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expression of tcr genes in adult and larval xenopus laevis.in order to better understand the development and function of γδ t cells in xenopus frogs, it is necessary to determine where and when γδ t cells are found in xenopus tissues. this study examined the expression of tcr genes, focused primarily on tcr γ, in tissues of adult and larval xenopus laevis and provide new data about the expression pattern of these different tcr genes in this anuran amphibian. tcr gene expression was detected by rt-pcr in adult frog tissues including the thymus, spleen, s ...201930738793
lissamphibian limbs and the origins of tetrapod hox domains.the expression and function of hox genes have played a key role in the debate on the evolution of limbs from fins. as an early branching tetrapod lineage, lissamphibians may provide information on the origin of the limb's hox domains and particularly how the plesiomorphic tetrapod pattern compares to the hox pattern present in fish fins. here, we comparatively investigated the expression of hox genes in the developing limbs of axolotl and xenopus laevis as well as in the fins of the direct devel ...201931445923
broad applicability of a streamlined ethyl cinnamate-based clearing procedure.turbidity and opaqueness are inherent properties of tissues that limit the capacity to acquire microscopic images through large tissues. creating a uniform refractive index, known as tissue clearing, overcomes most of these issues. these methods have enabled researchers to image large and complex 3d structures with unprecedented depth and resolution. however, tissue clearing has been adopted to a limited extent due to a combination of cost, time, complexity of existing methods and potential nega ...201930665888
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
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
evaluating potential distribution of high-risk aquatic invasive species in the water garden and aquarium trade at a global scale based on current established populations.aquatic non-native invasive species are commonly traded in the worldwide water garden and aquarium markets, and some of these species pose major threats to the economy, the environment, and human health. understanding the potential suitable habitat for these species at a global scale and at regional scales can inform risk assessments and predict future potential establishment. typically, global habitat suitability models are fit for freshwater species with only climate variables, which provides ...201930428498
the peptide transporter 1a of the zebrafish danio rerio, an emerging model in nutrigenomics and nutrition research: molecular characterization, functional properties, and expression analysis.peptide transporter 1 (pept1, alias slc15a1) mediates the uptake of dietary di/tripeptides in all vertebrates. however, in teleost fish, more than one pept1-type transporter might function, due to specific whole genome duplication event(s) that occurred during their evolution leading to a more complex paralogue gene repertoire than in higher vertebrates (tetrapods).201931890051
myelopoiesis of the amphibian xenopus laevis is segregated to the bone marrow, away from their hematopoietic peripheral liver.across vertebrates, hematopoiesis takes place within designated tissues, wherein committed myeloid progenitors further differentiate toward cells with megakaryocyte/erythroid potential (mep) or those with granulocyte/macrophage potential (gmp). while the liver periphery (lp) of the xenopus laevis amphibian functions as a principal site of hematopoiesis and contains meps, cells with gmp potential are instead segregated to the bone marrow (bm) of this animal. presently, using gene expression and w ...201932038608
antiarrhythmic properties of ranolazine: inhibition of atrial fibrillation associated task-1 potassium channels.background: atrial fibrillation (af) is the most common sustained cardiac arrhythmia and one of the major causes of cardiovascular morbidity and mortality. despite good progress within the past years, safe and effective treatment of af remains an unmet clinical need. the anti-anginal agent ranolazine has been shown to exhibit antiarrhythmic properties via mainly late ina and ikr blockade. this results in prolongation of the atrial action potential duration (apd) and effective refractory period ( ...201932038227
