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characterizing channelrhodopsin channel properties via two-electrode voltage clamp and kinetic modeling.two-electrode voltage clamp (tevc) is a preferred electrophysiological technique used to study gating kinetics and ion selectivity of light-activated channelrhodopsins (chrs). the method uses two intracellular microelectrodes to hold, or clamp, the membrane potential at a specific value and measure the flow of ions across the plasma membrane. here, we describe the use of tevc and a simple solution exchange protocol to measure cation selectivity and analyze gating kinetics of the c1c2 chimera exp ...202132865738
epigenetic control of myeloid cells behavior by histone deacetylase activity (hdac) during tissue and organ regeneration in xenopus laevis.in the present work we have focused on the histone deacetylase (hdac) control of myeloid cells behavior during xenopus tail regeneration. here we show that myeloid differentiation is crucial to modulate the regenerative ability of xenopus tadpoles in a hdac activity-dependent fashion. hdac activity inhibition during the first wave of myeloid differentiation disrupted myeloid cells dynamics in the regenerative bud as well the mrna expression pattern of myeloid markers, such as lurp, mpox, spib an ...202132858087
clearance of activity-evoked k+ transients and associated glia cell swelling occur independently of aqp4: a study with an isoform-selective aqp4 inhibitor.the mammalian brain consists of 80% water, which is continuously shifted between different compartments and cellular structures by mechanisms that are, to a large extent, unresolved. aquaporin 4 (aqp4) is abundantly expressed in glia and ependymal cells of the mammalian brain and has been proposed to act as a gatekeeper for brain water dynamics, predominantly based on studies utilizing aqp4-deficient mice. however, these mice have a range of secondary effects due to the gene deletion. an efficie ...202132506554
xenopus deep cell aggregates: a 3d tissue model for mesenchymal-to-epithelial transition.mesenchymal-to-epithelial transition (met) describes the ability of loosely associated migratory cells to form a more adherent sheet-like assembly of cells. met is a conserved motif occurring throughout organogenesis and plays a key role in regeneration and cancer metastasis, and is the first step in producing induced pluripotent stem cells (ipscs). to resolve fundamental biological questions about met, its relation to epithelial-to-mesenchymal transition, and to explore met's role in tissue ass ...202132939727
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
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
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
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
embryonic epidermal lectins in three amphibian species, rana ornativentris, bufo japonicus formosus, and cynops pyrrhogaster.intelectins (itlns) are secretory lectins found in several chordate species that recognize carbohydrates on the bacterial cell surface depending on ca2+ . in newly hatched larvae of rana ornativentris (r. orn), bufo japonicus formosus (b. jpn), and cynops pyrrhogaster (c. pyr), an anti-itln monoclonal antibody (mab) labeled a subset of epidermal cells in whole-mount immunocytochemical assays. in western blot analyses, the mab identified protein bands at approximately 33-37 kda in the larval extr ...202032729712
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
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
distinct m6a methylome profiles in poly(a) rna from xenopus laevis testis and that treated with atrazine.recent discovery of reversible n6-methyladenosine (m6a) methylation on messenger rna (mrna) and mapping of m6a methylomes in mammals, plant and yeast revealed potential regulatory functions of this rna modification. however, the role of the m6a methylomes in amphibious is still poorly understood. here, we examined the m6a transcriptome-wide profile in testis tissues of xenopus laevis (x. laevis) with and without treatment with 100 μg/l atrazine (az) through m6a sequencing analysis using the late ...202031877456
transformation of receptor tyrosine kinases into glutamate receptors and photoreceptors.receptor tyrosine kinases (rtks) are key regulators of cellular functions in metazoans. in vertebrates, rtks are mostly activated by polypeptides but are not naturally sensitive to amino acids or light. taking inspiration from venus kinase receptors (vkrs), an atypical family of rtks found in nature, we have transformed the human insulin (hir) and hepatocyte growth factor receptor (hmet) into glutamate receptors by replacing their extracellular binding domains with the ligand-binding domain of m ...202031872568
modeling ocular lens disease in xenopus.ocular lens clouding is termed as cataract, which depending on the onset, is classified as congenital or age-related. developing new cataract treatments requires new models. thus far, xenopus embryos have not been evaluated as a system for studying cataract.202031872467
