Publications

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the interplay between voluntary food intake, dietary carbohydrate-lipid ratio and nutrient metabolism in an amphibian, (xenopus laevis).digestion of food and metabolism of frogs are little studied at the moment, and such processes could be very particular in the case of amphibians, given their ectothermic and carnivorous nature which may lead them to use nutrients through specific biochemical pathways. in the present study, 24 adult xenopus laevis (six replicates with two frogs per treatment) were randomly assigned to two diets with different carbohydrate:fat ratio (4.5:1 and 2.1:1), changing the dietary glucogenic and lipogenic ...201830532132
control of xenopus tadpole locomotion via selective expression of ih in excitatory interneurons.locomotion relies on the coordinated activity of rhythmic neurons in the hindbrain and spinal cord and depends critically on the intrinsic properties of excitatory interneurons. therefore, understanding how ion channels sculpt the properties of these interneurons, and the consequences for circuit function and behavior, is an important task. the hyperpolarization-activated cation current, ih, is known to play important roles in shaping neuronal properties and for rhythm generation in many neurona ...201830503615
genomic takeover by transposable elements in the strawberry poison frog.we sequenced the genome of the strawberry poison frog, oophaga pumilio, at a depth of 127.5× using variable insert size libraries. the total genome size is estimated to be 6.76 gb, of which 4.76 gb are from high copy number repetitive elements with low differentiation across copies. these repeats encompass dna transposons, rna transposons, and ltr retrotransposons, including at least 0.4 and 1.0 gb of mariner/tc1 and gypsy elements, respectively. expression data indicate high levels of gypsy and ...201830517748
effects of quinine, quinidine and chloroquine on human muscle nicotinic acetylcholine receptors.the genus cinchona is known for a range of alkaloids, such as quinine, quinidine, cinchonine, and cinchonidine. cinchona bark has been used as an antimalarial agent for more than 400 years. quinine was first isolated in 1820 and is still acknowledged in the therapy of chloroquine-resistant falciparum malaria; in lower dosage quinine has been used as treatment for leg cramps since the 1940s. here we report the effects of the quinoline derivatives quinine, quinidine, and chloroquine on human adult ...201830515099
auditory perception exhibits sexual dimorphism and left telencephalic dominance in xenopus laevis.sex differences in both vocalization and auditory processing have been commonly found in vocal animals, although the underlying neural mechanisms associated with sexual dimorphism of auditory processing are not well understood. in this study we investigated whether auditory perception exhibits sexual dimorphism in xenopus laevis to do this we measured event-related potentials (erps) evoked by white noise (wn) and conspecific calls in the telencephalon, diencephalon and mesencephalon respectively ...201830509903
the effect of an environmentally relevant phthalate mixture on primordial germ cells of xenopus laevis embryos. 201832550375
thyroid hormone levels and temperature during development alter thermal tolerance and energetics of xenopus laevis larvae.environmental variation induced by natural and anthropogenic processes including climate change may threaten species by causing environmental stress. anuran larvae experiencing environmental stress may display altered thyroid hormone (th) status with potential implications for physiological traits. therefore, any capacity to adapt to environmental changes through plastic responses provides a key to determining species vulnerability to environmental variation. we investigated whether developmenta ...201830464840
cellspecks: a software for automated detection and analysis of calcium channels in live cells.to couple the fidelity of patch-clamp recording with a more high-throughput screening capability, we pioneered a, to our knowledge, novel approach to single-channel recording that we named "optical patch clamp." by using highly sensitive fluorescent ca2+ indicator dyes in conjunction with total internal fluorescence microscopy techniques, we monitor ca2+ flux through individual ca2+-permeable channels. this approach provides information about channel gating analogous to patch-clamp recording at ...201830447989
automating event-detection of brain neuron synaptic activity and action potential firing in vivo using a random-access multiphoton laser scanning microscope for real-time analysis.determining how a neuron computes requires an understanding of the complex spatiotemporal relationship between its input (e.g. synaptic input as a result of external stimuli) and action potential output. recent advances in in vivo, laser-scanning multiphoton technology, known as random-access microscopy (ram), can capture this relationship by imaging fluorescent light, emitted from calcium-sensitive biosensors responding to synaptic and action potential firing in a neuron's full dendritic arbor ...201830440280
expression of hyaluronan synthases upregulated by thyroid hormone is involved in intestinal stem cell development during xenopus laevis metamorphosis.during amphibian intestinal remodeling, thyroid hormone (th) induces adult stem cells, which newly generate the absorptive epithelium analogous to the mammalian one. we have previously shown that hyaluronan (ha) is newly synthesized and plays an essential role in the development of the stem cells via its major receptor cd44 in the xenopus laevis intestine. we here focused on ha synthase (has) and examined how the expression of has family genes is regulated during natural and th-induced metamorph ...201830430240
