| impact of signaling microcompartment geometry on gpcr dynamics in live retinal photoreceptors. | g protein-coupled receptor (gpcr) cascades rely on membrane protein diffusion for signaling and are generally found in spatially constrained subcellular microcompartments. how the geometry of these microcompartments impacts cascade activities, however, is not understood, primarily because of the inability of current live cell-imaging technologies to resolve these small structures. here, we examine the dynamics of the gpcr rhodopsin within discrete signaling microcompartments of live photorecepto ... | 2012 | 22891277 |
| xtr, a plural tudor domain-containing protein, is involved in the translational regulation of maternal mrna during oocyte maturation in xenopus laevis. | xtr in the fertilized eggs of xenopus has been demonstrated to be a member of a messenger ribonucleoprotein (mrnp) complex that plays a crucial role in karyokinesis during cleavage. since the xtr is also present both in oocytes and spermatocytes and its amount increases immediately after spematogenic cells enter into the meiotic phase, this protein was also predicted to act during meiotic progression. taking advantage of xenopus oocytes' large size to microinject anti-xtr antibody into them for ... | 2012 | 22889276 |
| transcription regulatory mechanism of pitx in the papilla-forming region in the ascidian, halocynthia roretzi, implies conserved involvement of otx as the upstream gene in the adhesive organ development of chordates. | pitx genes play important roles in a variety of developmental processes in vertebrates. in an ascidian species, halocynthia roretzi, hr-pitx, the only pitx gene of this species, has been reported to be expressed in the left epidermis at the tailbud stage. in the present study, first, we have shown that hr-pitx is also expressed in the papilla-forming region at the neurula to tailbud stages, and then we addressed transcription regulatory mechanisms for the expression of hr-pitx in the papilla-for ... | 2012 | 22889275 |
| histochemical identification of sialylated glycans in xenopus laevis testis. | carbohydrate chains of glycoprotein and glycosphingolipids are highly diverse molecules involved in many cell functions, including cell recognition, adhesion and signalling. sialylated glycans are of special interest because the terminal position of sialic acid (neuac) in glycans linked by different ways to subterminal monosaccharides has been shown to be involved in several biological processes, as occurs with gangliosides, which have been reported as being essential in spermatogenesis in mamma ... | 2012 | 22881213 |
| significance of short chain fatty acid transport by members of the monocarboxylate transporter family (mct). | metabolism of short-chain fatty acids (scfa) in the brain, particularly that of acetate, appears to occur mainly in astrocytes. the differential use has been attributed to transport, but the extent to which transmembrane movement of scfa is mediated by transporters has not been investigated systematically. here we tested the possible contribution of monocarboxylate transporters to scfa uptake by measuring fluxes with labelled compounds and by following changes of the intracellular ph in xenopus ... | 2012 | 22878645 |
| hepatic confinement of newly produced erythrocytes caused by low-temperature exposure in xenopus laevis. | diminished erythrocyte count and erythropoiesis have been reported during hypothermia in some ectothermic animals. in this study, the african clawed frog, xenopus laevis, was used to investigate the cause of hypothermia-induced anemia. we developed a new model of hypothermia at 5°c and monitored blood cell count and erythropoiesis on several days. erythrocyte count declined by 30% on the first day following cold exposure (5°c) and mrna expression of hemeoxygenase-1 was enhanced 10-fold; accumula ... | 2012 | 22875773 |
| proteolytic activation of the epithelial sodium channel (enac) by the cysteine protease cathepsin-s. | proteolytic processing of the amiloride-sensitive epithelial sodium channel (enac) by serine proteases is known to be important for channel activation. inappropriate enac activation by proteases may contribute to the pathophysiology of cystic fibrosis and could be involved in sodium retention and the pathogenesis of arterial hypertension in the context of renal disease. we hypothesized that in addition to serine proteases, cathepsin proteases may activate enac. cathepsin proteases belong to the ... | 2012 | 22864553 |
| functional characterization and substrate specificity of a novel gene encoding zinc finger-like protein, zflp, in xenopus laevis oocytes. | in the present study, we isolated and determined the pharmacological characteristics of a novel gene encoding the zinc finger-like protein (zflp). the isolated cdna consisted of 1,581 base pairs that encoded a 526-amino acid protein. the amino acid sequence of zflp is 96% identical to that of zinc finger protein 415 isoform 5 (znf415-5). reverse-transcription (rt)-polymerase chain reaction (pcr) analysis revealed that the zflp mrna is expressed in the breast, lung, stomach, small intestine colon ... | 2012 | 22863851 |
| seeing the warburg effect in the developing retina. | proliferating cells of the xenopus laevis retina facultatively use aerobic glycolysis instead of oxidative phosphorylation. this demonstrates that the metabolic rewiring usually associated with the warburg effect in tumorigenesis may be a more widespread feature of proliferative metabolism than generally appreciated. | 2012 | 22854814 |
| intestinal drug transport via the proton-coupled amino acid transporter pat1 (slc36a1) is inhibited by gly-x(aa) dipeptides. | the oral absorption of some drug substances is mediated by nutrient transporters. as a consequence, nutrients and drugs may compete for available transporters, and interactions at the level of intestinal absorption are possible. recently, we have identified δ-aminolevulinic acid, gly-gly, and gly-sar as substrates of the amino acid transporter pat1. the aim of the present study is to investigate if other gly-containing dipeptides interact with pat1, and whether they can inhibit pat1 mediated dru ... | 2012 | 22853447 |
| the rna-binding protein xcirp2 is involved in apoptotic tail regression during metamorphosis in xenopus laevis tadpoles. | frog metamorphosis induced by thyroid hormone (th) involves not only cell proliferation and differentiation in reconstituted organs such as limbs, but also apoptotic cell death in degenerated organs such as tails. however, the molecular mechanisms directing the th-dependent cell fate determination remain unclear. we have previously identified from newts an rna-binding protein (nrbp) acting as the regulator governing survival and death in germ cells during spermatogenesis. to investigate the mole ... | 2012 | 22850217 |
| intrinsically low open probability of α7 nicotinic acetylcholine receptors can be overcome by positive allosteric modulation and serum factors leading to the generation of excitotoxic currents at physiological temperatures. | α7 nicotinic acetylcholine receptors (nachrs) have been a puzzle since their discovery in brain and non-neuronal tissues. maximal transient probability of an α7 nachr being open with rapid agonist applications is only 0.002. the concentration dependence of α7 responses measured from transfected cells and xenopus laevis oocytes shows the same disparity in potency estimations for peak currents and net charge, despite being studied at 1000-fold different time scales. in both cases the ec₅₀ was appr ... | 2012 | 22828799 |
