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pannexin 1 activation and inhibition is permeant-selective.the large-pore channel pannexin 1 (panx1) is expressed in many cell types and can open upon different, yet not fully established, stimuli. panx1 permeability is often inferred from channel permeability to fluorescent dyes, but it is currently unknown whether dye permeability translates to permeability to other molecules. cell shrinkage and c-terminal cleavage led to a panx1 open-state with increased permeability to atomic ions (current), but did not alter ethidium uptake. panx1 inhibitors affect ...202031698505
ligand binding characteristics of the ku80 von willebrand domain.the n-terminal von willebrand domain of ku80 supports interactions with a ku binding motif (kbm) that has been identified in at least three other dna repair proteins: the non-homologous end joining (nhej) scaffold aplf, the modulator of retrovirus infection, mri, and the werner syndrome protein (wrn). a second, more recently identified ku binding motif present in xlf and several other proteins (kbmx) has also been reported to interact with this domain. the isolated ku80 von willebrand antigen do ...202031733588
toward decoding bioelectric events in xenopus embryogenesis: new methodology for tracking interplay between calcium and resting potentials in vivo.although chemical signaling during embryogenesis is readily addressed by a plethora of available techniques, the developmental functions of ionic signaling are still poorly understood. it is increasingly realized that bioelectric events in nonneural cells are critical for pattern regulation, but their study has been hampered by difficulties in monitoring and manipulating them in vivo. recent developments in visualizing electrical signaling dynamics in the field of neuroscience have facilitated f ...202031711960
arabidopsis pic30 encodes a major facilitator superfamily transporter responsible for the uptake of picolinate herbicides.picloram is an auxinic herbicide that is widely used for controlling broad leaf weeds. however, its mechanism of transport into plants is poorly understood. in a genetic screen for picloram resistance, we identified three arabidopsis mutant alleles of pic30 (picloram resistant30) that are specifically resistant to picolinates, but not to other auxins. pic30 is a previously uncharacterized gene that encodes a major facilitator superfamily (mfs) transporter. similar to most members of mfs, pic30 c ...202031710151
serotonin and mucxs release by small secretory cells depend on xpod, a ssc specific marker gene.mucus secretion and ciliary motility are hallmarks for muco-ciliary epithelia (mce). both, mammalian airways as well as the less complex epidermis of xenopus embryos show cilia-driven mucus flow to protect the organism against harmful effects by exogenous pathogens or pollutants. four cell types set up the epidermal mce in xenopus. multi-ciliated cells (mccs) generate an anterior to posterior flow of mucus. ion secreting cells (iscs) are characterized by the expression of ion transporters, presu ...202031705622
tomato roots have a functional silicon influx transporter but not a functional silicon efflux transporter.silicon (si) accumulation in shoots differs greatly with plant species, but the molecular mechanisms for this interspecific difference are unknown. here, we isolated homologous genes of rice si influx (sllsi1) and efflux (sllsi2) transporter genes in tomato (solanum lycopersicum l.) and functionally characterized these genes. sllsi1 showed transport activity for si when expressed in both rice lsi1 mutant and xenopus laevis oocytes. sllsi1 was constitutively expressed in the roots. immunostaining ...202031724184
the flavor enhancer maltol increases pigment aggregation in dermal and neural melanophores in xenopus laevis tadpoles.melanophores are pigmented cells that change the distribution of melanosomes, enabling animals to appear lighter or darker for camouflage, thermoregulation, and protection from ultraviolet radiation. a complex series of hormonal and neural mechanisms regulates melanophore pigment distribution, making these dynamic cells a valuable tool to screen toxicants as they rapidly respond to changes in the environment. we found that maltol, a naturally occurring flavor enhancer and fragrance agent, induce ...202031721268
iron nanoparticle bio-interactions evaluated in xenopus laevis embryos, a model for studying the safety of ingested nanoparticles.iron nanoparticles (nps) have been proposed as a tool in very different fields such as environmental remediation and biomedical applications, including food fortification against iron deficiency, even if there is still concern about their safety. here, we propose xenopus laevis embryos as a suitable model to investigate the toxicity and the bio-interactions at the intestinal barrier of fe3o4 and zerovalent iron (zvi) nps compared to fe(ii) and (iii) salts in the 5 to 100 mg fe/l concentration ra ...202031718350
