Publications

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tgf-β family signaling in early vertebrate development.tgf-β family ligands function in inducing and patterning many tissues of the early vertebrate embryonic body plan. nodal signaling is essential for the specification of mesendodermal tissues and the concurrent cellular movements of gastrulation. bone morphogenetic protein (bmp) signaling patterns tissues along the dorsal-ventral axis and simultaneously directs the cell movements of convergence and extension. after gastrulation, a second wave of nodal signaling breaks the symmetry between the lef ...201728600394
xenopus pitx3 target genes lhx1 and xnr5 are identified using a novel three-fluor flow cytometry-based analysis of promoter activation and repression.pitx3 plays a well understood role in directing development of lens, muscle fiber, and dopaminergic neurons; however, in xenopus laevis, it may also play a role in early gastrulation and somitogenesis. potential downstream targets of pitx3 possess multiple binding motifs that would not be readily accessible by conventional promoter analysis.201728598520
anesthetic synergy between two n-alkanes.n-butane and n-pentane can both produce general anesthesia. both compounds potentiate γ-aminobutyric acid type a (gabaa) receptor function, but only butane inhibits n-methyl-d-aspartate (nmda) receptors. it was hypothesized that butane and pentane would exhibit anesthetic synergy due to their different actions on ligand-gated ion channels.201728583773
inhibition of insect olfactory behavior by an airborne antagonist of the insect odorant receptor co-receptor subunit.response to volatile environmental chemosensory cues is essential for insect survival. the odorant receptor (or) family is an important class of receptors that detects volatile molecules; guiding insects towards food, mates, and oviposition sites. ors are odorant-gated ion channels, consisting of a variable odorant specificity subunit and a conserved odorant receptor co-receptor (orco) subunit, in an unknown stoichiometry. the orco subunit possesses an allosteric site to which modulators can bin ...201728562598
the flexible cytoplasmic loop 3 contributes to the substrate affinity of human monocarboxylate transporters.human monocarboxylate transporters (hmcts/slc16as) mediate the transport of small molecular weight monocarboxylates. among hmcts, hmct1 exhibits high-affinity l-lactate transport and broad substrate recognition, whereas hmct4 shows highly specific substrate recognition and low-affinity l-lactate transport, indicating that hmct1 and hmct4 have different roles in the body. however, the molecular mechanism of transporter-mediated substrate transport remains unknown. the aim of this study is to iden ...201728559188
neun immunoreactivity in the brain of xenopus laevis.neuronal nuclear antigen (neun), discovered in mice brain cell nuclei by mullen et al. (1992), is used as an excellent marker of post-mitotic neurons in vertebrates. in this study, the expression pattern of neun was examined in the xenopus brain to explore phylogenetic differences in neun expression. anti-neun antibody showed selective staining in mouse and xenopus brain extracts, but the number and molecular weight of the bands differed in western blotting analysis. in immunostaining, anti-neun ...201728558928
the gliotransmitter d-serine promotes synapse maturation and axonal stabilization in vivo.the nmdar is thought to play a key role in the refinement of connectivity in developing neural circuits. pharmacological blockade or genetic loss-of-function manipulations that prevent nmdar function during development result in the disorganization of topographic axonal projections. however, because nmdars contribute to overall glutamatergic neurotransmission, such loss-of-function experiments fail to adequately distinguish between the roles played by nmdars and neural activity in general. the g ...201728550169
digital dissection of the model organism xenopus laevis using contrast-enhanced computed tomography.the african clawed frog, xenopus laevis, is one of the most widely used model organisms in biological research. however, the most recent anatomical description of x. laevis was produced nearly a century ago. compared with other anurans, pipid frogs - including x. laevis - exhibit numerous unusual morphological features; thus, anatomical descriptions of more 'typical' frogs do not detail many aspects of x. laevis skeletal and soft-tissue morphology. the relatively new method of using iodine-based ...201728547827
an analysis of myod-dependent transcription using crispr/cas9 gene targeting in xenopus tropicalis embryos.myogenic regulatory factors (mrfs) are known to have essential roles in both the establishment and differentiation of the skeletal muscle cell lineage. myod is expressed early in the xenopus mesoderm where it is present and active several hours before the activation of muscle differentiation genes. previous studies in cultured cells and in xenopus laevis have identified sets of genes that require myod prior to differentiation of skeletal muscle. here we report results from experiments using cris ...201728536000
the neuronal and astrocytic protein slc38a10 transports glutamine, glutamate, and aspartate, suggesting a role in neurotransmission.in brain cells, glutamine transporters are vital to monitor and control the levels of glutamate and gaba. there are 11 members of the slc38 family of amino acid transporters of which eight have been functionally characterized. here, we report the first histological and functional characterization of the previously orphan member, slc38a10. we used pairwise global sequence alignments to determine the sequence identity between the slc38 family members. slc38a10 was found to share 20-25% transmembra ...201728593130
high-quality frozen extracts of xenopus laevis eggs reveal size-dependent control of metaphase spindle micromechanics.cell-free extracts from unfertilized xenopus laevis eggs offer the opportunity for a variety of biochemical and biophysical assays for analyzing essential cell cycle events such as metaphase spindle assembly. however, the extracts often exhibit substantial variation in quality and have low storage stability, factors that hamper their experimental utility. here we report a simple two-step method for preparing frozen egg extracts that retain spindle assembly activity levels similar to those of fre ...201728592634
characterization of the transport activity of sglt2/map17, the renal low-affinity na+-glucose cotransporter.the cotransporter sglt2 is responsible for 90% of renal glucose reabsorption, and we recently showed that map17 appears to work as a required β-subunit. we report in the present study a detailed functional characterization of human sglt2 in coexpression with human map17 in xenopus laevis oocytes. addition of external glucose generates a large inward current in the presence of na, confirming an electrogenic transport mechanism. at a membrane potential of -50 mv, sglt2 affinity constants for gluco ...201728592437
the c-terminal kinesin motor kifc1 may participate in nuclear reshaping and flagellum formation during spermiogenesis of larimichthys crocea.spermatogenesis is a highly ordered process in the differentiation of male germ cells. nuclear morphogenesis is one of the most fundamental cellular transformations to take place during spermatogenesis. these striking transformations from spermatogonia to spermatozoa are a result of phase-specific adaption of the cytoskeleton and its association with molecular motor proteins. kifc1 is a c-terminal kinesin motor protein that plays an essential role in acrosome formation and nuclear reshaping duri ...201728534180
