bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal Variation and Indirect Monitoring of Microcystin Concentrations in Daechung Reservoir, Korea
Authors: Oh Hee-Mock , Lee Seog June , Kim Jee-Hwan , Kim Hee-Sik , Yoon Byung-Dae
Published: July 2002

Physicochemical and biological water quality, including the microcystin concentration, was investigated from spring to autumn 1999 in the Daechung Reservoir, Korea. The dominant genus in the cyanobacterial blooming season wasMicrocystis. The microcystin concentration in particulate form increased dramatically from August up to a level of 200 ng liter−1in early October and thereafter tended to decrease. The microcystin concentration in dissolved form was about 28% of that of the particulate form. The microcystins detected using a protein phosphatase (PP) inhibition assay were highly correlated with those microcystins detected by a high-performance liquid chromatograph (r= 0.973;P< 0.01). Therefore, the effectiveness of a PP inhibition assay for microcystin detection in a high number of water samples was confirmed as easy, quick, and convenient. The microcystin concentration was highly correlated with the phytoplankton number (r= 0.650;P< 0.01) and chlorophyll-aconcentration (r= 0.591;P< 0.01). When the microcystin concentration exceeded about 100 ng liter−1, the ratio of particulate to dissolved total nitrogen (TN) or total phosphorus (TP) converged at a value of 0.6. Furthermore, the microcystin concentration was lower than 50 ng liter−1at a particulate N/P ratio below 8, whereas the microcystin concentration varied quite substantially from 50 to 240 ng liter−1at a particulate N/P ratio of >8. Therefore, it seems that the microcystin concentration in water can be estimated and indirectly monitored by analyzing the following: the phytoplankton number and chlorophyll-aconcentration, the ratio of the particulate and the dissolved forms of N and P, and the particulate N/P ratio when the dominant genus is toxigenicMicrocystis.
Characterization of a Novel Type II Restriction-Modification System,
Sth
368I, Encoded by the Integrative Element ICE
St1
of
Streptococcus thermophilus
CNRZ368
Authors: Burrus Vincent , Bontemps Cyril , Decaris Bernard , Guédon Gérard
Published: July 2002

A novel type II restriction and modification (R-M) system,
Sth
368I, which confers resistance to φST84, was found in
Streptococcus thermophilus
CNRZ368 but not in the very closely related strain A054. Partial sequencing of the integrative conjugative element ICE
St1,
carried by
S. thermophilus
CNRZ368 but not by A054, revealed a divergent cluster of two genes,
sth368IR
and
sth368IM
. The protein sequence encoded by
sth368IR
is related to the type II endonucleases R.
Lla
KR2I and R.
Sau
3AI, which recognize and cleave the sequence 5′-GATC-3′. The protein sequence encoded by
sth368IM
is very similar to numerous type II 5-methylcytosine methyltransferases, including M.
Lla
KR2I and M.
Sau
3AI. Cell extracts of CNRZ368 but not A054 were found to cleave at the GATC site. Furthermore, the C residue of the sequence 5′-GATC-3′ was found to be methylated in CNRZ368 but not in A054. Cloning and integration of a copy of
sth368IR
and
sth368IM
in the A054 chromosome confers on this strain phenotypes similar to those of CNRZ368, i.e., phage resistance, endonuclease activity of cell extracts, and methylation of the sequence 5′-GATC-3′. Disruption of
sth368IR
removes resistance and restriction activity. We conclude that ICE
St1
encodes an R-M system,
Sth
368I, which recognizes the sequence 5′-GATC-3′ and is related to the
Sau
3AI and
Lla
KR2I restriction systems.
Genomic Interspecies Microarray Hybridization: Rapid Discovery of Three Thousand Genes in the Maize Endophyte,
Klebsiella pneumoniae
342, by Microarray Hybridization with
Escherichia coli
K-12 Open Reading Frames
Authors: Dong Yuemei , Glasner Jeremy D. , Blattner Frederick R. , Triplett Eric W.
Published: July 2002

In an effort to efficiently discover genes in the diazotrophic endophyte of maize,
Klebsiella pneumoniae
342, DNA from strain 342 was hybridized to a microarray containing 96% (
n
= 4,098) of the annotated open reading frames from
Escherichia coli
K-12. Using a criterion of 55% identity or greater, 3,000 (70%) of the
E. coli
K-12 open reading frames were also found to be present in strain 342. Approximately 24% (
n
= 1,030) of the
E. coli
K-12 open reading frames are absent in strain 342. For 1.6% (
n
= 68) of the open reading frames, the signal was too low to make a determination regarding the presence or absence of the gene. Genes with high identity between the two organisms are those involved in energy metabolism, amino acid metabolism, fatty acid metabolism, cofactor synthesis, cell division, DNA replication, transcription, translation, transport, and regulatory proteins. Functions that were less highly conserved included carbon compound metabolism, membrane proteins, structural proteins, putative transport proteins, cell processes such as adaptation and protection, and central intermediary metabolism. Open reading frames of
E. coli
K-12 with little or no identity in strain 342 included putative regulatory proteins, putative chaperones, surface structure proteins, mobility proteins, putative enzymes, hypothetical proteins, and proteins of unknown function, as well as genes presumed to have been acquired by lateral transfer from sources such as phage, plasmids, or transposons. The results were in agreement with the physiological properties of the two strains. Whole genome comparisons by genomic interspecies microarray hybridization are shown to rapidly identify thousands of genes in a previously uncharacterized bacterial genome provided that the genome of a close relative has been fully sequenced. This approach will become increasingly more useful as more full genome sequences become available.
Characterization of the 450-kb Linear Plasmid in a Polychlorinated Biphenyl Degrader,
Rhodococcus
sp. Strain RHA1
Authors: Shimizu Satoru , Kobayashi Hiroyuki , Masai Eiji , Fukuda Masao
Published: July 2002

