bluuebunny/crossref_metadata_2025_split huggingface dataset:
APPLICATION OF THE TAGUCHI METHOD TO OPTIMIZE MONASCUS SPP. CULTURE
Authors: CHUNG C.C. , CHEN H.H. , HSIEH P.C. 
Published: April 2007

ABSTRACT The Taguchi method was applied to determine optimum conditions for submerged culture of Monascus spp. fermentation to produce a high yield of monacolin K (also known as lovastain, mevinolin or mevacor). The control factors included carbon, nitrogen, oil, and salt sources and pH values. In the growth phase the optimum culture conditions are 1% whole wheat flour, l% peptone, 0.01% olive oil and 0.01% potassium phosphate and a pH of 5.0 (P < 0.05). In the metabolic phase the optimal culture conditions are 1% whole wheat flour, 1% peptone, 0.01% soybean oil, 0.01% potassium phosphate and a pH of 3.0 (P < 0.001). Using optimal culture conditions in the growth and metabolic phases, the yield of monacolin K in the fermentation process was 151.06 ppm.
CHARACTERIZING QUALITY OF RENDERED DUCK FAT COMPARED TO OTHER FATS AND OILS
Authors: GONG YUANSHENG , WEBER PETER F. , RICHARDS MARK P. 
Published: April 2007

ABSTRACT The characteristics of rendered duck fat (RDF) were compared to commercial sources of soybean oil, lard, tallow, butter and olive oil. RDF was highly susceptible to lipid oxidation during storage compared to the other fats and oils. However, 0.005% tert‐butyl hydroquinone delayed the onset of lipid oxidation to an extent that was comparable to the lag phase observed in the commercial fats and oils. Positive attributes of RDF included a relatively high oleic acid content and low saturated fat content. Undesirable attributes of RDF included a lack of conjugated linoleic acid (CLA) and intermediate levels of trans fatty acids (TFA) compared to the other lipid sources. Decreasing the time and temperature of rendering decreased the TFA content in RDF. Around one‐half of the TFA content in RDF was vaccenic acid which is converted to CLA after ingestion.
Barriers to nurse entrepreneurship: A study of the process model of entrepreneurship
Authors: Elango B. , Hunter Gary L. , Winchell Mike 
Published: April 2007

AbstractPurpose: The potential for nurse entrepreneurship to contribute to the effectiveness of healthcare delivery is well acknowledged, yet it has not been fully realized. Using the process model of entrepreneurship, we attempted to glean information from nursing professionals through focus groups on the barriers to starting a business.Data sources: Two focus groups were used and expert moderators conducted these exercises. The first focus group included two hospital administrators, a nurse entrepreneur, an ophthalmology entrepreneur, and a dean of the nursing school familiar with nurse entrepreneurship. The second focus group used 20 students in a nurse practitioner program.Conclusions: The study findings indicate nurse practitioners and other nursing professionals do recognize the potential of nurse entrepreneurship. However, several barriers prevent them from exploiting the identified opportunity.Implications for practice: While the barriers are significant, we believe they can be overcome with coordinated action by individual nurses, professional associations, and public policy initiatives. Several suggestions are offered to nurses seeking to become nurse entrepreneurs.
TAKING THE PUZZLE OUT OF THE PURCHASING POWER PARITY PUZZLE: AN APPLICATION IN RESPECT OF SOUTH AFRICA
Authors: Mokoena Tm 
Published: April 2007

AbstractThis paper discusses two versions of the purchasing power parity puzzle. It presents the results of nonlinearity and nonstationarity tests in respect of the real exchange rates of the rand. It is found that the rand real exchange rate behaviour tends to be nonlinear and stationary in a majority of cases in the sample. This suggests that for the majority of the currencies in the sample, the real exchange rates of the rand are mean‐reverting, implying that the purchasing power parity relation holds in a nonlinear manner.
Sonoporation Is an Efficient Tool for Intracellular Fluorescent Dextran Delivery and One-Step Double-Crossover Mutant Construction in
Fusobacterium nucleatum
Authors: Han Yiping W. , Ikegami Akihiko , Chung Peter , Zhang Lei , Deng Cheri X. 
Published: April 2007

