Oxidative mechanisms involved in kainate-induced cytotoxicity in cortical neurons

In our previous experiments, evidence of free radical formation has been demonstrated in gerbil brain after kainic acid (KA) administration. In the present study, the mechanisms involved in KA-induced free radical formation and subsequent cell degeneration were investigated using high density cortical neuron cultures. A free radical trapping agent,a-phenyl-N-tert-butyl-nitrone (PBN), as well as the combined action of superoxide dismutase and catalase attenuated KA neurotoxic effect. Calpain-induced xanthine oxidase (XO) activation may play an important role in KA excitotoxicity since calpain inhibitor I as well as allopurinol, a selective XO inhibitor, significantly protected the cortical neurons from KA-induced cell death. However, XO activation may not be the only source producing free radicals, other free radical generating systems such as nitric oxide synphase may also play a role in KA insult.     

Genetic variation and population structure of swimming crab (Portunus trituberculatus) inferred from mitochondrial control region

Genetic variation and population structure in Portunus trituberculatus along the coast of China were revealed according to 617 bp of mitochondrial DNA control region. 90 polymorphic sites defined 53 distinct haplotypes, showing a moderately high diversity among 72 individuals sampled from eight localities. Neighbor-joining tree, statistics analyses of gene flow and genetic differentiation index indicated two populations from Beihai and Laizhou had differentiated. The population from Yingkou, Dandong, Laizhou and Beihai had smaller genetic diversity compared to that from Ningbo, Lianyungang, Qingdao and Japan according to the genetic distance. And mantel test showed significant positive correlation between genetic distance and geographic distance for P. trituberculatus. TCS parsimony network suggested that all the animals sampled were probably the result of recent divergence from a common ancestral haplotype but for Laizhou population. Moreover, the haplotype distribution appeared to correlate with a recent colonization followed by localized genetic differentiation. Mismatch distribution results suggested that Ningbo, Yingkou, Qingdao, Lianyungang and Japan populations, particularly Dandong population had experienced a sudden demographic or spatial expansion. The Pleistocene glaciations might contribute to this process.     

Large scale purification of myo-inositol monophosphate phosphatase from porcine brains

myo-Inositol monophosphate phosphatase (IMPase) has been purified 888-fold to apparent homogeneity from procine brains. The purification procedure involves: homogenization, ammonium sulfate fractionation, and a number of ion-exchange and gel-filtration chromatography steps. The purified enzyme exhibited a final specific activity of 932 nmol . min(-1) . mg(-1). The molecular mass of the enzyme was estimated to be 29kDa by SDS poly-acrylamide gel electrophoresis and 58 +/- 5 kDa by HPLC gel filtration in 10mM Tris-HCI, pH 7.4. Kinetic measurements have shown that the apparent K(m) value of the phosphatase for the utilization of inositol-1-phosphate and beta-glycerol phosphate are 3.20 x 10(-4) and 8 x 10(-3) M, respectively. Similar to the same enzyme isolated from bovine brains, the porcine brain enzyme has been shown to be inhibited by lithium. The K(1) was determined to be 6.38 x 10(-4) M and the inhibition is uncompetitive. (c) 1995 John Wiley & Sons, Inc.     

北京城市蝴蝶蜜源植物网络特征及重要蜜源植物识别

物种间相互作用网络研究能为物种多样性的保护、城市生态系统稳定性的维持提供指导。基于群落水平的城市蝴蝶蜜源植物互作网络的研究较少,对城市蝴蝶蜜源网络结构缺乏深入认识。研究在国内城市生态系统中构建蝴蝶蜜源网络,并探讨不同类型植物对网络特征的影响。2020年6-9月,在北京26个城市公园中记录访花蝴蝶和蜜源植物物种及互作频次,采用交互多样性（ID）、交互均匀性（IE）、专业化程度（H2''）定量化生态网络结构特征,采用Kruskal-Wallis秩和检验和变差分解分析不同生长型、起源、栽培方式的植物类型对网络结构的影响差异。采用物种的伙伴多样性（PD）和专业化程度（d''）识别重要蜜源植物。研究结果表明：（1）北京城市公园中22种蝴蝶与81种开花植物的交互作用,形成趋于泛化的生态网络结构;（2）不同生长型及不同起源的植物-蝴蝶网络的交互多样性及专业化程度有显著差异,草本及乡土植物对丰富网络中交互多样性和支持专业性更高的蝴蝶物种具重要作用,而植物的栽培方式对蜜源网络结构影响较小;（3）伙伴多样性高且专业化程度高的植物可被视为重要蜜源植物。基于蝴蝶多样性保护的目标,在城市生态系统中,绿色空间应注重构建乡土草本植物群落,优先选择重要蜜源植物。我们的发现印证了蝴蝶-蜜源植物生态网络方法作为联结生态研究和城市绿地实践管理的有效工具,能为城市生态系统中生物多样性保护提供科学策略,具有重要意义。     

原虫穴螨属一新种(蜱螨亚纲: 虫穴螨科)

记述原虫穴螨属1新种长白原虫穴螨Prozercon changbaiensis, sp. nov..该属为我国首次记录.模式标本保存于辽宁省沈阳农业大学植物保护学院.     

