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in vitro inhibition of human nucleoside transporters and uptake of azacitidine by an isocitrate dehydrogenase-2 inhibitor enasidenib and its metabolite agi-16903.1. the present study investigated inhibitory effects of enasidenib and its metabolite agi-16903 on (a) recombinant human nucleoside transporters (hnts) in hnt-producing xenopus laevis oocytes, and (b) azacitidine uptake in a normal b-lymphoblast peripheral blood cell line (pbc) and acute myeloid leukemia (aml) cell lines. 2. enasidenib inhibited hent1, hent2, hent3, and hent4 in oocytes with ic50 values of 7, 63, 27, and 76 μm, respectively, but exhibited little inhibition of hcnt1-3. agi-16903 ...201930394160
paracetamol-induced liver injury modelled in xenopus laevis embryos.failure to predict drug-induced liver injury (dili) remains a major contributing factor to lead compound drop-out during drug development. xenopus embryos are amenable for early stage medium throughput small molecule screens and so have the potential to be used in pre-clinical screens. to begin to assess the usefulness and limitations of xenopus embryos for safety assessment in the early phases of drug development, paracetamol was used as a model hepatotoxin. paracetamol overdose is associated w ...201930282005
conservation and divergence of protein pathways in the vertebrate heart.heart disease is the leading cause of death in the western world. attaining a mechanistic understanding of human heart development and homeostasis and the molecular basis of associated disease states relies on the use of animal models. here, we present the cardiac proteomes of 4 model vertebrates with dual circulatory systems: the pig (sus scrofa), the mouse (mus musculus), and 2 frogs (xenopus laevis and xenopus tropicalis). determination of which proteins and protein pathways are conserved and ...201931490923
discovery of the arp2 protein as a determining molecule in tumor cell death.cancer is a multifactorial disease that constitutes a serious public health problem worldwide. prostate cancer advanced stages are associated with the development of androgen-independent tumors and an apoptosis-resistant phenotype that progresses to metastasis. by studying androgen-independent lymphoid nodule carcinoma of the prostate (lncap) cells induced to apoptosis by serum elimination, we identified the activation of a non-selective cationic channel of 23ps conductance that promotes incomin ...201932091029
descubrimiento de la proteína reguladora de apoptosis 2 como determinante en la muerte de células tumorales.cancer is a multifactorial disease that constitutes a serious public health problem worldwide. prostate cancer advanced stages are associated with the development of androgen-independent tumors and an apoptosis-resistant phenotype that progresses to metastasis. by studying androgen-independent lymphoid nodule carcinoma of the prostate (lncap) cells induced to apoptosis by serum elimination, we identified the activation of a non-selective cationic channel of 23ps conductance that promotes incomin ...201931695224
a flipr assay for discovery of gabaa receptor modulators of natural origin.a fluorometric imaging plate reader (flipr) assay utilizing chinese hamster ovary (cho) cells stably transfected with gabaa receptors of α1β2γ2 subunit composition was evaluated and validated for rapid screening of plant extract libraries and efficient localization of active compounds in extracts. validation was performed with pure compounds and extracts known to contain allosteric gabaa receptor modulators. plants extracts that had been previously reported as active in an assay using xenopus la ...201931127604
[exploring the mysteries of megakaryocytopoiesis and thrombopoiesis through comparative hematology].in modern hematology, research on hematopoiesis and blood cells in vertebrates, such as birds, reptiles, amphibians, and fish, is lagging. this is because there are many experimental constraints when selecting subjects other than humans and mice as research subjects. currently, the availability of flow cytometry to count classified nucleated blood cells and utilization of whole genome information have led to novel findings. for example, in case of amphibian hematopoiesis studies, megakaryocytes ...201931597828
distinct host-mycobacterial pathogen interactions between resistant adult and tolerant tadpole life stages of xenopus laevis.mycobacterium marinum is a promiscuous pathogen infecting many vertebrates, including humans, whose persistent infections are problematic for aquaculture and public health. among unsettled aspects of host-pathogen interactions, the respective roles of conventional and innate-like t (it) cells in host defenses against m. marinum remain unclear. in this study, we developed an infection model system in the amphibian xenopus laevis to study host responses to m. marinum at two distinct life stages, t ...201931591148
different pharmacological properties of glut9a and glut9b: potential implications in preeclampsia.glucose transporter 9 (glut9/slc2a9) is the major regulator of uric acid homeostasis in humans. hyperuricemia due to impaired regulation by glut9 in pregnancy is closely associated with preeclampsia. while glut9 is expressed in two alternative splice variants, glut9a and glut9b, with different subcellular localizations, no functional differences of the two splice variants are known to date. the aim of this study was to investigate the function of both glut9 isoforms.201931502429
heterologous hyaluronic acid production in kluyveromyces lactis.hyaluronic acid (ha) is a biopolymer composed by the monomers glucuronic acid (glcua) and n-acetyl glucosamine (glcnac). it has a broad range of applications in the field of medicine, being marketed between usd 1000-5000/kg. its primary sources include extraction of animal tissue and fermentation using pathogenic bacteria. however, in both cases, extensive purification protocols are required to prevent toxin contamination. in this study, aiming at creating a safe ha producing microorganism, the ...201931466214
advancing genetic and genomic technologies deepen the pool for discovery in xenopus tropicalis.xenopus laevis and xenopus tropicalis have long been used to drive discovery in developmental, cell, and molecular biology. these dual frog species boast experimental strengths for embryology including large egg sizes that develop externally, well-defined fate maps, and cell-intrinsic sources of nutrients that allow explanted tissues to grow in culture. development of the xenopus cell extract system has been used to study cell cycle and dna replication. xenopus tadpole tail and limb regeneration ...201931254427
adaptive correction of craniofacial defects in pre-metamorphic xenopus laevis tadpoles involves thyroid hormone-independent tissue remodeling.although it is well established that some organisms can regenerate lost structures, the ability to remodel existing malformed structures has been less well studied. therefore, in this study we examined the ability of pre-metamorphic xenopus laevis tadpoles to self-correct malformed craniofacial tissues. we found that tadpoles can adaptively improve and normalize abnormal craniofacial morphology caused by numerous developmental perturbations. we then investigated the tissue-level and molecular me ...201931253636