| microarray-based identification of pitx3 targets during xenopus embryogenesis. | unexpected phenotypes resulting from morpholino-mediated translational knockdown of pitx3 in xenopus laevis required further investigation regarding the genetic networks in which the gene might play a role. microarray analysis was, therefore, used to assess global transcriptional changes downstream of pitx3. | 2012 | 22826267 |
| a developmental requirement for hira-dependent h3.3 deposition revealed at gastrulation in xenopus. | discovering how histone variants that mark distinct chromatin regions affect a developmental program is a major challenge in the epigenetics field. to assess the importance of the h3.3 histone variant and its dedicated histone chaperone hira, we used an established developmental model, xenopus laevis. after the early rapid divisions exploiting a large maternal pool of both replicative h3.2 and replacement h3.3, h3.3 transcripts show a distinct peak of expression at gastrulation. depletion of bot ... | 2012 | 22813747 |
| a substrate binding hinge domain is critical for transport-related structural changes of organic cation transporter 1. | organic cation transporters are membrane potential-dependent facilitative diffusion systems. functional studies, extensive mutagenesis, and homology modeling indicate the following mechanism. a transporter conformation with a large outward-open cleft binds extracellular substrate, passes a state in which the substrate is occluded, turns to a conformation with an inward-open cleft, releases substrate, and subsequently turns back to the outward-open state. in the rat organic cation transporter (ro ... | 2012 | 22810231 |
| direct measurement of diffusion in olfactory cilia using a modified frap approach. | the diffusion coefficient of fluorescein in detached cilia of xenopus laevis olfactory receptor neurons was measured using spatially-resolved frap, where the dye along half of the ciliary length was photobleached and its spatiotemporal fluorescence redistribution recorded. fitting a one-dimensional numerical simulation of diffusion and photobleaching for 35 cilia resulted in a mean value of the diffusion coefficient (1.20 ± 0.23) · 10(-10)m(2)/s and thus a reduction by a factor of 3.4 compared t ... | 2012 | 22808046 |
| biochemical response to exposure to six textile dyes in early developmental stages of xenopus laevis. | the present study was undertaken to determine the toxic effect of a lethal concentration of six different commercially used textile dyes on the 46th stage of xenopus laevis tadpoles. the tadpoles were exposed to astrazon red fbl, astrazon blue fgrl, remazol red rr, remazol turquoise blue g-a, cibacron red fn-3g, and cibacron blue fn-r for 168 h in static test conditions, and thus, 168-h median lethal concentrations (lc(50)s) of each dye were determined to be 0.35, 0.13, 112, 7, 359, and 15.8 mg/ ... | 2013 | 22802115 |
| histone h3k79 methyltransferase dot1l is directly activated by thyroid hormone receptor during xenopus metamorphosis. | thyroid hormone (t3) is important for adult organ function and vertebrate development. amphibian metamorphosis is totally dependent on t3 and offers a unique opportunity to study how t3 controls postembryonic development in vertebrates. earlier studies have demonstrated that tr mediates the metamorphic effects of t3 in xenopus laevis. liganded tr recruits histone modifying coactivator complexes to target genes during metamorphosis. this leads to nucleosomal removal and histone modifications, inc ... | 2012 | 22800560 |
| an integrated field-effect microdevice for monitoring membrane transport in xenopus laevis oocytes via lateral proton diffusion. | an integrated microdevice for measuring proton-dependent membrane activity at the surface of xenopus laevis oocytes is presented. by establishing a stable contact between the oocyte vitelline membrane and an ion-sensitive field-effect (isfet) sensor inside a microperfusion channel, changes in surface ph that are hypothesized to result from facilitated proton lateral diffusion along the membrane were detected. the solute diffusion barrier created between the sensor and the active membrane area al ... | 2012 | 22792166 |
| neck-linker length dependence of processive kinesin-5 motility. | processive motility of individual molecules is essential for the function of many kinesin motors. processivity for kinesins relies on communication between the two heads of a dimeric molecule, such that binding strictly alternates. the main communicating elements are believed to be the two neck linkers connecting the motors' stalks and heads. a proposed mechanism for coordination is the transmission of stress through the neck linkers. it is believed that the efficiency of gating depends on the l ... | 2012 | 22789568 |
| a chimera carrying the functional domain of the orphan protein slc7a14 in the backbone of slc7a2 mediates trans-stimulated arginine transport. | in human skin fibroblasts, a lysosomal transport system specific for cationic amino acids has been described and named system c. we asked if slc7a14 (solute carrier family 7 member a14), an orphan protein assigned to the slc7 subfamily of cationic amino acid transporters (cats) due to sequence homology, may represent system c. fusion proteins between slc7a14 and enhanced gfp localized to intracellular vesicles, co-staining with the lysosomal marker lysotracker(®). to perform transport studies, w ... | 2012 | 22787143 |
| growth, interaction, and positioning of microtubule asters in extremely large vertebrate embryo cells. | ray rappaport spent many years studying microtubule asters, and how they induce cleavage furrows. here, we review recent progress on aster structure and dynamics in zygotes and early blastomeres of xenopus laevis and zebrafish, where cells are extremely large. mitotic and interphase asters differ markedly in size, and only interphase asters span the cell. growth of interphase asters occurs by a mechanism that allows microtubule density at the aster periphery to remain approximately constant as r ... | 2012 | 22786885 |
| activity of long-chain acyl-coa synthetase is required for maintaining meiotic arrest in xenopus laevis. | in most vertebrates, fully grown oocytes are arrested in meiotic prophase i and only resume the cell cycle upon external stimuli, such as hormones. the proper arrest and resumption of the meiotic cycle is critical for reproduction. a galpha(s) signaling pathway essential for the arrest is conserved in organisms from xenopus to mouse and human. a previous gene association study implicated that mutations of human acsl6 may be related to premature ovarian failure. however, functional roles of acsl6 ... | 2012 | 22786823 |
| enzymatic excision of uracil residues in nucleosomes depends on the local dna structure and dynamics. | the excision of uracil bases from dna is accomplished by the enzyme uracil dna glycosylase (ung). recognition of uracil bases in free dna is facilitated by uracil base pair dynamics, but it is not known whether this same mechanistic feature is relevant for detection and excision of uracil residues embedded in nucleosomes. here we investigate this question using nucleosome core particles (ncps) generated from xenopus laevis histones and the high-affinity "widom 601" positioning sequence. the reac ... | 2012 | 22784353 |
| optimization of 4-aminoquinoline/clotrimazole-based hybrid antimalarials: further structure-activity relationships, in vivo studies, and preliminary toxicity profiling. | despite recent progress in the fight against malaria, the emergence and spread of drug-resistant parasites remains a serious obstacle to the treatment of infections. we recently reported the development of a novel antimalarial drug that combines the 4-aminoquinoline pharmacophore of chloroquine with that of clotrimazole-based antimalarials. here we describe the optimization of this class of hybrid drug through in-depth structure-activity relationship studies. antiplasmodial properties and mode o ... | 2012 | 22783984 |
