bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of Plant Residues in Determining Temporal Patterns of the Activity, Size, and Structure of Nitrate Reducer Communities in Soil
Authors: Chèneby D. , Bru D. , Pascault N. , Maron P. A. , Ranjard L. , Philippot L.
Published: September 2010

The incorporation of plant residues into soil not only represents an opportunity to limit soil organic matter depletion resulting from cultivation but also provides a valuable source of nutrients such as nitrogen. However, the consequences of plant residue addition on soil microbial communities involved in biochemical cycles other than the carbon cycle are poorly understood. In this study, we investigated the responses of one N-cycling microbial community, the nitrate reducers, to wheat, rape, and alfalfa residues for 11 months after incorporation into soil in a field experiment. A 20- to 27-fold increase in potential nitrate reduction activity was observed for residue-amended plots compared to the nonamended plots during the first week. This stimulating effect of residues on the activity of the nitrate-reducing community rapidly decreased but remained significant over 11 months. During this period, our results suggest that the potential nitrate reduction activity was regulated by both carbon availability and temperature. The presence of residues also had a significant effect on the abundance of nitrate reducers estimated by quantitative PCR of thenarGandnapAgenes, encoding the membrane-bound and periplasmic nitrate reductases, respectively. In contrast, the incorporation of the plant residues into soil had little impact on the structure of thenarGandnapAnitrate-reducing community determined by PCR-restriction fragment length polymorphism (RFLP) fingerprinting. Overall, our results revealed that the addition of plant residues can lead to important long-term changes in the activity and size of a microbial community involved in N cycling but with limited effects of the type of plant residue itself.
Dihydrolipoamide Dehydrogenases of
Advenella mimigardefordensis
and
Ralstonia eutropha
Catalyze Cleavage of 3,3′-Dithiodipropionic Acid into 3-Mercaptopropionic Acid
Authors: Wübbeler Jan Hendrik , Raberg Matthias , Brandt Ulrike , Steinbüchel Alexander
Published: September 2010

The catabolism of the disulfide 3,3′-dithiodipropionic acid (DTDP) is initiated by the reduction of its disulfide bond. Three independent Tn
5
::
mob
-induced mutants of
Advenella mimigardefordensis
strain DPN7
T
were isolated that had lost the ability to utilize DTDP as the sole source of carbon and energy and that harbored the transposon insertions in three different sites of the same dihydrolipoamide dehydrogenase gene encoding the E3 subunit of the pyruvate dehydrogenase multi-enzyme complex of this bacterium (LpdA

Am

). LpdA

Am

was analyzed
in silico
and compared to homologous proteins, thereby revealing high similarities to the orthologue in
Ralstonia eutropha
H16 (PdhL

Re

). Both bacteria are able to cleave DTDP into two molecules of 3-mercaptopropionic acid (3MP).
A. mimigardefordensis
DPN7
T
converted 3MP to 3-sulfinopropionic acid, whereas
R. eutropha
H16 showed no growth with DTDP as the sole carbon source but was instead capable of synthesizing heteropolythioesters using the resulting cleavage product 3MP. Subsequently, the genes

lpdA
Am

and

pdhL
Re

were cloned, heterologously expressed in
Escherichia coli
applying the pET23a expression system, purified, and assayed by monitoring the oxidation of NADH. The physiological substrate lipoamide was reduced to dihydrolipoamide with specific activities of 1,833 mkat/kg of protein (LpdA

Am

) or 1,667 mkat/kg of protein (PdhL

Re

). Reduction of DTDP was also unequivocally detected with the purified enzymes, although the specific enzyme activities were much lower: 0.7 and 0.5 mkat/kg protein, respectively.
Schizosaccharomyces pombe Calmodulin, Cam1, Plays a Crucial Role in Sporulation by Recruiting and Stabilizing the Spindle Pole Body Components Responsible for Assembly of the Forespore Membrane
Authors: Itadani Akiko , Nakamura Taro , Hirata Aiko , Shimoda Chikashi
Published: September 2010

Calmodulin in
Schizosaccharomyces pombe
is encoded by the
cam1
+
gene, which is indispensable for both vegetative growth and sporulation. Here, we report how Cam1 functions in spore formation. We found that Cam1 preferentially localized to the spindle pole body (SPB) during meiosis and sporulation. Formation of the forespore membrane, a precursor of the plasma membrane in spores, was blocked in a missense
cam1
mutant, which was viable but unable to sporulate. Three SPB proteins necessary for the onset of forespore membrane formation, Spo2, Spo13, and Spo15, were unable to localize to the SPB in the
cam1
mutant although five core SPB components that were tested were present. Recruitment of Spo2 and Spo13 is known to require the presence of Spo15 in the SPB. Notably, Spo15 was unstable in the
cam1
mutant, and as a result, SPB localization of Spo2 and Spo13 was lost. Overexpression of Spo15 partially alleviated the sporulation defect in the
cam1
mutant. These results indicate that calmodulin plays an essential role in forespore membrane formation by stably maintaining Spo15, and thus Spo2 and Spo13, at the SPB in meiotic cells.
A Novel Protein Kinase Localized to Lipid Droplets Is Required for Droplet Biogenesis in Trypanosomes
Authors: Flaspohler John A. , Jensen Bryan C. , Saveria Tracy , Kifer Charles T. , Parsons Marilyn
Published: September 2010