the amphibian (xenopus laevis) colony-stimulating factor-1 and interleukin-34-derived macrophages possess disparate pathogen recognition capacities.pathogens such as the frog virus 3 (fv3) ranavirus are contributing to the worldwide amphibian declines. while amphibian macrophages (mϕs) are central to the immune defenses against these viruses, the pathogen recognition capacities of disparate amphibian mϕ subsets remain unexplored. in turn, mϕ differentiation and functionality are interdependent on the colony-stimulating factor-1 receptor (csf-1r), which is ligated by colony-stimulating factor-1 (csf-1) and the unrelated interleukin-34 (il-34 ...201931029710
the voltage sensing phosphatase (vsp) localizes to the apical membrane of kidney tubule epithelial cells.voltage-sensing phosphatases (vsps) are transmembrane proteins that couple changes in membrane potential to hydrolysis of inositol signaling lipids. vsps catalyze the dephosphorylation of phosphatidylinositol phosphates (pips) that regulate diverse aspects of cell membrane physiology including cell division, growth and migration. vsps are highly conserved among chordates, and their rna transcripts have been detected in the adult and embryonic stages of frogs, fish, chickens, mice and humans. how ...201930964862
developmental exposure to chemicals associated with unconventional oil and gas extraction alters immune homeostasis and viral immunity of the amphibian xenopus.although aquatic vertebrates and humans are increasingly exposed to water pollutants associated with unconventional oil and gas extraction (uog), the long-term effects of these pollutants on immunity remains unclear. we have established the amphibian xenopus laevis and the ranavirus frog virus 3 (fv3) as a reliable and sensitive model for evaluating the effects of waterborne pollutants. x. laevis tadpoles were exposed to a mixture of equimass amount of uog chemicals with endocrine disrupting act ...201930939317
developmental regulation of wnt signaling by nagk and the udp-glcnac salvage pathway.in a screen for human kinases that regulate xenopus laevis embryogenesis, we identified nagk and other components of the udp-glcnac glycosylation salvage pathway as regulators of anteroposterior patterning and wnt signaling. we find that the salvage pathway does not affect other major embryonic signaling pathways (fgf, tgfβ, notch, or shh), thereby demonstrating specificity for wnt signaling. we show that the role of the salvage pathway in wnt signaling is evolutionarily conserved in zebrafish a ...201930904594
stage-dependent cardiac regeneration in xenopus is regulated by thyroid hormone availability.despite therapeutic advances, heart failure is the major cause of morbidity and mortality worldwide, but why cardiac regenerative capacity is lost in adult humans remains an enigma. cardiac regenerative capacity widely varies across vertebrates. zebrafish and newt hearts regenerate throughout life. in mice, this ability is lost in the first postnatal week, a period physiologically similar to thyroid hormone (th)-regulated metamorphosis in anuran amphibians. we thus assessed heart regeneration in ...201930755533
ketone body modulation of ligand-gated ion channels.ketogenesis is a metabolic process wherein ketone bodies are produced from the breakdown of fatty acids. in humans, fatty acid catabolism results in the production of acetyl-coa which can then be used to synthesize three ketone bodies: acetoacetate, acetone, and β-hydroxybutyrate. ketogenesis occurs at a higher rate in situations of low blood glucose, such as during fasting, heavy alcohol consumption, and in situations of low insulin, as well as in individuals who follow a 'ketogenic diet' consi ...201930562540
preventing ethanol-induced brain and eye morphology defects using optogenetics.background: embryonic exposure to the teratogen ethanol leads to dysmorphias, including eye and brain morphology defects associated with fetal alcohol spectrum disorder (fasd). exposure of xenopus laevis embryos to ethanol leads to similar developmental defects, including brain and eye dysmorphism, confirming our work and the work of others showing xenopus as a useful system for studies of the brain and eye birth defects associated with fasd. several targets of ethanol action have been hypothesi ...201932685918
embryogenesis of marsupial frogs (hemiphractidae), and the changes that accompany terrestrial development in frogs.the developmental adaptations of the marsupial frogs gastrotheca riobambae and flectonotus pygmaeus (hemiphractidae) are described and compared with frogs belonging to seven additional families. incubation of embryos by the mother in marsupial frogs is associated with changes in the anatomy and physiology of the female, modifications of oogenesis, and extraordinary changes in embryonic development. the comparison of early development reveals that gene expression is highly conserved. however, the ...201931598865
enhanced visual experience rehabilitates the injured brain in xenopus tadpoles in an nmdar-dependent manner.traumatic brain injuries introduce functional and structural circuit deficits that must be repaired for an organism to regain function. we developed an injury model in which xenopus laevis tadpoles are given a penetrating stab wound that damages the optic tectal circuit and impairs visuomotor behavior. in tadpoles, as in other systems, injury induces neurogenesis. the newly generated neurons are thought to integrate into the existing circuit; however, whether they integrate via the same mechanis ...201930517041
sr 57227a is a partial agonist/partial antagonist of 5-ht3 receptor and inhibits subsequent 5-ht- or sr 57227a-induced 5-ht3 receptor current.the serotonin (5-hydroxytryptamine) type 3 (5-ht3) receptors are transmembrane ligand-gated ion channels. although several 5-ht3 receptor agonists have been used as preclinical tools, sr 57227a is the most commonly used 5-ht3 receptor agonist with the ability to cross the blood brain barrier. however, the precise pharmacological profile of sr 57227a remains unclear. therefore, we examined the pharmacological profile of sr 57227a at the 5-ht3a and 5-ht3ab receptors. we microinjected xenopus laevi ...201930509492
involvement of epigenetic modifications in thyroid hormone-dependent formation of adult intestinal stem cells during amphibian metamorphosis.amphibian metamorphosis has long been used as model to study postembryonic development in vertebrates, a period around birth in mammals when many organs/tissues mature into their adult forms and is characterized by peak levels of plasma thyroid hormone (t3). of particular interest is the remodeling of the intestine during metamorphosis. in the highly-related anurans xenopus laevis and xenopus tropicalis, this remodeling process involves larval epithelial cell death and de novo formation of adult ...201930472386
solid lipid nanoparticles for the delivery of anti-microbial oligonucleotides.novel alternatives to antibiotics are urgently needed for the successful treatment of antimicrobial resistant (amr) infections. experimental antibacterial oligonucleotide therapeutics, such as transcription factor decoys (tfd), are a promising approach to circumvent amr. however, the therapeutic potential of tfd is contingent upon the development of carriers that afford efficient dna protection against nucleases and delivery of dna to the target infection site. as a carrier for tfd, here we pres ...201930468838
increasing nitroxide lifetime in cells to enable in-cell protein structure and dynamics measurements by electron spin resonance spectroscopy.there is increasing evidence that the stability, structure, dynamics, and function of many proteins differ in cells versus in vitro. the determination of protein structure and dynamics within the native cellular environment may lead to better understanding of protein behavior. electron spin resonance (esr) has emerged as a technique that can report on protein structure and dynamics within cells. nitroxide based spin labels are capable of reporting on protein dynamics, structure, and backbone fle ...201930550988
