藏鸡线粒体全基因组序列的测定和分析

通过PCR扩增,测序,拼接,获得藏鸡(Tibetan Chicken)线粒体全基因组序列并进行数据分析处理.藏鸡线粒体全基因组序列全长16 783 bp,共有13个蛋白质编码基因、2个rRNA基因、22个tRNA基因和1个D-loop区.模拟电子酶切结果显示,藏鸡Dra Ⅰ酶的酶切结果和先前报道的原鸡,茶花鸡,尼西鸡和大理漾濞黄鸡的酶切结果都不相同,为藏鸡特有.基于D-loop区全序列和13个蛋白质编码基因序列,采用N-J算法与原鸡属4个种,3个亚种和3个家鸡品系构建系统进化树:初步确定藏鸡起源于红原鸡,与家鸡中的来航鸡、白洛克鸡亲缘关系最近,但是藏鸡的进化与来航鸡、白洛克鸡这两个家鸡品系又显得相对独立.推测可能原因是藏鸡的祖先在进入高原以后处于相对封闭的环境,从而形成了独特群体遗传特性.

Estimating labels from label proportions

Consider the following problem: given sets of unlabeled observations, each set with known label proportions, predict the labels of another set of observations, also with known label proportions. This problem appears in areas like e-commerce, spam filtering and improper content detection. We present consistent estimators which can reconstruct the correct labels with high probability in a uniform convergence sense. Experiments show that our method works well in practice. Copyright 2008 by the author(s)/owner(s).

Growth of AlGaN epitaxial film with high Al content by metalorganic chemical vapour deposition

A high-Al-content AlGaN epilayer is grown on a low-temperature-deposited AlN buffer on (0001) sapphire by low pressure metalorganic chemical vapour deposition. The dependence of surface roughness, tilted mosaicity, and twisted mosaicity on the conditions of the AlGaN epilayer deposition is evaluated. An AlGaN epilayer with favourable surface morphology and crystal quality is deposited on a 20 nm low-temperature-deposited AlN buffer at a low V/III flow ratio of 783 and at a low reactor pressure of 100 Torr, and the adduct reaction between trimethylaluminium and NH3 is considered.

1.5 mu m luminescence characteristic of erbium in B, P doped a-SiO : H films

Hydrogenated amorphous silicon films co-doped with oxygen (O), boron (B) and phosphorus (P) were fabricated using PECVD technique. The erbium (Er) implanted samples were annealed in a N-2 ambient by rapid thermal annealing. Strong photoluminescence (PL) spectra of these samples were observed at room temperature. The incorporation of O, B and P could not only enhance the PL intensity but also the thermal annealing temperature of the strongest PL intensity. It seems that the incorporation of B or P can decrease the grain boundary potential barriers thus leading to an easier movement of carriers and a stronger PL intensity. Temperature dependence of PL indicated the thermal quenching of Er-doped hydrogenated amorphous silicon is very weak.

The Category-Theoretic Solution of Recursive Domain Equations

Recursive specifications of domains plays a crucial role in denotational semantics as developed by Scott and Strachey and their followers. The purpose of the present paper is to set up a categorical framework in which the known techniques for solving these equations find a natural place. The idea is to follow the well-known analogy between partial orders and categories, generalizing from least fixed-points of continuous functions over cpos to initial ones of continuous functors over $\omega $-categories. To apply these general ideas we introduce Wand's ${\bf O}$-categories where the morphism-sets have a partial order structure and which include almost all the categories occurring in semantics. The idea is to find solutions in a derived category of embeddings and we give order-theoretic conditions which are easy to verify and which imply the needed categorical ones. The main tool is a very general form of the limit-colimit coincidence remarked by Scott. In the concluding section we outline how compatibility considerations are to be included in the framework. A future paper will show how Scott's universal domain method can be included too.

地衣芽孢杆菌GXN151纤维素酶基因的克隆与表达

从广西大学农场陈旧稻草堆、甘蔗渣堆、龙胜温泉等地采集不同的土样和水样，从中共分离到10株能降解结晶纤维素的细菌、放线菌和真菌，对它们的165RNA或185 rRNA基因序列进行了分析，其中从稻草堆中分离到的好氧细菌GXN 151具有耐中温、生长迅速、能降解天然纤维素的特点。运用生理生化和电镜观察进一步将其鉴定为地衣芽抱杆菌。用pUC18和pBluescript KS＋作载体，分别以CoR工和品u3AI部分酶切的GXN 151的总DNA作目的片段，在大肠杆菌中构建了地衣芽抱杆菌GXN151的2个基因文库。运用含狡甲基纤维素的平板筛选法，从GXN151的基因文库中共筛选到14个表达梭甲基纤维素酶（CMCase）活性的克隆，采用酶切分析、亚克隆、Southern杂交、DNA测序分析将这些克隆划分为3类不重叠克隆群。pGxNLI、pGXNLZ、pGxNL7、pGxNP12和pGxNPI～pGXNP6共10个克隆归为一类重叠克隆，测序分析了PGXNLZ的序列，其长度为3672bP，其上含有一个完整的长1626 bp的ORF（GenBonk索引号为AY291583），可编码一个含542个氨基酸的内切葡聚糖酶Ce15A，其预计分子量为59，625D娜Ce15A含有家族5糖基水解酶催化功能域和家族3碳水化合物结合组件（CBM3）。PCR 扩增了ceJSA的编码框并将其克隆到大肠杆菌表达载体pET-30a（＋）上，酶谱分析表明该基因在大肠杆菌JM109（DE3）和BL21（DE3） pLysS中均表达出具梭甲基纤维素酶活性的蛋白质产物。克隆pGxNLg测序共得5818bp，pGxNLg序列中含有一个完整的内切葡聚糖酶基因cel12A（GenBaok索引号为AY291066）和一个外切-Q-葡萄糖营酶基因amyA，cel12A长783 bp，可编码含261个氨基酸的蛋白质，预计分子量为29，035 Da，含有一个家族12糖基水解酶催化功能域。amyA为1680bP，推断其编码含560个氨基酸的蛋白质，预计分子量为65，121 Da。PCR扩增了cel12A基因的含催化功能域编码区的DNA序列并连接到表达载体pET30a（＋）上得表达质粒pGxN12A，pGXN 12A在大肠杆菌JM1O9（DE3）和BL21（DE3）pLysS中均J高效表达，并对表达条件进行了研究。克隆pGXNLS、pGXNPS和pGXNpn为一类重叠克隆，测序表明pGxNPll克隆的序列共为3406bP，它包括了一个完整的内切葡聚糖酶基因ce19A和一个不完整的纤维二糖水解酶基因ce148A，ce19A基因由1899bP组成，可编码一个含633个氨基酸的蛋白质，预计分子量为71，240Da。ce19A基因的产物Ce19A含有一个家族9糖基水解酶催化功能域和一个家族3碳水化合物结合组件（CBM3）。Ce148A属于糖基水解酶第4S家族，DNA杂交表明cel48A基因的未被克隆的下游序列位于一个约10kb的SaLI片段或4kb的EcoRI片段上。