| long-range gap junctional signaling controls oncogene-mediated tumorigenesis in xenopus laevis embryos. | in addition to the immediate microenvironment, long-range signaling may be an important component of cancer. molecular-genetic analyses have implicated gap junctions-key mediators of cell-cell communication-in carcinogenesis. we recently showed that the resting voltage potential of distant cell groups is a key determinant of metastatic transformation and tumor induction. here, we show in the xenopus laevis model that gap junctional communication (gjc) is a modulator of the long-range bioelectric ... | 2014 | 25646081 |
| dissecting microtubule structures by laser ablation. | here, we describe a detailed protocol, based on laser ablation and fluorescence optical microscopy, to measure the microtubule organization in spindles, including microtubule length distribution, polarity, and plus and minus end densities. the method uses the asymmetry in microtubule depolymerization after a cut, where the newly created microtubule plus ends depolymerize all the way to the minus ends, whereas the newly created minus ends remain stable. the protocol described in this chapter is o ... | 2015 | 25640424 |
| expression of a novel serine/threonine kinase gene, ulk4, in neural progenitors during xenopus laevis forebrain development. | we have analyzed the expression pattern of a novel serine/threonine kinase gene ulk4 during forebrain development in xenopus laevis. to this aim, we firstly cloned a ulk4 cdna fragment from x.laevis and generated a rna probe that was used for its detection by in situ hybridization. throughout development xulk4 expression was detected along the ventricular (vz) and subventricular zones (svz) of all forebrain regions, with the exception of the vz of the striatum. in the adult, xulk4 was also mainl ... | 2015 | 25637795 |
| distinct patterns of endosulfatase gene expression during xenopus laevis limb development and regeneration. | the heparan sulfate 6-o-endosulfatases sulf1 and sulf2 regulate multiple cellular processes and organ development. sulfs modulate a range of heparan-sulfate-dependent extracellular pathways, including the fibroblast growth factor, bone morphogenetic protein, and wingless/wnt signaling pathways. known patterns of sulf transcript expression together with functional experiments have implicated the sulfs in chondrogenesis and muscle regeneration in mammals. here, we describe the expression patterns ... | 2015 | 27499864 |
| the effects of simazine, a chlorotriazine herbicide, on the expression of genes in developing male xenopus laevis. | simazine was investigated for gene expression concurrent with simazine-induced phenotype changes during development of male xenopus laevis. x. laevis tadpoles (nieuwkoop-faber stage 46) were exposed to 0.1, 1.2, 11.0 and 100.9 μg/l simazine for 100 days. the results showed that an increased mortality of x. laevis, decreased gonad weight and altered gonadosomatic index of males significantly (p<0.05) when exposed to simazine at 11.0 and 100.9 µg/l. significant degeneration in testicular tissues w ... | 2015 | 25634327 |
| acute toxic effects of the herbicide formulation and the active ingredient used in cycloxydim-tolerant maize cultivation on embryos and larvae of the african clawed frog, xenopus laevis. | most genetically engineered herbicide-tolerant crops are still awaiting approval in europe. there is, however, a recent trend for the cultivation of cycloxydim-tolerant maize hybrids for use in maize production. we studied the acute toxic effects of the complementary herbicide focus(®) ultra and its active ingredient cycloxydim on embryos and early-stage larvae of the african clawed frog (xenopus laevis). the results indicate that the herbicide formulation is significantly more toxic than the ac ... | 2015 | 25634323 |
| α- and β-subunit composition of voltage-gated sodium channels investigated with μ-conotoxins and the recently discovered μo§-conotoxin gviij. | we investigated the identities of the isoforms of the α (nav1)- and β (navβ)-subunits of voltage-gated sodium channels, including those responsible for action potentials in rodent sciatic nerves. to examine α-subunits, we used seven μ-conotoxins, which target site 1 of the channel. with the use of exogenously expressed channels, we show that two of the μ-conotoxins, μ-buiiib and μ-sxiiia, are 50-fold more potent in blocking nav1.6 from mouse than that from rat. furthermore, we observed that μ-bu ... | 2015 | 25632083 |
| hydrogen sulfide decreases β-adrenergic agonist-stimulated lung liquid clearance by inhibiting enac-mediated transepithelial sodium absorption. | in pulmonary epithelia, β-adrenergic agonists regulate the membrane abundance of the epithelial sodium channel (enac) and, thereby, control the rate of transepithelial electrolyte absorption. this is a crucial regulatory mechanism for lung liquid clearance at birth and thereafter. this study investigated the influence of the gaseous signaling molecule hydrogen sulfide (h2s) on β-adrenergic agonist-regulated pulmonary sodium and liquid absorption. application of the h2s-liberating molecule na2s ( ... | 2015 | 25632025 |
| small-molecule high-throughput screening utilizing xenopus egg extract. | screens for small-molecule modulators of biological pathways typically utilize cultured cell lines, purified proteins, or, recently, model organisms (e.g., zebrafish, drosophila, c. elegans). herein, we describe a method for using xenopus laevis egg extract, a biologically active and highly tractable cell-free system that recapitulates a legion of complex chemical reactions found in intact cells. specifically, we focus on the use of a luciferase-based fusion system to identify small-molecule mod ... | 2015 | 25618336 |
| the wnt receptor frizzled-4 modulates adam13 metalloprotease activity. | cranial neural crest (cnc) cells are a transient population of stem cells that originate at the border of the neural plate and the epidermis, and migrate ventrally to contribute to most of the facial structures including bones, cartilage, muscles and ganglia. adam13 is a cell surface metalloprotease that is essential for cnc cell migration. here, we show in xenopus laevis embryos that the wnt receptor fz4 binds to the cysteine-rich domain of adam13 and negatively regulates its proteolytic activi ... | 2015 | 25616895 |
| temporal and spatial expression analysis of peripheral myelin protein 22 (pmp22) in developing xenopus. | peripheral myelin protein 22 (pmp22), a member of the junction protein family claudin/emp/pmp22, contributes to the formation and maintenance of myelin sheaths in the peripheral nervous system. apart from the establishment and maintenance of peripheral nerves, pmp22 and its family member have also participated in a broad range of more general processes including cell cycle regulation and apoptosis during development. pmp22 has been identified from several vertebrate species including mouse, huma ... | 2015 | 25616247 |
| discovery of a novel general anesthetic chemotype using high-throughput screening. | the development of novel anesthetics has historically been a process of combined serendipity and empiricism, with most recent new anesthetics developed via modification of existing anesthetic structures. | 2015 | 25603205 |
| highly efficient gene knockout by injection of talen mrnas into oocytes and host transfer in xenopus laevis. | zinc-finger nucleases, transcription activator-like effector nucleases (talens) and the crispr/cas (clustered regularly interspaced short palindromic repeats/crispr-associated proteins) system are potentially powerful tools for producing tailor-made knockout animals. however, their mutagenic activity is not high enough to induce mutations at all loci of a target gene throughout an entire tadpole. in this study, we present a highly efficient method for introducing gene modifications at almost all ... | 2015 | 25596277 |
