| x-ray phase-contrast in vivo microtomography probes new aspects of xenopus gastrulation. | an ambitious goal in biology is to understand the behaviour of cells during development by imaging-in vivo and with subcellular resolution-changes of the embryonic structure. important morphogenetic movements occur throughout embryogenesis, but in particular during gastrulation when a series of dramatic, coordinated cell movements drives the reorganization of a simple ball or sheet of cells into a complex multi-layered organism. in xenopus laevis, the south african clawed frog and also in zebraf ... | 2013 | 23676755 |
| herbivory of maize by southern corn rootworm induces expression of the major intrinsic protein zmnip1;1 and leads to the discovery of a novel aquaporin zmpip2;8. | aquaporins channel water and other neutral molecules through cell membranes. aquaporin gene expression is subject to transcriptional control and can be modulated by factors affecting water balance such as salt, abscisic acid and drought. during infestation of maize by southern corn rootworm (scr), an insect that chews into and significantly damages maize roots, three maize aquaporins were differentially expressed upon prolonged infestation. using a brief infestation of maize roots zmnip1;1 trans ... | 2013 | 23673351 |
| a large pseudoautosomal region on the sex chromosomes of the frog silurana tropicalis. | sex chromosome divergence has been documented across phylogenetically diverse species, with amphibians typically having cytologically nondiverged ("homomorphic") sex chromosomes. with an aim of further characterizing sex chromosome divergence of an amphibian, we used "rad-tags" and sanger sequencing to examine sex specificity and heterozygosity in the western clawed frog silurana tropicalis (also known as xenopus tropicalis). our findings based on approximately 20 million genotype calls and appr ... | 2013 | 23666865 |
| postnatal regulation of x,k-atpases in rat skin and conserved lateroapical polarization of na,k-atpase in vertebrate epidermis. | development of epidermis creates stratified epithelium with different sets of ion-transporting enzymes in its layers. we have characterized expression of na,k- and h,k-atpase α and β subunits and fxyd isoforms in rat skin. maturation of rat skin from newborn to adult is associated with an increase in fxyd4 and a decrease of na,k-atpase α1-isoform, atp1b4 and fxyd6 transcripts. na,k-atpase of rat epidermis is represented predominantly by α1 and β3 isoforms. keratinization is associated with the l ... | 2013 | 23651441 |
| kinetic analyses of trans-1-amino-3-[18f]fluorocyclobutanecarboxylic acid transport in xenopus laevis oocytes expressing human asct2 and snat2. | trans-1-amino-3-[(18)f]fluorocyclobutanecarboxylic acid (anti-[(18)f]facbc) is a promising amino acid positron emission tomography (pet) radiotracer for visualizing prostate cancer. we previously showed that anti-facbc is transported by amino acid transporters, especially by alanine-serine-cysteine transporter 2 (asct2), which is associated with tumor growth. we studied this affinity to assess the mechanism of anti-facbc transport in prostate cancer cells. | 2013 | 23647854 |
| genomic dynamics of transposable elements in the western clawed frog (silurana tropicalis). | transposable elements (tes) are repetitive dna sequences that can make new copies of themselves that are inserted elsewhere in a host genome. the abundance and distributions of tes vary considerably among phylogenetically diverse hosts. with the aim of exploring the basis of this variation, we evaluated correlations between several genomic variables and the presence of tes and non-te repeats in the complete genome sequence of the western clawed frog (silurana tropicalis). this analysis reveals p ... | 2013 | 23645600 |
| skin wound healing in different aged xenopus laevis. | xenopus froglets can perfectly heal skin wounds without scarring. to explore whether this capacity is maintained as development proceeds, we examined the cellular responses during the repair of skin injury in 8- and 15-month-old xenopus laevis. the morphology and sequence of healing phases (i.e., inflammation, new tissue formation, and remodeling) were independent of age, while the timing was delayed in older frogs. at the beginning of postinjury, wound re-epithelialization occurred in form of a ... | 2013 | 23640793 |
| quantification and localization of erythropoietin-receptor-expressing cells in the liver of xenopus laevis. | erythropoiesis occurs in the african clawed frog, xenopus laevis and is mediated by erythropoietin (xlepo), a primary regulator of this process. previously, we have shown that the xlepo receptor (xlepor), which is expressed by erythroid progenitors that respond to xlepo, is found predominantly in the liver. the aim of the present study was to determine the dynamics of erythropoiesis in the livers of normal and anemic x. laevis by identifying the number and precise location of mature and immature ... | 2013 | 23640133 |
| fibre-selective recording from the peripheral nerves of frogs using a multi-electrode cuff. | we investigate the ability of the method of velocity selective recording (vsr) to determine the fibre types that contribute to a compound action potential (cap) propagating along a peripheral nerve. real-time identification of the active fibre types by determining the direction of action potential propagation (afferent or efferent) and velocity might allow future neural prostheses to make better use of biological sensor signals and provide a new and simple tool for use in fundamental neuroscienc ... | 2013 | 23640008 |
| gene expression responses for detecting sublethal effects of xenobiotics and whole effluents on a xenopus laevis embryo assay. | in the present study, the authors investigated the effects of bisphenol a, chlorpyrifos, methylparaben, and 2 effluent samples from wastewater treatment plants located in the province of madrid, spain, on the messenger rna expression of specific genes involved in early development (esr1, pax6, bmp4, and myf5) and a gene involved in the general stress response (hsp70) during xenopus laevis embryo development. gene expression was analyzed after 4 h, 24 h, and 96 h of exposure by semiquantitative r ... | 2013 | 23637088 |
| synthesis and structure activity relationship of tetrahydroisoquinoline-based potentiators of glun2c and glun2d containing n-methyl-d-aspartate receptors. | we describe here the synthesis and evaluation of a series of tetrahydroisoquinolines that show subunit-selective potentiation of nmda receptors containing the glun2c or glun2d subunits. bischler-napieralski conditions were employed in the key step for the conversion of acyclic amides to the corresponding tetrahydroisoquinoline-containing analogs. compounds were evaluated using both two-electrode voltage clamp recordings from xenopus laevis oocytes and imaging of mammalian bhk cells loaded with c ... | 2013 | 23627311 |
| localisation of rnas into the germ plasm of vitellogenic xenopus oocytes. | we have studied the localisation of mrnas in full-grown xenopus laevis oocytes by injecting fluorescent rnas, followed by confocal microscopy of the oocyte cortex. concentrating on rna encoding the xenopus nanos homologue, nanos1 (formerly xcat2), we find that it consistently localised into aggregated germ plasm ribonucleoprotein (rnp) particles, independently of cytoskeletal integrity. this implies that a diffusion/entrapment-mediated mechanism is active, as previously reported for previtelloge ... | 2013 | 23626739 |
