Publications

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effects of trimethoprim-sulfadiazine and detomidine on the function of equine kv 11.1 channels in a two-electrode voltage-clamp (tevc) oocyte model.the long qt syndrome (lqts) is a channelopathy that can lead to severe arrhythmia and sudden cardiac death. pharmacologically induced lqts is caused by interaction between drugs and potassium channels, especially the kv 11.1 channel. due to such interactions, numerous drugs have been withdrawn from the market or are administered with precautions in human medicine. however, some compounds, such as trimethoprim-sulfonamide combinations are still widely used in veterinarian medicine. therefore, we ...201829566261
ribosomal rna biogenesis and its response to chilling stress in oryza sativa.ribosome biogenesis is crucial for plant growth and environmental acclimation. processing of ribosomal rnas (rrnas) is an essential step in ribosome biogenesis and begins with transcription of the rdna. the resulting precursor-rrna (pre-rrna) transcript undergoes systematic processing, where multiple endonucleolytic and exonucleolytic cleavages remove the external and internal transcribed spacers (ets and its). the processing sites and pathways for pre-rrna processing have been deciphered in sac ...201829555785
comparison of etomidate, benzocaine, and ms222 anesthesia with and without subsequent flunixin meglumine analgesia in african clawed frogs (xenopus laevis).often few alternative anesthetics for exotic species are available, due to the small numbers of these animals used in research. in this study, we evaluated the depth and duration of anesthesia in xenopus laevis after their immersion in 3 doses of etomidate (15, 22.5, and 30 mg/l) and in 3 doses of benzocaine (0.1%, 0.5%, and 1%) compared with the 'gold standard,' tricaine methanesulfonate (ms222; 2 g/l). we then chose an optimal dose for each alternative anesthetic according to induction time, d ...201829555009
differential patterns of inhibition of the sugar transporters glut2, glut5 and glut7 by flavonoids.only limited data are available on the inhibition of the sugar transporter glut5 by flavonoids or other classes of bioactives. intestinal glut7 is poorly characterised and no information exists concerning its inhibition. we aimed to study the expression of glut7 in caco-2/tc7 intestinal cells, and evaluate inhibition of glucose transport by glut2 and glut7, and of fructose transport by glut2, glut5 and glut7, by flavonoids. differentiated caco-2/tc7 cell monolayers were used to investigate glut7 ...201829548810
satb1 downregulation induced by oxidative stress participates in trophoblast invasion by regulating β-catenin.preeclampsia (pe) is characterized by abnormal placentation in the early stages of pregnancy. adequate migration and invasion of trophoblasts into the uterine wall and spiral arteries to form a functional maternal-fetal interface are pivotal for normal placentation, but the exact mechanism remains unclear. growing evidence has revealed that special at-rich sequence binding protein 1 (binds to nuclear matrix/scaffold-associating dna) (satb1) is a tumor promoter that participates in cancer cell mi ...201829546272
effects of transportation, transport medium and re-housing on xenopus laevis (daudin).understanding the immediate and longer-term effects of transportation and re-housing in a laboratory species is crucial in order to refine the transfer process, enable the optimal introduction of new animals to a novel environment and to provide a sufficient acclimatisation period before usage. whilst consideration of animal welfare in most model vertebrate species has received attention, little quantitative evidence exists for the optimal care of the common laboratory amphibian xenopus laevis. ...201829545087
large, long range tensile forces drive convergence during xenopus blastopore closure and body axis elongation.indirect evidence suggests that blastopore closure during gastrulation of anamniotes, including amphibians such as xenopus laevis, depends on circumblastoporal convergence forces generated by the marginal zone (mz), but direct evidence is lacking. we show that explanted mzs generate tensile convergence forces up to 1.5 μn during gastrulation and over 4 μn thereafter. these forces are generated by convergent thickening (ct) until the midgastrula and increasingly by convergent extension (ce) there ...201829533180
lithobates catesbeianus (american bullfrog) oocytes: a novel heterologous expression system for aquaporins.xenopus laevis oocytes are a valuable tool for investigating the function of membrane proteins. however, regulations around the world, specifically in brazil, render the import of xenopus laevis frogs impractical, and, in some cases, impossible. here, as an alternative, we evaluate the usefulness of the north american aquatic bullfrog lithobates catesebeianus, which is commercially available in brazil, for the heterologous expression of aquaporin (aqp) proteins. we have developed a method that c ...201829530931
pitx1 regulates cement gland development in xenopus laevis through activation of transcriptional targets and inhibition of bmp signaling.the cement gland in xenopus laevis has long been used as a model to study the interplay of cell signaling and transcription factors during embryogenesis. it has been shown that an intermediate level of bone morphogenetic protein (bmp) signaling is essential for cement gland formation. in addition, several transcription factors have been linked to cement gland development. one of these, the homeodomain-containing protein pitx1, can generate ectopic cement gland formation; however, the mechanisms ...201829530451
frog's dcs have it all in one.although the amphibian xenopus laevis produces antibodies as diversified as those from mammals in the primary repertoire, antibody affinity maturation after immunization is relatively poor and has been associated with a poor b cell selection of aid-mediated hypermutations and lack of germinal centers in the spleen, the only secondary lymphoid organ of this amphibian. in this issue of the european journal of immunology, neely et al., [eur. j. immunol. 2018. 48: 430-440] have unveiled the role of ...201829522243
transcriptome analysis identifies genes involved in sex determination and development of xenopus laevis gonads.development of the gonads is a complex process, which starts with a period of undifferentiated, bipotential gonads. during this period the expression of sex-determining genes is initiated. sex determination is a process triggering differentiation of the gonads into the testis or ovary. sex determination period is followed by sexual differentiation, i.e. appearance of the first testis- and ovary-specific features. in xenopus laevis w-linked dm-domain gene (dm-w) had been described as a master det ...201829518581
c8orf46 homolog encodes a novel protein vexin that is required for neurogenesis in xenopus laevis.neural basic helix-loop helix (bhlh) transcription factors promote progenitor cell differentiation by activation of downstream target genes that coordinate neuronal differentiation. here we characterize a neural bhlh target gene in xenopus laevis, vexin (vxn; previously sbt1), that is homologous to human c8orf46 and is conserved across vertebrate species. c8orf46 has been implicated in cancer progression, but its function is unknown. vxn is transiently expressed in differentiating progenitors in ...201829518376
