bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resistance training increases skeletal muscle oxidative capacity and net intramuscular triglyceride breakdown in type I and II fibres of sedentary males
Authors: Shepherd S. O. , Cocks M. , Tipton K. D. , Witard O. C. , Ranasinghe A. M. , Barker T. A. , Wagenmakers A. J. M. , Shaw C. S. 
Published: April 2014

New Findings
What is the central question of this study?
Recent research from our laboratory, supported by in vitro effects of perilipins, suggested that improvements in insulin sensitivity following endurance training are mechanistically linked to increases in muscle oxidative capacity, intramuscular triglyceride utilization during moderate endurance exercise and increases in the content of the lipid droplet‐associated perilipins 2 and 5. This study aimed to investigate whether these adaptations also occur in response to resistance training.
What is the main finding and its importance?
Six weeks of resistance training increased all the mentioned variables. These novel data suggest that improvements in muscle oxidative capacity and lipid metabolism contribute to the increase in insulin sensitivity following resistance training.
Recent in vitro and in vivo experimental observations suggest that improvements in insulin sensitivity following endurance training are mechanistically linked to increases in muscle oxidative capacity, intramuscular triglyceride (IMTG) utilization during endurance exercise and increases in the content of the lipid droplet‐associated perilipin 2 (PLIN2) and perilipin 5 (PLIN5). This study investigated the hypothesis that similar adaptations may also underlie the resistance training (RT)‐induced improvements in insulin sensitivity. Thirteen sedentary men (20 ± 1 years old; body mass index 24.8 ± 0.8 kg m−2) performed 6 weeks of whole‐body RT (three times per week), and changes in peak O2 uptake (in millilitres per minute per kilogram) and insulin sensitivity were assessed. Muscle biopsies (n = 8) were obtained before and after 60 min steady‐state cycling at ∼65% peak O2 uptake. Immunofluorescence microscopy was used to assess changes in oxidative capacity (measured as cytochrome c oxidase protein content), IMTG and PLIN2 and PLIN5 protein content. Resistance training increased peak O2 uptake (by 8 ± 3%), COX protein content (by 46 ± 13 and 61 ± 13% in type I and II fibres, respectively) and the Matsuda insulin sensitivity index (by 47 ± 6%; all P < 0.05). In type I fibres, IMTG (by 52 ± 11%; P < 0.05) and PLIN2 content (by 107 ± 19%; P < 0.05) were increased and PLIN5 content tended to increase (by 54 ± 22%; P = 0.054) post‐training. In type II fibres, PLIN2 content increased (by 57 ± 20%; P < 0.05) and IMTG (by 46 ± 17%; P = 0.1) and PLIN5 content (by 44 ± 24%; P = 0.054) tended to increase post‐training. Breakdown of IMTG during moderate‐intensity exercise was greater in both type I and type II fibres (by 43 ± 5 and 37 ± 5%, respectively; P < 0.05) post‐RT. The results confirm the hypothesis that RT enhances muscle oxidative capacity and increases IMTG breakdown and the content of PLIN2 and PLIN5 in both type I and type II fibres during endurance‐type exercise.
Mass and Density Measurements of Live and Dead Gram-Negative and Gram-Positive Bacterial Populations
Authors: Lewis Christina L. , Craig Caelli C. , Senecal Andre G. 
Published: April 2014

ABSTRACT

Monitoring cell growth and measuring physical features of food-borne pathogenic bacteria are important for better understanding the conditions under which these organisms survive and proliferate. To address this challenge, buoyant masses of live and dead
Escherichia coli
O157:H7 and
Listeria innocua
were measured using Archimedes, a commercially available suspended microchannel resonator (SMR). Cell growth was monitored with Archimedes by observing increased cell concentration and buoyant mass values of live growing bacteria. These growth data were compared to optical density measurements obtained with a Bioscreen system. We observed buoyant mass measurements with Archimedes at cell concentrations between 10
5
and 10
8
cells/ml, while growth was not observed with optical density measurements until the concentration was 10
7
cells/ml. Buoyant mass measurements of live and dead cells with and without exposure to hydrogen peroxide stress were also compared; live cells generally had a larger buoyant mass than dead cells. Additionally, buoyant mass measurements were used to determine cell density and total mass for both live and dead cells. Dead
E. coli
cells were found to have a larger density and smaller total mass than live
E. coli
cells. In contrast, density was the same for both live and dead
L. innocua
cells, while the total mass was greater for live than for dead cells. These results contribute to the ongoing challenge to further develop existing technologies used to observe cell populations at low concentrations and to measure unique physical features of cells that may be useful for developing future diagnostics.
Transcription of Two Adjacent Carbohydrate Utilization Gene Clusters in Bifidobacterium breve UCC2003 Is Controlled by LacI- and Repressor Open Reading Frame Kinase (ROK)-Type Regulators
Authors: O'Connell Kerry Joan , O'Connell Motherway Mary , Liedtke Andrea , Fitzgerald Gerald F. , Ross R. Paul , Stanton Catherine , Zomer Aldert , van Sinderen Douwe 
Published: April 2014

