| control of timing of embryonic m-phase entry and exit is differentially sensitive to cdk1 and pp2a balance. | harmonious embryo development requires precise coordination between the timing of the cell cycle and the developmental program. cyclin accumulation determines the timing of the cell cycle m-phase entry and its degradation determines the timing of the m-phase exit. it is well known that cdk1 and pp2a also govern m-phase entry. however, it is unknown how this kinase and phosphatase regulate the precise timing of events at the beginning of the m-phase and how they cooperate with cyclin metabolism. ... | 2014 | 26154318 |
| epigenetic regulation of thyroid hormone-induced adult intestinal stem cell development during anuran metamorphosis. | epigenetic modifications of histones are emerging as key factors in gene regulation by diverse transcription factors. their roles during vertebrate development and pathogenesis are less clear. the causative effect of thyroid hormone (t3) on amphibian metamorphosis and the ability to manipulate this process for molecular and genetic studies have led to the demonstration that t3 receptor (tr) is necessary and sufficient for xenopus metamorphosis, a process that resembles the postembryonic developm ... | 2014 | 25937894 |
| developmental expression of pitx2c in xenopus trigeminal and profundal placodes. | cranial placodes are thickenings of the embryonic head ectoderm that contribute to the paired sense organs and to the cephalic peripheral nervous system. here we report the spatiotemporal expression pattern of transcription factor pitx2c during xenopus laevis cranial placode formation, focusing more specifically on key stages of trigeminal and profundal placode development. we also compare its expression to five genes that have been associated with development of these sensory placodes, namely f ... | 2014 | 25896206 |
| pparβ interprets a chromatin signature of pluripotency to promote embryonic differentiation at gastrulation. | epigenetic post-transcriptional modifications of histone tails are thought to help in coordinating gene expression during development. an epigenetic signature is set in pluripotent cells and interpreted later at the onset of differentiation. in pluripotent cells, epigenetic marks normally associated with active genes (h3k4me3) and with silent genes (h3k27me3) atypically co-occupy chromatin regions surrounding the promoters of important developmental genes. however, it is unclear how these epigen ... | 2013 | 24367589 |
| environmental (anti-)androgenic chemicals affect germinal vesicle breakdown (gvbd) of xenopus laevis oocytes in vitro. | progesterone-induced germinal vesicle breakdown (gvbd) of xenopus oocytes in vitro was used to study endocrine disrupting activity of chemicals in previous studies. in this study, we investigated for the first time effects of environmental androgens on oocyte maturation and effects of anti-androgens on androgen-induced oocyte maturation, using xenopus gvbd in vitro. trenbolone and nandrolone, two environmental androgens, were found to induce xenopus gvbd at low concentrations. the potential of t ... | 2014 | 24362045 |
| pax3 and zic1 trigger the early neural crest gene regulatory network by the direct activation of multiple key neural crest specifiers. | neural crest development is orchestrated by a complex and still poorly understood gene regulatory network. premigratory neural crest is induced at the lateral border of the neural plate by the combined action of signaling molecules and transcription factors such as ap2, gbx2, pax3 and zic1. among them, pax3 and zic1 are both necessary and sufficient to trigger a complete neural crest developmental program. however, their gene targets in the neural crest regulatory network remain unknown. here, t ... | 2014 | 24360906 |
| optimizing plant transporter expression in xenopus oocytes. | rapid improvements in dna synthesis technology are revolutionizing gene cloning and the characterization of their encoded proteins. xenopus laevis oocytes are a commonly used heterologous system for the expression and functional characterization of membrane proteins. for many plant proteins, particularly transporters, low levels of expression can limit functional activity in these cells making it difficult to characterize the protein. improvements in synthetic dna technology now make it quick, e ... | 2013 | 24359672 |
| developmental expression and role of kinesin eg5 during xenopus laevis embryogenesis. | the neural crest is a transient multipotent migratory cell population unique to vertebrates. these cells undergo an epithelial-to-mesenchymal transition and migrate extensively through the embryo. they differentiate into numerous diverse derivatives including the peripheral nervous system, melanocytes,and craniofacial cartilages. the development of the neural crest is mediated by complex interactions of multiple signals and transcription factors. the kinesin eg5 is a plus end-directed microtubul ... | 2014 | 24357413 |
| the role of sdf-1α signaling in xenopus laevis somite morphogenesis. | stromal derived factor-1α (sdf-1α), a chemoattractant chemokine, plays a major role in tumor growth, angiogenesis, metastasis, and in embryogenesis. the sdf-1α signaling pathway has also been shown to be important for somite rotation in zebrafish (hollway et al., 2007). given the known similarities and differences between zebrafish and xenopus laevis somitogenesis, we sought to determine whether the role of sdf-1α is conserved in xenopus laevis. | 2014 | 24357195 |
| nicotine decreases the activity of glutamate transporter type 3. | nicotine, the main ingredient of tobacco, elicits seizures in animal models and cigarette smoking is regarded as a behavioral risk factor associated with epilepsy or seizures. in the hippocampus, the origin of nicotine-induced seizures, most glutamate uptake could be performed primarily by excitatory amino acid transporter type 3 (eaat3). an association between temporal lobe epilepsy and eaat3 downregulation has been reported. therefore, we hypothesized that nicotine may elicit seizures through ... | 2014 | 24355585 |
| regulation of α-endosulfine, an inhibitor of protein phosphatase 2a, by multisite phosphorylation. | progression into m phase requires inhibition of heterotrimeric pp2a containing the regulatory b55 subunit (pp2a-b55) as well as the activation of cyclin-dependent kinase 1 (cdk1). α-endosulfine (ensa)/cyclic amp-regulated 19 kda phosphoprotein (arpp-19) family proteins phosphorylated at s67 by greatwall kinase bind and inhibit pp2a-b55. this study shows that endogenous kinases phosphorylate not only s67 but also two additional sites in ensa (t28 and s109) with different kinetics at different cel ... | 2014 | 24354984 |
| simultaneous in vitro characterisation of dna deaminase function and associated dna repair pathways. | during immunoglobulin (ig) diversification, activation-induced deaminase (aid) initiates somatic hypermutation and class switch recombination by catalysing the conversion of cytosine to uracil. the synergy between aid and dna repair pathways is fundamental for the introduction of mutations, however the molecular and biochemical mechanisms underlying this process are not fully elucidated. we describe a novel method to efficiently decipher the composition and activity of dna repair pathways that a ... | 2013 | 24349193 |
| islet-1 immunoreactivity in the developing retina of xenopus laevis. | the lim-homeodomain transcription factor islet1 (isl1) has been widely used as a marker of neuronal differentiation in the developing visual system of different classes of vertebrates, including mammals, birds, reptiles, and fish. in the present study, we analyzed the spatial and temporal distribution of isl1-immunoreactive cells during xenopus laevis retinal development and its relation to the formation of the retinal layers, and in combination with different markers of cell differentiation. th ... | 2013 | 24348185 |
