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ISSa4-Based Differentiation of Streptococcus agalactiae Strains and Identification of Multiple Target Sites for ISSa4 Insertions. Alexander Dmitriev, 2004.A collection of 113 epidemiologically unrelated Streptococcus agalactiae strains were studied [group B streptococcus; GBS]: they belonged to different serotypes and were isolated frompregnant women in China and Russia . The insertion sequence ISSa4was found in 21 of 113 strains [18,6%] . All of the strains withISSa4 belonged to serotypes II and II/c and were characterizedby the presence of IS1381 and IS861 as well as the absence ofIS1548 and GBSi1 . All of the strains with ISSa4 possessed bothbca and bac virulence genes coding for 
and ß antigens,respectively . Among 21 ISSa4-positive strains, 13
differentHindIII patterns [D1 to D13] hybridizing with an
ISSa4 probewere found . One of them [D13] contained a single HindIII
hybridizationfragment 6.5 kb in size that was found to be specific
for allISSa4-positive GBS strains . Multiple target sites for
insertionsof ISSa4 were identified and included a putative
pathogenicityisland, "housekeeping" genes, and intergenic regions,
as wellas the genes for hypothetical proteins . No significant
similaritywas observed in the sequences of the target genes for
ISSa4insertions, in the relative location of the target genes on
the chromosome, or the biological functions of the encoded proteins.
The possible significance of ISSa4-based differentiation ofthe
strains and the presence of possible "hot spots" for insertionsof
ISSa4 in GBS genome are discussed.
tonB3 Is Required for Normal Twitching Motility and Extracellular Assembly of Type IV Pili. Bixing Huang, 2004.Three mutants with Tn5-B21 insertion in tonB3 (PA0406) of Pseudomonas aeruginosa exhibited defective twitching motility and reduced assembly of extracellular pili . These defects could be complemented with wild-type tonB3 . Suppression of Factor-Dependent Transcription Termination by Antiterminator RNA. Rodney A. King, 2003.Nascent transcripts of the phage HK022 put sites modify the transcription elongation complex so that it terminates less efficiently at intrinsic transcription terminators and accelerates through pause sites . We show here that the modification also suppresses termination in vivo at two factor-dependent terminators, one that depends on the bacterial Rho protein and a second that depends on the HK022-encoded Nun protein . Suppression was efficient when the termination factors were present at physiological levels, but an increase in the intracellular concentration of Nun increased termination both in the presence and absence of put . put-mediated antitermination thus shows no apparent terminator specificity, suggesting that put inhibits a step that is common to termination at the different types of terminator . Isolation and Characterization of NaCl-Sensitive Mutants of Caulobacter crescentus. Luiz Fernando G. Zuleta, 2003.An attempt to characterize Caulobacter crescentus genes important for the response to high concentrations of NaCl was initiated by the isolation of mutants defective in survival in the presence of 85 mM NaCl . A transposon Tn5 library was screened, and five strains which contained different genes disrupted by the transposon were isolated . Three of the mutants had the Tn5 in genes involved in lipopolysaccharide biosynthesis, one had the Tn5 in the nhaA gene, which encodes a Na+/H+ antiporter, and one had the Tn5 in the ppiD gene, which encodes a peptidyl-prolyl cis-trans isomerase . All the mutant strains showed severe growth arrest in the presence of 85 mM NaCl, but only the nhaA mutant showed decreased viability under these conditions . All the mutants except the nhaA mutant showed a slightly reduced viability in the presence of 40 mM KCl, but all the strains showed a more severe reduction in viability in the presence of 150 mM sucrose, suggesting that they are defective in responding to osmotic shock . The promoter regions of each disrupted gene were cloned in lacZ reporter vectors, and the pattern of expression in response to NaCl and sucrose was determined; this showed that both agents induced ppiD and nhaA gene expression but did not induce the other genes . Furthermore, the ppiD gene was not induced by heat shock, indicating that it does not belong to the  32 regulon, as opposed to what was observed for its Escherichia coli homolog .
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