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Local Genetic Patterns within a Vancomycin-Resistant Enterococcus faecalis Clone Isolated in Three Hospitals in Portugal. Carla Novais, 2004.Eight pulsed-field gel electrophoresis subtypes and six Tn1546 variants were identified among Enterococcus faecalis isolates of a single clone recovered in three geographically separate Portuguese hospitals . Some clonal subtypes were found in particular hospitals, and Tn1546 variants were either widespread or confined to some of them . We also report on the first Tn1546 transposon containing an ISEf1 insertion . CsrA Regulates Translation of the Escherichia coli Carbon Starvation Gene, cstA, by Blocking Ribosome Access to the cstA Transcript. Ashok K. Dubey, 2003.CsrA is a global regulator that binds to two sites in the glgCAP leader transcript, thereby blocking ribosome access to the glgC Shine-Dalgarno sequence . The upstream CsrA binding site (GCACACGGAU) was used to search the Escherichia coli genomic sequence for other genes that might be regulated by CsrA . cstA contained an exact match that overlapped its Shine-Dalgarno sequence . cstA was previously shown to be induced by carbon starvation and to encode a peptide transporter . Expression of a cstA'-'lacZ translational fusion in wild-type and csrA mutant strains was examined . Expression levels in the csrA mutant were approximately twofold higher when cells were grown in Luria broth (LB) and 5- to 10-fold higher when LB was supplemented with glucose . It was previously shown that cstA is regulated by the cyclic AMP (cAMP)-cAMP receptor protein complex and transcribed by E  70 . We investigated the influence of
S on cstA expression and found that a
S deficiency resulted in a threefold increase in cstA expression in wild-type and csrA mutant strains; however, CsrA-dependent regulation was retained . The mechanism of CsrA-mediated cstA regulation was also examined in vitro . Cross-linking studies demonstrated that CsrA is a homodimer . Gel mobility shift results showed that CsrA binds specifically to cstA RNA, while coupled-transcription-translation and toeprint studies demonstrated that CsrA regulates CstA synthesis by inhibiting ribosome binding to cstA transcripts . RNA footprint and boundary analyses revealed three or four CsrA binding sites, one of which overlaps the cstA Shine-Dalgarno sequence, as predicted . These results establish that CsrA regulates translation of cstA by sterically interfering with ribosome binding .
Genetic and Biochemical Studies of Phosphatase Activity of PhoR. Daniel O. Carmany, 2003.In Escherichia coli, PhoR is the histidine kinase of the phosphate regulon . It has been postulated that PhoR may function as a phospho-PhoB phosphatase . Experiments with four precise phoR deletion mutants supported this hypothesis and suggested that this activity resides within the histidine phosphorylation domain . This biochemical activity was confirmed by using a separately expressed histidine phosphorylation domain . Giardia Cysts in Wastewater Treatment Plants in Italy. Simone M. Cacciò, 2003.Reductions in annual rainfall in some regions and increased human consumption have caused a shortage of water resources at the global level . The recycling of treated wastewaters has been suggested for certain domestic, industrial, and agricultural activities . The importance of microbiological and parasitological criteria for recycled water has been repeatedly emphasized . Among water-borne pathogens, protozoa of the genera Giardia and Cryptosporidium are known to be highly resistant to water treatment procedures and to cause outbreaks through contaminated raw or treated water . We conducted an investigation in four wastewater treatment plants in Italy by sampling wastewater at each stage of the treatment process over the course of 1 year . The presence of the parasites was assessed by immunofluorescence with monoclonal antibodies . While Cryptosporidium oocysts were rarely observed, Giardia cysts were detected in all samples throughout the year, with peaks observed in autumn and winter . The overall removal efficiency of cysts in the treatment plants ranged from 87.0 to 98.4% . The removal efficiency in the number of cysts was significantly higher when the secondary treatment consisted of active oxidation with O2 and sedimentation instead of activated sludge and sedimentation (94.5% versus 72.1 to 88.0%; P = 0.05, analysis of variance) . To characterize the cysts at the molecular level, the ß-giardin gene was PCR amplified, and the products were sequenced or analyzed by restriction . Cysts were typed as assemblage A or B, both of which are human pathogens, stressing the potential risk associated with the reuse of wastewater .
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