Publications

discovery of a potent and selective α3β4 nicotinic acetylcholine receptor antagonist from an α-conotoxin synthetic combinatorial library.	α-conotoxins are disulfide-rich peptide neurotoxins that selectively inhibit neuronal nicotinic acetylcholine receptors (nachrs). the α3β4 nachr subtype has been identified as a novel target for managing nicotine addiction. using a mixture-based positional-scanning synthetic combinatorial library (ps-scl) with the α4/4-conotoxin buia framework, we discovered a highly potent and selective α3β4 nachr antagonist. the initial ps-scl consisted of a total of 113 379 904 sequences that were screened fo ...	2014	24649848
musashi protein-directed translational activation of target mrnas is mediated by the poly(a) polymerase, germ line development defective-2.	the mrna-binding protein, musashi, has been shown to regulate translation of select mrnas and to control cellular identity in both stem cells and cancer cells. within the mammalian cells, musashi has traditionally been characterized as a repressor of translation. however, we have demonstrated that musashi is an activator of translation in progesterone-stimulated oocytes of the frog xenopus laevis, and recent evidence has revealed musashi's capability to function as an activator of translation in ...	2014	24644291
evidence for expression and function of angiotensin ii receptor type 1 in pulmonary epithelial cells.	there is a growing evidence that the peptide hormone angiotensin ii (angii) can act as an auto-/paracrine mediator to regulate epithelial ion transport processes. the present study focused on the impact of angii on transepithelial ion transport in pulmonary epithelia. transcripts for the angii receptor type 1 (atr1) were detected in lungs of xenopus laevis and h441 cells (human pulmonary epithelial cell line). native xenopus lung preparations were used for ussing chamber recordings and apically ...	2014	24530803
wiring the retinal circuits activated by light during early development.	light information is sorted by neuronal circuits to generate image-forming (if) (interpretation and tracking of visual objects and patterns) and non-image-forming (nif) tasks. among the nif tasks, photic entrainment of circadian rhythms, the pupillary light reflex, and sleep are all associated with physiological responses, mediated mainly by a small group of melanopsin-expressing retinal ganglion cells (mrgcs). using xenopus laevis as a model system, and analyzing the c-fos expression induced by ...	2014	24521229
degradation of m(r) 25,000 protein by cathepsin l-like protease in xenopus laevis oocytes.	a phosphorylated protein with a molecular mass of 25,000 (pp25) is involved in xenopus laevis vitellogenin b1 and partially overlaps with phosvitin and lipovitellin 2. the protease responsible for pp25 degradation was studied in vitro since this occurs during embryogenesis. initially, a protease thought to be a contaminant of the purified pp25 preparation was analyzed and an antipain-sensitive protease presumed to be involved. when commercially available proteases were examined, pp25 was not deg ...	2014	24510540
changes in oscillatory dynamics in the cell cycle of early xenopus laevis embryos.	during the early development of xenopus laevis embryos, the first mitotic cell cycle is long (∼85 min) and the subsequent 11 cycles are short (∼30 min) and clock-like. here we address the question of how the cdk1 cell cycle oscillator changes between these two modes of operation. we found that the change can be attributed to an alteration in the balance between wee1/myt1 and cdc25. the change in balance converts a circuit that acts like a positive-plus-negative feedback oscillator, with spikes o ...	2014	24523664
dissection of xenopus laevis neural crest for in vitro explant culture or in vivo transplantation.	the neural crest (nc) is a transient dorsal neural tube cell population that undergoes an epithelium-to-mesenchyme transition (emt) at the end of neurulation, migrates extensively towards various organs, and differentiates into many types of derivatives (neurons, glia, cartilage and bone, pigmented and endocrine cells). in this protocol, we describe how to dissect the premigratory cranial nc from xenopus laevis embryos, in order to study nc development in vivo and in vitro. the frog model offers ...	2014	24637938
the different effects on cranial and trunk neural crest cell behaviour following exposure to a low concentration of alcohol in vitro.	embryonic neural crest cells give rise to large regions of the face and peripheral nervous system. exposure of these cells to high alcohol concentrations leads to cell death in the craniofacial region resulting in facial defects. however, the effects of low concentrations of alcohol on neural crest cells are not clear. in this study, cranial neural crest cells from xenopus laevis were cultured in an ethanol concentration approximately equivalent to one drink. techniques were developed to study v ...	2014	24631632
glycogen-supplemented mitotic cytosol for analyzing xenopus egg microtubule organization.	undiluted cytoplasmic extract prepared from unfertilized xenopus laevis eggs by low-speed centrifugation (csf extracts) is useful for reconstitution of egg microtubule dynamics and meiosis-ii spindle organization, but it suffers limitations for biochemical analysis due to abundant particulates. here, we describe preparation and the use of fully clarified, undiluted mitotic cytosol derived from csf extract. addition of glycogen improves the ability of this cytosol to reconstitute microtubule orga ...	2014	24630120
specificity of calcium/calmodulin-dependent protein kinases in mouse egg activation.	camkiiγ, the predominant camkii isoform in mouse eggs, controls egg activation by regulating cell cycle resumption. in this study we further characterize the involvement and specificity of camkiiγ in mouse egg activation. using exogenous expression of different crnas in camk2g(-/-) eggs, we show that the other multifunctional cam kinases, camki, and camkiv, are not capable of substituting camkiiγ to initiate cell cycle resumption in response to a rise in intracellular ca (2+). exogenous expressi ...	2014	24626179
quantitative proteomics of xenopus laevis embryos: expression kinetics of nearly 4000 proteins during early development.	while there is a rich literature on transcription dynamics during the development of many organisms, protein data is limited. we used itraq isotopic labeling and mass spectrometry to generate the largest developmental proteomic dataset for any animal. expression dynamics of nearly 4,000 proteins of xenopus laevis was generated from fertilized egg to neurula embryo. expression clusters into groups. the cluster profiles accurately reflect the major events that mark changes in gene expression patte ...	2014	24626130
the cost of muscle power production: muscle oxygen consumption per unit work increases at low temperatures in xenopus laevis.	metabolic energy (atp) supply to muscle is essential to support activity and behaviour. it is expected, therefore, that there is strong selection to maximise muscle power output for a given rate of atp use. however, the viscosity and stiffness of muscle increases with a decrease in temperature, which means that more atp may be required to achieve a given work output. here, we tested the hypothesis that atp use increases at lower temperatures for a given power output in xenopus laevis. to account ...	2014	24625645
