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the role of ca(2+) in progesterone-induced germinal vesicle breakdown of xenopus laevis oocytes: the synergic effects of microtubule depolymerization and ca(2+).by monitoring (45)ca(2+) influx and efflux from oocytes a transient increase followed by a transient decrease in the ca(2+)-content of progesterone-treated oocytes was observed. chelation of intracellular ca(2+) with egta or bapta-type buffers inhibited progesterone-induced gvbd. buffers with a mid-range kd (∼1.5 μm) were most effective in inhibiting gvbd whereas buffers with a kd above or below this value were less effective. these observations indicate that intracellular ca(2+), probably in th ...199624173464
two distinct allosteric binding sites at α4β2 nicotinic acetylcholine receptors revealed by ns206 and ns9283 give unique insights to binding activity-associated linkage at cys-loop receptors.positive allosteric modulators (pams) of α4β2 nicotinic acetylcholine receptors have the potential to improve cognitive function and alleviate pain. however, only a few selective pams of α4β2 receptors have been described limiting both pharmacological understanding and drug-discovery efforts. here, we describe a novel selective pam of α4β2 receptors, ns206, and compare with a previously reported pam, ns9283. using two-electrode voltage-clamp electrophysiology in xenopus laevis oocytes, ns206 was ...201324169695
significant modulation of the hepatic proteome induced by exposure to low temperature in xenopus laevis.the african clawed frog, xenopus laevis, is an ectothermic vertebrate that can survive at low environmental temperatures. to gain insight into the molecular events induced by low body temperature, liver proteins were evaluated at the standard laboratory rearing temperature (22°c, control) and a low environmental temperature (5°c, cold exposure). using nano-flow liquid chromatography coupled with tandem mass spectrometry, we identified 58 proteins that differed in abundance. a subsequent gene ont ...201324167716
structural basis of ion permeation gating in slo2.1 k+ channels.the activation gate of ion channels controls the transmembrane flux of permeant ions. in voltage-gated k(+) channels, the aperture formed by the s6 bundle crossing can widen to open or narrow to close the ion permeation pathway, whereas the selectivity filter gates ion flux in cyclic-nucleotide gated (cng) and slo1 channels. here we explore the structural basis of the activation gate for slo2.1, a weakly voltage-dependent k(+) channel that is activated by intracellular na(+) and cl(-). slo2.1 ch ...201324166878
caffeic acid inhibits organic anion transporters oat1 and oat3 in rat kidney.some food components influence drug elimination. previously, we found that caffeic acid, present in coffee, fruits, and vegetables, strongly inhibited human homologs of organic anion transporters (oats) oat1 and oat3, which are responsible for renal tubular secretion of anionic drugs. in this study, we examined the effect of caffeic acid on drug transport by oat1 and oat3 in the rat kidney.201324166669
monitoring gene expression in a single xenopus oocyte using multiple cytoplasmic collections and quantitative rt-pcr.oocytes and eggs of the african clawed frog, xenopus laevis, are commonly used in gene expression studies. however, monitoring transcript levels in the individual living oocytes remains challenging. to address this challenge, we used a technique based on multiple repeated collections of nanoliter volumes of cytoplasmic material from a single oocyte. transcript quantification was performed by quantitative rt-pcr. the technique allowed monitoring of heterologous gene expression in a single oocyte ...201424165194
novel animal pole-enriched maternal mrnas are preferentially expressed in neural ectoderm.many animals utilize maternal mrnas to pre-pattern the embryo before the onset of zygotic transcription. in xenopus laevis, vegetal factors specify the germ line, endoderm, and dorsal axis, but there are few studies demonstrating roles for animal-enriched maternal mrnas. therefore, we carried out a microarray analysis to identify novel maternal transcripts enriched in 8-cell-stage animal blastomeres.201424155242
the gafa domain of phosphodiesterase-6 contains a rod outer segment localization signal.photoreceptor phosphodiesterase-6 (pde6) is a peripheral membrane protein synthesized in the inner segment of photoreceptor cells. newly synthesized pde6 is transported to the outer segment (os) where it serves as a key effector enzyme in the phototransduction cascade. proper localization of pde6 in photoreceptors is critically important to the function and survival of photoreceptor cells. the mechanism of pde6 transport to the os remains largely unknown. in this study, we investigated potential ...201424147783
magnetic control of protein spatial patterning to direct microtubule self-assembly.living systems offer attractive strategies to generate nanoscale structures because of their innate functional properties such as the dynamic assembly of ordered nanometer fibers, the generation of mechanical forces, or the directional transport mediated by molecular motors. the design of hybrid systems, capable of interfacing artificial building blocks with biomolecules, may be a key step toward the rational design of nanoscale devices and materials. here, we have designed a bottom-up approach ...201324144301
a transgenic xenopus laevis reporter model to study lymphangiogenesis.the importance of the blood- and lymph vessels in the transport of essential fluids, gases, macromolecules and cells in vertebrates warrants optimal insight into the regulatory mechanisms underlying their development. mouse and zebrafish models of lymphatic development are instrumental for gene discovery and gene characterization but are challenging for certain aspects, e.g. no direct accessibility of embryonic stages, or non-straightforward visualization of early lymphatic sprouting, respective ...201324143274
