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N N Kolesnikov

Publications and source records attributed to N N Kolesnikov.

14 recordsLinked to original sources
PubMed2002

Magnetic resonant mode in the single-layer high-temperature superconductor Tl2Ba2CuO(6+delta).

An unusual spin excitation mode observed by neutron scattering has inspired numerous theoretical studies of the interplay between charged quasiparticles and collective spin excitations in the copper oxide high-temperature superconductors. The mode has, thus far, only been observed in materials with crystal structures consisting of copper oxide bilayers, and it is absent in the single-layer compound La(2-x)Sr(x)CuO(4+delta). Neutron-scattering data now show that the mode is present in Tl(2)Ba(2)CuO(6+delta), a single-layer compound with a superconducting transition temperature of approximately 90 kelvin, demonstrating that it is a generic feature of the copper oxide superconductors, independent of the layer sequence. This restricts the theoretical models for the origin of the resonant mode and its role in the mechanism of high-temperature superconductivity.

Journal Article↗
PubMed2001

Characterization of the genomic Xist locus in rodents reveals conservation of overall gene structure and tandem repeats but rapid evolution of unique sequence.

The Xist locus plays a central role in the regulation of X chromosome inactivation in mammals, although its exact mode of action remains to be elucidated. Evolutionary studies are important in identifying conserved genomic regions and defining their possible function. Here we report cloning, sequence analysis, and detailed characterization of the Xist gene from four closely related species of common vole (field mouse), Microtus arvalis. Our analysis reveals that there is overall conservation of Xist gene structure both between different vole species and relative to mouse and human Xist/XIST. Within transcribed sequence, there is significant conservation over five short regions of unique sequence and also over Xist-specific tandem repeats. The majority of unique sequences, however, are evolving at an unexpectedly high rate. This is also evident from analysis of flanking sequences, which reveals a very high rate of rearrangement and invasion of dispersed repeats. We discuss these results in the context of Xist gene function and evolution.

3' Untranslated Regions↗
PubMed1991

MEC: a transposable element from Chironomus thummi (diptera).

Two genomic clones, pC1.2 and p20D (containing inserts of 2.0 and 1.6 kb, respectively) were isolated from the A2b region to polytene chromosome IV of Chironomus thummi thummi salivary gland cells. Upon in situ hybridization to polytene chromosomes of C. thummi thummi and C. thummi piger, p20D DNA hybridized mainly over the A2b region of chromosome IV, whereas pC1.2 DNA hybridized to at least 90 sites distributed over all the chromosomes. A partial nucleotide sequence analysis showed that these clones were very similar and allowed the detection of a 596 bp insert in the pC1.2 clone. This insert possesses all of the essential features of a Class II transposable element and was called MEC. It carries a nearly perfect 107 bp terminal inverted repeat containing one mismatch and is flanked by a 5 bp direct repeat. The 372 bp central region contains a short open reading frame with a coding capacity of 58 amino acids.

Amino Acid Sequence↗
PubMed1990

A tissue-specific puff (Balbiani ring a) in Chironomus thummi may contain a gene encoding a 67-kDa protein which exhibits non-tissue-specific expression.

A 2.3-kb genomic clone has been isolated from the region where the tissue-specific puff, Balbiani ring a (BRa), is found on chromosome IV of the special lobe of Chironomus thummi salivary gland cells. The clone was characterized by nucleotide sequence analysis. Two clusters of direct tandem repeats were identified, as well as large and small open reading frames (ORFs). The large ORF was fused to an Escherichia coli lacZ gene. Antibodies against the beta-galactosidase/ORF fusion protein reacted selectively on Western blots with a 67-kDa protein. Western-blot analysis and immunoelectron microscopy showed that this protein was distributed in the cells of all larval tissues examined. We concluded that BRa, a tissue-specific puff, whose activity correlates with the synthesis of 160-kDa secretory protein [Kolesnikov et al., Chromosoma 83 (1981) 661-677], may also contain a gene which is not expressed in a tissue-specific manner.

Amino Acid Sequence↗
PubMed1990

A new transposable element in Chironomus thummi.

A 1.7 kb long transposable element called TECth1 was found in the 3' flanking region of a Chironomus thummi Balbiani ring gene. As shown by sequence comparison with a second copy, TECth1 is characterized by a perfect terminal inverted repeat of 17 bp flanked by a duplicated target site of 8 bp, four internal imperfect inverted repeats of 17 to 26 bp and terminal regions of about 0.25 kb with a high number of short direct repeats of the consensus sequence ACTTT or permutated and mutated forms such as TTTAC or ACTAT. The terminal inverted repeats and the 8 bp target site duplication are reminiscent of Drosophila P and hobo elements but no long open reading frame starting with ATG is present, suggesting that the two TECth1 copies studied represent deletion derivatives of a longer element coding for its own transposase. In situ hybridization revealed about 75 labelled sites distributed over all chromosomes with the Balbiani ring locus most strongly labelled. Fifty percent of the sites are specific for a given individual, and these variable sites are often heterozygous for the element.

Animals↗
PubMed1981

Cell-specific synthesis and glycosylation of secretory proteins in larval salivary glands of Chironomus thummi.

