| semicircular canal-dependent developmental tuning of translational vestibulo-ocular reflexes in xenopus laevis. | gaze stabilization during head/body movements is achieved to a large extent by vestibular-evoked compensatory eye movements. these reflexes derive from semicircular canal and otolith organs and depend on the transformation of the respective sensory signals into extraocular motor commands. to elicit directionally and dynamically appropriate compensatory eye movements, extraocular motoneurons require spatiotemporally specific inputs from semicircular canals and regions of the utricular epithelium ... | 2015 | 25266079 |
| cdc6 controls dynamics of the first embryonic m-phase entry and progression via cdk1 inhibition. | cdc6 is essential for s-phase to initiate dna replication. it also regulates m-phase exit by inhibiting the activity of the major m-phase protein kinase cdk1. here we show that addition of recombinant cdc6 to xenopus embryo cycling extract delays the m-phase entry and inhibits cdk1 during the whole m-phase. down regulation of endogenous cdc6 accelerates the m-phase entry, abolishes the initial slow and progressive phase of histone h1 kinase activation and increases the level of cdk1 activity dur ... | 2014 | 25264619 |
| upregulation of eif5b controls cell-cycle arrest and specific developmental stages. | proliferation arrest and distinct developmental stages alter and decrease general translation yet maintain ongoing translation. the factors that support translation in these conditions remain to be characterized. we investigated an altered translation factor in three cell states considered to have reduced general translation: immature xenopus laevis oocytes, mouse es cells, and the transition state of proliferating mammalian cells to quiescence (g0) upon growth-factor deprivation. our data revea ... | 2014 | 25261552 |
| cathepsin b contributes to na+ hyperabsorption in cystic fibrosis airway epithelial cultures. | in cystic fibrosis (cf) lung disease, the absence of functional cf transmembrane conductance regulator results in cl(-)/hco3 (-) hyposecretion and triggers na(+) hyperabsorption through the epithelial na(+) channel (enac), which contribute to reduced airway surface liquid (asl) ph and volume. prostasin, a membrane-anchored serine protease with trypsin-like substrate specificity has previously been shown to activate enac in cf airways. however, prostasin is typically inactive below ph 7.0, sugges ... | 2014 | 25260629 |
| sperm and spermatids contain different proteins and bind distinct egg factors. | spermatozoa are more efficient at supporting normal embryonic development than spermatids, their immature, immediate precursors. this suggests that the sperm acquires the ability to support embryonic development during spermiogenesis (spermatid to sperm maturation). here, using xenopus laevis as a model organism, we performed 2-d fluorescence difference gel electrophoresis (2d-dige) and mass spectrometry analysis of differentially expressed proteins between sperm and spermatids in order to ident ... | 2014 | 25244019 |
| circadian genes, xbmal1 and xnocturnin, modulate the timing and differentiation of somites in xenopus laevis. | we have been investigating whether xbmal1 and xnocturnin play a role in somitogenesis, a cyclic developmental process with an ultradian period. previous work from our lab shows that circadian genes (xperiod1, xperiod2, xbmal1, and xnocturnin) are expressed in developing somites. somites eventually form the vertebrae, muscles of the back, and dermis. in xenopus, a pair of somites is formed about every 50 minutes from anterior to posterior. we were intrigued by the co-localization of circadian gen ... | 2014 | 25238599 |
| extracellular gentamicin reduces the activity of connexin hemichannels and interferes with purinergic ca(2+) signaling in hela cells. | gap junction channels (gjcs) and hemichannels (hcs) are composed of protein subunits termed connexins (cxs) and are permeable to ions and small molecules. in most organs, gjcs communicate the cytoplasm of adjacent cells, while hcs communicate the intra and extracellular compartments. in this way, both channel types coordinate physiological responses of cell communities. cx mutations explain several genetic diseases, including about 50% of autosomal recessive non-syndromic hearing loss. however, ... | 2014 | 25237294 |
| aqp4 plasma membrane trafficking or channel gating is not significantly modulated by phosphorylation at cooh-terminal serine residues. | aquaporin 4 (aqp4) is the predominant water channel in the mammalian brain and is mainly expressed in the perivascular glial endfeet at the brain-blood interface. aqp4 serves as a water entry site during brain edema formation, and regulation of aqp4 may therefore be of therapeutic interest. phosphorylation of aquaporins can regulate plasma membrane localization and, possibly, the unit water permeability via gating of the aqp channel itself. in vivo phosphorylation of six serine residues in the c ... | 2014 | 25231107 |
| aberrant connexin26 hemichannels underlying keratitis-ichthyosis-deafness syndrome are potently inhibited by mefloquine. | keratitis-ichthyosis-deafness (kid) syndrome is an ectodermal dysplasia caused by dominant mutations of connexin26 (cx26). loss of cx26 function causes nonsyndromic sensorineural deafness, without consequence in the epidermis. functional analyses have revealed that a majority of kid-causing mutations confer a novel expansion of hemichannel activity, mediated by connexin channels in a nonjunctional configuration. inappropriate cx26 hemichannel opening is hypothesized to compromise keratinocyte in ... | 2015 | 25229253 |
| using plustiptracker software to measure microtubule dynamics in xenopus laevis growth cones. | microtubule (mt) plus-end-tracking proteins (+tips) localize to the growing plus-ends of mts and regulate mt dynamics(1,2). one of the most well-known and widely-utilized +tips for analyzing mt dynamics is the end-binding protein, eb1, which binds all growing mt plus-ends, and thus, is a marker for mt polymerization(1). many studies of eb1 behavior within growth cones have used time-consuming and biased computer-assisted, hand-tracking methods to analyze individual mts(1-3). our approach is to q ... | 2014 | 25225829 |
| 5-mehtyltetrahydrofolate rescues alcohol-induced neural crest cell migration abnormalities. | alcohol is detrimental to early development. fetal alcohol spectrum disorders (fasd) due to maternal alcohol abuse results in a series of developmental abnormalities including cranial facial dysmorphology, ocular anomalies, congenital heart defects, microcephaly and intellectual disabilities. previous studies have been shown that ethanol exposure causes neural crest (nc) apoptosis and perturbation of neural crest migration. however, the underlying mechanism remains elusive. in this report we inv ... | 2014 | 25223405 |
| molecular and cellular characterization of urinary bladder-type aquaporin in xenopus laevis. | in contrast to many anuran amphibians, water is not reabsorbed from the urinary bladder in aquatic xenopus, thereby helping to prevent excessive water influx. however, little is known about the molecular mechanisms for this process. in the present study, we have identified urinary bladder-type aquaporin, aqp-x2, in xenopus laevis by cdna cloning. the predicted amino acid sequence contained six putative transmembrane domains and the two conserved asn-pro-ala motifs, characteristic of aqps. the se ... | 2015 | 25220852 |
