A single amino acid defines cross-species reactivity of tree shrew (Tupaia belangeri) CD1d to human invariant natural killer T (iNKT) cells

P>The non-classical major histocompatibility complex (MHC) class I molecule CD1d presents lipid antigens to invariant natural killer T (iNKT) cells, which are an important part of the innate immune system. CD1d/iNKT systems are highly conserved in evoluti

蛋白质可能作为遗传信息的载体吗?

分子生物学的“中心法则表明”: 遗传信息的方向是从DNA-RNA-蛋自质. 然而, 截止目前为止, 中心法则仍未从控制论和信息论获得足够的理论支持. 此外, 生物学中的一些特殊情况, 例如, 虽然用碱可使羊骚痒病基因不可逆地失活, 但用对核酸具专一修饰作用的5种方法却都未能使其失活; 另外, 当间期细胞被某些因素激活并造成分裂时, 在 DNA 合成之前蛋白质的合成就已经开始等, 也都很难用中心法则来解释清楚. 基于正常的翻泽过程, 也能容易地“设计”一个逆翻译机制的大概轮廓, 并且这种机制既可以证明为什么中心法则没有理论基础,同时又可以说明遗传密码的简并性。

半乳糖神经酰胺脂质体对HIV-1感染性的影响

目的研究体外空白及包封抗HIV药物和PFA的GalCer脂质体对HIV-1复制的影响。方法通过HIV p24抗原测定、合胞体抑制实验、融合阻断实验和对HIV感染细胞的保护作用实验等，观察了空白GalCer脂质体、AZT-GalCer脂质体和PFA-GalCer脂质体对HIV-1复制的影响。结果空白GalCer脂质体预处理细胞，能促进HIV-1感染CD4＋细胞；空白GalCer脂质体预处理HIV-1，则抑制了病毒吸附和结合宿主细胞；GalCer脂质体还具有阻断HIV-1感染细胞与正常CD4＋细胞间的融合作用；GalCer脂质体包封AZT或PFA不能显著提高药物体外抗HIV-1活性。结论空白GalCer脂质体预处理细胞，能促进HIV-1感染性；预处理HIV-1，则抑制了病毒的感染。

Sleeping sites, sleeping trees, and sleep-related behaviors of black crested gibbons (Nomascus concolor jingdongensis) at Mt. Wuliang, central Yunnan, China

Data on sleep-related behaviors were collected for a group of central Yunnan black crested gibbons (Nomascus concolor jingdongensis) at Mt. Wuliang, Yunnan, China from March 2005 to April 2006. Members of the group usually formed four sleeping units (adult male and juvenile, adult female with one semi-dependent black infant, adult female with one dependent yellow infant, and subadult male) spread over different sleeping trees. Individuals or units preferred specific areas to sleep; all sleeping sites were situated in primary forest, mostly (77%) between 2,200 and 2,400 m in elevation. They tended to sleep in the tallest and thickest trees with large crowns on steep slopes and near important food patches. Factors influencing sleeping site selection were (1) tree characteristics, (2) accessibility, and (3) easy escape. Few sleeping trees were used repeatedly by the same or other members of the group. The gibbons entered the sleeping trees on average 128 min before sunset and left the sleeping trees on average 33 min after sunrise. The lag between the first and last individual entering the trees was on average 17.8 min. We suggest that sleep-related behaviors are primarily adaptations to minimize the risk of being detected by predators. Sleeping trees may be chosen to make approach and attack difficult for the predator, and to provide an easy escape route in the dark. In response to cold temperatures in a higher habitat, gibbons usually sit and huddle together during the night, and in the cold season they tend to sleep on ferns and/or orchids.