are invasive populations characterized by a broader diet than native populations?invasive species are among the most significant threats to biodiversity. the diet of invasive animal populations is a crucial factor that must be considered in the context of biological invasions. a broad dietary spectrum is a frequently cited characteristic of invasive species, allowing them to thrive in a wide range of environments. therefore, empirical studies comparing diet in invasive and native populations are necessary to understand dietary requirements, dietary flexibility, and the assoc ...201728533950
leptin induces mitosis and activates the canonical wnt/β-catenin signaling pathway in neurogenic regions of xenopus tadpole brain.in addition to its well-known role as an adipostat in adult mammals, leptin has diverse physiological and developmental actions in vertebrates. leptin has been shown to promote development of hypothalamic circuits and to induce mitosis in different brain areas of mammals. we investigated the ontogeny of leptin mrna, leptin actions on cell proliferation in the brain, and gene expression in the preoptic area/hypothalamus of tadpoles of xenopus laevis. the level of leptin mrna was low in premetamor ...201728533765
two-electrode voltage-clamp recordings in xenopus laevis oocytes: reconstitution of abscisic acid activation of slac1 anion channel via pyl9 aba receptor.two-electrode voltage-clamp (tevc) recording in xenopus laevis oocytes provides a powerful method to investigate the functions and regulation of ion channel proteins. this approach provides a well-known tool to characterize ion channels or transporters expressed in xenopus laevis oocytes. the plasma membrane of the oocyte is impaled by two microelectrodes, one for voltage sensing and the other one for current injection. here we list a protocol that allows robust reconstitution of multi-component ...201728516122
editorial: the xenopus laevis genome. 201728457863
use of xenopus frogs to study renal development/repair.the xenopus genus includes several members of aquatic frogs native to africa but is perhaps best known for the species xenopus laevis and xenopus tropicalis. these species were popularized as model organisms from as early as the 1800s and have been instrumental in expanding several biological fields including cell biology, environmental toxicology, regenerative biology, and developmental biology. in fact, much of what we know about the formation and maturation of the vertebrate renal system has ...201728409343
asymmetries in cell division, cell size, and furrowing in the xenopus laevis embryo.asymmetric cell divisions produce two daughter cells with distinct fate. during embryogenesis, this mechanism is fundamental to build tissues and organs because it generates cell diversity. in adults, it remains crucial to maintain stem cells. the enthusiasm for asymmetric cell division is not only motivated by the beauty of the mechanism and the fundamental questions it raises, but has also very pragmatic reasons. indeed, misregulation of asymmetric cell divisions is believed to have dramatic c ...201728409308
asymmetric localization and distribution of factors determining cell fate during early development of xenopus laevis.asymmetric division is a property of eukaryotic cells that is fundamental to the formation of higher life forms. despite its importance, the mechanism behind it remains elusive. asymmetry in the cell is induced by polarization of cell fate determinants that become unevenly distributed among progeny cells. so far dozens of determinants have been identified. xenopus laevis is an ideal system to study asymmetric cell division during early development, because of the huge size of its oocytes and ear ...201728409307
the role of nitric oxide during embryonic epidermis development of xenopus laevis.nitric oxide (no) is a potent radical molecule that participates in various biological processes such as vasodilation, cell proliferation, immune response and neurotransmission. no mainly activates soluble guanylate cyclase, leading to cgmp production and activation of protein kinase g and its downstream targets. here we report the essential role of no during embryonic epidermis development. xenopus embryonic epidermis has become a useful model reflecting human epithelial tissue composition. the ...201728483981
mechanosensory stimulation evokes acute concussion-like behavior by activating girks coupled to muscarinic receptors in a simple vertebrate.most vertebrates show concussion responses when their heads are hit suddenly by heavy objects. previous studies have focused on the direct physical injuries to the neural tissue caused by the concussive blow. we study a similar behavior in a simple vertebrate, the xenopus laevis tadpole. we find that concussion-like behavior can be reliably induced by the mechanosensory stimulation of the head skin without direct physical impacts on the brain. head skin stimulation activates a cholinergic pathwa ...201728462392
functional assessment of the nmda receptor variant glun2a r586k.background: the n-methyl-d-aspartate receptor (nmdar) is an ionotropic glutamate receptor that has important roles in synaptogenesis, synaptic transmission, and synaptic plasticity. recently, a large number of rare genetic variants have been found in nmdar subunits in people with neurodevelopmental disorders, and also in healthy individuals. one such is the glun2ar586k variant, found in a person with intellectual disability. identifying the functional consequences, if any, of such variants allow ...201728459106
chromosomal passenger complex hydrodynamics suggests chaperoning of the inactive state by nucleoplasmin/nucleophosmin.the chromosomal passenger complex (cpc) is a conserved, essential regulator of cell division. as such, significant anti-cancer drug development efforts have been focused on targeting it, most notably by inhibiting its aurkb kinase subunit. the cpc is activated by aurkb-catalyzed autophosphorylation on multiple subunits, but how this regulates cpc interactions with other mitotic proteins remains unclear. we investigated the hydrodynamic behavior of the cpc in xenopus laevis egg cytosol using sucr ...201728404751
functional assessment of sodium chloride cotransporter ncc mutants in polarized mammalian epithelial cells.the thiazide-sensitive sodium chloride cotransporter ncc is important for maintaining serum sodium (na+) and, indirectly, serum potassium (k+) levels. functional studies on ncc have used cell lines with native ncc expression, transiently transfected nonpolarized cell lines, or xenopus laevis oocytes. here, we developed the use of polarized madin-darby canine kidney type i (mdcki) mammalian epithelial cell lines with tetracycline-inducible human ncc expression to study ncc activity and membrane a ...201728515174
quercetin, morin, luteolin, and phloretin are dietary flavonoid inhibitors of monocarboxylate transporter 6.monocarboxylate transporter 6 (mct6; slc16a5) has been recognized for its role as a xenobiotic transporter, with characterized substrates probenecid, bumetanide, and nateglinide. to date, the impact of commonly ingested dietary compounds on mct6 function has not been investigated, and therefore, the objective of this study was to evaluate a variety of flavonoids for their potential mct6-specific interactions. flavonoids are a large group of polyphenolic phytochemicals found in commonly consumed ...201728513167