| chibby functions in xenopus ciliary assembly, embryonic development, and the regulation of gene expression. | wnt signaling and ciliogenesis are core features of embryonic development in a range of metazoans. chibby (cby), a basal-body associated protein, regulates β-catenin-mediated wnt signaling in the mouse but not drosophila. here we present an analysis of cby's embryonic expression and morphant phenotypes in xenopus laevis. cby rna is supplied maternally, negatively regulated by snail2 but not twist1, preferentially expressed in the neuroectoderm, and regulates β-catenin-mediated gene expression. r ... | 2014 | 25220153 |
| role for endocytosis of a constitutively active gpcr (gpr185) in releasing vertebrate oocyte meiotic arrest. | vertebrate oocytes are naturally arrested at prophase of meiosis i for sustained periods of time before resuming meiosis in a process called oocyte maturation that prepares the egg for fertilization. members of the constitutively active gpr3/6/12 family of g-protein coupled receptors represent important mediators of meiotic arrest. in the frog oocyte the gpr3/12 homolog gprx (renamed gpr185) has been shown to sustain meiotic arrest by increasing intracellular camp levels through gαsβγ. here we s ... | 2014 | 25220151 |
| activation of sox3 gene by thyroid hormone in the developing adult intestinal stem cell during xenopus metamorphosis. | the maturation of the intestine into the adult form involves the formation of adult stem cells in a thyroid hormone (t3)-dependent process in vertebrates. in mammals, this takes place during postembryonic development, a period around birth when the t3 level peaks. due to the difficulty of manipulating late-stage, uterus-enclosed embryos, very little is known about the development of the adult intestinal stem cells. interestingly, the remodeling of the intestine during the t3-dependent amphibian ... | 2014 | 25211587 |
| thyroid hormone-regulated wnt5a/ror2 signaling is essential for dedifferentiation of larval epithelial cells into adult stem cells in the xenopus laevis intestine. | amphibian intestinal remodeling, where thyroid hormone (t3) induces some larval epithelial cells to become adult stem cells analogous to the mammalian intestinal ones, serves as a unique model for studying how the adult stem cells are formed. to clarify its molecular mechanisms, we here investigated roles of non-canonical wnt signaling in the larval-to-adult intestinal remodeling during xenopus laevis metamorphosis. | 2014 | 25211363 |
| identification of dehydroabietc acid from boswellia thurifera resin as a positive gabaa receptor modulator. | in a two-microelectrode voltage clamp assay with xenopus laevis oocytes, a petroleum ether extract (100 μg/ml) of the resin of boswellia thurifera (burseraceae) potentiated gaba-induced chloride currents (igaba) through receptors of the subtype α₁β₂γ₂s by 319.8% ± 79.8%. with the aid of hplc-based activity profiling, three known terpenoids, dehydroabietic acid (1), incensole (2), and akba (3), were identified in the active fractions of the extract. structure elucidation was achieved by means of ... | 2014 | 25200370 |
| erythropoietin protects red blood cells from trail1-induced cell death during red blood cell transition in xenopus laevis. | in anuran amphibians, larval red blood cells (rbcs) are replaced by adult-type rbcs during metamorphosis. we previously showed that tumor necrosis factor-related apoptosis-inducing ligand 1 (trail1) induces apoptosis in larval-, but not adult-type rbcs in xenopus laevis. we also found that protein kinase c (pkc) activation is involved in establishing resistance to trail1-induced apoptosis in adult-type rbcs. here, we investigated whether erythropoietin (epo), which induces pkc activation in mamm ... | 2015 | 25200139 |
| the bile acid receptor tgr5 activates the trpa1 channel to induce itch in mice. | patients with cholestatic disease have increased systemic concentrations of bile acids (bas) and profound pruritus. the g-protein-coupled ba receptor 1 tgr5 (encoded by gpbar1) is expressed by primary sensory neurons; its activation induces neuronal hyperexcitability and scratching by unknown mechanisms. we investigated whether the transient receptor potential ankyrin 1 (trpa1) is involved in ba-evoked, tgr5-dependent pruritus in mice. | 2014 | 25194674 |
| effects of low dose endosulfan exposure on brain neurotransmitter levels in the african clawed frog xenopus laevis. | understanding the impact of pesticides in amphibians is of growing concern to assess the causes of their decline. among pesticides, endosulfan belongs to one of the potential sources of danger because of its wide use and known effects, particularly neurotoxic, on a variety of organisms. however, the effect of endosulfan was not yet evaluated on amphibians at levels encompassing simultaneously brain neurotransmitters and behavioural endpoints. in this context, tadpoles of the african clawed frog ... | 2015 | 25192837 |
| divergent antiviral roles of amphibian (xenopus laevis) macrophages elicited by colony-stimulating factor-1 and interleukin-34. | macrophages are integral to amphibian immunity against rvs, as well as to the infection strategies of these pathogens. although csf-1 was considered to be the principal mediator of macrophage development, the il-34 cytokine, which shares no sequence identity with csf-1, is now believed to contribute to vertebrate monopoiesis. however, the respective roles of csf-1- and il-34-derived macrophages are still poorly understood. to delineate the contribution of these macrophage populations to amphibia ... | 2014 | 25190077 |
| diverse functions of kindlin/fermitin proteins during embryonic development in xenopus laevis. | the kindlin/fermitin family includes three proteins involved in regulating integrin ligand-binding activity and adhesion. loss-of-function mutations in kindlins1 and 3 have been implicated in kindler syndrome and leukocyte adhesion deficiency iii (lad-iii) respectively, whereas kindlin2 null mice are embryonic lethal. post translational regulation of cell-cell and cell-ecm adhesion has long been presumed to be important for morphogenesis, however, few specific examples of activation-dependent ch ... | 2014 | 25173804 |
| electrophysiological characterization of human na⁺/taurocholate cotransporting polypeptide (hntcp) heterologously expressed in xenopus laevis oocytes. | the na(+)/taurocholate cotransporting polypeptide (ntcp) plays a major role in na(+)-dependent bile acid uptake into hepatocytes. the purpose of the present study was to establish the heterologous expression of human ntcp (hntcp) in xenopus laevis oocytes and to elucidate whether the transport of bile acid via hntcp is electrogenic using electrophysiological techniques. first, we evaluated the uptake of taurocholate (tca) by hntcp heterologously expressed in xenopus oocytes utilizing [(3)h]-labe ... | 2014 | 25168282 |
| a cycloartane glycoside derived from actaea racemosa l. modulates gabaa receptors and induces pronounced sedation in mice. | 23-o-acetylshengmanol 3-o-β-d-xylopyranoside (ac-sm) isolated from actaea racemosa l.-an herbal remedy for the treatment of mild menopausal disorders-has been recently identified as a novel efficacious modulator of gabaa receptors composed of α1-, β2-, and γ2s-subunits. in the present study, we analyzed a potential subunit-selective modulation of gaba-induced chloride currents (igaba) at gaba concentrations eliciting 3-8% of the maximal gaba response (ec3-8) through nine gabaa receptor isoforms ... | 2014 | 25161170 |
| evaluating the teratogenicity of ritodrine and nifedipine using a frog embryo teratogenesis assay (fetax). | the frog embryo teratogenesis assay-xenopus (fetax) was used to assess the teratogenic potential of two tocolytics. embryos of the south african clawed frog, xenopus laevis, were exposed to ritodrine or nifedipine. exposure media were changed and monitored at 24-hour intervals. the 96-hour lc50 (lethal concentration), the 96-hour ec50 (malformation), and the no observable adverse effect concentrations (noaec) and the lowest observable adverse effect concentration (loaec) for mortality, malformat ... | 2015 | 25156158 |
