利用RAPD标记分析濒危植物白豆杉种群的遗传结构

以我国特有的濒危裸子植物白豆杉为材料,采用RAPD标记对其分布于浙江、江西、湖南和广西的11个天然种群予以检测,通过贝叶斯法估测了种群的遗传分化程度,并和由其他算法得出的结果进行了比较.求出的θ^B（Hickory）、GST（Nei）及φST（AMOVA）值分别为0.5018、0.5865和0.5436;而经由Shannon指数计算出的种群间遗传多样性所占比例为0.4839,同贝叶斯法估计出的结果最为接近.和其他松杉类植物相比,白豆杉种群间发生了极其显著的遗传分化,这可能是因为：（1）种群长期处于星散分布状态;（2）雌雄异株,而生于林下的雌株经常不能正常受粉;（3）种群取样跨越的地理范围宽广.Mantel检验表明,种群间的遗传分化程度和地理距离之间显著相关（r=0.719,P=0.003）.此外还发现白豆杉的遗传变异水平偏低,推测瓶颈效应和遗传漂变对小种群的作用是造成这一后果的重要因素.对白豆杉种群的保育和管理提出了建议.     

宁夏盐池近年来植被与气候变化分析

使用1981年到2004年的植被指数（NDVI）资料,分析了盐池县植被指数的历史演变情况,发现从1981年以来植被覆盖的状况在变好,尤其是近4a的春季最明显,植被指数在0.2～0.3级别的年平均面积较前20a增大了1.9倍（887km^2）.统计分析发现年平均NDVI与降水量、气温、相对湿度呈正相关,与蒸发量呈负相关,并且植被覆盖增加对能见度改善的影响非常显著.从季节平均来看,春季的降水与夏季的NDVI、夏季降水与秋季的NDVI具有显著的正相关,夏季降水是决定夏季和秋季以及全年植被覆盖的关键因子.     

Cloning,over-expression and characterization of a thermo-tolerant xylanase from Thermotoga thermarum

The xyn10B gene, encoding the endo-1,4-β-xylanase Xyn10B from Thermotoga thermarum, was cloned and expressed in Escherichia coli. The ORF of the xyn10B was 1,095 bp and encoded to mature peptide of 344 amino acids with a calculated MW of 40,531 Da. The recombinant xylanase was optimally active at 80 °C, pH 6.0 and retained approx. 60 % of its activity after 2 h at 75 °C. Apparent K _m , k _cat and k _cat /K _m values of the xylanase for beechwood xylan were 1.8 mg ml^?1, 520 s^?1 and 289 ml mg^?1 s^?1, respectively. The end products of the hydrolysis of beechwood xylan were mainly oligosaccharides but without xylose after 2 h hydrolysis.     

Endoplasmic reticulum stress and autophagy are involved in adipocyte-induced fibrosis in hepatic stellate cells

Liver fibrosis, with the characterization of progressive accumulation of extracellular matrix (ECM), is the common pathologic feature in the process of chronic liver disease. Hepatic stellate cells (HSCs) which are activated and differentiate into proliferative and contractile myofibroblasts are recognized as the main drivers of fibrosis. Obesity-related adipocytokine dysregulation is known to accelerate liver fibrosis progression, but the direct fibrogenic effect of mature adipocytes on HSCs has been rarely reported. Therefore, the purpose of this study was to explore the fibrogenic effect of adipocyte 3T3-L1 cells on hepatic stellate LX-2 cells. The results showed that incubating LX-2 cells with the supernatant of 3T3-L1 adipocytes triggered the expression of ECM related proteins, such as α-smooth muscle actin (α-SMA), type I collagen (CO-I), and activated TGF β/Smad2/3 signaling pathway in LX-2 cells. In addition, 3T3-L1 cells inhibited insulin sensitivity, activated endoplasmic reticulum stress and autophagy to promote the development of fibrosis. These results supported the notion that mature adipocytes can directly activate hepatic stellate cells, and the establishment of an in vitro model of adipocytes on HSCs provides an insight into screening of drugs for liver diseases, such as nonalcoholic fatty liver disease.

