bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metabolic Engineering of
Lactobacillus helveticus
CNRZ32 for Production of Pure
l
-(+)-Lactic Acid
Authors: Kylä-Nikkilä Kari , Hujanen Mervi , Leisola Matti , Palva Airi 
Published: July 2002

ABSTRACT

Expression of
d
-(−)-lactate dehydrogenase (
d
-LDH) and
l
-(+)-LDH genes (
ldhD
and
ldhL
, respectively) and production of
d
-(−)- and
l
-(+)-lactic acid were studied in
Lactobacillus helveticus
CNRZ32. In order to develop a host for production of pure
l
-(+)-isomer of lactic acid, two
ldhD
-negative
L. helveticus
CNRZ32 strains were constructed using gene replacement. One of the strains was constructed by deleting the promoter region of the
ldhD
gene, and the other was constructed by replacing the structural gene of
ldhD
with an additional copy of the structural gene (
ldhL
) of
l
-LDH of the same species. The resulting strains were designated GRL86 and GRL89, respectively. In strain GRL89, the second copy of the
ldhL
structural gene was expressed under the
ldhD
promoter. The two
d
-LDH-negative strains produced only
l
-(+)-lactic acid in an amount equal to the total lactate produced by the wild type. The maximum
l
-LDH activity was found to be 53 and 93% higher in GRL86 and GRL89, respectively, than in the wild-type strain. Furthermore, process variables for
l
-(+)-lactic acid production by GRL89 were optimized using statistical experimental design and response surface methodology. The temperature and pH optima were 41°C and pH 5.9. At low pH, when the growth and lactic acid production are uncoupled, strain GRL89 produced approximately 20% more lactic acid than GRL86.
Role of the DmpR-Mediated Regulatory Circuit in Bacterial Biodegradation Properties in Methylphenol-Amended Soils
Authors: Sarand Inga , Skärfstad Eleonore , Forsman Mats , Romantschuk Martin , Shingler Victoria 
Published: July 2002

ABSTRACT

Pathway substrates and some structural analogues directly activate the regulatory protein DmpR to promote transcription of the
dmp
operon genes encoding the (methyl)phenol degradative pathway of
Pseudomonas
sp. strain CF600. While a wide range of phenols can activate DmpR, the location and nature of substituents on the basic phenolic ring can limit the level of activation and thus utilization of some compounds as assessed by growth on plates. Here we address the role of the aromatic effector response of DmpR in determining degradative properties in two soil matrices that provide different nutritional conditions. Using the wild-type system and an isogenic counterpart containing a DmpR mutant with enhanced ability to respond to
para
-substituted phenols, we demonstrate (i) that the enhanced in vitro biodegradative capacity of the regulator mutant strain is manifested in the two different soil types and (ii) that exposure of the wild-type strain to 4-methylphenol-contaminated soil led to rapid selection of a subpopulation exhibiting enhanced capacities to degrade the compound. Genetic and functional analyses of 10 of these derivatives demonstrated that all harbored a single mutation in the sensory domain of DmpR that mediated the phenotype in each case. These findings establish a dominating role for the aromatic effector response of DmpR in determining degradation properties. Moreover, the results indicate that the ability to rapidly adapt regulator properties to different profiles of polluting compounds may underlie the evolutionary success of DmpR-like regulators in controlling aromatic catabolic pathways.
Relative Distribution and Conservation of Genes Encoding Aminoglycoside-Modifying Enzymes in
Salmonella enterica
Serotype Typhimurium Phage Type DT104
Authors: Frana Timothy S. , Carlson Steve A. , Griffith Ronald W. 
Published: July 2002

ABSTRACT

PCR was used to identify genes encoding aminoglycoside-modifying enzymes in 422 veterinary isolates of
Salmonella enterica
serotype Typhimurium. The identities of extra-integron genes encoding resistance to streptomycin, gentamicin, kanamycin, and apramycin were evaluated. Gentamicin resistance was conferred by the
aadB
gene. Kanamycin resistance was encoded by either the
aphA1-Iab
gene or the
Kn
gene. Apramycin resistance was determined by the
aacC4
gene. Analysis of gene distribution did not reveal significant differences with regard to phage type, host species, or region except for the
Kn
gene, which was found mostly in nonclinical isolates. The data from this study indicate that pentaresistant DT104 does not acquire extra-integron genes in species- or geography-related foci, which supports the hypothesis that clonal expansion is the method of spread of this organism.
Solid-Phase Capture of Proteins, Spores, and Bacteria
Authors: Weimer B. C. , Walsh M. K. , Beer C. , Koka R. , Wang X. 
Published: July 2002

