bluuebunny/crossref_metadata_2025 huggingface dataset:
Movement-Preceding Neural Activity under Parametrically Varying Levels of Time Pressure
Authors: Trovò Bianca , Visser Yvonne , İşcan Zafer , Schurger Aaron
Published: April 2021

Self-initiated movements are known to be preceded by the readiness potential or RP, a gradual increase in surface-negativity of cortical potentials that can begin up to 1 second or more before movement onset. The RP has been extensively studied for decades, and yet we still lack a clear understanding of its functional role. Attempts to model the RP as an accumulation-to-bound process suggest that this signal is a by-product of time-locking to crests in neural noise rather than the outcome of a pre-conscious decision to initiate a movement. One parameter of the model accounts for the imperative to move now, with cued movements having a strong imperative and purely spontaneous movements having no imperative. Two different variants of the model have been proposed, and both predict a decrease in the (negative) amplitude of the early RP as the imperative grows stronger. In order to test this empirically, we conducted an experiment where subjects produced self-initiated movements under varying levels of time pressure, and we investigated the amplitude, shape, and latency of the RP as a function of the imperative to move, operationalised as a time limit. We identified distinct changes in the amplitude of the early RP that grew non-linearly as the time limit grew shorter. Thus these data did not support the prediction made by the model. In addition, our results confirm that the shape of the RP is not stereotypically negative, being either positive or absent in about half of the subjects.
Nopp140-chaperoned 2’-O-methylation of small nuclear RNAs in Cajal bodies ensures splicing fidelity
Authors: Bizarro Jonathan , Deryusheva Svetlana , Wacheul Ludivine , Gupta Varun , Ernst Felix G.M. , Lafontaine Denis L.J. , Gall Joseph G. , Meier U. Thomas
Published: April 2021

Spliceosomal small nuclear RNAs (snRNAs) are modified by small Cajal body (CB) specific ribonucleoproteins (scaRNPs) to ensure snRNP biogenesis and pre-mRNA splicing. However, the function and subcellular site of snRNA modification are largely unknown. We show that CB localization of the protein Nopp140 is essential for concentration of scaRNPs in that nuclear condensate; and that phosphorylation by casein kinase 2 (CK2) at some 80 serines targets Nopp140 to CBs. Transiting through CBs, snRNAs are apparently modified by scaRNPs. Indeed, Nopp140 knockdown-mediated release of scaRNPs from CBs severely compromises 2’-O-methylation of spliceosomal snRNAs, identifying CBs as the site of scaRNP catalysis. Additionally, alternative splicing patterns change indicating that these modifications in U1, U2, U5, and U12 snRNAs safeguard splicing fidelity. Given the importance of CK2 in this pathway, compromised splicing could underlie the mode of action of small molecule CK2 inhibitors currently considered for therapy in cholangiocarcinoma, hematological malignancies, and COVID-19.
Cerebellar Neuronal Dysfunction Accompanies Early Motor Symptoms in Spinocerebellar Ataxia Type 3
Authors: Mayoral-Palarz Kristin , Neves-Carvalho Andreia , Maciel Patrícia , Khodakhah Kamran
Published: April 2021

Spinocerebellar Ataxia Type 3 (SCA3) is an adult-onset, progressive ataxia. SCA3 presents with ataxia before any gross neuropathology. A feature of many cerebellar ataxias is aberrant cerebellar output that contributes to motor dysfunction. We examined whether abnormal cerebellar output was present in the CMVMJD135 SCA3 mouse model and, if so, whether it correlated with the disease onset and progression.In vivorecordings showed that the activity of deep cerebellar nuclei neurons, the main output of the cerebellum, was altered. The aberrant activity correlated with the onset of ataxia. However, although the severity of ataxia increased with age, the severity of the aberrant cerebellar output was not progressive. The abnormal cerebellar output, however, was accompanied with non-progressive abnormal activity of their upstream synaptic inputs, the Purkinje cells.In vitrorecordings indicated that alterations in both intrinsic Purkinje cell pacemaking and in their synaptic inputs contributed to abnormal Purkinje cell activity. These findings implicate abnormal cerebellar physiology as an early, consistent contributor to pathophysiology in SCA3, and suggest that the aberrant cerebellar output could be an appropriate therapeutic target in SCA3.

Summary Statement

In a mouse model of Spinocerebellar ataxia type 3 aberrant cerebellar physiology is apparent early in disease, before overt neuronal pathology or neuronal death.
Type I interferon responsive microglia shape cortical development and behavior
Authors: Escoubas Caroline C. , Dorman Leah C. , Nguyen Phi T. , Lagares-Linares Christian , Nakajo Haruna , Anderson Sarah R. , Cuevas Beatriz , Vainchtein Ilia D. , Silva Nicholas J. , Xiao Yinghong , Lidsky Peter V. , Wang Ellen Y. , Taloma Sunrae E. , Nakao-Inoue Hiromi , Schwer Bjoern , Andino Raul , Nowakowski Tomasz J. , Molofsky Anna V.
Published: April 2021

