Publications

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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
evaluating the teratogenicity of ritodrine and nifedipine using a frog embryo teratogenesis assay (fetax).	the frog embryo teratogenesis assay-xenopus (fetax) was used to assess the teratogenic potential of two tocolytics. embryos of the south african clawed frog, xenopus laevis, were exposed to ritodrine or nifedipine. exposure media were changed and monitored at 24-hour intervals. the 96-hour lc50 (lethal concentration), the 96-hour ec50 (malformation), and the no observable adverse effect concentrations (noaec) and the lowest observable adverse effect concentration (loaec) for mortality, malformat ...	2015	25156158
a di-arginine er retention signal regulates trafficking of hcn1 channels from the early secretory pathway to the plasma membrane.	hyperpolarization-activated cyclic nucleotide-gated 1 (hcn1) channels carry ih, which contributes to neuronal excitability and signal transmission in the nervous system. controlling the trafficking of hcn1 is an important aspect of its regulation, yet the details of this process are poorly understood. here, we investigated how the c-terminus of hcn1 regulates trafficking by testing for its ability to redirect the localization of a non-targeted reporter in transgenic xenopus laevis photoreceptors ...	2015	25142030
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
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
a hydrophobic area of the gaba ρ₁ receptor containing phenylalanine 124 influences both receptor activation and deactivation.	experimental evidence suggests that gaba ρ1 receptors are potential therapeutic targets for the treatment of a range of neurological conditions, including anxiety and sleep disorders. homology modelling of the gaba ρ1 extracellular n-terminal domain has revealed a novel hydrophobic area that extends beyond, but not including the gaba-binding site. phenylalanine 124 (f124) is predicted to be involved in maintaining the structural integrity of the orthosteric-binding site. we have assessed the act ...	2015	24816654
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
in vivo pump-probe optical coherence tomography imaging in xenopus laevis.	currently, optical coherence tomography (oct), is not capable of obtaining molecular information often crucial for identification of disease. to enable molecular imaging with oct, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. a fourier-domain pump-probe oct (ppoct) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. methylene blue, a biological dye with well-know pho ...	2015	24282110
xepac protein and ip3/ca2+ pathway implication during xenopus laevis vitellogenesis.	the objective of this study was to elucidate the signalling pathways initiated by camp once inside the xenopus laevis oocyte, where it triggers and maintains vitellogenin endocytic uptake. our results showed the presence of xepac transcripts at all stages of oogenesis and we demonstrated that a camp analogue that exclusively activates xepac, 8-cpt, was able to rescue the endocytic activity in oocytes with uncoupled gap junctions. inhibition experiments for the ip3/ca2+ signalling pathway showed ...	2015	23890344
the structure of a contact-dependent growth-inhibition (cdi) immunity protein from neisseria meningitidis mc58.	contact-dependent growth inhibition (cdi) is an important mechanism of intercellular competition between neighboring gram-negative bacteria. cdi systems encode large surface-exposed cdia effector proteins that carry a variety of c-terminal toxin domains (cdia-cts). all cdi(+) bacteria also produce cdii immunity proteins that specifically bind to the cognate cdia-ct and neutralize its toxin activity to prevent auto-inhibition. here, the x-ray crystal structure of a cdii immunity protein from neis ...	2015	26057799
perturbation of critical prolines in gloeobacter violaceus ligand-gated ion channel (glic) supports conserved gating motions among cys-loop receptors.	gloeobacter violaceus ligand-gated ion channel (glic) has served as a valuable structural and functional model for the eukaryotic cys-loop receptor superfamily. in cys-loop and other receptors, we have previously demonstrated the crucial roles played by several conserved prolines. here we explore the role of prolines in the gating transitions of glic. as conventional substitutions at some positions resulted in nonfunctional proteins, we used in vivo non-canonical amino acid mutagenesis to determ ...	2015	26668320
evaluation of presurgical skin preparation agents in african clawed frogs (xenopus laevis).	despite the routine collection of oocytes from african clawed frogs (xenopus laevis) for use in research, few studies have evaluated methods for preparing their skin for surgery. we evaluated 3 skin preparatory agents by examining their antibacterial efficacy and the gross and microscopic appearance of xenopus skin after exposure. frogs (n = 14) were sedated and treated (contact time, 10 min) with 0.9% sterile nacl on one-half of the ventrum and with 0.5% povidone-iodine or 0.75% chlorhexidine o ...	2015	26632790
