The cry3Aa gene of Bacillus thuringiensis Bt886 encodes a toxin against long-horned beetles

This report describes the identification of a new toxigenic strain of Bacillus thuringiensis specific for long-horned beetles. B. thuringiensis Bt866 encodes a cry3Aa-like gene (Bt886cry3Aa) that is 1,956 bp in length and is predicted to encode an 85.78-kDa protein. The gene is highly similar to cry3Aa1, differing in only six nucleotides and four amino acids. The four disparate amino acids occur within the conserved domains of the Cry3Aa toxin. The expression of Bt866cry3A in Escherichia coli cells resulted in a high level of toxicity toward Apriona germari Hope larvae. More than 75% of the larvae were killed; and the remaining survivors exhibited slower growth. These results indicate that the toxigenic strain Bt886cry3Aa encodes a protein that is specific against long-horned beetles. Genetic engineering of the Bt866cry3Aa gene into poplar plantations may provide resistance to long-horned beetles.     

稻纵卷叶螟羧酸酯酶基因的鉴定与表达谱分析

【目的】鉴定稻纵卷叶螟Cnaphalocrocis medinalis的羧酸酯酶基因,并检测这些基因在成虫不同组织中的表达模式。【方法】从稻纵卷叶螟转录组中搜索羧酸酯酶基因,使用生物信息学软件对所获得的基因序列进行分析,使用荧光定量PCR检测这些基因在各组织中的相对表达水平。【结果】获得了15个羧酸酯酶基因,分别命名为Cm Car E1~Cm Car E15。其中Cm Car E12缺少3′区域,其余14个序列均含有完整的开放阅读框。除Cm Car E11外,其余14个基因编码的蛋白均具有羧酸酯酶的典型特征,如保守的五肽结构域,催化三联体和氧阴离子穴等。系统进化分析显示15个Cm Car Es被聚在不同的进化支内,Cm Car E13、Cm Car E14和Cm Car E15聚在"胞内催化类"进化支,其余12个Cm Car Es聚在"分泌催化类"进化支。Cm Car E1、Cm Car E2、Cm Car E3、Cm Car E7、Cm Car E8、Cm Car E10和Cm Car E13特异表达于成虫腹部,而Cm Car E9特异表达于雌雄成虫触角。其他基因的表达没有组织特异性。【结论】Cm Car E1、Cm Car E2、Cm Car E3、Cm Car E7、Cm Car E8、Cm Car E10和Cm Car E13编码的酯酶可能参与了内外源化合物的代谢,而Cm Car E9编码的酯酶可能参与了气味分子的降解。     

Magnesium Protects Cognitive Functions and Synaptic Plasticity in Streptozotocin-Induced Sporadic Alzheimer’s Model

Alzheimer’s disease (AD) is characterized by profound synapse loss and impairments of learning and memory. Magnesium affects many biochemical mechanisms that are vital for neuronal properties and synaptic plasticity. Recent studies have demonstrated that the serum and brain magnesium levels are decreased in AD patients; however, the exact role of magnesium in AD pathogenesis remains unclear. Here, we found that the intraperitoneal administration of magnesium sulfate increased the brain magnesium levels and protected learning and memory capacities in streptozotocin-induced sporadic AD model rats. We also found that magnesium sulfate reversed impairments in long-term potentiation (LTP), dendritic abnormalities, and the impaired recruitment of synaptic proteins. Magnesium sulfate treatment also decreased tau hyperphosphorylation by increasing the inhibitory phosphorylation of GSK-3β at serine 9, thereby increasing the activity of Akt at Ser473 and PI3K at Tyr458/199, and improving insulin sensitivity. We conclude that magnesium treatment protects cognitive function and synaptic plasticity by inhibiting GSK-3β in sporadic AD model rats, which suggests a potential role for magnesium in AD therapy.     

广西地衣新记录属——炭刺文衣属

该文报道了文字衣科(Graphidaceae)地衣一广西新记录属——炭刺文衣属(Carbacanthographis).该属主要特征是子囊盘面闭合,果壳炭化,盘唇具白色粉霜层,类缘丝具疣,子囊孢子砖壁型或横隔双透镜型,I-或微I+.枯炭刺文衣,标本采自广西金秀圣堂山,该种特征是线盘明显、盘被两侧炭化、子囊孢子无色砖壁型、孢子大小(12.5-20)×(5-7.5)μm、地衣体含有水杨嗪酸.该属是中国稀有属,迄今仅有1种报道.该种首次在内陆自然环境中发现,这对于炭刺文衣属及其类群的区系研究、物种保护和利用具有很重要的意义.     

纳米基因载体在生物医学中的研究进展

纳米生物技术是21世纪具有开发前景的科技领域,纳米材料的出现为解决基因转移载体提供了新的思路,本文在阐述纳米基因载体的优势、种类及导入体内方法的基础上,综述了纳米基因载体在基因治疗、遗传育种等生物医学上的应用。     

硝酸盐和硫酸盐厌氧氧化甲烷途径及氧化菌群

甲烷属于温室气体,厌氧氧化甲烷有效地减少了大气环境中甲烷的含量。依据吉布斯自由能变,以SO42、Mn4+、Fe3+、NO3等作为电子受体,厌氧条件下甲烷可以转化为CO2。重点阐述以SO42和NO3为电子受体时甲烷厌氧氧化的机理、反应发生的环境条件以及甲烷厌氧氧化菌的特点。针对目前研究存在的主要问题,提出了今后的发展方向。SO42为电子受体时,甲烷厌氧氧化的可能途径包括:逆甲烷生成途径、乙酰生成途径以及甲基生成途径。甲烷的好氧或厌氧氧化协同反硝化是以NO3为电子受体的甲烷氧化的可能途径。环境中的甲烷、硫酸盐或硝酸盐的浓度,有机质的数量,以及环境条件对甲烷的厌氧氧化有显著影响。