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the human dna glycosylases neil1 and neil3 excise psoralen-induced dna-dna cross-links in a four-stranded dna structure.interstrand cross-links (icls) are highly cytotoxic dna lesions that block dna replication and transcription by preventing strand separation. previously, we demonstrated that the bacterial and human dna glycosylases nei and neil1 excise unhooked psoralen-derived icls in three-stranded dna via hydrolysis of the glycosidic bond between the crosslinked base and deoxyribose sugar. furthermore, neil3 from xenopus laevis has been shown to cleave psoralen- and abasic site-induced icls in xenopus egg ex ...201729234069
functional reintegration of sensory neurons and transitional dendritic reduction of mitral/tufted cells during injury-induced recovery of the larval xenopus olfactory circuit.understanding the mechanisms involved in maintaining lifelong neurogenesis has a clear biological and clinical interest. in the present study, we performed olfactory nerve transection on larval xenopus to induce severe damage to the olfactory circuitry. we surveyed the timing of the degeneration, subsequent rewiring and functional regeneration of the olfactory system following injury. a range of structural labeling techniques and functional calcium imaging were performed on both tissue slices an ...201729234276
rnas coordinate nuclear envelope assembly and dna replication through elys recruitment to chromatin.upon fertilisation, the sperm pronucleus acquires the competence to replicate the genome through a cascade of events that link chromatin remodelling to nuclear envelope formation. the factors involved have been partially identified and are poorly characterised. here, using xenopus laevis egg extracts we show that rnas are required for proper nuclear envelope assembly following sperm dna decondensation. although chromatin remodelling and pre-replication complex formation occur normally, rna-deple ...201729242643
unravelling the mechanisms that determine the uptake and metabolism of magnetic single and multicore nanoparticles in a xenopus laevis model.multicore superparamagnetic nanoparticles have been proposed as ideal tools for some biomedical applications because of their high magnetic moment per particle, high specific surface area and long term colloidal stability. through controlled aggregation and packing of magnetic cores it is possible to obtain not only single-core but also multicore and hollow spheres with internal voids. in this work, we compare toxicological properties of single and multicore nanoparticles. both types of particle ...029242877
tight junctions negatively regulate mechanical forces applied to adherens junctions in vertebrate epithelial tissue.epithelia are layers of polarised cells tightly bound to each other by adhesive contacts. epithelia act as barriers between an organism and its external environment. understanding how epithelia maintain their essential integrity while remaining sufficiently plastic to allow events such as cytokinesis to take place is a key biological problem. in vertebrates, the remodelling and reinforcement of adherens junctions maintains epithelial integrity during cytokinesis. the involvement of tight junctio ...201729246943
differentiation-dependent antiviral capacities of amphibian (xenopus laevis) macrophages.infections by ranaviruses such as frog virus 3 (fv3) are significantly contributing to the worldwide amphibian population declines. notably, amphibian macrophages (mφs) are important to both the fv3 infection strategies and the immune defense against this pathogen. however, the mechanisms underlying amphibian mφ fv3 susceptibility and resistance remain unknown. mφ differentiation is mediated by signaling through the colony-stimulating factor-1 receptor (csf-1r), which is now known to be bound by ...201729259133
dynamic intramolecular regulation of the histone chaperone nucleoplasmin controls histone binding and release.nucleoplasmin (npm) is a highly conserved histone chaperone responsible for the maternal storage and zygotic release of histones h2a/h2b. npm contains a pentameric n-terminal core domain and an intrinsically disordered c-terminal tail domain. though intrinsically disordered regions are common among histone chaperones, their roles in histone binding and chaperoning remain unclear. using an nmr-based approach, here we demonstrate that the xenopus laevis npm tail domain controls the binding of hist ...201729263320
rna helicase mov10 is essential for gastrulation and cns development.mov10 is an rna helicase that modulates access of argonaute 2 to microrna recognition elements in mrnas. we examined the role of mov10 in xenopus laevis development and show a critical role for mov10 in gastrulation and in the development of the central nervous system.201729266590
the progestin norethisterone affects thyroid hormone-dependent metamorphosis of xenopus laevis tadpoles at environmentally relevant concentrations.previously, levonorgestrel (lng) has been shown to be an endocrine disruptor of the amphibian thyroid system. in the present study, we investigated whether anti-thyroidal effects are a common property of progestins other than lng. premetamorphic xenopus laevis tadpoles were exposed to norethisterone (net) and dienogest die (each at 0.1-10nm) and lng (10nm) until completion of metamorphosis. lng and net at all concentrations caused a significant developmental retardation whereas die did not impai ...029268119