effect of triadimefon and its metabolite on adult amphibians xenopus laevis.the decrease in the population of amphibians all over the world has raised concerns. adult x. laevis frogs were exposed to 0, 1 and 10 mg/l triadimefon and triadimenol. after 14 or 28 days exposure, we collected male and female specimens to study swimming activity, lactic dehydrogenase (ldh) and antioxidant enzyme activity in blood samples, histopathology of liver and thyroid tissue, thyroid hormone levels and thyroid hormone-related gene expression levels in brains. our results showed that tria ...202031743868
apple almt9 requires a conserved c-terminal domain for malate transport underlying fruit acidity.malate accumulation in the vacuole largely determines apple (malus domestica) fruit acidity, and low fruit acidity is strongly associated with truncation of ma1, an ortholog of aluminum-activated malate transporter9 (almt9) in arabidopsis (arabidopsis thaliana). a mutation at base 1,455 in the open reading frame of ma1 leads to a premature stop codon that truncates the protein by 84 amino acids at its c-terminal end. here, we report that both the full-length protein, ma1, and its naturally occur ...202031772076
role of trka signaling during tadpole tail regeneration and early embryonic development in xenopus laevis.neurotrophic signaling regulates neural cell behaviors in development and physiology, although its role in regeneration has not been fully investigated. here, we examined the role of neurotrophic signaling in xenopus laevis tadpole tail regeneration. after the tadpole tails were amputated, the expression of neurotrophin ligand family genes, especially ngf and bdnf, was up-regulated as regeneration proceeded. moreover, notochordal expression of the ngf receptor gene trka, but not that of other ne ...202031788928
studying in vivo retinal progenitor cell proliferation in xenopus laevis.the efficient generation and maintenance of retinal progenitor cells (rpcs) are key goals needed for developing strategies for productive eye repair. although vertebrate eye development and retinogenesis are well characterized, the mechanisms that can initiate rpc proliferation following injury-induced regrowth and repair remain unknown. this is partly because endogenous rpc proliferation typically occurs during embryogenesis while studies of retinal regeneration have largely utilized adult (or ...202031786778
molecular characterization of the orphan transporter slc16a9, an extracellular ph- and na+-sensitive creatine transporter.human monocarboxylate transporters (hmcts) mediate the transport of monocarboxylates across plasma membranes. one such transporter, hmct9, has been shown to be related to serum uric acid levels and the risk of renal overload gout. however, the functional characteristics of hmct9 remain unknown. the aim of this study was to investigate the expression and localization of hmct9 using a xenopus laevis oocyte heterologous expression system and characterize its transport properties. kinetic analysis o ...202031784090
a glimpse of the peptide profile presentation by xenopus laevis mhc class i: crystal structure of pxela-uaa reveals a distinct peptide-binding groove.the african clawed frog, xenopus laevis, is a model species for amphibians. before metamorphosis, tadpoles do not efficiently express the single classical mhc class i (mhc-i) molecule xela-uaa, but after metamorphosis, adults express this molecule in abundance. to elucidate the ag-presenting mechanism of xela-uaa, in this study, the xela-uaa structure complex (pxela-uaag) bound with a peptide from a synthetic random peptide library was determined. the amino acid homology between the xela-uaa and ...202031776204
d-glucuronolactone attenuates para-xylene-induced defects in neuronal development and plasticity in xenopus tectum in vivo.xylene and its derivatives are known to be neurotoxic to the central nervous system of animals. our previous work has shown that para-xylene (px) can cause an increase in apoptotic cells and abnormal avoidance behavior in xenopus laevis. however, the mechanism underlying the impact of px on neuronal structural and functional plasticity is less clear. here, we examined the effects of px on neuronal development and plasticity in the developing optic tectum. we found that huc/d-positive neurons wer ...202031811891
analysis of clcnkb mutations at dimer-interface, calcium-binding site, and pore reveals a variety of functional alterations in clc-kb channel leading to bartter syndrome.pathological missense mutations in clcnkb gene give a wide spectrum of clinical phenotypes in bartter syndrome type iii patients. molecular analysis of the mutated clc-kb channels can be helpful to classify the mutations according to their functional alteration. we investigated the functional consequences of nine mutations in the clcnkb gene causing bartter syndrome. we first established that all tested mutations lead to decreased clc-kb currents. combining electrophysiological and biochemical m ...202031803959
endoplasmic reticulum transmembrane protein tmtc3 contributes to o-mannosylation of e-cadherin, cellular adherence, and embryonic gastrulation.protein glycosylation plays essential roles in protein structure, stability, and activity such as cell adhesion. the cadherin superfamily of adhesion molecules carry o-linked mannose glycans at conserved sites and it was recently demonstrated that the transmembrane and tetratricopeptide repeat-containing proteins 1-4 (tmtc1-4) gene products contribute to the addition of these o-linked mannoses. here, biochemical, cell biological, and organismal analysis was used to determine that tmtc3 supports ...202031851597