ABSTRACT

Current methods for the detection of pathogens in food and water samples generally require a preenrichment step that allows selective enrichment of the test organism. The objective of this research was to eliminate an enrichment step to allow detection of bacteria directly in food and water samples in 30 min. A high-flow-rate, fluidized bed to capture and concentrate large (bacteria and spores) and small (protein) molecules was developed. This format, ImmunoFlow, is volume independent and uses large beads (greater than 3 mm in diameter) when capturing bacteria to prevent sample clogging when testing food samples. Detection of bound targets was done using existing enzyme-linked immunosorbent assay (ELISA) protocols. Four antibodies (anti-
Escherichia coli
O157:H7, -
Bacillus globigii
, -bovine serum albumin [BSA], and -ovalbumin [OVA]) were covalently coupled to various glass and ceramic beads. Very small amounts of BSA (<1 ng) and OVA (0.2 to 4.0 μg) were detected. Various industrial and environmental samples were used to observe the effect of the sample composition on the capture of anti-
B. globigii
and anti-
E. coli
O157:H7 modified beads. The lower limit of detection for both
E. coli
O157:H7 and
B. globigii
was 1 spore/cell independent of the sample size. The activity of anti-
B. globigii
modified beads declined after 3 days. Anti-
E. coli
O157:H7 modified beads declined in their capture ability after 2 days in various storage buffers. Storage temperature (4 and 25°C) did not influence the stability. The ImmunoFlow technology is capable of capturing bacteria and spores directly from samples, with subsequent detection in an ELISA format in 30 min.
Rupture of the Cell Envelope by Decompression of the Deep-Sea Methanogen
Methanococcus jannaschii
Authors: Park Chan Beum , Clark Douglas S. 
Published: July 2002

ABSTRACT

The effect of decompression on the structure of
Methanococcus jannaschii
, an extremely thermophilic deep-sea methanogen, was studied in a novel high-pressure, high-temperature bioreactor. The cell envelope of
M. jannaschii
appeared to rupture upon rapid decompression (ca. 1 s) from 260 atm of hyperbaric pressure. When decompression from 260 atm was performed over 5 min, the proportion of ruptured cells decreased significantly. In contrast to the effect produced by decompression from hyperbaric pressure, decompression from a hydrostatic pressure of 260 atm did not induce cell lysis.
Genes from
Pseudomonas
sp. Strain BS Involved in the Conversion of
l
-2-Amino-Δ
2
-Thiazolin-4-Carbonic Acid to
l
-Cysteine
Authors: Shiba Toshikazu , Takeda Kohji , Yajima Misako , Tadano Makoto 
Published: July 2002

ABSTRACT

dl
-2-amino-Δ
2
-thiazolin-4-carbonic acid (
dl
-ATC) is a substrate for cysteine synthesis in some bacteria, and this bioconversion has been utilized for cysteine production in industry. We cloned a DNA fragment containing the genes involved in the conversion of
l
-ATC to
l
-cysteine from
Pseudomonas
sp. strain BS. The introduction of this DNA fragment into
Escherichia coli
cells enabled them to convert
l
-ATC to cysteine via
N
-carbamyl-
l
-cysteine (
l
-NCC) as an intermediate. The smallest recombinant plasmid, designated pTK10, contained a 2.6-kb insert DNA fragment that has
l
-cysteine synthetic activity. The nucleotide sequence of the insert DNA revealed that two open reading frames (ORFs) encoding proteins with molecular masses of 19.5 and 44.7 kDa were involved in the
l
-cysteine synthesis from
dl
-ATC. These ORFs were designated
atcB
and
atcC
, respectively, and their gene products were identified by overproduction of proteins encoded in each ORF and by the maxicell method. The functions of these gene products were examined using extracts of
E. coli
cells carrying deletion derivatives of pTK10. The results indicate that
atcB
and
atcC
are involved in the conversion of
l
-ATC to
l
-NCC and the conversion of
l
-NCC to cysteine, respectively.
atcB
was first identified as a gene encoding an enzyme that catalyzes thiazolin ring opening. AtcC is highly homologous with
l
-
N
-carbamoylases. Since both enzymes can only catalyze the
l
-specific conversion from
l
-ATC to
l
-NCC or
l
-NCC to
l
-cysteine, it is thought that
atcB
and
atcC
encode
l
-ATC hydrolase and
N
-carbamyl-
l
-cysteine amidohydrolase, respectively.
Characterization of
Trichodesmium
spp. by Genetic Techniques
Authors: Orcutt K. M. , Rasmussen U. , Webb E. A. , Waterbury J. B. , Gundersen K. , Bergman B. 
Published: July 2002