odorant receptor-based discovery of natural repellents of human lice.	the body louse, pediculus humanus humanus, is an obligate blood-feeding ectoparasite and an important insect vector that mediates the transmission of diseases to humans. the analysis of the body louse genome revealed a drastic reduction of the chemosensory gene repertoires when compared to other insects, suggesting specific olfactory adaptations to host specialization and permanent parasitic lifestyle. here, we present for the first time functional evidence for the role of odorant receptors (ors ...	2015	26494014
functional characterization of a novel class of morantel-sensitive acetylcholine receptors in nematodes.	acetylcholine receptors are pentameric ligand-gated channels involved in excitatory neuro-transmission in both vertebrates and invertebrates. in nematodes, they represent major targets for cholinergic agonist or antagonist anthelmintic drugs. despite the large diversity of acetylcholine-receptor subunit genes present in nematodes, only a few receptor subtypes have been characterized so far. interestingly, parasitic nematodes affecting human or animal health possess two closely related members of ...	2015	26625142
follicle online: an integrated database of follicle assembly, development and ovulation.	folliculogenesis is an important part of ovarian function as it provides the oocytes for female reproductive life. characterizing genes/proteins involved in folliculogenesis is fundamental for understanding the mechanisms associated with this biological function and to cure the diseases associated with folliculogenesis. a large number of genes/proteins associated with folliculogenesis have been identified from different species. however, no dedicated public resource is currently available for fo ...	2015	25931457
adaptive evolutionary paths from uv reception to sensing violet light by epistatic interactions.	ultraviolet (uv) reception is useful for such basic behaviors as mate choice, foraging, predator avoidance, communication, and navigation, whereas violet reception improves visual resolution and subtle contrast detection. uv and violet reception are mediated by the short wavelength-sensitive (sws1) pigments that absorb light maximally (λmax) at ~360 nm and ~395 to 440 nm, respectively. because of strong nonadditive (epistatic) interactions among amino acid changes in the pigments, the adaptive e ...	2015	26601250
direct recording of trans-plasma membrane electron currents mediated by a member of the cytochrome b561 family of soybean.	trans-plasma membrane electron transfer is achieved by b-type cytochromes of different families, and plays a fundamental role in diverse cellular processes involving two interacting redox couples that are physically separated by a phospholipid bilayer, such as iron uptake and redox signaling. despite their importance, no direct recordings of trans-plasma membrane electron currents have been described in plants. in this work, we provide robust electrophysiological evidence of trans-plasma membran ...	2015	26282237
aspergillus glaucus aquaglyceroporin gene glpf confers high osmosis tolerance in heterologous organisms.	aquaglyceroporins (glpfs) that transport glycerol along with water and other uncharged solutes are involved in osmoregulation in myriad species. fungal species form a large group of eukaryotic organisms, and their glpfs may be diverse, exhibiting various activities. however, few filamentous fungal glpfs have been biologically investigated. here, a glpf gene from the halophilic fungus aspergillus glaucus (agglpf) was verified to be a channel of water or glycerol in xenopus laevis oocytes and was ...	2015	26209670
proton-dependent glutamine uptake by aphid bacteriocyte amino acid transporter apglnt1.	aphids house large populations of the gammaproteobacterial symbiont buchnera aphidicola in specialized bacteriocyte cells. the combined biosynthetic capability of the holobiont (acyrthosiphon pisum and buchnera) is sufficient for biosynthesis of all twenty protein coding amino acids, including amino acids that animals alone cannot synthesize; and that are present at low concentrations in a. pisum's plant phloem sap diet. collaborative holobiont amino acid biosynthesis depends on glutamine import ...	2015	26028424
the ph sensitivity of aqp0 channels in tetraploid and diploid teleosts.	water homeostasis and the structural integrity of the vertebrate lens is partially mediated by aqp0 channels. emerging evidence indicates that external ph may be involved in channel gating. here we show that a tetraploid teleost, the atlantic salmon, retains 4 aqp0 genes (aqp0a1, -0a2, -0b1, and -0b2), which are highly, but not exclusively, expressed in the lens. functional characterization reveals that, although each paralog permeates water efficiently, the permeability is respectively shifted ...	2015	25667219
