| mta2 promotes tipin-dependent maintenance of replication fork integrity. | orderly progression of s phase requires the action of replisome-associated tipin and tim1 proteins, whose molecular function is poorly understood. here, we show that tipin deficiency leads to the accumulation of aberrant replication intermediates known as reversed forks. we identified mta2, a subunit of the nurd chromatin remodeler complex, as a novel tipin binding partner and mediator of its function. mta2 is required for tipin-dependent polymerase α binding to replicating chromatin, and this f ... | 2014 | 24830473 |
| transmembrane voltage potential of somatic cells controls oncogene-mediated tumorigenesis at long-range. | the microenvironment is increasingly recognized as a crucial aspect of cancer. in contrast and complement to the field's focus on biochemical factors and extracellular matrix, we characterize a novel aspect of host:tumor interaction - endogenous bioelectric signals among non-excitable somatic cells. extending prior work focused on the bioelectric state of cancer cells themselves, we show for the first time that the resting potentials of distant cells are critical for oncogene-dependent tumorigen ... | 2014 | 24830454 |
| distal expression of sprouty (spry) genes during xenopus laevis limb development and regeneration. | the eukaryotic sprouty (spry) proteins are negative regulators of receptor tyrosine kinase signaling pathways, which in turn provide readout for morphogens such as fibroblast growth factors (fgfs) that are essential for many developmental processes, including limb development. in a transcriptome analysis of early proximo-distal patterning of the xenopus laevis limb bud, spry1a, 2 and 4 were predicted to be expressed predominantly in the distal third. expression of all three in the distal limb in ... | 2014 | 24823862 |
| 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 |
| endothelin modulates the circadian expression of non-visual opsins. | the non-visual opsin, melanopsin, expressed in the mammalian retina, is considered a circadian photopigment because it is responsible to entrain the endogenous biological clock. this photopigment is also present in the melanophores of xenopus laevis, where it was first described, but its role in these cells is not fully understood. x. laevis melanophores respond to light with melanin granule dispersion, the maximal response being achieved at the wavelength of melanopsin maximal excitation. pigme ... | 2014 | 24816266 |
| single cell wound generates electric current circuit and cell membrane potential variations that requires calcium influx. | breaching of the cell membrane is one of the earliest and most common causes of cell injury, tissue damage, and disease. if the compromise in cell membrane is not repaired quickly, irreversible cell damage, cell death and defective organ functions will result. it is therefore fundamentally important to efficiently repair damage to the cell membrane. while the molecular aspects of single cell wound healing are starting to be deciphered, its bio-physical counterpart has been poorly investigated. u ... | 2014 | 24801267 |
| caging, but not air deprivation, slows tadpole growth and development in the amphibian xenopus laevis. | xenopus laevis tadpoles raised in submerged cages in normoxic water develop more slowly than tadpoles raised with access to air. this study distinguishes between the effects of being caged and being deprived access to air on development and growth. tadpoles were raised in high and low density control tanks and in cages in the same tank that were either completely submerged or with the top exposed to air. experiments were repeated with the cages in different positions relative to the air stones a ... | 2014 | 24799365 |
| maternal syntabulin is required for dorsal axis formation and is a germ plasm component in xenopus. | in amphibians and teleosts, early embryonic axial development is driven by maternally deposited mrnas and proteins, called dorsal determinants, which migrate to the presumptive dorsal side of the embryo in a microtubule-dependent manner after fertilization. syntabulin is an adapter protein that binds to kinesin kif5b and to the transmembrane protein syntaxin1. in zebrafish, a mutation in syntabulin causes complete embryo ventralization. it is unknown whether syntabulin plays an analogous role du ... | 2014 | 24798204 |
| structural and functional similarity of amphibian constitutive androstane receptor with mammalian pregnane x receptor. | the nuclear receptors and xenosensors constitutive androstane receptor (car, nr1i3) and pregnane x receptor (pxr, nr1i2) induce the expression of xenobiotic metabolizing enzymes and transporters, which also affects various endobiotics. while human and mouse car feature a high basal activity and low induction upon ligand exposure, we recently identified two constitutive androstane receptors in xenopus laevis (xlcará and â) that possess pxr-like characteristics such as low basal activity and activ ... | 2014 | 24797902 |