ABSTRACT

The genetic diversity of
Trichodesmium
spp. from natural populations (off Bermuda in the Sargasso Sea and off North Australia in the Arafura and Coral Seas) and of culture isolates from two regions (Sargasso Sea and Indian Ocean) was investigated. Three independent techniques were used, including a DNA fingerprinting method based on a highly iterated palindrome (HIP1), denaturing gradient gel electrophoresis of a
hetR
fragment, and sequencing of the internal transcribed spacer (ITS) of the 16S-23S rDNA region. Low genetic diversity was observed in natural populations of
Trichodesmium
spp. from the two hemispheres. Culture isolates of
Trichodesmium thiebautii
,
Trichodesmium hildebrandtii
,
Trichodesmium tenue
, and
Katagnymene spiralis
displayed remarkable similarity when these techniques were used, suggesting that
K. spiralis
is very closely related to the genus
Trichodesmium
. The largest genetic variation was found between
Trichodesmium erythraeum
and all other species of
Trichodesmium
, including a species of
Katagnymene
. Our data obtained with all three techniques suggest that there are two major clades of
Trichodesmium
spp. The HIP1 fingerprinting and ITS sequence analyses allowed the closely related species to be distinguished. This is the first report of the presence of HIP1 in marine cyanobacteria.
Superantigens and Cystic Fibrosis: Resistance of Presenting Cells to Dexamethasone
Authors: Ben-Ari Josef , Gozal David , Dorio Raymond J. , Bowman C. Michael , Reiff Andreas , Walker Sharyn M. 
Published: July 2002

ABSTRACTStaphylococcus aureus, a common pulmonary pathogen in cystic fibrosis (CF), produces exotoxins that are extremely potent superantigens. A number of animal studies have shown that superantigens cause pulmonary inflammation, but the possible role of superantigens in CF has not been investigated. The present study assessed possible differences between control and CF B cells in presenting superantigens to T cells. Immortalized B-cell lines were used as superantigen-presenting cells to avoid environmental influences (e.g., infection or antibiotics) common to freshly isolated cells. The results show that CF B-cell lines presented a staphylococcal superantigen to the immortalized T-cell line (Jurkat) as effectively as did control B-cell lines as measured by interleukin-2 production. However, in contrast to the case for control B-cell lines, dexamethasone did not inhibit CF B-cell lines from presenting superantigen. The resistance of superantigen-presenting CF B cells to corticosteroids suggests that the pulmonary response to superantigens may be poorly regulated in CF, leading to an exaggerated inflammatory response toS. aureus.
Serum Opsonic Activity in Infants with Sickle-Cell Disease Immunized with Pneumococcal Polysaccharide Protein Conjugate Vaccine
Authors: Nowak-Wegrzyn Anna , Winkelstein Jerry A. , Swift Andrea J. , Lederman Howard M. ,   The Pneumococcal Conjugate Vaccine Study Group
Published: July 2002

ABSTRACT
Pneumococcal infections are an important cause of morbidity and mortality in children with sickle-cell disease (SCD). Pneumococcal conjugate vaccines (PCVs) are immunogenic in healthy infants <2 years of age but have not been evaluated in young children with SCD. Infants with SCD were immunized with a 7-valent PCV (Wyeth-Lederle Vaccines & Pediatrics) at 2, 4, and 6 months of age. A booster dose of 23-valent pneumococcal polysaccharide vaccine (PPV; Pnu-Immune) was administered at 24 months of age. Antipneumococcal type 6B and 14 serum opsonic activity was measured to assess the biologic function of the antibody. Following the administration of three doses of PCV, opsonic activity against serotype 6B increased from 4.8% at 2 months to 33.5% at 7 months, with a subsequent decline to 8.1% at 12 months and 7.5% at 24 months and with an increase to 30.7% at 25 months after administration of a booster dose of PPV. Similar trends were seen with serotype 14 (opsonic activities were 9.4% at 2 months, 24.9% at 7 months, 16.5% at 12 months, and 12.6% at 24 months, and the opsonic activity was 27.3% 1 month after the administration of PPV). Serum opsonic activity correlated with antibody levels for both serotypes. PCV induces serum opsonic activity in infants with SCD. Antipneumococcal serum opsonic activity correlates with antibody levels.
Performance of Antigens Used in Detecting Delayed-Type Hypersensitivity in Adolescents Infected with the Human Immunodeficiency Virus
Authors: Rogers Audrey Smith , Ellenberg Jonas H. , Douglas Steven D. , Henry-Reid Lisa , Peralta Ligia , Wilson Craig M. ,   The Adolescent Medicine HIV/AIDS Research Network
Published: July 2002