the nodulin 26-like intrinsic membrane protein osnip3;2 is involved in arsenite uptake by lateral roots in rice.previous studies have shown that the nodulin 26-like intrinsic membrane protein (nip) lsi1 (osnip2;1) is involved in arsenite [as(iii)] uptake in rice (oryza sativa). however, the role of other rice nips in as(iii) accumulation in planta remains unknown. in the present study, we investigated the role osnip3;2 in as(iii) uptake in rice. when expressed in xenopus laevis oocytes, osnip3;2 showed a high transport activity for as(iii). quantitative real-time rt-pcr showed that the expression of osnip ...201728505352
co-accumulation of cis-regulatory and coding mutations during the pseudogenization of the xenopus laevis homoeologs six6.l and six6.s.common models for the evolution of duplicated genes after genome duplication are subfunctionalization, neofunctionalization, and pseudogenization. although the crucial roles of cis-regulatory mutations in subfunctionalization are well-documented, their involvement in pseudogenization and/or neofunctionalization remains unclear. we addressed this issue by investigating the evolution of duplicated homeobox genes, six6.l and six6.s, in the allotetraploid frog xenopus laevis. based on a comparative ...201728501477
identification of α7 nicotinic acetylcholine receptor silent agonists based on the spirocyclic quinuclidine-δ2 -isoxazoline scaffold: synthesis and electrophysiological evaluation.compound 11 (3-(benzyloxy)-1'-methyl-1'-azonia-4h-1'-azaspiro[isoxazole-5,3'-bicyclo[2.2.2]octane] iodide) was selected from a previous set of nicotinic ligands as a suitable model compound for the design of new silent agonists of α7 nicotinic acetylcholine receptors (nachrs). silent agonists evoke little or no channel activation but can induce the α7 desensitized ds state, which is sensitive to a type ii positive allosteric modulator, such as pnu-120596. introduction of meta substituents into t ...201728494140
opposing effects of valproic acid treatment mediated by histone deacetylase inhibitor activity in four transgenic x. laevis models of retinitis pigmentosa.retinitis pigmentosa (rp) is an inherited retinal degeneration (rd) that leads to blindness for which no treatment is available. rp is frequently caused by mutations in rhodopsin; in some animal models, rd is exacerbated by light. valproic acid (vpa) is a proposed treatment for rp and other neurodegenerative disorders, with a phase ii trial for rp under way. however, the therapeutic mechanism is unclear, with minimal research supporting its use in rp. we investigated the effects of vpa on xenopu ...201728490005
a magnesium transporter osmgt1 plays a critical role in salt tolerance in rice.salt stress is one of the major factors limiting rice (oryza sativa) production globally. although several transporters involved in salt tolerance have been identified in rice, the mechanisms regulating their transport activity are still poorly understood. here, we show evidence that a rice mg transporter osmgt1 is required for salt tolerance probably by regulating transport activity of oshkt1;5, a key transporter for the removal of na+ from the xylem sap at the root mature zone. knockout of osm ...201728487477
hplc-based activity profiling for gabaa receptor modulators in extracts: validation of an approach utilizing a larval zebrafish locomotor assay.gamma-aminobutyric acid type a (gabaa) receptors are major inhibitory neurotransmitter receptors in the central nervous system and a target for numerous clinically important drugs used to treat anxiety, insomnia, and epilepsy. a series of allosteric gabaa receptor agonists was identified previously with the aid of hplc-based activity profiling, whereby activity was tracked with an electrophysiological assay in xenopus laevis oocytes. to accelerate the discovery process, an approach has been esta ...201728485933
in situ microprobe single-cell capillary electrophoresis mass spectrometry: metabolic reorganization in single differentiating cells in the live vertebrate (xenopus laevis) embryo.knowledge of single-cell metabolism would provide a powerful look into cell activity changes as cells differentiate to all the tissues of the vertebrate embryo. however, single-cell mass spectrometry technologies have not yet been made compatible with complex three-dimensional changes and rapidly decreasing cell sizes during early development of the embryo. here, we bridge this technological gap by integrating capillary microsampling, microscale metabolite extraction, and capillary electrophores ...201728434226
masculinization-related genes and cell-mass structures during early gonadal differentiation in the african clawed frog xenopus laevis.the african clawed frog xenopus laevis has a female heterogametic zz/zw-type sex-determining system. we previously discovered a w-linked female sex-determining gene dm-w that is involved in ovary formation, probably through the up-regulation of the estrogen synthesis genes cyp19a1 and foxl2. we also reported that a unique "mass-in-line structure", which disappears from zz gonads during early testicular development, might serve as the basis for ovary differentiation in zw gonads. however, the mol ...201728397603
role of micrornas in zygotic genome activation: modulation of mrna during embryogenesis.a fundamental process occurring during early development is the zygotic genome activation, i.e., the initiation of transcription from the embryonic genome. before that step, cellular processes in the developing embryo are dictated by transcripts produced by the maternal genome and accumulated in the egg during oogenesis. the maternal-to-zygotic transition (mzt) involves both the clearance of maternal rnas and the initiation of transcription of the embryonic genome and is a tightly regulated proc ...201728456956
analysis of active transport by fluorescence recovery after photobleaching.fluorescence recovery after photobleaching (frap) is a well-established experimental technique to study binding and diffusion of molecules in cells. although a large number of analytical and numerical models have been developed to extract binding and diffusion rates from frap recovery curves, active transport of molecules is typically not included in the existing models that are used to estimate these rates. here we present a validated numerical method for estimating diffusion, binding/unbinding ...201728445762
pattern of neurogenesis and identification of neuronal progenitor subtypes during pallial development in xenopus laevis.the complexity of the pallium during evolution has increased dramatically in many different respects. the highest level of complexity is found in mammals, where most of the pallium (cortex) shows a layered organization and neurons are generated during development following an inside-out order, a sequence not observed in other amniotes (birds and reptiles). species-differences may be related to major neurogenetic events, from the neural progenitors that divide and produce all pallial cells. in ma ...201728396626
the mgcracgap sxip motif tethers centralspindlin to microtubule plus ends in xenopus laevis.centralspindlin, a complex of the kinesin-6-family member mklp1 and mgcracgap (also known as kif23 and racgap1, respectively), is required for cytokinesis and cell-cell junctions. during anaphase, centralspindlin accumulates at overlapping central spindle microtubules and directs contractile ring formation by recruiting the gef ect2 to the cell equator to activate rhoa. we found that mgcracgap localized to the plus ends of equatorial astral microtubules during cytokinesis in xenopus laevis embry ...201728389580