functional characterization of tissue inhibitor of metalloproteinase-1 (timp-1) n- and c-terminal domains during xenopus laevis development.	extracellular matrix (ecm) remodeling is essential for facilitating developmental processes. ecm remodeling, accomplished by matrix metalloproteinases (mmps), is regulated by endogenous tissue inhibitors of metalloproteinases (timps). while the timp n-terminal domain is involved in inhibition of mmp activity, the c-terminal domain exhibits cell-signaling activity, which is timp and cell type dependent. we have previously examined the distinct roles of the xenopus laevis timp-2 and -3 c-terminal ...	2014	24616631
cyp19a1 (aromatase) expression in the xenopus brain at different developmental stages.	cytochrome p450 aromatase (p450arom; aromatase) is a microsomal enzyme involved in the production of endogeneous sex steroids by converting testosterone into oestradiol. aromatase is the product of the cyp19a1 gene and plays a crucial role in the sexual differentiation of the brain and in the regulation of reproductive functions. in the brain of mammals and birds, expression of cyp19a1 has been demonstrated in neuronal populations of the telencephalon and diencephalon. by contrast, a wealth of e ...	2014	24612124
tail structure is formed when blastocoel roof contacts blastocoel floor in xenopus laevis.	the tail organizer has been assessed by such transplantation methods as the einsteck procedure. however, we found that simple wounding of blastocoel roof (bcr) made it possible to form secondary tails without any transplantation in xenopus laevis. we revealed that the ectopic expression of xbra was blocked by inhibiting the contact between bcr and blastocoel floor (bcf), and wounding per se seemed to be not directly related to the secondary tail formation. therefore, the secondary tail might be ...	2014	24611759
structure of aurora b-incenp in complex with barasertib reveals a potential transinhibitory mechanism.	the aurora family is a well conserved and well characterized group of serine-threonine kinases involved in the normal progression of mitosis. the deregulation of aurora kinases impairs spindle assembly, checkpoint function and cell division. to date, many small molecules that compete with atp for binding to aurora kinases have been developed and characterized. here, the first structure of the xenopus laevis aurora b-incenp complex bound to the clinically relevant small molecule barasertib was de ...	2014	24598913
a novel serotonin-secreting cell type regulates ciliary motility in the mucociliary epidermis of xenopus tadpoles.	the embryonic skin of xenopus tadpoles serves as an experimental model system for mucociliary epithelia (mce) such as the human airway epithelium. mces are characterized by the presence of mucus-secreting goblet and multiciliated cells (mccs). a third cell type, ion-secreting cells (iscs), is present in the larval skin as well. synchronized beating of mcc cilia is required for directional transport of mucus. here we describe a novel cell type in the xenopus laevis larval epidermis, characterized ...	2014	24598162
kcnt1 gain of function in 2 epilepsy phenotypes is reversed by quinidine.	mutations in kcnt1 have been implicated in autosomal dominant nocturnal frontal lobe epilepsy (adnfle) and epilepsy of infancy with migrating focal seizures (eimfs). more recently, a whole exome sequencing study of epileptic encephalopathies identified an additional de novo mutation in 1 proband with eimfs. we aim to investigate the electrophysiological and pharmacological characteristics of hkcnt1 mutations and examine developmental expression levels.	2014	24591078
the effects of pesticide exposure on ultraviolet-b radiation avoidance behavior in tadpoles.	effects of contaminants on behavior may have important consequences on wildlife populations because behaviors such as predation, predator avoidance, reproduction, and social interaction can affect population dynamics. as a common environmental stressor, ultraviolet-b (uvb) radiation causes various deleterious effects and some aquatic organisms actively avoid uvb radiation in water. however, the extent to which environmental contaminants can impair uvb avoidance has not been evaluated, which may ...	2014	24589757
a voltage dependent non-inactivating na+ channel activated during apoptosis in xenopus oocytes.	ion channels in the plasma membrane are important for the apoptotic process. different types of voltage-gated ion channels are up-regulated early in the apoptotic process and block of these channels prevents or delays apoptosis. in the present investigation we examined whether ion channels are up-regulated in oocytes from the frog xenopus laevis during apoptosis. the two-electrode voltage-clamp technique was used to record endogenous ion currents in the oocytes. during staurosporine-induced apop ...	2014	24586320
generation of recombinant antibodies to rat gabaa receptor subunits by affinity selection on synthetic peptides.	the abundance and physiological importance of gabaa receptors in the central nervous system make this neurotransmitter receptor an attractive target for localizing diagnostic and therapeutic biomolecules. gabaa receptors are expressed within the retina and mediate synaptic signaling at multiple stages of the visual process. to generate monoclonal affinity reagents that can specifically recognize gabaa receptor subunits, we screened two bacteriophage m13 libraries, which displayed human scfvs, by ...	2014	24586298
disulfide cross-linking of transport and trimerization domains of a neuronal glutamate transporter restricts the role of the substrate to the gating of the anion conductance.	excitatory amino acid transporters remove synaptically released glutamate and maintain its concentrations below neurotoxic levels. eaats also mediate a thermodynamically uncoupled substrate-gated anion conductance that may modulate cell excitability. a structure of an archeal homologue, which reflects an early intermediate on the proposed substrate translocation path, has been suggested to be similar to an anion conducting conformation. to probe this idea by functional studies, we have introduce ...	2014	24584931
engineering xenopus embryos for phenotypic drug discovery screening.	many rare human inherited diseases remain untreatable despite the fact that the disease causing genes are known and adequate mouse disease models have been developed. in vivo phenotypic drug screening relies on isolating drug candidates by their ability to produce a desired therapeutic phenotype in whole organisms. embryos of zebrafish and xenopus frogs are abundant, small and free-living. they can be easily arrayed in multi-well dishes and treated with small organic molecules. with the developm ...	2014	24576445
hplc-based activity profiling for gabaa receptor modulators in adenocarpus cincinnatus.	in a two-microelectrode voltage clamp assay with xenopus laevis oocytes, a dichloromethane extract of adenocarpus cincinnatus roots and tubers (leguminosae) enhanced the gaba-induced chloride current (igaba) through receptors of the subtype α1β2γ2s by 126.5 ± 25.1% when tested at 100 μg/ml. by means of hplc-based activity profiling, 15 flavonoid and isoflavonoid derivatives, including eight new compounds, were identified in the active fractions of the extract. isoflavone 11 and pterocarpans 2 an ...	2014	24571311
ras-dva1 small gtpase regulates telencephalon development in xenopus laevis embryos by controlling fgf8 and agr signaling at the anterior border of the neural plate.	we previously found that the small gtpase ras-dva1 is essential for the telencephalic development in xenopus laevis because ras-dva1 controls the fgf8-mediated induction of foxg1 expression, a key telencephalic regulator. in this report, we show, however, that ras-dva1 and foxg1 are expressed in different groups of cells; whereas ras-dva1 is expressed in the outer layer of the anterior neural fold, foxg1 and fgf8 are activated in the inner layer from which the telencephalon is derived. we resolv ...	2014	24570397
