Publications

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morphomechanical reactions and mechanically stressed structures in amphibian embryos, as related to gastrulation and axial organs formation.reactions of embryonic tissues to a distributed and concentrated stretching are described and compared with the mechanics of the normal gastrulation movements. a role of mechanically stressed dynamic cell structures in the gastrulation, demarcation of notochord borders and in providing proportionality of the axial rudiments is demonstrated. a morphomechanical scheme of amphibian gastrulation is presented.201830321583
reconstitution of cell-cycle oscillations in microemulsions of cell-free xenopus egg extracts.real-time measurement of oscillations at the single-cell level is important to uncover the mechanisms of biological clocks. although bulk extracts prepared from xenopus laevis eggs have been powerful in dissecting biochemical networks underlying the cell-cycle progression, their ensemble average measurement typically leads to a damped oscillation, despite each individual oscillator being sustained. this is due to the difficulty of perfect synchronization among individual oscillators in noisy bio ...201830320763
assembly of protein complexes restricts diffusion of wnt3a proteins.members of the wnt protein family play roles in many aspects of embryogenesis and homeostasis. despite their biological significance, characteristics of wnt proteins still remain unclear, mainly due to their insolubility after the removal of serum. here we examine wnt proteins in serum-containing media by using analytical ultracentrifugation with a fluorescence detection system. this analysis reveals that wnt3a assembles into high-molecular-weight complexes that become dissociable by interaction ...201830320232
polystyrene microplastics did not affect body growth and swimming activity in xenopus laevis tadpoles.a growing number of studies have highlighted the contamination and the effects towards organisms of diverse microplastics (μps) in the marine environment. surprisingly, although the main sources of μps for marine environments are inland surface waters, the information on the occurrence and the effects of μps in freshwater ecosystems is still scant. thus, the aim of the present work is to investigate the ingestion and possible adverse effects due to the exposure to polystyrene μps (psμps; ø = 3 μ ...201830317408
unusual light-reflecting pigment cells appear in the xenopus neural tube culture system in the presence of guanosine.isolation and culture of xenopus laevis neural tubes resulted in differentiation of melanophores and iridophores from neural crest cells; the differentiated melanophores and iridophores were then maintained in culture for more than 6 months. guanosine has been reported to promote reflecting platelet formation in melanin-producing pigment cells; however, the process of pigment organellogenesis is still unclear. in the present study, unusual light-reflecting pigment cells were observed upon additi ...201830309510
uroplakins play conserved roles in egg fertilization and acquired additional urothelial functions during mammalian divergence.uroplakin (up) tetraspanins and their associated proteins are major mammalian urothelial differentiation products that form unique two-dimensional crystals of 16-nm particles ("urothelial plaques") covering the apical urothelial surface. although uroplakins are highly expressed only in mammalian urothelium and are often referred to as being urothelium specific, they are also expressed in several mouse nonurothelial cell types in stomach, kidney, prostate, epididymis, testis/sperms, and ovary/ooc ...201830303751
retinal tissue preparation for high-resolution live imaging of photoreceptors expressing multiple transgenes.live imaging has become the favorite method in recent years to study the protein transport, localization and dynamics in live cells. protein transport is extremely essential for proper function of photoreceptors. aberration in the proper transport of proteins gives rise to the loss of photoreceptor and blindness. on the other hand, the ease of generation of transgenic xenopus laevis tadpoles and the advantage of high resolution live confocal imaging provide new insight into understanding protein ...201830302320
antibacterial and antibiofilm activity and mode of action of magainin 2 against drug-resistant acinetobacter baumannii.antimicrobial peptides (amps) are promising therapeutic agents for treating antibiotic-resistant bacterial infections. previous studies showed that magainin 2 (isolated from african clawed fogs xenopus laevis) has antimicrobial activity against gram-positive and gram-negative bacteria. the present study was conducted to investigate the antibacterial activity of magainin 2 against acinetobacter baumannii. magainin 2 showed excellent antibacterial activity against a. baumannii strains and high sta ...201830301180
functional analysis of a triplet deletion in the gene encoding the sodium glucose transporter 3, a potential risk factor for adhd.sodium-glucose transporters (sglt) belong to the solute carrier 5 family, which is characterized by sodium dependent transport of sugars and other solutes. in contrast, the human sglt3 (hsglt3) isoform, encoded by slc5a4, acts as a glucose sensor that does not transport sugar but induces membrane depolarization by na+ currents upon ligand binding. whole-exome sequencing (wes) of several extended pedigrees with high density of attention-deficit/hyperactivity disorder (adhd) identified a triplet a ...201830286162
nucleosomes and the three glycosylases: high, medium, and low levels of excision by the uracil dna glycosylase superfamily.human cells express the udg superfamily of glycosylases, which excise uracil (u) from the genome. the three members of this structural superfamily are uracil dna glycosylase (ung/udg), single-strand selective monofunctional uracil dna glycosylase (smug1), and thymine dna glycosylase (tdg). we previously reported that udg is efficient at removing u from dna packaged into nucleosome core particles (ncp) and is minimally affected by the histone proteins when acting on an outward-facing u in the dya ...201830268365
a xenopus oocyte model system to study action potentials.action potentials (aps) are the functional units of fast electrical signaling in excitable cells. the upstroke and downstroke of an ap is generated by the competing and asynchronous action of na+- and k+-selective voltage-gated conductances. although a mixture of voltage-gated channels has been long recognized to contribute to the generation and temporal characteristics of the ap, understanding how each of these proteins function and are regulated during electrical signaling remains the subject ...201830266757
amphibian (xenopus laevis) interleukin-8 (cxcl8): a perspective on the evolutionary divergence of granulocyte chemotaxis.the glutamic acid-leucine-arginine (elr) motif is a hallmark feature shared by mammalian inflammatory cxc chemokines such the granulocyte chemo-attractant cxcl8 (interleukin-8, il-8). by contrast, most teleost fish inflammatory chemokines lack this motif. interestingly, the amphibian xenopus laevis encodes multiple isoforms of cxcl8, one of which (cxcl8a) possesses an elr motif, while another (cxcl8b) does not. these cxcl8 isoforms exhibit distinct expression patterns during frog development and ...201830258441
