bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Bayesian Analysis of Steady–State Enzyme Data leads to Estimates of Rate Constants and Uncertainties in a Multi-Step Reaction, along with Free Energy Profiles†
Authors: Barr Ian 
Published: August 2021

AbstractThe microscopic rate constants that govern an enzymatic reaction are only directly measured under certain experimental set-ups, such as stopped flow, quenched flow, or temperaturejump assays; the majority of enzymology proceeds from steady state conditions which leads to a set of more easily–observable parameters such askcat,KM, and observed Kinetic Isotope Effects. This paper further develops a model from Toney (2013) to estimate microscopic rate constants from steady-state data for a set of reversible, four–step reactions. This paper uses the Bayesian modeling software Stan, and demonstrates the benefits of Bayesian data analysis in the estimation of these rate constants. In contrast to the optimization methods employed often in the estimation of kinetic constants, a Bayesian treatment is more equipped to estimate the uncertainties of each parameter; sampling from the posterior distribution using Hamiltonian Monte Carlo immediately gives parameter estimates as mean or median of the posterior, and also confidence intervals that express the uncertainty of each parameter.
Response to nitrogen and salinity in Rhizophora mangle propagules varies by maternal family and population of origin
Authors: Richards Christina L. , Langanke Kristen L. , Mounger Jeannie , Fox Gordon A. , Lewis David B. 
Published: August 2021

AbstractMany coastal foundation plant species thrive across a range of environmental conditions, often displaying dramatic phenotypic variation in response to environmental variation. We characterized the response of propagules from six populations of the foundation species Rhizophora mangle L. to full factorial combinations of two levels of salt (15 ppt and 45 ppt) reflecting the range of salinity measured in the field populations, and two levels of nitrogen (N; no addition and amended at approximately 3 mg N per pot each week) equivalent to comparing ambient N to a rate of addition of 75 kg per hectare per year. The response to increasing salt included significant plasticity in succulence. Propagules also showed plasticity in maximum photosynthetic rate in response to N amendment, but the responses depended on the level of salt and varied by population of origin. Generally, survival was lower in high salt and high N, but the impact varied among populations. Overall, this study revealed significant phenotypic plasticity in response to salt and N level. Propagules from different populations differed in all traits measured. Variation in phenotypic plasticity and propagule survival in R. mangle may contribute to adaptation to a complex mosaic of environmental conditions and response to climate change.
GEPSi: A Python Library to Simulate GWAS Phenotype Data
Authors: Reidenbach Daniel A. , Lal Avantika , Slim Lotfi , Mosafi Ohad , Israeli Johnny 
Published: August 2021

AbstractMotivationMany computational methods aim to identify genetic variants associated with diseases and complex traits. Due to the absence of ground truth data, simulated genotype and phenotype data is needed to benchmark these methods. However, phenotypes are frequently simulated as an additive function of randomly selected variants, neglecting biological complexity such as non-random occurrence of causal SNPs, epistatic effects, heritability and dominance. Including such features would improve benchmarking studies and accelerate the development of methods for genetic analysis.ResultsHere, we describe GEPSi (GWAS Epistatic Phenotype Simulator), a user-friendly python package to simulate phenotype data based on user-supplied genotype data for a population. GEPSi incorporates diverse biological parameters such as heritability, dominance, population stratification and epistatic interactions between SNPs. We demonstrate the use of this package to compare machine learning methods for GWAS analysis.Availability and ImplementationGEPSi is freely available under an Apache 2.0 license, and can be downloaded from https://github.com/clara-parabricks/GEPSi.Supplementary informationSupplementary data are available online.
Sex-dependent development of Kras-induced anal squamous cell carcinoma in mice
Authors: Walcheck Morgan T. , Matkowskyj Kristina A. , Turco Anne , Blaine-Sauer Simon , Nukaya Manabu , Noel Jessica , Ronnekleiv Oline K. , Ronnekleiv-Kelly Sean M. 
Published: August 2021

