| conserved rna binding activity of a yin-yang 1 homologue in the ova of the purple sea urchin strongylocentrotus purpuratus. | yin-yang 1 (yy1) is a highly conserved transcription factor possessing rna-binding activity. a putative yy1 homologue was previously identified in the developmental model organism strongylocentrotus purpuratus (the purple sea urchin) by genomic sequencing. we identified a high degree of sequence similarity with yy1 homologues of vertebrate origin which shared 100% protein sequence identity over the dna- and rna-binding zinc-finger region with high similarity in the n-terminal transcriptional act ... | 2018 | 29795182 |
| a novel clcn5 pathogenic mutation supports dent disease with normal endosomal acidification. | dent disease is an x-linked recessive renal tubular disorder characterized by low-molecular-weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and progressive renal failure. inactivating mutations of clcn5, the gene encoding the 2cl- /h+ exchanger clc-5, have been reported in patients with dent disease 1. in vivo studies in mice harboring an artificial mutation in the "gating glutamate" of clc-5 (c.632a > c, p.glu211ala) and mathematical modeling suggest that endosomal chlori ... | 2018 | 29791050 |
| rod-specific ablation using the nitroreductase/metronidazole system to investigate regeneration in xenopus. | genetically controlled cell type-specific ablation provides a reproducible method to induce regeneration that can be temporally and spatially controlled. until recently, regeneration studies in xenopus have relied on surgical methods to stimulate regeneration. these methods are labor intensive and not as reproducible as a genetically controlled approach. in this protocol we describe selective ablation of rod photoreceptors in the premetamorphic xenopus laevis retina using the nitroreductase/metr ... | 2018 | 29789402 |
| septin-dependent remodeling of cortical microtubule drives cell reshaping during epithelial wound healing. | wounds in embryos heal rapidly through contraction of the wound edges. despite well-recognized significance of the actomyosin purse string for wound closure, roles for other cytoskeletal components are largely unknown. here, we report that the septin cytoskeleton cooperates with actomyosin and microtubules to coordinate circumferential contraction of the wound margin and concentric elongation of wound-proximal cells in xenopus laevis embryos. microtubules reoriented radially, forming bundles alo ... | 2018 | 29777035 |
| dissecting and culturing animal cap explants. | the animal cap explant is a simple but adaptable tool available to developmental biologists. the use of animal cap explants in demonstrating the presence of mesoderm-inducting activity in the xenopus embryo vegetal pole is one of many elegant examples of their worth. animal caps respond to a range of growth factors (e.g., wnts, fgf, tgf-β), making them especially useful for studying signal transduction pathways and gene regulatory networks. explants are also suitable for examining cell behavior ... | 2018 | 29769399 |
| larval thymectomy of xenopus laevis. | in jawed vertebrates from sharks to mammals, the thymus is the primary (or central) lymphoid tissue where t cells develop and mature. the particular stromal cell types, cytokine environment, and tissue organization in the thymus are essential for v(d)j recombination, positive selection for major histocompatibility complex recognition, and negative selection against self-peptide recognition of most αβ t cells. the thymectomy operation on xenopus tadpole larva described here creates a t-cell-defic ... | 2018 | 29769397 |
| methods for investigating the larval period and metamorphosis in xenopus. | anuran metamorphosis resembles postembryonic development in mammals, a period around birth when many organs/tissues mature into their adult form as circulating thyroid and stress hormone levels are high. unlike uterus-enclosed mammalian embryos, tadpoles develop externally and undergo the dramatic changes of hormone-dependent development totally independent of maternal influence, making them a valuable model in which to study vertebrate postembryonic organ development and maturation. various pro ... | 2018 | 29769395 |
| infrared laser-mediated gene induction at the single-cell level in the regenerating tail of xenopus laevis tadpoles. | we describe a precise and reproducible gene-induction method in the amphibian, xenopus laevis tetrapod amphibians are excellent models for studying the mechanisms of three-dimensional organ regeneration because they have an exceptionally high regenerative ability. however, spatial and temporal manipulation of gene expression has been difficult in amphibians, hindering studies on the molecular mechanisms of organ regeneration. recently, however, development of a xenopus transgenic system with a h ... | 2018 | 29769391 |
| cell transplantation as a method to investigate spinal cord regeneration in regenerative and nonregenerative xenopus stages. | mammals are not capable of regenerating their central nervous system (cns); anamniotes, however, can regenerate in response to injury. the mechanisms that explain the different regenerative capabilities include: (i) extrinsic mechanisms that consider the cellular environment and extracellular matrix composition, (ii) intrinsic factors implicating the presence or absence of genetic programs that promote axon regeneration, and (iii) the presence or absence of neural stem and progenitors cells (nsp ... | 2018 | 29769390 |
| retinoic acid-induced expression of hnf1b and fzd4 is required for pancreas development in xenopus laevis. | retinoic acid (ra) is required for pancreas specification in xenopus and other vertebrates. however, the gene network that is directly induced by ra signalling in this context remains to be defined. by rna sequencing of in vitro-generated pancreatic explants, we identified the genes encoding the transcription factor hnf1β and the wnt-receptor fzd4/fzd4s as direct ra target genes. functional analyses of hnf1b and fzd4/fzd4s in programmed pancreatic explants and whole embryos revealed their requir ... | 2018 | 29769220 |
| coulomb and ch-π interactions in (6-4) photolyase-dna complex dominate dna binding and repair abilities. | (6-4) photolyases ((6-4)pls) are flavoenzymes that repair the carcinogenic uv-induced dna damage, pyrimidine(6-4)pyrimidone photoproducts ((6-4)pps), in a light-dependent manner. although the reaction mechanism of dna photorepair by (6-4)pls has been intensively investigated, the molecular mechanism of the lesion recognition remains obscure. we show that a well-conserved arginine residue in xenopus laevis (6-4)pl (xl64) participates in dna binding, through coulomb and ch-π interactions. fragment ... | 2018 | 29762762 |
| rxr ligands modulate thyroid hormone signaling competence in young xenopus laevis tadpoles. | appropriate thyroid hormone (th) signaling through thyroid hormone receptors (trs) is essential for vertebrate development. amphibian metamorphosis is initiated and sustained through the action of th on trs, which are conserved across vertebrates. trs heterodimerize with retinoid x receptors (rxrs) on thyroid hormone response elements (tres) in the genome; however, in most cell line and adult animal studies, rxr ligands do not affect expression of tr target genes. we used a quantitative, precoci ... | 2018 | 29762675 |
| expression variation and covariation impair analog and enable binary signaling control. | due to noise in the synthesis and degradation of proteins, the concentrations of individual vertebrate signaling proteins were estimated to vary with a coefficient of variation (cv) of approximately 25% between cells. such high variation is beneficial for population-level regulation of cell functions but abolishes accurate single-cell signal transmission. here, we measure cell-to-cell variability of relative protein abundance using quantitative proteomics of individual xenopus laevis eggs and cu ... | 2018 | 29759982 |
