bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly diverse and spatially heterogeneous mycorrhizal symbiosis in a rare epiphyte is unrelated to broad biogeographic or environmental features
Authors: Kartzinel Tyler R. , Trapnell Dorset W. , Shefferson Richard P. 
Published: October 2013

AbstractSymbiotic interactions are common in nature. In dynamic or degraded environments, the ability to associate with multiple partners (i.e. broad specificity) may enable species to persist through fluctuations in the availability of any particular partner. Understanding how species interactions vary across landscapes is necessary to anticipate direct and indirect consequences of environmental degradation on species conservation. We asked whether mycorrhizal symbiosis by populations of a rare epiphytic orchid (Epidendrum firmum) is related to geographic or environmental heterogeneity. The latter would suggest that interactions are governed by environmental conditions rather than historic isolation of populations and/or mycorrhizal fungi. We used DNA‐based methods to identify mycorrhizal fungi from eleven E. firmum populations in Costa Rica. We used molecular and phylogenetic analyses to compare associations. Epidendrum firmum exhibited broad specificity, associating with diverse mycorrhizal fungi, including six Tulasnellaceae molecular operational taxonomic units (MOTUs), five Sebacinales MOTUs and others. Notably, diverse mycorrhizal symbioses formed in disturbed pasture and roadside habitats. Mycorrhizal fungi exhibited significant similarity within populations (spatial and phylogenetic autocorrelation) and significant differences among populations (phylogenetic community dissimilarity). However, mycorrhizal symbioses were not significantly associated with biogeographic or environmental features. Such unexpected heterogeneity among populations may result from complex combinations of fine‐scale environmental factors and macro‐evolutionary patterns of change in mycorrhizal specificity. Thus, E. firmum exhibits broad specificity and the potential for opportunistic associations with diverse fungi. We suggest that these characteristics could confer symbiotic assurance when mycorrhizal fungi are stochastically available, which may be crucial in dynamic or disturbed habitats such as tropical forest canopies.
Phylogeography and niche modelling of the relict plant Amborella trichopoda (Amborellaceae) reveal multiple Pleistocene refugia in New Caledonia
Authors: Poncet Valérie , Munoz François , Munzinger Jérôme , Pillon Yohan , Gomez Céline , Couderc Marie , Tranchant‐Dubreuil Christine , Hamon Serge , de Kochko Alexandre 
Published: October 2013

AbstractAmborella trichopoda Baill. (Amborellaceae, Amborellales), the sole living member of the sister group to all other extant angiosperms, is endemic to New Caledonia. We addressed the intraspecific phylogeography of Amborella by investigating whether its present population genetic structure could be related to its current and past habitats. We found moderate range‐wide genetic diversity based on nuclear microsatellite data and detected four well‐differentiated, geographically distinct genetic groups using Bayesian clustering analyses. We modelled the ecological niche of Amborella based on the current climatic and environmental conditions. The predictive ability of the model was very good throughout the Central East mainland zone, but Amborella was predicted in the northern part of the island where this plant has not been reported. Furthermore, no significant barrier was detected based on habitat suitability that could explain the genetic differentiation across the area. Conversely, we found that the main genetic clusters could be related to the distribution of the suitable habitat at the last glacial maximum (LGM, c. 21 000 years BP), when Amborella experienced a dramatic 96.5% reduction in suitable area. At least two lineages survived in distinct putative refugia located in the Massif des Lèvres and in the vicinity of Mount Aoupinié. Our findings finally confirmed the importance of LGM rainforest refugia in shaping the current intra‐ and interspecific diversity in New Caledonian plants and revealed the possibility of an as yet unreported refugium. The combination of niche modelling and population genetics thereby offered novel insight into the biogeographical history of an emblematic taxon.
Combining animal personalities with transcriptomics resolves individual variation within a wild‐type zebrafish population and identifies underpinning molecular differences in brain function
Authors: Rey S. , Boltana S. , Vargas R. , Roher N. , MacKenzie S. 
Published: October 2013

