bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autonomic, locomotor and cardiac abnormalities in a mouse model of muscular dystrophy: targeting the renin–angiotensin system
Authors: Sabharwal Rasna , Chapleau Mark W. 
Published: December 2013

New Findings
What is the topic of this review?
This symposium report summarizes autonomic, cardiac and skeletal muscle abnormalities in sarcoglycan‐δ‐deficient mice (Sgcd−/−), a mouse model of limb girdle muscular dystrophy, with emphasis on the roles of autonomic dysregulation and activation of the renin–angiotensin system at a young age.
What advances does it highlight?
The contributions of the autonomic nervous system and the renin–angiotensin system to the pathogenesis of muscular dystrophy are highlighted. Results demonstrate that autonomic dysregulation precedes and predicts later development of cardiac dysfunction in Sgcd−/− mice and that treatment of young Sgcd−/− mice with the angiotensin type 1 receptor antagonist losartan or with angiotensin‐(1–7) abrogates the autonomic dysregulation, attenuates skeletal muscle pathology and increases spontaneous locomotor activity.
Muscular dystrophies are a heterogeneous group of genetic muscle diseases characterized by muscle weakness and atrophy. Mutations in sarcoglycans and other subunits of the dystrophin–glycoprotein complex cause muscular dystrophy and dilated cardiomyopathy in animals and humans. Aberrant autonomic signalling is recognized in a variety of neuromuscular disorders. We hypothesized that activation of the renin–angiotensin system contributes to skeletal muscle and autonomic dysfunction in mice deficient in the sarcoglycan‐δ (Sgcd) gene at a young age and that this early autonomic dysfunction contributes to the later development of left ventricular (LV) dysfunction and increased mortality. We demonstrated that young Sgcd−/− mice exhibit histopathological features of skeletal muscle dystrophy, decreased locomotor activity and severe autonomic dysregulation, but normal LV function. Autonomic regulation continued to deteriorate in Sgcd−/− mice with age and was accompanied by LV dysfunction and dilated cardiomyopathy at older ages. Autonomic dysregulation at a young age predicted later development of LV dysfunction and higher mortality in Sgcd−/− mice. Treatment of Sgcd−/− mice with the angiotensin type 1 receptor blocker losartan for 8–9 weeks, beginning at 3 weeks of age, decreased fibrosis and oxidative stress in skeletal muscle, increased locomotor activity and prevented autonomic dysfunction. Chronic infusion of the counter‐regulatory peptide angiotensin‐(1–7) resulted in similar protection. We conclude that activation of the renin–angiotensin system, at a young age, contributes to skeletal muscle and autonomic dysfunction in muscular dystrophy. We speculate that the latter is mediated via abnormal sensory nerve and/or cytokine signalling from dystrophic skeletal muscle to the brain and contributes to age‐related LV dysfunction, dilated cardiomyopathy, arrhythmias and premature death. Therefore, correcting the early autonomic dysregulation and renin–angiotensin system activation may provide a novel therapeutic approach in muscular dystrophy.
Elevated levels of branched‐chain amino acids have little effect on pancreatic islet cells, but l‐arginine impairs function through activation of the endoplasmic reticulum stress response
Authors: Mullooly Niamh , Vernon Wendy , Smith David M. , Newsholme Philip 
Published: December 2013

New Findings
What is the central question of this study?
Recent studies have demonstrated strong correlations between circulating branched‐chain amino acid (AA) levels and insulin resistance, a predictor of susceptibility to type 2 diabetes. This study investigated how elevations in various AA concentrations over a chronic incubation period affect rat pancreatic islet cell viability and insulin secretion.
What is the main finding and its importance?
We report that chronic exposure to specific AAs provoked islet cell toxic effects, particularly the insulinotropic AA l‐arginine. Dose‐dependent decreases in insulin secretion and cell proliferation were observed in addition to activation of the cell endoplasmic reticulum stress response. These results show, for the first time, that elevated l‐arginine levels may impact negatively on islet function, providing further insights into β‐cell dysfunction in type 2 diabetes.
Recent metabolic profiling studies have identified a correlation between branched‐chain amino acid levels, insulin resistance associated with prediabetes and susceptibility to type 2 diabetes. Glucose and lipids in chronic excess have been reported to induce toxic effects in pancreatic β‐cells, but the effect of elevated amino acid concentrations on primary islet cell function has not been investigated to date. The aim of this study was to investigate the effect of chronic exposure to various amino acids on islet cell function in vitro. Isolated rat islets were incubated over periods of 48 h with a range of concentrations of individual amino acids (0.1 μm to 10 mm). After 48 h, islets were assessed for glucose‐dependent insulin secretion capacity, proliferation or islet cell apoptosis. We report that elevated levels of branched‐chain amino acids have little effect on pancreatic islet cell function or viability; however, increased levels of the amino acid l‐arginine were found to be β‐cell toxic, causing a dose‐dependent decrease in insulin secretion accompanied by a decrease in islet cell proliferation and an increase in islet cell apoptosis. These effects were not due to l‐arginine‐dependent increases in production of nitric oxide but arose through elicitation of the islet cell endoplasmic reticulum stress response. This novel finding indicates, for the first time, that the l‐arginine concentration in vitro may impact negatively on islet cell function, thus indicating further complexity in relationship to in vivo susceptibility of β‐cells to nutrient‐induced dysfunction.
Association of Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) Elements with Specific Serotypes and Virulence Potential of Shiga Toxin-Producing Escherichia coli
Authors: Toro Magaly , Cao Guojie , Ju Wenting , Allard Marc , Barrangou Rodolphe , Zhao Shaohua , Brown Eric , Meng Jianghong 
Published: December 2013