| thyroid hormones in the skeletogenesis and accessory sources of endogenous hormones in xenopus laevis (amphibia; anura) ontogeny: experimental evidence. | skeletal development was studied in normal and goitrogen-treated xenopus laevis tadpoles reared under thyroid hormone (th) deficiency. early stages of skeletal development proceed similarly in both groups. later stages are retarded or completely arrested in goitrogen-treated tadpoles. after goitrogen-treated tadpoles were transferred into pure water or into a medium containing both goitrogen and exogenous th, tadpoles resumed development. consequently, late stages of skeletogenesis are th-depend ... | 2014 | 24795191 |
| investigating physical chromatin associations across the xenopus genome by chromatin immunoprecipitation. | chromatin immunoprecipitation (chip) combined with genomic analysis techniques provide a global snapshot of protein-dna interactions in the context of chromatin, yielding insights into which genomic loci might be regulated by the dna-associated protein under investigation. this protocol describes how to perform chip on intact or dissected xenopus embryos. the chip-isolated dna fragments are suitable for high-throughput sequencing (chip-seq) or for quantitative pcr (chip-qpcr). in this protocol, ... | 2014 | 24786504 |
| african clawed toads (xenopus laevis) sense the distance of lateral line stimuli. | sighted african clawed toads use their lateral lines to detect stimulus distance, although accuracy and precision are poorer than for stimulus direction. single surface wave trains elicited discrete turns and/or swims towards the wave origin. most responses were brief, ending with the toad stationary (70% overall; 54-86% individual toads) or pausing before turning away (11%; 1-24%). lunges or capturing movements with the arms (13%; 10-22%) also indicated where toads expected to find prey. overal ... | 2014 | 24781249 |
| nucleoside transporters and human organic cation transporter 1 determine the cellular handling of dna-methyltransferase inhibitors. | inhibitors of dna methyltransferases (dnmts), such as azacytidine, decitabine and zebularine, are used for the epigenetic treatment of cancer. their action may depend upon their translocation across the plasma membrane. the aim of this study was to identify transporter proteins contributing to dnmt inhibitor action. | 2014 | 24780098 |
| biomechanics and the thermotolerance of development. | successful completion of development requires coordination of patterning events with morphogenetic movements. environmental variability challenges this coordination. for example, developing organisms encounter varying environmental temperatures that can strongly influence developmental rates. we hypothesized that the mechanics of morphogenesis would have to be finely adjusted to allow for normal morphogenesis across a wide range of developmental rates. we formulated our hypothesis as a simple mo ... | 2014 | 24776615 |
| unusual evolutionary conservation and further species-specific adaptations of a large family of nonclassical mhc class ib genes across different degrees of genome ploidy in the amphibian subfamily xenopodinae. | nonclassical mhc class ib (class ib) genes are a family of highly diverse and rapidly evolving genes wherein gene numbers, organization, and expression markedly differ even among closely related species rendering class ib phylogeny difficult to establish. whereas among mammals there are few unambiguous class ib gene orthologs, different amphibian species belonging to the anuran subfamily xenopodinae exhibit an unusually high degree of conservation among multiple class ib gene lineages. comparati ... | 2014 | 24771209 |
| the wnt/jnk signaling target gene alcam is required for embryonic kidney development. | proper development of nephrons is essential for kidney function. β-catenin-independent wnt signaling through fzd8, inversin, daam1, rhoa and myosin is required for nephric tubule morphogenesis. here, we provide a novel mechanism through which non-canonical wnt signaling contributes to tubular development. using xenopus laevis as a model system, we found that the cell-adhesion molecule alcam is required for proper nephrogenesis and functions downstream of fzd3 during embryonic kidney development. ... | 2014 | 24764076 |
| monoterpene glycoside esk246 from pittosporum targets lat3 amino acid transport and prostate cancer cell growth. | the l-type amino acid transporter (lat) family consists of four members (lat1-4) that mediate uptake of neutral amino acids including leucine. leucine is not only important as a building block for proteins, but plays a critical role in mtorc1 signaling leading to protein translation. as such, lat family members are commonly upregulated in cancer in order to fuel increased protein translation and cell growth. to identify potential lat-specific inhibitors, we established a function-based high-thro ... | 2014 | 24762008 |
| a device for emulating cuff recordings of action potentials propagating along peripheral nerves. | this paper describes a device that emulates propagation of action potentials along a peripheral nerve, suitable for reproducible testing of bio-potential recording systems using nerve cuff electrodes. the system is a microcontroller-based stand-alone instrument which uses established nerve and electrode models to represent neural activity of real nerves recorded with a nerve cuff interface, taking into consideration electrode impedance, voltages picked up by the electrodes, and action potential ... | 2014 | 24760928 |