| in vivo full-field en face correlation mapping optical coherence tomography. | a full-field optical coherence tomography (oct) system has been developed for the purpose of performing nonscanning en face flow imaging. the light source is centered at 840 nm with a bandwidth of 50 nm resulting in an axial resolution of 8 μm in air. microscope objectives with a numerical aperture of 0.1 were incorporated giving a transverse resolution of 5 μm. a magnification of 5.65 was measured, resulting in a field of view of 1260×945 μm. pairs of interference fringe images are captured wi ... | 2013 | 24343439 |
| plasticity of lung development in the amphibian, xenopus laevis. | contrary to previous studies, we found that xenopus laevis tadpoles raised in normoxic water without access to air can routinely complete metamorphosis with lungs that are either severely stunted and uninflated or absent altogether. this is the first demonstration that lung development in a tetrapod can be inhibited by environmental factors and that a tetrapod that relies significantly on lung respiration under unstressed conditions can be raised to forego this function without adverse effects. ... | 2013 | 24337117 |
| molecular and functional characterization of multiple aquaporin water channel proteins from the western tarnished plant bug, lygus hesperus. | aquaporins (aqps) are integral membrane channel proteins that facilitate the bidirectional transfer of water or other small solutes across biological membranes involved in numerous essential physiological processes. in arthropods, aqps belong to several subfamilies, which contribute to osmoregulation, respiration, cryoprotection, anhydrobiosis, and excretion. we cloned and characterized five novel aqps from the western tarnished plant bug, lygus hesperus, a polyphagous insect pest of food and fi ... | 2014 | 24333473 |
| product formation controlled by substrate dynamics in leukotriene a4 hydrolase. | leukotriene a4 hydrolase/aminopeptidase (lta4h) (ec 3.3.2.6) is a bifunctional zinc metalloenzyme with both an epoxide hydrolase and an aminopeptidase activity. lta4h from the african claw toad, xenopus laevis (xllta4h) has been shown to, unlike the human enzyme, convert lta4 to two enzymatic metabolites, ltb4 and another biologically active product δ(6)-trans-δ(8)-cis-ltb4 (5(s),12r-dihydroxy-6,10-trans-8,14-cis-eicosatetraenoic acid). in order to study the molecular aspect of the formation of ... | 2014 | 24333438 |
| expression, purification, and projection structure by single particle electron microscopy of functional human trpm4 heterologously expressed in xenopus laevis oocytes. | despite efforts implicating the cationic channel transient receptor potential melastatin member 4 (trpm4) to cardiac, nervous, and immunological pathologies, little is known about its structure and function. in this study, we optimized the requirements for purification and extraction of functional human trpm4 protein and investigated its supra-molecular assembly. we selected the xenopus laevis oocyte expression system because it lacks endogenous trpm4 expression, it is known to overexpress funct ... | 2014 | 24333049 |
| light-activated serotonin for exploring its action in biological systems. | serotonin (5-ht) is a neuromodulator involved in regulating mood, appetite, memory, learning, pain, and establishment of left-right (lr) asymmetry in embryonic development. to explore the role of 5-ht in physiology, we have created two forms of "caged" 5-ht, bhq-o-5ht and bhq-n-5ht. when exposed to 365 or 740 nm light, bhq-o-5ht releases 5-ht through one- or two-photon excitation, respectively. bhq-o-5ht mediated changes in neural activity in cultured mouse primary sensory neurons and the trigem ... | 2013 | 24333002 |
| targeted mutagenesis of multiple and paralogous genes in xenopus laevis using two pairs of transcription activator-like effector nucleases. | transcription activator-like effector nucleases (talens) have been extensively used in genome editing in various organisms. in some cases, however, it is difficult to efficiently disrupt both paralogous genes using a single pair of talens in xenopus laevis because of its polyploidy. here, we report targeted mutagenesis of multiple and paralogous genes using two pairs of talens in x. laevis. first, we show simultaneous targeted mutagenesis of three genes, tyrosinase paralogues (tyra and tyrb) and ... | 2014 | 24329851 |
| chimeric herg channels containing a tetramerization domain are functional and stable. | biochemical and detailed structural information of human ether-a-go-go-related gene (herg) potassium channels are scarce but are a prerequisite to understand the unwanted interactions of herg with drugs and the effect of mutations that lead to long qt syndrome. despite the huge interest in herg, to our knowledge, procedures that provide a purified, functional, and tetrameric herg channel are not available. here, we describe hybrid herg molecules, termed chimeric herg channels, in which the n-ter ... | 2013 | 24325597 |
| scaling of dorsal-ventral patterning in the xenopus laevis embryo. | scaling of pattern with size has been described and studied for over a century, yet its molecular basis is understood in only a few cases. in a recent, elegant study, inomata and colleagues proposed a new model explaining how bone morphogenic protein (bmp) activity gradient scales with embryo size in the early xenopus laevis embryo. we discuss their results in conjunction with an alternative model we proposed previously. the expansion-repression mechanism (exr) provides a conceptual framework un ... | 2014 | 24323952 |
| microvascularization and histomorphology of lateral line organs in adult xenopus laevis. | the microvasculariaztion of the lateral line organs (llos) of the adult pipid frog, xenopus laevis was studied by scanning electron microscopy of vascular corrosion casts (vccs) and correlative light microscopy of paraplast embedded tissues sections. scanning electron micrographs of vccs revealed that each neuromast within the llo rests on a distinct bowl-like capillary network (vascular bowl). one to three vascular bowls were supplied by an ascending arteriole and drained by a descending venule ... | 2014 | 24323840 |
| dominant-negative effects of kcnq2 mutations are associated with epileptic encephalopathy. | mutations in kcnq2 and kcnq3, encoding the voltage-gated potassium channels kv 7.2 and kv 7.3, are known to cause benign familial neonatal seizures mainly by haploinsufficiency. here, we set out to determine the disease mechanism of 7 de novo missense kcnq2 mutations that were recently described in patients with a severe epileptic encephalopathy including pharmacoresistant seizures and pronounced intellectual disability. | 2014 | 24318194 |
| kidins220/arms is dynamically expressed during xenopus laevis development. | kidins220 (kinase d interacting substrate of 220 kda)/arms (ankyrin repeat-rich membrane spanning) is a conserved scaffold protein that acts as a downstream substrate for protein kinase d and mediates multiple receptor signalling pathways. despite the dissecting of the function of this protein in mammals, using both in vitro and in vivo studies, a detailed characterization of its gene expression during early phases of embryogenesis has not been described yet. here, we have used xenopus laevis as ... | 2013 | 24307304 |