| structural analysis of dopamine- and amphetamine-induced depolarization currents in the human dopamine transporter. | amphetamine (amph) induces depolarizing currents through the human dopamine transporter (hdat). recently we discovered that the s(+) enantiomer of amph induces a current through hdat that persists long after its removal from the external milieu. the persistent current is less prominent for r(-)amph and essentially absent for dopamine (da)-induced currents. related agents such as methamphetamine also exhibit persistent currents, which are present in both frog oocyte and mammalian hek expression s ... | 2015 | 25594379 |
| trpp2-dependent ca2+ signaling in dorso-lateral mesoderm is required for kidney field establishment in xenopus. | in xenopus laevis embryos, kidney field specification is dependent on retinoic acid (ra) and coincides with a dramatic increase of ca(2+) transients, but the role of ca(2+) signaling in the kidney field is unknown. here, we identify trpp2, a member of the transient receptor potential (trp) superfamily of channel proteins encoded by the pkd2 gene, as a central component of ca(2+) signaling in the kidney field. trpp2 is strongly expressed at the plasma membrane where it might regulate extracellula ... | 2015 | 25588842 |
| pan-african phylogeography of a model organism, the african clawed frog 'xenopus laevis'. | the african clawed frog xenopus laevis has a large native distribution over much of sub-saharan africa and is a model organism for research, a proposed disease vector, and an invasive species. despite its prominent role in research and abundance in nature, surprisingly little is known about the phylogeography and evolutionary history of this group. here, we report an analysis of molecular variation of this clade based on 17 loci (one mitochondrial, 16 nuclear) in up to 159 individuals sampled th ... | 2015 | 25583226 |
| interactive effects of ultraviolet-b radiation and pesticide exposure on dna photo-adduct accumulation and expression of dna damage and repair genes in xenopus laevis embryos. | pesticide use and ultraviolet-b (uvb) radiation have both been suggested to adversely affect amphibians; however, little is known about their interactive effects. one potential adverse interaction could involve pesticide-induced dysregulation of dna repair pathways, resulting in greater numbers of dna photo-adducts from uvb exposure. in the present study, we investigated the interactive effects of uvb radiation and two common pesticides (endosulfan and α-cypermethrin) on induction of dna photo-a ... | 2015 | 25569846 |
| effects on channel properties and induction of cell death induced by c-terminal truncations of pannexin1 depend on domain length. | pannexin1 (panx1) is an integral membrane protein and known to form multifunctional hexameric channels. recently, panx1 was identified to be responsible for the release of atp and utp from apoptotic cells after site-specific proteolysis by caspases 3/7. cleavage at the carboxy-terminal (ct) position aa 376-379 irreversibly opens human panx1 channels and leads to the release of the respective nucleotides resulting in recruitment of macrophages and in subsequent activation of the immunologic respo ... | 2015 | 25567359 |
| transmembrane signal transduction in oocyte maturation and fertilization: focusing on xenopus laevis as a model animal. | fertilization is a cell biological phenomenon of crucial importance for the birth of new life in a variety of multicellular and sexual reproduction species such as algae, animal and plants. fertilization involves a sequence of events, in which the female gamete "egg" and the male gamete "spermatozoon (sperm)" develop, acquire their functions, meet and fuse with each other, to initiate embryonic and zygotic development. here, it will be briefly reviewed how oocyte cytoplasmic components are orche ... | 2014 | 25546390 |
| characterization of tweety gene (ttyh1-3) expression in xenopus laevis during embryonic development. | the tweety family of genes encodes large-conductance chloride channels and has been implicated in a wide array of cellular processes including cell division, cell adhesion, regulation of calcium activity, and tumorigenesis, particularly in neuronal cells. however, their expression patterns during early development remain largely unknown. here, we describe the spatial and temporal patterning of ttyh1, ttyh2, and ttyh3 in xenopus laevis during early embryonic development. ttyh1 and ttyh3 are initi ... | 2015 | 25541457 |
| human intestine luminal ace2 and amino acid transporter expression increased by ace-inhibitors. | sodium-dependent neutral amino acid transporter b(0)at1 (slc6a19) and imino acid (proline) transporter sit1 (slc6a20) are expressed at the luminal membrane of small intestine enterocytes and proximal tubule kidney cells where they exert key functions for amino acid (re)absorption as documented by their role in hartnup disorder and iminoglycinuria, respectively. expression of b(0)at1 was shown in rodent intestine to depend on the presence of the carboxypeptidase angiotensin-converting enzyme 2 (a ... | 2015 | 25534429 |
| the effect of 900 and 1800 mhz gsm-like radiofrequency irradiation and nicotine sulfate administration on the embryonic development of xenopus laevis. | the aim of this study was to investigate the effects of gsm-like radiofrequency electromagnetic radiation (rf emr) and nicotine sulfate (ns) exposure on xenopus embryonic development.the developmental effects of gsm-like rf-emr (900-1800 mhz, at a sar value of 1w/kg and ns on xenopus laevis embryos were investigated). following the application of radiofrequency radiation and/or ns administration, the embryos were closely examined in order to determine their possible teratogenic effects. xenopus ... | 2015 | 25531835 |
| negative regulation of the creatine transporter slc6a8 by spak and osr1. | transport regulation involves several kinases including spak (sps1-related proline/alanine-rich kinase) and osr1 (oxidative stress-responsive kinase 1), which are under control of wnk (with-no-k[lys]) kinases. the present study explored whether spak and/or osr1 participate in the regulation of the creatine transporter creat (slc6a8), which accomplishes na+ coupled cellular uptake of creatine in several tissues including kidney, intestine, heart, skeletal muscle and brain. | 2014 | 25531585 |
| pancreatic carcinoma in an african clawed frog (xenopus laevis). | this report describes the histologic features of a pancreatic carcinoma in an adult female african clawed frog (xenopus laevis). the animal was found to be in poor body condition and subsequently euthanized for a complete necropsy. histologically, the pancreas was effaced by packets of polyhedral cells consistent with a pancreatic islet cell carcinoma. metastatic disease was not identified. pancreatic tumors are uncommon in amphibians, and this report is the first to describe a pancreatic carcin ... | 2014 | 25527022 |
| direct nkx2-5 transcriptional repression of isl1 controls cardiomyocyte subtype identity. | during cardiogenesis, most myocytes arise from cardiac progenitors expressing the transcription factors isl1 and nkx2-5. here, we show that a direct repression of isl1 by nkx2-5 is necessary for proper development of the ventricular myocardial lineage. overexpression of nkx2-5 in mouse embryonic stem cells (escs) delayed specification of cardiac progenitors and inhibited expression of isl1 and its downstream targets in isl1(+) precursors. embryos deficient for nkx2-5 in the isl1(+) lineage faile ... | 2015 | 25524439 |
