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sclerostin inhibits wnt signaling through tandem interaction with two lrp6 ectodomains.low-density lipoprotein receptor-related protein 6 (lrp6) is a coreceptor of the β-catenin-dependent wnt signaling pathway. the lrp6 ectodomain binds wnt proteins, as well as wnt inhibitors such as sclerostin (sost), which negatively regulates wnt signaling in osteocytes. although lrp6 ectodomain 1 (e1) is known to interact with sost, several unresolved questions remain, such as the reason why sost binds to lrp6 e1e2 with higher affinity than to the e1 domain alone. here, we present the crystal ...202033097721
high affinity na+ transport by wheat hkt1;5 is blocked by k.the wheat sodium transporters tmhkt1;5-a and tahkt1;5-d are encoded by genes underlying the major shoot na+ exclusion loci nax2 and kna1 from triticum monococcum (tm) and triticum aestivum (ta), respectively. in contrast to hkt2 transporters that have been shown to exhibit high affinity k+-dependent na+ transport, hkt1 proteins have, with one exception, only been shown to catalyze low affinity na+ transport and no k+ transport. here, using heterologous expression in xenopus laevis oocytes we unc ...202033103046
amiodarone bioconcentration and suppression of metamorphosis in xenopus.trace concentrations of a number of pharmaceutically active compounds have been detected in the aquatic environment in many countries, where they are thought to have the potential to exert adverse effects on non-target organisms. amiodarone (amd) is one such high-risk compound commonly used in general hospitals. amd is known to alter normal thyroid hormone (th) function, although little information is available regarding the specific mechanism by which this disruption occurs. anuran tadpole meta ...202032956954
aquaporin expression in the alimentary canal of the honey bee apis mellifera l. (hymenoptera: apidae) and functional characterization of am_eglp 1.aquaporins (aqp) are a family of plasma membrane proteins responsible for water transport through cell membranes. they are differentially expressed in different parts of the alimentary canal of insects where they regulate water transport. these proteins have been studied in detail in some insects, but few data are available for aquaporins of the honey bee, apis mellifera. we used quantitative pcr to study the expression of six putative aquaporin genes in forager honey bees. we found differential ...202032956406
rad21 is involved in corneal stroma development by regulating neural crest migration.previously, we identified rad21r450c from a peripheral sclerocornea pedigree. injection of this rad21 variant mrna into xenopus laevis embryos disrupted the organization of corneal stroma fibrils. to understand the mechanisms of rad21-mediated corneal stroma defects, gene expression and chromosome conformation analysis were performed using cells from family members affected by peripheral sclerocornea. both gene expression and chromosome conformation of cell adhesion genes were affected in cells ...202033096935
phosphoproteomic analysis of xenopus laevis reveals expression and phosphorylation of hypoxia-inducible pfkfb3 during dehydration.xenopus laevis tolerate dehydration when their environments evaporate during summer months. protein phosphorylation has previously shown to regulate important adaptations in x. laevis, including the transition to anaerobic metabolism. we therefore performed phosphoproteomic analysis of x. laevis to further elucidate the cellular and metabolic responses to dehydration. phosphoproteins were enriched in cellular functions and pathways related to glycolysis/gluconeogenesis, the tca cycle, and protei ...202033083755
microtubule-dependent pushing forces contribute to long-distance aster movement and centration in xenopus laevis egg extracts.during interphase of the eukaryotic cell cycle, the microtubule (mt) cytoskeleton serves as both a supportive scaffold for organelles and an arborized system of tracks for intracellular transport. at the onset of mitosis, the position of the astral mt network, specifically its center, determines the eventual location of the spindle apparatus and ultimately the cytokinetic furrow. positioning of the mt aster often results in its movement to the center of a cell, even in large blastomeres hundreds ...202033026931
ecotoxicological assessment of commercial boron nitride nanotubes toward xenopus laevis tadpoles and host-associated gut microbiota.despite the growing interest for boron nitride nanotubes (bnnt) due to their unique properties, data on the evaluation of the environmental risk potential of this emerging engineered nanomaterial are currently lacking. therefore, the ecotoxicity of a commercial form of bnnt (containing tubes, hexagonal-boron nitride, and boron) was assessed in vivo toward larvae of the amphibian xenopus laevis. following the exposure, multiple endpoints were measured in the tadpoles as well as in bacterial commu ...202033171057
