bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physiological and pathophysiological reactive oxygen species as probed by EPR spectroscopy: the underutilized research window on muscle ageing
Authors: A. Abdel‐Rahman Engy , Mahmoud Ali M. , Khalifa Abdulrahman M. , Ali Sameh S. 
Published: January 2016

AbstractReactive oxygen and nitrogen species (ROS and RNS) play crucial roles in triggering, mediating and regulating physiological and pathophysiological signal transduction pathways within the cell. Within the cell, ROS efflux is firmly controlled both spatially and temporally, making the study of ROS dynamics a challenging task. Different approaches have been developed for ROS assessment; however, many of these assays are not capable of direct identification or determination of subcellular localization of different ROS. Here we highlight electron paramagnetic resonance (EPR) spectroscopy as a powerful technique that is uniquely capable of addressing questions on ROS dynamics in different biological specimens and cellular compartments. Due to their critical importance in muscle functions and dysfunction, we discuss in some detail spin trapping of various ROS and focus on EPR detection of nitric oxide before highlighting how EPR can be utilized to probe biophysical characteristics of the environment surrounding a given stable radical. Despite the demonstrated ability of EPR spectroscopy to provide unique information on the identity, quantity, dynamics and environment of radical species, its applications in the field of muscle physiology, fatiguing and ageing are disproportionately infrequent. While reviewing the limited examples of successful EPR applications in muscle biology we conclude that the field would greatly benefit from more studies exploring ROS sources and kinetics by spin trapping, protein dynamics by site‐directed spin labelling, and membrane dynamics and global redox changes by spin probing EPR approaches.image
The effect of age and unilateral leg immobilization for 2 weeks on substrate utilization during moderate‐intensity exercise in human skeletal muscle
Authors: Vigelsø A. , Gram M. , Dybboe R. , Kuhlman A. B. , Prats C. , Greenhaff P. L. , Constantin‐Teodosiu D. , Birk J. B. , Wojtaszewski J. F. P. , Dela F. , Helge J. W. 
Published: January 2016

Key points
This study aimed to provide molecular insight into the differential effects of age and physical inactivity on the regulation of substrate metabolism during moderate‐intensity exercise.
Using the arteriovenous balance technique, we studied the effect of immobilization of one leg for 2 weeks on leg substrate utilization in young and older men during two‐legged dynamic knee‐extensor moderate‐intensity exercise, as well as changes in key proteins in muscle metabolism before and after exercise.
Age and immobilization did not affect relative carbohydrate and fat utilization during exercise, but the older men had higher uptake of exogenous fatty acids, whereas the young men relied more on endogenous fatty acids during exercise.
Using a combined whole‐leg and molecular approach, we provide evidence that both age and physical inactivity result in intramuscular lipid accumulation, but this occurs only in part through the same mechanisms.
AbstractAge and inactivity have been associated with intramuscular triglyceride (IMTG) accumulation. Here, we attempt to disentangle these factors by studying the effect of 2 weeks of unilateral leg immobilization on substrate utilization across the legs during moderate‐intensity exercise in young (n = 17; 23 ± 1 years old) and older men (n = 15; 68 ± 1 years old), while the contralateral leg served as the control. After immobilization, the participants performed two‐legged isolated knee‐extensor exercise at 20 ± 1 W (∼50% maximal work capacity) for 45 min with catheters inserted in the brachial artery and both femoral veins. Biopsy samples obtained from vastus lateralis muscles of both legs before and after exercise were used for analysis of substrates, protein content and enzyme activities. During exercise, leg substrate utilization (respiratory quotient) did not differ between groups or legs. Leg fatty acid uptake was greater in older than in young men, and although young men demonstrated net leg glycerol release during exercise, older men showed net glycerol uptake. At baseline, IMTG, muscle pyruvate dehydrogenase complex activity and the protein content of adipose triglyceride lipase, acetyl‐CoA carboxylase 2 and AMP‐activated protein kinase (AMPK)γ3 were higher in young than in older men. Furthermore, adipose triglyceride lipase, plasma membrane‐associated fatty acid binding protein and AMPKγ3 subunit protein contents were lower and IMTG was higher in the immobilized than the contralateral leg in young and older men. Thus, immobilization and age did not affect substrate choice (respiratory quotient) during moderate exercise, but the whole‐leg and molecular differences in fatty acid mobilization could explain the age‐ and immobilization‐induced IMTG accumulation.
Influence of exercise intensity and duration on functional and biochemical perturbations in the human heart
Authors: Stewart Glenn M. , Yamada Akira , Haseler Luke J. , Kavanagh Justin J. , Chan Jonathan , Koerbin Gus , Wood Cameron , Sabapathy Surendran 
Published: January 2016

