bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resource availability and disturbance shape maximum tree height across the Amazon
Authors: Gorgens Eric , Nunes Matheus Henrique , Jackson Tobias , Coomes David , Keller Michael , Reis Cristiano Rodrigues , Valbuena Rubén , Rosette Jacqueline , de Almeida Danilo Roberti Alves , Gimenez Bruno , Cantinho Roberta , Motta Alline Zagnolli , Assis Mauro , de Souza Pereira Francisca Rocha , Spanner Gustavo , Higuchi Niro , Ometto Jean Pierre 
Published: May 2020

AbstractThe factors shaping the distribution of giant tropical trees are poorly understood, despite its importance as a link between evolutionary biology and ecosystem biogeochemistry. The recent discovery of clusters of trees over 80 metres tall in the Guiana Shield region of the Amazon rainforest challenges the current understanding of the factors controlling the growth and survival of giant trees. The new discovery led us to revisit the question: what determines the distribution of the tallest trees of the Amazon?Here, we used high-resolution airborne LiDAR (Light Detection and Ranging) surveys to measure canopy height across 282,750 ha of primary old-growth and secondary forests throughout the entire Brazilian Amazon to investigate the relationship between the occurrence of giant trees and the environmental factors that influence their growth and survival. Our results suggest that the factors controlling where trees grow extremely tall are distinct from those controlling their longevity. Trees grow taller in areas with high soil clay content (> 42%), lower radiation (< 130 clear days per year) and wind speeds, avoiding alluvial areas (elevations higher than 40 m a.s.l), and with an optimal precipitation range of 1,500 to 2,500 mm yr-1. We then used an envelope model to determine the environmental conditions that support the very tallest trees (i.e. over 70 m height). We found that, as opposed to the myriad of interacting factors that control the maximum height at a large scale, wind speed had by far the largest influence on the distribution of these sentinel trees, and explained 67% of the probability of finding trees over 70 m in the Brazilian Amazon forest.The high-resolution pan-Amazon LiDAR data showed that environmental variables that drive growth in height are fundamentally different from environmental variables that support their survival. While precipitation and temperature seem to have lower importance for their survival than expected from previous studies, changes in wind and radiation regimes could reshape our forested biomes. This should be carefully considered by policy-makers when identifying important hotspots for the conservation of biodiversity in the Amazon.
A characterization of the electrophysiological, morphological and input domains of vasoactive intestinal peptide (VIP) interneurons in the medial entorhinal cortex (MEC)
Authors: Badrinarayanan Saishree , Manseau Frédéric , Lim Byung Kook , Williams Sylvain , Brandon Mark P. 
Published: May 2020

AbstractCircuit interactions within the medial entorhinal cortex (MEC) translate movement into a coherent code for spatial location. Entorhinal principal cells are subject to strong lateral inhibition, suggesting that a disinhibitory mechanism may drive their activation. Cortical Vasoactive Intestinal Peptide (VIP) expressing inhibitory neurons predominantly contact interneurons, providing a local disinhibitory mechanism. Here, we investigate the electrophysiological and morphological properties of VIP cells usingin vitrowhole-cell patch clamp recordings and use rabies-mediated circuit tracing to discover long-range inputs that may modulate this population in mice. We report physiological and morphological properties of VIP cells that differ across lamina and along the dorsal-ventral MEC axis. Furthermore, we reveal long-range inputs to VIP neurons from regions known to encode proprioceptive and auditory information, including the mesencephalic trigeminal nucleus and superior para-olivary nuclei, respectively. These results characterize the properties of VIP cells and reveal sensory modalities that could drive disinhibition in the MEC.
Mechano-regulation of bone adaptation is controlled by the localin vivoenvironment and logarithmically dependent on loading frequency
Authors: Scheuren Ariane C. , Vallaster Paul , Kuhn Gisela A. , Paul Graeme R. , Malhotra Angad , Kameo Yoshitaka , Müller Ralph 
Published: May 2020

