scholarly journals Characterization of Recombinant Fluoroquinolone-Resistant Pneumococcus-Like Isolates

2012 ◽  
Vol 57 (1) ◽  
pp. 254-260 ◽  
Author(s):  
Luz Balsalobre ◽  
Montserrat Ortega ◽  
Adela G. de la Campa
Keyword(s):  
Recombinant Dna ◽  
Chromosomal Region ◽  
Split Decomposition ◽  
Dna Topoisomerase ◽  
Content Type ◽  
Streptococcus Oralis ◽  
Close Relationship ◽  
Phenotypic Tests ◽  
Resistant Pneumococcus

ABSTRACTFourteen fluoroquinolone-resistant streptococcal isolates with recombinant DNA topoisomerase genes, preliminarily identified as pneumococci, were further characterized using phenotypic and genotypic approaches. Phenotypic tests classified them as atypical pneumococci. Phylogenetic relationships were analyzed by using the sequences of seven housekeeping alleles from these isolates and from isolates ofStreptococcus pneumoniae,Streptococcus mitis,Streptococcus oralis, andStreptococcus pseudopneumoniae. Four isolates grouped withS. pneumoniae, seven grouped withS. pseudopneumoniae, and three grouped withS. mitis. These results generally agreed with those obtained with an optochin susceptibility test and with the organization of theatpoperon chromosomal region, encoding the FoF1H+-ATPase (the target of optochin). All seven isolates grouping withS. pseudopneumoniaeshare the samespr1368-atpC-atpAgene order; all four grouping withS. pneumoniaeshare thespr1368-IS1239-atpC-atpAorder, and two out of the three grouping withS. mitisshare thespr1284-atpC-atpAorder. In addition, evidence for recombination within the seven housekeeping alleles of theS. pseudopneumoniaepopulation was provided by several methods: the index of association (0.4598,P< 0.001), the pairwise homoplasy index, and the split-decomposition method. This study confirms the existence of pneumococci among the alpha-hemolytic streptococci with DNA topoisomerase genes showing a mosaic structure and reveals a close relationship between atypical pneumococci andS. pseudopneumoniae.

scholarly journals Comparative Structural and Molecular Characterization of Ribitol-5-Phosphate-Containing Streptococcus oralis Coaggregation Receptor Polysaccharides

2009 ◽  
Vol 191 (6) ◽  
pp. 1891-1900 ◽  
Author(s):  
Jinghua Yang ◽  
Mary Ritchey ◽  
Yasuo Yoshida ◽  
C. Allen Bush ◽  
John O. Cisar
Keyword(s):  
Dental Plaque ◽  
Molecular Basis ◽  
Capsular Polysaccharide ◽  
Polysaccharide Biosynthesis ◽  
Streptococcus Oralis ◽  
High Resolution Nmr ◽  
Close Relationship ◽  
Plaque Biofilm ◽  
Biofilm Community

ABSTRACT The antigenically related coaggregation receptor polysaccharides (RPS) of Streptococcus oralis strains C104 and SK144 mediate recognition of these bacteria by other members of the dental plaque biofilm community. In the present study, the structure of strain SK144 RPS was established by high resolution NMR spectroscopy as [6Galfβ1-6GalNAcβ1-3Galα1-2ribitol-5-PO4 −-6Galfβ1-3Galβ1]n, thereby indicating that this polysaccharide and the previously characterized RPS of strain C104 are identical, except for the linkage between Gal and ribitol-5-phosphate, which is α1-2 in strain SK144 versus α1-1 in strain C104. Studies to define the molecular basis of RPS structure revealed comparable genes for six putative transferases and a polymerase in the rps loci of these streptococci. Cell surface RPS production was abolished by disrupting the gene for the first transferase of strain C104 with a nonpolar erm cassette. It was restored in the resulting mutant by plasmid-based expression of either wcjG, the corresponding gene of S. pneumoniae for serotype 10A capsular polysaccharide (CPS) biosynthesis or wbaP for the transferase of Salmonella enterica that initiates O-polysaccharide biosynthesis. Thus, WcjG, like WbaP, appears to initiate polysaccharide biosynthesis by transferring galactose-1-phosphate to a lipid carrier. In further studies, the structure of strain C104 RPS was converted to that of strain SK144 by replacing the gene (wefM) for the fourth transferase in the rps locus of strain C104 with the corresponding gene (wcrC) of strain SK144 or Streptococcus pneumoniae serotype 10A. These findings identify genetic markers for the different ribitol-5-phosphate-containing types of RPS present in S. oralis and establish a close relationship between these polysaccharides and serogroup 10 CPSs of S. pneumoniae.