ABSTRACT

Shiga toxin-producing
Escherichia coli
(STEC) strains (
n
= 194) representing 43 serotypes and
E. coli
K-12 were examined for clustered regularly interspaced short palindromic repeat (CRISPR) arrays to study genetic relatedness among STEC serotypes. A subset of the strains (
n
= 81) was further analyzed for subtype I-E
cas
and virulence genes to determine a possible association of CRISPR elements with potential virulence. Four types of CRISPR arrays were identified. CRISPR1 and CRISPR2 were present in all strains tested; 1 strain also had both CRISPR3 and CRISPR4, whereas 193 strains displayed a short, combined array, CRISPR3-4. A total of 3,353 spacers were identified, representing 528 distinct spacers. The average length of a spacer was 32 bp. Approximately one-half of the spacers (54%) were unique and found mostly in strains of less common serotypes. Overall, CRISPR spacer contents correlated well with STEC serotypes, and identical arrays were shared between strains with the same H type (O26:H11, O103:H11, and O111:H11). There was no association identified between the presence of subtype I-E
cas
and virulence genes, but the total number of spacers had a negative correlation with potential pathogenicity (
P
< 0.05). Fewer spacers were found in strains that had a greater probability of causing outbreaks and disease than in those with lower virulence potential (
P
< 0.05). The relationship between the CRISPR-
cas
system and potential virulence needs to be determined on a broader scale, and the biological link will need to be established.
The Presence of Conjugative Plasmid pLS20 Affects Global Transcription of Its Bacillus subtilis Host and Confers Beneficial Stress Resistance to Cells
Authors: Rösch Thomas C. , Golman Wladislaw , Hucklesby Laura , Gonzalez-Pastor Jose E. , Graumann Peter L. 
Published: December 2013

ABSTRACT

Conjugation activity of plasmid pLS20 from
Bacillus subtilis
subsp.
natto
is induced when cells are diluted into fresh medium and diminishes as cells enter into stationary-phase growth. Transcriptional profiling shows that during mid-exponential growth, more than 5% of the host genes are affected in the presence of the plasmid, in contrast to the minor changes seen in freshly diluted and stationary-phase cells. Changes occurred in many metabolic pathways, although pLS20 does not confer any detectable burden on its host cell, as well as in membrane and cell wall-associated processes, in the large motility operon, and in several other cellular processes. In agreement with these changes, we found considerable alterations in motility and enzyme activity and increased resistance against several different forms of stress in cells containing the plasmid, revealing that the presence of pLS20 has a broad impact on the physiology of its host cell and increases its stress resistance in multiple aspects. Additionally, we found that the lack of chromosomal gene
yueB
, known to encode a phage receptor protein, which is upregulated in cells containing pLS20, strongly reduced conjugation efficiency, revealing that pLS20 not only increases fitness of its host but also employs host proteins for efficient transfer into a new cell.
Ubiquity of Insect-Derived Nitrogen Transfer to Plants by Endophytic Insect-Pathogenic Fungi: an Additional Branch of the Soil Nitrogen Cycle
Authors: Behie Scott W. , Bidochka Michael J. 
Published: December 2013

