The Methemoglobin Blood Level and Stability of Circulating Erythrocytes of the Rockfish Scorpaena porcus to Osmotic Shock under Conditions of Experimental Hypoxia

Under experimental conditions the oxygen content in water was reduced to 1.3–1.4 mg l^–1 (15% of the saturation) and 2.6–2.7 mg(l^–1 (30% of the saturation). The rockfish (Scorpaena porcus L. ) were kept under these conditions for 90 min. Analysis of samples has shown a decrease of methemoglobin level by 58.2% (p < 0.001) and an increase of erythrocyte stability to the osmotic shock. The cell lysis occurred at lower concentrations of NaCl. It is concluded that the process of natural oxygenation is one of the causes of the rise of the oxidized pigment concentration in the fish blood. This is due to low efficiency of erythrocytic NADH-diaphorases and is compensated by an increase of activity of enzymes of the cell antioxidant protection system. The latter prevents from development of peroxidation processes and lysis of cells during their circulation despite a comparatively high level of methemoglobin in blood.     

Taxonomic composition of Lake Baikal bacterioneuston communities

The taxonomic composition of microbial communities of Lake Baikal surface microlayer was studied by pyrosequencing of the 16S rDNA amplicons. Statistically reliable differences were found between bacterioneuston of the shallow and deep-water stations. The shallow station community was characterized by higher diversity than the deep-water one. While bacterioneuston communities were shown to be less diverse than the water column communities, their diversity was comparable to that of other biofilm associations. Microbial communities of Lake Baikal surface microlayer were shown to be similar to those of the water column in the composition of predominant phyla, while differing considerably at the genus level. Bacterioneuston of Lake Baikal was comparable to microbial communities of the surface microlayer of other freshwater basins, although it was characterized by high abundance of the Alphaproteobacteria and Verrucomicrobia. High abundance of photoheterotrophs compared to the water column communities of other freshwater basins was another distinctive feature of Lake Baikal bacterioneuston. Our results showed the Lake Baikal surface microlayer to be a specific microbial community with low species diversity and relatively high abundance of photoheterotrophic microorganisms.     

Combined prophylactic administration of riboxin and algisorbum at 239Pu intake into gastrointestinal tract of rats

The present study is devoted to the investigation of effectiveness of combined prophylactic administration of riboxin and algisorbum at 239Pu per oral intake and possible mechanisms of their interaction, and also to comparative estimation of effectiveness of combined administration of the preparations at per oral and intra peritoneal methods of riboxin introduction. The experiments have been carried out on white nonlinear rats. Riboxin (per oral and intra peritoneal) and algisorbum (per oral) have been introduced to the rats both separately and combined before per oral 239Pu introduction. Data obtained as a result of the investigation showed that combined riboxin and algisorbum introduction into gastrointestinal tract before 239PU intake lead to greater decrease in the plutonium content in the organs of deposition than single algisorbum administration. Intra peritoneal riboxin introduction reduced effectiveness of per oral algisorbum administration in plutonium binding in GI tract. Efficiency of combined riboxin and algisorbum administration in the reduction of 239Pu accumulation in organs depends on the method of riboxin introduction and develops only at per oral introduction.     

Permissive contributions of NO and prostacyclin in CO-induced cerebrovascular dilation in piglets

Endogenously produced CO is an important dilator in newborn cerebrovascular circulation. CO dilates cerebral arterioles by activating Ca2+-activated K+ channels, but modulatory actions of other effectors and second messenger inputs are unclear. Specifically, the mechanisms behind the obligatory permissive roles of prostacyclin and NO are uncertain. Therefore, the present study was performed using acutely implanted, closed cranial windows in newborn pigs to address the hypothesis that the permissive roles of NO and prostacyclin in cerebrovascular dilation in response to CO involve a common mechanism. The NO donor sodium nitroprusside restored dilation in response to CO after inhibition of that dilation with the prostaglandin cyclooxygenase inhibitor indomethacin. The stable prostacyclin analog iloprost restored CO-induced dilation blocked by the NO synthase inhibitor Nomega-nitro-L-arginine. Restoration of dilation in response to CO by the cGMP-dependent phosphodiesterase inhibitor zaprinast and blockade of CO dilation by the guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazole-[4,3-a]quinoxalin-1-one (ODQ) suggests involvement of the cGMP/PKG pathway. Iloprost or the cAMP-dependent dilator isoproterenol restored dilation in response to CO after ODQ administration. However, CO-induced dilation blocked by the cGMP-dependent PKG inhibitor Rp-8-[(4-chlorophenyl)thio]-cGMPS triethylamine could not be reversed by administration of sodium nitroprusside, iloprost, or isoproterenol. Conversely, PKA inhibition did not block dilation in response to CO. Overall, data indicate that activation of PKG is the predominant mechanism of the permissive actions of NO and prostacyclin for CO-induced pial arteriolar dilation.     

