Ecology of diapausing copepodids of Cyclops kolensis Lill. in reservoirs of the Upper Volga

Cyclops kolensis Lill. forms dense populations in different water-bodies of the Upper Volga basin. In spring, when the other planktonic crustaceans have not yet appeared, C. kolensis is an important food object for fishes. Its active reproduction occurs from April to the beginning of June. A rapid accumulation of stage IV copepodids in the plankton occurs in June and at 12–14° they sink into the pelogene in a diapause stage. During the summer stagnation period the diapausing copepodids are distributed evenly over the bottom; their abundance here is 0.7–0.8 million ind. m^-2 (Rybinsk reservoir). During storms and autumn active water mixing the copepodids together with detritus are disturbed and brought to the deepest, silt rich, part of the water-bodies. After the ice formation and at the beginning of bottom heating the diapausing copepodids are transported by near bottom currents and are concentrated in depressions; their biomass here reaches 60 g m^-3. After the thermo-oxy-cline formation they revive and begin to live actively. Copepodids feed, accumulate adipose matter and in February–March they begin to moult.     

Predictive Dynamics of Human Pain Perception

While the static magnitude of thermal pain perception has been shown to follow a power-law function of the temperature, its dynamical features have been largely overlooked. Due to the slow temporal experience of pain, multiple studies now show that the time evolution of its magnitude can be captured with continuous online ratings. Here we use such ratings to model quantitatively the temporal dynamics of thermal pain perception. We show that a differential equation captures the details of the temporal evolution in pain ratings in individual subjects for different stimulus pattern complexities, and also demonstrates strong predictive power to infer pain ratings, including readouts based only on brain functional images.     

Oxidative damage and antioxidant defense system in leaves of Vicia faba major L. cv. Bartom during soil flooding and subsequent drainage

The adaptive reactions of Vicia faba major L. cv. Bartom to 13-27 days soil flooding and to 14 days of drainage following 13-days of soil flooding were studied. Under flooding, oxygen diffusion rate (ODR) in the root zone decreased from 2.28–3.44 to 0.09–0.28?µmol O₂ m^?2 s^?1; the soil redox potential (Eh) decreased from 543 to 70 mV. Upon drainage of flooded soil the ODR and Eh values returned to the control levels. Oxidative damage and defense systems in leaves were assessed by the concentration of thiobarbituric acid reactive substances (TBARs) and by the activities of superoxide dismutase (SOD) and glutathione reductase (GR). Two stages of stress development are described. During the first stage (1–13 days) shoot dry mass did not decrease, the TBARs concentration and SOD activity increased, the GR activity decreased. The second stage (13–27 days) was characterized by a decrease in the TBARs concentration, SOD and GR activities, pigment concentrations and shoot dry mass. Drainage of flooded soil resulted in elevated concentrations of TBARs and also increased the activities of SOD and GR. Increased SOD activity in the first stage of hypoxic stress development and activations of SOD and GR at oxygen re-entry to soil are responsible for tolerance of Vicia faba to hypoxic and post hypoxic stress associated with soil flooding and subsequent drainage.     

Elongation factor Tu can reduce translation errors in poly(U)-directed cell-free systems

Rates of incorporation of [³H]phenylalanine and [¹⁴C]leucine from the aminoacylated transfer-RNA into polypeptides synthesized on poly(U) programmed Escherichia coli ribosomes have been determined in cell-free translation systems containing either elongation factors Tu and G with GTP, or just elongation factor Tu or G with GTP, or none of the elongation factors. The presence of elongation factor Tu with GTP has been shown to reduce the leucine to phenylalanine ratio in the product at relatively low concentrations of Mg²⁺. This error-reducing effect of elongation factor Tu has not been observed at high concentrations of Mg²⁺, although the factor still contributed to the speed of elongation. The results are discussed in terms of the kinetic proof-reading mechanism proposed by Hopfield (1974).     