dual cationic-anionic profiling of metabolites in a single identified cell in a live xenopus laevis embryo by microprobe ce-esi-ms.in situ capillary microsampling with capillary electrophoresis (ce) electrospray ionization (esi) mass spectrometry (ms) enabled the characterization of cationic metabolites in single cells in complex tissues and organisms. for deeper coverage of the metabolome and metabolic networks, analytical approaches are needed that provide complementary detection for anionic metabolites, ideally using the same instrumentation. described here is one such approach that enables sequential cationic and anioni ...201930542678
radiobiological characteristics of descendant progeny of fish and amphibian cells that survive the initial ionizing radiation dose.to evaluate the development of delayed lethal mutations, the production of medium borne lethal bystander signals, and the acquirement of radiosensitive or radioresistant traits in distant descendant progeny of fish and amphibian cells surviving ionizing radiation materials and methods: american eel brain endothelial cells (eelb) and african clawed frog epithelial cells (a6) were initially irradiated with gamma rays at 0.5 gy or 2 gy. ionizing radiation (ir)-surviving cells were grown for 27 popu ...201930530089
a xenopus tadpole alternative model to study innate-like t cell-mediated anti-mycobacterial immunity.owing to the high incidence of multi-drug resistance and challenges posed by the complex and long duration of treatments, mycobacterium tuberculosis (mtb) infections remain a significant clinical burden, which would benefit from development of novel immuno-therapeutic-based treatment strategies. among early immune effectors, invariant or innate-like (i)t cells are attracting attention because of their potential regulatory activity, which can shape anti-mycobacterial immune responses. unlike conv ...201930521838
gd(iii)-gd(iii) relaxation-induced dipolar modulation enhancement for in-cell electron paramagnetic resonance distance determination.in-cell distance determination by electron paramagnetic resonance (epr) spectroscopy reveals essential structural information about biomacromolecules under native conditions. we demonstrate that the pulsed epr technique ridme (relaxation induced dipolar modulation enhancement) can be utilized for such distance determination. the performance of in-cell ridme has been assessed at q-band using stiff molecular rulers labeled with gd(iii)-pymta and microinjected into xenopus laevis oocytes. the overt ...201930864799
dynamin binding protein is required for xenopus laevis kidney development.the adult human kidney contains over one million nephrons, with each nephron consisting of a tube containing segments that have specialized functions in nutrient and water absorption and waste excretion. the embryonic kidney of xenopus laevis consists of a single functional nephron composed of regions that are analogous to those found in the human nephron, making it a simple model for the study of nephrogenesis. the exocyst complex, which traffics proteins to the cell membrane in vesicles via cd ...201930863317
foxn3 is necessary for the development of the interatrial septum, the ventricular trabeculae and the muscles at the head/trunk interface in the african clawed frog, xenopus laevis (lissamphibia: anura: pipidae).fox genes are a large family of transcription factors that play diverse roles in the immune system, metabolism, cancer, cell cycle, and animal development. it has been shown that foxn3 is indispensable for normal craniofacial development in the mouse and the african clawed frog, xenopus laevis. morpholino-mediated knockdown of foxn3 in x. laevis delays overall development of early tadpole stages and causes eye defects, the absence of some cranial nerve branches, and malformations of the cranial ...201930859697
erratum: skin grafting in xenopus laevis: a technique for assessing development and immunological disparity. 201931371466
jmjd6a regulates gsk3β rna splicing in xenopus laevis eye development.it has been suggested that jmjd6 plays an important role in gene regulation through its demethylation or hydroxylation activity on histone and transcription factors. in addition, jmjd6 has been shown to regulate rna splicing by interaction with splicing factors. in this study, we demonstrated that jmjd6a is expressed in developing xenopus laevis eye during optic vesicle formation and retinal layer differentiation stages. knockdown of jmjd6a by an antisense morpholino resulted in eye malformation ...201931361752
identification of the catechin uptake transporter responsible for intestinal absorption of epigallocatechin gallate in mice.many studies have shown that epigallocatechin gallate (egcg) contribute to the health benefits of green tea, although its bioavailability is usually low. however, the mechanism underlying its intestinal absorption remains unclear. in human subjects, it has been reported that the bioavailability of egcg increases after repeated oral catechin intake. we hypothesized that a certain uptake transporter was involved in this increase, and investigated a novel egcg transporter. we first confirmed the in ...201931358798
maldi-imaging of early stage xenopus laevis embryos.xenopus laevis is an important model organism for vertebrate development. an extensive literature has developed on changes in transcript expression during development of this organism, and there is a growing literature on the corresponding protein expression changes during development. in contrast, there is very little information on changes in metabolite expression during development. we present the first maldi mass-spectrometry images of metabolites within the developing embryo. these images w ...201931357275
encephalopathies with kcnc1 variants: genotype-phenotype-functional correlations.to analyze clinical phenotypes associated with kcnc1 variants other than the progressive myoclonus epilepsy-causing variant p.arg320his, determine the electrophysiological functional impact of identified variants and explore genotype-phenotype-physiological correlations.201931353855
spatial analysis of reck, mt1-mmp, and timp-2 proteins during early xenopus laevis development.proper cell-cell and cell-ecm interactions are vital for cell migration and patterning of the vertebrate embryo. mmps and their inhibitors, reck and timps, are all differentially expressed during embryogenesis to regulate such ecm remodeling and cell interactions. mt1-mmp, reck, and timp-2 are unique amongst other ecm-regulating proteins as they act in the pericellular space. past studies have shown that reck and timp-2 interact with mt1-mmp on the cell surface, thereby influencing cell behaviou ...201931352120
mechanical force induces phosphorylation-mediated signaling that underlies tissue response and robustness in xenopus embryos.mechanical forces are essential drivers of numerous biological processes, notably during development. although it is well recognized that cells sense and adapt to mechanical forces, the signal transduction pathways that underlie mechanosensing have remained elusive. here, we investigate the impact of mechanical centrifugation force on phosphorylation-mediated signaling in xenopus embryos. by monitoring temporal phosphoproteome and proteome alterations in response to force, we discover and valida ...201930852251