| mortality and morbidity in african clawed frogs (xenopus laevis) associated with construction noise and vibrations. | in spring 2008, 175 adult female xenopus laevis were exposed to construction-related vibrations that caused overt water rippling in the frog tanks. the 3 affected tanks were custom-built static, 300-gal 'pond-style' tanks that sat on the floor of the housing room. the water in the tank developed visible ripples as a result of the vibrations transmitted through the floor during jack-hammering in an adjacent room that was approximately 10 ftaway. all frogs in the tanks displayed buoyancy problems, ... | 2012 | 22776127 |
| the firing patterns of spinal neurons: in situ patch-clamp recordings reveal a key role for potassium currents. | neuron firing patterns underpin the detection and processing of stimuli, influence synaptic interactions, and contribute to the function of networks. to understand how intrinsic membrane properties determine firing patterns, we investigated the biophysical basis of single and repetitive firing in spinal neurons of hatchling xenopus laevis tadpoles, a well-understood vertebrate model; experiments were conducted in situ. primary sensory rohon-beard (rb) neurons fire singly in response to depolaris ... | 2012 | 22775205 |
| dimerization and heme binding are conserved in amphibian and starfish homologues of the microrna processing protein dgcr8. | human digeorge critical region 8 (dgcr8) is an essential microrna (mirna) processing factor that is activated via direct interaction with fe(iii) heme. in order for dgcr8 to bind heme, it must dimerize using a dimerization domain embedded within its heme-binding domain (hbd). we previously reported a crystal structure of the dimerization domain from human dgcr8, which demonstrated how dimerization results in the formation of a surface important for association with heme. here, in an attempt to c ... | 2012 | 22768307 |
| investigation of quadruplex structure under physiological conditions using in-cell nmr. | in this chapter we describe the application of in-cell nmr spectroscopy to the investigation of g-quadruplex structures inside living xenopus laevis oocytes and in x. laevis egg extract. first, in-cell nmr spectroscopy of nucleic acids (na) is introduced and applications and limitations of the approach are discussed. in the following text the application of in-cell nmr spectroscopy to investigation of g-quadruplexes are reviewed. special emphasis is given to the discussion of the influence of th ... | 2013 | 22760824 |
| in-cell nmr in xenopus laevis oocytes. | for the purpose of studying idps inside cells of higher organisms, several eukaryotic in-cell nmr systems have been developed over the past years. in this chapter we will focus on high-resolution in-cell nmr applications in xenopus laevis oocytes, the first eukaryotic cellular model system to be established. in contrast to prokaryotic in-cell nmr samples, eukaryotic in-cell nmr specimens are prepared by cytoplasmic delivery of an exogenously produced, isotope-labeled protein into the non-isotope ... | 2012 | 22760310 |
| α4βδ gaba(a) receptors are high-affinity targets for γ-hydroxybutyric acid (ghb). | γ-hydroxybutyric acid (ghb) binding to brain-specific high-affinity sites is well-established and proposed to explain both physiological and pharmacological actions. however, the mechanistic links between these lines of data are unknown. to identify molecular targets for specific ghb high-affinity binding, we undertook photolinking studies combined with proteomic analyses and identified several gaba(a) receptor subunits as possible candidates. a subsequent functional screening of various recombi ... | 2012 | 22753476 |
| β-hexosaminidase from xenopus laevis eggs and oocytes: from gene to immunochemical characterization. | glycosidases are present both in sperm and eggs in vertebrates and have been associated with different fertilization steps as gamete binding, egg coat penetration, and polyspermy prevention. in this manuscript, we have analyzed the activity of different glycosidases of xenopus laevis eggs. the main activity corresponded to n-acetyl-β-d-glucosaminidase (hex), which was reported to participate both in gamete binding and polyspermy prevention among phylogenetically distant animals. we have raised h ... | 2012 | 22753314 |
| ontogeny of hypoxic modulation of cardiac performance and its allometry in the african clawed frog xenopus laevis. | the ontogeny of cardiac hypoxic responses, and how such responses may be modified by rearing environment, are poorly understood in amphibians. in this study, cardiac performance was investigated in xenopus laevis from 2 to 25 days post-fertilization (dpf). larvae were reared under either normoxia or moderate hypoxia (po₂ = 110 mmhg), and each population was assessed in both normoxia and acute hypoxia. heart rate (f(h)) of normoxic-reared larvae exhibited an early increase from 77 ± 1 beats min⁻¹ ... | 2013 | 22752075 |
| cone outer segments: a biophysical model of membrane dynamics, shape retention, and lamella formation. | an hypothesis is developed to explain how the unique, right circular conical geometry of cone outer segments (coss) in xenopus laevis and other lower vertebrates is maintained during the cycle of axial shortening by apical phagocytosis and axial elongation via the addition of new basal lamellae. extension of a new basal evagination (be) applies radial (lateral) traction to membrane and cytoplasmic domains, achieving two coupled effects. 1), the bilayer domain is locally stretched/dilated, creati ... | 2012 | 22735519 |
| identification of androgen receptor variants in testis from humans and other vertebrates. | the androgen receptor (ar) is a ligand-activated transcription factor member of the nuclear receptor superfamily. the existence of alternatively spliced variants is well recognised for several members of this superfamily, most of them having functional importance. for example, several testicular oestrogen receptor variants have been suggested to play a role in the regulation of spermatogenesis. however, information on ar variants is mostly related to cancer and androgen insensitivity syndrome (a ... | 2013 | 22734680 |
| allosteric modulation of alpha4beta2 nicotinic acetylcholine receptors by hepes. | a number of new positive allosteric modulators (pams) have been reported that enhance responses of neuronal alpha7 and alpha4beta2 nicotinic acetylcholine receptor subtypes to orthosteric ligands. pams represent promising new leads for the development of therapeutic agents for disorders involving alterations in nicotinic neurotransmission including autism, alzheimer's and parkinson's disease. during our recent studies of alpha4beta2 pams, we identified a novel effect of 4-(2-hydroxyethyl)-1-pipe ... | 2014 | 22732654 |
| retraction notice to: overexpression of αcp2, a translational repressor of gap-43, inhibited axon outgrowth during development in xenopus laevis [biochem. biophys. res. commun. 419 (2012) 262–267]. | | 2012 | 22730563 |
| the embryonic development of xenopus laevis under a low frequency electric field. | the aim of this study was to determine the effects of a low frequency electric field on the early embryonic development of frogs. the embryos of african clawed toads, xenopus laevis, were exposed to a 20-μa electric current during the cleavage stages. the developmental processes of embryos during and after electric field exposure were monitored for teratogenic effects. all the embryos continuously exposed to the electric field died without undergoing any developmental processes. however, when th ... | 2012 | 22723004 |