novel findings on the impact of chytridiomycosis on the cardiac function of anurans: sensitive vs. tolerant species.understanding of the physiological effects of chytridiomycosis is crucial to worldwide amphibian conservation. therefore, we analyzed the cardiac function of two anuran species (xenopus laevis and physalaemus albonotatus) with different susceptibilities to infection by the causative agent of chytridiomycosis, batrachochytrium dendrobatidis (hereafter bd).201830425891
a taxonomically and geographically constrained information base limits non-native reptile and amphibian risk assessment: a systematic review.for many taxa, new records of non-native introductions globally occur at a near exponential rate. we undertook a systematic review of peer-reviewed publications on non-native herpetofauna, to assess the information base available for assessing risks of future invasions, resulting in 836 relevant papers. the taxonomic and geographic scope of the literature was also compared to a published database of all known invasions globally. we found 1,116 species of herpetofauna, 95% of which were present i ...201830425887
development of an acute method to deliver transgenes into the brains of adult xenopus laevis.the central vocal pathway of the african clawed frog, xenopus laevis, is a powerful vertebrate model to understand mechanisms underlying central pattern generation. however, fast and efficient methods of introducing exogenous genes into the neurons of adult x. laevis are currently not available. here, we systematically tested methods of transgene delivery into adult x. laevis neurons. although successfully used for tadpole neurons for over a decade, electroporation was not efficient in transfect ...201830416430
trypanosoma brucei aquaglyceroporins mediate the transport of metabolic end-products: methylglyoxal, d-lactate, l-lactate and acetate.bloodstream forms of trypanosoma (t.) brucei, the causative agent of african sleeping sickness, possess a highly active glycolysis, which generates as main end-products: pyruvate under aerobic conditions, and pyruvate and glycerol under anaerobic conditions. to secrete them into the extracellular milieu, the parasites have at least two main specific membrane proteins, the pyruvate transporter and the aquaglyceroporins however, there are several other minor products from the glycolysis that must ...201830409521
brief local application of progesterone via a wearable bioreactor induces long-term regenerative response in adult xenopus hindlimb.the induction of limb repair in adult vertebrates is a pressing, unsolved problem. here, we characterize the effects of an integrated device that delivers drugs to severed hindlimbs of adult xenopus laevis, which normally regenerate cartilaginous spikes after amputation. a wearable bioreactor containing a silk protein-based hydrogel that delivered progesterone to the wound site immediately after hindlimb amputation for only 24 hr induced the regeneration of paddle-like structures in adult frogs. ...201830404012
atlht1 transporter can facilitate the uptake and translocation of a glycinergic-chlorantraniliprole conjugate in arabidopsis thaliana.understanding of the transporters involved in the uptake and translocation of agrochemicals in plants could provide an opportunity to guide pesticide to the site of insect feeding. the product of arabidopsis thaliana gene atlht1 makes a major contribution to the uptake into the roots of free amino acids and some of their derivatives. here, a chlorantraniliprole-glycine conjugate (cap-gly-1) was tested for its affinity to atlht1 both in planta and in vitro. seedlings deficient in atlht1 exhibited ...201830403859
transcriptome analysis of xenopus orofacial tissues deficient in retinoic acid receptor function.development of the face and mouth is orchestrated by a large number of transcription factors, signaling pathways and epigenetic regulators. while we know many of these regulators, our understanding of how they interact with each other and implement changes in gene expression during orofacial development is still in its infancy. therefore, this study focuses on uncovering potential cooperation between transcriptional regulators and one important signaling pathway, retinoic acid, during developmen ...201830390632
flow cytometric analysis of xenopus laevis and x. tropicalis blood cells using acridine orange.automated blood cell counters can distinguish cells based on their size and the presence or absence of a nucleus. however, most vertebrates have nucleated blood cells that cannot be counted automatically. we established an alternative automatic method for counting peripheral blood cells by staining cells with the fluorescent dye acridine orange (ao) and analysing cell populations using flow cytometry (fcm). as promising new animal models, we chose xenopus laevis and three inbred strains of x. tr ...201830390005
size-dependent functional response of xenopus laevis feeding on mosquito larvae.predators can play an important role in regulating prey abundance and diversity, determining food web structure and function, and contributing to important ecosystem services, including the regulation of agricultural pests and disease vectors. thus, the ability to predict predator impact on prey is an important goal in ecology. often, predators of the same species are assumed to be functionally equivalent, despite considerable individual variation in predator traits known to be important for sha ...201830386704
