bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of Symbiotic Clostridia in the Mixed Segment of the Termite
Nasutitermes takasagoensis
(Shiraki)
Authors: Tokuda Gaku , Yamaoka Ikuo , Noda Hiroaki 
Published: July 2002

ABSTRACT

Phylogeny and the distribution of symbiotic bacteria in the mixed segment of the wood-eating termite
Nasutitermes takasagoensis
(Shiraki) were studied. Bacterial 16S rRNA genes (rDNA) were amplified from the mixed segment of the gut by PCR, and two kinds of sequences were identified. The phylogenetic tree was constructed by neighbor-joining and maximum parsimony methods to identify symbionts harbored in the mixed segment. They are classified as low-G+C-content gram-positive bacteria and are most closely related to the genus
Clostridium
. The distribution of these bacteria throughout the whole gut was examined by PCR using specific primers, which suggested that they are confined to the mixed segment despite the presence of bacteria throughout the gut. In situ hybridization indicated that the symbiotic bacteria were localized to the ectoperitrophic space between the midgut wall and the peritrophic membrane in the mixed segment. Electron microscopy revealed the close association between these bacteria and the mesenteric epithelium, suggesting that they have some interactions with the gut tissue of termites.
Deletion of Various Carboxy-Terminal Domains of
Lactococcus lactis
SK11 Proteinase: Effects on Activity, Specificity, and Stability of the Truncated Enzyme
Authors: Bruinenberg Paul G. , De Vos Willem M. , Siezen Roland J. 
Published: July 2002

ABSTRACT

The
Lactococcus lactis
SK11 cell envelope proteinase is an extracellular, multidomain protein of nearly 2,000 residues consisting of an N-terminal serine protease domain, followed by various other domains of largely unknown function. Using a strategy of deletion mutagenesis, we have analyzed the function of several C-terminal domains of the SK11 proteinase which are absent in cell envelope proteinases of other lactic acid bacteria. The various deletion mutants were functionally expressed in
L. lactis
and analyzed for enzyme stability, activity, (auto)processing, and specificity toward several substrates. C-terminal deletions of first the cell envelope W (wall) and AN (anchor) domains and then the H (helix) domain leads to fully active, secreted proteinases of unaltered specificity. Gradually increasing the C-terminal deletion into the so-called B domain leads to increasing instability and autoproteolysis and progressively less proteolytic activity. However, the mutant with the largest deletion (838 residues) from the C terminus and lacking the entire B domain still retains proteolytic activity. All truncated enzymes show unaltered proteolytic specificity toward various substrates. This suggests that the main role played by these domains is providing stability or protection from autoproteolysis (B domain), spacing away from the cell (H domain), and anchoring to the cell envelope (W and AN domains). In addition, this study allowed us to more precisely map the main C-terminal autoprocessing site of the SK11 proteinase and the epitope for binding of group IV monoclonal antibodies.
Diversity of Thiosulfate-Oxidizing Bacteria from Marine Sediments and Hydrothermal Vents
Authors: Teske A. , Brinkhoff T. , Muyzer G. , Moser D. P. , Rethmeier J. , Jannasch H. W. 
Published: July 2002

ABSTRACT

Species diversity, phylogenetic affiliations, and environmental occurrence patterns of thiosulfate-oxidizing marine bacteria were investigated by using new isolates from serially diluted continental slope and deep-sea abyssal plain sediments collected off the coast of New England and strains cultured previously from Galapagos hydrothermal vent samples. The most frequently obtained new isolates, mostly from 10
3
- and 10
4
-fold dilutions of the continental slope sediment, oxidized thiosulfate to sulfate and fell into a distinct phylogenetic cluster of marine alpha-
Proteobacteria
. Phylogenetically and physiologically, these sediment strains resembled the sulfate-producing thiosulfate oxidizers from the Galapagos hydrothermal vents while showing habitat-related differences in growth temperature, rate and extent of thiosulfate utilization, and carbon substrate patterns. The abyssal deep-sea sediments yielded predominantly base-producing thiosulfate-oxidizing isolates related to Antarctic marine
Psychroflexus
species and other cold-water marine strains of the
Cytophaga-Flavobacterium-Bacteroides
phylum, in addition to gamma-proteobacterial isolates of the genera
Pseudoalteromonas
and
Halomonas-Deleya
. Bacterial thiosulfate oxidation is found in a wide phylogenetic spectrum of
Flavobacteria
and
Proteobacteria
.
marY1
, a Member of the
gypsy
Group of Long Terminal Repeat Retroelements from the Ectomycorrhizal Basidiomycete
Tricholoma matsutake
Authors: Murata Hitoshi , Yamada Akiyoshi 
Published: July 2002