AbstractAnal squamous cell carcinoma (SCC) will be diagnosed in an estimated 9,080 adults in the United States this year, and rates have been rising over the last several decades. Most people that develop anal SCC have associated human papillomavirus (HPV) infection (∼85-95%), with approximately 5-15% of anal SCC cases occurring in HPV-negative patients from unknown etiology. This study identified and characterized a Kras-driven, female sex hormone-dependent development of anal squamous cell carcinoma (SCC) in the LSL-KrasG12D ; Pdx1-Cre (KC) mouse model that is not dependent on papillomavirus infection. One hundred percent of female KC mice develop anal SCC, while no male KC mice develop tumors. Both male and female KC anal tissue express Pdx1 and Cre-recombinase mRNA, and the activated mutant KrasG12D gene. Although the driver gene mutation KrasG12D is present in anus of both sexes, only female KC mice develop Kras-mutant induced anal SCC. To understand the sex-dependent differences, KC male mice were castrated and KC female mice were ovariectomized. Castrated KC males displayed an unchanged phenotype with no anal tumor formation. In contrast, ovariectomized KC females demonstrated a marked reduction in anal SCC development, with only 15% developing anal SCC. Finally, exogenous administration of estrogen rescued the tumor development in ovariectomized KC female mice and induced tumor development in castrated KC males. These results confirm that the anal SCC is estrogen mediated. The delineation of the role of female sex hormones in mediating mutant Kras to drive anal SCC pathogenesis highlights a subtype of anal SCC that is independent of papillomavirus infection. These findings may have clinical applicability for the papillomavirus-negative subset of anal SCC patients that typically respond poorly to standard of care chemoradiation.
Gadolinium-free Magnetic Resonance Imaging of the Liver using an Oatp1-targeted Manganese(III) Porphyrin
Authors: Nyström Nivin N. , Liu Hanlin , Martinez Francisco M. , Zhang Xiao-an , Scholl Timothy J. , Ronald John A. 
Published: August 2021

ABSTRACTControversy surrounding gadolinium-based contrast agents (GBCAs) have rendered their continued utility highly contentious, but the liver-specific GBCA Gd(III) ethoxybenzyl-diethylene triamine pentaacetic acid (Gd(III)-EOB-DTPA) remains in use because it provides unique diagnostic information that could not be obtained by any other means. To address the need for an alternative liver-specific MRI contrast agent, we synthesized Mn(III) 20-(4-ethoxyphenyl) porphyrin-5,10,15-tricarboxylate (Mn(III)TriCP-PhOEt), which exhibited significantly higher r1 relaxivity than Gd(III)-EOB-DTPA, and targeted organic anion-transporting polypeptide 1 (Oatp1) channels as a biomarker of hepatocyte viability. Mn(III)TriCP-PhoEt increased the r1 relaxation rate of cells expressing rodent Oatp1a1 and human Oatp1b3, relative to control cells not expressing these liver channels. In mice, Mn(III)TriCP-PhoEt resulted in significant and specific increases in liver signal intensity on T1-weighted images, and significant decreases in liver T1 time relative to precontrast measurements. Our findings suggest that Mn(III)TriCP-PhOEt operates as a specific and sensitive MR contrast agent for in vivo liver imaging.
Pandemic-Scale Phylogenomics Reveals Elevated Recombination Rates in the SARS-CoV-2 Spike Region
Authors: Turkahia Yatish , Thornlow Bryan , Hinrichs Angie , McBroome Jakob , Ayala Nicolas , Ye Cheng , De Maio Nicola , Haussler David , Lanfear Robert , Corbett-Detig Russell 
Published: August 2021