investigation of higher-order rna g-quadruplex structures in vitro and in living cells by 19f nmr spectroscopy.growing evidence indicates that rna g-quadruplexes have important roles in various processes such as transcription, translation, regulation of telomere length, and formation of telomeric heterochromatin. investigation of rna g-quadruplex structures associated with biological events is therefore essential to understanding the functions of these rna molecules. we recently demonstrated that the sensitivity and simplicity of 19f nmr can be used to directly observe higher-order telomeric g-quadruplex ...201829517770
occurrence of batrachochytrium dendrobatidis in anurans of the mediterranean region of baja california, méxico.chytridiomycosis is caused by the fungal pathogen batrachochytrium dendrobatidis (bd) and is regarded as one of the most significant threats to global amphibian populations. in méxico, bd was first reported in 2003 and has now been documented in 13 states. we visited 33 localities and swabbed 199 wild-caught anurans from 7 species (5 native, 2 exotic) across the mediterranean region of the state of baja california. using quantitative pcr, bd was detected in 94 individuals (47.2% of samples) at 2 ...201829516858
evaluation of the toxic effects of celecoxib on xenopus embryo development.celecoxib is a non-steroidal anti-inflammatory drug that selectively inhibits cyclooxygenase-2 and is prescribed for severe pain and inflammation. the excellent therapeutic effects of celecoxib mean that it is frequently used clinically, including for women of child-bearing age. however, the prenatal effects of this compound have not been studied extensively in vertebrates. the present study examined the developmental toxicity of celecoxib using a frog embryo teratogenic assay-xenopus (fetax). i ...201829505793
booting up the organism during development: pre-behavioral functions of the vertebrate brain in guiding body morphogenesis.a recent study in xenopus laevis embryos showed that the very early brain has important functions long before behavior. while the nascent brain is being constructed, it is required for normal patterning of the muscle and peripheral nerve networks, including those far away from the head. in addition to providing important developmental signals to remote tissues in normal embryogenesis, its presence is also able to render harmless exposure to specific chemicals that normally act as teratogens. the ...201829497473
whole-mount in situ hybridization of xenopus oocytes.whole-mount in situ hybridization (wmish) is a common approach that is used to visualize spatial and temporal gene expression in embryos. in this process, digoxygenin-labeled antisense rna is hybridized to the complementary transcript of interest and rna hybrids are immunohistochemically detected using an alkaline phosphatase-conjugated antibody against digoxigenin. during xenopus laevis oogenesis, certain rnas localize to the animal or vegetal pole laying the foundation for germ cell developmen ...201829496817
identification of circular rnas and their alterations involved in developing male xenopus laevis chronically exposed to atrazine.atrazine (az) is an environmental endocrine disrupting chemical which can affect the development of amphibians. in our past studies, we demonstrated that chronical exposure to 100 μg/l az can cause abnormalities in development and related genes expression of gonads in developing male xenopus laevis (x. laevis) tadpoles. recent studies by others have demonstrated that circular rnas (circrnas) are implicated in multiple developmental anomalies. however, whether circrnas involve in the effects in a ...201829494910
a nurd complex from xenopus laevis eggs is essential for dna replication during early embryogenesis.dna replication in the embryo of xenopus laevis changes dramatically at the mid-blastula transition (mbt), with y rna-independent random initiation switching to y rna-dependent initiation at specific origins. here, we identify xnurd, an mta2-containing assemblage of the nucleosome remodeling and histone deacetylation complex nurd, as an essential factor in pre-mbt xenopus embryos that overcomes a functional requirement for y rnas during dna replication. human nurd complexes have a different subu ...201829490265
plasma kallikrein activates the epithelial sodium channel in vitro but is not essential for volume retention in nephrotic mice.recent work has demonstrated that activation of the epithelial sodium channel (enac) by aberrantly filtered serine proteases causes sodium retention in nephrotic syndrome. the aim of this study was to elucidate a potential role of plasma kallikrein (pklk) as a candidate serine protease in this context.201829489063
hydrolytic activity of human nudt16 enzyme on dinucleotide cap analogs and short capped oligonucleotides.human nudt16 (hnudt16) is a member of the nudix family of hydrolases, comprising enzymes catabolizing various substrates including canonical (d)ntps, oxidized (d)ntps, nonnucleoside polyphosphates, and capped mrnas. decapping activity of the xenopus laevis (x29) nudt16 homolog was observed in the nucleolus, with a high specificity toward u8 snorna. subsequent studies have reported cytoplasmic localization of mammalian nudt16 with cap hydrolysis activity initiating rna turnover, similar to dcp2. ...201829483298
a novel rhodopsin phosphodiesterase from salpingoeca rosetta shows light-enhanced substrate affinity.it is since many years textbook knowledge that the concentration of the second messenger cgmp is regulated in animal rod and cone cells by type ii rhodopsins via a g-protein signaling cascade. microbial rhodopsins with enzymatic activity for regulation of cgmp concentration were only recently discovered: in 2014 light-activated guanylyl-cyclase opsins in fungi and in 2017 a novel rhodopsin phosphodiesterase (rhopde) in the protist salpingoeca rosetta (srrhopde). the light regulation of srrhopde, ...201829483295
rare coding variants in genes encoding gabaa receptors in genetic generalised epilepsies: an exome-based case-control study.genetic generalised epilepsy is the most common type of inherited epilepsy. despite a high concordance rate of 80% in monozygotic twins, the genetic background is still poorly understood. we aimed to investigate the burden of rare genetic variants in genetic generalised epilepsy.201830033060
des-formylflustrabromine (dfbr): a structure-activity study on its ability to potentiate the action of acetylcholine at α4β2 nicotinic acetylcholine receptors.the naturally occurring indole alkaloid des-formylflustrabromine (dfbr; 1) is one of the first agents shown to act as a selective positive allosteric modulator (pam) at α4β2 nicotinic acetylcholine receptors (nachrs). we previously deconstructed this agent to determine which of its structural features contribute to its actions and have identified an agent that might serve as the basis for a " working pharmacophore". here, we elaborate the dfbr (1; ec50 = 0.2 μm) structure to identify how various ...201830028943
