The moblizable plashed pBF101 carrying Tn5-nifA of E. cloacae E26 was introduced into K. oxytoca NG13 with high frequency from donor E. coli S17-1 by mating. Tn5-nifA was transposed spontaneously from PBF101 into the ...The moblizable plashed pBF101 carrying Tn5-nifA of E. cloacae E26 was introduced into K. oxytoca NG13 with high frequency from donor E. coli S17-1 by mating. Tn5-nifA was transposed spontaneously from PBF101 into the genome of NG13 with a frequency of 6 ×10-5. Strain NG1394 was obtamed by selecting KmrCms colonies,which had lost plashed PBF101 and into which transposition of Tns-nifA had occurred. The integrahon of nifA gene into the genome in NG1394 was verified by agarose gel electrophoresis (Fig. 1) and curing of plasdrid with acridine orange. The synthesis of nitrogrnase in NG1394 was not repressed by (Table 1 ). Constitutive nifA could be stably maintained in NG1394 without antibiotic selection stress. borne nitrogenase activity was detected in NG1394 at 39℃ while NG13 (wild type) competely lost the activity at 39℃ (table 2).展开更多
Several studies have demonstrated that the Rhizobium nifA gene is an activator of nitrogen fixation acting in nodule bacteria. To understand the effects of the Sinorhizobium meliloti nifA gene on Alfalfa, the cDNA-AFL...Several studies have demonstrated that the Rhizobium nifA gene is an activator of nitrogen fixation acting in nodule bacteria. To understand the effects of the Sinorhizobium meliloti nifA gene on Alfalfa, the cDNA-AFLP technique was employed to study the changes in gene expression in nifA mutant nodules. Among the approximately 3,000 transcriptderived fragments, 37 had differential expression levels. These expression levels were subsequently confirmed by reverse Northern blot and RT-polymerase chain reaction. Sequence analyses revealed that 21 cDNA fragments corresponded to genes involved in signal communication, protein degradation, nutrient metabolism, cell growth and development.展开更多
文摘The moblizable plashed pBF101 carrying Tn5-nifA of E. cloacae E26 was introduced into K. oxytoca NG13 with high frequency from donor E. coli S17-1 by mating. Tn5-nifA was transposed spontaneously from PBF101 into the genome of NG13 with a frequency of 6 ×10-5. Strain NG1394 was obtamed by selecting KmrCms colonies,which had lost plashed PBF101 and into which transposition of Tns-nifA had occurred. The integrahon of nifA gene into the genome in NG1394 was verified by agarose gel electrophoresis (Fig. 1) and curing of plasdrid with acridine orange. The synthesis of nitrogrnase in NG1394 was not repressed by (Table 1 ). Constitutive nifA could be stably maintained in NG1394 without antibiotic selection stress. borne nitrogenase activity was detected in NG1394 at 39℃ while NG13 (wild type) competely lost the activity at 39℃ (table 2).
文摘Several studies have demonstrated that the Rhizobium nifA gene is an activator of nitrogen fixation acting in nodule bacteria. To understand the effects of the Sinorhizobium meliloti nifA gene on Alfalfa, the cDNA-AFLP technique was employed to study the changes in gene expression in nifA mutant nodules. Among the approximately 3,000 transcriptderived fragments, 37 had differential expression levels. These expression levels were subsequently confirmed by reverse Northern blot and RT-polymerase chain reaction. Sequence analyses revealed that 21 cDNA fragments corresponded to genes involved in signal communication, protein degradation, nutrient metabolism, cell growth and development.
