Partial characterization of an extracellular polysaccharide produced by the moderately halophilic bacterium Halomonas xianhensis SUR308.

A moderately halophilic bacterium, Halomonas xianhensis SUR308 (Genbank Accession No. KJ933394) was isolated from a multi-pond solar saltern at Surala, Ganjam district, Odisha, India. The isolate produced a significant amount (7.87 g l(-1)) of extracellular polysaccharides (EPS) when grown in malt extract-yeast extract medium supplemented with 2.5% NaCl, 0.5% casein hydrolysate and 3% glucose. The EPS was isolated and purified following the conventional method of precipitation and dialysis. Chromatographic analysis (paper, GC and GC-MS) of the hydrolyzed EPS confirmed its heteropolymeric nature and showed that it is composed mainly of glucose (45.74 mol%), galactose (33.67 mol %) and mannose (17.83 mol%). Fourier-transform infrared spectroscopy indicated the presence of methylene and carboxyl groups as characteristic functional groups. In addition, its proton nuclear magnetic resonance spectrum revealed functional groups specific for extracellular polysaccharides. X-ray diffraction analysis revealed the amorphous nature (CIxrd, 0.56) of the EPS. It was thermostable up to 250 °C and displayed pseudoplastic rheology and remarkable stability against pH and salts. These unique properties of the EPS produced by H. xianhensis indicate its potential to act as an agent for detoxification, emulsification and diverse biological activities.

Diffusion kinetics of samarium and neodymium in garnet, and a method for determining cooling rates of rocks

Experimental determinations of the diffusion coefficients of samarium and neodymium in almandine garnet and theoretical considerations show that one cannot assign a sufficiently restricted range of closure temperature, TC, to the samarium-neodymium decay system in garnet for the purpose of constraining the cooling rate. However, it is shown that the samarium-neodymium cooling age of garnet can be used to calculate both cooling rate and TC if the temperature and age at the peak metamorphic conditions are known.

Purification of a retinol binding protein from the hen-oviduct cytosol and its immunological cross-reactivity with those from the nucleus.

Cellular retinol-binding protein was purified from the cytosol of the oviducts of laying hens by ammonium sulphate fractionation and chromatography on Sephadex G-75 and DEAE-Sephadex A-50 columns. Analysis of the purified retinol-binding protein on 10% SDS-polyacrylamide gel revealed the presence of a doublet representing very similar molecular sizes. Antiserum was prepared against the purified cellular retinol-binding protein, and on the basis of (a) immunodiffusion test and (b) immunoneutralization of 3H-labelled retinol-cellular retinol-binding protein complex on a column of Sephadex G-75, the antiserum appeared to be specific. The antiserum showed cross-reactivity with the nucleosol and a 0.4 M NaCl extract of the chromatin of the oviduct nuclei, while it did not react with the major egg-white proteins such as ovalbumin, conalbumin and ovomucoid.

Localization of testis-variant histones in rat testis chromatin.

Nucleosome core particles and oligonucleosomes were isolated by digesting rat testis nuclei with micrococcal nuclease to 20% acid-solubility, followed by fractionation of the digest on a Bio-Gel A-5m column. The core particles thus isolated were characterized on the basis of their DNA length of 151 +/- 5 base-pairs and sedimentation coefficient of 11.4S. Analysis of the acid-soluble proteins of the core particles indicated that histones TH2B and X2 are constituents of the core particles, in addition to the somatic histones H2A, H2B, H3 and H4. The acid-soluble proteins of the oligonucleosomes comprised all the histones, including both the somatic (H1, H2A, H2B, H3, H4 and X2) and the testis-specific ones (TH1 and TH2B). It was also observed that histones TH1 and H1 are absent from the core particles and were readily extracted from the chromatin by 0.6 M-NaCl, which indicated that both of them are bound to the linker DNA.

Effect of dietary unsaturated oils on the biosynthesis of cholesterol, and on biliary and fecal excretion of cholesterol and bile acids in rats.

The aim of the present work was to investigate whether the hypocholesterolemic effect of polyunsaturated oils is due to inhibition of cholesterol synthesis or increased excretion of cholesterol and bile acids through the bile and feces of animals. Separate groups of rats were fed diets containing 10% safflower oil, coconut oil or hydrogenated vegetable oils for 30 days, after which the hepatic cholesterol and bile acid synthesis and their excretion through the bile and feces were studied. As compared to the rats in the other two groups, those given the diet containing 10% safflower oil showed markedly increased rates of bile flow and excreted through their bile and feces markedly higher amounts of cholesterol and bile acids. At the same time incorporation of [1-14C]acetate and [2-14C]mevalonate into the liver cholesterol and conversion of [4-14C]cholesterol into 14C-bile acids were also higher in the same rats. In the light of these observations it has been discussed that in the animals given polyunsaturated oils, biliary and fecal loss of cholesterol and bile acids far outweighs the activation of cholesterol synthesis and thereby effectively lowers the serum cholesterol levels.

Isolation and characterization of binding proteins for retinol from the cytosol, nucleosol and chromatin of the oviduct magnum of laying hens.

Protein fractions that bind retinol were isolated from the cytosol, nucleosol and chromatin of the oviduct magnum of laying hens. The proteins isolated from the three sources showed similar elution profiles on chromatography through Sephadex G-75 and G-50 columns, and comparable mobility during electrophoresis on sodium dodecyl sulphate/polyacrylamide gels. Their molecular weights were calculated to be around 14500. When oviducts from vitamin A-depleted and vitamin A-repleted immature chicks given oestrogen injections for 6 consecutive days were incubated with [3H]retinyl acetate, uptake of the radioactivity in the nuclei of the vitamin A-depleted tissue was severalfold higher than that in the nuclei from the vitamin A-repleted tissue.

Effect of vitamin A nutritional status on the ribonucleic acids of liver, intestinal mucosa and testes of rats.

1. Vitamin A deficiency led to an increase in the oligonucleotide fraction of testes and intestinal mucosa of rats at the expense of high-molecular-weight RNA and 4S RNA, but no such changes were observed in the liver. Retinyl acetate supplementation reversed these effects in both tissues, whereas retinoic acid supplementation was almost equally effective in the mucosa but virtually ineffective in the testes. The ribonuclease activities of all the tissues remained unaffected by the above treatments. 2. The effect of vitamin A deprivation on the acceptor activity of the tRNA of the testes and intestinal mucosa was more pronounced than on the liver tRNA. The testes and mucosal tRNA of the retinoic acid-supplemented rats showed significantly lower charging capacity as compared with the retinyl acetate-supplemented ones. Here also no significant effect was observed on the liver tRNA. 3. Vitamin A deficiency caused a decrease in the percentage of poly(A) in RNA of the mucosa and testes, but not in the liver RNA. The poly(A) contents of both tissues were brought to normal by retinyl acetate supplementation; treatment with retinoic acid led to an appreciable increase in poly(A) in the mucosa, but considerably less increase in poly(A) in the testes. 4. The incorporation of H332PO4 into the rRNA and tRNA of the testes was lowered by vitamin A deficiency, but no such effects was observed in the liver RNA.