Reaction of the blood forming system of the dogs to acute radiation exposure (by the SRC-Institute of biophysics data bank)

At present time in the SRC--Institute of Biophysics the data bank containing the information on the reactions of 431 dogs to radiation exposure in a wide range of doses has been created. By the results of 4299 blood tests reporting a leukocyte content, including 2509 tests reporting a blood formula, the individual peculiarity of the peripheral blood reaction in dogs were analyzed. Dose dependencies for the reaction of blood-forming system to radiation exposure to doses in the range from 1.0 to 7.0 Gy were obtained. In comparison with the similar data for humans, the neutrophil content in peripheral blood decreased approximately 1.5-2.0 times faster in dogs than in men, resulting in earlier recovery.     

Phototropic response features for different systematic groups of mesoplankton under adverse environmental conditions

Current trends in the application of bioindication methods are related to the use of submersible tools that perform real‐time measurements directly in the studied aquatic environment. The methods based on the registration of changes in the behavioral responses of zooplankton, in particular Crustaceans, which make up the vast majority of the biomass in water areas, seem quite promising. However, the multispecies composition of natural planktonic biocenoses poses the need to consider the potential difference in the sensitivity of organisms to pollutants.This paper describes laboratory studies of the phototropic response of plankton to attracting light. The studies were carried out on a model natural community that in equal amounts includes Daphnia magna, Daphnia pulex, and Cyclops vicinus, as well as on the monoculture groups of these species. The phototropic response was initiated by the attracting light with a wavelength of 532 nm close to the local maximum of the reflection spectrum of chlorella microalgae. Standard potassium bichromate was used as the model pollutant.The largest phototropic response value is registered in the assemblage. The concentration growth rate of crustaceans in the illuminated volume was 4.5 ± 0.3 ind (L min)⁻¹. Of the studied species, the phototropic response was mostly expressed in Daphnia magna (3.7 ± 0.4 ind (L min)⁻¹), while in Daphnia pulex, it was reduced to 2.4 ± 0.2 ind (L min)⁻¹, and in Cyclops vicinus, it was very small—0.16 ± 0.02 ind (L min)⁻¹. This is caused by peculiar trophic behavior of phyto‐ and zoophages. The addition of a pollutant, namely potassium bichromate, caused a decrease in the concentration rate of crustaceans in the attracting light zone, while a dose‐dependent change in phototropic responses was observed in a group of species and the Daphnia magna assemblage.The results of laboratory studies showed high potential of using the phototropic response of zooplankton to monitor the quality of its habitat thus ensuring the early diagnostics of water pollution. Besides, the paper shows the possibility of quantifying the phototropic response of zooplankton using submersible digital holographic cameras (DHC).     

Degradation of maltose by proliferating cells of Desulfovibrio desulfuricans 2198.

Desulfovibrio desulfuricans 2198 can grow on maltose-based medium only in the presence of yeast extract. The results of kinetic measurements of maltose consumption by the cells show that there is no marked difference in Km and Vmax values for this bacterium versus other carbohydrate-utilizing microorganisms. The determination of some enzymes of sugar metabolism in D. desulfuricans 2198 suggests that maltose degradation occurs by the Embden--Meyerhof pathway. The cell extract also contains glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. 2-Keto-3-deoxy-6-phosphogluconate aldolase, the key enzyme of the Entner--Doudoroff pathway, is not found in D. desulfuricans 2198. In the bacterium grown on [U-14C]maltose-containing medium, a portion of the labeled carbon is incorporated into biomass. As degradation products, labeled acetate and carbon dioxide are found.     

Protein methylation in mitochondria

Many proteins are modified by posttranslational methylation, introduced by a number of methyltransferases (MTases). Protein methylation plays important roles in modulating protein function and thus in optimizing and regulating cellular and physiological processes. Research has mainly focused on nuclear and cytosolic protein methylation, but it has been known for many years that also mitochondrial proteins are methylated. During the last decade, significant progress has been made on identifying the MTases responsible for mitochondrial protein methylation and addressing its functional significance. In particular, several novel human MTases have been uncovered that methylate lysine, arginine, histidine, and glutamine residues in various mitochondrial substrates. Several of these substrates are key components of the bioenergetics machinery, e.g., respiratory Complex I, citrate synthase, and the ATP synthase. In the present review, we report the status of the field of mitochondrial protein methylation, with a particular emphasis on recently discovered human MTases. We also discuss evolutionary aspects and functional significance of mitochondrial protein methylation and present an outlook for this emergent research field.     

HIV infection in Saint Petersburg: the changing face of the epidemic

The specific features of the epidemiological situation in St. Petersburg at the first stage (1987-1995) and the second stage (1986-1999) of the development of HIV infection are described. During this period morbidity in HIV infection, starting from the insignificant rate of growth, sharply increased. For the first time injecting drug users were noted to come out to the foreground in the structure of the contingent of persons affected by HIV infection (57.5% and 72.6% in 1998 and 1999 respectively). Such change on the epidemic situation requires corrections in the strategy and tactics of preventive measures and medical assistance. To control HIV infection among drug users, only the combination of medical assistance given by narcologists with the realization of all elements of the program "Harm Reduction" can be effective.     

L22 ribosomal protein and effect of its mutation on ribosome resistance to erythromycin

The ribosomal protein L22 is a core protein of the large ribosomal subunit interacting with all domains of the 23S rRNA. The triplet Met82-Lys83-Arg84 deletion in L22 from Escherichia coli renders cells resistant to erythromycin which is known as an inhibitor of the nascent peptide chain elongation. The crystal structure of the Thermus thermophilus L22 mutant with equivalent triplet Leu82-Lys83-Arg84 deletion has been determined at 1.8A resolution. The superpositions of the mutant and the wild-type L22 structures within the 50S subunits from Haloarcula marismortui and Deinococcus radiodurans show that the mutant beta-hairpin is bent inward the ribosome tunnel modifying the shape of its narrowest part and affecting the interaction between L22 and 23S rRNA. 23S rRNA nucleotides of domain V participating in erythromycin binding are located on the opposite sides of the tunnel and are brought to those positions by the interaction of the 23S rRNA with the L22 beta-hairpin. The mutation in the L22 beta-hairpin affects the orientation and distances between those nucleotides. This destabilizes the erythromycin-binding "pocket" formed by 23S rRNA nucleotides exposed at the tunnel surface. It seems that erythromycin, while still being able to interact with one side of the tunnel but not reaching the other, is therefore unable to block the polypeptide growth in the drug-resistant ribosome.     

Antioxidative enzymes of sulfate-reducing bacterium desulfovibrio desulfuricans: superoxide dismutase and peroxidases

Extracts of Desulfovibrio desulfuricans B-1388 cells grown under anaerobic conditions displayed superoxide dismutase activity. The maximal activity was found during the stationary growth phase. The enzyme was virtually completely located in the periplasm fraction. D. desulfuricans B-1388 lacked catalase activity but contained active NADH- and NADPH-peroxidases. The activity of NADH-peroxidase depended on the physiological state of the culture. On changing the growth conditions (the presence of 5% CO in the gaseous phase), the activity of superoxide dismutase decreased.