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51.
Structure and synthesis of histopine, a histidine derivative produced by crown gall tumors 总被引:2,自引:0,他引:2
Histopine, an unusual amino acid derivative of histidine isolated from crown gall tumors of sunflowers (Helianthus annus) inoculated with Agrobacterium tumefaciens strain B6, was previously assigned the gross structure N-(1-carboxyethyl) histidine (2). A diastereomeric mixture containing histopine (2a and 2b) was readily prepared by reductive alkylation of (S)-histidine (1) with pyruvic acid and sodium cyanoborohydride. The individual diastereomers were prepared by reaction of (S)-histidine with (R)- and (S)-2-bromopropionic acid. (R)-N-(1-Carboxyethyl)-(S)-histidine (2a) supports the growth of A. tumefaciens whereas (S)-N-(1-carboxyethyl)-(S)-histidine (2b) is inactive. Therefore, we assign structure 2a to histopine. 相似文献
52.
Sprague-Dawley albino rats or Long-Evans pigmented rats were exposed during the dark phase of the daily light:dark cycle to various intensities of a sunlight-stimulating white fluorescent light (0.022, 0.044, 0.110, 0.220, 0.440 or 2.200 μW/cm2) for 30 min; pineal glands and trunk blood samples were then collected and assayed for melatonin by radioimmunoassay. Albino rats exposed to irradiances of 0.110 μW/cm2 or less had pineal melatonin levels that were not significantly different from those of unexposed animals; higher irradiances significantly (P < 0.001) reduced melatonin levels. In contrast, as little as 0.022 μW/cm2 significantly (P < 0.02) reduced pineal and serum melatonin levels in the pigmented rats. These results suggest that something other than the simple presence or absence of eye pigmentation is the critical factor in determining the sensitivity of the rat's pineal to retinal-mediated photic suppression of melatonin synthesis. 相似文献
53.
新城疫病毒单克隆抗体的特性及应用 总被引:2,自引:0,他引:2
建立了8个分泌抗新城疫病毒(NDV)特异性单克隆抗体(McAb)的杂交瘤细胞株,根据它们的免疫生物学特性可以分为三种类型:(1)具有FA和ELISA特性(FN1、FN4、FN29、FN30、FN35、FNl22);(2)具有FA、ELISA和HI特性(FN7);(3)具有ELISA、HI特性和中和能力(FN106),根据FN30和FN106的ELISA试验,可将11个NDV毒株分为二种不同的抗原群,应用FN4-FITC,FN7-FITC和FN29-HRP试剂,对人工感染NDV和野外送检病例检测结果表明,单抗试剂的DFA阳性率(92.3%)高于病毒分离阳性率(87.2%),两种方法的符合率89.7%,这些单抗试剂用于临床诊断敏感性和特异性高,且方法快速、简便。 相似文献
54.
大尺蠖核多角体病毒DNA的限制性消化和物理图谱 总被引:4,自引:0,他引:4
用5种限制性核酸内切酶消化大尺蠖核多角体病毒(BsNPV)基因组DNA,所得片段数分别是:BamH Ⅰ,9;Bgl Ⅱ,7;Xho Ⅰ,10;HindⅢ 13;EcoR Ⅰ,12,从各个片段的累加测出BsNPV基因组的平均大小约为91,75kb;分子量约为59.60×10~6d。在单酶消化的基础上,用BamH Ⅰ/Bgl Ⅱ双酶消化得到16个片段(即9+7);大小为91,27kb,用、Bgl Ⅱ/Xho Ⅰ双酶消化产生7+10=17个片段,大小为90.04kb,由此组建了这三个酶在BsNPV基因组上的物理图谱。 相似文献
55.
用改进的LiCl沉淀法和寡聚(dT)-纤维素亲和层析法由猪垂体制得总mRNA。在兔网织红细胞无细胞翻译体系中进行体外翻译的结果表明,制得的总mRNA具有一定的翻译活力。翻译产物与兔抗猪生长激素抗血清发生免疫沉淀,沉淀物占总翻译产物的10%左右。SDS聚丙烯酰胺凝胶电泳的结果表明翻译产物有一条很深的带,分子量约为24,000道尔顿,与猪前生长激素的分子量相近。以制备的mRNA为模板反转录合成了双链cDNA。第一链的合成产率为10—35%,第二链的合成产率为84—115%。cDNA的平均分子长度为825bp。 相似文献
56.
Alston-Mills Brenda Li Qi Chang Ottinger Mary Ann 《In vitro cellular & developmental biology. Plant》1989,25(10):934-938
Summary Production of antibodies against peptides or poorly antigenic proteins by conventional methods often requires either large
quantities of the native immunogen or some chemical modification to increase their antigenicity. In this study an in vivo
and in vitro immunization protocol has been used to generate monoclonal antibodies against the decapeptide luteinizing hormone-releasing
hormone (LHRH). Two injections of 100 μg of avian LHRH-I into BALB/c mice were given 7 d apart. Dissociated splenocytes were
collected under sterile conditions. They were incubated with 100 μg of the immunogen in 75-cm2 tissue culture flasks in thymocyte-conditioned media. After 5 to 8 d exposure to the antigen, splenocytes were fused with
SP2/O myeloma cells by polyethylene glycol. The cells were plated into 24 wells and then incubated in hypoxanthine aminopterin
and thymidine selective media. After 14 d an initial screening was done by enzyme immunoassay. The positive wells (6/24) were
expanded into 96-well plates and rescreened. Selected lines were cloned out 3 times by limiting dilution and the most positive
expanded for ascites production. The antibody was affinity purified in a protein A column. The antibody cross-reacted with
LHRH-I and II but preferentially to LHRH-I, as shown by competitive assay. A hypothalamic extract from a mature chick showed
a higher response than preparations from whole brain explants of 1- to 3-d posthatched chicks, mature quail, and mature mouse.
This work was funded by the Maryland Agricultural Experiment Station artical no. A4975, contribution no. 8019. 相似文献
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60.
在现代社会中,人类的经济建设以与自然过程相竞争的规模进行着,所造成的生态影响不仅表现在地区生态系统的结构和功能上,也表现在生物圈中,而且还从地球化学循环中显示出来。这种情况,使得现代社会的经济管理,必然由传统的经济管理逐步转变成生态经济管理。 相似文献