INTRODUCING EXOGENOUS DNA INTO PLANTS AFTER POLLINATION——DNA TRAVERSE PATHWAY OF POLLEN TUBE TO REACH EMBRYONIC SAC

The technique of introducing exogenous DNA into plants through the pathway of pollen tube after pollination has been applied since 1978 for transformation of the egg, zygote or carly embryonic cells. By introducing the erogenous DNA containing the goal gene(s) into cotton and rice, several new varieties with economic value and genetic stability are obtained. Thus molecular breeding of crops can be realized by this biotechnique.The pollen tube pathway is demonstrated by tritium-labelled cotton DNA (> 50kb). The labelled DNA is injected into cotton ovaries from the center of the top 24 h after selfing. 30 min to 8 h later, the ovaries are removed. It is clearly shown that the exogenous DNA can only pass from the micrnphyle to the opened nucellus, and then reach the embryonic sac. ~3H-DNA can be found in the embryonic sacs 30 min after injection. In more than 80％ of the embryonic sacs ~3H-DNA can be seen between 2 and 4 h after injection. No ~3H-DNA is found inside the pollen tubes. Therefore it is not th     

毛细管气相色谱法测定大白鼠生物膜标本中磷脂脂肪酸的含量

用十七烷酸（Ｃ＿（１７：０））作内标,对大白鼠红细胞膜、肝徽粒体膜、心肌细胞线粒体膜等生物细胞膜中磷脂脂肪酸含量进行毛细管气相色谱分析。通过低温差速离心,从大白鼠血、肝及心组织中获得纯净的红细胞膜、肝微粒体膜及心肌细胞线粒体膜。用正己烷萃取去掉可能残存于膜样品中的游离脂肪酸,用氯仿甲醇混合提取液提取膜类脂,以５％三氯化用甲醇溶液加热回流,使磷脂脂肪酸水解并甲酯化,其平均酯化率为９４．５％。对各次加入不同量Ｃ＿（１２：０）→Ｃ＿（２２：６）的回收率为９４．５％～９９．８％。