Cold and distant: structural features of the nucleoprotein complex of a cold-adapted influenza A virus strain.

Two influenza A nucleoprotein variants (wild-type: G102R; and mutant: G102R and E292G) were studied with regard to macro-molecular interactions in oligomeric form (24-mers). The E292G mutation has been previously shown to provide cold adaptation. Molecular dynamics simulations of these complexes and trajectory analysis showed that the most significant difference between the obtained models was distance between nucleoprotein complex strands. The isolated complexes of two ribonucleoprotein variants were characterized by transmission electron microscopy and differential scanning fluorimetry (DSF). Presence of the E292G substitution was shown by DSF to affect nucleoprotein complex melting temperature. In the filament interface peptide model, it was shown that the peptide corresponding in primary structure to the wild-type NP (SGYDFEREGYS) is prone to temperature-dependent self-association, unlike the peptide corresponding to E292G substitution (SGYDFGREGYS). It was also shown that the SGYDFEREGYS peptide is capable of interacting with a monomeric nucleoprotein (wild type); this interaction's equilibrium dissociation constant is five orders of magnitude lower than for the SGYDFGREGYS peptide. Using small-angle neutron scattering (SANS), the supramolecular structures of isolated complexes of these proteins were studied at temperatures of 15, 32, and 37 °C. SANS data show that the structures of the studied complexes at elevated temperature differ from the rod-like particle model and react differently to temperature changes. The data suggest that the mechanism behind cold adaptation with E292G is associated with a weakening of the interaction between strands of the ribonucleoprotein complex and, as a result, the appearance of inter-chain interface flexibility necessary for complex function at low temperature.Communicated by Ramaswamy H. Sarma.

The time scale of adaptation in tonal sequence processing by the mouse auditory midbrain neurons.

The time course of poststimulatory adaptation of the inferior colliculus central nucleus (ICC) of CBB6F1 hybrid mice to sound sequences, specifically, series of four tonal stimuli presented at intervals of 0, 2, 4, 10, 20, 50, 100, 200, 500, 700, 1000, and 1500 ms were studied. Assessment of the adaptation of the entire neuronal population have shown that, at an interstimulus interval of 0-200 ms, the response to the first tone in a series is significantly stronger than those to the second to fourth tones, the strengths of the latter three responses not differing significantly from one another. If the interstimulus interval is 500 ms or longer, the response to none of the tones in a series differs significantly in strength from the others. The role of adaptation of midbrain neurons to the grouping of components of bioacoustic stimuli is discussed.

[Biodegradation of Cellulose-Containing Substrates by Micromycetes Followed by Bioconversion into Biogas].

The ability of micromycetes Trichoderma viride and Aspergillus terreus to decompose the cellulose-containing substrates was studied. Office paper and cardboard, as well as a paper mixture, were found to be the most hydrolyzable. The cellulolytic activity of T. viride was 2-3 times higher than that of A. terreus; the highest values of 0.80 and 0.73 U/mLwere obtained from office paper and the paper mixture, respectively. The micromycete cultivation conditions (composition of culture medium, sucrose cosubstrate addition, seeding method) and the conditions of the fungus biomass treatment for its subsequent bioconversion into biogas by anaerobic microbial communities were optimized. It was shown that pretreatment improves the efficiency of biogas production from lignocellulosic materials under seeding with microbial community of bovine animal manure. After pretreatment of the Jerusalem artichoke phytomass (stems and leaves) and its subsequent bioconversion into biogas by methanogenic community, the biogas yield was increased by 1.5 times.

[VOCALIZATIONS OF SEX PARTNERS IN THE HOUSE MOUSE (MUS MUSCULUS)].

Acoustic parameters of the house mouse male and female vocalizations accompanying the sexual behavior were studied. The spectral-temporal analysis of female defensive call and male ultrasound call was carried out for adult house mice--hybrids of outbreed strains CBA and C57B1/6. The principal feature of the female defensive call is its harmonic structure formed by three--five main harmonics with the fundamental frequency about 3 kHz. The major energy of the signal is concentrated below 25 kHz. The basic harmonic structure could be modified by frequency and amplitude modulation or/and.noise. Call duration varied widely from 40 up to 470 ms with the average value of 180 ± 70 ins. The principal feature of male ultrasound vocalization is its low intensity and rareness of noise components. Depending on semantic load of the call, its fundamental frequency averaged 67.3 ± 8.5 or 45.6 ± 3.7 kHz. Male ultrasound vocalizations were shorter than female defensive calls and their duration did not exceed 220 ms. Key words: house mouse, acoustic structure of vocalizations, sexual behavior, sound and ultrasound vocalizations of rodents.

