Roy R K, Murty S S, Chakravorty M
Molecular Biology Unit, Banaras, Hindu University, Varanasi, India.
Plasmid. 1995 Sep;34(2):144-7. doi: 10.1006/plas.1995.9993.
A naturally occurring plasmid isolated from a drug-resistant strain of Salmonella typhimurium (993) has been used to construct a plasmid vector for cloning in a wild strain of Salmonella. The strain (993) contains at least two plasmids. The smaller plasmid (9 kb) contains an ampicillin-resistant marker, while the larger one (25 kb) is cryptic. Physical mapping of the 9-kb plasmid and construction of a 3.5-kb derivative have been carried out. This plasmid has been used for cloning in a restriction+modification+strain of S. typhimurium using a conventional calcium chloride method. It exhibited better efficiency of transformation than other commonly used plasmids such as pBR322 or its derivatives and transformants were found to be stable in the absence of antibiotic selection. The vector is compatible with pBR322 and can be used to study the expression of cloned genes in minicells.
从鼠伤寒沙门氏菌耐药菌株（993）中分离出的一种天然存在的质粒已被用于构建一种用于在鼠伤寒沙门氏菌野生菌株中克隆的质粒载体。菌株（993）含有至少两种质粒。较小的质粒（9 kb）含有氨苄青霉素抗性标记，而较大的质粒（25 kb）是隐蔽型的。已对9 kb质粒进行了物理图谱分析并构建了一个3.5 kb的衍生物。该质粒已通过常规氯化钙方法用于在鼠伤寒沙门氏菌的限制 + 修饰 + 菌株中进行克隆。它表现出比其他常用质粒如pBR322或其衍生物更好的转化效率，并且发现转化体在没有抗生素选择的情况下是稳定的。该载体与pBR322兼容，可用于研究克隆基因在微小细胞中的表达。
