bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of Antimalarial Action of the Synthetic Trioxolane RBX11160 (OZ277)
Authors: Uhlemann Anne-Catrin , Wittlin Sergio , Matile Hugues , Bustamante Leyla Y. , Krishna Sanjeev 
Published: December 2006

ABSTRACT

RBX11160 (OZ277) is a fully synthetic peroxidic antimalarial in clinical development. To study the possible mechanisms of action of RBX11160, we have examined its ability to inhibit PfATP6, a sarcoplasmic reticulum calcium ATPase and proposed target for semisynthetic peroxidic artemisinin derivatives. RBX11160 inhibits PfATP6 (apparent half-maximal inhibitory constant = 7,700 nM) less potently than artemisinin (79 nM). Inhibition of PfATP6 is abrogated by desferrioxamine, an iron-chelating agent. Consistent with this finding, the killing of
Plasmodium falciparum
organisms by RBX11160 in vitro is antagonized by desferrioxamine. Artesunate and RBX11160 also act antagonistically against
P. falciparum
in vitro. A fluorescent derivative of RBX11160 localizes to the parasite cytosol in some parasites and to the food vacuole in other parasites. These data demonstrate that there are both similarities and differences between the antimalarial properties of RBX11160 and those of semisynthetic antimalarials such as artesunate and artemisinin.
Aspirin Antagonism in Isoniazid Treatment of Tuberculosis in Mice
Authors: Byrne Sean T. , Denkin Steven M. , Zhang Ying 
Published: December 2006

ABSTRACT

Salicylate has previously been shown to reduce the susceptibility of
Mycobacterium tuberculosis
to several drugs in vitro. In this study, aspirin, a salicylate anti-inflammatory, antagonized isoniazid treatment of murine pulmonary tuberculosis, whereas the nonsalicylate ibuprofen did not. These results may have implications on concurrent administration of anti-inflammatory and antituberculosis drugs.
Relationships between
Mycobacterium
Isolates from Patients with Pulmonary Mycobacterial Infection and Potting Soils
Authors: De Groote Mary Ann , Pace Norman R. , Fulton Kayte , Falkinham Joseph O. 
Published: December 2006

ABSTRACT

High numbers of mycobacteria, including known pathogenic species such as
Mycobacterium avium
,
Mycobacterium intracellulare
, and
Mycobacterium chelonae
, were recovered from aerosols produced by pouring commercial potting soil products and potting soil samples provided by patients with pulmonary mycobacterial infections. The dominant mycobacteria in the soil samples corresponded to the dominant species implicated clinically. Profiles of large restriction fragments obtained by pulsed-field gel electrophoresis demonstrated a closely related pair of
M. avium
isolates recovered from a patient and from that patient's own potting soil. Thus, potting soils are potential sources of infection by environmental mycobacteria. Use of dust-excluding masks should be considered during potting or other activities that generate aerosol with soil.
Isolation and Molecular Characterization of Chitinase-Deficient
Bacillus licheniformis
Strains Capable of Deproteinization of Shrimp Shell Waste To Obtain Highly Viscous Chitin
Authors: Waldeck Jens , Daum Gabriele , Bisping Bernward , Meinhardt Friedhelm 
Published: December 2006

ABSTRACT

Proteolytic but chitinase-deficient microbial cultures were isolated from shrimp shell waste and characterized. The most efficient isolate was found to be a mixed culture consisting of two
Bacillus licheniformis
strains, which were first determined microscopically and physiologically. Molecular characterization was carried out by sequencing the 16S rRNA gene of both strains. According to the residual protein and ash content, the chitin obtained by fermentation of such a mixed culture was found to be comparable to a commercially available, chemically processed product. However, the strikingly high viscosity (80 versus 10 mPa of the commercially available sample) indicates its superior quality. The two strains differed in colony morphology and in their secretion capabilities for degradative extracellular enzymes. Sequencing of the loci encoding amylase, cellulase, chitinases, and proteases, as well as the
degS/degU
operon, which is instrumental in the regulation of degradative enzymes, and the
pga
operon, which is responsible for polyglutamic acid production, revealed no differences. However, a frameshift mutation in
chiA
, encoding a chitinase, was validated for both strains, providing an explanation for the ascertained absence of chitinolytic activities and the concomitant possibility of producing highly viscous chitin in a fermentational deproteinization process.
A Naturally Occurring Novel Allele of
Escherichia coli
Outer Membrane Protein A Reduces Sensitivity to Bacteriophage
Authors: Power Michelle L. , Ferrari Belinda C. , Littlefield-Wyer Jane , Gordon David M. , Slade Martin B. , Veal Duncan A. 
Published: December 2006