| quantification of total thyroxine in plasma from xenopus laevis. | there is evidence that the endocrine systems of certain fish and wildlife can be affected by chemical contaminants, possibly resulting in developmental and reproductive problems. perturbations in the hypothalamus-pituitary-thyroid (hpt) axis, in particular, can be detrimental during early development. because the rate of amphibian metamorphosis is controlled by circulating thyroid hormones, tadpoles undergoing metamorphosis have been selected as relevant test organisms for evaluating the potenti ... | 2013 | 23625702 |
| the cdk1-apc/c cell cycle oscillator circuit functions as a time-delayed, ultrasensitive switch. | despite the complexity and variety of biological oscillators, their core design invariably includes an essential negative feedback loop. in the xenopus laevis embryonic cell cycle oscillator, this loop consists of the kinase cyclin b-cdk1 and the ubiquitin ligase apc/c(cdc20); active cdk1 activates apc/c(cdc20), which then brings about cyclin b degradation and inactivates cdk1. here we ask how this negative feedback loop functions quantitatively, with the aim of understanding what mechanisms kee ... | 2013 | 23624406 |
| cutaneous nitrogen excretion in the african clawed frog xenopus laevis: effects of high environmental ammonia (hea). | ammonia is a highly toxic molecule and often introduced in considerable amounts into aquatic environments due to anthropogenic activities. many aquatic and semi-aquatic amphibians utilize, in addition to their kidneys, the skin for osmoregulation and nitrogen excretion. in the present study the effects of prolonged (7-21 days) exposure to high environmental ammonia (hea, 1 mmol l(-1) nh4cl) on cutaneous nitrogen excretion and gene expression of key-transporters involved in nitrogen excretion and ... | 2013 | 23624175 |
| pfkfb (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase) isoforms display a tissue-specific and dynamic expression during xenopus laevis development. | pfkfb (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase) enzymes are bi-functional enzymes encoded by four different genes (pfkfb1, pfkfb2, pfkfb3, pfkfb4) in vertebrates. they are involved in the regulation of glycolysis: they catalyze the synthesis and the degradation of f-2,6-bp (fructose-2,6-bisphosphate), the most potent allosteric activator of phosphofructokinase 1 (pfk1), a key glycolytic enzyme. by producing f-2,6-bp, pfkfb enzymes allow glycolysis to proceed, while by degrading f-2, ... | 2013 | 23623824 |
| female hormone release of microencapsulated xenopus laevis ovarian cells. | cell microencapsulation has potential for the treatment of endocrine diseases. this study aims to probe the feasibility of xenopus laevis as an animal model for cell microencapsulation and transplantation and to evaluate the female hormone release of microencapsulated x. laevis ovarian cells. the cells were harvested, cultured and microencapsulated into alginate-chitosan-alginate microcapsules with an electrostatic generator. the estradiol and progesterone releases of the microencapsulated x. la ... | 2013 | 23623793 |
| gabaa receptor modulation by piperine and a non-trpv1 activating derivative. | the action of piperine (the pungent component of pepper) and its derivative sct-66 ((2e,4e)-5-(1,3-benzodioxol-5-yl))-n,n-diisobutyl-2,4-pentadienamide) on different gamma-aminobutyric acid (gaba) type a (gaba(a)) receptors, transient-receptor-potential-vanilloid-1 (trpv1) receptors and behavioural effects were investigated. gaba(a) receptor subtypes and trpv1 receptors were expressed in xenopus laevis oocytes. modulation of gaba-induced chloride currents (i(gaba)) by piperine and sct-66 and act ... | 2013 | 23623790 |
| abcb1 single nucleotide polymorphisms (1236c>t, 2677g>t, and 3435c>t) do not affect transport activity of human p-glycoprotein. | p-glycoprotein (p-gp) is a multidrug efflux transporter that has a defined role in the absorption and disposition of drugs. many studies have investigated the potential influence of abcb1 polymorphisms on the disposition of its substrates. however, there remains significant controversy regarding the role of these polymorphisms. our aim was to generate a p-gp expression system for single nucleotide polymorphisms (snps) and the reference sequence to assess the functional significance of these vari ... | 2013 | 23619510 |
| ser 15 of wee1b is a potential pka phosphorylation target in g2/m transition in one-cell stage mouse embryos. | the wee1 kinase family has been shown to be the major kinase family responsible for phosphorylating tyr 15 on cyclin-dependent kinase 1 (cdk1). wee1 homolog 2 (wee2, also known as wee1b) was first identified in xenopus laevis and more recently in humans and mice, and is responsible for phosphorylating the cdk1 inhibitory site and maintaining meiotic arrest in oocytes. however, the mechanism by which wee1b is regulated in one-cell stage mouse embryos remains to be elucidated. in the present study ... | 2013 | 23616086 |
| activation of adf/cofilin by phosphorylation-regulated slingshot phosphatase is required for the meiotic spindle assembly in xenopus laevis oocytes. | we identify xenopus adf/cofilin (xac) and its activator, slingshot phosphatase (xssh), as key regulators of actin dynamics essential for spindle microtubule assembly during xenopus oocyte maturation. phosphorylation of xssh at multiple sites within the tail domain occurs just after germinal vesicle breakdown (gvbd) and is accompanied by dephosphorylation of xac, which was mostly phosphorylated in immature oocytes. this xac dephosphorylation after gvbd is completely suppressed by latrunculin b, a ... | 2013 | 23615437 |
| pain perception and anaesthesia in research frogs. | frogs possess pain receptors and pathways that support processing and perception of noxious stimuli however the level of organization is less well structured compared to mammals. it was long believed that the experience of pain was limited to 'higher' phylums of the animal kingdom. however, it is now commonly accepted that amphibians possess neuro-anatomical pathways conductive of a complete nociceptive experience. xenopus laevis frogs have been one of the most popular aquatic research models fo ... | 2013 | 23615302 |
| ancestral amphibian v2rs are expressed in the main olfactory epithelium. | mammalian olfactory receptor families are segregated into different olfactory organs, with type 2 vomeronasal receptor (v2r) genes expressed in a basal layer of the vomeronasal epithelium. in contrast, teleost fish v2r genes are intermingled with all other olfactory receptor genes in a single sensory surface. we report here that, strikingly different from both lineages, the v2r gene family of the amphibian xenopus laevis is expressed in the main olfactory as well as the vomeronasal epithelium. i ... | 2013 | 23613591 |
| proteolysis of xenopus cip-type cdk inhibitor, p16xic2, is regulated by pcna binding and cdk2 phosphorylation. | cell division is positively regulated by cyclin-dependent kinases (cdks) partnered with cyclins and negatively regulated by cdk inhibitors. in the frog, xenopus laevis, three types of cdk inhibitors have been described: p27xic1 (xic1) which shares sequence homology with both p21cip1 and p27kip1 from mammals, p16xic2 (xic2) which shares sequence homology with p21cip1, and p17xic3 (xic3) which shares sequence homology with p27kip1. while past studies have demonstrated that during dna polymerase sw ... | 2013 | 23607668 |
