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.     

Ichthyoplankton of the eastern shelf of Sakhalin Island and its use as an environmental state indicator

Results of studying ichthyoplankton off the eastern coast of Sakhalin Island in July 2002, are presented. The spatial distribution of the eggs and larvae of almost all encountered species confirms the presence of drift along the coast with a gradual drift of passive migrants from the coast of eastern Sakhalin into the open waters. The most diverse and numerous ichthyoplankton was over the shelf zone to the north of 51°00′; the least diverse, from 50°00′ to 51°00′ N. The minimal proportion of the normally developing eggs of the wall-eyed pollack Theragra chalcogramma and the yellow-finned sole Limanda aspera dominant in catches was recorded over the oil-gas deposits located in the coastal zone of the northeastern shelf. The coincidence of stations (83%) with a high proportion of the dead eggs of these fish species can indicate a similar impact on it of environmental conditions formed in deposit areas.     

Effect of pancreatic DNAse on the nuclear DNA topology of Candida tropicalis yeasts

It has been shown that pancreatic DNAase added to the nutritious medium caused the change in the nuclear DNA topology of asporogenic Candida tropicalis yeast. DNA conformative changes are due to the unwinding of supertwisted molecules as a result of single-strand ruptures formation which induce DNA synthesis acceleration, cell growth and division.     

Dynamics of proteins in a culture broth growing beta-hemolytic streptococci group C

The dynamic study of the protein spectrum of culture fluid during the growth of beta-hemolytic streptococcal strain H46A has been carried out by the methods of electrophoresis and isoelectrofocusing in polyacrylamide gel. Changes in the protein spectrum have phasic character and, on the whole, reflect the state of the microbial population, the presence of fractions corresponding to streptokinase and streptolysins being detected at all phases of growth. The electrophoretic mobility of streptokinase perceptibly changes at the end of the logarithmic phase; as shown by electrofocusing, at all stages of the population growth the heterogeneity of streptokinase is observed.     

Immunocompetence increases with larval body size in a phytophagous moth

Despite the obvious benefit of an immune system, its efficacy against pathogens and parasites may show great variation among individuals, populations and species. Understanding the causes of this variation is becoming a central theme in ecology. Many biotic and abiotic factors are known to influence immunocompetence (temperature, age, etc.). However, for a given age, size among individuals varies, probably as a result of accumulated resources. Thus, these variable resources could be allocated to immune defence and, consequently, body size may explain part of the variation in immune responsiveness. However, the influence of body size on immune defence is often overlooked. The present study investigates variations in haemocyte count and phenoloxidase activity in larvae of the phytophagous vine moth Eupoecilia ambiguella Hübner of the same age, although differing in body size. The measurements of immune function are made both when the insects are immunologically naïve and 24 h after a bacterial immune challenge. The base levels of these immune parameters do not covary with body size in naïve larvae. After the bacterial immune challenge, more haemocytes and phenoloxidase enzyme are mobilized, and the mobilization of these immune effectors is correlated positively with individual body size. Thus, larger larvae exhibit higher immunocompetence than smaller ones, suggesting that smaller larvae might be more vulnerable to infection. These results suggest that body size is probably an underestimated variable, which nevertheless modulates the insect immune system and should thus be considered as a covariate in insect immune system measurement. It is recommended therefore, that body size should be taken into account in ecological immunity studies with insects. © 2013 The Royal Entomological Society     

Identification of chemical elements as pollutants and their primary distribution in steppes of the southern Minusinsk depression

The chemical composition of solid and liquid phases of snow samples collected at different distances from various sources of anthropogenic emissions was studied. The main chemical elements polluting geosystems during the production of aluminum were determined and the halos of their spatial scattering were revealed. The total pollution index and the load of pollution were calculated. Based on quantitative indicators in comparison with maximum permissible concentration values, zones of ecological and geochemical risk were identified. A comparative analysis of the levels of the selected association of elements in technogenic aerosols of the area of the greatest risk and in background soil was carried out.