ABSTRACT

A novel
Escherichia coli
outer membrane protein A (OmpA) was discovered through a proteomic investigation of cell surface proteins. DNA polymorphisms were localized to regions encoding the protein's surface-exposed loops which are known phage receptor sites. Bacteriophage sensitivity testing indicated an association between bacteriophage resistance and isolates having the novel
ompA
allele.
Aerobic Growth of
Escherichia coli
with 2,4,6-Trinitrotoluene (TNT) as the Sole Nitrogen Source and Evidence of TNT Denitration by Whole Cells and Cell-Free Extracts
Authors: Stenuit Ben , Eyers Laurent , Rozenberg Raoul , Habib-Jiwan Jean-Louis , Agathos Spiros N. 
Published: December 2006

ABSTRACT

Escherichia coli
grew aerobically with 2,4,6-trinitrotoluene (TNT) as sole nitrogen source and caused TNT's partial denitration. This reaction was enhanced in nongrowing cell suspensions with 0.516 mol nitrite released per mol TNT. Cell extracts denitrated TNT in the presence of NAD(P)H. Isomers of amino-dimethyl-tetranitrobiphenyl were detected and confirmed with U-
15
N-labeled TNT.
Resistance of
Listeria monocytogenes
Biofilms to Sanitizing Agents in a Simulated Food Processing Environment
Authors: Pan Y. , Breidt F. , Kathariou S. 
Published: December 2006

ABSTRACT

The objective of this study was to evaluate the resistance of biofilms of
Listeria monocytogenes
to sanitizing agents under laboratory conditions simulating a food processing environment. Biofilms were initially formed on stainless steel and Teflon coupons using a five-strain mixture of
L. monocytogenes
. The coupons were then subjected to repeated 24-h daily cycles. Each cycle consisted of three sequential steps: (i) a brief (60 s) exposure of the coupons to a sanitizing agent (a mixture of peroxides) or saline as a control treatment, (ii) storage of the coupons in sterile plastic tubes without any nutrients or water for 15 h, (iii) and incubation of the coupons in diluted growth medium for 8 h. This regimen was repeated daily for up to 3 weeks and was designed to represent stresses encountered by bacteria in a food processing environment. The bacteria on the coupons were reduced in number during the first week of the simulated food processing (SFP) regimen, but then adapted to the stressful conditions and increased in number. Biofilms repeatedly exposed the peroxide sanitizer in the SFP regimen developed resistance to the peroxide sanitizer as well as other sanitizers (quaternary ammonium compounds and chlorine). Interestingly, cells that were removed from the biofilms on peroxide-treated and control coupons were not significantly different in their resistance to sanitizing agents. These data suggest that the resistance of the treated biofilms to sanitizing agents may be due to attributes of extracellular polymeric substances and is not an intrinsic attribute of the cells in the biofilm.
Induction of Heavy-Metal-Transporting CPX-Type ATPases during Acid Adaptation in
Lactobacillus bulgaricus
Authors: Penaud S. , Fernandez A. , Boudebbouze S. , Ehrlich S. D. , Maguin E. , van de Guchte M. 
Published: December 2006

ABSTRACT

Lactobacillus bulgaricus
is a lactic acid bacteria (LAB) that, through the production of lactic acid, gradually acidifies its environment during growth. In the course of this process,
L. bulgaricus
acquires an improved tolerance to acidity. A survey of the recently established genome sequence shows that this bacterium possesses few of the pH control functions that have been described in other LAB and raises the question of what other mechanisms could be involved in its adaptation to the decreasing environmental pH. In some bacteria other than LAB, ion transport systems have been implicated in acid adaptation. We therefore studied the expression of this type of transport system during acid adaptation in
L. bulgaricus
by reverse transcription and real-time quantitative PCR and mapped transcription start sites. Intriguingly, the most significantly induced were three ATPases carrying the CPX signature of heavy-metal transporters. Protein homology and the presence of a conserved sequence motif in the promoter regions of the genes encoding these proteins strongly suggest that they are involved in copper homeostasis. Induction of this system is thought to assist in avoiding indirect damage that could result from medium acidification.
Different Levels of Transcriptional Regulation Due to Trophic Constraints in the Reduced Genome of
Buchnera aphidicola
APS
Authors: Reymond Nancie , Calevro Federica , Viñuelas José , Morin Nicolas , Rahbé Yvan , Febvay Gérard , Laugier Christian , Douglas Angela , Fayard Jean-Michel , Charles Hubert 
Published: December 2006