scholarly journals Characterization of a Newly Discovered Symbiont of the Whitefly Bemisia tabaci (Hemiptera: Aleyrodidae)

2012 ◽  
Vol 79 (2) ◽  
pp. 569-575 ◽  
Author(s):  
Xiao-Li Bing ◽  
Jiao Yang ◽  
Einat Zchori-Fein ◽  
Xiao-Wei Wang ◽  
Shu-Sheng Liu
Keyword(s):  
Cryptic Species ◽  
Bemisia Tabaci ◽  
Pcr Analysis ◽  
Human Pathogens ◽  
Wild Populations ◽  
Content Type ◽  
Close Relationship

ABSTRACTBemisia tabaci(Hemiptera: Aleyrodidae) is a species complex containing >28 cryptic species, some of which are important crop pests worldwide. Like many other sap-sucking insects, whiteflies harbor an obligatory symbiont, “CandidatusPortiera aleyrodidarum,” and a number of secondary symbionts. So far, six genera of secondary symbionts have been identified inB. tabaci. In this study, we report and describe the finding of an additional bacterium in the indigenousB. tabacicryptic species China 1 (formerly known asB. tabacibiotype ZHJ3). Phylogenetic analysis based on the 16S rRNA andgltAgenes showed that the bacterium belongs to theAlphaproteobacteriasubdivision of theProteobacteriaand has a close relationship with human pathogens of the genusOrientia. Consequently, we temporarily named itOrientia-like organism (OLO). OLO was found in six of eight wild populations ofB. tabaciChina 1, with the infection rate ranging from 46.2% to 76.8%. Fluorescencein situhybridization (FISH) ofB. tabaciChina 1 in nymphs and adults revealed that OLOs are confined to the bacteriome and co-occur with “Ca. Portiera aleyrodidarum.” The vertical transmission of OLO was demonstrated by detection of OLO at the anterior pole end of the oocytes through FISH. Quantitative PCR analysis of population dynamics suggested a complex interaction between “Ca. Portiera aleyrodidarum” and OLO. Based on these results, we propose “CandidatusHemipteriphilus asiaticus” for the classification of this symbiont fromB. tabaci.

scholarly journals Phenotypic and genomic characterization of pneumococcus-like streptococci isolated from HIV-seropositive patients

Microbiology ◽  
2010 ◽  
Vol 156 (3) ◽  
pp. 838-848 ◽  
Author(s):  
Truls M. Leegaard ◽  
Hester J. Bootsma ◽  
Dominique A. Caugant ◽  
Marc J. Eleveld ◽  
Turid Mannsåker ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Phenotypic Characterization ◽  
Comparative Genomic ◽  
Rrna Gene ◽  
Upper Respiratory Tract ◽  
Viridans Streptococci ◽  
Close Relationship ◽  
Phenotypic Tests ◽  
Hiv Seropositive