transplantation of ears provides insights into inner ear afferent pathfinding properties.numerous tissue transplantations have demonstrated that otocysts can develop into normal ears in any location in all vertebrates tested thus far, though the pattern of innervation of these transplanted ears has largely been understudied. here, expanding on previous findings that transplanted ears demonstrate capability of local brainstem innervation and can also be innervated themselves by efferents, we show that inner ear afferents grow toward the spinal cord mostly along existing afferent and ...201830027559
amphibian (xenopus laevis) tadpoles and adult frogs differ in their use of expanded repertoires of type i and type iii interferon cytokines.while amphibians around the globe are facing catastrophic declines, in part because of infections with pathogens such as the frog virus 3 (fv3) ranavirus; the mechanisms governing amphibian susceptibility and resistance to such pathogens remain poorly understood. the type i and type iii interferon (ifn) cytokines represent a cornerstone of vertebrate antiviral immunity, while our recent work indicates that tadpoles and adult frogs of the amphibian xenopus laevis may differ in their ifn responses ...201830018186
the b-hlh transcription factor hes3 participates in neural plate border formation by interfering with wnt/β-catenin signaling.hes3 belongs to the hes basic helix-loop-helix family of transcriptional repressors that play central roles in maintaining progenitor cells and regulating binary cell fate decisions in the embryo. during xenopus laevis development, hes3 is expressed in the embryonic ectoderm in a horseshoe shape domain at the edge of the developing neural pate. hes3 mis-expression at early neurula stage blocks neural crest (snai2, sox8, sox9 and sox10) and cranial placode (six1 and dmrta1) gene expression, and p ...201830016640
plc and ip3-evoked ca2+ release initiate the fast block to polyspermy in xenopus laevis eggs.the prevention of polyspermy is essential for the successful progression of normal embryonic development in most sexually reproducing species. in external fertilizers, the process of fertilization induces a depolarization of the egg's membrane within seconds, which inhibits supernumerary sperm from entering an already-fertilized egg. this fast block requires an increase of intracellular ca2+ in the african clawed frog, xenopus laevis, which in turn activates an efflux of cl- that depolarizes the ...201830012841
comprehensive substrate characterization of 22 antituberculosis drugs for multiple solute carrier (slc) uptake transporters in vitro.the substrate potentials of antituberculosis drugs on solute carrier (slc) transporters are not well characterized to date, despite a well-established understanding of their drug dispositions and pharmacokinetics. in this study, we investigated comprehensively the substrate potentials of the 22 currently available antituberculosis drugs for slc family transporter-mediated uptake, using xenopus laevis oocytes and stably transfected hek-293 cells in vitro the result suggested that ethambutol, ison ...201830012768
a gene regulatory network underlying the formation of pre-placodal ectoderm in xenopus laevis.the neural plate border ectoderm gives rise to key developmental structures during embryogenesis, including the neural crest and the preplacodal ectoderm. many sensory organs and ganglia of vertebrates develop from cranial placodes, which themselves arise from preplacodal ectoderm, defined by expression of transcription factor six1 and its coactivator eya1. here we elucidate the gene regulatory network underlying the specification of the preplacodal ectoderm in xenopus, and the functional intera ...201830012125
water contaminants associated with unconventional oil and gas extraction cause immunotoxicity to amphibian tadpoles.chemicals associated with unconventional oil and gas (uog) operations have been shown to contaminate surface and ground water with a variety of endocrine disrupting compounds (edcs) inducing multiple developmental alteration in mice. however, little is known about the impacts of uog-associated contaminants on amphibian health and resistance to an emerging ranavirus infectious disease caused by viruses in the genus ranavirus, especially at the vulnerable tadpole stage. here we used tadpoles of th ...201830011011
thiodipeptides targeting the intestinal oligopeptide transporter as a general approach to improving oral drug delivery.the broad substrate capacity of the intestinal oligopeptide transporter, pept1, has made it a key target of research into drug delivery. whilst the substrate capacity of this transporter is broad, studies have largely been limited to small peptides and peptide-like drugs. here, we demonstrate for the first time that a diverse range of drugs can be targeted towards transport by pept1 using a hydrolysis resistant carrier. eleven prodrugs were synthesized by conjugating modified dipeptides containi ...201830006163
pharmacological and toxicological activity of rsd921, a novel sodium channel blocker.rsd921, the r,r enantiomer of the kappa (k) agonist pd117,302, lacks significant activity on opioid receptors.201829990839
human mutations in slc2a9 (glut9) affect transport capacity for urate.slc2a9 or glut9 is a voltage sensitive urate transporter, mainly expressed in the kidneys, the liver, and the intestine. human glut9 loss-of-function mutations were identified in familial hypouricemia, and several single nucleotide polymorphisms (snps) were associated with lower serum urate, further indicating that glut9 is a major determinant of serum uric acid level. to get insights in glut9 transport characteristics, we systematically analyzed the function of known human glut9 mutants using 1 ...201829967582
the fungal alkaloid okaramine-b activates an l-glutamate-gated chloride channel from ixodes scapularis, a tick vector of lyme disease.a novel l-glutamate-gated anion channel (iscaglucl1) has been cloned from the black-legged tick, ixodes scapularis, which transmits multiple pathogens including the agents of lyme disease and human granulocytic anaplasmosis. when mrna encoding iscaglucl1 was expressed in xenopus laevis oocytes, we detected robust 50-400 na currents in response to 100 μm l-glutamate. responses to l-glutamate were concentration-dependent (pec50 3.64 ± 0.11). ibotenate was a partial agonist on iscaglucl1. we detect ...201829957333
multiple massive domestication and recent amplification of kolobok superfamily transposons in the clawed frog xenopus.dna transposons are generally destroyed by mutations and have short lifespans in hosts, as they are neutral or harmful to the host and therefore not conserved by natural selection. the clawed frog xenopus harbors many dna transposons and certain families, such as t2-mite, have extremely long lives. these have ancient origins, but have shown recent transposition activity. in addition, certain transposase genes may have been "domesticated" by xenopus and conserved over long time periods by natural ...201829946483
adamts9, a member of the adamts family, in xenopus development.extracellular matrix (ecm) remodeling by metalloproteinases is crucial during development. the adamts (a disintegrin and metalloproteinase with thrombospondin type i motifs) enzymes are secreted, multi-domain matrix-associated zinc metalloendopeptidases that have diverse roles in tissue morphogenesis and patho-physiological remodeling. the human family includes 19 members. in this study we identified the 19 members of the adamts family in xenopus laevis and xenopus tropicalis. gene identificatio ...201829935379