ABSTRACT

Symbiotic associations involving intracellular microorganisms and animals are widespread, especially for species feeding on poor or unbalanced diets.
Buchnera aphidicola
, the obligate intracellular bacterium associated with most aphid species, provides its hosts with essential amino acids (EAAs), nutrients in short supply in the plant phloem sap. The
Buchnera
genome has undergone severe reductions during intracellular evolution. Genes for EAA biosynthesis are conserved, but most of the transcriptional regulatory elements are lost. This work addresses two main questions: is transcription in
Buchnera
(i) regulated and (ii) scaled to aphid EAA demand? Two microarray experiments were designed for profiling the gene expression in
Buchnera
. The first one was characterized by a specific depletion of tyrosine and phenylalanine in the aphid diet, and the second experiment combined a global diminution of EAAs in the aphid diet with a sucrose concentration increase to manipulate the aphid growth rate. Aphid biological performance and budget analysis (the balance between EAAs provided by the diet and those synthesized by
Buchnera
) were performed to quantify the nutritional demand from the aphids toward their symbiotic bacteria. Despite the absence of known regulatory elements, a significant transcriptional regulation was observed at different levels of organization in the
Buchnera
genome: between genes, within putative transcription units, and within specific metabolic pathways. However, unambiguous evidence for transcriptional changes underpinning the scaling of EAA biosynthesis to aphid demand was not obtained. The phenotypic relevance of the transcriptional response from the reduced genome of
Buchnera
is addressed.
Molecular Detection of Epiphytic
Acaryochloris
spp. on Marine Macroalgae
Authors: Ohkubo Satoshi , Miyashita Hideaki , Murakami Akio , Takeyama Haruko , Tsuchiya Tohru , Mimuro Mamoru 
Published: December 2006

ABSTRACT

A molecular method for detecting the epiphyte community on marine macroalgae was developed by using PCR-denaturing gradient gel electrophoresis. Selective amplification of 16S rRNA gene fragments from either cyanobacteria or algal plastids improved the detection of minor epiphytes. Two phylotypes of
Acaryochloris
, a chlorophyll
d
-containing cyanobacterium, were found not only on red macroalgae but also on green and brown macroalgae.
Virus-Specific Responses of
Heterosigma akashiwo
to Infection
Authors: Lawrence Janice E. , Brussaard Corina P. D. , Suttle Curtis A. 
Published: December 2006

ABSTRACT

We used flow cytometry to examine the process of cell death in the bloom-forming alga
Heterosigma akashiwo
during infection by a double-stranded DNA virus (OIs1) and a single-stranded RNA virus (
H. akashiwo
RNA virus [HaRNAV]). These viruses were isolated from the same geographic area and infect the same strain of
H. akashiwo
. By use of the live/dead stains fluorescein diacetate and SYTOX green as indicators of cellular physiology, cells infected with OIs1 showed signs of infection earlier than HaRNAV-infected cultures (6 to 17 h versus 23 to 29 h). Intracellular esterase activity was lost prior to increased membrane permeability during infection with OIs1, while the opposite was seen with HaRNAV-infected cultures. In addition, OIs1-infected cells accumulated in the cultures while HaRNAV-infected cells rapidly disintegrated. Progeny OIs1 viruses consisted of large and small morphotypes with estimated latent periods of 11 and 17 h, respectively, and about 1,100 and 16,000 viruses produced per cell, respectively. In contrast, HaRNAV produced about 21,000 viruses per cell and had a latent period of 29 h. This study reveals that the characteristics of viral infection in algae are virus dependent and therefore are variable among viruses infecting the same species. This is an important consideration for ecosystem modeling exercises; calculations based on in situ measurements of algal physiology must be sensitive to the diverse responses of algae to viral infection.
Evidence for Horizontal Gene Transfer as Origin of Putrescine Production in
Oenococcus oeni
RM83
Authors: Marcobal Ángela , de las Rivas Blanca , Moreno-Arribas M. Victoria , Muñoz Rosario 
Published: December 2006