| ancient origins and evolutionary conservation of intracellular and neural signaling pathways engaged by the leptin receptor. | in mammals, leptin acts on leptin receptor (lepr) -expressing neurons in the brain to suppress food intake and stimulate whole-body metabolism. a similar action of leptin on food intake has been reported in the frog xenopus laevis and in several bony fishes. however, the intracellular signaling and neural pathways by which leptin regulates energy balance have not been investigated outside of mammals. using reporter assays and site-directed mutagenesis we show that the frog lepr signals via signa ... | 2014 | 25153147 |
| correlative super-resolution fluorescence and electron microscopy of the nuclear pore complex with molecular resolution. | here, we combine super-resolution fluorescence localization microscopy with scanning electron microscopy to map the position of proteins of nuclear pore complexes in isolated xenopus laevis oocyte nuclear envelopes with molecular resolution in both imaging modes. we use the periodic molecular structure of the nuclear pore complex to superimpose direct stochastic optical reconstruction microscopy images with a precision of <20 nm on electron micrographs. the correlative images demonstrate quantit ... | 2014 | 25146397 |
| a di-arginine er retention signal regulates trafficking of hcn1 channels from the early secretory pathway to the plasma membrane. | hyperpolarization-activated cyclic nucleotide-gated 1 (hcn1) channels carry ih, which contributes to neuronal excitability and signal transmission in the nervous system. controlling the trafficking of hcn1 is an important aspect of its regulation, yet the details of this process are poorly understood. here, we investigated how the c-terminus of hcn1 regulates trafficking by testing for its ability to redirect the localization of a non-targeted reporter in transgenic xenopus laevis photoreceptors ... | 2015 | 25142030 |
| cpkc regulates interphase nuclear size during xenopus development. | dramatic changes in cell and nuclear size occur during development and differentiation, and aberrant nuclear size is associated with many disease states. however, the mechanisms that regulate nuclear size are largely unknown. a robust system for investigating nuclear size is early xenopus laevis development, during which reductions in nuclear size occur without changes in dna content. to identify cellular factors that regulate nuclear size during development, we developed a novel nuclear resizin ... | 2014 | 25135933 |
| sirtuin inhibitor ex-527 causes neural tube defects, ventral edema formations, and gastrointestinal malformations in xenopus laevis embryos. | chemical reagent ex-527 is widely used as a major inhibitor of sirtuin enzymes, which are a family of highly conserved protein deacetylases and have been linked with caloric restriction and aging by modulating energy metabolism, genomic stability, and stress resistance. however, the extent to which ex-527 controls early developmental events of vertebrate embryos remains to be understood. here, we report an examination of ex-527 effects during xenopus early development, followed by a confirmation ... | 2014 | 25131500 |
| targeting of viral capsids to nuclear pores in a cell-free reconstitution system. | many viruses deliver their genomes into the nucleoplasm for viral transcription and replication. here, we describe a novel cell-free system to elucidate specific interactions between viruses and nuclear pore complexes (npcs). nuclei reconstituted in vitro from egg extracts of xenopus laevis, an established biochemical system to decipher nuclear functions, were incubated with gfp-tagged capsids of herpes simplex virus, an alphaherpesvirus replicating in the nucleus. capsid binding to npcs was ana ... | 2014 | 25131140 |
| clonal relationships impact neuronal tuning within a phylogenetically ancient vertebrate brain structure. | understanding how neurons acquire specific response properties is a major goal in neuroscience. recent studies in mouse neocortex have shown that "sister neurons" derived from the same cortical progenitor cell have a greater probability of forming synaptic connections with one another and are biased to respond to similar sensory stimuli. however, it is unknown whether such lineage-based rules contribute to functional circuit organization across different species and brain regions. to address thi ... | 2014 | 25127219 |
| cathepsin s causes inflammatory pain via biased agonism of par2 and trpv4. | serine proteases such as trypsin and mast cell tryptase cleave protease-activated receptor-2 (par2) at r(36)↓s(37) and reveal a tethered ligand that excites nociceptors, causing neurogenic inflammation and pain. whether proteases that cleave par2 at distinct sites are biased agonists that also induce inflammation and pain is unexplored. cathepsin s (cat-s) is a lysosomal cysteine protease of antigen-presenting cells that is secreted during inflammation and which retains activity at extracellular ... | 2014 | 25118282 |
| ion conduction and selectivity in acid-sensing ion channel 1. | the ability of acid-sensing ion channels (asics) to discriminate among cations was assessed based on changes in conductance and reversal potential with ion substitution. human asic1a was expressed in xenopus laevis oocytes, and acid-induced currents were measured using two-electrode voltage clamp. replacement of extracellular na(+) with li(+), k(+), rb(+), or cs(+) altered inward conductance and shifted the reversal potentials consistent with a selectivity sequence of li ∼ na > k > rb > cs. perm ... | 2014 | 25114023 |
| wnk-spak-ncc cascade revisited: wnk1 stimulates the activity of the na-cl cotransporter via spak, an effect antagonized by wnk4. | the with-no-lysine (k) kinases, wnk1 and wnk4, are key regulators of blood pressure. their mutations lead to familial hyperkalemic hypertension (fhht), associated with an activation of the na-cl cotransporter (ncc). although it is clear that wnk4 mutants activate ncc via ste20 proline-alanine-rich kinase, the mechanisms responsible for wnk1-related fhht and alterations in ncc activity are not as clear. we tested whether wnk1 modulates ncc through wnk4, as predicted by some models, by crossing ou ... | 2014 | 25113964 |
| label-free real-time imaging of myelination in the xenopus laevis tadpole by in vivo stimulated raman scattering microscopy. | the myelin sheath plays an important role as the axon in the functioning of the neural system, and myelin degradation is a hallmark pathology of multiple sclerosis and spinal cord injury. electron microscopy, fluorescent microscopy, and magnetic resonance imaging are three major techniques used for myelin visualization. however, microscopic observation of myelin in living organisms remains a challenge. using a newly developed stimulated raman scattering microscopy approach, we report noninvasive ... | 2014 | 25104411 |
| casein kinase 1 α phosphorylates the wnt regulator jade-1 and modulates its activity. | tight regulation of wnt/β-catenin signaling is critical for vertebrate development and tissue maintenance, and deregulation can lead to a host of disease phenotypes, including developmental disorders and cancer. proteins associated with primary cilia and centrosomes have been demonstrated to negatively regulate canonical wnt signaling in interphase cells. the plant homeodomain zinc finger protein jade-1 can act as an e3 ubiquitin ligase-targeting β-catenin for proteasomal degradation and concent ... | 2014 | 25100726 |
