Effect of oxidative stress inductors on the photosynthetic apparatus in cyanobacterium Synechocystis sp. PCC 6803 Prq20 mutant resistant to methyl viologen

The damaging effect of oxidative stress inductors: methyl viologen, benzyl viologen, cumene hydroperoxide, H2O2, menadion, and high irradiance on the photosynthetic apparatus of cyanobacterium Synechocystis sp. PCC 6803 in cells of the wild type strain and the methyl viologen-resistant Prq20 mutant with the disrupted function of the regulatory gene prqR has been investigated by measuring the delayed fluorescence of chlorophyll a and the rate of CO2dependent -O2 gas exchange. It has been shown that the damage to the photosynthetic apparatus in the Prq20 mutant as compared with the wild type was less in the presence of methyl viologen and benzyl viologen. Reasons for the enhanced resistance of the photosynthetic apparatus in the mutant Prq20 to methyl viologen and benzyl viologen are discussed.     

The possible role of immunogenetic factors in the pathogenesis of HIV infection

In this review the data on the presence of associations between immunogenetic markers and the development of HIV infection are presented. Special attention is given to spatial relationships of genetic determinants, responsible for the synthesis of the components of the complement system on one hand and the genes controlling resistance to the causative agents of opportunistic infections and malignant growth on the other hand. Suggestion is made on close relationship between the specific features of the course of HIV infection and the genetic control, responsible for the synthesis of complement components, in particular the genes making up the HLA system.     

Outpatient screening and its place in better detection of breast tumors

The authors state their opinion on this problem by analyzing their 5-year use of their programme specially developed for detection of breast disease, mainly cancer, among females visiting specialized rooms of non-mammological profiles (gastroenterology, endocrinology, rheumatology, pulmonology, neurology, cardiology, hematology, nephrology, etc.) in the consulting polyclinics of regional (territorial) hospitals and large city hospital-polyclinic complexes. In this period, mammographic studies were made in 9169 women included into a breast cancer-risk group. Of them 1370 young female patients with well-developed glandular tissue that makes mammographic diagnosis of presumed masses difficult underwent breast ultrasonography. Abnormalities were found in 6092 (66.44%) patients. Breast cancer and nodal benign masses (including cysts and fibroadenomas) were detected in 278 (3.03%) and 669 (7.30%) women, respectively. The detection rates of unpalpable breast malignant and benign masses carcinomas were 0.4 and 3.03%, respectively. The findings allow the authors to recommend their proposed screening programme for wide use in large regional (territoreal), city, and town polyclinic complexes.     

Epidemiological surveillance on natural-borne infections in the Ulyanovsk region

The analysis of natural foci of haemorrhagic fever with renal syndrome (HFRS) and tick-borne borreliosis on the territory of the Ulyanovsk region is presented. Reduced rat control interventions result in a wide spread of these and other infections with natural focality. Monitoring of natural foci of HFRS, tick-borne borreliosis and arbovirus infections, their typing and determination of main reservoirs are the most promising among epidemiological surveillance methods.     

The accumulation and degradation dynamics of cyanophycin in cyanobacteria grown in symbiotic associations with plant tissues and cells

Five different artificial associations of cyanobacterial cells with the cells or tissues of nightshade and rauwolfia were studied. The associations grown on nitrogen-containing media produced heterocysts. Cyanobacterial cells in the associations retained their ability to take up bound nitrogen from the medium, to store it in the form of cyanophycin granules, and to use them in the process of symbiotic growth. The synthesis and degradation of cyanophycin granules in cyanobacterial cells were more active in the associations than in monocultures. In the symbiotic associations of Chlorogloeopsis fritschii ATCC 27193 with Solanum laciniatum cells and of Nostoc muscorum CALU 304 with the Rauwolfia serpentina callus, heterocysts were produced at 3- to 30-fold higher cyanophycin contents than in cyanobacterial monocultures. In contrast, in the association of N. muscorum CALU 304 with the Solanum dulcamara callus, heterocysts were produced at lower cyanophycin contents than in the N. muscorum CALU 304 monoculture. The degradation of cyanophycin granules in N. muscorum CALU 304 cells grown in associations with plant tissues or cells was subjected to mathematical analysis. The activation of cyanophycin degradation and heterocyst production in the associations N. muscorum CALU 304-R. serpentina and C. fritschii-S. laciniatum was accompanied by an enhanced synthesis of the nitrogen-containing alkaloids in plant cells. The data obtained suggest that an integrated system of nitrogen homeostasis can be formed in symbiotic associations. Depending on the growth stage of an association, its plant member can either stimulate the accumulation of bound nitrogen in vegetative cyanobacterial cells in the form of cyanophycin granules, or activate their degradation, or initiate the formation of heterocysts independently of the cyanobacterial sensory-signalling system.     

Urokinase induces adhesion of monocytes to fibrinogen

Urokinase activates adhesion of monocytic U937 cells to fibrinogen-coated surface. This effect is due to urokinase proteolytic activity and does not depend on the urokinase binding to its receptor.     

Single amino acid substitutions in the Ca2+-binding site of recoverin.II.The unusual behavior of the protein upon the binding of calcium ions

The structural properties of myristoylated forms of recombinant recoverin of the wild type and of its mutants with damaged second and/or third Ca(2+)-binding sites were studied by fluorimetry and circular dichroism. The interaction of wild-type recoverin with calcium ions was shown to induce unusual structural rearrangements in its molecule. In particular, protein binding with Ca2+ ions results in an increase in the mobility of the environment of Trp residues, in higher hydrophobicity, and in elevated thermal stability (its thermal transition shifts by 15 degrees C to higher temperatures) but has almost no effect on its secondary structure. Similar structural changes induced by Ca2+ are also characteristic of the -EF2 mutant of recoverin whose second Ca(2+)-binding site is modified and cannot bind calcium ions. The structural properties of the -EF3 and -EF2,3 mutants (whose third or simultaneously second and third Ca(2+)-binding sites, respectively, are modified and damaged) are practically indifferent to calcium ions.