Protein synthesis is not required for the inhibitory effect of selenite on cell colony formation and RNA synthesis

Selenite has been shown to undergo intracellular metabolism that results in its conversion to other low molecular weight Secontaining species and also to its incorporation into a selenocysteine residue in selenoprotein. In order to investigate whether the incorporation into protein is required for the cytotoxic effects of selenite, we have examined whether inhibition of protein synthesis prevents the inhibitory effect of selenite on the ability of cells to form colonies or to synthesize RNA. We have found that treatment of HeLa cells with cycloheximide inhibited protein synthesis by >90% but had no effect on the inhibitory effect of selenite on cell colony formation or RNA synthesis. Since protein synthesis is not necessary for these cytotoxic effects of selenite they are unlikely to result from an increase in the synthesis of selenoproteins.     

The last 140 ka in the Afro-Asian arid/semi-arid transitional zone

During the last ten years, a great number of geological or other proxy records provided radiocarbon, U/Th or TL dated information on the past climatic oscillations in the arid/semi-arid zones extending between the Atlantic and the Pacific. Comparisons and a synthetic view of these results can now be attempted for the last 140 ka, and compared with global changes, as registered in oceanic or ice cores, and with palaeomonsson models: for this purpose, wide spatial and time scales have to be used. On the whole, arid/humid alternations roughly fit global changes, cold phases corresponding to an extension of the arid areas to the South, warm phases corresponding to the shrinking of the same to the North.

The last interglacial is associated with an increase of precipitation throughout the area considered. Isotopic stage 4 brings no evidence whatsoever of humid conditions. Two wetter episodes are registrated during stage 3. A major rainfall decrease is everywhere associated with the Last Glacial Maximum (21-15 ka in most regions), the arid or semi-arid zones extending several hundred kilometers southwards, relative to the present-day pattern. The two abrupt deglaciation steps and the Younger Dryas are recorded in all of the most sensitive regions, at the margins of the present-day monsoonal range. During the Holocene, the precipitation increases everywhere (by 100–400 mn, relative to the present-day values), the optimum being at 8.5-6.5 ka. A climatic deterioration follows with an irregular pattern of dry/wet episodes, according to the different geographic conditions. The humid phase terminates at 3.5-3 ka in the whole transitional zone.

The major southward shift of the monsoonal precipitation range since its optimum, some 8000 years ago, fits the astronomical neoglacial trend and may possibly be correlated with past stage 5d, although its rapidity and spatial importance may just reflect one of the sharp successive cold/warm variations registered by GRIP during the whole stage 5.     

旋毛虫肌幼虫ES抗原的基因克隆及高效表达

作者对编码旋毛虫肌幼虫ES抗原的部分结构基因进行了克隆、鉴定和表达。用RNA PCR技术直接从旋毛虫肌幼虫总RNA中反转录并扩增出0．7kh的靶DNA,酶切分析后将其克隆到融合表达载体pEx3lC中。SDS—PAGE电泳表明,含重组子的大肠杆菌能够表达出一分子量为37kDa的融合蛋白(P37),后者占菌体总蛋白的22%以上,并以包含体形式存在于菌体中。经对纯化后表达蛋白的ELlSA检测,证明它能被猪旋毛虫病阳性血清和抗旋毛虫单克隆抗体识别。研究结果揭示,重组蛋白P37对于研制旋毛虫病诊断抗原和免疫抗原具有潜在的应用价值。     

Specificity and function of monoclonal antibodies directed against Ewing sarcoma cells

A selection of 16 monoclonal antibodies has been produced against a fresh Ewing's sarcoma (ES) tumor mixed with a permanent ES cell line. The majority of antibodies identify an 80-kDa molecule, which is not detected on healthy tissues except on certain cultured monocytes. One antibody recognize the CD2 ligand MIC2 and 2 antibodies (numbers 13 and 16) define a higher-molecular-mass antigen. Antibody 16 is also expressed on mesenchymal fibroblasts of bone marrow or fetal origin. Tumorspecific antigen expression is potentially linked to the chromosome 22 abnormality decribed in Ewing's sarcoma.     

