Effects of SARA on Oxygen–Glucose Deprivation in PC12 Cell Line

Ischemic stroke is a major composition of cerebrovascular disease, seriously threatening to human health in the world. Activin A (ActA), belonging to transforming growth factor-beta (TGF-β) super family, plays an important role in the hypoxic-ischemic brain injury through ActA/Smads pathway. While as an essential phosphorylation assistor in TGF-β signaling, the functions and mechanisms of smad anchor for receptor activation (SARA) in ischemic brain injury remain poorly understood. To solve this problem and explore the pathological processes of ischemic stroke, we used an Oxygen–Glucose deprivation (OGD) model in nerve growth factor-induced differentiated rattus PC12 pheochromocytoma cells and down regulated the expressions of SARA by RNA interference technology. Our results showed that the repression of SARA before OGD exposure reduced the expressions of Smad2, 3, 4 mRNA and the phosphorylation rate of Smad2 protein, but it did not affect the mRNA expressions of Smad7. After OGD treatment, ActA/Smads pathway was activated and the expression of SARA in the SARA pre-repression group was significantly up-regulated. The pre-repression of SARA increased the sensitivities of nerve-like cells to OGD damage. Moreover, the mRNA expression of Smad7 which was supposed to participate in the negative feedback of ActA/Smads pathway was also elevated due to OGD injury. Taken together, these results suggest a positive role of SARA in assisting the phosphorylation of Smad2 and maintaining the neuron protective effect of ActA/Smads pathway.     

Degradation of toluene and m-xylene and transformation of o-xylene by denitrifying enrichment cultures

Seven different sources of inocula that included sediments, contaminated soils, groundwater, process effluent, and sludge were used to establish enrichment cultures of denitrifying bacteria on benzene, toluene, and xylenes in the absence of molecular oxygen. All of the enrichment cultures demonstrated complete depletion of toluene and partial depletion of o-xylene within 3 months of incubation. The depletion of o-xylene was correlated to and dependent on the metabolism of toluene. No losses of benzene, p-xylene, or m-xylene were observed in these initial enrichment cultures. However, m-xylene was degraded by a subculture that was incubated on m-xylene alone. Complete carbon, nitrogen, and electron balances were determined for the degradation of toluene and m-xylene. These balances showed that these compounds were mineralized with greater than 50% conversion to CO2 and significant assimilation into biomass. Additionally, the oxidation of these compounds was shown to be dependent on nitrate reduction and denitrification. These microbial degradative capabilities appear to be widespread, since the widely varied inoculum sources all yielded similar results.     

Anaerobic degradation of toluene by a denitrifying bacterium

A denitrifying bacterium, designated strain T1, that grew with toluene as the sole source of carbon under anaerobic conditions was isolated. The type of agar used in solid media and the toxicity of toluene were determinative factors in the successful isolation of strain T1. Greater than 50% of the toluene carbon was oxidized to CO2, and 29% was assimilated into biomass. The oxidation of toluene to CO2 was stoichiometrically coupled to nitrate reduction and denitrification. Strain T1 was tolerant of and grew on 3 mM toluene after a lag phase. The rate of toluene degradation was 1.8 mumol min-1 liter-1 (56 nmol min-1 mg of protein-1) in a cell suspension. Strain T1 was distinct from other bacteria that oxidize toluene anaerobically, but it may utilize a similar biochemical pathway of oxidation. In addition, o-xylene was transformed to a metabolite in the presence of toluene but did not serve as the sole source of carbon for growth of strain T1. This transformation was dependent on the degradation of toluene.     

南方菜豆花叶病毒外壳蛋白基因序列的分析

用重组DNA技术及序列分析法测定了南方菜豆花叶病毒RNA基因组3′端1,000个碱基的序列,以及由此序列推导出的整个外壳蛋白的氨基酸顺序,它与巳报导的基本上一致。介绍了用DNA的寡核苷酸水解混合物作为起始引物,以3′端不含PolyA尾巴且不能加上PolyA的病毒RNA作为模板合成互补DNA,及进一步无性繁殖此cDNA的方法。     