structure-function elucidation of a new α-conotoxin, lo1a, from conus longurionis.	α-conotoxins are peptide toxins found in the venom of marine cone snails and potent antagonists of various subtypes of nicotinic acetylcholine receptors (nachrs). nachrs are cholinergic receptors forming ligand-gated ion channels in the plasma membranes of certain neurons and the neuromuscular junction. because nachrs have an important role in regulating transmitter release, cell excitability, and neuronal integration, nachr dysfunctions have been implicated in a variety of severe pathologies su ...	2014	24567324
methods for the study of caspase activation in the xenopus laevis oocyte and egg extract.	the study of apoptosis and caspases has advanced greatly over recent decades. studies conducted in the xenopus laevis egg extract and oocyte model system have significantly contributed to these advances. twenty years ago, newmeyer and colleagues first showed that the x. laevis egg extract, when incubated at room temperature, reconstituted the key molecular events of cellular apoptosis including cytochrome c release, nuclear condensation, internucleosomal fragmentation, and caspase activation. th ...	2014	24567099
the cryocapsule: simplifying correlative light to electron microscopy.	correlating complementary multiple scale images of the same object is a straightforward means to decipher biological processes. light microscopy and electron microscopy are the most commonly used imaging techniques, yet despite their complementarity, the experimental procedures available to correlate them are technically complex. we designed and manufactured a new device adapted to many biological specimens, the cryocapsule, that simplifies the multiple sample preparation steps, which at present ...	2014	24533564
rfx7 is required for the formation of cilia in the neural tube.	regulatory factor x (rfx) transcription factors are important for development and are likely involved in the pathogenesis of serious human diseases including ciliopathies. while seven rfx genes have been identified in vertebrates and several rfx transcription factors have been reported to be regulators of ciliogenesis, the role of rfx7 in development including ciliogenesis is not known. here we show that rfx7 in xenopus laevis is expressed in the neural tube, eye, otic vesicles, and somites. kno ...	2014	24530844
cleavage of the symbiosis receptor-like kinase ectodomain promotes complex formation with nod factor receptor 5.	plants form root symbioses with fungi and bacteria to improve their nutrient supply. symbiosis receptor-like kinase (symrk) is required for phosphate-acquiring arbuscular mycorrhiza, as well as for the nitrogen-fixing root nodule symbiosis of legumes and actinorhizal plants, but its precise function was completely unclear. here we show that the extracytoplasmic region of symrk, which comprises three leucine-rich repeats (lrrs) and a malectin-like domain (mld) related to a carbohydrate-binding pr ...	2014	24508172
distinct permeation profiles of the connexin 30 and 43 hemichannels.	connexin 43 (cx43) hemichannels may form open channels in the plasma membrane when exposed to specific stimuli, e.g. reduced extracellular concentration of divalent cations, and allow passage of fluorescent molecules and presumably a range of smaller physiologically relevant molecules. however, the permeability profile of cx43 hemichannels remains unresolved. exposure of cx43-expressing xenopus laevis oocytes to divalent cation free solution induced a gadolinium-sensitive uptake of the fluoresce ...	2014	24503060
effects of tributyltin on metamorphosis and gonadal differentiation of xenopus laevis at environmentally relevant concentrations.	tributyltin (tbt), a well known endocrine disruptor, has high teratogenicity to embryos of amphibian (xenopus tropicalis). an amphibian metamorphosis assay (ama) and a complete ama (cama) were conducted for tbt. in ama, the body weight, the snout-to-vent length and the hind limb length of x. laevis tadpoles were decreased in tributyltin chloride (tbtcl; 12.5-200 ng/l) treatment groups after 7 days exposure. tbt greatly retarded the development of tadpoles, decreased the number of follicle and in ...	2014	22903176
allosteric modulation of alpha4beta2 nicotinic acetylcholine receptors by hepes.	a number of new positive allosteric modulators (pams) have been reported that enhance responses of neuronal alpha7 and alpha4beta2 nicotinic acetylcholine receptor subtypes to orthosteric ligands. pams represent promising new leads for the development of therapeutic agents for disorders involving alterations in nicotinic neurotransmission including autism, alzheimer's and parkinson's disease. during our recent studies of alpha4beta2 pams, we identified a novel effect of 4-(2-hydroxyethyl)-1-pipe ...	2014	22732654
cellular and molecular targets of benzo[a]pyrene and metal toxicity in xenopus laevis embryos and in hep g2 cells.	this paper describes the use of two in vitro systems (stage 35 xenopus laevis embryos and the human hepatoblastoma cell line, hep g2) to study effects of some environmental contaminants (benzo[a]pyrene, copper and zinc), which are representative of chemicals with different cell targets and mechanisms of action. the ability to activate benzo[a[pyrene and to metabolise it with the cytochrome p4501a isozyme were demonstrated in both in vitro systems by assessing the formation of water-soluble and p ...	2014	25470671
essential amino acid transporter lat4 (slc43a2) is required for mouse development.	amino acid (aa) uniporter lat4 (slc43a2) mediates facilitated diffusion of branched-chain aas, methionine and phenylalanine, although its physiological role and subcellular localization are not known. we report that slc43a2 knockout mice were born at expected mendelian frequency but displayed an ∼10% intrauterine growth retardation and low amniotic fluid aas, suggesting defective transplacental transport. postnatal growth was strongly reduced, with premature death occurring within 9 days such th ...	2015	25480797
sensitisation of trpv4 by par2 is independent of intracellular calcium signalling and can be mediated by the biased agonist neutrophil elastase.	proteolytic activation of protease-activated receptor 2 (par2) may represent a major mechanism of regulating the transient receptor potential vanilloid 4 (trpv4) non-selective cation channel in pathophysiological conditions associated with protease activation (e.g. during inflammation). to provide electrophysiological evidence for par2-mediated trpv4 regulation, we characterised the properties of human trpv4 heterologously expressed in xenopus laevis oocytes in the presence and absence of co-exp ...	2015	24906497
erythropoietin protects red blood cells from trail1-induced cell death during red blood cell transition in xenopus laevis.	in anuran amphibians, larval red blood cells (rbcs) are replaced by adult-type rbcs during metamorphosis. we previously showed that tumor necrosis factor-related apoptosis-inducing ligand 1 (trail1) induces apoptosis in larval-, but not adult-type rbcs in xenopus laevis. we also found that protein kinase c (pkc) activation is involved in establishing resistance to trail1-induced apoptosis in adult-type rbcs. here, we investigated whether erythropoietin (epo), which induces pkc activation in mamm ...	2015	25200139
effects of low dose endosulfan exposure on brain neurotransmitter levels in the african clawed frog xenopus laevis.	understanding the impact of pesticides in amphibians is of growing concern to assess the causes of their decline. among pesticides, endosulfan belongs to one of the potential sources of danger because of its wide use and known effects, particularly neurotoxic, on a variety of organisms. however, the effect of endosulfan was not yet evaluated on amphibians at levels encompassing simultaneously brain neurotransmitters and behavioural endpoints. in this context, tadpoles of the african clawed frog ...	2015	25192837