a unique role of thyroid hormone receptor β in regulating notochord resorption during xenopus metamorphosis.tail resorption during anuran metamorphosis is perhaps the most dramatic tissue transformation that occurs during vertebrate development. earlier studies in highly related anuran species xenopus laevis and xenopus tropicalis have shown that thyroid hormone (t3) receptor (tr) plays a necessary and sufficient role to mediate the causative effect of t3 on metamorphosis. of the two known tr genes in vertebrates, trα is highly expressed during both premetamorphosis and metamorphosis while trβ express ...201930851299
distinctive single-channel properties of α4β2-nicotinic acetylcholine receptor isoforms.central nervous system nicotinic acetylcholine receptors (nachr) are predominantly of the α4β2 subtype. two isoforms exist, with high or low agonist sensitivity (hs-(α4β2)2β2- and ls-(α4β2)2α4-nachr). both isoforms exhibit similar macroscopic potency and efficacy values at low acetylcholine (ach) concentrations, mediated by a common pair of high-affinity α4(+)/(-)β2 subunit binding interfaces. however ls-(α4β2)2α4-nachr also respond to higher concentrations of ach, acting at a third α4(+)/(-)α4 ...201930845161
evolution of the rho guanine nucleotide exchange factors kalirin and trio and their gene expression in xenopus development.guanine nucleotide exchange factors (gefs) activate rho gtpases by accelerating their gdp/gtp exchange. trio and its paralog kalirin (kalrn) are unique members of the rho-gefs that harbor three catalytic domains: two functional gef domains and a serine/threonine kinase domain. the n-terminal gef domain activates rac1 and rhog gtpases, while the c-terminal gef domain acts specifically on rhoa. trio and kalrn have an evolutionary conserved function in morphogenetic processes including neuronal dev ...201930844509
electrophysiological changes during early steps of retinitis pigmentosa.the rhodopsin mutation p23h is responsible for a significant portion of autosomal-dominant retinitis pigmentosa, a disorder characterized by rod photoreceptor death. the mechanisms of toxicity remain unclear; previous studies implicate destabilization of p23h rhodopsin during light exposure, causing decreased endoplasmic reticulum (er) exit and er stress responses. here, we probed phototransduction in xenopus laevis rods expressing bovine p23h rhodopsin, in which retinal degeneration is inducibl ...201930840038
bisphenol a, bisphenol af, di-n-butyl phthalate, and 17β-estradiol have shared and unique dose-dependent effects on early embryo cleavage divisions and development in xenopus laevis.bisphenol a (bpa), bisphenol af (bpaf), and di-n-butyl phthalate (dbp) are widespread compounds used in the production of plastics. we used xenopus laevis to compare their effects on early embryo cell division and development. directly after in vitro fertilizations, embryos were exposed to bpa, bpaf, dbp, or 17β-estradiol (e2) for up to 96 h. bpa (1-50 μm) and bpaf (0.003-25 μm) caused disrupted cleavage divisions, slowed cytokinesis, and cellular dissociation within 1-6 h. flexures of the spina ...201930579998
molecular charge associated with antiarrhythmic actions in a series of amino-2-cyclohexyl ester derivatives.a series of amino-2-cyclohexyl ester derivatives were studied for their ion channel blocking and antiarrhythmic actions in the rat and a structure-activity analysis was conducted. the compounds are similar in chemical structure except for ionizable amine groups (pk values 6.1-8.9) and the positional arrangements of aromatic naphthyl moieties. ventricular arrhythmias were produced in rats by coronary-artery occlusion or electrical stimulation. the electrophysiological effects of these compounds o ...201930571955
lack of evidence for synaptic high-affinity γ-hydroxybutyric acid (ghb) transport in rat brain synaptosomes and 11 na+ -dependent slc neurotransmitter transporters.γ-hydroxybutyric acid (ghb) is an endogenous compound proposed to act as a neurotransmitter. na+ -dependent, high-affinity ghb transport has long been considered important evidence supporting this hypothesis. however, the molecular identity of such a high-affinity transporter remains unknown. in this study, we sought to identify and characterize ghb synaptic transport through a series of studies using both native and recombinant systems with the ultimate aim of providing evidence to clarify the ...201930570143
lysine demethylase 3a in craniofacial and neural development during xenopus embryogenesis.epigenetic modifier lysine demethylase 3a (kdm3a) specifically demethylates mono‑ and di‑methylated ninth lysine of histone 3 and belongs to the jumonji domain‑containing group of demethylases. kdm3a serves roles during various biological and pathophysiological processes, including spermatogenesis and metabolism, determination of sex, androgen receptor‑mediated transcription and embryonic carcinoma cell differentiation. in the present study, physiological functions of kdm3a were evaluated during ...201930569092
ospht1;3 mediates uptake, translocation, and remobilization of phosphate under extremely low phosphate regimes.plant roots rely on inorganic orthophosphate (pi) transporters to acquire soluble pi from soil solutions that exists at micromolar levels in natural ecosystems. here, we functionally characterized a rice (oryza sativa) pi transporter, os phosphate transporter-1;3 (ospht1;3), that mediates pi uptake, translocation, and remobilization. ospht1;3 was directly regulated by os phosphate starvation response-2 and, in response to pi starvation, showed enhanced expression in young leaf blades and shoot b ...201930567970
expression pattern and histone acetylation of energy metabolic genes in xenopus laevis liver in response to diet statuses.amphibians can survive without food for relatively longer periods by reducing the locomotor activity and metabolic rate and can recover quickly with refeeding from a dormant state. to clarify the molecular mechanism underlying this survival strategy, we investigated serum biochemical parameters, the transcript levels of energy metabolic genes, and global and gene-specific histone modifications in the liver of adult male xenopus laevis, which were fed, fasted, or refed after fasting. glucose, tri ...201930460762
how thyroid hormones and their inhibitors affect cartilage growth and shape in the frog xenopus laevis.understanding how skeleton changes shape in ontogeny is fundamental to understanding how its shape diversifies in phylogeny. amphibians pose a special case because their jaw and throat skeleton consists of cartilages that are dramatically reshaped midway through life to support new feeding and breathing styles. although amphibian metamorphosis is commonly studied by immersing larvae in thyroid hormones (th), how individual cartilages respond to th is poorly understood. this study documents the e ...201930456781
class a scavenger receptors mediate extracellular dsrna sensing, leading to downstream antiviral gene expression in a novel american toad cell line, bufotad.viral double-stranded (ds)rna is a potent pathogen-associated molecular pattern (pamp), capable of inducing a strong antiviral state within the cell, protecting the cell from virus infection. in mammals and fish, sensing extracellular dsrna is mediated by cell-surface class a scavenger receptors (sr-as). currently, very little is known about sr-as in amphibians, including: sequence, expression patterns and function. to this end, sr-a expression and function was studied in a novel american toad ( ...201930452932
