bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fungal Fragments as Indoor Air Biocontaminants
Authors: Górny Rafał L. , Reponen Tiina , Willeke Klaus , Schmechel Detlef , Robine Enric , Boissier Marjorie , Grinshpun Sergey A. 
Published: July 2002

ABSTRACT

The aerosolization process of fungal propagules of three species (
Aspergillus versicolor
,
Penicillium melinii
, and
Cladosporium cladosporioides
) was studied by using a newly designed and constructed aerosolization chamber. We discovered that fungal fragments are aerosolized simultaneously with spores from contaminated agar and ceiling tile surfaces. Concentration measurements with an optical particle counter showed that the fragments are released in higher numbers (up to 320 times) than the spores. The release of fungal propagules varied depending on the fungal species, the air velocity above the contaminated surface, and the texture and vibration of the contaminated material. In contrast to spores, the release of fragments from smooth surfaces was not affected by air velocity, indicating a different release mechanism. Correlation analysis showed that the number of released fragments cannot be predicted on the basis of the number of spores. Enzyme-linked immunosorbent assays with monoclonal antibodies produced against
Aspergillus
and
Penicillium
fungal species showed that fragments and spores share common antigens, which not only confirmed the fungal origin of the fragments but also established their potential biological relevance. The considerable immunological reactivity, the high number, and the small particle size of the fungal fragments may contribute to human health effects that have been detected in buildings with mold problems but had no scientific explanation until now. This study suggests that future fungal spore investigations in buildings with mold problems should include the quantitation of fungal fragments.
Identification of theEnterococcus faecalisTyrosine Decarboxylase Operon Involved in Tyramine Production
Authors: Connil Nathalie , Le Breton Yoann , Dousset Xavier , Auffray Yanick , Rincé Alain , Prévost Hervé 
Published: July 2002

ABSTRACTScreening of a library ofEnterococcus faecalisinsertional mutants allowed isolation of a mutant affected in tyramine production. The growth of this mutant was similar to that of the wild-typeE. faecalisJH2-2 strain in Maijala broth, whereas high-performance liquid chromatography analyses showed that tyramine production, which reached 1,000 μg ml−1for the wild-type strain, was completely abolished. Genetic analysis of the insertion locus revealed a gene encoding a decarboxylase with similarity to eukaryotic tyrosine decarboxylases. Sequence analysis revealed a pyridoxal phosphate binding site, indicating that this enzyme belongs to the family of amino acid decarboxylases using this cofactor. Reverse transcription-PCR analyses demonstrated that the gene (tdc) encoding the putative tyrosine decarboxylase ofE. faecalisJH2-2 is cotranscribed with the downstream gene encoding a putative tyrosine-tyramine antiporter and with the upstream tyrosyl-tRNA synthetase gene. This study is the first description of a tyrosine decarboxylase gene in prokaryotes.
Effects of Psychological Stress and Alprazolam on Development of Oral Candidiasis in Rats
Authors: Núñez M. J. , Balboa J. , Riveiro P. , Liñares D. , Mañá P. , Rey-Méndez M. , Rodríguez-Cobos A. , Suárez-Quintanilla J. A. , García-Vallejo L. A. , Freire-Garabal M. 
Published: July 2002

