bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oil price shocks and economic growth in Nigeria: are thresholds important?
Authors: Adeniyi Oluwatosin , Oyinlola Abimbola , Omisakin Olusegun 
Published: December 2011

AbstractThe impact of oil price shocks on the economy has occupied the attention of researchers for almost four decades. Majority of studies support the existence of a negative association, while some recent evidences seem to have popularised the view that outcomes are the artefacts of misspecified functional forms. This study, although similar in spirit to this popular opinion, is, however, distinct in a number of ways. Firstly, unlike most Nigeria‐specific studies, this paper explores alternative measures of oil price shocks, which have been developed and used in the literature with a view to ascertaining the extent to which conclusions about the oil price‐growth association depend on the definition of shocks adopted. More importantly, this, to the best of our knowledge, is a pioneer attempt at introducing threshold effects into the linkage between oil price shocks and output growth in Nigeria. The relatively recent regime‐dependent multivariate threshold autoregressive model, together with the characteristic impulse response functions and forecast error variance decomposition, is adopted in this study. Using quarterly data spanning 1985–2008, a non‐linear model of oil price shocks and economic growth is estimated.Our main results indicate that oil price shocks do not account for a significant proportion of observed movements in macroeconomic aggregates. This pattern persists despite the introduction of threshold effects. This implied the enclave nature of Nigeria's oil sector with weak linkages. Therefore, the need to spend oil revenue productively is imperative if favourable effect on real output growth is envisaged.
The impact of oil prices on the real exchange rate of the dirham: a case study of the United Arab Emirates (UAE)
Authors: Al‐mulali Usama , Che Sab Che Normee Binti 
Published: December 2011

AbstractThis study investigated the impact of oil shocks on the real exchange rate of the United Arab Emirates (UAE) dirham. Time series data were used for the period 1977–2007. Through this study, it has been found that a fixed exchange rate to the US dollar is not an appropriate exchange rate regime for the UAE. This is because when the price of oil increases, and with a fixed exchange rate regime, this would lead to rapid growth in gross domestic product and liquidity in the UAE economy. This, in turn, causes domestic prices to increase, and results in high levels of inflation.
Clinical guidelines for diagnosing and managing ocular manifestations in children with mucopolysaccharidosis
Authors: Fahnehjelm Kristina T. , Ashworth Jane L. , Pitz Susanne , Olsson Monica , Törnquist Alba Lucia , Lindahl Päivi , Summers C. Gail 
Published: December 2011

Abstract.The mucopolysaccharidoses (MPS) are a group of rare lysosomal storage disorders characterized by the accumulation of glycosaminoglycans in several tissues and organs. This accumulation results in an array of clinical manifestations and premature death in severe cases. Ocular problems are very common in children with MPS and may involve the cornea, sclera, trabecular meshwork, retina, optic nerve and also the posterior visual pathways. The aims of this study are to give an overview of ocular problems in MPS and to provide clinical guidelines for paediatric ophthalmologists for early diagnosis and management of ocular manifestations in children with MPS. Diagnostic problems may arise in children with severe corneal clouding, hampering visualization of the fundus. Intraocular pressures may be falsely high, even leading to suspicion and unnecessary pressure‐lowering treatment. Simple interventions such as the use of prescription glasses or photochromatic glasses can considerably improve quality of life in children with MPS.
SPARC modulates expression of extracellular matrix genes in human trabecular meshwork cells
Authors: Wei Hai‐Ying , Liu Jing‐Lei , Lv Bing‐Jie , Xing Lin , Fu Shao‐Ying 
Published: December 2011

Abstract.Purpose:  To investigate the effects of secreted protein acidic and rich in cysteine (SPARC) on the expression of components of the extracellular matrix (ECM) in cultured human trabecular meshwork (TM) cells.Methods:  Cultured human trabecular cells were transfected with small interfering RNAs (siRNAs) specific for the human SPARC gene. Protein and mRNA expressions of fibronectin (FN) and the α1chains of collagen I and collagen III were quantified.Results:  After silencing of the SPARC gene by transfection of cells with SPARC siRNA, the expression of COL1A1 and COL3A1 mRNAs and proteins was significantly enhanced, as compared to that in the control group (all, p < 0.001). In contrast, SPARC siRNA significantly reduced the expression of FN and SPARC mRNAs and FN protein, as compared to that in the control group (all, p < 0.001.).Conclusions:  SPARC modulates the expression of several ECM genes in cultured human TM cells.
THE MORAL SIGNIFICANCE OF GRATITUDE IN KANT'S ETHICS
Authors: SMIT HOUSTON , TIMMONS MARK 
Published: December 2011