molecular determinants of α-conotoxin potency for inhibition of human and rat α6β4 nicotinic acetylcholine receptors.nicotinic acetylcholine receptors (nachrs) containing α6 and β4 subunits are expressed by dorsal root ganglion neurons and have been implicated in neuropathic pain. rodent models are often used to evaluate the efficacy of analgesic compounds, but species differences may affect the activity of some nachr ligands. a previous candidate α-conotoxin-based therapeutic yielded promising results in rodent models, but failed in human clinical trials, emphasizing the importance of understanding species di ...201830249616
the balance of two opposing factors mad and myc regulates cell fate during tissue remodeling.cell proliferation and differentiation are two distinct yet coupled processes in development in diverse organisms. understanding the molecular mechanisms that regulate this process is a central theme in developmental biology. the intestinal epithelium is a highly complex tissue that relies on the coordination of cell proliferation within the crypts and apoptosis mainly at the tip of the villi, preservation of epithelial function through differentiation, and homeostatic cell migration along the c ...201830237868
two tier hox collinearity mediates vertebrate axial patterning.a two tier mechanism mediates hox collinearity. besides the familiar collinear chromatin modification within each hox cluster (nanocollinearity), there is also a macrocollinearity tier. individual hox clusters and individual cells are coordinated and synchronized to generate multiscale (macro and nano) collinearity in the early vertebrate embryo. macro-collinearity is mediated by three non-cell autonomous hox-hox interactions. these mediate temporal collinearity in early nom (non-organizer mesod ...201830234110
dscam differentially modulates pre- and postsynaptic structural and functional central connectivity during visual system wiring.proper patterning of dendritic and axonal arbors is a critical step in the formation of functional neuronal circuits. developing circuits rely on an array of molecular cues to shape arbor morphology, but the underlying mechanisms guiding the structural formation and interconnectivity of pre- and postsynaptic arbors in real time remain unclear. here we explore how down syndrome cell adhesion molecule (dscam) differentially shapes the dendritic morphology of central neurons and their presynaptic r ...201830219101
systematic variation of the benzoylhydrazine moiety of the glun2a selective nmda receptor antagonist tcn-201.glun2a containing n-methyl-d-aspartate receptors (nmdars) are important ion channels in the central nervous system and highly involved in several different neurophysiological but also neuropathophysiological processes. however, current understanding of the contribution of glun2a containing nmdars in these processes is incomplete. therefore, highly selective compounds are required to further investigate these ion channels. in 2010, tcn-201 (2), one of the first selective negative allosteric modul ...201830218911
bighead is a wnt antagonist secreted by the xenopus spemann organizer that promotes lrp6 endocytosis.the xenopus laevis embryo has been subjected to almost saturating screens for molecules specifically expressed in dorsal spemann organizer tissue. in this study, we performed high-throughput rna sequencing of ectodermal explants, called animal caps, which normally give rise to epidermis. we analyzed dissociated animal cap cells that, through sustained activation of mapk, differentiate into neural tissue. we also microinjected mrnas for cerberus, chordin, fgf8, bmp4, wnt8, and xnr2, which induce ...201830209221
a review of interventions against fetal alcohol spectrum disorder targeting oxidative stress.fetal alcohol spectrum disorder is caused by maternal ethanol exposure; it causes physical, behavioral, cognitive, and neural impairments (murawski et al., 2015). mechanisms of fasd causing damage are not yet fully elucidated. oxidative stress might be one of its mechanisms (henderson et al., 1995). yet no effective treatment against fasd has been found other than ethanol abstention (long et al., 2010).201830205148
in vitro analyses of novel hcn4 gene mutations.the hyperpolarization-activated cyclic nucleotide-gated cation channel hcn4 contributes significantly to the generation of basic cardiac electrical activity in the sinus node and is a mediator of modulation by β-adrenergic stimulation. heterologous expression of sick sinus syndrome (sss) and bradycardia associated mutations within the human hcn4 gene results in altered channel function. the main aim was to describe the functional characterization of three (two novel and one known) missense mutat ...201830196304
inward rectifier potassium (kir) channels in the soybean aphid aphis glycines: functional characterization, pharmacology, and toxicology.inward rectifier k+ (kir) channels contribute to a variety of physiological processes in insects and are emerging targets for insecticide development. previous studies on insect kir channels have primarily focused on dipteran species (e.g., mosquitoes, fruit flies). here we identify and functionally characterize kir channel subunits in a hemipteran insect, the soybean aphid aphis glycines, which is an economically important insect pest and vector of soybeans. from the transcriptome and genome of ...201830196125
a dual-app nucleoside probe provides structural insights into the human telomeric overhang in live cells.understanding the topology adopted by individual g-quadruplex (gq)-forming sequences in vivo and targeting a specific gq motif among others in the genome will have a profound impact on gq-directed therapeutic strategies. however, this remains a major challenge as most of the tools poorly distinguish different gq conformations and are not suitable for both cell-free and in-cell analysis. here, we describe an innovative probe design to investigate gq conformations and recognition in both cell-free ...201830192541
multiscale analysis of architecture, cell size and the cell cortex reveals cortical f-actin density and composition are major contributors to mechanical properties during convergent extension.the large-scale movements that construct complex three-dimensional tissues during development are governed by universal physical principles. fine-grained control of both mechanical properties and force production is crucial to the successful placement of tissues and shaping of organs. embryos of the frog xenopus laevis provide a dramatic example of these physical processes, as dorsal tissues increase in young's modulus by six-fold to 80 pascal over 8 h as germ layers and the central nervous syst ...201830190279
draft genome of dugesia japonica provides insights into conserved regulatory elements of the brain restriction gene nou-darake in planarians.planarians are non-parasitic platyhelminthes (flatworms) famous for their regeneration ability and for having a well-organized brain. dugesia japonica is a typical planarian species that is widely distributed in the east asia. extensive cellular and molecular experimental methods have been developed to identify the functions of thousands of genes in this species, making this planarian a good experimental model for regeneration biology and neurobiology. however, no genome-level information is ava ...201830181897