ABSTRACT

Studies of microorganisms are often hindered by a lack of effective genetic tools. One such example is
Fusobacterium nucleatum
, a gram-negative anaerobe associated with various human infections, including those causing periodontal disease and preterm birth. The first double-crossover allelic-exchange mutant in
F. nucleatum
was recently constructed using sonoporation, a novel ultrasound-mediated intracellular delivery method, demonstrating potential for bacterial gene transfection. To better unveil its mechanism, the current study examines the factors affecting the outcome of sonoporation. Delivery of Texas Red-conjugated dextran into
F. nucleatum
by sonoporation was at least twice as efficient as that by electroporation, and sonoporation was nonbactericidal, unlike electroporation. The delivery efficiency was affected by the acoustic pressure amplitude, the duty cycle, and the quantity of microbubbles used to initiate cavitation but not by the pulse repetition frequency of ultrasound application. To examine the involvement of homologous recombination in sonoporation-mediated mutant construction, the highly conserved
recA
gene, which carried most of the consensus residues, including the P loop, was identified in
F. nucleatum
, and a double-crossover
recA
mutant of
F. nucleatum
12230, US1610, was constructed by sonoporation. The mutant exhibited increased sensitivity to UV exposure compared with that of the wild type, indicating that the RecA function in
F. nucleatum
was conserved. Interestingly, US1610 was also sensitive to ultrasound treatment, suggesting the likely involvement of RecA in postsonoporation repair and survival. Since sonoporation has consistently generated one-step double-crossover mutants in
F. nucleatum
by use of intact suicide plasmids, this technology may be developed into an efficient tool for streamlining mutant construction in bacteria.
Detection and Transformation of Genome Segments That Differ within a Coastal Population of
Vibrio cholerae
Strains
Authors: Miller Michael C. , Keymer Daniel P. , Avelar Abigail , Boehm Alexandria B. , Schoolnik Gary K. 
Published: April 2007

ABSTRACT

Vibrio cholerae
is an autochthonous member of diverse aquatic ecosystems around the globe. Collectively, the genomes of environmental
V. cholerae
strains comprise a large repository of encoded functions which can be acquired by individual
V. cholerae
lineages through uptake and recombination. To characterize the genomic diversity of environmental
V. cholerae
, we used comparative genome hybridization to study 41 environmental strains isolated from diverse habitats along the central California coast, a region free of endemic cholera. These data were used to classify genes of the epidemic
V. cholerae
O1 sequenced strain N16961 as conserved, variably present, or absent from the isolates. For the most part, absent genes were restricted to large mobile elements and have known functions in pathogenesis. Conversely, genes present in some, but not all, California isolates were in smaller contiguous clusters and were less likely to be near genes with functions in DNA mobility. Two such clusters of variable genes encoding different selectable metabolic phenotypes (mannose and diglucosamine utilization) were transformed into the genomes of environmental isolates by chitin-dependent competence, indicating that this mechanism of general genetic exchange is conserved among
V. cholerae
. The transformed DNA had an average size of 22.7 kbp, demonstrating that natural competence can mediate the movement of large chromosome fragments. Thus, whether variable genes arise through the acquisition of new sequences by horizontal gene transfer or by the loss of preexisting DNA though deletion, natural transformation provides a mechanism by which
V. cholerae
clones can gain access to the
V. cholerae
pan-genome.
Lactobacillus rhamnosus
Strain GG Reduces Aflatoxin B
1
Transport, Metabolism, and Toxicity in Caco-2 Cells
Authors: Gratz S. , Wu Q. K. , El-Nezami H. , Juvonen R. O. , Mykkänen H. , Turner P. C. 
Published: April 2007