expression and ion transport activity of rice oshkt1;1 variants.oshkt1;1 in rice, belongs to the high-affinity k+ transporter family, has been found to be involved in salt tolerance. oshkt1;1 in japonica rice (nipponbare) produces mrna variants, but their functions remain elusive. in salt tolerant rice, pokkali, eight oshkt1;1 variants (v1-v8) were identified in addition to the full-length oshkt1;1 (fl) cdna. absolute quantification by qpcr revealed that accumulation of oshkt1;1-fl mrna is minor in contrast to that of oshkt1;1-v1, -v2, -v4, and -v7 mrnas, al ...201931877741
loc496300 is expressed in the endoderm of developing xenopus laevis embryos. 201932550462
using hdr and a template to introduce an in-frame ha tag on the 3' end of the xenopus laevis gata2.l open reading frame. 201932550411
a novel calcium-activated potassium channel controls membrane potential and intracellular ph in trypanosoma cruzi.trypanosoma cruzi develops in environments where nutrient availability, osmolarity, ionic concentrations, and ph undergo significant changes. the ability to adapt and respond to such conditions determines the survival and successful transmission of t. cruzi. ion channels play fundamental roles in controlling physiological parameters that ensure cell homeostasis by rapidly triggering compensatory mechanisms. combining molecular, cellular and electrophysiological approaches we have identified and ...201932010643
prominin-1 and photoreceptor cadherin localization in xenopus laevis: protein-protein relationships and function.retinal degenerative diseases are genetically diverse and rare inherited disorders that cause the death of rod and cone photoreceptors, resulting in progressive vision loss and blindness. this review will focus on two retinal degeneration-causing genes: prominin-1 (prom1) and photoreceptor cadherin (prcad). we will discuss protein localization, potential roles in photoreceptor outer segment disc morphogenesis, and areas for future investigation.201931884658
autophagy induction by hdac inhibitors is unlikely to be the mechanism of efficacy in prevention of retinal degeneration caused by p23h rhodopsin.we previously found that valproic acid (vpa) and other histone deacetylase inhibitors (hdacis) ameliorate retinal degeneration (rd) caused by p23h rhodopsin in xenopus laevis larvae and hypothesized that this may be due to enhancement of autophagy. here we use x. laevis expressing an autophagy marker to assess effects of hdacis on autophagy. we also assess the effects of non-hdaci activators and inducers of autophagy on rd caused by p23h rhodopsin.201931884645
characterization of spinal cord damage based on automatic video analysis of froglet swimming.xenopus laevis frogs are a widely used organism to study aspects of modern biology ( harland and grainger, 2011). its central nervous system is particularly interesting, because in certain stages of metamorphosis the spinal cord can regenerate after injury and recover swimming. with this in mind, automatic gait analysis could help evaluate the regenerative performance by means of a method that automatically and quantitatively establishes the degree in froglets' limb movement. here, we present an ...201931852668
the chalcone lonchocarpin inhibits wnt/β-catenin signaling and suppresses colorectal cancer proliferation.the deregulation of the wnt/β-catenin signaling pathway is a central event in colorectal cancer progression, thus a promising target for drug development. many natural compounds, such as flavonoids, have been described as wnt/β-catenin inhibitors and consequently modulate important biological processes like inflammation, redox balance, cancer promotion and progress, as well as cancer cell death. in this context, we identified the chalcone lonchocarpin isolated from lonchocarpus sericeus as a wnt ...201931817828
the tff peptides xp1 and xp4 appear in distinctive forms in the xenopus laevis gastric mucosa: indications for different protective functions.the gastric secretory trefoil factor family (tff) peptides xp1 and xp4 are the xenopus laevis orthologs of mammalian tff1 and tff2, respectively. the aim of this study was to analyze the molecular forms of xp1 and xp4 in the x. laevis gastric mucosa by fplc. xp1 mainly occurred in a monomeric low-molecular-mass form and only a minor subset is associated with the mucus fraction. the occurrence of monomeric xp1 is unexpected because of its odd number of cysteine residues. probably a conserved acid ...201931801293
mathematical model explaining the role of cdc6 in the diauxic growth of cdk1 activity during the m-phase of the cell cycle.in this paper we propose a role for the cdc 6 protein in the entry of cells into mitosis. this has not been considered in the literature so far. recent experiments suggest that cdc 6 , upon entry into mitosis, inhibits the appearance of active cdk 1 and cyclin b complexes. this paper proposes a mathematical model which incorporates the dynamics of kinase cdk 1 , its regulatory protein cyclin b, the regulatory phosphatase cdc 25 and the inhibitor cdc 6 known to be involved in the regulation of ac ...201931795221