| 11-trifluoromethyl-phenyldiazirinyl neurosteroid analogues: potent general anesthetics and photolabeling reagents for gabaa receptors. | while neurosteroids are well-described positive allosteric modulators of gamma-aminobutyric acid type a (gabaa) receptors, the binding sites that mediate these actions have not been definitively identified. | 2014 | 24756762 |
| facial transplants in xenopus laevis embryos. | craniofacial birth defects occur in 1 out of every 700 live births, but etiology is rarely known due to limited understanding of craniofacial development. to identify where signaling pathways and tissues act during patterning of the developing face, a 'face transplant' technique has been developed in embryos of the frog xenopus laevis. a region of presumptive facial tissue (the "extreme anterior domain" (ead)) is removed from a donor embryo at tailbud stage, and transplanted to a host embryo of ... | 2014 | 24748020 |
| trpc2 is expressed in two olfactory subsystems, the main and the vomeronasal system of larval xenopus laevis. | complete segregation of the main olfactory epithelium (moe) and the vomeronasal epithelium is first observed in amphibians. in contrast, teleost fishes possess a single olfactory surface, in which genetic components of the main and vomeronasal olfactory systems are intermingled. the transient receptor potential channel trpc2, a marker of vomeronasal neurons, is present in the single fish sensory surface, but is already restricted to the vomeronasal epithelium in a terrestrial amphibian, the red- ... | 2014 | 24737764 |
| chd7, the gene mutated in charge syndrome, regulates genes involved in neural crest cell guidance. | heterozygous loss of function mutations in chd7 (chromodomain helicase dna-binding protein 7) lead to charge syndrome, a complex developmental disorder affecting craniofacial structures, cranial nerves and several organ systems. recently, it was demonstrated that chd7 is essential for the formation of multipotent migratory neural crest cells, which migrate from the neural tube to many regions of the embryo, where they differentiate into various tissues including craniofacial and heart structures ... | 2014 | 24728844 |
| prolonged in vivo imaging of xenopus laevis. | while live imaging of embryonic development over long periods of time is a well established method for embryos of the frog xenopus laevis, once development has progressed to the swimming stages, continuous live imaging becomes more challenging because the tadpoles must be immobilized. current imaging techniques for these advanced stages generally require bringing the tadpoles in and out of anesthesia for short imaging sessions at selected time points, severely limiting the resolution of the data ... | 2014 | 24723337 |
| functional analysis of a missense mutation in the serine protease inhibitor spint2 associated with congenital sodium diarrhea. | membrane-bound serine proteases play important roles in different biological processes. their regulation by endogenous inhibitors is poorly understood. a y163c mutation in the spint2 gene encoding the serine protease inhibitor hepatocyte growth factor inhibitor hai-2 is associated with a congenital sodium diarrhea. the functional consequences of this mutation on hai-2 activity and its physiological targets are unknown. we established a cellular assay in xenopus laevis oocytes to study functional ... | 2014 | 24722141 |
| immunohistochemical analysis of pax6 and pax7 expression in the cns of adult xenopus laevis. | pax6 and pax7 are transcription factors essential for the development of the cns. in addition, increasing data, mainly obtained in amniotes, support that they are expressed in subsets of neurons in the adult, likely playing a role in maintaining neuron type identity. in the present study we analyzed the detailed distribution of pax6 and pax7 cells in the adult cns of xenopus laevis. immunohistochemistry with antibodies that are required for high-resolution analysis of pax-expressing cells was co ... | 2014 | 24717807 |
| the egg membrane microdomain-associated uroplakin iii-src system becomes functional during oocyte maturation and is required for bidirectional gamete signaling at fertilization in xenopus laevis. | in xenopus laevis, sperm-egg interaction promotes partial proteolysis and/or tyrosine phosphorylation of uroplakin iii (upiii) and the tyrosine kinase src, which both localize to the cholesterol-enriched egg membrane microdomains (mds). here we show that sperm promote proteolysis and/or tyrosine phosphorylation of upiii and src in mds isolated from ovulated and unfertilized eggs (uf-mds). an antibody against the extracellular domain of upiii interferes with these events. inhibition of fertilizat ... | 2014 | 24715460 |
| differential modulation of gaba(a) receptor function by aryl pyrazoles. | several aryl pyrazoles characterized by a different molecular structure (flexible vs constrained), but chemically related to rimonabant and am251, were tested for their ability to modulate the function of recombinant α1β2γ2l gabaa receptors expressed in xenopus laevis oocytes. the effects of 6bio-r, 14bio-r, ness 0327, gp1a and gp2a (0.3-30 μm) were evaluated using a two-electrode voltage-clamp technique. 6bio-r and 14bio-r potentiated gaba-evoked cl(-) currents. ness 0327, gp1a and gp2a did not ... | 2014 | 24704372 |