| mitochondrial activation at the onset of contractions in isolated myofibres during successive contractile periods. | at the onset of skeletal muscle repetitive contractions, there is a significant delay in the time to achieve oxidative phosphorylation steady state. the purpose of the present study was to examine the factors that limit oxidative phosphorylation at the onset of contractions. nad(p)h was measured in real time during two contractile periods (2 min each) separated by 5 min of rest in intact single muscle fibres (n = 7) isolated from xenopus laevis. the fibres were then loaded with the dye tetrameth ... | 2012 | 22711953 |
| transport of l-proline by the proton-coupled amino acid transporter pat2 in differentiated 3t3-l1 cells. | mechanism and substrate specificity of the proton-coupled amino acid transporter 2 (pat2, slc36a2) have been studied so far only in heterologous expression systems such as hela cells and xenopus laevis oocytes. in this study, we describe the identification of the first cell line that expresses pat2. we cultured 3t3-l1 cells for up to 2 weeks and differentiated the cells into adipocytes in supplemented media containing 2 μm rosiglitazone. during the 14 day differentiation period the uptake of the ... | 2013 | 22711289 |
| large multimeric assemblies of nucleosome assembly protein and histones revealed by small-angle x-ray scattering and electron microscopy. | the nucleosome assembly protein (nap) family represents a key group of histone chaperones that are essential for cell viability. several x-ray structures of nap1 dimers are available; however, there are currently no structures of this ubiquitous chaperone in complex with histones. we have characterized nap1 from xenopus laevis and reveal that it forms discrete multimers with histones h2a/h2b and h3/h4 at a stoichiometry of one nap dimer to one histone fold dimer. these complexes have been charac ... | 2012 | 22707715 |
| characterization of xenopus tissue inhibitor of metalloproteinases-2: a role in regulating matrix metalloproteinase activity during development. | frog metamorphosis is totally dependent on thyroid hormone (t3) and mimics the postembryonic period around birth in mammals. it is an excellent model to study the molecular basis of postembryonic development in vertebrate. we and others have shown that many, if not all, matrix metalloproteinases (mmps), which cleave proteins of the extracellular matrix as well as other substrates, are induced by t3 and important for metamorphosis. mmp activity can be inhibited by tissue inhibitors of metalloprot ... | 2012 | 22693555 |
| effects of 17α-ethynylestradiol on sexual differentiation and development of the african clawed frog (xenopus laevis). | several studies have shown that exposure of amphibians, including the african clawed frog (xenopus laevis), to potent estrogens at critical times during development results in feminization and/or demasculinization. however, genotyping of x. laevis has only recently become possible, so studies performed in the past were rarely able to make explicit linkages between genetic and phenotypic sex. therefore, to further characterize this relationship, x. laevis tadpoles were exposed during development ... | 2012 | 22692001 |
| williams syndrome transcription factor is critical for neural crest cell function in xenopus laevis. | williams syndrome transcription factor (wstf) is one of ∼25 haplodeficient genes in patients with the complex developmental disorder williams syndrome (ws). ws results in visual/spatial processing defects, cognitive impairment, unique behavioral phenotypes, characteristic "elfin" facial features, low muscle tone and heart defects. wstf exists in several chromatin remodeling complexes and has roles in transcription, replication, and repair. chromatin remodeling is essential during embryogenesis, ... | 2017 | 22691402 |
| involvement of the eukaryotic initiation factor 6 and kermit2/gipc2 in xenopus laevis pronephros formation. | the translation initiation factor eif6 has been implicated as a regulator of ribosome assembly, selective mrna translation and apoptosis. many of these activities depend upon the phosphorylation of eif6 serine 235 by protein kinase c (pkc). eif6-60s is probably part of the rna-induced silencing complex (risc). eif6 over-expression in xenopus embryos causes aberrant eye development. kermit2/gipc2 morphants have an eye phenotype similar to that of the eif6 overexpressors. eye formation is regulate ... | 2012 | 22689378 |
| induction of differentiation of undifferentiated cells into pancreatic beta cells in vertebrates. | the beta cells of the pancreatic islets, which maintain glucose homeostasis by secreting insulin, are important cells for sustaining life. in recent years, islet transplantation has been performed as a treatment for type i diabetes. since there are not enough donors for patients awaiting transplantation, beta cells grown in vitro are expected to be utilized as a substitute for islets. to obtain the cells with properties of human beta cells, it is necessary to understand the process by which huma ... | 2012 | 22689376 |
| in vivo functional analysis of transcription factor: response element interaction using transgenic xenopus laevis. | analysis of transcription factor-target interactions in vivo is important to the study of transcriptional regulation of gene expression. a key experiment involves analysis of the functional interaction between a trans-acting factor and its corresponding cis-acting element in the context of a target promoter in vivo. we describe a method for this analysis in transgenic xenopus tadpoles in which expression of the trans-acting factor is knocked down using an shrna-mediated approach. | 2012 | 22688697 |
| generation of transgenic xenopus using restriction enzyme-mediated integration. | transgenesis, the process of incorporating an exogenous gene (transgene) into an organism's genome, is a widely used tool to develop models of human diseases and to study the function and/or regulation of genes. generating transgenic xenopus is rapid and involves simple in vitro manipulations, taking advantage of the large size of the amphibian egg and external embryonic development. restriction enzyme-mediated integration (remi) has a number of advantages for transgenesis compared to other meth ... | 2012 | 22688696 |
| hybridization between the african clawed frogs xenopus laevis and xenopus muelleri (pipidae) increases the multiplicity of antimicrobial peptides in skin secretions of female offspring. | peptidomic analysis was used to compare the distribution of host-defense peptides in norepinephrine-stimulated skin secretions from laboratory-generated female f1 hybrids of the common clawed frog xenopus laevis (daudin, 1802) and mueller's clawed frog xenopus muelleri (peters, 1844) with the corresponding distribution in skin secretions from the parent species. a total of 18 peptides were identified in secretions from the hybrid frogs. eleven peptides (magainin-1, magainin-2, cpf-1, cpf-3, cpf- ... | 2012 | 22687652 |
| adam13 function is required in the 3 dimensional context of the embryo during cranial neural crest cell migration in xenopus laevis. | the cranial neural crest (cnc) is a population of cells that arises from the lateral part of the developing brain, migrates ventrally and coordinates the entire craniofacial development of vertebrates. many molecules are involved in cnc migration including the transmembrane metalloproteases adam13 and 19. we have previously shown that these adams cleave a number of extracellular proteins and modify the transcription of a number of genes, and that both of these activities are important for cell m ... | 2012 | 22683825 |