ABSTRACT

The probiotic
Lactobacillus rhamnosus
GG is able to bind the potent hepatocarcinogen aflatoxin B
1
(AFB
1
) and thus potentially restrict its rapid absorption from the intestine. In this study we investigated the potential of GG to reduce AFB
1
availability in vitro in Caco-2 cells adapted to express cytochrome P-450 (CYP) 3A4, such that both transport and toxicity could be assessed. Caco-2 cells were grown as confluent monolayers on transmembrane filters for 21 days prior to all studies. AFB
1
levels in culture medium were measured by high-performance liquid chromatography. In CYP 3A4-induced monolayers, AFB
1
transport from the apical to the basolateral chamber was reduced from 11.1% ± 1.9% to 6.4% ± 2.5% (
P
= 0.019) and to 3.3% ± 1.8% (
P
= 0.002) within the first hour in monolayers coincubated with GG (1 × 10
10
and 5 × 10
10
CFU/ml, respectively). GG (1 × 10
10
and 5 × 10
10
CFU/ml) bound 40.1% ± 8.3% and 61.0% ± 6.0% of added AFB
1
after 1 h, respectively. AFB
1
caused significant reductions of 30.1% (
P
= 0.01), 49.4% (
P
= 0.004), and 64.4% (
P
< 0.001) in transepithelial resistance after 24, 48, and 72 h, respectively. Coincubation with 1 × 10
10
CFU/ml GG after 24 h protected against AFB
1
-induced reductions in transepithelial resistance at both 24 h (
P
= 0.002) and 48 h (
P
= 0.04). DNA fragmentation was apparent in cells treated only with AFB
1
cells but not in cells coincubated with either 1 × 10
10
or 5 × 10
10
CFU/ml GG. GG reduced AFB
1
uptake and protected against both membrane and DNA damage in the Caco-2 model. These data are suggestive of a beneficial role of GG against dietary exposure to aflatoxin.
PfGCN5-Mediated Histone H3 Acetylation Plays a Key Role in Gene Expression in
Plasmodium falciparum
Authors: Cui Long , Miao Jun , Furuya Tetsuya , Li Xinyi , Su Xin-zhuan , Cui Liwang 
Published: April 2007

ABSTRACT

Histone acetylation, regulated by the opposing actions of histone acetyltransferases (HATs) and deacetylases, is an important epigenetic mechanism in eukaryotic transcription. Although an acetyltransferase (PfGCN5) has been shown to preferentially acetylate histone H3 at K9 and K14 in
Plasmodium falciparum
, the scale of histone acetylation in the parasite genome and its role in transcriptional activation are essentially unknown. Using chromatin immunoprecipitation (ChIP) and DNA microarray, we mapped the global distribution of PfGCN5, histone H3K9 acetylation (H3K9ac) and trimethylation (H3K9m3) in the
P. falciparum
genome. While the chromosomal distributions of H3K9ac and PfGCN5 were similar, they are radically different from that of H3K9m3. In addition, there was a positive, though weak correlation between relative occupancy of H3K9ac on individual genes and the levels of gene expression, which was inversely proportional to the distance of array elements from the putative translational start codons. In contrast, H3K9m3 was negatively correlated with gene expression. Furthermore, detailed mapping of H3K9ac for selected genes using ChIP and real-time PCR in three erythrocytic stages detected stage-specific peak H3K9ac enrichment at the putative transcriptional initiation sites, corresponding to stage-specific expression of these genes. These data are consistent with H3K9ac and H3K9m3 as epigenetic markers of active and silent genes, respectively. We also showed that treatment with a PfGCN5 inhibitor led to reduced promoter H3K9ac and gene expression. Collectively, these results suggest that PfGCN5 is recruited to the promoter regions of genes to mediate histone acetylation and activate gene expression in
P. falciparum
.
Regulation of the
Pseudomonas aeruginosa
Quorum-Sensing Regulator VqsR
Authors: Li Luen-Luen , Malone Jane E. , Iglewski Barbara H. 
Published: April 2007