A strong polychlorinated biphenyl (PCB) degrader,
Rhodococcus
sp. strain RHA1, has diverse biphenyl/PCB degradative genes and harbors huge linear plasmids, including pRHL1 (1,100 kb), pRHL2 (450 kb), and pRHL3 (330 kb). The diverse degradative genes are distributed mainly on the pRHL1 and pRHL2 plasmids. In this study, the structural and functional characteristics of pRHL2 were determined. We constructed a physical map of pRHL2, and the degradative enzyme genes, including
bphB2, etbD2, etbC, bphDEF, bphC2
, and
bphC4
, were localized in three regions. Conjugal transfer of pRHL2 between RHA1 mutant derivatives was observed at a frequency of 7.5 × 10
−5
transconjugant per recipient. These results suggested that the linear plasmid is a possible determinant of propagation of the diverse degradative genes in rhodococci. The termini of pRHL2 were cloned and sequenced. The left and right termini of pRHL2 had 3-bp perfect terminal inverted repeats and were not as similar to each other (64% identity) as the known actinomycete linear replicons are. Southern hybridization analysis with pRHL2 terminal probes suggested that the right terminus of pRHL2 is similar to pRHL1 and pRHL3 termini. Retardation of both terminal fragments in the gel shift assay indicated that each terminus of pRHL2 is linked to a protein. We suggest that pRHL2 has invertron termini, as has been reported previously for
Streptomyces
linear replicons.
Purification ofSynechocystissp. Strain PCC6308 Cyanophycin Synthetase and Its Characterization with Respect to Substrate and Primer Specificity
Authors: Aboulmagd Elsayed , Oppermann-Sanio Fred B. , Steinbüchel Alexander
Published: July 2002

Synechocystissp. strain PCC6308 cyanophycin synthetase was purified 72-fold in three steps by anion exchange chromatography on Q Sepharose, affinity chromatography on the triazine dye matrix Procion Blue HE-RD Sepharose, and gel filtration on Superdex 200 HR from recombinant cells ofEscherichia coli.The native enzyme, which catalyzed the incorporation of arginine and aspartic acid into cyanophycin, has an apparent molecular mass of 240 ± 30 kDa and consists of identical subunits of 85 ± 5 kDa. TheKmvalues for arginine (49 μM), aspartic acid (0.45 mM), and ATP (0.20 mM) indicated that the enzyme had a high affinity towards these substrates. During in vitro cyanophycin synthesis, 1.3 ± 0.1 mol of ATP per mol of incorporated amino acid was converted to ADP. The optima for the enzyme-catalyzed reactions were pH 8.2 and 50°C, respectively. Arginine methyl ester (99.5 and 97% inhibition), argininamide (99 and 96%), S-(2-aminoethyl) cysteine (43 and 42%), β-hydroxy aspartic acid (35 and 37%), aspartic acid β-methyl ester (38 and 40%), norvaline (0 and 3%), citrulline (9 and 7%), and asparagine (2 and 0%) exhibited an almost equal inhibitory effect on the incorporation of both arginine and aspartic acid, respectively, when these compounds were added to the complete reaction mixture. In contrast, the incorporation of arginine was diminished to a greater extent than that of aspartic acid, respectively, with canavanine (82 and 53%), lysine (36 and 19%), agmatine (33 and 25%),d-aspartic acid (37 and 30%),l-glutamic acid (13 and 5%), and ornithine (23 and 11%). On the other hand, canavanine (45% of maximum activity) and lysine (13%) stimulated the incorporation of aspartic acid, whereas aspartic acid β-methyl ester (53%) and asparagine (9%) stimulated the incorporation of arginine. [3H]lysine (15% of maximum activity) and [3H]canavanine (13%) were incorporated into the polymer, when they were either used instead of arginine or added to the complete reaction mixture, whereasl-glutamic acid was not incorporated. No effect on arginine incorporation was obtained by the addition of other amino acids (i.e., alanine, histidine, leucine, proline, tryptophan, and glycine). Various samples of chemically synthesized poly-α,β-d,l-aspartic acid served as primers for in vitro synthesis of cyanophycin, whereas poly-α-l-aspartic acid was almost inactive.
Changes in Activity and Community Structure of Methane-Oxidizing Bacteria over the Growth Period of Rice
Authors: Eller Gundula , Frenzel Peter
Published: July 2002

The activity and community structure of methanotrophs in compartmented microcosms were investigated over the growth period of rice plants. In situ methane oxidation was important only during the vegetative growth phase of the plants and later became negligible. The in situ activity was not directly correlated with methanotrophic cell counts, which increased even after the decrease in in situ activity, possibly due to the presence of both vegetative cells and resting stages. By dividing the microcosms into two soil and two root compartments it was possible to locate methanotrophic growth and activity, which was greatest in the rhizoplane of the rice plants. Molecular analysis by denaturing gradient gel electrophoresis and fluorescent in situ hybridization (FISH) with family-specific probes revealed the presence of both families of methanotrophs in soil and root compartments over the whole season. Changes in community structure were detected only for members of the
Methylococcaceae
and could be associated only with changes in the genus
Methylobacter
and not with changes in the dominance of different genera in the family
Methylococcaceae
. For the family
Methylocystaceae
stable communities in all compartments for the whole season were observed. FISH analysis revealed evidence of in situ dominance of the
Methylocystaceae
in all compartments. The numbers of
Methylococcaceae
cells were relatively high only in the rhizoplane, demonstrating the importance of rice roots for growth and maintenance of methanotrophic diversity in the soil.
Metabolic Behavior of
Lactococcus lactis
MG1363 in Microaerobic Continuous Cultivation at a Low Dilution Rate
Authors: Jensen Niels Bang Siemsen , Melchiorsen Claus Rix , Jokumsen Kirsten Væver , Villadsen John
Published: July 2002