Key points
Strenuous endurance exercise induces transient functional and biochemical cardiac perturbations that persist for 24–48 h.
The magnitude and time‐course of exercise‐induced reductions in ventricular function and increases in cardiac injury markers are influenced by the intensity and duration of exercise.
In a human experimental model, exercise‐induced reductions in ventricular strain and increases in cardiac troponin are greater, and persist for longer, when exercise is performed within the heavy‐ compared to moderate‐intensity exercise domain, despite matching for total mechanical work.
The results of the present study help us better understand the dose–response relationship between endurance exercise and acute cardiac stress/injury, a finding that has implications for the prescription of day‐to‐day endurance exercise regimes.
AbstractStrenuous endurance exercise induces transient cardiac perturbations with ambiguous health outcomes. The present study investigated the magnitude and time‐course of exercise‐induced functional and biochemical cardiac perturbations by manipulating the exercise intensity–duration matrix. Echocardiograph‐derived left (LV) and right (RV) ventricular global longitudinal strain (GLS), and serum high‐sensitivity cardiac troponin (hs‐cTnI) concentration, were examined in 10 males (age: 27 ± 4 years; : 4.0 ± 0.8 l min−1) before, throughout (50%, 75% and 100%), and during recovery (1, 3, 6 and 24 h) from two exercise trials. The two exercise trials consisted of 90 and 120 min of heavy‐ and moderate‐intensity cycling, respectively, with total mechanical work matched. LVGLS decreased (P < 0.01) during the 90 min trial only, with reductions peaking at 1 h post (pre: −19.9 ± 0.6%; 1 h post: −18.5 ± 0.7%) and persisting for >24 h into recovery. RVGLS decreased (P < 0.05) during both exercise trials with reductions in the 90 min trial peaking at 1 h post (pre: −27.5 ± 0.7%; 1 h post: −25.1 ± 0.8%) and persisting for >24 h into recovery. Serum hs‐cTnI increased (P < 0.01) during both exercise trials, with concentrations peaking at 3 h post but only exceeding cardio‐healthy reference limits (14 ng l−1) in the 90 min trial (pre: 4.2 ± 2.4 ng l−1; 3 h post: 25.1 ± 7.9 ng l−1). Exercise‐induced reductions in ventricular strain and increases in cardiac injury markers persist for 24 h following exercise that is typical of day‐to‐day endurance exercise training; however, the magnitude and time‐course of this response can be altered by manipulating the intensity–duration matrix.
Evidence of Apis cerana
Sacbrood virus
Infection in Apis mellifera
Authors: Gong Hong-Ri , Chen Xiu-Xian , Chen Yan Ping , Hu Fu-Liang , Zhang Jiang-Lin , Lin Zhe-Guang , Yu Ji-Wei , Zheng Huo-Qing 
Published: January 2016

ABSTRACT

Sacbrood virus
(SBV) is one of the most destructive viruses in the Asian honeybee
Apis cerana
but is much less destructive in
Apis mellifera
. In previous studies, SBV isolates infecting
A. cerana
(AcSBV) and SBV isolates infecting
A. mellifera
(AmSBV) were identified as different serotypes, suggesting a species barrier in SBV infection. In order to investigate this species isolation, we examined the presence of SBV infection in 318
A. mellifera
colonies and 64
A. cerana
colonies, and we identified the genotypes of SBV isolates. We also performed artificial infection experiments under both laboratory and field conditions. The results showed that 38
A. mellifera
colonies and 37
A. cerana
colonies were positive for SBV infection. Phylogenetic analysis based on RNA-dependent RNA polymerase (RdRp) gene sequences indicated that
A. cerana
isolates and most
A. mellifera
isolates formed two distinct clades but two strains isolated from
A. mellifera
were clustered with the
A. cerana
isolates. In the artificial-infection experiments, AcSBV negative-strand RNA could be detected in both adult bees and larvae of
A. mellifera
, although there were no obvious signs of the disease, demonstrating the replication of AcSBV in
A. mellifera
. Our results suggest that AcSBV is able to infect
A. mellifera
colonies with low prevalence (0.63% in this study) and pathogenicity. This work will help explain the different susceptibilities of
A. cerana
and
A. mellifera
to sacbrood disease and is potentially useful for guiding beekeeping practices.
Airborne Microalgae: Insights, Opportunities, and Challenges
Authors: Tesson Sylvie V. M. , Skjøth Carsten Ambelas , Šantl-Temkiv Tina , Löndahl Jakob 
Published: January 2016