FliO Regulation of FliP in the Formation of the Salmonella enterica Flagellum

The type III secretion system of the Salmonella flagellum consists of 6 integral membrane proteins: FlhA, FlhB, FliO, FliP, FliQ, and FliR. However, in some other type III secretion systems, a homologue of FliO is apparently absent, suggesting it has a specialized role. Deleting the fliO gene from the chromosome of a motile strain of Salmonella resulted in a drastic decrease of motility. Incubation of the ΔfliO mutant strain in motility agar, gave rise to pseudorevertants containing extragenic bypass mutations in FliP at positions R143H or F190L. Using membrane topology prediction programs, and alkaline phosphatase or GFPuv chimeric protein fusions into the FliO protein, we demonstrated that FliO is bitopic with its N-terminus in the periplasm and C-terminus in the cytoplasm. Truncation analysis of FliO demonstrated that overexpression of FliO_43–125 or FliO_1–95 was able to rescue motility of the ΔfliO mutant. Further, residue leucine 91 in the cytoplasmic domain was identified to be important for function. Based on secondary structure prediction, the cytoplasmic domain, FliO_43–125, should contain beta-structure and alpha-helices. FliO_43–125-Ala was purified and studied using circular dichroism spectroscopy; however, this domain was disordered, and its structure was a mixture of beta-sheet and random coil. Coexpression of full-length FliO with FliP increased expression levels of FliP, but coexpression with the cytoplasmic domain of FliO did not enhance FliP expression levels. Overexpression of the cytoplasmic domain of FliO further rescued motility of strains deleted for the fliO gene expressing bypass mutations in FliP. These results suggest FliO maintains FliP stability through transmembrane domain interaction. The results also demonstrate that the cytoplasmic domain of FliO has functionality, and it presumably becomes structured while interacting with its binding partners.     

Non-linear effects of macromolecular crowding on enzymatic activity of multi-copper oxidase

Enzymes catalyze biochemical reactions in highly crowded environments where the amount of macromolecules may occupy up to 40% of the volume. Here we report how cell-like conditions tune catalytic parameters for the monomeric multi-copper oxidase, Saccharomyces cerevisiae Fet3p, in vitro. At low amounts of crowding agent, we detect increases in both of K_M (weaker substrate binding) and k_cat (improved catalytic efficiency), whereas at higher crowding levels, both parameters were reduced. Presence of crowding agents does not affect Fet3p structural content but increases thermal resistance. The observations are compatible with ordering of a non-optimal substrate-binding site and restricted internal dynamics as a result of excluded volume effects making the protein less structurally ‘strained’.     

Development of glial cells cultured from prenatally alcohol treated rat brain: Effect of supplementation of the maternal alcohol diet with a grape extract

The aim of this work was to investigate the effect of supplementation of a maternal alcohol diet with a grape extract on glial cell development. Glial cells were cultured during 4 weeks from cortical brain cells of the new born offspring in DMEM medium supplemented with fetal calf serum. Enzymatic markers of nerve cell development were measured (enolase isoenzymes and glutamine synthetase). Since alcohol consumption produces free radicals the antioxidant system superoxide dismutase was also investigated. Compared to the decrease found in only alcohol treated animals, all parameters except neuron-specific enolase were antagonized and even stimulated after grape extract supplementation. The effect was more important after only 1 month than 3 months of treatment. Also in the total brain an alcohol antagonizing effect and a glutamine synthetase activation were found. Our data demonstrate that addition of a grape extract to the maternal alcohol diet may partially or completely overcome the alcohol induced retardation of glial cell development.     

The Culture-Transmission Motive in Immigrants: A World-Wide Internet Survey

A world-wide internet survey was conducted to test central assumptions of a recent theory of cultural transmission in minorities proposed by the authors. 844 1^st to 2^nd generation immigrants from a wide variety of countries recruited on a microjob platform completed a questionnaire designed to test eight hypotheses derived from the theory. Support was obtained for all hypotheses. In particular, evidence was obtained for the continued presence, in the immigrants, of the culture-transmission motive postulated by the theory: the desire to maintain the culture of origin and transmit it to the next generation. Support was also obtained for the hypothesized anchoring of the culture-transmission motive in more basic motives fulfilled by cultural groups, the relative intra- and intergenerational stability of the culture-transmission motive, and its motivating effects for action tendencies and desires that support cultural transmission under the difficult conditions of migration. Furthermore, the findings suggest that the assumption that people have a culture-transmission motive belongs to the folk psychology of sociocultural groups, and that immigrants regard the fulfillment of this desire as a moral right.