bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local control of resource allocation is sufficient to model optimal dynamics in syntrophic systems
Authors: Ledder Glenn , Russo Sabrina E. , Muller Erik B. , Peace Angela , Nisbet Roger M. 
Published: October 2019

AbstractSyntrophic systems are common in nature and include forms of obligate mutualisms in which each participating organism or component of an organism obtains from the other an essential nutrient or metabolic product that it cannot provide for itself. Models of how these complementary resources are allocated between partners often assume optimal behavior, but whether mechanisms enabling global control exist in syntrophic systems, and what form they might take, is unknown. Recognizing that growth of plant organs that supply complementary resources, like roots and shoots, can occur autonomously, we present a theory of plant growth in which root-shoot allocation is determined by purely local rules. Each organ uses as much as it can of its locally produced or acquired resource (inorganic nitrogen or photosynthate) and shares only the surplus. Subject to stoichiometric conditions that likely hold for most plants, purely local rules produce the same optimal allocation as would global control, even in a fluctuating environment, with sharing the surplus being the specific mechanism stabilizing syntrophic dynamics. Our local control model contributes a novel approach to plant growth modeling because it assumes a simple mechanism of root:shoot allocation that can be considered a higher-level physiological rule, from which the optimal growth outcome emerges from the system’s dynamics, rather than being built into the model. Moreover, our model is general, in that the mechanism of sharing the surplus can readily be adapted to many obligate syntrophic relationships.
Constraints on microbial communities, decomposition and methane production in deep peat deposits
Authors: Kluber L.A. , Johnston E.R. , Allen S.A. , Hendershot J.N. , Hanson P.J. , Schadt C.W. 
Published: October 2019

AbstractPeatlands play outsized roles in the global carbon cycle. Despite occupying a rather small fraction of the terrestrial biosphere (∼3%), these ecosystems account for roughly one third of the global soil carbon pool. This carbon is largely comprised of undecomposed deposits of plant material (peat) that may be meters thick. The fate of this deep carbon stockpile with ongoing and future climate change is thus of great interest and has large potential to induce positive feedback to climate warming. Recentin situwarming of an ombrotrophic peatland indicated that the deep peat microbial communities and decomposition rates were resistant to elevated temperatures. In this experiment, we sought to understand how nutrient and pH limitations may interact with temperature to limit microbial activity and community composition. Anaerobic microcosms of peat collected from 1.5 to 2 meters in depth were incubated at 6°C and 15°C with elevated pH, nitrogen (NH4Cl), and/or phosphorus (KH2PO4) in a full factorial design. The production of CO2and CH4was significantly greater in microcosms incubated at 15°C, although the structure of the microbial community did not differ between the two temperatures. Increasing the pH from ∼3.5 to ∼5.5 altered microbial community structure, however increases in CH4production were non-significant. Contrary to expectations, N and P additions did not increase CO2and CH4production, indicating that nutrient availability was not a primary constraint in microbial decomposition of deep peat. Our findings indicate that temperature is a key factor limiting the decomposition of deep peat, however other factors such as the availability of O2or alternative electron donors and high concentrations of phenolic compounds, may also exert constraints. Continued experimental peat warming studies will be necessary to assess if the deep peat carbon bank is susceptible to increased temperatures over the longer time scales.
Thickness of deep layers in the fusiform face area predicts face recognition
Authors: McGugin Rankin W. , Newton Allen T. , Tamber-Rosenau Benjamin , Tomarken Andrew , Gauthier Isabel 
Published: October 2019

