水稻品种与氮肥施用水平对田间褐飞虱发生的影响

于2010年在田间条件下研究了水稻品种和氮肥施用水平(250 kg/hm2有效氮,125 kg/hm2有效氮及不施氮肥的处理)对褐飞虱Nilaparvata tugens(St(a)l)发生的影响.结果表明,8月10日-9月10日期间,南粳44、宁粳1号、丙123、淮稻9号4个水稻品种上褐飞虱虫量显著低于感虫对照TN1...     

应用RNA干扰沉默猪内源性反转录病毒

目的:尝试应用RNA干扰(RNAi)沉默猪源PK-15细胞中的猪内源性反转录病毒(PERV),并通过反转录酶活性及pol基因相对荧光定量PCR检测沉默效果。方法:依据GenBank公布的PERV pol基因序列,采用Invitro-gen公司的BLOCK-iT RNAi Designer软件设计Stealth小干扰RNA(siRNA)序列;将合成的siRNA转染PK-15细胞,72 h后检测细胞上清PERV反转录酶活性及细胞内pol基因拷贝数并评价沉默效果。结果:反转录酶活性及pol基因拷贝数检测结果表明,设计的3条Stealth siRNA序列中,位于pol基因3272～3296 bp的序列能有效沉默PERV。结论:RNAi方法可有效使猪源PK-15细胞中的PERV沉默,为进一步研究天然抗病毒分子与PERV的相互作用提供了实验基础,同时也为猪源异种移植研究中去除PERV提供了一种可供尝试的方法。     

缺血性脑卒中患者同型半胱氨酸代谢相关酶基因突变的研究

为研究同型半胱氨酸代谢相关酶亚甲基四氢叶酸还原酶(MTHFR)基因C677T和胱硫醚-β-合成酶(CBS)基因T833C位点碱基突变与缺血性脑卒中的关系,对74例缺血性脑卒中患者和83例健康对照者,采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)技术检测MTHFR基因C677T基因型,用扩增阻滞突变体系法(ARMS)检测CBS基因T833C突变。实验检出患者组MTHFR基因T纯合基因型、杂合基因型和T等位基因频率分别为2.7％、51.4％和28.4％,对照组分别为1.2％、39,8％和21.1％。患者组CBS基因C纯合基因型和C等位基因频率分别为13.5％和43.9％,对照组分别为6.0％和38.0％。Multiple Logistic Regression分析显示;C677T位点T等位基因,T833C位点C等位基因以及年龄均与缺血性脑卒中发病有关(P<0.05),C677T位点T等位基因的比值比(OR)为1.74(95％CI 1.06～2,B6)和T833C位点C等位基因的比值比为1.73(95％CI 1.07～-2.81)。实验显示MTHFR C677T和CBS T833C基因位点突变与缺血性脑卒中发病有关,上述两个基因位点突变可能是缺血性脑卒中发病的遗传因素。     

鸟苷发酵过程的多尺度问题研究

以鸟苷发酵为对象,在生物反应器中以多尺度问题的角度,对在线计算机数据进行相关分析,结合中间代谢物及有关酶活性的检测,建立了以代谢流为核心的多尺度调控方法;又通过与代谢流迁移有关的动态化学计量分析,实现了对批式发酵过程的时变系统估算,建立了主体代谢与产物形成的支路代谢间,包括能量与物质流的关系模型;最后,把具有不同生产能力菌株的关键基因与基因库数据进行了序列比较,发现了本文研究的菌株已具备高产能力,即编码sAMP合成酶的基因发生移码突变以及pur操纵子的多处突变,而中心代谢流迁移是过程优化的关键。对开展微生物功能基因组学的研究和工业过程优化的问题进行了探讨,作者提出有必要从生物反应器的系统生物学高度来认识和解决所面临的问题。     

被子植物成花诱导和性别决定机制的研究进展

开花植物具有多样性的生殖系统,其中单性花的形成是促进异交、避免自交衰退、保持遗传多样性的重要途径。单性花物种分布于被子植物不同进化分支上的事实表明,物种的雌雄异花性可能是通过不同的机制进化形成的。本文从花发育、性染色体、植物激素和环境因素四个方面,阐述了被子植物性别分化调控机制的研究进展。     

Expression and Purification of a Spider Silk Protein: A New Strategy for Producing Repetitive Proteins

Synthetic genes were constructed based on the known sequence of the spider dragline silk protein MaSp 2. The genes had 8, 16, or 32 contiguous units of the consensus repeat sequence of the protein. These artificial genes were constructed using a strategy involving compatible but nonregenerable restriction sites, which allowed construction of very large inserts in a precisely controlled manner. This strategy should have general utility in the controlled construction of repetitive proteins composed of identical or different repeat units. The protein from the 16-unit repeat was produced inEscherichia coliat levels up to 10 mg/g wet wt of cells although yields of 1–2 mg/g were more typical. The protein was easily purified with high recovery using an affinity column. The purified protein had the predicted amino acid composition and N-terminal sequence after cleavage of a leader sequence. The methodology described will allow production of sufficient quantities of protein for basic structure/function studies including production of synthetic fibers.     

