bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple glacial refugia for cool‐temperate deciduous trees in northern East Asia: the Mongolian oak as a case study
Authors: Zeng Yan‐Fei , Wang Wen‐Ting , Liao Wan‐Jin , Wang Hong‐Fang , Zhang Da‐Yong 
Published: October 2015

AbstractIn East Asia, temperate forests are predicted to have retracted southward to c. 30° N during the last glacial maximum (LGM) based on fossil pollen data, whereas phylogeographic studies have often suggested glacial in situ survival of cool‐temperate deciduous trees in their modern northern ranges. Here we report a study of the genetic diversity and structure of 29 natural Mongolian oak (Quercus mongolica) populations using 19 nuclear simple sequence repeat (nSSR) loci and four chloroplast DNA fragments. Bayesian clustering analysis with nSSRs revealed five groups, which were inferred by approximate Bayesian computation (ABC) to have diverged in multiple refugia through multiple glacial–interglacial cycles. Analysis of chloroplast DNA variation revealed four lineages that were largely but incompletely geographically disjunct. Ecological niche modelling (ENMs) indicated a southward range shift of the oak's distribution at the LGM, although high suitability scores were also evident in the Changbai Mts. (Northeast China), the Korean Peninsula, areas surrounding the Bohai Sea, and along the coast of the Russian Far East. In addition, endemic chloroplast DNA haplotypes and nuclear lineages occurred in high‐latitude northern areas where the ENM predicted no suitable habitat. The combined evidence from nuclear and chloroplast DNA, and the results of the ENM clearly demonstrate that multiple northern refugia, including cryptic ones, were maintained across the current distributional range of the Mongolian oak during the LGM or earlier glacial periods. Though spatially limited, postglacial expansions from these refugia have led to a pattern of decreased genetic diversity with increasing latitude.
Identification of the HrpS binding site in the hrpL promoter and effect of the RpoN binding site of HrpS on the regulation of the type III secretion system in Erwinia amylovora
Authors: Lee Jae Hoon , Sundin George W. , Zhao Youfu 
Published: October 2015

SummaryThe type III secretion system (T3SS) is a key pathogenicity factor in Erwinia amylovora. Previous studies have demonstrated that the T3SS in E. amylovora is transcriptionally regulated by an RpoN–HrpL sigma factor cascade, which is activated by the bacterial alarmone (p)ppGpp. In this study, the binding site of HrpS, an enhancer binding protein, was identified for the first time in plant‐pathogenic bacteria. Complementation of the hrpL mutant with promoter deletion constructs of the hrpL gene and promoter activity analyses using various lengths of the hrpL promoter fused to a promoter‐less green fluorescent protein (gfp) reporter gene delineated the upstream region for HrpS binding. Sequence analysis revealed a dyad symmetry sequence between −138 and −125 nucleotides (TGCAA‐N4‐TTGCA) as the potential HrpS binding site, which is conserved in the promoter of the hrpL gene among plant enterobacterial pathogens. Results of quantitative real‐time reverse transcription‐polymerase chain reaction (qRT‐PCR) and electrophoresis mobility shift assay coupled with site‐directed mutagenesis (SDM) analysis showed that the intact dyad symmetry sequence was essential for HrpS binding, full activation of T3SS gene expression and virulence. In addition, the role of the GAYTGA motif (RpoN binding site) of HrpS in the regulation of T3SS gene expression in E. amylovora was characterized by complementation of the hrpS mutant using mutant variants generated by SDM. Results showed that a Y100F substitution of HrpS complemented the hrpS mutant, whereas Y100A and Y101A substitutions did not. These results suggest that tyrosine (Y) and phenylalanine (F) function interchangeably in the conserved GAYTGA motif of HrpS in E. amylovora.
Photorespiration participates in the assimilation of acetate in Chlorella sorokiniana under high light
Authors: Xie Xiujun , Huang Aiyou , Gu Wenhui , Zang Zhengrong , Pan Guanghua , Gao Shan , He Linwen , Zhang Baoyu , Niu Jianfeng , Lin Apeng , Wang Guangce 
Published: October 2015

Summary

The development of microalgae on an industrial scale largely depends on the economic feasibility of mass production. High light induces productive suspensions during cultivation in a tubular photobioreactor. Herein, we report that high light, which inhibited the growth of Chlorella sorokiniana under autotrophic conditions, enhanced the growth of this alga in the presence of acetate.