chytrid fungus infections in laboratory and introduced xenopus laevis populations: assessing the risks for u.k. native amphibians.	the chytrid fungus batrachochytrium dendrobatidis (bd) is notorious amongst current conservation biology challenges, responsible for mass mortality and extinction of amphibian species. world trade in amphibians is implicated in global dissemination. exports of south african xenopus laevis have led to establishment of this invasive species on four continents. bd naturally infects this host in africa and now occurs in several introduced populations. however, no previous studies have investigated t ...	2015	25843959
using supported bilayers to study the spatiotemporal organization of membrane-bound proteins.	cell division in prokaryotes and eukaryotes is commonly initiated by the well-controlled binding of proteins to the cytoplasmic side of the cell membrane. however, a precise characterization of the spatiotemporal dynamics of membrane-bound proteins is often difficult to achieve in vivo. here, we present protocols for the use of supported lipid bilayers to rebuild the cytokinetic machineries of cells with greatly different dimensions: the bacterium escherichia coli and eggs of the vertebrate xeno ...	2015	25997350
remyelination by resident oligodendrocyte precursor cells in a xenopus laevis inducible model of demyelination.	we have generated a xenopus laevis transgenic line, mbp-gfp-ntr, allowing conditional ablation of myelin-forming oligodendrocytes. in this transgenic line the transgene is driven by the proximal portion of the myelin basic protein regulatory sequence, specific to mature oligodendrocytes. the transgene protein is formed by the green fluorescent protein reporter fused to the escherichia coli nitroreductase (ntr) selection enzyme. the ntr enzyme converts the innocuous prodrug metronidazole (mtz) to ...	2015	25896276
the influence of electromagnetic pollution on living organisms: historical trends and forecasting changes.	current technologies have become a source of omnipresent electromagnetic pollution from generated electromagnetic fields and resulting electromagnetic radiation. in many cases this pollution is much stronger than any natural sources of electromagnetic fields or radiation. the harm caused by this pollution is still open to question since there is no clear and definitive evidence of its negative influence on humans. this is despite the fact that extremely low frequency electromagnetic fields were ...	2015	25811025
nonclassical mhc-restricted invariant vα6 t cells are critical for efficient early innate antiviral immunity in the amphibian xenopus laevis.	nonclassical mhc class ib-restricted invariant t (it) cell subsets are attracting interest because of their potential to regulate immune responses against various pathogens. the biological relevance and evolutionary conservation of it cells have recently been strengthened by the identification of it cells (invariant vα6 [ivα6]) restricted by the nonclassical mhc class ib molecule xnc10 in the amphibian xenopus laevis. these ivα6 t cells are functionally similar to mammalian cd1d-restricted invar ...	2015	26062996
prominent amphibian (xenopus laevis) tadpole type iii interferon response to the frog virus 3 ranavirus.	ranaviruses (iridoviridae) are posing an increasing threat to amphibian populations, with anuran tadpoles being particularly susceptible to these viral infections. moreover, amphibians are the most basal phylogenetic class of vertebrates known to possess both type i and type iii interferon (ifn)-mediated immunity. moreover, little is known regarding the respective roles of the ifn mediators in amphibian antiviral defenses. accordingly, we transcriptionally and functionally compared the amphibian ...	2015	25717104
a molecular characterization of the agonist binding site of a nematode cys-loop gaba receptor.	cys-loop gaba receptors represent important targets for human chemotherapeutics and insecticides and are potential targets for novel anthelmintics (nematicides). however, compared with insect and mammalian receptors, little is known regarding the pharmacological characteristics of nematode cys-loop gaba receptors. here we have investigated the agonist binding site of the cys-loop gaba receptor unc-49 (hco-unc-49) from the parasitic nematode haemonchus contortus.	2015	25850584
a lactate and formate transporter in the intraerythrocytic malaria parasite, plasmodium falciparum.	the intraerythrocytic malaria parasite relies primarily on glycolysis to fuel its rapid growth and reproduction. the major byproduct of this metabolism, lactic acid, is extruded into the external medium. in this study, we show that the human malaria parasite plasmodium falciparum expresses at its surface a member of the microbial formate-nitrite transporter family (pffnt), which, when expressed in xenopus laevis oocytes, transports both formate and lactate. the transport characteristics of pffnt ...	2015	25823844