ABSTRACT

Members of the genus
Bifidobacterium
are commonly found in the gastrointestinal tracts of mammals, including humans, where their growth is presumed to be dependent on various diet- and/or host-derived carbohydrates. To understand transcriptional control of bifidobacterial carbohydrate metabolism, we investigated two genetic carbohydrate utilization clusters dedicated to the metabolism of raffinose-type sugars and melezitose. Transcriptomic and gene inactivation approaches revealed that the raffinose utilization system is positively regulated by an activator protein, designated RafR. The gene cluster associated with melezitose metabolism was shown to be subject to direct negative control by a LacI-type transcriptional regulator, designated MelR1, in addition to apparent indirect negative control by means of a second LacI-type regulator, MelR2.
In silico
analysis, DNA-protein interaction, and primer extension studies revealed the MelR1 and MelR2 operator sequences, each of which is positioned just upstream of or overlapping the correspondingly regulated promoter sequences. Similar analyses identified the RafR binding operator sequence located upstream of the
rafB
promoter. This study indicates that transcriptional control of gene clusters involved in carbohydrate metabolism in bifidobacteria is subject to conserved regulatory systems, representing either positive or negative control.
Population Structure of Listeria monocytogenes Serotype 4b Isolates from Sporadic Human Listeriosis Cases in the United States from 2003 to 2008
Authors: Lee Sangmi , Ward Todd J. , Graves Lewis M. , Tarr Cheryl L. , Siletzky Robin M. , Kathariou Sophia 
Published: April 2014

ABSTRACT

Listeria monocytogenes
can cause severe food-borne disease (listeriosis). Numerous outbreaks have involved three serotype 4b epidemic clones (ECs): ECI, ECII, and ECIa. However, little is known about the population structure of
L. monocytogenes
serotype 4b from sporadic listeriosis in the United States, even though most cases of human listeriosis are in fact sporadic. Here we analyzed 136 serotype 4b isolates from sporadic cases in the United States, 2003 to 2008, utilizing multiple tools including multilocus genotyping, pulsed-field gel electrophoresis, and sequence analysis of the
inlAB
locus. ECI, ECII, and ECIa were frequently encountered (32, 17, and 7%, respectively). However, annually 30 to 68% of isolates were outside these ECs, and several novel clonal groups were identified. An estimated 33 and 17% of the isolates, mostly among the ECs, were resistant to cadmium and arsenic, respectively, but resistance to benzalkonium chloride was uncommon (3%) among the sporadic isolates. The frequency of clonal groups fluctuated within the 6-year study period, without consistent trends. However, on several occasions, temporal clusters of isolates with indistinguishable genotypes were detected, suggesting the possibility of hidden multistate outbreaks. Our analysis suggests a complex population structure of serotype 4b
L. monocytogenes
from sporadic disease, with important contributions by ECs and several novel clonal groups. Continuous monitoring will be needed to assess long-term trends in clonality patterns and population structure of
L. monocytogenes
from sporadic listeriosis.
Insects Represent a Link between Food Animal Farms and the Urban Environment for Antibiotic Resistance Traits
Authors: Zurek Ludek , Ghosh Anuradha 
Published: April 2014