| pattern of calbindin-d28k and calretinin immunoreactivity in the brain of xenopus laevis during embryonic and larval development. | the present study represents a detailed spatiotemporal analysis of the localization of calbindin-d28k (cb) and calretinin (cr) immunoreactive structures in the brain of xenopus laevis throughout development, conducted with the aim to correlate the onset of the immunoreactivity with the development of compartmentalization of distinct subdivisions recently identified in the brain of adult amphibians and primarily highlighted when analyzed within a segmental paradigm. cr and cb are expressed early ... | 2013 | 22678695 |
| determining the influence of muscle operating length on muscle performance during frog swimming using a bio-robotic model. | frogs are capable of impressive feats of jumping and swimming. recent work has shown that anuran hind limb muscles can operate at lengths longer than the 'optimal length'. to address the implications of muscle operating length on muscle power output and swimming mechanics, we built a robotic frog hind limb model based upon xenopus laevis. the model simulated the force-length and force-velocity properties of vertebrate muscle, within the skeletal environment. we tested three muscle starting lengt ... | 2012 | 22677569 |
| intestinal peptidases form functional complexes with the neutral amino acid transporter b(0)at1. | the brush-border membrane of the small intestine and kidney proximal tubule are the major sites for the absorption and re-absorption of nutrients in the body respectively. transport of amino acids is mediated through the action of numerous secondary active transporters. in the mouse, neutral amino acids are transported by b(0)at1 [broad neutral ((0)) amino acid transporter 1; slc6a19 (solute carrier family 6 member 19)] in the intestine and by b(0)at1 and b(0)at3 (slc6a18) in the kidney. immunop ... | 2012 | 22677001 |
| probing the xenopus laevis inner ear transcriptome for biological function. | the senses of hearing and balance depend upon mechanoreception, a process that originates in the inner ear and shares features across species. amphibians have been widely used for physiological studies of mechanotransduction by sensory hair cells. in contrast, much less is known of the genetic basis of auditory and vestibular function in this class of animals. among amphibians, the genus xenopus is a well-characterized genetic and developmental model that offers unique opportunities for inner ea ... | 2012 | 22676585 |
| an amphibian model for studies of developmental reproductive toxicity. | the developmental programming of the reproductive system is vulnerable to chemical exposure. it is therefore important to evaluate long-term consequences of early life-stage exposure to endocrine disrupting chemicals. the african clawed frog xenopus tropicalis has several characteristics which facilitates studies of developmental reproductive toxicity. here, i present a x. tropicalis test protocol, including study design, exposure regime, and endpoints for chemical disruption of sex differentiat ... | 2012 | 22669660 |
| photoconversion for tracking the dynamics of cell movement in xenopus laevis embryos. | xenopus laevis is an ideal model system for investigating dynamic morphogenetic processes during embryogenesis, regeneration, and homeostasis. our understanding of these events has been greatly facilitated by lineage labeling, that is, marking a cell or a group of cells and all their descendants using vital dyes, fluorescent molecules, or transplantation techniques. unfortunately, these strategies are limited in their spatiotemporal resolution: they do not allow long-term dynamic in vivo imaging ... | 2012 | 22661444 |
| brain-specific promoter/exon i.f of the cyp19a1 (aromatase) gene in xenopus laevis. | aromatase, encoded by the cyp19a1 gene, is the key enzyme for estrogen biosynthesis. exon i.f of aromatase transcripts in the xenopus brain is driven in a brain-specific manner. in this study, we cloned brain aromatase with a 5'-end of various lengths by 5'-race and detected the expression pattern of the aromatase mrna. in xenopus at the larval stage, the brain aromatase mrna expression was five-fold higher than those in the gonad and liver, and was upregulated from stage 42 to stage 50. after i ... | 2012 | 22659284 |
| association of tctp with centrosome and microtubules. | translationally controlled tumour protein (tctp) associates with microtubules (mt), however, the details of this association are unknown. here we analyze the relationship of tctp with mts and centrosomes in xenopus laevis and mammalian cells using immunofluorescence, tagged tctp expression and immunoelectron microscopy. we show that tctp associates both with mts and centrosomes at spindle poles when detected by species-specific antibodies and by myc-xltctp expression in xenopus and mammalian cel ... | 2012 | 22655198 |
| a switch in aminergic modulation of locomotor cpg output during amphibian metamorphosis. | in the south african clawed frog, xenopus laevis, a complete functional switch in the mode of locomotion occurs during development from axial, undulatory, tail-based swimming in post-hatching tadpoles to limb-based kick propulsion in the adult froglet. at key stages during the metamorphosis from tadpole to frog both locomotor systems are present, co-functional and subject to modulation by the two ubiquitous biogenic amines, serotonin (5-ht) and noradrenaline (na), arising from the brainstem. her ... | 2012 | 22652878 |
| molecular cloning of phd1 and comparative analysis of phd1, 2, and 3 expression in xenopus laevis. | intensive gene targeting studies in mice have revealed that prolyl hydroxylase domain proteins (phds) play important roles in murine embryonic development; however, the expression patterns and function of these genes during embryogenesis of other vertebrates remain largely unknown. here we report the molecular cloning of phd1 and systematic analysis of phd1, phd2, and phd3 expression in embryos as well as adult tissues of xenopus laevis. all three phds are maternally provided during xenopus earl ... | 2012 | 22645445 |
| expression of orexin receptors in the pituitary. | orexin receptors type 1 (ox1r) and type 2 (ox2r) are g protein-coupled receptors whose structure is highly conserved in mammals. ox1r is selective for orexin a, and ox2r binds orexin a and orexin b with similar affinity. orexin receptor expression was observed in human, rat, porcine, sheep as well as xenopus laevis pituitaries, both in the adenohypophysis and in the neurohypophysis. the expression level is regulated by gonadal steroid hormones and gnrh. the majority of orexins reaching the pitui ... | 2012 | 22640608 |
| an immunofluorescence method to analyze the proliferation status of individual nephron segments in the xenopus pronephric kidney. | organ development requires the coordination of proliferation and differentiation of various cell types. this is particularly challenging in the kidney, where up to 26 different cell types with highly specialized functions are present. moreover, even though the nephron initially develops from a common progenitor pool, the individual nephron segments are ultimately quite different in respect to cell numbers. this suggests that some cells in the nephron have a higher proliferative index (i.e., cell ... | 2012 | 22639256 |
| are fish and standardized fetax assays protective enough for amphibians? a case study on xenopus laevis larvae assay with biologically active substances present in livestock wastes. | biologically active substances could reach the aquatic compartment when livestock wastes are considered for recycling. recently, the standardized fetax assay has been questioned, and some researchers have considered that the risk assessment performed on fish could not be protective enough to cover amphibians. in the present study a xenopus laevis acute assay was developed in order to compare the sensitivity of larvae relative to fish or fetax assays; veterinary medicines (ivermectin, oxytetracyc ... | 2012 | 22629159 |