effects of transgenic cry1ca rice on the development of xenopus laevis.	in fields of genetically modified, insect-resistant rice expressing bacillus thuringiensis (bt) proteins, frogs are exposed to bt cry proteins by consuming both target and non-target insects, and through their highly permeable skin. in the present study, we assessed the potential risk posed by transgenic cry1ca rice (t1c-19) on the development of a frog species by adding purified cry1ca protein or t1c-19 rice straw into the rearing water of xenopus laevis tadpoles, and by feeding x. laevis frogl ...	2015	26695426
lizip3 is a cellular zinc transporter that mediates the tightly regulated import of zinc in leishmania infantum parasites.	cellular zinc homeostasis ensures that the intracellular concentration of this element is kept within limits that enable its participation in critical physiological processes without exerting toxic effects. we report here the identification and characterization of the first mediator of zinc homeostasis in leishmania infantum, lizip3, a member of the zip family of divalent metal-ion transporters. the zinc transporter activity of lizip3 was first disclosed by its capacity to rescue the growth of s ...	2015	25644708
backbone and side-chain nmr assignments for the c-terminal domain of mammalian vps28.	vps28 is one of four cytosolic proteins comprising the endosomal sorting complex required for transport i (escrt-i). escrt-i is involved in sorting ubiquitinated proteins to multivesicular bodies as well as in mediating budding of retroviruses. here, we report the backbone and side-chain assignments of the mammalian c-terminal domain of vps28 (mvps28(ctd)), which is involved in interactions with other escrt components. we also compare the predicted secondary structures of mvps28(ctd) with those ...	2015	24366722
cdc174, a novel component of the exon junction complex whose mutation underlies a syndrome of hypotonia and psychomotor developmental delay.	siblings of non-consanguineous jewish-ethiopian ancestry presented with congenital axial hypotonia, weakness of the abducens nerve, psychomotor developmental delay with brain ventriculomegaly, variable thinning of corpus callosum and cardiac septal defects. homozygosity mapping identified a single disease-associated locus of 3.5 mb on chromosome 3. studies of a bedouin consanguineous kindred affected with a similar recessive phenotype identified a single disease-associated 18 mb homozygosity loc ...	2015	26358778
pseudouridine in mrna: incorporation, detection, and recoding.	it has long been known that pseudouridine (ψ) is the most abundant modified nucleotide in stable rnas, including trna, rrna, and snrna. recent studies using massive parallel sequencing have uncovered the presence of hundreds of ψs in mrnas as well. in eukaryotes and archaea, rna pseudouridylation is introduced predominantly by box h/aca rnps, rna-protein complexes each consisting of a single rna moiety and four core proteins. it has been well established that ψ plays an essential role in regulat ...	2015	26253972
dna-protein crosslink repair.	dna-protein crosslinks (dpcs) are highly toxic dna adducts, but whether dedicated dpc-repair mechanisms exist was until recently unknown. this has changed with discoveries made in yeast and xenopus laevis that revealed a protease-based dna-repair pathway specific for dpcs. importantly, mutations in the gene encoding the putative human homologue of a yeast dpc protease cause a human premature ageing and cancer predisposition syndrome. thus, dpc repair is a previously overlooked genome-maintenance ...	2015	26130008
the xenopus laevis atg4b protease: insights into substrate recognition and application for tag removal from proteins expressed in pro- and eukaryotic hosts.	during autophagy, members of the ubiquitin-like atg8 protein family get conjugated to phosphatidylethanolamine and act as protein-recruiting scaffolds on the autophagosomal membrane. the atg4 protease produces mature atg8 from c-terminally extended precursors and deconjugates lipid-bound atg8. we now found that xenopus laevis atg4b (xatg4b) is ideally suited for proteolytic removal of n-terminal tags from recombinant proteins. to implement this strategy, an atg8 cleavage module is inserted in be ...	2015	25923686
iron deficiency regulated osopt7 is essential for iron homeostasis in rice.	the molecular mechanism of iron (fe) uptake and transport in plants are well-characterized; however, many components of fe homeostasis remain unclear. we cloned iron-deficiency-regulated oligopeptide transporter 7 (osopt7) from rice. osopt7 localized to the plasma membrane and did not transport fe(iii)-dma or fe(ii)-na and gsh in xenopus laevis oocytes. furthermore osopt7 did not complement the growth of yeast fet3fet4 mutant. osopt7 was specifically upregulated in response to fe-deficiency. pro ...	2015	25893776