ABSTRACT

We cloned an intact copy of a long terminal repeat retroelement designated
marY1
from the ectomycorrhizal basidiomycete
Tricholoma matsutake
. The reverse transcriptase domain is found in
T. matsutake
and
Tricholoma magnivelare
worldwide. This finding suggests that retroelements associate with ectomycorrhizal basidiomycetes and may be useful as genetic markers for identification, phylogenetic analysis, and mutagenesis of this fungal group.
Pyrosequencing as a Method for Grouping of
Listeria monocytogenes
Strains on the Basis of Single-Nucleotide Polymorphisms in the
inlB
Gene
Authors: Unnerstad Helle , Ericsson Henrik , Alderborn Anders , Tham Wilhelm , Danielsson-Tham Marie-Louise , Mattsson Jens G. 
Published: July 2002

ABSTRACT

By using pyrosequencing (i.e., sequencing by synthesis) 106 strains of different serovars of
Listeria monocytogenes
were rapidly grouped into four categories based on nucleotide variations at positions 1575 and 1578 of the
inlB
gene. Strains of serovars 1/2a and 1/2c constituted one group, and strains of serovars 1/2b and 3b constituted another group, whereas serovar 4b strains were separated into two groups.
Development of a Reverse Transcription-PCR–DNA Enzyme Immunoassay for Detection of “Norwalk-Like” Viruses and Hepatitis A Virus in Stool and Shellfish
Authors: Schwab Kellogg J. , Neill Frederick H. , Le Guyader Françoise , Estes Mary K. , Atmar Robert L. 
Published: July 2002

ABSTRACT

Outbreaks of food- and waterborne gastroenteritis are being increasingly reported throughout the world. The analysis of environmental samples by newer diagnostic techniques such as reverse transcription-PCR (RT-PCR) amplification of nucleic acid has begun to identify human enteric viruses (predominantly “Norwalk-like” viruses [NLVs]) as the cause of many of these outbreaks. To streamline NLV detection from environmental samples such as shellfish, we have developed an RT-PCR–oligoprobe amplification and detection method using several new procedures that enable confirmed RT-PCR amplification and product detection in 1 day. The new steps include replacing reverse transcriptase and
Taq
polymerase with r
Tth
polymerase, a heat-stable enzyme that functions as both a reverse transcriptase and DNA polymerase, in a single-tube, single-buffer, elevated temperature reaction. An internal standard Norwalk virus (NV) RNA control is added to each RT-PCR to identify sample inhibition, and thermolabile uracil
N
-glycosylase is incorporated into the reaction to prevent PCR product carryover contamination. Finally, RT-PCR-generated amplicons are detected in microtiter wells using virus-specific biotinylated oligoprobes in an enzyme-linked immunosorbent assay-based format. The DNA enzyme immunoassay is based on the capture of PCR product by biotinylated probes fixed onto individual streptavidin-coated wells. Using this method, low levels of NV were detected in stool and both NLV and hepatitis A virus were detected in bivalve mollusks following bioaccumulation. The method also successfully detected NLV in oysters implicated in an outbreak of NLV gastroenteritis. This method dramatically decreases the time needed for analysis and is amenable to automation.
Transposon Mutagenesis in Purple Sulfur Photosynthetic Bacteria: Identification of
hypF
, Encoding a Protein Capable of Processing [NiFe] Hydrogenases in α, β, and γ Subdivisions of the Proteobacteria
Authors: Fodor Barna , Rákhely Gábor , Kovács Ákos T. , Kovács Kornél L. 
Published: July 2002

