Structures composing protein domains

This review summarizes available data concerning intradomain structures (IS) such as functionally important amino acid residues, short linear motifs, conserved or disordered regions, peptide repeats, broadly occurring secondary structures or folds, etc. IS form structural features (units or elements) necessary for interactions with proteins or non-peptidic ligands, enzyme reactions and some structural properties of proteins. These features have often been related to a single structural level (e.g. primary structure) mostly requiring certain structural context of other levels (e.g. secondary structures or supersecondary folds) as follows also from some examples reported or demonstrated here. In addition, we deal with some functionally important dynamic properties of IS (e.g. flexibility and different forms of accessibility), and more special dynamic changes of IS during enzyme reactions and allosteric regulation. Selected notes concern also some experimental methods, still more necessary tools of bioinformatic processing and clinically interesting relationships.     

甘蓝型油菜BnCOP1基因编码区全长cDNA的克隆与功能研究

通过分析拟南芥、豌豆、番茄和水稻的COP1 (constitutively photomorphogenic 1) 的cDNA序列, 运用RT-PCR和改进的基因组步行 (genome walking) 技术相结合的方法, 首次从甘蓝型油菜中克隆到油菜 BnCOP1编码区cDNA的全长序列, 其全长2 034 bp, 编码677个氨基酸. 同源 性分析表明, 其编码的氨基酸序列与拟南芥的同源性高达94%. 对BnCOP1编 码序列（cDNA）演绎出的氨基酸序列分析表明, 其编码的蛋白包含有N端的 环形锌指结合域(ring finger zinc binding domain, RING)、中间的卷曲 螺旋形结构域(coiled-coil domain, coiled-coil ), 7个C端的WD-40重复 序列(WD-40 repeats, WD-40)的功能域. 半定量RT-PCR和实时荧光定量PCR 分析该基因在油菜中的表达模式,结果显示, BnCOP1在甘蓝型油菜的各个组 织器官中均有表达,其中在花中的表达明显高于在根、叶、茎、果荚及子叶 和胚轴中,暗示该蛋白可能与开花途径相关. 过表达BnCOP1的转基因拟南芥 植株在高度、主茎的直径和叶片大小上都呈现出比野生型弱小的表型, 表 明BnCOP1抑制了拟南芥光形态建成从而影响了植物的生长发育.     

小麦耐盐种质遗传多样性的RAPD分析

选用２２个引物对２４份小麦耐盐种质进行ＲＡＰＤ分析,共产生２００条扩增片段,多态性片段数为１７２条,扩增片段的多态性百分率为８６％,利用ＮＹＳＴＳ软件根据Ｊａｃｃａｒｄ系统分析ＲＡＰＤ结果,并按ＵＰＧＭＡ类平均法进行聚类。２４份材料相似系数在０．２１￣０．９７之间,其中含有多枝赖草、黑麦和偃麦草等外源染色体的多１７４、ＷＲ８３０和南前１２７被分别在３个独立的组,多１７４和南前１２７的亲关系最远,相     

湖南猕猴桃属植物地理分布及其区系特点研究

湖南猕猴桃属植物有２１种１３变种,主要分布于湘南和湘西两地区,经分析研究,湖南猕猴桃属植物区系有如下特点：１、种类比较丰富,是构成湖南森林植物区系林间植物的主要成分之一;２、地理成分比较复杂,种的分析显示出以中国特有分布为主的特点;３、种间、种内分化强烈;４、特有种较多;５、与邻近地区猕猴桃属植物区系的关系密切,最后,作者对湖南猕猴桃属植物的起源问题进行了分析和推测。     

玉米叶肉细胞和维管束鞘细胞中光合产物的分析

玉米苗照光后,叶肉细胞和维管束鞘细胞大量积累淀粉和可溶性糖(包括蔗糖),其中淀粉95％以上在维管束鞘细胞中。阻断光合产物输出时,两类细胞中蔗糖和淀粉积累都显著增加。离体维管束鞘细胞也能合成蔗糖。离体玉米叶内原生质体饲喂NaH~(14)CO_3并照光后,通常90％以上的~(14)C参入到有机酸和氨基酸中,3～10％参入糖和淀粉中。玉米叶肉原生质体具有直接利用CO_2合成碳水化合物的能力。     

The Specific Elongation Factor to Selenocysteine Incorporation in Escherichia coli: Unique tRNASec Recognition and its Interactions

