Secretion of organic acids and bases by the kidneys of marine teleosts

In the experiments performed on kidneys of 5 species of marine Teleostei, morphological peculiarities in secretion of 8 fluorescent organic acids (uranin, primulin, tripaphlavin, erythrosin etc.) and in 5 organic bases (rhodamin C, auramin etc.) have been studied. At a very low concentration in the incubation medium--about 0.005 mg/ml--the substances mentioned penetrate into the epithelial cell of the canaliculus; its weak fluorescence appears, and soon they begin to be excreted in great amount through the apical part of the plasmolemma and accumulated in the canalicular lumen. All the substances studied accumulate in the cell and only some of them (uranin, primulin, titanic yellow, etc.) are secreted into the canalicular lumen. Penicillinum and probenecide inhibit penetration of the organic acids into the cell through the basal membrane. Uranin secretion into the canalicular lumen is inhibited in the presence of furocemid; amilorid, magnium and sulfate ions do not influence secretion of the organic acids. Secretion of the organic bases does not change when paraaminohippuric acid and furocemid are added to the medium, but it decreases when concentration of magnium ions increases.     

Etiologic role of bacteria of the genus Providencia in acute intestinal diseases

A study was made of morphological, cultural, biochemical properties and antigenic structure (by O-antigen) of 59 strains isolated in group acute intestinal affection of children at the pioneer camp. By the combination of biochemical properties (31 tests) all the cultures isolated were referred to Providencia alcalifaciens of biotype 7. Serological typing with the aid of experimental diagnostic agglutinating O-sera showed these strains to be referred to serological group O2. Identity of the O-antigen of the isolated cultures to the standard O2 strain was confirmed by the results of cross reactions of agglutinin absorption. The results of bacteriological and clinico-epidemiological studies offered a possibility of regarding the isolated Providencia alcalifaciens of serological group O2 as the causative agents of the group intestinal disease in children.     

Isolation of Tyr- mutants of facultative methylotrophic Pseudomonas sp. M

A method for isolation of Tyr- mutants of facultative methylotrophic bacteria Pseudomonas sp. M which possess two tyrosine synthesis pathways is presented. The method is based on the two-step blocking of the tyrosine synthesis: the first step of the supplementary pathway of synthesis from phenylalanine, the second being the main pathway from 4-hydroxyphenylpyruvate.     

Hypothalamo-amygdaloid connections of cat's brain]

Under study were the afferent connections of the cat's amygdala nuclei with the hypothalamus (Nauta's method) in parallel with studying geometrical parameters of the afferent fibre endings in these nuclei by the Golgi method. It has been shown that the medial hypothalamus gives the beginning to a small amount of fibres running to the medial group of the amygdala nuclei; dissipated solitary fibres run to the large- and small-cellular parts of the basal nucleus. A considerable amount of fibres run from the lateral hypothalamus to the amygdala, mainly to the medial group of its nuclei and the anterior amygdalar area, only solitary fibres were followed in the basal nuclei. We failed to observe degenerated fibres from the medial preoptical area to the amygdale. The geometry of branches of these fibre systems in the amygdala nuclei was established: they all terminate as a compact but rarely branching brush.     

Fragmentation of mitochondrial H+-ATPase hydrophobic complex]

The subunits with molecular weights of 30 000, 10 000 and 20 000 + 19 000 have been obtained by fractionation of the hydrophobic part of the oligomycin-sensitive ATPase complex on Sephadex G-200 and Sephadex G-150 in the presence of sodium dodecyl sulfate.     

Optimization of the medium for the yeast synthesis of biotin

In order to increase the yield of biotin produced by the culture Sporobolomyces pararoseus, the medium containing sucrose, asparagine, MgSO4 (NH4)2SO4, KH2PO4, vitamin complex and trace elements was optimized. With the aid of a fractional factor experiment (2(5-1)) and a complete factor experiment (2(4)), the proportion of constituents was chosen in such a way as to double biotin yield, i.e. to increase it to 55.25 micrograms/l. An enrichment of the medium with yeast autolysate, casein hydrolysate and peptone in the presence of adenine increased biotin yield to 105.7 micrograms/l and cell productivity from 6.1 to 8.0 micrograms/l dry biomass.     

NAD-dependent formate dehydrogenase from methylotrophic bacteria. Isolation and properties]

NAD-Dependent formate dehydrogenase (FDH) has been isolated from methylotrophyc strain Bacterium sp 1 by (NH4)2SO4 fractionation of cell extract, ion-exchange chromatography and preparative isotachophoresis. Preparation of FDH is homogeneous in analytical polyacrylamide gel electrophoresis and under ultracentrifugation. Sedimentation coefficient of FDH is 4.9S. Mikhaelis constants are 1.1-10(-4) M for NAD and 1.5-10(-2) M for formate. In the absence of sulfhydril compounds FDH is unstable, but it is stable in the presence of mercaptoethanol or ditiotreitol.