AbstractResolving phenotype variation within a population in response to environmental perturbation is central to understanding biological adaptation. Relating meaningful adaptive changes at the level of the transcriptome requires the identification of processes that have a functional significance for the individual. This remains a major objective towards understanding the complex interactions between environmental demand and an individual's capacity to respond to such demands. The interpretation of such interactions and the significance of biological variation between individuals from the same or different populations remain a difficult and under‐addressed question. Here, we provide evidence that variation in gene expression between individuals in a zebrafish population can be partially resolved by a priori screening for animal personality and accounts for >9% of observed variation in the brain transcriptome. Proactive and reactive individuals within a wild‐type population exhibit consistent behavioural responses over time and context that relates to underlying differences in regulated gene networks and predicted protein–protein interactions. These differences can be mapped to distinct regions of the brain and provide a foundation towards understanding the coordination of underpinning adaptive molecular events within populations.
Calcium Homeostasis and Sensitization in Pulmonary Arterial Smooth Muscle
Authors: Jernigan Nikki L. , Resta Thomas C. 
Published: October 2013

AbstractThe pulmonary circulation is a low‐pressure, low‐resistance vascular bed with little to no resting tone under normal conditions. An increase in the [Ca2+]i in PASMCs is an important determinant of contraction, migration, and proliferation. Both Ca2+ influx through plasma membrane Ca2+ channels and Ca2+ release from the SR contribute to a rise in [Ca2+]i. Additionally important in the pulmonary circulation are several kinase‐mediated signaling pathways that act to increase the sensitivity of the contractile apparatus to [Ca2+]i. Similarly, cytoskeletal processes resulting in dynamic remodeling of the actin cytoskeleton can further contribute to contractility in the pulmonary circulation. In addition to endocrine, paracrine, and autocrine factors, alveolar hypoxia is an important stimulus for pulmonary vasoconstriction. However, prolonged hypoxia is a critical pathological stimulus associated with the development of pulmonary hypertension and cor pulmonale. In this review, we will discuss recent advances in our understanding of how Ca2+ homeostasis and sensitization regulate PASMC contractility under both physiological and pathophysiological conditions.
Requirement of essential Pbp2x and GpsB for septal ring closure in Streptococcus pneumoniae D39
Authors: Land Adrian D. , Tsui Ho‐Ching T. , Kocaoglu Ozden , Vella Stephen A. , Shaw Sidney L. , Keen Susan K. , Sham Lok‐To , Carlson Erin E. , Winkler Malcolm E. 
Published: October 2013

SummaryBacterial cell shapes are manifestations of programs carried out by multi‐protein machines that synthesize and remodel the resilient peptidoglycan (PG) mesh and other polymers surrounding cells. GpsB protein is conserved in low‐GC Gram‐positive bacteria and is not essential in rod‐shaped Bacillus subtilis, where it plays a role in shuttling penicillin‐binding proteins (PBPs) between septal and side‐wall sites of PG synthesis. In contrast, we report here that GpsB is essential in ellipsoid‐shaped, ovococcal Streptococcus pneumoniae (pneumococcus), and depletion of GpsB leads to formation of elongated, enlarged cells containing unsegregated nucleoids and multiple, unconstricted rings of fluorescent‐vancomycin staining, and eventual lysis. These phenotypes are similar to those caused by selective inhibition of Pbp2x by methicillin that prevents septal PG synthesis. Dual‐protein 2D and 3D‐SIM (structured illumination) immunofluorescence microscopy (IFM) showed that GpsB and FtsZ have overlapping, but not identical, patterns of localization during cell division and that multiple, unconstricted rings of division proteins FtsZ, Pbp2x, Pbp1a and MreC are in elongated cells depleted of GpsB. These patterns suggest that GpsB, like Pbp2x, mediates septal ring closure. This first dual‐protein 3D‐SIM IFM analysis also revealed separate positioning of Pbp2x and Pbp1a in constricting septa, consistent with two separable PG synthesis machines.
An alternative outer membrane secretion mechanism for an autotransporter protein lacking a C‐terminal stable core
Authors: Besingi Richard N. , Chaney Julie L. , Clark Patricia L. 
Published: October 2013