| evidence for multiple, distinct adar-containing complexes in xenopus laevis. | adar (adenosine deaminase acting on rna) is an rna-editing enzyme present in most metazoans that converts adenosines in double-stranded rna targets into inosines. although the rna targets of adar-mediated editing have been extensively cataloged, our understanding of the cellular function of such editing remains incomplete. we report that long, double-stranded rna added to xenopus laevis egg extract is incorporated into an adar-containing complex whose protein components resemble those of stress ... | 2015 | 25519486 |
| vertical signalling involves transmission of hox information from gastrula mesoderm to neurectoderm. | development and patterning of neural tissue in the vertebrate embryo involves a set of molecules and processes whose relationships are not fully understood. classical embryology revealed a remarkable phenomenon known as vertical signalling, a gastrulation stage mechanism that copies anterior-posterior positional information from mesoderm to prospective neural tissue. vertical signalling mediates unambiguous copying of complex information from one tissue layer to another. in this study, we report ... | 2014 | 25514127 |
| pre-meiotic transformation of germplasm-related structures during male gamete differentiation in xenopus laevis. | to highlight the ultrastructural features of transformation occurring with germplasm-related structures (gprs), the spermatogenic cells of xenopus laevis were studied by transmission electron microscopy and quantitative analysis. it was determined that in spermatogonia and spermatocytes, the compact germinal granules underwent fragmentation into particles comparable with inter-mitochondrial cement (imc). fragments of imc agglutinated some cell mitochondria and resulted in the creation of mitocho ... | 2016 | 25511532 |
| subcellular metabolite and lipid analysis of xenopus laevis eggs by laesi mass spectrometry. | xenopus laevis eggs are used as a biological model system for studying fertilization and early embryonic development in vertebrates. most methods used for their molecular analysis require elaborate sample preparation including separate protocols for the water soluble and lipid components. in this study, laser ablation electrospray ionization (laesi), an ambient ionization technique, was used for direct mass spectrometric analysis of x. laevis eggs and early stage embryos up to five cleavage cycl ... | 2014 | 25506922 |
| ntpdase2 and the p2y1 receptor are not required for mammalian eye formation. | eye formation in vertebrates is controlled by a conserved pattern of molecular networks. homeobox transcription factors are crucially involved in the establishment and maintenance of the retina. a previous study of massé et al. (nature, 449: 1058-62, 2007) using morpholino knockdown identified the ectonucleotidase ntpdase2 and the p2y1 receptor as essential elements for eye formation in embryos of the clawed frog xenopus laevis. in order to investigate whether a similarly essential mechanism wou ... | 2015 | 25504514 |
| kcnip1 a ca²⁺-dependent transcriptional repressor regulates the size of the neural plate in xenopus. | in amphibian embryos, our previous work has demonstrated that calcium transients occurring in the dorsal ectoderm at the onset of gastrulation are necessary and sufficient to engage the ectodermal cells into a neural fate by inducing neural specific genes. some of these genes are direct targets of calcium. here we search for a direct transcriptional mechanism by which calcium signals are acting. the only known mechanism responsible for a direct action of calcium on gene transcription involves an ... | 2015 | 25499267 |
| methylmercury exposure during early xenopus laevis development affects cell proliferation and death but not neural progenitor specification. | methylmercury (mehg) is a widespread environmental toxin that preferentially and adversely affects developing organisms. to investigate the impact of mehg toxicity on the formation of the vertebrate nervous system at physiologically relevant concentrations, we designed a graded phenotype scale for evaluating xenopus laevis embryos exposed to mehg in solution. embryos displayed a range of abnormalities in response to mehg, particularly in brain development, which is influenced by both mehg concen ... | 2017 | 25496965 |
| effect of allyl isothiocyanate on developmental toxicity in exposed xenopus laevis embryos. | the pungent natural compound allyl isothiocyanate isolated from the seeds of cruciferous (brassica) plants such as mustard is reported to exhibit numerous beneficial health-promoting antimicrobial, antifungal, anticarcinogenic, cardioprotective, and neuroprotective properties. because it is also reported to damage dna and is toxic to aquatic organisms, the objective of the present study was to determine whether it possesses teratogenic properties. the frog embryo teratogenesis assay-xenopus (fet ... | 2015 | 28962355 |
| apkc phosphorylates p27xic1, providing a mechanistic link between apicobasal polarity and cell-cycle control. | during the development of the nervous system, apicobasally polarized stem cells are characterized by a shorter cell cycle than nonpolar progenitors, leading to a lower differentiation potential of these cells. however, how polarization might be directly linked to the kinetics of the cell cycle is not understood. here, we report that apicobasally polarized neuroepithelial cells in xenopus laevis have a shorter cell cycle than nonpolar progenitors, consistent with mammalian systems. we show that t ... | 2014 | 25490266 |
| brain-derived neurotrophic factor (bdnf) expression in normal and regenerating olfactory epithelium of xenopus laevis. | olfactory epithelium has the capability to continuously regenerate olfactory receptor neurons throughout life. adult neurogenesis results from proliferation and differentiation of neural stem cells, and consequently, olfactory neuroepithelium offers an excellent opportunity to study neural regeneration and the factors involved in the maintenance and regeneration of all their cell types. we analyzed the expression of bdnf in the olfactory system under normal physiological conditions as well as du ... | 2015 | 25488259 |
| distinct action of the α-glucosidase inhibitor miglitol on sglt3, enteroendocrine cells, and glp1 secretion. | oral ingestion of carbohydrate triggers glucagon-like peptide 1 (glp1) secretion, but the molecular mechanism remains elusive. by measuring glp1 concentrations in murine portal vein, we found that the atp-sensitive k(+) (katp) channel is not essential for glucose-induced glp1 secretion from enteroendocrine l cells, while the sodium-glucose co-transporter 1 (sglt1) is required, at least in the early phase (5 min) of secretion. by contrast, co-administration of the α-glucosidase inhibitor (α-gi) m ... | 2015 | 25486965 |
| nuclear size scaling during xenopus early development contributes to midblastula transition timing. | early xenopus laevis embryogenesis is a robust system for investigating mechanisms of developmental timing. after a series of rapid cell divisions with concomitant reductions in cell size, the first major developmental transition is the midblastula transition (mbt), when zygotic transcription begins and cell cycles elongate. whereas the maintenance of a constant nuclear-to-cytoplasmic (n/c) volume ratio is a conserved cellular property, it has long been recognized that the n/c volume ratio chang ... | 2015 | 25484296 |
| aminolevulinate synthase 2 mediates erythrocyte differentiation by regulating larval globin expression during xenopus primary hematopoiesis. | hemoglobin synthesis by erythrocytes continues throughout a vertebrate's lifetime. the mechanism of mammalian heme synthesis has been studied for many years; aminolevulinate synthase 2 (alas2), a heme synthetase, is associated with x-linked dominant protoporphyria in humans. amphibian and mammalian blood cells differ, but little is known about amphibian embryonic hemoglobin synthesis. we investigated the function of the xenopus alas2 gene (xalas2) in primitive amphibian erythrocytes and found th ... | 2015 | 25482442 |