bupropion inhibits serotonin type 3ab heteromeric channels at clinically relevant concentrations.bupropion, a food and drug administration-approved antidepressant and smoking cessation aid, blocks dopamine and norepinephrine reuptake transporters and noncompetitively inhibits nicotinic acetylcholine and serotonin (5-ht) type 3a receptors (5-ht3ars). 5-ht3 receptors are pentameric ligand-gated ion channels that regulate synaptic activity in the central and peripheral nervous system, presynaptically and postsynaptically. in the present study, we examined and compared the effect of bupropion a ...202031871303
the γ-hydroxybutyric acid (ghb) analogue ncs-382 is a substrate for both monocarboxylate transporters subtypes 1 and 4.the small-molecule ligand (e)-2-(5-hydroxy-5,7,8,9-tetrahydro-6h-benzo[7]annulen-6-ylidene)acetic acid (ncs-382) is an analogue of γ-hydroxybutyric acid (ghb) and is widely used for probing the brain-specific ghb high-affinity binding sites. to reach these, brain uptake is imperative, and it is therefore important to understand the molecular mechanisms of ncs-382 transport in order to direct in vivo studies. in this study, we hypothesized that ncs-382 is a substrate for the monocarboxylate trans ...202031866563
applying tensile and compressive force to xenopus animal cap tissue.over many years, the xenopus laevis embryo has provided a powerful model system to investigate how mechanical forces regulate cellular function. here, we describe a system to apply reproducible tensile and compressive force to x. laevis animal cap tissue explants and to simultaneously assess cellular behavior using live confocal imaging.202031857437
insights into the assembly and activation of the microtubule nucleator γ-turc.microtubules are dynamic polymers of α- and β-tubulin and have crucial roles in cell signalling, cell migration, intracellular transport and chromosome segregation1. they assemble de novo from αβ-tubulin dimers in an essential process termed microtubule nucleation. complexes that contain the protein γ-tubulin serve as structural templates for the microtubule nucleation reaction2. in vertebrates, microtubules are nucleated by the 2.2-megadalton γ-tubulin ring complex (γ-turc), which comprises γ-t ...202031856152
organ-specific requirements for thyroid hormone receptor ensure temporal coordination of tissue-specific transformations and completion of xenopus metamorphosis.background: thyroid hormone (triiodothyronine [t3]) is essential for the development throughout vertebrates. anuran metamorphosis mimics mammalian postembryonic development, a period around birth when plasma t3 level peaks and many organs/tissues mature into their adult forms. compared with the uterus-enclosed mammalian embryos, tadpoles can be easily manipulated to study the roles of t3 and t3 receptors (trs) in tissue remodeling and adult organ development. we and others have previously knocke ...202031854240
active emigration from climate change-caused seawater intrusion into freshwater habitats.ecological risk assessment associated with seawater intrusions has been supported on the determination of lethal/sublethal effects following standard protocols that force exposure neglecting the ability of mobile organisms to spatially avoid salinized environments. thus, this work aimed at assessing active emigration from climate change-caused seawater intrusion into freshwater habitats. to specific objectives were delineated: first, to compute median 12-h avoidance conductivities (ac50,12h) for ...202031883492
heparan sulfate proteoglycans regulate bmp signalling during neural crest induction.bone morphogenetic protein (bmp) signalling is key to many developmental processes, including early regionalisation of the ectoderm. the neural crest is induced here by a combination of bmp and wnt signals from nearby tissues with many secreted factors contributing to its initial specification at the neural plate border. gremlin 1 (grem1) is a secreted bmp antagonist expressed in the neural crest in xenopus laevis but its function here is unknown. as well as binding bmps, grem1 has been shown to ...202031883440
endoplasmic reticulum transmembrane protein tmtc3 contributes to o-mannosylation of e-cadherin, cellular adherence, and embryonic gastrulation.protein glycosylation plays essential roles in protein structure, stability, and activity such as cell adhesion. the cadherin superfamily of adhesion molecules carry o-linked mannose glycans at conserved sites and it was recently demonstrated that the transmembrane and tetratricopeptide repeat-containing proteins 1-4 (tmtc1-4) gene products contribute to the addition of these o-linked mannoses. here, biochemical, cell biological, and organismal analysis was used to determine that tmtc3 supports ...202031851597