| new insights in endogenous modulation of ligand-gated ion channels: histamine is an inverse agonist at strychnine sensitive glycine receptors. | histamine is involved in many physiological functions in the periphery and is an important neurotransmitter in the brain. it acts on metabotropic h1-h4 receptors mediating vasodilatation, bronchoconstriction and stimulation of gastric acid secretion. in the brain histamine is produced by neurons in the tuberomamillary nucleus (tmn), which controls arousal. histamine is also a positive modulator of the inhibitory cys-loop ligand-gated ion channel gabaa. we investigated now its effect on the secon ... | 2013 | 23603522 |
| towards a humanized pparγ reporter system for in vivo screening of obesogens. | overeating and lack of exercise are major contributors to the current obesity epidemic, but environmental contaminants, or obesogens, are also considered to be potential actors. a common obesogen target is the peroxisome proliferator activated receptor gamma (pparγ). screening for exogenous obesogens requires in vivo systems as many xenobiotics exert their effects through metabolites. we thus developed a humanized in vivo pparγ reporter model, using xenopus laevis larvae, a species possessing me ... | 2013 | 23603401 |
| progesterone increases the activity of glutamate transporter type 3 expressed in xenopus oocytes. | progesterone is an important sex hormone for pregnancy and also has neuroprotective and anticonvulsant effects. it is well-known that full-term parturients become more susceptible to volatile anesthetics. glutamate transporters are important for preventing neurotoxicity and anesthetic action in the central nervous system. we investigated the effects of progesterone on the activity of glutamate transporter type 3 (eaat3), the major neuronal eaat. eaat3 was expressed in xenopus laevis oocytes by i ... | 2013 | 23602688 |
| the monomeric state of the proton-coupled folate transporter represents the functional unit in the plasma membrane. | folic acid is an essential vitamin required for de novo biosynthesis of nucleotides and amino acids. the proton-coupled folate transporter (pcft; slc46a1) has been identified as the major contributor for intestinal folate uptake. it is also involved in folate transport across the blood-brain barrier and into solid tumors. pcft belongs to the major facilitator superfamily. major facilitator superfamily members can exist in either monomeric or homo-oligomeric form. here, we utilized blue native po ... | 2013 | 23601781 |
| dysfunction of the heteromeric kv7.3/kv7.5 potassium channel is associated with autism spectrum disorders. | heterozygous mutations in the kcnq3 gene on chromosome 8q24 encoding the voltage-gated potassium channel kv7.3 subunit have previously been associated with rolandic epilepsy and idiopathic generalized epilepsy (ige) including benign neonatal convulsions. we identified a de novo t(3;8) (q21;q24) translocation truncating kcnq3 in a boy with childhood autism. in addition, we identified a c.1720c > t [p.p574s] nucleotide change in three unrelated individuals with childhood autism and no history of c ... | 2013 | 23596459 |
| a trafficking-deficient mutant of kcc3 reveals dominant-negative effects on k-cl cotransport function. | the k-cl cotransporter (kcc) functions in maintaining chloride and volume homeostasis in a variety of cells. in the process of cloning the mouse kcc3 cdna, we came across a cloning mutation (e289g) that rendered the cotransporter inactive in functional assays in xenopus laevis oocytes. through biochemical studies, we demonstrate that the mutant e289g cotransporter is glycosylation-deficient, does not move beyond the endoplasmic reticulum or the early golgi, and thus fails to reach the plasma mem ... | 2013 | 23593405 |
| the dimeric mcm8-9 complex of xenopus laevis likely has a conserved function for resistance to dna damage. | | 2013 | 23588076 |
| expression of xsdf-1α, xcxcr4, and xcxcr7 during gastrulation in xenopus laevis. | chemokines play a crucial role in developmental processes and recent studies have revealed that they also control gastrulation movements. in this paper, we report the expression patterns of xsdf-1α, xcxcr4 and xcxcr7 and regulation of the expression of xsdf-1α and xcxcr4 during gastrulation. we performed whole mount in situ hybridization (wish) and quantitative real-time rt-pcr (qrt-pcr) analyses to examine the distribution of transcripts. the effect of activin/nodal signaling on the expression ... | 2013 | 23585357 |
| characterization of cxc-type chemokine molecules in early xenopus laevis development. | chemokine molecules play important roles in the immune system. however, several chemokine molecules are expressed during early development before the immune system is established. using reverse transcriptionpolymerase chain reaction (rt-pcr) and overexpression of chemokine molecules, we identified and characterized xenopus laevis cxc-type chemokine ligands (xcxcl13l1, xcxcl13l2, xcxcla, xcxclb, xcxcld, and xcxcle) and receptors (xcxcr1/2, xcxcr3, xcxcr5, xcxcr6, and xcxcra) during early develop ... | 2013 | 23585351 |
| functional assay of mammalian and insect olfactory receptors using xenopus oocytes. | the large number of olfactory receptors (ors) expressed by various mammalian and insect species, as well as the large number of potential odorant ligands, has made the pairing of odorants with receptors -(de-orphaning) exceedingly difficult. these efforts are further complicated by difficulties in expressing ors in many standard expression systems. xenopus laevis oocytes offer a versatile expression platform for the de-orphaning and functional characterization of ors. two-electrode voltage clamp ... | 2013 | 23585043 |
| an intrinsic crf signaling system within the optic tectum. | previous work indicates that crf administration inhibits visually guided feeding in amphibians. we used the african clawed frog xenopus laevis to examine the hypothesis that crf acts as a neurotransmitter in the optic tectum, the major brain area integrating the visual and premotor pathways regulating visually guided feeding in anurans. reverse transcriptase pcr revealed that cells in the optic tectum express mrna for crf and the crf r1 receptor but not the crf r2 receptor. radioligand binding s ... | 2013 | 23583471 |
| xenopus oocyte meiosis lacks spindle assembly checkpoint control. | the spindle assembly checkpoint (sac) functions as a surveillance mechanism to detect chromosome misalignment and to delay anaphase until the errors are corrected. the sac is thought to control mitosis and meiosis, including meiosis in mammalian eggs. however, it remains unknown if meiosis in the eggs of nonmammalian vertebrate species is also regulated by sac. using a novel karyotyping technique, we demonstrate that complete disruption of spindle microtubules in xenopus laevis oocytes did not a ... | 2013 | 23569212 |
| tissue distribution of enrofloxacin in african clawed frogs (xenopus laevis) after intramuscular and subcutaneous administration. | as part of an enrofloxacin pharmacokinetic study, concentrations of enrofloxacin and ciprofloxacin (metabolite) were measured in various tissues (brain, heart, kidney, liver, lung, and spleen) collected from treated (subcutaneous delivery, n = 3; intramuscular delivery, n = 3; untreated controls, n = 2) adult female xenopus laevis by using hplc. enrofloxacin was rapidly absorbed after administration by either route and readily diffused into all sampled tissues. enrofloxacin and ciprofloxacin wer ... | 2013 | 23562103 |
| intestinal absorption mechanism of mirabegron, a potent and selective β₃-adrenoceptor agonist: involvement of human efflux and/or influx transport systems. | mirabegron, a weak-basic compound, is a potent and selective β3-adrenoceptor agonist for the treatment of overactive bladder. mirabegron extended release formulation shows dose-dependent oral bioavailability in humans, which is likely attributable to saturation of intestinal efflux abilities leading to higher absorption with higher doses. this study evaluated the membrane permeability of mirabegron and investigated the involvement of human intestinal transport proteins in the membrane permeation ... | 2013 | 23560393 |