ABSTRACT
Antibiotic-resistant bacterial infections result in higher patient mortality rates, prolonged hospitalizations, and increased health care costs. Extensive use of antibiotics as growth promoters in the animal industry represents great pressure for evolution and selection of antibiotic-resistant bacteria on farms. Despite growing evidence showing that antibiotic use and bacterial resistance in food animals correlate with resistance in human pathogens, the proof for direct transmission of antibiotic resistance is difficult to provide. In this review, we make a case that insects commonly associated with food animals likely represent a direct and important link between animal farms and urban communities for antibiotic resistance traits. Houseflies and cockroaches have been shown to carry multidrug-resistant clonal lineages of bacteria identical to those found in animal manure. Furthermore, several studies have demonstrated proliferation of bacteria and horizontal transfer of resistance genes in the insect digestive tract as well as transmission of resistant bacteria by insects to new substrates. We propose that insect management should be an integral part of pre- and postharvest food safety strategies to minimize spread of zoonotic pathogens and antibiotic resistance traits from animal farms. Furthermore, the insect link between the agricultural and urban environment presents an additional argument for adopting prudent use of antibiotics in the food animal industry.
A Mesophilic, Autotrophic, Ammonia-Oxidizing Archaeon of Thaumarchaeal Group I.1a Cultivated from a Deep Oligotrophic Soil Horizon
Authors: Jung Man-Young , Park Soo-Je , Kim So-Jeong , Kim Jong-Geol , Sinninghe Damsté Jaap S. , Jeon Che Ok , Rhee Sung-Keun 
Published: April 2014

ABSTRACT

Soil nitrification plays an important role in the reduction of soil fertility and in nitrate enrichment of groundwater. Various ammonia-oxidizing archaea (AOA) are considered to be members of the pool of ammonia-oxidizing microorganisms in soil. This study reports the discovery of a chemolithoautotrophic ammonia oxidizer that belongs to a distinct clade of nonmarine thaumarchaeal group I.1a, which is widespread in terrestrial environments. The archaeal strain MY2 was cultivated from a deep oligotrophic soil horizon. The similarity of the 16S rRNA gene sequence of strain MY2 to those of other cultivated group I.1a thaumarchaeota members, i.e.,
Nitrosopumilus maritimus
and “
Candidatus
Nitrosoarchaeum koreensis,” is 92.9% for both species. Extensive growth assays showed that strain MY2 is chemolithoautotrophic, mesophilic (optimum temperature, 30°C), and neutrophilic (optimum pH, 7 to 7.5). The accumulation of nitrite above 1 mM inhibited ammonia oxidation, while ammonia oxidation itself was not inhibited in the presence of up to 5 mM ammonia. The genome size of strain MY2 was 1.76 Mb, similar to those of
N. maritimus
and “
Ca
. Nitrosoarchaeum koreensis,” and the repertoire of genes required for ammonia oxidation and carbon fixation in thaumarchaeal group I.1a was conserved. A high level of representation of conserved orthologous genes for signal transduction and motility in the noncore genome might be implicated in niche adaptation by strain MY2. On the basis of phenotypic, phylogenetic, and genomic characteristics, we propose the name “
Candidatus
Nitrosotenuis chungbukensis” for the ammonia-oxidizing archaeal strain MY2.
Environmental Transmission of Human Noroviruses in Shellfish Waters
Authors: Campos Carlos J. A. , Lees David N. 
Published: April 2014

ABSTRACTHuman noroviruses (NoV) are the most common cause of epidemic gastroenteritis following consumption of bivalve shellfish contaminated with fecal matter. NoV levels can be effectively reduced by some sewage treatment processes such as activated sludge and membrane bioreactors. However, tertiary sewage treatment and substantial sewage dilution are usually required to achieve low concentrations of virus in shellfish. Most outbreaks have been associated with shellfish harvested from waters affected by untreated sewage from, for example, storm overflows or overboard disposal of feces from boats. In coastal waters, NoV can remain in suspension or associate with organic and inorganic matter and be accumulated by shellfish. Shellfish take considerably longer to purge NoV than fecal indicator bacteria when transferred from sewage-polluted estuarine waters to uncontaminated waters. The abundance and distribution of NoV in shellfish waters are influenced by the levels of sewage treatment, proximity of shellfish beds to sewage sources, rainfall, river flows, salinity, and water temperature. Detailed site-specific information on these factors is required to design measures to control the viral risk.
Role of
norEF
in Denitrification, Elucidated by Physiological Experiments with Rhodobacter sphaeroides
Authors: Bergaust Linda L. , Hartsock Angela , Liu Binbin , Bakken Lars R. , Shapleigh James P. 
Published: April 2014

ABSTRACT

Many denitrifying organisms contain the
norEF
gene cluster, which codes for two proteins that are thought to be involved in denitrification because they are expressed during the reduction of nitrite and nitric oxide. The products of both genes are predicted to be membrane associated, and the
norE
product is a member of the cytochrome
c
oxidase subunit III family. However, the specific role of
norEF
is unknown. The denitrification phenotypes of
Rhodobacter sphaeroides
strains with and without
norEF
genes were studied, and it was found that loss of
norEF
lowered the rate of denitrification from nitrate and resulted in accumulation of micromolar concentrations of nitric oxide during denitrification from nitrite.
norEF
appears to have no direct role in the reduction of nitric oxide; however, since deletion of
norEF
in the wild-type 2.4.3 strain had essentially no influence on the kinetics of potential nitric oxide reduction (
V
max
and