ABSTRACT

We examined the performance of delayed-type hypersensitivity (DTH) antigens employing a new
Candida albicans
product in a human immunodeficiency virus (HIV)-infected and nonanergic adolescent population. Diameters of induration (in millimeters) for three intradermally applied antigens (
C. albicans
, tetanus toxoid, and mumps) were compared in a population of HIV-infected 12 to 18 year olds at study entry in a national multicenter study of HIV disease progression. CD4
+
T-cell counts were measured in quality-controlled laboratories. The influence of past immunization, gender, and clinical status on antigen reactivity was evaluated with contingency table comparisons and relative risk estimation. Nearly one-half of the 123 eligible subjects were untreated, and almost three-quarters were early in HIV disease by clinical indicators. There was no statistically significant difference in reactivity by past immunization status. Candida antigen (CASTA; Greer Laboratories) evoked DTH response in a significantly higher number of males and females at every level of induration (largest
P
value, 0.049 for male comparisons; all
P
values, <0.001 for females) and in subjects with early and intermediate HIV disease at every level of induration (all
P
values, <0.0001) than either tetanus or mumps antigens. No two-antigen combination was as useful as all three antigens across either gender or clinical categories, although candida and tetanus was the most useful two-antigen combination at indurations of <3 mm. The superior performance of a new C.
albicans
antigen may extend the utility of DTH assessment in monitoring immune function.
Immunoblot Profile as Predictor of Toxoplasmic Encephalitis in Patients Infected with Human Immunodeficiency Virus
Authors: Leport Catherine , Franck Jacqueline , Chene Genevieve , Derouin Francis , Ecobichon Jean-Luc , Pueyo Sophie , Miro Jose M. , Luft Benjamin J. , Morlat Philippe , Dumon Henri ,   the ANRS 005– ACTG 154 Study Group
Published: July 2002

ABSTRACT

In order to define more accurately human immunodeficiency virus-infected patients at risk of developing toxoplasmic encephalitis (TE), we assessed the prognostic significance of the anti-
Toxoplasma gondii
immunoglobulin G (IgG) immunoblot profile, in addition to AIDS stage, a CD4
+
cell count <50/mm
3
, and an antibody titer ≥150 IU/ml, in patients with CD4 cell counts <200/mm
3
and seropositive for
T. gondii.
Baseline serum samples from 152 patients included in the placebo arm of the ANRS 005-ACTG 154 trial (pyrimethamine versus placebo) were used. The IgG immunoblot profile was determined using a
Toxoplasma
lysate and read using the Kodak Digital Science 1D image analysis software. Mean follow-up was 15.1 months, and the 1-year incidence of TE was 15.9%. The cumulative probability of TE varied according to the type and number of anti-
T. gondii
IgG bands and reached 65% at 12 months for patients with IgG bands of 25 and 22 kDa. In a Cox model adjusted for age, gender, Centers for Disease Control and Prevention (CDC) clinical stage, and CD4 and CD8 cell counts, the incidence of TE was higher when the IgG 22-kDa band (hazard ratio [HR] = 5.4;
P
< 0.001), the IgG 25-kDa band (HR = 4.7;
P
< 0.001), or the IgG 69-kDa band (HR = 3.4;
P
< 0.001) was present and was higher for patients at CDC stage C (HR = 4.9;
P
< 0.001).
T. gondii
antibody titer and CD4 cell count were not predictive of TE. Thus, detection of IgG bands of 25, 22, and/or 69 kDa may be helpful for deciding when primary prophylaxis for TE should be started or discontinued, especially in the era of highly active antiretroviral therapy.
Expression of Interleukin-9 Leads to Th2 Cytokine-Dominated Responses and Fatal Enteropathy in Mice with ChronicSchistosoma mansoniInfections
Authors: Fallon Padraic G. , Smith Philip , Richardson Emma J. , Jones Frances J. , Faulkner Helen C. , Van Snick Jacques , Renauld Jean-Christophe , Grencis Richard K. , Dunne David W. 
Published: July 2002

