Effects of some alcohols on the conformation of mitochondrial H+-ATPase complex and F1-ATPase from pig heart

The conformations of the H+-ATPase complex and F1-ATPase in low concentrations of methanol, ethanol, n-propanol, iso-propanol and t-butanol were studied by circular dichroism. For F1-ATPase, all but methanol first increased and then decreased the circular dichroism magnitude of helical bands as the alcohol concentration was increased. With ethanol, n-propanol, iso-propanol and t-butanol, the alpha-helix content reached a maximum at about 5% alcohol and began to decrease at 10%. The content of beta-sheet showed the opposite effect, reaching a minimum at 5% and increasing slightly at higher concentrations. None of the alcohols studied had a significant effect on the conformation of the H+-ATPase complex. This difference implies that the alcohols had a greater effect on free F1-ATPase than on the membrane-bound F1-ATPase. The hydrophobic protein F0 and the membrane lipids in the H+-ATPase complex may stabilize and protect F1 from the effects of the alcohols.     

N-Deacetylation of 2-acetamido-2-deoxy-hexosecontaining oligosaccharides and polysaccharides by calcium in liquid ammonia

N-Deacetylation of 2-acetamido-2-deoxy-hexose residues is accomplished in liquid ammonia containing calcium. Oligosaccharides, lacto-N-fucopentaose II and lacto-N-difucohexaose I, containing 3,4-disubstitutedN-acetylhexosamine residues are quantitativelyN-deacetylated. When applied to polysaccharides, however, only partialN-deacetylation was achieved.Author for correspondence. AXRD     

Several nodulins of soybean share structural domains but differ in their subcellular locations.

Four soybean cDNA nodule-specific clones encoding nodulin-23, -26b, -27 and -44 were observed to cross-hybridize under low stringency conditions. Nucleotide sequence analysis revealed that the cDNAs contain three distinct domains: two domains with 70 to 95% homology separated by a third domain unique to each cDNA. Despite a number of nucleotide insertions and deletions, the protein sequences are conserved in the two domains which correlate with the homologous nucleotide domains. The amino terminal domain of each nodulin contains putative signal sequences for membrane translocation, although only two (nodulin-23 and -44) meet all the criteria for a functional signal. Immuno-precipitation of hybrid-release translation products of the four cDNAs revealed that nodulin-23 is associated with the peribacteroid membrane while nodulin-27 is in the cytoplasmic fraction of the nodule. These four nodulins are members of a diverse family with conserved structural features and the genes encoding them appear to have recently evolved from a common ancestor.     

Chicken erythrocyte beta-globin chromatin: enhanced solubility is a direct consequence of induced histone hyperacetylation.

Chicken immature red blood cells were incubated for 1 hour in Swim's medium containing 3H-acetate and 10 mM n-butyrate. During the incubation period, the small percentage of dynamically acetylated and deacetylated histone is radiolabeled and hyperacetylated. A second effect of the n-butyrate incubation is to shift a small subset of nucleohistone into a soluble form. This chromatin is predominantly polynucleosome size (approximately dimer to pentamer) and can be separated from soluble mononucleosomes by 5-30% sucrose gradient centrifugation. The soluble polynucleosomes are 25-30 fold enriched for adult beta-globin (beta A) DNA and contain the hyperacetylated histones. We have tested whether histone hyperacetylation is responsible for the enhanced beta-globin chromatin solubility by in vitro deacetylation of the soluble chromatin histones. This procedure converts the beta-globin polynucleosomes to an insoluble form, demonstrating that histone hyperacetylation is in fact directly responsible for the increased solubility of the beta A chromatin.     

长滩果引种驯化研究

长滩果系罗汉果最佳品种。原产区分布于永福和临桂县交界400—600米山区,但不适应于低丘陵和平原地区,因而不能在低丘陵和平原地区推广。为了解决这个问题。采用了(1)选择湿润和半阴的生长环境;(2)采用适应性强的砧木;(3)促成栽培;(4)加强秋旱期的科学管理等措施并取得成功,试验结果表明长滩果产量和品质达到或略超过原产区水平。     

Antimutagenic effect of garlic (Allium sativum L.) on 4NQO-induced mutagenesis in Escherichia coli WP2

Aqueous extract prepared from garlic bulbs markedly suppressed the mutagenesis in both E. coli WP2 trp- and E. coli WP2 trp- uvrA- induced by 4-nitroquinoline 1-oxide (4NQO), but not that induced by UV. Cellular toxicity, inhibition of the expression of the Trp+ phenotype and delay of the first cell division after 4NQO treatment were not observed in the presence of the extract. Since the extract showed identical antimutagenic effects against 4NQO in both test strains but no effect on the mutagenesis of UV, it seems that the extract might act by inactivating the electrophilic group(s) of 4NQO or inhibiting its metabolic activation.     

Microcalorimetric measurements of tissue cells in vitro

A culture flask was designed for the microcalorimetric measurements of tissue cells by an MS 80 standard calvet microcalorimeter. Tissue cells cultured in this flask behaved in the same manner as in the common culture flask used in cytobiological studies. The thermograms of human adenocarcinoma gastric cells (SGc 7901) and HeLa cells were obtained. The heat output power of SGc 7901 cells continuously increased for 70 h with an initial cell number of 3.0 X 10(5). The thermogram was reproducible under strictly controlled conditions. The relationship between the heat output power and the number of SGc 7901 cells within 48 h was obtained. The heat output power was 40 pW/cell to 49 pW/cell when the cell number was in the range 4.5 X 10(5) to 10.4 X 10(5). It was 62.3 +/- 2.9 pW/cell for HeLa cells when the cell number was 6 X 10(5).