calcineurin promotes apc/c activation at meiotic exit by acting on both xerp1 and cdc20.vertebrate oocytes await fertilization arrested at metaphase of the second meiotic division. fertilization triggers a transient calcium wave, which induces the activation of the anaphase-promoting complex/cyclosome (apc/c) and its co-activator cdc20 resulting in the destruction of cyclin b and hence meiotic exit. two calcium-dependent enzymes are implicated in fertilization-induced apc/ccdc20 activation: calcium-/calmodulin-dependent kinase type ii (camkii) and calcineurin (can). while the role ...201830373936
assessment of the complex refractive indices of xenopus laevis sciatic nerve for the optimization of optical (nir) neurostimulation.despite an increasing interest in the use of light for neural stimulation, there is little information on how it interacts with neural tissue. the choice of wavelength in most of the optical stimulation literature is based on already available light sources designed for other applications. this paper is the first one to report the complex refractive index of the sciatic nerve of xenopus laevis, which is a crucial parameter for identifying the optimal wavelength of optical stimuli. the xenopus la ...201830371379
the receptor-like pseudokinase ghr1 is required for stomatal closure.guard cells control the aperture of stomatal pores to balance photosynthetic carbon dioxide uptake with evaporative water loss. stomatal closure is triggered by several stimuli that initiate complex signaling networks to govern the activity of ion channels. activation of slow anion channel1 (slac1) is central to the process of stomatal closure and requires the leucine-rich repeat receptor-like kinase (lrr-rlk) guard cell hydrogen peroxide-resistant1 (ghr1), among other signaling components. here ...201830361234
divergent subgenome evolution after allopolyploidization in african clawed frogs (xenopus).whole genome duplication (wgd), the doubling of the nuclear dna of a species, contributes to biological innovation by creating genetic redundancy. one mode of wgd is allopolyploidization, wherein each genome from two ancestral species becomes a 'subgenome' of a polyploid descendant species. the evolutionary trajectory of a duplicated gene that arises from wgd is influenced both by natural selection that may favour redundant, new or partitioned functions, and by gene silencing (pseudogenization). ...201830341989
synthetic light-activated ion channels for optogenetic activation and inhibition.optogenetic manipulation of cells or living organisms became widely used in neuroscience following the introduction of the light-gated ion channel channelrhodopsin-2 (chr2). chr2 is a non-selective cation channel, ideally suited to depolarize and evoke action potentials in neurons. however, its calcium (ca2+) permeability and single channel conductance are low and for some applications longer-lasting increases in intracellular ca2+ might be desirable. moreover, there is need for an efficient lig ...201830333716
multiple combinations of rdl subunits diversify the repertoire of gaba receptors in the honey bee parasite varroa destructor.in insects, γ-aminobutyric acid (gaba) is the major inhibitory neurotransmitter, and gaba-gated ion channels are the target of different classes of insecticides, including fipronil. we report here the cloning of six subunits (four rdl, one lcch3, and one grd) that constitute the repertoire of the gaba-gated ion channel family of the varroa mite (varroa destructor), a honey bee ectoparasite. we also isolated a truncated grd subunit with a premature stop codon. we found that when expressed in xeno ...201830333227
emerin induces nuclear breakage in xenopus extract and early embryos.emerin is an inner nuclear membrane protein often mutated in emery-dreifuss muscular dystrophy. because emerin has diverse roles in nuclear mechanics, cytoskeletal organization, and gene expression, it has been difficult to elucidate its contribution to nuclear structure and disease pathology. in this study, we investigated emerin's impact on nuclei assembled in xenopus laevis egg extract, a simplified biochemical system that lacks potentially confounding cellular factors and activities. notably ...201830332321
early redox activities modulate xenopus tail regeneration.redox state sustained by reactive oxygen species (ros) is crucial for regeneration; however, the interplay between oxygen (o2), ros and hypoxia-inducible factors (hif) remains elusive. here we observe, using an optic-based probe (optrode), an elevated and steady o2 influx immediately upon amputation. the spatiotemporal o2 influx profile correlates with the regeneration of xenopus laevis tadpole tails. inhibition of ros production but not ros scavenging decreases o2 influx. inhibition of hif-1α i ...201830327466
expression of trpv channels during xenopus laevis embryogenesis.transient receptor potential (trp) cation channel genes code for an extensive family of conserved proteins responsible for a variety of physiological processes, including sensory perception, ion homeostasis, and chemical signal transduction. the trp superfamily consists of seven subgroups, one of which is the transient receptor potential vanilloid (trpv) channel family. while trpv channels are relatively well studied in adult vertebrate organisms given their role in functions such as nociception ...201830326274
