bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secondary (γ-
Proteobacteria
) Endosymbionts Infect the Primary (β-
Proteobacteria
) Endosymbionts of Mealybugs Multiple Times and Coevolve with Their Hosts
Authors: Thao MyLo Ly , Gullan Penny J. , Baumann Paul 
Published: July 2002

ABSTRACT

Mealybugs (Hemiptera, Coccoidea, Pseudococcidae) are plant sap-sucking insects that have within their body cavities specialized cells containing prokaryotic primary endosymbionts (P-endosymbionts). The P-endosymbionts have the unusual property of containing within their cytoplasm prokaryotic secondary endosymbionts (S-endosymbionts) [C. D. von Dohlen, S. Kohler, S. T. Alsop, and W. R. McManus, Nature (London) 412:433-436, 2001]. Four-kilobase fragments containing 16S-23S ribosomal DNA (rDNA) were obtained from the P-endosymbionts of 22 mealybug species and the S-endosymbionts of 12 representative species. Phylogenetic analyses of the P-endosymbionts indicated that they have a monophyletic origin and are members of the β-subdivision of the
Proteobacteria
; these organisms were subdivided into five different clusters. The S-endosymbionts were members of the γ-subdivision of the
Proteobacteria
and were grouped into clusters similar to those observed with the P-endosymbionts. The S-endosymbiont clusters were distinct from each other and from other insect-associated bacteria. The similarity of the clusters formed by the P- and S-endosymbionts suggests that the P-endosymbionts of mealybugs were infected multiple times with different precursors of the S-endosymbionts and once the association was established, the P- and S-endosymbionts were transmitted together. The lineage consisting of the P-endosymbionts of mealybugs was given the designation “
Candidatus
Tremblaya” gen. nov., with a single species, “
Candidatus
Tremblaya princeps” sp. nov. The results of phylogenetic analyses of mitochondrial DNA fragments encoding cytochrome oxidase subunits I and II from four representative mealybug species were in agreement with the results of 16S-23S rDNA analyses, suggesting that relationships among strains of “
Candidatus
T. princeps” are useful in inferring the phylogeny of their mealybug hosts.
Phage-Displayed Peptides as Developmental Agonists for
Phytophthora capsici
Zoospores
Authors: Bishop-Hurley Sharon L. , Mounter Sarah A. , Laskey James , Morris Roy O. , Elder Jim , Roop Philip , Rouse Chris , Schmidt Francis J. , English James T. 
Published: July 2002

ABSTRACT

As part of its pathogenic life cycle,
Phytophthora capsici
disperses to plants through a motile zoospore stage. Molecules on the zoospore surface are involved in reception of environmental signals that direct preinfection behavior. We developed a phage display protocol to identify peptides that bind to the surface molecules of
P. capsici
zoospores in vitro
.
The selected phage-displayed peptides contained an abundance of polar amino acids and proline but were otherwise not conserved. About half of the selected phage that were tested concomitantly induced zoospore encystment in the absence of other signaling agents. A display phage was shown to bind to the zoospore but not to the cyst form of
P. capsici.
Two free peptides corresponding to active phage were similarly able to induce encystment of zoospores, indicating that their ability to serve as signaling ligands did not depend on their exact molecular context. Isolation and subsequent expression of peptides that act on pathogens could allow the identification of receptor molecules on the zoospore surface, in addition to forming the basis for a novel plant disease resistance strategy.
Genotypic and Phenotypic Diversity within Species of Purple Nonsulfur Bacteria Isolated from Aquatic Sediments
Authors: Oda Yasuhiro , Wanders Wouter , Huisman Louis A. , Meijer Wim G. , Gottschal Jan C. , Forney Larry J. 
Published: July 2002