| validation of the sperm chromatin dispersion (scd) test in the amphibian xenopus laevis using in situ nick translation and comet assay. | the integrity of sperm dna is becoming increasingly recognised as an important parameter of semen quality, but there are no published reports of this procedure for any amphibian. the primary aim of this study was to apply a modified sperm chromatin dispersion (scd) test (halomax) to an amphibian sperm model (african clawed frog; xenopus laevis) and to validate the assay against in situ nick translation (isnt) and the double-comet assay procedure. inactivated spermatozoa were collected from fresh ... | 2015 | 25482041 |
| essential amino acid transporter lat4 (slc43a2) is required for mouse development. | amino acid (aa) uniporter lat4 (slc43a2) mediates facilitated diffusion of branched-chain aas, methionine and phenylalanine, although its physiological role and subcellular localization are not known. we report that slc43a2 knockout mice were born at expected mendelian frequency but displayed an ∼10% intrauterine growth retardation and low amniotic fluid aas, suggesting defective transplacental transport. postnatal growth was strongly reduced, with premature death occurring within 9 days such th ... | 2015 | 25480797 |
| microtubule nucleation remote from centrosomes may explain how asters span large cells. | a major challenge in cell biology is to understand how nanometer-sized molecules can organize micrometer-sized cells in space and time. one solution in many animal cells is a radial array of microtubules called an aster, which is nucleated by a central organizing center and spans the entire cytoplasm. frog (here xenopus laevis) embryos are more than 1 mm in diameter and divide with a defined geometry every 30 min. like smaller cells, they are organized by asters, which grow, interact, and move t ... | 2014 | 25468969 |
| calcium-dependent neuroepithelial contractions expel damaged cells from the developing brain. | both developing and adult organisms need efficient strategies for wound repair. in adult mammals, wounding triggers an inflammatory response that can exacerbate tissue injury and lead to scarring. in contrast, embryonic wounds heal quickly and with minimal inflammation, but how this is achieved remains incompletely understood. using in vivo imaging in the developing brain of xenopus laevis, we show that atp release from damaged cells and subsequent activation of purinergic receptors induce long- ... | 2014 | 25468753 |
| distinct patterns of compartmentalization and proteolytic stability of pde6c mutants linked to achromatopsia. | phosphodiesterase-6 (pde6) is an essential effector enzyme in vertebrate photoreceptor cells. mutations in rod and cone pde6 cause recessive retinitis pigmentosa and achromatopsia, respectively. the mechanisms of missense pde6 mutations underlying severe visual disorders are poorly understood. to probe these mechanisms, we expressed seven known missense mutants of cone pde6c in rods of transgenic xenopus laevis and examined their stability and compartmentalization. pde6c proteins with mutations ... | 2015 | 25461672 |
| differential regulation of the glutamate transporters glt-1 and glast by gsk3β. | the glutamate transporters glast and glt-1 are mainly expressed in glial cells and regulate glutamate levels in the synapses. glast and glt-1 are the targets of several signaling pathways. in this study we explore the possible functional interaction between these transporters and gsk3β. this kinase is involved in multiple cellular processes including neuronal development and synaptic plasticity. to evaluate whether glt-1 and glast were regulated by gsk3β, we coexpressed these proteins in heterol ... | 2014 | 25454285 |
| a novel method for inducing nerve growth via modulation of host resting potential: gap junction-mediated and serotonergic signaling mechanisms. | a major goal of regenerative medicine is to restore the function of damaged or missing organs through the implantation of bioengineered or donor-derived components. it is necessary to understand the signals and cues necessary for implanted structures to innervate the host, as organs devoid of neural connections provide little benefit to the patient. while developmental studies have identified neuronal pathfinding molecules required for proper patterning during embryogenesis, strategies to initia ... | 2015 | 25449797 |
| a method for using direct injection of plasmid dna to study cis-regulatory element activity in f0 xenopus embryos and tadpoles. | the ability to express exogenous reporter genes in intact, externally developing embryos, such as xenopus, is a powerful tool for characterizing the activity of cis-regulatory gene elements during development. although methods exist for generating transgenic xenopus lines, more simplified methods for use with f0 animals would significantly speed the characterization of these elements. we discovered that injecting 2-cell stage embryos with a plasmid bearing a ϕc31 integrase-targeted attb element ... | 2015 | 25448690 |
| cellular characterization of thrombocytes in xenopus laevis with specific monoclonal antibodies. | platelets are produced from megakaryocytes (mks) in the bone marrow. in contrast, most nonmammalian vertebrates have nucleated and spindle-shaped thrombocytes instead of platelets in their circulatory systems, and the presence of mks as thrombocyte progenitors has not been verified. in developing a new animal model in adult african clawed frog (xenopus laevis), we needed to distinguish nucleated thrombocytes and their progenitors from other blood cells, because the cellular morphology of activat ... | 2015 | 25448492 |
| changes in gastric sodium-iodide symporter (nis) activity are associated with differences in thyroid gland sensitivity to perchlorate during metamorphosis. | we investigated stage-dependent changes in sensitivity of the thyroid gland to perchlorate during development of african clawed frog tadpoles (xenopus laevis) in relation to non-thyroidal iodide transporting tissues. perchlorate-induced increases in thyroid follicle cell size and colloid depletion were blunted when exposures began at nieuwkoop-faber (nf) stage 55 compared to when exposures began at nf stages 49 or 1-10. to determine if the development of other iodide transporting tissues may con ... | 2015 | 25448256 |
| biological and biochemical properties of two xenopus laevis n-acetylgalactosaminyltransferases with contrasting roles in embryogenesis. | the biosynthesis of mucin-type o-linked glycans in animals is initiated by members of the large family of polypeptide n-acetylgalactosaminyltransferases (galnac-ts), which play important roles in embryogenesis, organogenesis, adult tissue homeostasis and carcinogenesis. until now, the mammalian forms of these enzymes have been the best characterized. however, two n-acetylgalactosaminyltransferases (xgalnac-t6 and xgalnac-t16) from the african clawed frog (xenopus laevis), which are most homologo ... | 2015 | 25447273 |
| a gene expression map of the larval xenopus laevis head reveals developmental changes underlying the evolution of new skeletal elements. | the morphology of the vertebrate head skeleton is highly plastic, with the number, size, shape, and position of its components varying dramatically between groups. while this evolutionary flexibility has been key to vertebrate success, its developmental and genetic bases are poorly understood. the larval head skeleton of the frog xenopus laevis possesses a unique combination of ancestral tetrapod features and anuran-specific novelties. we built a detailed gene expression map of the head mesenchy ... | 2015 | 25446275 |