mechanisms activating latent functions of pip aquaporin water channels via the interaction between pip1 and pip2 proteins.plant plasma-membrane type pip aquaporins are classified into two groups, pip1s and pip2s. in this study, we focused on hvpip1; 2, a pip1 in barley (hordeum vulgare), to dissect the molecular mechanisms that evoke hvpip1-mediated water transport. no hvpip1; 2 protein was localized to the plasma membrane when expressed alone in xenopus laevis oocytes. in contrast, a chimeric hvpip1; 2 protein (hvpip1; 2_24nc), in which the n- and c-terminal regions were replaced with the corresponding regions fro ...202033169164
cross-talk between p2x and nmda receptors.purinergic p2x receptors (p2x) are atp-gated ion channels widely expressed in the cns. while the direct contribution of p2x to synaptic transmission is uncertain, p2x reportedly affect n-methyl-d-aspartate receptor (nmdar) activity, which has given rise to competing theories on the role of p2x in the modulation of synapses. however, p2x have also been shown to participate in receptor cross-talk: an interaction where one receptor (e.g., p2x2) directly influences the activity of another (e.g., nic ...202033003406
nicotinic acetylcholine receptors in the synganglion of the tick ixodes ricinus: functional characterization using membrane microtransplantation.nicotinic acetylcholine receptors are an important class of excitatory receptors in the central nervous system of arthropods. in the ticks ixodes ricinus, the functional and pharmacological properties of nicotinic receptors located in their neurons are still unknown. the objective of this study was to characterize the pharmacological properties of tick nicotinic receptors using membrane microtransplantation in xenopus laevis oocytes and two-electrodes voltage clamp method. the membranes microtra ...202033120248
observation of nucleic acids inside living human cells by in-cell nmr spectroscopy.the intracellular environment is highly crowded with biomacromolecules such as proteins and nucleic acids. under such conditions, the structural and biophysical features of nucleic acids have been thought to be different from those in vitro. to obtain high-resolution structural information on nucleic acids in living cells, the in-cell nmr method is a unique tool. following the first in-cell nmr measurement of nucleic acids in 2009, several interesting insights were obtained using xenopus laevis ...202033110737
derivation of proliferative islet1-positive cells during metamorphosis and wound response in xenopus.in mammalian hearts, cardiomyocytes retain a transient capacity to proliferate and regenerate following injury before birth, whereas they lose proliferative capacity immediately after birth. it has also been known that cardiac progenitor cells including islet1-positive cells do not contribute to the cardiac repair and regeneration in mammals. in contrast, hearts of zebrafish, amphibians and reptiles maintain a regenerative ability throughout life. here, we analyzed proliferative capacity of card ...202033070205
non-junctional role of cadherin3 in cell migration and contact inhibition of locomotion via domain-dependent, opposing regulation of rac1.classical cadherins are well-known adhesion molecules responsible for physically connecting neighboring cells and signaling this cell-cell contact. recent studies have suggested novel signaling roles for "non-junctional" cadherins (njcads); however, the function of cadherin signaling independent of cell-cell contacts remains unknown. in this study, mesendodermal cells and tissues from gastrula stage xenopus laevis embryos demonstrate that deletion of extracellular domains of cadherin3 (cdh3; for ...202033060598
dna content contributes to nuclear size control in xenopus laevis.cells adapt to drastic changes in genome quantity during evolution and cell division by adjusting the nuclear size to exert genomic functions. however, the mechanism by which dna content within the nucleus contributes to controlling the nuclear size remains unclear. here, we experimentally evaluated the effects of dna content by utilizing cell-free xenopus egg extracts and imaging of in vivo embryos. upon manipulation of dna content while maintaining cytoplasmic effects constant, both plateau si ...202032997613