AbstractAccurate and timely detection of recombinant lineages is crucial for interpreting genetic variation, reconstructing epidemic spread, identifying selection and variants of interest, and accurately performing phylogenetic analyses. During the SARS-CoV-2 pandemic, genomic data generation has exceeded the capacities of existing analysis platforms, thereby crippling real-time analysis of viral recombination. Low SARS-CoV-2 mutation rates make detecting recombination difficult. Here, we develop and apply a novel phylogenomic method to exhaustively search a nearly comprehensive SARS-CoV-2 phylogeny for recombinant lineages. We investigate a 1.6M sample tree, and identify 606 recombination events. Approximately 2.7% of sequenced SARS-CoV-2 genomes have recombinant ancestry. Recombination breakpoints occur disproportionately in the Spike protein region. Our method empowers comprehensive real time tracking of viral recombination during the SARS-CoV-2 pandemic and beyond.
Virucidal activity of CPC-containing oral rinses against SARS-CoV-2 variants and are active in the presence of human saliva
Authors: Anderson Enyia R , Patterson Edward I , Richards Siobhan , Green Alison , Mukherjee Sayandip , Hoptroff Michael , Hughes Grant L 
Published: August 2021

AbstractThe role of human saliva in aerosol-based transmission of SARS-CoV-2 has highlighted the need to understand the potential of oral hygiene products to inactivate the virus. Here we examined the efficacy of mouthwashes containing cetylpyridinium chloride (CPC) or chlorhexidine (CHX) in inactivating SARS-CoV-2. After 30 seconds contact under standard aqueous conditions CPC mouthwashes achieved a ≥4.0log10PFU/mL reduction in SARS-CoV-2 (USA-WA1/2020) titres whereas comparable products containing CHX achieved <2.0log10PFU/mL reduction. Further testing with CPC mouthwashes demonstrated efficacy against multiple SARS-CoV-2 variants, with inactivation below the limit of detection observed against the Alpha (B.1.1.7), Beta (B.1.351) and Gamma (P.1) variants. Virucidal efficacy of CPC mouthwash was also observed in the presence of human saliva with the product delivering ≥4.0log10PFU/mL reduction in SARS-CoV-2 titres after 30 seconds providing additional evidence for the virucidal efficacy of CPC mouthwashes under simulated physiological conditions. Together these data suggest CPC-based mouthwashes are effective at inactivating SARS-CoV-2 and further supports the use of mouthwash to mitigate the risk of transmission during dentistry procedures.
Th1/17 Cells Infiltrate Murine Cytomegalovirus-Infected Renal Allografts via Virus-Induced CCL20 and Promote Th1 Cells through IL-17A
Authors: Dhital Ravi , Anand Shashi , Zeng Qiang , Velazquez Victoria M. , Boddeda Srinivasa R. , Fitch James R. , Minz Ranjana W. , Minz Mukut , Sharma Ashish , Cianciolo Rachel , Shimamura Masako 
Published: August 2021

ABSTRACTCytomegalovirus (CMV) infection is associated with renal allograft failure by unknown mechanisms. In a murine renal transplant model, murine CMV (MCMV) induces intragraft infiltration of Th17 cells co-expressing Th1 cytokines, IFN-γ and TNF-α, but only a minority of intragraft Th17 cells are specific for MCMV antigens. Instead, MCMV promotes viral antigen-independent Th17 cell recruitment via CCL20-CCR6 and CXCL10-CXCR3 interactions. Th17 cells correlate directly with Th1 cell frequencies and inversely with Tregs in MCMV infected grafts. Pharmacologic inhibition of IL-17A reduces intragraft Th17 cells and neutrophils, increases Tregs, and reduces total but not MCMV-specific Th1 cells. Among a clinical renal transplant cohort with acute rejection, patients with CMV DNAemia had significantly higher serum IL-17A quantities compared to those without CMV DNAemia. Together, these findings indicate that CMV infection upregulates Th17 cell activity during acute rejection and suggests that inhibition of IL-17A may ameliorate CMV-associated allograft injury without impairing antiviral Th1 cells.
Rapid assessment of SARS-CoV-2 evolved variants using virus-like particles
Authors: Syed Abdullah M. , Taha Taha Y. , Khalid Mir M. , Tabata Takako , Chen Irene P. , Sreekumar Bharath , Chen Pei-Yi , Hayashi Jennifer M. , Soczek Katarzyna M. , Ott Melanie , Doudna Jennifer A. 
Published: August 2021