Microglia are brain resident phagocytes that can engulf synaptic components and extracellular matrix as well as whole neurons. However, whether there are unique molecular mechanisms that regulate these distinct phagocytic states is unknown. Here we define a molecularly distinct microglial subset whose function is to engulf neurons in the developing brain. We transcriptomically identified a cluster of Type I interferon (IFN-I) responsive microglia that expanded 20-fold in the postnatal day 5 somatosensory cortex after partial whisker deprivation, a stressor that accelerates neural circuit remodeling.In situ, IFN-I responsive microglia were highly phagocytic and actively engulfed whole neurons. Conditional deletion of IFN-I signaling (Ifnar1fl/fl) in microglia but not neurons resulted in dysmorphic microglia with stalled phagocytosis and an accumulation of neurons with double strand DNA breaks, a marker of cell stress. Conversely, exogenous IFN-I was sufficient to drive neuronal engulfment by microglia and restrict the accumulation of damaged neurons. IFN-I deficient mice had excess excitatory neurons in the developing somatosensory cortex as well as tactile hypersensitivity to whisker stimulation. These data define a molecular mechanism through which microglia engulf neurons during a critical window of brain development. More broadly, they reveal key homeostatic roles of a canonical antiviral signaling pathway in brain development.
Evaluation of data-driven MEG analysis approaches for the extraction of fMRI resting state networks
Authors: Pelzer Esther Annegret , Sharma Abhinav , Florin Esther
Published: April 2021

The electrophysiological basis of resting state networks (RSN) is still under debate. In particular, no principled mechanism has been determined that is capable of explaining all RSN equally well. While magnetoencephalography (MEG) and electroencephalography (EEG) are the methods of choice to determine the electrophysiological basis of RSN, no standard analysis pipeline of RSN yet exists. In this paper, we compare the two main existing data-driven analysis strategies for extracting resting state networks from MEG data. The first approach extracts RSN through an independent component analysis (ICA) of the Hilbert envelope in different frequency bands. The second approach uses phase –amplitude coupling to determine the RSN. To evaluate the performance of these approaches, we compare the MEG-RSN to the functional magnetic resonance imaging (fMRI)-RSN from the same subjects.

Overall, it was possible to extract the canonical fMRI RSN with MEG. The approach based on phase-amplitude coupling yielded the best correspondence to the fMRI-RSN. The Hilbert envelope-ICA produced different dominant frequency-bands underlying RSN for different ICA runs, suggesting the absence of a single dominant frequency underlying the RSN. Our results also suggest that individual RSN are not characterized by one single dominant frequency. Instead, the resting state networks seem to be based on a combination of the delta/theta phase and gamma amplitude.
A model of naturalistic decision making in preference tests
Authors: Ksander John , Katz Donald B , Miller Paul
Published: April 2021

Decisions as to whether to continue with an ongoing activity or to switch to an alternative are a constant in an animal’s natural world, and in particular underlie foraging behavior and performance in food preference tests. Stimuli experienced by the animal both impact the choice and are themselves impacted by the choice, in a dynamic back and forth. Here, we present model neural circuits, based on spiking neurons, in which the choice to switch away from ongoing behavior instantiates this back and forth, arising as a state transition in neural activity. We analyze two classes of circuit, which differ in whether state transitions result from a loss of hedonic input from the stimulus (an “entice to stay” model) or from aversive stimulus input (a “repel to leave” model). In both classes of model, we find that the mean time spent sampling a stimulus decreases with increasing value of the alternative stimulus, a fact that we linked to the inclusion of depressing synapses in our model. The competitive interaction is much greater in “entice to stay” model networks, which has qualitative features of the marginal value theorem, and thereby provides a framework for optimal foraging behavior. We offer suggestions as to how our models could be discriminatively tested through the analysis of electrophysiological and behavioral data.

Author summary

Many decisions are of the ilk of whether to continue sampling a stimulus or to switch to an alternative, a key feature of foraging behavior. We produce two classes of model for such stay-switch decisions, which differ in how decisions to switch stimuli can arise. In an “entice-to-stay” model, a reduction in the necessary positive stimulus input causes switching decisions. In a “repel-to-leave” model, a rise in aversive stimulus input produces a switch decision. We find that in tasks where the sampling of one stimulus follows another, adaptive biological processes arising from a highly hedonic stimulus can reduce the time spent at the following stimulus, by up to ten-fold in the “entice-to-stay” models. Along with potentially observable behavioral differences that could distinguish the classes of networks, we also found signatures in neural activity, such as oscillation of neural firing rates and a rapid change in rates preceding the time of choice to leave a stimulus. In summary, our model findings lead to testable predictions and suggest a neural circuit-based framework for explaining foraging choices.
Biomolecular mechanisms for signal differentiation
Authors: Alexis Emmanouil , Schulte Carolin CM , Cardelli Luca , Papachristodoulou Antonis
Published: April 2021

Cells can sense temporal changes of molecular signals, allowing them to predict environmental vari-ations and modulate their behaviour. This paper elucidates the underlying biomolecular mechanisms of time derivative computation, facilitating the design of reliable synthetic differentiator devices for a variety of applications, ultimately expanding our understanding of cell behaviour. In particular, we describe and analyse three alternative biomolecular topologies that work as signal differentiators of high accuracy to arbitrary input signals around their nominal operation. We propose strategies to preserve their performance even in the presence of high-frequency input signal components, which are detrimental to the performance of most differentiators. We found that the core of the proposed topologies appears in natural regulatory networks and we further discuss their biological relevance. The simple structure of our designs makes them promising tools for realizing derivative control action in synthetic biology.
Hybridization and cryptic speciation in the Tropical Eastern Pacific octocoral genusPacifigorgia
Authors: Poliseno Angelo , Breedy Odalisca , Guzman Hector M. , Vargas Sergio
Published: April 2021

