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diversity of parasites from xenopus laevis (amphibia: pipidae) and their seasonal rate of infection in selected habitats in the limpopo province, south africa.this study determined the diversity and seasonality of parasites species of the african clawed frog, xenopus laevis (daudin, 1802), from three localities, namely modjadjikloof, mokopane and university of limpopo, limpopo province, south africa. a total of seven parasite species were collected and identified. they included two nematodes, camallanus kaapstaadi southwell & kirshner, 1937 and batrachocamallanus slomei (southwell & kirshner, 1937), a monogenean, protopolystoma xenopodis (price, 1943) ...202032855613
blood-brain barrier protein claudin-5 expressed in paired xenopus laevis oocytes mediates cell-cell interaction.claudin-5 determines the sealing properties of blood-brain barrier tight junctions and its function is impaired in neurodegenerative and neuroinflammatory disorders. focusing on the contribution of claudin-5 to the trans-interaction within the tight junction seal, we used xenopus laevis oocytes as an expression system. cells were clustered and challenged in a novel approach for the analysis of claudin interaction. we evaluated the strengthening effect of claudin-5 to cell-cell-connection in comp ...202032848831
a simple and efficient method for visualizing individual cells in vivo by cre-mediated single-cell labeling by electroporation (cremscle).efficient methods for visualizing cell morphology in the intact animal are of great benefit to the study of structural development in the nervous system. quantitative analysis of the complex arborization patterns of brain cells informs cell-type classification, dissection of neuronal circuit wiring, and the elucidation of growth and plasticity mechanisms. time-lapse single-cell morphological analysis requires labeling and imaging of single cells in situ without contamination from the ramified pr ...202032848634
na+ transporter svhkt1;1 from a halophytic turf grass is specifically upregulated by high na+ concentration and regulates shoot na+ concentration.we characterized an na+ transporter svhkt1;1 from a halophytic turf grass, sporobolus virginicus. svhkt1;1 mediated inward and outward na+ transport in xenopus laevis oocytes and did not complement k+ transporter-defective mutant yeast. svhkt1;1 did not complement athkt1;1 mutant arabidopsis, suggesting its distinguishable function from other typical hkt1 transporters. the transcript was abundant in the shoots compared with the roots in s. virginicus and was upregulated by severe salt stress (50 ...202032847126
preliminary indications that recombinant human il-16 attracts and stimulates lymphocytes of the amphibian, xenopus laevis implying an ancestral role for cd4 as a cytokine receptor.the d1 domain of the cd4 co-receptor interacts with mhc class ii during helper cd4+ th-cell activation and effector function in all gnathostomes but the sequence and structure of this region are not well conserved through phylogeny. conversely, the proximal d4 domain of cd4 is the binding site of the cytokine il-16 and is highly conserved, allowing for promiscuous binding of il-16 to cd4 between disparate gnathostomes. we report here that recombinant human il-16 (rhil-16) bound to xenopus lympho ...202032836028
dynamic expression of mmp28 during cranial morphogenesis.matrix metalloproteinases (mmps) are a large family of proteases comprising 24 members in vertebrates. they are well known for their extracellular matrix remodelling activity. mmp28 is the latest member of the family to be discovered. it is a secreted mmp involved in wound healing, immune system maturation, cell survival and migration. mmp28 is also expressed during embryogenesis in human and mouse. here, we describe the detailed expression profile of mmp28 in xenopus laevis embryos. we show tha ...202032829678
effect of obps on the response of olfactory receptors.the technique of two-electrode voltage-clamp (tevc) recording from the heterologous expression system of olfactory receptors (ors) in xenopus laevis oocytes has been widely used to deorphanize insect ors, that is to identify specific ligands for each of them. however, there is a controversial issue on whether ors are activated by the odorant/obp complex or the odorant alone. the mechanism of interaction among odorants, odorant-binding proteins (obps) and ors remains largely unknown, due to the l ...202032828257
new insights into hcptr2a and hcptr2b, two high-affinity peptide transporters from the ectomycorrhizal model fungus hebeloma cylindrosporum.while plants mainly rely on the use of inorganic nitrogen sources like ammonium and nitrate, soil-borne microorganisms like the ectomycorrhizal fungus hebeloma cylindrosporum can also take up soil organic n in the form of amino acids and peptides that they use as nitrogen and carbon sources. following the previous identification and functional expression in yeast of two ptr-like peptide transporters, the present study details the functions and substrates of hcptr2a and hcptr2b by analysing their ...202032820366
identification of the essential extracellular aspartic acids conserved in human monocarboxylate transporters 1, 2, and 4.human monocarboxylate transporters (hmcts) 1-4 transport monocarboxylates, such as l-lactate and pyruvate, as well as h+ across the plasma membrane. hmct1, 2, and 4 play important roles in energy balance, ph homeostasis. however, the molecular mechanism of these transporters, especially their ph dependency, remains unknown. the aim of this study was to identify the residues involved in the ph dependence of hmct1, 2, and 4. firstly, we focused on the effects of extracellular acids of hmct1. l-lac ...202032819565
a non-canonical role for the dna glycosylase neil3 in suppressing ape1 endonuclease-mediated ssdna damage.the dna glycosylase neil3 has been implicated in dna repair pathways including the base excision repair and the interstrand cross-link repair pathways via its dna glycosylase and/or ap lyase activity, which are considered canonical roles of neil3 in genome integrity. compared with the other dna glycosylases neil1 and neil2, xenopus laevis neil3 c terminus has two highly conserved zinc finger motifs containing grxf residues (designated as zf-grf). it has been demonstrated that the minor ap endonu ...202032817342
experiences with the marsupial frogs: reminiscences of a developmental biologist.this article provides a brief account of the career of eugenia m. del pino. casual events and serendipity played important roles in modeling her career as developmental biologist. in collaboration with colleagues and students, she analyzed the biology and development of the marsupial frog gastrotheca riobambae (family: hemiphractidae) in comparison with xenopus laevis and tropical frogs. the emphasis was placed on oogenesis and the early stages of development. topics include the mono- and multi- ...202032813268
design, synthesis, and electrophysiological evaluation of ns6740 derivatives: exploration of the structure-activity relationship for alpha7 nicotinic acetylcholine receptor silent activation.the α7 nicotinic acetylcholine receptor (nachr) silent agonists, able to induce receptor desensitization and promote the α7 metabotropic function, are emerging as new promising therapeutic anti-inflammatory agents. herein, we report the structure-activity relationship investigation of the archetypal silent agonist ns6740 (1,4-diazabicyclo[3.2.2]nonan-4-yl(5-(3-(trifluoromethyl)-phenyl)-furan-2-yl)methanone) (1) to elucidate the ligand-receptor interactions responsible for the α7 silent activatio ...202032810771