torc1 selectively regulates synaptic maturation and input convergence in the developing visual system.newly synthesized proteins support the development of functional neural circuits and previous work has suggested that dysregulated translation mediates certain forms of autism spectrum disorder (asd). here, we investigated the role of target of rapamycin complex 1 (torc1) in synaptic and dendritic development in vivo in the retinotectal system of xenopus laevis tadpoles. we found that torc1 signaling regulates dendritic growth and branching and that acute over-activation of torc1 by rheb overexp ...202032996262
effect of 158 herbal remedies on human trpv1 and the two-pore domain potassium channels kcnk2, 3 and 9.herbal medicines are used to treat a broad number of maladies. however, the pharmacological profile of most remedies is poorly understood. we investigated the effect of herbal remedies from kampo, traditional chinese medicine (tcm) and other phytotherapies on human two-pore domain potassium channels (kcnk channels; trek-1, task-1 and task-3) as well as the human trpv1 channel. kcnk channels are responsible for the background potassium current of excitable cells, thus essential for the maintenanc ...202032953560
design, synthesis, and in vitro evaluation of p2x7 antagonists.the p2x7 receptor is a promising target for the treatment of various diseases due to its significant role in inflammation and immune cell signaling. this work describes the design, synthesis, and in vitro evaluation of a series of novel derivatives bearing diverse scaffolds as potent p2x7 antagonists. our approach was based on structural modifications of reported (adamantan-1-yl)methylbenzamides able to inhibit the receptor activation. the adamantane moieties and the amide bond were replaced, an ...202032964578
endoparasites infecting exotic captive amphibian pet and zoo animals (anura, caudata) in germany.alongside exotic reptiles, amphibians, such as toads, frogs, salamanders, and newts, are nowadays considered popular pets worldwide. as reported for other exotic pet animals, amphibians are known to harbor numerous gastrointestinal parasites. nonetheless, very little data are available on captive amphibian parasitic diseases. in this study, we applied direct saline fecal smears (dsfs) to examine in total 161 stool samples from 41 different amphibian species belonging to the orders anura and caud ...202032960371
scorpion toxin meunatxα-1 sensitizes primary nociceptors by selective modulation of voltage-gated sodium channels.venoms are a rich source of highly specific toxins, which allow the identification of novel therapeutic targets. we have now applied high content screening (hcs) microscopy to identify toxins that modulate pain sensitization signaling in primary sensory neurons of rat and elucidated the underlying mechanism. a set of venoms and fractions thereof were analyzed for their ability to activate type ii protein kinase a (pka-ii) and extracellular signal-regulated kinases (erk1/2). we identified meunatx ...202033051988
glutamate, d-(-)-2-amino-5-phosphonopentanoic acid, and n-methyl-d-aspartate do not directly modulate glycine receptors.replication studies play an essential role in corroborating research findings and ensuring that subsequent experimental works are interpreted correctly. a previously published paper indicated that the neurotransmitter glutamate, along with the compounds n-methyl-d-aspartate (nmda) and d-(-)-2-amino-5-phosphonopentanoic acid (ap5), acts as positive allosteric modulators of inhibitory glycine receptors. the paper further suggested that this form of modulation would play a role in setting the spina ...202033051383
establishing embryonic territories in the context of wnt signaling.this review highlights the work that my research group has been developing, together with international collaborators, during the last decade. since we were able to establish xenopus laevis experimental model in brazil we have been focused on understanding early embryonic patterns regarding neural induction and axes establishment. in this context, wnt pathway appears as a major player and has been much explored by us and other research groups. here we chose to review three published works that w ...202032930371
a collision coupling model governs the activation of neuronal girk1/2 channels by muscarinic-2 receptors.the g protein-activated inwardly rectifying k+-channel (girk) modulates heart rate and neuronal excitability. following g-protein coupled receptor (gpcr)-mediated activation of heterotrimeric g proteins (gαβγ), opening of the channel is obtained by direct binding of gβγ subunits. interestingly, girks are solely activated by gβγ subunits released from gαi/o-coupled gpcrs, despite the fact that all receptor types, for instance gαq-coupled, are also able to provide gβγ subunits. it is proposed that ...202032903404
