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71.
提出一种在给定构象下计算蛋白质多肽链中所有二面角的新方法.通过总体最小二乘法将每 个肽单位中的6个原子拟合为1个肽平面,将连续平面之间包含的角定义为二面角,并以数值实验证明了该方法的有效性.精确的二面角值对很多蛋白质分析方法意义重大,特别是将二面角作为基本结构参数的同源建模法. 相似文献
72.
MENG Yan ZHAO ChunYan ZHANG XueXin ZHAO HuaShan GUO LiRong Lü Bin ZHAO XueJian& YANG BaoXue Department of Pathophysiology School of Basic Medicine Jilin University Changchun China Department of Physiology Department of Medicine University of California San Francisco CA USA 《中国科学:生命科学英文版》2009,52(5):474-478
73.
BAO Lei CHEN HaiDe JONG UiMyong RIM CholHo LI WenLing LIN XiJuan ZHANG Dan LUO Qiong CUI Chun HUANG HeFeng ZHANG Yan XIAO Lei FU ZhiXin 《中国科学:生命科学英文版》2014,57(2):263-268
Genetically modified pigs are valuable models of human disease and donors of xenotransplanted organs.Conventional gene targeting in pig somatic cells is extremely inefficient.Zinc-finger nuclease(ZFN)technology has been shown to be a powerful tool for efficiently inducing mutations in the genome.However,ZFN-mediated targeting in pigs has rarely been achieved.Here,we used ZFNs to knock out the porcineα-1,3-galactosyl-transferase(GGTA1)gene,which generates Gal epitopes that trigger hyperacute immune rejection in pig-to-human transplantation.Primary pig fibroblasts were transfected with ZFNs targeting the coding region of GGTA1.Eighteen mono-allelic and four biallelic knockout cell clones were obtained after drug selection with efficiencies of 23.4%and 5.2%,respectively.The biallelic cells were used to produce cloned pigs via somatic cell nuclear transfer(SCNT).Three GGTA1 null piglets were born,and one knockout primary fibroblast cell line was established from a cloned fetus.Gal epitopes on GGTA1 null pig cells were completely eliminated from the cell membrane.Functionally,GGTA1 knockout cells were protected from complement-mediated immune attacks when incubated with human serum.This study demonstrated that ZFN is an efficient tool in creating gene-modified pigs.GGTA1 null pigs and GGTA1 null fetal fibroblasts would benefit research and pig-to-human transplantation. 相似文献
74.
Mental states such as stress and anxiety can cause heart disease.On the other hand,meditation can improve cardiac performance.In this study,the heart rate variability,directed transfer function and corrected conditional entropy were used to investigate the effects of mental tasks on cardiac performance,and the functional coupling between the cerebral cortex and the heart.When subjects tried to decrease their heart rate by volition,the sympathetic nervous system was inhibited and the heart rate decreased.When subjects tried to increase their heart rate by volition,the parasympathetic nervous system was inhibited and the sympathetic nervous system was stimulated,and the heart rate increased.When autonomic nervous system activity was regulated by mental tasks,the information flow from the post-central areas to the pre-central areas of the cerebral cortex increased,and there was greater coupling between the brain and the heart.Use of directed transfer function and corrected conditional entropy techniques enabled analysis of electroencephalographic recordings,and of the information flow causing functional coupling between the brain and the heart. 相似文献
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76.
Human disturbance and climate change have increased the risk of extinction for rare and endangered wild plant species.One effective way to conserve these rare and endangered species is through reintroduction.In this review,we summarize the advances in wild plant reintroduction from five perspectives:the establishment of reintroduction biology as an important tool for biodiversity conservation;the importance of genetic diversity in reintroduction;reintroduction under global climate change;recruitment limitation in reintroduction;and reintroduction and ecological restoration.In addition,we consider the future of plant reintroduction strategies. 相似文献
77.
XIA HaiYong ZHAO JianHua SUN JianHao XUE YanFang EAGLING Tristan BAO XingGuo ZHANG FuSuo LI Long 《中国科学:生命科学英文版》2014,57(3):362-362
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79.
Alam Md. Asraful WAN Chun ZHANG Xiao-yue GUO Suo-lian ZHAO Xin-qing BAI Feng-wu 《微生物学杂志》2014,(6):49-54
微藻是可广泛用于健康食品及水产养殖的饵料,同时,微藻细胞内积累的油脂可作为可再生生物燃料,因此微藻的生长和代谢受到广泛关注。温度和pH对微藻的生物量积累有很大影响,考察不同温度和pH条件下微藻细胞的生长有助于寻找最佳的条件进行微藻的培养。自絮凝小球藻JSC-7(Chlorella vulgaris JSC-7)可实现自沉降采收,有利于降低微藻生产成本,优化其生长条件对更好地利用该微藻具有重要意义。考察了温度(22∽40℃)及pH(6.0∽10.0)对其细胞生长、叶绿素含量和油脂产量的影响。在所选取的温度及pH范围内,JSC-7细胞均可生长,显示该藻种可以适应广泛的温度和pH条件。适合细胞生长的温度依次为31℃〉28℃〉35℃〉25℃,pH依次为7.0〉8.0〉6.0。pH 8.0时生物量和油脂的积累量最多,说明该藻株在弱碱条件下更适合生长和产油。当温度为31℃、pH为7.0时,可获得最高的生长量(OD690=0.941)、叶绿素含量(19 mg/L)及油脂产量(39.07%/克干重)。 相似文献
80.
一步法提取植物DNA用于大规模RAPD分析 总被引:25,自引:0,他引:25
RAPD技术已广泛地用于植物的系统演化、种群多样性、群体遗传学及杂种种子纯度的鉴定等工作中〔1~3〕。本文基于快速节省的原则对碱液法提取植物DNA进行一些改进。1材料与方法DNA提取方法取10~20mg幼叶 ,加100μl0 5mol/LNaOH(或附加0 5 %~1 5 %巯基乙醇)研磨后 ,取40μl研磨液加入200μl100mmol/LTris HClpH7 6缓冲液(或附加0 5%不溶性聚乙烯吡咯烷酮 ,PVP)中 ,8000×g离心5min,上清液即可用于PCR反应。PCR反应体系含10mmol/LTri… 相似文献