proteolytic activation of bmps: analysis of cleavage in xenopus oocytes and embryos.bone morphogenetic proteins (bmps) are synthesized as inactive precursors that are cleaved to generate active ligands, along with prodomain fragments that can modulate growth factor activity. here we provide three protocols that can be used to examine the process of proteolytic activation of bmps. the first protocol describes how to generate radiolabeled bmp precursor proteins in xenopus oocytes and then analyze the time course of precursor cleavage by recombinant enzymes in vitro. the second pr ...201930414129
microtransplantation of human brain receptors into oocytes to tackle key questions in drug discovery.it is important in drug discovery to demonstrate that activity of novel drugs found by screening on recombinant receptors translates to activity on native human receptors in brain areas affected by disease. in this review, we summarise the development and use of the microtransplantation technique. native receptors are reconstituted from human brain tissues into oocytes from the frog xenopus laevis where they can be functionally assessed. oocytes microtransplanted with hippocampal tissue from an ...201930395928
a modified tripeptide motif of rs1 (rsc1a1) down-regulates exocytotic pathways of human na+-d-glucose cotransporters sglt1, sglt2, and glucose sensor sglt3 in the presence of glucose.a domain of protein rs1 (rsc1a1) called rs1-reg down-regulates the plasma membrane abundance of na+-d-glucose cotransporter sglt1 by blocking the exocytotic pathway at the trans-golgi. this effect is blunted by intracellular glucose but prevails when serine in a qsp (gln-ser-pro) motif is replaced by glutamate [rs1-reg(s20e)]. rs1-reg binds to ornithine decarboxylase (odc) and inhibits odc in a glucose-dependent manner. because the odc inhibitor difluoromethylornithine (dfmo) acts like rs1-reg(s ...201930355744
functional studies of transcriptional cofactors via microinjection-mediated gene editing in xenopus.the anuran xenopus laevis has been studied for decades as a model for vertebrate cell and developmental biology. more recently, the highly related species xenopus tropicalis has offered the opportunity to carry out genetic studies due to its diploid genome as compared to the pseudo-tetraploid xenopus laevis. amphibians undergo a biphasic development: embryogenesis to produce a free-living tadpoles and subsequent metamorphosis to transform the tadpole to a frog. this second phase mimics the so-ca ...201930353533
comprehensive analysis of formin localization in xenopus epithelial cells.reorganization of the actin cytoskeleton is crucial for cellular processes, including cytokinesis and cell-cell junction remodeling. formins are conserved processive actin-polymerizing machines that regulate actin dynamics by nucleating, elongating, and bundling linear actin filaments. because the formin family is large, with at least 15 members in vertebrates, there have not been any comprehensive studies examining formin localization and function within a common cell type. here, we characteriz ...201930379611
anticipation of food intake induces phosphorylation switch to regulate basolateral amino acid transporter lat4 (slc43a2) function.amino acid absorption requires luminal uptake into and subsequent basolateral efflux out of epithelial cells, with the latter step being critical to regulate the intracellular concentration of the amino acids. the basolateral essential neutral amino acid uniporter lat4 (slc43a2) has been suggested to drive the net efflux of non-essential and cationic amino acids via parallel amino acid antiporters by recycling some of their substrates; its deletion has been shown to cause defective postnatal gro ...201930379325
high-affinity k+ transporters from a halophyte, sporobolus virginicus, mediate both k+ and na+ transport in transgenic arabidopsis, x. laevis oocytes and yeast.class ii high-affinity potassium transporters (hkts) have been proposed to mediate na+-k+ co-transport in plants, as well as na+ and k+ homeostasis under k+-starved and saline environments. we identified class ii hkts, namely svhkt2;1 and svhkt2;2 (svhkts), from the halophytic turf grass, sporobolus virginicus. svhkt2;2 expression in s. virginicus was up-regulated by nacl treatment, while svhkt2;1 expression was assumed to be up-regulated by k+ starvation and down-regulated by nacl treatment. lo ...201930325438
generation and analysis of xenopus laevis models of retinal degeneration using crispr/cas9.xenopus laevis have proven to be a useful system for rapid generation and analysis of transgenic models of human retinal disease. however, experimental approaches in this system were limited by lack of a robust knockdown or knockout technology. here we describe a protocol for generation of cas9-edited x. laevis embryos. the technique introduces point mutations into the genome of x. laevis resulting in in-frame and out-of-frame insertions and deletions that allow modeling of both dominant and rec ...201930324446
microsampling capillary electrophoresis mass spectrometry enables single-cell proteomics in complex tissues: developing cell clones in live xenopus laevis and zebrafish embryos.label-free single-cell proteomics by mass spectrometry (ms) is currently incompatible with complex tissues without requiring cell culturing, single-cell dissection, or tissue dissociation. we here report the first example of label-free single-cell ms-based proteomics directly in single cells in live vertebrate embryos. our approach integrates optically guided in situ subcellular capillary microsampling, one-pot extraction-digestion of the collected proteins, peptide separation by capillary elect ...201930827088
conditional demyelination and remyelination in a transgenic xenopus laevis.multiple sclerosis (ms) is the first cause of acquired disability progression in the young adult. pathology of ms associates inflammation, demyelination, and neurodegeneration. the development of immunotherapies, by reducing the relapse rate, has profoundly impacted short-term prognosis and patients' quality of life. these anti-inflammatory medications, however, have not proven to be sufficient to prevent long-term disability progression, resulting from axonal transection and neuronal damage, co ...201930820903
the c-terminus of the retinal homeobox (rax) gene product modulates transcription in a context-dependent manner.the evolutionarily conserved retinal homeobox (rax) transcription factor is essential for normal eye development in all vertebrates. despite rax's biologic significance, the molecular mechanisms underlying rax molecular function as a transcriptional regulator are poorly defined. the rax gene encodes a conserved octapeptide motif (op) near the n-terminus and several conserved regions in the c-terminus of unknown function, including the orthopedia, aristaless, rax (oar) domain and the rx domain. t ...201930820152
more than just a bandage: closing the gap between injury and appendage regeneration.the remarkable regenerative capabilities of amphibians have captured the attention of biologists for centuries. the frogs xenopus laevis and xenopus tropicalis undergo temporally restricted regenerative healing of appendage amputations and spinal cord truncations, injuries that are both devastating and relatively common in human patients. rapidly expanding technological innovations have led to a resurgence of interest in defining the factors that enable regenerative healing, and in coupling thes ...201930800076
the wnt inhibitor dkk1 is required for maintaining the normal cardiac differentiation program in xenopus laevis.wnt proteins can activate different intracellular signaling pathways. these pathways need to be tightly regulated for proper cardiogenesis. the canonical wnt/β-catenin inhibitor dkk1 has been shown to be sufficient to trigger cardiogenesis in gain-of-function experiments performed in multiple model systems. loss-of-function studies however did not reveal any fundamental function for dkk1 during cardiogenesis. using xenopus laevis as a model we here show for the first time that dkk1 is required f ...201930797757