ABSTRACTAirborne dispersal of microalgae has largely been a blind spot in environmental biological studies because of their low concentration in the atmosphere and the technical limitations in investigating microalgae from air samples. Recent studies show that airborne microalgae can survive air transportation and interact with the environment, possibly influencing their deposition rates. This minireview presents a summary of these studies and traces the possible route, step by step, from established ecosystems to new habitats through air transportation over a variety of geographic scales. Emission, transportation, deposition, and adaptation to atmospheric stress are discussed, as well as the consequences of their dispersal on health and the environment and state-of-the-art techniques to detect and model airborne microalga dispersal. More-detailed studies on the microalga atmospheric cycle, including, for instance, ice nucleation activity and transport simulations, are crucial for improving our understanding of microalga ecology, identifying microalga interactions with the environment, and preventing unwanted contamination events or invasions.
Evaluation of the Efficacy of Methyl Bromide in the Decontamination of Building and Interior Materials Contaminated with Bacillus anthracis Spores
Authors: Wood Joseph P. , Wendling Morgan , Richter William , Lastivka Andrew , Mickelsen Leroy 
Published: January 2016

ABSTRACT

The primary goal of this study was to determine the conditions required for the effective inactivation of
Bacillus anthracis
spores on materials by using methyl bromide (MeBr) gas. Another objective was to obtain comparative decontamination efficacy data with three avirulent microorganisms to assess their potential for use as surrogates for
B. anthracis
Ames. Decontamination tests were conducted with spores of
B. anthracis
Ames and
Geobacillus stearothermophilus
,
B. anthracis
NNR1Δ1, and
B. anthracis
Sterne inoculated onto six different materials. Experimental variables included temperature, relative humidity (RH), MeBr concentration, and contact time. MeBr was found to be an effective decontaminant under a number of conditions. This study highlights the important role that RH has when fumigation is performed with MeBr. There were no tests in which a ≥6-log
10
reduction (LR) of
B. anthracis
Ames was achieved on all materials when fumigation was done at 45% RH. At 75% RH, an increase in the temperature, the MeBr concentration, or contact time generally improved the efficacy of fumigation with MeBr. This study provides new information for the effective use of MeBr at temperatures and RH levels lower than those that have been recommended previously. The study also provides data to assist with the selection of an avirulent surrogate for
B. anthracis
Ames spores when additional tests with MeBr are conducted.
Comparative Transcriptome Analysis of Vibrio splendidus JZ6 Reveals the Mechanism of Its Pathogenicity at Low Temperatures
Authors: Liu Rui , Chen Hao , Zhang Ran , Zhou Zhi , Hou Zhanhui , Gao Dahai , Zhang Huan , Wang Lingling , Song Linsheng 
Published: January 2016

ABSTRACT

Yesso scallop-pathogenic
Vibrio splendidus
strain JZ6 was found to have the highest virulence at 10°C, while its pathogenicity was significantly reduced with increased temperature and completely incapacitated at 28°C. In the present study, comparative transcriptome analyses of JZ6 and another nonpathogenic
V. splendidus
strain, TZ19, were conducted at two crucial culture temperatures (10°C and 28°C) in order to determine the possible mechanism of temperature regulation of virulence. Comparisons among four libraries, constructed from JZ6 and TZ19 cultured at 10°C and 28°C (designated JZ6_10, JZ6_28, TZ19_10, and TZ19_28), revealed that 241 genes were possibly related to the increased virulence of JZ6 at 10°C. There were 10 genes, including 2 encoding Flp pilus assembly proteins (FlhG and VS_2437), 6 encoding proteins of the “
Vibrio cholerae
pathogenic cycle” (ToxS, CqsA, CqsS, RpoS, HapR, and Vsm), and 2 encoding proteins in the Sec-dependent pathway (SecE and FtsY), that were significantly upregulated in JZ6_10 (
P
< 0.05) compared to those in JZ6_28, TZ19_10, and TZ19_28, which were supposed to be responsible for adhesion, quorum sensing, virulence, and protein secretion of
V. splendidus
. When cultured at 10°C, JZ6 cells were larger and tended to aggregate more than those cultured at 28°C. The virulence factor (extracellular metalloprotease) was also found to be highly expressed in the extracellular product (ECP) of JZ6 at 10°C, and this ECP exhibited obvious cytotoxicity to oyster primary hemocytes, A549 cells, and L929 cells. These results indicated that low temperatures (10°C) could enhance adhesion, activate the quorum sensing systems, upregulate virulence factor synthesis and secretion, and, lastly, increase the pathogenicity of JZ6.
P212A Mutant of Dihydrodaidzein Reductase Enhances (
S
)-Equol Production and Enantioselectivity in a Recombinant Escherichia coli Whole-Cell Reaction System
Authors: Lee Pyung-Gang , Kim Joonwon , Kim Eun-Jung , Jung EunOk , Pandey Bishnu Prasad , Kim Byung-Gee 
Published: January 2016