[Biogas production by microbial communities via decomposition of cellulose and food waste].

Several active microbial communities that form biogas via decomposition of cellulose and domestic food waste were identified among 24 samples isolated from different natural and anthropogenic sources. The methane yield was 90-260 ml CH4/g from microbial communities grown on cellulose substrates, office paper, and cardboard at 37 degrees C without preprocessing. Under mesophilic conditions, bioconversion of paper waste yields biogas with a methane content from 47 to 63%; however, the rate of biogas production was 1.5-2.0 times lower than under thermophilic conditions. When microbial communities were grown on DFW under thermophilic conditions, the most stable and effective of them produced 230-353 ml CH4/g, and the methane content in biogas was 54-58%. These results demonstrated the significance of our studies for the development of a technology for the biotransformation of paper waste into biogas and for the need of selection of microbial communities to improve the efficiency of the process.

[Phenotypic properties of Sulfobacillus thermotolerans: comparative aspects].

The phenotypic characteristics of the species Sulfobacillus thermotolerans Kr1(T), as dependent on the cultivation conditions, are described in detail. High growth rates (0.22-0.30 h(-1)) and high oxidative activity were recorded under optimum mixotrophic conditions at 40 degrees C on medium with inorganic (Fe(II), S(0), or pyrite-arsenopyrite concentrate) and organic (glucose and/or yeast extract) substrates. In cells grown under optimum conditions on medium with iron, hemes a, b, and, most probably, c were present, indicating the presence of the corresponding cytochromes. Peculiar extended structures in the form of cylindrical cords, never observed previously, were revealed; a mucous matrix, likely of polysaccharide nature, occurred around the cells. In the cells of sulfobacilli grown litho-, organo-, and mixotrophically at 40 degrees C, the enzymes of the three main pathways of carbon utilization and some enzymes of the TCA cycle were revealed. The enzyme activity was maximum under mixotrophic growth conditions. The growth rate in the regions of limiting temperatures (55 degrees C and 12-14 degrees C) decreased two- and tenfold, respectively; no activity of 6-phosphogluconate dehydrogenase, one of the key enzymes of the oxidative pentose phosphate pathway, could be revealed; and a decrease in the activity of almost all enzymes of glucose metabolism and of the TCA cycle was observed. The rate of 14CO2 fixation by cells under auto-, mixo-, and heterotrophic conditions constituted 31.8, 23.3, and 10.3 nmol/(h mg protein), respectively. The activities of RuBP carboxylase (it peaked during lithotrophic growth) and of carboxylases of heterotrophic carbon dioxide fixation were recorded. The physiological and biochemical peculiarities of the thermotolerant sulfobacillus are compared versus moderately thermophilic sulfobacilli.

[Effect of cultivation conditions on the growth and activities of sulfur metabolism enzymes and carboxylases of Sulfobacillus thermosulfidooxidans subsp. asporogenes strain 41]. / Vliianie uslovii kul'tivirovaniia na rost, aktivnost' fermentov metabolizma sery i karboksilaz u Sulfobacillus thermosulfidooxidans subsp. asporogenes, shtamm 41.

The moderately thermophilic acidophilic bacterium Sulfobacillus thermosulfidooxidans subsp. asporogenes strain 41 is capable of utilizing sulfides of gold-arsenic concentrate and elemental sulfur as a source of energy. The growth in the presence of S0 under auto- or mixotrophic conditions was less stable compared with the media containing iron monoxide. The enzymes involved in oxidation of sulfur inorganic compounds--thiosulfate-oxidizing enzyme, tetrathionate hydrolase, rhodonase, adenylyl sulfate reductase, sulfite oxidase, and sulfur oxygenase--were discovered in the cells of Sulfobacillus grown in the mineral medium containing 0.02% yeast extract and either sulfur or iron monoxide and thiosulfate. Cell-free extracts of the cultures grown in the medium with sulfur under auto- or mixotrophic conditions displayed activity of the key enzyme of the Calvin cycle--ribulose bisphosphate carboxylase--and several other enzymes involved in heterotrophic fixation of carbonic acid. Activities of carboxylases depended on the composition of cultivation media.