desensitization of nmda channels requires ligand binding to both glun1 and glun2 subunits to constrict the pore beside the activation gate.n-methyl-d-aspartate (nmda) receptor channels are activated by glutamate (or nmda) and glycine. the channels also undergo desensitization, which denotes decreased channel availability, after prolonged exposure to the activating ligands. glycine apparently has a paradoxical negative effect on desensitization, as the increase in ambient glycine in concentrations required for channel activation would increase sustained nmda receptor currents. we hypothesized that this classical "glycine-dependent d ...202031821563
d-glucuronolactone attenuates para-xylene-induced defects in neuronal development and plasticity in xenopus tectum in vivo.xylene and its derivatives are known to be neurotoxic to the central nervous system of animals. our previous work has shown that para-xylene (px) can cause an increase in apoptotic cells and abnormal avoidance behavior in xenopus laevis. however, the mechanism underlying the impact of px on neuronal structural and functional plasticity is less clear. here, we examined the effects of px on neuronal development and plasticity in the developing optic tectum. we found that huc/d-positive neurons wer ...202031811891
analysis of clcnkb mutations at dimer-interface, calcium-binding site, and pore reveals a variety of functional alterations in clc-kb channel leading to bartter syndrome.pathological missense mutations in clcnkb gene give a wide spectrum of clinical phenotypes in bartter syndrome type iii patients. molecular analysis of the mutated clc-kb channels can be helpful to classify the mutations according to their functional alteration. we investigated the functional consequences of nine mutations in the clcnkb gene causing bartter syndrome. we first established that all tested mutations lead to decreased clc-kb currents. combining electrophysiological and biochemical m ...202031803959
role of trka signaling during tadpole tail regeneration and early embryonic development in xenopus laevis.neurotrophic signaling regulates neural cell behaviors in development and physiology, although its role in regeneration has not been fully investigated. here, we examined the role of neurotrophic signaling in xenopus laevis tadpole tail regeneration. after the tadpole tails were amputated, the expression of neurotrophin ligand family genes, especially ngf and bdnf, was up-regulated as regeneration proceeded. moreover, notochordal expression of the ngf receptor gene trka, but not that of other ne ...202031788928
studying in vivo retinal progenitor cell proliferation in xenopus laevis.the efficient generation and maintenance of retinal progenitor cells (rpcs) are key goals needed for developing strategies for productive eye repair. although vertebrate eye development and retinogenesis are well characterized, the mechanisms that can initiate rpc proliferation following injury-induced regrowth and repair remain unknown. this is partly because endogenous rpc proliferation typically occurs during embryogenesis while studies of retinal regeneration have largely utilized adult (or ...202031786778
molecular characterization of the orphan transporter slc16a9, an extracellular ph- and na+-sensitive creatine transporter.human monocarboxylate transporters (hmcts) mediate the transport of monocarboxylates across plasma membranes. one such transporter, hmct9, has been shown to be related to serum uric acid levels and the risk of renal overload gout. however, the functional characteristics of hmct9 remain unknown. the aim of this study was to investigate the expression and localization of hmct9 using a xenopus laevis oocyte heterologous expression system and characterize its transport properties. kinetic analysis o ...202031784090
a glimpse of the peptide profile presentation by xenopus laevis mhc class i: crystal structure of pxela-uaa reveals a distinct peptide-binding groove.the african clawed frog, xenopus laevis, is a model species for amphibians. before metamorphosis, tadpoles do not efficiently express the single classical mhc class i (mhc-i) molecule xela-uaa, but after metamorphosis, adults express this molecule in abundance. to elucidate the ag-presenting mechanism of xela-uaa, in this study, the xela-uaa structure complex (pxela-uaag) bound with a peptide from a synthetic random peptide library was determined. the amino acid homology between the xela-uaa and ...202031776204
apple almt9 requires a conserved c-terminal domain for malate transport underlying fruit acidity.malate accumulation in the vacuole largely determines apple (malus domestica) fruit acidity, and low fruit acidity is strongly associated with truncation of ma1, an ortholog of aluminum-activated malate transporter9 (almt9) in arabidopsis (arabidopsis thaliana). a mutation at base 1,455 in the open reading frame of ma1 leads to a premature stop codon that truncates the protein by 84 amino acids at its c-terminal end. here, we report that both the full-length protein, ma1, and its naturally occur ...202031772076
