Determinants of growth-promoting activity reside in the A-domain of insulin-like growth factor I

A two-chain, disulfide linked, insulin-like compound embodying the A-domain of insulin-like growth factor I (IGF-I) and the B-chain of insulin has been synthesized and characterized with respect to insulin-like biological activity and growth-promoting potency. The compound displays a potency of ca. 41% relative to insulin in assays for insulin-like activity (e.g., lipogenesis) but significantly higher activity than insulin, ca. 730% relative to insulin, in growth factor assays (e.g., thymidine incorporation). The compound is, however, a less potent growth factor than IGF-I itself, ca. 26.5% relative to IGF-I, and is not recognized by IGF carrier proteins. We conclude that structural features contained in the A-domain of IGF-I are primarily responsible for the growth-promoting ability displayed by IGF-I, while features in the B-domain are responsible for recognition by IGF carrier proteins.     

中国的脊棱齿象属(Stegolophodon)化石

剑齿象属 Stegodon 起源于脊棱齿象属 Stegolophodon,两者都是亚洲大陆晚新生代的特有动物,本文讨论两属中一些种的性质和分类位置问题,并记述了药铺脊棱齿象 Stegolophodon officinalis 的新材料.     

Bioconversion of organosilicon compounds by horse liver alcohol dehydrogenase: the role of the silicon atom in enzymatic reactions

Summary Bioconversion of three organosilicon compounds of different chain length between the silicon atom and the hydroxyl group (Me₃Si(CH₂)_nOH, n = 1–3) by horse liver alcohol dehydrogenase (HLADH, EC 1.1.1.1.) was studied. Furthermore, the effect of the silicon atom on the HLADH-catalysed reaction was examined in comparison with the corresponding carbon compounds. HLADH could catalyse the dehydrogenation of trimethylsilyeethanol (n = 2) and trimethylsilylpropanol (n = 3). Trimethylsilylethanol was a better substrate than both its carbon analogue, 3,3-dimethylbutanol, and ethanol. The improved activity of HLADH on trimethylsilylethanol could be accounted for by a higher affinity toward HLADH and a lower activation energy of the reaction by HLADH than those of the carbon counterpart. These are derived from physical properties of the silicon atom, that is, the lower electronegativity and the bigger radius than those of the carbon atom. In contrast, HLADH showed no activity on trimethylsilylmethanol (n = 1), whereas it catalysed the dehydrogenation of the carbon analogue, 2,2-dimethylpropanol, fairly well. The reason for the inactivity of HLADH in the case of trimethylsilylmethanol based on the electric effect of the silicon atom is also discussed. Offsprint requests to: A. Tanaka     

生物复苏——大绝灭后生物演化历史的第一幕

生命史是一部生物界短期,快速剧变与长期,慢速稳定相互交替的历史。大绝灭（即集群绝灭）事件反映了全球环境的大突变,点断了地质历史中的生命记录及其发展历程,预示着生物界的演化出现了最有意义的飞跃,近年来尝试研究大绝灭后全球生物界的残存－复苏及其基本型式,并探索复苏的控制因素,标志着地质科学中一个重心的转移（即从大绝灭转向其后的生物残存与复苏的研究）。生物复苏揭示了大绝灭后生物演化历史的第一幕,其研究的     

二核苷酸重复多态性的非同位素检测及其在基因诊断中的应用

本文报道了一种检测二核苷酸重复多态性的简便的非同位素法,利用重复序列两侧的特异引物进行ＰＣＲ扩增,产生的等位片段在薄层变性聚丙烯酰胺凝胶电泳上分离,再用灵敏的银染法显色。该方法不需要标记ＰＣＲ产物,简便、快速,分辨率可达１ｂｐ,并可用多对引物同时进行多重ＰＣＲ分析。用此方法对ＤＭＤ家系成员ｄｙｓｔｒｏｐｈｉｎ基因的５＇－脑型外显子止游区和３＇－非翻译区的两个（ＣＡ）。位点进行了扩增片段长度多态性分     

Distinctive effects of the carboxyl-terminal sequence of the insulin-like growth factor I receptor on its signaling functions.