| validation of novel reference genes for rt-qpcr studies of gene expression in xenopus tropicalis during embryonic and post-embryonic development. | accurate interpretation of transcriptome profiling by quantitative pcr requires the establishment of species-specific standards. however, the selection of reference genes for assessing rna expression profiles in xenopus laevis and xenopus tropicalis was mostly based on historical reasons and they often only reflect the traditions of a laboratory. | 2013 | 23559567 |
| effects of exposure to 17α-ethynylestradiol during sexual differentiation on the transcriptome of the african clawed frog (xenopus laevis). | exposure to estrogens during the period of sexual differentiation is known to adversely affect the development of testes in african clawed frogs (xenopus laevis), but little is known about molecular changes that coincide with the development of altered phenotypes. therefore, the transcriptome-level effects of exposure to 17α-ethynylestradiol (ee2) during sexual differentiation of x. laevis were evaluated by use of illumina sequencing coupled with rna-seq expression analysis. overall, a number of ... | 2013 | 23550701 |
| thyroid hormone-induced cell-cell interactions are required for the development of adult intestinal stem cells. | the mammalian intestine has long been used as a model to study organ-specific adult stem cells, which are essential for organ repair and tissue regeneration throughout adult life. the establishment of the intestinal epithelial cell self-renewing system takes place during perinatal development when the villus-crypt axis is established with the adult stem cells localized in the crypt. this developmental period is characterized by high levels of plasma thyroid hormone (t3) and t3 deficiency is know ... | 2013 | 23547658 |
| investigating morphogenesis in xenopus embryos: imaging strategies, processing, and analysis. | methods have been developed for visualizing cell movement and protein dynamics during morphogenesis within live multicellular tissues isolated from xenopus laevis embryos. these include the preparation and use of reporter constructs in xenopus embryos, microsurgical techniques for isolating embryonic tissues, and methods for culturing live tissues for extended periods. in this article, we present strategies for successful imaging of large thick embryonic tissues by improving the signal and minim ... | 2013 | 23547160 |
| assembly of chambers for stable long-term imaging of live xenopus tissue. | understanding the molecular mechanisms and cellular mechanics that drive morphogenesis in xenopus laevis embryos requires high-resolution quantitative imaging of cell movement and protein dynamics within multicellular tissues. to perform long-term tissue culture and stable imaging of live xenopus tissue, we have developed a simple acrylic chamber that can be sealed and reused. the explants can be cultured on an adhesive substrate or within a nonadhesive microenvironment. we have developed a meth ... | 2013 | 23547159 |
| microsurgical approaches to isolate tissues from xenopus embryos for imaging morphogenesis. | to understand dynamic cell and tissue mechanics during xenopus laevis morphogenesis requires the use of live reporters of cell architecture as well as reporters for the location and activity of proteins in cells within a multicellular tissue. fluorescently tagged proteins are some of the most useful reporters for live cell work. once the desired expression pattern of fluorescent reporters has been found, the next step is preparing samples of tissue explants to bring subcellular structures and pr ... | 2013 | 23547158 |
| preparation and use of reporter constructs for imaging morphogenesis in xenopus embryos. | to understand dynamic cell and tissue mechanics during xenopus laevis morphogenesis requires the use of live reporters of cell architecture as well as reporters for the location and activity of proteins in cells within a multicellular tissue. fluorescently tagged proteins are some of the most useful reporters for live cell work. these fluorescent reporters are either proteins conjugated to small fluorochromes or molecularly engineered chimeric fluorescent proteins, and they can be distributed ev ... | 2013 | 23547157 |
| expression of slc22a1 variants may affect the response of hepatocellular carcinoma and cholangiocarcinoma to sorafenib. | reduced drug uptake is an important mechanism of chemoresistance. down-regulation of slc22a1 encoding the organic cation transporter-1 (oct1) may affect the response of hepatocellular carcinoma (hcc) and cholangiocarcinoma (cgc) to sorafenib, a cationic drug. here we investigated whether slc22a1 variants may contribute to sorafenib chemoresistance. complete sequencing and selective variant identification were carried out to detect single nucleotide polymorphisms (snps) in slc22a1 complementary d ... | 2013 | 23532667 |
| species differences of organic anion transporters involved in the renal uptake of 4-amino-3-chlorophenyl hydrogen sulfate, a metabolite of resatorvid, between rats and dogs. | previous studies on the metabolic fate of resatorvid (tak-242) have shown that species differences in the pharmacokinetics of 4-amino-3-chlorophenyl hydrogen sulfate (m-iii), a metabolite of tak-242, between rats and dogs are mainly attributable to the urinary excretion process. in the present study, the renal uptake mechanism of m-iii was investigated using kidney slices and xenopus laevis oocytes expressing rat organic anion transporter 1 (roat1; slc22a6) and roat3 (slc22a8). the uptake of p-a ... | 2013 | 23529922 |
| a role of prostaglandin transporter in regulating pge₂ release from human bronchial epithelial beas-2b cells in response to lps. | naturally occurring prostaglandin e₂ (pge₂) plays a role in inflammatory responses through eicosanoid signaling pathways. pge₂ is impermeable to cell membranes at physiological ph and needs solute carrier across the membranes; however, it remains unclear how intercellular concentrations of pge₂ are regulated under the condition of inflammation. we aimed to clarify a role of organic anion-transporting polypeptide 2a1 (oatp2a1/slco2a1), also known as prostaglandin transporter (pgt), in pge₂ releas ... | 2013 | 23528477 |
| conserved extracellular cysteines differentially regulate the potentiation produced by zn2+ in rat p2x4 receptors. | one feature of the amino acid sequence of p2x receptors identified from mammalian species, xenopus laevis and zebrafish is the conservation of ten cysteines in the extracellular loop. little information is available about the role of these conserved ectodomain cysteines in the function of p2x receptors. here, we investigated the possibility that ten conserved cysteine residues in the extracellular loop of the rat p2x4 receptor may regulate zinc potentiation of the receptor using a series of indi ... | 2013 | 23524095 |
| solution structure of the qua1 dimerization domain of pxqua, the xenopus ortholog of quaking. | the star protein family member quaking is essential for early development in vertebrates. for example, in oligodendrocyte cells it regulates the splicing, localization, translation and lifetime of a set of mrnas that code for crucial components of myelin. the quaking protein contains three contiguous conserved regions: a qua1 oligomerization element, followed by a single-stranded rna binding motif comprising the kh and qua2 domains. an embryonic lethal point mutation in the qua1 domain, e48g, is ... | 2013 | 23520467 |
