【摘要】 用Tn5插入导致的T-1（His^-Hup^-Fix^-）变株为受体,从慢生大豆根瘤菌USDA 110基因文库中钓取His⁺结合子10株,经检测,它们都不同程度地恢复了Hup⁺与Fix⁺功能,从它们的DNA琼脂糖凝胶电泳图上,可见到都有一个分子量大小各异的pLAFRI::his质粒,其中5株接合子的重组质粒已转入E.coli HB101中,从它们的质粒电泳图型再显示其分子量各有差异,经Southern转移之后,分别用hup探针和nif探针进行DNA杂交分析,明确EC_r菌株的质粒能与hup和nif探针杂交,EC₆菌株的质粒能与hup探针杂交,其它三株虽能解除Hup^-Fix^-功能上的缺陷,但其质粒DNA序列上并无与nif或hup序列有同源性的成份。更多还原

【Abstract】 Ten pL AFR1 cosmid clones carrying the His Hup Fix region of the Bradyrhizobium japonicum chromosome were isolated from a gene library of B. japonicum USDA 110 by complementation of a His~- Hup~- Fix~- mutant of B. Japonicum USDA110. Five of these recombinant plasmids were transferred into E. coli HB101 for further study. Using hup and nif probes, a plasmid containing a DNA region hybridyzing with hup and nif probes, another plasmid containing a DNA region hybridized only with hup probe were detected. Though the others did not hybridize with hup or nif probe, they did restore the Hup~+ Fix~+ function in His~- Hup~- Fix~- mutant.The results indicate that we have cloned at least three kinds of gene fragments coding for Hup and Fix activity.更多还原