| behavioral observation of xenopus tadpole swimming for neuroscience labs. | neuroscience labs benefit from reliable, easily-monitored neural responses mediated by well-studied neural pathways. xenopus laevis tadpoles have been used as a simple vertebrate model preparation in motor control studies. most of the neuronal pathways underlying different aspects of tadpole swimming behavior have been revealed. these include the skin mechanosensory touch and pineal eye light-sensing pathways whose activation can initiate swimming, and the cement gland pressure-sensing pathway r ... | 2014 | 24693257 |
| marine natural products acting on the acetylcholine-binding protein and nicotinic receptors: from computer modeling to binding studies and electrophysiology. | for a small library of natural products from marine sponges and ascidians, in silico docking to the lymnaea stagnalis acetylcholine-binding protein (achbp), a model for the ligand-binding domains of nicotinic acetylcholine receptors (nachrs), was carried out and the possibility of complex formation was revealed. it was further experimentally confirmed via competition with radioiodinated α-bungarotoxin ([¹²⁵i]-αbgt) for binding to achbp of the majority of analyzed compounds. alkaloids pibocin, va ... | 2014 | 24686559 |
| ire1α is essential for xenopus pancreas development. | inositol requiring enzyme-1 (ire1) is highly conserved from yeasts to humans. upon the endoplasmic reticulum (er) stress, ire1 activates x-box-binding protein 1 (xbp1) by unconventionally splicing xbp1 mrna, which activates the unfolded protein response (upr) to restore er homeostasis. in mice, ire1α inactivity leads to embryonic death and ire1α plays an essential role in extraembryonic tissues and the placenta. however, its precise action in the embryo proper is still unknown. in this study, th ... | 2014 | 24683410 |
| ephrinb2 affects apical constriction in xenopus embryos and is regulated by adam10 and flotillin-1. | the eph/ephrin signalling pathways have a critical function in cell adhesion and repulsion, and thus play key roles in various morphogenetic events during development. here we show that a decrease in ephrinb2 protein causes neural tube closure defects during xenopus laevis embryogenesis. such a decrease in ephrinb2 protein levels is observed on the loss of flotillin-1 scaffold protein, a newly identified ephrinb2-binding partner. this dramatic decline in ephrinb2 protein levels on the absence of ... | 2014 | 24662724 |
| purification and characterization of a urea sensitive lactate dehydrogenase from the liver of the african clawed frog, xenopus laevis. | the african clawed frog, xenopus laevis, is able to withstand extremely arid conditions by estivating, in conjunction with dehydration tolerance and urea accumulation. estivating x. laevis reduce their metabolic rate and recruit anaerobic glycolysis, driven by lactate dehydrogenase (ldh; e.c. 1.1.1.27) enzymes that reversibly convert pyruvate and nadh to lactate and nad(+), to meet newly established atp demands. the present study investigated purified ldh from the liver of dehydrated and control ... | 2014 | 24651940 |
| disk-shaped amperometric enzymatic biosensor for in vivo detection of d-serine. | at the synapse, d-serine is an endogenous co-agonist for the n-methyl-d-aspartate receptor (nmdar). it plays an important role in synaptic transmission and plasticity and has also been linked to several pathological diseases such as schizophrenia and huntington's. the quantification of local changes in d-serine concentration is essential to further understanding these processes. we report herein the development of a disk-shaped amperometric enzymatic biosensor for detection of d-serine based on ... | 2014 | 24650010 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| differential regulation of two histidine ammonia-lyase genes during xenopus development implicates distinct functions during thyroid hormone-induced formation of adult stem cells. | organ-specific, adult stem cells are essential for organ-homeostasis and tissue repair and regeneration. the formation of such stem cells during vertebrate development remains to be investigated. frog metamorphosis offers an excellent opportunity to study the formation of adult stem cells as this process involves essentially the transformations of all larval tissues/organs into the adult form. of particular interest is the remodeling of the intestine. early studies in xenopus laevis have shown t ... | 2013 | 24499573 |
| the b-subdomain of the xenopus laevis xfin krab-ab domain is responsible for its weaker transcriptional repressor activity compared to human znf10/kox1. | the krüppel-associated box (krab) domain interacts with the nuclear hub protein trim28 to initiate or mediate chromatin-dependent processes like transcriptional repression, imprinting or suppression of endogenous retroviruses. the prototype krab domain initially identified in znf10/kox1 encompasses two subdomains a and b that are found in hundreds of zinc finger transcription factors studied in human and murine genomes. here we demonstrate for the first time transcriptional repressor activity of ... | 2014 | 24498343 |