rapid method to express and purify human membrane protein using the xenopus oocyte system for functional and low-resolution structural analysis.	progress toward elucidating the 3d structures of eukaryotic membrane proteins has been hampered by the lack of appropriate expression systems. recent work using the xenopus oocyte as a novel expression system for structural analysis demonstrates the capability of providing not only the significant amount of protein yields required for structural work but also the expression of eukaryotic membrane proteins in a more native and functional conformation. there is a long history using the oocyte expr ...	2015	25857785
screening breeding sites of the common toad (bufo bufo) in england and wales for evidence of endocrine disrupting activity.	anuran amphibians are often present in agricultural landscapes and may therefore be exposed to chemicals in surface waters used for breeding. we used passive accumulation devices (spmd and pocis) to sample contaminants from nine breeding sites of the common toad (bufo bufo) across england and wales, measuring endocrine activity of the extracts in a recombinant yeast androgen screen (yas) and yeast estrogen screen (yes) and an in vitro vitellogenin induction screen in primary culture of xenopus l ...	2015	25817886
rmnd5 from xenopus laevis is an e3 ubiquitin-ligase and functions in early embryonic forebrain development.	in saccharomyces cerevisiae the gid-complex functions as an ubiquitin-ligase complex that regulates the metabolic switch between glycolysis and gluconeogenesis. in higher organisms six conserved gid proteins form the ctlh protein-complex with unknown function. here we show that rmnd5, the gid2 orthologue from xenopus laevis, is an ubiquitin-ligase embedded in a high molecular weight complex. expression of rmnd5 is strongest in neuronal ectoderm, prospective brain, eyes and ciliated cells of the ...	2015	25793641
investigating polymorphisms in membrane-associated transporter protein slc45a2, using sucrose transporters as a model.	solute carrier family 45 member 2 encodes the melanosomal membrane protein, membrane-associated transporter protein (matp), of unknown function, that is required for normal melanin synthesis. the present study analyzed the effects of two human matp mutations, d93n, which causes oculocutaneous albinism 4 (oca4), and l374f, which is correlated with light pigmentation in european populations. corresponding mutations were produced in the related and well-characterized sucrose transporter from rice, ...	2015	25760657
influence of oxidized purine processing on strand directionality of mismatch repair.	replicative dna polymerases are high fidelity enzymes that misincorporate nucleotides into nascent dna with a frequency lower than [1/10(5)], and this precision is improved to about [1/10(7)] by their proofreading activity. because this fidelity is insufficient to replicate most genomes without error, nature evolved postreplicative mismatch repair (mmr), which improves the fidelity of dna replication by up to 3 orders of magnitude through correcting biosynthetic errors that escaped proofreading. ...	2015	25694431
atnpf5.5, a nitrate transporter affecting nitrogen accumulation in arabidopsis embryo.	dipeptide (leu-leu) and nitrate transport activities of 26 arabidopsis npf (nrt1/ptr family) proteins were screened in saccharomyces cerevisiae and xenopus laevis oocytes, respectively. dipeptide transport activity has been confirmed for 2 already known dipeptide transporters (atnpf8.1 and atnpf8.3) but none of the other tested npfs displays dipeptide transport. the nitrate transport screen resulted in the identification of two new nitrate transporters, atnpf5.5 and atnpf5.10. the localization o ...	2015	25608465
the neonicotinoid imidacloprid, and the pyrethroid deltamethrin, are antagonists of the insect rdl gaba receptor.	a mutation in the second transmembrane domain of the gaba receptor subunit, rdl, is associated with resistance to insecticides such as dieldrin and fipronil. molecular cloning of rdl cdna from a strain of the malaria mosquito, anopheles gambiae, which is highly resistant to dieldrin revealed this mutation (a296g) as well as another mutation in the third transmembrane domain (t345m). wild-type, a296g, t345m and a296g + t345m homomultimeric rdl were expressed in xenopus laevis oocytes and their se ...	2015	26296809
comparative and phylogenetic perspectives of the cleavage process in tailed amphibians.	the order caudata includes about 660 species and displays a variety of important developmental traits such as cleavage pattern and egg size. however, the cleavage process of tailed amphibians has never been analyzed within a phylogenetic framework. we use published data on the embryos of 36 species concerning the character of the third cleavage furrow (latitudinal, longitudinal or variable) and the magnitude of synchronous cleavage period (up to 3-4 synchronous cell divisions in the animal hemis ...	2015	25180466
a heteromeric potassium channel involved in the modulation of the plasma membrane potential is essential for the survival of african trypanosomes.	discovery of novel drug targets may lead to improved treatment of trypanosomiasis. we characterize here 2 gene products of trypanosoma brucei that are essential for the growth of bloodstream form (bsf) parasites, as shown by rna interference (rnai)-mediated down-regulation of the individual mrnas. the primary sequences of the 2 proteins--protein encoded by gene tb927.1.4450 (tbk1) and protein encoded by gene tb927.9.4820 (tbk2)--indicate that both belong to the family of putative, ca(2+)-activat ...	2015	25868728
