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Group I Intron Homing in Bacillus Phages SPO1 and SP82: a Gene Conversion Event Initiated by a Nicking Homing Endonuclease. Markus Landthaler, 2004.Many group I introns encode endonucleases that promote intron homing by initiating a double-stranded break-mediated homologous recombination event . In this work we describe intron homing in Bacillus subtilis phages SPO1 and SP82 . The introns encode the DNA endonucleases I-HmuI and I-HmuII, respectively, which belong to the H-N-H endonuclease family and possess nicking activity in vitro . Coinfections of B . subtilis with intron-minus and intron-plus phages indicate that I-HmuI and I-HmuII are required for homing of the SPO1 and SP82 introns, respectively . The homing process is a gene conversion event that does not require the major B . subtilis recombination pathways, suggesting that the necessary functions are provided by phage-encoded factors . Our results provide the first examples of H-N-H endonuclease-mediated intron homing and the first demonstration of intron homing initiated by a nicking endonuclease . Structural Characterization of Lignin during Pinus taeda Wood Treatment with Ceriporiopsis subvermispora. Anderson Guerra, 2004.Pinus taeda wood chips were biotreated with Ceriporiopsis subvermispora under solid-state fermentation for periods varying from 15 to 90 days . Milled wood lignins extracted from sound and biotreated wood samples were characterized by wet-chemical and spectroscopic techniques . Treatment of the lignins by derivatization followed by reductive cleavage (DFRC) made it possible to detect DFRC monomers and dimers that are diagnostic of the occurrence of arylglycerol-ß-O-aryl and ß-ß, ß-5, ß-1, and 4-O-5 units in the lignin structure . Quantification of these DFRC products indicated that ß-O-aryl cleavage was a significant route for lignin biodegradation but that ß-ß, ß-5, ß-1, and 4-O-5 linkages were more resistant to the biological attack . The amount of aromatic hydroxyls did not increase with the split of ß-O-4 linkages, suggesting that the ß-O-4 cleavage products remain as quinone-type structures as detected by UV and visible spectroscopy . Nuclear magnetic resonance techniques also indicated the formation of new substructures containing nonoxygenated, saturated aliphatic carbons (CH2 and CH3) in the side chains of lignins extracted from biotreated wood samples . NikAB- or NikB-Dependent Intracellular Recombination between Tandemly Repeated oriT Sequences of Plasmid R64 in Plasmid or Single-Stranded Phage Vectors. Nobuhisa Furuya, 2003.The origin of transfer (oriT) of a bacterial plasmid plays a key role in both the initiation and termination of conjugative DNA transfer . We have previously shown that a conjugation-dependent recombination between the tandem R64 oriT sequences cloned into pHSG398 occurred, resulting in the deletion of the intervening sequence during DNA transfer . In this study, we tandemly cloned two oriT sequences of IncI1 plasmid R64 into pUC18 . Specific recombination between the two oriT sequences in pUC18 was observed within Escherichia coli cells harboring mini-R64 . This recombination was found to be independent of both the recA gene and conjugative DNA transfer . The R64 genes nikA and nikB, required for conjugal DNA processing, were essential for this recombination . Although a fully active 92-bp oriT sequence was required at one site for the recombination, the 44-bp oriT core sequence was sufficient at the other site . Furthermore, when two oriT sequences were tandemly cloned into the single-stranded phage vector M13 and propagated within E . coli cells, recombination between the two oriT sequences was observed, depending on the nikB gene . These results suggest that the R64 relaxase protein NikB can execute cleavage and rejoining of single-stranded oriT DNA within E . coli cells, whereas such a reaction in double-stranded oriT DNA requires collaboration of the two relaxosome proteins, NikA and NikB . Prevalence and Characteristics of eae-Positive Escherichia coli from Healthy Cattle in Japan. Hideki Kobayashi, 2003.The prevalence of eae-positive Escherichia coli (eaeEC) in Japan was examined using rectal stool samples taken from 35 calves less than 1 month old, 107 calves more than 1 to 3 months old, 88 heifers more than 3 to 6 months old, 214 heifers over 6 months old, and cows from 95 farms . Screening with eae PCR revealed the prevalence to be, with increasing age, 31.4, 8.4, 26.1, and 14.5%, respectively . Of 51 selected eaeEC strains, more than 40% were serotyped as O26, O103, O111, O145, or O157, which are frequently detected as enterohemorrhagic E . coli types . Four strains were identified as recently reported intimin types  ,
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