We have shown previously that the extracellular sequences of the human insulin receptor (IR) and the insulin-like growth factor I receptor (IGFR) have an inhibitory effect on protein tyrosine kinase (PTK) activity and on the biological functions of their respective Gag-receptor fusion proteins. To study the role of IGFR carboxyl sequence in modulation of the Gag-IGFR PTK and biological activities, five mutants, CM1, CM2, CM3, CM4, and CM5, containing carboxyl deletions of 17, 27, 47, 67, and 88 amino acids (aa), respectively, were constructed from the parental virus UIGFR encoding the Gag-IGFR. Deletion of up to 27 aa had little effect on the cell-transforming and PTK activities of UIGFR. Deletions of 47 aa in CM3 abolished PTK and transforming activities. Surprisingly, a further deletion of 20 aa in CM4 beyond that in CM3 reactivated the kinase and transforming activities. CM5, containing a deletion of 20 aa beyond that in CM4, had only marginal transforming and PTK activities. We conclude that deletion of the carboxyl region of the Gag-IGFR inactivates, instead of activating as in the case with Gag-IR, its transforming activity and the amino acid sequence 1250 to 1310 is essential for PTK and transforming activities. Analysis of the ability of the full-length IGFR and its mutant receptors described above to associate with phosphatidylinositol 3 kinase indicated that the association required PTK activity and tyrosine phosphorylation of the receptors and correlated well with their transforming activities. The carboxyl 88 aa are not essential for the association.     

鼠兔核质杂交胚胎早期发育的研究

细胞核移植技术已被证明是研究发育中核质相互关系的非常重要的手段之一,电融合技术也是近十年发展起来的新型细胞融合技术。本实验运用这两项技术,进行了鼠、兔目间核质杂交实验,小鼠8-细胞核在激活的兔去核卵母细胞中,发生了染色体超前凝聚及核膨胀,融合卵移植到小鼠输卵管4.5天后,冲洗出,有5.4%的重构卵发育到囊胚期,通过染色体检查,囊胚细胞中均为小鼠染色体,其中一个囊胚为正常小鼠核型(2 n=40,XX)。通过本实验,我们认为:鼠兔远缘核质杂交胚胎的早期发育是可能的。     

Tyrosine phosphorylation of the herpes simplex virus type 1 regulatory protein ICP22 and a cellular protein which shares antigenic determinants with ICP22.

At least eight herpes simplex virus type 1 (HSV-1) and five HSV-2 proteins were tyrosine phosphorylated in infected cells. The first viral tyrosine phosphoprotein identified was the HSV-1 regulatory protein ICP22. Also, two novel phosphotyrosine proteins were bound by anti-ICP22 antibodies. H(R22) is a cellular protein, while the F(R10) protein is observed only in HSV-1-infected cells.     

江苏省海滩植被演替的研究

江苏省海滩植被可分为滨海盐土植被、盐沼植被及海滩沙生植被三个基本类型。本文论述了这些植被类型的演替规律。滨海盐土植被与盐沼植被的演替,外因于土壤盐分含量递减与有机质含量的递增;海滩沙生植被的演替,外因于土壤沙颗粒大小及其相应的土壤含水量的变化,所以海滩植被演替为外因动态演替。     

Expression of a gene encoding a rabbit sperm membrane protein in mammalian cells.

A general mammalian expression vector designated pSV2-EP was reconstructed by inserting an oligonucleotide fragment into pSV2-dhfr. This vector allowed insertion of cDNAs with EcoRI cohesive ends. The pSV2-EP contains a simian virus 40 (SV40) early promoter, origin for DNA replication, SV40 poly-A site, splicing site, an initiator ATG downstream from the promoter and an EcoRI site for the insertion of cDNA fragment screened from lambda gt11 expression libraries. A recombinant plasmid (pS-VRS-1) was constructed by inserting RSD-1, a cDNA encoding a rabbit sperm tail protein, into the EcoRI site of the pSV2-EP vector. Chinese hamster ovarian (CHO) dhfr-negative cells were cotransformed with pSV2-dhfr and pSVRS-1 by the calcium phosphate method. In selective culture medium without thymidine and hypoxanthine, several cell lines were obtained containing mRNA and DNA that hybridized with RSD-1. One of these transformed cell lines stained intensely with anti-rSMP-B antibodies, demonstrating that the RSD-1 was expressed in the transformed CHO cells.