SummaryAutotransporter (AT) proteins are a broad class of virulence factors from Gram‐negative pathogens. AT outer membrane (OM) secretion appears simple in many regards, yet the mechanism that enables transport of the central AT ‘passenger’ across the OM remains unclear. OM secretion efficiency for two AT passengers is enhanced by a ∼ 20 kDa stable core at the C‐terminus of the passenger, but studies on a broader range of AT proteins are needed in order to determine whether a stability difference between the passenger N‐ and C‐terminus represents a truly common mechanistic feature. Yersinia pestis YapV is homologous to Shigella flexneri IcsA, and like IcsA, YapV recruits mammalian neural Wiskott–Aldrich syndrome protein (N‐WASP). In vitro, the purified YapV passenger is functional and rich in β‐sheet structure, but lacks a ∼ 20 kDa C‐terminal stable core. However, the N‐terminal 49 residues of the YapV passenger globally destabilize the entire YapV passenger, enhancing its OM secretion efficiency. These results indicate that the contributions of AT passenger sequences to OM secretion efficiency extend beyond a C‐terminal stable core, and highlight a role of the passenger N‐terminus in reducing passenger stability in order to facilitate OM secretion of some AT proteins.
O‐linked protein glycosylation in mycoplasma
Authors: Jordan David S. , Daubenspeck James M. , Laube Audra H. , Renfrow Matthew B. , Dybvig Kevin 
Published: October 2013

SummaryAlthough mycoplasmas have a paucity of glycosyltransferases and nucleotidyltransferases recognizable by bioinformatics, these bacteria are known to produce polysaccharides and glycolipids. We show here that mycoplasmas also produce glycoproteins and hence have glycomes more complex than previously realized. Proteins from several species of Mycoplasma reacted with a glycoprotein stain, and the murine pathogen Mycoplasma arthritidis was chosen for further study. The presence of M. arthritidis glycoproteins was confirmed by high‐resolution mass spectrometry. O‐linked glycosylation was clearly identified at both serine and threonine residues. No consensus amino acid sequence was evident for the glycosylation sites of the glycoproteins. A single hexose was identified as the O‐linked modification, and glucose was inferred by 13C‐labelling to be the hexose at several of the glycosylation sites. This is the first study to conclusively identify sites of protein glycosylation in any of the mollicutes.
gfsA encodes a novel galactofuranosyltransferase involved in biosynthesis of galactofuranose antigen of O‐glycan in Aspergillus nidulans and Aspergillus fumigatus
Authors: Komachi Yuji , Hatakeyama Shintaro , Motomatsu Haruka , Futagami Taiki , Kizjakina Karina , Sobrado Pablo , Ekino Keisuke , Takegawa Kaoru , Goto Masatoshi , Nomura Yoshiyuki , Oka Takuji 
Published: October 2013

SummaryThe cells walls of filamentous fungi in the genus Aspergillus have galactofuranose (Galf)‐containing polysaccharides and glycoconjugates, including O‐glycans, N‐glycans, fungal‐type galactomannan and glycosylinositolphosphoceramide, which are important for cell wall integrity. Here, we attempted to identify galactofuranosyltransferases that couple Galf monomers onto other wall components in Aspergillus nidulans. Using reverse‐genetic and biochemical approaches, we identified that the AN8677 gene encoded a galactofuranosyltransferase, which we called GfsA, involved in Galf antigen biosynthesis. Disruption of gfsA reduced binding of β‐Galf‐specific antibody EB‐A2 to O‐glycosylated WscA protein and galactomannoproteins. The results of an in‐vitro Galf antigen synthase assay revealed that GfsA has β1,5‐ or β1,6‐galactofuranosyltransferase activity for O‐glycans in glycoproteins, uses UDP‐d‐Galf as a sugar donor, and requires a divalent manganese cation for activity. GfsA was found to be localized at the Golgi apparatus based on cellular fractionation experiments. ΔgfsA cells exhibited an abnormal morphology characterized by poor hyphal extension, hyphal curvature and limited formation of conidia. Several gfsA orthologues were identified in members of the Pezizomycotina subphylum of Ascomycota, including the human pathogen Aspergillus fumigatus. To our knowledge, this is the first characterization of a fungal β‐galactofuranosyltransferase, which was shown to be involved in Galf antigen biosynthesis of O‐glycans in the Golgi.
LmHus1 is required for the DNA damage response in Leishmania major and forms a complex with an unusual Rad9 homologue
Authors: Damasceno Jeziel D. , Nunes Vinicius S. , Tosi Luiz R. O. 
Published: October 2013