ABSTRACT

A random transposon-based mutagenesis system was optimized for the purple sulfur phototrophic bacterium
Thiocapsa roseopersicina
BBS. Screening for hydrogenase-deficient phenotypes resulted in the isolation of six independent mutants in a mini-Tn
5
library. One of the mutations was in a gene showing high amino acid sequence similarity to HypF proteins in other organisms. Inactivation of hydrogen uptake activity in the
hypF
-deficient mutant resulted in a dramatic increase in the hydrogen evolution capacity of
T. roseopersicina
under nitrogen-fixing conditions. This mutant is therefore a promising candidate for use in practical biohydrogen-producing systems. The reconstructed
hypF
gene was able to complement the
hypF
-deficient mutant of
T. roseopersicina
BBS. Heterologous complementation experiments, using
hypF
mutant strains of
T. roseopersicina
,
Escherichia coli
, and
Ralstonia eutropha
and various
hypF
genes, were performed. They were successful in all of the cases tested, although for
E. coli
, the regulatory region of the foreign gene had to be replaced in order to achieve partial complementation. RT-PCR data suggested that HypF has no effect on the transcriptional regulation of the structural genes of hydrogenases in this organism.
Degradation of Chlorinated Dibenzofurans and Dibenzo-
p
-Dioxins by Two Types of Bacteria Having Angular Dioxygenases with Different Features
Authors: Habe Hiroshi , Chung Jin-Sung , Lee Jong-Hoon , Kasuga Kano , Yoshida Takako , Nojiri Hideaki , Omori Toshio 
Published: July 2002

ABSTRACT

Two kinds of bacteria having different-structured angular dioxygenases—a dibenzofuran (DF)-utilizing bacterium,
Terrabacter
sp. strain DBF63, and a carbazole (CAR)-utilizing bacterium,
Pseudomonas
sp. strain CA10—were investigated for their ability to degrade some chlorinated dibenzofurans (CDFs) and chlorinated dibenzo-
p
-dioxins (CDDs) (or, together, CDF/Ds) using either wild-type strains or recombinant
Escherichia coli
strains. First, it was shown that CAR 1,9a-dioxygenase (CARDO) catalyzed angular dioxygenation of all mono- to triCDF/Ds investigated in this study, but DF 4,4a-dioxygenase (DFDO) did not degrade 2,7-diCDD. Secondly, degradation of CDF/Ds by the sets of three enzymes (angular dioxygenase, extradiol dioxygenase, and
meta
-cleavage compound hydrolase) was examined, showing that these enzymes in both strains were able to convert 2-CDF to 5-chlorosalicylic acid but not other tested substrates to the corresponding chlorosalicylic acid (CSA) or chlorocatechol (CC). Finally, we tested the potential of both wild-type strains for cooxidation of CDF/Ds and demonstrated that both strains degraded 2-CDF, 2-CDD, and 2,3-diCDD to the corresponding CSA and CC. We investigated the sites for the attack of angular dioxygenases in each CDF/D congener, suggesting the possibility that the angular dioxygenation of 2-CDF, 2-CDD, 2,3-diCDD, and 1,2,3-triCDD (10 ppm each) by both DFDO and CARDO occurred mainly on the nonsubstituted aromatic nuclei.
Induction of a Mitosis Delay and Cell Lysis by High-Level Secretion of Mouse α-Amylase from
Saccharomyces cerevisiae
Authors: Wang Bi-Dar , Kuo Tsong-Teh 
Published: July 2002

