谭清苏铁性别相关的RAPD标记研究

以谭清苏铁(Cycas tanqingii D.Y.Wang)雌雄植株半年生羽叶为材料,用优化的CTAB法分别提取其全基因组DNA,进行RAPD单因子梯度实验和正交实验以优化扩增条件。应用160个RAPD随机引物检测基因组DNA,雌雄植株均扩增出1450多条带,其中引物S0465扩增出与谭清苏铁雌株高度相关的RAPD标记,其大小约为500bp,该标记与雄株没有关联。     

Mechanisms of the acute ischemia-induced arrhythmogenesis--a simulation study

The underlying ionic mechanisms of ischemic-induced arrhythmia were studied by the computer simulation method. To approximate the real situation, ischemic cells were simulated by considering the three major component conditions of acute ischemia (elevated extracellular K(+) concentration, acidosis and anoxia) at the level of ionic currents and ionic concentrations, and a round ischemic zone was introduced into a homogeneous healthy sheet to avoid sharp angle of the ischemic tissue. The constructed models were solved using the operator splitting and adaptive time step methods, and the perturbation finite difference (PFD) scheme was first used to integrate the partial differential equations (PDEs) in the model. The numerical experiments showed that the action potential durations (APDs) of ischemic cells did not exhibited rate adaptation characteristic, resulting in flattening of the APD restitution curve. With reduction of sodium channel availability and long recovery of excitability, refractory period of the ischemic tissue was significantly prolonged, and could no longer be considered as same as APD. Slope of the conduction velocity (CV) restitution curve increased both in normal and ischemic region when pacing cycle length (PCL) was short, and refractory period dispersion increased with shortening of PCL as well. Therefore, dynamic changes of CV and dispersion of refractory period rather than APD were suggested to be the fundamental mechanisms of arrhythmia in regional ischemic myocardium.     

The role of LXRα in goose primary hepatocyte lipogenesis

In this study, we investigate the role of liver X receptor alpha (LXR alpha) in lipogenesis in geese in order to understand the differences in hepatic steatosis mechanisms between mammals and waterfowl. Primary goose hepatocytes were isolated and treated with the LXR alpha agonist T0901317. Triglyceride (TG) accumulation, acetyl-CoA carboxylase alpha (ACC alpha) and fatty acid synthase (FAS) activities, and gene expression levels of LXR alpha, sterol regulatory element-binding proteins-1 (SREBP-1), FAS, ACC alpha and lipoprotein lipase (LPL) were measured in primary hepatocytes. We found a dose-dependent up-regulation of TG accumulation, ACC, and FAS activities and the mRNA levels of LXR alpha, SREBP-1, FAS, ACC alpha, and LPL genes in the presence of To-901317. We also found that binding of nuclear SREBP-1 to ACC alpha SRE sequence was induced by To-901317 (P < 0.05). In conclusion, LXR alpha is involved in the induction of the lipogenic pathway through activation of SREBP-1 and its target genes in goose primary hepatocytes.