植物miRNA参与调控作物农艺性状的研究进展

植物microRNA (miRNA)是一类长度约为20～24 nt的内源非编码小RNA,它们通过在转录后水平调控靶基因的表达,在植物的生长发育、逆境响应和环境适应等过程中起着关键作用. miRNA对水稻、玉米、大豆等重要经济作物的农艺性状也起着重要的调控作用,在改良农作物性状上具有重大的应用潜能.本文重点介绍了参与作物农艺性状(如株型、花期、种子发育及抗逆等)调控的关键miRNA及其调控途径,同时总结了miRNA参与作物性状改良的主要研究方法和手段,并讨论了miRNA在作物性状改良应用中的前景.     

硫化氢对抗脑缺血再灌注损伤的机制研究进展

硫化氢（H2S）是一种新型内源性气体信使分子,在许多生理和病理生理过程中,尤其在神经保护中,扮演重要角色,既是神经调节剂, 也是神经保护剂。近年来的研究发现,H2S对于脑缺血再灌注损伤具有积极的防治作用,它可通过抗氧化应激、抗炎及抗细胞凋亡等多个途径, 对脑缺血再灌注损伤起保护作用,具有良好的临床应用前景。简介脑内H2S生成途径,综述H2S在中枢神经系统中的生物学效应及其对脑 缺血再灌注损伤的保护作用与机制研究进展,以期为脑缺血再灌注损伤的临床防治提供新思路。     

硫化氢在植物中的生理功能及作用机制

硫化氢(H₂S)是继一氧化氮(NO)和一氧化碳(CO)之后第3个气体信号分子, 在植物体内参与许多重要的生理活动, 能够促进植物光合作用和有机物的积累, 缓解各种生物和非生物胁迫并促进植物生长发育。该文综述了植物体内H₂S的物理化学性质、产生机制、主要生理功能和作用机制以及与其它信号分子的互作关系, 并展望了H₂S信号分子的研究前景。     

小菜蛾对定虫隆的抗性生化机制初探

以定虫隆汰选的抗性指数为23.78倍抗性种群(CH-R),并以上海田间种群(SH-R,对定虫隆的抗性指数为9.16倍)作为参比种群,研究小菜蛾Plutella xylostlla(L.)对定虫隆的抗性机制,结果表明：CH—R种群多功能氧化酶O-脱甲基活力比相对敏感种群(SZ-S)提高1倍,而SH-R种群多功能氧化酶O-脱甲基活力虽有所提高,但与SZ-S种群相比差异并不显著;CH-R和SH-R种群羧酸酯酶比活力均明显高于Sz-S种群,分别为SZ-S种群的4.61和2.18倍,且CH-R种群的Km仅为SZ-S种群的1/20;酸性磷酸酯酶和碱性磷酸酯酶比活力种群间无明显差异;CH-R种群的几丁质酶活力降低48%,酚氧化酶活力降低60%。说明小菜蛾对定虫隆的抗性机制具有多因子性,多功能氧化酶解毒代谢能力的提高可能是主导抗性机制之一,羧酸酯酶、几丁质酶和酚氧化酶也参与了小菜蛾对定虫隆的抗性。     

Transcriptome and miRNAs analyses enhance our understanding of the evolutionary advantages of polyploidy

Polyploid organisms have more than two sets of chromosomes, including autopolyploid via intraspecific genome doubling, and allopolyploid via merging genomes of distinct species by hybridization. Polyploid organisms are widespread in plants, indicating that polyploidy has some evolutionary advantages over its diploid ancestor. Actually, polyploidy is always tightly associated with hybrid vigor and adaptation to adverse environmental conditions. However, why polyploidy can develop such advantages is poorly known. MicroRNAs (miRNAs) are endogenous ～21?nt small RNAs which can play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression. MicroRNAs are essential for cell development, differentiation, signal transduction, and show an adaptive response to biotic and abiotic stresses. Environmental stresses cause plants to over- or under-express certain miRNAs or synthesize new miRNAs to cope with stress. We have here reviewed our current knowledge on the molecular mechanisms, which can account for the evolutionary advantages of polyploidy over its diploid ancestor from genome-wide gene expression and microRNAs expression perspectives.     