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
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
high-throughput screening to identify anesthetic ligands using xenopus laevis tadpoles.general anesthetics are considered among the most significant advances in modern medicine; however, they are also some of the most dangerous commonly administered drugs. despite this, the discovery of novel anesthetics has been slow, with few clinically used agents regardless of their nearly 200-year history. xenopus laevis frogs have a long history as a model organism and provide a vital bridge between in vitro and preclinical mammalian assays. the provided protocols are efficient and cost-effe ...201829588028
mitochondrial ros cause motor deficits induced by synaptic inactivity: implications for synapse pruning.developmental synapse pruning refines burgeoning connectomes. the basic mechanisms of mitochondrial reactive oxygen species (ros) production suggest they select inactive synapses for pruning: whether they do so is unknown. to begin to unravel whether mitochondrial ros regulate pruning, we made the local consequences of neuromuscular junction (nmj) pruning detectable as motor deficits by using disparate exogenous and endogenous models to induce synaptic inactivity en masse in developing xenopus l ...201829587245
unexplained cardiac arrest: a tale of conflicting interpretations of kcnq1 genetic test results.unexplained cardiac arrest (uca) is often the first manifestation of an inherited arrhythmogenic disease. genetic testing in uca is challenging due to the complexities of variant interpretation in the absence of supporting cardiac phenotype. we aimed to investigate if a kcnq1 variant [p.(pro64_pro70del)], previously reported as pathogenic, contributes to the long-qt syndrome phenotype, co-segregates with disease or affects kcnq1 function in vitro.201829582136
orthogonality of pyrrolysine trna in the xenopus oocyte.chemical aminoacylation of orthogonal trna allows for the genetic encoding of a wide range of synthetic amino acids without the need to evolve specific aminoacyl-trna synthetases. this method, when paired with protein expression in the xenopus laevis oocyte expression system, can extract atomic scale functional data from a protein structure to advance the study of membrane proteins. the utility of the method depends on the orthogonality of the trna species used to deliver the amino acid. here, w ...201829581437
delay models for the early embryonic cell cycle oscillator.time delays are known to play a crucial role in generating biological oscillations. the early embryonic cell cycle in the frog xenopus laevis is one such example. although various mathematical models of this oscillating system exist, it is not clear how to best model the required time delay. here, we study a simple cell cycle model that produces oscillations due to the presence of an ultrasensitive, time-delayed negative feedback loop. we implement the time delay in three qualitatively different ...201829579091
proteomic characterization of the neural ectoderm fated cell clones in the xenopus laevis embryo by high-resolution mass spectrometry.the molecular program by which embryonic ectoderm is induced to form neural tissue is essential to understanding normal and impaired development of the central nervous system. xenopus has been a powerful vertebrate model in which to elucidate this process. however, abundant vitellogenin (yolk) proteins in cells of the early xenopus embryo interfere with protein detection by high-resolution mass spectrometry (hrms), the technology of choice for identifying these gene products. here, we systematic ...201829578674
the right thalamus may play an important role in anesthesia-awakening regulation in frogs.previous studies have shown that the mammalian thalamus is a key structure for anesthesia-induced unconsciousness and anesthesia-awakening regulation. however, both the dynamic characteristics and probable lateralization of thalamic functioning during anesthesia-awakening regulation are not fully understood, and little is known of the evolutionary basis of the role of the thalamus in anesthesia-awakening regulation.201829576980
incorporation of the δ-subunit into the epithelial sodium channel (enac) generates protease-resistant enacs in xenopus laevis.the epithelial sodium channel (enac) is a critical regulator of vertebrate electrolyte homeostasis. enac is the only constitutively open ion channel in the degenerin/enac protein family, and its expression, membrane abundance, and open probability therefore are tightly controlled. the canonical enac is composed of three subunits (α, β, and γ), but a fourth δ-subunit may replace α and form atypical δβγ-enacs. using xenopus laevis as a model, here we found that mrnas of the α- and δ-subunits are d ...201829576549
effects of trimethoprim-sulfadiazine and detomidine on the function of equine kv 11.1 channels in a two-electrode voltage-clamp (tevc) oocyte model.the long qt syndrome (lqts) is a channelopathy that can lead to severe arrhythmia and sudden cardiac death. pharmacologically induced lqts is caused by interaction between drugs and potassium channels, especially the kv 11.1 channel. due to such interactions, numerous drugs have been withdrawn from the market or are administered with precautions in human medicine. however, some compounds, such as trimethoprim-sulfonamide combinations are still widely used in veterinarian medicine. therefore, we ...201829566261