identification and functional characterization of a novel arginine/ornithine transporter, a member of a cationic amino acid transporter subfamily in the trypanosoma cruzi genome.	trypanosoma cruzi, the etiological agent of chagas disease, is auxotrophic for arginine. it obtains this amino acid from the host through transporters expressed on the plasma membrane and on the membranes of intracellular compartments. a few cationic amino acid transporters have been characterized at the molecular level, such as the novel intracellular arginine/ornithine transporter, tccat1.1, a member of the tccat subfamily that is composed of four almost identical open reading frames in the t. ...	2015	26109388
tcpho91 is a contractile vacuole phosphate sodium symporter that regulates phosphate and polyphosphate metabolism in trypanosoma cruzi.	we have identified a phosphate transporter (tcpho91) localized to the bladder of the contractile vacuole complex (cvc) of trypanosoma cruzi, the etiologic agent of chagas disease. tcpho91 has 12 transmembrane domains, an n-terminal regulatory spx (named after syg1, pho81 and xpr1) domain and an anion permease domain. functional expression in xenopus laevis oocytes followed by two-electrode voltage clamp showed that tcpho91 is a low-affinity transporter with a km for pi in the millimolar range, a ...	2015	26031800
grapevine and arabidopsis cation-chloride cotransporters localize to the golgi and trans-golgi network and indirectly influence long-distance ion transport and plant salt tolerance.	plant cation-chloride cotransporters (cccs) have been implicated in conferring salt tolerance. they are predicted to improve shoot salt exclusion by directly catalyzing the retrieval of sodium (na(+)) and chloride (cl(-)) ions from the root xylem. we investigated whether grapevine (vitis vinifera [vvi]) ccc has a role in salt tolerance by cloning and functionally characterizing the gene from the cultivar cabernet sauvignon. amino acid sequence analysis revealed that vviccc shares a high degree o ...	2015	26378102
aquaporins contribute to aba-triggered stomatal closure through ost1-mediated phosphorylation.	stomatal movements in response to environmental stimuli critically control the plant water status. although these movements are governed by osmotically driven changes in guard cell volume, the role of membrane water channels (aquaporins) has remained hypothetical. assays in epidermal peels showed that knockout arabidopsis thaliana plants lacking the plasma membrane intrinsic protein 2;1 (pip2;1) aquaporin have a defect in stomatal closure, specifically in response to abscisic acid (aba). aba ind ...	2015	26163575
high yield expression and purification of equilibrative nucleoside transporter 7 (ent7) from arabidopsis thaliana.	equilibrative nucleoside transporters (ents) facilitate the import of nucleosides and their analogs into cells in a bidirectional, non-concentrative manner. however, in contrast to their name, most characterized plant ents act in a concentrative manner. a direct characterization of any ent protein has been hindered due to difficulties in overexpression and obtaining pure recombinant protein.	2015	26080001
third-generation electrokinetically pumped sheath-flow nanospray interface with improved stability and sensitivity for automated capillary zone electrophoresis-mass spectrometry analysis of complex proteome digests.	we have reported a set of electrokinetically pumped sheath flow nanoelectrospray interfaces to couple capillary zone electrophoresis with mass spectrometry. a separation capillary is threaded through a cross into a glass emitter. a side arm provides fluidic contact with a sheath buffer reservoir that is connected to a power supply. the potential applied to the sheath buffer drives electro-osmosis in the emitter to pump the sheath fluid at nanoliter per minute rates. our first-generation interfac ...	2015	25786131
phylogenetic and structural analysis of the phospholipase a2 gene family in vertebrates.	the phospholipase a (pla)2 family is the most complex gene family of phospholipases and plays a crucial role in a number of physiological activities. however, the phylogenetic background of the pla2 gene family and the amino acid residues of the pla2g7 gene following positive selection gene remain undetermined. in this study, we downloaded 49 genomic data sets of pla from different species, including the human, house mouse, norway rat, pig, dog, chicken, cattle, african clawed frog, sumatran ora ...	2015	25543670
