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A Homologue of aliB Is Found in the Capsule Region of Nonencapsulated Streptococcus pneumoniae. Lucy J. Hathaway, 2004.The epidemiology, phylogeny, and biology of nonencapsulated Streptococcus pneumoniae are largely unknown . Increased colonization capacity and transformability are, however, intriguing features of these pneumococci and play an important role . Twenty-seven nonencapsulated pneumococci were identified in a nationwide collection of 1,980 nasopharyngeal samples and 215 blood samples obtained between 1998 and 2002 . On the basis of multilocus sequence typing and capsule region analysis we divided the nonencapsulated pneumococci into two groups . Group I was closely related to encapsulated strains . Group II had a clonal population structure, including two geographically widespread clones able to cause epidemic conjunctivitis and invasive diseases . Group II strains also carried a 1,959-bp homologue of aliB (aliB-like ORF 2) in the capsule region, which was highly homologous to a sequence in the capsule region of Streptococcus mitis . In addition, strains of the two major clones in group II had an additional sequence, aliB-like ORF 1 (1,968 to 2,004 bp), upstream of aliB-like ORF 2 . Expression of aliB-like ORF 1 was detected by reverse transcription-PCR, and the corresponding RNA was visualized by Northern blotting . A gene fragment homologous to capN of serotypes 33 and 37 suggests that group II strains were derived from encapsulated pneumococci some time ago . Therefore, loss of capsule expression in vivo was found to be associated with the importation of one or two aliB homologues in some nonencapsulated pneumococci . Comparison of Simultaneous Splenic Sample PCR with Blood Sample PCR for Diagnosis and Treatment of Experimental Ehrlichia canis Infection. Shimon Harrus, 2004.This report presents evidence that dogs recover from acute canine monocytic ehrlichiosis (CME) after 16 days of doxycycline treatment (10 mg/kg of body weight every 24 h) . Blood PCR was as valuable as splenic aspirate PCR for early diagnosis of acute CME . Splenic aspirate PCR was, however, superior to blood PCR for the evaluation of ehrlichial elimination . VdNEP, an Elicitor from Verticillium dahliae, Induces Cotton Plant Wilting. Jian-Ying Wang, 2004.Verticillium wilt is a vascular disease of cotton . The causal fungus, Verticillium dahliae, secretes elicitors in culture . We have generated  1,000 5'-terminal expressed sequence tags (ESTs) from a cultured mycelium of V . dahliae . A number of ESTs were found to encode proteins harboring putative signal peptides for secretion, and their cDNAs were isolated . Heterologous expression led to the identification of a protein with elicitor activities . This protein, named V . dahliae necrosis- and ethylene-inducing protein (VdNEP), is composed of 233 amino acids and has high sequence identities with fungal necrosis- and ethylene-inducing proteins . Infiltration of the bacterially expressed His-VdNEP into Nicotiana benthamiana leaves resulted in necrotic lesion formation . In Arabidopsis thaliana, the fusion protein also triggered production of reactive oxygen species and induced the expression of PR genes . When added into suspension cultured cells of cotton (Gossypium arboreum), the fusion protein elicited the biosynthesis of gossypol and related sesquiterpene phytoalexins at low concentrations, and it induced cell death at higher concentrations . On cotton cotyledons and leaves, His-VdNEP induced dehydration and wilting, similar to symptoms caused by a crude preparation of V . dahliae elicitors . Northern blotting showed a low level of VdNEP expression in the mycelium during culture . These data suggest that VdNEP is a wilt-inducing factor and that it participates in cotton-V . dahliae interactions .
Role of the C-Terminal Domain of the Alpha Subunit of RNA Polymerase in LuxR-Dependent Transcriptional Activation of the lux Operon during Quorum Sensing. Angela H. Finney, 2002.During quorum sensing in Vibrio fischeri, the luminescence, or lux, operon is regulated in a cell density-dependent manner by the activator LuxR in the presence of an acylated homoserine lactone autoinducer molecule [N-(3-oxohexanoyl) homoserine lactone] . LuxR, which binds to the lux operon promoter at a position centered at -42.5 relative to the transcription initiation site, is thought to function as an ambidextrous activator making multiple contacts with RNA polymerase (RNAP) . The specific role of the  -subunit C-terminal domain (CTD) of RNAP in LuxR-dependent transcriptional activation of the lux operon promoter has been investigated . The effects of 70 alanine substitution variants of the
subunit were determined in vivo by measuring the rate of transcription of the lux operon via luciferase assays in recombinant Escherichia coli . The mutant RNAPs from strains exhibiting at least twofold-increased or -decreased activity in comparison to the wild type were further examined by in vitro assays . Since full-length LuxR has not been purified, an autoinducer-independent N-terminally truncated form of LuxR, LuxR N, was used for in vitro studies . Single-round transcription assays were performed using reconstituted mutant RNAPs in the presence of LuxRN, and 14 alanine substitutions in the
CTD were identified as having negative effects on the rate of transcription from the lux operon promoter . Five of these 14
variants were also involved in the mechanisms of both LuxR- and LuxRN-dependent activation in vivo . The positions of these residues lie roughly within the 265 and 287 determinants in
that have been identified through studies of the cyclic AMP receptor protein and its interactions with RNAP . This suggests a model where residues 262, 265, and 296 in
play roles in DNA recognition and residues 290 and 314 play roles in
-LuxR interactions at the lux operon promoter during quorum sensing .
Analysis of Residues Determining Specificity of Vibrio cholerae TonB1 for Its Receptors. Alexandra R. Mey, 2003. Reverse Transcription-PCR Analysis of Bottled and Natural Mineral Waters for the Presence of Noroviruses. Gilbert Thierry Lamothe, 2003.A seminested reverse transcription-PCR method coupled to membrane filtration was optimized to investigate the presence of norovirus (NV) RNA sequences in bottled and natural mineral waters . The recovery of viral particles by filtration varied between 28 and 45%, while the limit of detection of the overall method ranged from 6 to 95 viral particles . The assay was broadly reactive, as shown by the successful detection of 27 different viral strains representing 12 common genotypes of NVs . A total of 718 bottled and natural mineral water samples were investigated, including 640 samples of finished, spring, and line products (mostly 1 to 1.5 liters), collected from 36 different water brands of various types and from diverse geographic origins over a 2-year period . In addition, 78 samples of larger volume (10 and 400 to 500 liters) and environmental swabs were investigated . From the 1,436 analyses that were performed for the detection of NVs belonging to genogroups I and II, 34 samples (2.44%) were presumptively positive by seminested RT-PCR . However, confirmation by DNA sequence analysis revealed that all presumptive positive results were either due to nonspecific amplification or to cross-contamination . In conclusion, these results do not provide any evidence for the presence of NV genome sequences in bottled waters .
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