| xenopus laevis fgf receptor substrate 3 (xfrs3) is important for eye development and mediates pax6 expression in lens placode through its shp2-binding sites. | members of the fibroblast growth factor (fgf) family play important roles during various developmental processes including eye development. frs (fgf receptor substrate) proteins bind to fgfr and serve as adapters for coordinated assembly of multi-protein complexes involved in ras/mapk and pi3 kinase/akt pathways. here, we identified xenopus laevis frs3 (xfrs3), a homolog of vertebrate frs3, and investigated its roles during embryogenesis. xfrs3 is expressed maternally and zygotically with specif ... | 2015 | 25446028 |
| transcriptional changes in african clawed frogs (xenopus laevis) exposed to 17α-ethynylestradiol during early development. | although the past two decades have witnessed a significant increase in the number of studies investigating effects of estrogenic chemicals on amphibians, to date little is known about specific molecular interactions of estrogens with the hypothalamus-pituitary-gonadal-hepatic axis in developing amphibians. here, tissue-specific functional sets of genes, derived previously from studies of fishes exposed to endocrine active chemicals, were evaluated in xenopus laevis exposed to 17α-ethynylestradio ... | 2015 | 25427717 |
| dynein light intermediate chains maintain spindle bipolarity by functioning in centriole cohesion. | cytoplasmic dynein 1 (dynein) is a minus end-directed microtubule motor protein with many cellular functions, including during cell division. the role of the light intermediate chains (lics; dync1li1 and 2) within the complex is poorly understood. in this paper, we have used small interfering rnas or morpholino oligonucleotides to deplete the lics in human cell lines and xenopus laevis early embryos to dissect the lics' role in cell division. we show that although dynein lacking lics drives micr ... | 2014 | 25422374 |
| mutations in the voltage-gated potassium channel gene kcnh1 cause temple-baraitser syndrome and epilepsy. | temple-baraitser syndrome (tbs) is a multisystem developmental disorder characterized by intellectual disability, epilepsy, and hypoplasia or aplasia of the nails of the thumb and great toe. here we report damaging de novo mutations in kcnh1 (encoding a protein called ether à go-go, eag1 or kv10.1), a voltage-gated potassium channel that is predominantly expressed in the central nervous system (cns), in six individuals with tbs. characterization of the mutant channels in both xenopus laevis oocy ... | 2015 | 25420144 |
| identifying direct targets of transcription factor rfx2 that coordinate ciliogenesis and cell movement. | recently, using the frog xenopus laevis as a model system, we showed that transcription factor rfx2 coordinates many genes involved in ciliogenesis and cell movement in multiciliated cells (chung et al., 2014). to our knowledge, it was the first paper to utilize the genomic resources, including genome sequences and interim gene annotations, from the ongoing xenopus laevis genome project. for researchers who are interested in the application of genomics and systems biology approaches in xenopus s ... | 2014 | 25419512 |
| protocadherin-9 involvement in retinal development in xenopus laevis. | biological roles of most protocadherins (pcdhs) are a largely unsolved problem. therefore, we cloned cdna for xenopus laevis protocadherin-9 and characterized its properties to elucidate the role. the deduced amino acid sequence was highly homologous to those of mammalian protocadherin-9 s. x. laevis protocadherin-9 expressed from the cdna in l cells showed basic properties similar to those of mammalian pcdhs. expression of x. laevis protocadherin-9 was first detected in stage-31 embryos and inc ... | 2015 | 25414271 |
| diurnal variation of tight junction integrity associates inversely with matrix metalloproteinase expression in xenopus laevis corneal epithelium: implications for circadian regulation of homeostatic surface cell desquamation. | the corneal epithelium provides a protective barrier against pathogen entrance and abrasive forces, largely due to the intercellular junctional complexes between neighboring cells. after a prescribed duration at the corneal surface, tight junctions between squamous surface cells must be disrupted to enable them to desquamate as a component of the tissue homeostatic renewal. we hypothesize that matrix metalloproteinase (mmps) are secreted by corneal epithelial cells and cleave intercellular junct ... | 2014 | 25412440 |
| assessment of natural variation in the first pore domain of the tomato hkt1;2 transporter and characterization of mutated versions of slhkt1;2 expressed in xenopus laevis oocytes and via complementation of the salt sensitive athkt1;1 mutant. | single nucleotide polymorphisms (snps) within the coding sequence of hkt transporters are important for the functioning of these transporters in several plant species. to unravel the functioning of hkt transporters analysis of natural variation and multiple site-directed mutations studies are crucial. also the in vivo functioning of hkt proteins, via complementation studies performed with athkt1;1 plants, could provide essential information about these transporters. in this work, we analyzed the ... | 2014 | 25408697 |
| the olfactory system as a model to study axonal growth patterns and morphology in vivo. | the olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. olfactory stem cells in the basal portion of the olfactory epithelium continuously give rise to new sensory neurons that extend their axons into the olfactory bulb, where they face the challenge to integrate into existing circuitry. because of this particular feature, the olfactory system represents a unique opportunity to monitor axonal wiring and guidance, and to investigate synapse fo ... | 2014 | 25406975 |
| phosphatidylinositol 4,5-bisphosphate degradation inhibits the na+/bicarbonate cotransporter nbce1-b and -c variants expressed in xenopus oocytes. | we previously reported that the phospholipid phosphatidylinositol 4,5-bisphosphate (pip2 ) directly stimulates heterologously expressed electrogenic na(+)/bicarbonate cotransporter nbce1-a in an excised macropatch from the xenopus oocyte, and indirectly stimulates nbce1-b and -c in the intact oocyte primarily through inositol 1,4,5-trisphosphate/ca(2+). in the current study, we expand on a previous observation that pip2 may also directly stimulate nbce1 in the intact oocyte. in this study on ooc ... | 2015 | 25398525 |
| hcn2 channels: a permanent open state and conductance changes. | hyperpolarization-activated cyclic nucleotide-gated (hcn) channels in the membranes of heart and brain cells can conduct na(+) and k(+) ions and activate between -30 and -120 mv. we express the α subunit of hcn2 channels in xenopus laevis oocytes and are confronted with two unexpected problems. first, we observe a rise in membrane conductance at resting potential proportional to the amount of expression. on activation to hyperpolarizing potentials, the instantaneous conductance rises in proporti ... | 2015 | 25391723 |
| system l amino acid transporter lat1 accumulates o-(2-fluoroethyl)-l-tyrosine (fet). | o-(2-fluoroethyl)-l-tyrosine (fet) labeled with fluorine-18 is an important and specific tracer for diagnostics of glioblastoma via positron emission tomography (pet). however, the mechanism of its quite specific accumulation in tumor tissue has not been understood so far. in this work we demonstrate that [(3)h]l-tyrosine is primarily transported by the system l transporter lat1 in human ln229 glioblastoma cells. fet reduced tyrosine transport, suggesting that it shares the same uptake pathway. ... | 2015 | 25385314 |