gene expression pattern of kifc3 during spermatogenesis of the skink eumeces chinensis.	kinesin superfamily is a class of microtubule-dependent motors that play crucial roles in acrosome biogenesis, nuclear reshaping and flagellum formation during spermiogenesis. we have cloned kinesin-like gene kifc3 (termed ec-kifc3) from the total rna of the testis of the skink eumeces chinensis. the cdna sequence of ec-kifc3 had a full-length of 3033bp, including a 260bp 5'-untranslated region (5'utr), a 445bp 3'-untranslated region (3'utr) and an open reading frame that encoded a 775-amino-aci ...	2015	25434495
light induces ultrastructural changes in rod outer and inner segments, including autophagy, in a transgenic xenopus laevis p23h rhodopsin model of retinitis pigmentosa.	we previously reported a transgenic xenopus laevis model of retinitis pigmentosa in which tadpoles express the bovine form of p23h rhodopsin (bp23h) in rod photoreceptors. in this model, retinal degeneration was dependent on light exposure. here, we investigated ultrastructural changes that occurred in the rod photoreceptors of these retinas when exposed to light.	2015	26720441
on the origin of vertebrate somites.	somites, blocks of mesoderm tissue located on either side of the neural tube in the developing vertebrate embryo, are derived from mesenchymal cells in the presomitic mesoderm (psm) and are a defining characteristic of vertebrates. in vertebrates, the somite segmental boundary is determined by notch signalling and the antagonistic relationship of the downstream targets of notch, lfng, and delta1 in the anterior psm. the presence of somites in the basal chordate amphioxus (branchiostoma floridae) ...	2015	26613046
developmental role of plk4 in xenopus laevis and danio rerio: implications for seckel syndrome.	the polo-like kinases are a family of conserved serine/threonine kinases that play multiple roles in regulation of the cell cycle. unlike its four other family members, the role of plk4 in embryonic development has not been well characterized. in mice, plk4(-)(/)(-) embryos arrest at e7.5, just prior to the initiation of somitogenesis. this has led to the hypothesis that plk4 expression may be essential to somitogenesis. recently characterized human mutations lead to seckel syndrome. riboprobe i ...	2015	26150138
site-specific methylation of notch1 controls the amplitude and duration of the notch1 response.	physiologically, notch signal transduction plays a pivotal role in differentiation; pathologically, notch signaling contributes to the development of cancer. transcriptional activation of notch target genes involves cleavage of the notch receptor in response to ligand binding, production of the notch intracellular domain (nicd), and nicd migration into the nucleus and assembly of a coactivator complex. posttranslational modifications of the nicd are important for its transcriptional activity and ...	2015	25805888
comparative assessment of in vitro and in vivo toxicity of azinphos methyl and its commercial formulation.	the toxic effects of gusathion (gus), which is a commercial organophosphate (op) pesticide, and also its active ingredient, azinphos methyl (azm), are evaluated comparatively with in vitro and in vivo studies. initially, the 96-h lc50 values of azm and gus were estimated for two different life stages of xenopus laevis, embryos, and tadpoles. the actual azm concentrations in exposure media were monitored by high-performance liquid chromatography. also, the sub-lethal effects of these compounds to ...	2015	24616035
a gamut of undiscovered electrophysiological effects produced by tityus serrulatus toxin 1 on nav-type isoforms.	in the last decades, ts1 has not only been the subject of many studies, it has also been considered as a very useful tool to investigate nav channels and to explore the exact role of nav channels in channelopathies. ts1 is believed to modulate the activation process of nav upon interaction at the neurotoxin binding site 4. our aim was to carry out an in depth functional characterization of ts1 on a wide array of nav channels, in order to investigate its mechanism of action and to verify if ts1 c ...	2015	25862296
pipa carvalhoi skin secretion profiling: absence of peptides and identification of kynurenic acid as the major constitutive component.	the presence of peptides has been identified in all african pipid genera; nevertheless, little is known about skin secretion of south american frog genus pipa. skin secretion from captive and wild pipa carvalhoi were obtained in the presence or absence of norepinephrine stimulation. the <10 kda fraction was analyzed by liquid chromatography and mass spectrometry, searching for peptides. chromatographic profiles show the presence of a major component in this secretion, regardless of the stimulati ...	2015	25181950
the human acid-sensing ion channel asic1a: evidence for a homotetrameric assembly state at the cell surface.	the chicken acid-sensing ion channel asic1 has been crystallized as a homotrimer. we address here the oligomeric state of the functional asic1 in situ at the cell surface. the oligomeric states of functional asic1a and mutants with additional cysteines introduced in the extracellular pore vestibule were resolved on sds-page. the functional asic1 complexes were stabilized at the cell surface of xenopus laevis oocytes or cho cells either using the sulfhydryl crosslinker bmoe, or sodium tetrathiona ...	2015	26252376