| identification of loop d domain amino acids in the human aquaporin-1 channel involved in activation of the ionic conductance and inhibition by aqb011. | aquaporins are integral proteins that facilitate the transmembrane transport of water and small solutes. in addition to enabling water flux, mammalian aquaporin-1 (aqp1) channels activated by cyclic gmp can carry non-selective monovalent cation currents, selectively blocked by arylsulfonamide compounds aqb007 (ic50 170 μm) and aqb011 (ic50 14 μm). in silico models suggested that ligand docking might involve the cytoplasmic loop d (between aqp1 transmembrane domains 4 and 5), but the predicted si ... | 2018 | 29755973 |
| ligand binding and activation properties of the purified bacterial cyclic nucleotide-gated channel sthk. | cyclic nucleotide-modulated ion channels play several essential physiological roles. they are involved in signal transduction in photoreceptors and olfactory sensory neurons as well as pacemaking activity in the heart and brain. investigations of the molecular mechanism of their actions, including structural and electrophysiological characterization, are restricted by the availability of stable, purified protein obtained from accessible systems. here, we establish that sthk, a cyclic nucleotide- ... | 2018 | 29752414 |
| retraction of rod-like mitochondria during microtubule-dependent transport. | molecular motors play relevant roles on the regulation of mitochondria size and shape, essential properties for the cell homeostasis. in this work, we tracked single rod-shaped mitochondria with nanometer precision to explore the performance of microtubule motor teams during processive anterograde and retrograde transport. we analyzed simultaneously the organelle size and verified that mitochondria retracted during retrograde transport with their leading tip moving slower in comparison with the ... | 2018 | 29752335 |
| determination of metals and pharmaceutical compounds released in hospital wastewater from toluca, mexico, and evaluation of their toxic impact. | due to the activities inherent to medical care units, the hospital effluent released contains diverse contaminants such as tensoactives, disinfectants, metals, pharmaceutical products and chemical reagents, which are potentially toxic to the environment since they receive no treatment or are not effectively removed by such treatment before entering the drain. they are incorporated into municipal wastewater, eventually entering water bodies where they can have harmful effects on organisms and can ... | 2018 | 29751329 |
| yokukansan contains compounds that antagonize the 5-ht3 receptor. | we recently focused on alkaloids in uncaria hook (a constituent of the kampo medicine, yokukansan) and identified the pharmacological action of geissoschizine methyl ether on several g protein-coupled receptors. however, the functions of other identified alkaloids in uncaria hook, including hirsutine, hirsuteine, rhynchophylline, isorhynchophylline, corynoxeine, isocorynoxeine, are not clear. | 2018 | 29747744 |
| foxo4 activity is regulated by phosphorylation and the cellular environment during dehydration in the african clawed frog, xenopus laevis. | the african clawed frog, xenopus laevis, is capable of enduring seasonal bouts of severe dehydration stress resulting from transcriptional regulation that facilitates a pro-survival response. previous studies have shown that dehydration increases antioxidant gene expression in this amphibian. as foxo4 is known to regulate several antioxidant genes, we sought to understand how differential phosphorylation and environmental factors (urea, temperature) may contribute to its transcriptional regulati ... | 2018 | 29746959 |
| deciphering the molecular determinants of cholinergic anthelmintic sensitivity in nematodes: when novel functional validation approaches highlight major differences between the model caenorhabditis elegans and parasitic species. | cholinergic agonists such as levamisole and pyrantel are widely used as anthelmintics to treat parasitic nematode infestations. these drugs elicit spastic paralysis by activating acetylcholine receptors (achrs) expressed in nematode body wall muscles. in the model nematode caenorhabditis elegans, genetic screens led to the identification of five genes encoding levamisole-sensitive-achr (l-achr) subunits: unc-38, unc-63, unc-29, lev-1 and lev-8. these subunits form a functional l-achr when hetero ... | 2018 | 29719008 |
| transposable elements and polyploid evolution in animals. | polyploidy in animals is much less common than in plants, where it is thought to be pervasive in all higher plant lineages. recent studies have highlighted the impact of polyploidization and the associated process of diploidy restoration on the evolution and speciation of selected taxonomic groups in the animal kingdom: from vertebrates represented by salmonid fishes and african clawed frogs to invertebrates represented by parasitic root-knot nematodes and bdelloid rotifers. in this review, we f ... | 2018 | 29715568 |
| cardiac regeneration in xenopus tropicalis and xenopus laevis: discrepancies and problems. | two studies have recently focused on adult heart regeneration in xenopus. while we reported on cardiac myogenic regeneration in xenopus tropicalis after injury, marshall and colleagues found no regeneration in an injured heart in xenopus laevis. here, we would like to join the discussion initiated by marshall et al. who debated the methods and species differences in both studies. we agree with their view that the species difference in cardiac regenerative capacity could lead to different results ... | 2018 | 29713455 |
| is adult cardiac regeneration absent in xenopus laevis yet present in xenopus tropicalis? | we recently used an endoscopy-based resection method to explore the consequences of cardiac injury in adult xenopus laevis, obtaining the result that the adult xenopus heart is unable to regenerate. at 11 months post-amputation, cellular and biological marks of scarring persisted. we thus concluded that, contrary to urodeles and teleosts, adult anurans share a cardiac injury outcome similar to adult mammals. however, in their work published in this journal on the 13 december 2017, liao et al. sh ... | 2018 | 29713454 |
| nmda receptor signaling is important for neural tube formation and for preventing antiepileptic drug-induced neural tube defects. | failure of neural tube closure leads to neural tube defects (ntds), which can have serious neurological consequences or be lethal. use of antiepileptic drugs (aeds) during pregnancy increases the incidence of ntds in offspring by unknown mechanisms. here we show that during xenopus laevis neural tube formation, neural plate cells exhibit spontaneous calcium dynamics that are partially mediated by glutamate signaling. we demonstrate that nmda receptors are important for the formation of the neura ... | 2018 | 29712790 |
| xenopus laevis oocyte as a model for the study of the cytoskeleton. | at the beginning of diplotene, the oocyte of xenopus laevis is a cell of about 10-20 microns destined to increase 10,000-fold its size when the oocyte becomes filled with yolk platelets and has accumulated a great number of pigment granules in a half of its periphery. its internal architecture is gradually accomplished during growth because of several factors, especially because of cytoskeletal changes. in the fully-grown oocyte, the cytoskeleton appears to sustain the eccentrically located germ ... | 2018 | 29705198 |