effect of triadimefon and its metabolite on adult amphibians xenopus laevis.the decrease in the population of amphibians all over the world has raised concerns. adult x. laevis frogs were exposed to 0, 1 and 10 mg/l triadimefon and triadimenol. after 14 or 28 days exposure, we collected male and female specimens to study swimming activity, lactic dehydrogenase (ldh) and antioxidant enzyme activity in blood samples, histopathology of liver and thyroid tissue, thyroid hormone levels and thyroid hormone-related gene expression levels in brains. our results showed that tria ...202031743868
tomato roots have a functional silicon influx transporter but not a functional silicon efflux transporter.silicon (si) accumulation in shoots differs greatly with plant species, but the molecular mechanisms for this interspecific difference are unknown. here, we isolated homologous genes of rice si influx (sllsi1) and efflux (sllsi2) transporter genes in tomato (solanum lycopersicum l.) and functionally characterized these genes. sllsi1 showed transport activity for si when expressed in both rice lsi1 mutant and xenopus laevis oocytes. sllsi1 was constitutively expressed in the roots. immunostaining ...202031724184
the flavor enhancer maltol increases pigment aggregation in dermal and neural melanophores in xenopus laevis tadpoles.melanophores are pigmented cells that change the distribution of melanosomes, enabling animals to appear lighter or darker for camouflage, thermoregulation, and protection from ultraviolet radiation. a complex series of hormonal and neural mechanisms regulates melanophore pigment distribution, making these dynamic cells a valuable tool to screen toxicants as they rapidly respond to changes in the environment. we found that maltol, a naturally occurring flavor enhancer and fragrance agent, induce ...202031721268
iron nanoparticle bio-interactions evaluated in xenopus laevis embryos, a model for studying the safety of ingested nanoparticles.iron nanoparticles (nps) have been proposed as a tool in very different fields such as environmental remediation and biomedical applications, including food fortification against iron deficiency, even if there is still concern about their safety. here, we propose xenopus laevis embryos as a suitable model to investigate the toxicity and the bio-interactions at the intestinal barrier of fe3o4 and zerovalent iron (zvi) nps compared to fe(ii) and (iii) salts in the 5 to 100 mg fe/l concentration ra ...202031718350
toward decoding bioelectric events in xenopus embryogenesis: new methodology for tracking interplay between calcium and resting potentials in vivo.although chemical signaling during embryogenesis is readily addressed by a plethora of available techniques, the developmental functions of ionic signaling are still poorly understood. it is increasingly realized that bioelectric events in nonneural cells are critical for pattern regulation, but their study has been hampered by difficulties in monitoring and manipulating them in vivo. recent developments in visualizing electrical signaling dynamics in the field of neuroscience have facilitated f ...202031711960
arabidopsis pic30 encodes a major facilitator superfamily transporter responsible for the uptake of picolinate herbicides.picloram is an auxinic herbicide that is widely used for controlling broad leaf weeds. however, its mechanism of transport into plants is poorly understood. in a genetic screen for picloram resistance, we identified three arabidopsis mutant alleles of pic30 (picloram resistant30) that are specifically resistant to picolinates, but not to other auxins. pic30 is a previously uncharacterized gene that encodes a major facilitator superfamily (mfs) transporter. similar to most members of mfs, pic30 c ...202031710151
serotonin and mucxs release by small secretory cells depend on xpod, a ssc specific marker gene.mucus secretion and ciliary motility are hallmarks for muco-ciliary epithelia (mce). both, mammalian airways as well as the less complex epidermis of xenopus embryos show cilia-driven mucus flow to protect the organism against harmful effects by exogenous pathogens or pollutants. four cell types set up the epidermal mce in xenopus. multi-ciliated cells (mccs) generate an anterior to posterior flow of mucus. ion secreting cells (iscs) are characterized by the expression of ion transporters, presu ...202031705622
the transcription factor hypermethylated in cancer 1 (hic1) regulates neural crest migration via interaction with wnt signaling.the transcription factor hypermethylated in cancer 1 (hic1) is associated with both tumorigenesis and the complex human developmental disorder miller-dieker syndrome. while many studies have characterized hic1 as a tumor suppressor, hic1 function in development is less understood. loss-of-function mouse alleles show embryonic lethality accompanied with developmental defects, including craniofacial abnormalities that are reminiscent of human miller-dieker syndrome patients. however, the tissue or ...202032502469
