Transformation of Microbial Complexes in Components of Soil Constructions of Different Origin (Soil,Peat, Sand) during Freezing-thawing Processes

Microbiology - In a model experiment, the transformation of microbial complexes of cultivated saprotrophic bacteria and yeasts during freezing-thawing was studied in various natural substrates that...     

Effect of heparin on the activation of the anticoagulation system by alpha-thrombin

Heparin-regulated alpha-thrombin ability to activate the response of the anticoagulation system has been studied by the perfusion of sinocarotid area of rabbits with DIP-alpha-thrombin-heparin complex. In a series of experiments the area was perfused with 1.8 micron DIP-alpha-thrombin and significant changes in anticoagulation parameters have been registered in systemic circulation. During perfusion of sinocarotid area by DIP-alpha-thrombin-heparin complex (2 microns) no activation of anticoagulation system was noted. DIP-alpha-thrombin-heparin perfusates contained no endogenic heparin, unlike DIP-alpha-thrombin perfusates. This confirms the absence of anticoagulation system response to DIP-alpha-thrombin. Control perfusion by heparin alone in equimolar concentrations revealed no changes in anticoagulation system. It is assumed that heparin, blocking cation subcentre of the recognition centre for high molecular compounds in the enzyme molecule, prevents the response of anticoagulation system, disturbing the enzyme ability to bind to specific receptors of the vascular walls.     

The use of triplet-sensitized photochromism phenomenon for the study of dynamic interaction of membrane proteins

Possibility of registration of protein interactions in the membranes was demonstrated. The membrane preparation of Na+, K+ ATPase was used in the investigations. The Na+, K+ ATPase was bound with 4-acetoamido-4'-isothiocyanatostilbene-2,2' disullfonic acid (SITS) and erythrosinisothiocyanate (ERITC). The label/Na+,K+ATPase (M/M) ratio was equal to 1:1 for SITS and changed from 1:1 to 1:5 for ERITC. The cis-trans isomerization of SITS was initiated by triplet-triplet energy transfer from light excited ERITC to SITS. The kinetics of isomerization was recorded by the SITS fluorescence measurements. The rate constant of triplet-triplet energy transfer (kT) from ERITC to cis isomer of SITS, (3 divided by 7) X 10(3) M-1 s-1 was determined at 25 degrees C. The kT value of the energy transfer between loose molecules of erythrosine and SITS in buffer solution equaled to 7 X 10(7) M-1 s-1. This drop of kT in the membrane at 10(4) reflected the decrease in the frequency of label collisions caused by the increase in the media viscosity and steric hindrances.     

Environmental and endogenous control of diapause inTrichogramma species

The 1st feature revealed typical for diapause phenomena inTrichogramma species is the interaction of environmental conditions in both parental and filial generations in induction of diapause in the latter. Lowered temperature during larval development is the ultimate factor evoking diapause in pronymphs but the norm of this thermal reaction is not fixed but varies depending on photoperiod and temperature in the previous generation due to maternal influence. Short day and in some cases high temperature in parental generation enhance tendency to diapause in the progeny. Unlike maternal influence the development to filial generation itself is not (or almost is not) governed by its own photoperiodic reaction. The 2nd typical feature revealed is the occurrence of endogenous process running in the sequence of generations and causing changes in the diapause tendency and underlying reaction norms even under constant rearing conditions.      

The effect of an insulin load on rat mast cells]

The increase of heparin secretion by mast cells of kidney capsule and subcutaneous fat has been noted in rats after 30 min intravenous insulin administration in a dose 0.3 U/200 g (by this time the blood sugar concentration lowers by 40%). The index of mast cells saturation with heparin drops by 2.3 and 1.9 times correspondingly. After preliminary administration of protamine sulphate (2 mg/200 g that provokes in rats the status of temporary resistance to the hypoglycemic action of insulin the stimulatory effect of insulin on the function of mast cells does not occur.     

中国西北沙漠夜间活动的东鳖甲属昆虫二新种(鞘翅目:拟步甲科:漠甲亚科)

记述中国西北地区东鳖甲属2新种:巴丹东鳖甲A.badainica Ba,Ren&Liu sp.nov.和古尔班东鳖甲A.gurbantunggutica Ba&Ren sp.nov.,提供了主要鉴别特征和形态图,并简要讨论了其昼夜活动规律.     

Haemosporidian Parasites of Antelopes and Other Vertebrates from Gabon,Central Africa

Re-examination, using molecular tools, of the diversity of haemosporidian parasites (among which the agents of human malaria are the best known) has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting vertebrate species (particularly mammals, birds and reptiles) living in the forests of Gabon (Central Africa), by analyzing a collection of 492 bushmeat samples. We found that samples from five mammalian species (four duiker and one pangolin species), one bird and one turtle species were infected by haemosporidian parasites. In duikers (from which most of the infected specimens were obtained), we demonstrated the existence of at least two distinct parasite lineages related to Polychromophilus species (i.e., bat haemosporidian parasites) and to sauropsid Plasmodium (from birds and lizards). Molecular screening of sylvatic mosquitoes captured during a longitudinal survey revealed the presence of these haemosporidian parasite lineages also in several Anopheles species, suggesting a potential role in their transmission. Our results show that, differently from what was previously thought, several independent clades of haemosporidian parasites (family Plasmodiidae) infect mammals and are transmitted by anopheline mosquitoes.     

Molecular basis of ion permeability in a voltage‐gated sodium channel

Voltage‐gated sodium channels are essential for electrical signalling across cell membranes. They exhibit strong selectivities for sodium ions over other cations, enabling the finely tuned cascade of events associated with action potentials. This paper describes the ion permeability characteristics and the crystal structure of a prokaryotic sodium channel, showing for the first time the detailed locations of sodium ions in the selectivity filter of a sodium channel. Electrostatic calculations based on the structure are consistent with the relative cation permeability ratios (Na⁺ ≈ Li⁺ ≫ K⁺, Ca²⁺, Mg²⁺) measured for these channels. In an E178D selectivity filter mutant constructed to have altered ion selectivities, the sodium ion binding site nearest the extracellular side is missing. Unlike potassium ions in potassium channels, the sodium ions in these channels appear to be hydrated and are associated with side chains of the selectivity filter residues, rather than polypeptide backbones.     

Receptors of the PAR Family as a Link between Blood Coagulation and Inflammation

Blood coagulation plays a key role among numerous mediating systems that are activated in inflammation. Receptors of the PAR family serve as sensors of serine proteinases of the blood clotting system in the target cells involved in inflammation.Activation of PAR-1 by thrombin and of PAR-2 by factor Xa leads to a rapid expression and exposure on the membrane of endothelial cells of both adhesive proteins that mediate an acute inflammatory reaction and of the tissue factor that initiates the blood coagulation cascade. Certain other receptors (EPR-1, thrombomodulin, etc.), which can modulate responses of the cells activated by proteinases through PAR receptors, are also involved in the association of coagulation and inflammation together with the receptors of the PAR family. The presence of PAR receptors on mast cells is responsible for their reactivity to thrombin and factor Xa and defines their contribution to the association of inflammation and blood clotting processes.