| overlapping cardiac phenotype associated with a familial mutation in the voltage sensor of the kcnq1 channel. | cardiac action potential repolarisation is determined by k(+) currents including i(ks). i(ks) channels are heteromeric channels composed of kcnq1 and kcne e-subunits. mutations in kcnq1 are associated with sinus bradycardia, familial atrial fibrillation (faf) and/or short qt syndrome as a result of gain-of-function, and long qt syndrome (lqts) due to loss-of-function in the ventricles. here, we report that the missense mutation r231c located in s4 voltage sensor domain is associated with a combi ... | 2012 | 22613981 |
| sildenafil acts as potentiator and corrector of cftr but might be not suitable for the treatment of cf lung disease. | the phosphodiesterase-5 inhibitor sildenafil is an established and approved drug to treat symptoms of a variety of human diseases. in the context of cystic fibrosis (cf), a genetic disease caused by a defective cftr gene (e.g. δf508-cftr), it was assumed that sildenafil could be a promising substance to correct impaired protein expression. this study focuses on the molecular mechanisms of sildenafil on cftr recovery. we used δf508-cftr/wt-cftr expressing xenopus laevis oocytes and human bronchia ... | 2012 | 22613978 |
| an inhibitory peptide derived from the α-subunit of the epithelial sodium channel (enac) shows a helical conformation. | proteolytic activation of the heteromeric epithelial sodium channel (enac) is thought to involve the release of inhibitory peptides from the extracellular domains of its α- and γ-subunit. recently, we demonstrated that an α-13-mer peptide, corresponding to a putative inhibitory region within the extracellular domain of human αenac, inhibits human αβγenac. the aim of the present study was to investigate the structural basis of the inhibitory effect of this α-13-mer peptide. analysis of the peptid ... | 2012 | 22613977 |
| crystal structure of the ubiquitin-like domain of human tbk1. | tank-binding kinase 1 (tbk1) is an important enzyme in the regulation of cellular antiviral effects. tbk1 regulates the activity of the interferon regulatory factors irf3 and irf7, thereby playing a key role in type i interferon (ifn) signaling pathways. the structure of tbk1 consists of an n-terminal kinase domain, a middle ubiquitin-like domain (uld), and a c-terminal elongated helical domain. it has been reported that the uld of tbk1 regulates kinase activity, playing an important role in sig ... | 2012 | 22610919 |
| xmab21l3 mediates dorsoventral patterning in xenopus laevis. | specification of the dorsoventral (dv) axis is critical for the subsequent differentiation of regional fate in the primary germ layers of the vertebrate embryo. we have identified a novel factor that is essential for dorsal development in embryos of the frog xenopus laevis. misexpression of xenopus mab21-like 3 (xmab21l3) dorsalizes gastrula-stage mesoderm and neurula-stage ectoderm, while morpholino-mediated knockdown of xmab21l3 inhibits dorsal differentiation of these embryonic germ layers. x ... | 2012 | 22609272 |
| differential effects of busulfan on gonadal development in five divergent anuran species. | the aim of this paper was to investigate the effects of germ cell depletion on the sexual differentiation of gonads in five anuran species. we used busulfan to eliminate the germ cells. our results indicate that germ cells are not required for gonadal ridge formation or the development of the undifferentiated gonads. we observed a gradual degeneration of gonads in studied species and the transdifferentiation of the whole gonads into large fat bodies in xenopus laevis. in the latter the sexual di ... | 2012 | 22609225 |
| ventx factors function as nanog-like guardians of developmental potential in xenopus. | vertebrate development requires progressive commitment of embryonic cells into specific lineages through a continuum of signals that play off differentiation versus multipotency. in mammals, nanog is a key transcription factor that maintains cellular pluripotency by controlling competence to respond to differentiation cues. nanog orthologs are known in most vertebrates examined to date, but absent from the anuran amphibian xenopus. interestingly, in silico analyses and literature scanning reveal ... | 2012 | 22606298 |
| altering membrane topology with sar1 does not impair spindle assembly in xenopus egg extracts. | intracellular membrane networks including the endoplasmic reticulum (er) and the golgi apparatus experience dramatic reorganization upon entry into mitosis. however, the mechanisms driving these rearrangements and their importance for cell division are poorly understood. the gtpase sar1 is a component of the secretory pathway and a key activator of anterograde transport of cargo from the er to the golgi. here we show that sar1 mutant proteins added to metaphase-arrested xenopus laevis egg extrac ... | 2012 | 22605651 |
| microtubule-severing enzymes at the cutting edge. | atp-dependent severing of microtubules was first reported in xenopus laevis egg extracts in 1991. two years later this observation led to the purification of the first known microtubule-severing enzyme, katanin. katanin homologs have now been identified throughout the animal kingdom and in plants. moreover, members of two closely related enzyme subfamilies, spastin and fidgetin, have been found to sever microtubules and might act alongside katanins in some contexts (roll-mecak and mcnally, 2010; ... | 2012 | 22595526 |
| neural activity and branching of embryonic retinal ganglion cell dendrites. | the shape of a neuron's dendritic arbor is critical for its function as it determines the number of inputs the neuron can receive and how those inputs are processed. during development, a neuron initiates primary dendrites that branch to form a simple arbor. subsequently, growth occurs by a process that combines the extension and retraction of existing dendrites, and the addition of new branches. the loss and addition of the fine terminal branches of retinal ganglion cells (rgcs) is dependent on ... | 2012 | 22587886 |
| mutations in irx5 impair craniofacial development and germ cell migration via sdf1. | using homozygosity mapping and locus resequencing, we found that alterations in the homeodomain of the irx5 transcription factor cause a recessive congenital disorder affecting face, brain, blood, heart, bone and gonad development. we found through in vivo modeling in xenopus laevis embryos that irx5 modulates the migration of progenitor cell populations in branchial arches and gonads by repressing sdf1. we further found that transcriptional control by irx5 is modulated by direct protein-protein ... | 2012 | 22581230 |
| strategies to detect interdigital cell death in the frog, xenopus laevis: t3 accerelation, bmp application, and mesenchymal cell cultivation. | fates of digits in amniotes, i.e., free or webbed digits, are determined by the size of programmed interdigital cell death (icd) area. however, no (or very few) cell death has thus far been observed in developing limb buds of non-amniotic terrestrial vertebrates including other anuran or urodela amphibians. we speculate that the undetectable situation of amphibian icd is the result of their less frequency due to slow developmental speed characteristic to most amphibian species. here, we present ... | 2012 | 22580907 |