ABSTRACT

The nucleotide sequence of a 17.2-kb chromosomal DNA fragment containing the
odc
gene encoding ornithine decarboxylase has been determined in the putrescine producer
Oenococcus oeni
RM83. This DNA fragment contains 13 open reading frames, including genes coding for five transposases and two phage proteins. This description might represent the first evidence of a horizontal gene transfer event as the origin of a biogenic amine biosynthetic locus.
Intracellular Accumulation of Trehalose Protects
Lactococcus lactis
from Freeze-Drying Damage and Bile Toxicity and Increases Gastric Acid Resistance
Authors: Termont Sofie , Vandenbroucke Klaas , Iserentant Dirk , Neirynck Sabine , Steidler Lothar , Remaut Erik , Rottiers Pieter 
Published: December 2006

ABSTRACT

Interleukin-10 (IL-10) is a promising candidate for the treatment of inflammatory bowel disease. Intragastric administration of
Lactococcus lactis
genetically modified to secrete IL-10 in situ in the intestine was shown to be effective in healing and preventing chronic colitis in mice. However, its use in humans is hindered by the sensitivity of
L. lactis
to freeze-drying and its poor survival in the gastrointestinal tract. We expressed the trehalose synthesizing genes from
Escherichia coli
under control of the nisin-inducible promoter in
L. lactis
. Induced cells accumulated intracellular trehalose and retained nearly 100% viability after freeze-drying, together with a markedly prolonged shelf life. Remarkably, cells producing trehalose were resistant to bile, and their viability in human gastric juice was enhanced. None of these effects were seen with exogenously added trehalose. Trehalose accumulation did not interfere with IL-10 secretion or with therapeutic efficacy in murine colitis. The newly acquired properties should enable a larger proportion of the administered bacteria to reach the gastrointestinal tract in a bioactive form, providing a means for more effective mucosal delivery of therapeutics.
Metabolism of Thioamides byRalstonia pickettiiTA
Authors: Dodge Anthony G. , Richman Jack E. , Johnson Gilbert , Wackett Lawrence P. 
Published: December 2006

ABSTRACTInformation on bacterial thioamide metabolism has focused on transformation of the antituberculosis drug ethionamide and related compounds byMycobacterium tuberculosis. To study this metabolism more generally, a bacterium that grew using thioacetamide as the sole nitrogen source was isolated via enrichment culture. The bacterium was identified asRalstonia pickettiiand designated strain TA. Cells grown on thioacetamide also transformed other thioamide compounds. Transformation of the thioamides tested was dependent on oxygen. During thioamide degradation, sulfur was detected in the medium at the oxidation level of sulfite, further suggesting an oxygenase mechanism.R. pickettiiTA did not grow on thiobenzamide as a nitrogen source, but resting cells converted thiobenzamide to benzamide, with thiobenzamide S-oxide and benzonitrile detected as intermediates. Thioacetamide S-oxide was detected as an intermediate during thioacetamide degradation, but the only accumulating metabolite of thioacetamide was identified as 3,5-dimethyl-1,2,4-thiadiazole, a compound shown to derive from spontaneous reaction of thioacetamide and oxygenated thioacetamide species. This dead-end metabolite accounted for only ca. 12% of the metabolized thioacetamide. Neither acetonitrile nor acetamide was detected during thioacetamide degradation, butR. pickettiigrew on both compounds as nitrogen and carbon sources. It is proposed thatR. pickettiiTA degrades thioamides via a mechanism involving consecutive oxygenations of the thioamide sulfur atom.
Identification of Novel Benzoylformate Decarboxylases by Growth Selection
Authors: Henning Helge , Leggewie Christian , Pohl Martina , Müller Michael , Eggert Thorsten , Jaeger Karl-Erich 
Published: December 2006