ribosomal rna biogenesis and its response to chilling stress in oryza sativa.ribosome biogenesis is crucial for plant growth and environmental acclimation. processing of ribosomal rnas (rrnas) is an essential step in ribosome biogenesis and begins with transcription of the rdna. the resulting precursor-rrna (pre-rrna) transcript undergoes systematic processing, where multiple endonucleolytic and exonucleolytic cleavages remove the external and internal transcribed spacers (ets and its). the processing sites and pathways for pre-rrna processing have been deciphered in sac ...201829555785
comparison of etomidate, benzocaine, and ms222 anesthesia with and without subsequent flunixin meglumine analgesia in african clawed frogs (xenopus laevis).often few alternative anesthetics for exotic species are available, due to the small numbers of these animals used in research. in this study, we evaluated the depth and duration of anesthesia in xenopus laevis after their immersion in 3 doses of etomidate (15, 22.5, and 30 mg/l) and in 3 doses of benzocaine (0.1%, 0.5%, and 1%) compared with the 'gold standard,' tricaine methanesulfonate (ms222; 2 g/l). we then chose an optimal dose for each alternative anesthetic according to induction time, d ...201829555009
differential patterns of inhibition of the sugar transporters glut2, glut5 and glut7 by flavonoids.only limited data are available on the inhibition of the sugar transporter glut5 by flavonoids or other classes of bioactives. intestinal glut7 is poorly characterised and no information exists concerning its inhibition. we aimed to study the expression of glut7 in caco-2/tc7 intestinal cells, and evaluate inhibition of glucose transport by glut2 and glut7, and of fructose transport by glut2, glut5 and glut7, by flavonoids. differentiated caco-2/tc7 cell monolayers were used to investigate glut7 ...201829548810
satb1 downregulation induced by oxidative stress participates in trophoblast invasion by regulating β-catenin.preeclampsia (pe) is characterized by abnormal placentation in the early stages of pregnancy. adequate migration and invasion of trophoblasts into the uterine wall and spiral arteries to form a functional maternal-fetal interface are pivotal for normal placentation, but the exact mechanism remains unclear. growing evidence has revealed that special at-rich sequence binding protein 1 (binds to nuclear matrix/scaffold-associating dna) (satb1) is a tumor promoter that participates in cancer cell mi ...201829546272
effects of transportation, transport medium and re-housing on xenopus laevis (daudin).understanding the immediate and longer-term effects of transportation and re-housing in a laboratory species is crucial in order to refine the transfer process, enable the optimal introduction of new animals to a novel environment and to provide a sufficient acclimatisation period before usage. whilst consideration of animal welfare in most model vertebrate species has received attention, little quantitative evidence exists for the optimal care of the common laboratory amphibian xenopus laevis. ...201829545087
large, long range tensile forces drive convergence during xenopus blastopore closure and body axis elongation.indirect evidence suggests that blastopore closure during gastrulation of anamniotes, including amphibians such as xenopus laevis, depends on circumblastoporal convergence forces generated by the marginal zone (mz), but direct evidence is lacking. we show that explanted mzs generate tensile convergence forces up to 1.5 μn during gastrulation and over 4 μn thereafter. these forces are generated by convergent thickening (ct) until the midgastrula and increasingly by convergent extension (ce) there ...201829533180
lithobates catesbeianus (american bullfrog) oocytes: a novel heterologous expression system for aquaporins.xenopus laevis oocytes are a valuable tool for investigating the function of membrane proteins. however, regulations around the world, specifically in brazil, render the import of xenopus laevis frogs impractical, and, in some cases, impossible. here, as an alternative, we evaluate the usefulness of the north american aquatic bullfrog lithobates catesebeianus, which is commercially available in brazil, for the heterologous expression of aquaporin (aqp) proteins. we have developed a method that c ...201829530931
pitx1 regulates cement gland development in xenopus laevis through activation of transcriptional targets and inhibition of bmp signaling.the cement gland in xenopus laevis has long been used as a model to study the interplay of cell signaling and transcription factors during embryogenesis. it has been shown that an intermediate level of bone morphogenetic protein (bmp) signaling is essential for cement gland formation. in addition, several transcription factors have been linked to cement gland development. one of these, the homeodomain-containing protein pitx1, can generate ectopic cement gland formation; however, the mechanisms ...201829530451
frog's dcs have it all in one.although the amphibian xenopus laevis produces antibodies as diversified as those from mammals in the primary repertoire, antibody affinity maturation after immunization is relatively poor and has been associated with a poor b cell selection of aid-mediated hypermutations and lack of germinal centers in the spleen, the only secondary lymphoid organ of this amphibian. in this issue of the european journal of immunology, neely et al., [eur. j. immunol. 2018. 48: 430-440] have unveiled the role of ...201829522243