The shallow waters of the Tropical Eastern Pacific (TEP) harbor a species-rich octocoral fauna, with seven genera and 124 octocoral species described to date for the region. Of these lineages,Pacifigorgia, with 35 species, is by far the most speciose and abundant shallow-water octocoral occurring in the region. The speciation mechanisms resulting in this remarkable diversity remain speculative, despite the extensive taxonomic and molecular systematic research conducted so far in the TEP. Using genome-wide SNP markers, we provide evidence for hybridization and extensive cryptic speciation inPacifigorgia, suggesting that the genus’ diversity has been underestimated by traditional and molecular systematic research. Our study highlights the difficulties faced by both traditional taxonomy and single-marker based molecular approaches to characterize octocoral diversity and evolution, and the role genome-wide molecular studies coupled to morphological research play to advance our understanding of this group.
Climate trends and behavior of an avian forest specialist in central Amazonia indicate thermal stress during the dry season
Authors: Jirinec Vitek , Rutt Cameron L. , Elizondo Elisa C. , Rodrigues Patricia F. , Stouffer Philip C
Published: April 2021

Rainforest loss threatens terrestrial insectivorous birds throughout the world’s tropics. Recent evidence shows these birds to be declining in undisturbed Amazonian rainforest, possibly due to climate change. Here, we first addressed whether Amazonian terrestrial insectivores were exposed to climate change using 38 years of climate data. We found that climate has changed in central Amazonia, especially in the dry season, which was ∼1.3°C hotter and 21% drier in 2019 than in 1981. Second, to test whether birds actively avoided hot and dry conditions, we used field sensors to identify ambient extremes and prospective microclimate refugia within undisturbed rainforest from 2017 – 2019. Simultaneously, we examined how tagged Black-faced Anthrushes (Formicarius analis) used this space. We collected 1.4 million field measurements quantifying ambient conditions in the forest understory, including along elevation gradients. For 11 birds, we obtained GPS locations to test whether birds adjusted their shelter use (n= 2,724) or elevation (n= 640) across seasonal and daily cycles. For four additional birds, we collected >180,000 light and temperature readings to assess exposure. Field measurements in the modern landscape revealed that temperature was higher in the dry season and highest on plateaus. Thus, low-lying areas were relatively buffered, providing microclimate refugia during hot afternoons in the dry season. At those times, birds entered shelters and shifted downslope, reducing their thermal exposure by 50%. Because climate change intensifies the hot, dry conditions that antthrushes avoid, our results are consistent with the hypothesis that climate change lowers habitat quality for terrestrial insectivores. This sensitivity may be related to their declines within ‘undisturbed’ Amazonian rainforest.
Distinct bioenergetic features of human invariant natural killer T (iNKT) cells enable retained functions in nutrient-deprived states
Authors: Khurana Priya , Burudpakdee Chakkapong , Grupp Stephan A. , Beier Ulf H. , Barrett David M. , Bassiri Hamid
Published: April 2021

Invariant natural killer T (iNKT) cells comprise a unique subset of lymphocytes that are primed for activation and possess innate NK-like functional features. Currently, iNKT cell-based immunotherapies remain in early clinical stages, and little is known about the ability of these cells to survive and retain effector functions within the solid tumor microenvironment (TME) long-term. In conventional T cells (TCONV), cellular metabolism is linked to effector functions and their ability to adapt to the nutrient-poor TME. In contrast, the bioenergetic requirements of iNKT cells – particularly those of human iNKT cells – at baseline and upon stimulation are not well understood; neither is how these requirements affect cytokine production or anti-tumor effector functions. We find that unlike TCONV, human iNKT cells are not dependent upon glucose or glutamine for cytokine production and cytotoxicity upon stimulation with anti-CD3 and anti-CD28. Additionally, transcriptional profiling revealed that stimulated human iNKT cells are less glycolytic than TCONVand display higher expression of fatty acid oxidation (FAO) and adenosine monophosphate-activated protein kinase (AMPK) pathway genes. Furthermore, stimulated iNKT cells displayed higher mitochondrial mass and membrane potential relative to TCONV. Real-time Seahorse metabolic flux analysis revealed that stimulated human iNKT cells utilize fatty acids as substrates for oxidation more than stimulated TCONV. Together, our data suggest that human iNKT cells possess different bioenergetic requirements from TCONVand display a more memory-like metabolic program relative to effector TCONV. Importantly, iNKT cell-based immunotherapeutic strategies could co-opt such unique features of iNKT cells to improve their efficacy and longevity of anti-tumor responses.
Hunter-gatherer foraging networks promote information transmission
Authors: Garg Ketika , Padilla-Iglesias Cecilia , Ochoa Nicolás Restrepo , Knight V. Bleu
Published: April 2021

Central-place foraging, where foragers return to a central location (or home), is a key feature of hunter-gatherer social organization. Central-place foraging could have significantly changed hunter-gatherers’ use of space and mobility, and altered social networks and increased opportunities for information exchange. We evaluated whether central-place foraging patterns facilitate information transmission and considered the potential roles of environmental conditions and mobility strategies. We built an agent-based central-place foraging model where agents move according to a simple optimal foraging rule, and can encounter other agents as they move across the environment. They either forage close to their home within a given radius or move the location of their home to new areas. We analyzed the interaction networks arising across different environments and mobility strategies. We found that, at intermediate levels of environmental heterogeneity and mobility, central-place foraging increased global and local network efficiencies as well as the rate of contagion-based information transmission (simple and complex). We also assessed the effect of population density on the resultant networks and found that central-place mobility strategies can further improve information transmission in larger populations. Our findings suggest that the combination of foraging and movement strategies, as well as the underlying environmental conditions that characterized early human societies, may have been a crucial precursor in our species’ unique capacity to innovate, accumulate and rely on complex culture.
Caveolae Impacts Cellular RNA Levels through Transcription and Translational Processes
Authors: Qifti Androniqi , Balaji Shravani , Scarlata Suzanne
Published: April 2021