the cytoskeletal protein zyxin interacts with the zinc-finger transcription factor zic1 and plays the role of a scaffold for gli1 and zic1 interactions during early development of xenopus laevis.we have shown recently that the cytoskeletal protein zyxin participates in the fine tuning of the neural plate pattering in xenopus laevis embryos by modulating activity of one of the effectors of hedgehog (shh) signaling cascade, the transcription factor gli1. in the present work, we show that zyxin can also interact with the potential modulator of the shh pathway, the transcription factor zic1. the interaction of proteins occurs primarily by mean of the zinc-finger domain of zic1 and 2nd lim d ...201830180953
a single xlf dimer bridges dna ends during nonhomologous end joining.nonhomologous end joining (nhej) is the primary pathway of dna double-strand-break repair in vertebrate cells, yet how nhej factors assemble a synaptic complex that bridges dna ends remains unclear. to address the role of xrcc4-like factor (xlf) in synaptic-complex assembly, we used single-molecule fluorescence imaging in xenopus laevis egg extract, a system that efficiently joins dna ends. we found that a single xlf dimer binds dna substrates just before the formation of a ligation-competent sy ...201830177755
ras-dva small gtpases lost during evolution of amniotes regulate regeneration in anamniotes.in contrast to amniotes (reptiles, birds and mammals), anamniotes (fishes and amphibians) can effectively regenerate body appendages such as fins, limbs and tails. why such a useful capability was progressively lost in amniotes remains unknown. as we have hypothesized recently, one of the reasons for this could be loss of some genes regulating the regeneration in evolution of amniotes. here, we demonstrate the validity of this hypothesis by showing that genes of small gtpases ras-dva1 and ras-dv ...201830158598
isolation and primary culture methods of adult and larval myogenic cells from xenopus laevis.during amphibian metamorphosis, larval-to-adult conversion of the myogenic system occurs and there are two distinct types of muscle stem cells; larval myogenic cells have a death-fate by apoptosis in the presence of thyroid hormone t3, and adult myogenic cells have a life-fate under the same conditions. here, we describe isolation and culture methods for adult and larval myogenic cells from the frog, xenopus laevis. both types of cultured myogenic cells undergo cell division and cell differentia ...201830151775
isolation and culture of amphibian (xenopus laevis) sub-capsular liver and bone marrow cells.the x. laevis sub-capsular liver is thought to be the principal hematopoietic site of xenopodinae species from early development and, in case of certain species, into adulthood. the xenopus bone marrow appears to be comprised of precursor cells committed to myeloid lineages, such as macrophage- and granulocyte-progenitor cells. with alarming increases in the contribution of pathogenic infections to the global amphibian declines, now more than ever a better understanding of the mechanisms control ...201830151774
x-fact: xenopus-fast clearing technique.accessibility and imaging of cell compartments in big specimens are crucial for cellular biological research but also a matter of contention. confocal imaging and tissue clearing on whole organs allow for 3d imaging of cellular structures after being subjected to in-toto immunohistochemistry. lately, the passive clarity technique (pact) has been adapted to clear and immunolabel large specimens or individual organs of several aquatic species. we recently demonstrated tissue clearing on one-week o ...201830151770
dye electroporation and imaging of calcium signaling in xenopus nervous system.electroporation is an efficient method of transferring charged macromolecules into living cells in order to study their morphology, function, and connectivity within neuronal networks. labeling cells with fluorophore-coupled macromolecules can be used to trace projections of whole neuronal ensembles, as well as the fine morphology of single cells. here, we present a protocol to visualize pre- and postsynaptic components of a sensory relay synapse in the brain, using the olfactory system of xenop ...201830151769
quantitative proteomics for xenopus embryos ii, data analysis.the oocytes, embryos, and cell-free lysates of the frog xenopus laevis have emerged as powerful models for quantitative proteomic experiments. in the accompanying paper (chapter 13) we describe how to prepare samples and acquire multiplexed proteomics spectra from those. as an illustrative example we use a 10-stage developmental time series from the egg to stage 35 (just before hatching). here, we outline how to convert the ~700,000 acquired mass spectra from this time series into protein expres ...201830151768
quantitative proteomics of xenopus embryos i, sample preparation.xenopus oocytes and embryos are model systems optimally suited for quantitative proteomics. this is due to the availability of large amount of protein material and the ease of physical manipulation. furthermore, facile in vitro fertilization provides superbly synchronized embryos for cell cycle and developmental stages. here, we detail protocols developed over the last few years for sample preparation of multiplexed proteomics with tmt-tags followed by quantitative mass spectrometry analysis usi ...201830151767
a simple knock-in system for xenopus via microhomology mediated end joining repair.following completion of the genome sequences of xenopus tropicalis and x. laevis, gene targeting techniques have become increasingly important for the further development of xenopus research in the life sciences. gene knockout using programmable nucleases, such as talen and crispr/cas9, has reached a level whereby we can readily and routinely perform loss-of-function analysis of genes of interest in these species. however, there is still room for improvement in gene knock-in techniques owing to ...201830151761
generation and care of xenopus laevis and xenopus tropicalis embryos.robust and efficient protocols for fertilization and early embryo care of xenopus laevis and xenopus tropicalis are essential for experimental success, as well as maintenance and propagation of precious animal stocks. the rapid growth of the national xenopus resource has required effective implementation and optimization of these protocols. here, we discuss the procedures used at the national xenopus resource, which we found helpful for generation and early upkeep of xenopus embryos and tadpoles ...201830151756
husbandry, general care, and transportation of xenopus laevis and xenopus tropicalis.maintenance of optimal conditions such as water parameters, diet, and feeding is essential to a healthy xenopus laevis and xenopus tropicalis colony and thus to the productivity of the lab. our prior husbandry experience as well as the rapid growth of the national xenopus resource has given us a unique insight into identifying and implementing these optimal parameters into our husbandry operations. here, we discuss our standard operating procedures that will be of use to both new and established ...201830151755
evaluating iodide recycling inhibition as a novel molecular initiating event for thyroid axis disruption in amphibians.the enzyme iodotyrosine deiodinase (dehalogenase, iyd) catalyzes iodide recycling and promotes iodide retention in thyroid follicular cells. loss of function or chemical inhibition of iyd reduces available iodide for thyroid hormone synthesis, which leads to hormone insufficiency in tissues and subsequent negative developmental consequences. iyd activity is especially critical under conditions of lower dietary iodine and in low iodine environments. our objective was to evaluate the toxicological ...201830137636