transcriptome analysis identifies genes involved in sex determination and development of xenopus laevis gonads.development of the gonads is a complex process, which starts with a period of undifferentiated, bipotential gonads. during this period the expression of sex-determining genes is initiated. sex determination is a process triggering differentiation of the gonads into the testis or ovary. sex determination period is followed by sexual differentiation, i.e. appearance of the first testis- and ovary-specific features. in xenopus laevis w-linked dm-domain gene (dm-w) had been described as a master det ...201829518581
c8orf46 homolog encodes a novel protein vexin that is required for neurogenesis in xenopus laevis.neural basic helix-loop helix (bhlh) transcription factors promote progenitor cell differentiation by activation of downstream target genes that coordinate neuronal differentiation. here we characterize a neural bhlh target gene in xenopus laevis, vexin (vxn; previously sbt1), that is homologous to human c8orf46 and is conserved across vertebrate species. c8orf46 has been implicated in cancer progression, but its function is unknown. vxn is transiently expressed in differentiating progenitors in ...201829518376
investigation of higher-order rna g-quadruplex structures in vitro and in living cells by 19f nmr spectroscopy.growing evidence indicates that rna g-quadruplexes have important roles in various processes such as transcription, translation, regulation of telomere length, and formation of telomeric heterochromatin. investigation of rna g-quadruplex structures associated with biological events is therefore essential to understanding the functions of these rna molecules. we recently demonstrated that the sensitivity and simplicity of 19f nmr can be used to directly observe higher-order telomeric g-quadruplex ...201829517770
occurrence of batrachochytrium dendrobatidis in anurans of the mediterranean region of baja california, méxico.chytridiomycosis is caused by the fungal pathogen batrachochytrium dendrobatidis (bd) and is regarded as one of the most significant threats to global amphibian populations. in méxico, bd was first reported in 2003 and has now been documented in 13 states. we visited 33 localities and swabbed 199 wild-caught anurans from 7 species (5 native, 2 exotic) across the mediterranean region of the state of baja california. using quantitative pcr, bd was detected in 94 individuals (47.2% of samples) at 2 ...201829516858
evaluation of the toxic effects of celecoxib on xenopus embryo development.celecoxib is a non-steroidal anti-inflammatory drug that selectively inhibits cyclooxygenase-2 and is prescribed for severe pain and inflammation. the excellent therapeutic effects of celecoxib mean that it is frequently used clinically, including for women of child-bearing age. however, the prenatal effects of this compound have not been studied extensively in vertebrates. the present study examined the developmental toxicity of celecoxib using a frog embryo teratogenic assay-xenopus (fetax). i ...201829505793
booting up the organism during development: pre-behavioral functions of the vertebrate brain in guiding body morphogenesis.a recent study in xenopus laevis embryos showed that the very early brain has important functions long before behavior. while the nascent brain is being constructed, it is required for normal patterning of the muscle and peripheral nerve networks, including those far away from the head. in addition to providing important developmental signals to remote tissues in normal embryogenesis, its presence is also able to render harmless exposure to specific chemicals that normally act as teratogens. the ...201829497473
whole-mount in situ hybridization of xenopus oocytes.whole-mount in situ hybridization (wmish) is a common approach that is used to visualize spatial and temporal gene expression in embryos. in this process, digoxygenin-labeled antisense rna is hybridized to the complementary transcript of interest and rna hybrids are immunohistochemically detected using an alkaline phosphatase-conjugated antibody against digoxigenin. during xenopus laevis oogenesis, certain rnas localize to the animal or vegetal pole laying the foundation for germ cell developmen ...201829496817
identification of circular rnas and their alterations involved in developing male xenopus laevis chronically exposed to atrazine.atrazine (az) is an environmental endocrine disrupting chemical which can affect the development of amphibians. in our past studies, we demonstrated that chronical exposure to 100 μg/l az can cause abnormalities in development and related genes expression of gonads in developing male xenopus laevis (x. laevis) tadpoles. recent studies by others have demonstrated that circular rnas (circrnas) are implicated in multiple developmental anomalies. however, whether circrnas involve in the effects in a ...201829494910
a nurd complex from xenopus laevis eggs is essential for dna replication during early embryogenesis.dna replication in the embryo of xenopus laevis changes dramatically at the mid-blastula transition (mbt), with y rna-independent random initiation switching to y rna-dependent initiation at specific origins. here, we identify xnurd, an mta2-containing assemblage of the nucleosome remodeling and histone deacetylation complex nurd, as an essential factor in pre-mbt xenopus embryos that overcomes a functional requirement for y rnas during dna replication. human nurd complexes have a different subu ...201829490265