AbstractNewly evolved SARS-CoV-2 variants are driving ongoing outbreaks of COVID-19 around the world. Efforts to determine why these viral variants have improved fitness are limited to mutations in the viral spike (S) protein and viral entry steps using non-SARS-CoV-2 viral particles engineered to display S. Here we show that SARS-CoV-2 virus-like particles can package and deliver exogenous transcripts, enabling analysis of mutations within all structural proteins and rapid dissection of multiple steps in the viral life cycle. Identification of an RNA packaging sequence was critical for engineered transcripts to assemble together with SARS-CoV-2 structural proteins S, nucleocapsid (N), membrane (M) and envelope (E) into non-replicative SARS-CoV-2 virus-like particles (SC2-VLPs) that deliver these transcripts to ACE2- and TMPRSS2-expressing cells. Using SC2-VLPs, we tested the effect of 30 individual mutations within the S and N proteins on particle assembly and entry. While S mutations unexpectedly did not affect these steps, SC2-VLPs bearing any one of four N mutations found universally in more-transmissible viral variants (P199L, S202R, R203M and R203K) showed increased particle production and up to 10-fold more reporter transcript expression in receiver cells. Our study provides a platform for rapid testing of viral variants outside a biosafety level 3 setting and identifies viral N mutations and viral particle assembly as mechanisms to explain the increased spread of current viral variants, including Delta (N:R203M).One-Sentence SummaryR203M substitution within SARS-CoV-2 N, found in delta variant, improves RNA packaging into virus-like particles by 10-fold.
Precision dynamical mapping using topological data analysis reveals a unique hub-like transition state at rest
Authors: Saggar Manish , Shine James M. , Liégeois Raphaël , Dosenbach Nico U. F. , Fair Damien 
Published: August 2021

AbstractEven in the absence of external stimuli, neural activity is both highly dynamic and organized across multiple spatiotemporal scales. The continuous evolution of brain activity patterns during rest is believed to help maintain a rich repertoire of possible functional configurations that relate to typical and atypical cognitive phenomena. Whether these transitions or “explorations” follow some underlying arrangement or instead lack a predictable ordered plan remains to be determined. Here, using a precision dynamics approach, we aimed at revealing the rules that govern transitions in brain activity at rest at the single participant level. We hypothesized that by revealing and characterizing the overall landscape of whole brain configurations (or states) we could interpret the rules (if any) that govern transitions in brain activity at rest. To generate the landscape of whole-brain configurations we used Topological Data Analysis based Mapper approach. Across all participants, we consistently observed a rich topographic landscape in which the transition of activity from one state to the next involved a central hub-like “transition state.” The hub topography was characterized as a shared attractor-like basin where all canonical resting-state networks were represented equally. The surrounding periphery of the landscape had distinct network configurations. The intermediate transition state and traversal through it via a topographic gradient seemed to provide the underlying structure for the continuous evolution of brain activity patterns at rest. In addition, differences in the landscape architecture were more consistent within than between subjects, providing evidence of idiosyncratic dynamics and potential utility in precision medicine.
KIF2C regulates synaptic plasticity and cognition by mediating dynamic microtubule invasion of dendritic spines
Authors: Zheng Rui , Du Yong-Lan , Wang Xin-Tai , Liao Tai-Lin , Zhang Zhe , Wang Na , Li Xiu-Mao , Shen Ying , Shi Lei , Luo Jian-Hong , Xia Jun , Wang Ziyi , Xu Junyu 
Published: August 2021

