产纤维素酶黏细菌在生物转化的作用

目的:预处理对木质纤维素降解的影响.方法:从土壤中分离筛选到高纤维素酶活的黏细菌菌株So ce sh1008.该菌具有CMC酶活(CMCase)及微晶纤维素酶活性.研究NaOH联合黏细菌降解盐蒿、稻草、棉花秸秆和甘蔗渣四种木质纤维素的情况.结果:碱(2％ NaOH) -黏细菌处理的方法优于黏细菌-碱的方法,其中降解棉花秸秆降解效果最明显,以5.0g木质纤维素为原料,其最终干重损失达2.1g,溶液中总糖含量和还原糖含量均值分别为12.8 mg/mL和0.93 mg/mL.酵母菌发酵产乙醇的研究结果表明,最佳发酵时间为47h,碱-黏细菌甘蔗渣降解液发酵效果最好,乙醇产出达6.0％.结论:黏细菌联合2％ NaOH能有效降解甘蔗渣,提高乙醇产量.     

Intensified plant N and C pool with more available nitrogen under experimental warming in an alpine meadow ecosystem

Nitrogen (N) availability is projected to increase in a warming climate. But whether the more available N is immobilized by microbes (thus stimulates soil carbon (C) decomposition), or is absorbed by plants (thus intensifies C uptake) remains unknown in the alpine meadow ecosystem. Infrared heaters were used to simulate climate warming with a paired experimental design. Soil ammonification, nitrification, and net mineralization were obtained by in situ incubation in a permafrost region of the Qinghai‐Tibet Plateau (QTP). Available N significantly increased due to the stimulation of net nitrification and mineralization in 0–30 cm soil layer. Microbes immobilized N in the end of growing season in both warming and control plots. The magnitude of immobilized N was lower in the warming plots. The root N concentration significantly reduced, but root N pool intensified due to the significant increase in root biomass in the warming treatment. Our results suggest that a warming‐induced increase in biomass is the major N sink and will continue to stimulate plant growth until plant N saturation, which could sustain the positive warming effect on ecosystem productivity.     

乳腺癌易感蛋白2的结构和功能

乳腺癌易感蛋白2是由乳腺癌易感基因2编码的一种在维持哺乳动物细胞染色体的稳定及DNA损伤生物应答中发挥重要作用的蛋白质。文章通过介绍近几年来对乳腺癌易感蛋白2的结构研究,阐述其在双链DNA损伤修复中的作用模型及其在肿瘤抑制中的功能。     

II型单纯疱疹病毒糖蛋白D的晶体结构解析

II型单纯疱疹病毒 (HSV-2) 糖蛋白D (Glycoprotein D,gD) 在介导该病毒入侵到宿主细胞中起着关键作用。为了更好地研究gD在病毒侵入过程中的作用机制,利用杆状病毒表达系统表达了gD胞外部分区域 (1~285 aa),通过Ni-NTA亲和层析以及分子排阻层析纯化后,得到的带His标签的分泌型可溶蛋白,用悬滴法对该蛋白进行了晶体筛选,获得了高质量的晶体。晶体生长条件为0.1 mol/L Hepes缓冲液 (pH 7.2),5％ (V/V) 2-甲基-2,4-戊二醇 (MPD),10％     

一种酚氧化酶原组织定位的胶体金标记免疫电镜方法

以亚洲玉米螟Ostrinia furnacalis Guenée5龄幼虫的中肠和体壁组织为材料,采用Epon812常规包埋方法,以作者实验室制备的酚氧化酶原多克隆抗体为一抗、胶体金标记的羊抗鼠IgG为二抗,采用醋酸双氧铀-柠檬酸铅双染色体系,建立一种胶体金标记的特异性强且超微结构保存较好的亚洲玉米螟幼虫体内中酚氧化酶原免疫电镜定位方法。     

云南雨石得电站工程建设对巴江渔业资源及生态环境的影响

综述了巴江渔业资源状况和雨石得电站建设对资源和环境的影响。巴江共有鱼类60种,其中土著鱼类47种。有16个水生动物新种(其中鱼类新种14个),和国家二级保护动物红瘰疣螈。屯站建成后将对巴江急流鱼种及洄游鱼种的生存造成不利影响。当前应采取切实可行的生态措施,以保护巴江特有的生物资源。     