molecular and cellular characterization of urinary bladder-type aquaporin in xenopus laevis.	in contrast to many anuran amphibians, water is not reabsorbed from the urinary bladder in aquatic xenopus, thereby helping to prevent excessive water influx. however, little is known about the molecular mechanisms for this process. in the present study, we have identified urinary bladder-type aquaporin, aqp-x2, in xenopus laevis by cdna cloning. the predicted amino acid sequence contained six putative transmembrane domains and the two conserved asn-pro-ala motifs, characteristic of aqps. the se ...	2015	25220852
evaluation of developmental toxicity and teratogenicity of diclofenac using xenopus embryos.	diclofenac is a non-steroidal anti-inflammatory drug (nsaid) with analgesic and anti-pyretic properties. this compound is therefore used to treat pain, inflammatory disorders, and dysmenorrhea. due to its multimodal mechanism of action and ability to penetrate placenta, diclofenac is known to have undesirable side effects including teratogenicity. however, limited data exist on its teratogenicity, and a detailed investigation regarding harmful effects of this drug during embryogenesis is warrant ...	2015	24992311
aromatase, estrogen receptors and brain development in fish and amphibians.	estrogens affect brain development of vertebrates, not only by impacting activity and morphology of existing circuits, but also by modulating embryonic and adult neurogenesis. the issue is complex as estrogens can not only originate from peripheral tissues, but also be locally produced within the brain itself due to local aromatization of androgens. in this respect, teleost fishes are quite unique because aromatase is expressed exclusively in radial glial cells, which represent pluripotent cells ...	2015	25038582
aberrant connexin26 hemichannels underlying keratitis-ichthyosis-deafness syndrome are potently inhibited by mefloquine.	keratitis-ichthyosis-deafness (kid) syndrome is an ectodermal dysplasia caused by dominant mutations of connexin26 (cx26). loss of cx26 function causes nonsyndromic sensorineural deafness, without consequence in the epidermis. functional analyses have revealed that a majority of kid-causing mutations confer a novel expansion of hemichannel activity, mediated by connexin channels in a nonjunctional configuration. inappropriate cx26 hemichannel opening is hypothesized to compromise keratinocyte in ...	2015	25229253
semicircular canal-dependent developmental tuning of translational vestibulo-ocular reflexes in xenopus laevis.	gaze stabilization during head/body movements is achieved to a large extent by vestibular-evoked compensatory eye movements. these reflexes derive from semicircular canal and otolith organs and depend on the transformation of the respective sensory signals into extraocular motor commands. to elicit directionally and dynamically appropriate compensatory eye movements, extraocular motoneurons require spatiotemporally specific inputs from semicircular canals and regions of the utricular epithelium ...	2015	25266079
evolutionarily conserved role for soxc genes in neural crest specification and neuronal differentiation.	members of the sox family of transcription factors play a variety of critical developmental roles in both vertebrates and invertebrates. whereas soxbs and soxes are involved in neural and neural crest development, respectively, far less is known about members of the soxc subfamily. to address this from an evolutionary perspective, we compare expression and function of soxc genes in neural crest cells and their derivatives in lamprey (petromyzon marinus), a basal vertebrate, to frog (xenopus laev ...	2015	25286121
comparative genomic and expression analysis of the adenosine signaling pathway members in xenopus.	adenosine is an endogenous molecule that regulates many physiological processes via the activation of four specific g-protein-coupled adora receptors. extracellular adenosine may originate either from the hydrolysis of released atp by the ectonucleotidases or from cellular exit via the equilibrative nucleoside transporters (slc29a). adenosine extracellular concentration is also regulated by its successive hydrolysis into uric acid by membrane-bound enzymes or by cell influx via the concentrative ...	2015	25319637
xenbase, the xenopus model organism database; new virtualized system, data types and genomes.	xenbase (http://www.xenbase.org), the xenopus frog model organism database, integrates a wide variety of data from this biomedical model genus. two closely related species are represented: the allotetraploid xenopus laevis that is widely used for microinjection and tissue explant-based protocols, and the diploid xenopus tropicalis which is used for genetics and gene targeting. the two species are extremely similar and protocols, reagents and results from each species are often interchangeable. x ...	2015	25313157
different solvent fractions of acanthopanax senticosus harms exert antioxidant and anti-inflammatory activities and inhibit the human kv1.3 channel.	the potential antioxidant and anti-inflammatory activities of acanthopanax senticosus harms were evaluated and its effect on the human kv1.3 potassium channel was detected. the ethyl acetate fraction possessed the highest phenolic (289.19±7.43 mg tannic acid equivalents/g) and flavonoid (10.80±0.67 mg quercetin equivalents/g) contents and exhibited stronger antioxidant effects than other fractions in most of the antioxidant assays. on the other hand, the dichloromethane (ch(2)cl(2)) fraction sho ...	2015	25340513
analysis of nuclear reprogramming following nuclear transfer to xenopus oocyte.	germinal vesicle of stage v-vi xenopus laevis oocytes (at the prophase i stage of meiosis) can be used to transplant mammalian nuclei. in this type of interspecies nuclear transfer no cell division occurs and no new cell types are generated. however, the transplanted nuclei undergo extensive transcriptional reprogramming. here, it is first explained how to carry out transplantation of multiple mammalian cell nuclei to xenopus oocytes. it is then described how to perform rt-qpcr, western blot, ch ...	2015	25287339
protocadherin-9 involvement in retinal development in xenopus laevis.	biological roles of most protocadherins (pcdhs) are a largely unsolved problem. therefore, we cloned cdna for xenopus laevis protocadherin-9 and characterized its properties to elucidate the role. the deduced amino acid sequence was highly homologous to those of mammalian protocadherin-9 s. x. laevis protocadherin-9 expressed from the cdna in l cells showed basic properties similar to those of mammalian pcdhs. expression of x. laevis protocadherin-9 was first detected in stage-31 embryos and inc ...	2015	25414271
phosphatidylinositol 4,5-bisphosphate degradation inhibits the na+/bicarbonate cotransporter nbce1-b and -c variants expressed in xenopus oocytes.	we previously reported that the phospholipid phosphatidylinositol 4,5-bisphosphate (pip2 ) directly stimulates heterologously expressed electrogenic na(+)/bicarbonate cotransporter nbce1-a in an excised macropatch from the xenopus oocyte, and indirectly stimulates nbce1-b and -c in the intact oocyte primarily through inositol 1,4,5-trisphosphate/ca(2+). in the current study, we expand on a previous observation that pip2 may also directly stimulate nbce1 in the intact oocyte. in this study on ooc ...	2015	25398525