diversity of parasites from xenopus laevis (amphibia: pipidae) and their seasonal rate of infection in selected habitats in the limpopo province, south africa.this study determined the diversity and seasonality of parasites species of the african clawed frog, xenopus laevis (daudin, 1802), from three localities, namely modjadjikloof, mokopane and university of limpopo, limpopo province, south africa. a total of seven parasite species were collected and identified. they included two nematodes, camallanus kaapstaadi southwell & kirshner, 1937 and batrachocamallanus slomei (southwell & kirshner, 1937), a monogenean, protopolystoma xenopodis (price, 1943) ...202032855613
blood-brain barrier protein claudin-5 expressed in paired xenopus laevis oocytes mediates cell-cell interaction.claudin-5 determines the sealing properties of blood-brain barrier tight junctions and its function is impaired in neurodegenerative and neuroinflammatory disorders. focusing on the contribution of claudin-5 to the trans-interaction within the tight junction seal, we used xenopus laevis oocytes as an expression system. cells were clustered and challenged in a novel approach for the analysis of claudin interaction. we evaluated the strengthening effect of claudin-5 to cell-cell-connection in comp ...202032848831
a survey of barley pip aquaporin ionic conductance reveals ca2+-sensitive hvpip2;8 na+ and k+ conductance.some plasma membrane intrinsic protein (pip) aquaporins can facilitate ion transport. here we report that one of the 12 barley pips (pip1 and pip2) tested, hvpip2;8, facilitated cation transport when expressed in xenopus laevis oocytes. hvpip2;8-associated ion currents were detected with na+ and k+, but not cs+, rb+, or li+, and was inhibited by ba2+, ca2+, and cd2+ and to a lesser extent mg2+, which also interacted with ca2+. currents were reduced in the presence of k+, cs+, rb+, or li+ relativ ...202032992595
inferring a complete genotype-phenotype map from a small number of measured phenotypes.understanding evolution requires detailed knowledge of genotype-phenotype maps; however, it can be a herculean task to measure every phenotype in a combinatorial map. we have developed a computational strategy to predict the missing phenotypes from an incomplete, combinatorial genotype-phenotype map. as a test case, we used an incomplete genotype-phenotype dataset previously generated for the malaria parasite's 'chloroquine resistance transporter' (pfcrt). wild-type pfcrt (pfcrt3d7) lacks signif ...202032991585
the mechanism of nmda receptor hyperexcitation in high pressure helium and hyperbaric oxygen.professional divers exposed to pressures greater than 1.1 mpa may suffer from the high pressure neurological syndrome (hpns). divers who use closed-circuit breathing apparatus face the risk of cns hyperbaric oxygen toxicity (hbotox). both syndromes are characterized by reversible cns hyperexcitability, accompanied by cognitive and motor deficits. previous studies have demonstrated that the hyperexcitability of hpns is induced mainly by nmda receptors (nmdars). in our recent studies, we demonstra ...202032982789
in-cell nmr spectroscopy of functional riboswitch aptamers in eukaryotic cells.we report here the in-cell nmr-spectroscopic observation of the binding of the cognate ligand 2'-deoxyguanosine to the aptamer domain of the bacterial 2'-deoxyguanosine-sensing riboswitch in eukaryotic cells, namely xenopus laevis oocytes and in human hela cells. the riboswitch is sufficiently stable in both cell types to allow for detection of binding of the ligand to the riboswitch. most importantly, we show that the binding mode established by in vitro characterization of this prokaryotic rib ...202032975353
do muscle contractile properties drive differences in locomotor performance in invasive populations of xenopus laevis in france?jumping and swimming are key locomotor traits in frogs intimately linked to survival and dispersal. french populations of the frog xenopus laevis from the invasion front are known to possess greater terrestrial locomotor endurance. here, we tested whether individuals from the invasion front show differences in their muscle physiology that may underlie the observed whole-organism performance differences. we measured muscle contractile properties of the isolated gastrocnemius muscle in vitro, incl ...202032955613
whole-brain calcium imaging in larval xenopus.sensory systems detect environmental stimuli and transform them into electrical activity patterns interpretable by the central nervous system. en route to higher brain centers, the initial sensory input is successively transformed by interposed secondary processing centers. mapping the neuronal activity patterns at all of those stages is essential to understand sensory information processing. larval xenopus laevis is very well-suited for whole-brain imaging of neuronal activity. this is mainly d ...202033037078