plasma kallikrein activates the epithelial sodium channel in vitro but is not essential for volume retention in nephrotic mice.recent work has demonstrated that activation of the epithelial sodium channel (enac) by aberrantly filtered serine proteases causes sodium retention in nephrotic syndrome. the aim of this study was to elucidate a potential role of plasma kallikrein (pklk) as a candidate serine protease in this context.201829489063
hydrolytic activity of human nudt16 enzyme on dinucleotide cap analogs and short capped oligonucleotides.human nudt16 (hnudt16) is a member of the nudix family of hydrolases, comprising enzymes catabolizing various substrates including canonical (d)ntps, oxidized (d)ntps, nonnucleoside polyphosphates, and capped mrnas. decapping activity of the xenopus laevis (x29) nudt16 homolog was observed in the nucleolus, with a high specificity toward u8 snorna. subsequent studies have reported cytoplasmic localization of mammalian nudt16 with cap hydrolysis activity initiating rna turnover, similar to dcp2. ...201829483298
a novel rhodopsin phosphodiesterase from salpingoeca rosetta shows light-enhanced substrate affinity.it is since many years textbook knowledge that the concentration of the second messenger cgmp is regulated in animal rod and cone cells by type ii rhodopsins via a g-protein signaling cascade. microbial rhodopsins with enzymatic activity for regulation of cgmp concentration were only recently discovered: in 2014 light-activated guanylyl-cyclase opsins in fungi and in 2017 a novel rhodopsin phosphodiesterase (rhopde) in the protist salpingoeca rosetta (srrhopde). the light regulation of srrhopde, ...201829483295
micrornas associated with early neural crest development in xenopus laevis.the neural crest (nc) is a class of transitory stem cell-like cells unique to vertebrate embryos. nc cells arise within the dorsal neural tube where they undergo an epithelial to mesenchymal transition in order to migrate and differentiate throughout the developing embryo. the derivative cell types give rise to multiple tissues, including the craniofacial skeleton, peripheral nervous system and skin pigment cells. several well-studied gene regulatory networks underpin nc development, which when ...201829347911
robustly cycling xenopus laevis cell-free extracts in teflon chambers.a central advantage of studying xenopus laevis is the manipulability of its cell-free extracts, which perform the cell cycle in vitro. however, these extracts are known to be experimentally temperamental and will often complete at most one or two cycles. over the course of developing systems for imaging cell cycle events in extracts in real time, we unexpectedly found that when standard xenopus extracts are placed in teflon tubes, they cycle extremely robustly; in one series of experiments, over ...201829475997
centromere and kinetochore assembly in xenopus laevis egg extract.during cell division, chromosomes must be equally segregated to daughter cells. centromeres, the primary interaction site between chromosomes and microtubules, mediate faithful chromosome segregation during mitosis. functional studies of centromere proteins in cells have proven difficult, as mutation or deletion of most centromeric proteins often results in cell lethality. in this protocol, sperm chromatin or reconstituted chromatin arrays, together with xenopus laevis egg extracts, are used to ...201829475995
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
[morphomechanical factors in gastrulation process and differentiation of embryonic tissue of xenopus laevis].effect of mechanical stretch on the differentiation of axial anlages and chordin gene expressionwas studied in sandwich explants prepared from embryonic tissues of xenopus laevis at the early gastrula stagein two variants: with dissected or intact dorso-medial region. in the first case, convergent cell movementswere suppressed and properly organized axial organs (notochord and somites) were almost completely absent.however, they developed if the explants of such type were artificially stretched ...201830272924
[role of mechano-dependent cell movements in the establishment of spatial organization of axial rudiments in xenopus laevis embryos].trajectories of individual cell movements and patterns of differentiation in the axial rudiments insuprablastoporal areas (sba) in whole embryos of xenopus laevis artificially stretched in the transverse directionup to 120–200% from the initial length at the early gastrula stage were mapped. we observed the impairmentof anisotropic cell movements of longitudinal stretching and latero-medial convergence inherent forsba. axial rudiments occurred in all cases, but their location was completely impa ...201830272919
[geometry of movement of the outer surface of the embryo during xenopus gastrulation].the surface of xenopus laevis embryos was marked with carbon particles, after which the locationof mark groups was recorded by time-lapse video imaging and subsequent image analysis until their disappearancein the depth of gastric invagination. measuring the distances between individually identifiablemarks whose size is smaller than the size of a single cell makes it possible to quantitatively analyze the geometryof collective cell movement without any external coordinate system. during the dors ...201830272406
[secreted protein noggin4 participates in the formation of forebrain structures in xenopus laevis by inhibitingthe wnt/beta-catenin signaling pathway].noggin proteins are important regulators of the early development of the vertebrate neural system.previously, it has been traditionally thought that vertebrates have only one noggin gene (noggin1), whosemain function is the inhibition of bmp signaling pathway during the formation of dorsoventral polarity inembryos. then other proteins of this family were discovered, and the studies of noggin2 protein showed thatnoggin proteins also participate in the modulation of nodal/activin and wnt/beta-cate ...201830272399