ABSTRACT

To assess the extent of genotypic and phenotypic diversity within species of purple nonsulfur bacteria found in aquatic sediments, a total of 128 strains were directly isolated from agar plates that had been inoculated with sediment samples from Haren and De Biesbosch in The Netherlands. All isolates were initially characterized by BOX-PCR genomic DNA fingerprinting, and 60 distinct genotypes were identified. Analyses of 16S rRNA gene sequences of representatives of each genotype showed that five and eight different phylotypes of purple nonsulfur bacteria were obtained from the Haren and De Biesbosch sites, respectively. At the Haren site, 80.5% of the clones were
Rhodopseudomonas palustris
, whereas
Rhodoferax fermentans
and
Rhodopseudomonas palustris
were numerically dominant at the De Biesbosch site and constituted 45.9 and 34.4% of the isolates obtained, respectively. BOX-PCR genomic fingerprints showed that there was a high level of genotypic diversity within each of these species. The genomic fingerprints of
Rhodopseudomonas palustris
isolates were significantly different for isolates from the two sampling sites, suggesting that certain strains may be endemic to each sampling site. Not all
Rhodopseudomonas palustris
isolates could degrade benzoate, a feature that has previously been thought to be characteristic of the species. There were differences in the BOX-PCR genomic fingerprints and restriction fragment length polymorphisms of benzoate-coenzyme A ligase genes and form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) genes between benzoate-degrading and non-benzoate-degrading genotypes. The ability to distinguish these two
Rhodopseudomonas palustris
groups based on multiple genetic differences may reflect an incipient speciation event resulting from adaptive evolution to local environmental conditions.
Influence of the Transposition of the Thermostabilizing Domain of
Clostridium thermocellum
Xylanase (XynX) on Xylan Binding and Thermostabilization
Authors: Shin Eun-Sun , Yang Mi-Jeong , Jung Kyung Hwa , Kwon Eun-Ju , Jung Jae Sung , Park Seur Kee , Kim Jungho , Yun Han Dae , Kim Hoon 
Published: July 2002

ABSTRACT

A xylanase gene,
xynX
, of
Clostridium thermocellum
had one thermostabilizing domain (TSD) between the signal peptide sequence and the catalytic domain (CD). The TSD of a truncated xylanase gene,
xynX
′
TSD-CD
, was transpositioned from the N terminus to the C terminus of the CD by overlapping PCRs, and a modified product,
xynX
′
CD-TSD
, was constructed. XynX′
TSD-CD
had a higher optimum temperature (70°C versus 65°C) and was more thermostable (residual activity of 68% versus 46% after a 20-min preincubation at 70°C) than the one without the TSD, XynX′
CD
. However, the domain-transpositioned enzyme, XynX′
CD-TSD
, showed a lower optimum temperature (30°C) and thermostability (20%) than XynX′
CD
. Both XynX′
TSD-CD
and XynX′
CD-TSD
showed significantly higher binding capacity toward xylan than XynX′
CD
, and the domain transposition did not cause any change in the binding ability. XynX′
TSD-CD
and XynX′
CD-TSD
also showed considerable binding to lichenan but not to carboxymethyl cellulose and laminarin. XynX′
TSD-CD
and XynX′
CD-TSD
had higher activities for insoluble xylan than XynX′
CD
, while XynX′
CD
was more active against soluble xylan than XynX′
TSD-CD
and XynX′
CD-TSD
. These results indicate that the TSD of XynX has dual functions, xylan binding and thermostabilization, and the domain should also be classified as a xylan-binding domain (XBD). The binding capacity of the XBD was not affected by domain transpositioning within the gene.
Biodegradation of 1,2,3-Trichloropropane through Directed Evolution and Heterologous Expression of a Haloalkane Dehalogenase Gene
Authors: Bosma Tjibbe , Damborský Jirí , Stucki Gerhard , Janssen Dick B. 
Published: July 2002

ABSTRACTUsing a combined strategy of random mutagenesis of haloalkane dehalogenase and genetic engineering of a chloropropanol-utilizing bacterium, we constructed an organism that is capable of growth on 1,2,3-trichloropropane (TCP). This highly toxic and recalcitrant compound is a waste product generated from the manufacture of the industrial chemical epichlorohydrin. Attempts to select and enrich bacterial cultures that can degrade TCP from environmental samples have repeatedly been unsuccessful, prohibiting the development of a biological process for groundwater treatment. The critical step in the aerobic degradation of TCP is the initial dehalogenation to 2,3-dichloro-1-propanol. We used random mutagenesis and screening on eosin-methylene blue agar plates to improve the activity on TCP of the haloalkane dehalogenase fromRhodococcussp. m15-3 (DhaA). A second-generation mutant containing two amino acid substitutions, Cys176Tyr and Tyr273Phe, was nearly eight times more efficient in dehalogenating TCP than wild-type dehalogenase. Molecular modeling of the mutant dehalogenase indicated that the Cys176Tyr mutation has a global effect on the active-site structure, allowing a more productive binding of TCP within the active site, which was further fine tuned by Tyr273Phe. The evolved haloalkane dehalogenase was expressed under control of a constitutive promoter in the 2,3-dichloro-1-propanol-utilizing bacteriumAgrobacterium radiobacterAD1, and the resulting strain was able to utilize TCP as the sole carbon and energy source. These results demonstrated that directed evolution of a key catabolic enzyme and its subsequent recruitment by a suitable host organism can be used for the construction of bacteria for the degradation of a toxic and environmentally recalcitrant chemical.
Differentiation of
Paenibacillus larvae
subsp.
larvae
, the Cause of American Foulbrood of Honeybees, by Using PCR and Restriction Fragment Analysis of Genes Encoding 16S rRNA
Authors: Alippi Adriana M. , López Ana Claudia , Aguilar O. Mario 
Published: July 2002