| the domain interface of the human glutamate transporter eaat1 mediates chloride permeation. | the concentration of glutamate within the glutamatergic synapse is tightly regulated by the excitatory amino-acid transporters (eaats). in addition to their primary role of clearing extracellular glutamate, the eaats also possess a thermodynamically uncoupled cl(-) conductance. several crystal structures of an archaeal eaat homolog, gltph, at different stages of the transport cycle have been solved. in a recent structure, an aqueous cavity located at the interface of the transport and trimerizat ... | 2014 | 25099801 |
| activation, permeability, and inhibition of astrocytic and neuronal large pore (hemi)channels. | astrocytes and neurons express several large pore (hemi)channels that may open in response to various stimuli, allowing fluorescent dyes, ions, and cytoplasmic molecules such as atp and glutamate to permeate. several of these large pore (hemi)channels have similar characteristics with regard to activation, permeability, and inhibitor sensitivity. consequently, their behaviors and roles in astrocytic and neuronal (patho)physiology remain undefined. we took advantage of the xenopus laevis expressi ... | 2014 | 25086040 |
| temperature-independent energy expenditure in early development of the african clawed frog xenopus laevis. | the thermal dissipation of activated eggs and embryos undergoing development from cleavage to the tailbud stage of the african clawed frog xenopus laevis was measured as a function of incubation time at temperatures ranging from t = 288.2 k to 295.2 k, using a high-precision isothermal calorimeter. a23187-mediated activation of mature eggs induced stable periodic thermal oscillations lasting for 8-34 h. the frequency agreed well with the cell cycle frequency of initial cleavages at the identical ... | 2014 | 25078857 |
| the molecular mechanism of intestinal levodopa absorption and its possible implications for the treatment of parkinson's disease. | levodopa (l-dopa) is the naturally occurring precursor amino acid for dopamine and the main therapeutic agent for neurologic disorders due to dopamine depletion, such as parkinson's disease. l-dopa absorption in small intestine has been suggested to be mediated by the large neutral amino acids transport machinery, but the identity of the involved transporters is unknown. clinically, coadministration of l-dopa and dietary amino acids is avoided to decrease competition for transport in intestine a ... | 2014 | 25073474 |
| radial intercalation is regulated by the par complex and the microtubule-stabilizing protein clamp/spef1. | the directed movement of cells is critical for numerous developmental and disease processes. a developmentally reiterated form of migration is radial intercalation; the process by which cells move in a direction orthogonal to the plane of the tissue from an inner layer to an outer layer. we use the radial intercalation of cells into the skin of xenopus laevis embryos as a model to study directed cell migration within an epithelial tissue. we identify a novel function for both the microtubule-bin ... | 2014 | 25070955 |
| tpx2 levels modulate meiotic spindle size and architecture in xenopus egg extracts. | the spindle segregates chromosomes in dividing eukaryotic cells, and its assembly pathway and morphology vary across organisms and cell types. we investigated mechanisms underlying differences between meiotic spindles formed in egg extracts of two frog species. small xenopus tropicalis spindles resisted inhibition of two factors essential for assembly of the larger xenopus laevis spindles: rangtp, which functions in chromatin-driven spindle assembly, and the kinesin-5 motor eg5, which drives ant ... | 2014 | 25070954 |
| accumulation of heme oxygenase-1 (hsp32) in xenopus laevis a6 kidney epithelial cells treated with sodium arsenite, cadmium chloride or proteasomal inhibitors. | the present study examined the effect of sodium arsenite, cadmium chloride, heat shock and the proteasomal inhibitors mg132, withaferin a and celastrol on heme oxygenase-1 (ho-1; also known as hsp32) accumulation in xenopus laevis a6 kidney epithelial cells. immunoblot analysis revealed that ho-1 accumulation was not induced by heat shock but was enhanced by sodium arsenite and cadmium chloride in a dose- and time-dependent fashion. immunocytochemistry revealed that these metals induced ho-1 acc ... | 2014 | 25064141 |
| global absolute quantification reveals tight regulation of protein expression in single xenopus eggs. | while recent developments in genomic sequencing technology have enabled comprehensive transcriptome analyses of single cells, single cell proteomics has thus far been restricted to targeted studies. here, we perform global absolute protein quantification of fertilized xenopus laevis eggs using mass spectrometry-based proteomics, quantifying over 5800 proteins in the largest single cell proteome characterized to date. absolute protein amounts in single eggs are highly consistent, thus indicating ... | 2014 | 25056316 |
| potential protective effect of l-cysteine against the toxicity of acrylamide and furan in exposed xenopus laevis embryos: an interaction study. | the embryo toxicities of two food-processing-induced toxic compounds, acrylamide and furan, with and without added l-cysteine were examined individually and in mixtures using the frog embryo teratogenesis assay-xenopus (fetax). the following measures of developmental toxicity were used: (a) 96 h lc50, the median concentration causing 50% embryo lethality; (b) 96 h ec50, the median concentration causing 50% malformations of the surviving embryos; and (c) teratogenic index (96 h lc50/96 h ec50), a ... | 2014 | 25055136 |
| cell-mass structures expressing the aromatase gene cyp19a1 lead to ovarian cavities in xenopus laevis. | the african clawed frog, xenopus laevis, has a zz/zw-type sex-determination system. we previously reported that a w-linked gene, dm-w, can determine development as a female. however, the mechanisms of early sex differentiation remain unclear. we used microarrays to screen for genes with sexually dimorphic expression in zz and zw gonads during early sex differentiation in x laevis and found several steroidogenic genes. importantly, the steroid 17α-hydroxylase gene cyp17a1 and the aromatase gene c ... | 2014 | 25051437 |
| functional evaluation of key interactions evident in the structure of the eukaryotic cys-loop receptor glucl. | the publication of the first high-resolution crystal structure of a eukaryotic cys-loop receptor, gluclα, has provided valuable structural information on this important class of ligand-gated ion channels (lgic). however, limited functional data exist for the glucl receptors. before applying the structural insights from glucl to mammalian cys-loop receptors such as nicotinic acetylcholine and gaba receptors, it is important to ensure that established functional features of mammalian cys-loop rece ... | 2014 | 25051140 |
| ire1α knockdown rescues tunicamycin-induced developmental defects and apoptosis in xenopus laevis. | inositol requiring enzyme-1 (ire1) is highly conserved from yeasts to humans. upon endoplasmic reticulum (er) stress, ire1 activates x-box-binding protein 1 (xbp1) by unconventional splicing of xbp1 mrna, which activates unfolded protein response (upr) to restore er homeostasis. in mice, ire1α plays an essential role in extraembryonic tissues. however, its precise action during the early stage of development is unknown. in this study, the gain and loss-of-function analyses were used to investiga ... | 2014 | 25050111 |