ABSTRACTMice infected withSchistosoma mansonidevelop Th2 cytokine-mediated granulomatous pathology that is focused on the liver and intestines. In this study, transgenic mice constitutively expressing IL-9 were infected withS. mansoniand the outcome of infection was determined. Eight weeks after infection, transgenic mice with acute infections had a moderate increase in Th2 cytokine production but were overtly normal with respect to parasite infection and pathological responses. Transgenic mice with chronic infections died 10 weeks after infection, with 86% of transgenic mice dead by week 12 of infection, compared to 7% mortality in infected wild-type mice. Stimulation of mesenteric lymph node cells from infected transgenic mice with parasite antigen elicited elevated interleukin-4 (IL-4) and IL-5 production and reduced gamma interferon and tumor necrosis factor alpha production compared to the responses in wild-type mice. Morbid transgenic mice had substantial enlargement of the ileum, which was associated with muscular hypertrophy, mastocytosis, eosinophilia, goblet cell hyperplasia, and increased mucin expression. We also observed that uninfected transgenic mice exhibited alterations in their intestines. Although there was hepatic mastocytosis and eosinophilia in infected transgenic mice, there was no hepatocyte damage. Death of transgenic mice expressing IL-9 during schistosome infection was primarily associated with enteropathy. This study highlights the pleiotropic in vivo activity of IL-9 and demonstrates that an elevated Th2 cytokine phenotype leads to death during murine schistosome infection.
Human Granulocytic Ehrlichiosis Agent Inhibits Superoxide Anion Generation by Human Neutrophils
Authors: Mott Jason , Rikihisa Yasuko 
Published: July 2002

ABSTRACTThe human granulocytic ehrlichiosis (HGE) agent, which replicates in neutrophils, was found not to induce superoxide anion (O2−) generation or extracellular release by human peripheral blood neutrophils, as measured by a luminol-dependent chemiluminescence assay or a cytochromecreduction assay, respectively. Furthermore, the HGE agent completely prevented O2−release by neutrophils upon stimulation with phorbol myristate acetate (PMA), formylmethionyl-leucyl-phenylalanine, orEscherichia coli. The inhibition was HGE agent dose dependent, required ehrlichial contact with the host cells, and was reversible upon removal of the extracellular HGE agent bound to the host cells prior to PMA stimulation. Structural integrity of or new protein synthesis by the HGE agent was not required for the inhibition; carbohydrate but not surface protein of the HGE agent was required. The HGE agent did not prevent O2−generation in human peripheral blood monocytes derived from the same individual. This neutrophil-specific prevention of O2−generation by the HGE agent would be critical in survival of the HGE agent. This is the first demonstration of the rapid inhibition of preexisting NADPH oxidase in human neutrophils by the HGE agent.
Pathogenic Mechanism of Mouse Brain Damage Caused by Oral Infection with Shiga Toxin-ProducingEscherichia coliO157:H7
Authors: Kita Eiji , Yunou Yoshihisa , Kurioka Takaaki , Harada Hiroko , Yoshikawa Shinji , Mikasa Keiichi , Higashi Nobutaka 
Published: July 2002

ABSTRACTIn a previous study, we showed that infection with Shiga toxin (Stx)-producingEscherichia coliO157:H7 (strain SmrN-9) caused neurologic symptoms in malnourished mice with positive immunoreactions of Stx2 in brain tissues. The present study explores the mechanism of how Stx injures the vascular endothelium to enter the central nervous system in mice. Oral infection with strain SmrN-9 elicited a tumor necrosis factor alpha (TNF-α) response in the blood as early as 2 days after infection, while Stx was first detected at 3 days postinfection. In the brain, TNF-α was detected at day 3, and its quantity was increased over the next 3 days. Frozen sections of the brains from moribound mice contained high numbers of apoptotic cells. Glycolipids recognized by an anti-Gb3 monoclonal antibody were extracted from the brain, and purified Stx2 was able to bind to the glycolipids. In human umbilical vascular endothelial cells (HUVEC) cultured with fluorescein-labeled Stx2 (100 ng/ml), TNF-α (20 U/ml) significantly facilitated the intracellular compartmentalization of fluorescence during 24 h of incubation, suggesting the enhanced intracellular processing of Stx2. Consequently, higher levels of apoptosis in HUVEC were found at 48 h. Short-term exposure of HUVEC to Stx2 abrogated their apoptotic response to subsequent incubation with TNF-α alone or TNF-α and Stx2. In contrast, primary exposure of HUVEC to TNF-α followed by exposure to Stx2 alone or TNF-α and Stx2 induced apoptosis at the same level as obtained after 48-h incubation with these two agents. These results suggest that the rapid production of circulating TNF-α after infection induces a state of competence in vascular endothelial cells to undergo apoptosis, which would be finally achieved by subsequent elevation of Stx in the blood. In this synergistic action, target cells must be first exposed to TNF-α. Such cell injury may be a prerequisite to brain damage after infection with Stx-producingE. coliO157:H7.