Ubiquitous among eukaryotes, lipid droplets are organelles that function to coordinate intracellular lipid homeostasis. Their morphology and abundance is affected by numerous genes, many of which are involved in lipid metabolism. In this report we identify a
Trypanosoma brucei
protein kinase, LDK, and demonstrate its localization to the periphery of lipid droplets. Association with lipid droplets was abrogated when the hydrophobic domain of LDK was deleted, supporting a model in which the hydrophobic domain is associated with or inserted into the membrane monolayer of the organelle. RNA interference knockdown of LDK modestly affected the growth of mammalian bloodstream-stage parasites but did not affect the growth of insect (procyclic)-stage parasites. However, the abundance of lipid droplets dramatically decreased in both cases. This loss was dominant over treatment with myriocin or growth in delipidated serum, both of which induce lipid body biogenesis. Growth in delipidated serum also increased LDK autophosphorylation activity. Thus, LDK is required for the biogenesis or maintenance of lipid droplets and is one of the few protein kinases specifically and predominantly associated with an intracellular organelle.
Ras Proteins Have Multiple Functions in Vegetative Cells of Dictyostelium
Authors: Bolourani Parvin , Spiegelman George , Weeks Gerald
Published: September 2010

During the aggregation of
Dictyostelium
cells, signaling through RasG is more important in regulating cyclic AMP (cAMP) chemotaxis, whereas signaling through RasC is more important in regulating the cAMP relay. However, RasC is capable of substituting for RasG for chemotaxis, since
rasG
−
cells are only partially deficient in chemotaxis, whereas
rasC
−
/
rasG
−
cells are totally incapable of chemotaxis. In this study we have examined the possible functional overlap between RasG and RasC in vegetative cells by comparing the vegetative cell properties of
rasG
−
,
rasC
−
, and
rasC
−
/
rasG
−
cells. In addition, since RasD, a protein not normally found in vegetative cells, is expressed in vegetative
rasG
−
and
rasC
−
/
rasG
−
cells and appears to partially compensate for the absence of RasG, we have also examined the possible functional overlap between RasG and RasD by comparing the properties of
rasG
−
and
rasC
−
/
rasG
−
cells with those of the mutant cells expressing higher levels of RasD. The results of these two lines of investigation show that RasD is capable of totally substituting for RasG for cytokinesis and growth in suspension, whereas RasC is without effect. In contrast, for chemotaxis to folate, RasC is capable of partially substituting for RasG, but RasD is totally without effect. Finally, neither RasC nor RasD is able to substitute for the role that RasG plays in regulating actin distribution and random motility. These specificity studies therefore delineate three distinct and none-overlapping functions for RasG in vegetative cells.
Recognition of Yeast by Murine Macrophages Requires Mannan but Not Glucan
Authors: Keppler-Ross Sabine , Douglas Lois , Konopka James B. , Dean Neta
Published: September 2010

The first barrier against infection by
Candida albicans
involves fungal recognition and destruction by phagocytic cells of the innate immune system. It is well established that interactions between different phagocyte receptors and components of the fungal cell wall trigger phagocytosis and subsequent immune responses, but the fungal ligands mediating the initial stage of recognition have not been identified. Here, we describe a novel assay for fungal recognition and uptake by macrophages which monitors this early recognition step independently of other downstream events of phagocytosis. To analyze infection in live macrophages, we validated the neutrality of a codon-optimized red fluorescent protein (yEmRFP) biomarker in
C. albicans
; growth, hyphal formation, and virulence in infected mice and macrophages were unaffected by yEmRFP production. This permitted a new approach for studying phagocytosis by carrying out competition assays between red and green fluorescent yeast cells to measure the efficiency of yeast uptake by murine macrophages as a function of dimorphism or cell wall defects. These competition experiments demonstrate that, given a choice, macrophages display strong preferences for phagocytosis based on genus, species, and morphology.
Candida glabrata
and
Saccharomyces cerevisiae
are taken up by J774 macrophage cells more rapidly than
C. albicans
, and
C. albicans
yeast cells are favored over hyphal cells. Significantly, these preferences are mannan dependent. Mutations that affect mannan, but not those that affect glucan or chitin, reduce the uptake of yeast challenged with wild-type competitors by both J774 and primary murine macrophages. These results suggest that mannose side chains or mannosylated proteins are the ligands recognized by murine macrophages prior to fungal uptake.
Extracellular Secretion of Overexpressed Glycosylphosphatidylinositol-Linked Cell Wall Protein Utr2/Crh2p as a Novel Protein Quality Control Mechanism in Saccharomyces cerevisiae
Authors: Miller Kelly A. , DiDone Louis , Krysan Damian J.
Published: September 2010

Eukaryotic cells employ a variety of mechanisms to maintain protein quality control and homeostasis. Here we provide evidence that one such mechanism in
Saccharomyces cerevisiae
involves the regulated release of excess or misfolded proteins to the extracellular space. The overexpression of an epitope-tagged allele of the glycosylphosphatidylinositol (GPI)-linked cell wall protein Utr2/Crh2p (Utr2/Crh2-green fluorescent protein [GFP] or -hemagglutinin [HA]) causes endoplasmic reticulum (ER) stress and the secretion of Crh2-GFP/HA into the extracellular space. Secretion is dependent on two GPI-linked aspartyl proteases (Yps1p/2p) and components of the unfolded protein response (Ire1p and Hac1p) but is independent of ER-associated degradation (ERAD) components such as Hrd1p and Doa10p. Supporting the idea that this process represents a mechanism for protein quality control, the level of Crh2-HA is increased in strains lacking Bst1p, a protein required for the proteasomal degradation of GPI-linked proteins. Furthermore, secretion is dependent on Sec18p, indicating that it requires ER-to-Golgi trafficking, and accordingly, Crh2-HA accumulates in the ER in
ire1
Δ and
bst1
Δ mutants by cycloheximide chase experiments. Since a fraction of Utr2/Crh2-GFP properly localizes to the cell wall in an
ire1
Δ mutant, extracellular secretion appears to occur through a pathway that is distinct from the normal GPI protein-trafficking pathway. Taken together, these data support a model in which the unfolded protein response (UPR)/yapsin-mediated extracellular release of overexpressed Utr2/Crh2-HA or -GFP is an alternative pathway for the removal of excess or misfolded secretory proteins functioning in parallel with proteasome-mediated degradation in
S. cerevisiae
. This model provides an explanation for the deleterious effects of Yps1/2p on the industrial production of some recombinant proteins in
S. cerevisiae
.
SpdR, a Response Regulator Required for Stationary-Phase Induction of
Caulobacter crescentus cspD
Authors: da Silva Carolina A. P. T. , Balhesteros Heloise , Mazzon Ricardo R. , Marques Marilis V.
Published: September 2010