大麦条纹花叶病毒新疆株(BSMV-XJ)RNA_2的cDNA克隆及5′端序列分析

分离了大麦条纹花叶病毒(BSMV)新疆株基因组的3个RNA组份。以RNA2为模板,3′端互补寡核苷酸为引物,合成了第一条cDNA链和第二条cDNA链,将ds-cDNA重组在pUC9质粒中,转化大肠杆菌细胞,获得含RNA3′端的克隆,并证明所选克隆的cDNA含有新疆株几近全长的RNA2组份。对于插入片段为3.3kbp的112号克隆进行了酶谱分析,得到了与国外典型株类似的结果;用双脱氧终止法分析了相当于RNA 2 5′端250bp的cDNA酶切片段,表明与国外典型株有十分相似的一级结构。     

苏云金芽孢杆菌δ-内毒素基因穿梭质粒的构建

在农业生产中长期使用化学农药已对环境和生态平衡造成一定破坏作用,同时有不少害虫也逐渐产生抗药性从而引起某些害虫的大流行,给农业生产带来巨大损失。应用苏云金杆菌杀虫蛋白基因(Bt基因)可构建具有抗虫作用的抗虫工程菌,这样通过拌种或植物叶面喷雾可达到快速、经济、有效的防治虫害的目的。国际上抗虫工程菌研究应用很快,如美国将BI基因转入到一种正常情况下定居在植物组织中的棒杆菌,将这种工程菌拌玉米种子,这样随植物生长该菌在植物体内大量繁殖,当玉米螟在茎和叶取食时,即因食用表达苏云金杆菌毒蛋白的工程菌而死亡。 田颖川等已克隆了苏云金芽孢杆菌内毒素基因CryIA(b)和CryIA(c)。本文将Bt基因CryIA(c)插入到大肠-枯草穿梭载体pBE-2中构建成Bt毒蛋白基因穿梭质粒pAMY,利用电穿孔法转人大肠杆菌DH5a,枯草芽孢杆菌B.subtilis BR151,IA511,野生型蜡状芽孢杆菌B.cereusa-47,短芽孢杆菌B.brevis A-5和枯草芽孢杆菌90-8,获得了具有较高杀虫活性的工程菌克隆。     

畜禽保种－选择指数原理

根据系统保种理论有关保种和选择可以相互结合的观点,本文提出了保种－选择指数的概念、导出了适于各种资料条件和各种保种与选择目的的通用保种－选择指数公式、并探讨了该公式在几种特殊情况下的形式,为国内大量地方品种保种选育提供了必要的理论和方法。     

电脉冲穿孔法将苏云金杆菌δ-内毒素基因导入野生型芽孢杆菌

利用电脉冲穿孔法将带有苏云金杆菌毒蛋白基因的穿梭质粒导入几株野生型芽孢杆菌中。它们是野生型的蜡状芽孢杆菌、短芽孢杆菌和枯草芽孢杆菌。通过观察在新霉素和氨苄青霉素平板上长出的抗性菌落数,计算出转化效率为10~1—10~4转化子/μgDNA。从转化子中分离到的质粒DNA大小及其用HindⅢ酶切的片段与原始质粒DNA相同,毒性测试表明重组转化子对烟青虫六天的致死率达90—100％。     

番木瓜环斑病毒复制酶(亚基)基因的克隆、序列分析及其植物表达载体的构建

近二年报道,在TMV^⑴、PVX^⑵、PEBV^⑶和CMV^⑷等病毒中,利用病毒编码的复制酶(亚基)基因或相关cDNA片段转化烟草,工程植株获得绝对或极高的病毒抗性。大量研究认为：马铃薯Y病毒组的核内含体大分子量蛋白(Nib)是依赖于RNA的RNA复制酶(或核心亚基),Nlb与上述病毒的复制酶有广泛的同源保守区^⑸。因此,Nib基因的克隆,不但在植物抗病基因工程方面,而且在马铃薯Y病毒组基因组的复制研究方面．均有重要的意义。本文以马铃薯Y病毒组的重要成员番木瓜环斑病毒的华南强株系(PRSV—sM)为材料,克隆了PRSV的Nib基因,并完成其全序列测定和植物表达载体的构建,为探索马铃薯Y病毒组复制酶可能介导的抗病性打下了基础。