α-conotoxin as potential to α7-nachr recombinant expressed in escherichia coli.α7 nicotinic acetylcholine receptors (nachr) is an important nicotinic acetylcholine receptors subtype and closely associated with cognitive disorders, such as alzheimer's and schizophrenia disease. the mutant arib (v11l, v16a) of α-conotoxin arib with 17-amino acid residues specifically targets α7 nachr with no obvious effect on other nachr subtypes. in the study, the synthetic gene encoding mature peptide of arib and mutant arib (v11l, v16a) carried a fusion protein trx and 6 × his-tag was sep ...202032806654
compaction of rna duplexes in the cell.the structure and flexibility of rna depends sensitively on the microenvironment. using pulsed electron-electron double-resonance (peldor)/double electron-electron resonance (deer) spectroscopy combined with advanced labeling techniques, we show that the structure of double-stranded rna (dsrna) changes upon internalization into xenopus laevis oocytes. compared to dilute solution, the dsrna a-helix is more compact in cells. we recapitulate this compaction in a densely crowded protein solution. at ...202032804430
mucociliary epithelial organoids from xenopus embryonic cells: generation, culture and high-resolution live imaging.mucociliary epithelium provides the first line of defense by removing foreign particles through the action of mucus production and cilia-mediated clearance. many clinically relevant defects in the mucociliary epithelium are inferred as they occur deep within the body. here, we introduce a tractable 3d model for mucociliary epithelium generated from multipotent progenitors that were microsurgically isolated from xenopus laevis embryos. the mucociliary epithelial organoids are covered with newly g ...202032804169
conservation of glomerular organization in the main olfactory bulb of anuran larvae.the glomerular array in the olfactory bulb of many vertebrates is segregated into molecularly and anatomically distinct clusters linked to different olfactory functions. in anurans, glomerular clustering is so far only described in xenopus laevis. we traced olfactory projections to the bulb in tadpoles belonging to six distantly related anuran species in four families (pipidae, hylidae, bufonidae, dendrobatidae) and found that glomerular clustering is remarkably conserved. the general bauplan co ...202032792916
mutation affecting the conserved acidic wnk1 motif causes inherited hyperkalemic hyperchloremic acidosis.gain-of-function mutations in with no lysine (k) 1 (wnk1) and wnk4 genes are responsible for familial hyperkalemic hypertension (fhht), a rare, inherited disorder characterized by arterial hypertension and hyperkalemia with metabolic acidosis. more recently, fhht-causing mutations in the kelch-like 3-cullin 3 (klhl3-cul3) e3 ubiquitin ligase complex have shed light on the importance of wnk's cellular degradation on renal ion transport. using full exome sequencing for a 4-generation family and th ...202032790646
monocarboxylate transporter 12 as a guanidinoacetate efflux transporter in renal proximal tubular epithelial cells.guanidinoacetate (gaa), which is a precursor of creatine, is mainly biosynthesized in the renal proximal tubular epithelial cells (rptecs). plasma concentration of gaa has been reported to be reduced in patients with monocarboxylate transporter 12 (mct12) mutation (p.q215x). however, the mechanism underlying gaa release from the rptecs remains unclear. therefore, to elucidate the role of mct12 in renal gaa release, mct12-mediated gaa transport was evaluated using the human and rat mct12-expressi ...202032781157
heterogeneity of synonymous substitution rates in the xenopus frog genome.with the increasing availability of high quality genomic data, there is opportunity to deeply explore the genealogical relationships of different gene loci between closely related species. in this study, we utilized genomes of xenopus laevis (xla, a tetraploid species with (l) and (s) sub-genomes) and x. tropicalis (xtr, a diploid species) to investigate whether synonymous substitution rates among orthologous or homoeologous genes displayed any heterogeneity. from over 1500 orthologous/homoeolog ...202032764757
the specific molecular composition and structural arrangement of eleutherodactylus coqui gular skin tissue provide its high mechanical compliance.a male eleutherodactylus coqui (ec, a frog) expands and contracts its gular skin to a great extent during mating calls, displaying its extraordinarily compliant organ. there are striking similarities between frog gular skin and the human bladder as both organs expand and contract significantly. while the high extensibility of the urinary bladder is attributed to the unique helical ultrastructure of collagen type iii, the mechanism behind the gular skin of ec is unknown. we therefore aim to under ...202032764252
sequential purification and characterization of torpedo californica nachr-dc supplemented with chs for high-resolution crystallization studies.over the past 10 years we have been developing a multi-attribute analytical platform that allows for the preparation of milligram amounts of functional, high-pure, and stable torpedo (muscle-type) nachr detergent complexes for crystallization purpose. in the present work, we have been able to significantly improve and optimize the purity and yield of nicotinic acetylcholine receptors in detergent complexes (nachr-dc) without compromising stability and functionality. we implemented new methods in ...202032763308
comparative gene expression profiling between optic nerve and spinal cord injury in xenopus laevis reveals a core set of genes inherent in successful regeneration of vertebrate central nervous system axons.the south african claw-toed frog, xenopus laevis, is uniquely suited for studying differences between regenerative and non-regenerative responses to cns injury within the same organism, because some cns neurons (e.g., retinal ganglion cells after optic nerve crush (onc)) regenerate axons throughout life, whereas others (e.g., hindbrain neurons after spinal cord injury (sci)) lose this capacity as tadpoles metamorphose into frogs. tissues from these cns regions (frog onc eye, tadpole sci hindbrai ...202032758133
grp94 regulates the recruitment of aneural achr clusters for the assembly of postsynaptic specializations by modulating adf/cofilin activity and turnover.temperature is a physiological factor that affects neuronal growth and synaptic homeostasis at the invertebrate neuromuscular junctions (nmjs); however, whether temperature stress could also regulate the structure and function of the vertebrate nmjs remains unclear. in this study, we use xenopus laevis primary cultures as a vertebrate model system for investigating the involvement of heat shock protein 90 (hsp90) family of stress proteins in nmj development. first, cold temperature treatment or ...202032747457
exploring the relationships between amphibian (xenopus laevis) myeloid cell subsets.the differentiation of distinct leukocyte subsets is governed by lineage-specific growth factors that elicit disparate expression of transcription factors and markers by the developing cell populations. for example, macrophages (mφs) and granulocytes (grns) arise from common granulocyte-macrophage progenitors in response to distinct myeloid growth factors. in turn, myelopoiesis of the xenopus laevis anuran amphibian appears to be unique to other studied vertebrates in several respects while the ...202032745480