Caveolae are membrane domains that provide mechanical strength to cells and localize signaling molecules. Caveolae are composed of caveolin-1 or −3 (Cav1/3) molecules that assemble into domains with the help of cavin-1. Besides organizing caveolae, cavin-1, also known as Polymerase I and Transcript Release Factor (PTRF), promotes ribosomal RNA transcription in the nucleus. Cell expression of Cav1 and cavin-1 are linked. Here, we find that deforming caveolae by subjecting cells to mild osmotic stress (300 to 150 mOsm), changes the levels of cellular proteins (GAPDH, Hsp90 and Ras) change only when Cav1/cavin-1 levels are reduced suggesting link between caveolae deformation and protein expression. We find that this link may be due to relocalization of cavin-1 from the plasma membrane to the nucleus upon caveolae deformation caused by osmotic stress. Cavin-1 relocalization is also seen when Cav1-Gαq contacts change upon stimulation with carbachol. Cav1 and cavin-1 levels have profound effects on the amount of cytosolic RNA and the size distribution of these RNAs that in turn impact the ability of cells to form stress granules and RNA-processing bodies (p-bodies) that protect mRNA when cells are subjected to environmental stress. Studies using a cavin-1 knock-out cell line show adaptive changes in cytosolic RNA levels but a reduced ability to form stress granules. Our studies show that caveolae, through release of cavin-1, communicates mechanical and chemical cues to the cell interior to impact transcriptional and translational processes.
Ornament, armament, or toolkit? Modelling how population size drives the evolution of birdsong, a functional cultural trait
Authors: Hudson Emily J. , Creanza Nicole
Published: April 2021

Oscine songbirds have been an important study system for social learning, particularly because their learned songs provide an analog for human languages and music. Here we propose a different analogy; from an evolutionary perspective, could a bird’s song be more like an arrowhead than an aria? We modify a model of human tool evolution to accommodate cultural evolution of birdsong: each song learner chooses the most skilled available tutor to emulate, and each is more likely to produce an inferior copy than a superior one. Similarly to human tool evolution, we show that larger populations foster improvements in song over time, even when learners restrict their pool of tutors to a subset of individuals. We also demonstrate that songs could be simplified instead of lost after population bottlenecks if lower-quality traits are easier to imitate than higher-quality ones. We show that these processes could plausibly generate empirically observed patterns of song evolution, and we make predictions about the types of song elements most likely to be lost when populations shrink. More broadly, we aim to connect the modeling approaches used in human and non-human systems, moving toward a cohesive theoretical framework that accounts for both cognitive and demographic processes.
Tissue fixation effects on human retinal lipid analysis by MALDI imaging and LC-MS/MS technologies
Authors: Kotnala Ankita , Anderson David M.G. , Patterson Nathan Heath , Cantrell Lee S. , Messinger Jeffrey D. , Curcio Christine A. , Schey Kevin L.
Published: April 2021

Imaging mass spectrometry (IMS) allows the location and abundance of lipids to be mapped across tissue sections of human retina. For reproducible and accurate information, sample preparation methods need to be optimized. Paraformaldehyde fixation of a delicate multilayer structure like human retina facilitates the preservation of tissue morphology by forming methylene bridge cross-links between formaldehyde and amine/ thiols in biomolecules; however, retina sections analyzed by IMS are typically fresh-frozen. To determine if clinically significant inferences could be reliably based on fixed tissue, we evaluated the effect of fixation on analyte detection, spatial localization, and introduction of artefactual signals. Hence, we assessed the molecular identity of lipids generated by matrix-assisted laser desorption ionization (MALDI-IMS) and liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) for fixed and fresh-frozen retina tissues in positive and negative ion modes. Based on MALDI-IMS analysis, more lipid signals were observed in fixed compared to fresh-frozen retina. More potassium adducts were observed in fresh-frozen tissues than fixed as the fixation process caused displacement of potassium adducts to protonated and sodiated species in ion positive ion mode. LC-MS/MS analysis revealed an overall decrease in lipid signals due to fixation that reduced glycerophospholipids and glycerolipids and conserved most sphingolipids and cholesteryl esters. The high quality and reproducible information from untargeted lipidomics analysis of fixed retina informs on all major lipid classes, similar to fresh-frozen retina, and serves as a steppingstone towards understanding of lipid alterations in retinal diseases.
Marker-assisted mapping enables effective forward genetic analysis in the arboviral vector Aedes aegypti, a species with vast recombination deserts
Authors: Chen Chujia , Compton Austin , Nikolouli Katerina , Wang Aihua , Aryan Azadeh , Sharma Atashi , Qi Yumin , Delinger Camden , Hempel Melanie , Augustinos Antonios , Severson David W. , Bourtzis Kostas , Tu Zhijian
Published: April 2021

