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71.
The mitochondrial genome of Aspergillus nidulans contains several group-I introns. Each one has been assayed for its ability to self-splice in vitro in the absence of proteins.
The intron from the apocytochrome b gene is unusual among subgroup IB4 introns in being able to self-splice, unlike a similar
intron from Saccharomyces cerevisiae. The first intron in the cytochrome oxidase subunit-1 gene self-splices but only correctly completes the first step of splicing;
cryptic 3′ splice-sites are recognized instead and these are also used at a low frequency in vivo. The highly homologous intron
from Podospora anserina completes both steps in vitro. The remaining introns do not self-splice. The correlation between subgroup category, the likely
presence of specific tertiary interactions, and self-splicing activity is discussed.
Received: 16 May / 25 August 1997 相似文献
72.
目的评价背根神经节(DRG)P2Y2受体mRNA的表达在大鼠慢性神经病理性痛中的作用。方法SPF级大鼠24只,体重150~200g,雌雄不拘,随机分为2组:假手术组(S组)和慢性神经痛组(N组),每组12只。N组结扎左侧坐骨神经建立大鼠慢性压迫性损伤(CCI)模型,S组只暴露,不结扎左侧坐骨神经。2组分别于CCI前1d、CCI后1、4、7、10、14 d进行行为学观察,测定大鼠双后肢热痛阈和机械痛阈,并分别于CCI后7、14 d各取6只大鼠断颈处死,取双侧L(4-6)背根神经节,RT-PCR法测定P2Y2受体mRNA的表达。结果两组CCI后4 d热痛阈、机械痛阈明显降低(P〈0.05),持续至CCI后14 d;N组左侧DRG P2Y2受体mRNA表达较右侧明显下调,CCI后14 d较CCI后7 d下调(P〈0.05);与S组右侧比较,N组DRG P2Y2受体mRNA表达差异无统计学意义(P〉0.05)。结论背根神经节P2Y2受体mRNA的表达下调参与了大鼠慢性神经病理性痛的形成。 相似文献
73.
为了观察糖皮质激素对哮喘患者白细胞介素(IL)-5mRNA表达与嗜酸性粒细胞激活作用的影响,本研究用逆转录(RT)-聚合酶链反应(PCR)法半定量分析了哮喘患者用糖皮质激素治疗前后外周血单个核细胞(PBMC)中IL-5mRNA表达水平的变化,检测了血清嗜酸细胞阳离子蛋白(ECP)浓度、一秒钟用力呼气容积(FEV1)下降20%时的乙酰甲胆碱(MCH)激发浓度(MCH-PC20值)和基础FEV1占用力肺活量比值(FEV1%)等指标。结果发现,糖皮质激素不仅能改善哮喘患者的气道高反应性和通气功能,而且还可抑制PBMC中IL-5mRNA的表达和降低血清ECP浓度(P<0.05);血清ECP浓度下降幅度或MCH-PC20值改善幅度与IL-5mRNA表达水平下降幅度之间均呈显著正相关(r分别为0.5426和0.4857,P值<0.05)。提示糖皮质激素可能是通过抑制IL-5基因的转录,从而抑制后者对嗜酸性粒细胞的活化,而发挥其抗气道炎症反应和降低气道高反应性的作用。 相似文献
74.
75.
A cDNA for the estradiol-regulated 24K protein: Control of mRNA levels in MCF-7 cells 总被引:1,自引:0,他引:1
Ines Moretti-Rojas Suzanne A. W. Fuqua Robert A. Montgomery III William L. McGuire 《Breast cancer research and treatment》1988,11(2):155-163
We have previously demonstrated an estradiol-regulated 24 kDa (24K) protein in human breast cancer tissue culture cells and human tumor biopsies. The presence of 24K correlates well with the presence of steroid hormone receptors. In order to further study the hormonal regulation of the 24K protein and gene, we have isolated cDNA clones corresponding to the 24K mRNA.Poly(A)+ RNA isolated from the MCF-7 human breast cancer cell line was translated in a cell-free translation system containing [35S]-methionine. The translation products were immunoprecipitated with a 24K monoclonal antibody, and thein vitro synthesis of 24K protein was confirmed by sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis. The same poly(A)+ RNA was used to construct an oligo(dT)-primed cDNA library in thegt11 expression vector system. The library was screened with a highly specific polyclonal antibody raised against 24K protein purified by immunoaffinity chromatography. Four recombinant clones reacting with the antibody by virtue of antigen expression were isolated and three were used in hybridization-selected translation. Three clones were able to hybridize specifically to a messenger RNA (mRNA) that yielded a Mr 24,000 protein when translatedin vitro and analyzed by SDS/polyacrylamide gel electrophoresis. This protein was also immunoprecipitable by the 24K monoclonal antibody. MCF-7 mRNA size fractionated by formaldehyde-agarose gel electrophoresis was transferred to nitrocellulose paper and hybridized to a nick-translated 24K cDNA clone. A single band of hybridization corresponding to a mRNA size of approximately 0.9–1.0 kilobase (kb) was observed. Using this same technique, 24K cDNA was hybridized to mRNA extracted from MCF-7 cells that had been treated for varying periods with either estradiol, nafoxidine, or tamoxifen. The 24K mRNA was elevated by the addition of estradiol, and clearly diminished by nafoxidine and tamoxifen.These results demonstrate that we have isolated cDNA clones for the study of the hormonal regulation of the 24K gene in breast cancer cells, and have shown that the mRNA is regulated by estradiol. 相似文献
76.
