Publications

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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
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
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
inward- and outward-facing homology modeling of human concentrative nucleoside transporter 3 (hcnt3) predicts an elevator-type transport mechanism.the human slc28 family of concentrative (na+-dependent) nucleoside transporters has three members, hcnt1, hcnt2 and hcnt3. previously, we have used heterologous expression in xenopus laevis oocytes in combination with an engineered cysteine-less hcnt3 protein hcnt3(c-) to undertake systematic substituted cysteine accessibility method (scam) analysis of the transporter using the membrane-impermeant thiol reactive reagent p-chloromercuribenzene sulfonate (pcmbs). a continuous sequence of more than ...201830096006
apoptosis propagates through the cytoplasm as trigger waves.apoptosis is an evolutionarily conserved form of programmed cell death critical for development and tissue homeostasis in animals. the apoptotic control network includes several positive feedback loops that may allow apoptosis to spread through the cytoplasm in self-regenerating trigger waves. we tested this possibility in cell-free xenopus laevis egg extracts and observed apoptotic trigger waves with speeds of ~30 micrometers per minute. fractionation and inhibitor studies implicated multiple f ...201830093599
the age-regulated zinc finger factor znf367 is a new modulator of neuroblast proliferation during embryonic neurogenesis.global population aging is one of the major social and economic challenges of contemporary society. during aging the progressive decline in physiological functions has serious consequences for all organs including brain. the age-related incidence of neurodegenerative diseases coincides with the sharp decline of the amount and functionality of adult neural stem cells. recently, we identified a short list of brain age-regulated genes by means of next-generation sequencing. among them znf367 codes ...201830087422
gli2 is required for the induction and migration of xenopus laevis neural crest.the neural crest (nc) is a multipotent migratory embryonic population that is formed during late gastrulation and gives rise to a wide array of derivatives, including cells from the peripheral nervous system (pns), the craniofacial bones and cartilages, peripheral glial cells, and melanocyte cells, among others. in this work we analyzed the role of the hedgehog signaling pathway effector gli2 in xenopus nc. we provide evidence that the gli2 gene is expressed in the prospective, premigratory and ...201830086335
spatial and temporal analysis of pcp protein dynamics during neural tube closure.planar cell polarity (pcp) controls convergent extension and axis elongation in all vertebrates. although asymmetric localization of pcp proteins is central to their function, we understand little about pcp protein localization during convergent extension. here, we use quantitative live imaging to simultaneously monitor cell intercalation behaviors and pcp protein dynamics in the xenopus laevis neural plate epithelium. we observed asymmetric enrichment of pcp proteins, but more interestingly, we ...201830080139
tectal crfr1 receptors modulate food intake and feeding behavior in the south african clawed frog xenopus laevis.the optic tectum and superior colliculus rapidly inhibit food intake when a visual threat is present. previous work indicates that crf, acting on crfr1 receptors, may play a role in tectal inhibition of feeding behavior and food intake. here we test the hypothesis that tectal crfr1 receptors modulate food intake and feeding behavior in juvenile xenopus laevis. we performed five experiments to test the following questions: 1) does tectal crf injection decrease food intake/feeding behavior? 2) doe ...201830077740
differential modulation of human gabac-ρ1 receptor by sulfur-containing compounds structurally related to taurine.the amino acid taurine (2-aminoethanesulfonic acid) modulates inhibitory neurotransmitter receptors. this study aimed to determine if the dual action of taurine on gabac-ρ1r relates to its structure. to address this, we tested the ability of the structurally related compounds homotaurine, hypotaurine, and isethionic acid to modulate gabac-ρ1r.201830075755
a simple decision to move in response to touch reveals basic sensory memory and mechanisms for variable response times.short-term working memory and decision-making are usually studied in the cerebral cortex; in many models of simple decision making, sensory signals build slowly and noisily to threshold to initiate a motor response after long, variable delays. when touched, hatchling frog tadpoles decide whether to swim; we define the long and variable delays to swimming and use whole-cell recordings to uncover the neurons and processes responsible. firing in sensory and sensory pathway neurons is short latency, ...201830074236
disruption of amino acid homeostasis by novel asct2 inhibitors involves multiple targets.the glutamine transporter asct2 (slc1a5) is actively investigated as an oncological target, but the field lacks efficient asct2 inhibitors. a new group of asct2 inhibitors, 2-amino-4-bis(aryloxybenzyl)aminobutanoic acids (aaba), were developed recently and shown to suppress tumor growth in preclinical in vivo models. to test its specificity, we deleted asct2 in two human cancer cell lines. surprisingly, growth of parental and asct2-knockout cells was equally sensitive to aaba compounds. aaba com ...201830072900
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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