The cold shock protein (CSP) family includes small polypeptides that are induced upon temperature downshift and stationary phase. The genome of the alphaproteobacterium
Caulobacter crescentus
encodes four CSPs, with two being induced by cold shock and two at the onset of stationary phase. In order to identify the environmental signals and cell factors that are involved in
cspD
expression at stationary phase, we have analyzed
cspD
transcription during growth under several nutrient conditions. The results showed that expression of
cspD
was affected by the medium composition and was inversely proportional to the growth rate. The maximum levels of expression were decreased in a
spoT
mutant, indicating that ppGpp may be involved in the signalization for carbon starvation induction of
cspD
. A Tn
5
mutant library was screened for mutants with reduced
cspD
expression, and 10 clones that showed at least a 50% reduction in expression were identified. Among these, a strain with a transposon insertion into a response regulator of a two-component system showed no induction of
cspD
at stationary phase. This protein (SpdR) was able to acquire a phosphate group from its cognate histidine kinase, and gel mobility shift assay and DNase I footprinting experiments showed that it binds to an inverted repeat sequence of the
cspD
regulatory region. A mutated SpdR with a substitution of the conserved aspartyl residue that is the probable phosphorylation site is unable to bind to the
cspD
regulatory region and to complement the
spdR
mutant phenotype.
Residue Histidine 669 Is Essential for the Catalytic Activity of
Bacillus anthracis
Lethal Factor
Authors: Cao Sha , Guo Aizhen , Wu Gaobing , Liu Ziduo , Chen Wei , Feng Chunfang , Zhang Cheng-Cai , Chen Huanchun
Published: September 2010

The lethal factor (LF) of
Bacillus anthracis
is a Zn
2+
-dependent metalloprotease which plays an important role in anthrax virulence. This study was aimed at identifying the histidine residues that are essential to the catalytic activities of LF. The site-directed mutagenesis was employed to replace the 10 histidine residues in domains II, III, and IV of LF with alanine residues, respectively. The cytotoxicity of these mutants was tested, and the results revealed that the alanine substitution for His-669 completely abolished toxicity to the lethal toxin (LT)-sensitive RAW264.7 cells. The reason for the toxicity loss was further explored. The zinc content of this LF mutant was the same as that of the wild type. Also this LF mutant retained its protective antigan (PA)-binding activity. Finally, the catalytic cleavage activity of this mutant was demonstrated to be drastically reduced. Thus, we conclude that residue His-669 is crucial to the proteolytic activity of LF.
The Two-Component System BvrR/BvrS Regulates the Expression of the Type IV Secretion System VirB inBrucella abortus
Authors: Martínez-Núñez Carola , Altamirano-Silva Pamela , Alvarado-Guillén Francisco , Moreno Edgardo , Guzmán-Verri Caterina , Chaves-Olarte Esteban
Published: September 2010

The pathogenesis ofBrucellais related to the ability to multiply intracellularly, an event controlled by the two-component system BvrR/BvrS (TCS BvrRS) and the type IV secretion machinery VirB (T4SS VirB). We have hypothesized that the TCS BvrRS transcriptionally regulates the T4SS VirB. To test this hypothesis, we have compared the levels of VirB proteins in the wild-type strainBrucella abortus2308 and mutant strains devoid of the sensor and regulator genes (bvrSandbvrRmutants, respectively). While thebvrRandbvrSmutants showed low levels of the VirB1, VirB5, VirB8, and VirB9 proteins, the same proteins were overexpressed in thebvrRmutant complemented with a plasmid carrying a functionalbvrRgene. Quantitation ofvirB5mRNA confirmed these data and indicated that the influence of the TCS BvrRS on the T4SS VirB occurs at the transcriptional level. The expression of the transcriptional activator VjbR also depended on the TCS BvrRS. In addition, we demonstrate a direct interaction between the promoter region of the VirB operon and the response regulator BvrR. Altogether these data demonstrate that the TCS BvrRS controls the expression of the T4SS VirB through direct and indirect mechanisms.
Role of Cross Talk in Regulating the Dynamic Expression of the FlagellarSalmonellaPathogenicity Island 1 and Type 1 Fimbrial Genes
Authors: Saini Supreet , Slauch James M. , Aldridge Phillip D. , Rao Christopher V.
Published: September 2010