| effective rnai-mediated β2-microglobulin loss of function by transgenesis in xenopus laevis. | to impair mhc class i (class i) function in vivo in the amphibian xenopus, we developed an effective reverse genetic loss of function approach by combining i-scei meganuclease-mediated transgenesis with rnai technology. we generated transgenic outbred x. laevis and isogenetic laevis/gilli cloned lines with stably silenced expression of β2-microglobulin (b2m) critical for class i function. transgenic f1 frogs exhibited decreased surface class i expression on erythrocytes and lymphocytes, decrease ... | 2013 | 23519478 |
| primary oocyte transcriptional activation of aqp1ab by the nuclear progestin receptor determines the pelagic egg phenotype of marine teleosts. | in marine teleosts, the aqp1ab water channel plays a vital role in the development of the pelagic egg phenotype. however, the developmental control of aqp1ab activation during oogenesis remains to be established. here, we report the isolation of the 5'-flanking region of the teleost gilthead seabream aqp1ab gene, in which we identify conserved cis-regulatory elements for the binding of the nuclear progestin receptor (pgr) and members of the sox family of transcription factors. subcellular locali ... | 2013 | 23499660 |
| microtransplantation of cellular membranes from squid stellate ganglion reveals ionotropic gaba receptors. | the squid has been the most studied cephalopod, and it has served as a very useful model for investigating the events associated with nerve impulse generation and synaptic transmission. while the physiology of squid giant axons has been extensively studied, very little is known about the distribution and function of the neurotransmitters and receptors that mediate inhibitory transmission at the synapses. in this study we investigated whether γ-aminobutyric acid (gaba) activates neurotransmitter ... | 2013 | 23493508 |
| double mutation at the putative protein kinase c phosphorylation sites thr151 plus thr323 in the mouse leukotriened4 receptor eliminates homologous desensitization. | signalling via cyslt1 is involved in activation of volume sensitive k(+) channels and homologous desensitization of the ltd4 receptor impairs regulatory volume decrease (rvd). the aim is to illustrate the effect of mutation of putative pkc consensus phosphorylation sites in the cyslt1r on desensitization and rvd. | 2013 | 23485744 |
| colony-stimulating factor-1-responsive macrophage precursors reside in the amphibian (xenopus laevis) bone marrow rather than the hematopoietic subcapsular liver. | macrophage precursors originate from and undergo lineage commitment within designated sites of hematopoiesis, such as the mammalian bone marrow. these cells subsequently differentiate in response to stimulation with macrophage colony-stimulating factor-1 (csf-1). the amphibian bone marrow, unlike that of mammals, has been overlooked as a source of leukocyte precursors in favor of the liver subcapsular region, where hematopoiesis occurs in anurans. here we report that the bone marrow rather than ... | 2013 | 23485675 |
| ampa receptor/tarp stoichiometry visualized by single-molecule subunit counting. | members of the transmembrane ampa receptor-regulatory protein (tarp) family modulate ampa receptor (ampa-r) trafficking and function. ampa-rs consist of four pore-forming subunits. previous studies show that tarps are an integral part of the ampa-r complex, acting as accessory subunits for mature receptors in vivo. the tarp/ampa-r stoichiometry was previously measured indirectly and found to be variable and dependent on tarp expression level, with at most four tarps associated with each ampa-r c ... | 2013 | 23479622 |
| subtype selectivity of α+β- site ligands of gabaa receptors: identification of the first highly specific positive modulators at α6β2/3γ2 receptors. | gabaa receptors are the major inhibitory neurotransmitter receptors in the mammalian brain and the target of many clinically important drugs interacting with different binding sites. recently, we demonstrated that cgs 9895 (2-(4-methoxyphenyl)-2h-pyrazolo[4,3-c]quinolin-3(5h)-one) elicits a strong and subtype-dependent enhancement of gaba-induced currents via a novel drug-binding site at extracellular αx+βy- (x = 1-6, y = 1-3) interfaces. here, we investigated 16 structural analogues of cgs 9895 ... | 2013 | 23472935 |
| identification of novel positive allosteric modulators and null modulators at the gabaa receptor α+β- interface. | gabaa receptors are the major inhibitory neurotransmitter receptors in the mammalian brain and the target of many clinically important drugs interacting with different binding sites. recently, we demonstrated that cgs 9895 (2-(4-methoxyphenyl)-2h-pyrazolo[4,3-c]quinolin-3(5h)-one) acts as a null modulator (antagonist) at the high affinity benzodiazepine binding site, but in addition elicits a strong enhancement of gaba-induced currents via a novel drug binding site at the extracellular α+β- inte ... | 2013 | 23472852 |
| transmembrane voltage potential is an essential cellular parameter for the detection and control of tumor development in a xenopus model. | understanding mechanisms that orchestrate cell behavior into appropriately patterned tissues and organs within the organism is an essential element of preventing, detecting and treating cancer. bioelectric signals (resting transmembrane voltage potential gradients in all cells) underlie an important and broadly conserved set of control mechanisms that regulate pattern formation. we tested the role of transmembrane potential in tumorigenesis mediated by canonical oncogenes in xenopus laevis. depo ... | 2013 | 23471912 |
| transport of kynurenic acid by rat organic anion transporters roat1 and roat3: species difference between human and rat in oat1. | a tryptophan catabolite, kynurenic acid, is involved in schizophrenia and uremia; there is little information on the mechanism of its disposition. recently, our laboratory showed that kynurenic acid is a good substrate of human organic anion transporters hoat1 and hoat3. in this study, we performed uptake experiment using xenopus laevis oocytes to characterize the transport of kynurenic acid by rat homologs of the transporters, roat1, and roat3. these transporters stimulated the uptake of kynure ... | 2013 | 23467467 |
| spinal efference copy signaling and gaze stabilization during locomotion in juvenile xenopus frogs. | in swimming xenopus laevis tadpoles, gaze stabilization is achieved by efference copies of spinal locomotory cpg output that produce rhythmic extraocular motor activity appropriate for minimizing motion-derived visual disturbances. during metamorphosis, xenopus switches its locomotory mechanism from larval tail-based undulatory movements to bilaterally synchronous hindlimb kick propulsion in the adult. the change in locomotory mode leads to body motion dynamics that no longer require conjugate l ... | 2013 | 23467343 |
| a lectin-based glycomic approach to identify characteristic features of xenopus embryogenesis. | cell surface glycans show dynamic changes during cell differentiation. several glycans are useful biomarkers of tumors, stem cells, and embryogenesis. glycomic studies have been performed using liquid chromatography and mass spectrometry, which are powerful tools for glycan structural analysis but are difficult to use for small sample sizes. recently, a lectin microarray system was developed for profiling cell surface glycome changes to terminal carbohydrate chains and branch types, using sample ... | 2013 | 23457585 |