dehydration stress alters the mitogen-activated-protein kinase signaling and chaperone stress response in xenopus laevis.in arid conditions, the african clawed frog xenopus laevis enters a state of estivation dormancy as an adaptive survival strategy. under estivation, x. laevis experience severe dehydration stress as 25-35% of total body water is lost. dehydration in x. laevis can lead to periods of hypoxia due to elevated blood viscosity that impedes tissue perfusion. to understand how x. laevis survives under such stress, we studied the regulation pattern of key mitogen-activated protein kinases (mapk) and thei ...202032497588
altered thyroid hormone levels affect the capacity for temperature-induced developmental plasticity in larvae of rana temporaria and xenopus laevis.anuran larvae show phenotypic plasticity in age and size at metamorphosis as a response to temperature variation. the capacity for temperature-induced developmental plasticity is determined by the thermal adaptation of a population. multiple factors such as physiological responses to changing environmental conditions, however, might influence this capacity as well. in anuran larvae, thyroid hormone (th) levels control growth and developmental rate and changes in th status are a well-known stress ...202032479394
the perinuclear er scales nuclear size independently of cell size in early embryos.nuclear size plays pivotal roles in gene expression, embryo development, and disease. a central hypothesis in organisms ranging from yeast to vertebrates is that nuclear size scales to cell size. this implies that nuclei may reach steady-state sizes set by limiting cytoplasmic pools of size-regulating components. by monitoring nuclear dynamics in early sea urchin embryos, we found that nuclei undergo substantial growth in each interphase, reaching a maximal size prior to mitosis that declined st ...202032473090
association of a novel splice site mutation in p/q-type calcium channels with childhood epilepsy and late-onset slowly progressive non-episodic cerebellar ataxia.episodic ataxia type 2 (ea2) is characterized by paroxysmal attacks of ataxia with typical onset in childhood or early adolescence. the disease is associated with mutations in the voltage-gated calcium channel alpha 1a subunit (cav2.1) that is encoded by the cacna1a gene. however, previously unrecognized atypical symptoms and the genetic overlap existing between ea2, spinocerebellar ataxia type 6, familial hemiplegic migraine type 1, and other neurological diseases blur the genotype/phenotype co ...202032471306
cloning and expression of cockroach α7 nicotinic acetylcholine receptor subunit.understanding insect nicotinic acetylcholine receptor (nachr) subtypes is of major interest because they are the main target of several insecticides. in this study, we have cloned a cockroach pameα7 subunit that encodes a 518 amino acid protein with futures typical of nachr subunit, and sequence homology to α7 subunit. pameα7 is differently expressed in the cockroach nervous system, in particular in the antennal lobes, optical lobes and the mushroom bodies where specific expression was found in ...202032457646
experimental platform using the amphibian xenopus laevis for research in fundamental and medical immunology.the amphibian xenopus constitutes a powerful, versatile, and cost-effective nonmammalian model with which to investigate important contemporary issues of immunity relevant to human health such as ontogeny of immunity, self-tolerance, wound healing, autoimmunity, cancer immunity, immunotoxicology, and adaptation of host immune defenses to emerging pathogens. this model system presents several attractive features: an external developmental environment free of maternal influence that allows for eas ...202032457040
nuclei determine the spatial origin of mitotic waves.traveling waves play an essential role in coordinating mitosis over large distances, but what determines the spatial origin of mitotic waves remains unclear. here, we show that such waves initiate at pacemakers, regions that oscillate faster than their surroundings. in cell-free extracts of xenopus laevis eggs, we find that nuclei define such pacemakers by concentrating cell cycle regulators. in computational models of diffusively coupled oscillators that account for nuclear import, nuclear posi ...202032452767
the regulation of akt and foxo transcription factors during dehydration in the african clawed frog (xenopus laevis).the african clawed frog (xenopus laevis) naturally tolerates severe dehydration using biochemical adaptation, one of which is the elevation of antioxidant defenses during whole-body dehydration. the present study investigated the role and regulation of a pathway known to regulate oxidative stress response, the akt-foxo signaling pathway, in clawed frog skeletal muscle, responding to medium (15%) and high (30%) dehydration. protein levels of total and phosphorylated akt, foxo1, and foxo3 were ass ...202032451989