analysis of pallial/cortical interneurons in key vertebrate models of testudines, anurans and polypteriform fishes.the organization of the pallial derivatives across vertebrates follows a comparable elementary arrangement, although not all of them possess a layered cortical structure as sophisticated as the cerebral cortex of mammals. however, its expansion along evolution has only been possible by the development and coevolution of the cellular networks formed by excitatory neurons and inhibitory interneurons. thus, the comparative analysis of interneuron types in vertebrate models of key evolutionary signi ...202032743670
rare heterozygous gdf6 variants in patients with renal anomalies.although over 50 genes are known to cause renal malformation if mutated, the underlying genetic basis, most easily identified in syndromic cases, remains unsolved in most patients. in search of novel causative genes, whole-exome sequencing in a patient with renal, i.e., crossed fused renal ectopia, and extrarenal, i.e., skeletal, eye, and ear, malformations yielded a rare heterozygous variant in the gdf6 gene encoding growth differentiation factor 6, a member of the bmp family of ligands. previo ...202032737436
new insights in the mode of action of (+)-erythravine and (+)-11α-hydroxy-erythravine alkaloids.erythrinian alkaloids ((+)-erythravine and (+)-11-α-hydroxy-erythravine) have been pointed as the main responsible agents for the anticonvulsant and anxiolytic properties of erythrina mulungu mart ex benth. the present work provides a new set of information about the mode of action of these alkaloids by the use of a complementary approach of neurochemical and electrophysiological assays. we propose here that the antiepileptic and anxiolytic properties exhibited by both alkaloids appear not to be ...202032735983
zinc protection of fertilized eggs is an ancient feature of sexual reproduction in animals.one of the earliest and most prevalent barriers to successful reproduction is polyspermy, or fertilization of an egg by multiple sperm. to prevent these supernumerary fertilizations, eggs have evolved multiple mechanisms. it has recently been proposed that zinc released by mammalian eggs at fertilization may block additional sperm from entering. here, we demonstrate that eggs from amphibia and teleost fish also release zinc. using xenopus laevis as a model, we document that zinc reversibly block ...202032735558
polyploidization and pseudogenization in allotetraploid frog xenopus laevis promote the evolution of aquaporin family in higher vertebrates.aquaporins (aqps), as members of the major intrinsic protein (mip) superfamily, facilitated the permeation of water and other solutes and are involved in multiple biological processes. aqp family exists in almost all living organisms and is highly diversified in vertebrates in both classification and function due to genome wide duplication. while some aqp orthologs have been lost in higher vertebrates through evolution.202032727380
postsynaptic and presynaptic nmdars have distinct roles in visual circuit development.to study contributions of n-methyl-d-aspartate receptors (nmdars) in presynaptic and postsynaptic neurons of the developing visual system, we microinject antisense morpholino oligonucleotide (mo) against glun1 into one cell of two-cell-stage xenopus laevis embryos. the resulting bilateral segregation of mo induces postsynaptic nmdar (postnmdar) knockdown in tectal neurons on one side and presynaptic nmdar (prenmdar) knockdown in ganglion cells projecting to the other side. postnmdar knockdown re ...202032726620
defective heart chamber growth and myofibrillogenesis after knockout of adprhl1 gene function by targeted disruption of the ancestral catalytic active site.adp-ribosylhydrolase-like 1 (adprhl1) is a pseudoenzyme expressed in the developing heart myocardium of all vertebrates. in the amphibian xenopus laevis, knockdown of the two cardiac adprhl1 protein species (40 and 23 kda) causes failure of chamber outgrowth but this has only been demonstrated using antisense morpholinos that interfere with rna-splicing. transgenic production of 40 kda adprhl1 provides only part rescue of these defects. crispr/cas9 technology now enables targeted mutation of the ...202032726316
gitx1(β/κ-theraphotoxin-gi1a), a novel toxin from the venom of brazilian tarantula grammostola iheringi (mygalomorphae, theraphosidae): isolation, structural assessments and activity on voltage-gated ion channels.spider venoms, despite their toxicity, represent rich sources of pharmacologically active compounds with biotechnological potential. however, in view of the large diversity of the spider species, the full potential of their venom molecules is still far from being known. in this work, we report the purification and structural and functional characterization of gitx1 (β/κ-trtx-gi1a), the first toxin purified from the venom of the brazilian tarantula spider grammostola iheringi. gitx1 was purified ...202032717411
nicotinic acetylcholine receptors: ex-vivo expression of functional, non-hybrid, heteropentameric receptors from a marine arthropod, lepeophtheirus salmonis.nicotinic acetylcholine receptors (nachrs) are ligand-gated ion channels mostly located in the post-synaptic membrane of cholinergic synapses. the natural neurotransmitter is acetylcholine, but they are also the direct targets for neonicotinoids, chemicals widely used against ectoparasites, arthropod vectors and agricultural pests. there are significant concerns regarding adverse effects of neonicotinoids on beneficial insects. in arthropods, functional nachrs made of α subunits have been expres ...202032716968
redox priming promotes aurora a activation during mitosis.cell cycle-dependent redox changes can mediate transient covalent modifications of cysteine thiols to modulate the activities of regulatory kinases and phosphatases. our previously reported finding that protein cysteine oxidation is increased during mitosis relative to other cell cycle phases suggests that redox modifications could play prominent roles in regulating mitotic processes. the aurora family of kinases and their downstream targets are key components of the cellular machinery that ensu ...202032694171
intracellular motor-driven transport of rodlike smooth organelles along microtubules.molecular motors are fascinating proteins that use the energy of atp hydrolysis to drive vesicles and organelles along cytoskeleton filaments toward their final destination within the cell. several copies of these proteins bind to the cargo and take turns transporting the cargo attaching to and detaching from the track stochastically. despite the relevance of molecular motors to cell physiology, key aspects of their collective functioning are still unknown. in this work we propose a one-dimensio ...202032688554
the influence of long-term cadmium exposure on the male advertisement call of xenopus laevis.cadmium (cd) is a non-essential environmental endocrine-disrupting compound found in water and a potential threat to aquatic habitats. cd has been shown to have various short-term effects on aquatic animals; however, evidence for long-term effects of cd on vocal communications in amphibians is lacking. to better understand the long-term effects of low-dose cd on acoustic communication in amphibians, male xenopus laevis individuals were treated with low cd concentrations (0.1, 1, and 10 μg/l) via ...202031889288
several phosphate transport processes are present in vascular smooth muscle cells.we have studied inorganic phosphate (pi) handling in rat aortic vascular smooth muscle cells (vsmc) using 32p-radiotracer assays. our results have revealed a complex set of mechanisms consisting of 1) well-known pit1/pit2-mediated sodium-dependent pi transport; 2) slc20-unrelated sodium-dependent pi transport that is sensitive to the stilbene derivatives 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (dids) and 4-acetamido-4-isothiocyanostilbene-2,2-disulfonate (sits); 3) a sodium-independe ...202031886722