ABSTRACT

Some foreign proteins are produced in yeast in a cell cycle-dependent manner, but the cause of the cell cycle dependency is unknown. In this study, we found that
Saccharomyces cerevisiae
cells secreting high levels of mouse α-amylase have elongated buds and are delayed in cell cycle completion in mitosis. The delayed cell mitosis suggests that critical events during exit from mitosis might be disturbed. We found that the activities of PP2A (protein phosphatase 2A) and MPF (maturation-promoting factor) were reduced in α-amylase-oversecreting cells and that these cells showed a reduced level of assembly checkpoint protein Cdc55, compared to the accumulation in wild-type cells. MPF inactivation is due to inhibitory phosphorylation on Cdc28, as a
cdc28
mutant which lacks an inhibitory phosphorylation site on Cdc28 prevents MPF inactivation and prevents the defective bud morphology induced by overproduction of α-amylase. Our data also suggest that high levels of α-amylase may downregulate
PPH22,
leading to cell lysis. In conclusion, overproduction of heterologous α-amylase in
S. cerevisiae
results in a negative regulation of PP2A, which causes mitotic delay and leads to cell lysis.
New Immunofluorescence Assays for Detection of
Human Herpesvirus 8
-Specific Antibodies
Authors: Inoue Naoki , Mar Eng-Chun , Dollard Sheila C. , Pau Chou-Pong , Zheng Qi , Pellett Philip E. 
Published: July 2002

ABSTRACT

Several assays have been developed for detection of immunoglobulin G antibodies to
Human herpesvirus 8
(HHV-8), including immunofluorescence assays (IFAs) and enzyme-linked immunosorbent assays (ELISAs). However, the specificity and sensitivity of these assays are not completely defined due to the lack of a “gold standard.” Although IFAs based on primary effusion lymphoma (PEL) cell lines are used widely, the assays can be confounded by nonspecific reactions against cellular components and potential cross-reaction with antibodies against other herpesviruses. To provide more reliable IFAs, we established recombinant Semliki Forest viruses (rSFVs) expressing the HHV-8-specific proteins ORF73 and K8.1 and used BHK-21 cells infected with these rSFVs for IFA (ORF73-IFA and K8.1-IFA). Expression of the HHV-8-specific proteins at very high levels by the rSFV system allowed easy scoring for IFA and thereby increased specificity. The rSFV system also allowed detection of antibodies against glycosylation-dependent epitopes of K8.1. Titers measured by rSFV-based IFAs and PEL-based IFAs correlated well (correlation coefficients of >0.9), and concordances of seroreactivities between rSFV-based and PEL-based IFAs were >97% (κ > 0.93). K8.1-IFA was more sensitive than either ORF73-IFA or peptide ELISAs. Using PEL-based lytic IFA as a reference assay, the sensitivity and specificity of K8.1-IFA were estimated to be 94 and 100%, respectively. HHV-8 prevalences determined by K8.1-IFA among the human immunodeficiency virus (HIV)-positive (HIV
+
) Kaposi's sarcoma (KS) patients, HIV
+
KS
−
patients, and healthy controls were 100, 65, and 6.7%, respectively, which were consistent with prior reports. Therefore, our rSFV-based IFAs may provide a specific and sensitive method for use in epidemiology studies. In addition, they will provide a basis for further development of diagnostic tests for HHV-8 infection.
Effects of Androgen Treatment on Expression of Macrophage Fcγ Receptors
Authors: Gomez F. , Ruiz P. , Lopez R. , Rivera C. , Romero S. , Bernal J. A. 
Published: July 2002