hcn2 channels: a permanent open state and conductance changes.	hyperpolarization-activated cyclic nucleotide-gated (hcn) channels in the membranes of heart and brain cells can conduct na(+) and k(+) ions and activate between -30 and -120 mv. we express the α subunit of hcn2 channels in xenopus laevis oocytes and are confronted with two unexpected problems. first, we observe a rise in membrane conductance at resting potential proportional to the amount of expression. on activation to hyperpolarizing potentials, the instantaneous conductance rises in proporti ...	2015	25391723
histone methyltransferase dot1l plays a role in postembryonic development in xenopus tropicalis.	histone methylations have been implicated to play important roles in diverse cellular processes. of particular interest is the methylation of histone h3k79, which is catalyzed by an evolutionarily conserved methyltransferase, disruptor of telomeric silencing (dot1)-like (dot1l). to investigate the role of dot1l during vertebrate development, we have generated a dot1l-specific transcription activator-like effector nuclease (talen) nuclease to knockdown endogenous dot1l in xenopus tropicalis, a di ...	2015	25366346
glycine transporters glyt1 and glyt2 are differentially modulated by glycogen synthase kinase 3β.	inhibitory glycinergic neurotransmission is terminated by the specific glycine transporters glyt1 and glyt2 which actively reuptake glycine from the synaptic cleft. glyt1 is associated with both glycinergic and glutamatergic pathways, and is the main regulator of the glycine levels in the synapses. glyt2 is the main supplier of glycine for vesicle refilling, a process that is vital to preserve the quantal glycine content in synaptic vesicles. therefore, to control glycinergic neurotransmission e ...	2015	25301276
cd44 functions in wnt signaling by regulating lrp6 localization and activation.	wnt reception at the membrane is complex and not fully understood. cd44 is a major wnt target gene in the intestine and is essential for wnt-induced tumor progression in colorectal cancer. here we show that cd44 acts as a positive regulator of the wnt receptor complex. downregulation of cd44 expression decreases, whereas cd44 overexpression increases wnt activity in a concentration-dependent manner. epistasis experiments place cd44 function at the level of the wnt receptor lrp6. mechanistically, ...	2015	25301071
flow sensing in developing xenopus laevis is disrupted by visual cues and ototoxin exposure.	we explored how lateral line cues interact with visual cues to mediate flow sensing behaviors in the nocturnal developing frog, xenopus laevis, by exposing animals to current flows under different lighting conditions and after exposure to the ototoxin gentamicin. under dark conditions, xenopus tadpoles move downstream at the onset of current flow, then turn, and orient toward the direction of the flow with high accuracy. postmetamorphic froglets also exhibit positive rheotaxis but with less accu ...	2015	25380559
mutations in the voltage-gated potassium channel gene kcnh1 cause temple-baraitser syndrome and epilepsy.	temple-baraitser syndrome (tbs) is a multisystem developmental disorder characterized by intellectual disability, epilepsy, and hypoplasia or aplasia of the nails of the thumb and great toe. here we report damaging de novo mutations in kcnh1 (encoding a protein called ether à go-go, eag1 or kv10.1), a voltage-gated potassium channel that is predominantly expressed in the central nervous system (cns), in six individuals with tbs. characterization of the mutant channels in both xenopus laevis oocy ...	2015	25420144
distinct patterns of compartmentalization and proteolytic stability of pde6c mutants linked to achromatopsia.	phosphodiesterase-6 (pde6) is an essential effector enzyme in vertebrate photoreceptor cells. mutations in rod and cone pde6 cause recessive retinitis pigmentosa and achromatopsia, respectively. the mechanisms of missense pde6 mutations underlying severe visual disorders are poorly understood. to probe these mechanisms, we expressed seven known missense mutants of cone pde6c in rods of transgenic xenopus laevis and examined their stability and compartmentalization. pde6c proteins with mutations ...	2015	25461672
system l amino acid transporter lat1 accumulates o-(2-fluoroethyl)-l-tyrosine (fet).	o-(2-fluoroethyl)-l-tyrosine (fet) labeled with fluorine-18 is an important and specific tracer for diagnostics of glioblastoma via positron emission tomography (pet). however, the mechanism of its quite specific accumulation in tumor tissue has not been understood so far. in this work we demonstrate that [(3)h]l-tyrosine is primarily transported by the system l transporter lat1 in human ln229 glioblastoma cells. fet reduced tyrosine transport, suggesting that it shares the same uptake pathway. ...	2015	25385314
ntpdase2 and the p2y1 receptor are not required for mammalian eye formation.	eye formation in vertebrates is controlled by a conserved pattern of molecular networks. homeobox transcription factors are crucially involved in the establishment and maintenance of the retina. a previous study of massé et al. (nature, 449: 1058-62, 2007) using morpholino knockdown identified the ectonucleotidase ntpdase2 and the p2y1 receptor as essential elements for eye formation in embryos of the clawed frog xenopus laevis. in order to investigate whether a similarly essential mechanism wou ...	2015	25504514
a novel method for inducing nerve growth via modulation of host resting potential: gap junction-mediated and serotonergic signaling mechanisms.	a major goal of regenerative medicine is to restore the function of damaged or missing organs through the implantation of bioengineered or donor-derived components. it is necessary to understand the signals and cues necessary for implanted structures to innervate the host, as organs devoid of neural connections provide little benefit to the patient. while developmental studies have identified neuronal pathfinding molecules required for proper patterning during embryogenesis, strategies to initia ...	2015	25449797
a method for using direct injection of plasmid dna to study cis-regulatory element activity in f0 xenopus embryos and tadpoles.	the ability to express exogenous reporter genes in intact, externally developing embryos, such as xenopus, is a powerful tool for characterizing the activity of cis-regulatory gene elements during development. although methods exist for generating transgenic xenopus lines, more simplified methods for use with f0 animals would significantly speed the characterization of these elements. we discovered that injecting 2-cell stage embryos with a plasmid bearing a ϕc31 integrase-targeted attb element ...	2015	25448690
cellular characterization of thrombocytes in xenopus laevis with specific monoclonal antibodies.	platelets are produced from megakaryocytes (mks) in the bone marrow. in contrast, most nonmammalian vertebrates have nucleated and spindle-shaped thrombocytes instead of platelets in their circulatory systems, and the presence of mks as thrombocyte progenitors has not been verified. in developing a new animal model in adult african clawed frog (xenopus laevis), we needed to distinguish nucleated thrombocytes and their progenitors from other blood cells, because the cellular morphology of activat ...	2015	25448492
changes in gastric sodium-iodide symporter (nis) activity are associated with differences in thyroid gland sensitivity to perchlorate during metamorphosis.	we investigated stage-dependent changes in sensitivity of the thyroid gland to perchlorate during development of african clawed frog tadpoles (xenopus laevis) in relation to non-thyroidal iodide transporting tissues. perchlorate-induced increases in thyroid follicle cell size and colloid depletion were blunted when exposures began at nieuwkoop-faber (nf) stage 55 compared to when exposures began at nf stages 49 or 1-10. to determine if the development of other iodide transporting tissues may con ...	2015	25448256