ABSTRACT

Psychological stress has been found to suppress cell-mediated immune responses that are important in limiting the proliferation of
Candida albicans
. Since anxiolytic drugs can restore cellular immunity in rodents exposed to stress conditions, we designed experiments conducted to evaluate the effects of alprazolam (1 mg/kg of body weight/day), a central benzodiazepine anxiolytic agonist, on the development of oral candidiasis in Sprague-Dawley rats exposed to a chronic auditory stressor. Animals were submitted to surgical hyposalivation in order to facilitate the establishment and persistence of
C. albicans
infection. Application of stress and treatment with drugs (placebo or alprazolam) were initiated 7 days before
C. albicans
inoculation and lasted until the end of the experiments (day 15 postinoculation). Establishment of
C. albicans
infection was evaluated by swabbing the inoculated oral cavity with a sterile cotton applicator on days 2 and 15 after inoculation, followed by plating on YEPD (yeast extract-peptone-dextrose) agar. Tissue injury was determined by the quantification of the number and type (normal or abnormal) of papillae on the dorsal tongue per microscopic field. A semiquantitative scale was devised to assess the degree of colonization of the epithelium by fungal hyphae. Our results show that stress exacerbates
C. albicans
infection of the tongues of rats. Significant increases in
Candida
counts, the percentage of the tongue's surface covered with clinical lesions, the percentage of abnormal papillae, and the colonization of the epithelium by fungal hyphae were found in stressed rats compared to those found in the unstressed rats. Treatment with alprazolam significantly reversed these adverse effects of stress, showing that, besides the psychopharmacological properties of this anxiolytic drug against stress, it has consequences for
Candida
infection.
NF-κB Family of Transcription Factors: Central Regulators of Innate and Adaptive Immune Functions
Authors: Caamaño Jorge , Hunter Christopher A. 
Published: July 2002

SUMMARYTranscription factors of the Rel/NF-κB family are activated in response to signals that lead to cell growth, differentiation, and apoptosis, and these proteins are critical elements involved in the regulation of immune responses. The conservation of this family of transcription factors in many phyla and their association with antimicrobial responses indicate their central role in the regulation of innate immunity. This is illustrated by the association of homologues of NF-κB, and their regulatory proteins, with resistance to infection in insects and plants (M. S. Dushay, B. Asling, and D. Hultmark, Proc. Natl. Acad. Sci. USA93:10343-10347, 1996; D. Hultmark, Trends Genet.9:178-183, 1993; J. Ryals et al., Plant Cell9:425-439, 1997). The aim of this review is to provide a background on the biology of NF-κB and to highlight areas of the innate and adaptive immune response in which these transcription factors have a key regulatory function and to review what is currently known about their roles in resistance to infection, the host-pathogen interaction, and development of human disease.
Proteasomal Degradation of Cytotoxic Necrotizing Factor 1-Activated Rac
Authors: Lerm Maria , Pop Marius , Fritz Gerhard , Aktories Klaus , Schmidt Gudula 
Published: July 2002

ABSTRACT

The cytotoxic necrotizing factor 1 (CNF1) from
Escherichia coli
has been shown to activate members of the Rho family by deamidation of glutamine 63. This amino acid is essential for hydrolysis of GTP, and any substitution results in a constitutively active Rho. Activation of Rho induces the formation of stress fibers, filopodia, and membrane ruffles due to activation of RhoA, Cdc42, and Rac, respectively. Here we show that the level of endogenous Rac decreased in CNF1-treated HEK293 and HeLa cells. The amount of mRNA remained unaffected, leaving the possibility that Rac is subject to proteolytic degradation. Treatment of cells with lactacystin, an inhibitor of the 26S proteasome, protected Rac from degradation. We have previously shown that CNF1 activates the c-Jun N-terminal kinase (JNK) only transiently in HeLa cells (M. Lerm, J. Selzer, A. Hoffmeyer, U. R. Rapp, K. Aktories, and G. Schmidt, Infect. Immun.
67:
496-503, 1998). Here we show that CNF1-induced JNK activation is stabilized in the presence of lactacystin. The data indicate that Rac is degraded by a proteasome-dependent pathway in CNF1-treated cells.
Novel 33-Kilodalton Lipoprotein fromMycobacterium leprae
Authors: Maeda Yumi , Makino Masahiko , Crick Dean C. , Mahapatra Sebabrata , Srisungnam Sopa , Takii Takemasa , Kashiwabara Yoshiko , Brennan Patrick J. 
Published: July 2002

