Chironomids (Diptera: Chironomidae) in lakes of central Yakutia and their indicative potential for paleoclimatic research

A study of chrionomid fauna was carried out in two regions of central Yakutia. Fossilized remnants of head capsules were sampled from shallow layers of the bottom sediments of lakes. Seventy five taxa of chironomids have been determined. Statistical analysis shows that the spatial distribution of chironomid taxa in the study regions is mainly controlled by ions of aluminium and magnesium, mean July temperature, transparency and content of oxygen in water. The obtained results serve as the base for development of a chironomid temperature model used for reconstruction of Holocene and Pleistocene paleotemperatures of the Russian North.     

Some features of methylpyrophosphate hydrolysis by yeast inorganic pyrophosphatase

The interaction of yeast inorganic pyrophosphatase with methylpyrophosphate was studied. In the presence of Mg2+ the rate of hydrolysis of the methylpyrophosphate-Zn2+ complex by the enzyme was shown to decrease. This was accompanied by competition of Zn2+ and Mg2+ for one site of Me2+ binding on the enzyme. The kinetics of combined hydrolysis of zinc methylpyrophosphate and zinc pyrophosphate were studied. It was found that both substrates are hydrolyzed at the same active site of the enzyme. Free methylpyrophosphate when bound to a specific phosphorylation site on the enzyme surface accelerated magnesium pyrophosphate hydrolysis. Some kinetic parameters of this hydrolysis were determined.     

Decomposition of human blood cholesterol by the enzyme from Actinomyces lavendulae

In vitro experiments with enzymic decomposition of cholesterol contained in the human blood were carried out. The enzyme was obtained from the mycelium of Actinomyces lavendulae. As a result of incubation of blood samples in the presence of the enzyme at 37 degrees, the cholesterol content decreased and reached 30--43% of the initial value within 2 hours. The enzyme showed its specific effect only upon free cholesterol but not on its esters.     

Diatoms of modern bottom sediments in Siberian arctic

The investigation of the species composition and ecology of diatoms of modern bottom sediments in water bodies of arctic polygonal tundra in three subregions of North Yakutiya has been carried out. As a result, 161 taxons of diatoms were determined; the determinant role of the depth, conductivity, pH of the water, and geographic latitude in their distribution was confirmed, and two complexes of species with respect to the leading abiotic factors were distinguished. The diatoms of the first complex prefer shallow water bodies of high latitudes with neutral and slightly alkaline water and relatively high conductivity. The second complex is confined to the water bodies of lower latitudes with small conductivity, as well as neutral and slightly acidic water.     

Dynamics of morphophysiological charateristics in female water voles (Arvicola amphibius L.) during pregnancy

Pregnancy and lactation need increased energy consumption and are accompanied by morphological and physiological changes of various maternal organs and systems. In water voles, connection of female interior characteristics has been poorly studied. Under standard vivarium conditions, we evaluated morphophysiological parameters of non-reproducing females and of females at the early (1–7 days), intermediate (8–14 days), and late (15–21 days) stages of pregnancy. There were established effect of the reproductive state on mass of abdominal and brown adipose tissue, liver, adrenals, spleen and an increment of body mass (without uterus with embryos). In pregnant females, as compared with the non-pregnant ones, the blood thyroxine level was significantly lower (16.2 ± 0.8 and 21.7 ± 1.4 pmol/l) and the blood testosterone level was higher (1.29 ± 0.19 and 0.83 ± 0.09 nmol/l). The blood glucose content fell in the end of pregnancy. Dynamics of morphophysiological parameters at the period of pregnancy reflects the compensatory body reactions providing preservation of embryos and preparation to lactation of offspring.     

Influence of cadmium ions on some morphofunctional and immune-physiological parameters of perch (<Emphasis Type="Italic">Perca fluviatilis</Emphasis>, Perciformes,Percidae) underyearlings

The changes in some morphofunctional and immune-physiological parameters in perch (Perca fluviatilis) underyearlings exposed to sublethal cadmium chloride concentration have been analyzed. The fluctuations of kidney index values and stimulating effect of toxicant upon humoral factors of nonspecific immunity have been revealed. The leucocytes ratio has been changed most sharply in the peripheral blood, kidney, and liver, but directions of changes in blood, liver, and kidney were different. Suppression of spontaneous and enhancement of induced phagocytosis by blood neutrophils were noted. In general, the observed changes correspond well to nonspecific stress response. It is concluded that the studied parameters are quite sensitive indices for assessment of environmental toxicity to fish.     

A regulatory protein isolated from cattle milk

A regulatory protein displaying biological activity at ultralow doses was identified in cow’s milk. The isoelectric point for this protein falls into the pH range of 4.48–5.59, and the molecular weight does not exceed 10 kDa. A study of the secondary structure detected the predominant presence of β-structures, especially antiparallel, in the molecule of this regulatory protein as well as the regions described in terms of a statistical globule. It was demonstrated that this protein is located extracellularly in the epithelium of mammary ducts, and that this regulatory protein is present in an active form in whole milk; however, it was detectable neither in dry milk nor in infant formula. The results obtained suggest that the milk regulatory protein characterized in this work was identical to low-molecular-weight serum glycoprotein, one of the proteins studied earlier, displaying biological activity at ultralow doses.     

A regulatory protein isolated from cattle milk

A regulatory protein displaying biological activity at ultralow doses was identified in cow's milk. The isoelectric point for this protein falls into the pH range of 4.48-5.59, and the molecular weight does not exceed 10 kDa. A study of the secondary structure detected the predominant presence of beta-structures, especially antiparallel, in the molecule of this regulatory protein as well as the regions described in terms of a statistical globule. It was demonstrated that this protein is located extracellularly in the epithelium of mammary ducts, and that this regulatory protein is present in an active form in whole milk; however, it was detectable neither in dry milk nor in infant formula. The results obtained suggest that the milk regulatory protein characterized in this work was identical to low-molecular-weight serum glycoprotein, one of the proteins studied earlier, displaying biological activity at ultralow doses.