ABSTRACT

The study of symbiotic nitrogen transfer in soil has largely focused on nitrogen-fixing bacteria. Vascular plants can lose a substantial amount of their nitrogen through insect herbivory. Previously, we showed that plants were able to reacquire nitrogen from insects through a partnership with the endophytic, insect-pathogenic fungus
Metarhizium robertsii
. That is, the endophytic capability and insect pathogenicity of
M. robertsii
are coupled so that the fungus acts as a conduit to provide insect-derived nitrogen to plant hosts. Here, we assess the ubiquity of this nitrogen transfer in five
Metarhizium
species representing those with broad (
M. robertsii
,
M. brunneum
, and
M. guizhouense
) and narrower insect host ranges (
M. acridum
and
M. flavoviride
), as well as the insect-pathogenic fungi
Beauveria bassiana
and
Lecanicillium lecanii
. Insects were injected with
15
N-labeled nitrogen, and we tracked the incorporation of
15
N into two dicots, haricot bean (
Phaseolus vulgaris
) and soybean (
Glycine max
), and two monocots, switchgrass (
Panicum virgatum
) and wheat (
Triticum aestivum
), in the presence of these fungi in soil microcosms. All
Metarhizium
species and
B. bassiana
but not
L. lecanii
showed the capacity to transfer nitrogen to plants, although to various degrees. Endophytic association by these fungi increased overall plant productivity. We also showed that in the field, where microbial competition is potentially high,
M. robertsii
was able to transfer insect-derived nitrogen to plants.
Metarhizium
spp. and
B. bassiana
have a worldwide distribution with high soil abundance and may play an important role in the ecological cycling of insect nitrogen back to plant communities.
Survival and Transmission of Potato Virus Y, Pepino Mosaic Virus, and Potato Spindle Tuber Viroid in Water
Authors: Mehle N. , Gutiérrez-Aguirre I. , Prezelj N. , Delić D. , Vidic U. , Ravnikar M. 
Published: December 2013

ABSTRACT
Hydroponic systems and intensive irrigation are used widely in horticulture and thus have the potential for rapid spread of water-transmissible plant pathogens. Numerous plant viruses have been reported to occur in aqueous environments, although information on their survival and transmission is minimal, due mainly to the lack of effective detection methods and to the complexity of the required transmission experiments. We have assessed the role of water as a source of plant infection using three mechanically transmissible plant pathogens that constitute a serious threat to tomato and potato production: pepino mosaic virus (PepMV), potato virus Y (PVY), and potato spindle tuber viroid (PSTVd). PepMV remains infectious in water at 20 ± 4°C for up to 3 weeks, PVY (NTN strain) for up to 1 week, and PSTVd for up to 7 weeks. Experiments using a hydroponic system show that PepMV (Ch2 genotype) and PVY (NTN strain) can be released from plant roots into the nutrient solution and can infect healthy plants through their roots, ultimately spreading to the green parts, where they can be detected after a few months. In addition, tubers developed on plants grown in substrate watered with PSTVd-infested water were confirmed to be the source of viroid infection. Our data indicate that although well-known pathways of virus spread are more rapid than water-mediated infection, like insect or mechanical transmission through leaves, water is a route that provides a significant bridge for rapid virus/viroid spread. Consequently, water should be taken into account in future epidemiology and risk assessment studies.
Analysis of the Transcriptional Regulator GlpR, Promoter Elements, and Posttranscriptional Processing Involved in Fructose-Induced Activation of the Phosphoenolpyruvate-Dependent Sugar Phosphotransferase System in Haloferax mediterranei
Authors: Cai Lei , Cai Shuangfeng , Zhao Dahe , Wu Jinhua , Wang Lei , Liu Xiaoqing , Li Ming , Hou Jing , Zhou Jian , Liu Jingfang , Han Jing , Xiang Hua 
Published: December 2013

ABSTRACT

Among all known archaeal strains, the phosphoenolpyruvate-dependent phosphotransferase system (PTS) for fructose utilization is used primarily by haloarchaea, which thrive in hypersaline environments, whereas the molecular details of the regulation of the archaeal PTS under fructose induction remain unclear. In this study, we present a comprehensive examination of the regulatory mechanism of the fructose PTS in the haloarchaeon
Haloferax mediterranei
. With gene knockout and complementation, microarray analysis, and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR), we revealed that GlpR is the indispensable activator, which specifically binds to the PTS promoter (P

PTS

) during fructose induction. Further promoter-scanning mutation indicated that three sites located upstream of the
H. mediterranei
P