ABSTRACT

Bacteria communicate with each other to regulate cell density-dependent gene expression via a quorum-sensing (QS) cascade. In
Pseudomonas aeruginosa
, two known QS systems,
las
and
rhl
, control the expression of many factors that relate to virulence, pathogenicity, and biofilm development. Microarray studies of the
las
and
rhl
regulons led to our hypothesis that a complicated hierarchy in the QS regulon is composed of multiple transcriptional regulators. Here, we examined a QS-regulated gene,
vqsR
, which encodes a probable transcriptional regulator with a putative 20-bp operator sequence (
las
box) upstream. The transcriptional start site for
vqsR
was determined. The
vqsR
promoter was identified by examining a series of
vqsR
promoter-
lacZ
fusions. In addition, an
Escherichia coli
system where either LasR or RhlR protein was expressed from a plasmid indicated that the
las
system was the dominant regulator for
vqsR
. Electrophoretic mobility shift assays (EMSA) demonstrate that purified LasR protein binds directly to the
vqsR
promoter in the presence of 3O-C
12
-HSL. Point mutational analysis of the
vqsR las
box suggests that positions 3 and 18 in the
las
box are important for
vqsR
transcription, as assayed with a series of
vqsRp-lacZ
fusions. EMSA also shows that positions 3 and 18 are important for binding between the
vqsR
promoter and LasR. Our results demonstrate that the
las
system directly regulates
vqsR
, and certain nucleotides in the
las
box are crucial for LasR binding and activation of the
vqsR
promoter.
The NsrR Regulon of
Escherichia coli
K-12 Includes Genes Encoding the Hybrid Cluster Protein and the Periplasmic, Respiratory Nitrite Reductase
Authors: Filenko Nina , Spiro Stephen , Browning Douglas F. , Squire Derrick , Overton Tim W. , Cole Jeff , Constantinidou Chrystala 
Published: April 2007

ABSTRACT

Successful pathogens must be able to protect themselves against reactive nitrogen species generated either as part of host defense mechanisms or as products of their own metabolism. The regulatory protein NsrR (a member of the Rrf2 family of transcription factors) plays key roles in this stress response. Microarray analysis revealed that NsrR represses nine operons encoding 20 genes in
Escherichia coli
MG1655, including the
hmpA
,
ytfE
, and
ygbA
genes that were previously shown to be regulated by NsrR. Novel NsrR targets revealed by this study include
hcp-hcr
(which were predicted in a recent bioinformatic study to be NsrR regulated) and the well-studied
nrfA
promoter that directs the expression of the periplasmic respiratory nitrite reductase. Conversely, transcription from the
ydbC
promoter is strongly activated by NsrR. Regulation of the
nrf
operon by NsrR is consistent with the ability of the periplasmic nitrite reductase to reduce nitric oxide and hence protect against reactive nitrogen species. Gel retardation assays were used to show that both FNR and NarL bind to the
hcp
promoter. The expression of
hcp
and the contiguous gene
hcr
is not induced by hydroxylamine. As
hmpA
and
ytfE
encode a nitric oxide reductase and a mechanism to repair iron-sulfur centers damaged by nitric oxide, the demonstration that
hcp-hcr
,
hmpA
, and
ytfE
are the three transcripts most tightly regulated by NsrR highlights the possibility that the hybrid cluster protein, HCP, might also be part of a defense mechanism against reactive nitrogen stress.
Comparative Genome Analysis of Four Magnetotactic Bacteria Reveals a Complex Set of Group-Specific Genes Implicated in Magnetosome Biomineralization and Function
Authors: Richter Michael , Kube Michael , Bazylinski Dennis A. , Lombardot Thierry , Glöckner Frank Oliver , Reinhardt Richard , Schüler Dirk 
Published: April 2007