| carbon monoxide (co) is a novel inhibitor of connexin hemichannels. | hemichannels (hcs) are hexamers of connexins that can form gap-junction channels at points of cell contacts or "free hcs" at non-contacting regions. hcs are involved in paracrine and autocrine cell signaling, and under pathological conditions may induce and/or accelerate cell death. therefore, studies of hc regulation are of great significance. nitric oxide affects the activity of cx43 and cx46 hcs, whereas carbon monoxide (co), another gaseous transmitter, modulates the activity of several ion ... | 2014 | 25384983 |
| recruitment of gβγ controls the basal activity of g-protein coupled inwardly rectifying potassium (girk) channels: crucial role of distal c terminus of girk1. | the g-protein coupled inwardly rectifying potassium (girk, or kir3) channels are important mediators of inhibitory neurotransmission via activation of g-protein coupled receptors (gpcrs). girk channels are tetramers comprising combinations of subunits (girk1-4), activated by direct binding of the gβγ subunit of gi/o proteins. heterologously expressed girk1/2 exhibit high, gβγ-dependent basal currents (ibasal) and a modest activation by gpcr or coexpressed gβγ. inversely, the girk2 homotetramers ... | 2014 | 25384780 |
| the virtual xenbase: transitioning an online bioinformatics resource to a private cloud. | as a model organism database, xenbase has been providing informatics and genomic data on xenopus (silurana) tropicalis and xenopus laevis frogs for more than a decade. the xenbase database contains curated, as well as community-contributed and automatically harvested literature, gene and genomic data. a gbrowse genome browser, a blast+ server and stock center support are available on the site. when this resource was first built, all software services and components in xenbase ran on a single phy ... | 2014 | 25380782 |
| flow sensing in developing xenopus laevis is disrupted by visual cues and ototoxin exposure. | we explored how lateral line cues interact with visual cues to mediate flow sensing behaviors in the nocturnal developing frog, xenopus laevis, by exposing animals to current flows under different lighting conditions and after exposure to the ototoxin gentamicin. under dark conditions, xenopus tadpoles move downstream at the onset of current flow, then turn, and orient toward the direction of the flow with high accuracy. postmetamorphic froglets also exhibit positive rheotaxis but with less accu ... | 2015 | 25380559 |
| nucleotide bound to rab11a controls localization in rod cells but not interaction with rhodopsin. | precise vectorial transport of rhodopsin is essential for rod photoreceptor health and function. mutations that truncate or extend the c terminus of rhodopsin disrupt this transport, and lead to retinal degeneration and blindness in human patients and in mouse models. here we show that such mutations disrupt the binding of rhodopsin to the small gtpase rab11a. the rhodopsin-rab11a interaction is a direct binding interaction that does not depend on the nucleotide binding state of rab11a. expressi ... | 2014 | 25378153 |
| spak dependent regulation of peptide transporters pept1 and pept2. | spak (ste20-related proline/alanine-rich kinase) is a powerful regulator of renal tubular ion transport and blood pressure. moreover, spak contributes to the regulation of cell volume. little is known, however, about a role of spak in the regulation or organic solutes. the present study thus addressed the influence of spak on the peptide transporters pept1 and pept2. | 2014 | 25376088 |
| optogenetic control of apoptosis in targeted tissues of xenopus laevis embryos. | killerred (kr) is a recently discovered fluorescent protein that, when activated with green light, releases reactive oxygen species (ros) into the cytoplasm, triggering apoptosis in a kr-expressing cell. this property allows for the use of kr as a means of killing cells in an organism with great temporal and spatial specificity, while minimizing the nonspecific effects that can result from mechanical or chemical exposure damage techniques. such optogenetic control of cell death, and the resultin ... | 2014 | 25374461 |
| histone methyltransferase dot1l plays a role in postembryonic development in xenopus tropicalis. | histone methylations have been implicated to play important roles in diverse cellular processes. of particular interest is the methylation of histone h3k79, which is catalyzed by an evolutionarily conserved methyltransferase, disruptor of telomeric silencing (dot1)-like (dot1l). to investigate the role of dot1l during vertebrate development, we have generated a dot1l-specific transcription activator-like effector nuclease (talen) nuclease to knockdown endogenous dot1l in xenopus tropicalis, a di ... | 2015 | 25366346 |
| an adhesome comprising laminin, dystroglycan and myosin iia is required during notochord development in xenopus laevis. | dystroglycan (dg) is a transmembrane receptor for laminin that must be expressed at the right time and place in order to be involved in notochord morphogenesis. the function of dg was examined in xenopus laevis embryos by knockdown of dg and overexpression and replacement of the endogenous dg with a mutated form of the protein. this analysis revealed that dg is required for correct laminin assembly, for cell polarization during mediolateral intercalation and for proper differentiation of vacuole ... | 2014 | 25359726 |
| transporters involved in renal excretion of n-carbamoylglutamate, an orphan drug to treat inborn n-acetylglutamate synthase deficiency. | inborn defects in n-acetylglutamate (nag) synthase (nags) cause a reduction of nag, an essential cofactor for the initiation of the urea cycle. as a consequence, blood ammonium concentrations are elevated, leading to severe neurological disorders. the orphan drug n-carbamoylglutamate (ncg; carbaglu), efficiently overcomes nags deficiency. however, not much is known about the transporters involved in the uptake, distribution, and elimination of the divalent organic anion ncg. organic anion-transp ... | 2014 | 25354943 |
| two different vestigial like 4 genes are differentially expressed during xenopus laevis development. | the vestigial gene (vg) was first characterized in drosophila and several homologues were identified in vertebrates and called vestigial like 1-4 (vgll1-4). vgll proteins interact with the transcription factors tef-1 and mef-2 through a conserved region called tondu (tdu). vgll4s are characterized by two tandem tdu domains which differentiate them from other members of the vestigial family. in xenopus two genes were identified as vgll4. our bioinformatic analysis demonstrated that these two gene ... | 2014 | 25354458 |
| differential expression of arid5b isoforms in xenopus laevis pronephros. | arid5b belongs to the arid family of transcription factors characterised by a helix-turn-helix motif- based dna-binding domain called arid (a-t rich interaction domain). in human, alternative splicing leads to long and short isoforms (isoform1 and 2, respectively) which differ in their n-terminal part. in this study, we report the cloning and expression pattern of xenopus laevis arid5b. we have isolated a full length cdna that shows homology with the human arid5b isoform1. furthermore, 5'race ex ... | 2014 | 25354457 |
| lack of negatively charged residues at the external mouth of kir2.2 channels enable the voltage-dependent block by external mg2+. | kir channels display voltage-dependent block by cytosolic cations such as mg2+ and polyamines that causes inward rectification. in fact, cations can regulate k channel activity from both the extracellular and intracellular sides. previous studies have provided insight into the up-regulation of kir channel activity by extracellular k+ concentration. in contrast, extracellular mg2+ has been found to reduce the amplitude of the single-channel current at milimolar concentrations. however, little is ... | 2014 | 25350118 |