| demonstration of proteolytic activation of the epithelial sodium channel (enac) by combining current measurements with detection of cleavage fragments. | the described methods can be used to investigate the effect of proteases on ion channels, receptors, and other plasma membrane proteins heterologously expressed in xenopus laevis oocytes. in combination with site-directed mutagenesis, this approach provides a powerful tool to identify functionally relevant cleavage sites. proteolytic activation is a characteristic feature of the amiloride-sensitive epithelial sodium channel (enac). the final activating step involves cleavage of the channel's γ-s ... | 2014 | 25045853 |
| benzocyclobutane, benzocycloheptane and heptene derivatives as melatonin agonists and antagonists. | two series of analogues were designed, synthesised and evaluated as potential human melatonin type 1 and 2 receptor (hmt1 and hmt2 ) ligands. their biological effects were assessed by a well-established, specific model of melatonin action, the pigment response of xenopus laevis melanophores. compounds containing a benzocyclobutane scaffold and a methoxy group in the "melatonin" orientation were found to be potent agonists, with one of the analogues exhibiting activity comparable to melatonin. in ... | 2014 | 25044938 |
| aromatase, estrogen receptors and brain development in fish and amphibians. | estrogens affect brain development of vertebrates, not only by impacting activity and morphology of existing circuits, but also by modulating embryonic and adult neurogenesis. the issue is complex as estrogens can not only originate from peripheral tissues, but also be locally produced within the brain itself due to local aromatization of androgens. in this respect, teleost fishes are quite unique because aromatase is expressed exclusively in radial glial cells, which represent pluripotent cells ... | 2015 | 25038582 |
| transport of boron by the tassel-less1 aquaporin is critical for vegetative and reproductive development in maize. | the element boron (b) is an essential plant micronutrient, and b deficiency results in significant crop losses worldwide. the maize (zea mays) tassel-less1 (tls1) mutant has defects in vegetative and inflorescence development, comparable to the effects of b deficiency. positional cloning revealed that tls1 encodes a protein in the aquaporin family co-orthologous to known b channel proteins in other species. transport assays show that the tls1 protein facilitates the movement of b and water into ... | 2014 | 25035406 |
| ion selectivity of pore-forming peptides and ion channels measured in xenopus oocytes. | the xenopus laevis oocyte is a widely used system for heterologous expression of exogenous ion channel proteins. they are easy to obtain, mechanically and electrically stable, have a large size, enabling multiple types of electrophysiological recordings: two-electrode voltage clamp, single cell-attached or cell-free patch-clamp and macropatch recordings. the size of an oocyte (1 mm in diameter) also allows for the use of additional electrodes (from 1 to 3) for injection of diverse materials (ca( ... | 2014 | 25023320 |
| berberine attenuates spontaneous action potentials in sinoatrial node cells and the currents of human hcn4 channels expressed in xenopus laevis oocytes. | the present study investigated the electropharmacological effects of a traditional chinese herbal drug, berberine, on the spontaneous activity of sinoatrial nodes (sans) of the rabbit heart and on human hyperpolarization-activated cyclic nucleotide-gated 4 (hhcn4) channels, which are heterologously expressed in xenopus oocytes, and which contribute to pacemaker currents (ifs). a standard microelectrode technique and standard two‑electrode voltage‑clamp recordings were employed to examine the pro ... | 2014 | 25017321 |
| hargreaves does not evaluate nociception following a surgical laparotomy in xenopus leavis frogs. | the present study was performed to determine the effectiveness of the hargreaves test for the evaluation of nociception in frogs, more precisely to determine if cutaneous thresholds to a radiant heat stimulus would increase with analgesics following an abdominal laparotomy performed under general anaesthesia. non breeding female xenopus leavis frogs (3 groups (non-anaesthetized, anaesthetized with tricaine methanesulfonate (ms222), with or without an abdominal laparotomy) were used to evaluate t ... | 2014 | 25016568 |
| nmda receptor structures reveal subunit arrangement and pore architecture. | n-methyl-d-aspartate (nmda) receptors are hebbian-like coincidence detectors, requiring binding of glycine and glutamate in combination with the relief of voltage-dependent magnesium block to open an ion conductive pore across the membrane bilayer. despite the importance of the nmda receptor in the development and function of the brain, a molecular structure of an intact receptor has remained elusive. here we present x-ray crystal structures of the xenopus laevis glun1-glun2b nmda receptor with ... | 2014 | 25008524 |
| transit amplification in the amniote cerebellum evolved via a heterochronic shift in neurod1 expression. | the cerebellum has evolved elaborate foliation in the amniote lineage as a consequence of extensive atoh1-mediated transit amplification in an external germinal layer (egl) comprising granule cell precursors. to explore the evolutionary origin of this layer, we have examined the molecular geography of cerebellar development throughout the life cycle of xenopus laevis. at metamorphic stages xenopus displays a superficial granule cell layer that is not proliferative and expresses both atoh1 and ne ... | 2014 | 25005474 |
| the thymus and skin wound healing in xenopus laevis adults. | the capacity to heal wounds without scars is generally lost during the development in vertebrates. to explore the involvement of cells of the adaptive immune system in a scar-like tissue based repair, we studied the thymus in 15-month-old xenopus after skin incisional wounding. after injury, the organ size significantly increased and marked changes in structure and tnf-α immunoreactivity were detected in the medullary microenvironment when the granulation tissue was present in the repair area. m ... | 2014 | 24998030 |
| evaluation of developmental toxicity and teratogenicity of diclofenac using xenopus embryos. | diclofenac is a non-steroidal anti-inflammatory drug (nsaid) with analgesic and anti-pyretic properties. this compound is therefore used to treat pain, inflammatory disorders, and dysmenorrhea. due to its multimodal mechanism of action and ability to penetrate placenta, diclofenac is known to have undesirable side effects including teratogenicity. however, limited data exist on its teratogenicity, and a detailed investigation regarding harmful effects of this drug during embryogenesis is warrant ... | 2015 | 24992311 |
| revealing transient structures of nucleosomes as dna unwinds. | the modulation of dna accessibility by nucleosomes is a fundamental mechanism of gene regulation in eukaryotes. the nucleosome core particle (ncp) consists of 147 bp of dna wrapped around a symmetric octamer of histone proteins. the dynamics of dna packaging and unpackaging from the ncp affect all dna-based chemistries, but depend on many factors, including dna positioning sequence, histone variants and modifications. although the structure of the intact ncp has been studied by crystallography a ... | 2014 | 24990379 |
| conformational flexibility of the agonist binding jaw of the human p2x3 receptor is a prerequisite for channel opening. | it is assumed that atp induces closure of the binding jaw of ligand-gated p2x receptors, which eventually results in the opening of the membrane channel and the flux of cations. immobilization by cysteine mutagenesis of the binding jaw inhibited atp-induced current responses, but did not allow discrimination between disturbances of binding, gating, subunit assembly or trafficking to the plasma membrane. | 2014 | 24989924 |