AbstractIt is well established that cyclic, but not static, mechanical loading has anabolic effects on bone. However, the function describing the relationship between the loading frequency and the amount of bone adaptation remains unclear. Using a combined experimental and computational approach, this study aimed to investigate whether bone mechano-regulation is controlled by mechanical signals in the localin vivoenvironment and dependent on loading frequency. Specifically, by combiningin vivomicro-computed tomography (micro-CT) imaging with micro-finite element (micro-FE) analysis, we monitored the changes in microstructural as well as the mechanicalin vivoenvironment (strain energy density (SED) and SED gradient) of mouse caudal vertebrae over 4 weeks of either cyclic loading at varying frequencies of 2Hz, 5Hz, or 10Hz, respectively or static loading. Higher values of SED and SED gradient on the local tissue level led to an increased probability of bone formation and a decreased probability of bone resorption. In all loading groups, the SED gradient was superior in the determination of local bone formation and resorption events as compared to SED. Cyclic loading induced positive net remodeling rates when compared to sham and static loading, mainly due to an increase in mineralizing surface and a decrease in eroded surface. Consequently, bone volume fraction increased over time in 2Hz, 5Hz and 10Hz (+15%, +21% and +24%, p<0.0001), while static loading led to a decrease in bone volume fraction (−9%, p≤0.001). Furthermore, regression analysis revealed a logarithmic relationship between loading frequency and the net change in bone volume fraction over the four week observation period (R2=0.74). In conclusion, these results suggest that bone adaptation is regulated by mechanical signals in the localin vivoenvironment and furthermore, that mechano-regulation is logarithmically dependent on loading frequency with frequencies below a certain threshold having catabolic effects, and those above anabolic effects. This study thereby provides valuable insights towards a better understanding of the mechanical signals influencing bone formation and resorption in the localin vivoenvironment.
The demographic buffering strategy has a threshold of effectiveness to increases in environmental stochasticity
Authors: Rodríguez-Caro R.C. , Capdevila P. , Graciá E. , Barbosa J. M. , Giménez A. , Salguero-Gómez R. 
Published: May 2020

AbstractAnimal populations have developed multiple strategies to deal with environmental change. Among them, the demographic buffering strategy consists on constraining the temporal variation of the vital rate(s) (e.g., survival, growth, reproduction) that most affect(s) the overall performance of the population. Given the increase in environmental stochasticity of the current global change scenario, identifying the thresholds beyond which populations are not able to remain viable -despite their potential buffering strategies- is of utmost importance.Tortoises are known to buffer the temporal variation in survival (i.e.this vital rate has the highest contribution to the population growth rateλ) at the expense of a high variability on reproductive rates (lowest contribution toλ). To identify the potential threshold in buffering ability, here we use field data collected across a decade on 15 locations ofTestudo graecaalong South-Eastern Spain. We analyse the effects of environmental variables (precipitation, temperature, and NDVI) on the probability of laying eggs and the number of eggs per clutch. Finally, we couple the demographic and environmental data to parametrise integral projection models (IPMs) to simulate the effects of different scenarios of drought recurrence on population growth rate.We find that droughts negatively affect the probability of laying eggs, but the overall effects on the population growth rates ofT. graecaunder the current drought frequencies (one per decade) are negligible. However, increasing the annual frequency of droughts decreases the buffering ability ofT. graecapopulations, with a threshold at three droughts per decade.Although some species may buffer current environmental regimes by carefully orchestrating how their vital rates vary through time, a demographic buffering strategy may alone not warrant population viability in extreme regimes. Our findings support the hypothesis that the buffering strategy indeed has a threshold of effectiveness. Our methodological approach also provides a useful pipeline for ecologists and managers to determine how effective the management of environmental drivers can be for demographically buffering populations, and which scenarios may not provide long-term species persistence.
Expression of tyrosine hydroxylase gene from rat leads to oxidative stress in potato plants
Authors: Kostyn Kamil , Boba Aleksandra , Kostyn Anna , Starzycki Michał , Szopa Jan , Kulma Anna 
Published: May 2020

