Endoplasmic Reticulum Stress in Heat- and Shake-Induced Injury in the Rat Small Intestine

We investigated the mechanisms underlying damage to rat small intestine in heat- and shake-induced stress. Eighteen Sprague-Dawley rats were randomly divided into a control group and a 3-day stressed group treated 2 h daily for 3 days on a rotary platform at 35°C and 60 r/min. Hematoxylin and eosin-stained paraffin sections of the jejunum following stress revealed shedding of the villus tip epithelial cells and lamina propria exposure. Apoptosis increased at the villus tip and extended to the basement membrane. Photomicrographs revealed that the microvilli were shorter and sparser; the nuclear envelope invaginated and gaps in the karyolemma increased; and the endoplasmic reticulum (ER) swelled significantly. Gene microarray analysis assessed 93 differentially expressed genes associated with apoptosis, ER stress, and autophagy. Relevant genes were compiled from the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Forty-one genes were involved in the regulation of apoptosis, fifteen were related to autophagy, and eleven responded to ER stress. According to KEGG, the apoptosis pathways, mitogen-activated protein kinase(MAPK) signaling pathway, the mammalian target of rapamycin (mTOR) signaling pathway, and regulation of autophagy were involved. Caspase3 (Casp3), caspase12 (Casp12), and microtubule-associate proteins 1 light chain 3(LC3) increased significantly at the villus tip while mTOR decreased; phosphorylated-AKT (P-AKT) decreased. ER stress was involved and induced autophagy and apoptosis in rat intestinal damage following heat and shake stress. Bioinformatic analysis will help determine the underlying mechanisms in stress-induced damage in the small intestine.     

基于水文平衡的湿地退化驱动因子定量研究

作为地球上最为重要的生态系统类型之一,湿地与森林、海洋并称为地球三大生态系统。但是,近年来湿地生态系统退化速度远大于其他类型生态系统,开展湿地退化的定量评估分析研究对于湿地生态系统的保护和恢复具有重要意义。选择北京城市湿地为研究对象,利用卫星遥感数据分别提取得到1991年和2007年的湿地面积,基于湿地水量平衡理论和湿地水文方程方法,定量评估分析了导致湿地退化的原因和不同驱动因子的贡献率。结果表明:(1)与1991年相比,2007年北京湿地减少约6275.31 hm2,约占1991年北京湿地总面积的24.46%。显著退化区域主要发生在野鸭湖湿地和密云水库湿地,分别减少了约1377.69 hm2和4654.50 hm2。(2)引起湿地退化的自然驱动因子中,以降水减少、入境地表水减少和蒸发量增加为主,驱动湿地退化的贡献率分别为39.22%、14.05%和11.85%。引起湿地退化的人为驱动因子中,以城市扩展为主,驱动湿地退化的贡献率为3.42%,而技术进步所采取的节水措施等有利于湿地保护,贡献率为25.55%。     

Association between Tumor Necrosis Factor-α 308G/A Gene Polymorphism and Silicosis Susceptibility: A Meta-Analysis

Background

Tumor necrosis factor-α (TNF-α) 308 G/A gene polymorphism has been reported to be associated with susceptibility to silicosis. However, the relevant study results are still inconsistent.

Objective and Methods

A meta-analysis was performed in order to drive a more precise estimation of the relationship between TNF-α-308 G/A gene polymorphism and susceptibility to silicosis. Electronic databases were searched and nine separate studies were included. The pooled odds ratios (ORs) and the corresponding 95% confidence internal (CI) were calculated by a fixed effect model.

Results

A total of 1267 cases and 1214 controls were included. In the overall analysis, significantly increased silicosis risk was found (for GA+AA vs. GG OR=1.45, 95%CI: 1.20-1.760, P=1.58E4; for GA vs. GG: OR=1.53, 95%CI=1.25-1.86, P=3.11E5; for A allele vs. G allele: OR=1.27, 95%CI=1.08-1.50, P= 0.004). In the subgroup analysis, significantly increased silicosis risk was also found among Asians (for GA+AA vs. GG: OR=1.63, 95%CI=1.27-2.08, P=1.01E4), for GA vs. GG: OR=1.71, 95%CI=1.33-2.20, P=3.44E5), for A allele vs. G allele: OR=1.45, 95%CI=1.17-1.80, P=0.001). However, no significantly increased risk was found among non-Asians for all genetic models.