We compared pigments, proteomics and the metabolic flux ratio in C. sorokiniana cultivated under high light (HL) and under low light (LL) in the presence of acetate.

Our results showed that high light induced the synthesis of xanthophyll and suppressed the synthesis of chlorophylls. Acetate in the medium was exhausted much more rapidly in HL than in LL. The data obtained from LC‐MS/MS indicated that high light enhanced photorespiration, the Calvin cycle and the glyoxylate cycle of mixotrophic C. sorokiniana. The results of metabolic flux ratio analysis showed that the majority of the assimilated carbon derived from supplemented acetate, and photorespiratory glyoxylate could enter the glyoxylate cycle.

Based on these data, we conclude that photorespiration provides glyoxylate to speed up the glyoxylate cycle, and releases acetate‐derived CO2 for the Calvin cycle. Thus, photorespiration connects the glyoxylate cycle and the Calvin cycle, and participates in the assimilation of supplemented acetate in C. sorokiniana under high light.
Structure of RagB, a major immunodominant outer‐membrane surface receptor antigen of Porphyromonas gingivalis
Authors: Goulas T. , Garcia‐Ferrer I. , Hutcherson J.A. , Potempa B.A. , Potempa J. , Scott D.A. , Gomis‐Rüth F. Xavier 
Published: October 2015

SummaryPorphyromonas gingivalis is the main causative agent of periodontitis. It deregulates the inflammatory and innate host immune responses through virulence factors, which include the immunodominant outer‐membrane surface receptor antigens A (PgRagA) and B (PgRagB), co‐transcribed from the rag pathogenicity island. The former is predicted to be a Ton‐dependent porin‐type translocator but the targets of this translocation and the molecular function of PgRagB are unknown. Phenomenologically, PgRagB has been linked with epithelial cell invasion and virulence according to murine models. It also acts as a Toll‐like receptor agonist and promotes multiple mediators of inflammation. Hence, PgRagB is a candidate for the development of a periodontitis vaccine, which would be facilitated by the knowledge of its atomic structure. Here, we crystallized and solved the structure of 54‐kDa PgRagB, which revealed a single domain centered on a curved helical scaffold. It consists of four tetratrico peptide repeats (TPR1–4), each arranged as two helices connected by a linker, plus two extra downstream capping helices. The concave surface bears four large intertwined irregular inserts (A–D), which contribute to an overall compact moiety. Overall, PgRagB shows substantial structural similarity with Bacteroides thetaiotaomicron SusD and Tannerella forsythia NanU, which are, respectively, engaged in binding and uptake of malto‐oligosaccharide/starch and sialic acid. This suggests a similar sugar‐binding function for PgRagB for uptake by the cognate PgRagA translocator, and, consistently, three potential monosaccharide‐binding sites were tentatively assigned on the molecular surface.
Stripe rust resistance gene Yr18 and its suppressor gene in Chinese wheat landraces
Authors: Wu Ling , Xia Xianchun , Rosewarne Garry M. , Zhu Huazhong , Li Shizhao , Zhang Zhengyu , He Zhonghu 
Published: October 2015

AbstractThe slow‐rusting and mildewing gene Yr18/Lr34/Pm38/Sr57 confers partial, durable resistance to multiple fungal pathogens and has its origins in China. A number of diagnostic markers were developed for this gene based on the gene sequence, but these markers do not always predict the presence of the resistant phenotype as some wheat varieties with the gene are susceptible to stripe rust in China. We hypothesized that these varieties have a suppressor of Yr18. This study was undertaken to determine the presence of Yr18, the suppressor and/or another resistance gene in 144 Chinese wheat landraces using molecular markers and stripe rust field data. Forty‐three landraces were predicted to have Yr18 based on the presence of the markers, but had final disease severities higher than 70%, indicating that this gene may be under the influence of a suppressor. Four of these landraces, ‘Sichuanyonggang 2’, ‘Baikemai’, ‘Youmai’ and ‘Zhangsihuang’, were chosen for genetic studies. Crosses were made between the lines and ‘Avocet S’, with further crosses of Sichuanyonggang 2 × ‘Huixianhong’ and Sichuanyonggang 2 × ‘Chinese Spring’. The F1 plants of Sichuanyonggang 2/Chinese Spring was susceptible indicating the presence of a dominant suppressor gene. The results of genetic analyses of F2:3 and BC1F2 families derived from these crosses indicated the presence of Yr18, a Yr18 suppressor and another additive resistance gene. The Yr18 region in Sichuanyonggang 2 was sequenced to ensure that it contained the functional allele. This is the first report of a suppressor of Yr18/Lr34/Pm38/Sr57 gene with respect to stripe rust response.
Embodied simulation of emotional valence: Facial muscle responses to abstract and concrete words
Authors: Künecke Janina , Sommer Werner , Schacht Annekathrin , Palazova Marina 
Published: October 2015