K
s

), as measured by monitoring the depletion of a bolus of nitric oxide injected into anoxic cultures without any other electron acceptors. However,
norEF
-deficient cells that had undergone a more chronic exposure to micromolar concentrations of nitric oxide showed an ∼50% reduction in
V
max
but no change in apparent

K
s

. These results can explain the occurrence of
norEF
in the 2.4.3 strain of
R. sphaeroides
, which can reduce nitrate to nitrous oxide, and their absence from strains such as 2.4.1, which likely use nitric oxide reductase to mitigate stress due to episodic exposure to nitric oxide from exogenous sources.
Influence of Iron and Aeration on Staphylococcus aureus Growth, Metabolism, and Transcription
Authors: Ledala Nagender , Zhang Bo , Seravalli Javier , Powers Robert , Somerville Greg A. 
Published: April 2014

ABSTRACT

Staphylococcus aureus
is a prominent nosocomial pathogen and a major cause of biomaterial-associated infections. The success of
S. aureus
as a pathogen is due in part to its ability to adapt to stressful environments. As an example, the transition from residing in the nares to residing in the blood or deeper tissues is accompanied by changes in the availability of nutrients and elements such as oxygen and iron. As such, nutrients, oxygen, and iron are important determinants of virulence factor synthesis in
S. aureus
. In addition to influencing virulence factor synthesis, oxygen and iron are critical cofactors in enzymatic and electron transfer reactions; thus, a change in iron or oxygen availability alters the bacterial metabolome. Changes in metabolism create intracellular signals that alter the activity of metabolite-responsive regulators such as CodY, RpiRc, and CcpA. To assess the extent of metabolomic changes associated with oxygen and iron limitation,
S. aureus
cells were cultivated in iron-limited medium and/or with decreasing aeration, and the metabolomes were examined by nuclear magnetic resonance (NMR) spectroscopy. As expected, oxygen and iron limitation dramatically decreased tricarboxylic acid (TCA) cycle activity, creating a metabolic block and significantly altering the metabolome. These changes were most prominent during post-exponential-phase growth, when TCA cycle activity was maximal. Importantly, many of the effects of iron limitation were obscured by aeration limitation. Aeration limitation not only obscured the metabolic effects of iron limitation but also overrode the transcription of iron-regulated genes. Finally, in contrast to previous speculation, we confirmed that acidification of the culture medium occurs independent of the availability of iron.
Genetic Dissection of T4 Lysis
Authors: Moussa Samir H. , Lawler Jessica L. , Young Ry 
Published: April 2014

ABSTRACT

t
is the holin gene for coliphage T4, encoding a 218-amino-acid (aa) protein essential for the inner membrane hole formation that initiates lysis and terminates the phage infection cycle. T is predicted to be an integral membrane protein that adopts an N
in
-C
out
topology with a single transmembrane domain (TMD). This holin topology is different from those of the well-studied holins S105 (3 TMDs; N
out
-C
in
) of the coliphage lambda and S68 (2 TMDs; N
in
-C
in
) of the lambdoid phage 21. Here, we used random mutagenesis to construct a library of lysis-defective alleles of
t
to discern residues and domains important for holin function and for the inhibition of lysis by the T4 antiholin, RI. The results show that mutations in all 3 topological domains (N-terminal cytoplasmic, TMD, and C-terminal periplasmic) can abrogate holin function. Additionally, several lysis-defective alleles in the C-terminal domain are no longer competent in binding RI. Taken together, these results shed light on the roles of the previously uncharacterized N-terminal and C-terminal domains in lysis and its real-time regulation.
EscO, a Functional and Structural Analog of the Flagellar FliJ Protein, Is a Positive Regulator of EscN ATPase Activity of the Enteropathogenic Escherichia coli Injectisome
Authors: Romo-Castillo Mariana , Andrade Angel , Espinosa Norma , Monjarás Feria Julia , Soto Eduardo , Díaz-Guerrero Miguel , González-Pedrajo Bertha 
Published: April 2014

