Genetic and transformation studies reveal negative regulation of ERS1 ethylene receptor signaling in Arabidopsis

Background  

Ethylene receptor single mutants of Arabidopsis do not display a visibly prominent phenotype, but mutants defective in multiple ethylene receptors exhibit a constitutive ethylene response phenotype. It is inferred that ethylene responses in Arabidopsis are negatively regulated by five functionally redundant ethylene receptors. However, genetic redundancy limits further study of individual receptors and possible receptor interactions. Here, we examined the ethylene response phenotype in two quadruple receptor knockout mutants, (ETR1) ers1 etr2 ein4 ers2 and (ERS1) etr1 etr2 ein4 ers2, to unravel the functions of ETR1 and ERS1. Their functions were also reciprocally inferred from phenotypes of mutants lacking ETR1 or ERS1. Receptor protein levels are correlated with receptor gene expression. Expression levels of the remaining wild-type receptor genes were examined to estimate the receptor amount in each receptor mutant, and to evaluate if effects of ers1 mutations on the ethylene response phenotype were due to receptor functional compensation. As ers1 and ers2 are in the Wassilewskija (Ws) ecotype and etr1, etr2, and ein4 are in the Columbia (Col-0) ecotype, possible effects of ecotype mixture on ethylene responses were also investigated.     

Targeting the angiotensin II type 2 receptor (AT2R) in colorectal liver metastases

Background  

Blockade of the angiotensin (ANG) II type 1 receptor (AT1R) inhibits tumour growth in several cancers, including colorectal cancer (CRC) liver metastases. While AT1R blockade has been extensively studied, the potential of targeting the antagonistically acting AT2R in cancer has not been investigated. This study examined the effect of AT2R activation with the agonist CGP42112A in a mouse model of CRC liver metastases.     

不同佐剂对含S+PreS1融合抗原的乙型肝炎病毒颗粒疫苗免疫原性的影响

本研究在前期工作基础上,用CHO细胞表达的含PreS1+S融合抗原的新型基因工程HBV颗粒疫苗(HBSS1)与Al(OH)3、CpG及CpG+Al(OH)3等佐剂配伍,在Balb/C小鼠模型上研究不同佐剂对HBV颗粒疫苗肌肉注射后免疫应答的影响,主要包括抗体滴度、抗体亚型分类及特异性细胞免疫(γ-IFNELISpot检测)。结果表明:CpG佐剂结合HBSS1颗粒疫苗可快速诱导(单针免疫)高水平的抗PreS1及S抗体,IgG2a/IgG1比率1,同时可诱导较高抗原特异的细胞免疫应答;Al(OH)3+CpG双佐剂组一次免疫后可诱导产生最高的抗S抗体滴度(1:105),其产生的抗体亚类包括IgG1、IgG2a与IgG2b;在S抗原N端(13~49aa)存在优势CTL表位。结论:CpG佐剂结合HBSS1颗粒疫苗应是发展新型治疗性乙肝疫苗的较佳选项。     

青藏高原东缘11种小檗属(Berberis)植物种子萌发特性

在实验室条件下研究了青藏高原东缘11种小檗属(Berberis)植物的种子萌发特性,并分析了种子萌发能力与种子大小和海拔之间的关系。结果表明,11种植物中,仅有5种植物(金花小檗、匙叶小檗、锥花小檗、鲜黄小檗和刺黄花)种子萌发率超过50%,其中金花小檗最高(86.7%);有2种植物(巴东小檗、华西小檗)种子始终没有萌发,其余4种植物种子萌发率均在10%以下;种子萌发开始时间均在10d以后,匙叶小檗种子萌发的持续时间最长(40d)。11种植物种子萌发率、萌发速率、萌发持续时间与种子大小均呈显著负相关,而萌发开始时间与种子大小之间具有显著的正相关关系。萌发率、萌发速率、萌发持续时间与海拔均有较弱的正关联,萌发开始时间与海拔有较弱的负关联。     

猪流行性腹泻病毒地方株LJB/03分离及培养特性

从黑龙江省某猪场疑为病毒性腹泻的发病猪采集腹泻粪便样品,以RT-PCR法扩增出猪流行性腹泻病毒M基因后,采用细胞培养法进行病毒分离。对细胞培养分离物进行间接免疫荧光、免疫电镜观察、RT-PCR及ELISA法检验,其中间接免疫荧光试验可见培养细胞中存在明显的特异性绿色荧光;免疫电镜下可见大小符合预期、有囊膜、花瓣状的典型冠状病毒结构特征;RT-PCR检测证实存在PEDVM基因;间接ELISA检测中平均P/N比值为7.6;从而确认为分离到一株猪流行性腹泻病毒(Porcine epidemic diarrhea virus,PEDV),命名为PEDVLJB/03株。随后,对该分离毒株的培养特性及如何提高病毒滴度进行探索。通过摸索该分离毒株的蚀斑形成条件,建立了PEDV蚀斑形成方法,并采用该方法进行病毒的蚀斑纯化,纯化得到PEDV大蚀斑克隆株和小蚀斑克隆株。对大、小两种蚀斑克隆株的病毒滴度测定结果表明,大小蚀斑克隆株细胞感染滴度相差明显。     

