Mitochondrial tRNA mutations associated with deafness

Mitochondrial tRNA mutations are one of the important causes of both syndromic and non-syndromic deafness. Of those, syndromic deafness-associated tRNA mutations such as tRNA(Leu(UUR)) 3243A>G are often present in heteroplasmy, while non-syndromic deafness-associated tRNA mutations including tRNA(Ser(UCN)) 7445A>G often occur in homplasmy or in high levels of heteroplasmy. These tRNA mutations are the primary mutations leading to hearing loss. However, other tRNA mutations such as tRNA(Thr) 15927G>A and tRNA(Ser(UCN)) 7444G>A may act in synergy with the primary mitochondrial DNA mutations, modulating the phenotypic manifestation of the primary mitochondrial DNA mutations. Theses tRNA mutations cause structural and functional alteration. A failure in tRNA metabolism caused by these tRNA mutations impaired mitochondrial translation and respiration, thereby causing mitochondrial dysfunctions responsible for deafness. These data offer valuable information for the early diagnosis, management and treatment of maternally inherited deafness.     

蛋白质组学技术在植物类囊体膜蛋白研究中的应用

类囊体作为植物光合作用光反应的重要场所,在植物亚细胞蛋白质组学研究中倍受关注.介绍了植物蛋白质组学相关技术,包括双向凝胶电泳(2DE)、高效液相色谱(HPLC)、高效毛细管电泳(HPCE)、质谱(MS)和蛋白质组学数据库在植物类囊体膜蛋白研究中的应用.同时对类囊体膜蛋白质组学的研究趋势进行了探讨.     

云南红豆杉紫杉烷2α-O-苯甲酰转运酶基因的克隆及定性

通过RACE技术,克隆了云南红豆杉紫杉烷2α-O-苯甲酰转运酶基因(TyTBT),该酶催化2-去苯甲酰-7,13-二乙酰巴卡亭Ⅲ生成7,13-二乙酰巴卡亭Ⅲ,是紫杉醇合成途径中的关键酶之一.TyTBT基因cDNA全长1481 bp,含有1 320 bp的开放读码框,编码440个氨基酸的多肽,分子量为50 050 Da,等电点为6.17.氨基酸序列比对表明TyTBT同植物酰化酶家族的其它成员有较高的相似性,超过67%,同东北红豆杉和曼地亚红豆杉的紫杉烷2α-O-苯甲酰转运酶氨基酸序列的一致性和相似性达到最高,分别为95%和96%.广泛地比对分析证明这种较高的相似性在红豆杉属的其它酶家族中具有普遍性,进化树分析表明同东北红豆杉和曼地亚红豆杉的紫杉烷2α-O-苯甲酰转运酶(TBT)的相似性高于紫杉醇合成途径中的其它酰化酶.     

水杉愈伤组织诱导及植株再生

通过愈伤组织诱导器官发生途径,建立了水杉（Metasequoia glyptostroboides）的植株再生体系,探讨了不同外植体（种胚、幼叶切块、茎段、根段）和植物生长调节剂对不定芽直接再生和愈伤组织诱导器官发生的影响。结果表明：以种胚、无菌苗叶片、茎段和根作为外植体,在MS补加2,4-D、NAA和6-BA不同组合的培养基上都能诱导得到愈伤组织,其中种胚诱导愈伤组织效果最好,诱导率可达100%,茎诱导效果次之,诱导率为97.1%。诱导愈伤组织效果较好的培养基有：MS＋1.0mg·L-12,4-D＋0.5mg·L-16-BA、MS＋0.1mg·L-16-BA＋1.0mg·L-1NAA、MS＋0.5mg·L-16-BA＋1.0mg·L-1NAA、MS＋1.0mg·L-16-BA＋1.0mg·L-1NAA、MS＋0.5mg·L-16-BA＋2.0mg·L-1NAA、MS＋1.0mg·L-16-BA＋2.0mg·L-1NAA和MS＋0.5mg·L-12,4-D＋0.5mg·L-1NAA。以愈伤组织在MS培养基上植株再生效果最好,再生率为62.5%。     