anosmin-1 is essential for neural crest and cranial placodes formation in xenopus.during embryogenesis vertebrates develop a complex craniofacial skeleton associated with sensory organs. these structures are primarily derived from two embryonic cell populations the neural crest and cranial placodes, respectively. neural crest cells and cranial placodes are specified through the integrated action of several families of signaling molecules, and the subsequent activation of a complex network of transcription factors. here we describe the expression and function of anosmin-1 (ano ...029277616
direct modification of the 5-ht3 receptor current by some anticancer drugs.the serotonin (5-hydroxytryptamine) type 3 (5-ht3) receptor is an important target in the control of emesis, and 5-ht3 receptor antagonists are effective against the early phase chemotherapy evoked vomiting. we recently reported that the anticancer drugs irinotecan and topotecan directly modulate the 5-ht-mediated 5-ht3 receptor current in vitro. in addition, the drug response depends on the 5-ht3 subunit composition. here, we explored the effects of 35 anticancer drugs on the 5-ht3 receptor cur ...201729277715
proton-independent activation of acid-sensing ion channel asic3 by alkaloid lindoldhamine from laurus nobilis.acid-sensing ion channels (asics) play an important role in synaptic plasticity and learning, as well as in nociception and mechanosensation. asics are implicated in pain, neurological and psychiatric diseases but their therapeutic potential is limited by lack of ligands activating them at physiological ph.201729277899
nanoscale correlated disorder in out-of-equilibrium myelin ultrastructure.ultrastructural fluctuations at nanoscale are fundamental to assess properties and functionalities of advanced out-of-equilibrium materials. we have taken myelin as a model of supramolecular assembly in out-of-equilibrium living matter. myelin sheath is a simple stable multilamellar structure of high relevance and impact in biomedicine. although it is known that myelin has a quasi-crystalline ultrastructure, there is no information on its fluctuations at nanoscale in different states due to limi ...029281257
microprobe capillary electrophoresis mass spectrometry for single-cell metabolomics in live frog (xenopus laevis) embryos.the quantification of small molecules in single cells raises new potentials for better understanding the basic processes that underlie embryonic development. to enable single-cell investigations directly in live embryos, new analytical approaches are needed, particularly those that are sensitive, selective, quantitative, robust, and scalable to different cell sizes. here, we present a protocol that enables the in situ analysis of metabolism in single cells in freely developing embryos of the sou ...201729286491
optimization of mass spectrometric parameters improve the identification performance of capillary zone electrophoresis for single-shot bottom-up proteomics analysis.the effects of ms1 injection time, ms2 injection time, dynamic exclusion time, intensity threshold, and isolation width were investigated on the numbers of peptide and protein identifications for single-shot bottom-up proteomics analysis using cze-ms/ms analysis of a xenopus laevis tryptic digest. an electrokinetically pumped nanospray interface was used to couple a linear-polyacrylamide coated capillary to a q exactive hf mass spectrometer. a sensitive method that used a 1.4 th isolation width, ...029291811
hyperinnervation improves xenopus laevis limb regeneration.xenopus laevis (an anuran amphibian) shows limb regeneration ability between that of urodele amphibians and that of amniotes. xenopus frogs can initiate limb regeneration but fail to form patterned limbs. regenerated limbs mainly consist of cone-shaped cartilage without any joints or branches. these pattern defects are thought to be caused by loss of proper expressions of patterning-related genes. this study shows that hyperinnervation surgery resulted in the induction of a branching regenerate. ...029291977
a transgenic reporter under control of an es1 promoter/enhancer marks wound epidermis and apical epithelial cap during tail regeneration in xenopus laevis tadpole.rapid wound healing and subsequent formation of the apical epithelial cap (aec) are believed to be required for successful appendage regeneration in amphibians. despite the significant role of aec in limb regeneration, its role in tail regeneration and the mechanisms that regulate the wound healing and aec formation are not well understood. we previously identified xenopus laevis es1, which is preferentially expressed in wounded regions, including the aec after tail regeneration. in this study w ...029291984
dioxin exposure alters molecular and morphological responses to thyroid hormone in xenopus laevis cultured cells and prometamorphic tadpoles.amphibian metamorphosis is driven by thyroid hormone (th). we used prometamorphic tadpoles and a cell line of the african clawed frog (xenopus laevis) to examine immediate effects of dioxin exposure on th. gene expression patterns suggest cross-talk between the thyroid hormone receptor (tr) and aryl hydrocarbon receptor (ahr) signaling pathways. in xlk-wg cells, expression of cytochrome p450 1a6 (cyp1a6), an ahr target, was induced 1000-fold by 100 nm tcdd (2, 3, 7, 8 tetrachlorodibenzo-p-dioxin ...029294139