Minute amounts of oxygen were supplied to a continuous cultivation of
Lactococcus lactis
subsp.
cremoris
MG1363 grown on a defined glucose-limited medium at a dilution rate of 0.1 h
−1
. More than 80% of the carbon supplied with glucose ended up in fermentation products other than lactate. Addition of even minute amounts of oxygen increased the yield of biomass on glucose by more than 10% compared to that obtained under anaerobic conditions and had a dramatic impact on catabolic enzyme activities and hence on the distribution of carbon at the pyruvate branch point. Increasing aeration caused carbon dioxide and acetate to replace formate and ethanol as catabolic end products while hardly affecting the production of either acetoin or lactate. The negative impact of oxygen on the synthesis of pyruvate formate lyase was confirmed. Moreover, oxygen was shown to down regulate the protein level of alcohol dehydrogenase while increasing the enzyme activity levels of the pyruvate dehydrogenase complex, α-acetolactate synthase, and the NADH oxidases. Lactate dehydrogenase and glyceraldehyde dehydrogenase enzyme activity levels were unaffected by aeration.
Photosynthetic and Phylogenetic Primers for Detection of Anoxygenic Phototrophs in Natural Environments
Authors: Achenbach Laurie A. , Carey Jennifer , Madigan Michael T.
Published: July 2002

Primer sets were designed to target specific 16S ribosomal DNA (rDNA) sequences of photosynthetic bacteria, including the green sulfur bacteria, the green nonsulfur bacteria, and the members of the
Heliobacteriaceae
(a gram-positive phylum). Due to the phylogenetic diversity of purple sulfur and purple nonsulfur phototrophs, the 16S rDNA gene was not an appropriate target for phylogenetic rDNA primers. Thus, a primer set was designed that targets the
pufM
gene, encoding the M subunit of the photosynthetic reaction center, which is universally distributed among purple phototrophic bacteria. The
pufM
primer set amplified DNAs not only from purple sulfur and purple nonsulfur phototrophs but also from
Chloroflexus
species, which also produce a reaction center like that of the purple bacteria. Although the purple bacterial reaction center structurally resembles green plant photosystem II, the
pufM
primers did not amplify cyanobacterial DNA, further indicating their specificity for purple anoxyphototrophs. This combination of phylogenetic- and photosynthesis-specific primers covers all groups of known anoxygenic phototrophs and as such shows promise as a molecular tool for the rapid assessment of natural samples in ecological studies of these organisms.
Toxic-Metabolite-Producing Bacteria and Fungus in an Indoor Environment
Authors: Peltola J. , Andersson M. A. , Haahtela T. , Mussalo-Rauhamaa H. , Rainey F. A. , Kroppenstedt R. M. , Samson R. A. , Salkinoja-Salonen M. S.
Published: July 2002

Toxic-metabolite-emitting microbes were isolated from the indoor environment of a building where the occupant was suffering serious building-related ill-health symptoms. Toxic substances soluble in methanol and inhibitory to spermatozoa at <10 μg (dry weight) ml
−1
were found from six bacterial isolates and one fungus. The substances from isolates of
Bacillus simplex
and from isolates belonging to the actinobacterial genera
Streptomyces
and
Nocardiopsis
were mitochondriotoxic. These substances dissipated the mitochondrial membrane potential (Δψ) of boar spermatozoa. The substances from the
Streptomyces
isolates also swelled the mitochondria. The substances from isolates of
Trichoderma harzianum
Rifai and
Bacillus pumilus
damaged the cell membrane barrier function of sperm cells.
Quantitative Comparisons of 16S rRNA Gene Sequence Libraries from Environmental Samples
Authors: Singleton David R. , Furlong Michelle A. , Rathbun Stephen L. , Whitman William B.
Published: July 2002

To determine the significance of differences between clonal libraries of environmental rRNA gene sequences, differences between homologous coverage curves,CX(D), and heterologous coverage curves,CXY(D), were calculated by a Cramér-von Mises-type statistic and compared by a Monte Carlo test procedure. This method successfully distinguished rRNA gene sequence libraries from soil and bioreactors and correctly failed to find differences between libraries of the same composition.
Grassland Management Regimens Reduce Small-Scale Heterogeneity and Species Diversity of β-Proteobacterial Ammonia Oxidizer Populations
Authors: Webster Gordon , Embley T. Martin , Prosser James I.
Published: July 2002

