bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential Roles of the ChiB Chitinase in Autolysis and Cell Death of
Aspergillus nidulans
Authors: Shin Kwang-Soo , Kwon Nak-Jung , Kim Young Hwan , Park Hee-Soo , Kwon Gi-Seok , Yu Jae-Hyuk 
Published: March 2009

ABSTRACT

Autolysis is a natural event that occurs in most filamentous fungi. Such self-degradation of fungal cells becomes a predominant phenomenon in the absence of the regulator of G protein signaling FlbA in
Aspergillus nidulans
. Among a number of potential hydrolytic enzymes in the
A. nidulans
genome, the secreted endochitinase ChiB was shown to play a major role in autolysis. In this report, we investigate the roles of ChiB in fungal autolysis and cell death processes through genetic, biochemical, and cellular analyses using a set of critical mutants. Determination of mycelial mass revealed that, while the
flbA
deletion (Δ
flbA
) mutant autolyzed completely after a 3-day incubation, the Δ
flbA
Δ
chiB
double mutant escaped from hyphal disintegration. These results indicate that ChiB is necessary for the Δ
flbA
-induced autolysis. However, importantly, both Δ
flbA
and Δ
flbA
Δ
chiB
strains displayed dramatically reduced cell viability compared to the wild type. These imply that ChiB is dispensable for cell death and that autolysis and cell death are separate processes. Liquid chromatography-tandem mass spectrometry analyses of the proteins that accumulate at high levels in the Δ
flbA
and Δ
flbA
Δ
chiB
mutants identify chitinase (ChiB), dipeptidyl peptidase V (DppV),
O
-glycosyl compound hydrolase, β-
N
-acetylhexosaminidase (NagA), and
myo
-inositol-1-phosphate synthase (InoB). Functional characterization of these four genes reveals that the deletion of
nagA
results in reduced cell death. A working model bridging G protein signaling and players in autolysis/cell death is proposed.
Type II NADH Dehydrogenase Inhibitor 1-Hydroxy-2-Dodecyl- 4(1H)Quinolone Leads to Collapse of Mitochondrial Inner- Membrane Potential and ATP Depletion inToxoplasma gondii
Authors: Lin San San , Groß Uwe , Bohne Wolfgang 
Published: March 2009

ABSTRACTThe apicomplexan parasiteToxoplasma gondiiexpresses type II NADH dehydrogenases (NDH2s) instead of canonical complex I at the inner mitochondrial membrane. These non-proton-pumping enzymes are considered to be promising drug targets due to their absence in mammalian cells. We recently showed by inhibition kinetics thatT. gondiiNDH2-I is a target of the quinolone-like compound 1-hydroxy-2-dodecyl-4(1H)quinolone (HDQ), which inhibitsT. gondiireplication in the nanomolar range. In this study, the cationic fluorescent probes Mitotracker and DiOC6(3) (3,3′-dihexyloxacarbocyanine iodine) were used to monitor the influence of HDQ on the mitochondrial inner membrane potential (ΔΨm) inT. gondii. Real-time imaging revealed that nanomolar HDQ concentrations led to a ΔΨm collapse within minutes, which is followed by severe ATP depletions of 30% after 1 h and 70% after 24 h. ΔΨm depolarization was attenuated when substrates for other dehydrogenases that can donate electrons to ubiquinone were added to digitonin-permeabilized cells or when infected cultures were treated with the Fo-ATPase inhibitor oligomycin. A prolonged treatment with sublethal concentrations of HDQ induced differentiation into bradyzoites. This dormant stage is likely to be less dependent on the ΔΨm, since ΔΨm-positive parasites were found at a significantly lower frequency in alkaline-pH-induced bradyzoites than in tachyzoites. Together, our studies reveal that oxidative phosphorylation is essential for maintaining the ATP level in the fast-growing tachyzoite stage and that HDQ interferes with this pathway by inhibiting the electron transport chain at the level of ubiquinone reduction.
Nitrite Transport Activity of the ABC-Type Cyanate Transporter of the Cyanobacterium
Synechococcus elongatus
Authors: Maeda Shin-ichi , Omata Tatsuo 
Published: March 2009

ABSTRACT

In addition to the ATP-binding cassette (ABC)-type nitrate/nitrite-bispecific transporter, which has a high affinity for both substrates (

K
m

, ∼1 μM),
Synechococcus elongatus
has an active nitrite transport system with an apparent