xenopus: an alternative model system for identifying muco-active agents.the airway epithelium in human plays a central role as the first line of defense against environmental contaminants. most respiratory diseases such as chronic obstructive pulmonary disease (copd), asthma, and respiratory infections, disturb normal muco-ciliary functions by stimulating the hypersecretion of mucus. several muco-active agents have been used to treat hypersecretion symptoms in patients. current muco-active reagents control mucus secretion by modulating either airway inflammation, ch ...201829470529
dicer inactivation stimulates limb regeneration ability in xenopus laevis.the ontogenetic decline of regeneration capacity in the anuran amphibian xenopus makes it an excellent model for regeneration studies. however, the cause of the regeneration ability decline is not fully understood. micrornas regulate animal development and have been indicated in various regeneration situations. however, little is known about the role of micrornas during limb regeneration in xenopus. this study investigates the effect of dicer, an enzyme responsible for microrna maturation, on li ...201829453851
invasive african clawed frogs in california: a reservoir for or predator against the chytrid fungus?amphibian species are experiencing population declines due to infection by the fungal pathogen, batrachochytrium dendrobatidis (bd). the african clawed frog (xenopus laevis), an asymptomatic carrier of bd, has been implicated in the spread of this pathogen through global trade and established invasive populations on several continents. however, research has not explored the relationships of both life stages of this amphibian with bd. while the post-metamorphic individuals may act as a reservoir, ...201829444096
tissue stiffening coordinates morphogenesis by triggering collective cell migration in vivo.collective cell migration is essential for morphogenesis, tissue remodelling and cancer invasion. in vivo, groups of cells move in an orchestrated way through tissues. this movement involves mechanical as well as molecular interactions between cells and their environment. while the role of molecular signals in collective cell migration is comparatively well understood, how tissue mechanics influence collective cell migration in vivo remains unknown. here we investigated the importance of mechani ...201829443958
primordial germ cell transplantation for crispr/cas9-based leapfrogging in xenopus.the creation of mutant lines by genome editing is accelerating genetic analysis in many organisms. crispr/cas9 methods have been adapted for use in the african clawed frog, xenopus, a longstanding model organism for biomedical research. traditional breeding schemes for creating homozygous mutant lines with crispr/cas9-targeted mutagenesis have several time-consuming and laborious steps. to facilitate the creation of mutant embryos, particularly to overcome the obstacles associated with knocking ...201829443056
amphibian zic genes.studies in xenopus laevis have greatly contributed to understanding the roles that the zic family of zinc finger transcription factors play as essential drivers of early development. explant systems that are not readily available in other organisms give xenopus embryos a unique place in these studies, facilitated by the recent sequencing of the xenopus laevis genome. a number of upstream regulators of zic gene expression have been identified, such as inhibition of bmp signaling, as well as calci ...201829442320
isolation and demembranation of xenopus sperm nuclei.the inherent experimental advantages of intact amphibian eggs have been exploited for several decades to advance our understanding of fundamental developmental processes and the cell cycle. characterization of these processes at the molecular level has been greatly advanced by the use of cell-free extracts, which permit the development of biochemically tractable approaches. demembranated xenopus laevis sperm nuclei have been used with cell-free extracts to recapitulate cell cycle progression and ...201829438000
preparation of cellular extracts from xenopus eggs and embryos.cell-free cytoplasmic extracts prepared from xenopus eggs have been used extensively to recapitulate and characterize intracellular events in vitro. egg extracts can be induced to transit the cell cycle and reconstitute assembly of dynamic structures including the interphase nucleus and the mitotic spindle. in this protocol, methods are described for preparing crude cytoplasmic extracts from xenopus eggs and embryos that are arrested in metaphase of the cell cycle. the basic protocol uses unfert ...201829437998
fluorescence in situ hybridization of cryosectioned xenopus oocytes.xenopus laevis oocytes are widely used to study mechanisms of rna function and biogenesis. while the large size of xenopus oocytes is amenable to both biochemical and imaging approaches, the relative opacity of the yolk-rich cytoplasm has limited high-resolution imaging of endogenous rnas. here, we present a protocol that combines multi-probe fluorescence in situ hybridization with cryosectioning to provide a highly sensitive means of imaging endogenous oocyte rnas.201829437997
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