AbstractPeople with superior face recognition have relatively thin cortex in face-selective brain areas, while those with superior vehicle recognition have relatively thick cortex in the same areas. We suggest that these opposite correlations reflect distinct mechanisms influencing cortical thickness (CT) for abilities acquired at different points in development. We explore a new prediction regarding the specificity of these effects through the depth of the cortex: that face recognition selectively and negatively correlates with thickness of the deepest laminar subdivision in face-selective areas. With ultra-high resolution MRI at 7T, we estimated the thickness of three laminar subdivisions, which we term MR layers, in the right fusiform face area (rFFA) in 14 adult male humans. Face recognition was negatively associated with the thickness of deep MR layers, while vehicle recognition was positively related to the thickness of all layers. Regression model comparisons provided overwhelming support for a model specifying that the magnitude of the association between face recognition and CT differs across MR layers (deep vs. superficial/middle) while the magnitude of the association between vehicle recognition and CT is invariant across layers. The total CT of rFFA accounted for 69% of the variance in face recognition, and thickness of the deep layer alone accounted for 84% of this variance. Our findings demonstrate the functional validity of MR laminar estimates in FFA. Studying the structural basis of individual differences for multiple abilities in the same cortical area can reveal effects of distinct mechanisms that are not apparent when studying average variation or development.Significance StatementFace and object recognition vary in the normal population and are only modestly related to each other. The recognition of faces and vehicles are both positively related to neural responses in the fusiform face area (FFA), but show different relations to the cortical thickness of FFA. Here, we use very high-resolution MRI, and find that face recognition ability (a skill acquired early in life) is negatively correlated with thickness of FFA’s deepest MR-defined layers, whereas recognition of vehicles (a skill acquired later in life) is positively related to thickness at of all cortical layers. Our methods can be used in the future to characterize sources of variability in human abilities and relate them to distinct mechanisms of neural plasticity.
Mapping short-latency cortical responses to electrical stimulation of thalamic motor nuclei by increasing sampling rate - a technical report
Authors: Toth Emilia , Chaitanya Ganne , Pati Sandipan 
Published: October 2019

AbstractDirect electrical stimulation (DES) of the cortex is a clinically indispensable brain mapping technique that provides reliable information about the distribution of eloquent cortex and its connectivity to the white matter bundles. Here we present a technical report on mapping the short latency cortical responses to stimulation of the ventral anterior nucleus of human thalamus. Reliable downstream responses were noted in the regions connected to the ventral anterior nucleus i.e. superior and inferior frontal gyri, supplementary motor area and limbic substructures (cingulate gyrus and hippocampus).
The retinoblastoma tumor suppressor limits ribosomal readthrough during oncogene induced senescence
Authors: del Toro Neylen , Lessard Frédéric , Tardif Sarah , Bouchard Jacob , Bourdeau Véronique , Ferbeyre Gerardo , Brakier-Gingras Léa 
Published: October 2019

AbstractThe origin and evolution of cancer cells is considered to be mainly fueled by mutations affecting the DNA sequence. Although errors in translation could also expand the cellular proteome, their role in cancer biology remains poorly understood. Tumor suppressors called “caretakers” block cancer initiation and progression by preventing DNA mutations and/or stimulating DNA repair. If translational errors contribute to tumorigenesis, then caretakers genes will prevent such errors in normal cells in response to oncogenic stimuli. Here, we show that the retinoblastoma protein (RB) acts as caretaker tumor suppressor by preventing the readthrough of termination codons, a process that allows proteins to be synthetized with additional domains. In particular, we show that expression of oncogenicrasin normal human cells triggers a cellular senescence response characterized by a significant reduction of basal ribosomal readthrough. However, inactivation of the RB tumor suppressor pathway in these cells, using the viral oncoprotein E7 or the oncogenic kinase CDK4 increased readthrough. Conversely, activation of the RB pathway by the tumor suppressor PML, the ribosomal proteins RPS14/uS11 and RPL22/eL22 or the CDK4/6 inhibitor palbociclib reduced readthrough. We thus reveal a novel function for the RB pathway as a caretaker of translational errors with implications for tumor suppression and cancer treatment.
Monitoring G-quadruplex formation with DNA carriers and solid-state nanopores
Authors: Bošković Filip , Zhu Jinbo , Chen Kaikai , Keyser Ulrich F. 
Published: October 2019