| unraveling new roles for serotonin receptor 2b in development: key findings from xenopus. | the serotonin receptor 5-ht2b has been shown to be critically important during embryogenesis as the knockout of this gene in mice causes heart defects and embryonic lethality that impairs further analyses on other embryonic cell and tissue types. in the present review, we highlight how the use of xenopus laevis, an alternative vertebrate model suitable for gene loss and gain of function analyses, has contributed to our understanding of the role of 5-ht2b signaling during development. in vivo stu ... | 2013 | 24307299 |
| functional properties of human ferroportin, a cellular iron exporter reactive also with cobalt and zinc. | iron homeostasis is achieved by regulating the intestinal absorption of the metal and its recycling by macrophages. iron export from enterocytes or macrophages to blood plasma is thought to be mediated by ferroportin under the control of hepcidin. although ferroportin was identified over a decade ago, little is understood about how it works. we expressed in xenopus oocytes a human ferroportin-enhanced green fluorescent protein fusion protein and observed using confocal microscopy its exclusive p ... | 2014 | 24304836 |
| the pungent substances piperine, capsaicin, 6-gingerol and polygodial inhibit the human two-pore domain potassium channels task-1, task-3 and tresk. | for a long time, the focus of trigeminal chemoperception has rested almost exclusively on trp channels. however, two-pore domain (k2p) potassium channels have recently been identified as targets for substances associated with typical trigeminal sensations, such as numbing and tingling. in addition, they have been shown to be modulated by several trp agonists. we investigated whether the pungent substances piperine, capsaicin, 6-gingerol and polygodial have an effect on human k2p channels. for th ... | 2013 | 24302912 |
| multiple mechanisms determine er network morphology during the cell cycle in xenopus egg extracts. | in metazoans the endoplasmic reticulum (er) changes during the cell cycle, with the nuclear envelope (ne) disassembling and reassembling during mitosis and the peripheral er undergoing extensive remodeling. here we address how er morphology is generated during the cell cycle using crude and fractionated xenopus laevis egg extracts. we show that in interphase the er is concentrated at the microtubule (mt)-organizing center by dynein and is spread by outward extension of er tubules through their a ... | 2013 | 24297752 |
| restriction of the xenopus deadsouth mrna to the primordial germ cells is ensured by multiple mechanisms. | deadsouth mrna encoding the rna helicase ddx25 is a component of the germ plasm in xenopus laevis. we investigated the mechanisms underlying its specific mrna expression in primordial germ cells (pgcs). based on our previous findings of several microrna mir-427 recognition elements (mres) in the 3' untranslated region of the mrna, we first examined whether deadsouth mrna was degraded by mir-427 targeting in somatic cells. injection of antisense mir-427 oligomer and reporter mrna for mutated mres ... | 2014 | 24291337 |
| growth cone-specific functions of xmap215 in restricting microtubule dynamics and promoting axonal outgrowth. | microtubule (mt) regulators play essential roles in multiple aspects of neural development. in vitro reconstitution assays have established that the xmap215/dis1/tog family of mt regulators function as mt 'plus-end-tracking proteins' (+tips) that act as processive polymerases to drive mt growth in all eukaryotes, but few studies have examined their functions in vivo. in this study, we use quantitative analysis of high-resolution live imaging to examine the function of xmap215 in embryonic xenopu ... | 2013 | 24289819 |
| extensions to in silico bioactivity predictions using pathway annotations and differential pharmacology analysis: application to xenopus laevis phenotypic readouts. | the simultaneous increase of computational power and the availability of chemical and biological data have contributed to the recent popularity of in silico bioactivity prediction algorithms. such methods are commonly used to infer the 'mechanism of action' of small molecules and they can also be employed in cases where full bioactivity profiles have not been established experimentally. however, protein target predictions by themselves do not necessarily capture information about the effect of a ... | 2013 | 27481146 |
| grem1, frzb and dkk1 mrna levels correlate with osteoarthritis and are regulated by osteoarthritis-associated factors. | osteoarthritis is, at least in a subset of patients, associated with hypertrophic differentiation of articular chondrocytes. recently, we identified the bone morphogenetic protein (bmp) and wingless-type mmtv integration site (wnt) signaling antagonists gremlin 1 (grem1), frizzled-related protein (frzb) and dickkopf 1 homolog (xenopus laevis) (dkk1) as articular cartilage's natural brakes of hypertrophic differentiation. in this study, we investigated whether factors implicated in osteoarthritis ... | 2013 | 24286177 |
| migratory and adhesive properties of xenopus laevis primordial germ cells in vitro. | the directional migration of primordial germ cells (pgcs) to the site of gonad formation is an advantageous model system to study cell motility. the embryonic development of pgcs has been investigated in different animal species, including mice, zebrafish, xenopus and drosophila. in this study we focus on the physical properties of xenopus laevis pgcs during their transition from the passive to the active migratory state. pre-migratory pgcs from xenopus laevis embryos at developmental stages 17- ... | 2013 | 24285703 |
| in vivo pump-probe optical coherence tomography imaging in xenopus laevis. | currently, optical coherence tomography (oct), is not capable of obtaining molecular information often crucial for identification of disease. to enable molecular imaging with oct, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. a fourier-domain pump-probe oct (ppoct) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. methylene blue, a biological dye with well-know pho ... | 2015 | 24282110 |
| changes in the inflammatory response to injury and its resolution during the loss of regenerative capacity in developing xenopus limbs. | tissue and organ regeneration, unlike development, involves an injury that in postembryonic animals triggers inflammation followed by resolution. how inflammation affects epimorphic regeneration is largely uninvestigated. here we examine inflammation and its resolution in xenopus laevis hindlimb regeneration, which declines during larval development. during the first 5 days postamputation, both regeneration-competent stage 53 and regeneration-deficient stage 57 hindlimbs showed very rapid accumu ... | 2013 | 24278286 |
| characterization of slc26a9 in patients with cf-like lung disease. | diffuse bronchiectasis is a common problem in respiratory clinics. we hypothesized that mutations in the solute carrier 26a9 (slc26a9) gene, encoding for a chloride (cl(-)) transporter mainly expressed in lungs, may lead to defects in mucociliary clearance. we describe two missense variants in the slc26a9 gene in heterozygote patients presenting with diffuse idiopathic bronchiectasis : p.arg575trp, identified in a patient also heterozygote for p.phe508del in the cftr gene; and p.val486ile. expre ... | 2013 | 24272871 |
| grin2b mutations in west syndrome and intellectual disability with focal epilepsy. | to identify novel epilepsy genes using a panel approach and describe the functional consequences of mutations. | 2014 | 24272827 |
