Sex-linked genes and linkage maps in amphibians

This paper reviews sex-linked genes and linkage maps in amphibians. It appears that there is no common ancestral or conserved sex-linkage group in amphibians, whereas an important proportion of other linkage groups has been conserved in amphibians. Comparisons of amphibian linkage maps with those of fishes and mammals reveal several syntenic associations apparently conserved over a very long period of vertebrate divergence.     

Cell-to-cell contact results in a selective translocation of maternal human immunodeficiency virus type 1 quasispecies across a trophoblastic barrier by both transcytosis and infection

Mother-to-child transmission can occur in utero, mainly intrapartum and postpartum in case of breastfeeding. In utero transmission is highly restricted and results in selection of viral variant from the mother to the child. We have developed an in vitro system that mimics the interaction between viruses, infected cells present in maternal blood, and the trophoblast, the first barrier protecting the fetus. Trophoblastic BeWo cells were grown as a tight polarized monolayer in a two-chamber system. Cell-free virions applied to the apical pole neither crossed the barrier nor productively infected BeWo cells. In contrast, apical contact with human immunodeficiency virus (HIV)-infected peripheral blood mononuclear cells (PBMCs) resulted in transcytosis of infectious virus across the trophoblastic monolayer and in productive infection correlating with the fusion of HIV-infected PBMCs with trophoblasts. We showed that viral variants are selected during these two steps and that in one case of in utero transmission, the predominant maternal viral variant characterized after transcytosis was phylogenetically indistinguishable from the predominant child's virus. Hence, the first steps of transmission of HIV-1 in utero appear to involve the interaction between HIV type 1-infected cells and the trophoblastic layer, resulting in the passage of infectious HIV by transcytosis and by fusion/infection, both leading to a selection of virus quasispecies.     

四川冕宁地区一万年来的植被与环境演变

依据彝海洼地钻孔高分辨率的孢粉时间序列,探讨了安宁河谷近１０Ｋａ来的古植被及古环境变迁。本区全新世大暖期以山毛榉科花粉连续的大量出现为标志,时间为８．８－２．６ＫＢＰ,前期温暖湿润,后期温热半湿,且冬季干旱化。气候被动明显存在３．５Ｋａ,１Ｋａ及０．２５Ｋａ的准周期。近３Ｋａ年来气候经历了两次大的干湿冷暖变化,可划分为四个气候期,基本为凉湿暖干的组合型式,降水量的变化与南极有可比性。     

日利用l基因工程培育成功耐高温植物

Nature Biotechnology 2000年18卷3期249页报道：日本九州大学的科学家们已培育成功一种可在高温下维持光合作用的转基因烟草(Science287,476～479,2000)。鉴于沙漠植物的叶绿体可在高温下减少三烯脂肪酸的合成,科学家们培育了含有来自拟南芥(Arabidopsis thaliana)的附加的叶绿体特异△-3去饱和酶(脱氢酶)基因的两个转基因烟草株系。互阻遏作用导致△-3去饱和酶基因在这些植株中的表达下降,以及与此伴随的三烯脂肪酸的相应减少。因此,这种转基因植株40℃高温下的光合作用活性可高于25℃下的活性(但40℃可极大地降低野生型植株的光合作用强度)。科学家们提示,利用内源基因可避免利－46用外源DNA进行基因操作时发生的有害效应。这个研究组的植物生理学家KohIba说：“此项研究给予我们的启迪是,利用基因操作技术可育成新的农作物或树木,以适应无可避免的全球性气候变化。例如可使寒冷地区的树木适应于高温环境”。汪开治     

应用基因工程技术生产IL-11和IL-12

目前武汉大学生命科学学院科研人员针对人体失血和免疫功能下降,应用基因工程技术生产出了人白细胞介素-11(即IL-11)和人白细胞介素-12(即IL-12)。 1 IL-11为人体自然产生的细胞生长因子,能增加血小板,提高凝血速度,防止伤口出血不止,在临床上用来治疗低血小板症,还能辅助治疗癌症,主要用于化疗。克隆于载体,通过大肠杆菌充分表达,经分离、纯化和精制,生产出质量很高的医用成药,故疗效很好。 2 IL-12这是目前在细胞素中发现对人体免疫活性细胞诱导和调节最强、范围最广的一种。其研制技术是将IL-12的两种不同来源的基因克隆于昆虫病毒载体,在昆虫细胞内表达,经分离纯化成工程蛋白,再制备成医药产品。它能诱导干扰素的产生,激活T细胞和NK细胞产生肿瘤坏死因子,能抗利什曼原虫、疟原虫、结核杆菌、血吸虫、肿瘤和病毒及其各相应的疾病,故美国基因研究所和惠施-阿耶斯特制药公司将它用于治疗艾滋病和肿瘤病,效果很好。秦春圃     

Senescence—like changes induced by expression of p21^Waf1／Cip1 in NIH3T3 cell line

P21^Waf1/Cip1 is a potent cyclin-dependent kinase inhibitor.As a downstream mediator of P53,P21^Waf1/Cip1 involves in cell cycle arrest,differentiation and apoptosis.Previous studies in human cells provided evidence for a link between P21^Waf1/Cip1 and cellular senescence.While in murine cells,the role of P21^Waf1/Cip1 is indefinite.We explored this issue using NIH3T3 cells with inducible P21^Waf1/Cip1 expression.Induc-tion of P21^Waf1/Cip1 triggered G1 growth arrest, and NIH3T3-p21 cells exhibited morphologic features,such as enlarged and flattened cellular shape,specific to the senescence phenotype.We also showed that P21^Waf1/Cip1-transduced NIH3T3 cells expressed β-galactosidase activity at pH6.0 ,which is known to be a marker of senescence.Our results suggest that P21^Waf1/Cip1 can also induce senescence-like changes in murine cells.     

Gene Regulatory Networks in the Genomics Era

<正>The precise regulation of gene expression is critical to the normal development and biological function of all organisms. Dysregulation of gene expression during early development can result in a spectrum of failures ranging from minor defects to the termination of development. In adult life, dysregulation ncan lead to