kv12.1 channels are not sensitive to gqpcr-triggered activation of phospholipase cβ.kv12.1 k+ channels are expressed in several brain areas, but no physiological function could be attributed to these subunits so far. as genetically-modified animal models are not available, identification of native kv12.1 currents must rely on characterization of distinct channel properties. recently, it was shown in xenopus laevis oocytes that kv12.1 channels were modulated by membrane pi(4,5)p2. however, it is not known whether these channels are also sensitive to physiologically-relevant pi(4 ...201830136882
developmental dependence for functional eye regrowth in xenopus laevis. 201830136686
photocatalytic degradation of azo dye using core@shell nano-tio2 particles to reduce toxicity.clean and safe water is fundamental for human and environmental health. traditional remediation of textile dye-polluted water with chemical, physical, and biological processes has many disadvantages. due to this, nano-engineered materials are drawing more attention to this area. however, the widespread use of nano-particles for this purpose may lead to photocatalytic degradation of xenobiotics, while increasing the risk of nano-particle-induced ecotoxicity. therefore, we comparatively evaluated ...201830136182
cross-limb communication during xenopus hindlimb regenerative response: non-local bioelectric injury signals.regeneration of damaged body parts requires coordination of size, shape, location and orientation of tissue with the rest of the body. it is not currently known to what extent injury sites communicate with the remaining soma during repair, or what information may emanate from the injury site and reach other regions. we examined the bioelectric properties (resting potential gradients in the epidermis) of xenopus laevis froglets undergoing hindlimb amputation and observed that the contralateral (u ...201830126906
molecular characterization of wdr68 gene in embryonic development of xenopus laevis.wdr68, also known as dcaf7, is a wd40 repeated domain protein highly conserved in eukaryotic organisms in both plants and animals. this protein participates in numerous cellular processes and exerts its function through interaction with other proteins. in the present work, we isolated, sequenced and characterized cdna corresponding to the wdr68 gene in embryos of the amphibian xenopus laevis. syntenic analysis revealed high conservation of the genomic region containing the wdr68 locus in amniote ...201830125741
in vitro expression and functional characterization of npa motifs in aquaporins of nosema bombycis.nosema bombycis contains functional aquaporins (nbaqps), which are key targets for exploring the mechanism of n. bombycis infection; however, the regulation of these nbaqps remains unknown. the two highly conserved asparagine-proline-alanine sequences (npa motifs) play important roles in aqp biogenesis. as part of this study, we constructed a series of nbaqp mutants (nbaqp_npa1, nbaqp_npa2, and nbaqp_npa1,2) and expressed them in bmn cells. the results showed that mutations in either npa motif o ...201830105406
rare coding variants in genes encoding gabaa receptors in genetic generalised epilepsies: an exome-based case-control study.genetic generalised epilepsy is the most common type of inherited epilepsy. despite a high concordance rate of 80% in monozygotic twins, the genetic background is still poorly understood. we aimed to investigate the burden of rare genetic variants in genetic generalised epilepsy.201830033060
des-formylflustrabromine (dfbr): a structure-activity study on its ability to potentiate the action of acetylcholine at α4β2 nicotinic acetylcholine receptors.the naturally occurring indole alkaloid des-formylflustrabromine (dfbr; 1) is one of the first agents shown to act as a selective positive allosteric modulator (pam) at α4β2 nicotinic acetylcholine receptors (nachrs). we previously deconstructed this agent to determine which of its structural features contribute to its actions and have identified an agent that might serve as the basis for a " working pharmacophore". here, we elaborate the dfbr (1; ec50 = 0.2 μm) structure to identify how various ...201830028943
transplantation of ears provides insights into inner ear afferent pathfinding properties.numerous tissue transplantations have demonstrated that otocysts can develop into normal ears in any location in all vertebrates tested thus far, though the pattern of innervation of these transplanted ears has largely been understudied. here, expanding on previous findings that transplanted ears demonstrate capability of local brainstem innervation and can also be innervated themselves by efferents, we show that inner ear afferents grow toward the spinal cord mostly along existing afferent and ...201830027559
amphibian (xenopus laevis) tadpoles and adult frogs differ in their use of expanded repertoires of type i and type iii interferon cytokines.while amphibians around the globe are facing catastrophic declines, in part because of infections with pathogens such as the frog virus 3 (fv3) ranavirus; the mechanisms governing amphibian susceptibility and resistance to such pathogens remain poorly understood. the type i and type iii interferon (ifn) cytokines represent a cornerstone of vertebrate antiviral immunity, while our recent work indicates that tadpoles and adult frogs of the amphibian xenopus laevis may differ in their ifn responses ...201830018186
the b-hlh transcription factor hes3 participates in neural plate border formation by interfering with wnt/β-catenin signaling.hes3 belongs to the hes basic helix-loop-helix family of transcriptional repressors that play central roles in maintaining progenitor cells and regulating binary cell fate decisions in the embryo. during xenopus laevis development, hes3 is expressed in the embryonic ectoderm in a horseshoe shape domain at the edge of the developing neural pate. hes3 mis-expression at early neurula stage blocks neural crest (snai2, sox8, sox9 and sox10) and cranial placode (six1 and dmrta1) gene expression, and p ...201830016640
plc and ip3-evoked ca2+ release initiate the fast block to polyspermy in xenopus laevis eggs.the prevention of polyspermy is essential for the successful progression of normal embryonic development in most sexually reproducing species. in external fertilizers, the process of fertilization induces a depolarization of the egg's membrane within seconds, which inhibits supernumerary sperm from entering an already-fertilized egg. this fast block requires an increase of intracellular ca2+ in the african clawed frog, xenopus laevis, which in turn activates an efflux of cl- that depolarizes the ...201830012841
comprehensive substrate characterization of 22 antituberculosis drugs for multiple solute carrier (slc) uptake transporters in vitro.the substrate potentials of antituberculosis drugs on solute carrier (slc) transporters are not well characterized to date, despite a well-established understanding of their drug dispositions and pharmacokinetics. in this study, we investigated comprehensively the substrate potentials of the 22 currently available antituberculosis drugs for slc family transporter-mediated uptake, using xenopus laevis oocytes and stably transfected hek-293 cells in vitro the result suggested that ethambutol, ison ...201830012768