ABSTRACTA novelMycobacterium lepraelipoprotein LpK (accession no.ML0603) was identified from the genomic database. The 1,116-bp open reading frame encodes a 371-amino-acid precursor protein with an N-terminal signal sequence and a consensus motif for lipid conjugation. Expression of the protein, LpK, inEscherichia colirevealed a 33-kDa protein, and metabolic labeling experiments and globomycin treatment proved that the protein was lipidated. Fractionation ofM. lepraedemonstrated that this lipoprotein was a membrane protein ofM. leprae. The purified lipoprotein was found to induce production of interleukin-12 in human peripheral blood monocytes. The studies imply thatM. lepraeLpK is involved in protective immunity against leprosy and may be a candidate for vaccine design.
Genes for Glycosylphosphatidylinositol Toxin Biosynthesis inPlasmodium falciparum
Authors: Delorenzi Mauro , Sexton Adrienne , Shams-Eldin Hosam , Schwarz Ralph T. , Speed Terry , Schofield Louis 
Published: July 2002

ABSTRACTAbout 2.5 million people die ofPlasmodium falciparummalaria every year. Fatalities are associated with systemic and organ-specific inflammation initiated by a parasite toxin. Recent studies show that glycosylphosphatidylinositol (GPI) functions as the dominant parasite toxin in the context of infection. GPIs also serve as membrane anchors for several of the most important surface antigens of parasite invasive stages. GPI anchoring is a complex posttranslational modification produced through the coordinated action of a multicomponent biosynthetic pathway. Here we present eight new genes ofP. falciparumselected for encoding homologs of proteins essential for GPI synthesis: PIG-A, PIG-B, PIG-M, PIG-O, GPI1, GPI8, GAA-1, and DPM1. We describe the experimentally verified mRNA and predicted amino acid sequences and in situ localization of the gene products to the parasite endoplasmic reticulum. Moreover, we show preliminary evidence for the PIG-L and PIG-C genes. The biosynthetic pathway of the malaria parasite GPI offers potential targets for drug development and may be useful for studying parasite cell biology and the molecular basis for the pathophysiology of parasitic diseases.
Quantitative Priming with Inactivated Pertussis Toxoid Vaccine in the Aerosol Challenge Model
Authors: Bruss Jon B. , Siber George R. 
Published: July 2002

ABSTRACT

Serum antibodies to pertussis toxin (PT) have been shown to be protective against severe pertussis disease, although a specific level of anti-PT antibody that correlates with protection has not been demonstrated. Current animal models such as the intracerebral challenge model have significant limitations in correlating protection to a specific level of anti-PT antibody. This study examines the protective effects of priming with tetranitromethane-inactivated pertussis toxoid (PTx) vaccine in the aerosol challenge model and whether a measurable response to a priming dose of PTx is enough to initiate a protective secondary response when challenged with infection. The correlation of priming with markers of illness such as leukocytosis, weight loss, bacterial proliferation, and mortality after established infection with
Bordetella pertussis
was explored. BALB/c mice were immunized with PTx vaccine on day 6 of life and then challenged with
B. pertussis
using the aerosol challenge model. Data were analyzed according to the primary immunologic response, differentiating responders (anti-PT immunoglobulin G [IgG] ≥1 μg/ml) from nonresponders (anti-PT IgG <1 μg/ml). Mice that showed evidence of priming on the day of aerosol challenge were able to mount a secondary response to the challenge with a ≥2-fold rise in anti-PT IgG antibody by day 7 and a ≥10-fold rise by day 14 post-aerosol challenge. These primed mice were significantly better protected against leukocytosis, weight loss, and proliferation of
B. pertussis
in the lungs following aerosol challenge than the nonprimed group. This protection correlated with levels of anti-PT antibody in serum present on the day of aerosol challenge.
Colony-Stimulating Factor 1-Dependent Cells Protect against Systemic Infection with
Listeria monocytogenes
but Facilitate Neuroinvasion
Authors: Jin Yuxuan , Dons Lone , Kristensson Krister , Rottenberg Martin E. 
Published: July 2002