小鲤地理分化的研究

小鲤Ｃｙｐｒｉｎｕｓ（Ｍｅｓｏｃｙｐｒｉｎｕｓ）ｍｉｃｒｉｓｔｉｕｓ分布于云南省的滇池、抚仙湖和星云湖。对历年馆藏和作者近年定期野外收集的２００尾标本和生态资料进行综合分析的结果表明：小鲤已分化为两个地理亚种，即滇池特有的小鲤指名亚种Ｃ．（Ｍ．）ｍｉｃｒｉｓｔｉｕｓｍｉｃｒｉｓｔｉｕｓＲｇｅｇａｎ和分布于抚仙湖、星云湖的抚仙小鲤Ｃ．（Ｍ．）ｍｉｃｒｉｓｔｉｕｓｆｕｘｉａｎｅｎｓｉｓＹａｎｇｅｔａｌ．，亚种间形态的分化主要表现在头长、尾柄长、眼间距与有关部分的比值、侧线鳞和背鳍前鳞的数目等方面；亚种间主要形态特征的分化是在长期的演化过程中适应不同的湖泊环境而产生的；小鲤亚种间繁殖生物学特性的分化主要表现在产卵行为、卵径、繁殖力以及达初次性成熟的年龄等方面；此外，亚种间在其空间分布、食性、年龄和生长等生态学特性上均表现出不同程度的分化。

Prefrontal white matter abnormalities in young adult with major depressive disorder: A diffusion tensor imaging study

Prefrontal impairments have been hypothesized to be most strongly associated with the cognitive and emotional dysfunction in depression. Recently, white matter microstructural abnormalities in prefrontal lobe have been reported in elderly patients with ma

关注会计信息的管理价值—管理会计的过去、现在和未来

市场环境的改变,推动了管理会计的发展.而对管理会计而言,所有的创新都来自管理会计体制的创新.归根结底,没有信息系统的创新就没有管理会计的发展.

五步蛇蛇毒磷脂酶A_(2)的纯化及部分性质

从五步蛇蛇毒中纯化一种均一的酸性磷脂酶A_(2)。SDS-PAGE测得分子量为15.8KD, 按氨基酸残基计算其分子量为14.352KD, IEF-PAGE测得等电点为5.32。氨基酸组分分析表明磷脂酶A_(2)分子由128个氨基酸残基组成, 富含Asp和Glu, 不含中性糖。PLA_(2)酶活性 的最适温度为45℃, 最适pH为8.5左右, 没有抗胰蛋白酶的活性, 具有一定的热稳定性。K~(+)、Ca~(++)和Na~(+)离子激活, 而Ca~(++)、Sn~(++)、Cu~(++)、Li~(++)、Hg~(++)、Zn~(++)、Fe~(++)和Co~(++)离子可抑制或完全丧失酶活力。图5表2参 10

用笛卡儿座标对菲氏叶猴和黑叶猴颅骨的比较形态研究

黑叶猴的颅骨大于菲氏叶猴, 显著性增大的区域出现在眉点、囟门、枕骨大 孔附近和下颌骨体的高度。但菲氏叶猴较黑叶猴具有更凸的面颅。据枕骨隆突 至眉点的侧视投影弧长, 两种叶猴的数学模式均为: Y=a+bX-cX~(2)(R=0.29) 。还比较了两叶猴颅骨的其他同异。图3 表3参15

中国鸟类一新纪录——楔嘴鹩鹛

1990年夏、秋季在云南西北部贡山县独龙江地区考察时, 于11月12日在高黎贡山北段西坡(东经98°23′; 北纬27°44′)海拔2010m 的常绿阔叶次生原始林的林下沟谷中网获一鸟, 经鉴定, 确认为楔嘴鹩鹛 Sphenocichla humei (Mandelli) 据文献记载, 楔嘴鹩鹛分布局限于锡金、阿萨姆和缅甸东北部. 此次所获标本, 第第一次发现其在中国分布, 为国内鸟类种的新纪录。

Expression, purification and characterization of recombinant Jerdonitin, a P-II class snake venom metalloproteinase comprising metalloproteinase and disintegrin domains

Jerdonitin is a P-II class snake venom metalloproteinase comprising metalloproteinase and disintegrin domains. In this study, we established a high-level expression system in Pichia pastoris and developed a purification strategy for the recombinant Jerdonitin. This recombinant Jerdonitin degraded fibrinogen at a level of activity comparable with its wild type. The effects of recombinant Jerdonitin on inhibiting ADP-induced human platelet aggregation were in a dose-dependent manner with an IC50 of 248 nM. In addition, we reported here that Jerdonitin can significantly inhibit the growth of several cell lines, including human liver cancer cells (Bel7402), human leukemia cells (K562) and human gastric carcinoma cells (BGC823). This study offers recombinant Jerdonitin that will be valuable for further functional and structural studies of Jerdonitin. (C) 2009 Elsevier Ltd. All rights reserved.