microvascular anatomy of ovary and oviduct in the adult african clawed toad (xenopus laevis daudin, 1802)-histomorphology and scanning electron microscopy of vascular corrosion casts.ovaries and oviducts of the adult african clawed toad (xenopus laevis daudin, 1802) were studied by light microscopy (lm) of paraplast embedded tissue sections and scanning electron microscopy (sem) of vascular corrosion casts (vccs). histomorphology revealed that ovarian vessels located in the thecal layers. ovarian and interlobar arteries displayed a horse-shoe shaped longitudinally running bundle of vascular smooth muscle cells. follicular blood vessels showed flattened profiles, which were c ...202032449214
optical control of muscular nicotinic channels with azocuroniums, photoswitchable azobenzenes bearing two n-methyl-n-carbocyclic quaternary ammonium groups.by linking two n-methyl-n-carbocyclic quaternary ammonium groups to an azobenzene scaffold in meta- or para-positions we generated a series of photoswitchable neuromuscular ligands for which we coined the term "azocuroniums". these compounds switched between the (e)- and (z)-isomers by light irradiation at 400-450 nm and 335-340 nm, respectively. meta-azocuroniums were potent nicotinic ligands with a clear selectivity for the muscular nachrs compared to neuronal α7 and α4β2 subtypes, showed good ...202032447198
cross-taxa distinctions in mechanisms of developmental effects for aquatic species exposed to trifluralin.standard ecological risk assessment practices often rely on larval and juvenile fish toxicity data as representative of the amphibian aquatic phase. empirical evidence suggests that endpoints measured in fish early life stage tests are often sufficient to protect larval amphibians. however, the process of amphibian metamorphosis relies on endocrine cues that affect development and morphological restructuring and are not represented by these test endpoints. the present study compares developmenta ...202032445211
identification of transient receptor potential channel 4-associated protein as a novel candidate gene causing congenital primary hypothyroidism.congenital primary hypothyroidism (ch) is the most common endocrine disorder in neonates.202032428920
de novo mutations in fbrsl1 cause a novel recognizable malformation and intellectual disability syndrome.we report truncating de novo variants in specific exons of fbrsl1 in three unrelated children with an overlapping syndromic phenotype with respiratory insufficiency, postnatal growth restriction, microcephaly, global developmental delay and other malformations. the function of fbrsl1 is largely unknown. interestingly, mutations in the fbrsl1 paralogue auts2 lead to an intellectual disability syndrome (auts2 syndrome). we determined human fbrsl1 transcripts and describe protein-coding forms by we ...202032424618
imaging nascent transcription in wholemount vertebrate embryos to characterize zygotic genome activation.a major event in early embryo development is the awakening of the embryonic genome, a process of large-scale transcriptional induction termed zygotic genome activation (zga). to understand how zga is controlled temporally and spatially, tools are required to image and quantify nascent transcription in wholemount embryos. in this chapter, we describe a metabolic labeling approach that leverages 5-ethynyl uridine (5-eu) incorporation into newly transcribed rnas. subsequently, click chemistry is us ...202032416911
supportive role of the na+ transporter cmhkt1;1 from cucumis melo in transgenic arabidopsis salt tolerance through improved k+/na+ balance.cmhkt1;1 selectively exports na+ from plant cells. upon nacl stress, its expression increased in a salt-tolerant melon cultivar. overexpression of cmhkt1;1 increased transgenic arabidopsis salt tolerance through improved k+/na+ balance. high-affinity k+ transporters (hkts) are thought to be involved in reducing na+ in plant shoots under salt stress and modulating salt tolerance, but their function in a moderately salt-tolerant species of melon (cucumis melo l.) remains unclear. in this study, a ...202032405802
animal maintenance systems: xenopus laevis.modular recirculating animal aquaculture systems incorporate uv sterilization and biological, mechanical, and activated carbon filtration, creating a nearly self-contained stable housing environment for xenopus laevis nonetheless, minimal water exchange is necessary to mitigate accumulation of metabolic waste, and regular weekly, monthly, and yearly maintenance is needed to ensure accurate and efficient operation. this protocol describes the methods for establishing a new recirculating system an ...202032404311
altered functional properties of a missense variant in the tresk k+ channel (kcnk18) associated with migraine and intellectual disability.mutations in the kcnk18 gene that encodes the tresk k2p potassium channel have previously been linked with typical familial migraine with aura. recently, an atypical clinical case has been reported in which a male individual carrying the p.trp101arg (w101r) missense mutation in the kcnk18 gene was diagnosed with intellectual disability and migraine with brainstem aura. here we report the functional characterization of this new missense variant. this mutation is located in a highly conserved resi ...202032394190