elucidating the framework for specification and determination of the embryonic retina.how cell determination is regulated remains a major unsolved problem in developmental biology. the early embryonic rudiments of many tissues and organs are difficult or impossible to identify, isolate and study at the time when determination occurs. we have examined the commitment process leading to retina formation in xenopus laevis, where presumptive eye tissue can be identified and studied to assay its biological properties during the events leading up to determination. we find that for the r ...202033031807
a simple and efficient method for visualizing individual cells in vivo by cre-mediated single-cell labeling by electroporation (cremscle).efficient methods for visualizing cell morphology in the intact animal are of great benefit to the study of structural development in the nervous system. quantitative analysis of the complex arborization patterns of brain cells informs cell-type classification, dissection of neuronal circuit wiring, and the elucidation of growth and plasticity mechanisms. time-lapse single-cell morphological analysis requires labeling and imaging of single cells in situ without contamination from the ramified pr ...202032848634
na+ transporter svhkt1;1 from a halophytic turf grass is specifically upregulated by high na+ concentration and regulates shoot na+ concentration.we characterized an na+ transporter svhkt1;1 from a halophytic turf grass, sporobolus virginicus. svhkt1;1 mediated inward and outward na+ transport in xenopus laevis oocytes and did not complement k+ transporter-defective mutant yeast. svhkt1;1 did not complement athkt1;1 mutant arabidopsis, suggesting its distinguishable function from other typical hkt1 transporters. the transcript was abundant in the shoots compared with the roots in s. virginicus and was upregulated by severe salt stress (50 ...202032847126
xenopus deep cell aggregates: a 3d tissue model for mesenchymal-to-epithelial transition.mesenchymal-to-epithelial transition (met) describes the ability of loosely associated migratory cells to form a more adherent sheet-like assembly of cells. met is a conserved motif occurring throughout organogenesis and plays a key role in regeneration and cancer metastasis, and is the first step in producing induced pluripotent stem cells (ipscs). to resolve fundamental biological questions about met, its relation to epithelial-to-mesenchymal transition, and to explore met's role in tissue ass ...202132939727
characterizing channelrhodopsin channel properties via two-electrode voltage clamp and kinetic modeling.two-electrode voltage clamp (tevc) is a preferred electrophysiological technique used to study gating kinetics and ion selectivity of light-activated channelrhodopsins (chrs). the method uses two intracellular microelectrodes to hold, or clamp, the membrane potential at a specific value and measure the flow of ions across the plasma membrane. here, we describe the use of tevc and a simple solution exchange protocol to measure cation selectivity and analyze gating kinetics of the c1c2 chimera exp ...202132865738
epigenetic control of myeloid cells behavior by histone deacetylase activity (hdac) during tissue and organ regeneration in xenopus laevis.in the present work we have focused on the histone deacetylase (hdac) control of myeloid cells behavior during xenopus tail regeneration. here we show that myeloid differentiation is crucial to modulate the regenerative ability of xenopus tadpoles in a hdac activity-dependent fashion. hdac activity inhibition during the first wave of myeloid differentiation disrupted myeloid cells dynamics in the regenerative bud as well the mrna expression pattern of myeloid markers, such as lurp, mpox, spib an ...202132858087
clearance of activity-evoked k+ transients and associated glia cell swelling occur independently of aqp4: a study with an isoform-selective aqp4 inhibitor.the mammalian brain consists of 80% water, which is continuously shifted between different compartments and cellular structures by mechanisms that are, to a large extent, unresolved. aquaporin 4 (aqp4) is abundantly expressed in glia and ependymal cells of the mammalian brain and has been proposed to act as a gatekeeper for brain water dynamics, predominantly based on studies utilizing aqp4-deficient mice. however, these mice have a range of secondary effects due to the gene deletion. an efficie ...202132506554
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