optimized photo-stimulation of halorhodopsin for long-term neuronal inhibition.optogenetic silencing techniques have expanded the causal understanding of the functions of diverse neuronal cell types in both the healthy and diseased brain. a widely used inhibitory optogenetic actuator is enphr3.0, an improved version of the light-driven chloride pump halorhodopsin derived from natronomonas pharaonis. a major drawback of enphr3.0 is related to its pronounced inactivation on a time-scale of seconds, which renders it unsuited for applications that require long-lasting silencin ...201931775747
a prototype of the mammalian sulfotransferase 1 (sult1) family in xenopus laevis: molecular and enzymatic properties of xlsult1b.s.the cytosolic sulfotransferase 1 (sult1) proteins are a family of highly divergent proteins that show variable expansion in different species during vertebrate evolution. to clarify the evolutionary origin of the mammalian lineage of the sult1 family, we compiled xenopus laevis and x. tropicalis sult1 (xsult1) sequences from public databases. the xsult1 family was found to comprise at least six subfamilies, which corresponded in part to five mammalian sult1 subfamilies but only poorly to zebrafi ...201931748465
in vitro modeling of batrachochytrium dendrobatidis infection of the amphibian skin.the largest current disease-induced loss of vertebrate biodiversity is due to chytridiomycosis and despite the increasing understanding of the pathogenesis, knowledge unravelling the early host-pathogen interactions remains limited. batrachochytrium dendrobatidis (bd) zoospores attach to and invade the amphibian epidermis, with subsequent invasive growth in the host skin. availability of an in vitro assay would facilitate in depth study of this interaction while reducing the number of experiment ...201931725762
cell type-specific transcriptome analysis unveils secreted signaling molecule genes expressed in apical epithelial cap during appendage regeneration.wound epidermis (we) and the apical epithelial cap (aec) are believed to trigger regeneration of amputated appendages such as limb and tail in amphibians by producing certain secreted signaling molecules. to date, however, only limited information about the molecular signatures of these epidermal structures is available. here we used a transgenic xenopus laevis line harboring the enhanced green fluorescent protein (egfp) gene under control of an es1 gene regulatory sequence to isolate we/aec cel ...201931713234
overexpression of ataap1 increased the uptake of an alanine-chlorantraniliprole conjugate in arabidopsis thaliana.transporters play an important role in the uptake and redistribution of agrochemicals to the site of insect feeding. the product of the arabidopsis thaliana gene ataap1 substantially contributes to inorganic nitrogen acquisition under ecologically relevant amino acid concentrations. here, the transporter ability of ataap1 to a chlorantraniliprole-alanine conjugate (cap-ala-1) was tested both in planta and in vitro. thirty-day-old and 15-day-old plants overexpressing ataap1 increased the uptake o ...201931741272
repression of inappropriate gene expression in the vertebrate embryonic ectoderm.during vertebrate embryogenesis, precise regulation of gene expression is crucial for proper cell fate determination. much of what we know about vertebrate development has been gleaned from experiments performed on embryos of the amphibian xenopus laevis; this review will focus primarily on studies of this model organism. an early critical step during vertebrate development is the formation of the three primary germ layers-ectoderm, mesoderm, and endoderm-which emerge during the process of gastr ...201931698780
the role of nitric oxide during embryonic wound healing.the study of the mechanisms controlling wound healing is an attractive area within the field of biology, with it having a potentially significant impact on the health sector given the current medical burden associated with healing in the elderly population. healing is a complex process and includes many steps that are regulated by coding and noncoding rnas, proteins and other molecules. nitric oxide (no) is one of these small molecule regulators and its function has already been associated with ...201931694542