| sulfonylureas suppress the stimulatory action of mg-nucleotides on kir6.2/sur1 but not kir6.2/sur2a katp channels: a mechanistic study. | sulfonylureas, which stimulate insulin secretion from pancreatic β-cells, are widely used to treat both type 2 diabetes and neonatal diabetes. these drugs mediate their effects by binding to the sulfonylurea receptor subunit (sur) of the atp-sensitive k(+) (katp) channel and inducing channel closure. the mechanism of channel inhibition is unusually complex. first, sulfonylureas act as partial antagonists of channel activity, and second, their effect is modulated by mgadp. we analyzed the molecul ... | 2014 | 25348414 |
| cell volume changes regulate slick (slo2.1), but not slack (slo2.2) k+ channels. | slick (slo2.1) and slack (slo2.2) channels belong to the family of high-conductance k+ channels and have been found widely distributed in the cns. both channels are activated by na+ and cl- and, in addition, slick channels are regulated by atp. therefore, the roles of these channels in regulation of cell excitability as well as ion transport processes, like regulation of cell volume, have been hypothesized. it is the aim of this work to evaluate the sensitivity of slick and slack channels to sma ... | 2014 | 25347289 |
| polyubiquitylation drives replisome disassembly at the termination of dna replication. | resolution of replication forks during termination of dna replication is essential for accurate duplication of eukaryotic genomes. here we present evidence consistent with the idea that polyubiquitylation of a replisome component (mcm7) leads to its disassembly at the converging terminating forks because of the action of the p97/vcp/cdc48 protein remodeler. using xenopus laevis egg extract, we have shown that blocking polyubiquitylation results in the prolonged association of the active helicase ... | 2014 | 25342805 |
| different solvent fractions of acanthopanax senticosus harms exert antioxidant and anti-inflammatory activities and inhibit the human kv1.3 channel. | the potential antioxidant and anti-inflammatory activities of acanthopanax senticosus harms were evaluated and its effect on the human kv1.3 potassium channel was detected. the ethyl acetate fraction possessed the highest phenolic (289.19±7.43 mg tannic acid equivalents/g) and flavonoid (10.80±0.67 mg quercetin equivalents/g) contents and exhibited stronger antioxidant effects than other fractions in most of the antioxidant assays. on the other hand, the dichloromethane (ch(2)cl(2)) fraction sho ... | 2015 | 25340513 |
| vitamin supplementation by gut symbionts ensures metabolic homeostasis in an insect host. | despite the demonstrated functional importance of gut microbes, our understanding of how animals regulate their metabolism in response to nutritionally beneficial symbionts remains limited. here, we elucidate the functional importance of the african cotton stainer's (dysdercus fasciatus) association with two actinobacterial gut symbionts and subsequently examine the insect's transcriptional response following symbiont elimination. in line with bioassays demonstrating the symbionts' contribution ... | 2014 | 25339726 |
| gd(iii)-pymta label is suitable for in-cell epr. | distance measurement in the nanometer range by electron paramagnetic resonance spectroscopy (epr) in combination with site-directed spin labeling is a very powerful tool to monitor the structure and dynamics of biomacromolecules in their natural environment. however, in-cell application is hampered by the short lifetime of the commonly used nitroxide spin labels in the reducing milieu inside a cell. here, we demonstrate that the gd(iii) based spin label gd-pymta is suitable for in-cell epr. gd-p ... | 2014 | 25325832 |
| regulation of clc-2 activity by spak and osr1. | spak (sps1-related proline/alanine-rich kinase) and osr1 (oxidative stress-responsive kinase 1) are powerful regulators of diverse transport processes. both kinases are activated by cell shrinkage and participate in stimulation of regulatory cell volume increase (rvi). execution of rvi involves inhibition of cl- channels. the present study explored whether spak and/or osr1 regulate the activity of the cl- channel clc-2. | 2014 | 25323061 |
| calcium signaling and meiotic exit at fertilization in xenopus egg. | calcium is a universal messenger that mediates egg activation at fertilization in all sexually reproducing species studied. however, signaling pathways leading to calcium generation and the mechanisms of calcium-induced exit from meiotic arrest vary substantially among species. here, we review the pathways of calcium signaling and the mechanisms of meiotic exit at fertilization in the eggs of the established developmental model, african clawed frog, xenopus laevis. we also discuss calcium involv ... | 2014 | 25322156 |
| comparative genomic and expression analysis of the adenosine signaling pathway members in xenopus. | adenosine is an endogenous molecule that regulates many physiological processes via the activation of four specific g-protein-coupled adora receptors. extracellular adenosine may originate either from the hydrolysis of released atp by the ectonucleotidases or from cellular exit via the equilibrative nucleoside transporters (slc29a). adenosine extracellular concentration is also regulated by its successive hydrolysis into uric acid by membrane-bound enzymes or by cell influx via the concentrative ... | 2015 | 25319637 |
| xenbase, the xenopus model organism database; new virtualized system, data types and genomes. | xenbase (http://www.xenbase.org), the xenopus frog model organism database, integrates a wide variety of data from this biomedical model genus. two closely related species are represented: the allotetraploid xenopus laevis that is widely used for microinjection and tissue explant-based protocols, and the diploid xenopus tropicalis which is used for genetics and gene targeting. the two species are extremely similar and protocols, reagents and results from each species are often interchangeable. x ... | 2015 | 25313157 |
| twin xenopus laevis embryos appearing from flattened eggs. | remarkable progress has recently been made in molecular biology of double axis formation in xenopus laevis. leaving aside, for the time being, the problem of the gene expressions regulating xenopus laevis development, here i show that pulse treatment could induce formation of a secondary axis in a fertilized xenopus laevis egg. at 3 min after insemination, metal oxides were added to xenopus fertilized eggs, and then twin embryos appeared. zirconium oxide (zro2) was the most effective metal oxide ... | 2014 | 25311141 |
| phosphorylation and arginine methylation mark histone h2a prior to deposition during xenopus laevis development. | stored, soluble histones in eggs are essential for early development, in particular during the maternally controlled early cell cycles in the absence of transcription. histone post-translational modifications (ptms) direct and regulate chromatin-templated transactions, so understanding the nature and function of pre-deposition maternal histones is essential to deciphering mechanisms of regulation of development, chromatin assembly, and transcription. little is known about histone h2a pre-deposit ... | 2014 | 25302076 |
| glycine transporters glyt1 and glyt2 are differentially modulated by glycogen synthase kinase 3β. | inhibitory glycinergic neurotransmission is terminated by the specific glycine transporters glyt1 and glyt2 which actively reuptake glycine from the synaptic cleft. glyt1 is associated with both glycinergic and glutamatergic pathways, and is the main regulator of the glycine levels in the synapses. glyt2 is the main supplier of glycine for vesicle refilling, a process that is vital to preserve the quantal glycine content in synaptic vesicles. therefore, to control glycinergic neurotransmission e ... | 2015 | 25301276 |