Study of the influence of peroral zincacin on the removing of ingested Americium

Effect of different cincacine doses was studied in rats ingesting americium citrate during 2 weeks. As a result new data showing the possibility and efficacy of per oral cincacine administration at americium intake into digestive tract have been obtained. Dose dependence of cincacine efficacy has been stated for per oral 241Am intake. Preparation administration at a dose of 25 mumol/kg reduces amount of 241Am in skeleton, liver and kidney by 93, 90 and 33%, respectively and is optimum for radionuclide removal from the body and for the prevention of its deposition in organs. Digestive system organs and kidney structure at cincacine administration at a dose of 150 and 300 mumol/kg) to the rats ingesting 241Am have been studied.     

Dependence of the structure of malate dehydrogenase on the type of metabolism in fresh water filamentous colorless sulfur bacteria of the Beggiatoa species

Major pathways of carbon metabolism were studied in strains D-402 and D-405 of freshwater colorless sulfur bacteria of the genus Beggiatoa grown organotrophically and mixotrophically. The bacteria were found to possess all the enzymes of the tricarboxylic acid (TCA) and glyoxylate cycles. When organotrophic growth changed to mixotrophic one, the activity of the TCA cycle enzymes decreased 2- to 3-fold, but the activity of enzymes of the glyoxylate cycle increased threefold. It follows that, in the oxidation of thiosulfate, organic compounds no longer play the leading part in the energy metabolism, and most of electrons that enter the electron transport chain (ETC) derive from inorganic sulfur compounds. A connection was established between the structure and kinetic characteristics of malate dehydrogenase--an enzyme of the TCA and glyoxylate cycles--and the type of carbon metabolism in the strains studied. Malate dehydrogenase in organotrophically grown cells of strains D-402 and D-405 is dimeric, whereas in strain D-402 grown mixotrophically it is tetrameric.     

The biodiversity of actinomycetes in Lake Baikal

The taxonomic analysis of 107 actinomycete strains isolated from the bottom sediments and water of Lake Baikal showed that most of the water isolates belong to the genus Streptomyces and most of the sediment isolates belong to the genus Micromonospora. In the sediments, the number of actinomycetes increased with depth (down to 200 m). Eight Streptomyces isolates were identified to a species level.     

Microbial biodiversity in the Lake Baikal water

The investigation of the microbial community of Lake Baikal by the methods of general and molecular microbiology showed that culturable bacterial strains were represented by various known genera. The lake water contains a great number of bacterial morphotypes, as revealed by electron microscopy, and a great diversity of nonculturable microorganisms belonging to different phylogenetic groups, as revealed by 16S rRNA gene fragment sequencing. The inference is made that the microbial community of Lake Baikal contains not only the known species but also new, possibly endemic to the lake, bacterial species.     

Carbon monoxide mediates vasodilator effects of glutamate in isolated pressurized cerebral arterioles of newborn pigs

The excitatory neurotransmitter glutamate causes dilation of newborn pig cerebral arterioles in vivo that is blocked by inhibition of carbon monoxide (CO) production. CO, a potent dilator in cerebral circulation in vivo, is produced endogenously in cerebral microvessels via heme oxygenase (HO). In isolated pressurized cerebral arterioles (approximately 200 microm) from newborn pigs, we investigated the involvement of CO and the endothelium in response to glutamate. A CO-releasing molecule, dimanganese decacarbonyl (10(-8)-10(-6) M), dilated cerebral arterioles. Glutamate (10(-6)-10(-4) M) and 1-aminocyclopentane-cis-1,3-dicarboxylic acid (cis-ACPD; 10(-6)-10(-5) M), a N-methyl-D-aspartate (NMDA) receptor agonist, caused cerebral vascular dilation. Dilation of cerebral arterioles to glutamate and cis-ACPD was abolished by chromium mesoporphyrin (CrMP; 10(-6) M), a HO inhibitor. In contrast, CrMP did not alter dilation to isoproterenol, a -adrenergic receptor agonist. Endothelium-denuded cerebral arterioles did not dilate to glutamate or bradykinin (endothelium-dependent dilator), whereas responses to isoproterenol were preserved. These data indicate that cerebral arterioles from newborn pigs may directly respond to glutamate and the NMDA receptor agonists by endothelium-dependent dilation that involves stimulation of CO production via the HO pathway in the endothelium.