bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diversity and Ubiquity of Bacteria Capable of Utilizing Humic Substances as Electron Donors for Anaerobic Respiration
Authors: Coates John D. , Cole Kimberly A. , Chakraborty Romy , O'Connor Susan M. , Achenbach Laurie A. 
Published: July 2002

ABSTRACT

Previous studies have demonstrated that reduced humic substances (HS) can be reoxidized by anaerobic bacteria such as
Geobacter
,
Geothrix
, and
Wolinella
species with a suitable electron acceptor; however, little is known of the importance of this metabolism in the environment. Recently we investigated this metabolism in a diversity of environments including marine and aquatic sediments, forest soils, and drainage ditch soils. Most-probable-number enumeration studies were performed using 2,6-anthrahydroquinone disulfonate (AHDS), an analog for reduced HS, as the electron donor with nitrate as the electron acceptor. Anaerobic organisms capable of utilizing reduced HS as an electron donor were found in all environments tested and ranged from a low of 2.31 × 10
1
in aquifer sediments to a high of 9.33 × 10
6
in lake sediments. As part of this study we isolated six novel organisms capable of anaerobic AHDS oxidation. All of the isolates coupled the oxidation of AHDS to the reduction of nitrate with acetate (0.1 mM) as the carbon source. In the absence of cells, no AHDS oxidation was apparent, and in the absence of AHDS, no cell density increase was observed. Generally, nitrate was reduced to N
2
. Analysis of the AHDS and its oxidized form, 2,6-anthraquinone disulfonate (AQDS), in the medium during growth revealed that the anthraquinone was not being biodegraded as a carbon source and was simply being oxidized as an energy source. Determination of the AHDS oxidized and nitrate reduced accounted for 109% of the theoretical electron transfer. In addition to AHDS, all of these isolates could also couple the oxidation of reduced humic substances to the reduction of nitrate. No HS oxidation occurred in the absence of cells and in the absence of a suitable electron acceptor, demonstrating that these organisms were capable of utilizing natural HS as an energy source and that AHDS serves as a suitable analog for studying this metabolism. Alternative electron donors included simple volatile fatty acids such as propionate, butyrate, and valerate as well as simple organic acids such as lactate and pyruvate. Analysis of the complete sequences of the 16S rRNA genes revealed that the isolates were not closely related to each other and were phylogenetically diverse, with members in the alpha, beta, gamma, and delta subdivisions of the
Proteobacteria
. Most of the isolates were closely related to known genera not previously recognized for their ability to couple growth to HS oxidation, while one of the isolates represented a new genus in the delta subclass of the
Proteobacteria
. The results presented here demonstrate that microbial oxidation of HS is a ubiquitous metabolism in the environment. This study represents the first description of HS-oxidizing isolates and demonstrates that microorganisms capable of HS oxidation are phylogenetically diverse.
Isolation and Metabolic Characteristics of Previously Uncultured Members of the Order
Aquificales
in a Subsurface Gold Mine
Authors: Takai Ken , Hirayama Hisako , Sakihama Yuri , Inagaki Fumio , Yamato Yu , Horikoshi Koki 
Published: July 2002

ABSTRACT

Culture-dependent and -independent techniques were combined to characterize the physiological properties and the ecological impacts of culture-resistant phylotypes of thermophiles within the order
Aquificales
from a subsurface hot aquifer of a Japanese gold mine. Thermophilic bacteria phylogenetically associated with previously uncultured phylotypes of
Aquificales
were successfully isolated. 16S ribosomal DNA clone analysis of the entire microbial DNA assemblage and fluorescence in situ whole-cell hybridization analysis indicated that the isolates dominated the microbial population in the subsurface aquifer. The isolates were facultatively anaerobic, hydrogen- or sulfur/thiosulfate-oxidizing, thermophilic chemolithoautotrophs utilizing molecular oxygen, nitrate, ferric iron, arsenate, selenate, and selenite as electron acceptors. Their versatile energy-generating systems may reflect the geochemical conditions of their habitat in the geothermally active subsurface gold mine.
Specificity and Prevalence of Natural Bovine Anti-Alpha Galactosyl (Galα1-6Glc or Galα1-6Gal) Antibodies
Authors: Ni Yawei , Powell Robert , Turner Debra D. , Tizard Ian 
Published: July 2002

