Factor interactions with the simian virus 40 early pre-mRNA influence branch site selection and alternative splicing.

To study the interaction of splicing factors with the simian virus 40 early-region pre-RNA, which can be alternatively spliced to produce large T and small t mRNAs, we used an in vitro RNase protection assay that defines the 5' boundaries of factor-RNA interactions. Protection products reflecting factor interactions with the large T and small t 5' splice sites and with the multiple lariat branch site region were characterized. All protection products were detected very early in the splicing reaction, before the appearance of spliced RNAs. However, protection of the large T 5' splice site was detected well before small t 5' splice site and branch site protection products, which appeared simultaneously. Oligonucleotide-targeted degradation of small nuclear RNAs (snRNAs) revealed that protection of the branch site region, which occurred at multiple sites, required intact U2 snRNA and was enhanced by U1 snRNA, while protection of the large T and small t 5' splice sites required both U1 and U2 snRNAs. Analysis of several pre-RNAs containing mutations in the branch site region suggests that factor interactions involving the multiple copies of the branch site consensus determine the selection of branch points, which is an important factor in the selection of alternative splicing pathways.     

区别人小细胞肺癌和非小细胞肺癌的LSC系列单克隆抗体(简报)

人小细胞肺癌的发病率虽不及非小细胞肺癌,但其五年生存率却相对低得多,这两种细胞类型不仅在病理类型上表现不同,在许多其它性质上也表现不同。小细胞肺癌是一种异质性疾病,它由几种形态不同的瘤细胞组成,包括非小细胞肺癌在内;它易早期转移,能在肝、脑和骨髓中繁殖,具有L-Dopa胱羧酶,神经原特异的烯醇化酶(enolase),能合成神经递质和多肽激素蛙皮肽等特性。目前已有关于小细胞肺癌的单克隆抗体的报道,我们采用美国N I H建立的小细胞肺癌细胞株SH-77作免疫原,目前尚未见有关抗该细胞株的单克隆抗体的报道,现将我们制备的三个单抗体及其初步特异性鉴定结果简报如下     

雌核发育银鲫的受精生物学研究——天然雌核发育银鲫繁殖方式的讨论

本文研究了同源雌核发育银鲫精子在4种类型的雌核发育银鲫卵中的发育特征。初步揭示了天然雌核发育银鲫根据精子的来源不同而分别具有二种不同的繁殖方式,对其在维持雌核发育银鲫种群生存,促使克隆分化等方面的独特的生物学意义进行了讨论。     

人α1/158Ⅴ型(α1c型)干扰素基因在大肠杆菌中的表达及其产物的初步纯化

采用DNA聚合酶链反应(PCR)技术,将本实验室从中国人胎肝细胞染色体DNA中发现和分离的IFN-α1/158V基因的原始克隆,改造成适于进行非融合蛋白原核表达的结构形式,并在大肠杆菌中获得高效表达。测得重组IFN-α1/158V的抗病毒活性为1.9×10~7单位/升菌液。随后又采用以单克隆抗体亲和层析为主的纯化流程对表达产物进行初步纯化,获得了在SDS-聚丙烯酰胺凝胶电泳上呈现单一条带的纯化产物。     

Immunocytochemistry of ion transport mediators in the genital tract of female rodents

With immunocytochemistry, we have determined distribution of sodium, potassium-adenosine triphosphatase (Na+, K+-ATPase) and of three isoenzymes of carbonic anhydrase (CA) and have shown absence of the chloride channel, Band 3 protein, in the genital tract of female rodents. Staining for Na+,K+-ATPase was strongest in the ampullary oviduct and uterine glands in the mouse. In the mouse and rat ovary, immunostaining evidenced CA I, II, and III in theca interna cells where the enzyme could affect the pH of follicular fluid. The zona pellucida of the ovary and cytoplasmic foci in follicular granulosa cells stained for content of only CA I in mouse ovary, suggesting synthesis of a zona pellucida component by granulosa cells. CA II in mouse oviductal epithelium increased from the negative infundibulum to the variably positive ampulla and isthmus to the uniformly positive interstitial segment. The content of CA III varied inversely to that of CA II. The prevalence of CA II-positive cells apparently corresponded with that of nonciliated cells, whereas abundance of CA III-positive cells concurred with that of ciliated cells in regions of the mouse oviduct. The rat oviduct lacked CA II but, like that of the mouse, showed CA III in the proximal region. The staining for CA II in surface epithelium exceeded the reactivity in glandular epithelium in the mouse uterus, except during estrus. In contrast, rat uterus evidenced CA II in glandular but not surface epithelium. These results testify to possible significance of various ion transport mechanisms for biologic activities of diverse cells in the female genital tract.     

Identification of a reversible inhibitor of plasminogen activators in blood plasma

Inhibition of tissue-type plasminogen activator (t-PA) by pooled plasma could be ascribed for only 60% to the endothelial cell type PA inhibitor. The residual inhibition is ascribed to a so-far undescribed plasma component present at 0.2 nmol/l. This component shows reversible binding to t-PA with an apparent K_i of 10 pmol/l (does not hinder t-PA binding to fibrin); also reacts with urokinase, but not with DIP-t-PA; is stable at 37°C and does not occur in media of endothelial cells, hepatocytes and fibroblasts. This PA binding component in plasma adds to the regulation of plasminogen activator activities.

Fibrinolysis Tissue-type plasminogen activator Urokinase Blood plasma Endothelial cell type plasminogen activator inhibitor Protease inhibitor