AbstractSemantic knowledge is thought to be at least partially grounded in sensory, motor, and affective information, acquired through experiences in our inner and outer world. The reactivation of experience‐related information during meaning access is called simulation. In the affective simulation account, it is assumed that the grounding information depends on the concepts’ concreteness. Whereas abstract concepts are thought to be mainly represented through affective experiential information, concrete words rely more on sensory‐motor experiential information. To test this hypothesis, we measured facial muscle activity as an indicator of affective simulation during visual word recognition. Words varied on the dimensions of concreteness and valence. Behavioral and electromyographic data were analyzed with linear mixed‐effects models with maximal random effect structure to optimize generalization over participants and word samples. Contrary to this hypothesis, we found a valence effect in the m. corrugator supercilii only in response to concrete but not to abstract words. Our data show that affective simulation as measured with facial muscle activity occurs in response to concrete rather than to abstract words. More concrete words are supposed to have higher context availability and richer visual imagery, which might promote affective simulation on the expressive level of facial muscle activity. The results are in line with embodied accounts of semantic representation but speak against its predominant role for representing affective information in abstract concepts.
Revisiting dysanapsis: sex‐based differences in airways and the mechanics of breathing during exercise
Authors: Sheel A. William , Dominelli Paolo B. , Molgat‐Seon Yannick 
Published: October 2015

New Findings

What is the topic of this review?
This review focuses on sex‐based differences in the anatomy of the respiratory system, which manifest in mechanical ventilatory contraints and potentially alter the integrative response to exercise.

What advances does it highlight?
Recent evidence indicates that women have smaller conducting airways than men, even when matched for lung size. Consequently, women are more likely to experience mechanical ventilatory constraints to exercise hyperpnoea. Furthermore, at a given ventilation, women have a higher work and oxygen cost of breathing, both of which may lead to differences in the whole‐body integrative response to dynamic exercise.

Our understanding of the human ventilatory response to exercise is largely based on a historical body of literature focused primarily on male rather than female research subjects. In recent years, important sex‐based differences in the anatomy of the human respiratory system have been identified; for a given lung size, women appear to have smaller‐diameter conducting airways than men. The presence of such inherent differences in the tracheobronchial tree greatly affects the mechanics of airflow generation, especially during conditions of high ventilation rates, such as exercise. Data from a growing number of studies suggest that women may be more susceptible to respiratory system limitations during exercise than their male counterparts. Specifically, women are more likely to experience expiratory flow limitation and exercise‐induced arterial hypoxaemia and have a higher metabolic cost of breathing for a given ventilation. Collectively, the available evidence suggests that sex differences in the ventilatory response to exercise are present and may have important ramifications for the integrated response to exercise; however, several fundamental questions remain unanswered.
Sex differences in fatigability of dynamic contractions
Authors: Hunter Sandra K. 
Published: October 2015

New Findings

What is the topic of this review?
Women are usually less fatigable than men for isometric fatiguing contractions of similar intensity, but whether this occurs for dynamic tasks is less clear. This review presents evidence that the sex difference in muscle fatigue of repeated dynamic contractions is specific to the task requirements, including the velocity of shortening and the muscle group involved.

What advances does it highlight?
Contractile mechanisms are responsible for the sex differences in muscle fatigue for slow‐velocity and low‐load dynamic tasks. The variability of the sex difference in fatigability among dynamic tasks has implications for fatiguing contractions prescribed in training and rehabilitation to men and women.