influenza d virus m2 protein exhibits ion channel activity in xenopus laevis oocytes.a new type of influenza virus, known as type d, has recently been identified in cattle and pigs. influenza d virus infection in cattle is typically asymptomatic; however, its infection in swine can result in clinical disease. swine can also be infected with all other types of influenza viruses, namely a, b, and c. consequently, swine can serve as a "mixing vessel" for highly pathogenic influenza viruses, including those with zoonotic potential. currently, the only antiviral drug available target ...201829927982
probing proline residues in the prokaryotic ligand-gated ion channel, elic.erwinia ligand-gated ion channel (elic) is a bacterial homologue of vertebrate pentameric ligand-gated ion channels (plgics) and has proven to be a valuable model for understanding the structure and function of this important protein family. there is nevertheless still a question about whether molecular details can be accurately extrapolated from this protein to those found in eukaryotes. here we explore the role of proline residues (pros) in elic by creating mutant receptors, expressing them in ...201829927250
nuclear arp2/3 drives dna break clustering for homology-directed repair.dna double-strand breaks repaired by non-homologous end joining display limited dna end-processing and chromosomal mobility. by contrast, double-strand breaks undergoing homology-directed repair exhibit extensive processing and enhanced motion. the molecular basis of this movement is unknown. here, using xenopus laevis cell-free extracts and mammalian cells, we establish that nuclear actin, wasp, and the actin-nucleating arp2/3 complex are recruited to damaged chromatin undergoing homology-direc ...201829925947
gitelman's syndrome: characterization of a novel c.1181g>a point mutation and functional classification of the known mutations.we have investigated the mechanisms by which a novel missense point mutation (c.1181g>a) found in two sisters causes gitelman's syndrome by impairing the sodium chloride co-transporter (ncc, encoded by slc12a3 gene) function. the cdna and in vitro transcribed mrna of either wild-type or mutated slc12a3 were transfected into hek293 cells and injected into xenopus laevis oocytes, respectively. the expression, maturation, trafficking, and function of the mutated and wild-type ncc were assessed by w ...201829925901
regulation of nuclear factor of activated t cells (nfat) and downstream myogenic proteins during dehydration in the african clawed frog.xenopus laevis, otherwise known as the african clawed frog, undergoes natural dehydration of up to 30% of its total body water during the dry season in sub-saharan africa. to survive under these conditions, a variety of physiological and biochemical changes take place in x. laevis. we were interested in understanding the role that the calcineurin-nfat pathway plays during dehydration stress response in the skeletal muscles of x. laevis. immunoblotting was performed to characterize the protein le ...201829923155
semicircular canal influences on the developmental tuning of the translational vestibulo-ocular reflex.vestibulo-ocular reflexes (vors) rely on neuronal computations that transform vestibular sensory signals into spatio-temporally appropriate extraocular motor commands. the motoneuronal discharge for contractions of the superior oblique eye muscle during linear translation derives from a utricular epithelial sector that is spatially aligned with the pulling direction of this muscle. in xenopus laevis, the alignment is gradually achieved during larval development and requires motion-related semici ...201829922219
a wide variety of mitf transcript variants are expressed in the xenopus laevis periodic albino mutant.the periodic albino mutant of xenopus laevis has been used to study the development of pigment cells because both the retinal pigment epithelium (rpe) and melanophores are affected. in this mutant, "white pigment cells" containing both melanophore-specific and iridophore-specific pigment organelles appear. the present experiments were designed to investigate the structural organization and expression of microphthalmia-associated transcription factor (mitf) in the mutant since mitf is known to re ...201829920861
a sodium transporter hvhkt1;1 confers salt tolerance in barley via regulating tissue and cell ion homeostasis.our previous studies showed that high salt tolerance in tibetan wild barley accessions was associated with hvhkt1;1, a member of the high-affinity potassium transporter family. however, molecular mechanisms of hvhkt1;1 for salt tolerance and its roles in k+/na+ homeostasis remain to be elucidated. functional characterization of hvhkt1;1 was conducted in the present study. nacl-induced transcripts of hvhkt1;1 were significantly higher in the roots of tibetan wild barley xz16 relative to other gen ...201829917153
isolation and functional characterization of cslsi2, a cucumber silicon efflux transporter gene.silicon has been proven to exert beneficial effects on plant growth and stress tolerance, and silicon accumulation varies among different plant species. cucumber (cucumis sativus) is a widely used dicot model for silicon accumulation, but little is known about the molecular mechanism of its silicon uptake. previously, we isolated and characterized cslsi1, a silicon influx transporter gene from cucumber. in this study, we cloned a putative silicon efflux transporter gene, cslsi2, from cucumber an ...201829905780
the rna-binding complex escrt-ii in xenopus laevis eggs recognizes purine-rich sequences through its subunit, vps25.rna-binding proteins (rbp) are critical regulators of gene expression. recent studies have uncovered hundreds of mrna-binding proteins that do not contain annotated rna-binding domains and have well-established roles in other cellular processes. investigation of these nonconventional rbps is critical for revealing novel rna-binding domains and may disclose connections between rna regulation and other aspects of cell biology. the endosomal sorting complex required for transport ii (escrt-ii) is a ...201829903915
transcriptome of xenopus andrei, an octoploid frog, during embryonic development.although polyploidy occurs throughout the fish and amphibian lineages, the xenopus genus exhibits a high incidence of polyploidy, with 25 out of the 26 known species being polyploid. however, transcriptomic information is currently available for only one of these species, the tetraploid xenopus laevis. xenopus andrei, an octoploid species within the xenopus genus, offers an opportunity for assessing a novel polyploid transcriptome during vertebrate development. rna-seq data was generated at nine ...201829900348
validation and bioinformatics analysis of differentially expressed circrnas involved in developing male xenopus laevis chronically exposed to atrazine.the data presented here are related to the research article titled "identification of circular rnas and their alterations involved in developing male xenopus laevis chronically exposed to atrazine" (sai et al., 2018) [1]. circular rnas (circrnas) are implicated in multiple developmental anomalies (bachmayr-heyda et al., 2015; li et al., 2015) [2], [3]. this report describes the differentially expressed circrnas involved in developing male xenopus laevis (x. laevis) chronically exposed to atrazin ...201829900306
