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111.
利用人粒细胞集落刺激因子(hG-CSF)cDNA3′端非翻译区(3′-UTR)中存在的DraⅠ酶切位点,通过部分酶切与完全酶切,删除3′-UTR不同长度,构建了四种hG-CSFcDNA瞬时重组表达质粒。转染COS-7细胞后,生物活性测定结果提示,hG-CSFcDNA3′-UTR对其表达起负调控作用,其关键性序列位于紧接终止密码子TGA下游的65bp范围内,3′-UTR对hG-CSFcDNA表达的影响与转录水平的差别有一定关系。 相似文献
112.
汉防己甲素(汉甲)及克矽平(Polyvinylpyridine-N-Oxide,PVNO)是目前较为有效的抑制矽肺纤维化的药物。本文研究了其对胶原mRNA水平的影响.斑点杂交实验表明大鼠接尘60天和120天后α1(Ⅰ)及α1(Ⅲ)mRNA水平明显上升,经汉甲或克矽平治疗1个月或3个月后,胶原mRNA水平明显下降。原位杂交结果表明胶原mR-NA银颗粒与细胞性结节和增厚的肺泡壁的成纤维细胞分布重合。汉甲或克矽平治疗后银颗粒数下降。提示汉甲及克矽平对矽肺进程中的胶原基因表达增强有抑制作用。 相似文献
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Hypervariable region IV of Salmonella gene fliCd encodes a dominant surface epitope and a stabilizing factor for functional flagella. 总被引:2,自引:1,他引:1 下载免费PDF全文
To identify the major antigenic determinant of native Salmonella flagella of antigenic type d, we constructed a series of mutated fliCd genes with deletions and amino acid alterations in hypervariable region IV and in region of putative epitopes as suggested by epitope mapping with synthetic octameric peptides (T.M. Joys and F. Schödel, Infect. Immun. 59:3330-3332, 1991). The expressed product of most of the mutant genes, with deletions of up to 92 amino acids in region IV, assembled into functional flagella and conferred motility on flagellin-deficient hosts. Serological analysis of these flagella with different anti-d antibodies revealed that the peptide sequence centered at amino acids 229 to 230 of flagellin was a dominant B-cell epitope at the surface of d flagella, because replacement of these two amino acids alone or together with their flanking sequence by a tripeptide specified by a linker sequence eliminated most reactivity with antisera against wild-type d flagella as tested by enzyme-linked immunosorbent assay or by Western immunoblot. Functional analysis of the mutated flagellin genes with or without an insert suggested that amino acids 180 to 214 in the 5' part of hypervariable region IV (residues 181 to 307 of the total of 505) is important to the function of flagella. The hybrid proteins formed by insertion of peptide sequence pre-S1 12-47 of hepatitis B virus surface antigen into the deleted flagellins assembled into functional flagella, and antibody to the pre-S1 sequence was detected after immunization of mice with the hybrid protein. This suggests that such mutant flagellins containing heterologous epitopes have potential as vaccines. 相似文献
116.
R. R. Sakai P. F. He X. D. Yang L. Y. Ma Y. F. Guo J. J. Reilly C. N. Moga S. J. Fluharty 《Journal of neurochemistry》1994,62(5):2053-2056
Abstract: Antisense Oligonucleotides were developed to study the expression and function of angiotensin type 1 (AT1) receptors in cultured cells and brain. In both liver epithelial WB and neuro-blastoma N1E-115 cells AT1 antisense oligomers substantially decreased AT1 receptor density, whereas angiotensin type 2 (AT2) receptors remained unchanged. Similarly, repeated intracerebroventricular injections of AT1 antisense oligomers in rats decreased AT1 receptor density in hypothalamic-thalamic-septal tissue, and AT2 receptors were unaffected. Intracerebroventricular antisense oligomers also attenuated drinking elicited by intra-cerebroventricular angiotensin II but not the cholinomimetic carbachol. Collectively, these results demonstrate that antisense Oligonucleotides attenuate angiotensin receptor expression and function in behaving animals. 相似文献
117.
