内蒙古锡林河流域主要类型草原土壤中CH_4和CO_2浓度的变化

于 1999年生长季对内蒙古锡林河流域主要类型草原土壤中 CH4和 CO2 浓度进行测定 ,结果表明 :CH4浓度沿土壤剖面逐渐降低 ,而且不同土壤深度之间差异显著 ,而 CO2 浓度呈现出沿土壤剖面增加的趋势。草甸草原、羊草 (L eymus chinesis)草原和大针茅 (Stipa grandis)草原土壤中 CH4的浓度差异显著 ,季节变化明显 ,但是三类草原土壤中 CO2 浓度变化不大。测定结果还表明 :一定时间尺度上 ,放牧对草原土壤中 CH4和 CO2 的浓度没有显著影响。     

以麦秸为基质豌豆根瘤菌的压力脉动固态发酵

生物肥料的常规生产方法是经液态发酵后 ,再以固态基质吸附[1 ] 。其工艺繁琐 ,吸附时易引入大量杂菌 ,从而降低生物肥料的施用效果。而由于静止浅盘固态发酵存在着较大的氧气浓度和温度梯度[2 ,3 ] ,及易染菌等因素 ,所以利用固态发酵成功生产生物肥料的研究较少。近年来 ,固态发酵以其优于液态发酵的特点而成为人们研究的热点[4] ,但至今仍未能普遍应用于工业生产。其主要原因是固态发酵反应器在放大过程中传质、传热困难[3 ] 。Ｂａｊｒａｃｈａｒｙａ＆Ｍｕｄｇｅｔｔ[5 ] 指出 ,解决上述弊端的唯一可行的方法是对反应器中的气相进行控…     

链格孢菌毒素对紫茎泽兰的致病机理

以叶圆片法分析链格孢菌[Alternaria alternata(Fr.)Keissler]毒素对紫茎泽兰（Eupatorium adenophorum Spreng.)叶组织细胞膜透性、过氧化物酶（POD）、抗坏血酸过氧化物酶（APX）和过氧化氢酶（CAT）活性以及丙二醛（MDA）含量的影响,结果表明,链格孢菌毒素使紫茎泽兰叶组织细胞膜透性上升,Na^ 和K^ 渗漏量增加,膜脂过氧化加强,MDA含量上升;链格孢菌毒素处理的紫茎泽兰叶片中POD、APX和CAT的活性均较对照降低。     

环颈雉胃的血供

用血管铸型法和大体解剖学方法对环颈雉胃动脉的起源、分布及胃静脉的回流情况进行了解剖学研究。结果表明,环颈雉的胃动脉均由腹腔动脉分出;腺胃由腺胃背侧动脉和腺胃腹侧动脉营养,腺胃背侧动脉直接起自腹腔动态的左侧,腺胃腹侧动脉起自腹腔动脉左支。腺胃血液的静脉有腺胃前静脉和腺胃后静脉,分别汇入后腔静脉和左肝门静脉。肌胃由肌胃左动脉、肌胃右动脉和肌胃背侧动脉营养,肌胃左动脉起自腹腔动脉的左支;肌胃右动脉起自腹腔动脉的右支;肌胃背侧动脉从腺胃背动脉分支而来。回流肌胃血液的静脉有胃右静脉、胃左静脉和胃腹侧静脉;胃右静脉汇入右肝门静脉,胃左静脉和胃腹侧静脉汇入左肝门静脉。另外腺胃和肌胃的表面缺乏主干动脉间的吻合。     

Fudenine, a C-terminal truncated rat homologue of mouse prominin, is blood glucose-regulated and can up-regulate the expression of GAPDH

Messenger RNA differential display was applied to screen for the blood glucose-regulated genes in SD rat skeletal muscle. The rat homologue of the mouse prominin was thus identified. Comparing to its mouse and human homologues, fudenine was C-terminal truncated due to a single nucleotide deletion. However, its mitochondrial energy transfer signature peptide PQDLVKKLI remained intact. Fudenine, an 592-amino acid containing, 66-kDa glycoprotein, is a novel plasma membrane protein with four transmembrane segments flanking by two large glycosylated extracellular domains. Although it is devoid of the last transmembrane domain comparing to its homologues, fudenine also locates in cell membrane by transfection of fusion plasmid pFudenine-EGFP into CBRH7919 cell and L-6TG cell. Overexpression of fudenine in CBRH7919 cell line up-regulated the mRNA level of GAPDH (3-phosphate glyceraldehyde dehydrogenase), while long-term glucose exposure resulted to reduced GAPDH expression. Since high blood glucose level induced the expression of fudenine in skeletal muscle, which in turn up-regulated the expression of GAPDH, we propose that fudenine might be a candidate gene for diabetes mellitus.     