The impact of soil management practices on ammonia oxidizer diversity and spatial heterogeneity was determined in improved (addition of N fertilizer), unimproved (no additions), and semi-improved (intermediate management) grassland pastures at the Sourhope Research Station in Scotland. Ammonia oxidizer diversity within each grassland soil was assessed by PCR amplification of microbial community DNA with both ammonia oxidizer-specific, 16S rRNA gene (rDNA) and functional,
amoA
, gene primers. PCR products were analysed by denaturing gradient gel electrophoresis, phylogenetic analysis of partial 16S rDNA and
amoA
sequences, and hybridization with ammonia oxidizer-specific oligonucleotide probes. Ammonia oxidizer populations in unimproved soils were more diverse than those in improved soils and were dominated by organisms representing
Nitrosospira
clusters 1 and 3 and
Nitrosomonas
cluster 7 (closely related phylogenetically to
Nitrosomonas europaea
). Improved soils were only dominated by
Nitrosospira
cluster 3 and
Nitrosomonas
cluster 7. These differences were also reflected in functional gene (
amoA
) diversity, with
amoA
gene sequences of both
Nitrosomonas
and
Nitrosospira
species detected. Replicate 0.5-g samples of unimproved soil demonstrated significant spatial heterogeneity in 16S rDNA-defined ammonia oxidizer clusters, which was reflected in heterogeneity in ammonium concentration and pH. Heterogeneity in soil characteristics and ammonia oxidizer diversity were lower in improved soils. The results therefore demonstrate significant effects of soil management on diversity and heterogeneity of ammonia oxidizer populations that are related to similar changes in relevant soil characteristics.
Population Dynamics of Active and Total Ciliate Populations in Arable Soil Amended with Wheat
Authors: Ekelund Flemming , Frederiksen Helle B. , Rønn Regin
Published: July 2002

Soil protozoa are characterized by their ability to produce cysts, which allows them to survive unfavorable conditions (e.g., desiccation) for extended periods. Under favorable conditions, they may rapidly excyst and begin feeding, but even under optimal conditions, a large proportion of the population may be encysted. The factors governing the dynamics of active and encysted cells in the soil are not well understood. Our objective was to determine the dynamics of active and encysted populations of ciliates during the decomposition of freshly added organic material. We monitored, in soil microcosms, the active and total populations of ciliates, their potential prey (bacteria and small protozoa), their potential competitors (amoebae, flagellates, and nematodes), and their potential predators (nematodes). We sampled with short time intervals (2 to 6 days) and generated a data set, suitable for mathematical modeling. Following the addition of fresh organic material, bacterial numbers increased more than 1,400-fold. There was a temporary increase in the number of active ciliates, followed by a rapid decline, although the size of the bacterial prey populations remained high. During this initial burst of ciliate growth, the population of cystic ciliates increased 100-fold. We suggest that internal population regulation is the major factor governing ciliate encystment and that the rate of encystment depends on ciliate density. This model provides a quantitative explanation of ciliatostasis and can explain why protozoan growth in soil is less than that in aquatic systems. Internally governed encystment may be an essential adaptation to an unpredictable environment in which individual protozoa cannot predict when the soil will dry out and will survive desiccation only if they have encysted in time.
Molecular and Culture-Based Analyses of Prokaryotic Communities from an Agricultural Soil and the Burrows and Casts of the EarthwormLumbricus rubellus
Authors: Furlong Michelle A. , Singleton David R. , Coleman David C. , Whitman William B.
Published: July 2002

The microbial populations in no-till agricultural soil and casts of the earthwormLumbricus rubelluswere examined by culturing and molecular methods. Clone libraries of the 16S rRNA genes were prepared from DNA isolated directly from the soil and earthworm casts. Although no single phylum dominated the soil library of 95 clones, the largest numbers of clones were fromAcidobacteria(14%),Cytophagales(13%),Chloroflexi(8%), and γ-Proteobacteria(8%). While the cast clone library of 102 clones was similar to the soil library, the abundances of several taxa were different. Representatives of thePseudomonasgenus as well as theActinobacteriaandFirmicutesincreased in number, and one group of unclassified organisms found in the soil library was absent in the cast library. Likewise, soil and cast archaeal 16S rRNA gene libraries were similar, although the abundances of some groups were different. Two hundred and thirty aerobic bacteria were also isolated on general heterotrophic media from casts, burrows, and soil. The cast isolates were both phenotypically and genotypically different from the soil isolates. The cast isolates were more likely to reduce nitrate, grow on acetate and Casamino Acids, and utilize fewer sugars than the soil isolates. On the basis of their ribotypes, the cast isolates were dominated byAeromonasspp. (28%), which were not found in the soil isolates, and other γ-Proteobacteria(49%). In contrast, the soil isolates were mostlyActinobacteria(53%),Firmicutes(16%), and γ-Proteobacteria(19%). Isolates obtained from the sides of earthworm burrows were not different from the soil isolates. Diversity indices for the collections of isolates as well as rRNA gene libraries indicated that the species richness and evenness were decreased in the casts from their levels in the soil. These results were consistent with a model where a large portion of the microbial population in soil passes through the gastrointestinal tract of the earthworm unchanged while representatives of some phyla increase in abundance.
Identification of the Functionally Active Methanotroph Population in a Peat Soil Microcosm by Stable-Isotope Probing
Authors: Morris Samantha A. , Radajewski Stefan , Willison Toby W. , Murrell J. Colin
Published: July 2002

The active population of low-affinity methanotrophs in a peat soil microcosm was characterized by stable-isotope probing. “Heavy”
13
C-labeled DNA, produced after microbial growth on
13
CH
4
, was separated from naturally abundant
12
C-DNA by cesium chloride density gradient centrifugation and used as a template for the PCR. Amplification products of 16S rRNA genes and
pmoA
,
mxaF
, and
mmoX
, which encode key enzymes in the CH
4
oxidation pathway, were analyzed. Sequences related to extant type I and type II methanotrophs were identified, indicating that these methanotrophs were active in peat exposed to 8% (vol/vol) CH
4
. The
13
C-DNA libraries also contained clones that were related to β-subclass
Proteobacteria
, suggesting that novel groups of bacteria may also be involved in CH
4
cycling in this soil.
Evaluation of 12 Commercial Tests for Detection of Epstein-Barr Virus-Specific and Heterophile Antibodies
Authors: Bruu Anne-Lise , Hjetland Reidar , Holter Ellen , Mortensen Liisa , Natås Olav , Petterson Wenche , Skar Anne Grete , Skarpaas Tone , Tjade Trygve , Åsjø Birgitta
Published: July 2002

