碱性纤维素酶高产菌株Bacillus sp.CY1-3的诱变选育

以一株产单组分羧甲基纤维素酶芽孢杆菌Bacillus sp.CY1-3为出发菌,经紫外线和亚硝基胍复合诱变处理后,其纤维素酶产量达到了53.86 U/mL,是出发菌株的4倍.研究发现最优的紫外辐射时间和亚硝基胍浓度分别是4min和0.06%.     

混合菌群诱变及诱变菌群对闪锌矿浸出的影响

将采自不同地区的混合菌分别培养于以黄铜矿和黄铁矿为能源的9 K培养基中,并以该培养物作为出发菌群,用亚硝酸钠(NaNO2)、硫酸二乙酯(DES)、紫外线(UV)及其组合为诱变剂,对混合菌群进行诱变。诱变后,经过连续浸矿筛选,得到对闪锌矿浸矿效果最好的诱变菌群E。浸矿试验结果表明:在9 K和Leathen培养基中,用诱变菌群E浸出闪锌矿40 d后,Zn2 的浸出率分别比对照组提高68%和84%;离心收集Leathen培养基中的菌体和矿样浸渣,弃除液体,加入新的Leathen培养基,在30℃和200 r/min条件下,恒温摇床培养20 d后,诱变菌群E对闪锌矿中Zn2 的二次浸出率比对照组高92%。     

PHB高产菌株的选育

选择甲基营养菌查氏生丝微菌成都亚种8502-3菌株作为出发菌株进行紫外光诱变处理,并得到PHB产量较高的菌株.比较原有的3株菌,确定用8502-3作为实验用种.利用紫外光的高诱变能力,对之进行多次的诱变工作,通过反复筛选,最终得到含量为64%的高产菌株.     

Generation of mutants with developmental defects in zebrafish by ENU mutagenesis

As a good model for studying early development of vertebrates, zebrafish (Danio rerio) is attracting more and more attention. Following ENU mutagenesis, 320 F2 families were established. Mutants, which showed defects in epiboly, axis, somite, head, and cardiac and blood systems, were identified by observing morphological changes in F3 embryos. So far, 35 mutant lines have been established, the majority of which showed anomalies in axis and somite formation. These mutant lines provide useful genetic resources for cloning of the mutant genes and for studying mechanisms of early development of vertebrate embryos.     

Structure and function of eukaryotic NAD(P)H:nitrate reductase

Pyridine nucleotide-dependent nitrate reductases (NRs; EC 1.6.6.1–3) are molybdenum-containing enzymes found in eukaryotic organisms which assimilate nitrate. NR is a homodimer with an ∼100 kDa polypeptide which folds into stable domains housing each of the enzyme's redox cofactors—FAD, heme-Fe molybdopterin (Mo-MPT) and the electron donor NAD(P)H—and there is also a domain for the dimer interface. NR has two active sites: the nitrate-reducing Mo-containing active site and the pyridine nucleotide active site formed between the FAD and NAD(P)H domains. The major barriers to defining the mechanism of catalysis for NR are obtaining the detailed three-dimensional structures for oxidized and reduced enzyme and more in-depth analysis of electron transfer rates in holo-NR. Recombinant expression of holo-NR and its fragments, including site-directed mutagenesis of key acative site and domain interface residues, are expected to make large contributions to this effort to understand the catalytic mechanism of NR.     

Hsp16.3中一个高度保守疏水残基的定点突变

结核杆菌小分子热休克蛋白Ｈｓｐ１６．３为一由三个三聚体组成的寡聚蛋白,并具有分子伴娘活性（Ｃｈａｎｇｅｔａｌ．,Ｊ．Ｂｉｏｌ．Ｃｈｅｍ．,１９９６,２７１：７２１８～７２２３）。为研究高度保守疏水片段中高度保守疏水亮氨酸残基（Ｌｅｕ１２１）对寡聚体结构和活性的影响,该残基被分别定点突变成天冬氨酸（Ａｓｐ）、天冬酰胺（Ａｓｎ）、缬氨酸（Ｖａｌ）和丙氨酸（Ａｌａ）等。结果发现当Ｌｅｕ１２１被突变成Ｖａｌ和Ａｌａ时,通过ＳＤＳ－ＰＡＧＥ凝胶电泳检测仍可见重组蛋白在大肠杆菌中的高水平表达,而当被突变成Ａｓｐ和Ａｓｎ时,在ＳＤＳ－ＰＡＧＥ胶上,见不到Ｈｓｐ１６．３蛋白带。表明该残基可能对寡聚蛋白的结构稳定起重要作用。     

Molecular dynamics simulation of site-directed mutagenesis of HIV-1 Tattrans-activator

The Cys-rich domain, core region and basic domain are highly conserved and very important to thetrans-activation activity of HIV-1 Tattrans-activator. The three-dimensional structures of 6 mutants of HIV-1 Tat protein were constructed with the methods of molecular dynamics simulation. The variations of the structures of the mutants have been analyzed and the factors that led to abolishment oftrans-activation activity have been discussed.     

Site-directed mutagenesis reveals new and essential elements for iron-coordination of the sulfur oxygenase reductase from the acidothermophilic Acidianus tengchongensis

Previous study on refolding of sulfur oxygenase reductase (SOR) inclusion bodies from recombinant Escherichia coli showed that iron was critical to the activity of the SOR from Acidianus ambivalens. In this study, enzymatic assays showed that 2,2′-Dipyridyl, Tiron and 8-hydroxyquinoline, which are specific for chelating ferrous or ferric ions, strongly inhibited the activity of SOR from A. tengchongensis, suggesting that iron atom is essential for SOR activity. Alignment of several functionally identified S...     

氧化铁硫杆菌的选育研究

试验从野生菌出发,通过一系列选育方法,筛选出了对硫铁矿与硫铜矿有较好溶解能力的氧化铁硫杆菌菌株A_1、A_2,试验方法同样适用于其它重金属治金微生物的选育     

血管生长素衍生物His13Gly的基因工程研究

在人工合成的血管生长素基因的基础上，利用化学合成的寡聚核苷酸片段，采用掺Ｕ法对ＡＮＧ知性定位眯诱变，同位素杂交筛选到ＡＮＧ基因的衍生物ＩＳ１３Ｇｌ６突变子。