combining different mrna capture methods to analyze the transcriptome: analysis of the xenopus laevis transcriptome.mrna sequencing (mrna-seq) is a commonly used technique to survey gene expression from organisms with fully sequenced genomes. successful mrna-seq requires purification of mrna away from the much more abundant ribosomal rna, which is typically accomplished by oligo-dt selection. however, mrnas with short poly-a tails are captured poorly by oligo-dt based methods. we demonstrate that combining mrna capture via oligo-dt with mrna capture by the 5' 7-methyl guanosine cap provides a more complete vi ...201324143257
enhanced xao: the ontology of xenopus anatomy and development underpins more accurate annotation of gene expression and queries on xenbase.the african clawed frogs xenopus laevis and xenopus tropicalis are prominent animal model organisms. xenopus research contributes to the understanding of genetic, developmental and molecular mechanisms underlying human disease. the xenopus anatomy ontology (xao) reflects the anatomy and embryological development of xenopus. the xao provides consistent terminology that can be applied to anatomical feature descriptions along with a set of relationships that indicate how each anatomical entity is r ...201324139024
expression profile of the aromatase enzyme in the xenopus brain and localization of estradiol and estrogen receptors in each tissue.estradiol (e2) with the strongest bioactivity of the estrogens, is synthesized by the cytochrome p450 aromatase enzyme and plays a key role in sex differentiation of the vertebrate's gonads. in xenopus, aromatase mrna is highly expressed in the brain rather than in the gonad during sex differentiation. in this study, we analyzed the stage change, tissue specificity, and localization of the aromatase expression in the xenopus brain. regardless of the sex difference, expression level of aromatase ...201324135319
functional evolution of a multigene family: orthologous and paralogous pheromone receptor genes in the turnip moth, agrotis segetum.lepidopteran pheromone receptors (prs), for which orthologies are evident among closely related species, provide an intriguing example of gene family evolution in terms of how new functions may arise. however, only a limited number of prs have been functionally characterized so far and thus evolutionary scenarios suffer from elements of speculation. in this study we investigated the turnip moth agrotis segetum, in which female moths produce a mixture of chemically related pheromone components th ...201324130875
expression, purification and low-resolution structure of human vitamin c transporter svct1 (slc23a1).expression and purification of human membrane proteins for structural studies represent a great challenge. this is because micro- to milligram amounts of pure isolated protein are required. to this aim, we successfully expressed the human vitamin c transporter-1 (hsvct1; slc23a1) in xenopus laevis oocytes and isolated highly pure protein in microgram amounts. recombinant hsvct1 was functional when expressed in oocytes and glycosylated. structural analysis of purified hsvct1 by transmission elect ...201324124560
gender-related sensitivity of development and growth to real microgravity in xenopus laevis.exposure of organisms to microgravity can induce morphological, physiological, and behavioral modifications which normalize after re-entry in 1g-condition within hours to few weeks. development of xenopus laevis tadpoles, their metamorphosis, and adults' growth were monitored for 3 years after their flight on the 12-day soyuz mission tma13 to the international space station. at onset of microgravity, tadpoles had just developed the hind limb (stage 47) or forelimb bud (stage 50). recordings duri ...201424123857
role of connexin 32 hemichannels in the release of atp from peripheral nerves.extracellular purines elicit strong signals in the nervous system. adenosine-5'-triphosphate (atp) does not spontaneously cross the plasma membrane, and nervous cells secrete atp by exocytosis or through plasma membrane proteins such as connexin hemichannels. using a combination of imaging, luminescence and electrophysiological techniques, we explored the possibility that connexin 32 (cx32), expressed in schwann cells (scs) myelinating the peripheral nervous system could be an important source o ...201324123415
characterization of the hypothalamus of xenopus laevis during development. ii. the basal regions.the expression patterns of conserved developmental regulatory transcription factors and neuronal markers were analyzed in the basal hypothalamus of xenopus laevis throughout development by means of combined immunohistochemical and in situ hybridization techniques. the connectivity of the main subdivisions was investigated by in vitro tracing techniques with dextran amines. the basal hypothalamic region is topologically rostral to the basal diencephalon and is composed of the tuberal (rostral) an ...201424122702
hypotonic regulation of mouse epithelial sodium channel in xenopus laevis oocytes.the regulation of the epithelial na⁺ channel (enac) during cell swelling is relevant in cellular processes in which cell volume changes occur, i.e., migration, proliferation and cell absorption. its sensitivity to hypotonically induced swelling was investigated in the xenopus oocyte expression system with the injection of the three subunits of mouse enac. we used voltage-clamp techniques to study the amiloride-sensitive na⁺ currents (ina(amil)) and video microscopic methodologies to assess oocyt ...201324121666
