Mechanisms of induced processes in aqueous hemoglobin solutions at 77 K

ESR spectra of gamma-irradiated and frozen at 77 K human oxyhemoglobin and partially denaturated methemoglobin solutions were analysed. The quartet signal ascribed to the anion-radical of proximal histidine was shown to dominate in the spectra of both solutions. The spectra of methemoglobin solution irradiated with relatively small doses have an intensive singlet ascribed to the stabilized electron. The formation mechanism of free radicals is discussed.     

EFFECTS OF LEUCINE ON BRAIN SEROTONIN

Abstract— The effect of excess leucine in the diet on serotonin metabolism in the brain was investigated in experimental animals. It was found that:
(1) Animals receiving diets containing 3 % and 8 % leucine and those receiving jowar diets had significantly lower levels of serotonin in the brain.
(2) Intraperitoneal administration of the precursor amino acid 5-HTP increased the serotonin concentration in brain in both control and leucine-fed animals. However, the serotonin concentration in leucine-fed animals was significantly lower than that of pairfed controls. Larger amounts of the synthesized serotonin were found to be catabolized in 3 hr in leucine-fed animals than in control animals.
(3) The in vitro uptake of [¹⁴C]5-HTP by brain slices of animals fed leucine was found to be similar to that of control animals.
(4) The basal concentration of 5-HIAA in brain was higher in leucine-fed animals, suggesting a higher rate of catabolism of serotonin.
(5) Administration of nicotinic acid resulted in a further fall of serotonin concentration in the brains of leucine-fed animals but not in control animals.     

A climate for contemporary evolution

A new study of divergence in freshwater fish provides strong evidence of rapid, temperature-mediated adaptation. This study is particularly important in the ongoing debate over the extent and significance of evolutionary response to climate change because divergence has occurred in relatively few generations in spite of ongoing gene flow and in the aftermath of a significant genetic bottleneck, factors that have previously been considered obstacles to evolution. Climate change may thus be more likely to foster contemporary evolutionary responses than has been anticipated, and I argue here for the importance of investigating their possible occurrence.     

Genetic and morphological variation in a partially isolated population of Caucasian shrew <Emphasis Type="Italic">Sorex satunini</Emphasis> (Mammalia)

Morphological and genetic variation at microsatellite loci of Caucasian shrew Sorex satunini Ogn. is examined and compared with that of the common shrew S. araneus L. Genetic distance at microsatellite loci between the common shrew and Caucasian shrew proved to be threefold higher than between chromosome races of the common shrew. The Caucasian shrew manifested low polymorphism in studies of both microsatellites and morphometric mandibular traits. The heterozygote deficit was also typical. These properties may be a consequence of partial isolation of the population and gene drift.     

Passive and active reactions of embryonic tissues to the action of dosed mechanical forces

With the help of a suction manometric device, the relation between the deformation of Xenonus laevis embryo at the gastrula and neurula stages and the value of the applied force has been studied. Stiffness modules of embryonic tissues were in the order of several dozens of Pascal and they were inversely proportional during deformation from 40 to 20%. At the gastrula stage, a uniform or an increasing rate of expansion of the embryo body in the suction capillary with the diameter of approximately half that of the embryo was observed for 30 min after the action of the suction forces. The length of the stretched portion of the embryo correlates with the value of its deformation at the first minute. As a result of the expansion, the total body surface area of the deformed embryo increases more than twice compared to intact embryos. After expelling the embryo from the capillary, its surface reduced and the deformation became smoothened within 5 min, which indicates the existence of tensional force in the expanded embryo. These data confirm that, at the embryo gastrula stage, external mechanical forces do not only passively deform the embryo but also initiate the active expansion of the embryo which takes place at zero external force and overcomes the tensional resistance of tissues. The mechanism of active expansion and its link with the processes of normal morphogenesis are discussed.