Several molecular mechanisms are involved in the genetic code interpretation during translation, as codon degeneration for the incorporation of rare amino acids. One mechanism that stands out is selenocysteine (Sec), which requires a specific biosynthesis and incorporation pathway. In Bacteria, the Sec biosynthesis pathway has unique features compared with the eukaryote pathway as Ser to Sec conversion mechanism is accomplished by a homodecameric enzyme (selenocysteine synthase, SelA) followed by the action of an elongation factor (SelB) responsible for delivering the mature Sec-tRNA^Sec into the ribosome by the interaction with the Selenocysteine Insertion Sequence (SECIS). Besides this mechanism being already described, the sequential events for Sec-tRNA^Sec and SECIS specific recognition remain unclear. In this study, we determined the order of events of the interactions between the proteins and RNAs involved in Sec incorporation. Dissociation constants between SelB and the native as well as unacylated-tRNA^Sec variants demonstrated that the acceptor stem and variable arm are essential for SelB recognition. Moreover, our data support the sequence of molecular events where GTP-activated SelB strongly interacts with SelA.tRNA^Sec. Subsequently, SelB.GTP.tRNA^Sec recognizes the mRNA SECIS to deliver the tRNA^Sec to the ribosome. SelB in complex with its specific RNAs were examined using Hydrogen/Deuterium exchange mapping that allowed the determination of the molecular envelopes and its secondary structural variations during the complex assembly. Our results demonstrate the ordering of events in Sec incorporation and contribute to the full comprehension of the tRNA^Sec role in the Sec amino acid biosynthesis, as well as extending the knowledge of synthetic biology and the expansion of the genetic code.     

斜纹夜蛾核多角体病毒几丁质酶基因的克隆及序列分析

以苜蓿丫纹夜蛾核多角体病毒（Ａｕｔｏｇｒａｐｈａ ｃａｌｉｔｉｒｎｉｃａ ｍｕｌｔｉｎｕｃｌｅｏｃａｐｓｉｄ ｎｕｃｌｅａｒ ｐｏｌｙｈｅｄｒｏｓｉｓ ｖｉｒｕｓ,ＡｃＭＮ－ＰＶ）基因组含几丁质酶基因（ｃｈｉＡ）的ｐｓｔＩ Ｍ片段为探针,通过Ｓｏｕｔｈｅｒｎ杂交将斜纹夜蛾核多角体病毒（Ｓｐｏｄｏｐｔｅｒａ ｌｉｔｕｒａ ｎｕｃｌｅａｒ ｐｏｌｙｈｅｄｒｏｓｉｓ ｖｉｒｕｓ,ＳｐｌｔＮＰＶ）的ｃｈｉ     

鸽基因Ⅶ型新城疫病毒的分离鉴定

从外表健康的法国进口鸽中分离到一株鸽Ⅰ型副粘病毒(FP株),电镜观察病毒形态不规则,以圆形为主,平均直径100mm～120mm,表面有许多突起。其鸡胚平均死亡时间(MDT)为59．2h,鸡脑内接种指数(IcPI)为1．88。接种1月龄鸽能使其发病。出现明显症状和病变并有80％试验鸽死亡,接种2月龄SPF鸡全部死亡。经多重RT—PCR鉴定,属速发型新城疫病毒。应用RT—PCR技术对F基因重要功能区片段扩增后进行序列测定、分析表明,F蛋白裂解位点处的序列(112R—R—Q—K—R—117F)与新城疫强毒在这一区域的序列相符。与国内强毒F48E9株、疫苗毒Lasota株的核苷酸同源性分别为84．1％、82％,氨基酸同源性为84．5％、80．6％。与多株已报道的NDV参考株相应片段进行序列比较,经遗传基因进化树分析,鉴定为基因Ⅶ型,由此首次报道了鸽源基因Ⅶ型NDV株的存在。     

Selenium in platelets

Blood and its main components are commonly used to detect states of selenium deficiency. In order to examine whether human platelets are able to provide better or additional information, improvements analytical method resulted in surprisingly narrow normal ranges for selenium and other mineral elements using neutron activation analysis (NAA) and atomic absorption spectrophotometry (AAS), and controlling thermal neutron flux, (n,γ)-cross sections, mean platelet wet wt, and water fraction of the platelets. Previously reported selenium concentrations in platelets on wet wt basis in the order of 500 ng/g—half of which had been found to derive from early bone marrow precursors using⁷⁴Se-selenite—were reproduced by NAA and AAS. However, with the new analytical method the selenium concentrations showed a narrower normal range than that of plasma. Moreover, platelet selenium did not in all cases correlate with plasma selenium. Cellular tissues such as platelets should, therefore, help to detect latent states of selenium deficiency.     

社鼠种群年龄结构的回归分析

本文利用社鼠(Nivitverter confucianus)头骨度量的8项指标(单位：mm)：颅全长X1、颅基长X2、基底长X3、颧宽X4、眶间宽X5、齿隙长X6、上裂齿长X7、门齿孔长X8,用多元回归分析方法,建立了其种群年龄结构的判别函数为：Y=0．3577X2-0．4599X7 0．3364X8—8．4267将头骨度量X2、X7、X8带入回归方程进行计算,如INT(Y 0．5)=G1,则该个体属于G1年龄组。回归方程表明,社鼠的年龄仅与头骨的颅基长X2、上裂齿长X7、门齿孔长X8有关,而颧宽X4、眶间宽X5、齿隙长X6在各年龄组相对较稳定,可以作为分类的指标。