Aedes aegypti is a major vector of arboviruses that cause dengue, chikungunya, yellow fever and Zika. Although recent success in reverse genetics has facilitated rapid progress in basic and applied research, integration of forward genetics with modern technologies remains challenging in this important species, as up-to-47% of its chromosome is refractory to genetic mapping due to extremely low rate of recombination. Here we report the development of a marker-assisted-mapping (MAM) strategy to readily screen for and genotype only the rare but informative recombinants, drastically increasing both the resolution and signal-to-noise ratio. Using MAM, we mapped a transgene that was inserted in a >100 Mb recombination desert and a sex-linked spontaneous red-eye (re) mutation just outside the region. We subsequently determined, by CRISPR/Cas9-mediated knockout, that cardinal is the causal gene of re, which is the first forward genetic identification of a causal gene in Ae. aegypti. This study provides the molecular foundation for using gene-editing to develop versatile and stable genetic sexing methods by improving upon the current re-based genetic sexing strains. MAM does not require densely populated markers and can be readily applied throughout the genome to facilitate the mapping of genes responsible for insecticide- and viral-resistance. By enabling effective forward genetic analysis, MAM bridges a significant gap in establishing Ae. aegypti as a model system for research in vector biology. As large regions of suppressed recombination are also common in other plant and animal species including those of economic significance, MAM will have broad applications beyond vector biology.
Stability of microbiota in vineyard soils across consecutive years
Authors: Cestaro Alessandro , Coller Emanuela , Albanese Davide , Stefani Erika , Pindo Massimo , Ioriatti Cluadio , Zanzotti Roberto , Donati Caludio
Published: April 2021

Agricultural soils harbor rich and diverse microbial communities that have a deep influence on soil properties and productivity. Large scale studies have shown the impact of environmental parameters like climate or chemical composition on the distribution of bacterial and fungal species. Comparatively, little data exists documenting how soil microbial communities change between different years. Quantifying the temporal stability of soil microbial communities will allow us to better understand the relevance of the differences between environments and their impact on ecological processes on the global and local scale.

We characterized the bacterial and fungal components of the soil microbiota in ten vineyards in two consecutive years. Despite differences of species richness and diversity between the two years, we found a general stability of the taxonomic structure of the soil microbiota. Temporal differences were smaller than differences due to geographical location, vineyard land management or differences between sampling sites within the same vineyard. Using machine learning, we demonstrated that each site was characterized by a distinctive microbiota, and we identified a reduced set of indicator species that could classify samples according to their geographic origin across different years with high accuracy.

Importance

The temporal stability of the soil microbiota is important to understand the relevance of the differences that are found in response to a variety of environmental factors. By comparing fungal and bacterial microbiota from samples collected in the same sites in two consecutive years, we found a remarkable stability of both components, with characteristic differences between bacteria and fungi. Our work fills an important gap toward the definition of a microbial cartography of agricultural soils.
Subsynaptic positioning of AMPARs by LRRTM2 controls synaptic strength
Authors: Ramsey A.M. , Tang A.H. , LeGates T.A. , Gou X.Z. , Carbone B.E. , Thompson S.M. , Biederer T. , Blanpied T.A.
Published: April 2021

Recent evidence suggests that nanoorganization of proteins within synapses may control the strength of communication between neurons in the brain. The unique subsynaptic distribution of glutamate receptors, which cluster in nanoalignment with presynaptic sites of glutamate release, supports this idea. However, testing it has been difficult because mechanisms controlling subsynaptic organization remain unknown. Reasoning that transcellular interactions could position AMPA receptors, we targeted a key transsynaptic adhesion molecule implicated in controlling AMPAR number, LRRTM2, using engineered, rapid proteolysis. Severing the LRRTM2 extracellular domain led quickly to nanoscale de-clustering of AMPARs away from release sites, not prompting their escape from synapses until much later. This rapid remodeling of AMPAR position produced significant deficits in evoked, but not spontaneous, postsynaptic receptor activation. These results dissociate receptor numbers from their nanopositioning in determination of synaptic function, and support the novel concept that adhesion molecules acutely position AMPA receptors to dynamically control synaptic strength.
Glucose Uptake as an Alternative to Stop-Flow Respirometry for Measuring Metabolic Rate inDanio rerioLarvae
Authors: Evans Bridget L , Hurlstone Adam F L , Clayton Peter E , Stevens Adam , Shiels Holly A
Published: April 2021

Respirometry is the current gold-standard for measuring metabolic rate. However, there is a growing need for metabolic rate measurements suitable for developmental studies, particularly inDanio rerio, where many important developmental stages occur at < 4 mm. While many metabolic studies rely on respirometry, the cost and complexity of the equipment limits its appeal in non-specialist labs, and background respiration becomes increasingly problematic as the size of the organism reduces. Here, glucose uptake was compared to stop-flow respirometry as an alternative measure of metabolic rate more suitable to the small scale required for developmental studies. A Passing-Bablok regression revealed the rate of glucose uptake can be considered equivalent to oxygen consumption as a measure of metabolic rate inDanio reriolarvae within a 95% limit of agreement. Therefore, glucose uptake is a valid alternative to the gold-standard in small organisms where conventional respirometry is problematic.