AbstractDynamic microtubules play a critical role in cell structure and function. In nervous system, microtubules specially extend into and out of synapses to regulate synaptic development and plasticity. However, the detailed polymerization especially the depolymerization mechanism that regulates dynamic microtubules in synapses is still unclear. In this study, we find that KIF2C, a dynamic microtubule depolymerization protein without known function in the nervous system, plays a vital role in the structural and functional plasticity of synapses and regulates cognitive function. Using RNAi knockdown and conditional knockout approaches, we showed that KIF2C regulates spine morphology and synaptic membrane expression of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid) receptors. Moreover, KIF2C deficiency leads to impaired excitatory transmission, long-term potentiation, and altered cognitive behaviors in mice. Mechanistically, KIF2C regulates microtubule dynamics and microtubule invasion of spines in neurons by its microtubule depolymerization capability in a neuronal activity-dependent manner. This study explores a novel function of KIF2C in the nervous system and provides an important regulatory mechanism on how microtubule invasion of spines regulates synaptic plasticity and cognition behaviors.
Is the genomics ‘cart’ before the restoration ecology ‘horse’? Insights from qualitative interviews and trends from the literature
Authors: Mohr Jakki J. , Harrison Peter A. , Stanhope Jessica , Breed Martin F. 
Published: August 2021

SummaryHarnessing new technologies is vital to achieve global imperatives to restore degraded ecosystems. We explored the potential of genomics as one such tool. We aimed to understand barriers hindering the uptake of genomics, and how to overcome them, via exploratory interviews with leading scholars in both restoration and its sister discipline of conservation – a discipline that has successfully leveraged genomics. We also conducted an examination of research trends to explore some insights that emerged from the interviews, including publication trends that have used genomics to address restoration and conservation questions. Our qualitative findings revealed varied perspectives in harnessing genomics. For example, scholars in restoration without genomics experience felt genomics was over-hyped. Scholars with genomics experience emphatically emphasised the need to proceed cautiously in using genomics in restoration. Both genomics-experienced and less-experienced scholars called for case studies to demonstrate the benefits of genomics in restoration. These qualitative data contrasted with our examination of research trends, which revealed 70 restoration genomics studies, particularly studies using environmental DNA as a monitoring tool. We provide a roadmap to facilitate the uptake of genomics into restoration, to help the restoration sector meet the monumental task of restoring huge areas to biodiverse and functional ecosystems.
Extracellular and intracellular components of the impedance of neural tissue
Authors: Bedard Claude , Piette Charlotte , Venance Laurent , Destexhe Alain 
Published: August 2021

AbstractElectric phenomena in brain tissue can be measured using extracellular potentials, such as the local field potential, or the electro-encephalogram. The interpretation of these signals depend on the electric structure and properties of extracellular media, but the measurements of these electric properties are still debated. Some measurements point to a model where the extracellular medium is purely resistive, and thus parameters such as electric conductivity and permittivity should be independent of frequency. Other measurements point to a pronounced frequency dependence of these parameters, with scaling laws that are consistent with capacitive or diffusive effects. However, these experiments correspond to different preparations, and it is unclear how to correctly compare them. Here, we provide for the first time, impedance measurements (in the 1-10 KHz frequency range) using the same set-up in various preparations, from primary cell cultures to acute brain slices, with a comparison with similar measurements performed in artificial cerebrospinal fluid with no biological material. The measurements show that when the current flows across a cell membrane, the frequency dependence of the macroscopic impedance between intracellular and extracellular electrodes is significant, and cannot be captured by a model with resistive media. Fitting a mean-field model to the data shows that this frequency dependence could be explained by the ionic diffusion mainly associated to Debye layers surrounding the membranes. We conclude that neuronal membranes and their ionic environment induce strong deviations to resistivity, that should be taken into account to correctly interpret extracellular potentials generated by neurons.SignificanceThe electro-encephalogram recorded at the scalp surface and local-field potentials recorded within neural tissue are generated by electric currents in neurons, and thus depend on the impedance of neural tissue. Different measured values were proposed, and it is currently unclear what is the real impedance of neural tissue. Here, we show that the impedance depends on the measurement technique. If the measurement is exclusively extracellular, the system appears as equivalent to a simple resistor. However, if the measurement includes an intracellular electrode, a more complex impedance is observed, because the current has to flow through the membrane, as happening in the brain. Thus, we provide an explanation for apparent disagreements, and indicate in which cases each impedance should be used.