bringing immersive science to undergraduate laboratory courses using crispr gene knockouts in frogs and butterflies.the use of crispr/cas9 for gene editing offers new opportunities for biology students to perform genuine research exploring the gene-to-phenotype relationship. it is important to introduce the next generation of scientists, health practitioners and other members of society to the technical and ethical aspects of gene editing. here, we share our experience leading hands-on undergraduate laboratory classes, where students formulate hypotheses regarding the roles of candidate genes involved in deve ...202032034043
annexin a3 is necessary for parallel artery-vein alignment in the mouse retina.annexin a3 (anxa3) is a member of the calcium-regulated, cell membrane-binding family of annexin proteins. we previously confirmed that anxa3 is expressed in the endothelial lineage in vertebrates and that loss of anxa3 in xenopus laevis leads to embryonic blood vessel defects. however, the biological function of anxa3 in mammals is completely unknown. in order to investigate anxa3 vascular function in mammals, we generated an endothelial cell-specific anxa3 conditional knockout mouse model (anx ...202032020697
human cationic amino acid transporters are not affected by direct nitros(yl)ation.a direct inhibiting effect of no on the function of cat-1 and -2a has been postulated to occur via nitrosylation of cysteine residues in the transporters. neither the no donor snap nor a mixture of sin-1 and spermine nonoate, that generates the strong nitrosating agent n2o3, reduced cat-mediated l-arginine transport. direct nitros(yl)ation does either not occur in cats or does not affect their transport function. a regulatory effect of no or nitrosating agents on cat-mediated transport under phy ...202032008093
structural basis of the fanconi anemia-associated mutations within the fanca and fancg complex.monoubiquitination of the fanconi anemia complementation group d2 (fancd2) protein by the fa core ubiquitin ligase complex is the central event in the fa pathway. fanca and fancg play major roles in the nuclear localization of the fa core complex. mutations of these two genes are the most frequently observed genetic alterations in fa patients, and most point mutations in fanca are clustered in the c-terminal domain (ctd). to understand the basis of the fa-associated fanca mutations, we determine ...202032002546
tectal crfr1 receptor involvement in avoidance and approach behaviors in the south african clawed frog, xenopus laevis.animals in the wild must balance food intake with vigilance for predators in order to survive. the optic tectum plays an important role in the integration of external (predators) and internal (energy status) cues related to predator defense and prey capture. however, the role of neuromodulators involved in tectal sensorimotor processing is poorly studied. recently we showed that tectal crfr1 receptor activation decreases food intake in the south african clawed frog, xenopus laevis, suggesting th ...202032001211
cav2.1 c-terminal fragments produced in xenopus laevis oocytes do not modify the channel expression and functional properties.the sequence and genomic organization of the cacna1a gene that encodes the cav2.1 subunit of both p and q-type ca2+ channels are well conserved in mammals. in human, rat and mouse cacna1a, the use of an alternative acceptor site at the exon 46-47 boundary results in the expression of a long cav2.1 splice variant. in transfected cells, the long isoform of human cav2.1 produces a c-terminal fragment, but it is not known whether this fragment affects cav2.1 expression or functional properties. here ...202031981388
subcellular localization of the tff peptides xp1 and xp4 in the xenopus laevis gastric/esophageal mucosa: different secretion modes reflecting diverse protective functions.the tff peptides xp1 and xp4 from xenopus laevis are orthologs of tff1 and tff2, respectively. xp1 is secreted as a monomer from gastric surface mucous cells and is generally not associated with mucins, whereas xp4 is a typical secretory peptide from esophageal goblet cells, and gastric mucous neck and antral gland cells tightly associated as a lectin with the ortholog of mucin muc6. both tff peptides have diverse protective functions, xp1 as a scavenger for reactive oxygen species preventing ox ...202031979419
expression of α3β2β4 nicotinic acetylcholine receptors by rat adrenal chromaffin cells determined using novel conopeptide antagonists.adrenal chromaffin cells release neurotransmitters in response to stress and may be involved in conditions such as post-traumatic stress and anxiety disorders. neurotransmitter release is triggered, in part, by activation of nicotinic acetylcholine receptors (nachrs). however, despite decades of use as a model system for studying exocytosis, the nachr subtypes involved have not been pharmacologically identified. quantitative real-time pcr of rat adrenal medulla revealed an abundance of mrnas for ...202031967330
hydrogen sulfide impairs meiosis resumption in xenopuslaevis oocytes.the role of hydrogen sulfide (h2s) is addressed in xenopuslaevis oocytes. three enzymes involved in h2s metabolism, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase, were detected in prophase i and metaphase ii-arrested oocytes and drove an acceleration of oocyte meiosis resumption when inhibited. moreover, meiosis resumption is associated with a significant decrease in endogenous h2s. on another hand, a dose-dependent inhibition was obtained using the h2 ...202031963573
convergent extension in the amphibian, xenopus laevis.this review is a comprehensive analysis of the cell biology and biomechanics of convergent extension in xenopus.202031959291
biochemical reconstitution of branching microtubule nucleation.microtubules are nucleated from specific locations at precise times in the cell cycle. however, the factors that constitute these microtubule nucleation pathways and their mode of action still need to be identified. using purified xenopus laevis proteins we biochemically reconstitute branching microtubule nucleation, which is critical for chromosome segregation. we found that besides the microtubule nucleator gamma-tubulin ring complex (γ-turc), the branching effectors augmin and tpx2 are requir ...202031933480
developmental and lethal effects of glyphosate and a glyphosate-based product on xenopus laevis embryos and tadpoles.effects of pure glyphosate and a glyphosate-based product were evaluated comparatively using two embryonic development stages of xenopus laevis as model system. when pure glyphosate was applied in ph adjusted media, lethal or developmental effects were not observed at concentrations up to 500 mg l-1. the 96 h lc50 values for the commercial herbicide, in contrast, were 32.1 and 35.1 mg active ingredient l-1 for embryos and tadpoles, respectively. since pure glyphosate has no effect on the selecte ...202031932905
reciprocal matched filtering in the inner ear of the african clawed frog (xenopus laevis).anurans (frogs and toads) are the most vocal amphibians. in most species, only males produce advertisement calls for defending territories and attracting mates. female vocalizations are the exceptions among frogs, however in the african clawed frog (xenopus laevis) both males and females produce distinct vocalizations. the matched filter hypothesis predicts a correspondence between peripheral auditory tuning of receivers and properties of species-specific acoustic signals, but few studies have a ...202031907715