| roles of xenopus chemokine ligand cxclh (xcxclh) in early embryogenesis. | several chemokine molecules control cell movements during early morphogenesis. however, it is unclear whether chemokine molecules affect cell fate. here, we identified and characterized the cxc-type chemokine ligand in xenopus laevis, xenopus cxclh (xcxclh), during early embryogenesis. xcxclh is expressed in the dorsal vegetal region at the gastrula stage. both overexpression and knockdown of xcxclh in the dorsal region inhibited gastrulation. xcxclh contributed to the attraction of mesendoderma ... | 2018 | 29700804 |
| effect of hemin, baicalein and heme oxygenase-1 (ho-1) enzyme activity inhibitors on cd-induced accumulation of ho-1, hsps and aggresome-like structures in xenopus kidney epithelial cells. | cadmium is a highly toxic environmental pollutant that can cause many adverse effects including cancer, neurological disease and kidney damage. aquatic amphibians are particularly susceptible to this toxicant as it was shown to cause developmental abnormalities and genotoxic effects. in mammalian cells, the accumulation of heme oxygenase-1 (ho-1), which catalyzes the breakdown of heme into co, free iron and biliverdin, was reported to protect cells against potentially lethal concentrations of cd ... | 2018 | 29698685 |
| microvascular anatomy of the brain of the adult pipid frog, xenopus laevis (daudin): a scanning electron microscopic study of vascular corrosion casts. | to demonstrate the 3d microvascular anatomy of the brain of the model organism xenopus laevis daudin scanning electron microscopy of vascular corrosion casts was correlated with light microscopy of stained 7 µm thick serial tissues sections. results showed that supplying arteries descended from the leptomeningeal surface without remarkable branchings straight to the subventricular zone where they branched and capillarized. capillaries showed few h- and/or y-shaped anastomoses during their centri ... | 2018 | 29693258 |
| developmental toxicity of dibutyl phthalate and citrate ester plasticizers in xenopus laevis embryos. | citrate esters have been considered as alternatives to phthalate plasticizers. being considered to have low toxicity in mammals, their toxicological information for aquatic animals remains poorly understood. we examined the developmental toxicity of citrate esters including tributyl o-acetylcitrate (atbc), triethyl 2-acetylcitrate (atec), and trihexyl o-acetylcitrate (athc) together with dibutyl phthalate (dbp) based on the frog embryo teratogenesis assay-xenopus (fetax). atbc has the lowest 96 ... | 2018 | 29684872 |
| new apetx-like peptides from sea anemone heteractis crispa modulate asic1a channels. | sea anemones are an abundant source of various biologically active peptides. the hydrophobic 20% ethanol fraction of tropical sea anemone heteractis crispa was shown to contain at least 159 peptide compounds including neurotoxins, proteinase and α-amylase inhibitors, as well as modulators of acid-sensing ion channels (asics). the three new peptides, π-anmtx hcr 1b-2, -3, and -4 (41 aa) (short names hcr 1b-2, -3, -4), identified by a combination of reversed-phase liquid chromatography and mass sp ... | 2018 | 29684594 |
| comparison of oocyte mrna localization patterns in sterlet acipenser ruthenus and african clawed frog xenopus laevis. | in oocytes, rna localization has critical implications, as assembly of proteins in particular subcellular domains is crucial to embryo development. the distribution of mrna molecules can identify and characterize localized transcripts. the goal of this study was to clarify the origin of primordial germ cells in the oocyte body plan and to reveal the generation of cell lineages by localized rnas. the distribution of 12 selected mrnas in sterlet acipenser ruthenus oocytes was investigated by qpcr ... | 2018 | 29682883 |
| effects of multiple life stage exposure to the fungicide prochloraz in xenopus laevis: manifestations of antiandrogenic and other modes of toxicity. | the larval amphibian growth and development assay (lagda) is an internationally harmonized testing guideline for evaluating effects of chronic chemical exposure in amphibians. in order to evaluate the effects of chronic exposure to an antiandrogenic chemical in an amphibian model, prochloraz was tested using a variation of the lagda design. exposure was initiated with <1d post-fertilization embryos at nominal concentrations of 0, 6.7, 20, 60 and 180 μg/l (0, 18, 53, 159, 478 nm) and continued in ... | 2018 | 29674245 |
| fluorescent anesthetics. | methods for using exogenous fluorophore and general anesthetic 1-aminoanthracene (1-ama) and its photoactive derivative 1-azidoanthracene (1-aza) are provided. 1-ama potentiates gabaa chloride currents and immobilizes xenopus laevis tadpoles. cellular and tissue anesthetic distribution can be imaged for quantifying "on-pathway" and "off-pathway" targets. 1-aza shares targets with 1-ama and offers further optoanesthetic spatial and temporal control upon near-uv laser irradiation. furthermore, 1-a ... | 2018 | 29673536 |
| galantamine is not a positive allosteric modulator of human α4β2 or α7 nicotinic acetylcholine receptors. | the alkaloid galantamine was originally isolated from the green snowdrop galanthus woronowii and is currently marketed as a drug for treatment of mild to moderate dementia in patients with alzheimer's disease. in addition to a well-documented proficiency to inhibit acetylcholinesterase, galantamine has been reported to increase neuronal nicotinic ach (nach) receptor function by acting as a positive allosteric modulator. yet there remains controversy regarding these findings in the literature. to ... | 2018 | 29669164 |
| atopt6 protein functions in long-distance transport of glutathione in arabidopsis thaliana. | the involvement of the arabidopsis oligopeptide transporter atopt6, which was previously shown to take up glutathione (gsh) when expressed in yeast cells or in xenopus laevis oocytes, in gsh transport was analyzed using opt6 knockout mutant lines. the concentration of gsh in flowers or siliques was lower in opt6 mutants relative to wild-type plants, suggesting involvement of atopt6 in long-distance transport of gsh. the gsh concentration in phloem sap was similar between opt6 mutants and wild-ty ... | 2018 | 29669129 |
| developmental expression profiles and thyroidal regulation of cytokines during metamorphosis in the amphibian xenopus laevis. | early life-stages of amphibians rely on the innate immune system for defense against pathogens. while thyroid hormones (th) are critical for metamorphosis and later development of the adaptive immune system, the role of th in innate immune system development is less clear. an integral part of the innate immune response are pro-inflammatory cytokines - effector molecules that allow communication between components of the immune system. the objective of this study was to characterize the expressio ... | 2018 | 29656046 |
| new targets for old drugs: cardiac glycosides inhibit atrial-specific k2p3.1 (task-1) channels. | cardiac glycosides have been used in the treatment of arrhythmias for more than 200 years. two-pore-domain (k2p) potassium channels regulate cardiac action potential repolarization. recently, k2p3.1 [tandem of p domains in a weak inward rectifying k+ channel (twik)-related acid-sensitive k+ channel (task)-1] has been implicated in atrial fibrillation pathophysiology and was suggested as an atrial-selective antiarrhythmic drug target. we hypothesized that blockade of cardiac k2p channels contribu ... | 2018 | 29643254 |