| tcn 201 selectively blocks glun2a-containing nmdars in a glun1 co-agonist dependent but non-competitive manner. | antagonists that are sufficiently selective to preferentially block glun2a-containing n-methyl-d-aspartate receptors (nmdars) over glun2b-containing nmdars are few in number. in this study we describe a pharmacological characterization of 3-chloro-4-fluoro-n-[4-[[2-(phenylcarbonyl)hydrazino]carbonyl]benzyl]benzenesulphonamide (tcn 201), a sulphonamide derivative, that was recently identified from a high-throughput screen as a potential glun2a-selective antagonist. using two-electrode voltage-cla ... | 2012 | 22579927 |
| function and expression of the proton-coupled amino acid transporter pat1 along the rat gastrointestinal tract: implications for intestinal absorption of gaboxadol. | intestinal absorption via membrane transporters may determine the pharmacokinetics of drug compounds. the hypothesis is that oral absorption of gaboxadol (4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridine-3-ol) in rats occurs via the proton-coupled amino acid transporter, rpat1 (encoded by the gene rslc36a1). consequently, we aimed to elucidate the in vivo role of rpat1 in the absorption of gaboxadol from various intestinal segments obtained from sprague-dawley rats. | 2012 | 22577815 |
| inhibitory effects of dextrorotatory morphinans on the human 5-ht(3a) receptor expressed in xenopus oocytes: involvement of the n-terminal domain of the 5-ht(3a) receptor. | we previously developed a series of dextromethorphan (dm, 3-methoxy-17-methylmorphinan) analogs modified at positions 3 and 17 of the morphinan ring system. recent reports have shown that dm attenuates abdominal pain caused by irritable bowel syndrome, and multidrug regimens that include dm prevent nausea/vomiting following cancer surgery. however, little is known regarding the molecular mechanisms underlying the beneficial effects of dm. here, we investigated the effects of dm, 3 of its analogs ... | 2012 | 22575521 |
| domain specific overexpression of timp-2 and timp-3 reveals mmp-independent functions of timps during xenopus laevis development. | extracellular matrix remodelling mediates many processes including cell migration and differentiation and is regulated through the enzymatic action of matrix metalloproteinases (mmps) and tissue inhibitors of metalloproteinases (timps). timps are secreted proteins, consisting of structurally and functionally distinct n- and c-terminal domains. timp n-terminal domains inhibit mmp activity, whereas their c-terminal domains may have cell signalling activity. the in vivo role of timp n- and c-termin ... | 2012 | 22574808 |
| multiple residues in the distal c terminus of the α-subunit have roles in modulating human epithelial sodium channel activity. | epithelial sodium channels (enac) are critically important in the regulation of ion and fluid balance in both renal and respiratory epithelia. enac functional polymorphisms may contribute to alterations in blood pressure in the general population. we previously reported that the a663t polymorphism in the c terminus of the α-subunit altered enac functional and surface expression in xenopus laevis oocytes (samaha ff, rubenstein rc, yan w, ramkumar m, levy di, ahn yj, sheng s, kleyman tr. j biol ch ... | 2012 | 22573385 |
| pituitary melanotrope cells of xenopus laevis are of neural ridge origin and do not require induction by the infundibulum. | classical studies in amphibians have concluded that the endocrine pituitary and pars intermedia are derived from epithelial buccal epidermis and do not require the infundibulum for their induction. these studies also assumed that the pituitary is not subsequently determined by infundibular induction. our extirpation, auto-transplantation and immunohistochemical studies with xenopus laevis were initiated to investigate early presumptive pituitary development. these studies were conducted especial ... | 2012 | 22569169 |
| [cement gland as the adhesion organ in xenopus laevis embryos]. | the cement gland in batrachians is a temporal ectodermic organ which is necessary for an embryo's attachment to the substrate. in this review, some notions about the origin of the cement gland of xenopus laevis frogs, its functioning, genes being expressed in it, and regulation of its formation and development are provided. the role of some homologies of agrgenes of the cement gland in xenopus laevis is noted at different conditions of other animals and man. | 2012 | 22567923 |
| identification and expression analysis of gpat family genes during early development of xenopus laevis. | production of lysophosphatidic acid (lpa) is the first step in the de novo pathway for glycerolipid biosynthesis, which is mainly catalyzed by the glycerol-3-phosphate acyltransferases (gpats; ec2.3.1.15). dhapat (ec2.3.1.42) also contributes in a minor way, using dihydroxyacetone phosphate as substrate. final products and intermediates of the glycerolipid synthesis pathway are the main structural components of cellular membranes, and provide signalling molecules that regulate diverse biological ... | 2012 | 22564474 |
| asymmetric localization of ck2α during xenopus oogenesis. | the establishment of the dorso-ventral axis is a fundamental process that occurs after fertilization. dorsal axis specification in frogs starts immediately after fertilization, and depends upon activation of wnt/β-catenin signaling. the protein kinase ck2α can modulate wnt/β-catenin signaling and is necessary for dorsal axis specification in xenopus laevis. our previous experiments show that ck2α transcripts and protein are animally localized in embryos, overlapping the region where wnt/β-cateni ... | 2012 | 25346867 |
| aversive training methods in xenopus laevis: general principles. | xenopus laevis is an ideal organism in which to study the mechanisms linking genetics, the embryogenesis of the central nervous system, and the generation of cognitive behavior. frog embryos facilitate the targeting of many pathways of importance to neuroscience via pharmacological, genetic, and surgical manipulations. a limiting factor for investigations of memory and learning has been the difficulty of eliciting learning in xenopus. here, we outline a simple strategy for aversive conditioning ... | 2012 | 22550289 |
| activation of the renal na+:cl- cotransporter by angiotensin ii is a wnk4-dependent process. | pseudohypoaldosteronism type ii is a salt-sensitive form of hypertension with hyperkalemia in humans caused by mutations in the with-no-lysine kinase 4 (wnk4). several studies have shown that wnk4 modulates the activity of the renal na(+)cl(-) cotransporter, ncc. because the renal consequences of wnk4 carrying pseudoaldosteronism type ii mutations resemble the response to intravascular volume depletion (promotion of salt reabsorption without k(+) secretion), a condition that is associated with h ... | 2012 | 22550170 |
| genetic diversity of mhc class i loci in six non-model frogs is shaped by positive selection and gene duplication. | comparative studies of major histocompatibility complex (mhc) genes across vertebrate species can reveal the evolutionary processes that shape the structure and function of immune regulatory proteins. in this study, we characterized mhc class i sequences from six frog species representing three anuran families (hylidae, centrolenidae and ranidae). using cdna from our focal species, we amplified a total of 79 unique sequences spanning exons 2-4 that encode the extracellular domains of the functio ... | 2012 | 22549517 |
| [osteocyte-network in various vertebrates]. | since aquatic and land vertebrates live in different habitats,the morphology and function of bone might be greatly affected by the habitats of each vertebrate. we histologically investigated the bones of various vertebrates including teleost fishes, amphibians, reptiles, and mammals. teleost fishes exhibited either bones contained many osteocytes (cellular bone) or bones have few osteocytes (acellular bone) . the development of osteocyte lacunocanalicular system in the cellular bone of the fish ... | 2012 | 22549191 |