| unlaid xenopus eggs degrade by apoptosis in the genital tract. | in several species with external fertilization, including frogs, laid unfertilized eggs were found to die by apoptosis outside of the animal body. however, there is no apparent reason for the externally laid eggs to degrade by this process, considering that apoptosis developed as a mechanism to reduce the damaging effect of individual cell death to the whole organism. | 2013 | 23452868 |
| structure of the arginine methyltransferase prmt5-mep50 reveals a mechanism for substrate specificity. | the arginine methyltransferase prmt5-mep50 is required for embryogenesis and is misregulated in many cancers. prmt5 targets a wide variety of substrates, including histone proteins involved in specifying an epigenetic code. however, the mechanism by which prmt5 utilizes mep50 to discriminate substrates and to specifically methylate target arginines is unclear. to test a model in which mep50 is critical for substrate recognition and orientation, we determined the crystal structure of xenopus laev ... | 2013 | 23451136 |
| regulation of aqp0 water permeability is enhanced by cooperativity. | aquaporin 0 (aqp0), essential for lens clarity, is a tetrameric protein composed of four identical monomers, each of which has its own water pore. the water permeability of aqp0 expressed in xenopus laevis oocytes can be approximately doubled by changes in calcium concentration or ph. although each monomer pore functions as a water channel, under certain conditions the pores act cooperatively. in other words, the tetramer is the functional unit. in this paper, we show that changes in external ph ... | 2013 | 23440275 |
| expression-dependent pharmacology of transient receptor potential vanilloid subtype 1 channels in xenopus laevis oocytes. | transient receptor potential vanilloid subfamily member 1 channels are polymodal sensors of noxious stimuli and integral players in thermosensation, inflammation and pain signaling. it has been shown previously that under prolonged stimulation, these channels show dynamic pore dilation, providing a pathway for large and otherwise relatively impermeant molecules. further, we have shown recently that these nonselective cation channels, when activated by capsaicin, are potently and reversibly block ... | 2013 | 23428812 |
| mitotic spindle scaling during xenopus development by kif2a and importin α. | early development of many animals is characterized by rapid cleavages that dramatically decrease cell size, but how the mitotic spindle adapts to changing cell dimensions is not understood. to identify mechanisms that scale the spindle during xenopus laevis embryogenesis, we established an in vitro system using cytoplasmic extracts prepared from embryos that recapitulates in vivo spindle size differences between stage 3 (4 cells, 37 µm) and stage 8 (∼4000 cells, 18 µm). we identified the kinesin ... | 2013 | 23425906 |
| xenopus laevis tadpoles can regenerate neural retina lost after physical excision but cannot regenerate photoreceptors lost through targeted ablation. | to determine whether the xenopus laevis retina is capable of regenerating photoreceptor cells lost through apoptotic cell death in an inducible transgenic x. laevis model of retinitis pigmentosa (rp). | 2013 | 23425694 |
| cell differentiation of pluripotent tissue sheets immobilized on supported membranes displaying cadherin-11. | investigating cohesive tissue sheets in controlled cultures still poses a challenge since the complex intercellular interactions are difficult to mimic in in vitro models. we used supported lipid membranes functionalized by the adhesive part of the extracellular domain of the cell adhesion molecule cadherin-11 for the immobilization of pluripotent tissue sheets, the animal cap isolated from xenopus laevis blastula stage embryos. cadherin-11 was bound via histidine tag to lipid membranes with che ... | 2013 | 23424619 |
| characterization of pax1, pax9, and uncx sclerotomal genes during xenopus laevis embryogenesis. | the axial skeleton develops from the sclerotome, a mesenchymal cell population derived from somites. sclerotomal cells migrate from somites to the perinotochordal and perineural space where they differentiate into chondrocytes to form cartilage and bone. in anurans, little is known about the way how the sclerotome changes as development proceeds and how these events are regulated at the molecular level. pax1, pax9, and uncx4.1 genes play a central role in the morphogenesis of the axial skeleton ... | 2013 | 23401059 |
| metabolic regulation of camkii protein and caspases in xenopus laevis egg extracts. | the metabolism of the xenopus laevis egg provides a cell survival signal. we found previously that increased carbon flux from glucose-6-phosphate (g6p) through the pentose phosphate pathway in egg extracts maintains nadph levels and calcium/calmodulin regulated protein kinase ii (camkii) activity to phosphorylate caspase 2 and suppress cell death pathways. here we show that the addition of g6p to oocyte extracts inhibits the dephosphorylation/inactivation of camkii bound to caspase 2 by protein ... | 2013 | 23400775 |
| specific ligand binding domain residues confer low dioxin responsiveness to ahr1β of xenopus laevis. | the aryl hydrocarbon receptor (ahr) is a per-arnt-sim (pas) family protein that mediates the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd) in vertebrates. frogs are remarkably insensitive to tcdd, and ahrs from xenopus laevis bind tcdd with low affinity. we sought to identify structural features of x. laevis ahr1β associated with low tcdd sensitivity. substitution of the entire ligand binding domain (lbd) with the corresponding sequence from mouse ahr(b-1) dramatically increased tcdd re ... | 2013 | 23394719 |
| human trace amine-associated receptor taar5 can be activated by trimethylamine. | in addition to the canonical olfactory receptors, taars were currently suggested to be a second class of chemosensory receptors in the olfactory epithelium of vertebrates. in contrast to several deorphanized murine taars, agonists for the intact human taar genes 2, 5, 6, 8 and 9 that are potentially expressed in the human olfactory epithelium have not been determined so far. moreover, the physiological relevance of taars still remains elusive. we present the first successful functional expressio ... | 2013 | 23393561 |
| molecular determinants for functional differences between alanine-serine-cysteine transporter 1 and other glutamate transporter family members. | the ascts (alanine, serine, and cysteine transporters) belong to the solute carrier family 1 (slc1), which also includes the human glutamate transporters (excitatory amino acid transporters, eaats) and the prokaryotic aspartate transporter gltph. despite the high degree of amino acid sequence identity between family members, ascts function quite differently from the eaats and gltph. the aim of this study was to mutate asct1 to generate a transporter with functional properties of the eaats and gl ... | 2013 | 23393130 |
| the neuronal serum- and glucocorticoid-regulated kinase 1.1 reduces neuronal excitability and protects against seizures through upregulation of the m-current. | the m-current formed by tetramerization of kv7.2 and kv7.3 subunits is a neuronal voltage-gated k(+) conductance that controls resting membrane potential and cell excitability. in xenopus laevis oocytes, an increase in kv7.2/3 function by the serum- and glucocorticoid-regulated kinase 1 (sgk1) has been reported previously (schuetz et al., 2008). we now show that the neuronal isoform of this kinase (sgk1.1), with distinct subcellular localization and modulation, upregulates the kv7.2/3 current in ... | 2013 | 23392695 |
