bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distinct Top-down and Bottom-up Brain Connectivity During Visual Perception and Imagery
Authors: Dijkstra N. , Zeidman P. , Ondobaka S. , van Gerven M. A. J. , Friston K. 
Published: July 2017

AbstractResearch suggests that perception and imagination engage neuronal representations in the same visual areas. However, the underlying mechanisms that differentiate sensory perception from imagination remain unclear. Here, we examine the directed coupling (effective connectivity) between fronto-parietal and visual areas during perception and imagery. We found an increase in bottom-up coupling during perception relative to baseline and an increase in top-down coupling during both perception and imagery, with a much stronger increase during imagery. Modulation of the coupling from frontal to early visual areas was common to both perception and imagery. Furthermore, we show that the experienced vividness during imagery was selectively associated with increases in top-down connectivity to early visual cortex. These results highlight the importance of top-down processing in internally as well as externally driven visual experience.
Deep-ocean dissolved organic matter reactivity along the Mediterranean Sea: does size matter?
Authors: Martínez-Pérez Alba María , Álvarez-Salgado Xosé Antón , Arístegui Javier , Nieto-Cid Mar 
Published: July 2017

AbstractDespite of the major role ascribed to marine dissolved organic matter (DOM) in the global carbon cycle, the reactivity of this pool in the dark ocean is still poorly understood. Present hypotheses, posed within the size-reactivity continuum (SRC) and the microbial carbon pump (MCP) conceptual frameworks, need further empirical support. Here, we provide field evidence of the soundness of the SRC model. We sampled the high salinity core-of-flow of the Levantine Intermediate Water along its westward route through the entire Mediterranean Sea. At selected sites, DOM was size-fractionated in apparent high (aHMW) and low (aLMW) molecular weight fractions using an efficient ultrafiltration cell. A percentage decline of the aHMW DOM from 68–76% to 40–55% was observed from the Levantine Sea to the Strait of Gibraltar in parallel with increasing apparent oxygen utilization (AOU). DOM mineralization accounted for 30 ± 3% of the AOU, being the aHMW fraction solely responsible for this consumption, verifying the SRC model in the field. We also demonstrate that, in parallel to this aHMW DOM consumption, fluorescent humic-like substances accumulate in both fractions and protein-like substances decline in the aLMW fraction, thus indicating that not only size matters and providing field support to the MCP model.
Olfactory bulb plasticity ensures proper olfaction after severe impairment in postnatal neurogenesis
Authors: Díaz D. , Muñoz-Castañeda R. , Ávila-Zarza C. , Carretero J. , Alonso J. R. , Weruaga E. 
Published: July 2017

AbstractThe olfactory bulb (OB) neurons establish a complex network that ensures the correct processing of the olfactory inputs. Moreover, the OB presents a lifelong addition of new neurons into its existing circuitry. This neurogenesis is considered essential for the OB function. However, its functional impact on physiology and behavior is still unclear. Here, we investigate the mechanisms of OB plasticity that underlie bulbar physiology in relation to severe damage of neurogenesis. The neurogenesis of young mice was altered by ionizing radiation. Afterwards, both multi-channel olfactometry and electrophysiological studies were performed. Furthermore, neurogenesis and differentiation of the newly formed cells were assessed using bromodeoxyuridine labeling combined with a wide battery of neuronal markers. Our results demonstrate a reduction in both neurogenesis and volume of the OB in irradiated animals. The number of neuroblasts reaching the OB was reduced and their differentiation rate into interneurons selectively changed; some populations were noticeably affected whereas others remained preserved. Surprisingly, both olfactory detection and discrimination as well as electrophysiology presented almost no alterations in irradiated mice. Our findings suggest that after damaging postnatal neurogenesis, the neurochemical fate of some interneurons changes within a new biological scenario, while maintaining homeostasis and olfaction.
Microbial turnover times in the deep seabed studied by amino acid racemization modelling
Authors: Braun Stefan , Mhatre Snehit S. , Jaussi Marion , Røy Hans , Kjeldsen Kasper U. , Pearce Christof , Seidenkrantz Marit-Solveig , Jørgensen Bo Barker , Lomstein Bente Aa. 
Published: July 2017