Central muscarinic modulation of fetal blood pressure and heart rate

It has previously been demonstrated that the fetal lamb cardiovascular system can respond to peripheral muscarinic stimulation. However the role of central muscarinic mechanisms in modulating fetal cardiovascular function has not been described. Pilocarpine is a muscarinic agonist that readily crosses the blood-brain barrier and was therefore employed to examine both central and peripheral muscarinic mechanisms in modulating fetal cardiovascular function. Fetal lambs were prepared for chronic intrauterine recording of fetal blood pressure (FBP) and heart rate (FHR). Direct administration of pilocarpine to the fetus resulted in an immediate dose-dependent decrease in both systolic and diastolic blood pressure and a rapid fall in FHR. The initial phase of hypotension was very short-lived (1-2 min) and was subsequently followed by a significant increase in systolic, diastolic and pulse pressures (30-60 min). Fetal heart rate gradually returned to control levels by 30 min after pilocarpine administration. Atropine pretreatment was effective in completely blocking the cardiovascular actions of pilocarpine, while methylatropine was only able to block the initial hypotensive and bradycardiac response. A prolonged tachycardia was also unmasked by methylatropine pretreatment. These data suggest that the initial hypotension and bradycardia in response to pilocarpine administration are mediated via peripheral muscarinic receptors, while stimulation of central muscarinic receptors result in hypertension and tachycardia. These data confirm that, as in the adult, central cholinergic mechanisms are involved in the modulation of cardiovascular function in the developing fetus.     

Etiology and control of durian foliar blight and dieback caused by Rhizoctonia solani

Foliar blight and dieback of durian seedlings and trees in Peninsular Malaysia was found to be caused by Rhizoctonia solani (teleomorph - Thanatephoms cucumeris) The fungus grew well and produced abundant sclerotia at temperatures higher than 24°C with an optimum at 28°C. It grew poorly at 35°C and did not grow at 10°C. The strains studied were found to belong to the anastomosis group AG-1. They were pathogenic on durian, papaya, cucumber, long bean, Mikania weed, padi, musk melon, mung bean, Zoysia grass, Bermuda grass, and St Augustine grass. They were mildly pathogenic on groundnut, and non-pathogenic on maize, guava and Brassica‘pak choy’. The disease was effectively controlled by foliar sprays of pencycuron and benomyl; triadimefon and an antagonistic bacterium suspension treatment were less effective and quintozene-etridiazole mixture gave poor disease control.     

Growth Regulator Interactions in the Growth of the Shoot System of Avena sativa Seedling: II. THE GROWTH OF THE FIRST LEAF AND THE COLEOPTILE1

1. Studies have been made of the growth in culture medium of thecomponent parts of compositesegments excised from 3 to 7-day-oldAvena sativa seedlings and comprising portions of coleoptileand first leaf bases and various lengths of first internodetissue.
2. The effects of various concentrations of gibberellicacid (GA)and indole-3- acetic acid (IAA) alone and in combinationhavebeen studied on the growth of these organs.
3. Both GA andIAA stimulate the growth of coleoptile base tissuebut in combinationtheir joint effects are less than additive.No synergism occurs.
4. The growth of the first-leaf base is greatly stimulated byGAbut is inhibited by IAA. In combination, the stimulatoryeffectof GA (up to 1 0 p.p.m.) may be virtually eliminatedby evenlow concentrations of IAA (0.01 p.p.m.).
5. The inclusionof first internode tissue in the segments considerablyincreasesthe growth of first leaf base tissue but has no consistenteffecton the growth of coleoptile base tissue. The presenceof firstinternode tissue also greatly increases the degreeof growthstimulation invoked by GA but does not influence thedegreeof IAA inhibition. It is postulated that the first internodetissue is the source of an unknown growth factor necessary forGA action in the first leaf and potentiating the action of endogenousgibberellin.
6. Kinetin, adenine sulphate, glutarnine, glutarnicacid, asparagine,glycine, arginine, histidine, lysine, aneurin,and pyridoxinewill not simulate the effects of this unknowngrowth factorin the growth of leaf tissue. Like IAA, kinetinvirtually eliminatesthe GA stimulation of leaf growth.
7. Astudy of extracts of internode tissue in various solvents,analysedby paper partition chromatography and assayed by thegrowthof the first leaf base, has indicated the presence ofgrowthinhibitors and gibberellin-like substances but has failedtoisolate the postulated endogenous GA-synergist.
8. The implicationsof these results for growth correlations andthe hormone controlof shoot growth in Avena sativa seedlingsis discussed.