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131.
最近的报道指出,某些病毒有诱导体外细胞凋亡的作用,借以限制病毒的扩散。为探讨HSV-2在体内诱导细胞凋亡的效果及其形态学特点,用 HSV-2 333株感染小鼠阴道,于感染后不同天数处死动物,取其阴道,固定于10%中性福尔马林,TUNEL末端标记染色显示凋亡的细胞,光镜下进行原位观察。结果显示:感染后的第1天粘膜上皮内即出现大量的凋亡细胞,第2天至11天凋亡细胞的数量及在上皮内的分布范围达最高水平。早期的凋亡细胞见于感染后所有标本,其核染色质形态及分布似正常细胞,但它被TUNEL标记染成棕黄色;晚期的凋亡细胞亦见于所有标本,其胞核缩小,染色质浓缩并在核周边集聚,核中心空化。载有凋亡细胞的上皮在阴道粘膜上分布很广,最广的可占全阴道上皮的2/3。同时可见HSV.2引起的上皮细胞坏死及疱疹形成,二者均由凋亡细胞包围。凋亡细胞不断地由上皮表面脱落至阴道,未见凋亡小体及吞噬现象。结果提示,HSV-2 333株阴道感染可同时诱导细胞坏死及凋亡,细胞凋亡可能在限制病毒产生子代及限制感染区域扩展起重要作用。 相似文献
132.
Ishizuka T Yoshida J Yamamoto Y Sumaoka J Tedeschi T Corradini R Sforza S Komiyama M 《Nucleic acids research》2008,36(5):1464-1471
Invasion of two PNA strands to double-stranded DNA is one of the most promising methods to recognize a predetermined site in double-stranded DNA (PNA = peptide nucleic acid). In order to facilitate this 'double-duplex invasion', a new type of PNA was prepared by using chiral PNA monomers in which a nucleobase was bound to the alpha-nitrogen of N-(2-aminoethyl)-d-lysine. These positively charged monomer units, introduced to defined positions in Nielsen's PNAs (poly[N-(2-aminoethyl)glycine] derivatives), promoted the invasion without impairing mismatch-recognizing activity. When pseudo-complementary nucleobases 2,6-diaminopurine and 2-thiouracil were bound to N-(2-aminoethyl)-d-lysine, the invasion successfully occurred even at highly G-C-rich regions [e.g. (G/C)7(A/T)3 and (G/C)8(A/T)2] which were otherwise hardly targeted. Thus, the scope of sequences available as the target site has been greatly expanded. In contrast with the promotion by the chiral PNA monomers derived from N-(2-aminoethyl)-d-lysine, their l-isomers hardly invaded, showing crucial importance of the d-chirality. The promotion of double-duplex invasion by the chiral (d) PNA monomer units was ascribed to both destabilization of PNA/PNA duplex and stabilization of PNA/DNA duplexes. 相似文献
133.
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135.
Yang Gu Jian Li Lei Zhang Jun Chen Lixia Niu Yunliu Yang Sheng Yang Weihong Jiang 《Journal of biotechnology》2009,143(4):284-287
Clostridium acetobutylicum ATCC 824 was metabolically engineered for improved xylose utilization. The gene talA, which encodes transaldolase from Escherichia coli K-12, was cloned and overexpressed in C. acetobutylicum ATCC 824. Compared with C. acetobutylicum ATCC 824 (824-WT), the transformant bearing the E. coli talA gene (824-TAL) showed improved ability on xylose utilization and solvents production using xylose as the sole carbon source. During the fermentation of xylose and glucose mixtures with three xylose/glucose ratios (approximately 1:2, 1:1 and 2:1), the rate of xylose consumption and final solvents titers of 824-TAL were all higher than those of 824-WT, despite glucose repression on xylose uptake still existing. These results suggest that the insufficiency of transaldolase in the pentose phosphate pathway (PPP) of C. acetobutylicum is one of the bottlenecks for xylose metabolism and therefore, overexpressing the gene encoding transaldolase is able to improve xylose utilization and solvent production. 相似文献
136.