AbstractThe study of active microbial populations in deep, energy-limited marine sediments has extended our knowledge of the limits of life on Earth. Typically, microbial activity in the deep biosphere is calculated by transport-reaction modelling of pore water solutes or from experimental measurements involving radiotracers. Here we modelled microbial activity from the degree of D:L-aspartic acid racemization in microbial necromass (remains of dead microbial biomass) in sediments up to ten million years old. This recently developed approach (D:L-amino acid modelling) does not require incubation experiments and is highly sensitive in stable, low-activity environments. We applied for the first time newly established constraints on several important input parameters of the D:L-amino acid model, such as a higher aspartic acid racemization rate constant and a lower cell-specific carbon content of sub-seafloor microorganisms. Our model results show that the pool of necromass amino acids is turned over by microbial activity every few thousand years, while the turnover times of vegetative cells are in the order of years to decades. Notably, microbial turnover times in million-year-old sediment from the Peru Margin are up to 100-fold shorter than previous estimates, highlighting the influence of microbial activities on element cycling over geologic time scales.
Small chaperons and autophagy protected neurons from necrotic cell death
Authors: Lei Ye , Liu Kai , Hou Lin , Ding Lianggong , Li Yuhong , Liu Lei 
Published: July 2017

AbstractNeuronal necrosis occurs during early phase of ischemic insult. However, our knowledge of neuronal necrosis is still inadequate. To study the mechanism of neuronal necrosis, we previously established a Drosophila genetic model of neuronal necrosis by calcium overloading through expression of a constitutively opened cation channel mutant. Here, we performed further genetic screens and identified a suppressor of neuronal necrosis, CG17259, which encodes a seryl-tRNA synthetase. We found that loss-of-function (LOF) CG17259 activated eIF2α phosphorylation and subsequent up-regulation of chaperons (Hsp26 and Hsp27) and autophagy. Genetically, down-regulation of eIF2α phosphorylation, Hsp26/Hsp27 or autophagy reduced the protective effect of LOF CG17259, indicating they function downstream of CG17259. The protective effect of these protein degradation pathways indicated activation of a toxic protein during neuronal necrosis. Our data indicated that p53 was likely one such protein, because p53 was accumulated in the necrotic neurons and down-regulation of p53 rescued necrosis. In the SH-SY5Y human cells, tunicamycin (TM), a PERK activator, promoted transcription of hsp27; and necrosis induced by glutamate could be rescued by TM, associated with reduced p53 accumulation. In an ischemic stroke model in rats, p53 protein was also increased, and TM treatment could reduce the p53 accumulation and brain damage.
Graphene microfiber as a scaffold for regulation of neural stem cells differentiation
Authors: Guo Weibo , Qiu Jichuan , Liu Jingquan , Liu Hong 
Published: July 2017

AbstractWe report the cytocompatibility and regulating effects of the nanostructured reduced graphene oxide (rGO) microfibers, which are synthesized through a capillary hydrothermal method, on neural differentiation of neural stem cells (NSCs). Our findings indicate that the flexible, mechanically strong, surface nanoporous, biodegradable, and cytocompatible nanostructured rGO microfibers not only offer a more powerful substrate for NSCs adhesion and proliferation compared with 2D graphene film and tissue cluture plate but also regulate the NSCs differentiation into neurons and form a dense neural network surrounding the microfiber. These results illustrate the great potential of nanostructured rGO microfibers as an artificial neural tissue engineering (NTE) scaffold for nerve regeneration.
Bulk vs. Surface Structure of 3d Metal Impurities in Topological Insulator Bi2Te3
Authors: Leedahl B. , Boukhvalov D. W. , Kurmaev E. Z. , Kukharenko A. , Zhidkov I. S. , Gavrilov N. V. , Cholakh S. O. , Le P. Huu , Luo C. Wei , Moewes A. 
Published: July 2017

AbstractTopological insulators have become one of the most prominent research topics in materials science in recent years. Specifically, Bi2Te3 is one of the most promising for technological applications due to its conductive surface states and insulating bulk properties. Herein, we contrast the bulk and surface structural environments of dopant ions Cr, Mn, Fe, Co, Ni, and Cu in Bi2Te3 thin films in order to further elucidate this compound. Our measurements show the preferred oxidation state and surrounding crystal environment of each 3d-metal atomic species, and how they are incorporated into Bi2Te3. We show that in each case there is a unique interplay between structural environments, and that it is highly dependant on the dopant atom. Mn impurities in Bi2Te3 purely substitute into Bi sites in a 2+ oxidation state. Cr atoms seem only to reside on the surface and are effectively not able to be absorbed into the bulk. Whereas for Co and Ni, an array of substitutional, interstitial, and metallic configurations occur. Considering the relatively heavy Cu atoms, metallic clusters are highly favourable. The situation with Fe is even more complex, displaying a mix of oxidation states that differ greatly between the surface and bulk environments.
Structural and rheological properties conferring fertilization competence to Xenopus egg-coating envelope
Authors: Hanaue Mayu , Miwa Naofumi 
Published: July 2017