ABSTRACT

A rapid procedure for the identification of
Paenibacillus larvae
subsp.
larvae
, the causal agent of American foulbrood (AFB) disease of honeybees (
Apis mellifera
L.), based on PCR and restriction fragment analysis of the 16S rRNA genes (rDNA) is described. Eighty-six bacterial strains belonging to 39 species of the genera
Paenibacillus
,
Bacillus
,
Brevibacillus
, and
Virgibacillus
were characterized. Amplified rDNA was digested with seven restriction endonucleases. The combined data from restriction analysis enabled us to distinguish 35 profiles. Cluster analysis revealed that
P. larvae
subsp.
larvae
and
Paenibacillus larvae
subsp.
pulvifaciens
formed a group with about 90% similarity; however, the
P. larvae
subsp.
larvae
restriction fragment length polymorphism pattern produced by endonuclease
Hae
III was found to be unique and distinguishable among other closely related bacteria. This pattern was associated with DNA extracted directly from honeybee brood samples showing positive AFB clinical signs that yielded the restriction profile characteristic of
P. larvae
subsp.
larvae
, while no amplification product was obtained from healthy larvae. The method described here is particularly useful because of the short time required to carry it out and because it allows the differentiation of
P. larvae
subsp.
larvae
-infected larvae from all other species found in apiarian sources.
Value of Microimmunofluorescence for Diagnosis and Follow-up of
Bartonella
Endocarditis
Authors: Fournier Pierre-Edouard , Mainardi Jean-Luc , Raoult Didier 
Published: July 2002

ABSTRACT

Bartonella
endocarditis is a disease of emerging importance that causes serious complications and high rates of mortality. Due to the fastidious nature of
Bartonella
species and their high degrees of antibiotic susceptibility, cultures of clinical samples most often remain sterile and valvular biopsy specimens, the best specimens for PCR amplification, are seldom available. Therefore, serology appears to be the easiest diagnostic tool. In order to determine the best cutoff value for serology and its predictive values for the detection of
Bartonella
endocarditis, we studied 48 patients with culture- and/or PCR-confirmed
Bartonella
endocarditis. We also applied these serological criteria to 156 patients with blood culture-negative endocarditis. Furthermore, we compared the kinetics of the antibody responses to
Bartonella
spp. in order to estimate the value of serology for prediction of the occurrence of relapses. A titer of ≥1:800 for immunoglobulin G antibodies to either
Bartonella henselae
or
B. quintana
has a positive predictive value of 0.810 for the detection of chronic
Bartonella
infections in the general population and a value of 0.955 for the detection of
Bartonella
infections among patients with endocarditis. When this cutoff was applied to 156 patients with blood culture-negative endocarditis, we were able to diagnose
Bartonella
infections in an additional 45 patients with definite endocarditis for whom a positive
Bartonella
serology was the only evidence of infection. On follow-up, the kinetics of the decrease in antibody titers were significantly delayed in two patients with relapses. In conclusion, we recommend the determination of antibodies to both
B. quintana
and
B. henselae
and the use of a cutoff value of 1:800 for the diagnosis of
Bartonella
endocarditis. We propose that this criterion, which may also help with the detection of late relapses, be included as a major criterion in the Duke criteria for the diagnosis of infective endocarditis.
MaGiK Method of T-Cell Receptor Repertoire Analysis
Authors: Killian M. Scott , Matud Jose , Detels Roger , Giorgi Janis V. , Jamieson Beth D. 
Published: July 2002

ABSTRACT
T-cell receptor diversity enables the cellular immune response to recognize a broad range of viral and other pathogenic agents. An increasingly common method of characterizing T-cell receptor diversity and usage in response to antigenic challenges involves the identification of clonal expansions by PCR amplification of the CDR3 region of distinct TCRVβ families. Though clonal expansions often appear evident upon visual inspection of the results, a systematic method is needed for the valid enumeration of these expansions. Here, we describe a novel analysis method, termed the MaGiK method, for systematically identifying and enumerating clonal T-cell expansions and for applying the results to investigations of the T-cell receptor repertoire.
Induction of Cytokines by Glucosyltransferases ofStreptococcus mutans
Authors: Chia Jean-San , Lien Huei-Ting , Hsueh Po-Ren , Chen Pei-Min , Sun Andy , Chen Jen-Yang 
Published: July 2002