1981～2005年中国H1N1甲型流感病毒血凝素基因的HA1演变特征

为了解1981~2005年我国H1N1甲型流感病毒血凝素基因的HA1演变特征,选取H1N1甲型流感病毒370株,提取病毒RNA,经逆转录和聚合酶链反应扩增HA1并测序,测定的序列用生物信息软件分析,与GenBank中相关序列比较,并对推导的编码氨基酸序列进行基因特性分析。结果表明:HA1氨基酸的变异表现为抗原决定簇4个区均有变异,Sb区和Ca区变化较大;HA1受体结合位点(RBS)的前壁130环的第134位赖氨酸从1991年起在部分毒株HA1序列上开始缺失,以后缺失株逐步增多,自2000年起测定的所有毒株上该氨基酸全部缺失,同时这些缺失株的第137位氨基酸也全部由苏氨酸替换为丝氨酸;糖基化位点从增多到减少,最后稳定在7个;1981~2004年我国H1N1甲型流感病毒血凝素HA1编码的氨基酸在种系发育树上同年代基本呈现集中分布,与时间和地域无关,2005年毒株分成两个分支在时间上有明显差异。     

Phenotypic responses of hatchlings to constant versus fluctuating incubation temperatures in the multi-banded krait, Bungarus multicintus (Elapidae)

Most studies on egg incubation in reptiles have relied on constant temperature incubation in the laboratory rather than on simulations of thermal regimes in natural nests. The thermal effects on embryos in constant-temperature studies often do not realistically reflect what occurs in nature. Recent studies have increasingly recognized the importance of simulating natural nest temperatures rather than applying constant-temperature regimes. We incubated Bungarus multicintus eggs under three constant and one fluctuating-temperature regimes to evaluate the effects of constant versus fluctuating incubation temperatures on hatching success and hatchling phenotypes. Hatching success did not differ among the four treatments, and incubation temperature did not affect the sexual phenotype of hatchlings. Incubation length decreased as incubation temperature increased, but eggs incubated at fluctuating temperatures did not differ from eggs incubated at constant temperatures with approximately the same mean in incubation length. Of the hatchling phenotypes examined, residual yolk, fat bodies and locomotor performance were more likely affected by incubation temperature. The maximal locomotor speed was fastest in the fluctuating-temperature and 30 degrees C treatments and slowest in the 24 degrees C treatment, with the 27 degrees C treatment in between. The maximal locomotor length was longest in the fluctuating-temperature treatment and shortest in the 24 degrees C and 27 degrees C treatments, with the 30 degrees C treatment in between. Our results show that fluctuating incubation temperatures do not influence hatching success and hatchling size and morphology any differently than constant temperatures with approximately the same mean, but have a positive effect on locomotor performance of hatchlings.     

An investigation on the genetic background of <Emphasis Type="Italic">Nostoc flagelliforme</Emphasis> by similarity analysis of its partial genomic DNA and phylogenetic comparison of deduced related species

Nostoc flagelliforme, which is distributed on arid and semi-arid steppes of northwestern parts of China, has attracted increasing interest for its stress tolerance. In order to gain more insight into the genetic background of N. flagelliforme, we sequenced its partial genomic DNA for similarity analyses against current public databases, followed by phylogenetic comparison of N. flagelliforme and the potentially related species deduced from the similarity analyses. Approximately 430 kb genomic sequence (~5% of genome as a rough estimate) was determined from 106 distinct genomic clones. Nucleotide BLAST showed that ~23.1% of the partial genomic sequence was similar to N. punctiforme genomic DNA and ~12.4% to its plasmid DNA. Similar protein search by online FASTA-protein program showed 46.2% of the similar proteins had their corresponding orthologs in N. punctiforme genome. Furthermore, phylogenetic comparison based on 16S rRNA sequences showed N. flagelliforme and N. punctiforme clustered closer among the deduced related species. These results indicated that N. punctiforme might also be potentially close neighbor species of N. flagelliforme, in addition to the formerly regarded close neighbor species N. commune and N. sphaeroids. In general, these data enriched our recognition of the evolutionary relationship between N. flagelliforme and other Nostoc species, especially N. punctiforme.