AbstractCatecholamines are biogenic aromatic amines common among both animals and plants. In animals they are synthesized via tyrosine hydroxylation, while in plants, both hydroxylation or decarboxylation of tyrosine are possible, depending on the species, though no tyrosine hydroxylase – a counterpart of animal enzyme has been identified yet. It is known that in potato plants it is the decarboxylation of tyrosine that leads to catecholamine production. In this paper we present the effects of induction of an alternative route of catecholamine production by introducing tyrosine hydroxylase gene from rat. We demonstrate that an animal system can be used by the plant, however, it does not function to synthesize catecholamines. Instead it leads to elevated reactive oxygen species content and constant stress condition to the plant which responds with elevated antioxidant level and further with improved resistance to infection.One sentence summaryIntroduction of rat tyrosine hydroxylase gene to potato disturbs catecholamine synthesis, causes oxidative stress and activates antioxidant response.
Simvastatin Therapy Attenuates Memory Deficits that Associate with Brain Monocyte Infiltration in Chronic Hypercholesterolemia
Authors: Don-Doncow Nicholas , Vanherle Lotte , Matthes Frank , Petersen Sine Kragh , Matuskova Hana , Rattik Sara , Härtlova Anetta , Meissner Anja 
Published: May 2020

AbstractEvidence associates cardiovascular risk factors with unfavorable systemic and neuro-inflammation and cognitive decline in the elderly. Cardiovascular therapeutics (e.g., statins and anti-hypertensives) possess immune-modulatory functions in parallel to their cholesterol- or blood pressure (BP)-lowering properties. How their ability to modify immune responses affects cognitive function is unknown. Here, we examined the effect of chronic hypercholesterolemia on inflammation and memory function in Apolipoprotein E (ApoE) knockout mice and normocholesterolemic wild-type mice. Chronic hypercholesterolemia that was accompanied by moderate blood pressure elevations associated with apparent immune system activation characterized by increases in circulating pro-inflammatory Ly6Chi monocytes in ApoE-/-mice. The persistent low-grade immune activation that is associated with chronic hypercholesterolemia facilitates the infiltration of pro-inflammatory Ly6Chi monocytes into the brain of aged ApoE-/-but not wild-type mice, and links to memory dysfunction. Therapeutic cholesterol-lowering through simvastatin reduced systemic and neuro-inflammation, and the occurrence of memory deficits in aged ApoE-/-mice with chronic hypercholesterolemia. BP-lowering therapy alone (i.e., hydralazine) attenuated some neuro-inflammatory signatures but not the occurrence of memory deficits. Our study suggests a link between chronic hypercholesterolemia, myeloid cell activation and neuro-inflammation with memory impairment and encourages cholesterol-lowering therapy as safe strategy to control hypercholesterolemia-associated memory decline during ageing.
Optimal coordination and reorganization of photosynthetic properties in C4grasses
Authors: Zhou Haoran , Akçay Erol , Helliker Brent 
Published: May 2020

AbstractC3and C4are major functional types in terrestrial biosphere models, with photosynthesis traits as important input parameters. The evolution of C4required reorganizations of Calvin-Benson-cycle and coordination of C4-cycle enzymes, resulting in divergences of physiological traits between C3and C4. In addition, photosynthesis further optimized after the evolution of C4causing diversification within C4lineages due to different evolutionary histories. We combined optimality modeling, physiological measurements and phylogenetic analysis to examine how various aspects of C4photosynthetic machinery were reorganized and coordinated within C4lineages and as compared to closely-related C3in grasses. Optimality models and measurements indicated a higher maximal electron transport to maximal Rubisco carboxylation ratio (Jmax/Vcmax) in C4than C3, consistent with the optimal prediction to maximize photosynthesis. The coordination between Calvin-Benson and C4cycles (Vpmax/Vcmax), however, is in line with the optimal modeling results under 200 ppm, as opposed to current CO2. Such inconsistencies can be explained by a slowly declining assimilation rate beyond optimalVpmax/Vcmax. Although rapid coordination occurred early in C4evolution, C4is still under optimizing processes and photosynthetic measures have continued to increase across time. Lastly, better understandings ofJmax/Vcmax,Vpmax/Vcmaxand fluorescence-based-electron-transport proffer enhanced approaches to parameterize terrestrial biosphere models.
Loss of Photosynthetic RhythmThermal Plasticity Under Domestication and Repurposing Drivers of Circadian Clock (DOC) Loci for Adaptive Breeding in Barley
Authors: Prusty Manas R. , Bdolach Eyal , Yamamoto Eiji , Neyhart Jeffrey L. , Tiwari Lalit D. , Pillen Klaus , Doron-Feigenbaum Adi , Smith Kevin P. , Fridman Eyal 
Published: May 2020