fluorescent analogues of bekm-1 with high and specific activity against the herg channel.peptidic toxins that target specifically mammalian channels and receptors can be found in the venom of animals. these toxins are rarely used directly as tools for biochemical experiments, and need to be modified via the attachment of chemical groups (e.g., radioactive or fluorescent moieties). ideally, such modifications should maintain the toxin specificity and affinity for its target. with the goal of obtaining fluorescent derivatives of bekm-1, a toxin from the scorpion species buthus eupeus ...201932550567
rho flares repair local tight junction leaks.tight junctions contribute to epithelial barrier function by selectively regulating the quantity and type of molecules that cross the paracellular barrier. experimental approaches to evaluate the effectiveness of tight junctions are typically global, tissue-scale measures. here, we introduce zinc-based ultrasensitive microscopic barrier assay (znumba), which we used in xenopus laevis embryos to visualize short-lived, local breaches in epithelial barrier function. these breaches, or leaks, occur ...201930773490
activity and intracellular localization of senescence-associated β-galactosidase in aging xenopus oocytes and eggs.senescence-associated β-galactosidase (sa-β-gal) serves as a marker of senescence in aging somatic cells. however, little is known about sa-β-gal dynamics in aging gamete cells. to address this issue, here we investigated activity and intracellular localization of sa-β-gal in freshly obtained and aging oocytes and eggs of the african clawed frog xenopus laevis. data base mining revealed the presence of several homologous β-galactosidase sequences in the annotated xenopus genome. some of them wer ...201930769028
on the mechanism of the electrophysiological changes and membrane lesions induced by asbestos fiber exposure in xenopus laevis oocytes.the so-called amphibole asbestos fibers are enriched with mineral iron ions, able to stimulate ros production. we recently reported that crocidolite asbestos was able to interact with the cell membranes of xenopus laevis oocytes, to alter their electrical membrane properties. here, we found that applied iron ions (fe3+) or h2o2 (for ros generation) mimicked these effects, suggesting that at least one effect of iron-containing asbestos fiber exposure was mediated by ros production. furthermore, c ...201930765791
wgddetector: a pipeline for detecting whole genome duplication events using the genome or transcriptome annotations.with the availability of well-assembled genomes of a growing number of organisms, identifying the bioinformatic basis of whole genome duplication (wgd) is a growing field of genomics. the most extant software for detecting footprints of wgds has been restricted to a well-assembled genome. however, the massive poor quality genomes and the more accessible transcriptomes have been largely ignored, and in theoretically they are also likely to contribute to detect wgd using ds based method. here, to ...201930760221
various nuclear reprogramming systems using egg and oocyte materials.maternal factors stored in eggs and oocytes are necessary for reprogramming sperm for embryonic development. this reprogramming activity of maternal factors also works towards somatic cells, including terminally differentiated cells. several different experimental systems utilizing egg and oocyte materials have been applied to study nuclear reprogramming by maternal factors. among these systems, the most widely used is the transfer of a somatic cell nucleus to an oocyte arrested at the metaphase ...201930745498
pymetrozine activates trpv channels of brown planthopper nilaparvata lugens.the commercial insecticide pymetrozine has been extensively used for brown planthopper control in east asia. the transient receptor potential vanilloid (trpv) channel, which consists of two proteins, nanchung (nan) and inactive (iav), has recently been shown to be the molecular target of pymetrozine in the fruit fly (drosophila melanogaster) and pea aphid (acyrthosiphon pisum). in this study, we characterized the nan and iav trpv channel subunits of n. lugens and measured the action of pymetrozi ...201930744899
jaburetox, a natural insecticide derived from jack bean urease, activates voltage-gated sodium channels to modulate insect behavior.jaburetox (jbtx) is an insecticidal peptide derived from canavalia ensiformis urease, whose mechanism of action is not completely elucidated. we employed behavioral, electromyographical and electrophysiological protocols to identify the cellular and molecular targets involved in the jbtx entomotoxicity in cockroaches and locusts. in nauphoeta cinerea, jbtx (32 μg/g) altered the locomotory behaviour inducing a significative decrease in the distance travelled followed by a significant increase in ...201930744898
gene expression program underlying tail resorption during thyroid hormone-dependent metamorphosis of the ornamented pygmy frog microhyla fissipes.thyroid hormone (t3) is essential for vertebrate development, especially during the so-called postembryonic development, a period around birth in mammals when plasma t3 level peaks and many organs mature into their adult form. compared to embryogenesis, postembryonic development is poorly studied in mammals largely because of the difficulty to manipulate the uterus-enclosed embryos and neonates. amphibian metamorphosis is independent of maternal influence and can be easily manipulated for molecu ...201930740088
generation of xenopus haploid, triploid, and hybrid embryos.frog species of the genus xenopus are widely used for studies of cell and developmental biology, and recent genome sequencing has revealed interesting phylogenetic relationships. here we describe methods to generate haploid, triploid, and hybrid species starting from eggs and sperm of xenopus laevis and xenopus tropicalis that enable investigation of how genome size and content affect physiology at the organismal, cellular, and subcellular levels.201930737699
methods for isolating the balbiani body/germplasm from xenopus laevis oocytes.the balbiani body (bb) is a large membrane-less organelle, densely packed with mitochondria, endoplasmic reticulum, proteins, and rna. the bb is present in many vertebrate female gametes. in frogs, the bb is established early during oogenesis and operates as a maternal inherited embryonic determinant that specifies germline identity through the formation of germplasm. we describe here two techniques to isolate the bb/germplasm from xenopus laevis primary oocytes.201930737696
membrane microdomains as platform to study membrane-associated events during oogenesis, meiotic maturation, and fertilization in xenopus laevis.studies on the egg plasma membrane-associated tyrosine kinase src have shed light on the identity of the molecular machinery that is responsible for gamete interaction and possibly fusion in african clawed frog xenopus laevis. here we describe our protocol for identifying and analyzing molecular and cellular machinery that contributes to a variety of biological processes in the course of oogenesis, oocyte maturation, egg fertilization, and early embryogenesis in xenopus. our current special inte ...201930737686