abstractIn this essay, we examine the grounds, nature and content, status, acquisition and role, and justification of gratitude in Kant's ethical system, making use of student notes from Kant's lectures on ethics. We are especially interested in questions about the significance of gratitude in Kant's ethics. We examine Kant's claim that gratitude is a sacred duty, because it cannot be discharged, and explain how this claim is consistent with his insistence that “ought” implies “can.” We argue that for Kant a proper understanding of self‐esteem is importantly related to, if not necessary for, possession of the virtue of gratitude.
Atypical Listeria monocytogenes Serotype 4b Strains Harboring a Lineage II-Specific Gene Cassette
Authors: Lee Sangmi , Ward Todd J. , Graves Lewis M. , Wolf Leslie A. , Sperry Kate , Siletzky Robin M. , Kathariou Sophia 
Published: December 2011

ABSTRACT

Listeria monocytogenes
is the etiological agent of listeriosis, a severe food-borne illness. The population of
L. monocytogenes
is divided into four lineages (I to IV), and serotype 4b in lineage I has been involved in numerous outbreaks. Several serotype 4b epidemic-associated clonal groups (ECI, -II, and -Ia) have been identified. In this study, we characterized a panel of strains of serotype 4b that produced atypical results with a serotype-specific multiplex PCR and possessed the
lmo0734
to
lmo0739
gene cassette that had been thought to be specific to lineage II. The cassette was harbored in a genomically syntenic locus in these isolates and in lineage II strains. Three distinct clonal groups (groups 1 to 3) were identified among these isolates based on single-nucleotide polymorphism-based multilocus genotyping (MLGT) and DNA hybridization data. Groups 1 and 2 had MLGT haplotypes previously encountered among clinical isolates and were composed of clinical isolates from multiple states in the United States. In contrast, group 3 consisted of clinical and environmental isolates solely from North Carolina and exhibited a novel haplotype. In addition, all group 3 isolates had DNA that was resistant to MboI, suggesting methylation of adenines at GATC sites. Sequence analysis of the
lmo0734
to
lmo0739
gene cassette from two strains (group 1 and group 3) revealed that the genes were highly conserved (>99% identity). The data suggest relatively recent horizontal gene transfer from lineage II
L. monocytogenes
into
L. monocytogenes
serotype 4b and subsequent dissemination among at least three distinct clonal groups of
L. monocytogenes
serotype 4b, one of which exhibits restrictions in regional distribution.
Porticoccus hydrocarbonoclasticus sp. nov., an Aromatic Hydrocarbon-Degrading Bacterium Identified in Laboratory Cultures of Marine Phytoplankton
Authors: Gutierrez Tony , Nichols Peter D. , Whitman William B. , Aitken Michael D. 
Published: December 2011

ABSTRACT

A marine bacterium, designated strain MCTG13d, was isolated from a laboratory culture of the dinoflagellate
Lingulodinium polyedrum
CCAP1121/2 by enrichment with polycyclic aromatic hydrocarbons (PAHs) as the sole carbon source. Based on 16S rRNA gene sequence comparisons, the strain was most closely related to
Porticoccus litoralis
IMCC2115
T
(96.5%) and to members of the genera
Microbulbifer
(91.4 to 93.7%) and
Marinimicrobium
(90.4 to 92.0%). Phylogenetic trees showed that the strain clustered in a distinct phyletic line in the class
Gammaproteobacteria
for which
P. litoralis
is presently the sole cultured representative. The strain was strictly aerobic, rod shaped, Gram negative, and halophilic. Notably, it was able to utilize hydrocarbons as sole sources of carbon and energy, whereas sugars did not serve as growth substrates. The predominant isoprenoid quinone of strain MCTG13d was Q-8, and the dominant fatty acids were C
16:1ω7c
, C
18:1ω7c
, and C
16:0
. DNA G+C content for the isolate was 54.9 ± 0.42 mol%. Quantitative PCR primers targeting the 16S rRNA gene of this strain showed that this organism was common in other laboratory cultures of marine phytoplankton. On the basis of phenotypic and genotypic characteristics, strain MCTG13d represents a novel species of
Porticoccus
, for which the name
Porticoccus hydrocarbonoclasticus
sp. nov. is proposed. The discovery of this highly specialized hydrocarbon-degrading bacterium living in association with marine phytoplankton suggests that phytoplankton represent a previously unrecognized biotope of novel bacterial taxa that degrade hydrocarbons in the ocean.
Isolation and Characterization of Enterocin W, a Novel Two-Peptide Lantibiotic Produced by Enterococcus faecalis NKR-4-1
Authors: Sawa Naruhiko , Wilaipun Pongtep , Kinoshita Seisuke , Zendo Takeshi , Leelawatcharamas Vichien , Nakayama Jiro , Sonomoto Kenji 
Published: December 2011

