Shoot population dynamics of persisting clones of<Emphasis Type="Italic"> Miscanthus sinensis</Emphasis> in the warm-temperate region of Japan

The population dynamics of annual shoots in four clonal patches of Miscanthus sinensis was surveyed in terms of clone persistence. Over a study period of 3 years, a stable net shoot number was attained through a balanced replacement of old shoots by tillering 2–3 times a year. The birth rate was significantly correlated with the average monthly temperature. This suggests that a warm climate advances the date of tillerings, and shoots become taller as they emerge earlier. Five cohorts were identified, corresponding to shoots that were born in spring, early summer, summer, autumn and early winter. The autumn cohorts were more numerous and had a greater longevity than the other cohorts; they were thus were best suited for overwintering and, consequently, maintaining the population from one generation to the next. The shoots of earlier cohorts grew too tall to survive the cold of winter, which might cause freezing injury, while later cohorts shoots excelled in overwintering because of their shortness. However, if the delayed shoots are very short, they will also have difficulty in surviving the early season of growth. Therefore, M. sinensis shoots have an optimum size for survival.     

Chlorogenic acid modifies plasma and liver concentrations of: cholesterol,triacylglycerol, and minerals in (fa/fa) Zucker rats

Chlorogenic acid, a phenolic compound found ubiquitously in plants, is an in vitro antioxidant and metal chelator. Some derivatives of chlorogenic acid are hypoglycemic agents and may affect lipid metabolism. Concentrations of cholesterol and triacylglycerols are of interest due to their association with diseases such as non-insulin-dependent-diabetes- mellitus and obese insulin resistance. As little is known about the effects of chlorogenic acid in vivo, studies using obese, hyperlipidemic, and insulin resistant (fa/fa) Zucker rats were conducted to test the effect of chlorogenic acid on fasting plasma glucose, plasma and liver triacylglycerols and cholesterol concentrations. Aditionally, the effects of chlorogenic acid on selected mineral concentrations in plasma, spleen, and liver were determined. Rats were implanted with jugular vein catheters. Chlorogenic acid was infused (5 mg/Kg body weight/day) for 3 weeks via intravenous infusion. Chlorogenic acid did not promote sustained hypoglycemia and significantly lowered the postprandial peak response to a glucose challenge when compared to the same group of rats before Chlorogenic acid treatment. In Chlorogenic acid-treated rats, fasting plasma cholesterol and triacylglycerols concentrations significantly decreased by 44% and 58% respectively, as did in liver triacylglycerols concentrations (24%). We did not find differences (p > 0.05) in adipose triacylglycerols concentration. Significant differences (p < 0.05) in the plasma, liver, and spleen concentration of selected minerals were found in chlorogenic acid-treated rats. In vivo, chlorogenic acid was found to improve glucose tolerance, decreased some plasma and liver lipids, and improve mineral pool distribution under the conditions of this study.     

No evidence of inbreeding depression in fast declining herds of migratory caribou

Identifying inbreeding depression early in small and declining populations is essential for management and conservation decisions. Correlations between heterozygosity and fitness (HFCs) provide a way to identify inbreeding depression without prior knowledge of kinship among individuals. In Northern Quebec and Labrador, the size of two herds of migratory caribou (Rivière‐George, RG and Rivière‐aux‐Feuilles, RAF) has declined by one to two orders of magnitude in the last three decades. This raises the question of a possible increase in inbreeding depression originating from, and possibly contributing to, the demographic decline in those populations. Here, we tested for the association of genomic inbreeding indices (estimated with 22,073 SNPs) with body mass and survival in 400 caribou sampled in RG and RAF herds between 1996 and 2016. We found no association of individual heterozygosity or inbreeding coefficient with body mass or annual survival. Furthermore, those genomic inbreeding indices remained stable over the period monitored. These results suggest that the rapid and intense demographic decline of the herds did not cause inbreeding depression in those populations. Although we found no evidence for HFCs, if demographic decline continues, it is possible that such inbreeding depression would be triggered.     

Effects of two chitin synthesis inhibitors on Thalassiosira fluviatilis and Cyclotella cryptica

Abstract The effects of two commercial chitin synthesis inhibitors, dimilin and polyoxin D, on chitin fiber formation and cell sedimentation for the diatoms Thalassiosira fluviatilis and Cyclotella cryptica (Bacillariophyceae) were investigated. Dimilin treatments for both diatom species were indistinguishable from controls in terms of chitin fiber productions, cell density and sedimentation. Polyoxin D-treated cells of both diatom species completely lacked the characteristic chitin fibers. Polyoxin D cultures were also characterized by a significant decrease in population density, increased sedimentation rates and a strong tendency to clump in comparison with control and dimilin treatments. It was concluded that (1) dimilin does not directly inhibit chitin synthesis in diatoms; (2) polyoxin-D inhibits β-chitin fibril formation, and (3) chitin fibers play an important role in cell separation and cell buoyancy.     

栗背短脚鹎的种群分化与遗传多样性

栗背短脚鹎(Hemixos castanonotus)是我国南方山区常见的杂食性鸟类。为探明其遗传多样性及分化现状,采用线粒体Cyt b基因和7个核基因非编码区片段作为分子标记,对分布于广东、广西、海南、贵州和江西五省(自治区)的栗背短脚鹎11个地理种群进行了遗传分化及遗传多样性研究。基于所获得的Cyt b基因866 bp和7个核基因内含子序列6 808 bp进行分析。结果显示,在Cyt b基因中,共检测到37个单倍型,共享单倍型占单倍型总数的35.6%,推测这些共享单倍型可能属于祖先单倍型。分子方差分析结果显示,遗传变异主要来源于种群内部(79.77%)。Tajima’s D和Fu’s Fs中性检验分析结果均支持栗背短脚鹎种群可能曾经历过种群扩张现象。基于7个核基因内含子联合序列的贝叶斯天际线(BSP)分析,推断其种群在大约5.3 ~ 3.7百万年前(Mya)和约0.7 ~ 0.3百万年前(Mya)发生过扩张。基于Cyt b基因的贝叶斯系统发育分析,11个地理种群共分为两支,一支为海南猴猕岭地理种群,属指名亚种(H. c. castanonotus),其他10个地理种群聚为另一支,属H. c. canipennis亚种,并且后者尚未形成显著的地理结构,单倍型网络图分析也获得相似的结果。本研究所用分子数据基本支持两个亚种的分化,对于存在争议的广西南部分布的指名亚种,其分子数据与形态学亚种归属不一致,有待更深入研究。     

Bt水稻田重要非靶标节肢动物权露于Cry2Aa蛋白的程度分析

根据风险=危险×机露的原理,在实验室条件下评价转基因作物对非靶标节肢动物影响时,所选择的代表性非靶标生物通常是在农田系统中较高地关露于转基因外源杀虫蛋白的节肢动物种.为了弄清Bt稻田主要节肢动物暴露于Cry蛋白的程度,选择合适的非靶标节肢动物,用于转基因抗虫水稻的风险评价,本文采用酶联免疫技术检测了水稻不同生长期从转cry2Aa基因水稻田采集的不同节肢动物体内Cry2Aa蛋白的含量.结果表明:不同节肢动物种体内的Cry蛋白含量差异显著.一些节肢动物体内不合Cry蛋白,而一些节肢动物体内含有较高的Cry蛋白;相对于花期后采集的节肢动物,在Bt水稻花期采集的节肢动物,特别是捕食性节肢动物体内的Cry蛋白含量较高;寄生性节肢动物体内未检测到Cry蛋白.这为在实验室条件下评价转基因水稻对农田非靶标节肢动物的影响奠定了基础.