Immunoelectrophoresis analysis of the antigenic composition of E. coli K12 hybrids which acquired the serological specificity of S. newcastle and S. flexneri

Genetic and immunoelectrophoretic studies confirm earlier data on the presence of 2 specific antigens of acidic nature in S. newcastle; one of them is a specific thermolabile K-antigen responsible for type IV specificity of these bacteria. The data concerning the differences in the genetic determinants controlling the synthesis of O- and K-antigens in S. newcastle have been obtained. S. newcastle O- and K-antigens did not react with S. flexneri in the group serum system 3, 4, which indicates that S. newcastle are serologically isolated and form a separate taxonomic group of dysentery bacteria. The existence of cross reactions between S. flexneri and S. newcastle due to the presence of neutral R-core antigens common to these 2 species has been shown . Immunoelectrophoresis in agar is the most promising and informative method in genetic and chemical studies of the antigenic structure of bacteria.     

Seasonal peculiarities of thyroxine influence on the way of serotonin metabolism in the pineal gland of the rat

In intact Wistar pubertal male rats held on LD 8:16 (winter) and 16:8 (summer) pineal melatonin (M) production and other pineal indoles content serotonin (S), 5-methoxytriptamine (5-MT), N-acetylserotonin (N-aS), 5-hydroxyindoleacetic acid (5-HIAA) and 5-methoxyindoleacetic acid (5-MIAA) were investigated in basic conditions and after 10-days T4 administration. The results suggest, that intact control in winter comparing with summer demonstrates high M, N-aS, 5-HIAA and 5-MIAA level, but low 5-MT concentrations, S level was not changed. T4 administration in winter produced a pronounced augmentation of all parameters (excluding serotonin), in summer M production not only increased, but appears to be dependent on the active metabolism of his precursors (S, 5-MT, N-aS). The experimental data favour more profound comprehension to the mechanisms of pineal activity regulation.     

A histochemical method for detecting xanthine oxidase activity in the liver

A histochemical method is described for localizing xanthine oxidase--the key enzyme in the purine catabolic pathway. The above method is based on the reduction of p-Nitroblue tetrazolium during hypoxanthine enzymatic oxidation, phenazine methosulfate being an intermediate electron acceptor. The patterns of the reaction product distribution suggest that the Kupffer cells and the sinusoidal endothelium possess the highest xanthine oxidase activity.     

A comparative evaluation of alcoholic motivation in animals by 2 behavioral methods]

The attitude of outbred white male rats to alcohol was determined by means of two behavioural methods--the method of free choice of alcohol or water and of reaction of preference of place (PP) connected with taking of alcohol. Conclusion is made about greater adequacy of PP application for determination of alcohol motivation in animals.     

Effect on the fertility of female Drosophila of sterol metabolism in an ecological-genetic yeast-Drosophila system

The consequences of sterol deficiency in feeding of adult Drosophila females have been studied. Feeding of Drosophila on nys 1 mutant strain yeast leads to significant increase of non-developed eggs in Drosophila females. The effect of sterol deficiency on oogenesis in virgin and fertilized females has been estimated using different regimens of feeding. Possible mechanisms of arising of fertility defects are discussed.     

白细胞介素－2中枢镇痛作用途径的探讨

抗ＩＬ－２受体α亚基的单克隆抗体不能阻断ＩＬ－２的中枢镇痛作用,以及丧失与ＩＬ－２受体β亚基结合能力的ＩＬ－２突变体仍具有提高大鼠痛阈的能力,这表明ＩＬ－２的中枢镇痛作用并不是通过ＩＬ－２受体所介导,亦表示ＩＬ－２的免疫和镇痛作用是通过不同的受体途径实现的。加之内源性阿片肽与ＩＬ－２分子有着共同的抗原决定基和结构相似性,提示ＩＬ－２可以与阿片受体直接结合产生中枢镇痛效应。从放射免疫法测定的ＩＬ－２侧脑室注射后不同时间大鼠脑内不同核团的内源性阿片肽含量,推测ＩＬ－２的中枢镇痛作用可能还与弓状核、室旁核、蓝斑等核团的β－ＥＰ和ＬＥＫ有关。     

Autotrophic picoplankton in southern Lake Baikal: abundance, growth and grazing mortality during summer

Autotrophic picoplankton were highly abundant during the thermalstratification period in late July in the pelagic area (waterdepth 500–1300 m) of southern Lake Baikal; maximum numberswere 2 x 10⁶ cells ml^–1 in the euphotic zone ({small tilde}15m). Unicellular cyanobacteria generally dominated the picoplanktoncommunity, although unidentified picoplankton that fluorescedred under blue excitation were also abundant (maximum numbers4 x 10⁵ cells ml^–1) and contributed up to {small tilde}40%of the total autotrophic picoplankton on occasions. Carbon andnitrogen biomasses of autotrophic picoplankton estimated byconversion from biovolumes were 14–84 µg C l^–1and 3.6–21 µg N l^–1. These were comparableto or exceeded the biomass of heterotrophic bacteria. Autotropicpicoplankton and bacteria accounted for as much as 33% of paniculateorganic carbon and 81% of nitrogen in the euphotic zone. Measurementsof the photosynthetic uptake of [^l4C]bicarbonate and the growthof picoplankton in diluted or size-fractionated waters revealedthat 80% of total primary production was due to picoplankton,and that much of this production was consumed by grazers inthe <20 µ.m cell-size category. These results suggestthat picoplankton-protozoan trophic coupling is important inthe pelagic food web and biogeochemical cycling of Lake Baikalduring summer.