Salmonella enterica, a common food-borne pathogen, differentially regulates the expression of multiple genes during the infection cycle. These genes encode systems related to motility, adhesion, invasion, and intestinal persistence. Key among them is a type three secretion system (T3SS) encoded withinSalmonellapathogenicity island 1 (SPI1). In addition to the SPI1 T3SS, other systems, including flagella and type 1 fimbriae, have been implicated inSalmonellapathogenesis. In this study, we investigated the dynamic expression of the flagellar, SPI1, and type 1 fimbrial genes. We demonstrate that these genes are expressed in a temporal hierarchy, beginning with the flagellar genes, followed by the SPI1 genes, and ending with the type 1 fimbrial genes. This hierarchy could mirror the roles of these three systems during the infection cycle. As multiple studies have shown that extensive regulatory cross talk exists between these three systems, we also tested how removing different regulatory links between them affects gene expression dynamics. These results indicate that cross talk is critical for regulating gene expression during transitional phases in the gene expression hierarchy. In addition, we identified a novel regulatory link between flagellar and type 1 fimbrial gene expression dynamics, where we found that the flagellar regulator, FliZ, represses type 1 fimbrial gene expression through the posttranscriptional regulation of FimZ. The significance of these results is that they provide the first systematic study of the effect of regulatory cross talk on the expression dynamics of flagellar, SPI1, and type 1 fimbrial genes.
Proteomic Analysis ofNeorickettsia sennetsuSurface-Exposed Proteins and Porin Activity of the Major Surface Protein P51
Authors: Gibson Kathryn , Kumagai Yumi , Rikihisa Yasuko
Published: September 2010

Neorickettsia sennetsuis an obligate intracellular bacterium of monocytes and macrophages and is the etiologic agent of human Sennetsu neorickettsiosis.Neorickettsiaproteins expressed in mammalian host cells, including the surface proteins ofNeorickettsiaspp., have not been defined. In this paper, we isolated surface-exposed proteins fromN. sennetsuby biotin surface labeling followed by streptavidin-affinity chromatography. Forty-two of the total of 936 (4.5%)N. sennetsuopen reading frames (ORFs) were detected by liquid chromatography-tandem mass spectrometry (LC/MS/MS), including six hypothetical proteins. Among the major proteins identified were the two major β-barrel proteins: the 51-kDa antigen (P51) andNeorickettsiasurface protein 3 (Nsp3). Immunofluorescence labeling not only confirmed surface exposure of these proteins but also showed rosary-like circumferential labeling with anti-P51 for the majority of bacteria and polar to diffuse punctate labeling with anti-Nsp3 for a minority of bacteria. We found that the isolated outer membrane ofN. sennetsuhad porin activity, as measured by a proteoliposome swelling assay. This activity allowed the diffusion ofl-glutamine, the monosaccharides arabinose and glucose, and the tetrasaccharide stachyose, which could be inhibited with anti-P51 antibody. We purified native P51 and Nsp3 under nondenaturing conditions. When reconstituted into proteoliposomes, purified P51, but not Nsp3, exhibited prominent porin activity. This the first proteomic study of aNeorickettsiasp. showing new sets of proteins evolved as major surface proteins forNeorickettsiaand the first identification of a porin for the genusNeorickettsia.
l
-Lysine Catabolism Is Controlled by
l
-Arginine and ArgR in
Pseudomonas aeruginosa
PAO1
Authors: Chou Han Ting , Hegazy Mohamed , Lu Chung-Dar
Published: September 2010

In comparison to other pseudomonads,
Pseudomonas aeruginosa
grows poorly in
l
-lysine as a sole source of nutrient. In this study, the
ldcA
gene (
l
ysine
d
e

c

arboxylase
A
; PA1818), previously identified as a member of the ArgR regulon of
l
-arginine metabolism, was found essential for
l
-lysine catabolism in this organism. LdcA was purified to homogeneity from a recombinant strain of
Escherichia coli
, and the results of enzyme characterization revealed that this pyridoxal-5-phosphate-dependent decarboxylase takes
l
-lysine, but not
l
-arginine, as a substrate. At an optimal pH of 8.5, cooperative substrate activation by
l
-lysine was depicted from kinetics studies, with calculated

K
m

and
V
max
values of 0.73 mM and 2.2 μmole/mg/min, respectively. Contrarily, the
ldcA
promoter was induced by exogenous
l
-arginine but not by
l
-lysine in the wild-type strain PAO1, and the binding of ArgR to this promoter region was demonstrated by electromobility shift assays. This peculiar arginine control on lysine utilization was also noted from uptake experiments in which incorporation of radioactively labeled
l
-lysine was enhanced in cells grown in the presence of
l
-arginine but not
l
-lysine. Rapid growth on
l
-lysine was detected in a mutant devoid of the main arginine catabolic pathway and with a higher basal level of the intracellular
l
-arginine pool and hence elevated ArgR-responsive regulons, including
ldcA
. Growth on
l
-lysine as a nitrogen source can also be enhanced when the
aruH
gene encoding an arginine/lysine:pyruvate transaminase was expressed constitutively from plasmids; however, no growth of the
ldcA
mutant on
l
-lysine suggests a minor role of this transaminase in
l
-lysine catabolism. In summary, this study reveals a tight connection of lysine catabolism to the arginine regulatory network, and the lack of lysine-responsive control on lysine uptake and decarboxylation provides an explanation of
l
-lysine as a poor nutrient for
P. aeruginosa
.
Regulation of a Phage Endolysin by Disulfide Caging
Authors: Kuty Gabriel F. , Xu Min , Struck Douglas K. , Summer Elizabeth J. , Young Ry
Published: September 2010