ABSTRACTProduction of proinflammatory cytokines is implicated in the pathogenesis of viridans streptococcus-induced α-streptococcal shock syndrome and infective endocarditis.Streptococcus mutans, one of the opportunistic pathogens causing infective endocarditis, was reported previously to stimulate monocytes and epithelial and endothelial cells in vitro to produce various cytokines. We found that glucosyltransferases (GTFs) GtfC and GtfD ofS. mutansstimulated predominantly the production of interleukin-6 (IL-6) from T cells cultured in vitro. The level of IL-6 but not of tumor necrosis factor alpha in blood was significantly elevated when rats were injected intravenously withS. mutansGS-5, whereas IL-6 was detected at a much lower level when rats were challenged with NHS1DD, an isogenic mutant defective in the expression of GTFs. The serum IL-6 level was elevated in patients with endocarditis caused by different species of viridans streptococci which express GTF homologues. Affinity column-purified GTFs reduced the levels of detectable IL-2 of T cells stimulated by another bacterial antigen, tetanus toxoid. These results suggested that GTFs might modulate the production of Th1-type cytokines and that GTFs ofS. mutansplay a significant role in stimulating the production of the proinflammatory cytokine IL-6 in vivo.
Complement-Mediated Neutralization of Canine Distemper Virus In Vitro: Cross-Reaction between Vaccine Onderstepoort and Field KDK-1 Strains with Different Hemagglutinin Gene Characteristics
Authors: Mochizuki Masami , Motoyoshi Megumi , Maeda Ken , Kai Kazunari 
Published: July 2002

ABSTRACTThe properties of neutralization of antigens of canine distemper virus Onderstepoort and a recent field isolate, KDK-1, were investigated with strain-specific dog sera. A conventional neutralization assay indicated antigenic dissimilarity between the strains; however, when guinea pig complement was included in the reaction mixture, the strains were neutralized with not only the homologous but also the heterologous antibodies.
Manipulations in Maternal Environment Reverse Periodontitis in Genetically Predisposed Rats
Authors: Sluyter Frans , Breivik Torbjørn , Cools Alexander 
Published: July 2002

ABSTRACTThe predisposition to develop periodontitis is partly genetically determined in humans as well as in animals. Here we demonstrate, however, that early manipulations in the maternal environment of an animal (rat) model of periodontitis can fully reverse the genetic predisposition to develop periodontitis at adult age.
Leukotriene B4Induces Nitric Oxide Synthesis inTrypanosoma cruzi-Infected Murine Macrophages and Mediates Resistance to Infection
Authors: Talvani A. , Machado F. S. , Santana G. C. , Klein A. , Barcelos L. , Silva J. S. , Teixeira M. M. 
Published: July 2002

ABSTRACTThe production of nitric oxide (NO) by gamma interferon (IFN-γ)-activated macrophages is a major effector mechanism during experimentalTrypanosoma cruziinfection. In addition to IFN-γ, chemoattractant molecules, such as platelet-activating factor (PAF) and CC chemokines, may also activate macrophages to induce NO and mediate the killing ofT. cruziin an NO-dependent manner. Here we investigated the ability of leukotriene B4(LTB4) to induce the production of NO by macrophages infected withT. cruziin vitro and whether NO mediated LTB4-induced parasite killing. The activation ofT. cruzi-infected but not naive murine peritoneal macrophages with LTB4induced the time- and concentration-dependent production of NO. In addition, low concentrations of LTB4acted in synergy with IFN-γ to induce NO production. The NO produced mediated LTB4-induced microbicidal activity in macrophages, as demonstrated by the inhibitory effects of an inducible NO synthase inhibitor. LTB4-induced NO production and parasite killing were LTB4receptor dependent and were partially blocked by a PAF receptor antagonist. LTB4also induced significant tumor necrosis factor alpha (TNF-α) production, and blockade of TNF-α suppressed LTB4-induced NO release and parasite killing. A blockade of LTB4or PAF receptors partially inhibited IFN-γ-induced NO and TNF-α production but not parasite killing. Finally, daily treatment of infected mice with CP-105,696 was accompanied by a significantly higher level of blood parasitemia, but not lethality, than that seen in vehicle-treated animals. In conclusion, our results suggest a role for LTB4during experimentalT. cruziinfection. Chemoattractant molecules such as LTB4not only may play a major role in leukocyte migration into sites of inflammation in vivo but also, in the event of an infection, may play a relevant role in the activation of recruited leukocytes to kill the invading microorganism in an NO-dependent manner.
FimbriatedSalmonella entericaSerovar Typhimurium Abates Initial Inflammatory Responses by Macrophages
Authors: Pascual David W. , Trunkle Theresa , Sura Jamie 
Published: July 2002