SummaryGenotoxic stress activates checkpoint‐signalling pathways leading to cell cycle arrest and DNA repair. In many eukaryotes, the Rad9–Hus1–Rad1 (9‐1‐1) checkpoint complex participates in the early steps of the DNA damage response to replicative stress and is a pivotal contributor to genome homeostasis. The remarkable genome plasticity of the protozoan Leishmania hints at a peculiar DNA metabolism in these ancient eukaryotes. Therefore, we set out to investigate the existence of homologues of the 9‐1‐1 components in Leishmania major and found that LmHus1 and LmRad9 are phylogenetically related to the 9‐1‐1 complex subunits from other eukaryotes. Altered levels of LmHus1 and LmRad9 affected the parasite ability to manage genotoxic stress and LmHus1‐defficent cells were defective in controlling cell cycle progression in response to genotoxic stress. Upon DNA damage, LmHus1 was recruited to the chromatin and colocalized with the single‐stranded DNA‐binding protein LmRpa1. Also, LmHus1 interacted with LmRad9 to form a DNA damage responsive complex in vivo. Altogether, our data strongly indicate the participation of LmHus1, LmRad9 and LmRpa1 in the L. major DNA damage response and suggest their involvement in genome maintenance mechanisms.
Methionine sulphoxide reductases revisited: free methionine as a primary target of H2O2 stress in auxotrophic fission yeast
Authors: García‐Santamarina Sarela , Boronat Susanna , Ayté José , Hidalgo Elena 
Published: October 2013

SummaryAmino acid methionine can suffer reversible oxidation to sulphoxide and further irreversible over‐oxidation to methionine sulphone. As part of the cellular antioxidant scavenging activities are the methionine sulphoxide reductases (Msrs), with a reported role in methionine sulphoxide reduction, both free and in proteins. Three families of Msrs have been described, but the fission yeast genome only includes one representative for two of these families: MsrA/Mxr1 and MsrB/Mxr2. We have investigated their role in methionine reduction and H2O2 sensitivity. We show here that MsrA/Mxr1 is able to reduce free oxidized methionine. Cells lacking each one of the genes are not significantly sensitive to different types of oxidative stresses, neither display altered life span. However, only when deletion of msrA/mxr1 is combined with deletion of met6, which confers methionine auxotrophy, the survival upon H2O2 stress decreases by 100‐fold. In fact, cells lacking only Met6, and which therefore require addition of methionine to the growth media, are extremely sensitive to H2O2 stress. These and other evidences suggest that oxidation of free methionine is a primary target of peroxide toxicity in cells devoid of methionine biosynthetic capacity, and that an important role of Msrs is to recycle this oxidized free amino acid.
Concerted transfer of the virulence Ti plasmid and companion At plasmid in the Agrobacterium tumefaciens‐induced plant tumour
Authors: Lang Julien , Planamente Sara , Mondy Samuel , Dessaux Yves , Moréra Solange , Faure Denis 
Published: October 2013

SummaryThe plant pathogen Agrobacterium tumefaciens C58 harbours three independent type IV secretion (T4SS) machineries. T4SST‐DNA promotes the transfer of the T‐DNA to host plant cells, provoking tumour development and accumulation of opines such as nopaline and agrocinopines. T4SSpTi and T4SSpAt control the bacterial conjugation of the Ti and At plasmids respectively. Expression of T4SSpTi is controlled by the agrocinopine‐responsive transcriptional repressor AccR. In this work, we compared the genome‐wide transcriptional profile of the wild‐type A. tumefaciens strain C58 with that of its accR KO‐mutant to delineate the AccR regulon. In addition to the genes that encode agrocinopine catabolism and T4SSpTi, we found that AccR also regulated genes coding for nopaline catabolism and T4SSpAt. Further opine detection and conjugation assays confirmed the enhancement of nopaline consumption and At plasmid conjugation frequency in accR. Moreover, co‐regulation of the T4SSpTi and T4SSpAt correlated with the co‐transfer of the At and Ti plasmids both in vitro and in plant tumours. Finally, unlike T4SSpTi, T4SSpAt activation does not require quorum‐sensing. Overall this study highlights the regulatory interplays between opines, At and Ti plasmids that contribute to a concerted dissemination of the two replicons in bacterial populations colonizing the plant tumour.
Expression of tomato salicylic acid (SA)‐responsive pathogenesis‐related genes in Mi‐1‐mediated and SA‐induced resistance to root‐knot nematodes
Authors: Molinari Sergio , Fanelli Elena , Leonetti Paola 
Published: October 2013