Women are usually less fatigable than men during single‐limb isometric contractions, primarily because of sex‐related differences in contractile mechanisms. It is less clear whether these sex differences in muscle fatigue occur for dynamic fatiguing tasks. This review highlights new findings that the sex difference in fatigability for dynamic shortening contractions with a single limb is dependent on the contraction velocity and the muscle group involved. Recent studies demonstrate that women are less fatigable than men for a dynamic task as follows: (i) the elbow‐flexor muscles at slow‐ but not high‐velocity contractions; and (ii) the knee‐extensor muscles when muscle fatigue was quantified as a reduction in the maximal voluntary isometric contraction force after the dynamic fatiguing task. Contractile mechanisms are responsible for the sex difference in muscle fatigue of the dynamic contractions, with no evidence for a sex difference in the reduction in voluntary activation (i.e. central fatigue). Thus, these findings indicate that the sex difference in muscle fatigue of dynamic contractions is task specific. These data also challenge the assumption that men and women respond in a similar manner to training and rehabilitation that involve fatiguing contractions to overload the neuromuscular system. There is, however, a tremendous opportunity for conducting high‐impact studies to gain insight into those factors that define the sex‐based differences in muscle fatigue during dynamic tasks. Such studies can define the boundaries to human performance in both men and women during athletic endeavours, ergonomic tasks and rehabilitation.
Impact of sympathetic nervous system activity on post‐exercise flow‐mediated dilatation in humans
Authors: Atkinson Ceri L. , Lewis Nia C.S. , Carter Howard H. , Thijssen Dick H.J. , Ainslie Philip N. , Green Daniel J. 
Published: October 2015

Key points
Previous studies indicate a transient reduction in arterial function following large muscle group exercise, but the mechanisms involved are unknown.
Sympathetic nervous system activation may contribute to such reductions through direct effects in the artery wall, or because of decreases in arterial shear stress.
Administration of prazosin (an α1‐adrenoreceptor blocker) abolished the transient reduction in vascular function observed under placebo conditions following exercise. This effect could not be explained by drug‐induced changes in arterial shear stress.
These results suggest that sympathetic vasoconstriction directly competes with endothelium‐dependent dilator activity to influence post‐exercise vascular function.
These findings have implications for understanding the stimuli responsible for exercise‐induced adaptations in arterial function and health in humans.
AbstractTransient reduction in vascular function following systemic large muscle group exercise has previously been reported in humans. The mechanisms responsible are currently unknown. We hypothesised that sympathetic nervous system activation, induced by cycle ergometer exercise, would contribute to post‐exercise reductions in flow‐mediated dilatation (FMD). Ten healthy male subjects (28 ± 5 years) undertook two 30 min sessions of cycle exercise at 75% HRmax. Prior to exercise, individuals ingested either a placebo or an α1‐adrenoreceptor blocker (prazosin; 0.05 mg kg−1). Central haemodynamics, brachial artery shear rate (SR) and blood flow profiles were assessed throughout each exercise bout and in response to brachial artery FMD, measured prior to, immediately after and 60 min after exercise. Cycle exercise increased both mean and antegrade SR (P < 0.001) with retrograde SR also elevated under both conditions (P < 0.001). Pre‐exercise FMD was similar on both occasions, and was significantly reduced (27%) immediately following exercise in the placebo condition (t‐test, P = 0.03). In contrast, FMD increased (37%) immediately following exercise in the prazosin condition (t‐test, P = 0.004, interaction effect P = 0.01). Post‐exercise FMD remained different between conditions after correction for baseline diameters preceding cuff deflation and also post‐deflation SR. No differences in FMD or other variables were evident 60 min following recovery. Our results indicate that sympathetic vasoconstriction competes with endothelium‐dependent dilator activity to determine post‐exercise arterial function. These findings have implications for understanding the chronic impacts of interventions, such as exercise training, which affect both sympathetic activity and arterial shear stress.
Sodium nitrate alleviates functional muscle ischaemia in patients with Becker muscular dystrophy
Authors: Nelson Michael D. , Rosenberry Ryan , Barresi Rita , Tsimerinov Evgeny I. , Rader Florian , Tang Xiu , Mason O'Neil , Schwartz Avery , Stabler Thomas , Shidban Sarah , Mobaligh Neigena , Hogan Shomari , Elashoff Robert , Allen Jason D. , Victor Ronald G. 
Published: October 2015