ABSTRACTG-quadruplexes (Gq) are guanine-rich DNA structures formed by single-stranded DNA. They are of paramount significance to gene expression regulation, but also drug targets for cancer and human viruses. Current ensemble and single-molecule methods require fluorescent labels, which can affect Gq folding kinetics. Here we introduce, a single-molecule Gq nanopore assay (smGNA) to detect Gqs and kinetics of Gq formation. We use ~5 nm solid-state nanopores to detect various Gq structural variants attached to designed DNA carriers. Gqs can be identified by localizing their positions along designed DNA carriers establishing smGNA as a tool for Gq mapping. In addition, smGNA allows for discrimination of (un-)folded Gq structures, provides insights into single-molecule kinetics of G-quadruplex folding, and probes quadruplex-to-duplex structural transitions. smGNA can elucidate the formation of G-quadruplexes at the single-molecule level without labelling and has potential implications on the study of these structures both in single-stranded DNA and in genomic samples.
Optogenetic control of excitatory post-synaptic differentiation through neuroligin-1 tyrosine phosphorylation
Authors: Letellier Mathieu , Lagardère Matthieu , Tessier Béatrice , Janovjak Harald , Thoumine Olivier 
Published: October 2019

AbstractNeuroligins (Nlgs) are adhesion proteins mediating trans-synaptic contacts in neurons. However, conflicting results around their role in synaptic differentiation arise from the various techniques used to manipulate Nlg expression. Orthogonally to these approaches, we triggered here the phosphorylation of endogenous Nlg1 in CA1 hippocampal neurons using a photoactivatable tyrosine kinase receptor (optoFGFR1). Light stimulation for 24 h selectively increased dendritic spine density and AMPA receptor-mediated EPSCs in wild-type neurons, but not in Nlg1 knock-out neurons or when endogenous Nlg1 was replaced by a non-phosphorylatable mutant (Y782F). Moreover, light stimulation of optoFGFR1 partially occluded LTP. Combined with computer simulations, our data support a model by which Nlg1 tyrosine phosphorylation promotes the assembly of an excitatory post-synaptic scaffold that captures surface AMPA receptors. This optogenetic strategy thus highlights the impact of Nlg1 intracellular signaling in synaptic differentiation and potentiation, while enabling an acute control of these mechanisms.Impact StatementOrthogonal to the traditional paradigms used to manipulate neuroligin expression level, the optogenetic trigger of tyrosine phosphorylation supports a strong role of endogenous neuroligin-1 in excitatory synaptic differentiation and potentiation.
Dynamic Clonal Hematopoiesis and Functional T-cell Immunity in a Super-centenarian
Authors: van den Akker Erik B. , Makrodimitris Stavros , Hulsman Marc , Brugman Martijn H. , Nikolic Tanja , Bradley Ted , Waisfisz Quinten , Baas Frank , Jakobs Marja E. , de Jong Daphne , Slagboom P. Eline , Staal Frank J.T. , Reinders Marcel J.T. , Holstege Henne 
Published: October 2019

AbstractThe aged hematopoietic system is characterized by decreased immuno-competence and by a reduced number of hematopoietic stem cells (HSCs) that actively generates new blood cell (age-related clonal hematopoiesis, ARCH). While both aspects are commonly associated with an increased risk of aging-related diseases, it is currently unknown to what extent these aspects co-occur during exceptional longevity. Here, we investigated these aspects in blood cells of an immuno-hematopoietically normal female who reached 111 years. Blood samples were collected across a 9-year period at ages 103, 110 and 111 years. We applied several genetic sequencing approaches to investigate clonality in peripheral blood samples and sorted cell subsets. Immuno-competence was characterized using flow cytometry, T-cell receptor excision circle (TREC) assays, and in vitro proliferation assays. We identified a single DNMT3A-mutated HSC clone with a complex subclonal architecture and observed ongoing subclonal dynamics within the 9-year timeframe of our sampling. The mutated HSC generated 78-87% myeloid cells, 6-7% of the B-cells, 6% of CD8+ T-cells, and notably 22% of the CD4+ T-cells. Intriguingly, we found that T-cells were capable of robust proliferation when challenged in vitro. Moreover, we observed a surprisingly high TREC content, indicative of recent generation of naive T-cells. Concluding, we observed long-term stability of extreme ARCH with ongoing clonal dynamics combined with functional T-cell immunity. Our results indicate that extreme ARCH does not compromise immuno-competence and that a clonally expanded CD4+ T-cell subset may serve as a potential hallmark of the supercentenarian immune system.Key pointsLongitudinal blood sampling from a female aged 103-111 revealed a dynamic clonal hematopoiesis contributing to myeloid and lymphoid subsetsDespite the highly advanced age and extreme clonal hematopoiesis we observed functional T-cell immunity
3D Printed Microheater Sensor-Integrated, Drug-Encapsulated Microneedle Patch System for Pain Management
Authors: Yin Mengtian , Xiao Li , Liu Qingchang , Kwon Sung-Yun , Zhang Yi , Sharma Poonam R , Jin Li , Li Xudong , Xu Baoxing 
Published: October 2019