Summary statement

The rate of glucose uptake is a valid alternative to respirometry for metabolic rate measurements in small larval fish.
Simplified heavy-atom derivatization of protein structures via co-crystallization with the MAD tetragon tetrabromoterephthalic acid
Authors: Truong Jia Q. , Nguyen Stephanie , Bruning John B. , Shearwin Keith E.
Published: April 2021

The phase problem is a persistent bottleneck that impedes the structure-determination pipeline and must be solved to obtain atomic resolution crystal structures of macromolecules. Although molecular replacement has become the predominant method of solving the phase problem, many scenarios still exist in which experimental phasing is needed. Here, a proof-of-concept study is presented that shows the efficacy of using tetrabromoterephthalic acid (B4C) as an experimental phasing compound. Incorporating B4C into the crystal lattice using co-crystallization, the crystal structure of hen egg-white lysozyme was solved using MAD phasing. The strong anomalous signal generated by its four Br atoms coupled with its compatibility with commonly used crystallization reagents render B4C an effective experimental phasing compound that can be used to overcome the phase problem.
Crystal structure of diaqua(3,14-diethyl-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosane)copper(II) dichloride tetrahydrate
Authors: Moon Dohyun , Choi Jong-Ha
Published: April 2021

The crystal structure of the novel hydrated CuII salt, [Cu(L)(H2O)2]Cl2·4H2O (L = 3,14-diethyl-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosane, C22H44N4) has been determined using synchrotron radiation. The asymmetric unit contains one half of the [Cu(L)(H2O)2]2+ cation (completed by crystallographic inversion symmetry), one chloride anion and two lattice water molecules. The copper(II) atom exists in a tetragonally distorted octahedral environment with the four N atoms of the macrocyclic ligand in equatorial and two O atoms from water molecules in axial positions. The latter exhibit a long axial Cu—O bond length of 2.7866 (16) Å due to the Jahn–Teller distortion. The macrocyclic ring adopts a stable trans-III conformation with typical Cu—N bond lengths of 2.0240 (11) and 2.0441 (3) Å. The complex is stabilized by hydrogen bonds formed between the O atoms of coordinated water molecules and the NH groups as donors, and chloride anions as acceptors. The chloride anions are further connected to the lattice water solvent molecules through O—H...Cl hydrogen bonds, giving rise to a three-dimensional network structure.
Crystal structure of {N
1,N
3-bis[(1-tert-butyl-1H-1,2,3-triazol-4-yl)methylidene]-2,2-dimethylpropane-1,3-diamine}bis(thiocyanato)iron(II)
Authors: Znovjyak Kateryna , Seredyuk Maksym , Malinkin Sergey O. , Golenya Iryna O. , Amirkhanov Vladimir M. , Shova Sergiu , Mulloev Nurullo U.
Published: April 2021

The unit cell of the title compound, [FeII(NCS)2(C19H32N8)], consists of two charge-neutral complex molecules. In the complex molecule, the tetradentate ligand N
1
,N
3-bis[(1-tert-butyl-1H-1,2,3-triazol-4-yl)methylene]-2,2-dimethylpropane-1,3-diamine coordinates to the FeII ion through the N atoms of the 1,2,3-triazole and aldimine groups. Two thiocyanate anions, also coordinated through their N atoms, complete the coordination sphere of the central Fe ion. In the crystal, neighbouring molecules are linked through weak C—H...C/S/N interactions into a three-dimensional network. The intermolecular contacts were quantified using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H...H 50.8%, H...C/C...H 14.3%, H...S/S...H 20.5% and H...N/N...H 12.1%. The average Fe—N bond distance is 2.170 Å, indicating the high-spin state of the FeII ion, which does not change upon cooling, as demonstrated by low-temperature magnetic susceptibility measurements. DFT calculations of energy frameworks at the B3LYP/6–31 G(d,p) theory level were performed to account for the interactions involved in the crystal structure.
Sampling touch DNA from human skin following skin‐to‐skin contact in mock assault scenarios—A comparison of nine collection methods
Authors: Kallupurackal Venus , Kummer Sonja , Voegeli Pamela , Kratzer Adelgunde , Dørum Guro , Haas Cordula , Hess Sabine
Published: April 2021

Collection of touch DNA from an offender on the victim's skin can provide relevant evidence for investigations of criminal cases. Therefore, the choice of the optimal sample collection method is crucial. In this study, we investigated the recovery of STR profiles from touch DNA on human skin by comparing nine different collection methods: the dry and wet cotton swabs in three different movements, the double‐swab (wet–dry) method, the wet and dry Copan FLOQSwabs™, and the Scene Safe FAST™ minitapes. Mock assault scenarios were conducted with a male offender grasping the forearms of a female victim. Samples were collected from the assaulted area of the victim's skin, and the recovery of the offender's STR profile was evaluated. Our results indicate that the different swabs and swabbing techniques did not have a distinct impact on the STR recovery; however, the lowest STR recovery was achieved with Scene Safe FAST™ minitapes. In addition, we compared the double‐swab method to the single‐swab method by analyzing the DNA quantity of the wet and dry swabs separately. We found on average 13.7% more offender DNA using the double‐swab method, but this did not translate into higher STR recovery. Our findings indicate that several methods perform equally well when collecting touch DNA from human skin, although SceneSafe FAST™ minitapes seem to be the least adequate for this purpose.
Biochemical properties of extracellular protease from Staphylococcus carnosus RT6 isolated from Harbin dry sausages, and its hydrolysis of meat proteins
Authors: Wang Hui , Wang Qiang , Xia Xiufang , Sun Fangda , Kong Baohua
Published: April 2021

