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Susceptibility of Candida Species to Photodynamic Effects of Photofrin. Joseph M. Bliss, 2004.The in vitro susceptibility of pathogenic Candida species to the photodynamic effects of the clinically approved photosensitizing agent Photofrin was examined . Internalization of Photofrin by Candida was confirmed by confocal fluorescence microscopy, and the degree of uptake was dependent on incubation concentration . Uptake of Photofrin by Candida and subsequent sensitivity to irradiation was influenced by culture conditions . Photofrin uptake was poor in C . albicans blastoconidia grown in nutrient broth . However, conversion of blastoconidia to filamentous forms by incubation in defined tissue culture medium resulted in substantial Photofrin uptake . Under conditions where Photofrin was effectively taken up by Candida, irradiated organisms were damaged in a drug dose- and light-dependent manner . Uptake of Photofrin was not inhibited by azide, indicating that the mechanism of uptake was not dependent on energy provided via electron transport . Fungal damage induced by Photofrin-mediated photodynamic therapy (PDT) was determined by evaluation of metabolic activity after irradiation . A strain of C . glabrata took up Photofrin poorly and was resistant to killing after irradiation . In contrast, two different strains of C . albicans displayed comparable levels of sensitivity to PDT . Furthermore, a reference strain of C . krusei that is relatively resistant to fluconazole compared to C . albicans was equally sensitive to C . albicans at Photofrin concentrations of  3 µg/ml . The results indicate that photodynamic therapy may be a useful adjunct or alternative to current anti-Candida therapeutic modalities, particularly for superficial infections on surfaces amenable to illumination .
fleQ, the Gene Encoding the Major Flagellar Regulator of Pseudomonas aeruginosa, Is  70 Dependent and Is Downregulated by Vfr, a Homolog of Escherichia coli Cyclic AMP Receptor Protein.Nandini Dasgupta, 2002.The flagellar transcriptional regulator FleQ appears to be the highest-level regulator in the hierarchical regulatory cascade of flagellar biogenesis in Pseudomonas aeruginosa . Except for the posttranslational downregulation of FleQ activity by FleN, an antiactivator, not much is known about the regulation of the fleQ gene or its gene product . Some FleQ homologs in other bacterial species either are positively regulated by another regulator (e.g., CtrA, the master regulator regulating FlbD in Caulobacter crescentus) or are expressed from a 70-dependent promoter (e.g., FlgR of Helicobacter pylori) . In this study we demonstrated that Vfr, an Escherichia coli CRP homolog known to function as an activator for various genes, including lasR, regA, and toxA, in P . aeruginosa, is capable of repressing fleQ transcription by binding to its consensus sequence in the fleQ promoter . In a DNase I footprint assay, purified Vfr protected the sequence 5'-AATTGACTAATCGTTCACATTTG-3' . When this putative Vfr binding site in the fleQ promoter was mutated, Vfr was unable to bind the fleQ promoter fragment and did not repress fleQ transcription effectively . Primer extension analysis of the fleQ transcript revealed two transcriptional start sites, t1 and t2, that map within the Vfr binding site . A putative -10 region (TAAAAT) for the t2 transcript, with a five-of-six match with the E . coli
70 binding consensus, overlaps with one end of the Vfr binding site . A 4-bp mutation and an 8-bp mutation in this -10 region markedly reduced the activity of the fleQ promoter . The same mutations led to the disappearance of the 203-nucleotide fleQ transcript in an in vitro transcription assay . Vfr probably represses fleQ transcription by binding to the Vfr binding site in the fleQ promoter and preventing the sigma factor from binding to the -10 region to initiate transcription .
Rapid Surface Motility in Bacillus subtilis Is Dependent on Extracellular Surfactin and Potassium Ion. Rebecca F. Kinsinger, 2003.Motility on surfaces is an important mechanism for bacterial colonization of new environments . In this report, we describe detection of rapid surface motility in the wild-type Bacillus subtilis Marburg strain, but not in several B . subtilis 168 derivatives . Motility involved formation of rapidly spreading dendritic structures, followed by profuse surface colonies if sufficient potassium ion was present . Potassium ion stimulated surfactin secretion, and the role of surfactin in surface motility was confirmed by deletion of a surfactin synthase gene . Significantly, this motility was independent of flagella . These results demonstrate that wild-type B . subtilis strains can use both swimming and sliding-type mechanisms to move across surfaces . Environmental Isolates of Aeromonas spp . Harboring the cagA-Like Gene of Helicobacter pylori. Simanti Datta, 2003.We investigated the presence of cagA-like gene of Helicobacter pylori in environmental isolates of Aeromonas spp . from different water samples of Calcutta, India, by colony hybridization using a cagA-specific DNA probe and by PCR with cagA-specific primers . Nucleotide sequencing of five PCR products revealed 97 to 98% homology to canonical cagA of H . pylori 26695 as well as to four clinical H . pylori strains from Calcutta . The cagA-like gene of the environmental isolates was unstable in laboratory conditions and tended to be lost upon subculturing .
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