xenopus embryos show a compensatory response following perturbation of the notch signaling pathway.as an essential feature of development, robustness ensures that embryos attain a consistent phenotype despite genetic and environmental variation. the growing number of examples demonstrating that embryos can mount a compensatory response to germline mutations in key developmental genes has heightened interest in the phenomenon of embryonic robustness. while considerable progress has been made in elucidating genetic compensation in response to germline mutations, the diversity, mechanisms, and l ...202031899211
generation, coordination, and evolution of neural circuits for vocal communication.in many species, vocal communication is essential for coordinating social behaviors including courtship, mating, parenting, rivalry, and alarm signaling. effective communication requires accurate production, detection, and classification of signals, as well as selection of socially appropriate responses. understanding how signals are generated and how acoustic signals are perceived is key to understanding the neurobiology of social behaviors. here we review our long-standing research program foc ...202031896561
genome-wide analysis identifies cis-acting elements regulating mrna polyadenylation and translation during vertebrate oocyte maturation.most cells change patterns of gene expression through transcriptional regulation. in contrast, oocytes are transcriptionally silent and regulate mrna poly(a) tail length to control protein production. however, the genome-wide relationship of poly(a) tail changes to mrna translation during vertebrate oocyte maturation is not known. we used tail-seq and polyribosome analysis to measure poly(a) tail and translational changes during oocyte maturation in xenopus laevis we identified large-scale poly( ...202031896558
chemical and voltage gating of gap junction channels expressed in xenopus oocytes.in most tissues, cells in contact with each other directly intercommunicate via cell-to-cell channels aggregated at gap junctions. direct cell-to-cell communication provides a fundamental mechanism for coordinating many cellular functions in mature and developing organs, as it enables free exchange of small cytosolic molecules. gap junction channels are regulated by a chemical gating mechanism sensitive to cytosolic calcium concentration [ca2+]i in the nanomolar range mediated by ca2+-activated ...202032548808
investigating the impact of the phosphorylation status of tyrosine residues within the tacc domain of tacc3 on microtubule behavior during axon growth and guidance.axon guidance is a critical process in forming the connections between a neuron and its target. the growth cone steers the growing axon toward the appropriate direction by integrating extracellular guidance cues and initiating intracellular signal transduction pathways downstream of these cues. the growth cone generates these responses by remodeling its cytoskeletal components. regulation of microtubule dynamics within the growth cone is important for making guidance decisions. tacc3, as a micro ...202032543081
the transition state and regulation of γ-turc-mediated microtubule nucleation revealed by single molecule microscopy.determining how microtubules (mts) are nucleated is essential for understanding how the cytoskeleton assembles. while the mt nucleator, γ-tubulin ring complex (γ-turc) has been identified, precisely how γ-turc nucleates a mt remains poorly understood. here, we developed a single molecule assay to directly visualize nucleation of a mt from purified xenopus laevis γ-turc. we reveal a high γ-/αβ-tubulin affinity, which facilitates assembly of a mt from γ-turc. whereas spontaneous nucleation require ...202032538784
functional characterization of the arabidopsis ammonium transporter atamt1;3 with the emphasis on structural determinants of substrate binding and permeation properties.atamt1;3 is a major contributor to high-affinity ammonium uptake in arabidopsis roots. using a stable electrophysiological recording strategy, we demonstrate in xenopus laevis oocytes that atamt1;3 functions as a typical high-affinity nh4+ uniporter independent of protons and ca2+. the findings that atamt1;3 transports methylammonium (mea+, a chemical analog of nh4+) with extremely low affinity (km in the range of 2.9-6.1 mm) led to investigate the mechanisms underlying substrate binding. homolo ...202032528489
hcn2 channel-induced rescue of brain teratogenesis via local and long-range bioelectric repair.embryonic exposure to the teratogen nicotine results in brain defects, by disrupting endogenous spatial pre patterns necessary for normal brain size and patterning. extending prior work in xenopus laevis that showed that misexpression of ion channels can rescue morphogenesis, we demonstrate and characterize a novel aspect of developmental bioelectricity: channel-dependent repair signals propagate long-range across the embryo. we show that distal hcn2 channel misexpression and distal transplants ...202032528251
xela ds2 and xela vs2: two novel skin epithelial-like cell lines from adult african clawed frog (xenopus laevis) and their response to an extracellular viral dsrna analogue.the skin epithelial layer acts as an important immunological barrier against pathogens and is capable of recognizing and responding to pathogen-associated molecular patterns (pamps) in human and mouse models. although presumed, it is unknown whether amphibian skin epithelial cells exhibit the ability to respond to pamps such as viral double-stranded rna (dsrna). to address this, two cell lines from the dorsal skin (xela ds2) and ventral skin (xela vs2) of the african clawed frog (xenopus laevis) ...202032526291
monoterpenes differently regulate acid-sensitive and mechano-gated k2p channels.potassium k2p ("leak") channels conduct current across the entire physiological voltage range and carry leak or "background" currents that are, in part, time- and voltage-independent. the activity of k2p channels affects numerous physiological processes, such as cardiac function, pain perception, depression, neuroprotection, and cancer development. we have recently established that, when expressed in xenopus laevis oocytes, k2p2.1 (trek-1) channels are activated by several monoterpenes (mts). he ...202032508645
evolution of the endothelin pathway drove neural crest cell diversification.neural crest cells (nccs) are migratory, multipotent embryonic cells that are unique to vertebrates and form an array of clade-defining adult features. the evolution of nccs has been linked to various genomic events, including the evolution of new gene-regulatory networks1,2, the de novo evolution of genes3 and the proliferation of paralogous genes during genome-wide duplication events4. however, conclusive functional evidence linking new and/or duplicated genes to ncc evolution is lacking. endo ...202032939088
establishing embryonic territories in the context of wnt signaling.this review highlights the work that my research group has been developing, together with international collaborators, during the last decade. since we were able to establish xenopus laevis experimental model in brazil we have been focused on understanding early embryonic patterns regarding neural induction and axes establishment. in this context, wnt pathway appears as a major player and has been much explored by us and other research groups. here we chose to review three published works that w ...202032930371
a collision coupling model governs the activation of neuronal girk1/2 channels by muscarinic-2 receptors.the g protein-activated inwardly rectifying k+-channel (girk) modulates heart rate and neuronal excitability. following g-protein coupled receptor (gpcr)-mediated activation of heterotrimeric g proteins (gαβγ), opening of the channel is obtained by direct binding of gβγ subunits. interestingly, girks are solely activated by gβγ subunits released from gαi/o-coupled gpcrs, despite the fact that all receptor types, for instance gαq-coupled, are also able to provide gβγ subunits. it is proposed that ...202032903404