ABSTRACTMacrophage Fcγ receptors (FcγRs) play an important role in the host defense against infection and in the pathophysiology of immune cytopenias. Modulation of macrophage FcγR expression is a potential therapeutic approach to immune disorders. Glucocorticoids and progesterones decrease macrophage FcγR expression. We assessed the effect of treatment with androgens and antiandrogens on the expression of macrophage FcγRs using an experimental guinea pig model. Four androgens (testosterone, dihydrotestosterone, mesterolone, and danazol) and five antiandrogens (flutamide, nilutamide, cyproterone acetate, spironolactone, and finasteride) were studied. Following in vivo treatment of guinea pigs, we determined the clearance of immunoglobulin G (IgG)-sensitized erythrocytes in vivo, the binding of IgG-sensitized erythrocytes by isolated splenic macrophages, and splenic macrophage FcγR cell surface expression. All of the androgens impaired the clearance of IgG-sensitized erythrocytes by decreasing splenic macrophage FcγR expression. Dihydrotestosterone and mesterolone were more effective than testosterone or dihydrotestosterone. Flow cytometry and fluorescence microscopy with monoclonal antibodies demonstrated that the androgens decreased the cell surface expression of FcγR1,2 more than that of FcγR2. Antiandrogens did not significantly alter macrophage FcγR expression. Nevertheless, antiandrogens counteracted the effects of androgens on macrophage FcγR expression. These data indicate that androgens impair the clearance of IgG-coated cells by decreasing splenic macrophage FcγR expression. Thus, androgens other than danazol are candidate drugs for the treatment of immune disorders.
Decreased Levels of CD54 (ICAM-1)-Positive Lymphocytes in the Peripheral Blood in Untreated Patients with Active Juvenile Dermatomyositis
Authors: O'Gorman Maurice R. G. , Bianchi Laura , Zaas David , Corrochano Virginia , Pachman Lauren M. 
Published: July 2002

ABSTRACTSignificant abnormalities are observed in the peripheral blood of juvenile dermatomyositis (JDM) patients with active disease. In this study, we confirm that there is a significant increase in the relative percentage of B lymphocytes in the peripheral blood of a group of untreated children with newly diagnosed active JDM compared to healthy children (P< 0.0001). In order to investigate if properties intrinsic to B cells contributed to their relative increase in JDM, the percentage of B cells expressing activation markers (CD23, CD25, CD54, and CD69) was measured and compared to pediatric controls. Compared to healthy children less than 10 years of age (not significantly different from the JDM group), the JDM patients had an increase in the proportion of lymphocytes expressing CD19 (B cells;P= 0.0017) and decreases in the percentage of lymphocytes that were CD3−CD16+and/or CD56+(NK cells;P= 0.01) and CD3+CD8+(T suppressor/cytotoxic cells;P= 0.02). There were no significant differences in any of the B-cell activation markers assessed. Of note, the percentage of CD54+non-B lymphocytes (i.e., T cells and NK cells expressing CD54) was significantly lower in the JDM patients (25% ± 5%) than in the “age-related” healthy control group (43% ± 4%;P= 0.013). These results suggest the following for untreated children with active JDM: (i) the increase in the percentage of peripheral blood B cells is not due to intrinsic B-cell activation, and (ii) CD54/ICAM-1+non-B cells, CD8+T cells, and NK cells are being removed from circulation and may be participating in the pathophysiology of the disease.
Up-Regulation of CD40 Ligand and Induction of a Th2 Response in Children Immunized with Pneumococcal Polysaccharide Vaccines
Authors: Leiva Lily E. , Butler Boyd , Hempe James , Ortigas Alejandro P. , Sorensen Ricardo U. 
Published: July 2002

ABSTRACTWe wished to determine whether pneumococcal polysaccharide antigens induce mRNA expression of CD40 ligand (CD40L) and Th1 or Th2 cytokines in unimmunized individuals in vitro and whether immunization with the 23-valent pneumococcal polysaccharide vaccine induces changes in CD40L and cytokine mRNA expression. Children with recurrent respiratory infections were studied before and 4 to 6 weeks after receiving the pneumococcal vaccine. One patient who failed to respond to the polysacharide vaccine subsequently received a single dose of the experimental 7-valent pneumococcal conjugate vaccine. Unimmunized healthy adults were included as controls. Quantification of mRNA expression of CD40L, interleukin-4 (IL-4), IL-12p40, and gamma interferon (IFN-γ) was performed by reverse transcription-PCR and enzyme-linked immunosorbent assay (ELISA)-PCR with resting and stimulated peripheral blood mononuclear cells. Serum immunoglobulin G (IgG) anti pneumococcal antibody levels were measured by ELISA. The results showed a significant increase in the expression of mRNAs for CD40L and IL-4, but not IL-12p40 or IFN-γ, in stimulated cultures from unimmunized individuals. CD40L and IL-4 mRNA expression was significantly higher in postimmunization than in preimmunization samples stimulated with the individual pneumococcal serotypes. These results suggest that pneumococcal polysaccharide antigens specifically up-regulate CD40L expression and induce a Th2 response in vitro which parallels the increase in IgG antipneumococcal antibody levels in serum.
Immunity to MurineChlamydia trachomatisGenital Tract Reinfection Involves B Cells and CD4+T Cells but Not CD8+T Cells
Authors: Morrison Sandra G. , Su Hua , Caldwell Harlan D. , Morrison Richard P. 
Published: July 2002