AbstractThe extracellular egg-coating envelope that comprises a meshwork of filaments polymerized by glycoproteins plays a pivotal role in species-selective sperm recognition and subsequent fertilization; however, the structural and rheological properties conferring fertilization competence to the egg-coating envelope remain poorly unveiled. Here we show several nanoscale-structural and viscoelastic properties of the egg-coat using the transmission electron microscopy and the quartz crystal microbalance experiments, following clamp of the egg-coat at either fertilization-competent or -incompetent statuses by short-term pretreatment with synthetic peptides. Individual filament of approximately 4.8 nm diameter crossed one another, forming several types of intersections. Higher competence-inducing treatment changed the proportion of V-, Y-, and T-type intersections, and induced more randomly deflected angles at intersections. Incompetence-inducing treatment increased the median of a Gaussian distribution of filament lengths that had a peak of 10–20 nm under control conditions; furthermore, this treatment created bumps in the 30–40 and 50–60 nm windows. Quartz crystal microbalance study revealed that viscoelasticity of the competent VE suspension was lower than that of incompetent VE, indicating that viscoelastic property required for successful fertilization resides within a specific range. These findings indicated that the architecture of the egg-coat is capable of rapid and dynamic remodeling, which determines fertilization efficiency.
Dissonance encoding in human inferior colliculus covaries with individual differences in dislike of dissonant music
Authors: Kim Seung-Goo , Lepsien Jöran , Fritz Thomas Hans , Mildner Toralf , Mueller Karsten 
Published: July 2017

AbstractHarmony is one of the most fundamental elements of music that evokes emotional response. The inferior colliculus (IC) has been known to detect poor agreement of harmonics of sound, that is, dissonance. Electrophysiological evidence has implicated a relationship between a sustained auditory response mainly from the brainstem and unpleasant emotion induced by dissonant harmony. Interestingly, an individual’s dislike of dissonant harmony of an individual correlated with a reduced sustained auditory response. In the current paper, we report novel evidence based on functional magnetic resonance imaging (fMRI) for such a relationship between individual variability in dislike of dissonance and the IC activation. Furthermore, for the first time, we show how dissonant harmony modulates functional connectivity of the IC and its association with behaviourally reported unpleasantness. The current findings support important contributions of low level auditory processing and corticofugal interaction in musical harmony preference.
Commensal Gut Microbiota Immunomodulatory Actions in Bone Marrow and Liver have Catabolic Effects on Skeletal Homeostasis in Health
Authors: Novince Chad M. , Whittow Carolyn R. , Aartun Johannes D. , Hathaway Jessica D. , Poulides Nicole , Chavez Michael B. , Steinkamp Heidi M. , Kirkwood Kaeleigh A. , Huang Emily , Westwater Caroline , Kirkwood Keith L. 
Published: July 2017

AbstractDespite knowledge the gut microbiota regulates bone mass, mechanisms governing the normal gut microbiota’s osteoimmunomodulatory effects on skeletal remodeling and homeostasis are unclear in the healthy adult skeleton. Young adult specific-pathogen-free and germ-free mice were used to delineate the commensal microbiota’s immunoregulatory effects on osteoblastogenesis, osteoclastogenesis, marrow T-cell hematopoiesis, and extra-skeletal endocrine organ function. We report the commensal microbiota has anti-anabolic effects suppressing osteoblastogenesis and pro-catabolic effects enhancing osteoclastogenesis, which drive bone loss in health. Suppression of Sp7(Osterix) and Igf1 in bone, and serum IGF1, in specific-pathogen-free mice suggest the commensal microbiota’s anti-osteoblastic actions are mediated via local disruption of IGF1-signaling. Differences in the RANKL/OPG Axis in vivo, and RANKL-induced maturation of osteoclast-precursors in vitro, indicate the commensal microbiota induces sustained changes in RANKL-mediated osteoclastogenesis. Candidate mechanisms mediating commensal microbiota’s pro-osteoclastic actions include altered marrow effector CD4+T-cells and a novel Gut-Liver-Bone Axis. The previously unidentified Gut-Liver-Bone Axis intriguingly implies the normal gut microbiota’s osteoimmunomodulatory actions are partly mediated via immunostimulatory effects in the liver. The molecular underpinnings defining commensal gut microbiota immunomodulatory actions on physiologic bone remodeling are highly relevant in advancing the understanding of normal osteoimmunological processes, having implications for the prevention of skeletal deterioration in health and disease.
Universal mechanism for hybrid percolation transitions
Authors: Lee Deokjae , Choi Wonjun , Kertész J. , Kahng B. 
Published: July 2017