SummaryThe expression pattern of pathogenesis‐related genes PR‐1, PR‐2 and PR‐5, considered as markers for salicylic acid (SA)‐dependent systemic acquired resistance (SAR), was examined in the roots and shoots of tomato plants pre‐treated with SA and subsequently infected with root‐knot nematodes (RKNs) (Meloidogyne incognita). PR‐1 was up‐regulated in both roots and shoots of SA‐treated plants, whereas the expression of PR‐5 was enhanced only in roots. The over‐expression of PR‐1 in the whole plant occurred as soon as 1 day after SA treatment. Up‐regulation of the PR‐1 gene was considered to be the main marker of SAR elicitation. One day after treatment, plants were inoculated with active juveniles (J2s) of M. incognita. The number of J2s that entered the roots and started to develop was significantly lower in SA‐treated than in untreated plants at 5 and 15 days after inoculation. The expression pattern of PR‐1, PR‐2 and PR‐5 was also examined in the roots and shoots of susceptible and Mi‐1‐carrying resistant tomato plants infected by RKNs. Nematode infection produced a down‐regulation of PR genes in both roots and shoots of SA‐treated and untreated plants, and in roots of Mi‐carrying resistant plants. Moreover, in resistant infected plants, PR gene expression, in particular PR‐1 gene expression, was highly induced in shoots. Thus, nematode infection was demonstrated to elicit SAR in shoots of resistant plants. The data presented in this study show that the repression of host defence SA signalling is associated with the successful development of RKNs, and that SA exogenously added as a soil drench is able to trigger a SAR‐like response to RKNs in tomato.
Correlation between motor and cognitive functions in the progressive course of Parkinson's disease
Authors: Murakami Hidetomo , Owan Yoshiyuki , Mori Yukiko , Fujita Kazuhisa , Futamura Akinori , Sugimoto Azusa , Kobayakawa Mutsutaka , Kezuka Machiko , Midorikawa Akira , Kawamura Mitsuru 
Published: October 2013

AbstractAimCorrelations between motor function and frontal‐executive function in Parkinson's disease (PD) have been examined previously, but correlations with other cognitive domains remain unknown. We examined the correlation between motor dysfunction and cognitive impairment with regard to their precise domains.MethodsMotor and cognitive functions were assessed in 61 patients. To assess motor function, the Unified Parkinson's Disease Rating Scale (UPDRS) was administered. The UPDRS score was assessed as general motor function with a sum of Parts II and III, and as subscores of individual motor symptoms (rigidity, tremor, akinesia and postural instability). To assess cognitive function, the Montreal Cognitive Assessment (MoCA) and the Frontal Assessment Battery (FAB) were administered. MoCA was assessed by a total score and subscores of six cognitive subdomains: visuospatial, executive, attention/concentration/working memory, language, memory and orientation. The correlation coefficients of both MoCA and FAB with patient background and motor symptoms were compared using Spearman's correlation coefficient.ResultsGeneral motor function and the subscore of postural instability showed significant negative correlations with MoCA, FAB, and the subdomains of visuospatial, executive and orientation skills. Tremor and rigidity showed no significant correlation with any cognitive assessment. Akinesia showed significant negative correlation with MoCA, and the subdomains of visuospatial and orientation skills.ConclusionsIn patients with PD, specific motor and cognitive functions correlate, with particular regard to postural instability and visuospatial skills. The correlations suggest functional links between a number of cerebral cortices and subcortical structures, and a common pathophysiology for motor and cognitive impairments in PD.
Pathogenesis of multiple system atrophy
Authors: Hasegawa Takafumi , Kikuchi Akio , Takeda Atsushi 
Published: October 2013

AbstractMultiple system atrophy (MSA) is an adult‐onset, progressive neurodegenerative disease involving parkinsonism, ataxia, and autonomic failure, in any combination. The unifying histopathological hallmark of MSA is the appearance of α‐synuclein (αSYN)‐positive, triangular‐shaped glial cytoplasmic inclusion (GCI) in affected brain regions including striatonigral and/or olivopontocerebellar systems. It is known that GCI follows the regions showing neuronal loss and gliosis, and the incidence of GCI is well correlated with disease severity and duration, suggesting that the oligodendroglial αSYN pathology in MSA would be a prerequisite for the disease rather than a consequence of glio‐neuronal degeneration. The mechanisms underlying the neuronal cell loss followed by oligodendroglial degeneration in MSA still remain elusive; however, recent observations from cultured cells, animal models, neuropathological and genetic studies have highlighted the several etiopathological factors including mitochondrial dysfunction, oxidative stress, aberrant misfolded protein processing and neuroinflammation. In the present review, we summarize a general overview of potential pathogenic processes and discuss the topics for debate especially focusing on the mechanisms by which αSYN accumulation in oligodendrocytes can secondarily lead to neuronal cell death.