ABSTRACTImmunity against the carbohydrate components of microorganisms mediated by antibodies is an important part of host defenses. Humans and closely related primates, but not other mammals, possess natural anti-Galα1-3Gal antibodies which also, although less avidly, react with melibiose (Galα1-6Glc). Using an enzyme-linked immunosorbent assay (ELISA) with melibiose-bovine serum albumin as an antigen, we analyzed bovine anti-alpha galactosyl antibodies with respect to specificity and distribution in individual animals. Inhibition assays showed that melibiose was the strongest inhibitor, followed equally by stachyose (Galα1-6Galα1-6Glcβ1-2Fru) and raffinose (Galα1-6Glcβ1-2Fru) and then by Galβ1-6Gal, Gal, and Galα1-2Gal. Others, including Galα1-3Gal and Galα1-4Gal, only exhibited minor inhibition. Thus, these bovine anti-alpha galactosyl antibodies appeared to preferentially react with Galα1-6Glc or Galα1-6Gal. The distinction of this specificity from that (Galα1-3Gal) of human antibodies was further demonstrated by the poor reaction of bovine serum to the Galα1-3Gal antigen in comparison to human serum. All 27 healthy bovine serum samples of the three age groups (newborn, calf, and adult) tested contained such antibodies with titers increasing with age. The antibodies purified by affinity chromatography using a melibiose-agarose column were mainly of the immunoglobulin G (IgG) isotype with a concentration of >23 μg/ml in most samples. IgG1 was found to be the primary antimelibiose IgG isotype in all age groups by isotype-specific ELISA, but a significant increase in IgG2, an isotype more related to innate immunity, was observed in calves and adults, compared to newborns. The purified antibodies reacted with the type II bovine strain ofStreptococcus agalactiae, a common pathogen of bovine mastitis. Thus, these anti-Galα1-6Glc or Galα1-6Gal antibodies in cattle might be involved in defense against microbes bearing this or the related epitopes.
Lack of Utility of Specific Immunoglobulin G Antibody Avidity for Serodiagnosis of Reactivated Toxoplasmosis in Immunocompromised Patients
Authors: Mechain Bénédicte , Garin Yves Jean-François , Robert-Gangneux Florence , Dupouy-Camet Jean , Derouin Francis 
Published: July 2002

ABSTRACTThe avidities ofToxoplasma-specific immunoglobulin G serum antibodies were measured in immunocompromised patients presenting with cerebral or extracerebral toxoplasmosis and/or serological reactivation. Since avidity remained high and stable in 39 of 40 patients with toxoplasmosis and 27 of 28 patients with serological reactivation, we conclude that this test cannot help diagnose toxoplasmosis in these patients.
The AIDA Autotransporter System Is Associated with F18 and Stx2e inEscherichia coliIsolates from Pigs Diagnosed with Edema Disease and Postweaning Diarrhea
Authors: Niewerth Ulla , Frey Andreas , Voss Thomas , Le Bouguénec Chantal , Baljer Georg , Franke Sylvia , Schmidt M. Alexander 
Published: July 2002

ABSTRACTPathogenicEscherichia colistrains are known to cause edema disease (ED) and postweaning diarrhea (PWD) in piglets. Although the exact mechanisms of pathogenicity that lead to ED-PWD remain to be elucidated,E. coli-borne Shiga-like toxin and adhesion-mediating virulence factors such as F18 adhesin or F4 fimbriae are believed to play a central role in ED-PWD. In light of these observations we investigated whether anotherE. coliadhesin, the plasmid-encoded AIDA (adhesin involved in diffuse adherence) might also be present in ED-PWD-causingE. coliisolates. For rapid screening for the AIDA system in large numbers of isolates, a multiplex PCR method along with a duplex Western blot procedure was developed. When screening 104 strains obtained from pigs with or without ED-PWD, we observed a high prevalence of the AIDA operon in porcineE. coliisolates, with over 25% of all strains being AIDA positive, and we could demonstrate a significant association of the intact AIDA gene (orfB) with ED-PWD, while defects inorfBwere associated with the absence of disease. Although our data hint toward a contribution of AIDA to ED-PWD, further studies will be necessary since the presence of the AIDA genes was also associated with the presence of the Shiga-like toxin and F18 adhesin genes, two reported virulence factors for ED-PWD.
Adherence ofGiardia lambliaTrophozoites to Int-407 Human Intestinal Cells
Authors: Céu Sousa M. , Gonçalves C. A. , Bairos V. A. , Poiares-da-Silva J. 
Published: July 2002