| relationships between calpains and glutamate- or kainate-induced apoptosis in xenopus laevis tadpoles. | cell glutamate-damage induced by overstimulation of ionotropic receptors is initiated by modification of the intracellular ca2+ homeostasis and the concomitant activation of ca2+-dependent cysteine proteases, the calpain and caspase families. the resultant cleavage of target molecules mediates a critical function in the execution of the cell death. in this work, we investigated relationships between the activity of calpain and glutamate-orkainate-induced apoptosis in several organs of xenopus la ... | 2013 | 24497135 |
| yap1, transcription regulator in the hippo signaling pathway, is required for xenopus limb bud regeneration. | the hippo signaling pathway is conserved from insects to mammals and is important for multiple processes, including cell proliferation, apoptosis and tissue homeostasis. hippo signaling is also crucial for regeneration, including intercalary regeneration, of the whole body in the flatworm and of the leg in the cricket. however, its role in vertebrate epimorphic regeneration is unknown. therefore, to identify principles of regeneration that are conserved among bilaterians, we investigated the rol ... | 2014 | 24491818 |
| phospholipase c and diacylglycerol mediate olfactory responses to amino acids in the main olfactory epithelium of an amphibian. | the semi-aquatic lifestyle of amphibians represents a unique opportunity to study the molecular driving forces involved in the transition of aquatic to terrestrial olfaction in vertebrates. most amphibians have anatomically segregated main and vomeronasal olfactory systems, but at the cellular and molecular level the segregation differs from that found in mammals. we have recently shown that amino acid responses in the main olfactory epithelium (moe) of larval xenopus laevis segregate into a lat ... | 2014 | 24489954 |
| comparative analysis reveals distinct and overlapping functions of mef2c and mef2d during cardiogenesis in xenopus laevis. | the family of vertebrate mef2 transcription factors is comprised of four members named mef2a, mef2b, mef2c, and mef2d. these transcription factors are regulators of the myogenic programs with crucial roles in development of skeletal, cardiac and smooth muscle cells. mef2a and mef2c are essential for cardiac development in mice. in xenopus, mef2c and mef2d but not mef2a were recently shown to be expressed during cardiogenesis. we here investigated the function of mef2c and mef2d during xenopus la ... | 2014 | 24489892 |
| retinal stem/progenitor cells in the ciliary marginal zone complete retinal regeneration: a study of retinal regeneration in a novel animal model. | our research group has extensively studied retinal regeneration in adult xenopus laevis. however, x. laevis does not represent a suitable model for multigenerational genetics and genomic approaches. instead, xenopus tropicalis is considered as the ideal model for these studies, although little is known about retinal regeneration in x. tropicalis. in the present study, we showed that a complete retina regenerates at approximately 30 days after whole retinal removal. the regenerating retina was de ... | 2014 | 24488715 |
| unique pharmacology of heteromeric α7β2 nicotinic acetylcholine receptors expressed in xenopus laevis oocytes. | α7β2 is a novel type of nicotinic acetylcholine receptor shown to be uniquely expressed in cholinergic neurons of the basal forebrain and in hippocampal interneurons. we have compared the pharmacological properties of recombinant homomeric α7 and heteromeric α7β2 nicotinic acetylcholine receptors in order to reveal the pharmacological consequences of β2 subunit incorporation into the pentamer. the non-selective agonist epibatidine did not distinguish α7β2 from α7 nicotinic acetylcholine receptor ... | 2014 | 24485886 |
| mitotic spindle assembly on chromatin patterns made with deep uv photochemistry. | we provide a detailed method to generate arrays of mitotic spindles in vitro. spindles are formed in extract prepared from unfertilized xenopus laevis eggs, which contain all the molecular ingredients of mitotic spindles. the method is based on using deep uv photochemistry to attach chromatin-coated beads on a glass surface according to a pattern of interest. the immobilized beads act as artificial chromosomes, and induce the formation of mitotic spindles in their immediate vicinity. to perform ... | 2014 | 24484654 |
| development of a new decision tree to rapidly screen chemical estrogenic activities of xenopus laevis. | during the last past decades, there is an increasing number of studies about estrogenic activities of the environmental pollutants on amphibians and many determination methods have been proposed. however, these determination methods are time-consuming and expensive, and a rapid and simple method to screen and test the chemicals for estrogenic activities to amphibians is therefore imperative. herein is proposed a new decision tree formulated not only with physicochemical parameters but also a bio ... | 2014 | 27485568 |
| the role of voltage-gated calcium channels in neurotransmitter phenotype specification: coexpression and functional analysis in xenopus laevis. | calcium activity has been implicated in many neurodevelopmental events, including the specification of neurotransmitter phenotypes. higher levels of calcium activity lead to an increased number of inhibitory neural phenotypes, whereas lower levels of calcium activity lead to excitatory neural phenotypes. voltage-gated calcium channels (vgccs) allow for rapid calcium entry and are expressed during early neural stages, making them likely regulators of activity-dependent neurotransmitter phenotype ... | 2014 | 24477801 |