a gene regulatory network underlying the formation of pre-placodal ectoderm in xenopus laevis.the neural plate border ectoderm gives rise to key developmental structures during embryogenesis, including the neural crest and the preplacodal ectoderm. many sensory organs and ganglia of vertebrates develop from cranial placodes, which themselves arise from preplacodal ectoderm, defined by expression of transcription factor six1 and its coactivator eya1. here we elucidate the gene regulatory network underlying the specification of the preplacodal ectoderm in xenopus, and the functional intera ...201830012125
water contaminants associated with unconventional oil and gas extraction cause immunotoxicity to amphibian tadpoles.chemicals associated with unconventional oil and gas (uog) operations have been shown to contaminate surface and ground water with a variety of endocrine disrupting compounds (edcs) inducing multiple developmental alteration in mice. however, little is known about the impacts of uog-associated contaminants on amphibian health and resistance to an emerging ranavirus infectious disease caused by viruses in the genus ranavirus, especially at the vulnerable tadpole stage. here we used tadpoles of th ...201830011011
thiodipeptides targeting the intestinal oligopeptide transporter as a general approach to improving oral drug delivery.the broad substrate capacity of the intestinal oligopeptide transporter, pept1, has made it a key target of research into drug delivery. whilst the substrate capacity of this transporter is broad, studies have largely been limited to small peptides and peptide-like drugs. here, we demonstrate for the first time that a diverse range of drugs can be targeted towards transport by pept1 using a hydrolysis resistant carrier. eleven prodrugs were synthesized by conjugating modified dipeptides containi ...201830006163
pharmacological and toxicological activity of rsd921, a novel sodium channel blocker.rsd921, the r,r enantiomer of the kappa (k) agonist pd117,302, lacks significant activity on opioid receptors.201829990839
human mutations in slc2a9 (glut9) affect transport capacity for urate.slc2a9 or glut9 is a voltage sensitive urate transporter, mainly expressed in the kidneys, the liver, and the intestine. human glut9 loss-of-function mutations were identified in familial hypouricemia, and several single nucleotide polymorphisms (snps) were associated with lower serum urate, further indicating that glut9 is a major determinant of serum uric acid level. to get insights in glut9 transport characteristics, we systematically analyzed the function of known human glut9 mutants using 1 ...201829967582
the fungal alkaloid okaramine-b activates an l-glutamate-gated chloride channel from ixodes scapularis, a tick vector of lyme disease.a novel l-glutamate-gated anion channel (iscaglucl1) has been cloned from the black-legged tick, ixodes scapularis, which transmits multiple pathogens including the agents of lyme disease and human granulocytic anaplasmosis. when mrna encoding iscaglucl1 was expressed in xenopus laevis oocytes, we detected robust 50-400 na currents in response to 100 μm l-glutamate. responses to l-glutamate were concentration-dependent (pec50 3.64 ± 0.11). ibotenate was a partial agonist on iscaglucl1. we detect ...201829957333
multiple massive domestication and recent amplification of kolobok superfamily transposons in the clawed frog xenopus.dna transposons are generally destroyed by mutations and have short lifespans in hosts, as they are neutral or harmful to the host and therefore not conserved by natural selection. the clawed frog xenopus harbors many dna transposons and certain families, such as t2-mite, have extremely long lives. these have ancient origins, but have shown recent transposition activity. in addition, certain transposase genes may have been "domesticated" by xenopus and conserved over long time periods by natural ...201829946483
adamts9, a member of the adamts family, in xenopus development.extracellular matrix (ecm) remodeling by metalloproteinases is crucial during development. the adamts (a disintegrin and metalloproteinase with thrombospondin type i motifs) enzymes are secreted, multi-domain matrix-associated zinc metalloendopeptidases that have diverse roles in tissue morphogenesis and patho-physiological remodeling. the human family includes 19 members. in this study we identified the 19 members of the adamts family in xenopus laevis and xenopus tropicalis. gene identificatio ...201829935379
influenza d virus m2 protein exhibits ion channel activity in xenopus laevis oocytes.a new type of influenza virus, known as type d, has recently been identified in cattle and pigs. influenza d virus infection in cattle is typically asymptomatic; however, its infection in swine can result in clinical disease. swine can also be infected with all other types of influenza viruses, namely a, b, and c. consequently, swine can serve as a "mixing vessel" for highly pathogenic influenza viruses, including those with zoonotic potential. currently, the only antiviral drug available target ...201829927982
probing proline residues in the prokaryotic ligand-gated ion channel, elic.erwinia ligand-gated ion channel (elic) is a bacterial homologue of vertebrate pentameric ligand-gated ion channels (plgics) and has proven to be a valuable model for understanding the structure and function of this important protein family. there is nevertheless still a question about whether molecular details can be accurately extrapolated from this protein to those found in eukaryotes. here we explore the role of proline residues (pros) in elic by creating mutant receptors, expressing them in ...201829927250
nuclear arp2/3 drives dna break clustering for homology-directed repair.dna double-strand breaks repaired by non-homologous end joining display limited dna end-processing and chromosomal mobility. by contrast, double-strand breaks undergoing homology-directed repair exhibit extensive processing and enhanced motion. the molecular basis of this movement is unknown. here, using xenopus laevis cell-free extracts and mammalian cells, we establish that nuclear actin, wasp, and the actin-nucleating arp2/3 complex are recruited to damaged chromatin undergoing homology-direc ...201829925947
gitelman's syndrome: characterization of a novel c.1181g>a point mutation and functional classification of the known mutations.we have investigated the mechanisms by which a novel missense point mutation (c.1181g>a) found in two sisters causes gitelman's syndrome by impairing the sodium chloride co-transporter (ncc, encoded by slc12a3 gene) function. the cdna and in vitro transcribed mrna of either wild-type or mutated slc12a3 were transfected into hek293 cells and injected into xenopus laevis oocytes, respectively. the expression, maturation, trafficking, and function of the mutated and wild-type ncc were assessed by w ...201829925901
regulation of nuclear factor of activated t cells (nfat) and downstream myogenic proteins during dehydration in the african clawed frog.xenopus laevis, otherwise known as the african clawed frog, undergoes natural dehydration of up to 30% of its total body water during the dry season in sub-saharan africa. to survive under these conditions, a variety of physiological and biochemical changes take place in x. laevis. we were interested in understanding the role that the calcineurin-nfat pathway plays during dehydration stress response in the skeletal muscles of x. laevis. immunoblotting was performed to characterize the protein le ...201829923155