managing the oocyte meiotic arrest-lessons from frogs and jellyfish.during oocyte development, meiosis arrests in prophase of the first division for a remarkably prolonged period firstly during oocyte growth, and then when awaiting the appropriate hormonal signals for egg release. this prophase arrest is finally unlocked when locally produced maturation initiation hormones (mihs) trigger entry into m-phase. here, we assess the current knowledge of the successive cellular and molecular mechanisms responsible for keeping meiotic progression on hold. we focus on tw ...202032392797
differences in intrinsic tubulin dynamic properties contribute to spindle length control in xenopus species.the function of cellular organelles relates not only to their molecular composition but also to their size. however, how the size of dynamic mesoscale structures is established and maintained remains poorly understood [1-3]. mitotic spindle length, for example, varies several-fold among cell types and among different organisms [4]. although most studies on spindle size control focus on changes in proteins that regulate microtubule dynamics [5-8], the contribution of the spindle's main building b ...202032386526
structure of the cytoplasmic ring of the xenopus laevis nuclear pore complex by cryo-electron microscopy single particle analysis.the nuclear pore complex (npc) exhibits structural plasticity and has only been characterized at local resolutions of up to 15 å for the cytoplasmic ring (cr). here we present a single-particle cryo-electron microscopy (cryo-em) structure of the cr from xenopus laevis npc at average resolutions of 5.5-7.9 å, with local resolutions reaching 4.5 å. improved resolutions allow identification and placement of secondary structural elements in the majority of the cr components. the two y complexes in e ...202032376910
rpe cells engulf microvesicles secreted by degenerating rod photoreceptors.rhodopsin is mislocalized to the inner segment plasma membrane (is pm) in various blinding disorders including autosomal-dominant retinitis pigmentosa caused by class i rhodopsin mutations. in these disorders, rhodopsin-laden microvesicles are secreted into the extracellular milieu by afflicted photoreceptor cells. using a xenopus laevis model expressing class i mutant rhodopsin or na+/k+-atpase (nka) fused to dendra2, we fluorescently labeled the microvesicles and found retinal pigment epitheli ...202032376599
renal microvasculature in the adult pipid frog, xenopus laevis: a scanning electron microscope study of vascular corrosion casts.we studied the opisthonephric (mesonephric) kidneys of adult male and female xenopus laevis using scanning electron microscopy (sem) of vascular corrosion casts and light microscopy of paraplast embedded tissue sections. both techniques displayed glomeruli from ventral to mid-dorsal regions of the kidneys with single glomeruli located dorsally close beneath the renal capsule. glomeruli in general were fed by a single afferent arteriole and drained via a single thinner efferent arteriole into per ...202032374496
molecular characterization of frog vocal neurons using constellation pharmacology.identification and characterization of neuronal cell classes in motor circuits are essential for understanding the neural basis of behavior. it is a challenging task, especially in a non-genetic-model organism, to identify cell-specific expression of functional macromolecules. here, we performed constellation pharmacology, calcium imaging of dissociated neurons to pharmacologically identify functional receptors expressed by vocal neurons in adult male and female african clawed frogs, xenopus lae ...202032374212
the gria3 c.2477g > a variant causes an exaggerated startle reflex, chorea, and multifocal myoclonus.hemizygous mutations in gria3 encoding the glua3 subunit of the amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor are known to be associated with neurodevelopmental disorders, including intellectual disability, hypotonia, an autism spectrum disorder, sleep disturbances, and epilepsy in males.202032369665
molecular architecture of the luminal ring of the xenopus laevis nuclear pore complex.the nuclear pore complex (npc) mediates the flow of substances between the nucleus and cytoplasm in eukaryotic cells. here we report the cryo-electron tomography (cryo-et) structure of the luminal ring (lr) of the npc from xenopus laevis oocyte. the observed key structural features of the lr are independently confirmed by single-particle cryo-electron microscopy (cryo-em) analysis. the lr comprises eight butterfly-shaped subunits, each containing two symmetric wings. each wing consists of four e ...202032367042
stentian structural plasticity in the developing visual system.in a small fraction of xenopus tadpoles, a single retinal ganglion cell (rgc) axon misprojects to the ipsilateral optic tectum. presenting flashes of light to the ipsilateral eye causes that ipsilateral axon to fire, whereas stimulating the contralateral eye excites all other rgc inputs to the tectum. we performed time-lapse imaging of individual ipsilaterally projecting axons while stimulating either the ipsilateral or contralateral eye. stimulating either eye alone reduced axon elaboration by ...202032366647
