CONJUGAL TRANSFER OF BACTEROIDES ANTIBIOTIC RESISTANCES

对克林霉素(CC-r)和四环素(TC-r)的耐药性可以转移 通过在类杆菌中结合。某些CC-R菌株含有结合体 CC-r质粒。共轭T_c-r元素和共轭T_c-r-C_c-r 在质粒上没有发现这些元素，但它们似乎整合在 类杆菌染色体。克林霉素是治疗的首选药物 厌氧感染，CC-r在类杆菌中的传播是 临床问题。TC-R共偶体系有时共转移CC-R En 阻断并可动员至少一个CC-r质粒和几个隐形载体 类杆菌质粒。三个接合的CC-r质粒含有一个 转座子，Tn4351，携带CC-r决定簇和a*Tc-r 仅在需氧培养的大肠杆菌中表达的决定簇。Tn4351 在大肠杆菌和类杆菌中都有转座。Tn4351将用于研究 CC-r基因在类杆菌染色体和类杆菌质粒中的传播， 尤其是对任何一种神秘的质粒。TC-R系统将是 使用Tn4351，通过以下方法表征：i)使用Tn4351 在类杆菌中插入Tc-r元件以在大肠杆菌中进行克隆 以确定整个Tc-r元素的大小和位置，并 亚克隆和分离T_c-r决定簇本身。Ii)使用Tn4351 转座子诱变定位TC-r系统转移基因和 在类杆菌中引起营养缺乏症以确定染色体DNA是否 与TC-R共转移。三)使用与过去类似的方法 分离Tn4351以确定TC-r是否也在转座子上。四)使用 Tn4351，包含由 TC-r系统，插入类杆菌染色体的不同位置，以 看看TC-R系统是否会启动染色体在这些区域的转移 网站。

Resistance to clindamycin (Cc-r) and tetracycline (Tc-r) can be transferred by conjugation in bacteroides. Certain Cc-r strains contain conjugative Cc-r plasmids. The conjugative Tc-r elements and conjugative Tc-r-Cc-r elements are not found on plasmids but appear to be integrated in the Bacteroides chromosome. Clindamycin is the drug of choice for treating anaerobic infections, and the spread of Cc-r among Bacteroides is of clinical concern. The Tc-r conjugal system sometimes co-transfers Cc-r en bloc and can mobilize at least one Cc-r plasmid and several cryptic Bacteroides plasmids. Three of the conjugative Cc-r plasmids contain a transposon, Tn4351, which carries the Cc-r determinant and a *Tc-r determinant that expresses only in aerobically grown E. coli. Tn4351 transposes in both E. coli and Bacteroides. Tn4351 will be used to study the spread of Cc-r to Bacteroides chromosome and to Bacteroides plasmids, especially to any of the cryptic plasmids. The Tc-r system will be characterized, using Tn4351, by the following methods: i) Use Tn4351 insertions into the Tc-r element in Bacteroides to allow cloning in E. coli to determine the size and location of the entire Tc-r element and to subclone and isolate the Tc-r determinant itself. ii) Use Tn4351 transposon mutagenesis to locate the transfer genes of the Tc-r system and to cause auxotrophs in Bacteroides to determine if chromosomal DNA is co-transferred with Tc-r. iii) Use methods similar to those used to isolate Tn4351 to determine if the Tc-r is also on a transposon. iv) Use Tn4351, containing cloned origins of transfer that are recognized by the Tc-r system, inserted into various sites of the Bacteroides chromosome to see if the Tc-r system will initiate transfer of the chromosome at those sites.