semicircular canal influences on the developmental tuning of the translational vestibulo-ocular reflex.vestibulo-ocular reflexes (vors) rely on neuronal computations that transform vestibular sensory signals into spatio-temporally appropriate extraocular motor commands. the motoneuronal discharge for contractions of the superior oblique eye muscle during linear translation derives from a utricular epithelial sector that is spatially aligned with the pulling direction of this muscle. in xenopus laevis, the alignment is gradually achieved during larval development and requires motion-related semici ...201829922219
a wide variety of mitf transcript variants are expressed in the xenopus laevis periodic albino mutant.the periodic albino mutant of xenopus laevis has been used to study the development of pigment cells because both the retinal pigment epithelium (rpe) and melanophores are affected. in this mutant, "white pigment cells" containing both melanophore-specific and iridophore-specific pigment organelles appear. the present experiments were designed to investigate the structural organization and expression of microphthalmia-associated transcription factor (mitf) in the mutant since mitf is known to re ...201829920861
a sodium transporter hvhkt1;1 confers salt tolerance in barley via regulating tissue and cell ion homeostasis.our previous studies showed that high salt tolerance in tibetan wild barley accessions was associated with hvhkt1;1, a member of the high-affinity potassium transporter family. however, molecular mechanisms of hvhkt1;1 for salt tolerance and its roles in k+/na+ homeostasis remain to be elucidated. functional characterization of hvhkt1;1 was conducted in the present study. nacl-induced transcripts of hvhkt1;1 were significantly higher in the roots of tibetan wild barley xz16 relative to other gen ...201829917153
isolation and functional characterization of cslsi2, a cucumber silicon efflux transporter gene.silicon has been proven to exert beneficial effects on plant growth and stress tolerance, and silicon accumulation varies among different plant species. cucumber (cucumis sativus) is a widely used dicot model for silicon accumulation, but little is known about the molecular mechanism of its silicon uptake. previously, we isolated and characterized cslsi1, a silicon influx transporter gene from cucumber. in this study, we cloned a putative silicon efflux transporter gene, cslsi2, from cucumber an ...201829905780
the rna-binding complex escrt-ii in xenopus laevis eggs recognizes purine-rich sequences through its subunit, vps25.rna-binding proteins (rbp) are critical regulators of gene expression. recent studies have uncovered hundreds of mrna-binding proteins that do not contain annotated rna-binding domains and have well-established roles in other cellular processes. investigation of these nonconventional rbps is critical for revealing novel rna-binding domains and may disclose connections between rna regulation and other aspects of cell biology. the endosomal sorting complex required for transport ii (escrt-ii) is a ...201829903915
transcriptome of xenopus andrei, an octoploid frog, during embryonic development.although polyploidy occurs throughout the fish and amphibian lineages, the xenopus genus exhibits a high incidence of polyploidy, with 25 out of the 26 known species being polyploid. however, transcriptomic information is currently available for only one of these species, the tetraploid xenopus laevis. xenopus andrei, an octoploid species within the xenopus genus, offers an opportunity for assessing a novel polyploid transcriptome during vertebrate development. rna-seq data was generated at nine ...201829900348
validation and bioinformatics analysis of differentially expressed circrnas involved in developing male xenopus laevis chronically exposed to atrazine.the data presented here are related to the research article titled "identification of circular rnas and their alterations involved in developing male xenopus laevis chronically exposed to atrazine" (sai et al., 2018) [1]. circular rnas (circrnas) are implicated in multiple developmental anomalies (bachmayr-heyda et al., 2015; li et al., 2015) [2], [3]. this report describes the differentially expressed circrnas involved in developing male xenopus laevis (x. laevis) chronically exposed to atrazin ...201829900306
visualization of gene expression patterns by in situ hybridization on early stages of development of xenopus laevis.in situ hybridization performed using whole fixed embryos provides accurate and detailed visualization of gene expression patterns. these patterns are useful for investigating spatial patterns of gene expression in normally developing embryos but can also be useful in investigating the effects of genetic or environmental changes on expression of genetic markers characteristic of particular tissues, organs, or genetic pathways. our lab's protocol for whole-mount in situ hybridization is presented ...201829896701
evaluation of teratogenicity of pharmaceuticals using fetax.pharmaceuticals are chemical compounds which are used to preserve human and animal health. once administered, these compounds are metabolized or can remain unaltered until excreted. therefore, a mixture of pharmaceuticals and their metabolites enters municipal sewers and wastewater treatment plants where, depending on their polarity, water solubility, and persistence, they cannot be completely removed or transformed during the treatment process, so that unaltered pharmaceuticals and/or their met ...201829896699
role of thyroid hormone receptor in amphibian development.the amphibian xenopus laevis has long been used as a model for studying vertebrate cell and developmental biology largely due to the easiness to manipulate this system in vivo and in vitro. while most of the developmental studies have been on xenopus embryogenesis, considerable efforts have been made to understand its metamorphosis, a process mimicking postembryonic development in mammals when many organs mature into their adult forms in the presence of high levels of thyroid hormone (t3). amphi ...201829892830
evaluating thyroid disrupting chemicals in vivo using xenopus laevis.using in vivo animal model systems for chemical screening can permit evaluation of the signaling pathways implicated. xenopus laevis is an ideal model organism to test thyroid axis disruption as thyroid hormones are highly conserved across vertebrates. here, we describe a high-throughput assay using non-feeding embryonic stage transgenic x. laevis (th/bzip) to screen for thyroid disrupting chemicals using a 3 day exposure protocol. we further describe a protocol to detect endocrine disruption of ...201829892825
atrial fibrillation and heart failure-associated remodeling of two-pore-domain potassium (k2p) channels in murine disease models: focus on task-1.understanding molecular mechanisms involved in atrial tissue remodeling and arrhythmogenesis in atrial fibrillation (af) is essential for developing specific therapeutic approaches. two-pore-domain potassium (k2p) channels modulate cellular excitability, and task-1 (k2p3.1) currents were recently shown to alter atrial action potential duration in af and heart failure (hf). finding animal models of af that closely resemble pathophysiological alterations in human is a challenging task. this study ...201829881975