biological and biochemical properties of two xenopus laevis n-acetylgalactosaminyltransferases with contrasting roles in embryogenesis.	the biosynthesis of mucin-type o-linked glycans in animals is initiated by members of the large family of polypeptide n-acetylgalactosaminyltransferases (galnac-ts), which play important roles in embryogenesis, organogenesis, adult tissue homeostasis and carcinogenesis. until now, the mammalian forms of these enzymes have been the best characterized. however, two n-acetylgalactosaminyltransferases (xgalnac-t6 and xgalnac-t16) from the african clawed frog (xenopus laevis), which are most homologo ...	2015	25447273
human intestine luminal ace2 and amino acid transporter expression increased by ace-inhibitors.	sodium-dependent neutral amino acid transporter b(0)at1 (slc6a19) and imino acid (proline) transporter sit1 (slc6a20) are expressed at the luminal membrane of small intestine enterocytes and proximal tubule kidney cells where they exert key functions for amino acid (re)absorption as documented by their role in hartnup disorder and iminoglycinuria, respectively. expression of b(0)at1 was shown in rodent intestine to depend on the presence of the carboxypeptidase angiotensin-converting enzyme 2 (a ...	2015	25534429
the effect of 900 and 1800 mhz gsm-like radiofrequency irradiation and nicotine sulfate administration on the embryonic development of xenopus laevis.	the aim of this study was to investigate the effects of gsm-like radiofrequency electromagnetic radiation (rf emr) and nicotine sulfate (ns) exposure on xenopus embryonic development.the developmental effects of gsm-like rf-emr (900-1800 mhz, at a sar value of 1w/kg and ns on xenopus laevis embryos were investigated). following the application of radiofrequency radiation and/or ns administration, the embryos were closely examined in order to determine their possible teratogenic effects. xenopus ...	2015	25531835
a gene expression map of the larval xenopus laevis head reveals developmental changes underlying the evolution of new skeletal elements.	the morphology of the vertebrate head skeleton is highly plastic, with the number, size, shape, and position of its components varying dramatically between groups. while this evolutionary flexibility has been key to vertebrate success, its developmental and genetic bases are poorly understood. the larval head skeleton of the frog xenopus laevis possesses a unique combination of ancestral tetrapod features and anuran-specific novelties. we built a detailed gene expression map of the head mesenchy ...	2015	25446275
xenopus laevis fgf receptor substrate 3 (xfrs3) is important for eye development and mediates pax6 expression in lens placode through its shp2-binding sites.	members of the fibroblast growth factor (fgf) family play important roles during various developmental processes including eye development. frs (fgf receptor substrate) proteins bind to fgfr and serve as adapters for coordinated assembly of multi-protein complexes involved in ras/mapk and pi3 kinase/akt pathways. here, we identified xenopus laevis frs3 (xfrs3), a homolog of vertebrate frs3, and investigated its roles during embryogenesis. xfrs3 is expressed maternally and zygotically with specif ...	2015	25446028
transcriptional changes in african clawed frogs (xenopus laevis) exposed to 17α-ethynylestradiol during early development.	although the past two decades have witnessed a significant increase in the number of studies investigating effects of estrogenic chemicals on amphibians, to date little is known about specific molecular interactions of estrogens with the hypothalamus-pituitary-gonadal-hepatic axis in developing amphibians. here, tissue-specific functional sets of genes, derived previously from studies of fishes exposed to endocrine active chemicals, were evaluated in xenopus laevis exposed to 17α-ethynylestradio ...	2015	25427717
effect of allyl isothiocyanate on developmental toxicity in exposed xenopus laevis embryos.	the pungent natural compound allyl isothiocyanate isolated from the seeds of cruciferous (brassica) plants such as mustard is reported to exhibit numerous beneficial health-promoting antimicrobial, antifungal, anticarcinogenic, cardioprotective, and neuroprotective properties. because it is also reported to damage dna and is toxic to aquatic organisms, the objective of the present study was to determine whether it possesses teratogenic properties. the frog embryo teratogenesis assay-xenopus (fet ...	2015	28962355
brain-derived neurotrophic factor (bdnf) expression in normal and regenerating olfactory epithelium of xenopus laevis.	olfactory epithelium has the capability to continuously regenerate olfactory receptor neurons throughout life. adult neurogenesis results from proliferation and differentiation of neural stem cells, and consequently, olfactory neuroepithelium offers an excellent opportunity to study neural regeneration and the factors involved in the maintenance and regeneration of all their cell types. we analyzed the expression of bdnf in the olfactory system under normal physiological conditions as well as du ...	2015	25488259
distinct action of the α-glucosidase inhibitor miglitol on sglt3, enteroendocrine cells, and glp1 secretion.	oral ingestion of carbohydrate triggers glucagon-like peptide 1 (glp1) secretion, but the molecular mechanism remains elusive. by measuring glp1 concentrations in murine portal vein, we found that the atp-sensitive k(+) (katp) channel is not essential for glucose-induced glp1 secretion from enteroendocrine l cells, while the sodium-glucose co-transporter 1 (sglt1) is required, at least in the early phase (5 min) of secretion. by contrast, co-administration of the α-glucosidase inhibitor (α-gi) m ...	2015	25486965
nuclear size scaling during xenopus early development contributes to midblastula transition timing.	early xenopus laevis embryogenesis is a robust system for investigating mechanisms of developmental timing. after a series of rapid cell divisions with concomitant reductions in cell size, the first major developmental transition is the midblastula transition (mbt), when zygotic transcription begins and cell cycles elongate. whereas the maintenance of a constant nuclear-to-cytoplasmic (n/c) volume ratio is a conserved cellular property, it has long been recognized that the n/c volume ratio chang ...	2015	25484296
aminolevulinate synthase 2 mediates erythrocyte differentiation by regulating larval globin expression during xenopus primary hematopoiesis.	hemoglobin synthesis by erythrocytes continues throughout a vertebrate's lifetime. the mechanism of mammalian heme synthesis has been studied for many years; aminolevulinate synthase 2 (alas2), a heme synthetase, is associated with x-linked dominant protoporphyria in humans. amphibian and mammalian blood cells differ, but little is known about amphibian embryonic hemoglobin synthesis. we investigated the function of the xenopus alas2 gene (xalas2) in primitive amphibian erythrocytes and found th ...	2015	25482442
validation of the sperm chromatin dispersion (scd) test in the amphibian xenopus laevis using in situ nick translation and comet assay.	the integrity of sperm dna is becoming increasingly recognised as an important parameter of semen quality, but there are no published reports of this procedure for any amphibian. the primary aim of this study was to apply a modified sperm chromatin dispersion (scd) test (halomax) to an amphibian sperm model (african clawed frog; xenopus laevis) and to validate the assay against in situ nick translation (isnt) and the double-comet assay procedure. inactivated spermatozoa were collected from fresh ...	2015	25482041