In contrast to canonical phage endolysins, which require holin-mediated disruption of the membrane to gain access to attack the cell wall, signal anchor release (SAR) endolysins are secreted by the host
sec
system, where they accumulate in an inactive form tethered to the membrane by their N-terminal SAR domains. SAR endolysins become activated by various mechanisms upon release from the membrane. In its inactive form, the prototype SAR endolysin, Lyz
P1
, of coliphage P1, has an active-site Cys covalently blocked by a disulfide bond; activation involves a disulfide bond isomerization driven by a thiol in the newly released SAR domain, unblocking the active-site Cys. Here, we report that Lyz
103
, the endolysin of
Erwinia
phage ERA103, is also a SAR endolysin. Although Lyz
103
does not have a catalytic Cys, genetic evidence suggests that it also is activated by a thiol-disulfide isomerization triggered by a thiol in the SAR domain. In this case, the inhibitory disulfide in nascent Lyz
103
is formed between cysteine residues flanking a catalytic glutamate, caging the active site. Thus, Lyz
P1
and Lyz
103
define subclasses of SAR endolysins that differ in the nature of their inhibitory disulfide, and Lyz
103
is the first enzyme found to be regulated by disulfide bond caging of its active site.
Analysis of the Intact Surface Layer ofCaulobacter crescentusby Cryo-Electron Tomography
Authors: Amat Fernando , Comolli Luis R. , Nomellini John F. , Moussavi Farshid , Downing Kenneth H. , Smit John , Horowitz Mark
Published: September 2010

The surface layers (S layers) of those bacteria and archaea that elaborate these crystalline structures have been studied for 40 years. However, most structural analysis has been based on electron microscopy of negatively stained S-layer fragments separated from cells, which can introduce staining artifacts and allow rearrangement of structures prone to self-assemble. We present a quantitative analysis of the structure and organization of the S layer on intact growing cells of the Gram-negative bacteriumCaulobacter crescentususing cryo-electron tomography (CET) and statistical image processing. Instead of the expected long-range order, we observed different regions with hexagonally organized subunits exhibiting short-range order and a broad distribution of periodicities. Also, areas of stacked double layers were found, and these increased in extent when the S-layer protein (RsaA) expression level was elevated by addition of multiplersaAcopies. Finally, we combined high-resolution amino acid residue-specific Nanogold labeling and subtomogram averaging of CET volumes to improve our understanding of the correlation between the linear protein sequence and the structure at the 2-nm level of resolution that is presently available. The results support the view that the U-shaped RsaA monomer predicted from negative-stain tomography proceeds from the N terminus at one vertex, corresponding to the axis of 3-fold symmetry, to the C terminus at the opposite vertex, which forms the prominent 6-fold symmetry axis. Such information will help future efforts to analyze subunit interactions and guide selection of internal sites for display of heterologous protein segments.
Latency of the Lipid A Deacylase PagL Is Involved in Producing a Robust Permeation Barrier in the Outer Membrane of
Salmonella enterica
Authors: Kawasaki Kiyoshi , Manabe Takayuki
Published: September 2010

Lipid A deacylase PagL, which detoxifies endotoxin, is latent in
Salmonella enterica
. This study determined the biological significance of this latency. PagL latency was beneficial for bacteria in producing a robust permeation barrier through lipid A modifications under host-mimetic conditions that induced the modification enzymes, including PagL.
Legionella pneumophilaStrain 130b Possesses a Unique Combination of Type IV Secretion Systems and Novel Dot/Icm Secretion System Effector Proteins
Authors: Schroeder Gunnar N. , Petty Nicola K. , Mousnier Aurélie , Harding Clare R. , Vogrin Adam J. , Wee Bryan , Fry Norman K. , Harrison Timothy G. , Newton Hayley J. , Thomson Nicholas R. , Beatson Scott A. , Dougan Gordon , Hartland Elizabeth L. , Frankel Gad
Published: September 2010

Legionella pneumophilais a ubiquitous inhabitant of environmental water reservoirs. The bacteria infect a wide variety of protozoa and, after accidental inhalation, human alveolar macrophages, which can lead to severe pneumonia. The capability to thrive in phagocytic hosts is dependent on the Dot/Icm type IV secretion system (T4SS), which translocates multiple effector proteins into the host cell. In this study, we determined the draft genome sequence ofL. pneumophilastrain 130b (Wadsworth). We found that the 130b genome encodes a unique set of T4SSs, namely, the Dot/Icm T4SS, a Trb-1-like T4SS, and two Lvh T4SS gene clusters. Sequence analysis substantiated that a core set of 107 Dot/Icm T4SS effectors was conserved among the sequencedL. pneumophilastrains Philadelphia-1, Lens, Paris, Corby, Alcoy, and 130b. We also identified new effector candidates and validated the translocation of 10 novel Dot/Icm T4SS effectors that are not present inL. pneumophilastrain Philadelphia-1. We examined the prevalence of the new effector genes among 87 environmental and clinicalL. pneumophilaisolates. Five of the new effectors were identified in 34 to 62% of the isolates, while less than 15% of the strains tested positive for the other five genes. Collectively, our data show that the core set of conserved Dot/Icm T4SS effector proteins is supplemented by a variable repertoire of accessory effectors that may partly account for differences in the virulences and prevalences of particularL. pneumophilastrains.
Genome Sequence of the Dioxin-Mineralizing Bacterium
Sphingomonas wittichii
RW1
Authors: Miller Todd R. , Delcher Arthur L. , Salzberg Steven L. , Saunders Elizabeth , Detter John C. , Halden Rolf U.
Published: September 2010

Pollutants such as polychlorinated biphenyls and dioxins pose a serious threat to human and environmental health. Natural attenuation of these compounds by microorganisms provides one promising avenue for their removal from contaminated areas. Over the past 2 decades, studies of the bacterium
Sphingomonas wittichii
RW1 have provided a wealth of knowledge about how bacteria metabolize chlorinated aromatic hydrocarbons. Here we describe the finished genome sequence of
S. wittichii
RW1 and major findings from its annotation.
Disability, environmental factors and non-fatal injury
Authors: Leff Marilyn , Stallones Lorann , Xiang Huiyun , Whiteneck Gale
Published: September 2010

Background

People with disabilities have high rates of non-fatal injury; they are also likely to experience environmental factors as barriers to functioning and participation in society. The reasons for the higher injury rates among those with disabilities have not been explained.