Elevated plasma low-density lipoprotein (LDL) cholesterol is considered as a risk factor for atherosclerosis. Because the hepatic LDL receptor (LDLR) uptakes plasma lipoproteins and lowers plasma LDL cholesterol, the activation of LDLR is a promising drug target for atherosclerosis. In the present study, we identified the naturally occurring alkaloid piperine, as an inducer of LDLR gene expression by screening the effectors of human LDLR promoter. The treatment of HepG2 cells with piperine increased LDLR expression at mRNA and protein levels and stimulated LDL uptake. Subsequent luciferase reporter gene assays revealed that the mutation of sterol regulatory element-binding protein (SREBP)-binding element abolished the piperine-mediated induction of LDLR promoter activity. Further, piperine treatments increased mRNA levels of several SREBP targets and mature forms of SREBPs. However, the piperine-mediated induction of the mature forms of SREBPs was not observed in SRD–15 cells, which lack insulin-induced gene–1 (Insig–1) and Insig–2. Finally, the knockdown of SREBPs completely abolished the piperine-meditated induction of LDLR gene expression in HepG2 cells, indicating that piperine stimulates the proteolytic activation of SREBP and subsequent induction of LDLR expression and activity. 相似文献
137.
Jun Feng Weixia Gao Yanyan Gu Wei Zhang Mingfeng Cao Cunjiang Song Peng Zhang Min Sun Chao Yang Shufang Wang 《Applied microbiology and biotechnology》2014,98(14):6397-6407
Poly-γ-glutamic acid (γ-PGA) is an important biopolymer with greatly potential in industrial and medical applications. In the present study, we constructed a metabolically engineered glutamate-independent Bacillus amyloliquefaciens LL3 strain with considerable γ-PGA production, which was carried out by single, double, and triple markerless deletions of three degradation genes pgdS, ggt, and cwlO. The highest γ-PGA production (7.12 g/L) was obtained from the pgdS and cwlO double-deletion strain NK-pc, which was 93 % higher than that of wild-type LL3 strain (3.69 g/L). The triple-gene-deletion strain NK-pgc showed a 28 % decrease in γ-PGA production, leading to a yield of 2.69 g/L. Furthermore, the cell morphologies of the mutant strains were also characterized. The cell length of cwlO deletion strains NK-c and NK-pc was shorter than that of the wild-type strain, while the ggt deletion strains NK-g, NK-pg, NK-gc, and NK-pgc showed longer cell lengths. This is the first report concerning the markerless deletion of γ-PGA degradation genes to improve γ-PGA production in a glutamate-independent strain and the first observation that γ-glutamyltranspeptidase (encoded by ggt) could be involved in the inhibition of cell elongation. 相似文献
138.
鹿衔草化学成分的研究:羟基肾叶鹿蹄草甙的结构鉴定 总被引:9,自引:0,他引:9
从鹿衔草(Pyrola calliantha H.Andres)分离得到两个化合物。经光谱分析,确定其中1个化合物为新化合物,命名为羟基肾叶鹿蹄草甙(1, hydroxylrenifolin),另一化合物为儿茶素(3)。 相似文献
139.
初次卵裂时间是猪克隆胚胎发育潜能的重要标识 总被引:2,自引:0,他引:2
初次卵裂时间与哺乳动物胚胎发育潜能有关.比较了不同初次卵裂时间(20~24 h,早期;25~36 h,中期;37~48 h,晚期;20~48 h,对照)的猪孤雌(parthenogenetic,PA)、体细胞核移植(somatic cell nuclear transfer,SCNT)胚胎的囊胚发育率、扩张囊胚发育率和囊胚细胞数,评价其体外发育能力.发现早期卵裂的PA胚胎发育到第6天的囊胚发育率显著高于中期、晚期以及对照组(P < 0.05;54.0% vs. 19.6%,5.4%,18.7%).扩张囊胚发育率,早裂胚胎同样优于其他组.早期卵裂的SCNT胚胎发育到第6天的囊胚比率高于中期卵裂胚胎(32.2% vs. 23.5%),而晚期卵裂胚胎发育到囊胚的比率最低(6.3%).早期卵裂的SCNT胚胎发育到第6天的扩张囊胚比率显著高于其余各组 (P < 0.05;18.9% vs. 5.9%、3.1%、7.4%).囊胚细胞数在早期、中期、晚期三组之间表现出下降趋势.将早期卵裂的SCNT胚胎与未经挑选的对照组胚胎分别进行移植,观察其体内发育能力.移植早裂SCNT胚胎的受体在产仔数和克隆效率上均明显高于未经挑选胚胎的受体(4.7 vs. 2.1;3.9% vs. 0.9%),说明早裂胚胎着床后具有更强的发育能力.以上结果表明:初次卵裂时间可以作为猪克隆胚胎发育潜能的重要标识,选择早裂的胚胎进行移植,有助于提高克隆效率. 相似文献
140.