ABSTRACT

Enterococcus faecalis
NKR-4-1 isolated from pla-ra produces a novel two-peptide lantibiotic, termed enterocin W, comprising Wα and Wβ. The structure of enterocin W exhibited similarity with that of plantaricin W. The two peptides acted synergistically, and their order of binding to the cell membrane was important for their inhibitory activity.
Microbial Community Composition and Dynamics of Moving Bed Biofilm Reactor Systems Treating Municipal Sewage
Authors: Biswas Kristi , Turner Susan J. 
Published: December 2011

ABSTRACTMoving bed biofilm reactor (MBBR) systems are increasingly used for municipal and industrial wastewater treatment, yet in contrast to activated sludge (AS) systems, little is known about their constituent microbial communities. This study investigated the community composition of two municipal MBBR wastewater treatment plants (WWTPs) in Wellington, New Zealand. Monthly samples comprising biofilm and suspended biomass were collected over a 12-month period. Bacterial and archaeal community composition was determined using a full-cycle community approach, including analysis of 16S rRNA gene libraries, fluorescencein situhybridization (FISH) and automated ribosomal intergenic spacer analysis (ARISA). Differences in microbial community structure and abundance were observed between the two WWTPs and between biofilm and suspended biomass. Biofilms from both plants were dominated byClostridiaand sulfate-reducing members of theDeltaproteobacteria(SRBs). FISH analyses indicated morphological differences in theDeltaproteobacteriadetected at the two plants and also revealed distinctive clustering between SRBs and members of theMethanosarcinales, which were the onlyArchaeadetected and were present in low abundance (<5%). Biovolume estimates of the SRBs were higher in biofilm samples from one of the WWTPs which receives both domestic and industrial waste and is influenced by seawater infiltration. The suspended communities from both plants were diverse and dominated by aerobic members of theGammaproteobacteriaandBetaproteobacteria.This study represents the first detailed analysis of microbial communities in full-scale MBBR systems and indicates that this process selects for distinctive biofilm and planktonic communities, both of which differ from those found in conventional AS systems.
Development of a Rapid and Sensitive Method Combining a Cellulose Ester Microfilter and a Real-Time Quantitative PCR Assay To Detect Campylobacter jejuni and Campylobacter coli in 20 Liters of Drinking Water or Low-Turbidity Waters
Authors: Tissier Adeline , Denis Martine , Hartemann Philippe , Gassilloud Benoît 
Published: December 2011

ABSTRACT

Investigations of
Campylobacter jejuni
and
Campylobacter coli
in samples of drinking water suspected of being at the origin of an outbreak very often lead to negative results. One of the reasons for this failure is the small volume of water typically used for detecting these pathogens (10 to 1,000 ml). The efficiencies of three microfilters and different elution procedures were determined using real-time quantitative PCR to propose a procedure allowing detection of
Campylobacter
in 20 liters of drinking water or low-turbidity water samples. The results showed that more than 80% of the bacteria inoculated in 1 liter of drinking water were retained on each microfilter. An elution with a solution containing 3% beef extract, 0.05 M glycine at pH 9, combined with direct extraction of the bacterial genomes retained on the cellulose ester microfilter, allowed recovery of 87.3% (±22% [standard deviation]) of
Campylobacter
per 1 liter of tap water. Recoveries obtained from 20-liter volumes of tap water spiked with a
C. coli
strain were 69.5% (±10.3%) and 78.5% (±15.1%) for 91 CFU and 36 CFU, respectively. Finally, tests performed on eight samples of 20 liters of groundwater collected from an alluvial well used for the production of drinking water revealed the presence of
C. jejuni
and
C. coli
genomes, whereas no bacteria were detected with the normative culture method in volumes ranging from 10 to 1,000 ml. In the absence of available epidemiological data and information on bacterial viability, these last results indicate only that the water resource is not protected from contamination by
Campylobacter
.
S-Layer Homology Domain Proteins Csac_0678 and Csac_2722 Are Implicated in Plant Polysaccharide Deconstruction by the Extremely Thermophilic Bacterium Caldicellulosiruptor saccharolyticus
Authors: Ozdemir Inci , Blumer-Schuette Sara E. , Kelly Robert M. 
Published: December 2011