Objective

To determine if problems with environmental factors influence the higher rates of injury among disabled compared with non-disabled.

Design

Data from a population-based, random-digit dial cross-sectional telephone survey were analysed to evaluate whether environmental factors as measured by the Craig Hospital Inventory of Environmental Factors explained higher injury rates among those with disabilities compared with those without. A total of 2511 Colorado adults (1997 with no disability, 386 with moderate disability, and 128 with severe disability) were included in the sample. All rated their experience of environmental factors and reported injuries within the previous 12 months. Logistic regression analyses were conducted to evaluate whether environmental factors could be confounding factors in the association between disability and non-fatal injury.

Results

Disability and environmental barriers were independently associated with higher rates of injury. Environmental factors did attenuate the increased odds of experiencing an injury among those with severe disabilities, but these people continued to have significantly higher rates of injury after adjustment for environmental factors. The natural environment, social attitudes and policies were ranked highly as problems by all injured persons.

Conclusion

Injury prevention efforts need to focus on reducing disability-related injuries and reducing environmental barriers for all.
The effects of timing on the cost-effectiveness of interventions for workers on sick leave due to low back pain
Authors: van Duijn Miranda , Eijkemans Marinus J , Koes Bart W , Koopmanschap Marc A , Burton Kim A , Burdorf Alex
Published: September 2010

Objective

To examine the effects of different timing of structured interventions for workers on sick leave due to low back pain on return to work (RTW), and the consequences for costs and benefits.

Methods

Literature reviews were conducted to identify RTW curves and to estimate treatment effects, costs and benefits of structured interventions among workers on sick leave due to low back pain. RTW curves were mathematically described by Weibull functions and intervention effects, expressed by hazard ratios, were used to adjust these Weibull functions. Subsequently, these functions were used to evaluate the theoretical effects of interventions on reduction in number of days on sick leave and on the benefit–cost ratio.

Results

The cost-benefits of a RTW intervention among workers on sick leave due to low back pain were determined by the estimated effectiveness of the intervention, the costs of the intervention, the natural course of RTW in the target population, the timing of the enrolment of subjects into the intervention, and the duration of the intervention.

Conclusion

With a good RTW in the first weeks, the only early interventions likely to be cost-beneficial are inexpensive work-focused enhancements to early routine care, such as accommodating workplaces. Structured interventions are unlikely to have an additional impact on the already good prognosis when offered before the optimal time window at approximately 8 to 12 weeks. The generalisibility of the effectiveness of a RTW intervention depends on the comparability of baseline characteristics and RTW curves in target and source populations.
Lung cancer mortality from exposure to chrysotile asbestos and smoking: a case–control study within a cohort in China
Authors: Yano Eiji , Wang Xiaorong , Wang Mianzhen , Qiu Hong , Wang Zhiming
Published: September 2010

Objective

To confirm the association between exposure to chrysotile asbestos and lung cancer risk and to demonstrate the combined effect of smoking and asbestos exposure.

Methods

A case–control study of 1139 asbestos workers identified 41 male lung cancer cases in 2001; each case was matched by age (±5 years) with five controls. Workers in seven workshops were categorised into high-, medium- and low-exposure subgroups, and conditional logistic regression was applied to estimate the odds ratios for lung cancer risk associated with the different exposure levels. Smoking, age at first exposure, and exposure duration were considered as covariates/confounding factors. A joint effect of asbestos exposure and smoking on lung cancer risk was analysed using a conditional logistical model.

Results

54% of cases had high exposure and 24% low exposure, while 24% of controls had high exposure and 44% low exposure. Smoking was more common in cases (90%) than in controls (73%). The adjusted OR for lung cancer was 3.66 (95% CI 1.61 to 8.29) for high exposure and was elevated slightly for medium exposure (1.25; 95% CI 0.47 to 3.31). Smoking was related to lung cancer risk (OR 3.33; 95% CI 1.10 to 10.08). In comparison with the low-exposure non-smoking group, the OR for the high-exposure smoking group was 10.39 (1.34 to 82.45), in contrast to 5.23 (0.50 to 54.58) for high-exposure non-smoking workers.

Conclusions

These results confirm the strong association between exposure to chrysotile asbestos and lung cancer risk, and support an interactive effect of asbestos exposure and smoking which is more than additive.
Long-term air pollution exposure and risk factors for cardiovascular diseases among the elderly in Taiwan
Authors: Chuang Kai-Jen , Yan Yuan-Horng , Chiu Shu-Yi , Cheng Tsun-Jen
Published: September 2010

Objectives

To investigate changes in blood pressure, blood lipids, blood sugar and haematological markers of inflammation associated with changes in long-term exposure to ambient air pollutants.