PTS

, which are conserved in most haloarchaeal P

PTS

s, are involved in this induction. Interestingly, two PTS transcripts (named T
8
and T
17
) with different lengths of 5′ untranslated region (UTR) were observed, and promoter or 5′ UTR swap experiments indicated that the shorter 5′ UTR was most likely generated from the longer one. Notably, the translation efficiency of the transcript with this shorter 5′ UTR was significantly higher and the ratio of T
8
(with the shorter 5′ UTR) to T
17
increased during fructose induction, implying that a posttranscriptional mechanism is also involved in PTS activation. With these insights into the molecular regulation of the haloarchaeal PTS, we have proposed a working model for haloarchaea in response to environmental fructose.
Cross-Institute Evaluations of Inhibitor-Resistant PCR Reagents for Direct Testing of Aerosol and Blood Samples Containing Biological Warfare Agent DNA
Authors: Minogue Timothy D. , Rachwal Phillip A. , Trombley Hall Adrienne , Koehler Jeffery W. , Weller Simon A. 
Published: December 2013

ABSTRACT

Rapid pathogen detection is crucial for the timely introduction of therapeutics. Two groups (one in the United Kingdom and one in the United States) independently evaluated inhibitor-resistant PCR reagents for the direct testing of substrates. In the United Kingdom, a multiplexed
Bacillus anthracis
(target) and
Bacillus subtilis
(internal-control) PCR was used to evaluate 4 reagents against 5 PCR inhibitors and down-selected the TaqMan Fast Virus 1-Step master mix (Life Technologies Inc.). In the United States, four real-time PCR assays (targeting
B. anthracis
,
Brucella melitensis
, Venezuelan equine encephalitis virus [VEEV], and
Orthopoxvirus
spp.) were used to evaluate 5 reagents (plus the Fast Virus master mix) against buffer, blood, and soil samples and down-selected the KAPA Blood Direct master mix (KAPA Biosystems Inc.) with added Platinum
Taq
(Life Technologies). The down-selected reagents underwent further testing. In the United Kingdom experiments, both reagents were tested against seven contrived aerosol collector samples containing
B. anthracis
Ames DNA and
B. subtilis
spores from a commercial formulation (BioBall). In PCR assays with reaction mixtures containing 40% crude sample, an airfield-collected sample induced inhibition of the
B. subtilis
PCR with the KAPA reagent and complete failure of both PCRs with the Fast Virus reagent. However, both reagents allowed successful PCR for all other samples—which inhibited PCRs with a non-inhibitor-resistant reagent. In the United States, a cross-assay limit-of-detection (LoD) study in blood was conducted. The KAPA Blood Direct reagent allowed the detection of agent DNA (by four PCRs) at higher concentrations of blood in the reaction mixture (2.5%) than the Fast Virus reagent (0.5%), although LoDs differed between assays and reagent combinations. Across both groups, the KAPA Blood Direct reagent was determined to be the optimal reagent for inhibition relief in PCR.
Functional Analysis of Environmental DNA-Derived Microviridins Provides New Insights into the Diversity of the Tricyclic Peptide Family
Authors: Gatte-Picchi Douglas , Weiz Annika , Ishida Keishi , Hertweck Christian , Dittmann Elke 
Published: December 2013

ABSTRACT

Microviridins represent a unique family of ribosomally synthesized cage-like depsipeptides from cyanobacteria with potent protease-inhibitory activities. The natural diversity of these peptides is largely unexplored. Here, we describe two methodologies that were developed to functionally characterize cryptic microviridin gene clusters from metagenomic DNA. Environmental samples were collected and enriched from cyanobacterial freshwater blooms of different geographical origins containing predominantly
Microcystis
sp. Microviridins were produced either directly from fosmid clones or after insertion of environmental DNA-derived gene cassettes into a minimal expression platform in
Escherichia coli
. Three novel microviridin variants were isolated and tested against different serine-type proteases. The comparison of the bioactivity profiles of the new congeners allows deduction of further structure-function relationships for microviridins. Moreover, this study provides new insights into microviridin processing and gene cluster organization.
Regio- and Stereospecific Hydroxylation of Various Steroids at the 16α Position of the D Ring by the Streptomyces griseus Cytochrome P450 CYP154C3
Authors: Makino Takuya , Katsuyama Yohei , Otomatsu Toshihiko , Misawa Norihiko , Ohnishi Yasuo 
Published: December 2013