ABSTRACTAttachment ofGiardia lambliatrophozoites to enterocytes is essential for colonization of the small intestine and is considered a prerequisite for parasite-induced enterocyte dysfunction and clinical disease. In this work, coincubation ofGiardiawith Int-407 cells, was used as an in vitro model to study the role of cytoskeleton and surface lectins involved in the attachment of the parasite. This interaction was also studied by scanning and transmission electron microscopy. Adherence was dependent on temperature and was maximal at 37°C. It was reduced by 2.5 mM colchicine (57%), mebendazole (10 μg/ml) (59%), 100 mM glucose (26%), 100 mM mannose (22%), 40 mM mannose-6-phosphate (18%), and concanavalin A (100 μg/ml) (21%). No significant modification was observed whenGiardiawas pretreated with cytochalasins B and D and with EDTA.Giardiaattachment was also diminished by preincubating Int-407 cells with cytochalasin B and D (5 μg/ml) (16%) and by glutaraldehyde fixation of intestinal cells and ofG. lambliatrophozoites (72 and 100%, respectively). Ultrastructural studies showed thatGiardiaattaches to the Int-407 monolayer predominantly by its ventral surface. Int-407 cells contact trophozoites with elongated microvilli, and both trophozoite imprints and interactions ofGiardiaflagella with intestinal cells were also observed. Transmission electron microscopy showed thatGiardialateral crest and ventrolateral flange were important structures in the adherence process. Our results suggest a combination of mechanical and hydrodynamic forces in trophozoite attachment; surface lectins also seem to mediate binding and may be involved in specific recognition of host cells.
Use of Hoechst 33342 Staining To Detect Apoptotic Changes in Bovine Mononuclear Phagocytes Infected withMycobacterium aviumsubsp.paratuberculosis
Authors: Allen S. , Sotos J. , Sylte M. J. , Czuprynski C. J. 
Published: July 2002

ABSTRACTMycobacterium aviumsubsp.paratuberculosisis an intracellular pathogen of macrophages that causes a chronic enteritis (Johne's disease) in ruminants. The purpose of this study was to determine whetherM. aviumsubsp.paratuberculosisinfection causes apoptosis in bovine monocytes. Using Hoechst 33342 staining, we observed increased numbers of apoptotic monocytes within 6 h of infection withM. aviumsubsp.paratuberculosis, and these numbers increased further at 24 and 48 h. This effect appeared to require viable bacilli, because monocytes infected with heat-killedM. aviumsubsp.paratuberculosisdid not exhibit a significant increase in apoptosis. Preincubation of monocytes with bovine growth hormone prior to infection withM. aviumsubsp.paratuberculosisdid not significantly alter the number of apoptotic cells.
Enhanced Antigen-Specific Delayed-Type Hypersensitivity and Immunoglobulin G2b Responses after Oral Administration of ViableLactobacillus caseiYIT9029 in Wistar and Brown Norway Rats
Authors: de Waard R. , Garssen J. , Snel J. , Bokken G. C. A. M. , Sako T. , Huis in 't Veld J. H. J. , Vos J. G. 
Published: July 2002

ABSTRACTIn this study, the effects of orally administered viableLactobacillus caseiShirota strain YIT9029 on the immunity parameters of Wistar and Brown Norway rats were examined. For this purpose, we used theTrichinella spiralishost resistance model. Two weeks before and duringT. spiralisinfection, rats were fed 109viableL. caseibacteria 5 days per week. TheT. spiralis-specific delayed-type hypersensitivity (DTH) response was significantly enhanced in both Wistar and Brown Norway rats givenL. casei. In both rat strains fedL. casei, serumT. spiralis-specific immunoglobulin G2b (IgG2b) concentrations were also significantly increased. In the model, no significant effects ofL. caseion larval counts or inflammatory reactions in the tongue musculature, body weights, or lymphoid organ weights were observed. Serum specific antibody responses, other than IgG2b, were not changed by feeding ofL. casei. In contrast toL. casei, it was shown that orally administeredBifidobacterium breveorBifidobacterium bifidumhad no influence on the measured infection and immunity indices in the rat infection model. Since the rat DTH response is considered to be a manifestation of Th1 cell-mediated immunity and the IgG2b isotype has been associated with Th1 activity, it was concluded that Th1 cells could play an active role in the immunomodulatory effects of orally administeredL. casei. Furthermore, our data do not indicate that the effect of oral supplementation withL. caseiis dependent on the genetic background of the host.
Evaluation of Two Enzyme-Linked Immunosorbent Assays for DetectingSalmonella entericasubsp.entericaSerovar Dublin Antibodies in Bulk Milk
Authors: Veling J. , van Zijderveld F. G. , van Zijderveld-van Bemmel A. M. , Schukken Y. H. , Barkema H. W. 
Published: July 2002