clinical and genetic spectrum of bartter syndrome type 3.bartter syndrome type 3 is a clinically heterogeneous hereditary salt-losing tubulopathy caused by mutations of the chloride voltage-gated channel kb gene (clcnkb), which encodes the clc-kb chloride channel involved in nacl reabsorption in the renal tubule. to study phenotype/genotype correlations, we performed genetic analyses by direct sequencing and multiplex ligation-dependent probe amplification and retrospectively analyzed medical charts for 115 patients with clcnkb mutations. functional a ...201728381550
a dominant mutation in nuclear receptor interacting protein 1 causes urinary tract malformations via dysregulation of retinoic acid signaling.congenital anomalies of the kidney and urinary tract (cakut) are the most common cause of ckd in the first three decades of life. however, for most patients with cakut, the causative mutation remains unknown. we identified a kindred with an autosomal dominant form of cakut. by whole-exome sequencing, we identified a heterozygous truncating mutation (c.279delg, p.trp93fs*) of the nuclear receptor interacting protein 1 gene (nrip1) in all seven affected members. nrip1 encodes a nuclear receptor tr ...201728381549
multiple origins of embryonic and tadpole myeloid cells in xenopus laevis.rabbit anti-serum against a myeloid-cell-specific peroxidase (mpo) of xenopus laevis was generated to identify myeloid cells in adult and larval animals. smears of blood samples from adult hematopoietic organs were co-stained with mpo and with xl-2, a mouse monoclonal antibody against a leukocyte common antigen. lymphocytes found in the thymus and spleen were xl-2+mpo- and granulocytes found in peripheral blood cells and the spleen were xl-2+mpo+, indicating that double-staining with these two a ...201728374149
endocrine disruption by environmental gestagens in amphibians - a short review supported by new in vitro data using gonads of xenopus laevis.endocrine disruption caused by various anthropogenic compounds is of persisting concern, especially for aquatic wildlife, because surface waters are the main sink of these so-called endocrine disruptors (ed). in the past, research focused on (anti)estrogenic, (anti)androgenic, and (anti)thyroidal substances, affecting primarily reproduction and development in vertebrates; however, other endocrine systems might be also targeted by ed. environmental gestagens, including natural progestogens (e.g. ...201728431277
frizzled 3 acts upstream of alcam during embryonic eye development.formation of a functional eye during vertebrate embryogenesis requires different processes such as cell differentiation, cell migration, cell-cell interactions as well as intracellular signalling processes. it was previously shown that the non-canonical wnt receptor frizzled 3 (fzd3) is required for proper eye formation, however, the underlying mechanism is poorly understood. here we demonstrate that loss of fzd3 induces severe malformations of the developing eye and that this defect is phenocop ...201728427856
cul-2lrr-1 and ubxn-3 drive replisome disassembly during dna replication termination and mitosis.replisome disassembly is the final step of dna replication in eukaryotes, involving the ubiquitylation and cdc48-dependent dissolution of the cmg helicase (cdc45-mcm-gins). using caenorhabditis elegans early embryos and xenopus laevis egg extracts, we show that the e3 ligase cul-2lrr-1 associates with the replisome and drives ubiquitylation and disassembly of cmg, together with the cdc-48 cofactors ufd-1 and npl-4. removal of cmg from chromatin in frog egg extracts requires cul2 neddylation, and ...201728368371
xenopus metamorphosis as a model to study thyroid hormone receptor function during vertebrate developmental transitions.a hormone-dependent developmental transition from aquatic to terrestrial existence occurs in all tetrapod vertebrates, such as birth, hatching, and metamorphosis. thyroid hormones (th) and their receptors (trs) are key players in the tissue transformations comprising vertebrate developmental transitions. the african clawed frog, xenopus, is a premier model for the role of trs in developmental transitions because of the numerous and dramatic th-dependent tissue transformations during metamorphosi ...201728363743
glycans in the intestinal peptide transporter pept1 contribute to function and protect from proteolysis.despite the fact that many membrane proteins carry extracellular glycans, little is known about whether the glycan chains also affect protein function. we recently demonstrated that the proton-coupled oligopeptide transporter 1 (pept1) in the intestine is glycosylated at six asparagine residues (n50, n406, n439, n510, n515, and n532). mutagenesis-induced disruption of the individual n-glycosylation site n50, which is highly conserved among mammals, was detected to significantly enhance the pept1 ...201728336547
effect of triclosan on anuran development and growth in a larval amphibian growth and development assay.a larval amphibian growth and development assay was performed to evaluate the potential effects of environmentally-relevant concentrations of triclosan (tcs) on amphibian development and growth. xenopus laevis were exposed to tcs 0.0 (control), 6.3, 12.5 and 25.0 μg l-1 (estimated maximum tolerable concentration) until 10 weeks post-metamorphosis. at median metamorphosis time (nieuwkoop and faber stage 62), five larvae per replicate were collected for snout-vent length, hind limb length and body ...201728436085
daphnia magna and xenopus laevis as in vivo models to probe toxicity and uptake of quantum dots functionalized with gh625.the use of quantum dots (qds) for nanomedicine is hampered by their potential toxicologic effects and difficulties with delivery into the cell interior. we accomplished an in vivo study exploiting daphnia magna and xenopus laevis to evaluate both toxicity and uptake of qds coated with the membranotropic peptide gh625 derived from the glycoprotein h of herpes simplex virus and widely used for drug delivery studies. we evaluated and compared the effects of qds and gh625-qds on the survival, uptake ...201728435254
osptr7 (osnpf8.1), a putative peptide transporter in rice, is involved in dimethylarsenate accumulation in rice grain.rice (oryza sativa) is a major dietary source of arsenic (as) for the population consuming rice as their staple food. rice grain contains both inorganic as and methylated as species, especially dimethyarsinate (dma). dma is highly mobile in long-distance translocation in plants, but the underlying mechanism remains unknown. in the present study, we showed that osptr7 (osnpf8.1), a putative peptide transporter in rice, was permeable to dma in xenopus laevis oocytes. transient expression of the os ...201728340032
upregulation of matrix metalloproteinase triggers transdifferentiation of retinal pigmented epithelial cells in xenopus laevis: a link between inflammatory response and regeneration.in adult xenopus eyes, when the whole retina is removed, retinal pigmented epithelial (rpe) cells become activated to be retinal stem cells and regenerate the whole retina. in the present study, using a tissue culture model, it was examined whether upregulation of matrix metalloproteinases (mmps) triggers retinal regeneration. soon after retinal removal, xmmp9 and xmmp18 were strongly upregulated in the tissues of the rpe and the choroid. in the culture, mmp expression in the rpe cells correspon ...201728371543
xenopus egg extract: a powerful tool to study genome maintenance mechanisms.dna repair pathways are crucial to maintain the integrity of our genome and prevent genetic diseases such as cancer. there are many different types of dna damage and specific dna repair mechanisms have evolved to deal with these lesions. in addition to these repair pathways there is an extensive signaling network that regulates processes important for repair, such as cell cycle control and transcription. despite extensive research, dna damage repair and signaling are not fully understood. in vit ...201728427716