Conclusions

TNF-α-308 G/A polymorphism might lead to an increased risk of silicosis susceptibility, especially for Asians. However, further studies with large sample sizes should be conducted to confirm the association.     

Anti-Arrhythmic Effect of Verapamil Is Accompanied by Preservation of Cx43 Protein in Rat Heart

The present study was to test the hypothesis that anti-arrhythmic properties of verapamil may be accompanied by preserving connexin43 (Cx43) protein via calcium influx inhibition. In an in vivo study, myocardial ischemic arrhythmia was induced by occlusion of the left anterior descending (LAD) coronary artery for 45 min in Sprague-Dawley rats. Verapamil, a calcium channel antagonist, was injected i.v. into a femoral vein prior to ischemia. Effects of verapamil on arrhythmias induced by Bay K8644 (a calcium channel agonist) were also determined. In an ex vivo study, the isolated heart underwent an initial 10 min of baseline normal perfusion and was subjected to high calcium perfusion in the absence or presence of verapamil. Cardiac arrhythmia was measured by electrocardiogram (ECG) and Cx43 protein was determined by immunohistochemistry and western blotting. Administration of verapamil prior to myocardial ischemia significantly reduced the incidence of ventricular arrhythmias and total arrhythmia scores, with the reductions in heat rate, mean arterial pressure and left ventricular systolic pressure. Verapamil also inhibited arrhythmias induced by Bay K8644 and high calcium perfusion. Effect of verapamil on ischemic arrhythmia scores was abolished by heptanol, a Cx43 protein uncoupler and Gap 26, a Cx43 channels inhibitor. Immunohistochemistry data showed that ischemia-induced redistribution and reduced immunostaining of Cx43 were prevented by verapamil. In addition, diminished expression of Cx43 protein determined by western blotting was observed following myocardial ischemia in vivo or following high calcium perfusion ex vivo and was preserved after verapamil administration. Our data suggest that verapamil may confer an anti-arrhythmic effect via calcium influx inhibition, inhibition of oxygen consumption and accompanied by preservation of Cx43 protein.     

Microsatellite development for the endangered Yangtze sturgeon (Acipenser dabryanus Duméril, 1869) using 454 sequencing

The Yangtze sturgeon (Acipenser dabryanus) is an endemic species in China. Using 454 sequencing, eight polymorphic tri‐, tetra‐, penta‐, and hexanucleotide microsatellite loci were isolated in this study. The raw sequence data from a one‐eighth run of 454 sequencings were 38.0 Mbp containing 94 222 reads/sequences. Of 80 microsatellite loci, only eight loci were polymorphic in a population of 30 individuals. The number of alleles per locus ranged from 4 to 14 (mean 7.62), and the observed heterozygosities varied between 0.46 and 0.88 (mean 0.74). Cross amplification was tested in congeneric species Acipenser sturio and Acipenser sinensis. These new microsatellite markers will be useful for further studies on genetic variation, parentage analysis, and conservation management for this critically endangered species.     

Mitochondrial respiration defects in cancer cells cause activation of Akt survival pathway through a redox-mediated mechanism

Cancer cells exhibit increased glycolysis for ATP production due, in part, to respiration injury (the Warburg effect). Because ATP generation through glycolysis is less efficient than through mitochondrial respiration, how cancer cells with this metabolic disadvantage can survive the competition with other cells and eventually develop drug resistance is a long-standing paradox. We report that mitochondrial respiration defects lead to activation of the Akt survival pathway through a novel mechanism mediated by NADH. Respiration-deficient cells (rho(-)) harboring mitochondrial DNA deletion exhibit dependency on glycolysis, increased NADH, and activation of Akt, leading to drug resistance and survival advantage in hypoxia. Similarly, chemical inhibition of mitochondrial respiration and hypoxia also activates Akt. The increase in NADH caused by respiratory deficiency inactivates PTEN through a redox modification mechanism, leading to Akt activation. These findings provide a novel mechanistic insight into the Warburg effect and explain how metabolic alteration in cancer cells may gain a survival advantage and withstand therapeutic agents.