目的:检测lnc-CCDC33-1:1在甲状腺乳头状癌(PTC)中的表达,并分析其临床意义。方法:选取2021年11月至2022年3月杭州市萧山区第一人民医院收治的120例PTC患者,收集120例PTC组织及30例癌旁正常甲状腺组织。采用qRT-PCR检测lnc-CCDC33-1:1在PTC组织及癌旁组织中的表达。分析本地队列和TCGA队列中lnc-CCDC33-1:1表达水平与PTC患者临床病理因素的相关性。采用受试者工作特征(ROC)曲线评价lnc-CCDC33-1:1对PTC的诊断价值。结果:与癌旁正常甲状腺组织比,lnc-CCDC33-1:1在PTC组织中表达明显升高(P <0.001)。ROC曲线显示曲线下面积为0.803(95%CI =0.736~0.869,P <0.001)。本地队列显示lnc-CCDC33-1:1 表达与PTC肿瘤大小(P =0.048)、腺外侵犯(P =0.019)、T分期(P =0.011)和淋巴结转移(P =0.009)相关,TCGA组数据显示lnc-CCDC33-1:1表达水平与PTC腺外侵犯(P =0.036)和淋巴结转移(P <0.001)相关。结论:lnc-CCDC33-1:1在PTC中表达异常升高,与PTC高危特征相关,可能是潜在的诊断标志物和治疗靶点。 相似文献
77.
目的为了了解丙型肝炎病毒载量在两性间的流行状况.方法荧光定量PCR用于HCV RNA定量检测.结果男性患者阳性率为20.27%(30/148),病毒拷贝对数值为4.18±1.04;而女性分别为29.29%(29/99),4.28±1.07.结论男女HCV阳性病人的阳性率(P=0.103,χ2=2.656)和病毒量(P=0.487 ,t=0.699)在男女两性间无统计学差异. 相似文献
78.
Immunoglobulin mimicry by Hepatitis C Virus envelope protein E2 总被引:4,自引:0,他引:4
Hu YW Rocheleau L Larke B Chui L Lee B Ma M Liu S Omlin T Pelchat M Brown EG 《Virology》2005,332(2):538-549
Hepatitis C virus (HCV) establishes persistent infection in the majority of infected individuals. The currently accepted hypothesis of immune evasion by antigenic variation in hypervariable region 1 (HVR1) of glycoprotein E2 does not however, explain the lack of subsequent immune recognition. Here, we show that the N-terminal region of E2 is antigenically and structurally similar to human immunoglobulin (Ig) variable domains. E2 is recognized by anti-human IgG antibodies and also possesses common amino acid (aa) sequence features of the conserved v-gene framework regions of human Ig light chains in particular but also heavy chains and T cell receptors. Using a position specific scoring system, the degree of similarity of HVR1 to Ig types correlated with immune escape and persistence in humans and experimentally infected chimpanzees. We propose a unique role for threshold levels of Ig molecular mimicry in HCV biology that not only advances our concept of viral immune escape and persistent infection but also provides insight into host-dependent disease patterns. 相似文献
79.
Early erythroid precursors were studied in human bone marrow smears to provide more information on small proerythroblasts--"microproerythroblasts"--using a silver reaction to demonstrate silver stained nucleolar organizer regions (AgNORs) and light microscopic densitometry of large irregularly shaped nucleoli and cytoplasm stained for RNA. No significant differences were found for the density of such nucleoli and basophilic cytoplasm between characteristic large proerythroblasts with a nuclear diameter larger that 9 microm (K2 and K1 erythroblasts) and small proerythroblasts--"microproerythroblasts" representing a subpopulation of K1/2 erythroblasts (early basophilic erythroblasts), which are characterized by a smaller nuclear diameter. In addition, large irregularly shaped nucleoli of "microproerythroblasts" possessed numerous silver stained particles representing AgNORs similar to those of large proerythroblasts. The number of AgNORs in "microproerythroblasts" was slightly, but significantly, smaller than that in large characteristic proerythroblasts. 相似文献
80.
《Immunity》2020,52(6):1075-1087.e8
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