表达人高致病性禽流感病毒H5N1(安徽株)结构基因的DNA疫苗在小鼠中诱导的免疫应答分析

本研究旨在研发经济、高效的人高致病性禽流感病毒H5N1实验疫苗并优化免疫方案。首先优化并合成H5N1(安徽株)的血凝素基因(HAop)和神经氨酸酶基因(NAop)并证实其正确表达,再构建含有H5N1(安徽株)结构基因的多个单顺反子(HAwt、HAop和NAop)和双顺反子(HAop/M2和NAop/M1)DNA疫苗质粒。随后,采用不同途径的体内电转法在第0周和第3周2次免疫Balb/C小鼠,初步分析了抗原特异性体液免疫(HA血凝抑制抗体,NA特异性抗体,中和抗体)和细胞免疫应答(IFN-γELISpot)的特点。结果表明:含有优化血凝素基因(HAop)和优化神经氨酸酶基因(NAop)的DNA疫苗可以快速激发较强的免疫应答,尤其是细胞免疫应答;皮内电转所激发的体液免疫应答强于肌肉电转。本研究为新型H5N1疫苗的研发以及免疫方案的优化奠定了基础。     

益坤宁对围绝经期大鼠卵巢细胞凋亡率及caspase-3表达的影响

目的:研究中药益坤宁(yikunning,YKN)对围绝经期大鼠卵巢细胞凋亡率及凋亡相关基因caspase-3基因表达的影响,探讨益坤宁治疗围绝经期综合征的作用机理。方法:选用30只自然衰老的围绝经期雌性大鼠,随机分为中药益坤宁实验组、围绝经期对照组和利维爱(livial)对照组,另选10只青年雌性大鼠作为青年对照组。连续灌胃处理4周后,采用原位脱氧核糖核苷酸末端转移酶介导的缺口末端标记(TUNEL)法检测大鼠卵巢细胞凋亡率,采用逆转录-聚合酶链反应(RT-PCR)和蛋白印迹(Western blot)检测大鼠卵巢中caspase-3 mRNA和蛋白表达。结果:益坤宁组大鼠卵巢细胞凋亡率显著低于围绝经期对照组(P0.01);益坤宁组大鼠卵巢中caspase-3 mRNA和蛋白表达低于围绝经期对照组,高于青年对照组,差异有统计学意义(P0.01)。结论:中药益坤宁通过降低围绝经期大鼠卵巢细胞凋亡率,下调卵巢中凋亡相关基因caspase-3的表达,从而延缓卵巢衰老,这可能是其治疗围绝经期综合征的分子机制之一。     

2-氧代-4-苯基丁酸乙酯还原酶产生菌筛选及产酶条件

研究了利用生物催化不对称还原的方法制备(R)-2-羟基-4-苯基丁酸乙酯[(R)-HPBE]。以2-氧代-4-苯基丁酸乙酯(OPBE)为底物,通过对实验室保藏菌株进行筛选,得到一株产物立体选择性较高的菌株G2ndida krusei SW2026,并对其发酵产酶条件进行研究。其最适的发酵培养基组成为4.5%葡萄糖,3%蛋白胨,1.5%牛肉膏,0.05%Mn~(2+);适宜的产酶发酵条件为初始pH 6.0,温度28℃,摇床转速180 r/min,发酵周期48 h。将此条件下发酵培养的菌体用于OPBE的不对称还原反应,产物(R)-HPBE的对映体过量值(e.e.)可达97.33%,产率最高达到72.54%。     

5'-to-3' exoribonuclease activity in bacteria: role of RNase J1 in rRNA maturation and 5' stability of mRNA

Although the primary mechanism of eukaryotic messenger RNA decay is exoribonucleolytic degradation in the 5'-to-3' orientation, it has been widely accepted that Bacteria can only degrade RNAs with the opposite polarity, i.e. 3' to 5'. Here we show that maturation of the 5' side of Bacillus subtilis 16S ribosomal RNA occurs via a 5'-to-3' exonucleolytic pathway, catalyzed by the widely distributed essential ribonuclease RNase J1. The presence of a 5'-to-3' exoribonuclease activity in B. subtilis suggested an explanation for the phenomenon whereby mRNAs in this organism are stabilized for great distances downstream of "roadblocks" such as stalled ribosomes or stable secondary structures, whereas upstream sequences are never detected. We show that a 30S ribosomal subunit bound to a Shine Dalgarno-like element (Stab-SD) in the cryIIIA mRNA blocks exonucleolytic progression of RNase J1, accounting for the stabilizing effect of this element in vivo.     

Bacterial Diversity in Mine Tailings Compared by Cultivation and Cultivation-independent Methods and their Resistance to Lead and Cadmium

To examine bacterial community composition in rhizosphere of plants colonizing on mine tailings and phylogenetic differences between subcommunities resistant to different metals, we constructed four clone libraries of 16S rDNA sequences. One was amplified directly from tailing microbial DNA (named as Ci library) and three from cultures on the plates containing of 0.5 mM CdCl(2) (Cd library), 2 mM Pb (NO(3))(2) (Pb library), and without any metals (Cw library). In total, nine bacterial divisions and two unclassified groups were identified from 352 clones of these libraries. Ci clones covered eight divisions, whereas all cultivable clones only covered four divisions. Thus, Ci library provided more phylogenetic diversity than cultivable libraries. However, the microbes represented by the cultivable clones were more similar to previously described bacteria than those represented by Ci clones. All Ci clones were not found in three cultivable libraries. Cd library were exclusively Gram-negative bacteria of Acinetobacter, Ralstonia, Comamonas, and Chryseobacterium. Meanwhile, dominant Gram-positive bacteria in Pb library, Paenibacillus and Bacillus, were also not found in Cd library. Our data indicate that phylogenetic structure was very different from those in acid mine drainage. Meanwhile, tailings harbored phylogenetically distinct subcommunities resistant to Pb and Cd.