| expression of the inactivating deiodinase, deiodinase 3, in the pre-metamorphic tadpole retina. | thyroid hormone (th) orchestrates amphibian metamorphosis. thus, this developmental phase is often used to study th-dependent responses in specific tissues. however, th signaling appears early in development raising the question of the control of th availability in specific cell types prior to metamorphosis. th availability is under strict temporal and tissue-specific control by deiodinases. we examined the expression of the th-inactivating enzyme, deiodinase type 3 (d3), during early retinal de ... | 2018 | 29641587 |
| tbx2 is required for the suppression of mesendoderm during early xenopus development. | t-box family proteins are dna-binding transcriptional regulators that play crucial roles during germ layer formation in the early vertebrate embryo. well-characterized members of this family, including the transcriptional activators brachyury and vegt, are essential for the proper formation of mesoderm and endoderm, respectively. to date, t-box proteins have not been shown to play a role in the promotion of the third primary germ layer, ectoderm. | 2018 | 29633424 |
| an ex vivo assay for screening glucocorticoid signaling disruption based on glucocorticoid-response gene transcription in xenopus tails. | there is a pressing need for developing in vivo or ex vivo assays to screen the glucocorticoid (gc) signaling disruption of chemicals. thus, we aimed to establish an ex vivo assay for screening gc signaling disruption based on the gc-response gene transcription in xenopus laevis tails cultured ex vivo. firstly, we investigated effects of corticosterone (cort, a main gc in frogs) on gc-response gene expression, and determined the six genes as molecular endpoints for assaying the gc signaling disr ... | 2018 | 29628076 |
| micrornp-mediated translational activation of nonadenylated mrnas in a mammalian cell-free system. | micrornas are small noncoding rnas that regulate translation and mrna stability by binding target mrnas in complex with argonaute (ago) proteins. ago interacts with a member of the tnrc6 family proteins to form a micrornp complex, which recruits the ccr4-not complex to accelerate deadenylation and inhibits translation. micrornas primarily repress translation of target mrnas but have been shown to enhance translation of a specific type of target reporter mrnas in various experimental systems: g0 ... | 2018 | 29626383 |
| an intersubunit electrostatic interaction in the gabaa receptor facilitates its responses to benzodiazepines. | benzodiazepines are positive allosteric modulators of the gabaa receptor (gabaar), acting at the α-γ subunit interface to enhance gabaar function. gaba or benzodiazepine binding induces distinct conformational changes in the gabaar. the molecular rearrangements in the gabaar following benzodiazepine binding remain to be fully elucidated. using two molecular models of the gabaar, we identified electrostatic interactions between specific amino acids at the α-γ subunit interface that were broken by ... | 2018 | 29622679 |
| aluminum-activated malate transporters can facilitate gaba transport. | plant aluminum-activated malate transporters (almts) are currently classified as anion channels; they are also known to be regulated by diverse signals, leading to a range of physiological responses. gamma-aminobutyric acid (gaba) regulation of anion flux through almt proteins requires a specific amino acid motif in almts that shares similarity with a gaba binding site in mammalian gabaa receptors. here, we explore why taalmt1 activation leads to a negative correlation between malate efflux and ... | 2018 | 29618628 |
| new information on morphology and molecular data of camallanid nematodes parasitising xenopus laevis (anura: pipidae) in south africa. | three species of nematodes from the camallanidae that are known to infect xenopus laevis daudin (anura: pipidae) were collected from several localities across south africa. new data on morphology, partial 28s and cox1 genes, infection levels and distribution are presented herein. the most common species, batrachocamallanus slomei southwell et kirshner, 1937, from the stomach and less often oesophagus, was found in eight localities. camallanus kaapstaadi southwell et kirshner, 1937, also from the ... | 2018 | 29611533 |
| distinct mhc class i-like interacting invariant t cell lineage at the forefront of mycobacterial immunity uncovered in xenopus. | the amphibian xenopus laevis is to date the only species outside of mammals where a mhc class i-like (mhc-like) restricted innate-like (i) t cell subset (ivα6 t cells) reminiscent of cd1d-restricted inkt cells has been identified and functionally characterized. this provides an attractive in vivo model to study the biological analogies and differences between mammalian it cells and the evolutionarily antecedent xenopus it cell defense system. here, we report the identification of a unique it cel ... | 2018 | 29610296 |
| divergent evolutionary trajectories of two young, homomorphic, and closely related sex chromosome systems. | there exists extraordinary variation among species in the degree and nature of sex chromosome divergence. however, much of our knowledge about sex chromosomes is based on comparisons between deeply diverged species with different ancestral sex chromosomes, making it difficult to establish how fast and why sex chromosomes acquire variable levels of divergence. to address this problem, we studied sex chromosome evolution in two species of african clawed frog (xenopus), both of whom acquired novel ... | 2018 | 29608717 |
| preparations and protocols for whole cell patch clamp recording of xenopus laevis tectal neurons. | the xenopus tadpole retinotectal circuit, comprised of the retinal ganglion cells (rgcs) in the eye which form synapses directly onto neurons in the optic tectum, is a popular model to study how neural circuits self-assemble. the ability to carry out whole cell patch clamp recordings from tectal neurons and to record rgc-evoked responses, either in vivo or using a whole brain preparation, has generated a large body of high-resolution data about the mechanisms underlying normal, and abnormal, cir ... | 2018 | 29608176 |
| xenopus laevis macrophage-like cells produce xcl-1, an intelectin family serum lectin that recognizes bacteria. | xenopus laevis ca2+ -dependent lectin-1 (xcl-1) is an intelectin family serum lectin that selectively recognizes carbohydrate chains on the bacterial cell surface. immunofluorescence examination of control spleen tissues from normal x. laevis revealed cells producing xcl-1 (xcl-1+ cells) exclusively in red pulps. intraperitoneal injection of escherichia coli lipopolysaccharide (lps) caused a marked increase in the number of xcl-1+ cells in red pulps on day 3, followed by a rapid decrease to near ... | 2018 | 29604105 |
| cellular composition and organization of the spinal cord central canal during metamorphosis of the frog xenopus laevis. | studying the cellular composition and morphological changes of cells lining the central canal during xenopus laevis metamorphosis could contribute to understand postnatal development and spinal cord regeneration. here we report the analysis of central canal cells at different stages during metamorphosis using immunofluorescence for protein markers expression, transmission and scanning electron microscopy and cell proliferation assays. the central canal was regionalized according to expression of ... | 2018 | 29603210 |