ABSTRACT

Cytochrome P450 monooxygenases (P450s), which constitute a superfamily of heme-containing proteins, catalyze the direct oxidation of a variety of compounds in a regio- and stereospecific manner; therefore, they are promising catalysts for use in the oxyfunctionalization of chemicals. In the course of our comprehensive substrate screening for all 27 putative P450s encoded by the
Streptomyces griseus
genome, we found that
Escherichia coli
cells producing an
S. griseus
P450 (CYP154C3), which was fused C terminally with the P450 reductase domain (RED) of a self-sufficient P450 from
Rhodococcus
sp., could transform various steroids (testosterone, progesterone, Δ
4
-androstene-3,17-dione, adrenosterone, 1,4-androstadiene-3,17-dione, dehydroepiandrosterone, 4-pregnane-3,11,20-trione, and deoxycorticosterone) into their 16α-hydroxy derivatives as determined by nuclear magnetic resonance and high-resolution mass spectrometry analyses. The purified CYP154C3, which was not fused with RED, also catalyzed the regio- and stereospecific hydroxylation of these steroids at the same position with the aid of ferredoxin and ferredoxin reductase from spinach. The apparent equilibrium dissociation constant (

K
d

) values of the binding between CYP154C3 and these steroids were less than 8 μM as determined by the heme spectral change, indicating that CYP154C3 strongly binds to these steroids. Furthermore, kinetic parameters of the CYP154C3-catalyzed hydroxylation of Δ
4
-androstene-3,17-dione were determined (

K
m

, 31.9 ± 9.1 μM;
k
cat
, 181 ± 4.5 s
−1
). We concluded that CYP154C3 is a steroid D-ring 16α-specific hydroxylase which has considerable potential for industrial applications. This is the first detailed enzymatic characterization of a P450 enzyme that has a steroid D-ring 16α-specific hydroxylation activity.
Deregulation of Feedback Inhibition of Phosphoenolpyruvate Carboxylase for Improved Lysine Production in Corynebacterium glutamicum
Authors: Chen Zhen , Bommareddy Rajesh Reddy , Frank Doinita , Rappert Sugima , Zeng An-Ping 
Published: December 2013

ABSTRACT

Allosteric regulation of phosphoenolpyruvate carboxylase (PEPC) controls the metabolic flux distribution of anaplerotic pathways. In this study, the feedback inhibition of
Corynebacterium glutamicum
PEPC was rationally deregulated, and its effect on metabolic flux redistribution was evaluated. Based on rational protein design, six PEPC mutants were designed, and all of them showed significantly reduced sensitivity toward aspartate and malate inhibition. Introducing one of the point mutations (N917G) into the
ppc
gene, encoding PEPC of the lysine-producing strain
C. glutamicum
LC298, resulted in ∼37% improved lysine production.
In vitro
enzyme assays and
13
C-based metabolic flux analysis showed ca. 20 and 30% increases in the PEPC activity and corresponding flux, respectively, in the mutant strain. Higher demand for NADPH in the mutant strain increased the flux toward pentose phosphate pathway, which increased the supply of NADPH for enhanced lysine production. The present study highlights the importance of allosteric regulation on the flux control of central metabolism. The strategy described here can also be implemented to improve other oxaloacetate-derived products.
Discovery of Novel Rickettsiella spp. in Ixodid Ticks from Western Canada
Authors: Anstead Clare A. , Chilton Neil B. 
Published: December 2013

ABSTRACT

The genomic DNA from four species of ixodid ticks in western Canada was tested for the presence of
Rickettsiella
by PCR analyses targeting the 16S rRNA gene. Eighty-eight percent of the
Ixodes angustus
(
n
= 270), 43% of the
I. sculptus
(
n
= 61), and 4% of the
I. kingi
(
n
= 93) individuals examined were PCR positive for
Rickettsiella
, whereas there was no evidence for the presence of
Rickettsiella
in
Dermacentor andersoni
(
n
= 45). Three different single-strand conformation polymorphism profiles of the 16S rRNA gene were detected among amplicons derived from
Rickettsiella
-positive ticks, each corresponding to a different sequence type. Furthermore, each sequence type was associated with a different tick species. Phylogenetic analyses of sequence data of the 16S rRNA gene and three other genes (
rpsA
,
gidA
, and
sucB
) revealed that all three sequence types were placed in a clade that contained species and pathotypes of the genus
Rickettsiella
. The bacterium in
I. kingi
represented the sister taxon to the
Rickettsiella
in
I. sculptus
, and both formed a clade with
Rickettsiella
grylli
from crickets (
Gryllus bimaculatus
) and “
R. ixodidis
” from
I. woodi
. In contrast, the
Rickettsiella
in
I. angustus
was not a member of this clade but was placed external to the clade comprising the pathotypes of
R. popilliae
. The results indicate the existence of at least two new species of
Rickettsiella
: one in
I. angustus
and another in
I. kingi
and
I. sculptus
. However, the
Rickettsiella
strains in
I. kingi
and
I. sculptus
may also represent different species because each had unique sequences for all four genes.