AbstractMicroneedle patch device has been widely utilized for transdermal drug delivery in pain management, but is challenged by accurate control of drug release and subsequent diffusion to human body. The recent emerging wearable electronics that could be integrated with microneedle devices offers a facile approach to address such a challenge. Here a 3D printed microheater integrated drug-encapsulated microneedle patch system for drug delivery is presented. The ink solution comprised of polydimethylsiloxane (PDMS) and multiwalled carbon nanotubes (MWCNTs) with mass concentration of up to 45% is prepared and used to print crack-free stretchable microheaters on substrates with a broad range of materials and geometric curves. The adhesion strength of printed microheater on microneedle patch in elevated temperatures are measured to evaluate their integration performance. Assessments of encapsulated drug release into rat’s skin are confirmed by examining degradation of microneedles, skin morphologies, and released fluorescent signals. Results and demonstrations established here creates a new opportunity for developing sensor controlled smart microneedle patch systems by integrating with wearable electronics, potentially useful in clinic and biomedical research.
Motorized shoes induce robust sensorimotor adaptation in walking
Authors: Aucie Yashar , Zhang Xunjie , Sargent Randy , Torres-Oviedo Gelsy 
Published: October 2019

AbstractThe motor system has the flexibility to update motor plans according to systematic changes in the environment or the body. This capacity is studied in the laboratory through sensorimotor adaptation paradigms imposing sustained and predictable motor demands specific to the task at hand. However, these studies are tied to the laboratory setting. Thus, we asked if a portable device could be used to elicit locomotor adaptation outside the laboratory. To this end we tested the extent to which a pair of motorized shoes could induce similar locomotor adaptation to split-belt walking, which is a well-established sensorimotor adaptation paradigm in locomotion. We specifically compared two groups of young, healthy subjects adapted on the treadmill by moving their feet at different speeds with a split-belt treadmill or with a pair of motorized shoes. We found that the adaptation of joint motions and measures of spatial and temporal asymmetry, which are commonly used to quantify sensorimotor adaptation in locomotion, were indistinguishable between groups. We only found small differences in the join angle kinematics during baseline walking between the groups-potentially due to the relatively large weight and height of the motorized shoes. Our results indicate that robust sensorimotor adaptation in walking can be induced with a paired of motorized shoes, opening the exciting possibility to study sensorimotor adaptation during more realistic situations outside the laboratory.
The microbiomes of seven lichen genera reveal host specificity, a reduced core community and potential as source of antimicrobials
Authors: Sierra Maria A , Danko David C , Sandoval Tito A , Pishchany Gleb , Moncada Bibiana , Kolter Roberto , Mason Christopher E. , Zambrano Maria Mercedes 
Published: October 2019

AbstractThe High Andean Paramo ecosystem is a unique neotropical mountain biome considered a diversity and evolutionary hotspot. Lichens, which are complex symbiotic structures that contain diverse commensal microbial communities, are prevalent in Paramos. There they play vital roles in soil formation and mineral fixation. In this study we analyzed the microbiomes of seven lichen genera in two Colombian Paramos using 16S rRNA gene analyses and provide the first description of the bacterial communities associated with Cora and Hypotrachyna lichens. Paramo lichen microbiomes were diverse, and in some cases were distinguished based on the identity of the lichen host. The majority of the lichen-associated microorganisms were not present in all lichens sampled and could be considered transient or specialists. We also uncovered sixteen shared taxa that suggest a core lichen microbiome among this diverse group of lichens, broadening our concept of these symbiotic structures. Additionally, we identified strains producing compounds active against clinically relevant pathogens. These results indicate that lichen microbiomes from the Paramo ecosystem are diverse and host-specific but share a taxonomic core and can be a source of new bacterial taxa and antimicrobials.
Human blood exposure toClostridium perfringensepsilon toxin may shed light on erythrocyte fragility during active multiple sclerosis
Authors: Rashid Rumah K. , Eleso Olawale E. , Fischetti Vincent A. 
Published: October 2019