| efficacy of tricaine methanesulfonate (ms-222) as an anesthetic agent for blocking sensory-motor responses in xenopus laevis tadpoles. | anesthetics are drugs that reversibly relieve pain, decrease body movements and suppress neuronal activity. most drugs only cover one of these effects; for instance, analgesics relieve pain but fail to block primary fiber responses to noxious stimuli. alternately, paralytic drugs block synaptic transmission at neuromuscular junctions, thereby effectively paralyzing skeletal muscles. thus, both analgesics and paralytics each accomplish one effect, but fail to singularly account for all three. tri ... | 2014 | 24984086 |
| positive allosteric modulation of the ghb high-affinity binding site by the gabaa receptor modulator monastrol and the flavonoid catechin. | γ-hydroxybutyric acid (ghb) is a metabolite of γ-aminobutyric acid (gaba) and a proposed neurotransmitter in the mammalian brain. we recently identified α4βδ gabaa receptors as possible high-affinity ghb targets. gabaa receptors are highly sensitive to allosteric modulation. thus to investigate whether ghb high-affinity binding sites are also sensitive to allosteric modulation, we screened both known gabaa receptor ligands and a library of natural compounds in the rat cortical membrane ghb speci ... | 2014 | 24973695 |
| identification and lateral membrane localization of cyclin m3, likely to be involved in renal mg2+ handling in seawater fish. | the kidney of marine teleosts is the major site of mg(2+) excretion and produces urine with a high mg(2+) concentration. however, the transporters involved in mg(2+) excretion are poorly understood. the cyclin m (cnnm; also known as ancient conserved domain protein) family comprises membrane proteins homologous to the bacterial mg(2+) and co(2+) efflux protein, corc. to understand the molecular mechanism of mg(2+) homeostasis in marine teleosts, we analyzed the expression of the cnnm family gene ... | 2014 | 24965791 |
| tetrabromobisphenol a disrupts vertebrate development via thyroid hormone signaling pathway in a developmental stage-dependent manner. | data concerning effects of tetrabromobisphenol a (tbbpa) on thyroid hormone (th)-dependent vertebrate development have been limited, although tbbpa has been demonstrated in vitro to disrupt the th signaling pathway at the transcriptional level. in this study, we investigated the effects of tbbpa on t3-induced and spontaneous xenopus laevis metamorphosis, which share many similarities with th-dependent development in higher vertebrates. in a 6-day t3-induced metamorphosis assay using premetamorph ... | 2014 | 24963557 |
| changes of statistical structural fluctuations unveils an early compacted degraded stage of pns myelin. | degradation of the myelin sheath is a common pathology underlying demyelinating neurological diseases from multiple sclerosis to leukodistrophies. although large malformations of myelin ultrastructure in the advanced stages of wallerian degradation is known, its subtle structural variations at early stages of demyelination remains poorly characterized. this is partly due to the lack of suitable and non-invasive experimental probes possessing sufficient resolution to detect the degradation. here ... | 2014 | 24962806 |
| a simple behavioral assay for testing visual function in xenopus laevis. | measurement of the visual function in the tadpoles of the frog, xenopus laevis, allows screening for blindness in live animals. the optokinetic response is a vision-based, reflexive behavior that has been observed in all vertebrates tested. tadpole eyes are small so the tail flip response was used as alternative measure, which requires a trained technician to record the subtle response. we developed an alternative behavior assay based on the fact that tadpoles prefer to swim on the white side of ... | 2014 | 24962702 |
| reconstitution of β-catenin degradation in xenopus egg extract. | xenopus laevis egg extract is a well-characterized, robust system for studying the biochemistry of diverse cellular processes. xenopus egg extract has been used to study protein turnover in many cellular contexts, including the cell cycle and signal transduction pathways(1-3). herein, a method is described for isolating xenopus egg extract that has been optimized to promote the degradation of the critical wnt pathway component, β-catenin. two different methods are described to assess β-catenin p ... | 2014 | 24962160 |
| actions of hydrogen sulfide on sodium transport processes across native distal lung epithelia (xenopus laevis). | hydrogen sulfide (h2s) is well known as a highly toxic environmental chemical threat. prolonged exposure to h2s can lead to the formation of pulmonary edema. however, the mechanisms of how h2s facilitates edema formation are poorly understood. since edema formation can be enhanced by an impaired clearance of electrolytes and, consequently, fluid across the alveolar epithelium, it was questioned whether h2s may interfere with transepithelial electrolyte absorption. electrolyte absorption was elec ... | 2014 | 24960042 |
| deep proteomics of the xenopus laevis egg using an mrna-derived reference database. | mass spectrometry-based proteomics enables the global identification and quantification of proteins and their posttranslational modifications in complex biological samples. however, proteomic analysis requires a complete and accurate reference set of proteins and is therefore largely restricted to model organisms with sequenced genomes. | 2014 | 24954049 |
| annotation of loci from genome-wide association studies using tissue-specific quantitative interaction proteomics. | genome-wide association studies (gwas) have identified thousands of loci associated with complex traits, but it is challenging to pinpoint causal genes in these loci and to exploit subtle association signals. we used tissue-specific quantitative interaction proteomics to map a network of five genes involved in the mendelian disorder long qt syndrome (lqts). we integrated the lqts network with gwas loci from the corresponding common complex trait, qt-interval variation, to identify candidate gene ... | 2014 | 24952909 |
| nucleosomal regulation of chromatin composition and nuclear assembly revealed by histone depletion. | nucleosomes are the fundamental unit of chromatin, but analysis of transcription-independent nucleosome functions has been complicated by the gene-expression changes resulting from histone manipulation. here we solve this dilemma by developing xenopus laevis egg extracts deficient for nucleosome formation and by analyzing the proteomic landscape and behavior of nucleosomal chromatin and nucleosome-free dna. we show that although nucleosome-free dna can recruit nuclear-envelope membranes, nucleos ... | 2014 | 24952593 |
| motion based x-ray imaging modality. | a new x-ray imaging method (patent pending) was developed to visualize function-related motion information. we modify existing x-ray imaging methods to provide four images without increasing the necessary measurement time or radiation dose. the most important of these images is a new "kinetic" image that represents motions inside the object or living body. the motion-based contrast of the kinetic image can help visualize details that were not accessible before. the broad range of the movements a ... | 2014 | 24951684 |
| the transport mechanism of the human sodium/myo-inositol transporter 2 (smit2/sglt6), a member of the leut structural family. | the sodium/myo-inositol transporter 2 (smit2) is a member of the slc5a gene family, which is believed to share the five-transmembrane segment inverted repeat of the leut structural family. the two-electrode voltage-clamp (tevc) technique was used to measure the steady-state and the pre-steady-state currents mediated by human smit2 after expression in xenopus laevis oocytes. phlorizin is first shown to be a poor inhibitor of pre-steady-state currents for depolarizing voltage pulse. from an up to ... | 2014 | 24944204 |