AbstractCircadian clock rhythms are critical to control physiological and development traits, allowing, plants to adapt to changing environments. Here we show that the circadian rhythms of cultivated barley (Hordeum vulgare) have slowed and amplitude increased under domestication by comparing with its wild ancestor (H. spontaneum). Moreover, we show a significant loss of thermal plasticity during barley evolution for the period and more extensively for amplitude. Our genetic analysis indicates that wild allele at epistatic loci, which mutually condition clock variation and its thermal plasticity in interspecific crosses, are absent in a contemporary barley breeding panel. These epistatic interactions include conditioned effects of Drivers of Circadian (DOC) clock loci on chromosome 3 and 5, which mediate amplitude decrease and period lengthening, respectively, under domestication. Notably, two significant loci,DOC3.1andDOC5.1, which are not associated with clock diversity in cultivated breeding material, do show pleiotropic effects on flowering time and grain yield at multiple experimental sites across the U.S. in a temperature-dependent manner. We suggest that transition from winter growth of wild barley (H. spontaneum) to spring growth of modern cultivars included the loss and repurposing of circadian clock regulators to yield adaptation by mechanisms yet to be clarified.Significance statementCircadian clock rhythms are crucial factors affecting crop adaptation to changing environments. If faced with increased temperature plants could respond with temperature compensation adaptation and maintain clock rhythms, or they can change period and/or amplitude to adapt. We used a combination of approaches: high-throughput clock analysis under optimal and elevated heat conditions, genome-wide association study (GWAS) with cultivated and wild diversity panels to identify changes under domestication and quantitative trait loci (QTL) that control the clock and its responses, and QTL-environment association for testing environmentally-conditioned effects of these QTLongrain yield and flowering timingacross US. Our findings provide insights into changes of circadian rhythms under domestication and genetic tools for plant breeders to develop better-adapted cultivars to changing environments.
A SNAI2-PEAK1 stromal axis drives progression and lapatinib resistance in HER2-positive breast cancer by supporting a cytokine expression profile that converges on PI3K/Akt signaling
Authors: Hamalian Sarkis , Güth Robert , Runa Farhana , Molnar Justin , Vickers Eric , Agajanian Megan , Humphries Jonathan , Humphries Martin J. , Tchou Julia , Zervantonakis Ioannis K. , Kelber Jonathan A. 
Published: May 2020

ABSTRACTIntercellular mechanisms by which the stromal microenvironment contributes to solid tumor progression and targeted therapy resistance remain poorly understood, presenting significant clinical hurdles. PEAK1 (Pseudopodium-Enriched Atypical Kinase One) is an actin cytoskeleton- and focal adhesion-associated pseudokinase that promotes cell state plasticity and cancer metastasis by mediating growth factor-integrin signaling crosstalk. Here, we determined that stromal PEAK1 expression predicts poor outcomes in HER2-positive breast cancers high in SNAI2 expression and enriched for MSC content. Notably, we identified that mesenchymal stem cells (MSCs) and cancer-associated fibroblasts (CAFs) express high PEAK1 protein levels and MSCs require PEAK1 to potentiate tumorigenesis, lapatinib resistance and metastasis of HER2-positive breast cancer cells. Analysis of PEAK1-dependent secreted factors from MSCs revealed a CCL4-, INHBA- and GDF5-focused network that converged on PI3K/Akt signaling. In this regard, we observed that MSC expression of PEAK1 is required for sustained Akt phosphorylation in neighboring HER2-positive breast cancer cells following lapatinib treatment. Finally, we uncovered a significant correlation between INHBA and PEAK1 expression levels in breast cancer, and that INHBA is an excellent predictor of disease relapse and decreased survival in HER2-positive tumors enriched for PEAK1 expression and MSC content. Importantly, we provide the first evidence that PEAK1 promotes tumorigenic phenotypes through a previously unrecognized SNAI2-PEAK1-INHBA-PI3K/Akt stromal to tumor cell signaling axis. These results establish a new, targetable intercellular mechanism that may be leveraged to improve targeted therapy responses and patient outcomes in breast cancer and other stroma-rich malignancies.
Spatiotemporal Evaluation of The Human Footprint in Colombia: Four Decades of Anthropic Impact in Highly Biodiverse Ecosystems
Authors: Correa Ayram Camilo Andrés , Etter Andres , Díaz-Timoté Jhonatan Julián , Buriticá Susana Rodríguez , Ramírez Wilson , Corzo Germán 
Published: May 2020