| plakophilin-3 catenin associates with the etv1/er81 transcription factor to positively modulate gene activity. | members of the plakophilin-catenin sub-family (pkp-1, -2, and -3) facilitate the linkage of desmosome junctional components to each other (e.g. desmosomal cadherins to desmoplakin) and the intermediate-filament cytoskeleton. pkps also contribute to desmosomal stabilization and the trafficking of its components. the functions of pkps outside of the desmosome are less well studied, despite evidence suggesting their roles in mrna regulation, small-gtpase modulation (e.g. mid-body scission) during c ... | 2014 | 24475179 |
| identification of dihydrostilbenes in pholidota chinensis as a new scaffold for gabaa receptor modulators. | a dichloromethane extract of stems and roots of pholidota chinensis (orchidaceae) enhanced gaba-induced chloride currents (i(gaba)) by 132.75 ± 36.69% when tested at 100 μg/ml in a two-microelectrode voltage clamp assay, on xenopus laevis oocytes expressing recombinant α₁β₂γ₂s gaba(a) receptors. by means of an hplc-based activity profiling approach, the three structurally related stilbenoids coelonin (1), batatasin iii (2), and pholidotol d (3) were identified in the active fractions of the extr ... | 2014 | 24462176 |
| cartilage derived morphogenetic protein 2 - a potential therapy for intervertebral disc regeneration? | low back pain is amongst the top ten risk factors that contribute to disability, ranking higher than diabetes and mental health disease globally as a contributor to years lost to disability (yld), and escalating as western societies age. abundant evidence suggests that intervertebral disc (ivd) damage is central to the origin of pain in the spine. ivd degeneration involves the progressive deterioration of the highly organized disc tissue extracellular matrix, losing its elasticity and hence its' ... | 2014 | 24457196 |
| nedd4-2 regulates surface expression and may affect n-glycosylation of hyperpolarization-activated cyclic nucleotide-gated (hcn)-1 channels. | hcn channels are important regulators of neuronal excitability. the proper function of these channels is governed by various mechanisms, including post-translational modifications of channel subunits. here, we provide evidence that ubiquitination via a ubiquitin ligase, neuronal precursor cell expressed developmentally downregulated (nedd)-4-2, is involved in the regulation of hyperpolarization-activated cyclic nucleotide-gated (hcn) channels. we identified a py motif (l/ppxy), the characteristi ... | 2014 | 24451387 |
| a nutrient-sensitive restriction point is active during retinal progenitor cell differentiation. | in many growing tissues, slowly dividing stem cells give rise to rapidly proliferating progenitors that eventually exit the cell cycle and differentiate. growth rates are limited by nutrient availability, but it is unclear which steps of the proliferation-differentiation programme are particularly sensitive to fuel supplies. we examined how nutrient deprivation (nd) affects stem and progenitor cells in the ciliary marginal zone (cmz) of the amphibian retina, a well-characterised neurogenic niche ... | 2014 | 24449845 |
| ioxynil and tetrabromobisphenol a suppress thyroid-hormone-induced activation of transcriptional elongation mediated by histone modifications and rna polymerase ii phosphorylation. | to elucidate molecular mechanisms by which the phenolic herbicide ioxynil (iox) and the brominated flame retardant tetrabromobisphenol a (tbbpa) exert thyroid hormone (th) disrupting activity, we investigated the effects of the chemicals on the histone and rna polymerase ii (rnapii) modifications in xenopus laevis xl58-tre-luc cells in direct th-response genes encoding th receptor β (thrb) and th-induced basic leucine zipper protein (thibz) using chromatin immunoprecipitation assays. for both th ... | 2014 | 24449421 |
| quantitative analysis of orofacial development and median clefts in xenopus laevis. | xenopus has become a useful tool to study the molecular mechanisms underlying orofacial development. however, few quantitative analyses exist to describe the anatomy of this region. in this study we combine traditional facial measurements with geometric morphometrics to describe anatomical changes in the orofacial region during normal and abnormal development. facial measurements and principal component (pc) analysis indicate that during early tadpole development the face expands primarily in th ... | 2014 | 24443252 |
| acetylcholine promotes binding of α-conotoxin mii at α3 β2 nicotinic acetylcholine receptors. | α-conotoxin mii (α-ctxmii) is a 16-residue peptide with the sequence gccsnpvchlehsnlc, containing cys2-cys8 and cys3-cys16 disulfide bonds. this peptide, isolated from the venom of the marine cone snail conus magus, is a potent and selective antagonist of neuronal nicotinic acetylcholine receptors (nachrs). to evaluate the impact of channel-ligand interactions on ligand-binding affinity, homology models of the heteropentameric α3β2-nachr were constructed. the models were created in modeller with ... | 2014 | 24420650 |