人类细胞色素P450与药物氧化代谢遗传多态性分子机制的研究现状

近年,在表型及基因型上均发现存在药物氧化代谢多态性,特别是对于人类细胞色素Ｐ４５０氧化酶与药氧化代谢遗传多态性的关系进行了深入的研究。有关ＣＹＰ２Ｄ６、ＣＹＰ２Ｃ１９等的突变已大多被鉴定;ＣＹＰ１Ａ１、ＣＹＰ１Ａ２等在表型存在多态性而确切的遗传机制尚不清楚。     

A Comparison of CO2 Uptake by the Green Algae Tetraedron minimum and Chlamydomonas monoica

Abstract: The ability of the green alga Tetraedron minimum to acquire inorganic carbon from its environment was investigated and compared with that of Chlamydomonas monoica. T. minimum showed a higher affinity for bicarbonate ions than C. monoica, regardless of whether it was grown at high or low CO₂ concentrations. Furthermore, T. minimum was distinguished by the fact that it maintained a large intracellular pool of inorganic carbon. These features may explain why this alga is able to proliferate in alkaline conditions.     

抗菌肽的研究进展

抗菌肽又称抗微生物肽(antimicrobial peptide)或肽抗生素(peptide antibiotics),在动植物体内分布广泛,是天然免疫防御系统的一部分。抗菌肽不仅有广谱抗细菌能力,而且对真菌、病毒及癌细胞也有作用。对抗菌肽作用机理的研究是近来的热点之一,本文综述了此方面近来的进展,并对微生物针对抗菌肽的耐药性进行了讨论。     

贵州喀斯特山区野生葡萄实生苗抗旱机理研究

以4份2生年喀斯特山区野生葡萄实生苗为试材,通过塑料大棚盆栽试验研究了自然干旱胁迫下野生葡萄幼苗的外观形态特性和生理指标变化规律,探讨其抗旱性及其抗旱机理.结果表明;(1)4份野生葡萄的抗旱性存在明显差异,以葛藟葡萄'小七孔-3'的抗旱性最强,毛葡萄'天河潭-2'的最差.(2)干旱胁迫期间,'小七孔-3'的1级旱害症状出现时间比'天河潭-2'晚12d,且旱害指数始终小于其他3份种质.(3)抗旱性强的野生葡萄叶片相对含水量、可溶性蛋白含量高于抗旱性差的株系,而其叶片水分饱和亏、细胞膜透性、丙二醛(MDA)含量变化则相反,且材料间差异随着干旱程度的增强而增加;(4)野生葡萄叶片相对含水量与其旱害指数间呈极显著负相关,而其水分饱和亏、相对电导率、丙二醛含量与旱害指数间呈极显著正相关;细胞膜脂过氧化产物丙二醛含量增加是导致葡萄旱害的首要因素.研究发现,在干旱胁迫下,抗旱性强的野生葡萄叶片膜系统稳定,水分散失较少,细胞电解质外渗较低,渗透调节物质可溶性蛋白含量增加,从而维持了正常的生理代谢活动.     

A “GC-rich” method for mammalian gene expression: A dominant role of non-coding DNA GC content in regulation of mammalian gene expression

High mammalian gene expression was obtained for more than twenty different proteins in different cell types by just a few laboratory scale stable gene transfections for each protein. The stable expression vectors were constructed by inserting a naturally-occurring 1.006 kb or a synthetic 0.733 kb DNA fragment (including intron) of extremely GC-rich at the 5′ or/and 3′ flanking regions of these protein genes or their gene promoters. This experiment is the first experimental evidence showing that a non-coding extremely GC-rich DNA fragment is a super “chromatin opening element” and plays an important role in mammalian gene expression. This experiment has further indicated that chromatin-based regulation of mammalian gene expression is at least partially embedded in DNA primary structure, namely DNA GC-content.