A new computational approach for real protein folding prediction

An effective and fast minimization approach is proposed for the prediction of protein folding, in which the 'relative entropy' is used as a minimization function and the off-lattice model is used. In this approach, we only use the information of distances between the consecutive Calpha atoms along the peptide chain and a generalized form of the contact potential for 20 types of amino acids. Tests of the algorithm are performed on the real proteins. The root mean square deviations of the structures of eight folded target proteins versus the native structures are in a reasonable range. In principle, this method is an improvement on the energy minimization approach.     

High-level phenotypic variations in populations of Armeniaca sibirica in Nei Mongol,China北大核心CSCD

Aims: Our objectives were to determine the variations in phenotypic traits of Armeniaca sibirica populations and their spatial patterns. Methods: We used nested variation, coefficient of variation, multi-comparison, correlation analysis and principal component analysis to analyze the 23 phenotypic traits for 130 individuals in 13 populations of A. sibirica. Important findings: The results showed that there were significant differences in phenotypic variations among and within populations. The variation was greater among populations (47.15%) than within population (16.43%). The mean phenotypic differentiation coefficient was 73.03% among populations, indicating the variance among populations being the main source of the phenotypic variation. The average variation coefficient of 23 traits ranged from 7.01% to 27.23%, with an average of 14.28%. The variation coefficient of nutlet was highest (15.67%), and the variation coefficient of fruit was smallest (12.11%). The phenotypic diversity is highest in Wanjiagou Tumotezuoqi and smallest in Horqin, Right Front Banner Chaersen. Longitude, mean annual precipitation and sunshine duration were significantly correlated with major traits of phenotypic. The 13 populations could be divided into four groups according to the principal component analysis. Leaf traits of Wula Mountain and nutlet traits of Archorchin Banner were significantly correlated with ecological and geographic factors.     

白背飞虱单克隆抗体的制备及其特性的研究

应用杂交瘤技术,制备出4株高度特异性的白背飞虱单克隆抗体,分别命名为WPH-1H9、WPH-2B6、WPH-2E12和WPH-3F12。这些抗体与其它8种昆虫未发生交叉反应,其中WPH-2B6可与白背飞虱所有虫态发生反应,其余3株只与卵和雌成虫发生反应。应用免疫双扩散法鉴定抗体类型及亚类,结果表明：WPH-2B6为IgG_2b亚类,其余均为IgG₁亚类。SDS-聚丙烯酰胺凝胶电泳和Western blot印迹分析表明,白背飞虱抗原主要由分子量分别为182、116、66.2及40 kD的4个多肽组成,其中WPH-2B6与182、116 kD的多肽结合,其余3株的单抗只与116 kD的多肽具有亲和性。最后对这些单克隆抗体在捕食作用研究中的应用潜力进行了讨论。     

端粒酶在细胞永生化和癌变中的作用

重点讨论了端粒酶在肿瘤细胞和永生化细胞中的作用和功能,以及它与细胞衰老和永生化的关系.多数真核细胞的端粒酶能将单一重复序列加到端粒DNA的3′末端.端粒酶主要由模板RNA和端粒酶蛋白催化亚基组成,后者以前者为模板起逆转录酶的作用.端粒酶活性存在于肿瘤细胞中,而在良性肿瘤、体细胞中未发现端粒酶.     

Identification of a Highly Conserved Epitope on Avian Influenza Virus Non-Structural Protein 1 Using a Peptide Microarray

Avian influenza virus (AIV) non-structural protein 1 (NS1) is a multifunctional protein. It is present at high levels in infected cells and can be used for AIV detection and diagnosis. In this study, we generated monoclonal antibody (MAb) D7 against AIV NS1 protein by immunization of BALB/c mice with purified recombinant NS1 protein expressed in Escherichia coli. Isotype determination revealed that the MAb was IgG₁/κ-type subclass. To identify the epitope of the MAb D7, the NS1 protein was truncated into a total of 225 15-mer peptides with 14 amino acid overlaps, which were spotted for a peptide microarray. The results revealed that the MAb D7 recognized the consensus DAPF motif. Furthermore, the AIV NS1 protein with the DAPF motif deletion was transiently expressed in 293T cells and failed to react with MAb D7. Subsequently, the DAPF motif was synthesized with an elongated GSGS linker at both the C- and N-termini. The MAb D7 reacted with the synthesized peptide both in enzyme-linked immunosorbent assay (ELISA) and dot-blot assays. From these results, we concluded that DAPF motif is the epitope of MAb D7. To our knowledge, this is the first report of a 4-mer epitope on the NS1 protein of AIV that can be recognized by MAb using a peptide microarray, which is able to simplify epitope identification, and that could serve as the basis for immune responses against avian influenza.     