desensitization of nmda channels requires ligand binding to both glun1 and glun2 subunits to constrict the pore beside the activation gate.n-methyl-d-aspartate (nmda) receptor channels are activated by glutamate (or nmda) and glycine. the channels also undergo desensitization, which denotes decreased channel availability, after prolonged exposure to the activating ligands. glycine apparently has a paradoxical negative effect on desensitization, as the increase in ambient glycine in concentrations required for channel activation would increase sustained nmda receptor currents. we hypothesized that this classical "glycine-dependent d ...202031821563
active emigration from climate change-caused seawater intrusion into freshwater habitats.ecological risk assessment associated with seawater intrusions has been supported on the determination of lethal/sublethal effects following standard protocols that force exposure neglecting the ability of mobile organisms to spatially avoid salinized environments. thus, this work aimed at assessing active emigration from climate change-caused seawater intrusion into freshwater habitats. to specific objectives were delineated: first, to compute median 12-h avoidance conductivities (ac50,12h) for ...202031883492
heparan sulfate proteoglycans regulate bmp signalling during neural crest induction.bone morphogenetic protein (bmp) signalling is key to many developmental processes, including early regionalisation of the ectoderm. the neural crest is induced here by a combination of bmp and wnt signals from nearby tissues with many secreted factors contributing to its initial specification at the neural plate border. gremlin 1 (grem1) is a secreted bmp antagonist expressed in the neural crest in xenopus laevis but its function here is unknown. as well as binding bmps, grem1 has been shown to ...202031883440
distinct m6a methylome profiles in poly(a) rna from xenopus laevis testis and that treated with atrazine.recent discovery of reversible n6-methyladenosine (m6a) methylation on messenger rna (mrna) and mapping of m6a methylomes in mammals, plant and yeast revealed potential regulatory functions of this rna modification. however, the role of the m6a methylomes in amphibious is still poorly understood. here, we examined the m6a transcriptome-wide profile in testis tissues of xenopus laevis (x. laevis) with and without treatment with 100 μg/l atrazine (az) through m6a sequencing analysis using the late ...202031877456
transformation of receptor tyrosine kinases into glutamate receptors and photoreceptors.receptor tyrosine kinases (rtks) are key regulators of cellular functions in metazoans. in vertebrates, rtks are mostly activated by polypeptides but are not naturally sensitive to amino acids or light. taking inspiration from venus kinase receptors (vkrs), an atypical family of rtks found in nature, we have transformed the human insulin (hir) and hepatocyte growth factor receptor (hmet) into glutamate receptors by replacing their extracellular binding domains with the ligand-binding domain of m ...202031872568
modeling ocular lens disease in xenopus.ocular lens clouding is termed as cataract, which depending on the onset, is classified as congenital or age-related. developing new cataract treatments requires new models. thus far, xenopus embryos have not been evaluated as a system for studying cataract.202031872467
bupropion inhibits serotonin type 3ab heteromeric channels at clinically relevant concentrations.bupropion, a food and drug administration-approved antidepressant and smoking cessation aid, blocks dopamine and norepinephrine reuptake transporters and noncompetitively inhibits nicotinic acetylcholine and serotonin (5-ht) type 3a receptors (5-ht3ars). 5-ht3 receptors are pentameric ligand-gated ion channels that regulate synaptic activity in the central and peripheral nervous system, presynaptically and postsynaptically. in the present study, we examined and compared the effect of bupropion a ...202031871303
the γ-hydroxybutyric acid (ghb) analogue ncs-382 is a substrate for both monocarboxylate transporters subtypes 1 and 4.the small-molecule ligand (e)-2-(5-hydroxy-5,7,8,9-tetrahydro-6h-benzo[7]annulen-6-ylidene)acetic acid (ncs-382) is an analogue of γ-hydroxybutyric acid (ghb) and is widely used for probing the brain-specific ghb high-affinity binding sites. to reach these, brain uptake is imperative, and it is therefore important to understand the molecular mechanisms of ncs-382 transport in order to direct in vivo studies. in this study, we hypothesized that ncs-382 is a substrate for the monocarboxylate trans ...202031866563
applying tensile and compressive force to xenopus animal cap tissue.over many years, the xenopus laevis embryo has provided a powerful model system to investigate how mechanical forces regulate cellular function. here, we describe a system to apply reproducible tensile and compressive force to x. laevis animal cap tissue explants and to simultaneously assess cellular behavior using live confocal imaging.202031857437