ABSTRACT

(
S
)-Equol, a gut bacterial isoflavone derivative, has drawn great attention because of its potent use for relieving female postmenopausal symptoms and preventing prostate cancer. Previous studies have reported on the dietary isoflavone metabolism of several human gut bacteria and the involved enzymes for conversion of daidzein to (
S
)-equol. However, the anaerobic growth conditions required by the gut bacteria and the low productivity and yield of (
S
)-equol limit its efficient production using only natural gut bacteria. In this study, the low (
S
)-equol biosynthesis of gut microorganisms was overcome by cloning the four enzymes involved in the biosynthesis from
Slackia isoflavoniconvertens
into
Escherichia coli
BL21(DE3). The reaction conditions were optimized for (
S
)-equol production from the recombinant strain, and this recombinant system enabled the efficient conversion of 200 μM and 1 mM daidzein to (
S
)-equol under aerobic conditions, achieving yields of 95% and 85%, respectively. Since the biosynthesis of
trans
-tetrahydrodaidzein was found to be a rate-determining step for (
S
)-equol production, dihydrodaidzein reductase (DHDR) was subjected to rational site-directed mutagenesis. The introduction of the DHDR P212A mutation increased the (
S
)-equol productivity from 59.0 mg/liter/h to 69.8 mg/liter/h in the whole-cell reaction. The P212A mutation caused an increase in the (
S
)-dihydrodaidzein enantioselectivity by decreasing the overall activity of DHDR, resulting in undetectable activity for (
R
)-dihydrodaidzein, such that a combination of the DHDR P212A mutant with dihydrodaidzein racemase enabled the production of (3
S
,4
R
)-tetrahydrodaidzein with an enantioselectivity of >99%.
Electroporation-Based Genetic Manipulation in Type I Methanotrophs
Authors: Yan Xin , Chu Frances , Puri Aaron W. , Fu Yanfen , Lidstrom Mary E. 
Published: January 2016

ABSTRACT

Methane is becoming a major candidate for a prominent carbon feedstock in the future, and the bioconversion of methane into valuable products has drawn increasing attention. To facilitate the use of methanotrophic organisms as industrial strains and accelerate our ability to metabolically engineer methanotrophs, simple and rapid genetic tools are needed. Electroporation is one such enabling tool, but to date it has not been successful in a group of methanotrophs of interest for the production of chemicals and fuels, the gammaproteobacterial (type I) methanotrophs. In this study, we developed electroporation techniques with a high transformation efficiency for three different type I methanotrophs:
Methylomicrobium buryatense
5GB1C,
Methylomonas
sp. strain LW13, and
Methylobacter
tundripaludum
21/22. We further developed this technique in
M. buryatense
, a haloalkaliphilic aerobic methanotroph that demonstrates robust growth with a high carbon conversion efficiency and is well suited for industrial use for the bioconversion of methane. On the basis of the high transformation efficiency of
M. buryatense
, gene knockouts or integration of a foreign fragment into the chromosome can be easily achieved by direct electroporation of PCR-generated deletion or integration constructs. Moreover, site-specific recombination (FLP-FRT [FLP recombination target] recombination) and
sacB
counterselection systems were employed to perform marker-free manipulation, and two new antibiotics, zeocin and hygromycin, were validated to be antibiotic markers in this strain. Together, these tools facilitate the rapid genetic manipulation of
M. buryatense
and other type I methanotrophs, promoting the ability to perform fundamental research and industrial process development with these strains.
Novel Enzyme Family Found in Filamentous Fungi Catalyzing
trans
-4-Hydroxylation of
l
-Pipecolic Acid
Authors: Hibi Makoto , Mori Ryosuke , Miyake Ryoma , Kawabata Hiroshi , Kozono Shoko , Takahashi Satomi , Ogawa Jun 
Published: January 2016