combining endocannabinoids with retigabine for enhanced m-channel effect and improved kv7 subtype selectivity.retigabine is unique among anticonvulsant drugs by targeting the neuronal m-channel, which is composed of kv7.2/kv7.3 and contributes to the negative neuronal resting membrane potential. unfortunately, retigabine causes adverse effects, which limits its clinical use. adverse effects may be reduced by developing m-channel activators with improved kv7 subtype selectivity. the aim of this study was to evaluate the prospect of endocannabinoids as m-channel activators, either in isolation or combined ...202032365171
functional characterization of multifunctional ligands targeting acetylcholinesterase and alpha 7 nicotinic acetylcholine receptor.alzheimer's disease (ad) is a neurodegenerative disorder associated with cholinergic dysfunction, provoking memory loss and cognitive dysfunction in elderly patients. the cholinergic hypothesis provided over the years with molecular targets for developing palliative treatments for ad, acting on the cholinergic system, namely, acetylcholinesterase and α7 nicotinic acetylcholine receptor (α7 nachr). in our synthetic work, we used "click-chemistry" to synthesize two multi target directed ligands (m ...202032360492
inhibition of cardiac kv4.3 (ito) channel isoforms by class i antiarrhythmic drugs lidocaine and mexiletine.transient outward k+ current, ito, contributes to cardiac action potential generation and is primarily carried by kv4.3 (kcnd3) channels. two kv4.3 isoforms are expressed in human ventricle and show differential remodeling in heart failure (hf). lidocaine and mexiletine may be applied in selected patients to suppress ventricular arrhythmias, without effects on sudden cardiac death or mortality. isoform-dependent effects of antiarrhythmic drugs on kv4.3 channels and potential implications for rem ...202032360350
effects of ferrocenyl 4-(imino)-1,4-dihydro-quinolines on xenopus laevis prophase i - arrested oocytes: survival and hormonal-induced m-phase entry.xenopus oocytes were used as cellular and molecular sentinels to assess the effects of a new class of organometallic compounds called ferrocenyl dihydroquinolines that have been developed as potential anti-cancer agents. one ferrocenyl dihydroquinoline compound exerted deleterious effects on oocyte survival after 48 h of incubation at 100 μm. two ferrocenyl dihydroquinoline compounds had an inhibitory effect on the resumption of progesterone induced oocyte meiosis, compared to controls without f ...202032357477
structure of a single-chain h2a/h2b dimer.chromatin is the complex assembly of nucleic acids and proteins that makes up the physiological form of the eukaryotic genome. the nucleosome is the fundamental repeating unit of chromatin, and is composed of ∼147 bp of dna wrapped around a histone octamer formed by two copies of each core histone: h2a, h2b, h3 and h4. prior to nucleosome assembly, and during histone eviction, histones are typically assembled into soluble h2a/h2b dimers and h3/h4 dimers and tetramers. a multitude of factors inte ...202032356520
how to grow xenopus laevis tadpole stages to adult.in xenopus laevis, the tadpole stage is characterized by three forms-those occurring before the initiation of limb development, those covering limb development, and those encompassing metamorphosis. maximal tadpole growth, especially during the second form, is critically dependent on good husbandry practices. here we describe a protocol for raising xenopus laevis tadpoles through to adulthood. each step may need to be modified depending on the aquaria used and local conditions.202032350123
effect of nano-encapsulation of β-carotene on xenopus laevis embryos development (fetax).vitamin a plays a vital role during embryo development as most precursor of embryonic retinoic acid, a key morphogen during embryogenesis. carotenoids, including β-carotene, are important vegetal source of vitamin a and in contrast to teratogenic potential of animal-derived retinoids, β-carotene is usually considered freed from embryotoxic effects and supplements in pregnancy with β-carotene are suggested. the aim of the present work is to evaluate the effect of bulk and nano-encapsulated β-caro ...202032346517
concentration-dependent physiological and transcriptional adaptations of wheat seedlings to ammonium.conventional wheat production utilizes fertilizers of various nitrogen forms. sole ammonium nutrition has been shown to improve grain quality, despite the potential toxic effects of ammonium at elevated concentrations. we therefore investigated the responses of young seedlings of winter wheat to different nitrogen sources (nh4 no3 = nn, nh4 cl = nnh4+ and kno3 = nno3- ). growth with ammonium-nitrate was superior. however, an elevated concentration of sole ammonium caused severe toxicity symptoms ...202032335941
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