Biomed Environ Sci, 2012; 25(6): 639‐644 639 *This work was supported by the National Natural Science Foundation of China (30930001 and 30900823). # Corresponding should be addressed to ZHOU Dong Sheng. Tel: 86‐10‐66948594. E‐mail: dongshengzhou1977@gmail.com Biographical not of the first authors: ZHANG Yi Quan, male, born in 1985, Ph.D candidate, majoring in bacterial gene regulation; MA Li Zhi, female, born in 1973, attending physician, majoring in bacterial gene regulation. Received: September 20, 2011; Accepted: December 2, 2011 Original Article Use of Rich BHI Medium Instead of Synthetic TMH Medium for Gene Regulation Study in Yersinia pestis * ZHANG Yi Quan 1 , MA Li Zhi 1,2 , WANG Li 1,3 , GAO He 1,4 , TAN Ya Fang 1 , GUO Zhao Biao 1 , QIU Jing Fu 3 , YANG Rui Fu 1 , and ZHOU Dong Sheng 1, # 1. State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China; 2.Department of Emergency Medicine, General Hospital of Chinese People's Armed Police Forces, Beijing 100039, China; 3. Department of Medical Laboratory, Chongqing Medical University, Chongqing 400016, China; 4. State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing 102206, China Abstract Objective This study is to verify the use of rich BHI medium to substitute synthetic media for gene regulation studies in Yersinia pestis. Methods The transcriptional regulation of rovA by PhoP or via temperature upshift, and that of pla by CRP were investigated when Y. pestis was cultured in BHI. After cultivation under 26 °C, and with temperature shifting from 26 to 37 °C, the wild‐type (WT) strain or its phoP or crp null mutant (ΔphoP or Δcrp, respectively) was subject to RNA isolation, and then the promoter activity of rovA or pla in the above strains was detected by the primer extension assay. The rovA promoter‐proximal region was cloned into the pRW50 containing a promoterless lacZ gene. The recombinant LacZ reporter plasmid was transformed into WT and ΔphoP to measure the promoter activity of rovA in these two strains with the β‐Galactosidase enzyme assay system. Results When Y. pestis was cultured in BHI, the transcription of rovA was inhibited by PhoP and upon temperature upshift while that of pla was stimulated by CRP. Conclusion The rich BHI medium without the need for modification to be introduced into the relevant stimulating conditions (which are essential to triggering relevant gene regulatory cascades), can be used in lieu of synthetic TMH media to cultivate Y. pestis for gene regulation studies. Key words: Yersinia pestis; BHI; TMH; Gene regulation Biomed Environ Sci, 2012; 25(6):639‐644 doi: 10.3967/0895‐3988.2012.06.005 ISSN:0895‐3988 www.besjournal.com(full text) CN: 11‐2816/Q Copyright ©2012 by China CDC INTRODUCTION lague is a fatal infectious disease caused by Yersinia pestis. Y. pestis is cycled among flea vectors and rodent reservoirs in natural plague foci, and it also infects humans by bite of infected flea, contact with infected tissues, or inhalation of respiratory droplets or aerosols, during which the expression of virulence/transmission‐ required genes is tightly regulated [1‐3] . PhoP is the P