visualization of gene expression patterns by in situ hybridization on early stages of development of xenopus laevis.in situ hybridization performed using whole fixed embryos provides accurate and detailed visualization of gene expression patterns. these patterns are useful for investigating spatial patterns of gene expression in normally developing embryos but can also be useful in investigating the effects of genetic or environmental changes on expression of genetic markers characteristic of particular tissues, organs, or genetic pathways. our lab's protocol for whole-mount in situ hybridization is presented ...201829896701
evaluation of teratogenicity of pharmaceuticals using fetax.pharmaceuticals are chemical compounds which are used to preserve human and animal health. once administered, these compounds are metabolized or can remain unaltered until excreted. therefore, a mixture of pharmaceuticals and their metabolites enters municipal sewers and wastewater treatment plants where, depending on their polarity, water solubility, and persistence, they cannot be completely removed or transformed during the treatment process, so that unaltered pharmaceuticals and/or their met ...201829896699
micrornas associated with early neural crest development in xenopus laevis.the neural crest (nc) is a class of transitory stem cell-like cells unique to vertebrate embryos. nc cells arise within the dorsal neural tube where they undergo an epithelial to mesenchymal transition in order to migrate and differentiate throughout the developing embryo. the derivative cell types give rise to multiple tissues, including the craniofacial skeleton, peripheral nervous system and skin pigment cells. several well-studied gene regulatory networks underpin nc development, which when ...201829347911
robustly cycling xenopus laevis cell-free extracts in teflon chambers.a central advantage of studying xenopus laevis is the manipulability of its cell-free extracts, which perform the cell cycle in vitro. however, these extracts are known to be experimentally temperamental and will often complete at most one or two cycles. over the course of developing systems for imaging cell cycle events in extracts in real time, we unexpectedly found that when standard xenopus extracts are placed in teflon tubes, they cycle extremely robustly; in one series of experiments, over ...201829475997
centromere and kinetochore assembly in xenopus laevis egg extract.during cell division, chromosomes must be equally segregated to daughter cells. centromeres, the primary interaction site between chromosomes and microtubules, mediate faithful chromosome segregation during mitosis. functional studies of centromere proteins in cells have proven difficult, as mutation or deletion of most centromeric proteins often results in cell lethality. in this protocol, sperm chromatin or reconstituted chromatin arrays, together with xenopus laevis egg extracts, are used to ...201829475995
functional analysis of a triplet deletion in the gene encoding the sodium glucose transporter 3, a potential risk factor for adhd.sodium-glucose transporters (sglt) belong to the solute carrier 5 family, which is characterized by sodium dependent transport of sugars and other solutes. in contrast, the human sglt3 (hsglt3) isoform, encoded by slc5a4, acts as a glucose sensor that does not transport sugar but induces membrane depolarization by na+ currents upon ligand binding. whole-exome sequencing (wes) of several extended pedigrees with high density of attention-deficit/hyperactivity disorder (adhd) identified a triplet a ...201830286162
nucleosomes and the three glycosylases: high, medium, and low levels of excision by the uracil dna glycosylase superfamily.human cells express the udg superfamily of glycosylases, which excise uracil (u) from the genome. the three members of this structural superfamily are uracil dna glycosylase (ung/udg), single-strand selective monofunctional uracil dna glycosylase (smug1), and thymine dna glycosylase (tdg). we previously reported that udg is efficient at removing u from dna packaged into nucleosome core particles (ncp) and is minimally affected by the histone proteins when acting on an outward-facing u in the dya ...201830268365
a xenopus oocyte model system to study action potentials.action potentials (aps) are the functional units of fast electrical signaling in excitable cells. the upstroke and downstroke of an ap is generated by the competing and asynchronous action of na+- and k+-selective voltage-gated conductances. although a mixture of voltage-gated channels has been long recognized to contribute to the generation and temporal characteristics of the ap, understanding how each of these proteins function and are regulated during electrical signaling remains the subject ...201830266757
cloning and functional characterisation of the duplicated rdl subunits from the pea aphid, acyrthosiphon pisum.the insect gaba receptor, rdl (resistance to dieldrin), is a cys-loop ligand-gated ion channel (cyslgic) that plays a central role in neuronal signaling, and is the target of several classes of insecticides. many insects studied to date possess one rdl gene; however, there is evidence of two rdls in aphids. to characterise further this insecticide target from pests that cause millions of dollars' worth of crop damage each year, we identified the complete cyslgic gene superfamily of the pea aphid ...201830065178
α1-fangs: protein ligands selective for the α-bungarotoxin site of the α1-nicotinic acetylcholine receptor.nicotinic acetylcholine receptors (nachrs) are pentameric ligand-gated ion channels that play a central role in neuronal and neuromuscular signal transduction. here, we have developed fang ligands, fibronectin antibody-mimetic nicotinic acetylcholine receptor-generated ligands, using mrna display. we generated a 1 trillion-member primary e10fniii library to target a stabilized α1 nicotinic subunit (α211). this library yielded 270000 independent potential protein binding ligands. the lead sequenc ...201830059207
altered thyroid hormone levels affect body condition at metamorphosis in larvae of xenopus laevis.chemical, physical and biological environmental stressors may affect the endocrine system, such as the thyroid hormone (th) axis in larval amphibians with consequences for energy partitioning among development, growth and metabolism. we studied the effects of two th level affecting compounds, exogenous l-thyroxine (t4 ) and sodium perchlorate (sp), on various measures of development and body condition in larvae of the african clawed frog (xenopus laevis). we calculated the scaled mass index, hep ...201830058724
tight junction-associated protein gef-h1 in the neighbours of dividing epithelial cells is essential for adaptation of cell-cell membrane during cytokinesis.animal cells divide by a process called cytokinesis which relies on the constriction of a contractile actomyosin ring leading to the production of two daughter cells. cytokinesis is an intrinsic property of cells which occurs even for artificially isolated cells. during division, isolated cells undergo dramatic changes in shape such as rounding and membrane deformation as the division furrow ingresses. however, cells are often embedded in tissues and thus are surrounded by neighbouring cells. ho ...201830056063