ABSTRACTDuring active multiple sclerosis (MS), red blood cells (RBCs) harvested from patients reportedly display increased osmotic fragility and increased cellular volume (macrocytosis). The cause of these abnormalities remains unknown. We have previously proposed thatClostridium perfringensepsilon toxin (ETX) may be a blood-borne trigger for newly forming MS lesions based on its tropism for blood-brain barrier vasculature and CNS myelin. Recently, Gao et al. have reported that ETX binds to and damages human RBCs, leading to hemolysis. Moreover, the authors suggest that purinergic nucleotide (P2) receptor activation amplifies the hemolytic process. Here, we confirm that ETX indeed causes human-specific RBC lysis. However, our data suggest that the hemolytic process is mediated by metal-catalyzed oxidation of the swell-induced, nucleotide-sensitive ICln chloride channel. We use spectrophotometry, flow cytometry and Western blotting to show that ETX targets human RBCs and T lymphocytes via their shared expression of Myelin and Lymphocyte protein (MAL); a protein shown to be both necessary and sufficient for ETX binding and toxicity. ETX likely triggers T cells to release redox-active heavy metals, Cu+and Fe3+, via the lysosomal exocytosis pathway, while RBCs likely release these heavy metals via ETX pore formation within the RBC membrane. Extracellular Cu+and Fe3+may then amplify hemolysis by oxidizing a previously identified heavy metal-binding site within the ICln channel pore, thus deregulating its normal conductance. Elucidating the precise mechanism of ETX-mediated hemolysis may shed light on the underlying etiology of MS, as it would explain why MS RBC abnormalities occur during active disease.IMPORTANCEDuring active MS, numerous reports suggest that circulating RBCs are larger than normal and fragment more easily. The exact trigger(s) for these RBC abnormalities and for newly forming MS lesions remains unidentified. We have proposed that ETX, secreted by the gut bacteriumClostridium perfringens, may be an environmental trigger for newly forming MS lesions. Indeed, ETX has been shown to breakdown the BBB, enter the brain and damage the myelin sheath. Because ETX is typically spread through the circulatory system, we wished to determine how the toxin affects human blood. Provocatively, there has been a recent report that ETX produces cellular abnormalities in human RBCs, reminiscent of what has been described during active MS. In our study, we sought to elucidate the precise mechanism for how ETX causes RBC damage. In addition to triggering BBB breakdown and CNS demyelination, ETX might also explain why RBCs appear abnormal during MS attacks.
Feeding status influences adult vine weevil (coleoptera: curculionidae) behaviour to conspecific volatiles
Authors: Roberts Joe M. , Kundun Jhaman , Pope Tom W. 
Published: October 2019

ABSTRACTVine weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), is widely considered to be one of the most economically important pests of soft-fruit and ornamental crops. The chemical ecology of vine weevil has been extensively studied in the pursuit of a semiochemical lure to improve monitoring tool sensitivity/reliability and develop novel control methods. Although vine weevil adults exhibit a strong tendency to aggregate, the mechanism underlying this behaviour has not, to date, been identified. It is notable, however, that previous studies have not considered the impact of feeding status on vine weevil aggregation behaviour. To investigate the importance of feeding status on aggregation behavior, this study recorded the responses of satiated and starved vine weevil adults to the odour of starved conspecifics. Satiated adults exhibited a preference for the odour of conspecifics while starved vine weevils exhibited no such preference. Therefore, this study provides evidence to support the hypothesis that feeding status is an important factor for vine weevil aggregation.