trpc1 as the missing link between the bmp and ca2+ signalling pathways during neural specification in amphibians.in amphibians, the inhibition of bone morphogenetic protein (bmp) in the dorsal ectoderm has been proposed to be responsible for the first step of neural specification, called neural induction. we previously demonstrated that in xenopus laevis embryos, the bmp signalling antagonist, noggin, triggers an influx of ca2+ through voltage-dependent l-type ca2+ channels (ltccs), mainly via cav1.2, and we showed that this influx constitutes a necessary and sufficient signal for triggering the expression ...201931690785
[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
heterologous expression of aedes aegypti cation chloride cotransporter 2 (aeccc2) in xenopus laevis oocytes induces an enigmatic na⁺/li⁺ conductance.the yellow fever mosquito aedes aegypti possesses three genes encoding putative na⁺-coupled cation chloride cotransporters (cccs): aenkcc1, aeccc2, and aeccc3. to date, none of the aecccs have been functionally characterized. here we expressed aeccc2 heterologously in xenopus oocytes and measured the uptake of li⁺ (a tracer for na⁺) and rb⁺ (a tracer for k⁺). compared to control (h₂o-injected) oocytes, the aeccc2-expressing oocytes exhibited significantly greater uptake of li⁺, but not rb⁺. howe ...201930875796
the effects of insecticides on two splice variants of the glutamate-gated chloride channel receptor of the major malaria vector, anopheles gambiae.between half to 1 million people die annually from malaria. anopheles gambiae mosquitoes are major malaria vectors. unfortunately, resistance has emerged to the agents currently used to control a. gambiae, creating a demand for novel control measures. the pentameric glutamate-gated chloride channel (glucl) expressed in the muscle and nerve cells of these organisms are a potentially important biological target for malaria control. the pharmacological properties of anophiline glucl receptors are, ...201931479507
periodic albinism of a widely used albino mutant of xenopus laevis caused by deletion of two exons in the hermansky-pudlak syndrome type 4 gene.the periodic albino mutant of xenopus laevis is a recessive mutant, in which reduced amounts of melanin appear in the retinal pigment epithelium (rpe) and in melanophores at the late embryonic stage, after which both rpe and melanophores gradually depigment. three types of pigment cells (melanophores, iridophores, and xanthophores) have been reported to be affected in this albino. however, the causative gene of the periodic albinism remains unknown. hermansky-pudlak syndrome (hps) is an autosoma ...202033147376
disease-associated hcn4 v759i variant is not sufficient to impair cardiac pacemaking.the hyperpolarization-activated cation current if is a key determinant for cardiac pacemaker activity. it is conducted by subunits of the hyperpolarization-activated cyclic nucleotide-gated (hcn) channel family, of which hcn4 is predominant in mammalian heart. both loss-of-function and gain-of-function mutations of the hcn4 gene are associated with sinus node dysfunction in humans; however, their functional impact is not fully understood yet. here, we sought to characterize a hcn4 v759i variant ...202033095298
using an aquatic model, xenopus laevis, to uncover the role of chromodomain 1 in craniofacial disorders.the chromodomain family member chromodomain 1 (chd1) has been shown to have numerous critical molecular functions including transcriptional regulation, splicing, and dna repair. complete loss of function of this gene is not compatible with life. on the other hand, missense and copy number variants of chd1 can result in intellectual disabilities and craniofacial malformations in human patients including cleft palate and pilarowski-bjornsson syndrome. we have used the aquatic developmental model o ...202032918369
acute consequences of a unilateral viiith nerve transection on vestibulo-ocular and optokinetic reflexes in xenopus laevis tadpoles.loss of peripheral vestibular function provokes severe impairments of gaze and posture stabilization in humans and animals. however, relatively little is known about the extent of the instantaneous deficits. this is mostly due to the fact that in humans a spontaneous loss often goes unnoticed initially and targeted lesions in animals are performed under deep anesthesia, which prevents immediate evaluation of behavioral deficits. here, we use isolated preparations of xenopus laevis tadpoles with ...202032915311
l-glutamic acid monosodium salt reduces the harmful effect of lithium on the development of xenopus laevis embryos.many xenobiotics in the environment affect the human body in various ways. among those xenobiotics, lithium chloride (li, licl) and monosodium glutamate (l-glutamic acid monosodium salt, msg) compounds affect the crucial processes of stem cell differentiation, cell proliferation, developmental gene expression, and overall development in animals. in this study, we aimed to examine the developmental effects of exposure to flavor enhancer msg and lici medicament on xenopus embryos using the frog em ...202032705564
