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The vir Gene of Bacteriophage MAV1 Confers Resistance to Phage Infection on Mycoplasma arthritidis. Brenda Clapper, 2004.Lysogenization of Mycoplasma arthritidis with the MAV1 bacteriophage increases the virulence of the mycoplasma in rats . The MAV1 vir gene is one of only two constitutively transcribed phage genes in the lysogen . We show here that Vir is a lipoprotein and is located on the outer surface of the cell membrane . To investigate whether Vir is a virulence factor, the vir gene was cloned into the transposon vector Tn4001T and inserted in the genome of the nonlysogen strain 158 . The virulence of the resulting transformants was no different from that of the parent strain . Interestingly, all vir-containing transformants were resistant to infection by MAV1 . Vir had no effect on MAV1 adsorption . We conclude that Vir is not a virulence factor but functions to exclude superinfecting phage, possibly by blocking the injection of phage DNA into the bacterial cytoplasm . Delivery of Granulocyte-Macrophage Colony-Stimulating Factor in Bioadhesive Hydrogel Stimulates Migration of Dendritic Cells in Models of Human Papillomavirus-Associated (Pre)Neoplastic Epithelial Lesions. Pascale Hubert, 2004.Because of the central role of dendritic cells and/or Langerhans cells(DC/LC) in the induction of cellular immune responses, pharmacological agents that modulate the recruitment of these cells might have a clinical interest . The present study was designed to evaluate the capacity of several pharmaceutical formulations to topically deliver granulocyte-macrophage colony-stimulating factor (GM-CSF) on human papillomavirus (HPV)-associated genital (pre)neoplastic lesions . The formulations were evaluated for their bioactivity and for their potential to recruit DC in organotypic cultures of HPV-transformed keratinocytes . We found that a bioadhesive polycarbophil gel (Noveon) at pH 5.5 is able to maintain the bioactivity of GM-CSF at 4 or 37°C for at least 7 days, whereas a decreased activity of GM-CSF was observed when the molecule is included in other polymer gels . GM-CSF incorporated in the polycarbophil gel was also a potent factor in enhancing the colonization of DC into organotypic cultures of HPV-transformed keratinocytes since the infiltration of DC in the in vitro-formed (pre)neoplastic epithelium was very low under basal conditions and dramatically increased in the presence of GM-CSF gel . We next demonstrated that GM-CSF incorporated in polycarbophil gel induces the recruitment of human DC in a human (pre)neoplastic epithelium grafted into NOD/SCID mice . The efficacy of GM-CSF in this formulation was equivalent to that observed with liquid GM-CSF . These results suggest that GM-CSF incorporated in polycarbophil gel could play an important role in the recruitment of DC/LC in mucosal surfaces and be useful as a new immunotherapeutic approach for genital HPV-associated (pre)neoplastic lesions . High-Salinity-Induced Iron Limitation in Bacillus subtilis. Tamara Hoffmann, 2002.Proteome analysis of Bacillus subtilis cells grown at low and high salinity revealed the induction of 16 protein spots and the repression of 2 protein spots, respectively . Most of these protein spots were identified by mass spectrometry . Four of the 16 high-salinity-induced proteins corresponded to DhbA, DhbB, DhbC, and DhbE, enzymes that are involved in the synthesis of 2,3-dihydroxybenzoate (DHB) and its modification and esterification to the iron siderophore bacillibactin . These proteins are encoded by the dhbACEBF operon, which is negatively controlled by the central iron regulatory protein Fur and is derepressed upon iron limitation . We found that iron limitation and high salinity derepressed dhb expression to a similar extent and that both led to the accumulation of comparable amounts of DHB in the culture supernatant . DHB production increased linearly with the degree of salinity of the growth medium but could still be reduced by an excess of iron . Such an excess of iron also partially reversed the growth defect exhibited by salt-stressed B . subtilis cultures . Taken together, these findings strongly suggest that B . subtilis cells grown at high salinity experience iron limitation . In support of this notion, we found that the expression of several genes and operons encoding putative iron uptake systems was increased upon salt stress . The unexpected finding that high-salinity stress has an iron limitation component might be of special ecophysiological importance for the growth of B . subtilis in natural settings, in which bioavailable iron is usually scarce . Identification of Upstream Sequences Essential for Activation of a Bacteriophage P2 Late Promoter. Gail E. Christie, 2003.We have carried out a mutational scan of the upstream region of the bacteriophage P2 FETUD late operon promoter, PF, which spans an element of hyphenated dyad symmetry that is conserved among all six of the P2 and P4 late promoters . All mutants were assayed for activation by P4 Delta in vivo, by using a lacZ reporter plasmid, and a subset of mutants was assayed in vitro for Delta binding . The results confirm the critical role of the three complementary nucleotides in each half site of the upstream element for transcription factor binding and for activation of transcription . A trinucleotide DNA recognition site is consistent with a model in which these transcription factors bind via a zinc finger motif . The mutational scan also led to identification of the -35 region of the promoter . Introduction of a  70 -35 consensus sequence resulted in increased constitutive expression, which could be further stimulated by Delta . These results indicate that activator binding to the upstream region of P2 late promoters compensates in part for poor
70 contacts and helps to recruit RNA polymerase holoenzyme .
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