Seed-to-seed potential allelopathic effects between <Emphasis Type="Italic">Ligularia virgaurea</Emphasis> and native grass species of Tibetan alpine grasslands

Allelopathy is an important process in plant communities, but the role of seed allelopathy in natural ecosystems remains poorly understood. In the present study, we examined the potential allelopathic effects of Ligularia virgaurea (a dominant species in degraded Tibetan grasslands) seeds on the germination of four native grass species (Festuca sinensis, Agrostis gigantean, Bromus inermis, and Elymus nutans). The results showed that L. virgaurea seeds can have potential allelopathic effects on seed germination, mean time to germination and root growth rates of native grass species. We further demonstrate that these effects are driven by a water-soluble seed leachate. Species with smaller seeds were generally more sensitive than larger seeded species. The results suggest that seed-to-seed allelopathic potential may be an important mechanism driving the dominance of L. virgaurea in degraded alpine grasslands on the Tibetan Plateau. Further studies are required to demonstrate effects of seed-to-seed potential allelopathy in a field setting.     

塔克拉玛干沙漠腹地胡杨林土壤细菌多样性分析

【目的】对塔克拉玛干沙漠腹地胡杨林土壤细菌多样性进行初步探索,为下一步从中筛选可用于生物饲料或生物肥料的微生物奠定基础。【方法】采用可培养方法,进行细菌的分离纯化。对各菌株进行革兰氏染色及淀粉酶、酯酶、纤维素酶和NaCl耐受浓度的测定,并提取各菌株基因组DNA,进行16SrRNA基因扩增、测序及系统进化树的绘制,分析其多样性。【结果】共分离得到27株菌,其中放线菌门(Actinobacteria)16株,变形菌门(Proteobacteria)4株,厚壁菌门(Firmicutes)6株,拟杆菌门(Bacteroidetes)1株。革兰氏染色结果表明,5株菌为革兰氏阴性,其余为革兰氏阳性;酶活测定结果表明,15株菌具有淀粉酶活性,9株菌具有酯酶活性,9株菌具有纤维素酶活性;NaCl耐受浓度测定结果显示,NaCl浓度为2%时所有菌株均能生长,5%时能生长的有22株,15%时能生长的有1株。【结论】塔克拉玛干沙漠腹地胡杨林土壤中存在较丰富的细菌类群,且具有一定的酶学活性和NaCl耐受性,具有进一步研究开发的价值。     

Cotton (Gossypium hirsutum) 14‐3‐3 proteins participate in regulation of fibre initiation and elongation by modulating brassinosteroid signalling

Cotton (Gossypium hirsutum) fibre is an important natural raw material for textile industry in the world. Understanding the molecular mechanism of fibre development is important for the development of future cotton varieties with superior fibre quality. In this study, overexpression of Gh14‐3‐3L in cotton promoted fibre elongation, leading to an increase in mature fibre length. In contrast, suppression of expression of Gh14‐3‐3L, Gh14‐3‐3e and Gh14‐3‐3h in cotton slowed down fibre initiation and elongation. As a result, the mature fibres of the Gh14‐3‐3 RNAi transgenic plants were significantly shorter than those of wild type. This ‘short fibre’ phenotype of the 14‐3‐3 RNAi cotton could be partially rescued by application of 2,4‐epibrassinolide (BL). Expression levels of the BR‐related and fibre‐related genes were altered in the Gh14‐3‐3 transgenic fibres. Furthermore, we identified Gh14‐3‐3 interacting proteins (including GhBZR1) in cotton. Site mutation assay revealed that Ser163 in GhBZR1 and Lys51/56/53 in Gh14‐3‐3L/e/h were required for Gh14‐3‐3‐GhBZR1 interaction. Nuclear localization of GhBZR1 protein was induced by BR, and phosphorylation of GhBZR1 by GhBIN2 kinase was helpful for its binding to Gh14‐3‐3 proteins. Additionally, 14‐3‐3‐regulated GhBZR1 protein may directly bind to GhXTH1 and GhEXP promoters to regulate gene expression for responding rapid fibre elongation. These results suggested that Gh14‐3‐3 proteins may be involved in regulating fibre initiation and elongation through their interacting with GhBZR1 to modulate BR signalling. Thus, our study provides the candidate intrinsic genes for improving fibre yield and quality by genetic manipulation.