ABSTRACTTwo enzyme-linked immunosorbent assays (ELISAs) for the detectingSalmonella entericasubsp. entericaserovar Dublin antibodies in bulk milk were developed and evaluated for potential use in control programs. The ELISAs were based on either lipopolysacharide (LPS ELISA) or flagellar antigen (GP ELISA). Sensitivity was determined with 79 case herds with a wide range of clinical signs. Specificity was determined with 125 Dutch and 200 Swedish control herds. The relation between antibodies in bulk milk, antibodies in serum, and the level of milk production of individual cows was studied with 61 case herds. The optimal optical density (OD) values of the LPS ELISA and the GP ELISA were determined to be 0.2 and 0.5, respectively. The sensitivities of the LPS ELISA and the GP ELISA were 54 and 63%, respectively, with a specificity of 98% for both ELISAs with samples from the Dutch control herds. The specificities for samples from the Swedish herds were 100% for the LPS ELISA and 95% for the GP ELISA. The sensitivity of the combination of tests was 65% when samples were run in parallel, and the specificity was 100% when samples were run in series, irrespective of whether the samples came from Dutch or Swedish control herds. The variance (R2) in the OD value for bulk milk samples could be explained by the percentage of seropositive lactating cows in a herd with the LPS ELISA for 51% of the samples and with the GP ELISA for 72%. The variance in the OD value was best explained by the combination of the percentage of seropositive lactating cows in the herd and the mean log10serum antibody titer for that herd (R2= 62% for the LPS ELISA andR2= 75% for the GP ELISA). Case herds more often tested negative by the ELISA with bulk milk when the percentage of seropositive lactating cows was less than 5%. It is concluded that both ELISAs with bulk milk can be used in control programs to distinguish between infected and noninfected herds. Specificity can be increased by using the two tests in combination. Sensitivity was relatively low for both single tests and both tests combined.
Diagnosis of Noncultivatable Gastroenteritis Viruses, the Human Caliciviruses
Authors: Atmar Robert L. , Estes Mary K. 
Published: July 2002

SUMMARY
Gastroenteritis is one of the most common illnesses of humans, and many different viruses have been causally associated with this disease. Of those enteric viruses that have been established as etiologic agents of gastroenteritis, only the human caliciviruses cannot be cultivated in vitro. The cloning of Norwalk virus and subsequently of other human caliciviruses has led to the development of several new diagnostic assays. Antigen detection enzyme immunoassays (EIAs) using polyclonal hyperimmune animal sera and antibody detection EIAs using recombinant virus-like particles have supplanted the use of human-derived reagents, but the use of these assays has been restricted to research laboratories. Reverse transcription-PCR assays for the detection of human caliciviruses are more widely available, and these assays have been used to identify virus in clinical specimens as well as in food, water, and other environmental samples. The application of these newer assays has significantly increased the recognition of the importance of human caliciviruses as causes of sporadic and outbreak-associated gastroenteritis.
αvβ3Integrin and Bacterial Lipopolysaccharide Are Involved inCoxiella burnetii-Stimulated Production of Tumor Necrosis Factor by Human Monocytes
Authors: Dellacasagrande Jérôme , Ghigo Eric , Machergui-El Sarah , Hammami  , Toman Rudolf , Raoult Didier , Capo Christian , Mege Jean-Louis 
Published: July 2002