ABSTRACT

The genus
Caldicellulosiruptor
contains extremely thermophilic bacteria that grow on plant polysaccharides. The genomes of
Caldicellulosiruptor
species reveal certain surface layer homology (SLH) domain proteins that have distinguishing features, pointing to a role in lignocellulose deconstruction. Two of these proteins in
Caldicellulosiruptor saccharolyticus
(Csac_0678 and Csac_2722) were examined from this perspective. In addition to three contiguous SLH domains, the Csac_0678 gene encodes a glycoside hydrolase family 5 (GH5) catalytic domain and a family 28 carbohydrate-binding module (CBM); orthologs to Csac_0678 could be identified in all genome-sequenced
Caldicellulosiruptor
species. Recombinant Csac_0678 was optimally active at 75°C and pH 5.0, exhibiting both endoglucanase and xylanase activities. SLH domain removal did not impact Csac_0678 GH activity, but deletion of the CBM28 domain eliminated binding to crystalline cellulose and rendered the enzyme inactive on this substrate. Csac_2722 is the largest open reading frame (ORF) in the
C. saccharolyticus
genome (predicted molecular mass of 286,516 kDa) and contains two putative sugar-binding domains, two Big4 domains (bacterial domains with an immunoglobulin [Ig]-like fold), and a cadherin-like (Cd) domain. Recombinant Csac_2722, lacking the SLH and Cd domains, bound to cellulose and had detectable carboxymethylcellulose (CMC) hydrolytic activity. Antibodies directed against Csac_0678 and Csac_2722 confirmed that these proteins bound to the
C. saccharolyticus
S-layer. Their cellular localization and functional biochemical properties indicate roles for Csac_0678 and Csac_2722 in recruitment and hydrolysis of complex polysaccharides and the deconstruction of lignocellulosic biomass. Furthermore, these results suggest that related SLH domain proteins in other
Caldicellulosiruptor
genomes may also be important contributors to plant biomass utilization.
Binding of Human GII.4 Norovirus Virus-Like Particles to Carbohydrates of Romaine Lettuce Leaf Cell Wall Materials
Authors: Esseili Malak A. , Wang Qiuhong , Saif Linda J. 
Published: December 2011

ABSTRACT

Norovirus (NoV) genogroup II genotype 4 (GII.4) strains are the dominant cause of the majority of food-borne outbreaks, including those that involve leafy greens, such as lettuce. Since human NoVs use carbohydrates of histo-blood group antigens as receptors/coreceptors, we examined the role of carbohydrates in the attachment of NoV to lettuce leaves by using virus-like particles (VLPs) of a human NoV/GII.4 strain. Immunofluorescence analysis showed that the VLPs attached to the leaf surface, especially to cut edges, stomata, and along minor veins. Binding was quantified using enzyme-linked immunosorbent assay (ELISA) performed on cell wall materials (CWM) from innermost younger leaves and outermost lamina of older leaves. The binding to CWM of older leaves was significantly (
P
< 0.05) higher (1.5- to 2-fold) than that to CWM of younger leaves. Disrupting the carbohydrates of CWM or porcine gastric mucin (PGM) (a carbohydrate control) using 100 mM sodium periodate (NaIO
4
) significantly decreased the binding an average of 17% in younger leaves, 43% in older leaves, and 92% for PGM. In addition, lectins recognizing GalNAc, GlcNAc, and sialic acid at 100 μg/ml significantly decreased the binding an average of 41%, 33%, and 20% on CWM of older leaves but had no effect on younger leaves. Lectins recognizing α-
d
-Gal, α-
d
-Man/α-
d
-Glc, and α-
l
-Fuc showed significant inhibition on CWM of older leaves as well as that of younger leaves. All lectins, except for the lectin recognizing α-
d
-Gal, significantly inhibited NoV VLP binding to PGM. Collectively, our results indicate that NoV VLPs bind to lettuce CWM by utilizing multiple carbohydrate moieties. This binding may enhance virus persistence on the leaf surface and prevent effective decontamination.
Transcription Factor Efg1 Shows a Haploinsufficiency Phenotype in Modulating the Cell Wall Architecture and Immunogenicity of Candida albicans
Authors: Zavrel Martin , Majer Olivia , Kuchler Karl , Rupp Steffen 
Published: December 2011