Ten microbiological departments in Norway have participated in a multicenter evaluation of the following commercial tests for detection of Epstein-Barr virus (EBV)-specific and heterophile antibodies: CAPTIA Select viral capsid antigen (VCA)-M/G/EBNA (Centocor Inc.), Enzygnost anti-EBV/immunoglobulin M (IgM) and IgG (Dade Behring), Vironostika EBV VCA IgM/IgG/EBNA enzyme-linked immunosorbent assay (ELISA) (Organon Teknika), SEROFLUOR immunofluorescence assay and EBV Combi-Test (Institute Virion Ltd.), anti-EBV recombinant IgM- and IgG-early antigen/EBNA IgG ELISA (Biotest Diagnostics), EBV IgM/IgG/EBNA ELISA (Gull Laboratories), Paul-Bunnell-Davidsohn test (Sanofi Diagnostics Pasteur), Monosticon Dri-Dot (Organon Teknika), Avitex-IM (Omega Diagnostics Ltd.), Alexon Serascan infectious mononucleosis test (Alexon Biomedical Inc.), Clearview IM (Unipath Ltd.), and Cards±OS Mono (Pacific Biotech, Inc.). The test panel included sera from patients with primary EBV infection, immunocompromised patients with recent cytomegalovirus infection, healthy persons (blood donors), and EBV-seronegative persons. Among the tests for EBV-specific antibodies the sensitivity was good, with only small differences between the different assays. However, there was a greater variation in specificity, which varied between 100% (Enzygnost) and 86% (Biotest). Tests for detection of heterophile antibodies based on purified or selected antigen (Avitex, Alexon, Clearview IM, and Cards±OS Mono) were more sensitive than the Paul-Bunnell-Davidsohn and Monosticon tests.
Antibody Response of Patients with
Helicobacter pylori
-Related Gastric Adenocarcinoma: Significance of Anti-CagA Antibodies
Authors: Vaucher Christine , Janvier Blandine , Nousbaum Jean-Baptiste , Grignon Bernadette , Pezennec Leon , Robaszkiewicz Michel , Gouerou Herve , Picard Bertrand , Fauchere Jean-Louis
Published: July 2002

The aim of this study was to search for a specific antibody pattern in sera from patients suffering from
Helicobacter pylori
-related gastric adenocarcinoma (GAC). The serological response of 22 patients suffering from GAC, 31 patients with gastroduodenal ulcer, and 39 asymptomatic subjects was analyzed using immunoblotting performed with three
H. pylori
strains: strain ATCC 43579; strain B110, isolated from a patient with ulcers; and strain B225, isolated from a patient with GAC. In addition, the latex agglutination test Pyloriset Dry was used to analyze ambiguous sera.
H. pylori
seropositivity was 75% in the GAC group, 61.3% in the ulcer group, and 56.4% in the asymptomatic group. Anti-CagA antibodies were found more often in the GAC group (48.8%) and in the ulcer group (47.3%) than in the asymptomatic group (21.2%). These percentages depended on the strain used as an antigen: in the GAC group, the anti-CagA frequencies were 93.3, 40, and 13.3% with strains B225, B110, and ATCC 43579, respectively. Thus the presence of anti-CagA antibodies was increased in patients suffering from
H. pylori
-related GAC, in particular when the CagA antigen was from a GAC strain. These data suggest the existence of a CagA protein specifically expressed by
H. pylori
strains isolated from GAC patients.
Placental Cellular Immune Response in Women Infected with Human Parvovirus B19 during Pregnancy
Authors: Jordan Jeanne A. , Huff Dale , DeLoia Julie A.
Published: July 2002

Human parvovirus B19 can cause congenital infection with variable morbidity and mortality in the fetus and neonate. Although much information exists on the B19-specific antibody response in pregnant women, little information is available describing the cell-mediated immune (CMI) response at the maternal-fetal interface. The focus of this study was to characterize the CMI response within placentas from women who seroconverted to B19 during their pregnancies and compare it to controls. Immunohistochemical techniques were used to identify the various immune cells and the inflammatory cytokine present within placental tissue sections. Group 1 consisted of placentas from 25 women whose pregnancies were complicated by B19 infection; 6 women with good outcome (near-term or term delivery), and 19 with poor outcome (spontaneous abortion, nonimmune hydrops fetalis, or fetal death). Group 2 consisted of placentas from 20 women whose pregnancies were complicated with nonimmune hydrops fetalis of known, noninfectious etiology. Group 3 consisted of placentas from eight women whose pregnancies ended in either term delivery or elective abortion. The results of the study revealed a statistically significant increase in the number of CD3-positive T cells present within placentas from group 1 compared to group 2 or 3 (13.3 versus 2 and 1, respectively) (
P
< 0.001). In addition, the inflammatory cytokine interleukin 2 was detected in every placenta within group 1 but was absent from all placentas evaluated from groups 2 and 3. Together, these findings demonstrate evidence for an inflammation-mediated cellular immune response within placentas from women whose pregnancies are complicated with B19 infection.
Immunoglobulin G1 Antibody Response toHelicobacter pyloriHeat Shock Protein 60 Is Closely Associated with Low-Grade Gastric Mucosa-Associated Lymphoid Tissue Lymphoma
Authors: Ishii E. , Yokota K. , Sugiyama T. , Fujinaga Y. , Ayada K. , Hokari I. , Hayashi S. , Hirai Y. , Asaka M. , Oguma K.
Published: July 2002