a triad of residues is functionally transferrable between 5-ht3 serotonin receptors and nicotinic acetylcholine receptors.cys-loop receptors are pentameric ligand-gated ion channels that facilitate communication within the nervous system. upon neurotransmitter binding, these receptors undergo an allosteric activation mechanism connecting the binding event to the membrane-spanning channel pore, which expands to conduct ions. some of the earliest steps in this activation mechanism are carried out by residues proximal to the binding site, the relative positioning of which may reflect functional differences among membe ...029298898
bioelectric regulation of innate immune system function in regenerating and intact xenopus laevis.two key inputs that regulate regeneration are the function of the immune system, and spatial gradients of transmembrane potential (vmem). endogenous bioelectric signaling in somatic tissues during regenerative patterning is beginning to be understood, but its role in the context of immune response has never been investigated. here, we show that vmem levels modulate innate immunity activity in xenopus laevis embryos. we developed an assay in which x. laevis embryos are infected with a uropathogen ...201729302351
the extraordinary biology and development of marsupial frogs (hemiphractidae) in comparison with fish, mammals, birds, amphibians and other animals.the study of oogenesis and early development of frogs belonging to the family hemiphractidae provide important comparison to the aquatic development of other frogs, such as xenopus laevis, because reproduction on land characterizes the hemiphractidae. in this review, the multinucleated oogenesis of the marsupial frog flectonotus pygmaeus (hemiphractidae) is analyzed and interpreted. in addition, the adaptations associated with the incubation of embryos in the pouch of the female marsupial frog g ...029305906
a glyphosate micro-emulsion formulation displays teratogenicity in xenopus laevis.glyphosate is the active ingredient in broad-spectrum herbicide formulations used in agriculture, domestic area and aquatic weed control worldwide. its market is growing steadily concurrently with the cultivation of glyphosate-tolerant transgenic crops and emergence of weeds less sensitive to glyphosate. ephemeral and lentic waters near to agricultural lands, representing favorite habitats for amphibian reproduction and early life-stage development, may thus be contaminated by glyphosate based h ...201729306033
exploring the underlying mechanisms of xenopus laevis embryonic cell cycle.cell cycle is an indispensable process in the proliferation and development. despite significant efforts, global quantification and physical understanding are still challenging. in this study, we explored the mechanisms of xenopus laevis embryonic cell cycle by quantifying the underlying landscape and flux. we uncovered the mexican hat landscape of the xenopus laevis embryonic cell cycle with several local basins and barriers on the oscillation path. the local basins characterize the different p ...029310435
molecular determinants of α3β4 nicotinic acetylcholine receptors inhibition by triterpenoids.in a previous work, we reported the regulatory role of the triterpenoids on 5-hydroxytryptamine (5-ht)3a receptors activity in xenopus laevis oocytes (eur. j. pharmacol., 615, 2009, lee et al.). in the present report, we studied the modulation of triterpenoids on the activity of the human nicotinic acetylcholine receptor type α3β4. two-electrode voltage clamp experiments were used to test acetylcholine mediated inward current (iach). treatment with triterpenoids (dehydroeburicoic acid, 6α-hydrox ...029311484
paternal chromosome loss and metabolic crisis contribute to hybrid inviability in xenopus.hybridization of eggs and sperm from closely related species can give rise to genetic diversity, or can lead to embryo inviability owing to incompatibility. although central to evolution, the cellular and molecular mechanisms underlying post-zygotic barriers that drive reproductive isolation and speciation remain largely unknown. species of the african clawed frog xenopus provide an ideal system to study hybridization and genome evolution. xenopus laevis is an allotetraploid with 36 chromosomes ...029320479
spemann-mangold grafts.in 1924, hans spemann and hilde mangold (née pröscholdt) published their famous work describing the transplantation of dorsal blastopore lip of one newt gastrula embryo onto the ventral side of a host embryo at the same stage. they performed these grafts using two newt species with different pigmentation (triturus taeniatus and triturus cristatus) to follow the fate of the grafted tissue. these experiments resulted in the development of conjoined twins attached through their belly. because of th ...029321278
whole-mount immunofluorescence for visualizing endogenous protein and injected rna in xenopus oocytes.asymmetric distribution of mrna and protein is a hallmark of cell polarity in many systems. the xenopus laevis oocyte provides many technical advantages to studying such polarity. thousands of oocytes at different stages of maturity can be harvested from a single ovary and, owing to their relatively large size, even the youngest oocytes can be manually microinjected. microinjection of fluorescently labeled rna combined with immunofluorescence of endogenous proteins can provide insight into the c ...029321279
analysis of mitotic checkpoint function in xenopus egg extracts.accurate sister chromatid segregation is pivotal in the faithful transmission of genetic information during each cell division. to ensure accurate segregation, eukaryotic organisms have evolved a "mitotic (or spindle assembly) checkpoint" to prevent premature advance to anaphase before successful attachment of every chromosome to the microtubules of the mitotic spindle. an unattached kinetochore generates a diffusible signal that inhibits ubiquitination of substrates such as cyclin b and securin ...029321280