nosip functions during vertebrate eye and cranial cartilage development.the nitric oxide synthase interacting protein (nosip) has been associated with diverse human diseases including psychological disorders. in line, early neurogenesis of mouse and xenopus is impaired upon nosip deficiency. nosip knockout mice show craniofacial defects and the down-regulation of nosip in the mouse and xenopus leads to microcephaly. until now, the exact underlying molecular mechanisms of these malformations were still unknown.201830055071
a cyclic nucleotide-gated channel, hvcngc2-3, is activated by the co-presence of na⁺ and k⁺ and permeable to na⁺ and k⁺ non-selectively.cyclic nucleotide-gated channels (cngcs) have been postulated to contribute significantly in plant development and stress resistance. however, their electrophysiological properties remain poorly understood. here, we characterized barley cngc2-3 (hvcngc2-3) by the two-electrode voltage-clamp technique in the xenopus laevis oocyte heterologous expression system. current was not observed in x. laevis oocytes injected with hvcngc2-3 complementary rna (crna) in a bathing solution containing either na ...201830049942
xenopus: an alternative model system for identifying muco-active agents.the airway epithelium in human plays a central role as the first line of defense against environmental contaminants. most respiratory diseases such as chronic obstructive pulmonary disease (copd), asthma, and respiratory infections, disturb normal muco-ciliary functions by stimulating the hypersecretion of mucus. several muco-active agents have been used to treat hypersecretion symptoms in patients. current muco-active reagents control mucus secretion by modulating either airway inflammation, ch ...201829470529
dicer inactivation stimulates limb regeneration ability in xenopus laevis.the ontogenetic decline of regeneration capacity in the anuran amphibian xenopus makes it an excellent model for regeneration studies. however, the cause of the regeneration ability decline is not fully understood. micrornas regulate animal development and have been indicated in various regeneration situations. however, little is known about the role of micrornas during limb regeneration in xenopus. this study investigates the effect of dicer, an enzyme responsible for microrna maturation, on li ...201829453851
invasive african clawed frogs in california: a reservoir for or predator against the chytrid fungus?amphibian species are experiencing population declines due to infection by the fungal pathogen, batrachochytrium dendrobatidis (bd). the african clawed frog (xenopus laevis), an asymptomatic carrier of bd, has been implicated in the spread of this pathogen through global trade and established invasive populations on several continents. however, research has not explored the relationships of both life stages of this amphibian with bd. while the post-metamorphic individuals may act as a reservoir, ...201829444096
tissue stiffening coordinates morphogenesis by triggering collective cell migration in vivo.collective cell migration is essential for morphogenesis, tissue remodelling and cancer invasion. in vivo, groups of cells move in an orchestrated way through tissues. this movement involves mechanical as well as molecular interactions between cells and their environment. while the role of molecular signals in collective cell migration is comparatively well understood, how tissue mechanics influence collective cell migration in vivo remains unknown. here we investigated the importance of mechani ...201829443958
primordial germ cell transplantation for crispr/cas9-based leapfrogging in xenopus.the creation of mutant lines by genome editing is accelerating genetic analysis in many organisms. crispr/cas9 methods have been adapted for use in the african clawed frog, xenopus, a longstanding model organism for biomedical research. traditional breeding schemes for creating homozygous mutant lines with crispr/cas9-targeted mutagenesis have several time-consuming and laborious steps. to facilitate the creation of mutant embryos, particularly to overcome the obstacles associated with knocking ...201829443056
amphibian zic genes.studies in xenopus laevis have greatly contributed to understanding the roles that the zic family of zinc finger transcription factors play as essential drivers of early development. explant systems that are not readily available in other organisms give xenopus embryos a unique place in these studies, facilitated by the recent sequencing of the xenopus laevis genome. a number of upstream regulators of zic gene expression have been identified, such as inhibition of bmp signaling, as well as calci ...201829442320
isolation and demembranation of xenopus sperm nuclei.the inherent experimental advantages of intact amphibian eggs have been exploited for several decades to advance our understanding of fundamental developmental processes and the cell cycle. characterization of these processes at the molecular level has been greatly advanced by the use of cell-free extracts, which permit the development of biochemically tractable approaches. demembranated xenopus laevis sperm nuclei have been used with cell-free extracts to recapitulate cell cycle progression and ...201829438000
preparation of cellular extracts from xenopus eggs and embryos.cell-free cytoplasmic extracts prepared from xenopus eggs have been used extensively to recapitulate and characterize intracellular events in vitro. egg extracts can be induced to transit the cell cycle and reconstitute assembly of dynamic structures including the interphase nucleus and the mitotic spindle. in this protocol, methods are described for preparing crude cytoplasmic extracts from xenopus eggs and embryos that are arrested in metaphase of the cell cycle. the basic protocol uses unfert ...201829437998
fluorescence in situ hybridization of cryosectioned xenopus oocytes.xenopus laevis oocytes are widely used to study mechanisms of rna function and biogenesis. while the large size of xenopus oocytes is amenable to both biochemical and imaging approaches, the relative opacity of the yolk-rich cytoplasm has limited high-resolution imaging of endogenous rnas. here, we present a protocol that combines multi-probe fluorescence in situ hybridization with cryosectioning to provide a highly sensitive means of imaging endogenous oocyte rnas.201829437997
assembly of spindles and asters in xenopus egg extracts.here, we provide methods for assembly of mitotic spindles and interphase asters in xenopus laevis egg extract, and compare them to spindles and asters in the egg and zygote. classic "cycled" spindles are made by adding sperm nuclei to metaphase-arrested cytostatic factor (csf) extract and inducing entry into interphase extract to promote nucleus formation and dna replication. interphase nuclei are then converted to cycled spindles arrested in metaphase by addition of csf extract. kinetochores as ...201829437996
plant cation-chloride cotransporters (ccc): evolutionary origins and functional insights.genomes of unicellular and multicellular green algae, mosses, grasses and dicots harbor genes encoding cation-chloride cotransporters (ccc). ccc proteins from the plant kingdom have been comparatively less well investigated than their animal counterparts, but proteins from both plants and animals have been shown to mediate ion fluxes, and are involved in regulation of osmotic processes. in this review, we show that ccc proteins from plants form two distinct phylogenetic clades (ccc1 and ccc2). s ...201829415511