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is related toHelicobacter pyloriinfection. Specifically, it has been pointed out that pathogenesis of MALT lymphoma involves the 60-kDa heat shock protein (hsp60). To investigate humoral immune responses to theH. pylorihsp60 in patients with gastroduodenal diseases and patients with MALT lymphoma, the hsp60 ofH. pyloriwas expressed with a glutathioneS-transferase fusion protein and was purified (recombinant hsp60). Sera were obtained fromH. pylori-positive patients with gastroduodenal diseases (MALT lymphoma,n= 13; gastric ulcer,n= 20; duodenal ulcer,n= 20; gastritis,n= 20) and fromH. pylori-negative healthy volunteers (n= 9). Sera from patients with MALT lymphoma were also obtained at two times: before and after eradication therapy. Antibodies to hsp60 andH. pyloriwere assessed by enzyme-linked immunosorbent assay. The levels of immunoglobulin G (IgG) antibodies to the hsp60 ofH. pylori-positive patients with gastroduodenal diseases were significantly elevated compared to those in the controls. The levels of IgG1 antibodies to hsp60 were elevated and correlated with the levels of anti-H. pyloriantibodies in patients with MALT lymphoma. Humarol immunity against hsp60 may be important and relevant to gastroduodenal diseases induced byH. pyloriinfection.
Emergence of DiverseHelicobacterSpecies in the Pathogenesis of Gastric and Enterohepatic Diseases
Authors: Solnick Jay V. , Schauer David B.
Published: July 2002

Since Helicobacter pylori was first cultivated from human gastric biopsy specimens in 1982, it has become apparent that many related species can often be found colonizing the mucosal surfaces of humans and other animals. These other Helicobacter species can be broadly grouped according to whether they colonize the gastric or enterohepatic niche. GastricHelicobacter species are widely distributed in mammalian hosts and are often nearly universally prevalent. In many cases they cause an inflammatory response resembling that seen with H. pylori in humans. Although usually not pathogenic in their natural host, these organisms serve as models of human disease. Enterohepatic Helicobacter species are an equally diverse group of organisms that have been identified in the intestinal tract and the liver of humans, other mammals, and birds. In many cases they have been linked with inflammation or malignant transformation in immunocompetent hosts and with more severe clinical disease in immunocompromised humans and animals. The purpose of this review is to describe these other Helicobacter species, characterize their role in the pathogenesis of gastrointestinal and enterohepatic disease, and discuss their implications for our understanding of H. pylori infection in humans.
Global Impact of Human Immunodeficiency Virus and AIDS
Authors: Gayle Helene D. , Hill Gena L.
Published: July 2002

This review provides information on the epidemiology, economic impact, and intervention strategies for the human immunodeficiency virus (HIV)/AIDS pandemic in developing countries. According to the World Health Organization and the Joint United Nations Programme on HIV/AIDS (UNAIDS) at the end of 1999, an estimated 34.3 million people were living with HIV/AIDS. Most of the people living with HIV, 95% of the global total, live in developing countries. Examples of the impact of HIV/AIDS in Africa, Asia, Latin America, the Caribbean, and the Newly Independent States provide insight into the demographics, modes of exposure, treatment and prevention options, and the economic effect of the epidemic on the global community. The epidemic in each region of the world is influenced by the specific risk factors that are associated with the spread of HIV/AIDS and the responses that have evolved to address it. These influences are important in developing HIV/AIDS policies and programs to effectively address the global pandemic.
Lack of Association between Maternal Antibody and Protection of African Infants from Malaria Infection
Authors: Riley E. M. , Wagner G. E. , Ofori M. F. , Wheeler J. G. , Akanmori B. D. , Tetteh K. , McGuinness D. , Bennett S. , Nkrumah F. K. , Anders R. F. , Koram K. A.
Published: July 2002

Maternally derived antibodies are believed to protect infants against infection, but there is little direct evidence for a protective role of passively acquired antibodies against malaria. A longitudinal study of malaria infection in 143 infants was conducted in a region of southern Ghana where
Plasmodium falciparum
is endemic. Infants born in the high-transmission season were less likely to become infected in the first 20 weeks of life than children born in the low-transmission season. Plasma, obtained at birth, was tested for immunoglobulin G (IgG) and IgG subclasses to
P. falciparum
schizonts and recombinant circumsporozoite antigen, MSP-1
19
, MSP-2, AMA-1, and Pf155 (also called ring-infected erytrocyte surface antigen). Antibody levels at birth were not associated with resistance to malaria infection. On the contrary, antibodies at birth were positively associated with infection, indicating that high levels of maternally derived antibodies represent a marker for intensity of exposure to malaria infection in infants. However, all five children who experienced high-density infections (>100 parasites/μl of blood) were seronegative for MSP-1
19
at the time of infection.
pMGA Phenotypic Variation in
Mycoplasma gallisepticum
Occurs In Vivo and Is Mediated by Trinucleotide Repeat Length Variation
Authors: Glew M. D. , Browning Glenn F. , Markham Philip F. , Walker Ian D.
Published: July 2002