Accurate differentiation between pneumococci and other viridans streptococci is essential given their differences in clinical significance. However, classical phenotypic tests are often inconclusive, and many examples of atypical reactions have been reported. In this study, we applied various phenotypic and genotypic methods to discriminate between a collection of 12 streptococci isolated from the upper respiratory tract of HIV-seropositive individuals in 1998 and 1999. Conventional phenotypic characterization initially classified these streptococci as Streptococcus pneumoniae, as they were all sensitive to optochin and were all bile soluble. However, they did not agglutinate with anti-pneumococcal capsular antibodies and were also far more resistant to antimicrobial agents than typeable pneumococci isolated in the same period. Genotypic characterization of these isolates and control isolates by both multilocus sequence analysis (MLSA) and comparative genomic hybridization (CGH) showed that only a single isolate was genetically considered to be a true S. pneumoniae isolate, and that the remaining 11 non-typable isolates were indeed distinct from true pneumococci. Of these, 10 most closely resembled a subgroup of Streptococcus mitis isolates genetically, while one strain was identified as a Streptococcus pseudopneumoniae isolate. CGH also showed that a considerable part of the proposed pneumococcal core genome, including many of the known pneumococcal virulence factors, was conserved in the non-typable isolates. Sequencing of part of the 16S rRNA gene and investigation for the presence of ply by PCR corroborated these results. In conclusion, our findings confirm the close relationship between streptococci of the Mitis group, and show that both MLSA and CGH enable pneumococci to be distinguished from other Mitis group streptococci.

scholarly journals Characterization of an associated microfibril protein through recombinant DNA techniques.

1992 ◽  
Vol 267 (14) ◽  
pp. 10087-10095
Author(s):  
S.K. Horrigan ◽  
C.B. Rich ◽  
B.W. Streeten ◽  
Z.Y. Li ◽  
J.A. Foster
Keyword(s):  
Recombinant Dna ◽  
Recombinant Dna Techniques

scholarly journals The isolation and partial characterization of recombinant DNA containing genomic globin sequences from the goat.

1979 ◽  
Vol 254 (13) ◽  
pp. 6187-6195
Author(s):  
J Robbins ◽  
P Rosteck ◽  
J R Haynes ◽  
G Freyer ◽  
M L Cleary ◽  
...  
Keyword(s):  
Recombinant Dna ◽  
Partial Characterization

scholarly journals Characterization of RarA, a Novel AraC Family Multidrug Resistance Regulator in Klebsiella pneumoniae

2012 ◽  
Vol 56 (8) ◽  
pp. 4450-4458 ◽  
Author(s):  
Mark Veleba ◽  
Paul G. Higgins ◽  
Gerardo Gonzalez ◽  
Harald Seifert ◽  
Thamarai Schneiders
Keyword(s):  
Multidrug Resistance ◽  
Klebsiella Pneumoniae ◽  
Efflux Pump ◽  
Content Type ◽  
Resistance Phenotype ◽  
Serratia Proteamaculans ◽  
Virulence Potential ◽  
Article Type ◽  
Acrab Efflux Pump

ABSTRACTTranscriptional regulators, such as SoxS, RamA, MarA, and Rob, which upregulate the AcrAB efflux pump, have been shown to be associated with multidrug resistance in clinically relevant Gram-negative bacteria. In addition to the multidrug resistance phenotype, these regulators have also been shown to play a role in the cellular metabolism and possibly the virulence potential of microbial cells. As such, the increased expression of these proteins is likely to cause pleiotropic phenotypes.Klebsiella pneumoniaeis a major nosocomial pathogen which can express the SoxS, MarA, Rob, and RamA proteins, and the accompanying paper shows that the increased transcription oframAis associated with tigecycline resistance (M. Veleba and T. Schneiders, Antimicrob. Agents Chemother. 56:4466–4467, 2012). Bioinformatic analyses of the availableKlebsiellagenome sequences show that an additional AraC-type regulator is encoded chromosomally. In this work, we characterize this novel AraC-type regulator, hereby called RarA (Regulator of antibiotic resistance A), which is encoded inK. pneumoniae,Enterobactersp. 638,Serratia proteamaculans568, andEnterobacter cloacae. We show that the overexpression ofrarAresults in a multidrug resistance phenotype which requires a functional AcrAB efflux pump but is independent of the other AraC regulators. Quantitative real-time PCR experiments show thatrarA(MGH 78578 KPN_02968) and its neighboring efflux pump operonoqxAB(KPN_02969_02970) are consistently upregulated in clinical isolates collected from various geographical locations (Chile, Turkey, and Germany). Our results suggest thatrarAoverexpression upregulates theoqxABefflux pump. Additionally, it appears thatoqxR, encoding a GntR-type regulator adjacent to theoqxABoperon, is able to downregulate the expression of theoqxABefflux pump, where OqxR complementation resulted in reductions to olaquindox MICs.