characterization of microtubule buckling in living cells.microtubules are filamentous biopolymers involved in essential biological processes. they form key structures in eukaryotic cells, and thus it is very important to determine the mechanisms involved in the formation and maintenance of the microtubule network. microtubule bucklings are transient and localized events commonly observed in living cells and characterized by a fast bending and its posterior relaxation. active forces provided by molecular motors have been indicated as responsible for mo ...201728424847
population-specific resequencing associates the atp-binding cassette subfamily c member 4 gene with gout in new zealand māori and pacific men.there is no evidence for a genetic association between organic anion transporters 1-3 (slc22a6, slc22a7, and slc22a8) and multidrug resistance protein 4 (mrp4; encoded by abcc4) with the levels of serum urate or gout. the māori and pacific (polynesian) population of new zealand has the highest prevalence of gout worldwide. the aim of this study was to determine whether any polynesian population-specific genetic variants in slc22a6-8 and abcc4 are associated with gout.201728371506
interaction and developmental activation of two neuroendocrine systems that regulate light-mediated skin pigmentation.lower vertebrates use rapid light-regulated changes in skin colour for camouflage (background adaptation) or during circadian variation in irradiance levels. two neuroendocrine systems, the eye/alpha-melanocyte-stimulating hormone (α-msh) and the pineal complex/melatonin circuits, regulate the process through their respective dispersion and aggregation of pigment granules (melanosomes) in skin melanophores. during development, xenopus laevis tadpoles raised on a black background or in the dark p ...201728371026
asymmetrically reduced expression of hand1 homeologs involving a single nucleotide substitution in a cis-regulatory element.during vertebrate evolution, whole genome duplications resulted in a number of duplicated genes, some of which eventually changed their expression patterns and/or levels via alteration of cis-regulatory sequences. however, the initial process involved in such cis-regulatory changes remains unclear. therefore, we investigated this process by analyzing the duplicated hand1 genes of xenopus laevis (hand1.l and hand1.s), which were generated by allotetraploidization 17-18 million years ago, and comp ...201728359808
the heterochronic gene lin28 regulates amphibian metamorphosis through disturbance of thyroid hormone function.metamorphosis is a classic example of developmental transition, which involves important morphological and physiological changes that prepare the organism for the adult life. it has been very well established that amphibian metamorphosis is mainly controlled by thyroid hormone (th). here, we show that the heterochronic gene lin28 is downregulated during xenopus laevis metamorphosis. lin28 overexpression before activation of th signaling delays metamorphosis and inhibits the expression of th targ ...201728359807
paxillin and embryonic polyadenylation binding protein (epabp) engage to regulate androgen-dependent xenopus laevis oocyte maturation - a model of kinase-dependent regulation of protein expression.steroid-triggered xenopus laevis oocyte maturation is an elegant physiologic model of nongenomic steroid signaling, as it proceeds completely independent of transcription. we previously demonstrated that androgens are the main physiologic stimulator of oocyte maturation in xenopus oocytes, and that the adaptor protein paxillin plays a crucial role in mediating this process through a positive feedback loop in which paxillin first enhances mos protein translation, ensued by erk2 activation and erk ...201728359799
pkc-mediated phosphorylation of nuclear lamins at a single serine residue regulates interphase nuclear size in xenopus and mammalian cells.how nuclear size is regulated is a fundamental cell-biological question with relevance to cancers, which often exhibit enlarged nuclei. we previously reported that conventional protein kinase c (cpkc) contributes to nuclear size reductions that occur during early xenopus development. here we report that pkc-mediated phosphorylation of lamin b3 (lb3) contributes to this mechanism of nuclear size regulation. by mapping pkc phosphorylation sites on lb3 and testing the effects of phosphomutants in x ...201728356420
spemann organizer transcriptome induction by early beta-catenin, wnt, nodal, and siamois signals in xenopus laevis.the earliest event in xenopus development is the dorsal accumulation of nuclear β-catenin under the influence of cytoplasmic determinants displaced by fertilization. in this study, a genome-wide approach was used to examine transcription of the 43,673 genes annotated in the xenopus laevis genome under a variety of conditions that inhibit or promote formation of the spemann organizer signaling center. loss of function of β-catenin with antisense morpholinos reproducibly reduced the expression of ...201728348214
persistent fibrosis, hypertrophy and sarcomere disorganisation after endoscopy-guided heart resection in adult xenopus.models of cardiac repair are needed to understand mechanisms underlying failure to regenerate in human cardiac tissue. such studies are currently dominated by the use of zebrafish and mice. remarkably, it is between these two evolutionary separated species that the adult cardiac regenerative capacity is thought to be lost, but causes of this difference remain largely unknown. amphibians, evolutionary positioned between these two models, are of particular interest to help fill this lack of knowle ...201728278282
the modulation of two motor behaviors by persistent sodium currents in xenopus laevis tadpoles.persistent sodium currents (inap) are common in neuronal circuitries and have been implicated in several diseases, such as amyotrophic lateral sclerosis (als) and epilepsy. however, the role of inap in the regulation of specific behaviors is still poorly understood. in this study we have characterized inap and investigated its role in the swimming and struggling behavior of xenopus tadpoles. inap was identified in three groups of neurons, namely, sensory rohon-beard neurons (rb neurons), descend ...201728331009
actomyosin-generated tension on cadherin is similar between dividing and non-dividing epithelial cells in early xenopus laevis embryos.epithelia represent a unique situation where polarized cells must maintain sufficiently strong cell-cell contacts to guarantee the epithelial integrity indispensable for barrier functions. nevertheless, epithelia must also keep sufficient plasticity which is crucial during development and morphogenesis. adherens junctions and mechanical forces produced by the actomyosin cytoskeleton are major players for epithelial integrity maintenance and plasticity regulations. to understand how the epitheliu ...201728327558
novel short antimicrobial peptide isolated from xenopus laevis skin.a rich source of bioactive peptides, including a large number of antimicrobial peptides, has been found in amphibian skin. in this study, a novel short antimicrobial peptide was purified from xenopus laevis skin and characterised through reversed-phase high-performance liquid chromatography, edman degradation and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. the peptide was composed of six amino acids with a sequence of dedlde and thus named x. laevis antibacteria ...201728299865