| purinergic receptor-induced ca2+ signaling in the neuroepithelium of the vomeronasal organ of larval xenopus laevis. | purinergic signaling has considerable impact on the functioning of the nervous system, including the special senses. purinergic receptors are expressed in various cell types in the retina, cochlea, taste buds, and the olfactory epithelium. the activation of these receptors by nucleotides, particularly adenosine-5'-triphosphate (atp) and its breakdown products, has been shown to tune sensory information coding to control the homeostasis and to regulate the cell turnover in these organs. while the ... | 2014 | 24271060 |
| activation of src and release of intracellular calcium by phosphatidic acid during xenopus laevis fertilization. | we report a new step in the fertilization in xenopus laevis which has been found to involve activation of src tyrosine kinase to stimulate phospholipase c-γ (plc-γ) which increases inositol 1,4,5-trisphosphate (ip3) to release intracellular calcium ([ca](i)). molecular species analysis and mass measurements suggested that sperm activate phospholipase d (pld) to elevate phosphatidic acid (pa). we now report that pa mass increased 2.7 fold by 1 min after insemination and inhibition of pa productio ... | 2014 | 24269904 |
| the neuroplastin adhesion molecules are accessory proteins that chaperone the monocarboxylate transporter mct2 to the neuronal cell surface. | the neuroplastins np65 and np55 are two synapse-enriched immunoglobulin (ig) superfamily adhesion molecules that contain 3 and 2 ig domains respectively. np65 is implicated in long term, activity dependent synaptic plasticity, including ltp. np65 regulates the surface expression of glur1 receptor subunits and the localisation of gaba(a) receptor subtypes in hippocampal neurones. the brain is dependent not only on glucose but on monocarboxylates as sources of energy. the. monocarboxylate transpor ... | 2013 | 24260123 |
| essential roles of lem-domain protein man1 during organogenesis in xenopus laevis and overlapping functions of emerin. | mutations in nuclear envelope proteins are linked to an increasing number of human diseases, called envelopathies. mutations in the inner nuclear membrane protein emerin lead to x-linked emery-dreifuss muscular dystrophy, characterized by muscle weakness or wasting. conversely, mutations in nuclear envelope protein man1 are linked to bone and skin disorders. both proteins share a highly conserved domain, called lem-domain. lem proteins are known to interact with barrier-to-autointegration factor ... | 2013 | 24252515 |
| a quantitative model of amphetamine action on the 5-ht transporter. | amphetamines bind to the plasmalemmal transporters for the monoamines dopamine (dat), noradrenaline (net) and 5-ht (sert); influx of amphetamine leads to efflux of substrates. various models have been proposed to account for this amphetamine-induced reverse transport in mechanistic terms. a most notable example is the molecular stent hypothesis, which posits a special amphetamine-induced conformation that is not likely in alternative access models of transport. the current study was designed to ... | 2014 | 24251585 |
| glutathione is a low-affinity substrate of the human sodium-dependent dicarboxylate transporter. | during a single pass through the kidneys, more than 80% of glutathione (gsh) is excreted, indicating not only glomerular filtration, but also tubular secretion. the first step in tubular secretion is the uptake of a substance across the basolateral membrane of proximal tubule cells by sodium-dependent and -independent transporters. due to the dicarboxylate-like structure, we postulated that gsh uptake across the basolateral membrane is mediated by the sodium-dependent dicarboxylate transporter 3 ... | 2013 | 24247155 |
| steroid exposure during larval development of xenopus laevis affects mrna expression of the reproductive pituitary-gonadal axis in a sex- and stage-dependent manner. | steroids are known to influence the reproductive pituitary-gonadal axis in adult amphibians. here, we studied the effects of hormones on pituitary and gonadal mrna expression during the development of xenopus laevis. tadpoles at nf 58 (prometamorphosis) and at nf 66 (freshly metamorphosed) were exposed for three days to 17β-estradiol (e2), tamoxifen (tam), testosterone (t), dihydrotestosterone (dht) at 10(-7)m, and flutamide (flu) at 10(-6)m. in both genders at nf 58 and 66, t and dht decreased ... | 2014 | 24239592 |
| knockdown of pex11β reveals its pivotal role in regulating peroxisomal genes, numbers, and ros levels in xenopus laevis a6 cells. | peroxisomes are organelles that are ubiquitously found in all eukaryotic cells. enzymes within their lumen are responsible for a variety of processes including the metabolism of fatty acids and eradication (neutralization) of free radicals. peroxisomes are dynamic organelles, able to alter their numbers in response to a variety of different metabolic and cell-specific cues. changes in peroxisome numbers can occur through division of preexisting peroxisomes or through de novo biogenesis from the ... | 2014 | 24234511 |
| distinct patterns of hsp30 and hsp70 degradation in xenopus laevis a6 cells recovering from thermal stress. | heat shock proteins (hsps) are molecular chaperones that assist in protein synthesis, folding and degradation and prevent stress-induced protein aggregation. in this study, we examined the pattern of accumulation of hsp30 and hsp70 in xenopus laevis a6 kidney epithelial cells recovering from heat shock. immunoblot analysis revealed the presence of elevated levels of hsp30 after 72h of recovery. however, the relative levels of hsp70 declined to near control levels after 24h. the relative levels o ... | 2014 | 24231468 |
| ciliogenesis and cerebrospinal fluid flow in the developing xenopus brain are regulated by foxj1. | circulation of cerebrospinal fluid (csf) through the ventricular system is driven by motile cilia on ependymal cells of the brain. disturbed ciliary motility induces the formation of hydrocephalus, a pathological accumulation of csf resulting in ventricle dilatation and increased intracranial pressure. the mechanism by which loss of motile cilia causes hydrocephalus has not been elucidated. the aim of this study was: (1) to provide a detailed account of the development of ciliation in the brain ... | 2013 | 24229449 |
| the ets transcription factor etv1 mediates fgf signaling to initiate proneural gene expression during xenopus laevis retinal development. | fibroblast growth factor signaling plays a significant role in the developing eye, regulating both patterning and neurogenesis. members of the pea3/etv4-subfamily of ets-domain transcription factors (etv1, etv4, and etv5) are transcriptional activators that are downstream targets of fgf/mapk signaling, but whether they are required for eye development is unknown. we show that in the developing xenopus laevis retina, etv1 is transiently expressed at the onset of retinal neurogenesis. we found tha ... | 2014 | 24219979 |
| novel task channels inhibitors derived from dihydropyrrolo[2,1-a]isoquinoline. | task channels belong to the family of k(+) channels with 4 transmembrane segments and 2 pore domains (4tm/2p) per subunit. these channels have been related to apoptosis in cerebellar granule neurons (cgn), as well as cancer in other tissues. task current is regulated by hormones, neurotransmitters, anesthetics and divalent cations, which are not selective. recently, there has been found some organic compounds that inhibit task current selectively. in order to find other modulators, we report her ... | 2014 | 24212057 |