uncoupling sodium channel dimers restores the phenotype of a pain-linked nav 1.7 channel mutation.the voltage-gated sodium channel nav 1.7 is essential for adequate perception of painful stimuli. mutations in the encoding gene, scn9a, cause various pain syndromes in humans. the hnav 1.7/a1632e channel mutant causes symptoms of erythromelalgia and paroxysmal extreme pain disorder (pepd), and its main gating change is a strongly enhanced persistent current. on the basis of recently published 3d structures of voltage-gated sodium channels, we investigated how the inactivation particle binds to ...202032663327
trpm6 and trpm7: novel players in cell intercalation during vertebrate embryonic development.a common theme in organogenesis is how the final structure of organs emerge from epithelial tube structures, with the formation of the neural tube being one of the best examples. two types of cell movements co-occur during neural tube closure involving the migration of cells toward the midline of the embryo (mediolateral intercalation or convergent extension) as well as the deep movement of cells from inside the embryo to the outside of the lateral side of the neural plate (radial intercalation) ...202032315468
effects of bisphenol a and its alternative bisphenol f on notch signaling and intestinal development: a novel signaling by which bisphenols disrupt vertebrate development.we previously found bisphenol a (bpa) alternative, bisphenol f (bpf) upregulated notch-related gene expression in intestines of the african clawed frog xenopus laevis, suggesting an agonistic action on notch signaling, a crucial signaling in multiple biological processes during development. here, we aimed to confirm the actions of bpa and bpf on notch signaling and to reveal their effects on intestinal development. using x. laevis, an excellent model for developmental biology, we found that 10-1 ...202032311622
modeling bainbridge-ropers syndrome in xenopus laevis embryos.the additional sex combs-like (asxl1-3) genes are linked to human neurodevelopmental disorders. the de novo truncating variants in asxl1-3 proteins serve as the genetic basis for severe neurodevelopmental diseases such as bohring-opitz, shashi-pena, and bainbridge-ropers syndromes, respectively. the phenotypes of these syndromes are similar but not identical, and include dramatic craniofacial defects, microcephaly, developmental delay, and severe intellectual disability, with a loss of speech an ...202032132929
hplc reveals novel features of nucleoside and nucleobase homeostasis, nucleoside metabolism and nucleoside transport.humans possess three members of the cation-coupled concentrative nucleoside transporter cnt (slc 28) family, hcnt1-3: hcnt1 is selective for pyrimidine nucleosides but also transports adenosine, hcnt2 transports purine nucleosides and uridine, and hcnt3 transports both pyrimidine and purine nucleosides. hcnt1/2 transport nucleosides using the transmembrane na+ electrochemical gradient, while hcnt3 is both na+- and h+-coupled. by producing recombinant hcnt3 in xenopus laevis oocytes, we have used ...202032126230
evaluation of the effects of low concentrations of bisphenol af on gonadal development using the xenopus laevis model: a finding of testicular differentiation inhibition coupled with feminization.developmental exposures to estrogenic chemicals possibly cause structural and functional abnormalities of reproductive organs in vertebrates. bisphenol af (bpaf), a bisphenol a (bpa) analogue, has been shown to have higher estrogenic activity than bpa, but little is known about the effects of bpaf on gonadal development, particularly gonadal differentiation. we aimed to determine whether low concentrations of bpaf could disrupt gonadal differentiation and subsequent development using xenopus lae ...202031991354
cfap43 modulates ciliary beating in mouse and xenopus.malfunctions of motile cilia cause a variety of developmental defects and diseases in humans and animal model organisms. defects include impaired mucociliary clearance of the airways, sperm immotility, hydrocephalus and organ laterality. here, we characterize the evolutionary conserved cfap43 gene by loss-of-function experiments in the mouse and the frog xenopus laevis. cfap43 is expressed in tissues carrying motile cilia and acts as a target gene of the transcription factor foxj1, which is esse ...202031884020