Synthesis and glycosylation of larval salivary gland secretory proteins of Chironomus thummi were analyzed with respect to cell specific differences in the Balbiani ring (BR) pattern and glycoprotein composition of secretion formerly detected by histochemical staining procedures. In the secretion of a special cell type in salivary glands, which is characterized by the appearance of an additional BR, and additional polypeptide with a relative molecular weight (Mr) of 160 kD was found differing in its antigenic properties and tryptic fingerprint pattern from main cell secretion proteins. This so-called ssp-160 component is preferentially synthesized and glycosylated in the special cells. In the same cells, both the synthesis and glycosylation of all other major secretory proteins was found to be diminished or even repressed. In contrast to the conspicuous cell-specific differences at the level of protein synthesis. RNA analyses show the prominent synthesis of 75S RNA in both main and special cells and gave no clear indication of the synthesis of a smaller RNA fraction as expected from the size of ssp-160 component.--These and further data on synthesis and properties of secretory proteins as well as expression of BR DNA are discussed with regard to the assumption that at least some of the eight major secretory polypeptides are coded for by BR DNA. The BR gene(s) might have originated by manifold duplications and modifications of short repetitive prototype DNA sequences, which are coordinatively expressed.

Animals↗
PubMed1976

[Functional activity of the salivary glands of Drosophila melanogaster in the course of metamorphosis: a comparative electrophoretic analysis of the proteins of the salivary glands, fat body and hemolymph].

The proteins of the salivary gland secretion at the moment of puparium formation and the protein composition of the salivary glands, fat-body and hemolymph during the III larval instar and 12 hours prepupal period were investigated by means of electrophoresis in polyacrilamide gel, in the presence of urea. Both the qualitative and quantitative differences in the protein composition of the salivary glands were found which appeared to be due to the change of functions of the salivary glands in the process of development. 69 protein fractions were isolated in the salivary gland secretion, 40 of them being PAS-positive. A correlation was noted between the appearance of the first PAS-positive fractions at the stage of 95-100 hrs (from the moment of egg laying) and the cytological demonstration of PAS-positive secretion granules. New glycoproteins appeared in the salivary glands in prepupae (2 hrs after the puparium formation) and, later, in the hemolymph. A complicated pattern of the secretion formation in the salivary glands of the III instar larvae and possible change of its composition during metamorphosis are discussed.

Adipose Tissue↗
PubMed1975

[Snythesis of mucoprotein secretion in the salivary glands of Drosophila melanogaster IIIrd instar larvae].

The process of mucoprotein (glue) accumulation is described. This substance is secreted by salivary glands of the III instar larvae of Drosophila melanogaster. Granules of the secretory substance appear in the glandular cells 90 hrs after egg laying. Its secretion takes place within 120 hrs. The template RNA of glue proteins appears to be synthesized within the range of 72-85 hrs since actinomycin treatment of larvae at this time suppresses the formation of secretory substance. The portion of secretory proteins amounts to 23-32% of the total gland protein. In a mutant, 13tl, deficient by the absence of pupation, no PAS-positive, staining of glands or secretory granules identified under the phase-contrast microscope was found. A possible participation of fat body in the formation of mucoprotein secretory substance is discussed.

Animals↗
PubMed1975

[Method of selection of synchronously developing larvae of Drosophila melanogaster].

Methods of obtaining synchronously developing larvae were comparatively evaluated. Larvae were selected by distinct morphological features: time of hatching, second larval moult, pupation. Both virgin and non-virgin females were taken in the experiment. The degree of synchronism was estimated by the interval during which pupation took place in all larvae of the sample. When selecting larvae at the time of second moult, the pupation of all selected larvae was completed within 8 hrs. All other methods of obtaining synchronously developing larvae give a spread of pupation from 12 to 25 hrs. A simple modification of the method of larval selection during the second moult is proposed which allows to obtain a large amount of synchronously developing larvae of the 3rd instar.

Animals↗
PubMedDate not supplied

[The composition of a population of cloned cultures of revertant Vibrio cholerae L forms].

The process of L-transformation and L-transformed state duration have been studied for their effect on variability of main characters of revertant cultures of choleric vibrions L-forms at the population level with the use of cloned cultures of the choleric vibrions. The study was conducted on two strains of the choleric vibrion of the eltor biovar in different periods of storage in the L-transformed state (1, 3, 6 months). It has been revealed that characters of the species and biovar remained stable despite the influence of L-transforming agents. The characters of clone cultures characterizing virulence (sensitivity to KhDF phages, hemolytic activity, toxin production and virulence for sucking rabbits proved to be subjected to variability to the greatest extent with simultaneous preservation of the toxin-production gene. A resistant change of the serovar (from Inaba to Ogava) is observed only in one revertant-subculture of the virulent strain.

Bacteriological Techniques↗
PubMedDate not supplied

[The characteristic properties of Vibrio cholerae eltor isolated from environmental objects on the territory of the former USSR during the 7th cholera pandemic].

The properties of 22,382 V. eltor strains isolated from environmental objects on the territory of different climatic and geographical zones during the period of 1970-1988 were studied. The study was made on the morphology of their colonies, the agglutinability of the strains by cholera O serum, type-specific serum and RO serum, their capacity for being lyzed by V. eltor bacteriophage, their hemolytic activity and virulence. Differences in the occurrence of strains with any of the above-mentioned properties, depending on the object from which they were isolate, the climatic and geographical zone and the intensity of the epidemiological situation with regard to cholera.

Cholera↗