ABSTRACT

Hydroxypipecolic acids are bioactive compounds widely distributed in nature and are valuable building blocks for the organic synthesis of pharmaceuticals. We have found a novel hydroxylating enzyme with activity toward
l
-pipecolic acid (
l
-Pip) in a filamentous fungus,
Fusarium oxysporum
c8D. The enzyme
l
-Pip
trans
-4-hydroxylase (Pip4H) of
F. oxysporum
(
Fo
Pip4H) belongs to the Fe(II)/α-ketoglutarate-dependent dioxygenase superfamily, catalyzes the regio- and stereoselective hydroxylation of
l
-Pip, and produces optically pure
trans
-4-hydroxy-
l
-pipecolic acid (
trans
-4-
l
-HyPip). Amino acid sequence analysis revealed several fungal enzymes homologous with
Fo
Pip4H, and five of these also had
l
-Pip
trans
-4-hydroxylation activity. In particular, the homologous Pip4H enzyme derived from
Aspergillus nidulans
FGSC A4 (
An
Pip4H) had a broader substrate specificity spectrum than other homologues and reacted with the
l
and
d
forms of various cyclic and aliphatic amino acids. Using
Fo
Pip4H as a biocatalyst, a system for the preparative-scale production of chiral
trans
-4-
l
-HyPip was successfully developed. Thus, we report a fungal family of
l
-Pip hydroxylases and the enzymatic preparation of
trans
-4-
l
-HyPip, a bioactive compound and a constituent of secondary metabolites with useful physiological activities.
Reduced Glutathione Mediates Resistance to H
2
S Toxicity in Oral Streptococci
Authors: Ooi Xi Jia , Tan Kai Soo 
Published: January 2016

ABSTRACT

Periodontal disease is associated with changes in the composition of the oral microflora, where health-associated oral streptococci decrease while Gram-negative anaerobes predominate in disease. A key feature of periodontal disease-associated anaerobes is their ability to produce hydrogen sulfide (H
2
S) abundantly as a by-product of anaerobic metabolism. So far, H
2
S has been reported to be either cytoprotective or cytotoxic by modulating bacterial antioxidant defense systems. Although oral anaerobes produce large amounts of H
2
S, the potential effects of H
2
S on oral streptococci are currently unknown. The aim of this study was to determine the effects of H
2
S on the survival and biofilm formation of oral streptococci. The growth and biofilm formation of
Streptococcus mitis
and
Streptococcus oralis
were inhibited by H
2
S. However, H
2
S did not significantly affect the growth of
Streptococcus gordonii
or
Streptococcus sanguinis
. The differential susceptibility of oral streptococci to H
2
S was attributed to differences in the intracellular concentrations of reduced glutathione (GSH). In the absence of GSH, H
2
S elicited its toxicity through an iron-dependent mechanism. Collectively, our results showed that H
2
S exerts antimicrobial effects on certain oral streptococci, potentially contributing to the decrease in health-associated plaque microflora.
HupO, a Novel Regulator Involved in Thiosulfate-Responsive Control of HupSL [NiFe]-Hydrogenase Synthesis in Thiocapsa roseopersicina
Authors: Nagy Ildikó K. , Kovács Kornél L. , Rákhely Gábor , Maróti Gergely 
Published: January 2016

ABSTRACT

[NiFe]-hydrogenases are regulated by various factors to fulfill their physiological functions in bacterial cells. The photosynthetic purple sulfur bacterium
Thiocapsa roseopersicina
harbors four functional [NiFe]-hydrogenases: HynSL, HupSL, Hox1, and Hox2. Most of these hydrogenases are functionally linked to sulfur metabolism, and thiosulfate has a central role in this organism. The membrane-associated Hup hydrogenases have been shown to play a role in energy conservation through hydrogen recycling. The expression of Hup-type hydrogenases is regulated by H
2
in
Rhodobacter capsulatus
and
Cupriavidus necator
; however, it has been shown that the corresponding hydrogen-sensing system is nonfunctional in
T. roseopersicina
and that thiosulfate is a regulating factor of
hup
expression. Here, we describe the discovery and analysis of mutants of a putative regulator (HupO) of the Hup hydrogenase in
T. roseopersicina
. HupO appears to mediate the transcriptional repression of Hup enzyme synthesis under low-thiosulfate conditions. We also demonstrate that the presence of the Hox1 hydrogenase strongly influences Hup enzyme synthesis in that
hup
expression was decreased significantly in the
hox1
mutant. This reduction in Hup synthesis could be reversed by mutation of
hupO
, which resulted in strongly elevated
hup
expression, as well as Hup protein levels, and concomitant
in vivo
hydrogen uptake activity in the
hox1
mutant. However, this regulatory control was observed only at low thiosulfate concentrations. Additionally, weak hydrogen-dependent
hup
expression was shown in the
hupO
mutant strain lacking the Hox1 hydrogenase. HupO-mediated Hup regulation therefore appears to link thiosulfate metabolism and the hydrogenase network in
T. roseopersicina
.