| impact of the whole-cell patch-clamp configuration on the pharmacological assessment of the herg channel: trazodone as a case example. | voltage- and state-dependent blocks are important mechanisms by which drugs affect voltage-gated ionic channels. however, spontaneous (i.e. drug-free) time-dependent changes in the activation and inactivation of herg and na(+) channels have been reported when using conventional whole-cell patch-clamp in hek-293 cells. | 2016 | 24412489 |
| time-lapse x-ray phase-contrast microtomography for in vivo imaging and analysis of morphogenesis. | x-ray phase-contrast microtomography (xpcμt) is a label-free, high-resolution imaging modality for analyzing early development of vertebrate embryos in vivo by using time-lapse sequences of 3d volumes. here we provide a detailed protocol for applying this technique to study gastrulation in xenopus laevis (african clawed frog) embryos. in contrast to μmri, xpcμt images optically opaque embryos with subminute temporal and micrometer-range spatial resolution. we describe sample preparation, culture ... | 2014 | 24407356 |
| co2 transport by pip2 aquaporins of barley. | co2 permeability of plasma membrane intrinsic protein 2 (pip2) aquaporins of hordeum vulgare l. was investigated. five pip2 members were heterologously expressed in xenopus laevis oocytes. co2 permeability was determined by decrease of cytosolic ph in co2-enriched buffer using a hydrogen ion-selective microelectrode. hvpip2;1, hvpip2;2, hvpip2;3 and hvpip2;5 facilitated co2 transport across the oocyte cell membrane. however, hvpip2;4 that is highly homologous to hvpip2;3 did not. the isoleucine ... | 2014 | 24406630 |
| maintenance of multipotency in human dermal fibroblasts treated with xenopus laevis egg extract requires exogenous fibroblast growth factor-2. | direct reprogramming of a differentiated somatic cell into a developmentally more plastic cell would offer an alternative to applications in regenerative medicine that currently depend on either embryonic stem cells (escs), adult stem cells, or induced pluripotent stem cells (ipscs). here we report the potential of select xenopus laevis egg extract fractions, in combination with exogenous fibroblast growth factor-2 (fgf2), to affect life span, morphology, gene expression, protein translation, an ... | 2014 | 24405062 |
| rem2 is an activity-dependent negative regulator of dendritic complexity in vivo. | a key feature of the cns is structural plasticity, the ability of neurons to alter their morphology and connectivity in response to sensory experience and other changes in the environment. how this structural plasticity is achieved at the molecular level is not well understood. we provide evidence that changes in sensory experience simultaneously trigger multiple signaling pathways that either promote or restrict growth of the dendritic arbor; structural plasticity is achieved through a balance ... | 2014 | 24403140 |
| the human sodium-dependent ascorbic acid transporters slc23a1 and slc23a2 do not mediate ascorbic acid release in the proximal renal epithelial cell. | sodium-dependent ascorbic acid membrane transporters slc23a1 and slc23a2 mediate ascorbic acid (vitamin c) transport into cells. however, it is unknown how ascorbic acid undergoes cellular release, or efflux. we hypothesized that slc23a1 and slc23a2 could serve a dual role, mediating ascorbic acid cellular efflux as well as uptake. renal reabsorption is required for maintaining systemic vitamin c concentrations. because efflux from nephron cells is necessary for reabsorption, we studied whether ... | 2013 | 24400138 |
| regional expression of pax7 in the brain of xenopus laevis during embryonic and larval development. | pax7 is a member of the highly conserved pax gene family that is expressed in restricted zones of the central nervous system (cns) during development, being involved in early brain regionalization and the maintenance of the regional identity. using sensitive immunohistochemical techniques we have analyzed the spatiotemporal pattern of pax7 expression in the brain of the anuran amphibian xenopus laevis, during development. pax7 expression was first detected in early embryos in the basal plate of ... | 2013 | 24399938 |
| conopeptide vt3.1 preferentially inhibits bk potassium channels containing β4 subunits via electrostatic interactions. | bk channel β subunits (β1-β4) modulate the function of channels formed by slo1 subunits to produce tissue-specific phenotypes. the molecular mechanism of how the homologous β subunits differentially alter bk channel functions and the role of different bk channel functions in various physiologic processes remain unclear. by studying channels expressed in xenopus laevis oocytes, we show a novel disulfide-cross-linked dimer conopeptide, vt3.1 that preferentially inhibits bk channels containing the ... | 2014 | 24398688 |
| a novel α4/7-conotoxin lvia from conus lividus that selectively blocks α3β2 vs. α6/α3β2β3 nicotinic acetylcholine receptors. | this study was performed to discover and characterize the first potent α3β2-subtype-selective nicotinic acetylcholine receptor (nachr) ligand. a novel α4/7-conotoxin, α-ctxlvia, was cloned from conus lividus. its pharmacological profile at xenopus laevis oocyte-expressed rat nachr subtypes was determined by 2-electrode voltage-clamp electrophysiology, and its 3-dimensional (3d) structure was determined by nmr spectroscopy. α-ctx lvia is a 16-aa c-terminally-amidated peptide with 2-disulfide brid ... | 2014 | 24398291 |