K
m

(NO
2
−
) value of 20 μM. We found that this activity depends on the
cynABD
genes, which encode a putative cyanate (NCO
−
) ABC-type transporter. Accordingly, nitrite transport by CynABD was competitively inhibited by NCO
−
with a

K
i

value of 0.025 μM. The transporter was induced under conditions of nitrogen deficiency, and the induced cells showed a
V
max
value of 11 to 13 μmol/mg of chlorophyll per h for cyanate or nitrite, which could supply ∼30% of the amount of nitrogen required for optimum growth. Its relative specificity for the substrates and regulation at transcriptional and posttranslational levels suggested that the physiological role of the bispecific cyanate/nitrite transporter in
S. elongatus
is to allow nitrogen-deficient cells to assimilate low concentrations of cyanate in the medium. Its contribution to nitrite assimilation was significant in a mutant lacking the ABC-type nitrate/nitrite transporter, suggesting a possible role for CynABD in nitrite assimilation by cyanobacterial species that lack another high-affinity mechanism(s) for nitrite transport.
A Novel Nitroreductase of
Staphylococcus aureus
with
S
-Nitrosoglutathione Reductase Activity
Authors: Tavares Ana Filipa N. , Nobre Lígia S. , Melo Ana M. P. , Saraiva Lígia M. 
Published: March 2009

ABSTRACT

In this report we show that inactivation of the putative nitroreductase SA0UHSC_00833 (
ntrA
) increases the sensitivity of
Staphylococcus aureus
to
S
-nitrosoglutathione (GSNO) and augments its resistance to nitrofurans.
S. aureus
NtrA is a bifunctional enzyme that exhibits nitroreductase and GSNO reductase activity. A phylogenetic analysis suggests that NtrA is a member of a novel family of nitroreductases that seems to play a dual role in vivo, promoting nitrofuran activation and protecting the cell against transnitrosylation.
Structural Requirements of thePseudomonasQuinolone Signal for Membrane Vesicle Stimulation
Authors: Mashburn-Warren Lauren , Howe Jörg , Brandenburg Klaus , Whiteley Marvin 
Published: March 2009

ABSTRACTPseudomonas aeruginosaproduces the quorum signal 2-heptyl-3-hydroxy-4-quinolone (Pseudomonasquinolone signal), which is important for stimulating outer membrane vesicle (MV) formation. Here we describe the importance of the 3-hydroxyl and 2-alkyl chain for MV production and the length of the 2-alkyl chain for association with MVs.
Identification and Characterization of a Novel Multidrug Resistance Operon,mdtRP(yusOP), ofBacillus subtilis
Authors: Kim Ji-Yun , Inaoka Takashi , Hirooka Kazutaka , Matsuoka Hiroshi , Murata Makiko , Ohki Reiko , Adachi Yoshikazu , Fujita Yasutaro , Ochi Kozo 
Published: March 2009

ABSTRACTUsing comparative genome sequencing analysis, we identified a novel mutation inBacillus subtilisthat confers a low level of resistance to fusidic acid. This mutation was located in themdtR(formerlyyusO) gene, which encodes a MarR-type transcriptional regulator, and conferred a low level of resistance to several antibiotics, including novobiocin, streptomycin, and actinomycin D. Transformation experiments showed that thismdtRmutation was responsible for multidrug resistance. Northern blot analysis revealed that the downstream genemdtP(formerlyyusP), which encodes a multidrug efflux transporter, is cotranscribed withmdtRas an operon. Disruption of themdtPgene completely abolished the multidrug resistance phenotype observed in themdtRmutant. DNase I footprinting and primer extension analyses demonstrated that the MdtR protein binds directly to themdtRPpromoter, thus leading to repression of its transcription. Moreover, gel mobility shift analysis indicated that an Arg83 → Lys or Ala67 → Thr substitution in MdtR significantly reduces binding affinity to DNA, resulting in derepression ofmdtRPtranscription. Low concentrations of fusidic acid induced the expression ofmdtP, although the level ofmdtPexpression was much lower than that in themdtRdisruptant. These findings indicate that the MdtR protein is a repressor of themdtRPoperon and that the MdtP protein functions as a multidrug efflux transporter inB. subtilis.
Regulation of Superoxide Dismutase (sod) Genes by SarA inStaphylococcus aureus
Authors: Ballal Anand , Manna Adhar C. 
Published: March 2009