threonine 67 is a key component in the coupling of the nss amino acid transporter kaat1. 201829409909
molecular cloning, spatiotemporal and functional expression of gaba receptor subunits rdl1 and rdl2 of the rice stem borer chilo suppressalis.insect γ-aminobutyric acid (gaba) receptor (gabar) is one of the major targets of insecticides. in the present study, cdnas (csrdl1a and csrdl2s) encoding the two isoforms of rdl subunits were cloned from the rice stem borer chilo suppressalis. transcripts of both genes demonstrated similar expression patterns in different tissues and developmental stages, although csrdl2s was ∼2-fold more abundant than csrdl1a throughout all development stages. to investigate the function of channels formed by ...201829408355
tooth germ initiation patterns in a developing dentition: an in vivo study of xenopus laevis tadpoles.the transparency of soft tissue in xenopus laevis tadpoles and the anterior-posterior orientation of their developing tooth germs in the upper jaw offer a unique opportunity for the in vivo charting of the first 15-20 days of the developing dentition. twenty-two x. laevis tadpoles were anesthetized daily and their mouths opened to record the first appearance, position, and development of tooth germs in the upper jaw. the initiation patterns revealed considerable variability between animals, and ...201829399866
the phosphorylation site t613 in the β-subunit of rat epithelial na+ channel (enac) modulates channel inhibition by nedd4-2.the epithelial na+ channel (enac) is a heteromeric channel composed of three subunits (α, β, γ). at the c-terminus of each subunit, a py-motif allows binding of the ubiquitin ligase nedd4-2 which plays a key role in promoting enac retrieval from the plasma membrane. phosphorylation of nedd4-2 by the serum and glucocorticoid-inducible kinase 1 (sgk1) reduces nedd4-2 binding to the py-motifs. in β and γenac, threonine residues (βt613, γt623) belong to an extracellular signal-regulated kinase (erk) ...201829397423
a multichannel computer-driven system to raise aquatic embryos under selectable hypoxic conditions.the formation of a functional cardiovascular system is an essential step in the early vertebrate embryo. nevertheless, the effect of hypoxia on the developmental program of organisms was studied rarely. in particular, this holds true for vertebrate embryos that depend on a functional placenta for proper development and had not been studied in this respect due to the obvious limitation. we established a protocol to culture aquatic embryos, which enabled us to culture a high number of xenopus embr ...201829392150
stac3 enhances expression of human cav1.1 in xenopus oocytes and reveals gating pore currents in hypopp mutant channels.mutations of cav1.1, the pore-forming subunit of the l-type ca2+ channel in skeletal muscle, are an established cause of hypokalemic periodic paralysis (hypopp). however, functional assessment of hypopp mutant channels has been hampered by difficulties in achieving sufficient plasma membrane expression in cells that are not of muscle origin. in this study, we show that coexpression of stac3 dramatically increases the expression of human cav1.1 (plus α2-δ1b and β1a subunits) at the plasma membran ...201829386226
protein immunodepletion and complementation in xenopus laevis egg extracts.the xenopus egg extract system has been widely used to study cell cycle events, including dna replication, nuclear envelope formation, spindle assembly, chromosome condensation and kinetochore formation. the functional roles of the proteins involved in these processes can be determined by immunodepleting a protein of interest from the extract. as immunodepletion may result in co-depletion of other proteins, the protein of interest can be added back to the extract to verify its function. addition ...201829382808
quantitative proteomics after spinal cord injury (sci) in a regenerative and a nonregenerative stage in the frog xenopus laevis.the capacity to regenerate the spinal cord after an injury is a coveted trait that only a limited group of nonmammalian organisms can achieve. in xenopus laevis, this capacity is only present during larval or tadpole stages, but is absent during postmetamorphic frog stages. this provides an excellent model for comparative studies between a regenerative and a nonregenerative stage to identify the cellular and molecular mechanisms that explain this difference in regenerative potential. here, we us ...201829358338
a model for investigating developmental eye repair in xenopus laevis.vertebrate eye development is complex and requires early interactions between neuroectoderm and surface ectoderm during embryogenesis. in the african clawed frog, xenopus laevis, individual eye tissues such as the retina and lens can undergo regeneration. however, it has been reported that removal of either the specified eye field at the neurula stage or the eye during tadpole stage does not induce replacement. here we describe a model for investigating xenopus developmental eye repair. we found ...201829357285
[morphomechanical factors in gastrulation process and differentiation of embryonic tissue of xenopus laevis].effect of mechanical stretch on the differentiation of axial anlages and chordin gene expressionwas studied in sandwich explants prepared from embryonic tissues of xenopus laevis at the early gastrula stagein two variants: with dissected or intact dorso-medial region. in the first case, convergent cell movementswere suppressed and properly organized axial organs (notochord and somites) were almost completely absent.however, they developed if the explants of such type were artificially stretched ...201830272924
[role of mechano-dependent cell movements in the establishment of spatial organization of axial rudiments in xenopus laevis embryos].trajectories of individual cell movements and patterns of differentiation in the axial rudiments insuprablastoporal areas (sba) in whole embryos of xenopus laevis artificially stretched in the transverse directionup to 120–200% from the initial length at the early gastrula stage were mapped. we observed the impairmentof anisotropic cell movements of longitudinal stretching and latero-medial convergence inherent forsba. axial rudiments occurred in all cases, but their location was completely impa ...201830272919
[geometry of movement of the outer surface of the embryo during xenopus gastrulation].the surface of xenopus laevis embryos was marked with carbon particles, after which the locationof mark groups was recorded by time-lapse video imaging and subsequent image analysis until their disappearancein the depth of gastric invagination. measuring the distances between individually identifiablemarks whose size is smaller than the size of a single cell makes it possible to quantitatively analyze the geometryof collective cell movement without any external coordinate system. during the dors ...201830272406
[secreted protein noggin4 participates in the formation of forebrain structures in xenopus laevis by inhibitingthe wnt/beta-catenin signaling pathway].noggin proteins are important regulators of the early development of the vertebrate neural system.previously, it has been traditionally thought that vertebrates have only one noggin gene (noggin1), whosemain function is the inhibition of bmp signaling pathway during the formation of dorsoventral polarity inembryos. then other proteins of this family were discovered, and the studies of noggin2 protein showed thatnoggin proteins also participate in the modulation of nodal/activin and wnt/beta-cate ...201830272399