scholarly journals Characterization of Glycoside Hydrolase Family 5 Proteins in Schizosaccharomyces pombe

2010 ◽  
Vol 9 (11) ◽  
pp. 1650-1660 ◽  
Author(s):  
Encarnación Dueñas-Santero ◽  
Ana Belén Martín-Cuadrado ◽  
Thierry Fontaine ◽  
Jean-Paul Latgé ◽  
Francisco del Rey ◽  
...  
Keyword(s):  
Cell Wall ◽  
Schizosaccharomyces Pombe ◽  
Protein Characterization ◽  
Wall Material ◽  
Glycoside Hydrolase Family ◽  
Content Type ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis ◽  
Hydrolase Family

ABSTRACT In yeast, enzymes with β-glucanase activity are thought to be necessary in morphogenetic events that require controlled hydrolysis of the cell wall. Comparison of the sequence of the Saccharomyces cerevisiae exo-β(1,3)-glucanase Exg1 with the Schizosaccharomyces pombe genome allowed the identification of three genes that were named exg1 + (locus SPBC1105.05), exg2 + (SPAC12B10.11), and exg3 + (SPBC2D10.05). The three proteins have different localizations: Exg1 is secreted to the periplasmic space, Exg2 is a membrane protein, and Exg3 is a cytoplasmic protein. Characterization of the biochemical activity of the proteins indicated that Exg1 and Exg3 are active only against β(1,6)-glucans while no activity was detected for Exg2. Interestingly, Exg1 cleaves the glucans with an endohydrolytic mode of action. exg1 + showed periodic expression during the cell cycle, with a maximum coinciding with the septation process, and its expression was dependent on the transcription factor Sep1. The Exg1 protein localizes to the septum region in a pattern that was different from that of the endo-β(1,3)-glucanase Eng1. Overexpression of Exg2 resulted in an increase in cell wall material at the poles and in the septum, but the putative catalytic activity of the protein was not required for this effect.

scholarly journals Characterization of T Cells Specific for CFP-10 and ESAT-6 in Mycobacterium tuberculosis-Infected Mauritian Cynomolgus Macaques

2017 ◽  
Vol 85 (4) ◽  
Author(s):  
Amy Ellis ◽  
Alexis Balgeman ◽  
Mark Rodgers ◽  
Cassaundra Updike ◽  
Jaime Tomko ◽  
...  
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
Mhc Class Ii ◽  
Nonhuman Primates ◽  
Content Type ◽  
Host Immune Responses ◽  
Cell Responses ◽  
Cynomolgus Macaques ◽  
Mhc Haplotype

ABSTRACT Nonhuman primates can be used to study host immune responses to Mycobacterium tuberculosis. Mauritian cynomolgus macaques (MCMs) are a unique group of animals that have limited major histocompatibility complex (MHC) genetic diversity, such that MHC-identical animals can be infected with M. tuberculosis. Two MCMs homozygous for the relatively common M1 MHC haplotype were bronchoscopically infected with 41 CFU of the M. tuberculosis Erdman strain. Four other MCMs, which had at least one copy of the M1 MHC haplotype, were infected with a lower dose of 3 CFU M. tuberculosis. All animals mounted similar T-cell responses to CFP-10 and ESAT-6. Two epitopes in CFP-10 were characterized, and the MHC class II alleles restricting them were determined. A third epitope in CFP-10 was identified but exhibited promiscuous restriction. The CFP-10 and ESAT-6 antigenic regions targeted by T cells in MCMs were comparable to those seen in cases of human M. tuberculosis infection. Our data lay the foundation for generating tetrameric molecules to study epitope-specific CD4 T cells in M. tuberculosis-infected MCMs, which may guide future testing of tuberculosis vaccines in nonhuman primates.

scholarly journals Analysis of the Functions of Recombination-Related Genes in the Generation of Large Chromosomal Deletions by Loop-Out Recombination in Aspergillus oryzae

