Gorman J A, Dove W F, Warren N
Mol Gen Genet. 1981;183(2):306-13. doi: 10.1007/BF00270633.
Hybrid plasmids containint the bacterial resistance-transfer factor pBR322 and the yeast leu2+ gene have been used to isolate DNA fragments of Physarum that are capable of initiating DNA replication in a yeast host. Five of forty hybrid plasmids containint Physarum sequences transform leu2- yeast to Leu+ at high frequency. The resulting Leu+ transformants are characterized by phenotypic instability. Supercoiled plasmid molecules containing pBR322 sequences can be detected in the transformed yeast, indicating that the transforming DNA replicates autonomously. Plasmid DNA isolated from Leu+ yeast can transform leuB bacteria. The hybrid plasmid recovered from the Leu+ bacterial transformants is identical to the original plasmid, indicating structural integrity is maintained during passage through the yeast host. These hybrid plasmids containing Physarum sequences have the same characteristics as those containing autonomously replicating yeast chromosomal sequences. As the temporal sequence of DNA replication is particularly accessible to study in Physarum plasmodia, the functional significance of these segments should be amenable to study.
含有细菌抗性转移因子pBR322和酵母亮氨酸2+基因的杂种质粒已被用于分离多头绒泡菌的DNA片段，这些片段能够在酵母宿主中启动DNA复制。40个含有多头绒泡菌序列的杂种质粒中有5个能高频地将亮氨酸2-酵母转化为亮氨酸+酵母。所得的亮氨酸+转化体具有表型不稳定性的特征。在转化的酵母中可检测到含有pBR322序列的超螺旋质粒分子，这表明转化的DNA能自主复制。从亮氨酸+酵母中分离出的质粒DNA能转化亮氨酸B细菌。从亮氨酸+细菌转化体中回收的杂种质粒与原始质粒相同，这表明在通过酵母宿主的过程中其结构完整性得以保持。这些含有多头绒泡菌序列的杂种质粒与那些含有自主复制酵母染色体序列的质粒具有相同的特征。由于在多头绒泡菌原质团中DNA复制的时间顺序特别便于研究，这些片段的功能意义应该易于研究。