lethal and teratogenic impacts of imazapyr, diquat dibromide, and glufosinate ammonium herbicide formulations using frog embryo teratogenesis assay-xenopus (fetax).globally, amphibians are experiencing widespread abnormalities and population declines. one potential contributor to these challenges is the use of pesticides, particularly aquatic herbicides applied to aquatic habitats inhabited by amphibians. critical issues of concern are the potential toxicity and teratogenicity of these herbicides towards amphibians. using the fetax protocol, three globally used formulations, including diquat dibromide (midstream), glufosinate ammonium (basta), and imazapyr ...202032901337
maximizing crispr/cas9 phenotype penetrance applying predictive modeling of editing outcomes in xenopus and zebrafish embryos.crispr/cas9 genome editing has revolutionized functional genomics in vertebrates. however, crispr/cas9 edited f0 animals too often demonstrate variable phenotypic penetrance due to the mosaic nature of editing outcomes after double strand break (dsb) repair. even with high efficiency levels of genome editing, phenotypes may be obscured by proportional presence of in-frame mutations that still produce functional protein. recently, studies in cell culture systems have shown that the nature of cris ...202032887910
tetrapeptide ac-haee-nh2 protects α4β2 nachr from inhibition by aβ.the cholinergic deficit in alzheimer's disease (ad) may arise from selective loss of cholinergic neurons caused by the binding of aβ peptide to nicotinic acetylcholine receptors (nachrs). thus, compounds preventing such an interaction are needed to address the cholinergic dysfunction. recent findings suggest that the 11evhh14 site in aβ peptide mediates its interaction with α4β2 nachr. this site contains several charged amino acid residues, hence we hypothesized that the formation of aβ-α4β2 nac ...202032872553
phosphorylation influences water and ion channel function of atpip2;1.the phosphorylation state of two serine residues within the c-terminal domain of atpip2;1 (s280, s283) regulates its plasma membrane localization in response to salt and osmotic stress. here, we investigated whether the phosphorylation state of s280 and s283 also influence atpip2;1 facilitated water and cation transport. a series of single and double s280 and s283 phosphomimic and phosphonull atpip2;1 mutants were tested in heterologous systems. in xenopus laevis oocytes, phosphomimic mutants at ...202032678928
predation threats for a 24-h period activated the extension of axons in the brains of xenopus tadpoles.the threat of predation is a driving force in the evolution of animals. we have previously reported that xenopus laevis enhanced their tail muscles and increased their swimming speeds in the presence of japanese larval salamander predators. herein, we investigated the induced gene expression changes in the brains of tadpoles under the threat of predation using 3'-tag digital gene expression profiling. we found that many muscle genes were expressed after 24 h of exposure to predation. ingenuity p ...202032678123
electrophysiological effects of non-vitamin k antagonist oral anticoagulants on atrial repolarizing potassium channels.non-vitamin k antagonist oral anticoagulants (noacs) are widely used in the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation (af). the efficacy of noacs has been attributed in part to pleiotropic effects that are mediated through effects on thrombin, factor xa, and their respective receptors. direct pharmacological effects of noacs and cardiac ion channels have not been addressed to date. we hypothesized that the favourable clinical outcome of noac use ...202032676673
functional and regulatory characterization of three amts in maize roots.maize grows in nitrate-dominated dryland soils, but shortly upon localized dressing of nitrogen fertilizers, ammonium is retained as a noticeable form of nitrogen source available to roots. thus in addition to nitrate, the absorption of ammonium can be an important strategy that promotes rapid plant growth at strong nitrogen demanding stages. the present study reports the functional characterization of three root-expressed ammonium transporters (amts), aiming at finding out functional and regula ...202032676086
mechanosensitivity is an essential component of phototransduction in vertebrate rods.photoreceptors are specialized cells devoted to the transduction of the incoming visual signals. rods are able also to shed from their tip old disks and to synthesize at the base of the outer segment (os) new disks. by combining electrophysiology, optical tweezers (ots), and biochemistry, we investigate mechanosensitivity in the rods of xenopus laevis, and we show that 1) mechanosensitive channels (mscs), transient receptor potential canonical 1 (trpc1), and piezo1 are present in rod inner segme ...202032667916
role of taalmt1 malate-gaba transporter in alkaline ph tolerance of wheat.malate exudation through wheat (triticum aestivum l) aluminium-activated malate transporter 1 (taalmt1) confers al3+ tolerance at low ph, but is also activated by alkaline ph, and is regulated by and facilitates significant transport of gamma-aminobutyric acid (gaba, a zwitterionic buffer). therefore, taalmt1 may facilitate acidification of an alkaline rhizosphere by promoting exudation of both malate and gaba. here, the performance of wheat near isogenic lines et8 (al+3 -tolerant, high taalmt1 ...202032666573
slc12a2 variants cause a neurodevelopmental disorder or cochleovestibular defect.the slc12 gene family consists of slc12a1-slc12a9, encoding electroneutral cation-coupled chloride co-transporters. scl12a2 has been shown to play a role in corticogenesis and therefore represents a strong candidate neurodevelopmental disorder gene. through trio exome sequencing we identified de novo mutations in slc12a2 in six children with neurodevelopmental disorders. all had developmental delay or intellectual disability ranging from mild to severe. two had sensorineural deafness. we also id ...202032658972
oxidized glutathione increases delta-subunit expressing epithelial sodium channel activity in xenopus laevis oocytes.epithelial sodium channels (enac) are heterotrimeric structures, made up of α, β, and γ subunits, and play an important role in maintaining fluid homeostasis. when δ-enac subunits are expressed in place of (or in addition to) the α-enac subunit alongside β- and γ- subunits, fundamental changes in the biophysical properties of enac can be observed. using human enac crna constructs and the xenopas laevis oocyte expression system, we show that oxidized glutathione (gssg) differently effects αβγ-ena ...202032656545
mambalgin-2 induces cell cycle arrest and apoptosis in glioma cells via interaction with asic1a.gliomas are fast growing and highly invasive brain tumors, characterized by tumor microenvironment acidification that drives glioma cell growth and migration. channels containing acid-sensing ion channel 1a subunit (asic1a) mediate amiloride-sensitive cation influx in late stage glioma cells, but not in normal astrocytes. thus, selective targeting of asic1a can be a perspective strategy for glioma treatment. here, asic1a expression in u251 mg and a172 glioma cells, but not in normal astrocytes, ...202032650495