| hsp72 mediates stronger antigen-dependent non-classical mhc class ib anti-tumor responses than hsc73 in xenopus laevis. | the heat shock proteins (hsps) gp96 and hsp70 mediate potent antigen-dependent anti-tumor t cell responses in both mammals and xenopus laevis. we have shown that frogs immunized with total hsp70 generate cd8+ t cell responses against the xenopus thymic lymphoid tumor 15/0 that expresses several non-classical mhc class ib (class ib) genes, but no classical mhc class ia (class ia). in the absence of class ia, we hypothesized that hsp72 can prime class ib-mediated anti-tumor unconventional cd8+ t c ... | 2013 | 23390375 |
| transplantation of xenopus laevis tissues to determine the ability of motor neurons to acquire a novel target. | the evolutionary origin of novelties is a central problem in biology. at a cellular level this requires, for example, molecularly resolving how brainstem motor neurons change their innervation target from muscle fibers (branchial motor neurons) to neural crest-derived ganglia (visceral motor neurons) or ear-derived hair cells (inner ear and lateral line efferent neurons). transplantation of various tissues into the path of motor neuron axons could determine the ability of any motor neuron to inn ... | 2013 | 23383335 |
| tissue-specific upregulation of mds/evi gene transcripts in the intestine by thyroid hormone during xenopus metamorphosis. | intestinal remodeling during amphibian metamorphosis resembles the maturation of the adult intestine during mammalian postembryonic development when the adult epithelial self-renewing system is established under the influence of high concentrations of plasma thyroid hormone (t3). this process involves de novo formation and subsequent proliferation and differentiation of the adult stem cells. | 2013 | 23383234 |
| suv4-20h histone methyltransferases promote neuroectodermal differentiation by silencing the pluripotency-associated oct-25 gene. | post-translational modifications (ptms) of histones exert fundamental roles in regulating gene expression. during development, groups of ptms are constrained by unknown mechanisms into combinatorial patterns, which facilitate transitions from uncommitted embryonic cells into differentiated somatic cell lineages. repressive histone modifications such as h3k9me3 or h3k27me3 have been investigated in detail, but the role of h4k20me3 in development is currently unknown. here we show that xenopus lae ... | 2013 | 23382689 |
| the gaba a receptor subunits heterologously expressed in xenopus oocytes. | the γ-aminobutyric acid (gaba) a receptor is composed of a variety of subunits and combinations and shows a characteristic distribution in the cns. to date, 20 subunits of the gaba a receptor have been cloned: α1-6, β1-4, γ1-3, δ, π, ε , θ, and ρ1-3. oocyte of xenopus laevis is one of the most frequently used heterologous expression systems, which are used to design and analyze specific combinations of gaba a receptor subunits. in oocytes, a certain gaba a receptor function is studied only by co ... | 2013 | 23373649 |
| loss of cell-extracellular matrix interaction triggers retinal regeneration accompanied by rax and pax6 activation. | the whole retina regenerates from retinal pigmented epithelial (rpe) cells by transdifferentiation in the adult newt and xenopus laevis when it is surgically removed. we produced a transgenic animal line, in which egfp expression is under the control of rax pomotor. using f1 and f2 generations, we analyzed rax-egfp expression during retinal regeneration in a tissue culture model. in the culture, 4 zones were distinguished as rpe cells migrating outwards from the periphery of the explant: the exp ... | 2013 | 23362049 |
| an intact brachyury function is necessary to prevent spurious axial development in xenopus laevis. | we have previously shown that the member of the hes family hairy2 induces the ectopic expression of dorsal markers when it is overexpressed in the ventral side of xenopus embryos. intriguingly, hairy2 represses the mesoderm transcription factor brachyury (bra) throughout its domain in the marginal zone. here we show that in early gastrula, bra and hairy2 are expressed in complementary domains. overexpression of bra repressed hairy2. interference of bra function with a dominant-negative construct ... | 2013 | 23359630 |
| an evaluation of 2,4-dichlorophenoxyacetic acid in the amphibian metamorphosis assay and the fish short-term reproduction assay. | 2,4-dichlorophenoxyacetic acid (2,4-d) was evaluated in both the amphibian metamorphosis assay (ama) and the fish short term reproduction assay (fstra). in the ama, tadpoles were exposed to mean measured 2,4-d concentrations of 0 (water control), 0.273, 3.24, 38.0 and 113 mg acid equivalents (ae)/l for either seven or 21 days. in the fstra, fathead minnows were exposed to mean measured 2,4-d concentrations of 0 (water control), 0.245, 3.14, 34.0, and 96.5 mg ae/l for 21 days. the respective conc ... | 2013 | 23357564 |
| regulation of g-protein signaling via gnas is required to regulate proximal tubular growth in the xenopus pronephros. | in the kidney, proximal tubules are very important for the reabsorption of water, ions and organic solutes from the primary urine. they are composed of highly specialized epithelial cells that are characterized by an elaborate apical brush border to increase transport efficiency. using the pronephric kidney of xenopus laevis we discovered that the g-protein modulator cholera toxin resulted in a dramatic reduction of the proximal tubular size. this phenotype was accompanied by changes in the cyto ... | 2013 | 23352791 |
| pharmacological fractionation of tetrodotoxin-sensitive sodium currents in rat dorsal root ganglion neurons by μ-conotoxins. | adult rat dorsal root ganglion (drg) neurons normally express transcripts for five isoforms of the α-subunit of voltage-gated sodium channels: nav 1.1, 1.6, 1.7, 1.8 and 1.9. tetrodotoxin (ttx) readily blocks all but nav 1.8 and 1.9, and pharmacological agents that discriminate among the ttx-sensitive nav 1-isoforms are scarce. recently, we used the activity profile of a panel of μ-conotoxins in blocking cloned rodent nav 1-isoforms expressed in xenopus laevis oocytes to conclude that action pot ... | 2013 | 23351163 |
| establishment of intestinal stem cell niche during amphibian metamorphosis. | in the amphibian intestine during metamorphosis, most of the larval epithelial cells undergo apoptosis, whereas a small number of them survive. these cells dedifferentiate into stem cells through interactions with the microenvironment referred to as "stem cell niche" and generate the adult epithelium analogous to the mammalian counterpart. since all processes of the larval-to-adult intestinal remodeling can be experimentally induced by thyroid hormone (th) both in vivo and in vitro, the amphibia ... | 2013 | 23347524 |
| histone deacetylase induces accelerated maturation in xenopus laevis oocytes. | in oocyte maturation in xenopus laevis, nuclear material induces rapid maturation and is required for entry into meiosis ii. nuclear material contains a large number of rnas and proteins, including histone deacetylase (hdac); however, it is not known which materials induce accelerated maturation. the hdac activity modifies transcription rate and is required for normal meiosis; however, its function in oocyte maturation is still unclear. we investigated the function of hdac activity, which is loc ... | 2013 | 23346879 |