| diuresis by intravenous administration of xanthurenic acid in rats, and inhibition by probenecid. | the conjugates with sulfate and glucoside of xanthurenic acid, a tryptophan metabolite, were reported to show natriuresis. sulfotransferase for xanthurenic acid works in the renal proximal tubule to produce the sulfate of xanthurenic acid as well as the liver, and we recently found that xanthurenic acid is a substrate of renal organic anion transporter oat1. the purpose of this study was to examine relationship between the transport by oat1 and diuresis related with xanthurenic acid. drug transp ... | 2014 | 24942862 |
| functional analysis of human na(+)/k(+)-atpase familial or sporadic hemiplegic migraine mutations expressed in xenopus oocytes. | functional characterization of atp1a2 mutations that are related to familial or sporadic hemiplegic migraine (fhm2, shm). | 2014 | 24921013 |
| wnk3 abrogates the nedd4-2-mediated inhibition of the renal na+-cl- cotransporter. | the serine/threonine kinase wnk3 and the ubiquitin-protein ligase nedd4-2 are key regulators of the thiazide-sensitive na+-cl- cotransporter (ncc), wnk3 as an activator and nedd2-4 as an inhibitor. nedd4-2 was identified as an interacting partner of wnk3 through a glutathione-s-transferase pull-down assay using the n-terminal domain of wnk3, combined with lc-ms/ms analysis. this was validated by coimmunoprecipitation of wnk3 and nedd4-2 expressed in hek293 cells. our data also revealed that the ... | 2014 | 24920754 |
| submembrane assembly and renewal of rod photoreceptor cgmp-gated channel: insight into the actin-dependent process of outer segment morphogenesis. | the photoreceptor outer segment (os) is comprised of two compartments: plasma membrane (pm) and disk membranes. it is unknown how the pm renewal is coordinated with that of the disk membranes. here we visualized the localization and trafficking process of rod cyclic nucleotide-gated channel α-subunit (cnga1), a pm component essential for phototransduction. the localization was visualized by fusing cnga1 to a fluorescent protein dendra2 and expressing in xenopus laevis rod photoreceptors. dendra2 ... | 2014 | 24920621 |
| generation of endo-sirnas in xenopus laevis oocytes. | endogenous sirnas (endo-sirnas) are well documented and characterized in c. elegans and drosophila. endo-sirnas can also be found in vertebrates; however, their biology is much less clear. they are thought to be produced by dicer and to contribute to transposon silencing. because of their generally low abundance and their similarity with mirnas and products of physiological rna turn-over, endo-sirnas are difficult to investigate. here, we report a system, oocytes from xenopus laevis, that allows ... | 2014 | 24920357 |
| phoretic interaction between the kangaroo leech marsupiobdella africana (hirudinea: glossiphoniidae) and the cape river crab potamonautes perlatus (decapoda: potamonautidae). | the south african leech marsupiobdella africana is a temporary ectoparasite of the amphibian xenopus laevis, has a phoretic association with a freshwater crab potamonautes perlatus, and exhibits advanced parental care by incubating its offspring in a brood pouch. because phoretic associations are usually regarded to favor the phoront's dispersion, its occurrence within the biology of a parasitic species reflects an intimate context of interactions. in addition to phoresy, attachment to the crab ... | 2014 | 24918071 |
| ncoa4 transcriptional coactivator inhibits activation of dna replication origins. | ncoa4 is a transcriptional coactivator of nuclear hormone receptors that undergoes gene rearrangement in human cancer. by combining studies in xenopus laevis egg extracts and mouse embryonic fibroblasts (mefs), we show here that ncoa4 is a minichromosome maintenance 7 (mcm7)-interacting protein that is able to control dna replication. depletion-reconstitution experiments in xenopus laevis egg extracts indicate that ncoa4 acts as an inhibitor of dna replication origin activation by regulating cmg ... | 2014 | 24910095 |
| sensitisation of trpv4 by par2 is independent of intracellular calcium signalling and can be mediated by the biased agonist neutrophil elastase. | proteolytic activation of protease-activated receptor 2 (par2) may represent a major mechanism of regulating the transient receptor potential vanilloid 4 (trpv4) non-selective cation channel in pathophysiological conditions associated with protease activation (e.g. during inflammation). to provide electrophysiological evidence for par2-mediated trpv4 regulation, we characterised the properties of human trpv4 heterologously expressed in xenopus laevis oocytes in the presence and absence of co-exp ... | 2015 | 24906497 |
| short term exposure to multi-walled carbon nanotubes induce oxidative stress and dna damage in xenopus laevis tadpoles. | the potential impact of multiwalled carbon nanotubes (mwcnts) was investigated on xenopus laevis tadpoles exposed to 0.1, 1 and 10mg/l. oxidative stress was measured in entire larvae exposed and dna damage (comet assay) was carried out in erythrocytes of circulating blood from 2h to 24h according to standardized recommendations. results showed significant h2o2 production when larvae were exposed to 1mg/l and 10mg/l of mwcnts after 4h and 2h of exposure, respectively. antioxidant enzyme activitie ... | 2014 | 24905693 |
| efficient modulation of γ-aminobutyric acid type a receptors by piperine derivatives. | piperine activates trpv1 (transient receptor potential vanilloid type 1 receptor) receptors and modulates γ-aminobutyric acid type a receptors (gabaar). we have synthesized a library of 76 piperine analogues and analyzed their effects on gabaar by means of a two-microelectrode voltage-clamp technique. gabaar were expressed in xenopus laevis oocytes. structure-activity relationships (sars) were established to identify structural elements essential for efficiency and potency. efficiency of piperin ... | 2014 | 24905252 |
| a single codon insertion in picalm is associated with development of familial subvalvular aortic stenosis in newfoundland dogs. | familial subvalvular aortic stenosis (sas) is one of the most common congenital heart defects in dogs and is an inherited defect of newfoundlands, golden retrievers and human children. although sas is known to be inherited, specific genes involved in newfoundlands with sas have not been defined. we hypothesized that sas in newfoundlands is inherited in an autosomal dominant pattern and caused by a single genetic variant. we studied 93 prospectively recruited newfoundland dogs, and 180 control do ... | 2014 | 24898977 |
| a prominent role for invariant t cells in the amphibian xenopus laevis tadpoles. | invariant t (it) cells expressing an invariant or semi-invariant t cell receptor (tcr) repertoire have gained attention in recent years because of their potential as specialized regulators of immune function. these it cells are typically restricted by nonclassical mhc class i molecules (e.g., cd1d and mr1) and undergo differentiation pathways distinct from conventional t cells. while the benefit of a limited tcr repertoire may appear counterintuitive in regard to the advantage of the diversified ... | 2014 | 24898512 |