ABSTRACTCD4+T-helper type 1 (Th1) responses are essential for the resolution of a primaryChlamydia trachomatisgenital tract infection; however, elements of the immune response that function in resistance to reinfection are poorly understood. Defining the mechanisms of immune resistance to reinfection is important because the elements of protective adaptive immunity are distinguished by immunological memory and high-affinity antigen recognition, both of which are crucial to the development of efficacious vaccines. Using in vivo antibody depletion of CD4+and CD8+T cells prior to secondary intravaginal challenge, we identified lymphocyte populations that functioned in resistance to secondary chlamydial infection of the genital tract. Depletion of either CD4+or CD8+T cells in immune wild-type C57BL/6 mice had a limited effect on resistance to reinfection. However, depletion of CD4+T cells, but not CD8+T cells, in immune B-cell-deficient mice profoundly altered the course of secondary infection. CD4-depleted B-cell-deficient mice were unable to resolve a secondary infection, shed high levels of infectious chlamydiae, and did not resolve the infection until 3 to 4 weeks following the discontinuation of anti-CD4 treatment. These findings substantiated a predominant role for CD4+T cells in host resistance to chlamydial reinfection of the female genital tract and demonstrated that CD8+T cells are unnecessary for adaptive immune resistance. More importantly, however, this study establishes a previously unrecognized but very significant role for B cells in resistance to chlamydial reinfection and suggests that B cells and CD4+T cells may function synergistically in providing immunity in this model of chlamydial infection. Whether CD4+T cells and B cells function independently or dependently is unknown, but definition of those mechanisms is fundamental to understanding optimum protective immunity and to the development of highly efficacious immunotherapies against chlamydial urogenital infections.
Complement Activation inMycoplasma fermentans-Induced Mycoplasma Clearance from Infected Cells: Probing of the Organism with Monoclonal Antibodies against M161Ag
Authors: Kikkawa Satomi , Matsumoto Misako , Sasaki Tsuguo , Nishiguchi Miyuki , Tanaka Kazuhiko , Toyoshima Kumao , Seya Tsukasa 
Published: July 2002

ABSTRACTMycoplasma fermentans, a cell wall-less prokaryote, is capable of infecting humans and has been suggested to serve as a cofactor in AIDS development. Recently, we discovered a novel lipoprotein with a molecular mass of 43 kDa originating fromM. fermentans. This protein, named M161Ag, activated human complement via the alternative pathway and efficiently induced the proinflammatory cytokines interleukin 1β (IL-1β), tumor necrosis factor alpha, IL-6, IL-10, and IL-12 in human peripheral blood monocytes. It is likely that M161Ag ofM. fermentansaffects the host immune system upon mycoplasma infection. In this study, we developed monoclonal antibodies (MAbs) against M161Ag and examined the direct role of complement inM. fermentansinfection using these MAbs as probes.M. fermentanswas rapidly cleared from the surfaces of infected cells by human complement, but a low-grade infection persisted in human tumor cell lines. Mycoplasma particles remaining alive in host cells may cause recurrent infection, and liberated M161Ag may serve as a biological response modifier affecting both innate and acquired immunity.