Nitric oxide‐mediated regulation of ‐amyloid clearance via alterations of MMP‐9/TIMP‐1

Fibrillar amyloid plaques are largely composed of amyloid‐beta (Aβ) peptides that are metabolized into products, including Aβ1‐16, by proteases including matrix metalloproteinase 9 (MMP‐9). The balance between production and degradation of Aβ proteins is critical to amyloid accumulation and resulting disease. Regulation of MMP‐9 and its endogenous inhibitor tissue inhibitor of metalloproteinase (TIMP)‐1 by nitric oxide (NO) has been shown. We hypothesize that nitric oxide synthase (NOS2) protects against Alzheimer's disease pathology by increasing amyloid clearance through NO regulation of MMP‐9/TIMP‐1 balance. We show NO‐mediated increased MMP‐9/TIMP‐1 ratios enhanced the degradation of fibrillar Aβ in vitro, which was abolished when silenced for MMP‐9 protein translation. The in vivo relationship between MMP‐9, NO and Aβ degradation was examined by comparing an Alzheimer's disease mouse model that expresses NOS2 with a model lacking NOS2. To quantitate MMP‐9 mediated changes, we generated an antibody recognizing the Aβ1‐16 fragment, and used mass spectrometry multi‐reaction monitoring assay for detection of immunoprecipitated Aβ1‐16 peptides. Aβ1‐16 levels decreased in brain lysates lacking NOS2 when compared with strains that express human amyloid precursor protein on the NOS2 background. TIMP‐1 increased in the APPSwDI/NOS2^?/? mice with decreased MMP activity and increased amyloid burden, thereby supporting roles for NO in the regulation of MMP/TIMP balance and plaque clearance.     

Association of mitochondrial haplogroup D and risk of esophageal cancer in Taihang Mountain and Chaoshan areas in China

Both the Taihang Mountain area in north-central China and Chaoshan area in the southeastern littoral of China are areas with high risk of esophageal cancer (EC). Our previous study confirmed that populations from the two areas might share similar matrilineal backgrounds and found that mitochondrial DNA (mtDNA) haplogroup D, especially subhaplogroups D4a and D5a, might be genetic background markers of EC in Chaoshan area. Here, to further determine whether D4a, D5a, and D might be susceptibility markers for EC in the two high-risk areas, we performed a case–control study with larger samples and analyzed the distributions of these three haplogroups in subjects (controls [n = 898] and patients [n = 768]) from the two areas. D4a haplogroup was significantly associated with increased risk of EC in Taihang Mountain subjects, especially women. D5 haplogroup was associated with EC at the general population level in the Taihang Mountain area and in subjects ≤ 60 years, especially women ≤ 60 years, in the Chaoshan area. D haplogroup was associated with EC only in subjects ≤ 60 years, especially men ≤ 60 years, in the Chaoshan area. D4a and D5 showing positive association with EC in the Taihang Mountain area became the predominant subhaplogroups of D in Chaoshan controls. In conclusion, D, D4a, and D5 haplogroups might be susceptibility markers for EC in the two high-risk areas in China, particularly D4a and D5 for the Taihang Mountain area and D and D5 for the Chaoshan area.     

Epigenetic repression of microRNA-129-2 leads to overexpression of SOX4 in gastric cancer

High levels of SOX4 expression have been found in a variety of human cancers, such as lung, brain and breast cancers. However, the expression of SOX4 in gastric tissues remains unknown. The SOX4 expression was detected using immunohistochemical staining and semi-quantitative RT-PCR, and our results showed that SOX4 was up-regulated in gastric cancer compared to benign gastric tissues. To further elucidate the molecular mechanisms underlying up-regulation of SOX4 in gastric cancers, we analyzed the expression of microRNA-129-2 (miR-129-2) gene, the epigenetic repression of which leads to overexpression of SOX4 in endometrial cancer. We found that up-regulation of SOX4 was inversely associated with the epigenetic silencing of miR-129-2 in gastric cancer, and restoration of miR-129-2 down-regulated SOX4 expression. We also found that inactivation of SOX4 by siRNA and restoration of miR-129-2 induced apoptosis in gastric cancer cells.