APP N端片段的神经营养作用

APP是β－淀粉样肽的前体蛋白,由695－770个氨基酸经,春N端水解产物可分沁至细胞外环境。AP具有促进神经细胞生长作用,其中319－335肽段即APP17肽能提高动物的学习记忆能力。其他APP片段是否具有神经营养功能未见报道。本研究通过观察APP N端片段对人神经母细胞瘤株SY5Y生长的影响以及对实验性糖尿病动物行为的影响,希望APP促进神经细胞生长的其他肽段。用化学合肥APP N端多肽片段,以SY5Y细胞MTT代谢率、细胞计数、LDH漏出率和实验性糖尿病小鼠水迷宫试验结果为观察指标。结果APP64肽、29肽、11肽均有促进SY5Y细胞生长的作用,APP11肽可提高糖尿病动物水迷宫测试成绩,说明可溶性APP的N端可能具有神经营养作用,我们认为保持此作用的最短片段为APP11肽,此肽段的发现为进一步研究APP的构效关系奠定了基础。     

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。     

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。     

The life cycle of the gastrin granule

Summary The ultrastructure of gastrin cells in the rat antrum was analyzed with standardized and quantitative planimetric methods. Resting and active cells were compared. The gastrin cells were activated by removal of the acidproducing part of the stomach (fundectomy). As a result the serum gastrin concentrations were greatly elevated. Compared with gastrin cells in fasted control rats the gastrin cells in fundectomized rats were increased in number, contained fewer cytoplasmic granules, increased amount of endoplasmic reticulum, and an enlarged Golgi area.Generally, the secretory granules of the gastrin cell displayed a wide range of electron density from highly electron-dense to electron-lucent. They exhibited certain characteristic features: 1) Electron-dense granules made up a greater proportion of the total granule population in active gastrin cells than in resting cells. 2) Electron-dense granules were more frequent near the Golgi stacks than in the periphery of the cell. 3) Electron-dense granules were smaller in size than the electron-lucent granules; hence, small electron-dense granules probably represent young granules (progranules), while large, electron-lucent granules represent mature (old) granules. 4) Electron-dense granules invariably displayed a more intense immunoreactivity than electron-lucent granules.The gastrins are generated from a large precursor molecule. The posttranslational processing of this precursor is reflected in the gastrin-component pattern. The gastrin-component pattern in antral extracts of fundectomized and normal fasting rats differed in that the proportion of the gastrin-4-like component was reduced, whereas the gastrin-34-like component was increased in the fundectomized rats. The results suggest a greater proportion of small gastrin components in the mature granules than in the newly formed ones, presumably due to more extensive conversion of larger forms into smaller forms with a longer granule half-life. As a result gastrin-17-and gastrin-34-like components make up a larger proportion of total gastrin in active gastrin cells than in resting gastrin cells.The findings were presented at the Meeting of the European Gastro-Club, Erlangen, October 1980 (R. Håkanson, J.F. Rehfeld, M. Ekelund, and F. Sundler 1981)     

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.     

Topography of somatostatin cells in the stomach of the rat: Possible functional significance

Summary Somatostatin cells in the stomach of the rat have a characteristic shape and distribution. In the antral mucosa they occur together with gastrin cells and enterochromaffin cells at the base of the glands. In the oxyntic mucosa they are scattered along the entire glands with some predominance in the zone of parietal cells. Throughout the gastric mucosa the somatostatin cells possess long and slender processes that emerge from the base of the cell and end in clublike swellings. Such processes appear to contact a certain proportion of neighbouring gastrin cells in the antral mucosa and parietal cells in the oxyntic mucosa.Exogenous somatostatin given by intravenous infusion to conscious rats counteracted the release of gastrin stimulated by feeding, elevated antral pH or vagal excitation. Gastrin causes parietal cells to secrete HCl and endocrine cells in the oxyntic mucosa to mobilise and synthesise histamine. Somatostatin is known to block the response of the parietal cells to gastrin. In contrast, somatostatin did not block the response of the histamine-storing endocrine cells to gastrin, perhaps because these endocrine cells lack receptors to somatostatin. Conceivably, somatostatin in the gastric mucosa has a paracrine mode of action. The observations of the present study suggest that somatostatin may affect some, but not all of the various cell types in the stomach. Under physiological conditions this selectivity may be achieved in the following ways: 1) Communication may be based on direct cell-to-cell contact. 2) Only certain cell types are supplied with somatostatin receptors.