reconstitution of intracellular calcium signaling in xenopus egg extracts.generation of calcium signal in the cytoplasm of fertilized or parthenogenetically activated eggs has been extensively studied in the intact eggs of several biological species. calcium transient was found to elicit a plethora of biochemical and cellular events in these cells. remarkably, intracellular calcium signaling can also be reconstituted in cell-free environment. in this chapter, we describe the methods that allow reconstitution, detection, and quantification of the calcium signal in cell ...201930737685
imatinib uptake into cells is not mediated by organic cation transporters oct1, oct2, or oct3, but is influenced by extracellular ph.cancer cells undergo genetic and environmental changes that can alter cellular disposition of drugs, notably by alterations of transmembrane drug transporters expression. whether the influx organic cation transporter 1 (oct1) encoded by the gene slc221a1 is implicated in the cellular uptake of imatinib is still controversial. besides, imatinib ionization state may be modulated by the hypoxic acidic surrounding extracellular microenvironment.201930734690
comparison the sensitivity of amphibian metamorphosis assays with nf 48 stage and nf 51 stage xenopus laevis tadpoles.the amphibian metamorphosis assay (ama) was proposed by the organization for economic cooperation and development (oecd) to screen thyroid disruptors of vertebrate species. the general experimental design of the ama exposes nieuwkoop and faber (nf) stage 51 xenopus laevis tadpoles to test chemical concentrations for 21 d. however, recent studies demonstrated that thyroid gland began to function after nf stage 45 in x. laevis. thus, in this study, we initiated exposure with nf stage 48 tadpoles w ...201930732517
using xenopus laevis oocytes to functionally characterize plant transporters.functionally characterizing plant membrane transport proteins is challenging. typically, heterologous systems are used to study them. immature eggs (oocytes) of the south african clawed frog xenopus laevis are considered an ideal expression system for such studies. these large oocytes have a low number of endogenous transport systems in their plasma membranes and highly express foreign mrna; the oocyte plasma membrane is the default destination of integral membrane proteins that lack recognized ...201930707001
anillin regulates epithelial cell mechanics by structuring the medial-apical actomyosin network.cellular forces sculpt organisms during development, while misregulation of cellular mechanics can promote disease. here, we investigate how the actomyosin scaffold protein anillin contributes to epithelial mechanics in xenopus laevis embryos. increased mechanosensitive recruitment of vinculin to cell-cell junctions when anillin is overexpressed suggested that anillin promotes junctional tension. however, junctional laser ablation unexpectedly showed that junctions recoil faster when anillin is ...201930702429
menthol acts as a positive allosteric modulator on nematode levamisole sensitive nicotinic acetylcholine receptors.the ongoing and widespread emergence of resistance to the existing anti-nematodal pharmacopeia has made it imperative to develop new anthelminthic agents. historically, plants have been important sources of therapeutic compounds and offer an alternative to synthetic drugs. monoterpenoids are phytochemicals that have been shown to produce acute toxic effects in insects and nematodes. previous studies have shown nicotinic acetylcholine receptors (nachrs) to be possible targets for naturally occurr ...201930682641
characterization of xenopus laevis guanine deaminase reveals new insights for its expression and function in the embryonic kidney.the mammalian guanine deaminase (gda), called cypin, is important for proper neural development, by regulating dendritic arborization through modulation of microtubule (mt) dynamics. additionally, cypin can promote mt assembly in vitro. however, it has never been tested whether cypin (or other gda orthologs) binds to mts or modulates mt dynamics. here, we address these questions and characterize xenopus laevis gda (gda) for the first time during embryonic development.201930682232
analysis of long non-coding rna involved in atrazine-induced testicular degeneration of xenopus laevis.long non-coding rna (lncrna) plays a critical role in male germline development. atrazine (az) as an environmental endocrine disrupting chemical (edcs) can induce male reproductive toxicity in amphibians. our previous studies demonstrated that az can alter gene and circular rna (circrna) expression of damaged testes in xenopus laevis (x. laevis). we furthered to investigate the lncrna expression profiling in the testis of x. laevis. over 3559 lncrnas were detected by lncrna sequencing. az induce ...201930675760
oscillating aquaporin phosphorylation and 14-3-3 proteins mediate the circadian regulation of leaf hydraulics.the circadian clock regulates plant tissue hydraulics to synchronize water supply with environmental cycles and thereby optimize growth. the circadian fluctuations in aquaporin transcript abundance suggest that aquaporin water channels play a role in these processes. here, we show that hydraulic conductivity (kros) of arabidopsis (arabidopsis thaliana) rosettes displays a genuine circadian rhythmicity with a peak around midday. combined immunological and proteomic approaches revealed that phosph ...201930674691
non-acylated wnts can promote signaling.wnts are a family of 19 extracellular ligands that regulate cell fate, proliferation, and migration during metazoan embryogenesis and throughout adulthood. wnts are acylated post-translationally at a conserved serine and bind the extracellular cysteine-rich domain (crd) of frizzled (fzd) seven-pass transmembrane receptors. although crystal structures suggest that acylation is essential for wnt binding to fzds, we show here that several wnts can promote signaling in xenopus laevis and danio rerio ...201930673610
effect of the flavonoid hesperidin on glucose and fructose transport, sucrase activity and glycaemic response to orange juice in a crossover trial on healthy volunteers.although polyphenols inhibit glucose absorption and transport in vitro, it is uncertain whether this activity is sufficient to attenuate glycaemic response in vivo. we examined this using orange juice, which contains high levels of hesperidin. we first used a combination of in vitro assays to evaluate the potential effect of hesperidin and other orange juice components on intestinal sugar absorption and then tested whether this translated to an effect in healthy volunteers. hesperidin attenuated ...201930670104
whole-cell photoacoustic sensor based on pigment relocalization.photoacoustic (optoacoustic) imaging can extract molecular information with deeper tissue penetration than possible by fluorescence microscopy techniques. however, there is currently still a lack of robust genetically controlled contrast agents and molecular sensors that can dynamically detect biological analytes of interest with photoacoustics. in a biomimetic approach, we took inspiration from cuttlefish who can change their color by relocalizing pigment-filled organelles in so-called chromato ...201930663315
x-linked α-thalassemia with mental retardation is downstream of protein kinase a in the meiotic cell cycle signaling cascade in xenopus oocytes and is dynamically regulated in response to dna damage†.x-linked α-thalassemia with mental retardation (atrx) is a chromatin remodeling protein that belongs to the switch/sucrose non-fermentable (swi2/snf2) family of helicase/atpases. during meiosis, atrx is necessary for heterochromatin formation and maintenance of chromosome stability in order to ensure proper assembly of the metaphase ii spindle. previously, we established atrx as a novel progesterone regulated protein during bovine meiotic maturation, in addition to being dynamically regulated in ...201930649195