transcriptomic analysis identifies early cellular and molecular events by which estrogen disrupts testis differentiation and causes feminization in xenopus laevis.extensive studies have shown that estrogenic endocrine-disrupting chemicals (edcs) can disrupt testis differentiation and even cause feminization in vertebrates. however, little is known about the mechanisms by which estrogenic edcs disrupt testis differentiation. here, we employed xenopus laevis, a model amphibian species sensitive to estrogenic edcs, to explore the molecular and cellular events by which 17β-estradiol (e2) disrupts testis differentiation and causes feminization. following water ...202032645606
altered glutaminase 1 activity during neurulation and its potential implications in neural tube defects.the neurulation process is regulated by a large amount of genetic and environmental factors that determine the establishment, folding, and fusion of the neural plate to form the neural tube, which develops into the main structure of the central nervous system. a recently described factor involved in this process is glutamate. through nmda ionotropic receptor, glutamate modifies intracellular ca2+ dynamics allowing the oriented cell migration and proliferation, essentials processes in neurulation ...202032636743
the histone h3-h4 tetramer is a copper reductase enzyme.eukaryotic histone h3-h4 tetramers contain a putative copper (cu2+) binding site at the h3-h3' dimerization interface with unknown function. the coincident emergence of eukaryotes with global oxygenation, which challenged cellular copper utilization, raised the possibility that histones may function in cellular copper homeostasis. we report that the recombinant xenopus laevis h3-h4 tetramer is an oxidoreductase enzyme that binds cu2+ and catalyzes its reduction to cu1+ in vitro. loss- and gain-o ...202032631887
heterologous expression of concatenated nicotinic ach receptors: pros and cons of subunit concatenation and recommendations for construct designs.concatenation of cys-loop receptor subunits is a commonly used technique to ensure experimental control of receptor assembly. however, we recently demonstrated that widely used constructs did not lead to the expression of uniform pools of ternary and more complex receptors. the aim was therefore to identify viable strategies for designing concatenated constructs that would allow strict control of resultant receptor pools.202032627170
relationship between oxygen consumption and neuronal activity in a defined neural circuit.neuronal computations related to sensory and motor activity along with the maintenance of spike discharge, synaptic transmission, and associated housekeeping are energetically demanding. the most efficient metabolic process to provide large amounts of energy equivalents is oxidative phosphorylation and thus dependent on o2 consumption. therefore, o2 levels in the brain are a critical parameter that influences neuronal function. measurements of o2 consumption have been used to estimate the cost o ...202032615976
comprehensive imaging of sensory-evoked activity of entire neurons within the awake developing brain using ultrafast aod-based random-access two-photon microscopy.determining how neurons transform synaptic input and encode information in action potential (ap) firing output is required for understanding dendritic integration, neural transforms and encoding. limitations in the speed of imaging 3d volumes of brain encompassing complex dendritic arbors in vivo using conventional galvanometer mirror-based laser-scanning microscopy has hampered fully capturing fluorescent sensors of activity throughout an individual neuron's entire complement of synaptic inputs ...202032612514
cofactor-enabled functional expression of fruit fly, honeybee, and bumblebee nicotinic receptors reveals picomolar neonicotinoid actions.the difficulty of achieving robust functional expression of insect nicotinic acetylcholine receptors (nachrs) has hampered our understanding of these important molecular targets of globally deployed neonicotinoid insecticides at a time when concerns have grown regarding the toxicity of this chemotype to insect pollinators. we show that thioredoxin-related transmembrane protein 3 (tmx3) is essential to enable robust expression in xenopus laevis oocytes of honeybee (apis mellifera) and bumblebee ( ...202032611810
disabled-2: a positive regulator of the early differentiation of myoblasts.dab2 is an adaptor protein and a tumor suppressor. our previous study has found that dab2 was expressed in early differentiating skeletal muscles in mouse embryos. in this study, we determined the role of dab2 in the skeletal muscle differentiation using c2c12 myoblasts in vitro and xenopus laevis embryos in vivo. the expression of dab2 was increased in c2c12 myoblasts during the formation of myotubes in vitro. knockdown of dab2 expression in c2c12 myoblasts resulted in a reduction of myotube fo ...202032607799
comparing the effect of triadimefon and its metabolite on male and female xenopus laevis: obstructed growth and gonad morphology.amphibians are the most endangered class of vertebrates. in this study, xenopus laevis frogs were exposed to 0, 1 and 10 mg/l of triadimefon or triadimenol. after 14 or 28 days of exposure, high levels of triadimefon or triadimenol obstructed the growth of frogs. however, low levels of triadimefon induced the growth of females after the longer period of exposure. we also found that the antioxidant enzyme activity and ldh levels in males were higher than those in females after 28-days exposure. i ...202032603964
the histone chaperone fact induces cas9 multi-turnover behavior and modifies genome manipulation in human cells.cas9 is a prokaryotic rna-guided dna endonuclease that binds substrates tightly in vitro but turns over rapidly when used to manipulate genomes in eukaryotic cells. little is known about the factors responsible for dislodging cas9 or how they influence genome engineering. unbiased detection through proximity labeling of transient protein interactions in cell-free xenopus laevis egg extract identified the dimeric histone chaperone facilitates chromatin transcription (fact) as an interactor of sub ...202032603710
active forces shape the metaphase spindle through a mechanical instability.the metaphase spindle is a dynamic structure orchestrating chromosome segregation during cell division. recently, soft matter approaches have shown that the spindle behaves as an active liquid crystal. still, it remains unclear how active force generation contributes to its characteristic spindle-like shape. here we combine theory and experiments to show that molecular motor-driven forces shape the structure through a barreling-type instability. we test our physical model by titrating dynein act ...202032601228
a turripeptide from polystira nobilis venom inhibits human α3β2 and α7 nicotinic acetylcholine receptors.almost all marine snails within superfamily conoidea produce venoms containing numerous neuroactive peptides. most toxins characterized from members of this superfamily are produced by species belonging to family conidae. these toxins (conotoxins) affect diverse membrane proteins, such as voltage- and ligand-gated ion channels, including nicotinic acetylcholine receptors (nachrs). family turridae has been considerably less studied than their conidae counterpart and, therefore, turrid toxins (tur ...202032592834
organizing the oocyte: rna localization meets phase separation.rna localization is a key biological strategy for organizing the cytoplasm and generating both cellular and developmental polarity. during rna localization, rnas are targeted asymmetrically to specific subcellular destinations, resulting in spatially and temporally restricted gene expression through local protein synthesis. first discovered in oocytes and embryos, rna localization is now recognized as a significant regulatory strategy for diverse rnas, both coding and non-coding, in a wide range ...202032591084