nucleus assembly and import in xenopus laevis egg extract.xenopus egg extract represents a powerful cell-free biochemical tool for studying organelle assembly and function. large quantities of cytoplasm can be isolated, and biochemical manipulation of extract composition and cell cycle state is relatively straightforward. in this protocol, we describe the reconstitution of nuclear assembly by adding a chromatin source to interphasic x. laevis egg extract. intact nuclei assemble within 30-45 min of initiating the reaction, followed by nuclear growth. we ...029321282
cranial neural crest explants.the cranial neural crest (cnc) explant assay was originally designed to assess the basic requirements for cnc migration in vitro. this protocol describes the key parameters of cnc explants in xenopus laevis, with a focus on how to extirpate cnc cells and assay their migration in vitro. the protocol can be adapted according to the needs of the experimenter, some examples of which are discussed here.029321283
cranial neural crest transplants.the transplantation of cranial neural crest (cnc) expressing green fluorescent protein (gfp) in xenopus laevis has allowed researchers not only to assess cnc migration in vivo but also to address many other experimental questions. coupled with loss- or gain-of-function experiments, this technique can be used to characterize the function of specific genes during cnc migration and differentiation. although targeted injection can also be used to assess gene function during cnc migration, cnc transp ...029321285
reference gene identification and validation for quantitative real-time pcr studies in developing xenopus laevis.reference genes are essential for gene expression analysis when using real-time quantitative pcr (rt-qpcr). xenopus laevis is a popular amphibian model for studying vertebrate embryogenesis and development. further, x. laevis is ideal for studying thyroid signaling due to its thyroid dependent metamorphosis, a stage comparable to birth in humans. when using pcr based studies, a primary concern is the choice of reference genes. commonly used references are eef1a1, odc1, rpl8, and actnb, although ...029323148
autocatalytic microtubule nucleation determines the size and mass of xenopus laevis egg extract spindles.regulation of size and growth is a fundamental problem in biology. a prominent example is the formation of the mitotic spindle, where protein concentration gradients around chromosomes are thought to regulate spindle growth by controlling microtubule nucleation. previous evidence suggests that microtubules nucleate throughout the spindle structure. however, the mechanisms underlying microtubule nucleation and its spatial regulation are still unclear. here, we developed an assay based on laser ab ...029323637
bisphenol f disrupts thyroid hormone signaling and postembryonic development in xenopus laevis.the safety of bisphenol a (bpa) alternatives has attracted much attention due to their wide use. in this study, we investigated the effects of bisphenol f (bpf), an alternative to bpa, on thyroid hormone (th) signaling and postembryonic development in vertebrates using t3-induced and spontaneous xenopus metamorphosis as models. we found that in the t3-induced metamorphosis assay, higher concentrations of bpf (100-10000 nm) antagonized t3-induced th-response gene transcription and morphological c ...029323886
retinoic acid promotes stem cell differentiation and embryonic development by transcriptionally activating cftr.retinoic acid (ra) plays a pivotal role in many cellular processes; however, the signaling mechanisms mediating the effect of ra are not fully understood. here, we show that ra transcriptionally upregulates cystic fibrosis transmembrane conductance regulator (cftr) by promoting the direct binding of its receptor rarα to cftr promoter in mouse spermatogonia and embryonic stem (es) cells. the ra/cftr pathway is involved in the differentiation of spermatogonia and organogenesis during the embryo de ...029326073
spinal cord cells from pre-metamorphic stages differentiate into neurons and promote axon growth and regeneration after transplantation into the injured spinal cord of non-regenerative xenopus laevis froglets.mammals are unable to regenerate its spinal cord after a lesion, meanwhile, anuran amphibians are capable of spinal cord regeneration only as larvae, and during metamorphosis, this capability is lost. sox2/3+ cells present in the spinal cord of regenerative larvae are required for spinal cord regeneration. here we evaluate the effect of the transplantation of spinal cord cells from regenerative larvae into the resected spinal cord of non-regenerative stages (nr-stage). donor cells were able to s ...201729326551
increased transcript levels and kinetic function of pyruvate kinase during severe dehydration in aestivating african clawed frogs, xenopus laevis.the african clawed frog, xenopus laevis, can withstand extremely arid conditions through aestivation, resulting in dehydration and urea accumulation. aestivating x. laevis reduce their metabolic rate, and rely on anaerobic glycolysis to meet reduced atp demands. the present study investigated how severe dehydration affected the transcript levels, kinetic profile, and phosphorylation state of the key glycolytic enzyme pyruvate kinase (pk) in the liver and skeletal muscle of x. laevis. compared to ...029331521
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