The characteristics of the extracellular protease, produced by Staphylococcus carnosus RT6 isolated from Harbin dry sausages, and its hydrolysis of meat proteins were investigated. The protease was purified by ammonium sulfate, ion exchange, and gel filtration chromatography to obtain a 20.0 kDa extracellular protease. The protease reached maximal activity at pH 9.0 and 50 °C and was stable at pH 7.0 to 11.0 and 20 to 40 °C. Its protease activity was easily inhibited in the presence of Zn2+, Fe2+, and Fe3+. The enzymatic characterization of the protease revealed a Vmax 49.50 U/ml·min, Km 8.19 mg/ml, and the half‐life = 28.06 min, ΔH*d = 114.11 kJ/mol, ΔG*d = 89.24 kJ/mol, and ΔS*d = 77.00 J/mol·K at 50 °C. In addition, the protease hydrolyzed meat protein into small particles and produced soluble peptides. This study provides a basis for understanding the biochemical characteristics of the S. carnosus RT6 protease and its future application for fermented meat products.
CD8+ T cells actively penetrate hepatocytes via the CD44/p‐ERM/F‐actin pathway in autoimmune hepatitis
Authors: Liang Ju Bo , Chen Yong , Chen Rui Ling , Li Yi Kang , Li Bo , You Zheng Rui , Li You , Zhang Jun , Huang Bing Yuan , Wei Yi Ran , Lyu Zhu Wan , Lian Min , Xiao Xiao , Wang Qi Xia , Tang Ru Qi , Fang Jing Yuan , Chen Xiao Yu , Ma Xiong , Miao Qi
Published: April 2021

Objective

Emperipolesis is a pathological feature for the diagnosis of autoimmune hepatitis (AIH). We have previously found that CD8+ T cells participated in the emperipolesis in AIH. In this study we aimed to clarify the characteristics and molecular mechanisms of emperipolesis in patients with AIH in vitro and in mice with α‐Galactosylceramide (α‐GalCer)‐induced acute hepatitis.

Methods

The peripheral blood mononuclear cells (PBMC) of patients with various chronic liver diseases and healthy controls were co‐cultured with hepatic cell lines to induce emperipolesis in vitro. Confocal staining was performed to illustrate the cellular types and potential mechanisms of emperipolesis in AIH. In addition, a murine model of α‐GalCer‐induced acute hepatitis that mimics human AIH was used to confirm the role of CD44/p‐ERM/F‐actin in the emperipolesis process in vivo.

Results

In the co‐cultured system of PBMC and hepatic cell line, emperipolesis was observed most commonly in patients with AIH. The main cells participating in emperipolesis were CD8+ T cells, and they penetrated hepatic cells actively via the CD44/p‐ERM/F‐actin pathway. As a result, most CD8+ T cells engulfed by hepatic cells underwent apoptosis. In the α‐GalCer‐induced acute hepatitis model, emperipolesis was observed around the inflammatory foci and was inhibited by the ezrin phosphorylation inhibitor NSC668394. Similarly, activated murine CD8+ T cells penetrated primary hepatocytes via the CD44/p‐ERM/F‐actin pathway in vitro.

Conclusions

CD8+ T cells penetrate hepatic cells actively via the CD44/p‐ERM/F‐actin signaling pathway and undergo apoptosis. This may be a compensatory mechanism to attenuate the overwhelming immune attack in AIH.
A multiplex antigen microarray for simultaneous IgG and IgM detection against SARS‐CoV‐2 reveals higher seroprevalence than reported
Authors: Ruano‐Gallego David , García‐Villadangos Miriam , Moreno‐Paz Mercedes , Gómez‐Elvira Javier , Postigo Marina , Simón‐Sacristán María , Reyburn Hugh T. , Carolis Carlo , Rodrigo Natalia , Codeseira Yaiza B. , Rueda Paloma , Zúñiga Sonia , Enjuanes Luis , Parro Victor
Published: April 2021

The surge of SARS‐CoV‐2 has challenged health systems worldwide and efficient tests to detect viral particles, as well as antibodies generated against them, are needed. Specificity, sensitivity, promptness or scalability are the main parameters to estimate the final performance, but rarely all of them match in a single test. We have developed SCOVAM, a protein microarray with several viral antigens (spike, nucleocapsid, main protease Nsp5) as capturing probes in a fluorescence immunoassay for COVID‐19 serological testing. SCOVAM depicts IgG and IgM antibody responses against each of these proteins of 22 individuals in a single microscope slide. It detects specific IgM (0.094 μg ml‐1) and IgG (~0.017 μg ml‐1) and is scalable and cost‐effective. We validated SCOVAM by comparing with a widely used chemiluminescent commercial serological test (n = 742). SCOVAM showed twice the sensitivity and allowed following seroconversion in a single assay. By analysing the prevalence 4 months later in a subset of 76 positive sera, we still detected 93.42% of positives, almost doubling the detection of the commercial assay. The higher sensitivity of SCOVAM is especially relevant to screen sera for convalescent plasma‐based treatments, high‐throughput antibody response monitoring after vaccination or evaluation of vaccine efficiency.
Month of birth and mental disorders: A population‐based study and validation using global meta‐analysis
Authors: Hsu Chih‐Wei , Tseng Ping‐Tao , Tu Yu‐Kang , Lin Pao‐Yen , Hung Chi‐Fa , Liang Chih‐Sung , Hsieh Yun‐Yu , Yang Yao‐Hsu , Wang Liang‐Jen , Kao Hung‐Yu
Published: April 2021

Objective

Month of birth (MOB) is associated with specified mental disorders (MDs). However, whether these relationships extend to all MDs remains unclear. We investigate the association using a population‐based cohort study and a meta‐analysis.