ABSTRACT

By using mice genomically lacking the mononuclear phagocytic growth factor colony-stimulating factor 1 and thereby deficient in macrophage and dendritic cell populations, we show that these cells play a dual role: they constitute a major defense against systemic infection but also facilitate cerebral bacterial invasion by
Listeria monocytogenes
.
cag+Helicobacter pyloriInduces Homotypic Aggregation of Macrophage-Like Cells by Up-Regulation and Recruitment of Intracellular Adhesion Molecule 1 to the Cell Surface
Authors: Moese Stefan , Selbach Matthias , Meyer Thomas F. , Backert Steffen 
Published: July 2002

ABSTRACTInfection withcag+but notcag-negativeHelicobacter pylorileads to the formation of large homotypic aggregates of macrophage-like cells. Intracellular adhesion molecule 1 is up-regulated and recruited to the cell surface of infected cells and mediates the aggregation via lymphocyte function-associated molecule 1. This signaling may regulate cell-cell interactions and inflammatory responses.
Internalization of
Staphylococcus aureus
by Human Corneal Epithelial Cells: Role of Bacterial Fibronectin-Binding Protein and Host Cell Factors
Authors: Jett Bradley D. , Gilmore Michael S. 
Published: July 2002

ABSTRACT

Wild-type
Staphylococcus aureus
was observed to be capable of invading human corneal epithelial cells (HCEC) in vitro. Internalization of
S. aureus
required expression of fibronectin-binding proteins (FnBPs); the capacity of an FnBP-deficient isogenic strain to invade HCEC was reduced by more than 99%. The binding of
S. aureus
to HCEC did not require viable bacteria, since UV-killed cells were observed to adhere efficiently. Invasion of HCEC by
S. aureus
involved active host cell mechanisms; uptake was nearly completely eliminated by cytochalasin D and genistein. These data suggest that FnBPs play a key role in host-parasite interactions and may serve as an important adhesin or invasin in ulcerative keratitis caused by
S. aureus
.
Diverse Bacteria Are Pathogens of
Caenorhabditis elegans
Authors: Couillault Carole , Ewbank Jonathan J. 
Published: July 2002

ABSTRACT

Practically and ethically attractive as model systems, invertebrate organisms are increasingly recognized as relevant for the study of bacterial pathogenesis. We show here that the nematode
Caenorhabditis elegans
is susceptible to a surprisingly broad range of bacteria and may constitute a useful model for the study of both pathogens and symbionts.
Characterization of Genes Involved in Modulation of Conjugal Transfer of theBacteroidesConjugative Transposon CTnDOT
Authors: Whittle Gabrielle , Shoemaker Nadja B. , Salyers Abigail A. 
Published: July 2002

ABSTRACTIn previous studies we identified an 18-kb region of theBacteroidesconjugative transposon CTnDOT that was sufficient for mobilization of coresident plasmids and unlinked integrated elements, as well as self-transfer fromBacteroidestoEscherichia coli. When this 18-kb region was cloned on a plasmid (pLYL72), the plasmid transferred itself constitutively in the absence of a coresident conjugative transposon. However, when this plasmid was present in aBacteroidesstrain containing a coresident conjugative transposon, conjugal transfer was repressed in the absence of tetracycline and enhanced in the presence of tetracycline. These results suggested that a negative and a positive regulator of conjugal transfer were encoded outside the transfer region of the CTnDOT element. In this work, a minimal and inducible transfer system was constructed and used in transfer and Western blot analyses to identify the differentially regulated genes from CTnDOT responsible for the enhancement and repression of pLYL72 conjugal transfer. Both of these regulatory functions have been localized to a region of the CTnDOT element that is essential for CTn excision. In the presence of tetracycline, the regulatory protein RteC activates the expression of a putative topoisomerase gene,exc, which in turn results in an increase in transfer protein expression and a concomitant 100- to 1,000-fold increase in the frequency of pLYL72 transfer. Our results also suggest that sinceexcalone cannot result in enhancement of transfer, other factors encoded upstream ofexcare also required. Conversely, in the absence of tetracycline, a gene located near the 3′ end ofexcis responsible for the repression of transfer protein expression and also results in a 100- to 1,000-fold decrease in the frequency of pLYL72 transfer.
The PhlA Hemolysin from the Entomopathogenic Bacterium
Photorhabdus
luminescens
Belongs to the Two-Partner Secretion Family of Hemolysins
Authors: Brillard Julien , Duchaud Eric , Boemare Noël , Kunst Frank , Givaudan Alain 
Published: July 2002

