Regulation of expression by divalent cations of a light-inducible gene in Arthrobacter photogonimos

Expression of the light-inducible (lipA) gene in Arthrobacter photogonimos is repressed by Ca²⁺ at a concentration greater than 0.1 M. Expression of lipA was induced by relatively high concentrations of Zn²⁺ Ni²⁺ or Co²⁺ in cell suspensions, an effect that was blocked by an increase in the concentration of Ca²⁺ in the medium. Zn²⁺ and other metals apparently overcame repression by Ca²⁺ by competing for a cellular binding site. Expression of lipA was also induced when the amount of free Ca²⁺ was lowered with ethylene-bis (oxyethylenenitrilo)tetraacetic acid (EGTA). Our results show that the lipA gene does not require Zn²⁺ or other divalent cation for expression and that it is regulated negatively by Ca²⁺.Accumulation of the mature product of this gene (light-inducible protein, LIP) was minimal in the presence of EGTA. Accumulation increased 10-to 20-fold when divalent cations such as Ca²⁺, Mn²⁺, Cu²⁺ or Zn²⁺ were added to cell suspensions treated with chelator. These divalent cations, which allowed the protein to achieve a protease-resistant form on the cell surface, could be substituted by protease inhibitors such as antipain, leupeptin or 1,10-phenanthroline. Our data can be explained by a biparous mechanism in which divalent cations regulate both expression of the lipA gene and accumulation of the gene product.Abbreviations LIP light-inducible protein - BAPTA 1,2-bis(o-aminophenoxy)ethanc-N,N,N,N-tetraacetic acid     

Chemistry in Bioinformatics

 

Chemical information is now seen as critical for most areas of life sciences. But unlike Bioinformatics, where data is openly available and freely re-usable, most chemical information is closed and cannot be re-distributed without permission. This has led to a failure to adopt modern informatics and software techniques and therefore paucity of chemistry in bioinformatics. New technology, however, offers the hope of making chemical data (compounds and properties) free during the authoring process. We argue that the technology is already available; we require a collective agreement to enhance publication protocols.     

小腹茧蜂亚科的雄外生殖器及族级单元系统发育的研究

对分布在东洋区和古北区的小腹茧蜂亚科 (膜翅目: 茧蜂科)21个属的67个种及外群折脉茧蜂属 (膜翅目: 茧蜂科) 2个种的雄外生殖器的5个性状进行了比较研究。在形态学研究的基础上,通过选用头部、胸部和腹部(包括雌雄外生殖器的性状) 等34个性状,运用支序分析的方法探讨了分布在东洋区和古北区的小腹茧蜂亚科21个属以及它们所属的族间的系统发育关系,并对Mason (1981) 的分类系统进行了重新评价。雄外生殖器和支序分析基本上证实并恢复了由Mason (1981) 确定的2个主要分支,即绒茧蜂族Apantelini+小腹茧蜂族Microgastrini和拱茧蜂族Fornicini+盘绒茧蜂族Cotesiini+侧沟茧蜂族MicroplitinI。绒茧蜂族Apantelini、拱茧蜂族Fornicini和侧沟茧蜂族Microplitini为单系群也被支持,但小腹茧蜂族Microgastrini和盘绒茧蜂族Cotesiini是否为单系群尚难于在树形图中体现,而且族内各属间的分支关系有变动。因此,尽管Mason的族级分类单元有一些欠缺,但仍是可信、实用的,不同意Walker等 (1990) 认为不应再使用Mason分族系统的观点。     

Interclonal differences, plasticity and trade-offs of life history traits of Cyperus esculentus in relation to water availability

Cyperus esculentus is an exotic clonal (or pseudoannual) weed in Japan, and its range is steadily increasing. To investigate its interclonal variation and phenotypic plasticity in response to water availability, five clones of C. esculentus , collected from different sites in Japan, were grown singly in pots placed outdoors under dry and wet conditions. All the traits examined showed considerable variation among the five clones. However, two clones from Tochigi were similar to each other; thus, they might have originated from the same founder population. The clone from Ibaraki was quite different from the others. Therefore, it is suggested that the Japanese populations of C. esculentus might have resulted from multiple introductions of genotypes from geographically separated and, hence, genetically differentiated, source populations. All the clones also showed considerable plasticity in response to water availability. Clones with a larger ramet number had a greater plasticity, whereas tuber size was invariant across water treatments. Highly plastic traits had generally low interclonal variation in plasticity. All the clones had high productivity and produced more ramets and tubers under wet conditions than under dry conditions. Moreover, water availability could partially regulate the mode of its reproduction; wet conditions favored tuber production (vegetative propagation) while dry conditions favored sexual reproduction. A number of trade-offs occurred between the traits of clonal growth, storage and sexual reproduction, indicating that allocation among the competing functions/organs is mutually exclusive in plants. The results obtained here suggest that C. esculentus is more likely to invade wet habitats than dry habitats.     

Synthesis of GA20 glucosyl derivatives and the biological activity of some gibberellin conjugates

GA₂₀-13-0-glucoside (7a) and GA₂₀ glucosyl ester (6a), potential endogenous conjugates in maize, were synthesized chemically. The biological activities of these compounds and of nine more GA glucosyl derivatives were determined using theZea mays dwarf- 5 seedling andOryza sativa cv. “Tan-ginbozu” assays. The relative bioactivities of the conjugates were also calculated.