ABSTRACTThe scavenging of reactive oxygen species (ROS) within cells is regulated by several interacting factors, including transcriptional regulators. Involvement ofsarAfamily genes in the regulation of proteins involved in the scavenging of ROS is largely unknown. In this report, we show that under aerobic conditions, the levels ofsodMand sodAtranscription, in particular thesodMtranscript, are markedly enhanced in thesarAmutant among the testedsarAfamily mutants. Increased levels ofsodexpression returned to near the parental level in a single-copysarAcomplemented strain. Under microaerophilc conditions, transcription of bothsodMandsodAwas considerably enhanced in thesarAmutant compared to the wild-type strain. Various genotypic, phenotypic, and DNA binding studies confirmed the involvement of SarA in the regulation ofsodtranscripts in different strains ofStaphylococcus aureus. ThesodAmutant was sensitive to an oxidative stress-inducing agent, methyl viologen, but thesarA sodAdouble mutant was more resistant to the same stressor than the singlesodAmutant. These results suggest that overexpression of SodM, which occurs in thesarAbackground, can rescue the methyl viologen-sensitive phenotype observed in the absence of thesodAgene. Analysis with various oxidative stress-inducing agents indicates that SarA may play a greater role in modulating oxidative stress resistance inS. aureus. This is the first report that demonstrates the direct involvement of a regulatory protein (SarA) in control ofsodexpression inS. aureus.
Crystal Structure of a Chimeric Receptor Binding Protein Constructed from Two Lactococcal Phages
Authors: Siponen Marina , Spinelli Silvia , Blangy Stéphanie , Moineau Sylvain , Cambillau Christian , Campanacci Valérie 
Published: March 2009

ABSTRACT

Lactococcus lactis
, a gram-positive bacterium widely used by the dairy industry to manufacture cheeses, is subject to infection by a diverse population of virulent phages. We have previously determined the structures of three receptor binding proteins (RBPs) from lactococcal phages TP901-1, p2, and bIL170, each of them having a distinct host range. Virulent phages p2 and bIL170 are classified within the 936 group, while the temperate phage TP901-1 is a member of the genetically distinct P335 polythetic group. These RBPs comprise three domains: the N-terminal domain, binding to the virion particle; a β-helical linker domain; and the C-terminal domain, bearing the receptor binding site used for host recognition. Here, we have designed, expressed, and determined the structure of an RBP chimera in which the N-terminal and linker RBP domains of phage TP901-1 (P335) are fused to the C-terminal RBP domain of phage p2 (936). This chimera exhibits a stable structure that closely resembles the parental structures, while a slight displacement of the linker made RBP domain adaptation efficient. The receptor binding site is structurally indistinguishable from that of native p2 RBP and binds glycerol with excellent affinity.
Thioredoxins in Redox Maintenance and Survival during Oxidative Stress ofBacteroides fragilis
Authors: Reott Michael A. , Parker Anita C. , Rocha Edson R. , Smith C. Jeffrey 
Published: March 2009

ABSTRACTThe anaerobeBacteroides fragilisis a gram-negative, opportunistic pathogen that is highly aerotolerant and can persist in aerobic environments for extended periods. In this study, the sixB. fragilisthioredoxins (Trxs) were investigated to determine their role during oxidative stress. Phylogenetic analyses of Trx protein sequences indicated that four of the six Trxs (TrxA, TrxC, TrxD, and TrxF) belong to the M-type Trx class but were associated with two different M-type lineages. TrxE and TrxG were most closely associated to Y-type Trxs found primarily in cyanobacteria. Single and multipletrxgene deletions were generated to determine functional differences between the Trxs. ThetrxAgene was essential, but no anaerobic growth defects were observed for any other singletrxdeletion or for the ΔtrxCΔtrxD::cfxA ΔtrxE ΔtrxF ΔtrxGquintuple mutant. Regulation of thetrxgenes was linked to the oxidative stress response, and all were induced by aerobic conditions. The ΔtrxCΔtrxEΔtrxFΔtrxGand the ΔtrxCΔtrxD::cfxA ΔtrxE ΔtrxF ΔtrxGmultiple deletion strains were impaired during growth in oxidized media, but singletrxgene mutants did not have a phenotype in this assay. TrxD was protective during exposure to the thiol oxidant diamide, and expression oftrxDwas induced by diamide. Diamide-induced expression oftrxC,trxE, andtrxFincreased significantly in atrxDmutant strain, suggesting that there is some capacity for compensation in this complex Trx system. These data provide insight into the role of individual Trxs in theB. fragilisoxidative stress response.
Large Intergenic Cruciform-Like Supermotifs in the
Lactobacillus plantarum
Genome
Authors: Wels Michiel , Bongers Roger S. , Boekhorst Jos , Molenaar Douwe , Sturme Mark , de Vos Willem M. , Siezen Roland J. , Kleerebezem Michiel 
Published: March 2009