2012 ◽  
Vol 11 (4) ◽  
pp. 507-517 ◽  
Author(s):  
Tadashi Takahashi ◽  
Masahiro Ogawa ◽  
Yasuji Koyama
Keyword(s):  
Aspergillus Oryzae ◽  
Chromosomal Region ◽  
Centromeric Region ◽  
Chromosome 8 ◽  
Telomeric Region ◽  
Dna Double Strand Breaks ◽  
Chromosomal Structure ◽  
Content Type ◽  
Strand Breaks ◽  
Chromosomal Deletions

ABSTRACT Loop-out-type recombination is a type of intrachromosomal recombination followed by the excision of a chromosomal region. The detailed mechanism underlying this recombination and the genes involved in loop-out recombination remain unknown. In the present study, we investigated the functions of ku70 , ligD , rad52 , rad54 , and rdh54 in the construction of large chromosomal deletions via loop-out recombination and the effect of the position of the targeted chromosomal region on the efficiency of loop-out recombination in Aspergillus oryzae . The efficiency of generation of large chromosomal deletions in the near-telomeric region of chromosome 3, including the aflatoxin gene cluster, was compared with that in the near-centromeric region of chromosome 8, including the tannase gene. In the Δ ku70 and Δ ku70-rdh54 strains, only precise loop-out recombination occurred in the near-telomeric region. In contrast, in the Δ ligD , Δ ku70-rad52 , and Δ ku70-rad54 strains, unintended chromosomal deletions by illegitimate loop-out recombination occurred in the near-telomeric region. In addition, large chromosomal deletions via loop-out recombination were efficiently achieved in the near-telomeric region, but barely achieved in the near-centromeric region, in the Δ ku70 strain. Induction of DNA double-strand breaks by I-SceI endonuclease facilitated large chromosomal deletions in the near-centromeric region. These results indicate that ligD , rad52 , and rad54 play a role in the generation of large chromosomal deletions via precise loop-out-type recombination in the near-telomeric region and that loop-out recombination between distant sites is restricted in the near-centromeric region by chromosomal structure.

scholarly journals Potentially Human-Pathogenic Escherichia coli O26 in Norwegian Sheep Flocks

2011 ◽  
Vol 77 (14) ◽  
pp. 4949-4958 ◽  
Author(s):  
C. Sekse ◽  
M. Sunde ◽  
B.-A. Lindstedt ◽  
P. Hopp ◽  
T. Bruheim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
Human Pathogens ◽  
Content Type ◽  
Representative Sampling ◽  
E Coli ◽  
Pathogenic Escherichia Coli ◽  
Close Relationship ◽  
Large Survey

ABSTRACTA national survey ofEscherichia coliO26 in Norwegian sheep flocks was conducted, using fecal samples to determine the prevalence. In total, 491 flocks were tested, andE. coliO26 was detected in 17.9% of the flocks. One hundred forty-twoE. coliO26 isolates were examined for flagellar antigens (H typing) and four virulence genes, includingstxandeae, to identify possible Shiga toxin-producingE. coli(STEC) and enteropathogenicE. coli(EPEC). Most isolates (129 out of 142) were identified asE. coliO26:H11. They possessedeaeand may have potential as human pathogens, although only a small fraction were identified as STEC O26:H11, giving a prevalence in sheep flocks of only 0.8%. Correspondingly, the sheep flock prevalence of atypical EPEC (aEPEC) O26:H11 was surprisingly high (15.9%). The genetic relationship between theE. coliO26:H11 isolates was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus variable number tandem repeat analysis (MLVA), identifying 63 distinct PFGE profiles and 22 MLVA profiles. Although the MLVA protocol was less discriminatory than PFGE and a few cases of disagreement were observed, comparison by partition mapping showed an overall good accordance between the two methods. A close relationship between a few isolates of aEPEC O26:H11 and STEC O26:H11 was identified, but all theE. coliO26:H11 isolates should be considered potentially pathogenic to humans. The present study consisted of a representative sampling of sheep flocks from all parts of Norway. This is the first large survey of sheep flocks focusing onE. coliO26 in general, including results of STEC, aEPEC, and nonpathogenic isolates.

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