Chickens were infected with a pathogenic strain of
Mycoplasma gallisepticum
, and the expression of pMGA, the major surface protein, was inferred by examination of colonies from ex vivo cells. Within 2 days postinfection, 40% of cells had ceased the expression of the original pMGA surface protein (pMGA1.1), and by day 6, the majority of recovered cells were in this category. The switch in pMGA phenotype which had occurred in vivo was reversible, since most colonies produced from ex vivo progenitors exhibited frequent pMGA1.1
+
sectors. After prolonged in vivo habitation, increasing proportions of recovered cells gave rise to variant pMGA colonies which had switched from the expression of pMGA1.1 to another gene, pMGA1.2, concomitant with the acquisition of a (GAA)
12
motif 5′ to its promoter. Collectively, the results suggest that changes in
M. gallisepticum
pMGA gene expression in vivo are normal, common, and possibly obligate events for successful colonization of the host. Surprisingly, the initial cessation of pMGA1.1 expression occurred in the absence of detectable pMGA antibodies and seemed to precede the adaptive immune response.
Strain Diversity in Major Surface Protein 2 Expression during Tick Transmission ofAnaplasma marginale
Authors: Rurangirwa Fred R. , Stiller David , Palmer Guy H.
Published: July 2002

Specific major surface protein 2 (MSP2) variants are expressed byAnaplasma marginalewithin the tick salivary gland and, following transmission, are expressed during acute rickettsemia. In previous work, we have shown that a restricted pattern of MSP2 variants is expressed in the salivary glands ofDermacentor andersoniticks infected with the South Idaho strain ofA. marginale. Now we demonstrate that the identical restriction does not apply to two other strains ofA. marginale, and that different variants are also expressed when the same strain is transmitted by differentDermacentorspp. This indicates that antigenic diversity among strains is maintained in tick transmission and may be a significant constraint to MSP2 vaccine development.
Molecular Epidemiological and Phylogenetic Associations of Two Novel Putative Virulence Genes,
iha
and

iroN
E. coli

, among
Escherichia coli
Isolates from Patients with Urosepsis
Authors: Johnson James R. , Russo Thomas A. , Tarr Phillip I. , Carlino Ulrike , Bilge Sima S. , Vary James C. , Stell Adam L.
Published: July 2002

Two novel putative
Escherichia coli
virulence genes,
iha
and
iroN
from
E. coli
(

iroN
E. coli

), were detected in 55 and 39%, respectively, of 67
E. coli
isolates from patients with urosepsis.
iha
and

iroN
E. coli

exhibited divergent associations with other putative virulence genes, phylogenetic markers, host characteristics, and antimicrobial resistance.
Extending the CD4+T-Cell Epitope Specificity of the Th1 Immune Response to an Antigen Using aSalmonella entericaSerovar Typhimurium Delivery Vehicle
Authors: Lo-Man Richard , Langeveld Jan P. M. , Dériaud Edith , Jehanno Muguette , Rojas Marie , Clément Jean-Marie , Meloen Robert H. , Hofnung Maurice , Leclerc Claude
Published: July 2002

We analyzed the CD4 T-cell immunodominance of the response to a model antigen (Ag), MalE, when delivered by an attenuated strain ofSalmonella entericaserovar Typhimurium (SL3261*pMalE). Compared to purified MalE Ag administered with adjuvant, the mapping of the peptide-specific proliferative responses showed qualitative differences when we used theSalmonellavehicle. We observed the disappearance of one out of eight MalE peptides' T-cell reactivity upon SL3261*pMalE immunization, but this phenomenon was probably due to a low level of T-cell priming, since it could be overcome by further immunization. The most striking effect of SL3261*pMalE administration was the activation and stimulation of new MalE peptide-specific T-cell responses that were silent after administration of purified Ag with adjuvant. Ag presentation assays performed with MalE-specific T-cell hybridomas showed that infection of Ag-presenting cells by this intracellular attenuated bacterium did not affect the processing and presentation of the different MalE peptides by major histocompatibility complex (MHC) class II molecules and therefore did not account for immunodominance modulation. Thus, immunodominance of the T-cell response to microorganisms is governed not only by the frequency of the available T-cell repertoire or the processing steps in Ag-presenting cells that lead to MHC presentation but also by other parameters probably related to the infectious process and to the bacterial products. Our results indicate that, upon infection by a microorganism, the specificity of the T-cell response induced against its Ags can be much more effective than with purified Ags and that it cannot completely be mimicked by purified Ags administered with adjuvant.
Overexpression of Protective Antigen as a Novel Approach To Enhance Vaccine Efficacy ofBrucella abortusStrain RB51
Authors: Vemulapalli Ramesh , He Yongqun , Cravero Silvio , Sriranganathan Nammalwar , Boyle Stephen M. , Schurig Gerhardt G.
Published: July 2002

Brucella abortusstrain RB51 is an attenuated rough strain that is currently being used as the official live vaccine for bovine brucellosis in the United States and several other countries. We reasoned that overexpression of a protective antigen(s) ofB. abortusin strain RB51 should enhance its vaccine efficacy. To test this hypothesis, we overexpressed Cu/Zn superoxide dismutase (SOD) protein ofB. abortusin strain RB51. This was accomplished by transforming strain RB51 with a broad-host-range plasmid, pBBR1MCS, containing thesodCgene along with its promoter. Strain RB51 overexpressing SOD (RB51SOD) was tested in BALB/c mice for its ability to protect against challenge infection with virulent strain 2308. Mice vaccinated with RB51SOD, but not RB51, developed antibodies and cell-mediated immune responses to Cu/Zn SOD. Strain RB51SOD vaccinated mice developed significantly (P< 0.05) more resistance to challenge than those vaccinated with strain RB51 alone. The presence of the plasmid alone in strain RB51 did not alter its vaccine efficacy. Also, overexpression of SOD did not alter the attenuation characteristic of strain RB51.
Biosynthesis and Functions of Melanin in
Sporothrix schenckii
Authors: Romero-Martinez Rafael , Wheeler Michael , Guerrero-Plata Antonieta , Rico Guadalupe , Torres-Guerrero Haydée
Published: July 2002

