AT-hook蛋白的最新研究进展

AT-hook是一类新的DNA结合蛋白基序,与其他功能已知的DNA结合蛋白基序不同。AT-hook蛋白具有AT-hook基序和PPC(plants and prokaryotes conserved domain,DUF296)两个特殊功能域。AT-hook广泛存在于不同物种的DNA结合蛋白中,在植物生长发育、器官构建、逆境胁迫和激素信号应答中发挥重要的调节作用;对基因克隆、细胞间特异性结合、染色体结构调节以及转录因子调节具有重要的调控作用。通过调节AT-hook蛋白进而改变生物某些不理想的生理生化调控通路,提高生物某些优良性状具有重要研究价值及意义。本综述主要从AT-hook蛋白的结构特征、分类及其依据、功能调节机制、生物学功能以及研究价值等方面进行相关阐述及总结。     

Design,synthesis and antibacterial activity of novel andrographolide derivatives

A series of andrographolide derivatives were synthesized through a facile condensation reaction with different carboxylic acids. The new compounds were characterized and screened for their antibacterial activities. A number of the new compounds significantly reduced bacterial quorum sensing virulence factors production in Pseudomonas aeruginosa, essential for pathogenesis. Compound 11b showed the best activity among all the new compounds.     

An interspecific somatic hybrid between upland cotton (<Emphasis Type="Italic">G. hirsutum</Emphasis> L. cv. ZDM-3) and wild diploid cotton (<Emphasis Type="Italic">G. klotzschianum</Emphasis> A.)

Somatic hybrids were produced through protoplast electrofusion between the tetraploid cotton Gossypium hirsutum L. cv. ZDM-3 and the wild diploid cotton G. klotzschianum. Hybrid plants were generated from 3 out of 24 callus lines that were derived from fused protoplasts. Hybrid plants were initially identified as somatic hybrids by ploidy analysis: the plants from the 3 callus lines had chromosome numbers near to sum of the two parents (78 = 52 + 26). The plants from the 3 lines were subsequently confirmed as hybrids by cytological, molecular, histological and morphological analyses. The morphology of hybrids was distinct from that of the parents, with elongated stigmas and malformed anthers lacking microspores and pollen, leading to male sterility. It is expected that the male sterility resulted from the high number of univalent and irregular multivalent chromosome pairings per meiocyte.     

Exploration on asymmetric synthesis of flavanone catalyzed by (S)-pyrrolidinyl tetrazole

An improved method of the synthesis of flavanones catalyzed by pyrrolidine and BF(3) ·Et(2) O has been developed and a lot of flavanones could be easily synthesized via this method. The asymmetric synthesis of flavanone from benzaldehyde and 5-fluoro-2-hydroxyacetophenone has been studied and flavanone with moderate enantioselectivity was obtained in one step.     

Structural features of the lysosomal hydrolase mannose 6-phosphate uncovering enzyme

The uncovering enzyme (UCE) removes N-acetylglucosamine from lysosomal enzymes to uncover the mannose 6-phosphate (Man-6-P) determinant necessary for targeting these enzymes to lysosomes. Failure to create the Man-6-P determinant is one cause of lysosomal storage diseases. Despite its medical importance, little structural information about UCE is available. In this report we have developed a model for the membrane proximal portion of the lumenal domain of UCE based on the structure of the EFG-3 and -4 domains of the extracellular segment of the beta chain of integrin V 3. In this model the EGF-like domains of UCE (residues 285–345) are predicted to form a rod-shaped stalk region, similar to the stem region in Golgi glycosyltransferases. This stalk causes the proposed catalytic domain (residues 1–277) to be extended away from the Golgi membrane. A portion of the proposed catalytic domain (residues 85-256) resides in Cluster of Orthologous Group (COG) 4632 with four bacterial proteins but is not homologous to any known eukaryotic proteins. Thus, UCE may have evolved from the fusion of a unique catalytic domain with a common EGF-like stalk domain. We have determined by mass spectrometry that the four disulfide bonds of the proposed catalytic domain are located between Cys²–Cys¹⁷², Cys⁶⁶–Cys⁹⁹, Cys⁸³–Cys²⁷⁴, and Cys²⁵⁸–Cys²⁶⁵. Finally, we determined that four of the six potential N-linked glycosylation sites are glycosylated (Asn 159, Asn 165, Asn 247, and Asn 317) in COS cells. Published in 2005.     