Incubation of thylakoid membranes from spinach with low concentrations of mercuric chloride induces the loss of one of the iron-sulfur centers, FB, in Photosystem I (PS I) and inhibits the electron transfer from PS I to the soluble electron carrier, ferredoxin. Reconstitution of this damaged iron-sulfur center has been carried out by incubating treated thylakoid membranes with exogenous FeCl3 and Na2S in the presence of-mercaptoethanol under anaerobic conditions. Low temperature EPR measurements indicate that center FB is largely restored. Kinetic experiments show that the restored FB can be photoreduced from P700. However, these reconstituted thylakoid membranes are still incompetent in the photoreduction of ferredoxin and NADP+, even though ferredoxin binding to the modified membranes was not impaired, indicating additional changes in the structure of the PS I complex must have occurred. 相似文献
118.
Leaf Developmental Age Controls Expression of Genes Encoding Enzymes of Chlorophyll and Heme Biosynthesis in Pea (Pisum sativum L.) 总被引:7,自引:4,他引:3 下载免费PDF全文
The effects of leaf developmental age on the expression of three nuclear gene families in pea (Pisum sativum L.) coding for enzymes of chlorophyll and heme biosynthesis have been examined. The steady-state levels of mRNAs encoding aminolevulinic acid (ALA) dehydratase, porphobilinogen (PBG) deaminase, and NADPH:protochlorophyllide reductase were measured by RNA gel blot and quantitative slot-blot analyses in the foliar leaves of embryos that had imbibed for 12 to 18 h and leaves of developing seedlings grown either in total darkness or under continuous white light for up to 14 d after imbibition. Both ALA dehydratase and PBG deaminase mRNAs were detectable in embryonic leaves, whereas mRNA encoding the NADPH:protochlorophyllide reductase was not observed at this early developmental stage. All three gene products were found to increase to approximately the same extent in the primary leaves of pea seedlings during the first 6 to 8 d after imbibition (postgermination) regardless of whether the plants were grown in darkness or under continuous white-light illumination. In the leaves of dark-grown seedlings, the highest levels of message accumulation were observed at approximately 8 to 10 d postgermination, and, thereafter, a steady decline in mRNA levels was observed. In the leaves of light-grown seedlings, steady-state levels of mRNA encoding the three chlorophyll biosynthetic enzymes were inversely correlated with leaf age, with youngest, rapidly expanding leaves containing the highest message levels. A corresponding increase in the three enzyme protein levels was also found during the early stages of development in the light or darkness; however, maximal accumulation of protein was delayed relative to peak levels of mRNA accumulation. We also found that although protochlorophyllide was detectable in the leaves immediately after imbibition, the time course of accumulation of the phototransformable form of the molecule coincided with NADPH:protochlorophyllide reductase expression. In studies in which dark-grown seedlings of various ages were subsequently transferred to light for 24 and 48 h, the effect of light on changes in steady-state mRNA levels was found to be more pronounced at later developmental stages. These results suggest that the expression of these three genes and likely those genes encoding other chlorophyll biosynthetic pathway enzymes are under the control of a common regulatory mechanism. Furthermore, it appears that not light, but rather as yet unidentified endogenous factors, are the primary regulatory factors controlling gene expression early in leaf development. 相似文献
119.
本文用N ̄(15)标记水稻和绿肥研究了稻田土壤-作物-家畜系统中氮的循环。N ̄(15)标记稻草喂羊,羊体回收饲料稻草N31.16%,羊粪28.26%,羊尿5.72%,总回收65.14%,损失34.86%。将羊粪尿单施,稻谷回收饲料稻草N3.19%,水稻全株回收4.82%,土壤残留19.00%,损失10.14%。故羊体、水稻及土壤残留共回收饲料稻草N54.98%.将羊粪与尿素配施,则饲料稻草N的总回收率为55.88%。N ̄(15)标记绿肥喂猪;猪体回收饲料绿肥N23.51%.猪粪23.85%,猪尿28.76%,总回收率76.12%,损失率23.88%。将猪粪、尿还田,稻谷回收饲料绿肥N6.69%,水稻全株回收10.05%,土壤残留19.17%,故猪体、水稻和土壤残留共回收饲料绿肥N52.73%,将猪粪与尿素配施,则饲料绿肥N的总回收率为52.75%。 相似文献
120.