Sporothrix schenckii
is a human pathogen that causes sporotrichosis, an important cutaneous mycosis with a worldwide distribution. It produces dark-brown conidia, which infect the host. We found that
S. schenckii
synthesizes melanin via the 1,8-dihydroxynaphthalene pentaketide pathway. Melanin biosynthesis in the wild type was inhibited by tricyclazole, and colonies of the fungus were reddish brown instead of black on tricyclazole-amended medium. Two melanin-deficient mutant strains were analyzed in this study: an albino that produced normal-appearing melanin on scytalone-amended medium and a reddish brown mutant that accumulated and extruded melanin metabolites into its medium. Scytalone and flaviolin obtained from cultures of the reddish brown mutant were identified by thin-layer chromatography, high-performance liquid chromatography, and UV spectra. Transmission electron microscopy showed an electron-dense granular material believed to be melanin in wild-type conidial cell walls, and this was absent in conidial walls of the albino mutant unless the albino was grown on a scytalone-amended medium. Melanized cells of wild-type
S. schenckii
and the albino grown on scytalone-amended medium were less susceptible to killing by chemically generated oxygen- and nitrogen-derived radicals and by UV light than were conidia of the mutant strains. Melanized conidia of the wild type and the scytalone-treated albino were also more resistant to phagocytosis and killing by human monocytes and murine macrophages than were unmelanized conidia of the two mutants. These results demonstrate that melanin protects
S. schenckii
against certain oxidative antimicrobial compounds and against attack by macrophages.
Comparison of Protection in Rabbits against Host-Adapted and CultivatedBorrelia burgdorferifollowing Infection-Derived Immunity or Immunization with Outer Membrane Vesicles or Outer Surface Protein A
Authors: Shang Ellen S. , Champion Cheryl I. , Wu Xiao-Yang , Skare Jonathan T. , Blanco David R. , Miller James N. , Lovett Michael A.
Published: July 2002

In this study, infection-derived immunity in the rabbit model of Lyme disease was compared to immunity following immunization with purified outer membrane vesicles (OMV) isolated fromBorrelia burgdorferiand recombinant outer surface protein A (OspA). Immunization of rabbits with OMV isolated from virulent strain B31 and its avirulent derivative B313 (lacking OspA and DbpA) conferred highly significant protection against intradermal injection with 6 × 104in vitro-cultivated virulentB. burgdorferi. This is the first demonstration of protective immunogenicity induced by OMV. While immunization with OspA and avirulent B31 OMV provided far less protection against this challenge, rabbits with infection-derived immunity were completely protected. Protection against host-adaptedB. burgdorferiwas assessed by implantation of skin biopsies taken from rabbit erythema migrans (a uniquely rich source ofB. burgdorferiin vertebrate tissue) containing up to 108spirochetes. While all of the OMV- and OspA-immunized rabbits were fully susceptible to skin and disseminated infection, rabbits with infection-derived immunity were completely protected. Analysis of the antibody responses to outer membrane proteins, including DbpA, OspA, and OspC, suggests that the remarkable protection exhibited by the infection-immune rabbits is due to antibodies directed at antigens unique to or markedly up-regulated in host-adaptedB. burgdorferi.
Influence of β2-Integrin Adhesion Molecule Expression and Pulmonary Infection withPasteurella haemolyticaon Cytokine Gene Expression in Cattle
Authors: Lee Haa-Yung , Kehrli Marcus E. , Brogden Kim A. , Gallup Jack M. , Ackermann Mark R.
Published: July 2002

β2-Integrins are leukocyte adhesion molecules composed of alpha (CD11a, -b, -c, or -d) and beta (CD18) subunit heterodimers. Genetic CD18 deficiency results in impaired neutrophil egress into tissues that varies between conducting airways and alveoli of the lung. In this study, we investigated whether CD18 deficiency in cattle affects proinflammatory cytokine (PIC) expression in pulmonary tissue after respiratory infection withPasteurella haemolytica. Cattle were infected withP. haemolyticavia fiberoptic deposition of organisms into the posterior part of the right cranial lung lobe. Animals were euthanized at 2 or 4 h postinoculation (p.i.), and tissues were collected to assess PIC gene expression using antisense RNA probes specific for bovine interleukin-1α (IL-1α), IL-1β, IL-6, gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) along with the β-actin (β-Act) housekeeping gene. Expression of PIC was induced at 2 h p.i. inP. haemolytica-infected cattle and continued to 4 h p.i. At 2 h p.i., induction of gene expression and increase of cells that expressed PIC were observed both in CD18+and CD18−cattle after inoculation ofP. haemolytica. The induction of gene expression withP. haemolyticainoculation was more prominent in CD18−cattle than in CD18+cattle by comparison to pyrogen-free saline (PFS)-inoculated control animals. At 4 h p.i., however, the induction of PIC, especially IL-1α, IL-6, and IFN-γ, in the lungs of CD18+cattle inoculated withP. haemolyticawas greater than that in lungs of the CD18−cattle. IFN-γ and TNF-α genes were not increased inP. haemolytica-inoculated CD18−cattle lungs compared to the PFS-inoculated control lungs at 4 h p.i. In PFS-inoculated lungs, we generally observed a higher percentage of cells and higher level of gene expression in the lungs of CD18−cattle than in the lungs of CD18+cattle, especially at 4 h p.i. The rate of neutrophil infiltration into the lungs of CD18−cattle at 2 h p.i. was significantly higher than that of CD18+cattle; at 4 h p.i., there was no difference between the two groups. These data suggest that β2-integrins may contribute to the induction of expression of some PIC genes, as a consequence ofP. haemolyticainfection.