| trichodina xenopodus, a ciliated protozoan, in a laboratory-maintained xenopus laevis. | a postmortem evaluation of a domestically bred, adult, female xenopus laevis revealed the presence of a urinary bladder protozoan consistent with trichodina xenopodus. t. xenopodus is considered an incidental finding, as its presence in the urinary bladder in frogs has not been correlated with disease or with urinary bladder epithelial lesions. trichodina spp. are ciliated protozoa known to colonize many species of amphibians and fish. these protozoa frequently inhabit the skin and gills, but ma ... | 2013 | 24209965 |
| gloeobacter rhodopsin, limitation of proton pumping at high electrochemical load. | we studied the photocurrents of a cyanobacterial rhodopsin gloeobacter violaceus (gr) in xenopus laevis oocytes and hek-293 cells. this protein is a light-driven proton pump with striking similarities to marine proteorhodopsins, including the d121-h87 cluster of the retinal schiff base counterion and a glutamate at position 132 that acts as a proton donor for chromophore reprotonation during the photocycle. interestingly, at low extracellular ph(o) and negative voltage, the proton flux inverted ... | 2013 | 24209850 |
| transient receptor potential channels encode volatile chemicals sensed by rat trigeminal ganglion neurons. | primary sensory afferents of the dorsal root and trigeminal ganglia constantly transmit sensory information depicting the individual's physical and chemical environment to higher brain regions. beyond the typical trigeminal stimuli (e.g. irritants), environmental stimuli comprise a plethora of volatile chemicals with olfactory components (odorants). in spite of a complete loss of their sense of smell, anosmic patients may retain the ability to roughly discriminate between different volatile comp ... | 2013 | 24205061 |
| par6b regulates the dynamics of apicobasal polarity during development of the stratified xenopus epidermis. | during early vertebrate development, epithelial cells establish and maintain apicobasal polarity, failure of which can cause developmental defects or cancer metastasis. this process has been mostly studied in simple epithelia that have only one layer of cells, but is poorly understood in stratified epithelia. in this paper we address the role of the polarity protein partitioning defective-6 homolog beta (par6b) in the developing stratified epidermis of xenopus laevis. at the blastula stage, anim ... | 2013 | 24204686 |
| characterization of a novel α-conotoxin txid from conus textile that potently blocks rat α3β4 nicotinic acetylcholine receptors. | the α3β4 nachrs are implicated in pain sensation in the pns and addiction to nicotine in the cns. we identified an α-4/6-conotoxin (ctx) txid from conus textile. the new toxin consists of 15 amino acid residues with two disulfide bonds. txid was synthesized using solid phase methods, and the synthetic peptide was functionally tested on nachrs heterologously expressed in xenopus laevis oocytes. txid blocked rat α3β4 nachrs with a 12.5 nm ic50, which places it among the most potent α3β4 nachr anta ... | 2013 | 24200193 |
| the unique α4+/-α4 agonist binding site in (α4)3(β2)2 subtype nicotinic acetylcholine receptors permits differential agonist desensitization pharmacology versus the (α4)2(β2)3 subtype. | selected nicotinic agonists were used to activate and desensitize high-sensitivity (hs) (α4)2(β2)3) or low-sensitivity (ls) (α4)3(β2)2) isoforms of human α4β2-nicotinic acetylcholine receptors (nachrs). function was assessed using (86)rb(+) efflux in a stably transfected sh-ep1-hα4β2 human epithelial cell line, and two-electrode voltage-clamp electrophysiology in xenopus laevis oocytes expressing concatenated pentameric hs or ls α4β2-nachr constructs (hsp and lsp). unlike previously studied agon ... | 2014 | 24190916 |
| functional, structural and phylogenetic analysis of domains underlying the al sensitivity of the aluminum-activated malate/anion transporter, taalmt1. | triticum aestivum aluminum-activated malate transporter (taalmt1) is the founding member of a unique gene family of anion transporters (almts) that mediate the efflux of organic acids. a small sub-group of root-localized almts, including taalmt1, is physiologically associated with in planta aluminum (al) resistance. taalmt1 exhibits significant enhancement of transport activity in response to extracellular al. in this study, we integrated structure-function analyses of structurally altered taalm ... | 2013 | 24188189 |
| muscle function and hydrodynamics limit power and speed in swimming frogs. | studies of the muscle force-velocity relationship and its derived n-shaped power-velocity curve offer important insights into muscular limits of performance. given the power is maximal at 1/3 v(max), geometric scaling of muscle force coupled with fluid drag force implies that this optimal muscle-shortening velocity for power cannot be maintained across the natural body-size range. instead, muscle velocity may decrease with increasing body size, conferring a similar n-shaped power curve with body ... | 2013 | 24177194 |
| olfactory wiring logic in amphibians challenges the basic assumptions of the unbranched axon concept. | olfactory receptor neurons extend axons into the olfactory bulb, where they face the challenge to integrate into existing circuitry. the consensus view is that in vertebrates individual receptor neurons project unbranched axons into one specific glomerulus of the olfactory bulb. we report here that, strikingly different from the generally assumed wiring principle in vertebrate olfactory systems, axons of single receptor neurons of xenopus laevis regularly bifurcate and project into more than one ... | 2013 | 24174658 |
| two distinct allosteric binding sites at α4β2 nicotinic acetylcholine receptors revealed by ns206 and ns9283 give unique insights to binding activity-associated linkage at cys-loop receptors. | positive allosteric modulators (pams) of α4β2 nicotinic acetylcholine receptors have the potential to improve cognitive function and alleviate pain. however, only a few selective pams of α4β2 receptors have been described limiting both pharmacological understanding and drug-discovery efforts. here, we describe a novel selective pam of α4β2 receptors, ns206, and compare with a previously reported pam, ns9283. using two-electrode voltage-clamp electrophysiology in xenopus laevis oocytes, ns206 was ... | 2013 | 24169695 |
| significant modulation of the hepatic proteome induced by exposure to low temperature in xenopus laevis. | the african clawed frog, xenopus laevis, is an ectothermic vertebrate that can survive at low environmental temperatures. to gain insight into the molecular events induced by low body temperature, liver proteins were evaluated at the standard laboratory rearing temperature (22°c, control) and a low environmental temperature (5°c, cold exposure). using nano-flow liquid chromatography coupled with tandem mass spectrometry, we identified 58 proteins that differed in abundance. a subsequent gene ont ... | 2013 | 24167716 |
| structural basis of ion permeation gating in slo2.1 k+ channels. | the activation gate of ion channels controls the transmembrane flux of permeant ions. in voltage-gated k(+) channels, the aperture formed by the s6 bundle crossing can widen to open or narrow to close the ion permeation pathway, whereas the selectivity filter gates ion flux in cyclic-nucleotide gated (cng) and slo1 channels. here we explore the structural basis of the activation gate for slo2.1, a weakly voltage-dependent k(+) channel that is activated by intracellular na(+) and cl(-). slo2.1 ch ... | 2013 | 24166878 |