| metabolic engineering of pichia pastoris for production of hyaluronic acid with high molecular weight. | the high molecular weight (>1 mda) of hyaluronic acid (ha) is important for its biological functions. the reported limiting factors for the production of ha with high molecular weight (mw) by microbial fermentation are the insufficient ha precursor pool and cell growth inhibition. to overcome these issues, the xenopus laevis xhasa2 and xhasb genes encoding hyaluronan synthase 2 (xhasa2) and udp-glucose dehydrogenase (xhasb), were expressed in pichia pastoris widely used for production of heterol ... | 2014 | 24892811 |
| genome-wide expression profile of the response to spinal cord injury in xenopus laevis reveals extensive differences between regenerative and non-regenerative stages. | xenopus laevis has regenerative and non-regenerative stages. as a tadpole, it is fully capable of functional recovery after a spinal cord injury, while its juvenile form (froglet) loses this capability during metamorphosis. we envision that comparative studies between regenerative and non-regenerative stages in xenopus could aid in understanding why spinal cord regeneration fails in human beings. | 2014 | 24885550 |
| retinoic acid induced-1 (rai1) regulates craniofacial and brain development in xenopus. | retinoic acid induced-1 (rai1) is an important yet understudied histone code reader that when mutated in humans results in smith-magenis syndrome (sms), a neurobehavioral disorder accompanied by signature craniofacial abnormalities. despite previous studies in mouse and human cell models, very little is known about the function of rai1 during embryonic development. in the present study, we have turned to the model vertebrates xenopus laevis and xenopus tropicalis to better understand the develop ... | 2014 | 24878353 |
| xenopus cadherin 5 is specifically expressed in endothelial cells of the developing vascular system. | vasculogenesis is an important, multistep process leading to the formation of a functional primary network of blood vessels in the developing embryo. a series of interactions between secreted growth factors and their specific receptors leads to the specification of mesodermal cells to become hemangioblasts, which then differentiate into angioblasts. these subsequently proliferate, coalesce into cords and finally form tubular vascular structures. for proper function of these primary blood vessels ... | 2014 | 24860995 |
| expression pattern of zcchc24 during early xenopus development. | we report the expression pattern of a novel xenopus laevis gene, zcchc24, which encodes a protein containing two zinc finger domains from the zf-cchc and zf-3cxxc superfamilies. this protein shares >84% amino acid identity with its vertebrate homologues. during x. laevis embryonic development, zcchc24 is expressed at gastrula stages in the dorsal mesoderm, including the cardiac precursors region. during neurula stages, zcchc24 is expressed as two stripes in the dorsal region, more precisely, in ... | 2014 | 24860994 |
| gymnemic acids inhibit sodium-dependent glucose transporter 1. | to evaluate the activity of botanicals used in chinese traditional medicine as hypoglycemic agents for diabetes type ii prevention and/or treatment, extracts prepared from 26 medicinal herbs were screened for their inhibitory activity on sodium-dependent glucose transporter 1 (sglt1) by using two-electrode voltage-clamp recording of glucose uptake in xenopus laevis oocytes microinjected with crna for sglt1. showing by far the strongest sglt1 inhibitory effect, the phytochemicals extracted from g ... | 2014 | 24856809 |
| rapid hebbian axonal remodeling mediated by visual stimulation. | we examined how correlated firing controls axon remodeling, using in vivo time-lapse imaging and electrophysiological analysis of individual retinal ganglion cell (rgc) axons that were visually stimulated either synchronously or asynchronously relative to neighboring inputs in the xenopus laevis optic tectum. rgcs stimulated out of synchrony rapidly lost the ability to drive tectal postsynaptic partners while their axons grew and added many new branches. in contrast, synchronously activated rgcs ... | 2014 | 24855269 |
| retrograde intraciliary trafficking of opsin during the maintenance of cone-shaped photoreceptor outer segments of xenopus laevis. | photoreceptor outer segments (oss) are essential for our visual perception, and take either rod or cone forms. the cell biological basis for the formation of rods is well established; however, the mechanism of cone formation is ill characterized. while xenopus rods are called rods, they exhibit cone-shaped oss during the early process of development. to visualize the dynamic reorganization of disk membranes, opsin and peripherin/rds were fused to a fluorescent protein, dendra2, and expressed in ... | 2014 | 24855015 |
| spatiotemporal lipid profiling during early embryo development of xenopus laevis using dynamic tof-sims imaging. | time-of-flight secondary ion mass spectrometry (tof-sims) imaging has been used for the direct analysis of single intact xenopus laevis embryo surfaces, locating multiple lipids during fertilization and the early embryo development stages with subcellular lateral resolution (∼4 μm). the method avoids the complicated sample preparation for lipid analysis of the embryos, which requires selective chemical extraction of a pool of samples and chromatographic separation, while preserving the spatial d ... | 2014 | 24852167 |
| male-male clasping may be part of an alternative reproductive tactic in xenopus laevis. | male xenopus laevis frogs have been observed to clasp other males in a sustained, amplectant position, the purpose of which is unknown. we examined three possible hypotheses for this counter-intuitive behavior: 1) clasping males fail to discriminate the sex of the frogs they clasp; 2) male-male clasping is an aggressive or dominant behavior; or 3) that males clasp other males to gain proximity to breeding events and possibly engage in sperm competition. our data, gathered through a series of beh ... | 2014 | 24849114 |
| proteolytic activation of the human epithelial sodium channel by trypsin iv and trypsin i involves distinct cleavage sites. | proteolytic activation is a unique feature of the epithelial sodium channel (enac). however, the underlying molecular mechanisms and the physiologically relevant proteases remain to be identified. the serine protease trypsin i can activate enac in vitro but is unlikely to be the physiologically relevant activating protease in enac-expressing tissues in vivo. herein, we investigated whether human trypsin iv, a form of trypsin that is co-expressed in several extrapancreatic epithelial cells with e ... | 2014 | 24841206 |
| anillin regulates cell-cell junction integrity by organizing junctional accumulation of rho-gtp and actomyosin. | anillin is a scaffolding protein that organizes and stabilizes actomyosin contractile rings and was previously thought to function primarily in cytokinesis [1-10]. using xenopus laevis embryos as a model system to examine anillin's role in the intact vertebrate epithelium, we find that a population of anillin surprisingly localizes to epithelial cell-cell junctions throughout the cell cycle, whereas it was previously thought to be nuclear during interphase [5, 11]. furthermore, we show that anil ... | 2014 | 24835458 |
| mutant elovl4 that causes autosomal dominant stargardt-3 macular dystrophy is misrouted to rod outer segment disks. | autosomal dominant stargardt macular dystrophy caused by mutations in the elongation of very long chain fatty acids (elovl4) gene results in macular degeneration, leading to early childhood blindness. transgenic mice and pigs expressing mutant elovl4 develop progressive photoreceptor degeneration. the mechanism by which these mutations cause macular degeneration remains unclear, but have been hypothesized to involve the loss of an er-retention dilysine motif located in the extreme c-terminus. do ... | 2014 | 24833735 |