Methods

We conducted secondary analyses of data on blood pressure and blood biochemistry markers from the Social Environment and Biomarkers of Aging Study in Taiwan and air pollution data from the Taiwan Environmental Protection Administration in 2000. Associations of 1-year averaged criteria air pollutants (particulate matter with aerodynamic diameters <10 μm (PM10) and <2.5 μm (PM2.5), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide and carbon monoxide) with systolic blood pressure, diastolic blood pressure, total cholesterol, triglycerides, high-density lipoprotein cholesterol, fasting glucose, haemoglobin A1c (HbA1c), interleukin 6 (IL-6) and neutrophils were explored by applying generalised additive models.

Results

After controlling for potential confounders, we observed that increased 1-year averaged particulate air pollutants (PM10and PM2.5) and NO2were associated with elevated blood pressure, total cholesterol, fasting glucose, HbA1c, IL-6 and neutrophils. Associations of increased 1-year averaged O3with elevated blood pressure, total cholesterol, fasting glucose, HbA1c and neutrophils were also observed. In particular, our two-pollutant models showed that PM2.5was more significantly associated with end-point variables than two gaseous pollutants, O3and NO2.

Conclusions

Changes in blood pressure, blood lipids, blood sugar and haematological markers of inflammation are associated with long-term exposure to ambient air pollutants. This might provide a link between air pollution and atherosclerotic cardiovascular diseases.
Neuroplastic changes within the brains of manganese-exposed welders: recruiting additional neural resources for successful motor performance
Authors: Chang Yongmin , Song Hui-Jin , Lee Jae-Jun , Seo Jee-Hye , Kim Joo-Hyun , Lee Hui Joong , Kim Hye Jung , Kim Yangho , Ahn Joon-Ho , Park Sin-Jae , Kwon Jee Hyun , Jeong Kyoung Sook , Jung Doo-Kyo
Published: September 2010

Background

In a previous study, regional delivery of manganese (Mn)ions within the brain revealed that the metal accumulates in the basal ganglia, where it induces degeneration of the globus pallidus. Degeneration of the basal ganglia impairs motor ability by compromising an important neural circuit involved in the regulation of motor control. Therefore, much research has been devoted to identifying a sensitive and non-invasive imaging marker to evaluate the functional correlates of Mn-related brain dysfunction.

Methods

We performed the first-ever sequential finger-tapping functional MRI (fMRI) experiment to investigate the behavioural significance of additionally recruited brain regions in welders with chronic Mn exposure.

Results

During the finger tapping task, activation of the bilateral primary sensorimotor cortex (SM1), bilateral supplementary motor area (SMA), bilateral dorsolateral premotor cortex, bilateral superior parietal cortex and ipsilateral dentate nucleus was higher in the welding group (42 welders) than in the control group (26 controls). The pallidal index correlated with the activation observed in the contralateral SM1 for the finger tapping task of the left hand. The fMRI variables correlated with motor behaviour. Grooved Pegboard performances (right hand) correlated with activation, as seen in the ipsilateral and contralateral SMAs obtained during the finger tapping task of the right hand.

Conclusion

Our findings suggest that increased brain activation results from the compensational activation of ancillary cortical pathways, which ensures adequate motor function.
Prevalence and correlates of regional pain and associated disability in Japanese workers
Authors: Matsudaira Ko , Palmer Keith T , Reading Isabel , Hirai Masami , Yoshimura Noriko , Coggon David
Published: September 2010

Objectives

To assess the prevalence and correlates of regional pain and associated disability in four groups of Japanese workers.

Methods

As part of a large international survey of musculoskeletal symptoms (the CUPID study), nurses, office workers, sales/marketing personnel and transportation operatives in Japan completed a self-administered questionnaire (response rate 83%) covering experience of pain in six anatomical regions, associated disability and sickness absence, and various possible occupational and psychosocial risk factors for these outcomes. Associations with risk factors were assessed by logistic regression.

Results

Analysis was based on 2290 subjects. Rates of regional pain were generally less than in the UK, with a particularly low prevalence of wrist/hand pain among office workers (6% in past month). The strongest and most consistent risk factor for regional pain in the past month was tendency to somatise (ORs (95% CIs) for report of ≥2 versus 0 distressing somatic symptoms 3.1 (2.4 to 4.0) for low back pain, 2.8 (2.1 to 3.8) for shoulder pain, and 2.5 (1.6 to 4.1) for wrist/hand pain). Sickness absence for regional pain complaints in the past year was reported by 5% of participants, the major risk factor for this outcome being absence during the same period for other medical reasons (OR 3.7, 95% CI 2.4 to 5.8).

Conclusions

Japanese office workers have markedly lower rates of wrist/hand pain than their UK counterparts. In Japan, as in Western Europe, somatising tendency is a major risk factor for regional pain. Sickness absence attributed to regional pain complaints appears to be much less common in Japan than in the UK, and to be driven principally by a general propensity to take sickness absence.
Stress management interventions in the workplace improve stress reactivity: a randomised controlled trial
Authors: Limm Heribert , Gündel Harald , Heinmüller Mechthild , Marten-Mittag Birgitt , Nater Urs M , Siegrist Johannes , Angerer Peter
Published: September 2010

Objective

To examine the long-term effects of a stress management intervention (SMI) based on the effort–reward imbalance (ERI) model, on psychological and biological reactions to work stress.

Methods

174 lower or middle management employees (99% male) were randomly assigned to an intervention or a waiting control group. The programme comprised 24×45 min group sessions (2 full days followed by two 4×45 min sessions within the next 8 months) on individual work stress situations. The primary endpoint was perceived stress reactivity (Stress Reactivity Scale, SRS), while secondary endpoints were salivary cortisol and α-amylase, anxiety and depression, and ERI. Assessments were repeated in 154 participants 1 year later.