| caffeic acid inhibits organic anion transporters oat1 and oat3 in rat kidney. | some food components influence drug elimination. previously, we found that caffeic acid, present in coffee, fruits, and vegetables, strongly inhibited human homologs of organic anion transporters (oats) oat1 and oat3, which are responsible for renal tubular secretion of anionic drugs. in this study, we examined the effect of caffeic acid on drug transport by oat1 and oat3 in the rat kidney. | 2013 | 24166669 |
| monitoring gene expression in a single xenopus oocyte using multiple cytoplasmic collections and quantitative rt-pcr. | oocytes and eggs of the african clawed frog, xenopus laevis, are commonly used in gene expression studies. however, monitoring transcript levels in the individual living oocytes remains challenging. to address this challenge, we used a technique based on multiple repeated collections of nanoliter volumes of cytoplasmic material from a single oocyte. transcript quantification was performed by quantitative rt-pcr. the technique allowed monitoring of heterologous gene expression in a single oocyte ... | 2014 | 24165194 |
| novel animal pole-enriched maternal mrnas are preferentially expressed in neural ectoderm. | many animals utilize maternal mrnas to pre-pattern the embryo before the onset of zygotic transcription. in xenopus laevis, vegetal factors specify the germ line, endoderm, and dorsal axis, but there are few studies demonstrating roles for animal-enriched maternal mrnas. therefore, we carried out a microarray analysis to identify novel maternal transcripts enriched in 8-cell-stage animal blastomeres. | 2014 | 24155242 |
| the gafa domain of phosphodiesterase-6 contains a rod outer segment localization signal. | photoreceptor phosphodiesterase-6 (pde6) is a peripheral membrane protein synthesized in the inner segment of photoreceptor cells. newly synthesized pde6 is transported to the outer segment (os) where it serves as a key effector enzyme in the phototransduction cascade. proper localization of pde6 in photoreceptors is critically important to the function and survival of photoreceptor cells. the mechanism of pde6 transport to the os remains largely unknown. in this study, we investigated potential ... | 2014 | 24147783 |
| magnetic control of protein spatial patterning to direct microtubule self-assembly. | living systems offer attractive strategies to generate nanoscale structures because of their innate functional properties such as the dynamic assembly of ordered nanometer fibers, the generation of mechanical forces, or the directional transport mediated by molecular motors. the design of hybrid systems, capable of interfacing artificial building blocks with biomolecules, may be a key step toward the rational design of nanoscale devices and materials. here, we have designed a bottom-up approach ... | 2013 | 24144301 |
| a transgenic xenopus laevis reporter model to study lymphangiogenesis. | the importance of the blood- and lymph vessels in the transport of essential fluids, gases, macromolecules and cells in vertebrates warrants optimal insight into the regulatory mechanisms underlying their development. mouse and zebrafish models of lymphatic development are instrumental for gene discovery and gene characterization but are challenging for certain aspects, e.g. no direct accessibility of embryonic stages, or non-straightforward visualization of early lymphatic sprouting, respective ... | 2013 | 24143274 |
| combining different mrna capture methods to analyze the transcriptome: analysis of the xenopus laevis transcriptome. | mrna sequencing (mrna-seq) is a commonly used technique to survey gene expression from organisms with fully sequenced genomes. successful mrna-seq requires purification of mrna away from the much more abundant ribosomal rna, which is typically accomplished by oligo-dt selection. however, mrnas with short poly-a tails are captured poorly by oligo-dt based methods. we demonstrate that combining mrna capture via oligo-dt with mrna capture by the 5' 7-methyl guanosine cap provides a more complete vi ... | 2013 | 24143257 |
| enhanced xao: the ontology of xenopus anatomy and development underpins more accurate annotation of gene expression and queries on xenbase. | the african clawed frogs xenopus laevis and xenopus tropicalis are prominent animal model organisms. xenopus research contributes to the understanding of genetic, developmental and molecular mechanisms underlying human disease. the xenopus anatomy ontology (xao) reflects the anatomy and embryological development of xenopus. the xao provides consistent terminology that can be applied to anatomical feature descriptions along with a set of relationships that indicate how each anatomical entity is r ... | 2013 | 24139024 |
| expression profile of the aromatase enzyme in the xenopus brain and localization of estradiol and estrogen receptors in each tissue. | estradiol (e2) with the strongest bioactivity of the estrogens, is synthesized by the cytochrome p450 aromatase enzyme and plays a key role in sex differentiation of the vertebrate's gonads. in xenopus, aromatase mrna is highly expressed in the brain rather than in the gonad during sex differentiation. in this study, we analyzed the stage change, tissue specificity, and localization of the aromatase expression in the xenopus brain. regardless of the sex difference, expression level of aromatase ... | 2013 | 24135319 |
| expression, purification and low-resolution structure of human vitamin c transporter svct1 (slc23a1). | expression and purification of human membrane proteins for structural studies represent a great challenge. this is because micro- to milligram amounts of pure isolated protein are required. to this aim, we successfully expressed the human vitamin c transporter-1 (hsvct1; slc23a1) in xenopus laevis oocytes and isolated highly pure protein in microgram amounts. recombinant hsvct1 was functional when expressed in oocytes and glycosylated. structural analysis of purified hsvct1 by transmission elect ... | 2013 | 24124560 |
| gender-related sensitivity of development and growth to real microgravity in xenopus laevis. | exposure of organisms to microgravity can induce morphological, physiological, and behavioral modifications which normalize after re-entry in 1g-condition within hours to few weeks. development of xenopus laevis tadpoles, their metamorphosis, and adults' growth were monitored for 3 years after their flight on the 12-day soyuz mission tma13 to the international space station. at onset of microgravity, tadpoles had just developed the hind limb (stage 47) or forelimb bud (stage 50). recordings duri ... | 2014 | 24123857 |
| role of connexin 32 hemichannels in the release of atp from peripheral nerves. | extracellular purines elicit strong signals in the nervous system. adenosine-5'-triphosphate (atp) does not spontaneously cross the plasma membrane, and nervous cells secrete atp by exocytosis or through plasma membrane proteins such as connexin hemichannels. using a combination of imaging, luminescence and electrophysiological techniques, we explored the possibility that connexin 32 (cx32), expressed in schwann cells (scs) myelinating the peripheral nervous system could be an important source o ... | 2013 | 24123415 |
| characterization of the hypothalamus of xenopus laevis during development. ii. the basal regions. | the expression patterns of conserved developmental regulatory transcription factors and neuronal markers were analyzed in the basal hypothalamus of xenopus laevis throughout development by means of combined immunohistochemical and in situ hybridization techniques. the connectivity of the main subdivisions was investigated by in vitro tracing techniques with dextran amines. the basal hypothalamic region is topologically rostral to the basal diencephalon and is composed of the tuberal (rostral) an ... | 2014 | 24122702 |