| cd44 functions in wnt signaling by regulating lrp6 localization and activation. | wnt reception at the membrane is complex and not fully understood. cd44 is a major wnt target gene in the intestine and is essential for wnt-induced tumor progression in colorectal cancer. here we show that cd44 acts as a positive regulator of the wnt receptor complex. downregulation of cd44 expression decreases, whereas cd44 overexpression increases wnt activity in a concentration-dependent manner. epistasis experiments place cd44 function at the level of the wnt receptor lrp6. mechanistically, ... | 2015 | 25301071 |
| the need of mmp-2 on the sperm surface for xenopus fertilization: its role in a fast electrical block to polyspermy. | monospermic fertilization in the frog, xenopus laevis, is ensured by a fast-rising, positive fertilization potential to prevent polyspermy on the fertilized egg, followed by a slow block with the formation of a fertilization envelope over the egg surface. in this paper, we found that not only the enzymatic activity of sperm matrix metalloproteinase-2 (mmp-2) was necessary for a sperm to bind and/or pass through the extracellular coat of vitelline envelope, but also the hemopexin (hpx) domain of ... | 2014 | 25296387 |
| correlative light and electron microscopy for a free-floating spindle in xenopus laevis egg extracts. | cryoimmobilization is an optimal method of preserving sample ultrastructure in electron microscopy studies. however, cryoimmobilization is limited to thin samples and this limitation may necessitate the isolation of the structure of interest. for cellular structures that are found in low number, or only during certain phases of the cell cycle, an added benefit of isolation is the possibility to concentrate the structures. we developed a method to perform correlative light and electron microscopy ... | 2014 | 25287839 |
| analysis of nuclear reprogramming following nuclear transfer to xenopus oocyte. | germinal vesicle of stage v-vi xenopus laevis oocytes (at the prophase i stage of meiosis) can be used to transplant mammalian nuclei. in this type of interspecies nuclear transfer no cell division occurs and no new cell types are generated. however, the transplanted nuclei undergo extensive transcriptional reprogramming. here, it is first explained how to carry out transplantation of multiple mammalian cell nuclei to xenopus oocytes. it is then described how to perform rt-qpcr, western blot, ch ... | 2015 | 25287339 |
| the calcium-dependent ribonuclease xendou promotes er network formation through local rna degradation. | how cells shape and remodel organelles in response to cellular signals is a poorly understood process. using xenopus laevis egg extract, we found that increases in cytosolic calcium lead to the activation of an endogenous ribonuclease, xendou. a fraction of xendou localizes to the endoplasmic reticulum (er) and is required for nuclear envelope assembly and er network formation in a catalysis-dependent manner. using a purified vesicle fusion assay, we show that xendou functions on the surface of ... | 2014 | 25287301 |
| expression, purification, and structural insights for the human uric acid transporter, glut9, using the xenopus laevis oocytes system. | the urate transporter, glut9, is responsible for the basolateral transport of urate in the proximal tubule of human kidneys and in the placenta, playing a central role in uric acid homeostasis. glut9 shares the least homology with other members of the glucose transporter family, especially with the glucose transporting members glut1-4 and is the only member of the glut family to transport urate. the recently published high-resolution structure of xyle, a bacterial d-xylose transporting homologue ... | 2014 | 25286413 |
| evolutionarily conserved role for soxc genes in neural crest specification and neuronal differentiation. | members of the sox family of transcription factors play a variety of critical developmental roles in both vertebrates and invertebrates. whereas soxbs and soxes are involved in neural and neural crest development, respectively, far less is known about members of the soxc subfamily. to address this from an evolutionary perspective, we compare expression and function of soxc genes in neural crest cells and their derivatives in lamprey (petromyzon marinus), a basal vertebrate, to frog (xenopus laev ... | 2015 | 25286121 |
| nkx2.5 is involved in myeloid cell differentiation at anterior ventral blood islands in the xenopus embryo. | we have shown previously that two populations of myeloid cells emerge in the anterior and posterior ventral blood islands (avbi and pvbi) at the different stages in xenopus laevis embryo. in order to elucidate the regulatory mechanism of myeloid cell differentiation in the avbi, we examined the role of nkx2.5, an essential transcription factor for heart differentiation, in regulation of the myeloid cell differentiation in this region. knockdown of endogenous nkx2.5 by introducing mo into the dor ... | 2014 | 25283688 |
| liquid chromatography tandem mass spectrometry method using solid-phase extraction and bead-beating-assisted matrix solid-phase dispersion to quantify the fungicide tebuconazole in controlled frog exposure study: analysis of water and animal tissue. | this paper presents the development, optimization, and validation of a lc-ms/ms methodology to determine the concentration of the antifungal drug and fungicide tebuconazole in a controlled exposure study of african clawed frogs (xenopus laevis). the method is validated on animal tank water and on tissue from exposed and non-exposed adult x. laevis. using solid-phase extraction (spe), the analytical method allows for quantification of tebuconazole at concentrations as low as 3.89 pg ml(-1) in 10 ... | 2014 | 25277103 |
| atomic force microscopy on plasma membranes from xenopus laevis oocytes containing human aquaporin 4. | atomic force microscopy (afm) is a unique tool for imaging membrane proteins in near-native environment (embedded in a membrane and in buffer solution) at ~1 nm spatial resolution. it has been most successful on membrane proteins reconstituted in 2d crystals and on some specialized and densely packed native membranes. here, we report on afm imaging of purified plasma membranes from xenopus laevis oocytes, a commonly used system for the heterologous expression of membrane proteins. isoform m23 of ... | 2014 | 25277091 |
| photoactivation-induced instability of rhodopsin mutants t4k and t17m in rod outer segments underlies retinal degeneration in x. laevis transgenic models of retinitis pigmentosa. | retinitis pigmentosa (rp) is an inherited neurodegenerative disease involving progressive vision loss, and is often linked to mutations in the rhodopsin gene. mutations that abolish n-terminal glycosylation of rhodopsin (t4k and t17m) cause sector rp in which the inferior retina preferentially degenerates, possibly due to greater light exposure of this region. transgenic animal models expressing rhodopsin glycosylation mutants also exhibit light exacerbated retinal degeneration (rd). in this stu ... | 2014 | 25274813 |
| getting to know your neighbor: cell polarization in early embryos. | polarization of early embryos along cell contact patterns--referred to in this paper as radial polarization--provides a foundation for the initial cell fate decisions and morphogenetic movements of embryogenesis. although polarity can be established through distinct upstream mechanisms in caenorhabditis elegans, xenopus laevis, and mouse embryos, in each species, it results in the restriction of par polarity proteins to contact-free surfaces of blastomeres. in turn, par proteins influence cell f ... | 2014 | 25267293 |