insights regarding skin regeneration in non-amniote vertebrates: skin regeneration without scar formation and potential step-up to a higher level of regeneration.skin wounds are among the most common injuries in animals and humans. vertebrate skin is composed of an epidermis and dermis. after a deep skin injury in mammals, the wound heals, but the dermis cannot regenerate. instead, collagenous scar tissue forms to fill the gap in the dermis, but the scar does not function like the dermis and often causes disfiguration. in contrast, in non-amniote vertebrates, including fish and amphibians, the dermis and skin derivatives are regenerated after a deep skin ...202031831357
impact of copper in xenopus laevis liver: histological damages and atp7b downregulation.copper is an essential micronutrient but its excess in the dietary can be toxic. both copper deficiency and abundance can occur in natural conditions and can lead to pathological dysfunctions. many of the toxic effects of copper, such as increased lipid peroxidation in cell membranes and dna damage, are due to its role in the generation of oxygen free radicals. copper is released into the environment by both natural sources and human activities and it can damage organisms and ecosystems. in the ...202031757510
the hkt transporter hvhkt1;5 negatively regulates salt tolerance.maintaining low intracellular na+ concentrations is an essential physiological strategy in salt stress tolerance in most cereal crops. here, we characterized a member of the high-affinity k+ transporter (hkt) family in barley (hordeum vulgare), hvhkt1;5, which negatively regulates salt tolerance and has different functions from its homology in other cereal crops. hvhkt1;5 encodes a plasma membrane protein localized to root stele cells, particularly in xylem parenchyma cells adjacent to the xylem ...202031690708
simple method to characterize the ciliary proteome of multiciliated cells.motile cilia of multiciliated epithelial cells have important roles in animal development and cell homeostasis. although several studies have identified and reported proteins localized in this complex organelle and the related immotile primary cilia from various cell types, it is still challenging to isolate high quantities of ciliary proteins for proteomic analysis. in this study, african clawed frog (xenopus laevis) embryos, which have many multiciliated cells in the epidermis, were treated wi ...202031689115
complement c1q subunit molecules from xenopus laevis possess conserved function in c1q-immunoglobulin interaction.complement component 1q (c1q), together with c1r and c1s to form c1, recognize and bind immune complex to initiate the classical complement pathway. in this study, c1q subunit molecules (xlc1qa, xlc1qb, xlc1qc) were cloned and analyzed from xenopus laevis (x. laevis). the open reading frame (orf) of xlc1qa is 819 bp of nucleotide sequence encoding 272 amino acids, the orf of xlc1qb is 711 bp encoding 236 aa, and the xlc1qc is consists of 732 bp encoding 243 aa. the deduced amino acid sequences c ...202031678076
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
human cationic amino acid transporters are not affected by direct nitros(yl)ation.a direct inhibiting effect of no on the function of cat-1 and -2a has been postulated to occur via nitrosylation of cysteine residues in the transporters. neither the no donor snap nor a mixture of sin-1 and spermine nonoate, that generates the strong nitrosating agent n2o3, reduced cat-mediated l-arginine transport. direct nitros(yl)ation does either not occur in cats or does not affect their transport function. a regulatory effect of no or nitrosating agents on cat-mediated transport under phy ...202032008093
structural basis of the fanconi anemia-associated mutations within the fanca and fancg complex.monoubiquitination of the fanconi anemia complementation group d2 (fancd2) protein by the fa core ubiquitin ligase complex is the central event in the fa pathway. fanca and fancg play major roles in the nuclear localization of the fa core complex. mutations of these two genes are the most frequently observed genetic alterations in fa patients, and most point mutations in fanca are clustered in the c-terminal domain (ctd). to understand the basis of the fa-associated fanca mutations, we determine ...202032002546