| effects of environmentally relevant sub-chronic atrazine concentrations on african clawed frog (xenopus laevis) survival, growth and male gonad development. | sub-chronic toxicity of environmentally relevant atrazine concentrations on exposed tadpoles and adult male african clawed frogs (xenopus laevis) was evaluated in a quality controlled laboratory for 90 days. the aim of this study was to determine the effects of atrazine on the survival, growth and gonad development of african clawed frogs. after exposure of tadpoles to atrazine concentrations of 0 (control), 0.01, 200 and 500 μg l-1 in water, mortality rates of 0, 0, 3.3 and 70% respectively wer ... | 2018 | 29602044 |
| muscarinic modulation of the xenopus laevis tadpole spinal mechanosensory pathway. | muscarinic acetylcholine receptors (machrs) mediate effects of acetylcholine (ach) in many systems, including those involved in spinal functions like locomotion. in xenopus laevis tadpoles at two days old, a model vertebrate for motor control research, we investigated the role of machrs in the skin mechanosensory pathway. we found that machr activation by carbachol did not affect the sensory rohon-beard neuron properties. however, carbachol could hyperpolarise sensory interneurons and decrease t ... | 2018 | 29601952 |
| the effects of 4-hydroxybenzoic acid identified from bamboo (dendrocalamus asper) shoots on kv1.4 channel. | bamboo shoot has been used as a treatment for epilepsy in traditional chinese medicine for generations to treat neuronal disorders such as convulsive, dizziness and headaches. 4-hydroxybenzoic acid (4-hba) is a non-flavonoid phenol found abundantly in dendrocalamus asper shoots (bamboo), fruits (strawberries and apples) and flowers. kv1.4 is a rapidly inactivating shaker-related member of the voltage-gated potassium channels with two inactivation mechanisms; the fast n-type and slow c-type. it p ... | 2018 | 29599640 |
| mir-206 is required for changes in cell adhesion that drive muscle cell morphogenesis in xenopus laevis. | micrornas (mirnas) are highly conserved small non-coding rna molecules that post-transcriptionally regulate gene expression in multicellular organisms. within the set of muscle-specific mirnas, mir-206 expression is largely restricted to skeletal muscle and is found exclusively within the bony fish lineage. although many studies have implicated mir-206 in muscle maintenance and disease, its role in skeletal muscle development remains largely unknown. here, we examine the role of mir-206 during x ... | 2018 | 29596841 |
| the degenerin region of the human bile acid-sensitive ion channel (basic) is involved in channel inhibition by calcium and activation by bile acids. | the bile acid-sensitive ion channel (basic) is a member of the enac/degenerin family of ion channels. it is activated by bile acids and inhibited by extracellular ca2+. the aim of this study was to explore the molecular mechanisms mediating these effects. the modulation of basic function by extracellular ca2+ and tauro-deoxycholic acid (t-dca) was studied in xenopus laevis oocytes heterologously expressing human basic using the two-electrode voltage-clamp and outside-out patch-clamp techniques. ... | 2018 | 29589117 |
| functional variants in hcn4 and cacna1h may contribute to genetic generalized epilepsy. | genetic generalized epilepsy (gge) encompasses seizure disorders characterized by spike-and-wave discharges (swd) originating within thalamo-cortical circuits. hyperpolarization-activated (hcn) and t-type ca2+ channels are key modulators of rhythmic activity in these brain regions. here, we screened hcn4 and cacna1h genes for potentially contributory variants and provide their functional analysis. | 2017 | 29588962 |
| high-throughput screening to identify anesthetic ligands using xenopus laevis tadpoles. | general anesthetics are considered among the most significant advances in modern medicine; however, they are also some of the most dangerous commonly administered drugs. despite this, the discovery of novel anesthetics has been slow, with few clinically used agents regardless of their nearly 200-year history. xenopus laevis frogs have a long history as a model organism and provide a vital bridge between in vitro and preclinical mammalian assays. the provided protocols are efficient and cost-effe ... | 2018 | 29588028 |
| mitochondrial ros cause motor deficits induced by synaptic inactivity: implications for synapse pruning. | developmental synapse pruning refines burgeoning connectomes. the basic mechanisms of mitochondrial reactive oxygen species (ros) production suggest they select inactive synapses for pruning: whether they do so is unknown. to begin to unravel whether mitochondrial ros regulate pruning, we made the local consequences of neuromuscular junction (nmj) pruning detectable as motor deficits by using disparate exogenous and endogenous models to induce synaptic inactivity en masse in developing xenopus l ... | 2018 | 29587245 |
| unexplained cardiac arrest: a tale of conflicting interpretations of kcnq1 genetic test results. | unexplained cardiac arrest (uca) is often the first manifestation of an inherited arrhythmogenic disease. genetic testing in uca is challenging due to the complexities of variant interpretation in the absence of supporting cardiac phenotype. we aimed to investigate if a kcnq1 variant [p.(pro64_pro70del)], previously reported as pathogenic, contributes to the long-qt syndrome phenotype, co-segregates with disease or affects kcnq1 function in vitro. | 2018 | 29582136 |
| orthogonality of pyrrolysine trna in the xenopus oocyte. | chemical aminoacylation of orthogonal trna allows for the genetic encoding of a wide range of synthetic amino acids without the need to evolve specific aminoacyl-trna synthetases. this method, when paired with protein expression in the xenopus laevis oocyte expression system, can extract atomic scale functional data from a protein structure to advance the study of membrane proteins. the utility of the method depends on the orthogonality of the trna species used to deliver the amino acid. here, w ... | 2018 | 29581437 |
| delay models for the early embryonic cell cycle oscillator. | time delays are known to play a crucial role in generating biological oscillations. the early embryonic cell cycle in the frog xenopus laevis is one such example. although various mathematical models of this oscillating system exist, it is not clear how to best model the required time delay. here, we study a simple cell cycle model that produces oscillations due to the presence of an ultrasensitive, time-delayed negative feedback loop. we implement the time delay in three qualitatively different ... | 2018 | 29579091 |
| proteomic characterization of the neural ectoderm fated cell clones in the xenopus laevis embryo by high-resolution mass spectrometry. | the molecular program by which embryonic ectoderm is induced to form neural tissue is essential to understanding normal and impaired development of the central nervous system. xenopus has been a powerful vertebrate model in which to elucidate this process. however, abundant vitellogenin (yolk) proteins in cells of the early xenopus embryo interfere with protein detection by high-resolution mass spectrometry (hrms), the technology of choice for identifying these gene products. here, we systematic ... | 2018 | 29578674 |
| the right thalamus may play an important role in anesthesia-awakening regulation in frogs. | previous studies have shown that the mammalian thalamus is a key structure for anesthesia-induced unconsciousness and anesthesia-awakening regulation. however, both the dynamic characteristics and probable lateralization of thalamic functioning during anesthesia-awakening regulation are not fully understood, and little is known of the evolutionary basis of the role of the thalamus in anesthesia-awakening regulation. | 2018 | 29576980 |
