黑河上游灌丛建群种中国沙棘自由授粉子代父本分析和花粉流

利用SSR分子标记对中国沙棘（Hippophae rhamnoides ssp. sinensis Rousi）自由授粉的种子进行父本分析,研究其子代的父本来源和花粉散布模式。结果显示：在80%的置信水平上,193个子代中有104个个体可以确定花粉来源;在20个确定的父本中,16个为中国沙棘,4个为肋果沙棘（H.neurocarpa S.W.Liu et T.N.He）。传粉格局分析结果显示,中国沙棘有效花粉散布范围为3~71 m,平均距离为20.4 m,2株母本分别有87.23%和78.95%的有效花粉来自距其30 m的范围之内,研究结果表明中国沙棘自然种群以近距离传粉为主。此外,在黑河上游沙棘杂交带中,中国沙棘子代中的肋果沙棘花粉平均贡献率达到14.84%,表明中国沙棘与肋果沙棘存在较高的种间当代花粉流。     

黑胸大蠊（Periplaneta fuliginosa）病毒的分离及某些特性

从黑胸大蠊(Periplaneta fuliginosa)自然罹病的虫尸中分离得到一株非包涵体病毒。将病毒悬液均匀拌入无菌饲料并供食154～169日龄黑胸大蠊健康若虫时,能使其感染、发病,死亡率可达98％以上。在电子显微镜下观察时,病毒为球形二十面体颗粒,直径约23nm。病毒悬液具有典型核蛋白紫外吸收光谱。病毒用DNase和RNase处理并经吖啶橙染色、二苯胺和苔黑酚试验及甲醛反应证明:该病毒含有单链DNA。以上特性与细小病毒科的特征有点类似。     

土牛膝碱（abidenine）的分离及结构测定

从土牛膝(Achyraanthes bidentata Bl.)的根中分离到一种新的生物碱——土牛膝碱(ubidenine),通过波谱方法测定出土牛膝碱的化学结构为5,6—二氢化—2,3,10,11—四甲氧基—二苯并[a,g]—喹嗪盐(1)。     

海三棱藨草种群的物候与分布格局研究

海三棱藨草群落是生长在海岸带滩涂原生裸地上的原生植被,在上海地区分布面积达20多万亩。本项工作研究了上海市南汇县东海农场海堤外侧滩涂上海三棱藨草种群的物候和分布格局。根据滩涂高程以及海三棱藨草种群生长状况,可以划分成三个地带,即地带A,海三棱藨草与芦苇群落交错区;地带B,海三棱藨草种群生长最适的中潮位地带;地带C,梅三棱藨草种群定居地带。由于三个地带内,生境条件不同,海三棱藨草种群的物候有明显差异。从地带A至C,海三棱藨草种群的分布格局依次为随机分布、均匀分布和随机分布或群聚分布。其空间分布格局在随时间变化的同时也在空间上改变其位置。     

Induction of hepatic mitochondrial glycerophosphate dehydrogenase in rats by dehydroepiandrosterone.

Feeding the thermogenic steroid, 5-androsten-3 beta-ol-17-one (dehydroepiandrosterone, DHEA) in the diet of rats induced the synthesis of liver mitochondrial sn-glycerol 3-phosphate dehydrogenase to levels three to five times that of control rats within 7 days. The previously reported enhancement of liver cytosolic malic enzyme was confirmed. The induction of both enzymes was detectable at 0.01% DHEA in the diet, reached plateau stimulation at 0.1 to 0.2%, and was completely blocked by simultaneous treatment with actinomycin D. Feeding DHEA caused smaller, but statistically significant increases of liver cytosolic lactate, sn-glycerol 3-phosphate, and isocitrate (NADP(+)-linked) dehydrogenases but not of malate or glucose 6-phosphate dehydrogenases. The capability of DHEA to enhance mitochondrial glycerophosphate dehydrogenase and malic enzyme was influenced by the thyroid status of the rats; was smallest in thyroidectomized rats and highest in rats treated with triiodothyronine. 5-Androsten-3 beta,17 beta-diol and 5-androsten-3 beta-ol-7,17-dione were as effective as DHEA in enhancing the liver mitochondrial glycerophosphate dehydrogenase and malic enzyme. Administering compounds that induce the formation of cytochrome P450 enzymes enhanced liver malic enzyme activity but not that of mitochondrial glycerophosphate dehydrogenase. Arochlor 1254 and 3-methylcholanthrene also increased the response of malic enzyme to DHEA feeding.     