tectal crfr1 receptor involvement in avoidance and approach behaviors in the south african clawed frog, xenopus laevis.animals in the wild must balance food intake with vigilance for predators in order to survive. the optic tectum plays an important role in the integration of external (predators) and internal (energy status) cues related to predator defense and prey capture. however, the role of neuromodulators involved in tectal sensorimotor processing is poorly studied. recently we showed that tectal crfr1 receptor activation decreases food intake in the south african clawed frog, xenopus laevis, suggesting th ...202032001211
cav2.1 c-terminal fragments produced in xenopus laevis oocytes do not modify the channel expression and functional properties.the sequence and genomic organization of the cacna1a gene that encodes the cav2.1 subunit of both p and q-type ca2+ channels are well conserved in mammals. in human, rat and mouse cacna1a, the use of an alternative acceptor site at the exon 46-47 boundary results in the expression of a long cav2.1 splice variant. in transfected cells, the long isoform of human cav2.1 produces a c-terminal fragment, but it is not known whether this fragment affects cav2.1 expression or functional properties. here ...202031981388
subcellular localization of the tff peptides xp1 and xp4 in the xenopus laevis gastric/esophageal mucosa: different secretion modes reflecting diverse protective functions.the tff peptides xp1 and xp4 from xenopus laevis are orthologs of tff1 and tff2, respectively. xp1 is secreted as a monomer from gastric surface mucous cells and is generally not associated with mucins, whereas xp4 is a typical secretory peptide from esophageal goblet cells, and gastric mucous neck and antral gland cells tightly associated as a lectin with the ortholog of mucin muc6. both tff peptides have diverse protective functions, xp1 as a scavenger for reactive oxygen species preventing ox ...202031979419
expression of α3β2β4 nicotinic acetylcholine receptors by rat adrenal chromaffin cells determined using novel conopeptide antagonists.adrenal chromaffin cells release neurotransmitters in response to stress and may be involved in conditions such as post-traumatic stress and anxiety disorders. neurotransmitter release is triggered, in part, by activation of nicotinic acetylcholine receptors (nachrs). however, despite decades of use as a model system for studying exocytosis, the nachr subtypes involved have not been pharmacologically identified. quantitative real-time pcr of rat adrenal medulla revealed an abundance of mrnas for ...202031967330
hydrogen sulfide impairs meiosis resumption in xenopuslaevis oocytes.the role of hydrogen sulfide (h2s) is addressed in xenopuslaevis oocytes. three enzymes involved in h2s metabolism, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase, were detected in prophase i and metaphase ii-arrested oocytes and drove an acceleration of oocyte meiosis resumption when inhibited. moreover, meiosis resumption is associated with a significant decrease in endogenous h2s. on another hand, a dose-dependent inhibition was obtained using the h2 ...202031963573
convergent extension in the amphibian, xenopus laevis.this review is a comprehensive analysis of the cell biology and biomechanics of convergent extension in xenopus.202031959291
biochemical reconstitution of branching microtubule nucleation.microtubules are nucleated from specific locations at precise times in the cell cycle. however, the factors that constitute these microtubule nucleation pathways and their mode of action still need to be identified. using purified xenopus laevis proteins we biochemically reconstitute branching microtubule nucleation, which is critical for chromosome segregation. we found that besides the microtubule nucleator gamma-tubulin ring complex (γ-turc), the branching effectors augmin and tpx2 are requir ...202031933480
developmental and lethal effects of glyphosate and a glyphosate-based product on xenopus laevis embryos and tadpoles.effects of pure glyphosate and a glyphosate-based product were evaluated comparatively using two embryonic development stages of xenopus laevis as model system. when pure glyphosate was applied in ph adjusted media, lethal or developmental effects were not observed at concentrations up to 500 mg l-1. the 96 h lc50 values for the commercial herbicide, in contrast, were 32.1 and 35.1 mg active ingredient l-1 for embryos and tadpoles, respectively. since pure glyphosate has no effect on the selecte ...202031932905
reciprocal matched filtering in the inner ear of the african clawed frog (xenopus laevis).anurans (frogs and toads) are the most vocal amphibians. in most species, only males produce advertisement calls for defending territories and attracting mates. female vocalizations are the exceptions among frogs, however in the african clawed frog (xenopus laevis) both males and females produce distinct vocalizations. the matched filter hypothesis predicts a correspondence between peripheral auditory tuning of receivers and properties of species-specific acoustic signals, but few studies have a ...202031907715