global gene expression during early differentiation of xenopus (silurana) tropicalis gonad tissues.	african clawed frog xenopus sp. is used extensively for developmental biology and toxicology research. amid concerns of environmental pollutants disrupting endocrine systems and causing altered reproductive development in wildlife, eco-toxicology research has led to a focus on linking molecular initiating events to population-level effects. as such, efforts to better understand reproductive development at the molecular level in these model species are warranted. to that end, transcriptomes were ...	2015	24960269
comparative analysis of cartilage marker gene expression patterns during axolotl and xenopus limb regeneration.	axolotls (ambystoma mexicanum) can completely regenerate lost limbs, whereas xenopus laevis frogs cannot. during limb regeneration, a blastema is first formed at the amputation plane. it is thought that this regeneration blastema forms a limb by mechanisms similar to those of a developing embryonic limb bud. furthermore, xenopus laevis frogs can form a blastema after amputation; however, the blastema results in a terminal cone-shaped cartilaginous structure called a "spike." the causes of this p ...	2015	26186213
mesodermal origin of median fin mesenchyme and tail muscle in amphibian larvae.	mesenchyme is an embryonic precursor tissue that generates a range of structures in vertebrates including cartilage, bone, muscle, kidney, and the erythropoietic system. mesenchyme originates from both mesoderm and the neural crest, an ectodermal cell population, via an epithelial to mesenchymal transition (emt). because ectodermal and mesodermal mesenchyme can form in close proximity and give rise to similar derivatives, the embryonic origin of many mesenchyme-derived tissues is still unclear. ...	2015	26086331
[on the classification of the cleavage patterns in amphibian embryos].	this paper presents a brief survey and preliminary classification of embryonic cleavage patterns in the class amphibia. we use published data on 41 anuran and 22 urodele species concerning the character of the third cleavage furrow (latitudinal or longitudinal) and the stage of transition from synchronous to asynchronous blastomere divisions in the animal hemisphere (4-8-celled stage, 8-16-celled stage or later). based on this, four patterns of amphibian embryonic cleavage are recognized, and an ...	2015	25720261
homodimeric anoctamin-1, but not homodimeric anoctamin-6, is activated by calcium increases mediated by the p2y1 and p2x7 receptors.	the p2x7 receptor (p2x7r) is a ligand-gated ion channel that conducts na(+), k(+), and ca(2+) when activated by extracellular atp. in various cell types, such as secretory epithelia, the p2x7r is co-expressed with ca(2+)-dependent cl(-) channels of the tmem16/anoctamin family. here, we studied whether the p2x7r and tmem16a/anoctamin-1 (ano1) or tmem16f/anoctamin-6 (ano6) interact functionally and physically, using oocytes of xenopus laevis and ambystoma mexicanum (axolotl) for heterologous expre ...	2015	25592660
histone deacetylases are required for amphibian tail and limb regeneration but not development.	amphibians such as xenopus laevis and ambystoma mexicanum are capable of whole structure regeneration. however, transcriptional control over these events is not well understood. here, we investigate the role of histone deacetylase (hdac) enzymes in regeneration using hdac inhibitors. the class i/ii hdac inhibitor valproic acid (vpa) inhibits tail regeneration in embryos of the anuran amphibian xenopus laevis, confirming a recent report by others (tseng et al., 2011). this inhibition correlates w ...	2015	22947425
extraordinary diversity in the origins of sex chromosomes in anurans inferred from comparative gene mapping.	sex determination in frogs (anurans) is genetic and includes both male and female heterogamety. however, the origins of the sex chromosomes and their differentiation processes are poorly known. to investigate diversity in the origins of anuran sex chromosomes, we compared the chromosomal locations of sex-linked genes in 4 species: the african clawed frog (xenopus laevis), the western clawed frog (silurana/x. tropicalis), the japanese bell-ring frog (buergeria buergeri), and the japanese wrinkled ...	2015	26089094
the frog inner ear: picture perfect?	many recent accounts of the frog peripheral auditory system have reproduced wever's (1973) schematic cross-section of the ear of a leopard frog. we sought to investigate to what extent this diagram is an accurate and representative depiction of the anuran inner ear, using three-dimensional reconstructions made from serial sections of rana pipiens, eleutherodactylus limbatus and xenopus laevis. in rana, three discrete contact membranes were found to separate the posterior otic (=endolymphatic) la ...	2015	25630769