ABSTRACTThe maintenance of biodiversity and the capacity of natural systems to provide goods and services for people is affected on different levels by the intensity of human activities on ecosystems. In this study, we apply a Legacy-adjusted Human Footprint Index (LHFI) to evaluate the spatiotemporal variation of anthropic impact in Colombia in 1970, 1990, 2000 and 2015. We identified hotspots of change in LHFI and we evaluated the intensity of anthropic pressures in natural regions and ecosystems. We found that LHFI in Colombia increased between 1970 and 2015. The Andean and Caribbean regions presented the highest levels of anthropic impact, remaining stable over time. Hotspots of change were mainly located in the following regions: Andean (Antioquia, Cauca and Valle del Cauca states), Amazon (Amazonas, parts of Meta, Guaviare and Putumayo states) and Orinoco (Casanare and parts of Meta and Vichada states). In addition, ecosystems that under the IUCN ecosystem risk categories are Critically Endangered (CR) and Vulnerable (VU) were the most affected by a high level of human impact. Spatiotemporal evaluation of the human footprint in Colombia provides new insights about trends in human pressures on ecosystems and constitutes an analytical tool with high potential for harmonizing land use planning and biodiversity conservation.
Implications of SARS-CoV-2 mutations for genomic RNA structure and host microRNA targeting
Authors: Rad SM Ali Hosseini , McLellan Alexander D. 
Published: May 2020

AbstractThe SARS-CoV-2 virus is a recently-emerged zoonotic pathogen already well adapted to transmission and replication in humans. Although the mutation rate is limited, recently introduced mutations in SARS-CoV-2 have the potential to alter viral fitness. In addition to amino acid changes, mutations could affect RNA secondary structure critical to viral life cycle, or interfere with sequences targeted by host miRNAs. We have analysed subsets of genomes from SARS-CoV-2 isolates from around the globe and show that several mutations introduce changes in Watson-Crick pairing, with resultant changes in predicted secondary structure. Filtering to targets matching miRNAs expressed in SARS-CoV-2 permissive host cells, we identified twelve separate target sequences in the SARS-CoV-2 genome; eight of these targets have been lost through conserved mutations. A genomic site targeted by the highly abundant miR-197-5p, overexpressed in patients with cardiovascular disease, is lost by a conserved mutation. Our results are compatible with a model that SARS-CoV-2 replication within the human host could be constrained by host miRNA defence. The impact of these and further mutations on secondary structures, miRNA targets or potential splice sites offers a new context in which to view future SARS-CoV-2 evolution, and a potential platform for engineered viral attenuation and antigen presentation.
Mitigation of radiation damage in biological macromolecules via tunable picosecond pulsed transmission electron microscopy
Authors: Choe Hyeokmin , Ponomarev Ilya , Montgomery Eric , Lau June W. , Zhu Yimei , Zhao Yubin , Liu Ao , Kanareykin Alexei , Jing Chunguang 
Published: May 2020

AbstractWe report mitigation of electron-beam-induced radiation damage in biological macromolecules using rapid, low-dose transmission electron microscopy (TEM) with a new, tunable, retrofittable picosecond pulser. Damage mitigation strategies historically consisted of sample cryoprotection and ultra-low beam current; ultrafast laser-pulsed systems have shown promise, but with day-long acquisition times. We show the first practical, fast, laser-free tunable system, with acquisition of diffraction series in minutes at 5.2 GHz and 10 pA. This is the largest study to date: two materials (C36H74paraffin and purple membrane), two beam energies (200 keV and 300 keV), two independent microscopes (Schottky and LaB6), two modes (pulsed and continuous), and unsurpassed repetition rate tunability. Critical dose at room temperature doubled versus continuous beam for ∼100 MHz single-electron repetition rates. Results herald a new class of highly-tunable, ultrafast pulsers with future applications in cryogenic electron microscopy (CryoEM), high resolution single particle imaging, and rapid low-dose TEM.