Morphological and physiological responses to increased salinity in marsh and dune ecotypes ofSporobolus virginicus (L.) Kunth

Summary Sporobolus virginicus (L.) Kunth is a halophytic grass native to tropical and warm temperate coasts throughout the world. A rhizomatous perennial with erect culms,S. virginicus occurs as two genetically distinct growth forms, which are designated by their characteristic habitats as marsh and dune. What accounts for the specific distribution and maintenance of two separate ecotypes ofS. virginicus is not known. The present study examined the effects of seawater salinity on several morphological and physiological responses of hydroponically cultivated marsh and dune plants to determine whether differential tolerance to substrate salinity might contribute to the observed pattern of habitation. Both marsh and dune form plants survived prolonged exposure to full-strength seawater and reproduced vegetatively via culms and rhizomes. Salinity-induced reductions in culm height, internode length, and leaf size led to a miniaturization of marsh and dune plants. Sodium ion levels were low (<1.0 mmol/g dry weight) in various organs of salinized plants irrespective of ecotype, and potassium ion content increased in all salt-challenged plants, as did quarternary ammonium compounds and proline. Significant differences, however, between marsh and dune plants with respect to the effects of salinity on resource allocation, flowering phenology, and protein composition suggested that external salt concentration has a role in determining ecotype distribution.     

Effect of pH on lipid accumulation by an oleaginous yeast:Rhodotorula glutinis IIP-30

Maximum lipid production (66% w/w dry wt) inRhodotorula glutinis IIP-30 utilizing glucose in a fed-batch fermentation under N-limiting conditions at 30°C, was at pH 4. At pH 3, 5 and 6, the lipid contents were 12%, 48% and 44%, respectively. There was only a small change in the fatty acid profile over the pH range examined, although the ergosterol content decreased by a third as the pH increased.     

人酸性成纤维细胞生长因子神经营养作用的初步研究

本实验研究了人酸性成纤维细胞生长因子(haFGF)的体外神经营养作用。结果表明,haFGF在体外能明显促进鸡胚(E-8)脊髓组织神经突起的生长,并能明显改变新生大鼠脑星形胶质细胞的形态,使扁平、多角形紧密联接的细胞转化为具有纤维样突起的胶质细胞,同时对胶质细胞DNA合成也有一定促进作用。实验还证明,haFGF可增加体外培养新生大鼠海马神经元的存活,且大大增加神经元胞体体积及突起长度。     

越冬期间香蕉果穗套袋的防寒效果及其对产量的影响

冬季香蕉果穗用兰色聚乙烯薄膜套袋之后,可提高袋内温度1～5℃,果实低温伤害卑只有1％左右,而未经套袋的达23％～35％,果指长度和径围增加率分别达12％和9％左右,果实产量比对照增加8％～16％。试验结果表明,兰色聚乙烯薄膜套袋是越冬期间香蕉防寒保果和增产的一项有效措施。     

染色体辐射效应的微机检测 Ⅱ断片率 微核率与细胞畸变率间的相关性检测

本文继前文后,按照设计的线性回归程序在“IBM—PC/XT”微型计算机上,进一步检测了断片率、微核率与细胞畸变率之间的相关性,肯定了微核测定法,断片测定法可以替代染色体畸变分析法。     

The binding of anionic and nonionic surfactants to collagen through the hydrophobic effect

The adsorption of nonionic surfactants on hide powder previously treated with anionic surfactants has been studied. The adsorption of nonionic surfactants takes place through hydrophobic interactions. A mechanism has been proposed for this interaction, assuming that the nonionic surfactant has been fixed by means of secondary adsorption (hydrophobic interaction) after the primary adsorption of the anionic surfactant (ionic and hydrophobic interaction) which makes it possible.     

Influence of salt concentration and temperature on the fatty acid compositions of Ectothiorhodospira and other halophilic phototrophic purple bacteria

Influences of the salt concentration on the fatty acid composition of Ectothiorhodospira species and other phototrophic purple bacteria have been analysed. Major fatty acids in bacteria of the genera Rhodobacter, Rhodopseudomonas, Chromatium, and Ectothiorhodospira were straight chain saturated and monounsaturated C-16 and C-18 fatty acids. Salt-dependent responses of all investigated bacteria revealed relations to their salt optima. Minimum values of C-16 and saturated fatty acids and maximum values of C-18 and unsaturated fatty acids were found at or close to the salt optima. Responses of Ectothiorhodospira mobilis upon changes in salinity were nearly identical, whether cells were grown in batch culture or in continuous culture with identical dilution rates at all salt concentrations. With increasing temperature, the fatty acid composition of Ectothiorhodospira mobilis and Ectothiorhodospira halophila strains showed decreasing portions of C-18 and of unsaturated fatty acids, while the contents of C-16 and saturated fatty acids increased. The results are discussed with respect to bilayer stabilisation and membrane fluidity.Abbreviations PC phosphatidylcholine - PG phosphatidylglycerol - CL cardiolipin - PE phosphatidylethanolamine     

Comparison of salt- and heat-induced alterations of protein synthesis in the cyanobacterium Synechocystis sp. PCC 6803

Protein synthesis of the cyanobacterium Synechocystis spec. PCC 6803 decreases after a 684 mM NaCl salt shock. Qualitative changes were observed during the shock and the subsequent adaptation process using one-dimensional polyacrylamide electrophoresis. Proteins of apparent molecular masses of 13.0, 14.2, 16.6, 20.0, 21.0, 23.0, 33.0, 47.0, 52.0, 65.0 and 72.0 kDa are synthesized at enhanced rates after salt stress. The proteins of 14.2, 21.1 and 52.0 kDa are transiently induced during the first hours of the adaptation phase, while the other proteins are also synthesized at enhanced rates in salt-adapted cells. The proteins of 14.2, 23.0, 33.0 and 65.0 kDa are also induced by heat shock (43°C). Heat shock proteins of about 88.0, 75.0, 58.0, 17.5 and 13.8 kDa, in contrast, are induced by heat shock but not by salt. Two-dimensional polyacrylamide electrophoresis showed that the induced salt and heat shock proteins in some cases consisted of isoforms of different isoelectric points.Abbreviations IP isoelectric point - PAGE polyacrylamide gel electrophoresis - PMSF phenylmethylsulfonyl fluoride