百合离体生殖细胞骨架的扫描电镜观察

从百合的花粉管分离出来的生殖细胞,经表面活化剂Ｔｒｉｔｏｎ Ｘ－１００ 及核糖核酸酶、硫酸铵离析处理。离析后的细胞经临界点干燥,扫描电镜观察显示：在离体生殖细胞的胞质内有一个非常复杂的支架网络系统。这一网络系统有内外两层：外层（靠近细胞膜）网络结构紧密,纤维束粗长;内层（靠近核）网络结构疏松,纤维束短细。一些间接证据显示,这一支架网络系统可能为微管骨架     

双价外壳蛋白基因植物表达载体的构建及马铃薯转基因植株的鉴定

在克隆了马铃薯Ｘ病毒（ＰＶＸ）、马铃薯Ｙ 病毒（ＰＶＹ）和马铃薯卷叶病毒（ＰＬＲＶ）的外壳蛋白基因的基础上,构建同时包含ＰＶＸ和ＰＶＹ 与ＰＶＹ 和ＰＬＲＶ 两个外壳蛋白基因植物表达框架的表达载体,通过农杆菌（Ａｇｒｏｂａｃｔｅｒｉｕｍ ｔｕｍｅｆａｃｉｅｎｓ）介导转化烟草（Ｎｉｃｏｔｉａｎａｔａｂａｃｕｍ ）和生产上常用的几个马铃薯（Ｓｏｌａｎｕｍ ｔｕｂｅｒｏｓｕｍ ）优良品种：“Ｆａｖｏｒｉｔａ”、“虎头”、“克４”。经ＰＣＲ检测证明外源基因已整合到植物的染色体上,得到批量转基因植株。在转ＰＶＸ＋ＰＶＹ 外壳蛋白基因的烟草上接种ＰＶＸ （５ μｇ／ｍ Ｌ）、ＰＶＹ（２０ μｇ／ｍ Ｌ）病毒,得到有一定抗性的植株     

花粉高尔基囊泡与牛脑微管的体外结合

把从榛木（Ｃｏｒｙｌｕｓａｖｅｌｌａｎａ Ｌ．）花粉中分离得到的高尔基囊泡与经高度纯化并聚合好的牛脑微管进行体外组合,然后于１．５ ｍ ｏｌ／Ｌ的蔗糖层上进行超离心,对其沉淀物进行ＳＤＳ－聚丙烯酰胺凝胶电泳和电镜负染。结果表明,花粉高尔基囊泡可以结合到牛脑微管上,证明植物花粉的高尔基囊泡与动物细胞的某些细胞器一样,也与细胞骨架的主要组成之一——微管具有结构上的紧密联系。花粉高尔基囊泡与牛脑微管的体外结合能力,受１０ ｍ ｍ ｏｌ／ＬＡＴＰ和０．５ ｍ ｏｌ／ＬＫＣｌ的影响,但不受５ ｍ ｍ ｏｌ／Ｌ ＡＭＰ－ＰＮＰ的影响,说明两者结合可能是通过高尔基囊泡表面与ＡＴＰ有关的某种外周膜蛋白来完成的。     

几种濒危植物及其近缘类群总DNA的提取与鉴定

用低ｐＨ 介质,高盐沉淀蛋白质方法成功地从银杉（Ｃａｔｈａｙａ ａｒｇｙｒｏｐｈｙｌｌａ Ｃｈｕｎ ｅｔＫｕａｎｇ）、矮牡丹（Ｐａｅｏｎｉａ ｓｕｆｆｒｕｔｉｃｏｓａ ｖａｒ． ｓｐｏｎｔａｎｅａ）、南川升麻（Ｃｉｍ ｉｃｉｆｕｇａ ｎａｎｃｈｕａｎｅｎｓｉｓＨｓｉａｏ）、裂叶沙参（Ａｄｅｎｏｐｈｏｒａ ｌｏｂｏｐｈｙｌｌａ）的同属种泡沙参（Ａ． ｐｏｔａｎｉｎｉｉ）等植物中提取和部分纯化了细胞总ＤＮＡ,并对其产率、质量和纯度作了鉴定。此方法的关键是用了一个低ｐＨ提取介质,它能有效防止组织破碎及沉淀大量材料时的电离化作用及酚化合物的进一步氧化。所得ＤＮＡ 不需经氯化铯梯度离心或柱层析,直接可用于限制性片断长度多态性（ＲＦＬＰ）及随机扩增的ＤＮＡ多态性（ＲＡＰＤ）等分子水平的遗传标记。为检测濒危植物的遗传多样性提供了一套迅速、简便和可靠的技术方案     

大蒜中期染色体内的核糖核蛋白物质

研究了大蒜（Ａｌｌｉｕｍ ｓａｔｉｖｕｍ Ｌ．）中期染色体的超微结构和ＲＮＰ物质。常规染色表明,大部分染色体内部有低电子密度区,有的染色体中低电子密度区域较大而似孔洞。银染结果也证明了有大小不等的孔洞存在。Ｂｅｒｎｈａｒｄ 染色显示,在染色体周边和染色体内部都有ＲＮＰ分布。用ＮａＯＨ 处理证明了Ｂｅｒｎｈａｒｄ 染色法所显示的深染区确实含有ＲＮＡ。ＲＮＰ量的多少与ＥＤＴＡ 的分化时间呈负相关