Key points
Dystrophin deficiency disrupts sarcolemmal targeting of neuronal nitric oxide synathase, resulting in functional muscle ischaemia.
Chronic treatment of dystrophic mice with an inorganic nitric oxide (NO) donor alleviates this ischaemia and improves many features of the dystrophic phenotype.
The present study translates this preclinical work by showing that a single oral dose of sodium nitrate,which serves as a NO donor when reduced to circulating nitrite by the commensal bacteria in the oral cavity, alleviates functional muscle ischaemia and restores normal blood flow regulation in human patients with dystrophinopathy.
The results of the present study further support the mechanistic hypothesis that circulating nitrite serves as an alternative NO donor when reduced by deoxyhaemoglobin and/or deoxymyoglobin in exercising muscle.
AbstractBecker muscular dystrophy (BMD) is a progressive X‐linked muscle wasting disease for which there is no treatment. BMD is caused by in‐frame mutations in the gene encoding dystrophin, a structural cytoskeletal protein that also targets other proteins to the sarcolemma. Among these is neuronal nitric oxide synthase mu (nNOSμ), which requires specific spectrin‐like repeats (SR16/17) in dystrophin's rod domain and the adaptor protein α‐syntrophin for sarcolemmal targeting. When healthy skeletal muscle is exercised, sarcolemmal nNOSμ‐derived nitric oxide (NO) attenuates α‐adrenergic vasoconstriction, thus optimizing perfusion. In the mdx mouse model of dystrophinopathy, this protective mechanism (functional sympatholysis) is defective, resulting in functional muscle ischaemia. Treatment with a NO‐donating non‐steroidal anti‐inflammatory drug (NSAID) alleviates this ischaemia and improves the murine dystrophic phenotype. In the present study, we report that, in 13 men with BMD, sympatholysis is defective mainly in patients whose mutations disrupt sarcolemmal targeting of nNOSμ, with the vasoconstrictor response measured as a decrease in muscle oxygenation (near infrared spectroscopy) to reflex sympathetic activation. Then, in a single‐arm, open‐label trial in 11 BMD patients and a double‐blind, placebo‐controlled cross‐over trial in six patients, we show that acute treatment with oral sodium nitrate, an inorganic NO donor without a NSIAD moiety, restores sympatholysis and improves post‐exercise hyperaemia (Doppler ultrasound). By contrast, sodium nitrate improves neither sympatholysis, nor hyperaemia in healthy controls. Thus, a simple NO donor recapitulates the vasoregulatory actions of sarcolemmal nNOS in BMD patients, and constitutes a putative novel therapy for this disease.
Esters of Pyrazinoic Acid Are Active against Pyrazinamide-Resistant Strains of Mycobacterium tuberculosis and Other Naturally Resistant Mycobacteria
In Vitro
and
Ex Vivo
within Macrophages
Authors: Pires David , Valente Emília , Simões Marta Filipa , Carmo Nuno , Testa Bernard , Constantino Luís , Anes Elsa 
Published: October 2015

ABSTRACT

Pyrazinamide (PZA) is active against major
Mycobacterium tuberculosis
species (
M. tuberculosis
,
M. africanum
, and
M. microti
) but not against
M. bovis
and
M. avium
. The latter two are mycobacterial species involved in human and cattle tuberculosis and in HIV coinfections, respectively. PZA is a first-line agent for the treatment of human tuberculosis and requires activation by a mycobacterial pyrazinamidase to form the active metabolite pyrazinoic acid (POA). As a result of this mechanism, resistance to PZA, as is often found in tuberculosis patients, is caused by point mutations in pyrazinamidase. In previous work, we have shown that POA esters and amides synthesized in our laboratory were stable in plasma (M. F. Simões, E. Valente, M. J. Gómez, E. Anes, and L. Constantino, Eur J Pharm Sci 37:257–263, 2009,
http://dx.doi.org/10.1016/j.ejps.2009.02.012
). Although the amides did not present significant activity, the esters were active against sensitive mycobacteria at concentrations 5- to 10-fold lower than those of PZA. Here, we report that these POA derivatives possess antibacterial efficacy
in vitro
and
ex vivo
against several species and strains of
Mycobacterium
with natural or acquired resistance to PZA, including
M. bovis
and
M. avium
. Our results indicate that the resistance probably was overcome by cleavage of the prodrugs into POA and a long-chain alcohol. Although it is not possible to rule out that the esters have intrinsic activity
per se
, we bring evidence here that long-chain fatty alcohols possess a significant antimycobacterial effect against PZA-resistant species and strains and are not mere inactive promoieties. These findings may lead to candidate dual drugs having enhanced activity against both PZA-susceptible and PZA-resistant isolates and being suitable for clinical development.