direct nkx2-5 transcriptional repression of isl1 controls cardiomyocyte subtype identity.	during cardiogenesis, most myocytes arise from cardiac progenitors expressing the transcription factors isl1 and nkx2-5. here, we show that a direct repression of isl1 by nkx2-5 is necessary for proper development of the ventricular myocardial lineage. overexpression of nkx2-5 in mouse embryonic stem cells (escs) delayed specification of cardiac progenitors and inhibited expression of isl1 and its downstream targets in isl1(+) precursors. embryos deficient for nkx2-5 in the isl1(+) lineage faile ...	2015	25524439
evidence for multiple, distinct adar-containing complexes in xenopus laevis.	adar (adenosine deaminase acting on rna) is an rna-editing enzyme present in most metazoans that converts adenosines in double-stranded rna targets into inosines. although the rna targets of adar-mediated editing have been extensively cataloged, our understanding of the cellular function of such editing remains incomplete. we report that long, double-stranded rna added to xenopus laevis egg extract is incorporated into an adar-containing complex whose protein components resemble those of stress ...	2015	25519486
characterization of tweety gene (ttyh1-3) expression in xenopus laevis during embryonic development.	the tweety family of genes encodes large-conductance chloride channels and has been implicated in a wide array of cellular processes including cell division, cell adhesion, regulation of calcium activity, and tumorigenesis, particularly in neuronal cells. however, their expression patterns during early development remain largely unknown. here, we describe the spatial and temporal patterning of ttyh1, ttyh2, and ttyh3 in xenopus laevis during early embryonic development. ttyh1 and ttyh3 are initi ...	2015	25541457
interactive effects of ultraviolet-b radiation and pesticide exposure on dna photo-adduct accumulation and expression of dna damage and repair genes in xenopus laevis embryos.	pesticide use and ultraviolet-b (uvb) radiation have both been suggested to adversely affect amphibians; however, little is known about their interactive effects. one potential adverse interaction could involve pesticide-induced dysregulation of dna repair pathways, resulting in greater numbers of dna photo-adducts from uvb exposure. in the present study, we investigated the interactive effects of uvb radiation and two common pesticides (endosulfan and α-cypermethrin) on induction of dna photo-a ...	2015	25569846
effects on channel properties and induction of cell death induced by c-terminal truncations of pannexin1 depend on domain length.	pannexin1 (panx1) is an integral membrane protein and known to form multifunctional hexameric channels. recently, panx1 was identified to be responsible for the release of atp and utp from apoptotic cells after site-specific proteolysis by caspases 3/7. cleavage at the carboxy-terminal (ct) position aa 376-379 irreversibly opens human panx1 channels and leads to the release of the respective nucleotides resulting in recruitment of macrophages and in subsequent activation of the immunologic respo ...	2015	25567359
dissecting microtubule structures by laser ablation.	here, we describe a detailed protocol, based on laser ablation and fluorescence optical microscopy, to measure the microtubule organization in spindles, including microtubule length distribution, polarity, and plus and minus end densities. the method uses the asymmetry in microtubule depolymerization after a cut, where the newly created microtubule plus ends depolymerize all the way to the minus ends, whereas the newly created minus ends remain stable. the protocol described in this chapter is o ...	2015	25640424
expression of a novel serine/threonine kinase gene, ulk4, in neural progenitors during xenopus laevis forebrain development.	we have analyzed the expression pattern of a novel serine/threonine kinase gene ulk4 during forebrain development in xenopus laevis. to this aim, we firstly cloned a ulk4 cdna fragment from x.laevis and generated a rna probe that was used for its detection by in situ hybridization. throughout development xulk4 expression was detected along the ventricular (vz) and subventricular zones (svz) of all forebrain regions, with the exception of the vz of the striatum. in the adult, xulk4 was also mainl ...	2015	25637795
distinct patterns of endosulfatase gene expression during xenopus laevis limb development and regeneration.	the heparan sulfate 6-o-endosulfatases sulf1 and sulf2 regulate multiple cellular processes and organ development. sulfs modulate a range of heparan-sulfate-dependent extracellular pathways, including the fibroblast growth factor, bone morphogenetic protein, and wingless/wnt signaling pathways. known patterns of sulf transcript expression together with functional experiments have implicated the sulfs in chondrogenesis and muscle regeneration in mammals. here, we describe the expression patterns ...	2015	27499864
the effects of simazine, a chlorotriazine herbicide, on the expression of genes in developing male xenopus laevis.	simazine was investigated for gene expression concurrent with simazine-induced phenotype changes during development of male xenopus laevis. x. laevis tadpoles (nieuwkoop-faber stage 46) were exposed to 0.1, 1.2, 11.0 and 100.9 μg/l simazine for 100 days. the results showed that an increased mortality of x. laevis, decreased gonad weight and altered gonadosomatic index of males significantly (p<0.05) when exposed to simazine at 11.0 and 100.9 µg/l. significant degeneration in testicular tissues w ...	2015	25634327
acute toxic effects of the herbicide formulation and the active ingredient used in cycloxydim-tolerant maize cultivation on embryos and larvae of the african clawed frog, xenopus laevis.	most genetically engineered herbicide-tolerant crops are still awaiting approval in europe. there is, however, a recent trend for the cultivation of cycloxydim-tolerant maize hybrids for use in maize production. we studied the acute toxic effects of the complementary herbicide focus(®) ultra and its active ingredient cycloxydim on embryos and early-stage larvae of the african clawed frog (xenopus laevis). the results indicate that the herbicide formulation is significantly more toxic than the ac ...	2015	25634323
trpp2-dependent ca2+ signaling in dorso-lateral mesoderm is required for kidney field establishment in xenopus.	in xenopus laevis embryos, kidney field specification is dependent on retinoic acid (ra) and coincides with a dramatic increase of ca(2+) transients, but the role of ca(2+) signaling in the kidney field is unknown. here, we identify trpp2, a member of the transient receptor potential (trp) superfamily of channel proteins encoded by the pkd2 gene, as a central component of ca(2+) signaling in the kidney field. trpp2 is strongly expressed at the plasma membrane where it might regulate extracellula ...	2015	25588842
pan-african phylogeography of a model organism, the african clawed frog 'xenopus laevis'.	the african clawed frog xenopus laevis has a large native distribution over much of sub-saharan africa and is a model organism for research, a proposed disease vector, and an invasive species. despite its prominent role in research and abundance in nature, surprisingly little is known about the phylogeography and evolutionary history of this group. here, we report an analysis of molecular variation of this clade based on 17 loci (one mitochondrial, 16 nuclear) in up to 159 individuals sampled th ...	2015	25583226
