otrA resembles elongation factor G （EF-G） and is considered to be an oxytetracycline （OTC）-resistance determinant in Streptomyces rimosus. In order to determine whether otrA also conferred resistance to OTC and ot...otrA resembles elongation factor G （EF-G） and is considered to be an oxytetracycline （OTC）-resistance determinant in Streptomyces rimosus. In order to determine whether otrA also conferred resistance to OTC and other aminoglycosides to Streptomyces coelicolor, the otrA gene from S. rimosus M527 was cloned under the control of the strong ermE promoter. The resulting plasmid, pIB139-otrA, was introduced into S. coeficolor M145 by intergenedc conjugation, yielding the recombinant strain S. coelicolor M145-OA. As expected S. coelicolor M145-OA exhibited higher resistance levels specifically to OTC and aminoglycosides gentamycin, hygromycin, streptomycin, and spectinomycin. However, unexpectedly, S. coelicolor M14-~OA on solid medium showed an accelerated aerial mycelia formation, a precocious sporulation, and an enhanced actinorhodin （Act） production. Upon growth in 5-L fermentor, the amount of intra- and extracellular Act production was 6-fold and 2-fold higher, respectively, than that of the original strain. Consistently, reverse transcription polymerase chain reaction （RT-PCR） analysis revealed that the transcrip- tional level of pathway-specific regulatory gene acUl-orf4 was significantly enhanced in S. coelicolor M145-OA compared with in S. coelicolor M145.展开更多
Although a variety of applications of the OTRAs have been reported in literature, the pole of the transresistance gain Rm of the OTRA has been usually considered to affect the performance of the circuits due to being ...Although a variety of applications of the OTRAs have been reported in literature, the pole of the transresistance gain Rm of the OTRA has been usually considered to affect the performance of the circuits due to being parasitic. In this paper, the pole of the OTRA has been used to evolve some simple OTRA-based active-R circuits for realizing a synthetic inductor, single resistance controlled oscillator and low-pass/band-pass filter. The workability of all the proposed circuits has been verified by SPICE simulations and all the new circuits have been found to work as predicted by theory. The exemplary propositions suggest that it is worthwhile to further investigate new circuit designs using OTRA-pole.展开更多
基金Project supported by the National Natural Science Foundation of China(No.31772213)the Excellent Youth Fund of Zhejiang Province,China(No.LR17C140002)
文摘otrA resembles elongation factor G （EF-G） and is considered to be an oxytetracycline （OTC）-resistance determinant in Streptomyces rimosus. In order to determine whether otrA also conferred resistance to OTC and other aminoglycosides to Streptomyces coelicolor, the otrA gene from S. rimosus M527 was cloned under the control of the strong ermE promoter. The resulting plasmid, pIB139-otrA, was introduced into S. coeficolor M145 by intergenedc conjugation, yielding the recombinant strain S. coelicolor M145-OA. As expected S. coelicolor M145-OA exhibited higher resistance levels specifically to OTC and aminoglycosides gentamycin, hygromycin, streptomycin, and spectinomycin. However, unexpectedly, S. coelicolor M14-~OA on solid medium showed an accelerated aerial mycelia formation, a precocious sporulation, and an enhanced actinorhodin （Act） production. Upon growth in 5-L fermentor, the amount of intra- and extracellular Act production was 6-fold and 2-fold higher, respectively, than that of the original strain. Consistently, reverse transcription polymerase chain reaction （RT-PCR） analysis revealed that the transcrip- tional level of pathway-specific regulatory gene acUl-orf4 was significantly enhanced in S. coelicolor M145-OA compared with in S. coelicolor M145.
文摘Although a variety of applications of the OTRAs have been reported in literature, the pole of the transresistance gain Rm of the OTRA has been usually considered to affect the performance of the circuits due to being parasitic. In this paper, the pole of the OTRA has been used to evolve some simple OTRA-based active-R circuits for realizing a synthetic inductor, single resistance controlled oscillator and low-pass/band-pass filter. The workability of all the proposed circuits has been verified by SPICE simulations and all the new circuits have been found to work as predicted by theory. The exemplary propositions suggest that it is worthwhile to further investigate new circuit designs using OTRA-pole.
