Barber C E, Archer D B, Daniels M J
Yale J Biol Med. 1983 Sep-Dec;56(5-6):777-81.
With one exception, all spiroplasma strains examined contained extrachromosomal DNA, most of which was in the form of covalently closed circular plasmids. One plasmid, pIJ2000, carried by Spiroplasma citri strain ASP-1, was purified and characterized and used to probe for related plasmids in other strains. Unsuccessful attempts were made to clone pIJ2000 into Escherichia coli using the vectors pAT153 and pBR322. However, spiroplasma chromosomal DNA fragments could be cloned without difficulty.
除了一个例外，所有检测的螺原体菌株都含有染色体外DNA，其中大部分是以共价闭合环状质粒的形式存在。柠檬螺原体菌株ASP-1携带的一个质粒pIJ2000被纯化、鉴定，并用于探测其他菌株中的相关质粒。使用载体pAT153和pBR322将pIJ2000克隆到大肠杆菌中的尝试未成功。然而，螺原体染色体DNA片段可以毫无困难地被克隆。