ABSTRACT

Twenty-four
Lactobacillus plantarum
supermotifs (LPSMs) with lengths from ∼800 to 1,000 nucleotides were identified in the
L. plantarum
genome. LPSMs were conserved in other
L. plantarum
strains but not in other species. Secondary structure analysis predicted that LPSMs may fold into cruciform-like structures. Preliminary experiments indicate that the LPSMs are transcribed.
Oxidation of Cysteine 645 of Cobalamin-Independent Methionine Synthase Causes a Methionine Limitation in
Escherichia coli
Authors: Hondorp Elise R. , Matthews Rowena G. 
Published: March 2009

ABSTRACT

Cobalamin-independent methionine synthase (MetE) catalyzes the final step in
Escherichia coli
methionine biosynthesis but is inactivated under oxidative conditions, triggering a methionine deficiency. This study demonstrates that the mutation of MetE cysteine 645 to alanine completely eliminates the methionine auxotrophy imposed by diamide treatment, suggesting that modulation of MetE activity via cysteine 645 oxidation has significant physiological consequences for oxidatively stressed cells.
Automation of the BD GeneOhm Methicillin-Resistant
Staphylococcus aureus
Assay for High-Throughput Screening of Nasal Swab Specimens
Authors: Wang Xue-Ping , Ginocchio Christine C. 
Published: March 2009

ABSTRACT

This study demonstrated that an automated version of the BD-GeneOhm methicillin-resistant
Staphylococcus aureus
(MRSA) assay (BD-MRSA), using achromopeptidase sample lysis and PCR setup performed on the Hamilton MICROLAB STAR
let
(Auto-MRSA), gave results comparable to those obtained with BD-MRSA. The positive- and negative-result concordance rates and overall concordance of BD-MRSA and Auto-MRSA were 98.2, 97.7, and 97.6%, respectively. Auto-MRSA required 60% less technical time than BD-MRSA, and the time required to obtain results was 50% of that required for BD-MRSA. Auto-MRSA provides a reliable, robust system for high-volume clinical use.
Early and Strong Immune Responses Are Associated with Control of Viral Replication and Recovery in Lassa Virus-Infected Cynomolgus Monkeys
Authors: Baize Sylvain , Marianneau Philippe , Loth Philippe , Reynard Stéphanie , Journeaux Alexandra , Chevallier Michèle , Tordo Noël , Deubel Vincent , Contamin Hugues 
Published: March 2009

ABSTRACT

Lassa virus causes a hemorrhagic fever endemic in West Africa. The pathogenesis and the immune responses associated with the disease are poorly understood, and no vaccine is available. We followed virological, pathological, and immunological markers associated with fatal and nonfatal Lassa virus infection of cynomolgus monkeys. The clinical picture was characterized by fever, weight loss, depression, and acute respiratory syndrome. Transient thrombocytopenia and lymphopenia, lymphadenopathy, splenomegaly, infiltration of mononuclear cells, and alterations of the liver, lungs, and endothelia were observed. Survivors exhibited fewer lesions and a lower viral load than nonsurvivors. Although all animals developed strong humoral responses, antibodies appeared more rapidly in survivors and were directed against GP
1
, GP
2
, and NP. Type I interferons were detected early after infection in survivors but only during the terminal stages in fatalities. The mRNAs for CXCL10 (IP-10) and CXCL11 (I-TAC) were abundant in peripheral blood mononuclear cells and lymph nodes from infected animals, but plasma interleukin-6 was detected only in fatalities. In survivors, high activated-monocyte counts were followed by a rise in the total number of circulating monocytes. Activated T lymphocytes circulated in survivors, whereas T-cell activation was low and delayed in fatalities. In vitro stimulation with inactivated Lassa virus induced activation of T lymphocytes from all infected monkeys, but only lymphocytes from survivors proliferated. Thus, early and strong immune responses and control of viral replication were associated with recovery, whereas fatal infection was characterized by major alterations of the blood formula and, in organs, weak immune responses and uncontrolled viral replication.
A case-crossover study on transient risk factors of work-related eye injuries
Authors: Chen S-Y , Fong P-C , Lin S-F , Chang C-H , Chan C-C 
Published: March 2009