ABSTRACT

Type III secretion systems (T3SSs) are multiprotein molecular devices used by many Gram-negative bacterial pathogens to translocate effector proteins into eukaryotic cells. A T3SS is also used for protein export in flagellar assembly, which promotes bacterial motility. The two systems are evolutionarily related, possessing highly conserved components in their export apparatuses. Enteropathogenic
Escherichia coli
(EPEC) employs a T3SS, encoded by genes in the locus of enterocyte effacement (LEE) pathogenicity island, to colonize the human intestine and cause diarrheal disease. In the present work, we investigated the role of the LEE-encoded EscO protein (previously Orf15 or EscA) in T3SS biogenesis. We show that EscO shares similar properties with the flagellar FliJ and the
Yersinia
YscO protein families. Our findings demonstrate that EscO is essential for secretion of all categories of T3SS substrates. Consistent with its central role in protein secretion, it was found to interact with the ATPase EscN and its negative regulator, EscL, of the export apparatus. Moreover, we show that EscO stimulates EscN enzymatic activity; however, it is unable to upregulate ATP hydrolysis in the presence of EscL. Remarkably, EscO partially restored the swimming defect of a
Salmonella
flagellar
fliJ
mutant and was able to stimulate the ATPase activity of FliI. Overall, our data indicate that EscO is the virulence counterpart of the flagellar FliJ protein.
Analysis of Factors That Affect FlgM-Dependent Type III Secretion for Protein Purification with Salmonella enterica Serovar Typhimurium
Authors: Guo Shukui , Alshamy Israa , Hughes Kelly T. , Chevance Fabienne F. V. 
Published: April 2014

ABSTRACT

The FlgM protein is secreted in response to flagellar hook-basal body secretion and can be used as a secretion signal to direct selected protein secretion via the flagellar type III secretion (T3S) system [H. M. Singer, M. Erhardt, A. M. Steiner, M. M. Zhang, D. Yoshikami, G. Bulaj, B. M. Olivera, and K. T. Hughes, mBio 3(3):e00115-12, 2012,
http://dx.doi.org/10.1128/mBio.00115-12
]. Conditions known to affect flagellar gene expression, FlgM stability, and flagellar T3S were tested either alone or in combination to determine their effects on levels of secreted FlgM. These conditions included mutations that affect activity of the flagellar FlhD
4
C
2
master regulatory protein complex or the FlgM T3S chaperone σ
28
, the removal of
Salmonella p
athogenicity
i
sland 1 (Spi1), the removal of flagellar late secretion substrates that could compete with FlgM for secretion, and changes in the ionic strength of the growth medium. Conditions that enhanced FlgM secretion were combined in order to maximize levels of secreted FlgM. An optimized FlgM secretion strain was used to secrete and isolate otherwise difficult-to-produce proteins and peptides fused to the C terminus of FlgM. These include cysteine-rich, hydrophobic peptides (conotoxins δ-SVIE and MrVIA), nodule-specific, cysteine-rich antimicrobial peptides (NCR), and a malaria surface antigen domain of apical membrane antigen AMA-1.
FlgN Is Required for Flagellum-Based Motility by Bacillus subtilis
Authors: Cairns Lynne S. , Marlow Victoria L. , Kiley Taryn B. , Birchall Christopher , Ostrowski Adam , Aldridge Phillip D. , Stanley-Wall Nicola R. 
Published: April 2014

ABSTRACT

The assembly of the bacterial flagellum is exquisitely controlled. Flagellar biosynthesis is underpinned by a specialized type III secretion system that allows export of proteins from the cytoplasm to the nascent structure.
Bacillus subtilis
regulates flagellar assembly using both conserved and species-specific mechanisms. Here, we show that YvyG is essential for flagellar filament assembly. We define YvyG as an orthologue of the
Salmonella enterica
serovar Typhimurium type III secretion system chaperone, FlgN, which is required for the export of the hook-filament junction proteins, FlgK and FlgL. Deletion of
flgN
(
yvyG
) results in a nonmotile phenotype that is attributable to a decrease in
hag
translation and a complete lack of filament polymerization. Analyses indicate that a
flgK-flgL
double mutant strain phenocopies deletion of
flgN
and that overexpression of
flgK-flgL
cannot complement the motility defect of a Δ
flgN
strain. Furthermore, in contrast to previous work suggesting that phosphorylation of FlgN alters its subcellular localization, we show that mutation of the identified tyrosine and arginine FlgN phosphorylation sites has no effect on motility. These data emphasize that flagellar biosynthesis is differentially regulated in
B. subtilis
from classically studied Gram-negative flagellar systems and questions the biological relevance of some posttranslational modifications identified by global proteomic approaches.