| zeb1 imposes a temporary stage-dependent inhibition of muscle gene expression and differentiation via ctbp-mediated transcriptional repression. | skeletal muscle development is orchestrated by the myogenic regulatory factor myod, whose activity is blocked in myoblasts by proteins preventing its nuclear translocation and/or binding to g/c-centered e-boxes in target genes. recent evidence indicates that muscle gene expression is also regulated at the cis level by differential affinity for dna between myod and other e-box binding proteins during myogenesis. myod binds to g/c-centered e-boxes, enriched in muscle differentiation genes, in myot ... | 2013 | 23339872 |
| early infantile epileptic encephalopathy associated with a high voltage gated calcium channelopathy. | early infantile epileptic encephalopathies usually manifest as severely impaired cognitive and motor development and often result in a devastating permanent global developmental delay and intellectual disability. a large set of genes has been implicated in the aetiology of this heterogeneous group of disorders. among these, the ion channelopathies play a prominent role. in this study, we investigated the genetic cause of infantile epilepsy in three affected siblings. | 2013 | 23339110 |
| spatiotemporal control of microtubule nucleation and assembly using magnetic nanoparticles. | decisions on the fate of cells and their functions are dictated by the spatiotemporal dynamics of molecular signalling networks. however, techniques to examine the dynamics of these intracellular processes remain limited. here, we show that magnetic nanoparticles conjugated with key regulatory proteins can artificially control, in time and space, the ran/rcc1 signalling pathway that regulates the cell cytoskeleton. in the presence of a magnetic field, rangtp proteins conjugated to superparamagne ... | 2013 | 23334169 |
| human aqp1 is a constitutively open channel that closes by a membrane-tension-mediated mechanism. | this work presents experimental results combined with model-dependent predictions regarding the osmotic-permeability regulation of human aquaporin 1 (haqp1) expressed in xenopus oocyte membranes. membrane elastic properties were studied under fully controlled conditions to obtain a function that relates internal volume and pressure. this function was used to design a model in which osmotic permeability could be studied as a pressure-dependent variable. the model states that haqp1 closes with mem ... | 2013 | 23332061 |
| an scf complex containing fbxl12 mediates dna damage-induced ku80 ubiquitylation. | the ku heterodimer, composed of ku70 and ku80, is the initiating factor of the nonhomologous end joining (nhej) double-strand break (dsb) repair pathway. ku is also thought to impede the homologous recombination (hr) repair pathway via inhibition of dna end resection. using the cell-free xenopus laevis egg extract system, we had previously discovered that ku80 becomes polyubiquitylated upon binding to dsbs, leading to its removal from dna and subsequent proteasomal degradation. here we show that ... | 2013 | 23324393 |
| chromosomal gain promotes formation of a steep rangtp gradient that drives mitosis in aneuploid cells. | many mitotic factors were shown to be activated by ran guanosine triphosphatase. previous studies in xenopus laevis egg extracts and in highly proliferative cells showed that mitotic chromosomes were surrounded by steep ran guanosine triphosphate (gtp) concentration gradients, indicating that rangtp-activated factors promote spindle assembly around chromosomes. however, the mitotic role of ran in normal differentiated cells is not known. in this paper, we show that although the steep mitotic ran ... | 2013 | 23319601 |
| amputation-induced reactive oxygen species are required for successful xenopus tadpole tail regeneration. | understanding the molecular mechanisms that promote successful tissue regeneration is critical for continued advancements in regenerative medicine. vertebrate amphibian tadpoles of the species xenopus laevis and xenopus tropicalis have remarkable abilities to regenerate their tails following amputation, through the coordinated activity of numerous growth factor signalling pathways, including the wnt, fgf, bmp, notch and tgf-β pathways. little is known, however, about the events that act upstream ... | 2013 | 23314862 |
| insulin increases the functional activity of the renal nacl cotransporter. | insulin is recognized to increase renal salt reabsorption in the distal nephron and hyperinsulinemic states have been shown to be associated with increased expression of the renal nacl cotransporter (ncc). however, the effect of insulin on ncc functional activity has not been reported. | 2013 | 23303355 |
| the xenbase literature curation process. | xenbase (www.xenbase.org) is the model organism database for xenopus tropicalis and xenopus laevis, two frog species used as model systems for developmental and cell biology. xenbase curation processes centre on associating papers with genes and extracting gene expression patterns. papers from pubmed with the keyword 'xenopus' are imported into xenbase and split into two curation tracks. in the first track, papers are automatically associated with genes and anatomy terms, images and captions are ... | 2013 | 23303299 |
| function of shaker potassium channels produced by cell-free translation upon injection into xenopus oocytes. | voltage-gated ion channels are a class of membrane proteins that temporally orchestrate the ion flux critical for chemical and electrical signaling in excitable cells. current methods to investigate the function of these channels rely on heterologous expression in living systems or reconstitution into artificial membranes; however these approaches have inherent drawbacks which limit potential biophysical applications. here, we describe a new integrated approach combining cell-free translation of ... | 2013 | 23301161 |
| coupling of nf-protocadherin signaling to axon guidance by cue-induced translation. | cell adhesion molecules and diffusible cues both regulate axon pathfinding, yet how these two modes of signaling interact is poorly understood. the homophilic cell adhesion molecule nf-protocadherin (nfpc) is expressed in the mid-dorsal optic tract neuroepithelium and in the axons of developing retinal ganglion cells (rgc) in xenopus laevis. here we report that targeted disruption of nfpc function in rgc axons or the optic tract neuroepithelium results in unexpectedly localized pathfinding defec ... | 2013 | 23292679 |
| expanding the genetic code in xenopus laevis oocytes. | heterologous expression of ligand-gated ion channels (lgics) in xenopus laevis oocytes combined with site-directed mutagenesis has been demonstrated to be a powerful approach to study structure-function relationships. in particular, introducing unnatural amino acids (uaas) has enabled modifications that are not found in natural proteins. however, the current strategy relies on the technically demanding in vitro synthesis of aminoacylated suppressor trna. we report here a general method that circ ... | 2013 | 23292655 |
| synthesis, pharmacology, and biostructural characterization of novel α4β2 nicotinic acetylcholine receptor agonists. | in our search for selective agonists for the α(4)β(2) subtype of the nicotinic acetylcholine receptors (nachrs), we have synthesized and characterized a series of novel heterocyclic analogues of 3-(dimethylamino)butyl dimethylcarbamate (dmabc, 4). all new heterocyclic analogues, especially n,n-dimethyl-4-(1-methyl-1h-imidazol-2-yloxy)butan-2-amine (7), showed an improved binding selectivity profile in favor of α(4)β(2) over other nachr subtypes, primarily due to impaired binding at β(4) containi ... | 2013 | 23256554 |