Affinity chromatography—dependent selection （ACDS） of genomic DNA fragments bound specifically to bacterial synthesized Myc／Myn proteins

This paper describes an approach to seek for mouse c-Myc/Myn proteins-bound specific sequences among genomic DNA.cDNA fragment of myn gene was obtained through RT-PCR technique from RNA of NIH3T3 cells.DNA fragments encoding BR/HLH/LZ structure of Myc and Myn proteins were cloned in frame into pGEX-2T vector respectively.Fusion GST-Myc and GST-Myn synthesized in E.coli hosts showed affinity to CACGTG E-box DNA and subsequently interacted with genomic fragments prepared through whole-genome-PCR.A PCR-assisted procedure which combines protein-DNA interaction and affinity chromatography was designed to enrich Myc/Myn bound DNA.At least two genomic DNA fragments obtained exhibit specifical binding capacity to Myc/Myn complex but not to GST alone.Significance of the work and of the technique itself as well asidentification of the DNAs are discussed.     

蛇床幼茎离体培养中体细胞胚胎形成的观察

蛇床幼茎外植体经诱导产生了愈伤组织。在ＭＳ＋２,４－Ｄ,０．２ｍｇ／Ｌ＋ＺＴ０．４ｍｇ／Ｌ培养基中,愈伤组织转变成胚性愈伤组织。转入ＭＳ＋ＮＡＡ０．２ｍｇ／Ｌ＋ＺＴ０．８ｍｇ／Ｌ培养基以后,胚性愈伤组织分化出体细胞胚胎。体细胞胚胎在ＭＳ＋ＮＡＡ０．５ｍｇ／Ｌ培养基中可直接发育成为完整植析。显微观察表明,体细胞胚胎产生于愈伤组织的表层细胞或内部细胞。在鱼雷胚期已有螺纹导管的分化。子叶期的维管组织从两     

The inhibitory effect of transthyretin gene on growth of human hepatoma cells

Transthyretin(TTR) gene was highly expressed in normal liver and it has been found to be deleted in part of DNA samples from human hepatic cancer.Its mRNA expression was suppressed in most hepatoma samples.In order to study the biological effect of TTR gene on the growth of hepatoma cells,a recombinant vector containing TTR cDNA was constructed by pCMV,then it was transfected into hepatoma cell lines SMMC-7721 and Q3.It has been demonstrated that the inhibition of growth rate of TTR cDNA transfected hepatoma cells was about 50% in strength compared with that of the control.This inhibition was further enhanced when the transfected hepatoma cells were treated with all-trans retinoic acid.Hepatoma cells of cell lines PLC/PRF/5,SMMC-7721 and Q3 as well as hepatoma cells SMMC-7721 transfected with pCMV or pCMV-TTR were analyzed for TTR expression by Northern hybridization.The low level of TTR expression was found in both hepatoma cell lines and in SMMC-7721 cells transfected with pCMV alone.However,a remarkable TTR mRNA expression was observed in hepatoma SMMV-7721 cells transfected with pCMV-TTR.It seems possible that TTR gene might be a candidate of cancer suppressor gene for human hepatic cancer.     

A stage—specific protein factor binding to a CACCC motif in both human β—globin gene promoter and 5‘—HS2 region

The DNaseI hypersensitive site 2 (HS2) of human β-globin locus control region(LCR) is required for the high level expression of human β-globin genes.In the present study,a stage-specific protein factor (LPF-β) was identified in the nuclear extract prepared from mouse fetal liver at d 18 of gestation,which could bind to the HS2 region of human β-globin LCR.We also found that the shift band of LPF-β factor could be competed by human β-globin promoter.However,it couldn‘t be competed by human ε-globin promoter or by human ^Aγ-globin promoter.Furthermore,our data demonstrated that the binding-sequence of LPF-β factor is 5‘CACACCCTA 3‘,which is located at the HS2 region of β-LCR(from-10845 to-10853 bp)and human β-globin promoter(from-92 to -84 bp).We speculated that these regions containing the CACCC box in both the human β-globin promoter and HS2 might function as stage selector elements in the regulation of human β-globin switching and the LPF-β factor might be a stage-specific protein factor involved in the regulation of human β-globin gene expression.     

乙型肝炎流行病学数学模型

本文根据乙型肝炎的自然传播过程,建立由偏微分方程表达的数学模型．模型中所有参数都由实际资料估计所得,而且考虑了乙型肝炎感染与转归随年龄变化的特点．免疫接种前、后模型模拟的结果与实际观察值相符,这说明模型能够反映乙型肝炎在人群中的传播过程．     

中国稻蝗属细胞分类学研究(英文)

本文对分布于中国境内11省区,27个采集地点的八种稻蝗进行了染色体C带核型比较研究。结果表明:中华稻蝗Oxya chinensis,上海稻蝗O.shanghaiensis,无齿稻蝗O.adentata C带分布型式相似,但染色体分组型式、交叉定位数据以及异染色质含量具有差异;山稻蝗O.agauisa具有本身独特的带纹结构,与本属其它种类迥异;双带稻蝗O.bicingula染色体带型结构相似于山稻蝗及中华稻蝗类群,表明三者在进化历程中有一定联系。小稻蝗O.hyla intricata中一个亲缘种团(Sibling species group),体现在种内的形态差异及染色体带型结构的不同。显示该种近期内分化速率较高。据此,本文讨论了稻蝗属内八个种相互间的亲缘关系和分类地位,本文认为稻蝗属内务物种进化速率是不均衡的,这种状态应归因于各物种的遗传背景和环境因素的影响。     

在调查反馈的信息中探寻生物教学方向

生物学是当代科学研究的热点和前沿,它与人类面临的“环境”、“人口”、“粮食”、“能源”四大危机具有密切关系。为了提高国民素质,在基础教育中普及生物知识是非常必要的,但由于追求升学考试等现实问题,使生物学科在中学理科中的位置面临很严重的问题(与发达