xenopus embryos show a compensatory response following perturbation of the notch signaling pathway.as an essential feature of development, robustness ensures that embryos attain a consistent phenotype despite genetic and environmental variation. the growing number of examples demonstrating that embryos can mount a compensatory response to germline mutations in key developmental genes has heightened interest in the phenomenon of embryonic robustness. while considerable progress has been made in elucidating genetic compensation in response to germline mutations, the diversity, mechanisms, and l ...202031899211
generation, coordination, and evolution of neural circuits for vocal communication.in many species, vocal communication is essential for coordinating social behaviors including courtship, mating, parenting, rivalry, and alarm signaling. effective communication requires accurate production, detection, and classification of signals, as well as selection of socially appropriate responses. understanding how signals are generated and how acoustic signals are perceived is key to understanding the neurobiology of social behaviors. here we review our long-standing research program foc ...202031896561
genome-wide analysis identifies cis-acting elements regulating mrna polyadenylation and translation during vertebrate oocyte maturation.most cells change patterns of gene expression through transcriptional regulation. in contrast, oocytes are transcriptionally silent and regulate mrna poly(a) tail length to control protein production. however, the genome-wide relationship of poly(a) tail changes to mrna translation during vertebrate oocyte maturation is not known. we used tail-seq and polyribosome analysis to measure poly(a) tail and translational changes during oocyte maturation in xenopus laevis we identified large-scale poly( ...202031896558
chemical and voltage gating of gap junction channels expressed in xenopus oocytes.in most tissues, cells in contact with each other directly intercommunicate via cell-to-cell channels aggregated at gap junctions. direct cell-to-cell communication provides a fundamental mechanism for coordinating many cellular functions in mature and developing organs, as it enables free exchange of small cytosolic molecules. gap junction channels are regulated by a chemical gating mechanism sensitive to cytosolic calcium concentration [ca2+]i in the nanomolar range mediated by ca2+-activated ...202032548808
investigating the impact of the phosphorylation status of tyrosine residues within the tacc domain of tacc3 on microtubule behavior during axon growth and guidance.axon guidance is a critical process in forming the connections between a neuron and its target. the growth cone steers the growing axon toward the appropriate direction by integrating extracellular guidance cues and initiating intracellular signal transduction pathways downstream of these cues. the growth cone generates these responses by remodeling its cytoskeletal components. regulation of microtubule dynamics within the growth cone is important for making guidance decisions. tacc3, as a micro ...202032543081
the transition state and regulation of γ-turc-mediated microtubule nucleation revealed by single molecule microscopy.determining how microtubules (mts) are nucleated is essential for understanding how the cytoskeleton assembles. while the mt nucleator, γ-tubulin ring complex (γ-turc) has been identified, precisely how γ-turc nucleates a mt remains poorly understood. here, we developed a single molecule assay to directly visualize nucleation of a mt from purified xenopus laevis γ-turc. we reveal a high γ-/αβ-tubulin affinity, which facilitates assembly of a mt from γ-turc. whereas spontaneous nucleation require ...202032538784
functional characterization of the arabidopsis ammonium transporter atamt1;3 with the emphasis on structural determinants of substrate binding and permeation properties.atamt1;3 is a major contributor to high-affinity ammonium uptake in arabidopsis roots. using a stable electrophysiological recording strategy, we demonstrate in xenopus laevis oocytes that atamt1;3 functions as a typical high-affinity nh4+ uniporter independent of protons and ca2+. the findings that atamt1;3 transports methylammonium (mea+, a chemical analog of nh4+) with extremely low affinity (km in the range of 2.9-6.1 mm) led to investigate the mechanisms underlying substrate binding. homolo ...202032528489
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