cDNA cloning of a developmentally regulated hemocyanin subunit in the crustacean Cancer magister and phylogenetic analysis of the hemocyanin gene family

The complete cDNA sequence and protein reading frame of a developmentally regulated hemocyanin subunit in the Dungeness crab (Cancer magister) is presented. The protein sequence is aligned with 18 potentially homologous hemocyanin-type proteins displaying apparent sequence similarities. Functional domains are identified, and a comparison of predicted hydrophilicities, surface probabilities, and regional backbone flexibilities provides evidence for a remarkable degree of structural conservation among the proteins surveyed. Parsimony analysis of the protein sequence alignment identifies four monophyletic groups on the arthropodan branch of the hemocyanin gene tree: crustacean hemocyanins, insect hexamerins, chelicerate hemocyanins, and arthropodan prophenoloxidases. They form a monophyletic group relative to molluscan hemocyanins and nonarthropodan tyrosinases. Arthropodan prophenoloxidases, although functionally similar to tyrosinases, appear to belong to the arthropodan hexamer- type hemolymph proteins as opposed to molluscan hemocyanins and tyrosinases.      

Specific features of taxonomic organization of cyanobacterial–algal flora in extreme habitats as reflection of different sucfcession models

We have revealed 75 species (78 species and intraspecies taxa) of algae and cyanobacteria that first colonized the substrates in different regions of Russia (Yano-Oimyakon Upland in the eastern part of Asian Russia and Western Siberia). An analysis of the data shows that the development of substrates (rocks and sandy ground) differs. They may be considered specific natural models of the development of autogenic lithoand psammosuccessions.     

Effects of anoxia and inhibitors of energy metabolism on potassium and sodium homeostasis in neurons of gastropod mollusk

The effect of anoxia and inhibitors of energy metabolism on intracellular concentrations of potassium and sodium, membrane potentials, permeability, active and passive ouabain-sensitive transport of potassium (determined with⁸⁶Rb) was studied in neurons of the freshwater planorbis mollusk (Planorbarius corneus). X-ray microanalysis showed that incubation of isolated ganglia in oxygen-free medium induced no change in intracellular concentrations of potassium and sodium. In the presence of cyanide, absorption of oxygen by the ganglia ceased, but accumulation of⁸⁶Rb decreased insignificantly. The membrane potential and permeability did not depend on addition of cyanide. Desoxyglucose, an inhibitor of glycolysis, decreased⁸⁶Rb accumulation more than cyanide did. In the presence of inhibitors of both glycolysis and respiration, which excluded the possibility of mutual compensation of oxidation and glycolytic sources of energy supply,⁸⁶Rb accumulation decreased to the highest degree. A hypothesis was formulated on the paramount importance of glycolytic ATP for maintaining ion homeostasis of the nerve cells. The problem of functionally facilitated compartmentation of intracellular energy sources is discussed.Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 23, No. 3, pp. 313–321, May–June, 1991.     

Influence of the unified state examination on the functional state in high school students

The results of a local comparative experiment are presented in the course of which physiological reactions to emotional and mental stress related to the situation of taking an examination in two forms—a traditional examination and the unified state examination (USE)—were compared. It was shown that the physiological stress during the USE is slightly higher than during the traditional examination.     

Diversity of the communities of acidophilic chemolithotrophic microorganisms in natural and technogenic ecosystems

The main representatives of acidophilic chemolithotrophs oxidizing sulfide minerals, ferrous iron, elemental sulfur, and reduced sulfur compounds and forming microbial communities in the natural and technogenic ecosystems with low pH values and high concentrations of heavy metal ions are listed. The species and strain diversity of the communities and environmental factors affecting their composition (temperature, pH value, energy substrate, mineralogical composition of sulfide ore concentrates, the presence of organic substances, and level of aeration) are analyzed. Involvement of mobile genetic elements (IS elements and plasmids) in the structural changes of the chromosomal DNA in the course of switching microbial metabolism to the oxidation of new energy substrates or under increased concentrations of metal ions is shown to be a probable mechanism responsible for the intraspecific genetic heterogeneity of the populations. Importance of determination of the dominant strains of different microbial species in the communities and of their physiological peculiarities for stabilization, optimization, and enhancement of efficiency of biotechnological processes for sulfide mineral oxidation is stressed.