[29] while detection of the 3′-CS and the variable cassette region was done as described

previously by Dalsgaard et al. [30]. Detection of intI2 was performed as previously described by Falbo et al. [31]. Screening for the integrase specific to integron class 3 (intI3) and integron class 4 (intI4) was performed as detailed previously by Machado et al. and Shi et al. respectively [32, 33]. We also conducted PCR experiments using the genomic DNA isolated from donors and transconjugants to verify the transfer of the Tn21 and the SXT/R391-like element. Detection of Tn21 transposon was done using trpM-specific primers and selleck kinase inhibitor PCR conditions published previously by Villa et al. [34] while detection of Tn7 was done using PCR conditions and primers described previously by Hansson et al. [26]. The presence of the ICE was detected using primers for amplification of a 1035 bp fragment of the integrase gene specific for the SXT/R391-like element as described previously by Bhanumathi et al. [35]. www.selleckchem.com/products/Vorinostat-saha.html Integration of the ICE into the chromosome was demonstrated by amplification of a PCR product of 825 bp corresponding to the right junction between the attP element of the ICE and the prfC chromosomal gene

of the bacteria. Primers and PCR conditions used are similar to those published before by Pugliese et al. [7]. Strains from our culture collection known to harbour various genes of interest were used as appropriate positive controls in corresponding PCR experiments. Analysis of Vibrio cholerae virulence genes PRKACG All strains were screened for the presence of genes encoding virulence determinants in V. cholerae including cholera toxin (ctxA), zonula occludens toxin (zot), accessory cholera enterotoxin (ace), hemolysin (hlyA), and NAG-specific heat-stable toxin (st). Detection of the tcpA gene specific to the El Tor and Classical biotypes was

done using a common forward primer and biotype-specific reverse primers. Similarly, two forward primers were used for the detection of the biotype-specific haemolysin gene (hylA). PCR conditions and primers used for the detection of tcpA, ompU, tcpI, toxR and hylA genes were similar to those described previously by Rivera et al. [29] while detection of the ctxA gene was done using primers and conditions described before by Fields et al. [36]. Genomic DNA from V. cholerae O139 strain ATCC 51394 was used as a positive control in screening for ctxA, zot, ace, tcpA, ompU, tcpI, and toxR genes. For detection of the four rstR gene alleles, a single reverse primer was used in combination with forward primers specific for each of the four rstR gene alleles as described previously by Nusrin et al. [37]. Plasmid analysis DNA for plasmid analysis was extracted using the method of Kado and Liu [38] with a few modifications [39]. DNA was resuspended in 50 μl of TE buffer containing 10 mM Tris, and 1 mM EDTA (pH 8) and separated by electrophoresis on 0.