| rare human nicotinic acetylcholine receptor α4 subunit (chrna4) variants affect expression and function of high-affinity nicotinic acetylcholine receptors. | nicotine, the primary psychoactive component in tobacco smoke, produces its behavioral effects through interactions with neuronal nicotinic acetylcholine receptors (nachrs). α4β2 nachrs are the most abundant in mammalian brain, and converging evidence shows that this subtype mediates the rewarding and reinforcing effects of nicotine. a number of rare variants in the chrna4 gene that encode the α4 nachr subunit have been identified in human subjects and appear to be underrepresented in a cohort o ... | 2014 | 24385388 |
| retinoic acid regulation by cyp26 in vertebrate lens regeneration. | xenopus laevis is among the few species that are capable of fully regenerating a lost lens de novo. this occurs upon removal of the lens, when secreted factors from the retina are permitted to reach the cornea epithelium and trigger it to form a new lens. although many studies have investigated the retinal factors that initiate lens regeneration, relatively little is known about what factors support this process and make the cornea competent to form a lens. we presently investigate the role of r ... | 2014 | 24384390 |
| challenges and approaches to conducting and interpreting the amphibian metamorphosis assay and the fish short-term reproduction assay. | the amphibian metamorphosis assay (ama) and the fish short-term reproduction assay (fstra) are screening assays designed to detect potential endocrine activity of a test substance. these assays are included in a battery of assays in tier 1 of u.s. environmental protection agency's endocrine disruptor screening program. based on our laboratory's experience with these two assays, we have noted several challenges in the conduct and interpretation of the ama and fstra, including, but not limited to, ... | 2014 | 24382780 |
| wnt-dependent osteogenic commitment of bone marrow stromal cells using a novel gsk3β inhibitor. | bone marrow stromal cells (bmscs, also known as bone marrow-derived mesenchymal stem cells) can differentiate into multiple lineages including osteogenic and adipogenic cells. wnt signalling has been implicated in controlling bmsc fate, but the mechanisms are unclear and apparently conflicting data exist. here we show that a novel glycogen synthase kinase 3β inhibitor, ar28, is a potent activator of canonical wnt signalling using in vitro β-catenin translocation studies and tcf-reporter assays. ... | 2014 | 24382458 |
| protein tyrosine phosphatase 4a3 (ptp4a3) is required for xenopus laevis cranial neural crest migration in vivo. | uveal melanoma is the most common intraocular malignancy in adults, representing between about 4% and 5% of all melanomas. high expression levels of protein tyrosine phosphatase 4a3, a dual phosphatase, is highly predictive of metastasis development and ptp4a3 overexpression in uveal melanoma cells increases their in vitro migration and in vivo invasiveness. melanocytes, including uveal melanocytes, are derived from the neural crest during embryonic development. we therefore suggested that ptp4a ... | 2013 | 24376839 |
| characterization of slco5a1/oatp5a1, a solute carrier transport protein with non-classical function. | organic anion transporting polypeptides (oatp/slco) have been identified to mediate the uptake of a broad range of mainly amphipathic molecules. human oatp5a1 was found to be expressed in the epithelium of many cancerous and non-cancerous tissues throughout the body but protein characterization and functional analysis have not yet been performed. this study focused on the biochemical characterization of oatp5a1 using xenopus laevis oocytes and flp-in t-rex-hela cells providing evidence regarding ... | 2013 | 24376674 |
| comparative expression analysis of cysteine-rich intestinal protein family members crip1, 2 and 3 during xenopus laevis embryogenesis. | members of the cysteine-rich intestinal protein (crip) family belong to the group 2 lim proteins. crip proteins are widely expressed in adult mammals but their expression profile and function during embryonic development are still mostly unknown. in this study, we have described for the first time the spatio-temporal expression pattern of the three family members crip1, crip2 and crip3 during xenopus laevis embryogenesis by rt-pcr and whole mount in situ hybridization approaches. we observed tha ... | 2014 | 26154325 |
| epithelial cell division in the xenopus laevis embryo during gastrulation. | how vertebrate epithelial cells divide in vivo and how the cellular environment influences cell division is currently poorly understood. a sine qua non condition to study cell division in situ is the ease of observation of cell division. this is fulfilled in the xenopus embryo at the gastrula stage where polarized epithelial cells divide with a high frequency at the surface of the organism. recently, using this model system, we have shown that epithelial cells divide by asymmetric furrowing and ... | 2014 | 26154319 |