| incorporation of the δ-subunit into the epithelial sodium channel (enac) generates protease-resistant enacs in xenopus laevis. | the epithelial sodium channel (enac) is a critical regulator of vertebrate electrolyte homeostasis. enac is the only constitutively open ion channel in the degenerin/enac protein family, and its expression, membrane abundance, and open probability therefore are tightly controlled. the canonical enac is composed of three subunits (α, β, and γ), but a fourth δ-subunit may replace α and form atypical δβγ-enacs. using xenopus laevis as a model, here we found that mrnas of the α- and δ-subunits are d ... | 2018 | 29576549 |
| effects of trimethoprim-sulfadiazine and detomidine on the function of equine kv 11.1 channels in a two-electrode voltage-clamp (tevc) oocyte model. | the long qt syndrome (lqts) is a channelopathy that can lead to severe arrhythmia and sudden cardiac death. pharmacologically induced lqts is caused by interaction between drugs and potassium channels, especially the kv 11.1 channel. due to such interactions, numerous drugs have been withdrawn from the market or are administered with precautions in human medicine. however, some compounds, such as trimethoprim-sulfonamide combinations are still widely used in veterinarian medicine. therefore, we ... | 2018 | 29566261 |
| ribosomal rna biogenesis and its response to chilling stress in oryza sativa. | ribosome biogenesis is crucial for plant growth and environmental acclimation. processing of ribosomal rnas (rrnas) is an essential step in ribosome biogenesis and begins with transcription of the rdna. the resulting precursor-rrna (pre-rrna) transcript undergoes systematic processing, where multiple endonucleolytic and exonucleolytic cleavages remove the external and internal transcribed spacers (ets and its). the processing sites and pathways for pre-rrna processing have been deciphered in sac ... | 2018 | 29555785 |
| comparison of etomidate, benzocaine, and ms222 anesthesia with and without subsequent flunixin meglumine analgesia in african clawed frogs (xenopus laevis). | often few alternative anesthetics for exotic species are available, due to the small numbers of these animals used in research. in this study, we evaluated the depth and duration of anesthesia in xenopus laevis after their immersion in 3 doses of etomidate (15, 22.5, and 30 mg/l) and in 3 doses of benzocaine (0.1%, 0.5%, and 1%) compared with the 'gold standard,' tricaine methanesulfonate (ms222; 2 g/l). we then chose an optimal dose for each alternative anesthetic according to induction time, d ... | 2018 | 29555009 |
| differential patterns of inhibition of the sugar transporters glut2, glut5 and glut7 by flavonoids. | only limited data are available on the inhibition of the sugar transporter glut5 by flavonoids or other classes of bioactives. intestinal glut7 is poorly characterised and no information exists concerning its inhibition. we aimed to study the expression of glut7 in caco-2/tc7 intestinal cells, and evaluate inhibition of glucose transport by glut2 and glut7, and of fructose transport by glut2, glut5 and glut7, by flavonoids. differentiated caco-2/tc7 cell monolayers were used to investigate glut7 ... | 2018 | 29548810 |
| satb1 downregulation induced by oxidative stress participates in trophoblast invasion by regulating β-catenin. | preeclampsia (pe) is characterized by abnormal placentation in the early stages of pregnancy. adequate migration and invasion of trophoblasts into the uterine wall and spiral arteries to form a functional maternal-fetal interface are pivotal for normal placentation, but the exact mechanism remains unclear. growing evidence has revealed that special at-rich sequence binding protein 1 (binds to nuclear matrix/scaffold-associating dna) (satb1) is a tumor promoter that participates in cancer cell mi ... | 2018 | 29546272 |
| effects of transportation, transport medium and re-housing on xenopus laevis (daudin). | understanding the immediate and longer-term effects of transportation and re-housing in a laboratory species is crucial in order to refine the transfer process, enable the optimal introduction of new animals to a novel environment and to provide a sufficient acclimatisation period before usage. whilst consideration of animal welfare in most model vertebrate species has received attention, little quantitative evidence exists for the optimal care of the common laboratory amphibian xenopus laevis. ... | 2018 | 29545087 |
| large, long range tensile forces drive convergence during xenopus blastopore closure and body axis elongation. | indirect evidence suggests that blastopore closure during gastrulation of anamniotes, including amphibians such as xenopus laevis, depends on circumblastoporal convergence forces generated by the marginal zone (mz), but direct evidence is lacking. we show that explanted mzs generate tensile convergence forces up to 1.5 μn during gastrulation and over 4 μn thereafter. these forces are generated by convergent thickening (ct) until the midgastrula and increasingly by convergent extension (ce) there ... | 2018 | 29533180 |
| lithobates catesbeianus (american bullfrog) oocytes: a novel heterologous expression system for aquaporins. | xenopus laevis oocytes are a valuable tool for investigating the function of membrane proteins. however, regulations around the world, specifically in brazil, render the import of xenopus laevis frogs impractical, and, in some cases, impossible. here, as an alternative, we evaluate the usefulness of the north american aquatic bullfrog lithobates catesebeianus, which is commercially available in brazil, for the heterologous expression of aquaporin (aqp) proteins. we have developed a method that c ... | 2018 | 29530931 |
| pitx1 regulates cement gland development in xenopus laevis through activation of transcriptional targets and inhibition of bmp signaling. | the cement gland in xenopus laevis has long been used as a model to study the interplay of cell signaling and transcription factors during embryogenesis. it has been shown that an intermediate level of bone morphogenetic protein (bmp) signaling is essential for cement gland formation. in addition, several transcription factors have been linked to cement gland development. one of these, the homeodomain-containing protein pitx1, can generate ectopic cement gland formation; however, the mechanisms ... | 2018 | 29530451 |
| frog's dcs have it all in one. | although the amphibian xenopus laevis produces antibodies as diversified as those from mammals in the primary repertoire, antibody affinity maturation after immunization is relatively poor and has been associated with a poor b cell selection of aid-mediated hypermutations and lack of germinal centers in the spleen, the only secondary lymphoid organ of this amphibian. in this issue of the european journal of immunology, neely et al., [eur. j. immunol. 2018. 48: 430-440] have unveiled the role of ... | 2018 | 29522243 |
| transcriptome analysis identifies genes involved in sex determination and development of xenopus laevis gonads. | development of the gonads is a complex process, which starts with a period of undifferentiated, bipotential gonads. during this period the expression of sex-determining genes is initiated. sex determination is a process triggering differentiation of the gonads into the testis or ovary. sex determination period is followed by sexual differentiation, i.e. appearance of the first testis- and ovary-specific features. in xenopus laevis w-linked dm-domain gene (dm-w) had been described as a master det ... | 2018 | 29518581 |
