在67种微生物基因组序列中都不存在的最短的碱基组合

对67种微生物基因组全序列进行分析，发现某些碱基组合(及其反向互补序列)在某些基因组中不存在，而这种不存在的概率很低；发现6个11bp的寡核苷酸序列(及其反向互补序列)--AGGGGGGGGTC(GACCCCCCCCT)、AGGGTCCCTG(CTAGGGACCCT)、ACGTACCTAGG(CCTAGGTACGT)、GACACACGTAG(CTACGTGTGTC)、CGCGTAACTAG(CTAGTTACGCG)、CTAGGGACCCA(TGGGTCCCTAG)在这67种基因组中都不存在。上述每个寡核苷酸序列(及其反向互补序列)在由这67种细菌基因组连接而成的DNA分子(长度为169660265bp)中不存在的概率至少小于2．5e-26。     

灰树花紫外诱变育种研究

应用原生质体紫外诱变技术,对灰树花菌株Gr1进行了紫外诱变处理.经过粗筛和精筛后,从50株诱变株中选出两株多糖含量和产量明显优于原始菌株的突变株Gr1a和Gr1g,其产量分别为1.74%和1.62%,多糖质量含量(w)分别为11.67%和12.01%.经过摇瓶试验以及发酵试验,两株诱变菌株Gr1a和Gr1g菌丝得率和多糖含量都很稳定,表明所得突变株是比原始菌株更优秀的稳定高产、高多糖含量的新菌株.     

利用同位素研究无性杂交接穗与砧木关系的一些規律

前言关于高等植物嫁接問題已积累了丰富的生产实践經驗,获得了大量的科学研究資料。可是对无性杂种仍存有各种不同的看法。李森科(1952、1956)、格魯森科(1948、1957)等认为是由于可塑性物貭定向影响的结果。而保尔(Baur、1909)、溫克列尔(Winkler、1907、1910)、克連开(1947)等则有“联合体理論”,柏梅(1953)认为是由于“体細胞回复突变”,安田貞雄(1956)认为是基因“活子”的作用,否认无性杂种的存在。这些情况表明,有必要在前人工作     

STUDIES ON INTRODUCTION OF FOREIGN GENES INTO CULTURED CELLS OF Oryza sativa INDICA USINC Agrobacterium Ti PLASMID SYSTEM

Either bacterial attachment or cellulose fibrillar elaboration was hardly observedduring the cocultivation of the cultured suspension cells of Oryza sativa Indica with thestrain C58C1 Rif~r of Agrobacterium tumefaciens that was not specially pretreated. Onthe other hand, quite a lot of Agrobacterium cells were found to adhere to the surface ofcultured rice cells and a number of cellulose fibrils were produced around the specifiedbacteria when phenolics-pretreated bacteria were cocultivated with rice suspension cellsin common culture media, especially in complex culture solutions. The complex culturesolution was the bacterium-free filtrate of hormone-containing MS medium which hadbeen utilized to incubate carrot cells and the newly wounded hypocotyl segments fromtomato and Agrobacterium cells. Detecting experiments demonstrated that both NPT Ⅱ andNOS genes, located on the T-DNA segment of chimaeric plasmid pGV3850 :: 1103neo, weretransferred and expressed in the cultured cells of O. sativa Indica in the