Methods

First, we examined patients with 34 DSM‐5‐classified MDs in the Taiwan national database. We estimated the relative risk ratios (RR) of each illness in each MOB relative to that in the general population and assessed the periodicity, with six further sensitivity analyses. Second, we searched PubMed, Embase, and Cochrane for related articles through 31 December 2020. We used a random‐effects model, pooled RRs with 95% confidence intervals of each MOB from the identified studies, and transformed them from MOB to relative age in a year or season.

Results

The cohort included 1,951,777 patients. Except for posttraumatic stress disorder, dissociative disorders, feeding/eating disorders, gender dysphoria, and paraphilic disorders, the other MDs had significant MOB periodicity. The meta‐analysis included 51 studies investigating 10 MDs. The youngest age at the start of school owing to MOB was associated with the highest RRs of intellectual disability (1.13), autism (1.05), attention‐deficit/hyperactivity disorder (1.13). Winter births had significant risks of schizophrenia (1.04), bipolar I disorder (1.02), and major depressive disorder (1.01), and autumn births had a significant risk of alcohol use disorder (1.02). No significant associations between season of birth and Alzheimer's disease, or eating disorders were found.

Conclusions

MOB is related to the risks of certain MDs. This finding provides a reference for future research on the etiology of MDs.
Ten years of uterine rupture in an Australian tertiary hospital
Authors: Wu Christine , McGee Therese
Published: April 2021

Aims

Complete uterine rupture is a rare and serious complication of pregnancy. Although most commonly associated with attempted vaginal birth after caesarean (VBAC), rupture also occurs in atypical/non‐VBAC cases. This retrospective, single‐tertiary‐institution observational study aimed to assess the prevalence and morbidity of complete uterine rupture during 2010–2020.

Methods

Hospital discharge codes and local maternity databases identified uterine rupture cases, with medical record reviews confirming the diagnosis, distinguishing complete rupture from dehiscence, and extracting additional data. VBAC attempt was defined as planned labour trial after one prior caesarean.

Results

Over the decade, 27 complete ruptures occurred among 58 614 women, a rate of 4.6 per 10 000 births. One woman with three successive fundal ruptures had only the first included in further analysis, leaving 25 discrete women; 19 ruptures occurred in term planned VBAC attempts and six in preterm atypical/non‐VBAC cases (two nulliparas and four women with multiple prior caesareans). The VBAC‐attempt rupture rate was 0.74%, similar to published reports. All five perinatal deaths occurred in preterm atypical/non‐VBAC cases. In the term VBAC‐attempt group, rupture‐related perinatal morbidity included four cases (21%) of hypoxic‐ischaemic encephalopathy, with two cases (11%) of cerebral palsy at follow‐up. Overall, perinatal morbidity was highest with total fetal extrusion. Maternal blood loss ≥1500 mL or transfusion was almost threefold higher, and postnatal length‐of‐stay was three days longer, after vaginal than caesarean birth, with delay in rupture recognition being a factor.

Conclusion

A high suspicion index for uterine rupture is imperative during any labour, particularly in the scarred uterus, with vigilance continuing after successful vaginal birth.
Overcoming bacteriophage insensitivity in Staphylococcus aureus using clindamycin and azithromycinat subinhibitory concentrations
Authors: Liu Sha , Zhao Yin , Hayes Andrew , Hon Karen , Zhang Guimin , Bennett Catherine , Hu Hua , Finnie John , Morales Sandra , Shearwin Linda , Psaltis Alkis J. , Shearwin Keith , Wormald Peter‐John , Vreugde Sarah
Published: April 2021

Background

Staphylococcus aureus is a pathogen of major concern in both acute infections and chronic conditions such as chronic rhinosinusitis (CRS). Bacteriophage (phage) therapy has recently regained interest for its potential to treat infections caused by antibiotic resistant strains including Methicillin Resistant Staphylococcus aureus (MRSA). However, bacteria can adapt and become resistant to phages. The aim of this study is to determine the potential for antibiotics to overcome phage resistance.

Methods

The susceptibility of S. aureus clinical isolates (CIs) to phages J‐Sa36, Sa83 and Sa87 alone or in combination with protein synthesis inhibitor (PSI) antibiotics clindamycin, azithromycin and erythromycin was assessed using plaque spot assays, minimum inhibitory concentration (MIC) assays, double layer spot assays and resazurin assays. The safety and efficacy of subinhibitory PSI antibiotics in combination with phage was tested in a Sprague Dawley rat model of sinusitis infected with a phage resistant S. aureus CI.

Results

All three antibiotics at subinhibitory concentrations showed synergy when combined with all 3 phages against S. aureus CIs in planktonic and biofilm form and could sensitize phage‐resistant S. aureus to promote phage infection. The combination of topical subinhibitory clindamycin or azithromycin and phage was safe and could eradicate S. aureus sinonasal biofilms in vivo.

Conclusion

Subinhibitory concentrations of PSI antibiotics could sensitize phage‐resistant S. aureus and MRSA strains to phages in vitro and in vivo. This data supports the potential use of phage‐PSI antibiotic combination therapies, in particular for difficult‐to‐treat infections with phage‐resistant S. aureus and MRSA strains.