| c8orf46 homolog encodes a novel protein vexin that is required for neurogenesis in xenopus laevis. | neural basic helix-loop helix (bhlh) transcription factors promote progenitor cell differentiation by activation of downstream target genes that coordinate neuronal differentiation. here we characterize a neural bhlh target gene in xenopus laevis, vexin (vxn; previously sbt1), that is homologous to human c8orf46 and is conserved across vertebrate species. c8orf46 has been implicated in cancer progression, but its function is unknown. vxn is transiently expressed in differentiating progenitors in ... | 2018 | 29518376 |
| investigation of higher-order rna g-quadruplex structures in vitro and in living cells by 19f nmr spectroscopy. | growing evidence indicates that rna g-quadruplexes have important roles in various processes such as transcription, translation, regulation of telomere length, and formation of telomeric heterochromatin. investigation of rna g-quadruplex structures associated with biological events is therefore essential to understanding the functions of these rna molecules. we recently demonstrated that the sensitivity and simplicity of 19f nmr can be used to directly observe higher-order telomeric g-quadruplex ... | 2018 | 29517770 |
| occurrence of batrachochytrium dendrobatidis in anurans of the mediterranean region of baja california, méxico. | chytridiomycosis is caused by the fungal pathogen batrachochytrium dendrobatidis (bd) and is regarded as one of the most significant threats to global amphibian populations. in méxico, bd was first reported in 2003 and has now been documented in 13 states. we visited 33 localities and swabbed 199 wild-caught anurans from 7 species (5 native, 2 exotic) across the mediterranean region of the state of baja california. using quantitative pcr, bd was detected in 94 individuals (47.2% of samples) at 2 ... | 2018 | 29516858 |
| evaluation of the toxic effects of celecoxib on xenopus embryo development. | celecoxib is a non-steroidal anti-inflammatory drug that selectively inhibits cyclooxygenase-2 and is prescribed for severe pain and inflammation. the excellent therapeutic effects of celecoxib mean that it is frequently used clinically, including for women of child-bearing age. however, the prenatal effects of this compound have not been studied extensively in vertebrates. the present study examined the developmental toxicity of celecoxib using a frog embryo teratogenic assay-xenopus (fetax). i ... | 2018 | 29505793 |
| booting up the organism during development: pre-behavioral functions of the vertebrate brain in guiding body morphogenesis. | a recent study in xenopus laevis embryos showed that the very early brain has important functions long before behavior. while the nascent brain is being constructed, it is required for normal patterning of the muscle and peripheral nerve networks, including those far away from the head. in addition to providing important developmental signals to remote tissues in normal embryogenesis, its presence is also able to render harmless exposure to specific chemicals that normally act as teratogens. the ... | 2018 | 29497473 |
| whole-mount in situ hybridization of xenopus oocytes. | whole-mount in situ hybridization (wmish) is a common approach that is used to visualize spatial and temporal gene expression in embryos. in this process, digoxygenin-labeled antisense rna is hybridized to the complementary transcript of interest and rna hybrids are immunohistochemically detected using an alkaline phosphatase-conjugated antibody against digoxigenin. during xenopus laevis oogenesis, certain rnas localize to the animal or vegetal pole laying the foundation for germ cell developmen ... | 2018 | 29496817 |
| identification of circular rnas and their alterations involved in developing male xenopus laevis chronically exposed to atrazine. | atrazine (az) is an environmental endocrine disrupting chemical which can affect the development of amphibians. in our past studies, we demonstrated that chronical exposure to 100 μg/l az can cause abnormalities in development and related genes expression of gonads in developing male xenopus laevis (x. laevis) tadpoles. recent studies by others have demonstrated that circular rnas (circrnas) are implicated in multiple developmental anomalies. however, whether circrnas involve in the effects in a ... | 2018 | 29494910 |
| a nurd complex from xenopus laevis eggs is essential for dna replication during early embryogenesis. | dna replication in the embryo of xenopus laevis changes dramatically at the mid-blastula transition (mbt), with y rna-independent random initiation switching to y rna-dependent initiation at specific origins. here, we identify xnurd, an mta2-containing assemblage of the nucleosome remodeling and histone deacetylation complex nurd, as an essential factor in pre-mbt xenopus embryos that overcomes a functional requirement for y rnas during dna replication. human nurd complexes have a different subu ... | 2018 | 29490265 |
| plasma kallikrein activates the epithelial sodium channel in vitro but is not essential for volume retention in nephrotic mice. | recent work has demonstrated that activation of the epithelial sodium channel (enac) by aberrantly filtered serine proteases causes sodium retention in nephrotic syndrome. the aim of this study was to elucidate a potential role of plasma kallikrein (pklk) as a candidate serine protease in this context. | 2018 | 29489063 |
| hydrolytic activity of human nudt16 enzyme on dinucleotide cap analogs and short capped oligonucleotides. | human nudt16 (hnudt16) is a member of the nudix family of hydrolases, comprising enzymes catabolizing various substrates including canonical (d)ntps, oxidized (d)ntps, nonnucleoside polyphosphates, and capped mrnas. decapping activity of the xenopus laevis (x29) nudt16 homolog was observed in the nucleolus, with a high specificity toward u8 snorna. subsequent studies have reported cytoplasmic localization of mammalian nudt16 with cap hydrolysis activity initiating rna turnover, similar to dcp2. ... | 2018 | 29483298 |
| a novel rhodopsin phosphodiesterase from salpingoeca rosetta shows light-enhanced substrate affinity. | it is since many years textbook knowledge that the concentration of the second messenger cgmp is regulated in animal rod and cone cells by type ii rhodopsins via a g-protein signaling cascade. microbial rhodopsins with enzymatic activity for regulation of cgmp concentration were only recently discovered: in 2014 light-activated guanylyl-cyclase opsins in fungi and in 2017 a novel rhodopsin phosphodiesterase (rhopde) in the protist salpingoeca rosetta (srrhopde). the light regulation of srrhopde, ... | 2018 | 29483295 |
| chromatin characterization in xenopus laevis cell-free egg extracts and embryos. | xenopus laevis development is marked by accelerated cell division solely supported by the proteins maternally deposited in the egg. oocytes mature to eggs with concomitant transcriptional silencing. the unique maternal chromatin state contributing to this silencing and subsequent zygotic activation is likely established by histone posttranslational modifications and histone variants. therefore, tools for understanding the nature and function of maternal and embryonic histones are essential to de ... | 2019 | 29475998 |
| robustly cycling xenopus laevis cell-free extracts in teflon chambers. | a central advantage of studying xenopus laevis is the manipulability of its cell-free extracts, which perform the cell cycle in vitro. however, these extracts are known to be experimentally temperamental and will often complete at most one or two cycles. over the course of developing systems for imaging cell cycle events in extracts in real time, we unexpectedly found that when standard xenopus extracts are placed in teflon tubes, they cycle extremely robustly; in one series of experiments, over ... | 2018 | 29475997 |
