Search for genetic markers of climatic adaptation in populations of North Eurasia

Genetic diversity of native populations of North Eurasia is investigated using a panel of genetic markers of candidate genes for cold climate adaptation. A high level of within- and between-population variability is detected. Comparative analysis of data on North Eurasian populations combined with data on worldwide populations from the 1000 Genomes and HDGP projects reveals correlations of genetic diversity in candidate genes for cold climate adaptation with key climate parameters, as well as the increase of genetic diversity in markers of this group of genes with the increase of latitude, that is, as modern humans migrated out of Africa. Using the method of searching for extreme empirical values of the coefficient of genetic diversity, signals of directional selection for markers of six genes adaptive to cold (MYOF, LONP2, IFNL4, MKL1, SLC2A12, and CPT1A) are found. The data are discussed in framework of the hypothesis of decanalization of genome–phenome relationships under the pressure of natural selection during human settlement throughout the world.     

Sex differences in aging,life span and spontaneous tumorigenesis in 129/Sv mice neonatally exposed to metformin

The perinatal (prenatal and early neonatal) period is a critical stage for hypothalamic programming of sexual differentiation as well as for the development of energy and metabolic homeostasis. We hypothesized that neonatal treatment with antidiabetic drug biguanide metformin would positively modify regulation of growth hormone – IGF-1 – insulin signaling pathway slowing down aging and improving cancer preventive patterns in rodents. To test this hypothesis male and female 129/Sv mice were s.c. injected with metformin (100 mg/kg) at the 3rd, 5th and 7th days after birth. Metformin-treated males consumed less food and water and their body weight was decreased as compared with control mice practically over their entire lifespan. There were no significant differences in age-related dynamics of food and water consumption in females and they were heavier than controls. The fraction of mice with regular estrous cycles decreased with age and demonstrated a tendency to decrease in the females neonatally treated with metformin. Neonatal exposure to metformin practically failed to change the extent of hormonal and metabolic parameters in blood serum of male and female mice. In males, neonatal metformin treatment significantly increased the mean life span (+20%, P < 0.05) and slightly increased the maximum life span (+3.5%). In females, the mean life span and median in metformin-treated groups were slightly decreased (−9.1% and −13.8% respectively, P > 0.05) in comparison to controls, whereas mean life span of last 10% survivors and maximum life span were the same as in controls. Almost half (45%) of control male mice and 71.8% male mice neonatally exposed to metformin survived up to 800 d of age, the same age was achieved by 54.3% of mice in control female group and 30% of metformin-treated females (P < 0.03). Thus, neonatal metformin exposure slows down aging and prolongs lifespan in male but not in female mice.     

Effects of phosphocreatine on the heart nerve structures under conditions of local immune impairment (electrophysiological and neurochemical aspects)

Effects of phosphocreatine on the neurohumoral mechanisms controlling the heart under conditions of a local immune injury were studied in acute experiments on anesthetized dogs using electrophysiological, biochemical, and electron microscopy techniques. After the development of heart injury, cardiogenic depressor reflexes evoked by an intracoronary injection of veratrine and mediated by vagus mechanisms disappeared, while pressor reflexes became dominating. This phenomenon correlated with an increase in concentration of a vasoconstrictor agent, leucotriene LTC₄, in the blood and with a considerable ultrastructural impairment of nerve terminals in the myocardium. Preliminary injection of phosphocreatine prevented the development of structural impairments, favored the preservation of vagosympathetic depressor reflex, and not only prevented the increase in LTC₄ concentration, but even dramatically decreased its level (by 82%, as compared with the initial level). We concluded that complex protective effect of phosphocreatine provides structural and functional preservation of the receptor apparatus in the heart and can play a considerable role in normalization of neurohumoral mechanisms controlling the heart under conditions of pathological impairment.Neirofiziologiya/Neurophysiology, Vol. 27, No. 2, pp. 140–146, March–April, 1995.     

Genetic identification and genomic organization of factors affecting fruit texture

Fleshy fruits are an essential part of the human diet providing vital vitamins, minerals and other health-promoting compounds. The texture of the ripe fruit has a significant effect on quality and influences consumer acceptance, shelf-life, resistance, and transportability. The development of rational approaches to improve texture and shelf-life depend on understanding the biological basis of fruit ripening. Until recently, work has focused on the isolation of ripening-related genes from a variety of fleshy fruits. However, little is known about the genes that regulate this complex developmental process or whether similar regulatory genes are active in all fruiting species. A major breakthrough would be the identification of generic genes associated with texture and other aspects of ripening in fleshy fruits. In tomato, a small number of single gene mutations exist, such as ripening-inhibitor (rin), non-ripening (nor), Never-ripe (Nr), and Colourless non-ripening (Cnr) which have pleiotropic effects resulting in the reduction or almost complete abolition of ripening. These mutations probably represent lesions in regulatory genes. The cloning of the wild-type alleles of RIN and NOR is reported by Moore et al. in this issue. This review focuses on the texture characteristics of the Cnr mutant. A possible framework for the molecular regulation of fruit texture is discussed and quantitative genetic approaches to determining the generic attributes of fruit texture are explored.     

Distribution and morphologic characteristics of lymphoid cells in the canine popliteal lymph nodes in their normal state and under antigen effect

By means of morphometry, light and electron microscopy methods peculiarities in distribution of small, middle and large lymphocytes, as well as plasmocytes in various zones of the popliteal lymph nodes have been studied in normal and in dynamics up to one year after subcutaneous injection of BCG vaccine into the left hind paw. The antigen produces certain changes in density and morphological parameters of lymphoid cells both in the regional and in the contralateral lymph nodes. For them 3 periods are specific. During the first 3 days they are not antigen-dependent (stipulated by the stress reaction), during 7-24 days antigen-dependent processes of proliferation and differentiation of lymphocytes get into action. In 3 months a new wave of the immune response is observed.     

Nerve regeneration after correction of its defect with a vascularized autologous nerve transplant

In chronic experiment performed on 6 dogs, by means of some neurohistological techniques peculiarities of regeneration of nerves have been studied, when their defects are substituted for vascularized and common autoneurotransplants. When the vascularized autoneurotransplants are applied, more favourable conditions are made for the nerve regeneration, than at a free plastisity and amount of regenerated fibers distal to the graft reaches 34-88%, more often making 48-52% of the initial number of fibers in the proximal parts of the nerves in 3 months after the operation. When in the same animals in the contralateral side common autoneurotransplants have been applied, during the same time the amount of fibers regenerated into the peripheral parts of the nerves makes 10-26%, more often 17-20% from the initial level, or in 2-2.5 times less than at substitution of the defects for the vascularized grafts. Absence of an active cellular reaction of the surrounding tissues to the sutural material supramid is used.