ABSTRACTOral immunization of mice with aSalmonellavaccine expressing colonization factor antigen I (CFA/I) from enterotoxigenicEscherichia coliresults in the rapid onset of interleukin-4 (IL-4) and IL-5 production, which explains the observed elevations in mucosal immunoglobulin A (IgA) and serum IgG1 antibodies. In contrast, oral immunization with theSalmonellavector does not result in the production of Th2-type cytokines. To begin to assess why such differences exist between the two strains, it should be noted that in vitro infection of RAW 264.7 macrophages resulted in the absence of nitric oxide (NO) production in cells infected with theSalmonella-CFA/I vaccine. This observation suggests differential proinflammatory cytokine production by these isogenicSalmonellastrains. Upon measurement of proinflammatory cytokines, minimal to no tumor necrosis factor alpha (TNF-α), IL-1α, IL-1β, or IL-6 was produced bySalmonella-CFA/I-infected RAW 264.7 or peritoneal macrophages, but production was greatly induced inSalmonellavector-infected macrophages. Only minute levels of IL-12 p70 were induced bySalmonellavector-infected macrophages, and none was induced bySalmonella-CFA/I-infected macrophages. The absence of IL-12 was not due to overt increases in production of either IL-12 p40 or IL-10. CFU measurements taken at 8 h postinfection showed no differences in colonization in RAW 264.7 cells infected with eitherSalmonellaconstruct, but there were differences in peritoneal macrophages. However, after 24 h, theSalmonellavector strain colonized to a greater extent in RAW 264.7 cells than in peritoneal macrophages. Infection of RAW 264.7 cells or peritoneal macrophages with eitherSalmonellaconstruct showed no difference in macrophage viabilities. This evidence shows that the expression of CFA/I fimbriae alters how macrophages recognize or process salmonellae and prevents the rapid onset of proinflammatory cytokines which is typical duringSalmonellainfections.
One of Two Copies of the Gene for the Activatable Shiga Toxin Type 2d in
Escherichia coli
O91:H21 Strain B2F1 Is Associated with an Inducible Bacteriophage
Authors: Teel Louise D. , Melton-Celsa Angela R. , Schmitt Clare K. , O'Brien Alison D. 
Published: July 2002

ABSTRACT

Shiga toxin (Stx) types 1 and 2 are encoded within intact or defective temperate bacteriophages in Stx-producing
Escherichia coli
(STEC), and expression of these toxins is linked to bacteriophage induction. Among Stx2 variants, only
stx
2e
from one human STEC isolate has been reported to be carried within a toxin-converting phage. In this study, we examined the O91:H21 STEC isolate B2F1, which carries two functional alleles for the potent activatable Stx2 variant toxin, Stx2d, for the presence of Stx2d-converting bacteriophages. We first constructed mutants of B2F1 that produced one or the other Stx2d toxin and found that the mutant that produced only Stx2d1 made less toxin than the Stx2d2-producing mutant. Consistent with that result, the Stx2d1-producing mutant was attenuated in a streptomycin-treated mouse model of STEC infection. When the mutants were treated with mitomycin C to promote bacteriophage induction, Vero cell cytotoxicity was elevated only in extracts of the Stx2d1-producing mutant. Additionally, when mice were treated with ciprofloxacin, an antibiotic that induces the O157:H7 Stx2-converting phage, the animals were more susceptible to the Stx2d1-producing mutant. Moreover, an
stx
2d1
-containing lysogen was isolated from plaques on strain DH5α that had been exposed to lysates of the mutant that produced Stx2d1 only, and supernatants from that lysogen transformed with a plasmid encoding RecA were cytotoxic when the lysogen was induced with mitomycin C. Finally, electron-microscopic examination of extracts from the Stx2d1-producing mutant showed hexagonal particles that resemble the prototypic Stx2-converting phage 933W. Together these observations provide strong evidence that expression of Stx2d1 is bacteriophage associated. We conclude that despite the sequence similarity of the
stx
2d1
- and
stx
2d2
-flanking regions in B2F1, Stx2d1 expression is repressed within the context of its toxin-converting phage while Stx2d2 expression is independent of phage induction.