AbstractHybrid percolation transitions (HPTs) induced by cascading processes have been observed in diverse complex systems such as k-core percolation, breakdown on interdependent networks and cooperative epidemic spreading models. Here we present the microscopic universal mechanism underlying those HPTs. We show that the discontinuity in the order parameter results from two steps: a durable critical branching (CB) and an explosive, supercritical (SC) process, the latter resulting from large loops inevitably present in finite size samples. In a random network of N nodes at the transition the CB process persists for O(N1/3) time and the remaining nodes become vulnerable, which are then activated in the short SC process. This crossover mechanism and scaling behavior are universal for different HPT systems. Our result implies that the crossover time O(N1/3) is a golden time, during which one needs to take actions to control and prevent the formation of a macroscopic cascade, e.g., a pandemic outbreak.
Melatonin promotes osteoblast differentiation by regulating Osterix protein stability and expression
Authors: Han Younho , Kim Young-Mi , Kim Hyung Sik , Lee Kwang Youl 
Published: July 2017

AbstractAlthough the biological role of melatonin in osteogenic differentiation has been suggested, the mechanism of osteoblast differentiation remains unclear. Thus, the present study investigated the underlying molecular mechanisms based on osteoblast-specific transcription factors. We found that melatonin enhanced BMP-4-induced osteogenic differentiation and increased the expression of osteogenic markers, especially Osterix, which is an essential transcription factor for the differentiation of preosteoblasts into mature osteoblasts in the late stage of osteoblast differentiation. Melatonin treatment increased the expression of Osterix during osteoblast differentiation and stabilized its expression by the inhibition of ubiquitin-proteasome-mediated degradation of Osterix, leading to up-regulated Osterix transcriptional activity on the osteogenic promoter and promoting alkaline phosphatase activity and bone mineralization. Furthermore, treatment with protein kinase A (PKA) inhibitor H89 and protein kinase C (PKC) inhibitor Go6976 blocked the melatonin-induced transcriptional activity and phosphorylation of Osterix, indicating that melatonin regulates Osterix expression via the PKA and PKC signaling pathways. Overall, these findings suggest that melatonin directly regulates the late stage of osteoblast differentiation by enhancing Osterix expression; this provides further evidence of melatonin as a potent agent for treating osteoporosis.
Neuroprotective effect of 5-aminolevulinic acid against low inorganic phosphate in neuroblastoma SH-SY5Y cells
Authors: Takase Naoko , Inden Masatoshi , Sekine Shin-ichiro , Ishii Yumi , Yonemitsu Hiroko , Iwashita Wakana , Kurita Hisaka , Taketani Yutaka , Hozumi Isao 
Published: July 2017

AbstractPiT-1 (encoded by SLC20A1) and PiT-2 (encoded by SLC20A2) are type-III sodium-dependent phosphate cotransporters (NaPiTs). Recently, SLC20A2 mutations have been found in patients with idiopathic basal ganglia calcification (IBGC), and were predicted to bring about an inability to transport Pi from the extracellular environment. Here we investigated the effect of low Pi loading on the human neuroblastoma SH-SY5Y and the human glioblastoma A172 cell lines. The results show a different sensitivity to low Pi loading and differential regulation of type-III NaPiTs in these cells. We also examined whether 5-aminolevulinic acid (5-ALA) inhibited low Pi loading-induced neurotoxicity in SH-SY5Y cells. Concomitant application of 5-ALA with low Pi loading markedly attenuated low Pi-induced cell death and mitochondrial dysfunction via the induction of HO-1 by p38 MAPK. The findings provide us with novel viewpoints to understand the pathophysiology of IBGC, and give a new insight into the clinical prevention and treatment of IBGC.
Interaction between trait and housing condition produces differential decision-making toward risk choice in a rat gambling task
Authors: Kim Wha Young , Cho Bo Ram , Kwak Myung Ji , Kim Jeong-Hoon 
Published: July 2017