a cellular mechanism for inverse effectiveness in multisensory integration.to build a coherent view of the external world, an organism needs to integrate multiple types of sensory information from different sources, a process known as multisensory integration (msi). previously, we showed that the temporal dependence of msi in the optic tectum of xenopus laevis tadpoles is mediated by the network dynamics of the recruitment of local inhibition by sensory input (felch et al., 2016). this was one of the first cellular-level mechanisms described for msi. here, we expand th ...201728315524
when size matters: transient receptor potential vanilloid 4 channel as a volume-sensor rather than an osmo-sensor.mammalian cells are frequently exposed to stressors causing volume changes. the transient receptor potential vanilloid 4 (trpv4) channel translates osmotic stress into ion flux. the molecular mechanism coupling osmolarity to trpv4 activation remains elusive. trpv4 responds to isosmolar cell swelling and osmolarity translated via different aquaporins. trpv4 functions as a volume-sensing ion channel irrespective of the origin of the cell swelling.201728295351
transcriptomic insights into genetic diversity of protein-coding genes in x. laevis.we characterize the genetic diversity of xenopus laevis strains using rna-seq data and allele-specific analysis. this data provides a catalogue of coding variation, which can be used for improving the genomic sequence, as well as for better sequence alignment, probe design, and proteomic analysis. in addition, we paint a broad picture of the genetic landscape of the species by functionally annotating different classes of mutations with a well-established prediction tool (polyphen-2). further, we ...201728283406
systematic variation of the benzenesulfonamide part of the glun2a selective nmda receptor antagonist tcn-201.glun2a subunit containing n-methyl-d-aspartate receptors (nmdars) are highly involved in various physiological processes in the central nervous system, but also in some diseases, such as anxiety, depression and schizophrenia. however, the role of glun2a subunit containing nmdars in pathological processes is not exactly elucidated. in order to obtain potent and selective inhibitors of glun2a subunit containing nmdars, the selective negative allosteric modulator 2 was systematically modified at th ...201728222314
strong signal increase in sted fluorescence microscopy by imaging regions of subdiffraction extent.photobleaching remains a limiting factor in superresolution fluorescence microscopy. this is particularly true for stimulated emission depletion (sted) and reversible saturable/switchable optical fluorescence transitions (resolft) microscopy, where adjacent fluorescent molecules are distinguished by sequentially turning them off (or on) using a pattern of light formed as a doughnut or a standing wave. in sample regions where the pattern intensity reaches or exceeds a certain threshold, the molec ...201728193881
heteromeric slick/slack k+ channels show graded sensitivity to cell volume changes.slick and slack high-conductance k+ channels are found in the cns, kidneys, pancreas, among other organs, where they play an important role in cell excitability as well as in ion transport processes. they are both activated by na+ and cl- but show a differential regulation by cell volume changes. slick has been shown to be regulated by cell volume changes, whereas slack is insensitive. α-subunits of these channels form homomeric as well as heteromeric channels. it is the aim of this work to expl ...201728222129
motor neurons tune premotor activity in a vertebrate central pattern generator.central patterns generators (cpgs) are neural circuits that drive rhythmic motor output without sensory feedback. vertebrate cpgs are generally believed to operate in a top-down manner in which premotor interneurons activate motor neurons that in turn drive muscles. in contrast, the frog (xenopus laevis) vocal cpg contains a functionally unexplored neuronal projection from the motor nucleus to the premotor nucleus, indicating a recurrent pathway that may contribute to rhythm generation. in this ...201728219984
apetx4, a novel sea anemone toxin and a modulator of the cancer-relevant potassium channel kv10.1.the human ether-à-go-go channel (heag1 or kv10.1) is a cancer-relevant voltage-gated potassium channel that is overexpressed in a majority of human tumors. peptides that are able to selectively inhibit this channel can be lead compounds in the search for new anticancer drugs. here, we report the activity-guided purification and electrophysiological characterization of a novel kv10.1 inhibitor from the sea anemone anthopleura elegantissima. purified sea anemone fractions were screened for inhibit ...201728902151
depolarization of the conductance-voltage relationship in the nav1.5 mutant, e1784k, is due to altered fast inactivation.e1784k is the most common mixed long qt syndrome/brugada syndrome mutant in the cardiac voltage-gated sodium channel nav1.5. e1784k shifts the midpoint of the channel conductance-voltage relationship to more depolarized membrane potentials and accelerates the rate of channel fast inactivation. the depolarizing shift in the midpoint of the conductance curve in e1784k is exacerbated by low extracellular ph. we tested whether the e1784k mutant shifts the channel conductance curve to more depolarize ...201728898267
methylisothiazolinone toxicity and inhibition of wound healing and regeneration in planaria.methylisothiazolinone (mit) is a common biocide used in cosmetic and industrial settings. studies have demonstrated that mit is a human sensitizer, to the extent that in 2013 mit was named allergen of the year. recently, we showed that mit exposure in xenopus laevis (the african clawed frog) inhibits wound healing and tail regeneration. however, it is unknown whether mit affects these processes in other animals. here, we investigated the effects of mit exposure in planaria-non-parasitic freshwat ...201728869924
interleukin-11 induces and maintains progenitors of different cell lineages during xenopus tadpole tail regeneration.unlike mammals, xenopus laevis tadpoles possess high ability to regenerate their lost organs. in amphibians, the main source of regenerated tissues is lineage-restricted tissue stem cells, but the mechanisms underlying induction, maintenance and differentiation of these stem/progenitor cells in the regenerating organs are poorly understood. we previously reported that interleukin-11 (il-11) is highly expressed in the proliferating cells of regenerating xenopus tadpole tails. here, we show that i ...201728887447
in vivo analysis of the neurovascular niche in the developing xenopus brain.the neurovascular niche is a specialized microenvironment formed by the interactions between neural progenitor cells (npcs) and the vasculature. while it is thought to regulate adult neurogenesis by signaling through vascular-derived soluble cues or contacted-mediated cues, less is known about the neurovascular niche during development. in xenopus laevis tadpole brain, npcs line the ventricle and extend radial processes tipped with endfeet to the vascularized pial surface. using in vivo labeling ...201728795134
comprehensive analyses of hox gene expression in xenopus laevis embryos and adult tissues.from whole genome sequencing of an allotetraploid frog, xenopus laevis, two homeologous sets (l and s) of four hox clusters a through d (hoxa.l/s, hoxb.l/s, hoxc.l/s, and hoxd.l/s) and 13 paralogous groups (pgs) with 76 genes were identified, allowing us to carry out the first comprehensive analyses of hox gene expression in vertebrates. expression of all hox genes during development and in adult tissues was analyzed by rna-sequencing. the expression levels of most hox genes were similar between ...201728791673