| hypotonic regulation of mouse epithelial sodium channel in xenopus laevis oocytes. | the regulation of the epithelial na⁺ channel (enac) during cell swelling is relevant in cellular processes in which cell volume changes occur, i.e., migration, proliferation and cell absorption. its sensitivity to hypotonically induced swelling was investigated in the xenopus oocyte expression system with the injection of the three subunits of mouse enac. we used voltage-clamp techniques to study the amiloride-sensitive na⁺ currents (ina(amil)) and video microscopic methodologies to assess oocyt ... | 2013 | 24121666 |
| gaba(a) receptor transmembrane amino acids are critical for alcohol action: disulfide cross-linking and alkyl methanethiosulfonate labeling reveal relative location of binding sites. | alcohols and inhaled anesthetics modulate gaba(a) receptor (gaba(a)r) function via putative binding sites within the transmembrane regions. the relative position of the amino acids lining these sites could be either inter- or intra-subunit. we introduced cysteines in relevant tm locations and tested the proximity of cysteine pairs using oxidizing and reducing agents to induce or break disulfide bridges between cysteines, and thus change gaba-mediated currents in wild-type and mutant α1β2γ2 gaba( ... | 2014 | 24117469 |
| a lov-domain-mediated blue-light-activated adenylate (adenylyl) cyclase from the cyanobacterium microcoleus chthonoplastes pcc 7420. | genome screening of the cyanobacterium microcoleus chthonoplastes pcc 7420 identified a gene encoding a protein (483 amino acids, 54.2 kda in size) characteristic of a bl (blue light)-regulated adenylate (adenylyl) cyclase function. the photoreceptive part showed signatures of a lov (light, oxygen, voltage) domain. the gene product, mpac (microcoleus photoactivated adenylate cyclase), exhibited the lov-specific three-peaked absorption band (λmax=450 nm) and underwent conversion into the photoadd ... | 2013 | 24112109 |
| identification, characterization, and expression of dentin matrix protein 1 gene in xenopus laevis. | dentin matrix protein 1 (dmp1) is an acidic extracellular matrix protein expressed mainly in bone and dentin, and is a member of the small integrin-binding ligand n-linked glycoprotein (sibling) family. the dmp1 gene, however, appears to evolve rapidly in comparison with other sibling genes, even though such functionally important molecules usually evolve more slowly than less important ones. the purpose of this study was to identify and characterize an ortholog of the dmp1 gene in an amphibian ... | 2013 | 24106181 |
| metabolic activation of camkii by coenzyme a. | active metabolism regulates oocyte cell death via calcium/calmodulin-dependent protein kinase ii (camkii)-mediated phosphorylation of caspase-2, but the link between metabolic activity and camkii is poorly understood. here we identify coenzyme a (coa) as the key metabolic signal that inhibits xenopus laevis oocyte apoptosis by directly activating camkii. we found that coa directly binds to the camkii regulatory domain in the absence of ca(2+) to activate camkii in a calmodulin-dependent manner. ... | 2013 | 24095281 |
| calpain2 protease: a new member of the wnt/ca(2+) pathway modulating convergent extension movements in xenopus. | calpains are a family of calcium-dependent intracellular cysteine proteases that regulate several physiological processes by limited cleavage of different substrates. the role of calpain2 in embryogenesis is not clear with conflicting evidence from a number of mouse knockouts. here we report the temporal and spatial expression of calpain2 in xenopus laevis embryos and address its role in xenopus development. we show that calpain2 is expressed maternally with elevated expression in neural tissues ... | 2013 | 24076278 |
| indoxacarb, metaflumizone, and other sodium channel inhibitor insecticides: mechanism and site of action on mammalian voltage-gated sodium channels. | sodium channel inhibitor (sci) insecticides were discovered almost four decades ago but have only recently yielded important commercial products (eg., indoxacarb and metaflumizone). sci insecticides inhibit sodium channel function by binding selectively to slow-inactivated (non-conducting) sodium channel states. characterization of the action of sci insecticides on mammalian sodium channels using both biochemical and electrophysiological approaches demonstrates that they bind at or near a drug r ... | 2013 | 24072940 |
| insight into the intermolecular recognition mechanism between keap1 and ikkβ combining homology modelling, protein-protein docking, molecular dynamics simulations and virtual alanine mutation. | degradation of certain proteins through the ubiquitin-proteasome pathway is a common strategy taken by the key modulators responsible for stress responses. kelch-like ech-associated protein-1(keap1), a substrate adaptor component of the cullin3 (cul3)-based ubiquitin e3 ligase complex, mediates the ubiquitination of two key modulators, nf-e2-related factor 2 (nrf2) and iκb kinase β (ikkβ), which are involved in the redox control of gene transcription. however, compared to the keap1-nrf2 protein- ... | 2013 | 24066166 |
| chromatin immunoprecipitation and deep sequencing in xenopus tropicalis and xenopus laevis. | chromatin immunoprecipitation and deep sequencing (chip-seq) represents a powerful tool for identifying the genomic targets of transcription factors, chromatin remodeling factors, and histone modifications. the frogs xenopus laevis and xenopus tropicalis have historically been outstanding model systems for embryology and cell biology, with emerging utility as highly accessible embryos for genome-wide studies. here we focus on the particular strengths and limitations of xenopus cell biology and g ... | 2014 | 24064036 |
| paf and ezh2 induce wnt/β-catenin signaling hyperactivation. | fine control of wnt signaling is essential for various cellular and developmental decision-making processes. however, deregulation of wnt signaling leads to pathological consequences, one of which is cancer. here, we identify a function of paf, a component of translesion dna synthesis, in modulating wnt signaling. paf is specifically overexpressed in colon cancer cells and intestinal stem cells and is required for colon cancer cell proliferation. in xenopus laevis, ventrovegetal expression of pa ... | 2013 | 24055345 |
| morpholino studies in xenopus brain development. | antisense morpholino oligonucleotides (mos) have become a valuable method to knock down protein levels, to block mrna splicing, and to interfere with mirna function. mos are widely used to alter gene expression during development of xenopus and zebra fish, where they are typically injected into the fertilized egg or blastomeres. here, we present methods to use electroporation to target delivery of mos to the central nervous system of xenopus laevis or xenopus tropicalis tadpoles. briefly, mo ele ... | 2014 | 24048933 |
| hydrostatic pressure activates atp-sensitive k+ channels in lung epithelium by atp release through pannexin and connexin hemichannels. | lungs of air-breathing vertebrates are constantly exposed to mechanical forces and therefore are suitable for investigation of mechanotransduction processes in nonexcitable cells and tissues. freshly dissected xenopus laevis lungs were used for transepithelial short-circuit current (isc) recordings and were exposed to increased hydrostatic pressure (hp; 5 cm fluid column, modified ussing chamber). i(sc) values obtained under hp (i(5cm)) were normalized to values before hp (i(0cm)) application (i ... | 2014 | 24048216 |