insights into the assembly and activation of the microtubule nucleator γ-turc.microtubules are dynamic polymers of α- and β-tubulin and have crucial roles in cell signalling, cell migration, intracellular transport and chromosome segregation1. they assemble de novo from αβ-tubulin dimers in an essential process termed microtubule nucleation. complexes that contain the protein γ-tubulin serve as structural templates for the microtubule nucleation reaction2. in vertebrates, microtubules are nucleated by the 2.2-megadalton γ-tubulin ring complex (γ-turc), which comprises γ-t ...202031856152
organ-specific requirements for thyroid hormone receptor ensure temporal coordination of tissue-specific transformations and completion of xenopus metamorphosis.background: thyroid hormone (triiodothyronine [t3]) is essential for the development throughout vertebrates. anuran metamorphosis mimics mammalian postembryonic development, a period around birth when plasma t3 level peaks and many organs/tissues mature into their adult forms. compared with the uterus-enclosed mammalian embryos, tadpoles can be easily manipulated to study the roles of t3 and t3 receptors (trs) in tissue remodeling and adult organ development. we and others have previously knocke ...202031854240
adverse effects of fly ashes used as immobilizing agents for highly metal-contaminated soils on xenopus laevis oocytes survival and maturation-a study performed in the north of france with field soil extracts.amphibians are now recognized as the most endangered group. one of this decline causes is the degradation of their habitat through direct contamination of water, soil leaching, or runoff from surrounding contaminated soils and environments. in the north of france, the extensive industrial activities resulted in massive soil contamination by metal compounds. mineral amendments were added to soils to decrease trace metal mobility. because of the large areas to be treated, the use of inexpensive in ...202030875069
coexposure to environmental concentrations of cis-bifenthrin and graphene oxide: adverse effects on the nervous system during metamorphic development of xenopus laevis.despite the great concerns associated with the combined biological effects of nanoparticles and insecticides, the current understanding of the corresponding ecological risks remains limited. xenopus laevis (x. laevis) tadpoles were exposed to various concentrations of typical pyrethroid (cis-bifenthrin; cis-bf), either alone or in combination with graphene oxide (go), for 21 days. the presence of go resulted in increased bioconcentration of cis-bf and a higher 1s-enantiomer fraction. exposure to ...202031425913
smooth muscle in cardiac chambers is common in turtles and extensive in the emydid turtle, trachemys scripta.a prominent layer of smooth muscle lining the luminal side of the atria of freshwater turtles (emydidae) was described more than a century ago. we recently demonstrated that this smooth muscle provides a previously unrecognized mechanism to change cardiac output in the emydid red-eared slider (trachemys scripta) that possibly contributes to their tremendous diving capacity. the purpose of the present immunohistochemical study was firstly to screen major groups of vertebrates for the presence of ...202031509333
leishmania heme uptake involves lmflvcrb, a novel porphyrin transporter essential for the parasite.leishmaniasis comprises a group of neglected diseases caused by the protozoan parasite leishmania spp. as is the case for other trypanosomatid parasites, leishmania is auxotrophic for heme and must scavenge this essential compound from its human host. in mammals, the slc transporter flvcr2 mediates heme import across the plasma membrane. herein we identify and characterize leishmania major flvcrb (lmflvcrb), the first member of the flvcr family studied in a non-metazoan organism. this protein lo ...202031372684
sorafenib activity and disposition in liver cancer does not depend on organic cation transporter 1.systemic therapy of advanced hepatocellular carcinoma (hcc) with the small-molecule multikinase inhibitor sorafenib is associated with large interindividual pharmacokinetic variability and unpredictable side effects potentially requiring dose reduction or treatment termination. organic cation transporter (oct1; gene slc22a1) has been proposed as a clinical biomarker of hcc response. because proof is lacking that oct1 transports sorafenib, we used a combinatorial approach to define how oct1 contr ...202031350763
effects of glyphosate and a commercial formulation roundup® exposures on maturation of xenopus laevis oocytes.pesticides are often found at high concentrations in small ponds near agricultural field where amphibians are used to live and reproduce. even if there are many studies on the impacts of phytopharmaceutical active ingredients in amphibian toxicology, only a few are interested in the earlier steps of their life cycle. while their populations are highly threatened with extinction. the aim of this work is to characterize the effects of glyphosate and its commercial formulation roundup® gt max on th ...202030835066
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
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
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