modeling dominant and recessive forms of retinitis pigmentosa by editing three rhodopsin-encoding genes in xenopus laevis using crispr/cas9.the utility of xenopus laevis, a common research subject for developmental biology, retinal physiology, cell biology, and other investigations, has been limited by lack of a robust gene knockout or knock-down technology. here we describe manipulation of the x. laevis genome using crispr/cas9 to model the human disorder retinitis pigmentosa, and to introduce point mutations or exogenous dna sequences. we introduced and characterized in-frame and out-of-frame insertions and deletions in three gene ...201728761125
essential roles of thyroid hormone-regulated hyaluronan/cd44 signaling in adult stem cell development during xenopus laevis intestinal remodeling.in the amphibian intestine during metamorphosis, thyroid hormone (th) induces some larval epithelial cells to dedifferentiate into stem cells, which generate the adult epithelium analogous to the mammalian intestinal epithelium. we have previously shown that the canonical wnt signaling pathway is involved in adult epithelial development in the xenopus laevis intestine. to understand the function of this pathway more precisely, we here focused on cd44, a major wnt target, which has been identifie ...201728758360
smarcal1-mediated fork reversal triggers mre11-dependent degradation of nascent dna in the absence of brca2 and stable rad51 nucleofilaments.brca2 deficiency causes mre11-dependent degradation of nascent dna at stalled forks, leading to cell lethality. to understand the molecular mechanisms underlying this process, we isolated xenopus laevis brca2. we demonstrated that brca2 protein prevents single-stranded dna gap accumulation at replication fork junctions and behind them by promoting rad51 binding to replicating dna. without brca2, forks with persistent gaps are converted by smarcal1 into reversed forks, triggering extensive mre11- ...201728757209
fetax assay for evaluation of developmental toxicity.the frog embryo teratogenesis assay xenopus (fetax) test is a development toxicity screening test. due to the small amount of compound needed and the capability to study organogenesis in a short period of time (96 h), fetax test constitutes an efficient development toxicity alert test when performed early in drug safety development. the test is conducted on fertilized xenopus laevis mid-blastula-stage eggs over the organogenesis period. compound teratogenic potential is determined after analysis ...201728748472
combining cytotoxicity assessment and xenopus laevis phenotypic abnormality assay as a predictor of nanomaterial safety.the african clawed frog, xenopus laevis, has been used as an efficient pre-clinical screening tool to predict drug safety during the early stages of the drug discovery process. x. laevis is a relatively inexpensive model that can be used in whole organism high-throughput assays whilst maintaining a high degree of homology to the higher vertebrate models often used in scientific research. despite an ever-increasing volume of biomedical nanoparticles (nps) in development, their unique physico-chem ...201728777439
tectal corticotropin-releasing factor (crf) neurons respond to fasting and a reactive stressor in the african clawed frog, xenopus laevis.it is well established that hypothalamic neurons producing the peptide corticotropin-releasing factor (crf) play a key role in stress adaptation, including reduction of food intake when a threat or stressor is present. we have previously reported on the presence of an intrinsic crf signaling system within the optic tectum (ot), a brain area that plays a key role in visually guided prey capture/predator avoidance decisions. to better understand the potential role of tectal crf neurons in regulati ...201728774755
the zahn drawings: new illustrations of xenopus embryo and tadpole stages for studies of craniofacial development.the embryos and tadpoles of the frog xenopus are increasingly important subjects for studies of the development of the head and face - studies that are providing novel and crucial insight into the causes and prevention of a suite of devastating birth defects, as well as basic evolutionary and developmental biology. however, many studies are conducted on a range of embryonic stages that are not fully represented in the beloved xenopus resource, nieuwkoop and faber's classic normal table of xenopu ...201728765211
lethal digenic mutations in the k+ channels kir4.1 (kcnj10) and slack (kcnt1) associated with severe-disabling seizures and neurodevelopmental delay.a 2-yr-old boy presented profound developmental delay, failure to thrive, ataxia, hypotonia, and tonic-clonic seizures that caused the death of the patient. targeted and whole exome sequencing revealed two heterozygous missense variants: a novel mutation in the kcnj10 gene that encodes for the inward-rectifying k+ channel kir4.1 and another previously characterized mutation in kcnt1 that encodes for the na+-activated k+ channel known as slo2.2 or slack. the objectives of this study were to perfo ...201728747464
the α2β2 isoform combination dominates the astrocytic na+ /k+ -atpase activity and is rendered nonfunctional by the α2.g301r familial hemiplegic migraine type 2-associated mutation.synaptic activity results in transient elevations in extracellular k+ , clearance of which is critical for sustained function of the nervous system. the k+ clearance is, in part, accomplished by the neighboring astrocytes by mechanisms involving the na+ /k+ -atpase. the na+ /k+ -atpase consists of an α and a β subunit, each with several isoforms present in the central nervous system, of which the α2β2 and α2β1 isoform combinations are kinetically geared for astrocytic k+ clearance. while transcr ...201728787093
tonoplast-localized nitrate uptake transporters involved in vacuolar nitrate efflux and reallocation in arabidopsis.a great proportion of nitrate taken up by plants is stored in vacuoles. vacuolar nitrate accumulation and release is of great importance to nitrate reallocation and efficient utilization. however, how plants mediate nitrate efflux from vacuoles to cytoplasm is largely unknown. the current study identified npf5.11, npf5.12 and npf5.16 as vacuolar nitrate efflux transporters in arabidopsis. histochemical analysis showed that npf5.11, npf5.12 and npf5.16 were expressed preferentially in root pericy ...201728743909
hmmr mediates anterior neural tube closure and morphogenesis in the frog xenopus.development of the central nervous system requires orchestration of morphogenetic processes which drive elevation and apposition of the neural folds and their fusion into a neural tube. the newly formed tube gives rise to the brain in anterior regions and continues to develop into the spinal cord posteriorly. conspicuous differences between the anterior and posterior neural tube become visible already during neural tube closure (ntc). planar cell polarity (pcp)-mediated convergent extension (ce) ...201728778799
xenopus laevis m18bp1 directly binds existing cenp-a nucleosomes to promote centromeric chromatin assembly.vertebrate centromeres are epigenetically defined by nucleosomes containing the histone h3 variant, cenp-a. cenp-a nucleosome assembly requires the three-protein mis18 complex (mis18α, mis18β, and m18bp1) that recruits the cenp-a chaperone hjurp to centromeres, but how the mis18 complex recognizes centromeric chromatin is unknown. using xenopus egg extract, we show that direct, cell-cycle-regulated binding of m18bp1 to cenp-a nucleosomes recruits the mis18 complex to interphase centromeres to pr ...201728743005