time-lapse imaging of cell death in cell culture and whole living organisms using turn-on deep-red fluorescent probes.cell death is a central process in developmental biology and also an important indicator of disease status and treatment efficacy. two related fluorescent probes are described that are molecular conjugates of one or two zinc dipicolylamine (zndpa) coordination complexes with an appended solvatochromic benzothiazolium squaraine dye. the probes were designed to target the anionic phospholipid, phosphatidylserine (ps), that is exposed on the surface of dead and dying cells. a series of spectrometri ...201830858977
effects of copper on the early development of xenopus laevis: the case of cuso4 and bordeaux mixture solutions. 201830701063
ventx1.1 as a direct repressor of early neural gene zic3 in xenopus laevis.from xenopus embryo studies, the bmp4/smad1-targeted gene circuit is a key signaling pathway for specifying the cell fate between the ectoderm and neuro-ectoderm as well as the ventral and dorsal mesoderm. in this context, several bmp4/smad1 target transcriptional factors have been identified as repressors of the neuro-ectoderm. however, none of these direct target transcription factors in this pathway, including gata1b, msx1 and ventx1.1 have yet been proven as direct repressors of early neuro- ...201830590909
development of a rapid functional assay that predicts glut1 disease severity.to examine the genotype to phenotype connection in glucose transporter type 1 (glut1) deficiency and whether a simple functional assay can predict disease outcome from genetic sequence alone.201830588498
xenopus hybrids provide insight into cell and organism size control.determining how size is controlled is a fundamental question in biology that is poorly understood at the organismal, cellular, and subcellular levels. the xenopus species, x. laevis and x. tropicalis differ in size at all three of these levels. despite these differences, fertilization of x. laevis eggs with x. tropicalis sperm gives rise to viable hybrid animals that are intermediate in size. we observed that although hybrid and x. laevis embryogenesis initiates from the same sized zygote and pr ...201830564147
alteration of the retinoid acid-cbp signaling pathway in neural crest induction contributes to enteric nervous system disorder.hirschsprung disease (hscr) and/or hypoganglionosis are common pediatric disorders that arise from developmental deficiencies of enteric neural crest cells (enccs). retinoid acid (ra) signaling has been shown to affect neural crest (nc) development. however, the mechanisms underlying ra deficiency-induced hscr or hypoganglionosis are not well-defined. in this report, we found that in hscr patient bowels, the ra nuclear receptor rarα and its interacting coregulator creb-binding protein (cbp) were ...201830560112
modeling underwater hearing and sound localization in the frog xenopus laevis.animals that are small compared to sound wavelengths face the challenge of localizing a sound source since the main cues to sound direction-interaural time differences (itd) and interaural level differences (ild)-both depend on size. remarkably, the majority of terrestrial vertebrates possess internally coupled ears (ice) with an air-filled cavity connecting the two eardrums and producing an inherently directional middle-ear system. underwater, longer wavelengths and faster sound-speed reduce bo ...201830522324
silurana chromosomal evolution: a new piece to the puzzle.the african clawed frogs of the subgenus silurana comprise both diploid and tetraploid species. the root of the polyploidization event leading to the extant xenopus calcaratus, x. mellotropicalis, and x. epitropicalis is not fully understood so far. in x. mellotropicalis, we previously proposed 2 evolutionary scenarios encompassing complete (scenario a) or incomplete (scenario b) translocation of a heterochromatic block from chromosome 9 to 2 in a diploid ancestor. to resolve this puzzle, we per ...201830537723
the interplay between voluntary food intake, dietary carbohydrate-lipid ratio and nutrient metabolism in an amphibian, (xenopus laevis).digestion of food and metabolism of frogs are little studied at the moment, and such processes could be very particular in the case of amphibians, given their ectothermic and carnivorous nature which may lead them to use nutrients through specific biochemical pathways. in the present study, 24 adult xenopus laevis (six replicates with two frogs per treatment) were randomly assigned to two diets with different carbohydrate:fat ratio (4.5:1 and 2.1:1), changing the dietary glucogenic and lipogenic ...201830532132
control of xenopus tadpole locomotion via selective expression of ih in excitatory interneurons.locomotion relies on the coordinated activity of rhythmic neurons in the hindbrain and spinal cord and depends critically on the intrinsic properties of excitatory interneurons. therefore, understanding how ion channels sculpt the properties of these interneurons, and the consequences for circuit function and behavior, is an important task. the hyperpolarization-activated cation current, ih, is known to play important roles in shaping neuronal properties and for rhythm generation in many neurona ...201830503615
genomic takeover by transposable elements in the strawberry poison frog.we sequenced the genome of the strawberry poison frog, oophaga pumilio, at a depth of 127.5× using variable insert size libraries. the total genome size is estimated to be 6.76 gb, of which 4.76 gb are from high copy number repetitive elements with low differentiation across copies. these repeats encompass dna transposons, rna transposons, and ltr retrotransposons, including at least 0.4 and 1.0 gb of mariner/tc1 and gypsy elements, respectively. expression data indicate high levels of gypsy and ...201830517748
effects of quinine, quinidine and chloroquine on human muscle nicotinic acetylcholine receptors.the genus cinchona is known for a range of alkaloids, such as quinine, quinidine, cinchonine, and cinchonidine. cinchona bark has been used as an antimalarial agent for more than 400 years. quinine was first isolated in 1820 and is still acknowledged in the therapy of chloroquine-resistant falciparum malaria; in lower dosage quinine has been used as treatment for leg cramps since the 1940s. here we report the effects of the quinoline derivatives quinine, quinidine, and chloroquine on human adult ...201830515099
auditory perception exhibits sexual dimorphism and left telencephalic dominance in xenopus laevis.sex differences in both vocalization and auditory processing have been commonly found in vocal animals, although the underlying neural mechanisms associated with sexual dimorphism of auditory processing are not well understood. in this study we investigated whether auditory perception exhibits sexual dimorphism in xenopus laevis to do this we measured event-related potentials (erps) evoked by white noise (wn) and conspecific calls in the telencephalon, diencephalon and mesencephalon respectively ...201830509903
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