ABSTRACT

Magnetotactic bacteria (MTB) are a heterogeneous group of aquatic prokaryotes with a unique intracellular organelle, the magnetosome, which orients the cell along magnetic field lines. Magnetotaxis is a complex phenotype, which depends on the coordinate synthesis of magnetosomes and the ability to swim and orient along the direction caused by the interaction with the Earth's magnetic field. Although a number of putative magnetotaxis genes were recently identified within a conserved genomic magnetosome island (MAI) of several MTB, their functions have remained mostly unknown, and it was speculated that additional genes located outside the MAI might be involved in magnetosome formation and magnetotaxis. In order to identify genes specifically associated with the magnetotactic phenotype, we conducted comparisons between four sequenced magnetotactic
Alphaproteobacteria
including the nearly complete genome of
Magnetospirillum gryphiswaldense
strain MSR-1, the complete genome of
Magnetospirillum magneticum
strain AMB-1, the complete genome of the magnetic coccus MC-1, and the comparative-ready preliminary genome assembly of
Magnetospirillum magnetotacticum
strain MS-1 against an in-house database comprising 426 complete bacterial and archaeal genome sequences. A magnetobacterial core genome of about 891 genes was found shared by all four MTB. In addition to a set of approximately 152 genus-specific genes shared by the three
Magnetospirillum
strains, we identified 28 genes as group specific, i.e., which occur in all four analyzed MTB but exhibit no (MTB-specific genes) or only remote (MTB-related genes) similarity to any genes from nonmagnetotactic organisms and which besides various novel genes include nearly all
mam
and
mms
genes previously shown to control magnetosome formation. The MTB-specific and MTB-related genes to a large extent display synteny, partially encode previously unrecognized magnetosome membrane proteins, and are either located within (18 genes) or outside (10 genes) the MAI of
M. gryphiswaldense
. These genes, which represent less than 1% of the 4,268 open reading frames of the MSR-1 genome, as yet are mostly of unknown functions but are likely to be specifically involved in magnetotaxis and, thus, represent prime targets for future experimental analysis.
Genes, Enzymes, and Regulation of
para
-Cresol Metabolism in
Geobacter metallireducens
Authors: Peters Franziska , Heintz Dimitri , Johannes Jörg , van Dorsselaer Alain , Boll Matthias 
Published: April 2007

ABSTRACT

In aerobic and facultatively anaerobic bacteria, the degradation of
para
-cresol (
p
-cresol) involves the initial hydroxylation to
p
-hydroxybenzyl alcohol by water catalyzed by the soluble, periplasmatic flavocytochrome
p
-cresol methylhydroxylase (PCMH; α
2
β
2
composition). In denitrifying bacteria the further metabolism proceeds via oxidation to
p
-hydroxybenzoate, the formation of
p
-hydroxybenzoyl-coenzyme A (CoA), and the subsequent dehydroxylation of the latter to benzoyl-CoA by reduction. In contrast, the strictly anaerobic
Desulfobacterium cetonicum
degrades
p
-cresol by addition to fumarate, yielding
p
-hydroxybenzylsuccinate. In this work, in vitro enzyme activity measurements revealed that the obligately anaerobic
Geobacter metallireducens
uses the
p
-cresol degradation pathway of denitrifying bacteria. Surprisingly, PCMH, which is supposed to catalyze both
p
-cresol hydroxylation and
p
-hydroxybenzyl alcohol oxidation to the corresponding aldehyde, was located in the membrane fraction. The α subunit of the enzyme was present in two isoforms, suggesting an αα′β
2
composition. We propose that the unusual asymmetric architecture and the membrane association of PCMH might be important for alternative electron transfer routes to either cytochrome
c
(in the case of
p
-cresol oxidation) or to menaquinone (in the case of
p
-hydroxybenzyl alcohol oxidation). Unusual properties of further enzymes of
p
-cresol metabolism,
p
-hydroxybenzoate-CoA ligase, and
p
-hydroxybenzoyl-CoA reductase were identified and are discussed. A proteomic approach identified a gene cluster comprising most of the putative structural genes for enzymes involved in
p
-cresol metabolism (
pcm
genes). Reverse transcription-PCR studies revealed a different regulation of transcription of
pcm
genes and the corresponding enzyme activities, suggesting the presence of posttranscriptional regulatory elements.
Multiple Controls Regulate the Expression of
mobE
, an HNH Homing Endonuclease Gene Embedded within a Ribonucleotide Reductase Gene of Phage Aeh1
Authors: Gibb Ewan A. , Edgell David R. 
Published: April 2007