过表达水稻OsAQP增强转基因拟南芥耐盐性

水稻OsAQP是实验室前期从cDNA文库中筛选的功能未知的水通道蛋白质编码基因。本文采用DNA重组技术构建其植物过表达载体,并对拟南芥进行了遗传转化,筛选获得转基因拟南芥。采用50、100、125和150 mmol/L梯度盐胁迫处理,结果显示,转基因拟南芥的发芽率、根长以及鲜重分别比对照至少高17%、40.8%和14.29%,且差异达到显著水平（P<0.05）。在正常条件下,转基因植株叶片中抗坏血酸过氧化物酶(APX)活性显著高于WT;经300 mmol/L NaCl处理,转基因拟南芥叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)、APX酶活性均升高,与处理前相比分别提高7.37倍、30.87倍和1.77倍,且与WT的酶活性差异达到显著水平（P<0.05）;丙二醛(MDA)含量也在处理后上升,但在转基因植株中的含量低于WT,分别是WT的0.74倍、0.68倍和0.62倍,差异同样达到显著水平（P<0.05）。本研究提示,OsAQP过表达不仅能够促进拟南芥种子萌发和根系生长,而且在盐胁迫下通过提高拟南芥内源抗氧化酶活性、降低膜脂过氧化程度,增强了转基因植株对一定程度盐胁迫的耐受性。     

Phosphorylation of cardiac troponin I by mammalian sterile 20-like kinase 1

Mst1 (mammalian sterile 20-like kinase 1) is a ubiquitously expressed serine/threonine kinase and its activation in the heart causes cardiomyocyte apoptosis and dilated cardiomyopathy. Its myocardial substrates, however, remain unknown. In a yeast two-hybrid screen of a human heart cDNA library with a dominant-negative Mst1 (K59R) mutant used as bait, cTn [cardiac Tn (troponin)] I was identified as an Mst1-interacting protein. The interaction of cTnI with Mst1 was confirmed by co-immunoprecipitation in both co-transfected HEK-293 cells (human embryonic kidney cells) and native cardiomyocytes, in which cTnI interacted with full-length Mst1, but not with its N-terminal kinase fragment. in vitro phosphorylation assays demonstrated that cTnI is a sensitive substrate for Mst1. In contrast, cTnT was phosphorylated by Mst1 only when it was incorporated into the Tn complex. MS analysis indicated that Mst1 phosphorylates cTnI at Thr(31), Thr(51), Thr(129) and Thr(143). Substitution of Thr(31) with an alanine residue reduced Mst1-mediated cTnI phosphorylation by 90%, whereas replacement of Thr(51), Thr(129) or Thr(143) with alanine residues reduced Mst1-catalysed cTnI phosphorylation by approx. 60%, suggesting that Thr(31) is a preferential phosphorylation site for Mst1. Furthermore, treatment of cardiomyocytes with hydrogen peroxide rapidly induced Mst1-dependent phosphorylation of cTnI at Thr(31). Protein epitope analysis and binding assays showed that Mst1-mediated phosphorylation modulates the molecular conformation of cTnI and its binding affinity to TnT and TnC, thus indicating functional significances. The results of the present study suggest that Mst1 is a novel mediator of cTnI phosphorylation in the heart and may contribute to the modulation of myofilament function under a variety of physiological and pathophysiological conditions.     

Overexpression of Jatropha curcas Defensin (JcDef) Enhances Sheath Blight Disease Resistance in Tobacco

Plant defensins are small, basic, cysteine‐rich peptides, belonging to the antimicrobial peptide superfamily, commonly found in the plant kingdom. In this study, we cloned and characterized a plant defensin gene from Jatropha curcas (JcDef). JcDef carried conserved receptor binding sites and a cysteine motif, and it was phylogenetically grouped together with defensin Ec‐AMP‐D2‐like in Elaeis guineensis. JcDef is localized to cytoplasm and highly expressed in young tissues with fast metabolism such as cotyledons and stem apexes. Transgenic expression of JcDef in tobacco showed enhanced resistance against sheath blight disease caused by R. solani, indicating the antibacterial function.     

杜鹃花属的研究(二)

灌木,高1.5-3米。小枝适度地纤细,当年生者紫色,有鳞斑,约长4-5厘米,直径1-1.5毫米,一年生以上者淡黄色或褐色,无鳞斑。冬芽长圆锥状,鳞片覆瓦状排列,早落。叶薄纸质,狭窄或长圆状椭圆形,先端渐尖或近于钝尖状锐尖,基部楔形或钝形,长4.5-5厘米,宽1.2-2厘米,上面深绿色,有稀疏的鳞斑,下面淡绿色,有鳞斑,彼此间的距离,为其直径的2-3倍,中脉在上而略四陷,在下面稍凸起,侧脉不发育;叶柄有稀疏的鳞斑,长6-8毫米。     

Five New Guaiane Sesquiterpenes from the Endophytic Fungus Xylaria sp. YM 311647 of Azadirachta indica

Five new guaiane sesquiterpenes, 1 – 5 , were isolated from the culture broth of the endophytic fungus Xylaria sp. YM 311647, isolated from Azadirachta indica A. Juss . The structures of these compounds were elucidated on the basis of spectroscopic analyses, and their inhibitory activities against five pathogenic fungi were evaluated. All guaiane sesquiterpenes showed moderate or weak antifungal activities in a broth microdilution assay.