pou3f transcription factor expression during embryonic development highlights distinct pou3f3 and pou3f4 localization in the xenopus laevis kidney.the pou (pit-oct-unc) genes encode a large transcription factor family comprising 6 classes (pou1f to pou6f ) involved in many developmental processes, such as cell commitment and differentiation. the pou3f class contains four members (pou3f1, pou3f2, pou3f3, pou3f4) characterized by expression in ectodermal tissue derivatives, such as nervous system and otic vesicle, during mammalian development. in order to obtain insights into the potential conservation of this class of transcription factors ...201829877572
lrpap1 as a specific marker of proximal pronephric kidney tubuli in xenopus laevis embryos.lrpap1, also known as receptor associated protein (rap) is a small protein of 40 kda associated with six of the seven members of the evolutionary conserved family of ldl receptors. numerous studies showed that lrpap1 has a dual function, initially as a chaperone insuring proper formation of intermolecular disulfide bonds during biogenesis of low density lipoprotein (ldl) receptors and later as an escort protein during trafficking through the endoplasmic reticulum and the early golgi compartment, ...201829877571
genome-wide transcriptomics analysis of genes regulated by gata4, 5 and 6 during cardiomyogenesis in xenopus laevis.the transcription factors gata4, gata5 and gata6 play important roles in heart muscle differentiation. the data presented in this article are related to the research article entitled "genome-wide transcriptomics analysis identifies sox7 and sox18 as specifically regulated by gata4 in cardiomyogenesis" (afouda et al., 2017) [1]. the present study identifies genes regulated by these individual cardiogenic gata factors using genome-wide transcriptomics analysis. we have presented genes that are spe ...201829876429
mechanism of how augmin directly targets the γ-tubulin ring complex to microtubules.microtubules (mts) must be generated from precise locations to form the structural frameworks required for cell shape and function. mts are nucleated by the γ-tubulin ring complex (γ-turc), but it remains unclear how γ-turc gets to the right location. augmin has been suggested to be a γ-turc targeting factor and is required for mt nucleation from preexisting mts. to determine augmin's architecture and function, we purified xenopus laevis augmin from insect cells. we demonstrate that augmin is su ...201829875259
premotor neuron divergence reflects vocal evolution.to identify mechanisms of behavioral evolution, we investigated the hindbrain circuit that generates distinct vocal patterns in two closely related frog species. male xenopus laevis and xenopus petersii produce courtship calls that include a fast trill: trains of ∼60 hz sound pulses. although fast trill rates are similar, x. laevis fast trills have a longer duration and period than those of x. petersii to pinpoint the neural basis of these differences, we used whole-cell patch-clamp recordings i ...201829875228
molecular insights into variable electron transfer in amphibian cryptochrome.cryptochrome proteins are activated by the absorption of blue light, leading to the formation of radical pairs through electron transfer in the active site. recent experimental studies have shown that once some of the amino acid residues in the active site of xenopus laevis cryptochrome dash are mutated, radical-pair formation is still observed. in this study, we computationally investigate electron-transfer pathways in the x. laevis cryptochrome dash by extensively equilibrating a previously es ...201829874607
spiral waves and vertebrate embryonic handedness.during early embryonic development, the vertebrate main body axis is segmented from head-to-tail into somites. somites emerge sequentially from the presomitic mesoderm (psm) as a consequence of oscillatory waves of genetic activity, called somitogenesis waves. here, we discuss the implications of the dynamic patterns of early x-delta-2 expression in the prospective somites (somitomeres) of xenopus laevis. we report that right somitomeres normally emerge before left to form chiral structures (i.e ...201829872025
akt signaling displays multifaceted functions in neural crest development.akt signaling is an essential intracellular pathway controlling cell homeostasis, cell proliferation and survival, as well as cell migration and differentiation in adults. alterations impacting the akt pathway are involved in many pathological conditions in human disease. similarly, during development, multiple transmembrane molecules, such as fgf receptors, pdgf receptors or integrins, activate akt to control embryonic cell proliferation, migration, differentiation, and also cell fate decisions ...201829859890
n-terminal and central domains of apc function to regulate branch number, length and angle in developing optic axonal arbors in vivo.during formation of neuronal circuits, axons navigate long distances to reach their target locations in the brain. when axons arrive at their target tissues, in many cases, they extend collateral branches and/or terminal arbors that serve to increase the number of synaptic connections they make with target neurons. here, we investigated how adenomatous polyposis coli (apc) regulates terminal arborization of optic axons in living xenopus laevis tadpoles. the n-terminal and central domains of apc ...201829856981
in vivo mitotic spindle scaling can be modulated by changing the levels of a single protein: the microtubule polymerase xmap215.in many organisms, early embryonic development is characterized by a series of reductive cell divisions that result in rapid increases in cell number and concomitant decreases in cell size. intracellular organelles, such as the nucleus and mitotic spindle, also become progressively smaller during this developmental window, but the molecular and mechanistic underpinnings of these scaling relationships are not fully understood. for the mitotic spindle, changes in cytoplasmic volume are sufficient ...201829851557
the calcium-sensing receptor increases activity of the renal ncc through the wnk4-spak pathway.background hypercalciuria can result from activation of the basolateral calcium-sensing receptor (casr), which in the thick ascending limb of henle's loop controls ca2+ excretion and nacl reabsorption in response to extracellular ca2+ however, the function of casr in the regulation of nacl reabsorption in the distal convoluted tubule (dct) is unknown. we hypothesized that casr in this location is involved in activating the thiazide-sensitive nacl cotransporter (ncc) to prevent nacl loss.methods ...201829848507
asymmetric distribution of biomolecules of maternal origin in the xenopus laevis egg and their impact on the developmental plan.asymmetric cell division is a ubiquitous feature during the development of higher organisms. asymmetry is achieved by differential localization or activities of biological molecules such as proteins, and coding and non-coding rnas. here, we present subcellular transcriptomic and proteomic analyses along the animal-vegetal axis of xenopus laevis eggs. more than 98% of the maternal mrnas could be categorized into four localization profile groups: animal, vegetal, extremely vegetal, and a newly des ...201829844480
living xenopus oocytes, eggs, and embryos as models for cell division.xenopus laevis has long been a popular model for studies of development and, based on the use of cell-free extracts derived from its eggs, as a model for reconstitution of cell cycle regulation and other basic cellular processes. however, work over the last several years has shown that intact xenopus eggs and embryos are also powerful models for visualization and characterization of cell cycle-regulated cytoskeletal dynamics. these findings were something of a surprise, given that the relatively ...201829804672