ABSTRACTTheCandida albicanstranscription factor Efg1 is known to be involved in many different cellular processes, including morphogenesis, general metabolism, and virulence. Here we show that besides its manifold roles, Efg1 also has a prominent effect on cell wall structure and composition, strongly affecting the structural glucan part. Deletion of only one allele ofEFG1already results in severe phenotypes for cell wall biogenesis, comparable to those with deletion of both alleles, indicative of a severe haploinsufficiency forEFG1. The observed defects in structural setup of the cell wall, together with previously reported alterations in expression of cell surface proteins, result in altered immunogenic properties of strains with compromised Efg1 function. This is shown by interaction studies with macrophages and primary dendritic cells. The structural changes in the cell wall carbohydrate meshwork presented here, together with the manifold changes in cell wall protein composition and metabolism reported in other studies, contribute to the altered immune response mounted by innate immune cells and to the altered virulence phenotypes observed for strains lackingEFG1.
Heterogeneous Expression of the Virulence-Related Adhesin Epa1 between Individual Cells and Strains of the Pathogen Candida glabrata
Authors: Halliwell Samantha C. , Smith Matthew C. A. , Muston Philippa , Holland Sara L. , Avery Simon V. 
Published: December 2011

ABSTRACT

We investigated the relevance of gene expression heterogeneity to virulence properties of a major fungal pathogen,
Candida glabrata
. The organism's key virulence-associated factors include glycosylphosphatidylinositol-anchored adhesins, encoded subtelomerically by the
EPA
gene family. Individual-cell analyses of expression revealed very striking heterogeneity for Epa1, an adhesin that mediates ∼95% of adherence to epithelial cells
in vitro
. The heterogeneity in Epa1 was markedly greater than that known for other yeast genes. Sorted cells expressing high or low levels of Epa1 exhibited high and low adherence to epithelial cells, indicating a link between gene expression noise and potential virulence. The phenotypes of sorted subpopulations reverted to mixed phenotypes within a few generations. Variation in single-cell Epa1 protein and mRNA levels was correlated, consistent with transcriptional regulation of heterogeneity. Sir-dependent transcriptional silencing was the primary mechanism driving heterogeneous Epa1 expression in
C. glabrata
BG2, but not in CBS138 (ATCC 2001). Inefficient silencing in the latter strain was not due to a difference in
EPA1
sequence or (sub)telomere length and was overcome by ectopic
SIR3
expression. Moreover, differences between strains in the silencing dependence of
EPA1
expression were evident across a range of clinical isolates, with heterogeneity being the greatest in strains where
EPA1
was subject to silencing. The study shows how heterogeneity can impact the virulence-related properties of
C. glabrata
cell populations, with potential implications for microbial pathogenesis more broadly.
Synthetic Lethality of the
lytE cwlO
Genotype in Bacillus subtilis Is Caused by Lack of
d
,
l
-Endopeptidase Activity at the Lateral Cell Wall
Authors: Hashimoto Masayuki , Ooiwa Seika , Sekiguchi Junichi 
Published: December 2011

ABSTRACT

Bacterial peptidoglycan acts as an exoskeleton to protect the bacterial cell. Although peptidoglycan biosynthesis by penicillin-binding proteins is well studied, few studies have described peptidoglycan disassembly, which is necessary for a dynamic structure that allows cell growth. In
Bacillus subtilis
, more than 35 genes encoding cell wall lytic enzymes have been identified; however, only two
d
,
l
-endopeptidases (
lytE
and
cwlO
) are involved in cell proliferation. In this study, we demonstrated that the
d
,
l
-endopeptidase activity at the lateral cell wall is essential for cell proliferation. Inactivation of LytE and CwlO by point mutation of the catalytic residues caused cell growth defects. However, the forced expression of LytF or CwlS, which are paralogs of LytE, did not suppress
lytE cwlO
synthetic lethality. Subcellular localization studies of these
d
,
l
-endopeptidases showed LytF and CwlS at the septa and poles, CwlO at the cylindrical part of the cell, and LytE at the septa and poles as well as the cylindrical part. Furthermore, construction of N-terminal and C-terminal domain-swapped enzymes of LytE, LytF, CwlS, and CwlO revealed that localization was dependent on the N-terminal domains. Only the chimeric proteins that were enzymatically active and localized to the sidewall were able to suppress the synthetic lethality, suggesting that the lack of
d
,
l
-endopeptidase activity at the cylindrical part of the cell leads to a growth defect. The functions of LytE and CwlO in cell morphogenesis were discussed.