     

Immunoaffinity purification of plasma membrane with secondary antibody superparamagnetic beads for proteomic analysis

Plasma membrane (PM) has very important roles in cell-cell interaction and signal transduction, and it has been extensively targeted for drug design. A major prerequisite for the analysis of PM proteome is the preparation of PM with high purity. Density gradient centrifugation has been commonly employed to isolate PM, but it often occurred with contamination of internal membrane. Here we describe a method for plasma membrane purification using second antibody superparamagnetic beads that combines subcellular fractionation and immunoisolation strategies. Four methods of immunoaffinity were compared, and the variation of crude plasma membrane (CPM), superparamagnetic beads, and antibodies was studied. The optimized method and the number of CPM, beads, and antibodies suitable for proteome analysis were obtained. The PM of mouse liver was enriched 3-fold in comparison with the density gradient centrifugation method, and contamination from mitochondria was reduced 2-fold. The PM protein bands were extracted and trypsin-digested, and the resulting peptides were resolved and characterized by MALDI-TOF-TOF and ESI-Q-TOF, respectively. Mascot software was used to analyze the data against IPI-mouse protein database. Nonredundant proteins (248) were identified, of which 67% are PM or PM-related proteins. No endoplasmic reticulum (ER) or nuclear proteins were identified according to the GO annotation in the optimized method. Our protocol represents a simple, economic, and reproducible tool for the proteomic characterization of liver plasma membrane.     

High ISSR Variation in 14 Surviving Individuals of Euryodendron excelsum (Ternstroemiaceae) Endemic to China

Euryodendron excelsum is a critically endangered Ternstroemiaceae species endemic to southern China, with only 14 individuals surviving in Ba Jia Zhen of Yangchun, Guangdong Province. Intersimple sequence repeat (ISSR) markers were used to assess genetic variation and relationships among these individuals. Population genetic parameters were estimated by a Bayesian approach as well as conventional methods. Of the 225 loci generated by 21 primers, 147 (65.33%) were polymorphic. Compared with other species of Theaceae and related families, a high level of genetic variation was identified in E. excelsum (Nei’s gene diversity, 0.2458; Shannon’s index, 0.3626). An unweighted pair group method with arithmetic mean (UPGMA) dendrogram showed that the 14 individuals were mainly clustered into three groups, a conclusion further supported by principal coordinate analysis. Based on these results, a management and conservation strategy for E. excelsum was proposed.     

褪黑素合成酶基因转化烟草及转化植株抗氧化系统变化

通过根癌农杆菌(含植物表达载体YXu55)介导的转化技术,将褪黑素生物合成酶-芳烷基胺N-乙酰转移酶(Arylalkylamine N-acetyltransferase,AANAT)与羟基吲哚O-甲基转移酶(Hydroxyindole O-methyltransferase,HIOMT)基因导入到烟草(秦烟95)中。对所获得的庆大霉素抗性烟草株系进行Southern blotting和RT-PCR分子生物学检测,结果表明,AANAT-HIOMT基因已成功地整合到烟草基因组中,并且可以在mRNA水平上进行转录。用反相高效液相色谱法(RP-HPLC)测定转化株系的褪黑素含量表明,转AANAT-HIOMT基因烟草株系的褪黑素含量均明显高于pZP122(不含AANAT和HIOMT基因的空白质粒)转基因株系和未转基因的对照植株,证明AANAT-HIOMT基因在转基因植株中的表达增强了褪黑素的合成能力。对不同株系抗氧化系统的部分指标进行了测定,并与其亲本对照植株比较,发现AANAT-HIOMT基因在转基因植物中的表达引起超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性增加,谷胱甘肽(GSH)浓度...