| the nedd4-binding protein 3 (n4bp3) is crucial for axonal and dendritic branching in developing neurons. | circuit formation in the nervous system essentially relies on the proper development of neurons and their processes. in this context, the ubiquitin ligase nedd4 is a crucial modulator of axonal and dendritic branching. | 2013 | 24044555 |
| tuning voltage-gated channel activity and cellular excitability with a sphingomyelinase. | voltage-gated ion channels generate action potentials in excitable cells and help set the resting membrane potential in nonexcitable cells like lymphocytes. it has been difficult to investigate what kinds of phospholipids interact with these membrane proteins in their native environments and what functional impacts such interactions create. this problem might be circumvented if we could modify specific lipid types in situ. using certain voltage-gated k(+) (kv) channels heterologously expressed i ... | 2013 | 24043861 |
| early evolution of the t-box transcription factor family. | developmental transcription factors are key players in animal multicellularity, being members of the t-box family that are among the most important. until recently, t-box transcription factors were thought to be exclusively present in metazoans. here, we report the presence of t-box genes in several nonmetazoan lineages, including ichthyosporeans, filastereans, and fungi. our data confirm that brachyury is the most ancient member of the t-box family and establish that the t-box family diversifie ... | 2013 | 24043797 |
| n-terminal serine dephosphorylation is required for kcc3 cotransporter full activation by cell swelling. | the k(+):cl(-) cotransporter (kcc) activity is modulated by phosphorylation/dephosphorylation processes. in isotonic conditions, kccs are inactive and phosphorylated, whereas hypotonicity promotes their dephosphorylation and activation. two phosphorylation sites (thr-991 and thr-1048) in kcc3 have been found to be critical for its regulation. however, here we show that the double mutant kcc3-t991a/t1048a could be further activated by hypotonicity, suggesting that additional phosphorylation site( ... | 2013 | 24043619 |
| the poz-zf transcription factor kaiso (zbtb33) induces inflammation and progenitor cell differentiation in the murine intestine. | since its discovery, several studies have implicated the poz-zf protein kaiso in both developmental and tumorigenic processes. however, most of the information regarding kaiso's function to date has been gleaned from studies in xenopus laevis embryos and mammalian cultured cells. to examine kaiso's role in a relevant, mammalian organ-specific context, we generated and characterized a kaiso transgenic mouse expressing a murine kaiso transgene under the control of the intestine-specific villin pro ... | 2013 | 24040197 |
| c-jun n-terminal kinase phosphorylation of heterogeneous nuclear ribonucleoprotein k regulates vertebrate axon outgrowth via a posttranscriptional mechanism. | c-jun n-terminal kinase (jnk) mediates cell signaling essential for axon outgrowth, but the associated substrates and underlying mechanisms are poorly understood. we identified in xenopus laevis embryos a novel posttranscriptional mechanism whereby jnk regulates axonogenesis by phosphorylating a specific site on heterogeneous nuclear ribonucleoprotein k (hnrnp k). both jnk inhibition and hnrnp k knockdown inhibited axon outgrowth and translation of hnrnp k-regulated cytoskeletal rnas (tau and ne ... | 2013 | 24027268 |
| coco regulates dorsoventral specification of germ layers via inhibition of tgfβ signalling. | one of the earliest steps in embryonic development is the specification of the germ layers, the subdivision of the blastula embryo into endoderm, mesoderm and ectoderm. maternally expressed members of the transforming growth factor β (tgfβ) family influence all three germ layers; the ligands are required to induce endoderm and mesoderm, whereas inhibitors are required for formation of the ectoderm. here, we demonstrate a vital role for maternal coco, a secreted antagonist of tgfβ signalling, in ... | 2013 | 24026124 |
| identification of cysteine residues in human cationic amino acid transporter hcat-2a that are targets for inhibition by n-ethylmaleimide. | in most cells, cationic amino acids such as l-arginine, l-lysine, and l-ornithine are transported by cationic (cat) and y(+)l (y(+)lat) amino acid transporters. in human erythrocytes, the cysteine-modifying agent n-ethylmaleimide (nem) has been shown to inhibit system y(+) (most likely cat-1), but not system y(+)l (devés, r., angelo, s., and chávez, p. (1993) j. physiol. 468, 753-766). we thus wondered if sensitivity to nem distinguishes generally all cat and y(+)lat isoforms. transport assays i ... | 2013 | 24019517 |
| functional assays for insect olfactory receptors in xenopus oocytes. | reconstitution of olfactory or pheromone receptors in heterologous expression systems greatly facilitates the functional analysis of these receptors. xenopus laevis oocytes can be used to efficiently express insect olfactory or pheromone receptors. in this chapter, we describe how to use xenopus laevis oocytes for functional assays of insect olfactory receptors. the procedure can be subdivided into the four following steps: (1) in vitro complementary rna (crna) synthesis, (2) isolation of oocyte ... | 2013 | 24014357 |
| phytochemical profiling of curcuma kwangsiensis rhizome extract, and identification of labdane diterpenoids as positive gabaa receptor modulators. | an ethyl acetate extract of curcuma kwangsiensis s.g. lee & c.f. liang (zingiberaceae) rhizomes (100 μg/ml) enhanced the gaba-induced chloride current (igaba) through gabaa receptors of the α1β2γ2s subtype by 79.0±7.0%. potentiation of igaba was measured using the two-microelectrode voltage-clamp technique and xenopus laevis oocytes. hplc-based activity profiling of the crude extract led to the identification of 11 structurally related labdane diterpenoids, including four new compounds. structur ... | 2013 | 24011802 |
| the xenopus amygdala mediates socially appropriate vocal communication signals. | social interaction requires that relevant sensory information is collected, classified, and distributed to the motor areas that initiate an appropriate behavioral response. vocal exchanges, in particular, depend on linking auditory processing to an appropriate motor expression. because of its role in integrating sensory information for the purpose of action selection, the amygdala has been implicated in social behavior in many mammalian species. here, we show that two nuclei of the extended amyg ... | 2013 | 24005304 |
| procaine, a state-dependent blocker, inhibits herg channels by helix residue y652 and f656 in the s6 transmembrane domain. | the article evaluated the inhibitory action of procaine on wild-type and mutated herg potassium channel current (i(herg)) to determine whether mutations in the s6 region are important for the inhibition of i(herg) by procaine. herg channels (wt, y652a, and f656a) were expressed in xenopus laevis oocytes and studied using the standard two-microelectrode voltage-clamp technique. the results revealed that wt herg is blocked in a concentration-, voltage-, and state-dependent manner by procaine ([ic₅ ... | 2013 | 24005047 |
| in vivo time-lapse imaging of neuronal development in xenopus. | in vivo fluorescence imaging of cells in the developing nervous system is greatly facilitated in specimens in which cells are brightly but sparsely labeled. in this article, we describe a number of techniques that can be used for delivering fluorophore to neurons in the albino xenopus laevis tadpole. fluorescent dye or dna that encodes a fluorescent protein can be delivered to single cells by electroporation. alternatively, multiple cells can be labeled with fluorescent dye introduced by local i ... | 2013 | 24003201 |