the electrical block to polyspermy induced by an intracellular ca2+ increase at fertilization of the clawed frogs, xenopus laevis and xenopus tropicalis.polyspermy blocking, to ensure monospermic fertilization, is necessary for normal diploid development in most animals. we have demonstrated here that monospermy in the clawed frog, xenopus tropicalis, as well as in x. laevis, is ensured by a fast, electrical block to polyspermy on the egg plasma membrane after the entry of the first sperm, which is mediated by the positive-going fertilization potential. an intracellular ca2+ concentration ([ca2+ ]i ) at the sperm entry site was propagated as a c ...201930648313
xenopus oocytes as a heterologous expression system for analysis of tight junction proteins.claudins (cldns) represent the largest family of transmembrane tight junction (tj) proteins, determining organ-specific epithelial barrier properties. because methods for the analysis of multiple cldn interaction are limited, we have established the heterologous xenopus laevis oocyte expression system for tj protein assembly and interaction analysis. oocytes were injected with crna encoding human cldn-1, -2, or -3 or with a combination of these and were incubated in pairs for interaction analysi ...201930645152
insemination or phosphatidic acid induces an outwardly spiraling disk of elevated ca2+ to produce the ca2+ wave during xenopus laevis fertilization.during xenopus fertilization, the initial intracellular calcium ((ca2+)i) release at the sperm-egg binding site (hot spot) has not been described without the use of inhibitors, nor related to underlying er structure. without inhibitors, we now report that sperm induce an initial hot spot after sperm addition to xenopus eggs that was ~25 µm. this area is consistent with the size of er patches and clusters of ip3 receptors that have enhanced activity. furthermore, we find a new mechanism for the f ...201930641042
deuterium-free, three-plexed peptide diethylation for highly accurate quantitative proteomics.the deuterium, a frequently used stable isotope in isotopic labeling for quantitative proteomics, could deteriorate the accuracy and precision of proteome quantification owing to the retention time shift of deuterated peptides from the hydrogenated counterpart. we introduce a novel three-plexed peptide "diethylation" using only 13c isotopologues of acetaldehyde and demonstrate that the accuracy and precision of our method in proteome quantification are significantly superior to the conventional ...201930638020
purification and characterization of a urea sensitive lactate dehydrogenase from skeletal muscle of the african clawed frog, xenopus laevis.the african clawed frog, xenopus laevis endures whole body dehydration which can increase its reliance on anaerobic glycolysis for energy production. this makes the regulation of the terminal enzyme of glycolysis, lactate dehydrogenase (ldh), crucial to stress survival. we investigated the enzymatic properties and posttranslational modification state of purified ldh from the skeletal muscle of control and dehydrated (30% total body water loss) x. laevis. ldh from the muscle of dehydrated frogs s ...201930631901
rhinella marina oocytes: a suitable alternative expression system for functional characterization of aquaglyceroporins.amphibian oocytes have been extensively used for heterologous expression of membrane proteins for studying their biochemical and biophysical properties. so far, xenopus laevis is the main amphibian used as oocytes source to express aquaglyceroporins in order to assess water and solutes permeability. however, this well-established amphibian model represents a threat to the biodiversity in many countries, especially in those from tropical regions. for that reason, the import of xenopus laevis is s ...201930631140
identification of vacuolar phosphate efflux transporters in land plants.inorganic phosphate (pi) is an essential component of all life forms. land plants acquire pi from the soil through roots and associated symbioses, and it is then transported throughout the plant. when sufficient, excess pi is stored in vacuoles for remobilization following pi deficiency. although pi release from the vacuoles to the cytoplasm serves as a critical mechanism for plants to adapt to low-pi stress, the transporters responsible for vacuolar pi efflux have not been identified. here, we ...201930626920
ensa and arpp19 differentially control cell cycle progression and development.greatwall (gwl) is an essential kinase that indirectly controls pp2a-b55, the phosphatase counterbalancing cyclin b/cdk1 activity during mitosis. in xenopus laevis egg extracts, gwl-mediated phosphorylation of overexpressed arpp19 and ensa turns them into potent pp2a-b55 inhibitors. it has been shown that the gwl/ensa/pp2a-b55 axis contributes to the control of dna replication, but little is known about the role of arpp19 in cell division. by using conditional knockout mouse models, we investiga ...201930626720
xenopus slc7a5 is essential for notochord function and eye development.slc7a5 (also known as lat1), largely accepted as an amino acid transporter, has been shown to play important roles in cancer and developmental processes. because knockout mice of slc7a5 are embryonically lethal due to placental defects, it is difficult to evaluate its role in early development. in this study, expression and function of slc7a5 were evaluated in xenopus laevis embryos that develop without a placenta. expression of slc7a5 was detected in the notochord and in the eye and it was not ...201930625369
reinterpretation of the substrate specificity of the voltage-sensing phosphatase during dimerization.voltage-sensing phosphatases (vsps) cleave both 3- and 5-phosphates from inositol phospholipids in response to membrane depolarization. when low concentrations of ciona intestinalis vsp are expressed in xenopus laevis oocytes, the 5-phosphatase reaction can be observed during large membrane depolarizations. when higher concentrations are expressed, the 5-phosphatase activity is observed with smaller depolarizations, and the 3-phosphatase activity is revealed with strong depolarization. here we a ...201930622132
probing the dynamics and structural topology of the reconstituted human kcnq1 voltage sensor domain (q1-vsd) in lipid bilayers using electron paramagnetic resonance spectroscopy.kcnq1 (kv7.1 or kvlqt1) is a potassium ion channel protein found in the heart, ear, and other tissues. in complex with the kcne1 accessory protein, it plays a role during the repolarization phase of the cardiac action potential. mutations in the channel have been associated with several diseases, including congenital deafness and long qt syndrome. nuclear magnetic resonance (nmr) structural studies in detergent micelles and a cryo-electron microscopy structure of kcnq1 from xenopus laevis have s ...201930620191
immunohistochemical localization of calpains in the amphibian xenopus laevis.though histochemical techniques have been used for decades, they are still very important in basic research. they make it possible to work on fixed tissues and provide a large amount of information in a relatively short time and at a low cost. here we describe methods for indirect immunohistochemistry and immunofluorescence on sections of tadpoles and tissues of adult amphibians belonging to the species xenopus laevis. the objective is to localize calpains within tissues in order to understand t ...201930617797
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