ABSTRACT

A growth selection system was established using
Pseudomonas putida
, which can grow on benzaldehyde as the sole carbon source. These bacteria presumably metabolize benzaldehyde via the β-ketoadipate pathway and were unable to grow in benzoylformate-containing selective medium, but the growth deficiency could be restored by expression in
trans
of genes encoding benzoylformate decarboxylases. The selection system was used to identify three novel benzoylformate decarboxylases, two of them originating from a chromosomal library of
P. putida
ATCC 12633 and the third from an environmental-DNA library. The novel
P. putida
enzymes BfdB and BfdC exhibited 83% homology to the benzoylformate decarboxylase from
P. aeruginosa
and 63% to the enzyme MdlC from
P. putida
ATCC 12633, whereas the metagenomic BfdM exhibited 72% homology to a putative benzoylformate decarboxylase from
Polaromonas naphthalenivorans
. BfdC was overexpressed in
Escherichia coli
, and the enzymatic activity was determined to be 22 U/ml using benzoylformate as the substrate. Our results clearly demonstrate that
P. putida
KT2440 is an appropriate selection host strain suitable to identify novel benzoylformate decarboxylase-encoding genes. In principle, this system is also applicable to identify a broad range of different industrially important enzymes, such as benzaldehyde lyases, benzoylformate decarboxylases, and hydroxynitrile lyases, which all catalyze the formation of benzaldehyde.
Characterization of a
Vibrio alginolyticus
Strain, Isolated from Alaskan Oysters, Carrying a Hemolysin Gene Similar to the Thermostable Direct Hemolysin-Related Hemolysin Gene (
trh
) of
Vibrio parahaemolyticus
Authors: González-Escalona Narjol , Blackstone George M. , DePaola Angelo 
Published: December 2006

ABSTRACT

A
Vibrio
strain isolated from Alaskan oysters and classified by its biochemical characteristics as
Vibrio alginolyticus
possessed a thermostable direct hemolysin-related hemolysin (
trh
) gene previously reported only in
Vibrio parahaemolyticus
. This
trh
-like gene was cloned and sequenced and was 98% identical to the
trh2
gene of
V. parahaemolyticus
. This gene seems to be functional since it was transcriptionally active in early-stationary-phase growing cells. To our knowledge, this is the first report of
V. alginolyticus
possessing a
trh
gene.
Tvbgn3, a β-1,6-Glucanase from the Biocontrol Fungus
Trichoderma virens
, Is Involved in Mycoparasitism and Control of
Pythium ultimum
Authors: Djonović Slavica , Pozo Maria J. , Kenerley Charles M. 
Published: December 2006

ABSTRACT

Even though β-1,6-glucanases have been purified from several filamentous fungi, the physiological function has not been conclusively established for any species. In the present study, the role of Tvbgn3, a β-1,6-glucanase from
Trichoderma virens
, was examined by comparison of wild-type (WT) and transformant strains in which Tv
bgn3
was disrupted (GKO) or constitutively overexpressed (GOE). Gene expression analysis revealed induction of Tv
bgn3
in the presence of host fungal cell walls, indicating regulation during mycoparasitism. Indeed, while deletion or overexpression of Tv
bgn3
had no evident effect on growth and development, GOE and GKO strains showed an enhanced or reduced ability, respectively, to inhibit the growth of the plant pathogen
Pythium ultimum
compared to results with the WT. The relevance of this activity in the biocontrol ability of
T. virens
was confirmed in plant bioassays. Deletion of the gene resulted in levels of disease protection that were significantly reduced from WT levels, while GOE strains showed a significantly increased biocontrol capability. These results demonstrate the involvement of β-1,6-glucanase in mycoparasitism and its relevance in the biocontrol activity of
T. virens
, opening a new avenue for biotechnological applications.
Diversity and Significance of Mold Species in Norwegian Drinking Water
Authors: Hageskal Gunhild , Knutsen Ann Kristin , Gaustad Peter , de Hoog G. Sybren , Skaar Ida 
Published: December 2006

ABSTRACT

In order to determine the occurrence, distribution, and significance of mold species in groundwater- and surface water-derived drinking water in Norway, molds isolated from 273 water samples were identified. Samples of raw water, treated water, and water from private homes and hospital installations were analyzed by incubation of 100-ml membrane-filtered samples on dichloran-18% glycerol agar. The total count (number of CFU per 100 ml) of fungal species and the species diversity within each sample were determined. The identification of mold species was based on morphological and molecular methods. In total, 94 mold species belonging to 30 genera were identified. The mycobiota was dominated by species of
Penicillium
,
Trichoderma
, and
Aspergillus
, with some of them occurring throughout the drinking water system. Several of the same species as isolated from water may have the potential to cause allergic reactions or disease in humans. Other species are common contaminants of food and beverages, and some may cause unwanted changes in the taste or smell of water. The present results indicate that the mycobiota of water should be considered when the microbiological safety and quality of drinking water are assessed. In fact, molds in drinking water should possibly be included in the Norwegian water supply and drinking water regulations.