| centromere and kinetochore assembly in xenopus laevis egg extract. | during cell division, chromosomes must be equally segregated to daughter cells. centromeres, the primary interaction site between chromosomes and microtubules, mediate faithful chromosome segregation during mitosis. functional studies of centromere proteins in cells have proven difficult, as mutation or deletion of most centromeric proteins often results in cell lethality. in this protocol, sperm chromatin or reconstituted chromatin arrays, together with xenopus laevis egg extracts, are used to ... | 2018 | 29475995 |
| endoplasmic reticulum network formation with xenopus egg extracts. | the endoplasmic reticulum (er) consists of morphologically distinct domains, including a polygonal network of tubules that is connected by three-way junctions. this network is found in all eukaryotic cells. extracts from xenopus laevis eggs contain stockpiles of components that allow the assembly of an er network in vitro. here we provide protocols for assembly of er networks in extracts that are arrested at different stages of the cell cycle. unfertilized xenopus laevis eggs contain a cytostati ... | 2019 | 29475993 |
| xenopus: an alternative model system for identifying muco-active agents. | the airway epithelium in human plays a central role as the first line of defense against environmental contaminants. most respiratory diseases such as chronic obstructive pulmonary disease (copd), asthma, and respiratory infections, disturb normal muco-ciliary functions by stimulating the hypersecretion of mucus. several muco-active agents have been used to treat hypersecretion symptoms in patients. current muco-active reagents control mucus secretion by modulating either airway inflammation, ch ... | 2018 | 29470529 |
| dicer inactivation stimulates limb regeneration ability in xenopus laevis. | the ontogenetic decline of regeneration capacity in the anuran amphibian xenopus makes it an excellent model for regeneration studies. however, the cause of the regeneration ability decline is not fully understood. micrornas regulate animal development and have been indicated in various regeneration situations. however, little is known about the role of micrornas during limb regeneration in xenopus. this study investigates the effect of dicer, an enzyme responsible for microrna maturation, on li ... | 2018 | 29453851 |
| invasive african clawed frogs in california: a reservoir for or predator against the chytrid fungus? | amphibian species are experiencing population declines due to infection by the fungal pathogen, batrachochytrium dendrobatidis (bd). the african clawed frog (xenopus laevis), an asymptomatic carrier of bd, has been implicated in the spread of this pathogen through global trade and established invasive populations on several continents. however, research has not explored the relationships of both life stages of this amphibian with bd. while the post-metamorphic individuals may act as a reservoir, ... | 2018 | 29444096 |
| tissue stiffening coordinates morphogenesis by triggering collective cell migration in vivo. | collective cell migration is essential for morphogenesis, tissue remodelling and cancer invasion. in vivo, groups of cells move in an orchestrated way through tissues. this movement involves mechanical as well as molecular interactions between cells and their environment. while the role of molecular signals in collective cell migration is comparatively well understood, how tissue mechanics influence collective cell migration in vivo remains unknown. here we investigated the importance of mechani ... | 2018 | 29443958 |
| primordial germ cell transplantation for crispr/cas9-based leapfrogging in xenopus. | the creation of mutant lines by genome editing is accelerating genetic analysis in many organisms. crispr/cas9 methods have been adapted for use in the african clawed frog, xenopus, a longstanding model organism for biomedical research. traditional breeding schemes for creating homozygous mutant lines with crispr/cas9-targeted mutagenesis have several time-consuming and laborious steps. to facilitate the creation of mutant embryos, particularly to overcome the obstacles associated with knocking ... | 2018 | 29443056 |
| amphibian zic genes. | studies in xenopus laevis have greatly contributed to understanding the roles that the zic family of zinc finger transcription factors play as essential drivers of early development. explant systems that are not readily available in other organisms give xenopus embryos a unique place in these studies, facilitated by the recent sequencing of the xenopus laevis genome. a number of upstream regulators of zic gene expression have been identified, such as inhibition of bmp signaling, as well as calci ... | 2018 | 29442320 |
| isolation and demembranation of xenopus sperm nuclei. | the inherent experimental advantages of intact amphibian eggs have been exploited for several decades to advance our understanding of fundamental developmental processes and the cell cycle. characterization of these processes at the molecular level has been greatly advanced by the use of cell-free extracts, which permit the development of biochemically tractable approaches. demembranated xenopus laevis sperm nuclei have been used with cell-free extracts to recapitulate cell cycle progression and ... | 2018 | 29438000 |
| preparation of cellular extracts from xenopus eggs and embryos. | cell-free cytoplasmic extracts prepared from xenopus eggs have been used extensively to recapitulate and characterize intracellular events in vitro. egg extracts can be induced to transit the cell cycle and reconstitute assembly of dynamic structures including the interphase nucleus and the mitotic spindle. in this protocol, methods are described for preparing crude cytoplasmic extracts from xenopus eggs and embryos that are arrested in metaphase of the cell cycle. the basic protocol uses unfert ... | 2018 | 29437998 |
| fluorescence in situ hybridization of cryosectioned xenopus oocytes. | xenopus laevis oocytes are widely used to study mechanisms of rna function and biogenesis. while the large size of xenopus oocytes is amenable to both biochemical and imaging approaches, the relative opacity of the yolk-rich cytoplasm has limited high-resolution imaging of endogenous rnas. here, we present a protocol that combines multi-probe fluorescence in situ hybridization with cryosectioning to provide a highly sensitive means of imaging endogenous oocyte rnas. | 2018 | 29437997 |
| assembly of spindles and asters in xenopus egg extracts. | here, we provide methods for assembly of mitotic spindles and interphase asters in xenopus laevis egg extract, and compare them to spindles and asters in the egg and zygote. classic "cycled" spindles are made by adding sperm nuclei to metaphase-arrested cytostatic factor (csf) extract and inducing entry into interphase extract to promote nucleus formation and dna replication. interphase nuclei are then converted to cycled spindles arrested in metaphase by addition of csf extract. kinetochores as ... | 2018 | 29437996 |
| plant cation-chloride cotransporters (ccc): evolutionary origins and functional insights. | genomes of unicellular and multicellular green algae, mosses, grasses and dicots harbor genes encoding cation-chloride cotransporters (ccc). ccc proteins from the plant kingdom have been comparatively less well investigated than their animal counterparts, but proteins from both plants and animals have been shown to mediate ion fluxes, and are involved in regulation of osmotic processes. in this review, we show that ccc proteins from plants form two distinct phylogenetic clades (ccc1 and ccc2). s ... | 2018 | 29415511 |