ABSTRACT

Photorhabdus
is an entomopathogenic bacterium symbiotically associated with nematodes of the family Heterorhabditidae. Bacterial hemolysins found in numerous pathogenic bacteria are often virulence factors. We describe here the nucleotide sequence and the molecular characterization of the
Photorhabdus
luminescens phlBA
operon, a locus encoding a hemolysin which shows similarities to the
Serratia
type of hemolysins. It belongs to the two-partner secretion (TPS) family of proteins. In low-iron conditions, a transcriptional induction of the
phlBA
operon was observed by using the chloramphenicol acetyltransferase reporter gene, causing an increase in PhlA hemolytic activity compared to iron-rich media. A spontaneous phase variant of
P. luminescens
was deregulated in
phlBA
transcription. The
phlA
mutant constructed by allelic exchange remained highly pathogenic after injection in the lepidopteran
Spodoptera littoralis
, indicating that PhlA hemolysin is not a major virulence determinant. Using the gene encoding green fluorescent protein as a reporter,
phlBA
transcription was observed in hemolymph before insect death. We therefore discuss the possible role of PhlA hemolytic activity in the bacterium-nematode-insect interactions.
The Bacteriophage T4 Transcription Activator MotA Interacts with the Far-C-Terminal Region of the σ70Subunit ofEscherichia coliRNA Polymerase
Authors: Pande Suchira , Makela Anna , Dove Simon L. , Nickels Bryce E. , Hochschild Ann , Hinton Deborah M. 
Published: July 2002

ABSTRACTTranscription from bacteriophage T4 middle promoters usesEscherichia coliRNA polymerase together with the T4 transcriptional activator MotA and the T4 coactivator AsiA. AsiA binds tightly within the C-terminal portion of the σ70subunit of RNA polymerase, while MotA binds to the 9-bp MotA box motif, which is centered at −30, and also interacts with σ70. We show here that the N-terminal half of MotA (MotANTD), which is thought to include the activation domain, interacts with the C-terminal region of σ70in anE. colitwo-hybrid assay. Replacement of the C-terminal 17 residues of σ70with comparable σ38residues abolishes the interaction with MotANTDin this assay, as does the introduction of the amino acid substitution R608C. Furthermore, in vitro transcription experiments indicate that a polymerase reconstituted with a σ70that lacks C-terminal amino acids 604 to 613 or 608 to 613 is defective for MotA-dependent activation. We also show that a proteolyzed fragment of MotA that contains the C-terminal half (MotACTD) binds DNA with aKD(app)that is similar to that of full-length MotA. Our results support a model for MotA-dependent activation in which protein-protein contact between DNA-bound MotA and the far-C-terminal region of σ70helps to substitute functionally for an interaction between σ70and a promoter −35 element.
Properties of 2-Oxoglutarate:Ferredoxin Oxidoreductase from
Thauera aromatica
and Its Role in Enzymatic Reduction of the Aromatic Ring
Authors: Dörner Edith , Boll Matthias 
Published: July 2002