Cajal细胞与胃肠起搏

存在于胃肠平滑肌内的Cajal间质细胞（ＩＣＣ）与胃肠道运动的发生和控制密切相关。ＩＣＣ可自发激活并产生节律性去极化慢波（ＳＷ）,经由ＩＣＣ形成的网络传向平滑肌细胞,并向远端扩布。平滑肌细胞缺乏产生ＳＷ活动的必要离子基础,但对于由ＩＣＣ传来的ＳＷ产生反应,使ＳＷ增强或诱发动作电位和收缩活动。因此,ＩＣＣ不仅是胃肠ＳＷ活动的起搏者,也是ＳＷ的传播者,同时对神经递质等生物活性物质影响平滑肌收缩起着居间调制作用。     

Analyses of the genomic methylation status of the human cyclin A1 promoter by a novel real-time PCR-based methodology

The role of CpG methylation in the regulation of tissue-specific gene expression is highly controversial. Cyclin A1 is a tissue-specifically expressed gene that is strongly methylated in non-expressing tumor cell lines. We have established a novel real-time PCR method to quantitate genomic CpG methylation of the cyclin A1 promoter. Genomic DNA samples from different human organs were treated with bisulfite and amplified with methylation-specific primers and with primers amplifying methylated as well as non-methylated DNA. PCR product quantitation was obtained by using a fluorogenic probe labeled with FAM and TAMRA. These analyses demonstrated that the human cyclin A1 promoter was methylated in kidney, colon, spleen, testis, and small intestine, but not in brain, liver, pancreas, or heart. Expression of cyclin A1 was predominantly found in testis. Low level expression of cyclin A1 was present in spleen, prostate, leukocytes, colon, and thymus. Taken together, our data provide evidence that CpG methylation patterns of the human cyclin A1 promoter in human organs do not generally correlate with cyclin A1 gene expression in vivo.     

Oxidants and skeletal muscle function: physiologic and pathophysiologic implications

Previous studies have demonstrated that skeletal muscles generate considerable reactive oxygen during intense muscle contraction. However, the significance of this phenomenon and whether it represents normal physiology or pathology are poorly understood. Treatment with exogenous antioxidants suggests that normal redox tone during contraction is influencing ongoing contractile function, both at rest and during intense exercise. This could represent the influence of redox-sensitive proteins responsible for excitation-contraction coupling or redox-sensitive metabolic enzymes. Some conditions associated with intense exercise, such as local tissue hypoxia or elevated tissue temperatures, could also contribute to reactive oxygen production. Evidence that muscle conditioning results in upregulation of antioxidant defenses also suggests a close relationship between reactive oxygen and contractile activity. Therefore, there appears to be a significant role for reactive oxygen in normal muscle physiology. However, a number of conditions may lead to an imbalance of oxidant production and antioxidant defense, and these, presumably, do create conditions of oxidant stress. Ischemia-reperfusion, severe hypoxia, severe heat stress, septic shock, and stretch-induced injury may all lead to oxidant-mediated injury to myocytes, resulting in mechanical dysfunction.     

Monitoring genome-wide changes in gene expression in response to endogenous cytokinin reveals targets in Arabidopsis thaliana

Cytokinins have been implicated in developmental and growth processes in plants including cell division, chloroplast biogenesis, shoot meristem initiation and senescence. The regulation of these processes requires changes in cytokinin-responsive gene expression. Here, we induced the expression of a bacterial isopentenyl transferase gene, IPT, in transgenic Arabidopsis thaliana seedlings to study the regulation of genome-wide gene expression in response to endogenous cytokinin. Using MPSS (massively parallel signature sequencing) we identified 823 and 917 genes that were up- and downregulated, respectively, following 24 h of IPT induction. When comparing the response to cytokinin after 6 and 24 h, we identified different clusters of genes showing a similar course of regulation. Our study provides researchers with the opportunity to rapidly assess whether genes of interest are regulated by cytokinins.     

Glucose deprivation induces mitochondrial dysfunction and oxidative stress in PC12 cell line

Glucose metabolism plays a pivotal role in many physiological and pathological conditions. To investigate the effect of hypoglycemia (obtained by glucose deprivation) on PC12 cell line, we analyzed the cell viability, mitochondrial function (assessed by MTT reduction, cellular ATP level, mitochondrial transmembrane potential), and the level of reactive oxygen species (ROS) after glucose deprivation (GD). Upon exposure to GD, ROS level increased and MTT reduction decreased immediately, intracellular ATP level increased in the first 3 hours, followed by progressive decrease till the end of GD treatment, and the mitochondrial transmembrane potential (ΔΨ_m) dropped after 6 hours. Both necrosis and apoptosis occurred apparently after 24 hours which was determined by nuclei staining with propidium iodide(PI) and Hoechst 33342. These data suggested that cytotoxity of GD is mainly due to ROS accumulation and ATP depletion in PC12 cells.