ABSTRACT

Mobile genetic elements have the potential to influence the expression of genes surrounding their insertion site upon invasion of a genome. Here, we examine the transcriptional organization of a ribonucleotide reductase operon (
nrd
) that has been invaded by an HNH family homing endonuclease,
mobE
. In
Aeromonas hydrophila
phage Aeh1,
mobE
has inserted into the large-subunit gene (
nrdA
) of aerobic ribonucleotide reductase (RNR), splitting it into two smaller genes,
nrdA-a
and
nrdA-b
. This gene organization differs from that in phages T4, T6, RB2, RB3, RB15, and LZ7, where
mobE
is inserted in the
nrdA-nrdB
intergenic region. We present evidence that the expression of Aeh1
mobE
is regulated by transcriptional, posttranscriptional, and translational controls. An Aeh1-specific late promoter drives expression of
mobE
, but strikingly the
mobE
transcript is processed internally at an RNase E-like site. We also identified a putative stem-loop structure upstream of
mobE
that sequesters the
mobE
ribosome binding site, presumably acting to down regulate MobE translation. Moreover, our transcriptional analyses indicate that the surrounding
nrd
genes of phage Aeh1 are expressed by a different strategy than are the corresponding phage T4 genes and that transcriptional readthrough is the only mechanism by which the promoterless Aeh1
nrdB
gene is expressed. We suggest that the occurrence of multiple layers of control to limit the expression of
mobE
to late in the Aeh1 infection cycle is an adaptation of Aeh1 to reduce any effects on expression of the surrounding
nrd
genes early in phage infection when RNR function is critical.
Role of
Escherichia coli
DNA Polymerase I in Conferring Viability upon the
dnaN159
Mutant Strain
Authors: Maul Robert W. , Sanders Laurie H. , Lim James B. , Benitez Rosemary , Sutton Mark D. 
Published: April 2007

ABSTRACT

The
Escherichia coli dnaN159
allele encodes a mutant form of the β-sliding clamp (β159) that is impaired for interaction with the replicative DNA polymerase (Pol), Pol III. In addition, strains bearing the
dnaN159
allele require functional Pol I for viability. We have utilized a combination of genetic and biochemical approaches to characterize the role(s) played by Pol I in the
dnaN159
strain. Our findings indicate that elevated levels of Pol I partially suppress the temperature-sensitive growth phenotype of the
dnaN159
strain. In addition, we demonstrate that the β clamp stimulates the processivity of Pol I in vitro and that β159 is impaired for this activity. The reduced ability of β159 to stimulate Pol I in vitro correlates with our finding that single-stranded DNA (ssDNA) gap repair is impaired in the
dnaN159
strain. Taken together, these results suggest that (i) the β clamp-Pol I interaction may be important for proper Pol I function in vivo and (ii) in the absence of Pol I, ssDNA gaps may persist in the
dnaN159
strain, leading to lethality of the
dnaN159
Δ
polA
strain.
Restraint in Order to Feed: Justifying a Lawful Policy for the UK
Authors: Gabe Simon , Sayers Gwen 
Published: April 2007

AbstractIn the UK, restraining medical patients in order to provide care is widely considered to be outmoded and difficult to justify. The prevailing clinical intuition that restraining patients is generally wrong (even when restraint is essential in order to provide artificial nutrition and hydration) has prompted us to develop a policy that is compatible with common law, the Mental Capacity Act 2005 and the Human Rights Act 1998. The nature and scope of the problem are illustrated with clinical cases. These, in turn, serve to demonstrate the tension that arises between article 2, article 3 and article 8 rights, when incompetent patients are restrained in order to feed.