Genes (ebrAB) responsible for ethidium resistance were cloned from chromosomal DNA of Bacillus subtilis ATCC 9372. The recombinant plasmid produced elevated resistance against ethidium bromide, acriflavine, pyronine Y, and safranin O not only in Escherichia coli but also in B. subtilis. It also caused an elevated energy-dependent efflux of ethidium in E. coli. EbrA and EbrB showed high sequence similarity with members of the small multidrug resistance (SMR) family of multidrug efflux pumps. Neither ebrA nor ebrB was sufficient for resistance, but introduction of the two genes carried on different plasmids conferred drug resistance. Thus, both EbrA and EbrB appear to be necessary for activity of the multidrug efflux pump. In known members of the SMR family, only one gene produces drug efflux. Thus, EbrAB is a novel SMR family multidrug efflux pump with two components.Drug efflux from cells is one of the major mechanisms of drug resistance. Multidrug efflux pumps are widely distributed in membranes ranging from bacterial cells to animal cells and remove toxic substances from the cytoplasm or membranes in an energy-dependent manner. The multidrug efflux pumps are responsible for multidrug resistance in bacterial cells and in cancer cells. Thus, the presence of multidrug efflux pumps is a serious problem in the treatment of infectious diseases and cancer. Several major groups of multidrug extrusion systems are known in microorganisms (2,11,17). One such group is the small multidrug resistance (SMR) family, and members of this family have been found in many microorganisms (19). Transporters of the SMR family are rather small and usually possess four transmembrane domains in one polypeptide. The SMR family includes more than 40 proteins in eubacteria, and a few of them have been studied in detail (19,24). These include Smr (Staphylococcus aureus) (6) and EmrE (Escherichia coli) (25). It is very likely that the SMR family drug transporters are drug/ H ϩ antiporters. During the course of our studies of multidrug transporters in bacterial cells, we found a unique system in Bacillus subtilis ATCC 9372: a two-component drug transporter that belongs to the SMR family. MATERIALS AND METHODSBacteria and growth. B. subtilis ATCC 9372 was used as a donor of chromosomal DNA. E. coli KAM3 (15), a derivative of K-12 that lacks a restriction system and AcrAB (13), was used as the cloning host and for drug susceptibility testing. B. subtilis ISW1214 (hsrM leuA8 metB5; Tet s ) was purchased from TaKaRa Co. and used for the drug susceptibility test. B. subtilis and E. coli cells were grown in Luria-Bertani (LB) broth (10) under aerobic conditions at 37°C. Where indicated, drugs were added to the medium.Drug susceptibility test. The MICs of drugs were determined in MuellerHinton broth (Difco) containing various drugs at various concentrations as indicated. Cells in the test medium (10 5 cells/ml) were incubated at 37°C for 24 h, and thereafter the growth was judged.Gene manipulation. The gene responsible for ethidium resistance was clo...

These results suggest that PGD2 is released via the action of h-PGDS from various cells, and the expression of h-PGDS may be associated with the hypertrophic inflammation in the nose. In addition, ligation of PGD2 to CRTH2 appears to be selectively involved in eosinophil recruitment into the nose regardless of atopic status.

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• CT fluoroscopy-guided renal tumour biopsy has a high diagnostic yield. • CT fluoroscopy-guided renal tumour biopsy is safe. • Small tumour size (≤1.5 cm) is a risk factor for diagnostic failure.

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