ABSTRACTCoxiella burnetii, the agent of Q fever, enters human monocytes through αvβ3integrin and survives inside host cells. In addition,C. burnetiistimulates the synthesis of inflammatory cytokines including tumor necrosis factor (TNF) by monocytes. We studied the role of the interaction ofC. burnetiiwith THP-1 monocytes in TNF production. TNF transcripts and TNF release reached maximum values within 4 h. Almost all monocytes boundC. burnetiiafter 4 h, while the percentage of phagocytosing monocytes did not exceed 20%. Cytochalasin D, which prevented the uptake ofC. burnetiiwithout interfering with its binding, did not affect the expression of TNF mRNA. Thus, bacterial adherence, but not phagocytosis, is necessary for TNF production by monocytes. The monocyte αvβ3integrin was involved in TNF synthesis since peptides containing RGD sequences and blocking antibodies against αvβ3integrin inhibited TNF transcripts induced byC. burnetii. Nevertheless, the cross-linking of αvβ3integrin by specific antibodies was not sufficient to induce TNF synthesis. The signal delivered byC. burnetiiwas triggered by bacterial lipopolysaccharide (LPS). Polymyxin B inhibited the TNF production stimulated byC. burnetii, and soluble LPS isolated fromC. burnetiilargely mimicked viable bacteria. On the other hand, avirulent variants ofC. burnetiiinduced TNF production through an increased binding to monocytes rather than through the potency of their LPS. We suggest that the adherence ofC. burnetiito monocytes via αvβ3integrin enables surface LPS to stimulate TNF production in THP-1 monocytes.
Analysis of Cytadherence-Deficient, GapA-Negative
Mycoplasma gallisepticum
Strain R
Authors: Papazisi L. , Troy K. E. , Gorton T. S. , Liao X. , Geary S. J. 
Published: July 2002

ABSTRACT

Comparison of the phenotypic expression of
Mycoplasma gallisepticum
strain R low (passage 15) to that of strain R high (passage 164) revealed that three proteins, i.e., the cytadhesin molecule GapA, a 116-kDa protein (p116), and a 45-kDa protein (p45), are missing in strain R high. Sequence analysis confirmed that the insertion of an adenine 105 bp downstream of the
gapA
translational start codon resulted in premature termination of translation in R high. A second adenine insertion had also occurred at position 907. Restoration of expression of wild-type
gapA
in R high (clone designated GT5) allowed us to evaluate the extent to which the diminished cytadherence capacity could be attributed to GapA alone. The results indicated that GT5 attached to the same limited extent as the parental R high, from which it was derived. The cytadherence capability of the parental R high was not restored solely by
gapA
complementation alone, indicating that either p116 or p45 or both may play a role in the overall cytadherence process. The gene encoding p116 was found to be immediately downstream of
gapA
in the same operon and was designated
crmA
. This gene exhibited striking homology to genes encoding molecules with cytadhesin-related functions in both
Mycoplasma pneumoniae
and
Mycoplasma genitalium
. Transcriptional analysis revealed that
crmA
is not transcribed in R high. We are currently constructing a shuttle vector containing both the wild-type
gapA
and
crmA
for transformation into R high to assess the role of CrmA in the cytadherence process.
Cytotoxic Activity of Coagulase-Negative Staphylococci in Bovine Mastitis
Authors: Zhang Songlin , Maddox Carol W. 
Published: July 2002

ABSTRACTSecreted toxins play important roles in the pathogenesis of bacterial infections. In this study, we examined the presence of secreted cytotoxic factors of coagulase-negative staphylococci (CoNS) from bovine clinical and subclinical mastitis. A 34- to 36-kDa protein with cell-rounding cytotoxic activity was found in many CoNS strains, especially inStaphylococcus chromogenesstrains. The protein caused cell detachment and cell rounding in several cell lines, including HEp-2, Int 407, CHO-K1, and Y-1 cells. Native protein recovered from nondenatured polyacrylamide gel electrophoresis showed both cytotoxic activity and casein hydrolysis activity. The purified protein had a pH optimal at 7.2 to 7.5 and a pI of 5.1 and was heat labile. The proteolytic activity could be inhibited by zinc and metal specific inhibitors such as 1,10-phenanthroline and EDTA, indicating that it is a metalloprotease. Protein mass analysis and peptide sequencing indicated that the protein is a novel metalloprotease. Different bacterial strains expressed variable levels of 34- to 36-kDa protease, which may provide an indication of strain virulence.