EFFECTS OF HUMAN ACTIVITIES ON STRUCTURE AND COMPOSITION OF WOODY SPECIES OF THE NOKREK BIOSPHERE RESERVE OF MEGHALAYA,NORTHEAST INDIA

Aims Our study was conducted in the Nokrek Biosphere Reserve (NBR) in the Garo hills districts of Meghalaya, Northeast India. Our aim was to assess the effects of human activities on plant diversity,population structure and regeneration.Methods We selected a representative 1.2 hm2 stand in both the core and buffer zones of NBR. Structure and composition were determined by randomly sampling square quadrats, population structure was assessed by determining age structure, and regeneration was assessed by measuring densities of seedling, sapling and adult trees.Important findings More woody species were recorded from the core zone than the buffer zone (87 vs. 81 species), and there were a large number of tropical, temperate, and Sino-Himalayan, Burma-Malaysian and Malayan elements, primitive families and primitive genera. The trees were distributed in three distinct strata,canopy, subcanopy and sapling. Subcanopy and sapling layers had the highest species richness (81％ -88％ ). Lauraceae and Euphorbiaceae were the dominant families in terms of the number of species, and a large number of families were represented by single species. Most woody species (57 ％ - 79 ％ ) were contagiously distributed and had low frequency ( ＜ 20％ ). Although stand density was high in the buffer zone, its basal area was low compared to the stand in the core zone. Low similarity and high β-diversity indicate marked differences in species composition of the stands. Shannon diversity index was high in both the stands, while Simpson dominance index was low. The diameter-class distribution for dominant species revealed that the most had a large number of young individuals in their populations. Preponderance of tree seedlings, followed by a steep decline in population density of saplings and adult trees, indicated that the seedling to sapling stage was the most critical in the life cycle of the tree populations. Most species (42 ％ - 48 ％ ) had no regeneration,25 ％ - 35 ％ had good/fair regeneration, and the rest had poor regeneration or reoccurred as immigrants.     

The experiment “initial stages of biological damage and deterioration in space”

A study of the microflora of structural surfaces on board the russian segment of the international space station (RS ISS) has demonstrated that the species composition that is formed during the mission is similar to that on board the mir station. the microflora of the sampled sites was similar to that of residential and industrial buildings on earth. it was represented by 17 species of fungi, seven genera of bacteria, and three genera of actinomycetes. the degree of colonization of the surfaces of structural materials of the rs iss by destructive microorganisms was low and showed undulating dynamics. the mycelial fungi included “technophile” species, which caused biological corrosion of an aluminum-magnesium alloy in simulation experiments.     

Appearance and Differentiation of NADPH-D-Neurons in Ontogeny of Cerebral Cortex in Rats

The appearance of presumptive NO-ergic nerve cells and their differentiation in the rat neocortex were studied. For this purpose, a comparative analysis of the development and differentiation of NADPH-D-positive neurons in the neocortex transplants taken from the embryos of different ages and transplanted in the occipital cortex of adult rats and in the normally developing cerebral cortex was undertaken. The nervous tissue was stained histochemically for NADPH-D. The results we obtained suggest that no NADPH-D-containing neurons were found in the transplants from 15-day embryos, while they developed in those from 18-day embryos. Hence, precursors of NO-ergic neurons were still absent in the presumptive neocortex of 15-day embryos and appeared only on day 16–18 of embryogenesis. Expression of NADPH-D begins in them only within four to five days, but the neurons are differentiated during a relatively short period of time. Most NADPH-D-positive neurons reach their structural–functional maturity already by the end of the first week of postnatal development, while their complete maturation takes place by the end of the second week of postnatal development.     

Isolation and analysis of Ca/Mg-dependent endonuclease from cell nuclei of human splenocytes

A scheme for the isolation of Ca,Mg-dependent endonuclease from human spleen lymphocyte nuclei has been developed. The isolation procedure resulted in protein preparations (Mr = 57 kD) possessing an enzymatic activity and stable upon storage for over a period of one year. The enzyme is an endonuclease which predominantly cleaves double-stranded DNA by a mixed single- and double-hit mechanism with the formation of 5'-phosphate and 3'-OH terminal groups. Its maximal activation is induced by Ca2+ plus Mg2+. The enzyme is also active in the presence of Mn2+, Ca2+, Mg2+ and Zn2+ and is inhibited by Co2+. NaCl and KCl (0.15-0.2 M) and p-chloromercuribenzoate (1 mM) also inhibit the enzyme. ATP has no activating effect.     

New informative index of the functional status of polymorphonuclear neutrophils

A new test was applied to study the function of polymorphonuclear neutrophils according to their ability to form oreols in a hypertonic medium. During inhibition of neutrophil function in vivo (desympathetization, tumor growth), oreol formation increased. Stimulation of neutrophils in vitro by adding noradrenaline to the incubation medium led to a decrease in their oreol-forming ability. The data obtained enabled the authors to offer the test for detecting the functional activity of polynuclear cells.     

Liver microsomal lipids of mice irradiated and administered an extract of turtle spleen

The influence of a tortoise spleen extract (TSE) on lipids of liver endoplasmic reticulum of irradiated (8 Gy) mice has been studied. The administration of TSE immediately after irradiation changes the content of lipid fractions in microsomal membranes preventing the accretion of cholesterol, nonesterified fatty acids, and triacylglycerol. The preparation under study exerts an antioxidant effect.     

Immunization with a synthetic fragment 155–164 of neurotrophin receptor p75 prevents memory loss and decreases beta-amyloid level in mice with experimentally induced Alzheimer’s disease

Neurotoxic beta-amyloid peptide plays an important role in the pathology of Alzheimer’s disease. In aggregated form it binds to several proteins on the surface of the brain cells leading to their death. p75 receptor involved in supporting of cell balance is one of the targets for toxic beta-amyloid. We proposed that induction of antibodies against potential binding sites of p75 with beta-amyloid can be a promising approach towards development of new anti-Alzheimer’s disease treatment. Four potentially immunoactive fragments of p75 were chosen and chemically synthesized. Investigation of immunoprotective effect of the peptide fragments carried out in mice with experimentally induced form of Alzheimer’s disease helped to reveal two fragments effectively preserving murine memory from impairment. Results obtained by ELISA biochemical analysis showed that only immunization with fragment p75 155–164 led to significant decrease in beta-amyloid level in the brain of the experimental mice. Thus, immunization with both fragments of p75 receptor pro-vides a new insight into anti-Alzheimer’s disease drug design.