histone methyltransferase dot1l is a coactivator for thyroid hormone receptor during xenopus development.histone modifications are associated with transcriptional regulation by diverse transcription factors. genome-wide correlation studies have revealed that histone activation marks and repression marks are associated with activated and repressed gene expression, respectively. among the histone activation marks is histone h3 k79 methylation, which is carried out by only a single methyltransferase, disruptor of telomeric silencing-1-like (dot1l). we have been studying thyroid hormone (t3)-dependent ...201728739643
splice variants of ph-sensitive chloride channel identify a key determinant of ivermectin sensitivity in the larvae of the silkworm bombyx mori.the ph-sensitive chloride channels (phcls) are broadly expressed in insects, but little is known about their physiologic role, diversity, and sensitivity to insecticides acting on relevant chloride channels. here we have sequenced 50 transcripts of the phcl-1 gene from the brain, third thoracic ganglion (t3g), and midgut of larvae of silkworm bombyx mori it was found that >50 variants were expressed with distinct splicing in the t3g compared with the brain and midgut. of the variants detected, v ...201728739571
a g326e substitution in the glutamate-gated chloride channel 3 (glucl3) of the two-spotted spider mite tetranychus urticae abolishes the agonistic activity of macrocyclic lactones.the macrocyclic lactones abamectin and milbemectin are frequently used to control phytophagous mites such as tetranychus urticae. consequently, resistance has developed and was genetically linked with substitutions in the glutamate-gated chloride channel (glucl) subunits tuglucl1 and tuglucl3. here, we functionally validated a g326e substitution in tuglucl3 by functional expression in xenopus laevis oocytes followed by two-electrode voltage-clamp electrophysiology.201728736919
neuronal degeneration and regeneration induced by axotomy in the olfactory epithelium of xenopus laevis.the olfactory epithelium (oe) has the remarkable capability to constantly replace olfactory receptor neurons (orns) due to the presence of neural stem cells (nscs). for this reason, the oe provides an excellent model to study neurogenesis and neuronal differentiation. in the present work, we induced neuronal degeneration in the oe of xenopus laevis larvae by bilateral axotomy of the olfactory nerves. we found that axotomy induces specific- neuronal death through apoptosis between 24 and 48h post ...201728719101
high-efficiency non-mosaic crispr-mediated knock-in and indel mutation in f0 xenopus.the revolution in crispr-mediated genome editing has enabled the mutation and insertion of virtually any dna sequence, particularly in cell culture where selection can be used to recover relatively rare homologous recombination events. the efficient use of this technology in animal models still presents a number of challenges, including the time to establish mutant lines, mosaic gene editing in founder animals, and low homologous recombination rates. here we report a method for crispr-mediated g ...201728694259
a functional approach to understanding the role of nckx5 in xenopus pigmentation.nckx5 is an ion exchanger expressed mostly in pigment cells; however, the functional role for this protein in melanogenesis is not clear. a variant allele of slc24a5, the gene encoding nckx5, has been shown to correlate with lighter skin pigmentation in humans, indicating a key role for slc24a5 in determining human skin colour. slc24a5 expression has been found to be elevated in melanoma. knockdown analyses have shown slc24a5 to be important for pigmentation, but to date the function of this ion ...201728692664
apolipoprotein c-i mediates wnt/ctnnb1 signaling during neural border formation and is required for neural crest development.in vertebrates, the neural crest and placodes originate in the neural border, which is located between the neural plate and epidermal ectoderm. the neural crest and placodes give rise to a vast array of cell types. formation of neural crest is a multi-step process, in which wnt signals are used reiteratively, but it is currently not clear if a wnt signal is required for neural border formation. here, we have identified apolipoprotein c-i (apoc1) in a screen for genes regulated by wnt/ctnnb1 sign ...201728695961
the effect of pungent and tingling compounds from piper nigrum l. on background k+ currents.black peppercorns (piper nigrum l.) elicit a pungent and tingling oral impression. their pungency is partially explained by the agonist activity of some of their active principles, especially piperine, on trp channels. however, we recently showed that piperine, as well as other pungent compounds, also possess a marked effect on two-pore domain (kcnk, k2p) k+ channels. members of this family play a key role in maintaining the resting membrane potential of excitable cells. interestingly, tingling ...201728694780
fluorescence correlation spectroscopy experiments to quantify free diffusion coefficients in reaction-diffusion systems: the case of ca^{2+} and its dyes.many cell signaling pathways involve the diffusion of messengers that bind and unbind to and from intracellular components. quantifying their net transport rate under different conditions then requires having separate estimates of their free diffusion coefficient and binding or unbinding rates. in this paper, we show how performing sets of fluorescence correlation spectroscopy (fcs) experiments under different conditions, it is possible to quantify free diffusion coefficients and on and off rate ...201728709293
regulation of the insulin-akt signaling pathway and glycolysis during dehydration stress in the african clawed frog xenopus laevis.estivation is an adaptive stress response utilized by some amphibians during periods of drought in the summer season. in this study, we examine the regulation of the insulin signaling cascade and glycolysis pathway in the african clawed frog xenopus laevis during the dehydration stress induced state of estivation. we show that in the brain and heart of x. laevis, dehydration reduces the phosphorylation of the insulin growth factor-1 receptor (igf-1r), and this is followed by similar reductions i ...201728708941
coordinating heart morphogenesis: a novel role for hyperpolarization-activated cyclic nucleotide-gated (hcn) channels during cardiogenesis in xenopus laevis.hyperpolarization-activated cyclic-nucleotide gated channel (hcn) proteins are important regulators of both neuronal and cardiac excitability. among the 4 hcn isoforms, hcn4 is known as a pacemaker channel, because it helps control the periodicity of contractions in vertebrate hearts. although the physiological role of hcn4 channel has been studied in adult mammalian hearts, an earlier role during embryogenesis has not been clearly established. here, we probe the embryonic roles of hcn4 channels ...201728702127
charged antimicrobial peptides can translocate across membranes without forming channel-like pores.how can highly charged, cationic antimicrobial peptides (amps) translocate across hydrophobic lipid bilayers despite the prohibitive energetic penalty to do so? a common explanation has been the formation of peptide-lined channels. however, for most amps, no structures of membrane pores have been found despite clear evidence of membrane leakage and antimicrobial activity. the study here suggests an alternative and simple reason: for the amp pgla from xenopus laevis (charge +5), such pores are no ...201728700927
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