| nucleation and transport organize microtubules in metaphase spindles. | spindles are arrays of microtubules that segregate chromosomes during cell division. it has been difficult to validate models of spindle assembly due to a lack of information on the organization of microtubules in these structures. here we present a method, based on femtosecond laser ablation, capable of measuring the detailed architecture of spindles. we used this method to study the metaphase spindle in xenopus laevis egg extracts and found that microtubules are shortest near poles and become ... | 2012 | 22541427 |
| length and amino acid sequence of peptides substituted for the 5-ht3a receptor m3m4 loop may affect channel expression and desensitization. | 5-ht3a receptors are pentameric neurotransmitter-gated ion channels in the cys-loop receptor family. each subunit contains an extracellular domain, four transmembrane segments (m1, m2, m3, m4) and a 115 residue intracellular loop between m3 and m4. in contrast, the m3m4 loop in prokaryotic homologues is <15 residues. to investigate the limits of m3m4 loop length and composition on channel function we replaced the 5-ht3a m3m4 loop with two to seven alanine residues (5-ht3a-a(n = 2-7)). mutants we ... | 2012 | 22539982 |
| the microvascular anatomy of the trachea in adult xenopus laevis daudin (lissamphibia; anura): scanning electron microscopy of vascular corrosion casts and correlative light microscopy. | studies on the amphibian respiratory tract microvascular anatomy are few and contradictory. using scanning electron microscopy of vascular corrosion casts, correlative light microscopy of paraplast-embedded goldner-stained serial tissue sections, and three-dimensional morphometry, we studied the topographic microvascular anatomy in the trachea of the adult south african clawed toad, xenopus laevis daudin. histomorphology showed that the cartilaginous portion of the trachea contained irregularly ... | 2012 | 22539457 |
| bcnrt1, a plasma membrane-localized nitrate transporter from non-heading chinese cabbage. | a nitrate transporter, bcnrt1, was isolated from non-heading chinese cabbage (brassica campestris ssp. chinensis makino) cultivar 'suzhouqing'. the full-length cdna was obtained using the rapid amplification of cdna ends technique and contains an open reading frame of 1,770 bp that predicts a protein of 589 acid residues that possesses 12 putative transmembrane domains. using the gus marker gene driven by the bcnrt1 promoter, we found bcnrt1 expression to be concentrated in primary and lateral r ... | 2012 | 22539185 |
| microneedle-based analysis of the micromechanics of the metaphase spindle assembled in xenopus laevis egg extracts. | to explain how micrometer-sized cellular structures generate and respond to forces, we need to characterize their micromechanical properties. here we provide a protocol to build and use a dual force-calibrated microneedle-based setup to quantitatively analyze the micromechanics of a metaphase spindle assembled in xenopus laevis egg extracts. this cell-free extract system allows for controlled biochemical perturbations of spindle components. we describe how the microneedles are prepared and how t ... | 2012 | 22538847 |
| visualisation of cerebrospinal fluid flow patterns in albino xenopus larvae in vivo. | it has long been known that cerebrospinal fluid (csf), its composition and flow, play an important part in normal brain development, and ependymal cell ciliary beating as a possible driver of csf flow has previously been studied in mammalian fetuses in vitro. lower vertebrate animals are potential models for analysis of csf flow during development because they are oviparous. albino xenopus laevis larvae are nearly transparent and have a straight, translucent brain that facilitates the observatio ... | 2012 | 22534239 |
| preparation and use of xenopus egg extracts to study dna replication and chromatin associated proteins. | the use of cell-free extracts prepared from eggs of the south african clawed toad, xenopus laevis, has led to many important discoveries in cell cycle research. these egg extracts recapitulate the key nuclear transitions of the eukaryotic cell cycle in vitro under apparently the same controls that exist in vivo. dna added to the extract is first assembled into a nucleus and is then efficiently replicated. progression of the extract into mitosis then allows the separation of paired sister chromat ... | 2012 | 22521908 |
| functional interaction between cftr and the sodium-phosphate co-transport type 2a in xenopus laevis oocytes. | a growing number of proteins, including ion transporters, have been shown to interact with cystic fibrosis transmembrane conductance regulator (cftr). cftr is an epithelial chloride channel that is involved in cystic fibrosis (cf) when mutated; thus a better knowledge of its functional interactome may help to understand the pathophysiology of this complex disease. in the present study, we investigated if cftr and the sodium-phosphate co-transporter type 2a (npt2a) functionally interact after het ... | 2012 | 22514683 |
| effects of pregabalin on the activity of glutamate transporter type 3. | pregabalin, (s)-3-aminomethyl-5-methyl hexanoic acid, is a ligand for the α2δ subunit (a component of voltage-gated calcium channels) and has analgesic and anticonvulsant properties. glutamate uptake by glutamate transporters may be a mechanism for these properties. we investigated the effects of pregabalin on the activity of the neuronal glutamate transporter type 3 (eaat3). | 2012 | 22511482 |
| a simulation study of the combined thermoelectric extracellular stimulation of the sciatic nerve of the xenopus laevis: the localized transient heat block. | the electrical behavior of the xenopus laevis nerve fibers was studied when combined electrical (cuff electrodes) and optical (infrared laser, low power sub-5 mw) stimulations are applied. assuming that the main effect of the laser irradiation on the nerve tissue is the localized temperature increase, this paper analyzes and gives new insights into the function of the combined thermoelectric stimulation on both excitation and blocking of the nerve action potentials (ap). the calculations involve ... | 2012 | 22510941 |
| analysis of the expression of microtubule plus-end tracking proteins (+tips) during xenopus laevis embryogenesis. | microtubules are a component of the cytoskeleton and are important for maintaining cell structure and providing platforms for intracellular transport in diverse cellular processes. microtubule plus-end tracking proteins (+tips), a structurally and functionally diverse group of proteins, are specifically accumulated in the microtubule plus end and regulate dynamic microtubule behavior. we characterized the +tips, clip1, p150(glued), clasp1, lis1 and stim1, in xenopus laevis and report their expre ... | 2012 | 22507908 |
| the xenopus oocyte: a model for studying the metabolic regulation of cancer cell death. | abnormal metabolism and the evasion of apoptosis are both considered hallmarks of cancer. a remarkable biochemical model system, the xenopus laevis oocyte, exhibits altered metabolism coupled to its apoptotic machinery in a similar fashion to cancer cells. this review considers the theory that these two hallmarks of cancer are coupled in tumor cells and provides strong proof that the xenopus laevis oocyte system is an appropriate model in which to dissect the biochemical events underlying the co ... | 2012 | 22507445 |