Colloidal Bismuth Pectin: An Alternative to Bismuth Subcitrate for the Treatment of Helicobacter pylori– Positive Duodenal Ulcer

Background. Bismuth triple therapy provides consistently good results in Helicobacter pylori eradication worldwide, whereas quadruple therapy using a combination of omeprazole and bismuth triple regimen has produced cure rates in excess of 90%. The prevalence of metronidazole-resistant strains was 26.8% in our area. Colloidal bismuth pectin (CBP) is a new, lower-priced bismuth salt made in China. The purpose of this study was to investigate the efficacy and safety of CBP triple and quadruple regimens in the treatment of H. pylori–positive duodenal ulcer. Materials and Methods. In this prospective trial, 205 patients with H. pylori–positive duodenal ulcer were allocated randomly to receive one of four regimens: metronidazole, 200 mg; amoxicillin, 250 mg; and colloidal bismuth subcitrate (CBS), 120 mg (group 1), or CBP, 100 mg qid (group 2) for 2 weeks, then continued CBS, 240 mg, or CBP, 200 mg bid for a further 2 weeks. A quadruple regimen using a combination of omeprazole, 20 mg bid, and CBS triple therapy (group 3) or CBP triple therapy (group 4), respectively, was given to patients for 1 week, followed by omeprazole, 20 mg once daily for a further 3 weeks. Further endoscopy was performed at least 4 weeks after cessation of the treatment. H. pylori status was determined by histology, a ¹⁴C urea breath test, and a urease test. Results. The per-protocol H. pylori cure rates were 85% (22 of 26 patients), 90% (35 of 39), 96% (46 of 48), and 95% (75 of 79) for groups 1 through 4. In the intention-to-treat analysis, cure rates were 79% (22 of 28), 83% (35 of 42), 90% (46 of 51), and 89% (75 of 84), respectively. The cure rates of quadruple therapy were higher than those of triple therapy; an 8.2% difference was not statistically significant (95% confidence interval [CI], 2.3–18.7%). The ulcer-healing rates were 88%, 87%, 98%, and 97%, respectively, for groups 1 through 4. The ulcer pain was relieved more rapidly in quadruple- than in triple-therapy regimens. Two patients discontinued treatment prematurely owing to drug-related side effects. Conclusion. One-week quadruple therapy is highly effective and safe in H. pylori eradication in Chinese patients. CBP is as effective as CBS.     

CAMSAP3-dependent microtubule dynamics regulates Golgi assembly in epithelial cells

The Golgi assembly pattern varies among cell types. In fibroblast cells, the Golgi apparatus concentrates around the centrosome that radiates microtubules; whereas in epithelial cells, whose microtubules are mainly noncentrosomal, the Golgi apparatus accumulates around the nucleus independently of centrosome. Little is known about the mechanisms behind such cell type-specific Golgi and microtubule organization. Here, we show that the microtubule minus-end binding protein Nezha/CAMSAP3 (calmodulin-regulated spectrin-associated protein 3) plays a role in translocation of Golgi vesicles in epithelial cells. This function of CAMSAP3 is supported by CG-NAP (centrosome and Golgi localized PKN-associated protein) through their binding. Depletion of either one of these proteins similarly induces fragmentation of Golgi membranes. Furthermore, we find that stathmin-dependent microtubule dynamics is graded along the radial axis of cells with highest activity at the perinuclear region, and inhibition of this gradient disrupts perinuclear distribution of the Golgi apparatus. We propose that the assembly of the Golgi apparatus in epithelial cells is induced by a multi-step process, which includes CAMSAP3-dependent Golgi vesicle clustering and graded microtubule dynamics.     

后河自然保护区珍稀植物群落主要种群结构及分布格局研究

利用方差均值比和修正的Clark-Evans最近邻体两种分布格局判定方法,对湖北省五峰县后河国家自然保护区1hmz固定样地中DBH≥5cm、重要值>2．5的26个树种的种群结构和分布格局类型进行了研究．结果表明,26个种群中有金钱槭、天师栗、白辛树、珙桐、领春木、水青树、连香树7种珍稀濒危植物种群和尖连蕊茶、君迁子、建始槭、曼青冈、鸡爪槭、桃叶黄杨、鹅耳枥等19种非珍稀濒危植物种群,7种珍稀植物种群中,除了2种个体较少的种群之外,1个种群为衰老型,其余4个种群均为增长型;3个种群呈随机分布类型,其余4个种群呈聚集分布类型,19个非珍稀植物种群中,1个种群为衰老型,6个种群为稳定型,其余12个种群为增长型;2个种群为随机分布类型,其余的17个种群为聚集分布类型．可见在26个种群中,以增长型种群居多(占66．7％),稳定型种群次之(占25．0％),衰老型种群最少(占8．3％);两种分布格局判定方法所得的结果较为一致,表现为种群的分布格局类型以聚集分布居多(占80．77％),随机分布和均匀分布较少。     

基于花青素代谢培育蓝色花卉的研究进展

花色是植物吸引昆虫传播花粉的主要因素,对于植物在自然界的生存必不可少,也是观赏植物最重要的性状之一。在蓬勃发展的花卉产业中,色彩各异花卉的培育,可以弥补自然花色的匮乏,但是令人垂涎的蓝色花比较难培育。花色的多样性主要是由花青素及其衍生物的种类和含量等因素决定的,飞燕草色素的合成是形成蓝色花的关键因素,许多植物体内缺少合成飞燕草色素的结构基因。近年来,利用基因工程技术培育蓝色花的研究也时有报道。文中以常见的观赏植物为例,基于花青素代谢调控,从影响飞燕草色素合成的关键因素和不同分子改良途径培育蓝色花等几个方面对植物花朵呈色的机制进行了综述,并展示不同分子育种策略可能在其他领域的应用,为其他植物或经济作物的色泽改良如彩色棉蓝色纤维的培育等提供参考和技术支持。