contribution of monocarboxylate transporter 6 to the pharmacokinetics and pharmacodynamics of bumetanide in mice.bumetanide, a sulfamyl loop diuretic, is used for the treatment of edema in association with congestive heart failure. being a polar, anionic compound at physiologic ph, bumetanide uptake and efflux into different tissues is largely transporter-mediated. of note, organic anion transporters (slc22a) have been extensively studied in terms of their importance in transporting bumetanide to its primary site of action in the kidney. the contribution of one of the less-studied bumetanide transporters, ...202032587098
functional analysis of the osnpf4.5 nitrate transporter reveals a conserved mycorrhizal pathway of nitrogen acquisition in plants.low availability of nitrogen (n) is often a major limiting factor to crop yield in most nutrient-poor soils. arbuscular mycorrhizal (am) fungi are beneficial symbionts of most land plants that enhance plant nutrient uptake, particularly of phosphate. a growing number of reports point to the substantially increased n accumulation in many mycorrhizal plants; however, the contribution of am symbiosis to plant n nutrition and the mechanisms underlying the am-mediated n acquisition are still in the e ...202032586957
acute toxicity of fluazinam to aquatic organisms and its bioaccumulation in brachydanio rerio.fluazinam (fzn) is a dinitroaniline fungicide. to evaluate the environmental risk of fzn in aquatic environments and ascertain the potential danger to typical aquatic organisms in china, the acute toxicity of fzn to representative aquatic organisms, including brachydanio rerio, chlorella vulgaris beij., daphnia magna straus, and xenopus laevis, was measured, and its bioaccumulation properties in brachydanio rerio were further investigated. the results showed that the acute toxicity of fzn to bra ...202032583109
electromechanical coupling of the kv1.1 voltage-gated k+ channel is fine-tuned by the simplest amino acid residue in the s4-s5 linker.investigating the shaker-related k+ channel kv1.1, the dysfunction of which is responsible for episodic ataxia 1 (ea1), at the functional and molecular level provides valuable understandings on normal channel dynamics, structural correlates underlying voltage-gating, and disease-causing mechanisms. most studies focused on apparently functional amino acid residues composing voltage-gated k+ channels, neglecting the simplest ones. glycine at position 311 of kv1.1 is highly conserved both evolution ...202032577860
polo-like kinase 1 (plk1) is a positive regulator of dna replication in the xenopus in vitro system.polo-like kinase 1 (plk1) is a cell cycle kinase essential for mitosis progression, but also important for checkpoint recovery and adaptation in response to dna damage and replication stress. however, although plk1 is expressed in s phase, little is known about its function during unperturbed dna replication. using xenopus laevis egg extracts, mimicking early embryonic replication, we demonstrate that plk1 is simultaneously recruited to chromatin with pre-replication proteins where it accumulate ...202032573322
molecular regulation of α3β4 nicotinic acetylcholine receptors by lupeol in cardiovascular system.cardiovascular disease (cvd) occurs globally and has a high mortality rate. the highest risk factor for developing cvd is high blood pressure. currently, natural products are emerging for the treatment of hypertension to avoid the side effects of drugs. among existing natural products, lupeol is known to be effective against hypertension in animal experiments. however, there exists no study regarding the molecular physiological evidence against the effects of lupeol. consequently, we investigate ...202032570692
three host plant volatiles, hexanal, lauric acid, and tetradecane, are detected by an antenna-biased expressed odorant receptor 27 in the dark black chafer holotrichia parallela.insects rely on olfaction to locate their host plants by antennae in complex chemical environments. odorant receptor (or) genes are thought to play a crucial role in the process. ors function together with odorant coreceptors to determine the specificity and sensitivity of olfactory reception. the dark black chafer, holotrichia parallela motschulsky (coleoptera: scarabaeidae), is a destructive underground pest. to understand the molecular basis of h. parallela olfactory reception, an olfactory-b ...202032551589
modulation by neonicotinoids of honeybee α1/chicken β2 hybrid nicotinic acetylcholine receptors expressed in xenopus laevis oocytes.neonicotinoids targeting insect nicotinic acetylcholine (ach) receptors (insect nachrs) are used for crop protection, but there is a concern about adverse effects on pollinators such as honeybees (apis mellifera). thus, we investigated the agonist actions of neonicotinoids (imidacloprid, thiacloprid and clothianidin) on a. mellifera α1 (amα1)/chicken β2 hybrid nachrs in xenopus laevis oocytes according to the subunit stoichiometry of (amα1)3(β2)2 and (amα1)2(β2)3 using voltage-clamp electrophysi ...202032448414
the mechanism of loop c-neonicotinoid interactions at insect nicotinic acetylcholine receptor α1 subunit predicts resistance emergence in pests.neonicotinoids selectively modulate insect nicotinic acetylcholine receptors (insect nachrs). studies have shown that serine with ability to form a hydrogen bond in loop c of some insect nachr α subunits and glutamate with a negative charge at the corresponding position in vertebrate nachrs may contribute to enhancing and reducing the neonicotinoid actions, respectively. however, there is no clear evidence what loop c properties underpin the target site actions of neonicotinoids. thus, we have i ...202032371996
surface contraction waves or cell proliferation waves in the presumptive neurectoderm during amphibian gastrulation: mexican axolotl versus african clawed frog.this essay represents a critical analysis of the literary data on various types of waves occurring in the amphibian embryos during gastrulation. a surface contraction wave travels through the presumptive neurectoderm during mexican axolotl gastrulation. this wave coincides temporally and spatially with involution of the inducing chordomesoderm and with the prospective neural plate. by contrast, there is no similar surface contraction wave during african clawed frog gastrulation. however, the cla ...202033181236
an aryl hydrocarbon receptor from the caecilian gymnopis multiplicata suggests low dioxin affinity in the ancestor of all three amphibian orders.the aryl hydrocarbon receptor (ahr) plays pleiotropic roles in the development and physiology of vertebrates in conjunction with xenobiotic and endogenous ligands. it is best known for mediating the toxic effects of dioxin-like pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd). while most vertebrates possess at least one ahr that binds tcdd tightly, amphibian ahrs bind tcdd with very low affinity. previous analyses of ahrs from xenopus laevis (a frog; order anura) and ambystoma mexic ...202032858041
von willebrand factor d and egf domains is an evolutionarily conserved and required feature of blastemas capable of multitissue appendage regeneration.regenerative ability varies tremendously across species. a common feature of regeneration of appendages such as limbs, fins, antlers, and tails is the formation of a blastema-a transient structure that houses a pool of progenitor cells that can regenerate the missing tissue. we have identified the expression of von willebrand factor d and egf domains (vwde) as a common feature of blastemas capable of regenerating limbs and fins in a variety of highly regenerative species, including axolotl (amby ...202032163674
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