Lateral diffusion of membrane-spanning and glycosylphosphatidylinositol-linked proteins: toward establishing rules governing the lateral mobility of membrane proteins.

In the plasma membrane of animal cells, many membrane-spanning proteins exhibit lower lateral mobilities than glycosylphosphatidylinositol (GPI)-linked proteins. To determine if the GPI linkage was a major determinant of the high lateral mobility of these proteins, we measured the lateral diffusion of chimeric membrane proteins composed of normally transmembrane proteins that were converted to GPI-linked proteins, or GPI-linked proteins that were converted to membrane-spanning proteins. These studies indicate that GPI linkage contributes only marginally (approximately twofold) to the higher mobility of several GPI-linked proteins. The major determinant of the high mobility of these proteins resides instead in the extracellular domain. We propose that lack of interaction of the extracellular domain of this protein class with other cell surface components allows diffusion that is constrained only by the diffusion of the membrane anchor. In contrast, cell surface interactions of the ectodomain of membrane-spanning proteins exemplified by the vesicular stomatitis virus G glycoprotein reduces their lateral diffusion coefficients by nearly 10-fold with respect to many GPI-linked proteins.     

The glycosyl phosphatidylinositol anchor is critical for Ly-6A/E-mediated T cell activation.

Ly-6E, a glycosyl phosphatidylinositol (GPI)-anchored murine alloantigen that can activate T cells upon antibody cross-linking, has been converted into an integral membrane protein by gene fusion. This fusion product, designated Ly-6EDb, was characterized in transiently transfected COS cells and demonstrated to be an integral cell surface membrane protein. Furthermore, the fusion antigen can be expressed on the surface of the BW5147 class "E" mutant cell line, which only expresses integral membrane proteins but not GPI-anchored proteins. The capability of this fusion antigen to activate T cells was examined by gene transfer studies in D10G4.1, a type 2 T cell helper clones. When transfected into D10 cells, the GPI-anchored Ly-6E antigen, as well as the endogenous GPI-anchored Ly-6A antigen, can initiate T cell activation upon antibody cross-linking. In contrast, the transmembrane anchored Ly-6EDb antigen was unable to mediate T cell activation. Our results demonstrate that the GPI-anchor is critical to Ly-6A/E-mediated T cell activation.     

Refined crystal structures of "aged" and "non-aged" organophosphoryl conjugates of gamma-chymotrypsin

"Aged" organophosphoryl conjugates of serine hydrolases differ from the corresponding "non-aged" conjugates in their striking resistance to nucleophilic reactivation. The refined X-ray structures of "aged" and "non-aged" organophosphoryl conjugates of gamma-chymotrypsin were compared in order to understand the molecular basis for this resistance of "aged" conjugates. "Aged" and "non-aged" crystalline organophosphoryl-gamma-chymotrypsin conjugates were obtained by prolonged soaking of native gamma-chymotrypsin crystals with appropriate organophosphates. Thus, a representative "non-aged" conjugate, diethylphosphoryl-gamma-chymotrypsin, was obtained by soaking native crystals with paraoxon (diethyl-p-nitrophenyl phosphate), and a closely related "aged" conjugate, monoisopropyl-gamma-chymotrypsin, was obtained by soaking with diisopropylphosphorofluoridate. In both crystalline conjugates, the refined structures clearly reveal a high occupancy of the active site by the appropriate organophosphoryl moiety within covalent bonding distance of Ser195 O gamma. Whereas in the "non-aged" conjugate both ethyl groups can be visualized clearly, in the putative "aged" conjugate, as expected, only one isopropyl group is present. There is virtually no difference between the "aged" and "non-aged" conjugates either with respect to the conformation of the polypeptide backbone as a whole or with respect to the positioning of the side-chains within the active site. In the "aged" conjugate, however, close proximity (2.6 A) of the negatively charged phosphate oxygen atom of the dealkylated organophosphoryl group to His57 N epsilon 2 indicates the presence of a salt bridge between these two moieties. In contrast, in the "non-aged" conjugate the DEP moiety retains its two alkyl groups; thus, lacking a negative oxygen atom, it does not enter into such a charge-charge interaction and its nearest oxygen atom is 3.6 A away from His57 N epsilon 2. It is suggested that steric constraints imposed by the salt bridge in the "aged" conjugate lie at the basis of its resistance to reactivation.