conserved rna binding activity of a yin-yang 1 homologue in the ova of the purple sea urchin strongylocentrotus purpuratus.yin-yang 1 (yy1) is a highly conserved transcription factor possessing rna-binding activity. a putative yy1 homologue was previously identified in the developmental model organism strongylocentrotus purpuratus (the purple sea urchin) by genomic sequencing. we identified a high degree of sequence similarity with yy1 homologues of vertebrate origin which shared 100% protein sequence identity over the dna- and rna-binding zinc-finger region with high similarity in the n-terminal transcriptional act ...201829795182
a novel clcn5 pathogenic mutation supports dent disease with normal endosomal acidification.dent disease is an x-linked recessive renal tubular disorder characterized by low-molecular-weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and progressive renal failure. inactivating mutations of clcn5, the gene encoding the 2cl- /h+ exchanger clc-5, have been reported in patients with dent disease 1. in vivo studies in mice harboring an artificial mutation in the "gating glutamate" of clc-5 (c.632a > c, p.glu211ala) and mathematical modeling suggest that endosomal chlori ...201829791050
rod-specific ablation using the nitroreductase/metronidazole system to investigate regeneration in xenopus.genetically controlled cell type-specific ablation provides a reproducible method to induce regeneration that can be temporally and spatially controlled. until recently, regeneration studies in xenopus have relied on surgical methods to stimulate regeneration. these methods are labor intensive and not as reproducible as a genetically controlled approach. in this protocol we describe selective ablation of rod photoreceptors in the premetamorphic xenopus laevis retina using the nitroreductase/metr ...201829789402
septin-dependent remodeling of cortical microtubule drives cell reshaping during epithelial wound healing.wounds in embryos heal rapidly through contraction of the wound edges. despite well-recognized significance of the actomyosin purse string for wound closure, roles for other cytoskeletal components are largely unknown. here, we report that the septin cytoskeleton cooperates with actomyosin and microtubules to coordinate circumferential contraction of the wound margin and concentric elongation of wound-proximal cells in xenopus laevis embryos. microtubules reoriented radially, forming bundles alo ...201829777035
dissecting and culturing animal cap explants.the animal cap explant is a simple but adaptable tool available to developmental biologists. the use of animal cap explants in demonstrating the presence of mesoderm-inducting activity in the xenopus embryo vegetal pole is one of many elegant examples of their worth. animal caps respond to a range of growth factors (e.g., wnts, fgf, tgf-β), making them especially useful for studying signal transduction pathways and gene regulatory networks. explants are also suitable for examining cell behavior ...201829769399
larval thymectomy of xenopus laevis.in jawed vertebrates from sharks to mammals, the thymus is the primary (or central) lymphoid tissue where t cells develop and mature. the particular stromal cell types, cytokine environment, and tissue organization in the thymus are essential for v(d)j recombination, positive selection for major histocompatibility complex recognition, and negative selection against self-peptide recognition of most αβ t cells. the thymectomy operation on xenopus tadpole larva described here creates a t-cell-defic ...201829769397
methods for investigating the larval period and metamorphosis in xenopus.anuran metamorphosis resembles postembryonic development in mammals, a period around birth when many organs/tissues mature into their adult form as circulating thyroid and stress hormone levels are high. unlike uterus-enclosed mammalian embryos, tadpoles develop externally and undergo the dramatic changes of hormone-dependent development totally independent of maternal influence, making them a valuable model in which to study vertebrate postembryonic organ development and maturation. various pro ...201829769395
infrared laser-mediated gene induction at the single-cell level in the regenerating tail of xenopus laevis tadpoles.we describe a precise and reproducible gene-induction method in the amphibian, xenopus laevis tetrapod amphibians are excellent models for studying the mechanisms of three-dimensional organ regeneration because they have an exceptionally high regenerative ability. however, spatial and temporal manipulation of gene expression has been difficult in amphibians, hindering studies on the molecular mechanisms of organ regeneration. recently, however, development of a xenopus transgenic system with a h ...201829769391
cell transplantation as a method to investigate spinal cord regeneration in regenerative and nonregenerative xenopus stages.mammals are not capable of regenerating their central nervous system (cns); anamniotes, however, can regenerate in response to injury. the mechanisms that explain the different regenerative capabilities include: (i) extrinsic mechanisms that consider the cellular environment and extracellular matrix composition, (ii) intrinsic factors implicating the presence or absence of genetic programs that promote axon regeneration, and (iii) the presence or absence of neural stem and progenitors cells (nsp ...201829769390
retinoic acid-induced expression of hnf1b and fzd4 is required for pancreas development in xenopus laevis.retinoic acid (ra) is required for pancreas specification in xenopus and other vertebrates. however, the gene network that is directly induced by ra signalling in this context remains to be defined. by rna sequencing of in vitro-generated pancreatic explants, we identified the genes encoding the transcription factor hnf1β and the wnt-receptor fzd4/fzd4s as direct ra target genes. functional analyses of hnf1b and fzd4/fzd4s in programmed pancreatic explants and whole embryos revealed their requir ...201829769220
coulomb and ch-π interactions in (6-4) photolyase-dna complex dominate dna binding and repair abilities.(6-4) photolyases ((6-4)pls) are flavoenzymes that repair the carcinogenic uv-induced dna damage, pyrimidine(6-4)pyrimidone photoproducts ((6-4)pps), in a light-dependent manner. although the reaction mechanism of dna photorepair by (6-4)pls has been intensively investigated, the molecular mechanism of the lesion recognition remains obscure. we show that a well-conserved arginine residue in xenopus laevis (6-4)pl (xl64) participates in dna binding, through coulomb and ch-π interactions. fragment ...201829762762
rxr ligands modulate thyroid hormone signaling competence in young xenopus laevis tadpoles.appropriate thyroid hormone (th) signaling through thyroid hormone receptors (trs) is essential for vertebrate development. amphibian metamorphosis is initiated and sustained through the action of th on trs, which are conserved across vertebrates. trs heterodimerize with retinoid x receptors (rxrs) on thyroid hormone response elements (tres) in the genome; however, in most cell line and adult animal studies, rxr ligands do not affect expression of tr target genes. we used a quantitative, precoci ...201829762675
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