[Activity of the enzymes of carbon metabolism in Sulfobacillus sibiricus under various conditions of cultivation]. / Aktivnost' fermentov uglerodnogo obmena u Sulfobacillus sibiricus v razlichnykh usloviiakh kul'tivirovaniia.

The thermoacidophilic iron-oxidizing chemolithotroph Sulfobacillus sibiricus N1T is characterized by steady growth and amplified cell yield when grown in vigorously aerated medium containing Fe2+, glucose, and yeast extract as energy sources. In this case, carbon dioxide, glucose, and yeast extract are used as carbon sources. Glucose is assimilated through the fructose-bisphosphate pathway and the pentose-phosphate pathway. Glyoxylate bypass does not function in S. sibiricus, and the tricarboxylic acid cycle is disrupted at the level of 2-oxoglutarate dehydrogenase. The presence of ribulose-bisphosphate carboxylase indicates that carbon dioxide fixation proceeds through the Calvin cycle. The activity of ribulose-bisphosphate carboxylase is highest in autotrophically grown cells. The cells also contain pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxytransphosphorylase.

[The enzyme of carbon metabolism in the thermotolerant sulfobacillus strain K1]. / Fermenty metabolizma ugleroda u termotolerantnoi sul'fobatsilly, shtamm K1.

To determine enzymatic activities in the thermotolerant strain K1 (formerly "Sulfobacillus thermosulfidooxidans subsp. thermotolerans"), it was grown in a mineral medium with (1) thiosulfate and Fe2+ or pyrite (autotrophic conditions), (2) Fe2+, thiosulfate, and yeast extract or glucose (mixotrophic conditions), and (3) yeast extract (heterotrophic conditions). Cells grown mixo-, hetero-, and autotrophically were found to contain enzymes of the tricarboxylic acid (TCA) cycle, as well as malate synthase, an enzyme of the glyoxylate cycle. Cells grown organotrophically in a medium with yeast extract exhibited the activity of the key enzymes of the Embden-Meyerhof-Parnas and Entner-Doudoroff pathways. An increased content of carbon dioxide (up to 5 vol%) in the auto- and mixotrophic media enhanced the activity of the enzymes involved in the terminal reactions of the TCA cycle and the enzymes of the pentose phosphate pathway. Carbon dioxide was fixed in the Calvin cycle. The highest activity of ribulose bisphosphate carboxylase was detected in cells grown autotrophically at the atmospheric content of CO2 in the air used for aeration of the growth medium. The activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxytransphosphorylase decreased with the increasing content of CO2 in the medium.

[Carbon metabolism in Sulfobacillus thermosulfidooxidans subsp. asporogenes, strain 41]. / Metabolizm ugleroda u Sulfobacillus thermosulfidooxidans subsp. Asporogenes, shtamm 41.

The activities of carbon metabolism enzymes were determined in cellular extracts of the moderately thermophilic, chemolithotrophic, acidophilic bacterium Sulfobacillus thermosulfidooxidans subsp. asporogenes, strain 41, grown either at an atmospheric content of CO2 in the gas phase (autotrophically, heterotrophically, or mixotrophically) or autotrophically at a CO2 content increased to 5-10%. Regardless of the growth conditions, all TCA cycle enzymes (except for 2-oxoglutarate dehydrogenase), one glyoxylate cycle enzyme (malate synthase), and some carboxylases (ribulose bisphosphate carboxylase, pyruvate carboxylase, and phosphoenolpyruvate carboxylase) were detected in the cellular extracts of strain 41. During autotrophic cultivation of strains 41 and 1269, the increase in the CO2 content of the supplied air to 5-10% resulted in the activation of growth and iron oxidation, a 20-30% increase in the cellular content of protein, enhanced activity of the key TCA enzymes (citrate synthase and aconitase), and, in strain 41, a decrease in the activity of carboxylases.