ABSTRACT

Benzoyl coenzyme A (benzoyl-CoA) reductase is a key enzyme in the anaerobic metabolism of aromatic compounds catalyzing the ATP-driven reductive dearomatization of benzoyl-CoA. The enzyme from
Thauera aromatica
uses a reduced 2[4Fe-4S] ferredoxin as electron donor. In this work, we identified 2-oxoglutarate:ferredoxin oxidoreductase (KGOR) as the ferredoxin reducing enzyme. KGOR activity was increased 10- to 50-fold in
T
.
aromatica
cells grown under denitrifying conditions on an aromatic substrate compared to that of cells grown on nonaromatic substrates. The enzyme was purified from soluble extracts by a 60-fold enrichment with a specific activity of 4.8 μmol min
−1
mg
−1
. The native enzyme had a molecular mass of 200 ± 20 kDa (mean ± standard deviation) and consisted of two subunits with molecular masses of 66 and 34 kDa, suggesting an (αβ)
2
composition. The UV/visible spectrum was characteristic for an iron-sulfur protein; the enzyme contained 8.3 ± 0.5 mol of Fe, 7.2 ± 0.5 mol of acid-labile sulfur, and 1.6 ± 0.2 mol of thiamine diphosphate (TPP) per mol of protein. The high specificity for 2-oxoglutarate and the low

K
m

for ferredoxin (∼10 μM) indicated that both are the in vivo substrates of the enzyme. KGOR catalyzed the isotope exchange between
14
CO
2
and C
1
of 2-oxoglutarate, representing a typical reversible partial reaction of 2-oxoacid oxidoreductases. The two genes coding for the two subunits of KGOR were found adjacent to the gene cluster coding for enzymes and ferredoxin of the catabolic benzoyl-CoA pathway. Sequence comparisons with other 2-oxoacid oxidoreductases indicated that KGOR from
T
.
aromatica
belongs to the
Halobacterium
type of 2-oxoacid oxidoreductases, which lack a ferredoxin-like module which contains two additional [4Fe-4S]
1+/2+
clusters/monomer. Using purified KGOR, ferredoxin, and benzoyl-CoA reductase, the 2-oxoglutarate-driven reduction of benzoyl-CoA was shown in vitro. This demonstrates that ferredoxin acts as an electron shuttle between the citric acid cycle and benzoyl-CoA reductase by coupling the oxidation of the end product of the benzoyl-CoA pathway, acetyl-CoA, to the reduction of the aromatic ring.
Rhizobium leguminosarumHas a Second General Amino Acid Permease with Unusually Broad Substrate Specificity and High Similarity to Branched-Chain Amino Acid Transporters (Bra/LIV) of the ABC Family
Authors: Hosie A. H. F. , Allaway D. , Galloway C. S. , Dunsby H. A. , Poole P. S. 
Published: July 2002

ABSTRACTAmino acid uptake byRhizobium leguminosarumis dominated by two ABC transporters, the general amino acid permease (Aap) and the branched-chain amino acid permease (BraRl). Characterization of the solute specificity of BraRlshows it to be the second general amino acid permease ofR. leguminosarum. Although BraRlhas high sequence identity to members of the family of hydrophobic amino acid transporters (HAAT), it transports a broad range of solutes, including acidic and basic polar amino acids (l-glutamate,l-arginine, andl-histidine), in addition to neutral amino acids (l-alanine andl-leucine). While amino and carboxyl groups are required for transport, solutes do not have to be α-amino acids. Consistent with this, BraRlis the first ABC transporter to be shown to transport γ-aminobutyric acid (GABA). All previously identified bacterial GABA transporters are secondary carriers of the amino acid-polyamine-organocation (APC) superfamily. Also, transport by BraRldoes not appear to be stereospecific asdamino acids cause significant inhibition of uptake ofl-glutamate andl-leucine. Unlike all other solutes tested,l-alanine uptake is not dependent on solute binding protein BraCRl. Therefore, a second, unidentified solute binding protein may interact with the BraDEFGRlmembrane complex duringl-alanine uptake. Overall, the data indicate that BraRlis a general amino acid permease of the HAAT family. Furthermore, BraRlhas the broadest solute specificity of any characterized bacterial amino acid transporter.