Discontinuous polyacrylamide gel electrophoresis of cell wall proteinase from variants of Streptococcus lactis

An electrophoretic procedure has been developed for the separation of plasmid-coded cell wall proteinases from Streptococcus lactis NCDO strain 712. The pH and casein concentration within the electrophoresis rod during detection is more closely defined than in existing methods. The incubation conditions used with casein, (approximately pH 7 and 30dEC) may be suitable for the detection of a wider range of proteinases from other sources. Four proteinase bands present in the cell wall have been detected in milk grown cells, but only two in those previously grown in a broth medium. No cell wall proteinases were detected in a proteinase deficient variant.     

Action of Angiotensins and Synthetic Renin Substrate on Isolated Rat Colon

AIKEN and Vane have reported¹ the independent actions of angiotensin I (AI) and angiotensin II (AII) on various isolated smooth muscle preparations, including rat colon. Tney showed that the apparent contractile action of AI on these preparations depended primarily on its in situ conversion to All by “converting enzyme” and that when the activity of the enzyme was inhibited by a pentapeptide extracted from Bothrops jararaca venom, the residual contractile action, probably due to unchanged AI, was very small. I have investigated the action of synthetic tetradecapeptide renin substrates (TPRS) on rat colon, in the light of the known actions of AI and All.     

高产杀粉蝶菌素的链霉菌鉴定及其拮抗水稻白叶枯菌活性研究

【目的】为保证农业生产可持续性发展,研发和使用环境友好的生物农药受到全社会的高度重视。微生物代谢产物农药是我国目前应用最广的生物农药,也是未来发展绿色农药的一个重要方向。【方法】利用包含水稻白叶枯菌(Xanthomonas oryzae pv. oryzae, Xoo) PXO99A的NA培养基琼脂平板,从水稻根际土壤中筛选能抑制Xoo生长的链霉菌。通过高效液相色谱和质谱分析活性代谢产物的化学结构;采用剪叶法接种Xoo到水稻叶片后,再喷施杀粉蝶菌素溶液(0.1 g/L),2周后测定叶枯症状;采用响应面分析法优化高产杀粉蝶菌素的发酵培养基;采用PacBio SMRT测序平台+Illumina HiSeq X Ten平台开展全基因组测序。平均核苷酸一致性(average nucleotide identity,ANI)用于比较HSW2009与其他链霉菌在全基因组水平的亲缘关系。【结果】分离到一株对Xoo生长有强抑制活性的链霉菌HSW2009,其活性代谢产物为杀粉蝶菌素A1(piericidin A1,简称PIE);喷施PIE可以减轻Xoo在水稻叶片内的侵染;优化HSW2009高产PIE的发...     

Land snail diversity in the monsoon tropics of Northern Australia: revision of the genus Exiligada Iredale, 1939 (Mollusca: Pulmonata: Camaenidae), with description of 13 new species

Vast parts of the monsoon tropics of Australia feature semi‐arid habitats, which are generally thought to harbour a depauperate land snail fauna as compared to the mesic continental fringes, in particular the Australian wet tropics. However, our knowledge of land snails inhabiting these often remote environments is still very patchy. In order to improve the understanding of land snail diversity in the monsoon tropics, we revised the camaenid land snail genus Exiligada based on comprehensive collections, undertaken by use of helicopters on remote limestone outcrops in the Northern Territory and in Western Australia. Based on comparative analyses of shell and genital morphology and patterns of molecular differentiation, we recognize 15 species within Exiligada, 13 of which are newly described. In addition, we suggest a revised delimitation of the type species Exiligada negriensis, as compared to the latest available revision, by removing Exiligada qualis from its synonymy and recognizing it as a distinct species. A key for species identification is also provided. Molecular phylogenetic analyses strongly supported the monophyly of Exiligada with respect to other confamilial genera known to occur in the same geographical region. Most Exiligada species are narrowly endemic to restricted limestone outcrops that cover areas with a diameter of about 20 to 150 km. Within the distributional range of Exiligada, the ranges of up to seven species overlap but we never found more than three species to occur in sympatry at a given sampling site. We propose that species originated by allopatric differentiation, followed by secondary range expansion, leading to sympatric distributions. Our study confirms that less complex rock habitats in more xeric environments support no more than three sympatric species, this being likely to be a result of ecological exclusion. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 689–722.