the experiments, in (s+)-selection the radial vein of the wing was restored to the wild phenotype, in (s-)-selection complete elimination of the radial vein took place. In four variants of selection, different TE412 pattern was formed under (s+)-selection and (s-)-selection in final generations. Correlation coefficient between (s+)-selection and (s-)-selection is -0.576, p < 0.001. At the same time, correlation coefficient between two independent replications of (s+)-selection is 0.912, p < 0.001, and of (s-)-selection, 0.946, p < 0.001. Thus, the availability of associated response to the selection of a quantitative trait and to the TE412 pattern is experimentally proved. Three hypotheses of the possible TE behaviour under selection are discussed.

[Induction of MGE 412 transposition in an isogenic strain of Drosophila melanogaster by different doses of ethanol fumes]. / Induktsiia transpozitsii MGE 412 razlichnymi dozami parov étanola v izogennoi linii Drosophila melanogaster.

The effect of treatment of males from an isogenic Drosophila melanogaster strain by limiting doses of ethanol fumes on transpositions of MGE 412 was examined. Validity of the phenomenon of transposition induction was demonstrated. We estimated rates of induced transposition (approximately 10(-2) events per site, per sperm, per generation versus < 10(-3) in control) and showed dose dependence of the rate on the exposure time of the males to ethanol fumes. Experiments with alcohol treatment at limiting doses must end either in death of the individuals or bursts of genetic variability in their progeny. In terms of genetics of an individual, this may mean loss of vital hereditary basis followed by mass degradation of the progeny of the "hard drinkers." In terms of populations genetics, this mode of MGE transposition induction can rapidly create a burst of novel genetic variation, which, apart of great losses, may generate a number of advantageous individuals, i.e., be significant for population survival in new, stressful environments.

[Induction of MGE 412 transposition individually by heat and cold shock in spermatogenesis in Drosophila males]. / Induktsiia transpozitsii MGE 412 razdel'no teplovym i kholodovym shokom v spermatogeneze u samtsov drozofily.

Effects of temperature treatment (heavy heat shock, HHS; heat shock, HS; and cold shock, CS) on the daily productivity of treated males in different spermatogenesis stages have been studied in isogenic line 51 of Drosophila melanogaster. The average productivity was shown to substantially decrease in all cases. The sum of the HS and CS contributions to this decrease was nearly equal to the HHS (the combined HS and CS) contribution, i.e., these contributions were almost additive. The temperature treatments did not kill mature sperm. In the control, mating productivity of day 1 exceeded that of the next day at least by 10-20%. Each day, most sperm in matings was new, i.e., matured during that day. Transposition induction of MGE 412 was studied at four spermatogenesis stages after HS and CS. Both temperature treatments were effective but CS had a more pronounced inducing effect. Most temperature-induced transpositions occurred at stage 3 (meiosis) and 4 (spermiogenesis). The day rates of transpositions at different stages were estimated. After HS at the meiosis stage, lambda = 0.11 events per initial MGE copy per sperm per day of mating, which is approximately equal to the previous estimates after HHS. After CS at the meiosis stage, lambda = 0.51. The transposition hot sites (including the previously known 43B and 97DE as well as a number of new sites) were detected. The lists of transpositions after CS completely included the corresponding lists after HS, which suggests similarity of induction mechanisms underlying CS and HS.

[Response of the MGE 412 pattern to truncation selection of a quantitative trait in an isogenic line of drosophila after severe heat shock (SHS)]. / Otklik patterna MGE 412 na otsekaiushchii otbor kolichestvennogo priznaka v izogennoi linii drozofil posle tiazhelogo teplovogo shoka (TTSh).

Positive and negative selection on the total length of two fragments of an interrupted longitudinal wing vein in an isogenic line of Drosophila melanogaster was accompanied by changes in the genomic localization pattern of MGE 412. Strong truncation selection was conducted in the population of effective size Ne = 160 for 50 generations. Twenty-six out of 35 polymorphic HHS-induced segments of MGE localization behaved as independent copies and markers, whereas 9 segments proved to be selective. The second group included "hot" segments of HHS transposition induction (43B, 97E, etc.). Thus, final consensus patterns of induced MGE transpositions have a random and an adaptive component in generation 50 of positive and negative selection. Selective patterns probably include modifier MGEs, which generate induced genetic regulatory variation of polygenes controlling the selected quantitative trait in the isogenic line after HHS.