AbstractPoor decision-making is a core problem in psychiatric disorders such as pathological gambling and substance abuse. Both trait and environmental factors are considerably important to affect decision-making. However, it has not yet been systematically shown how they interact to affect risk preference in animal models evaluating decision-making. Here, we trained rats, housed in pairs or in isolation, in a touch screen chamber to detect the association between four different light signals on the screen and accompanied reward and punishment outcomes arranged with different schedules. Then, the rats were allowed to freely choose from 4 different light signals. Once animals showed a stabilized pattern of preference (risk-averse or risk-seeking), they were injected with saline or cocaine (a single injection per day for 7 days) followed by 2 weeks of withdrawal. Then, their preference of choice was re-tested in the touch screen chamber while they were cocaine challenged. All rats significantly changed their preference toward more risky choices when they were exposed to and challenged with cocaine, except those in the risk-averse/isolated housing group. These results indicate that the pre-existing trait toward risk and the housing condition interact to affect the quality of decision-making, and cocaine may help to aggravate this process.
Morphological and functional maturity of the oral jaws covary with offspring size in Trinidadian guppies
Authors: Dial T. R. , Hernandez L. P. , Brainerd E. L. 
Published: July 2017

AbstractLarge size of individual offspring is routinely selected for in highly competitive environments, such as in low-predation populations of the Trinidadian guppy (Poecilia reticulata). Large guppy offspring outcompete their smaller conspecifics, but the functional mechanisms underlying this advantage are unknown. We measured jaw kinematics during benthic feeding and cranial musculoskeletal morphologies in neonates and juveniles from five populations of Trinidadian guppy and found that both kinematics and morphologies vary substantially with neonatal size. Rotation at the intramandibular joint (IMJ), but not the quadratomandibular joint (QMJ), increases with size among guppy offspring, from 11.7° in the smallest neonates to 22.9° in the largest neonates. Ossification of the cranial skeleton varies from 20% in the smallest neonates to 90% in the largest. Relative to standard length (SL; jaw tip to caudal fin base distance), the surface area of jaw-closing musculature scales with positive allometry (SL2.72) indicating that muscle growth outpaces body growth. Maximum gape also scales with positive allometry (SL1.20), indicating that larger neonates are capable of greater jaw excursions. These findings indicate that size is not the sole adaptive benefit to producing larger offspring; maturation provides a potential functional mechanism underlying the competitive advantage of large offspring size among Trinidadian guppies.
Dysregulated miRNAs and their pathogenic implications for the neurometabolic disease propionic acidemia
Authors: Rivera-Barahona Ana , Fulgencio-Covián Alejandro , Pérez-Cerdá Celia , Ramos Ricardo , Barry Michael A. , Ugarte Magdalena , Pérez Belén , Richard Eva , Desviat Lourdes R 
Published: July 2017

AbstractmiRNome expression profiling was performed in a mouse model of propionic acidemia (PA) and in patients’ plasma samples to investigate the role of miRNAs in the pathophysiology of the disease and to identify novel biomarkers and therapeutic targets. PA is a potentially lethal neurometabolic disease with patients developing neurological deficits and cardiomyopathy in the long-term, among other complications. In the PA mouse liver we identified 14 significantly dysregulated miRNAs. Three selected miRNAs, miR-34a-5p, miR-338-3p and miR-350, were found upregulated in brain and heart tissues. Predicted targets involved in apoptosis, stress-signaling and mitochondrial function, were inversely found down-regulated. Functional analysis with miRNA mimics in cellular models confirmed these findings. miRNA profiling in plasma samples from neonatal PA patients and age-matched control individuals identified a set of differentially expressed miRNAs, several were coincident with those identified in the PA mouse, among them miR-34a-5p and miR-338-3p. These two miRNAs were also found dysregulated in childhood and adult PA patients’ cohorts. Taken together, the results reveal miRNA signatures in PA useful to identify potential biomarkers, to refine the understanding of the molecular mechanisms of this rare disease and, eventually, to improve the management of patients.