Objectives:To investigate modifiable risk and preventive factors of work-related eye injuries.Methods:A case-crossover study conducted to explore the associations between transient risk factors and work-related eye injuries. Patients seen at seven medical centres in Taiwan with work-related eye injuries over a 4-year period were enrolled in the study. Clinical information was collected from medical charts and detailed information on exposure to eight potentially modifiable factors during the 60 minutes prior to the occurrence of each injury, as well as during the same time interval on the last work day prior to the injury, were obtained using questionnaire surveys. Matched-pair interval analysis was adopted to assess the odds ratios (ORs) for work-related eye injuries given exposure to the eight modifiable factors.Results:A total of 283 subjects were interviewed. Most of these injured workers were young, male, and self-employed or small enterprise workers. The most common injury type was photokeratitis (33.2%), mainly caused by welding (30.4%). The OR for a work-related eye injury was increased with the performance of an unfamiliar task (57.0), operation of a faulty tool or piece of equipment (48.5), distractions (24.0), being rushed (13.0), or fatigued (10.0), and a poor work environment (4.3). Wearing eye protection devices was found to have a significant protective effect on workers who might otherwise have been exposed to eye injuries (OR = 0.4; 95% CI 0.2 to 0.7).Conclusion:Potential modifiable risk and preventive factors for work-related eye injuries were identified using a case-crossover study. This information should be helpful in the development of preventive strategies.
On the Nature of Soil Moisture in Land Surface Models
Authors: Koster Randal D. , Guo Zhichang , Yang Rongqian , Dirmeyer Paul A. , Mitchell Kenneth , Puma Michael J. 
Published: March 2009

Abstract
The soil moisture state simulated by a land surface model is a highly model-dependent quantity, meaning that the direct transfer of one model’s soil moisture into another can lead to a fundamental, and potentially detrimental, inconsistency. This is first illustrated with two recent examples, one from the National Centers for Environmental Prediction (NCEP) involving seasonal precipitation forecasting and another from the realm of ecological modeling. The issue is then further addressed through a quantitative analysis of soil moisture contents produced as part of a global offline simulation experiment in which a number of land surface models were driven with the same atmospheric forcing fields. These latter comparisons clearly demonstrate, on a global scale, the degree to which model-simulated soil moisture variables differ from each other and that these differences extend beyond those associated with model-specific layer thicknesses or soil texture. The offline comparisons also show, however, that once the climatological statistics of each model’s soil moisture variable are accounted for (here, through a simple scaling using the first two moments), the different land models tend to produce very similar information on temporal soil moisture variability in most parts of the world. This common information can perhaps be used as the basis for successful mappings between the soil moisture variables in different land models.
Injury Patterns and Injury Rates in the Circus Arts
Authors: Shrier Ian , Meeuwisse Willem H. , Matheson Gordon O. , Wingfield Kristin , Steele Russell J. , Prince François , Hanley James , Montanaro Michael 
Published: March 2009

Background Human circus arts are gaining increasing popularity as a physical activity with more than 500 companies and 200 schools. The only injury data that currently exist are a few case reports and 1 survey. Hypothesis To describe injury patterns and injury rates among Cirque du Soleil artists between 2002 and 2006. Study Design Descriptive epidemiology study. Methods The authors defined an injury as any work-related condition recorded in an electronic injury database that required a visit to the show therapist. Analyses for treatments, missed performances, and injury rates (per 1000 artist performances) were based on a subset of data that contained appropriate denominator (exposure) information (began in 2004). Results There were 1376 artists who sustained a total of the 18 336 show- or training-related injuries. The pattern of injuries was generally similar across sex and performance versus training. Most injuries were minor. Of the 6701 injuries with exposure data, 80% required ≤7 treatments and resulted in ≤1 completely missed performance. The overall show injury rate was 9.7 (95% confidence interval, 9.4–10.0; for context, published National Collegiate Athletic Association women’s gymnastics rate was 15.2 injuries per 1000 athlete-exposures). The rate for injuries resulting in more than 15 missed performances for acrobats (highest risk group) was 0.74 (95% confidence interval, 0.65–0.83), which is much lower than the corresponding estimated National Collegiate Athletic Association women’s gymnastics rate. Conclusion Most injuries in circus performers are minor, and rates of more serious injuries are lower than for many National Collegiate Athletic Association sports.