kcnip1 a ca²⁺-dependent transcriptional repressor regulates the size of the neural plate in xenopus.	in amphibian embryos, our previous work has demonstrated that calcium transients occurring in the dorsal ectoderm at the onset of gastrulation are necessary and sufficient to engage the ectodermal cells into a neural fate by inducing neural specific genes. some of these genes are direct targets of calcium. here we search for a direct transcriptional mechanism by which calcium signals are acting. the only known mechanism responsible for a direct action of calcium on gene transcription involves an ...	2015	25499267
apoptosis and differentiation of xenopus tail-derived myoblasts by thyroid hormone.	the metamorphosis of anuran amphibians is induced by thyroid hormone (th). to study the molecular mechanisms underlying tail regression during metamorphosis, we established a cell line, xl-b4, from a xenopus laevis tadpole tail at a premetamorphic stage. the cells expressed myoblast markers and differentiated into myotubes in differentiation medium. xl-b4 cells expressing fluorescent proteins were transplanted into tadpole tails. at 5 days post-transplantation, fluorescence was observed in myotu ...	2015	25791374
evidence for a revised ion/substrate coupling stoichiometry of gaba transporters.	plasma membrane γ-aminobutyric acid (gaba) transporters (gats) are electrogenic transport proteins that couple the cotranslocation of na(+), cl(-), and gaba across the plasma membrane of neurons and glia. a fundamental property of the transporter that determines its ability to concentrate gaba in cells and, hence, regulate synaptic and extra-synaptic gaba concentrations, is the ion/substrate coupling stoichiometry. here, we scrutinized the currently accepted 2 na(+):1 cl(-):1 gaba stoichiometry ...	2015	25824654
transport function of rice amino acid permeases (aaps).	the transport function of four rice (oryza sativa) amino acid permeases (aaps), osaap1 (os07g04180), osaap3 (os06g36180), osaap7 (os05g34980) and osaap16 (os12g08090), was analyzed by expression in xenopus laevis oocytes and electrophysiology. osaap1, osaap7 and osaap16 functioned, similarly to arabidopsis aaps, as general amino acid permeases. osaap3 had a distinct substrate specificity compared with other rice or arabidopsis aaps. osaap3 transported the basic amino acids lysine and arginine we ...	2015	25907566
influence of hydrophobic residues on the activity of the antimicrobial peptide magainin 2 and its synergy with pgla.	magainin 2 (mag2) and pgla are two related antimicrobial peptides found in the skin of the african frog xenopus laevis with a pronounced synergistic activity, which act by permeabilizing bacterial membranes. to probe the influence of hydrophobic peptide-lipid and peptide-peptide interactions on the antimicrobial activity and on synergy, the sequence of mag2 was modified by replacing single amino acids either with a small alanine or with the stiff and bulky hydrophobic 3-(trifluoromethyl)-l-bicyc ...	2015	25898805
endogenous gradients of resting potential instructively pattern embryonic neural tissue via notch signaling and regulation of proliferation.	biophysical forces play important roles throughout embryogenesis, but the roles of spatial differences in cellular resting potentials during large-scale brain morphogenesis remain unknown. here, we implicate endogenous bioelectricity as an instructive factor during brain patterning in xenopus laevis. early frog embryos exhibit a characteristic hyperpolarization of cells lining the neural tube; disruption of this spatial gradient of the transmembrane potential (vmem) diminishes or eliminates the ...	2015	25762681
proteomics analysis of xenopus laevis gonad tissue following chronic exposure to atrazine.	atrazine is the most commonly detected pesticide contaminant in ground and surface water. previous studies have shown that atrazine is an endocrine disruptor owing to its adverse effects on the male reproductive system in several vertebrates, but very few molecular mechanisms for these effects have been revealed. in the present study, xenopus laevis were exposed to 100 ppb of atrazine for 120 d, and then the isobaric tags for relative and absolute quantitation (itraq) technique was used to detec ...	2015	25760937
efficient retina formation requires suppression of both activin and bmp signaling pathways in pluripotent cells.	retina formation requires the correct spatiotemporal patterning of key regulatory factors. while it is known that repression of several signaling pathways lead to specification of retinal fates, addition of only noggin, a known bmp antagonist, can convert pluripotent xenopus laevis animal cap cells to functional retinal cells. the aim of this study is to determine the intracellular molecular events that occur during this conversion. surprisingly, blocking bmp signaling alone failed to mimic nogg ...	2015	25750435
phospholipase c and d regulation of src, calcium release and membrane fusion during xenopus laevis development.	this review emphasizes how lipids regulate membrane fusion and the proteins involved in three developmental stages: oocyte maturation to the fertilizable egg, fertilization and during first cleavage. decades of work show that phosphatidic acid (pa) releases intracellular calcium, and recent work shows that the lipid can activate src tyrosine kinase or phospholipase c during xenopus fertilization. numerous reports are summarized to show three levels of increase in lipid second messengers inositol ...	2015	25748412
more similar than you think: frog metamorphosis as a model of human perinatal endocrinology.	hormonal control of development during the human perinatal period is critically important and complex with multiple hormones regulating fetal growth, brain development, and organ maturation in preparation for birth. genetic and environmental perturbations of such hormonal control may cause irreversible morphological and physiological impairments and may also predispose individuals to diseases of adulthood, including diabetes and cardiovascular disease. endocrine and molecular mechanisms that reg ...	2015	25744725
xenopus laevis oocytes as a model system for studying the interaction between asbestos fibres and cell membranes.	the mode of interaction of asbestos fibres with cell membranes is still debatable. one reason is the lack of a suitable and convenient cellular model to investigate the causes of asbestos toxicity. we studied the interaction of asbestos fibres with xenopus laevis oocytes, using electrophysiological and morphological methods. oocytes are large single cells, with a limited ability to endocytose molecular ligands; we therefore considered these cells to be a good model for investigating the nature o ...	2015	25745069
ensemble-based virtual screening for cannabinoid-like potentiators of the human glycine receptor α1 for the treatment of pain.	the human glycine receptors (hglyrs) are chloride-selective ion channels that mediate inhibitory neurotransmission in the brain stem and spinal cord. they are also targets for compounds of potential use in analgesic therapies. here, we develop a strategy to discover analgesic drugs via structure-based virtual screening based on the recently published nmr structure of the hglyr-α1 transmembrane domain (pdb id: 2m6i ) and the critical role of residue s296 in hglyr-α1 potentiation by δ(9)-tetrahydr ...	2015	25790278
hdac1 regulates the proliferation of radial glial cells in the developing xenopus tectum.	in the developing central nervous system (cns), progenitor cells differentiate into progeny to form functional neural circuits. radial glial cells (rgs) are a transient progenitor cell type that is present during neurogenesis. it is thought that a combination of neural trophic factors, neurotransmitters and electrical activity regulates the proliferation and differentiation of rgs. however, it is less clear how epigenetic modulation changes rg proliferation. we sought to explore the effect of hi ...	2015	25789466