[Dosage compensation in drosophila: sequence-specific initiation and sequence-independent spreading of MSL complex to the active genes on the male X chromosome]

For the dosage compensation to occur, genes on the single male X chromosomes in Drosophila must be selectively bound and acetylated by the ribonucleoprotein complex called MSL complex. It remained unknown how such exquisite specificity is achieved, and whether specific DNA sequences were involved. In the present work we demonstrate that it is transcription of the gene on the X chromosome that is important for MSL targeting, irrespective of gene origin and DNA sequence.

[Cause for maintaining high instability at the yellow gene in Drosophila melanogaster lines, isolated during the "mode for mutation" period in Uman populations]

Mobile genetic elements are responsible for most spontaneous mutations in Drosophila melenogaster. The discovered in the 1980s phenomenon of frequent change of the wild-type yellow phenotype for a mutant one, and vice-versa, in strains of Drosophila melanogaster isolated from the Uman' natural population can be, according to our data, explained by repeated inversions and reinversions of the gene regulatory region located between the two copies of the hobo transport. However, most molecular genetic events accompanying the process can occur without the phenotype change. After several generations, the strains, remaining phenotypically unchanged, can possess different molecular genetic properties with respect to yellow. Using genetically homogenous or isogenic strains for the genetic analysis or for production of the new plant cultivars or animal breeds, geneticists and breeders often face the problem of stability of the strains. In the present study, the mechanism underlying the generation of instability at the yellow locus of D. melanogaster determined by the hobo-induced genome instability is described.

[Some aspects of developing reflux esophagitis in patients with hiatal hernias]

An examination of 60 patients with gastro-esophageal reflux has shown that a continuous contact of the gastric mucosa with the gastric contents and retarded evacuation from the stomach are considered to be the principal factors in the development of reflux-esophagitis.

[Use of systems approach to solving regional problems of renewal of the stock of ultrasound scanners (the case of the Smolensk Region)]

The Smolensk Region (Russian Federation) was used to assess how ultrasound diagnosis is made in the therapeutical and prophylactic institutions. Requirements for the diagnosis are worded in terms of regional, organizational, and other features. At the same time the paper gives main criteria for assessing the obsolescence of equipment; data on the level of organization of service; a share of brands of equipment; and characteristics of manufacturers in the ultrasound equipment market of the Smolensk Region.

[Use of constant electric current in prevention of postoperative bronchopulmonary complications in patients with hiatal hernia]

The prophylactics of bronchopulmonary complications was performed by the authors original method of intrapulmonary electrophoresis. It was shown to be effective and allowed the amount of postoperative bronchitis and pneumonia to be reduced from 15-20% to 4.4%.

[Choice of the method of plasty in hiatal hernia]

Results of operative treatment of patients with esophageal hernias of the diaphragm can be substantially improved in cases of differential approach to choice of the plasty method. Choice of the method of plasty depends on the hernia type, topographic-anatomical structure of the esophageal opening of the diaphragm, concomitant diseases and age of the patient. Preference should be given to methods of non-complete fundoplication performed from the transabdominal access.

[Microcloning and characteristics of DNA from regions of the centromeric heterochromatin of Drosophila melanogaster polytene chromosomes]

A method of microcloning, which involves microsurgical excision of chromosome fragments, DNA amplification by means of a polymerase chain reaction (PCR), and ligation of amplified products with plasmids, was employed in studying Drosophila polytene chromosomes for the first time. Clones of the DNA library thus obtained contained inserts varying in size from 0.1 to 0.5 kb. DNA sequencing of five clones of the library showed that pericentromeric heterochromatin contained the 17.6 and 297 retrotransposons, the ninja retrotransposon characteristic of D. simulans, and two Drosophila repetitive elements, a8 and a12, the function of which remains unknown.

[The conduction of combined operations for pulmonary cancer]

The supraexpanded (combined) operation was conducted in 36 patients for pulmonary cancer. The conduction of such operations is indicated in spite of their significant postoperative complications occurrence and high postoperative mortality (22.2%) because it permits to improve a grade II pulmonary cancer result of treatment.

[A genetic factor, suppressing DNA underreplication in Drosophila melanogaster polytene chromosomes]

The Drosophila melanogaster line carrying the In(I)scv2 was found to exhibit unique cytological phenotype distinguished by the lack of "weak" points in the intercalary heterochromatin of the salivary gland polytene chromosomes, the absence of ectopic contacts between the chromosome regions, and the occurrence of additional intercalary heterochromatin in the centromeric regions. Southern blot hybridization revealed the absence of DNA underreplication in the intercalary heterochromatin region 39E carrying the histone gene cluster. This phenotype may have arisen under the influence of a genetic factor, Su(UR), which suppressed DNA underreplication in polytene chromosomes. Genetic analysis of the inheritance of the "suppression of DNA underreplication" phenotype showed that this factor was located in the third chromosome and was expressed in a semidominant manner. Discovery of Su(UR) suggested existence of common mechanisms regulating DNA underreplication in the centromeric and intercalary heterochromatin regions containing genes that were completely inactivated during ontogeny. These results confirm the assumption of common mechanisms of epigenetic repression of highly repetitive, somewhat repetitive, and unique sequences of the Drosophila genome.