Sequence analysis of lacZ~- mutations induced by ion beam irradiation in double-stranded M13mp18DNA

While M13mpl8 double-stranded DNA was irradiated with ion beam, and transfected into E. coli JM103, a decrease of transfecting activity was discovered. The lacZ-mutation frequency at 20% survival could reach (3.6-16.8) × 104, about 2.3-10 times that of unirradiated M13DNA. Altogether, 27 lacZ~ mutants were select-ed, 10 of which were used for sequencing. 7 of the sequenced mutants show base changes in 250-bp region examined (the remaining 3 mutants probably have base changes outside the regions sequenced). 5 of the base-changed mutants contain more than one mutational base sites (some of them even have 5-6 mutational base sites in 250-bp region ex-amined) ; this dense distribution of base changes in polysites has seldom been seen in X-rays, γ-rays or UV induced DNA mutations. Our experiments also showed that the types of base changes include transitions( 50 % ), transversions (45% ) and deletion (5% ); no addition or duplication was observed. The transitions were mainly C→T and A→G; the transversion     

从玉米幼穗再生完整植株

1.植物名称玉米(Zea mays L.)本所杂粮室配制的“肖纱3-2×330”杂交种。 2.材料类别田间生长植株的幼穗(穗长10毫米),切成2～3毫米切段。 3.培养条件诱导愈伤组织培养基为N_6,每升加2,4-D2毫克,NAA0.5毫克或2,4-D2毫克、BA3毫克、KT2毫克、NAA0.5毫克。分化培养基也为N_6,每升加BA2毫克,     

玉米体细胞培养中胚状体的发生

在植物细胞和组织培养中,高等植物发生胚状体的现象比较普遍。单子叶植物从花粉小孢子和体细胞形成胚状体的有水稻、小麦、黑麦、玉米、甘蔗、大麦、无芒雀麦、珍珠谷等。我们对玉米雌、雄幼穗进行培养,获得了体细胞胚状体和胚性细胞团,并建立起细胞无性系。现将试验结果报道如下。