Results

SRS score decreased in both groups. A two-factor ANOVA with repeated measures showed a significant time×group effect (F=5.932; p=0.016) with the greater reduction in the intervention group. For SRS, the effect size (Cohen's d) after 1 year was d=0.416 in the intervention and d=0.166 in the control group. α-Amylase as a measure of sympathetic nervous system activation, decreased more strongly in the intervention group (area under the daytime curve and daytime slope: time×group effect p=0.076 and p=0.075). No difference was observed for cortisol. For depression, anxiety and ERI, improvements were higher in the intervention group but did not reach statistical significance.

Conclusions

SMI based on work stress theory, is effective in reducing perceived stress reactivity and sympathetic activation in lower and middle management employees. Other mental health parameters and ERI show a tendency towards improvement. These beneficial effects are present 1 year later.
The relationship between multiple myeloma and occupational exposure to six chlorinated solvents
Authors: Gold Laura S , Stewart Patricia A , Milliken Kevin , Purdue Mark , Severson Richard , Seixas Noah , Blair Aaron , Hartge Patricia , Davis Scott , De Roos Anneclaire J
Published: September 2010

Objectives

Few studies have examined whether exposure to chlorinated solvents is associated with multiple myeloma. We evaluated associations between multiple myeloma and occupational exposure to six chlorinated solvents: 1,1,1-trichloroethane, trichloroethylene (TCE), methylene chloride (DCM), perchloroethylene, carbon tetrachloride and chloroform.

Methods

In-person interviews obtained occupational histories and information on jobs with likely solvent exposure. We assigned exposure metrics of probability, frequency, intensity and confidence using job-exposure matrices modified by job-specific questionnaire information. We used logistic regression to estimate ORs and 95% CIs for associations between multiple myeloma and ever exposure to each, and any, chlorinated solvent and analysed whether associations varied by duration and cumulative exposure. We also considered all occupations that were given the lowest confidence scores as unexposed and repeated all analyses.

Results

Risk of multiple myeloma was elevated for subjects ever exposed to 1,1,1-trichloroethane (OR (95% CI): 1.8 (1.1 to 2.9)). Ever exposure to TCE or DCM also entailed elevated, but not statistically significant, risks of multiple myeloma; these became statistically significant when occupations with low confidence scores were considered unexposed (TCE: 1.7 (1.0 to 2.7); DCM: 2.0 (1.2 to 3.2)). Increasing cumulative exposure to perchloroethylene was also associated with increasing multiple myeloma risk. We observed non-significantly increased multiple myeloma risks with exposure to chloroform; however, few subjects were exposed.

Conclusions

Evidence from this relatively large case-control study suggests that exposures to certain chlorinated solvents may be associated with increased incidence of multiple myeloma; however, the study is limited by relatively low participation (52%) among controls.
Lung ischemia-reperfusion injury: a molecular and clinical view on a complex pathophysiological process
Authors: den Hengst Willem A. , Gielis Jan F. , Lin Judy Y. , Van Schil Paul E. , De Windt Leon J. , Moens An L.
Published: September 2010

Lung ischemia-reperfusion injury remains one of the major complications after cardiac bypass surgery and lung transplantation. Due to its dual blood supply system and the availability of oxygen from alveolar ventilation, the pathogenetic mechanisms of ischemia-reperfusion injury in the lungs are more complicated than in other organs, where loss of blood flow automatically leads to hypoxia. In this review, an extensive overview is given of the molecular and cellular mechanisms that are involved in the pathogenesis of lung ischemia-reperfusion injury and the possible therapeutic strategies to reduce or prevent it. In addition, the roles of neutrophils, alveolar macrophages, cytokines, and chemokines, as well as the alterations in the cell-death related pathways, are described in detail.
Calcium-sensing receptor: a sensor and mediator of ischemic preconditioning in the heart
Authors: Sun Junhui , Murphy Elizabeth
Published: September 2010

As a G protein-coupled receptor, the extracellular Ca2+-sensing receptor (CaSR) responds to changes not only in extracellular Ca2+, but also to many other ligands. CaSR has been found to be expressed in the hearts and cardiovascular system. In this study, we confirmed that CaSR is expressed in mouse cardiomyocytes and showed that it is predominantly localized in caveolae. The goal of this study was to investigate whether CaSR plays a cardioprotective role in ischemic preconditioning (IPC). Hearts from C57BL/6J mice (male, 12–16 wk) were perfused in the Langendorff mode and subjected to the following treatments: 1) control perfusion; 2) perfusion with a specific CaSR antagonist, NPS2143; 3) IPC (four cycles of 5 min of global ischemia and 5 min of reperfusion); or 4) perfusion with NPS2143 before and during IPC. Following these treatments, hearts were subjected to 20 min of no-flow global ischemia and 120 min of reperfusion. Compared with control, IPC significantly improved postischemic left ventricular functional recovery and reduced infarct size. Although NPS2143 perfusion alone did not change the hemodynamic function and did not change the extent of postischemic injury, NPS2143 treatment abolished cardioprotection of IPC. Through immunoblot analysis, it was demonstrated that IPC significantly increased the levels of phosphorylated ERK1/2, AKT, and GSK-3β, which were also prevented by NPS2143 treatment. Taken together, the distribution of CaSR in caveolae along with NPS2143-blockade of IPC-induced cardioprotective signaling suggest that the activation of CaSR during IPC is cardioprotective by a process involving caveolae.