gaba(a) receptor transmembrane amino acids are critical for alcohol action: disulfide cross-linking and alkyl methanethiosulfonate labeling reveal relative location of binding sites.alcohols and inhaled anesthetics modulate gaba(a) receptor (gaba(a)r) function via putative binding sites within the transmembrane regions. the relative position of the amino acids lining these sites could be either inter- or intra-subunit. we introduced cysteines in relevant tm locations and tested the proximity of cysteine pairs using oxidizing and reducing agents to induce or break disulfide bridges between cysteines, and thus change gaba-mediated currents in wild-type and mutant α1β2γ2 gaba( ...201424117469
a lov-domain-mediated blue-light-activated adenylate (adenylyl) cyclase from the cyanobacterium microcoleus chthonoplastes pcc 7420.genome screening of the cyanobacterium microcoleus chthonoplastes pcc 7420 identified a gene encoding a protein (483 amino acids, 54.2 kda in size) characteristic of a bl (blue light)-regulated adenylate (adenylyl) cyclase function. the photoreceptive part showed signatures of a lov (light, oxygen, voltage) domain. the gene product, mpac (microcoleus photoactivated adenylate cyclase), exhibited the lov-specific three-peaked absorption band (λmax=450 nm) and underwent conversion into the photoadd ...201324112109
mind the gaps: investigating the cause of the current range disjunction in the cape platanna, xenopus gilli (anura: pipidae).low-lying areas of the cape at africa's south-westernmost tip have undergone dramatic marine-remodelling, with regular changes in sea-level following glacial cycles. species for which marine barriers are impenetrable underwent concomitant radical distribution changes which may account for current range disjunctions. the cape platanna, xenopus gilli, is a frog distributed in only three disjunt areas within low-lying regions of the southwestern cape. we determined the relationship between frogs fr ...201324109551
identification, characterization, and expression of dentin matrix protein 1 gene in xenopus laevis.dentin matrix protein 1 (dmp1) is an acidic extracellular matrix protein expressed mainly in bone and dentin, and is a member of the small integrin-binding ligand n-linked glycoprotein (sibling) family. the dmp1 gene, however, appears to evolve rapidly in comparison with other sibling genes, even though such functionally important molecules usually evolve more slowly than less important ones. the purpose of this study was to identify and characterize an ortholog of the dmp1 gene in an amphibian ...201324106181
metabolic activation of camkii by coenzyme a.active metabolism regulates oocyte cell death via calcium/calmodulin-dependent protein kinase ii (camkii)-mediated phosphorylation of caspase-2, but the link between metabolic activity and camkii is poorly understood. here we identify coenzyme a (coa) as the key metabolic signal that inhibits xenopus laevis oocyte apoptosis by directly activating camkii. we found that coa directly binds to the camkii regulatory domain in the absence of ca(2+) to activate camkii in a calmodulin-dependent manner. ...201324095281
functional characterization of the trypanosome translational repressor scd6.the storage of translationally inactive mrnas in cytosolic granules enables cells to react flexibly to environmental changes. in eukaryotes, scd6 (suppressor of clathrin deficiency 6)/rap55 (rna-associated protein 55), a member of the lsm14 (like-sm14) family, is an important factor in the formation and activity of p-bodies, where mrna decay factors accumulate, in stress granules that store mrnas under adverse conditions and in granules that store developmentally regulated mrnas. scd6 from trypa ...201424087925
molecular characterization and expression analysis of a kifc1-like kinesin gene in the testis of eumeces chinensis.the member of the kinesin-14 subfamily, kifc1, is a carboxyl-terminal motor protein that plays an important role in the elongation of nucleus and acrosome biogenesis during the spermiogenesis of mammals. here, we had cloned and sequenced the cdna of a mammalian kifc1 homologue (termed ec-kifc1) from the total rna of the testis of the reptile eumeces chinensis. the full-length sequence was 2,339 bp that contained a 216 bp 5'-untranslated region (5'utr), a 194 bp 3'-untranslated region (3'utr) and ...201324078165
calpain2 protease: a new member of the wnt/ca(2+) pathway modulating convergent extension movements in xenopus.calpains are a family of calcium-dependent intracellular cysteine proteases that regulate several physiological processes by limited cleavage of different substrates. the role of calpain2 in embryogenesis is not clear with conflicting evidence from a number of mouse knockouts. here we report the temporal and spatial expression of calpain2 in xenopus laevis embryos and address its role in xenopus development. we show that calpain2 is expressed maternally with elevated expression in neural tissues ...201324076278
indoxacarb, metaflumizone, and other sodium channel inhibitor insecticides: mechanism and site of action on mammalian voltage-gated sodium channels.sodium channel inhibitor (sci) insecticides were discovered almost four decades ago but have only recently yielded important commercial products (eg., indoxacarb and metaflumizone). sci insecticides inhibit sodium channel function by binding selectively to slow-inactivated (non-conducting) sodium channel states. characterization of the action of sci insecticides on mammalian sodium channels using both biochemical and electrophysiological approaches demonstrates that they bind at or near a drug r ...201324072940
insight into the intermolecular recognition mechanism between keap1 and ikkβ combining homology modelling, protein-protein docking, molecular dynamics simulations and virtual alanine mutation.degradation of certain proteins through the ubiquitin-proteasome pathway is a common strategy taken by the key modulators responsible for stress responses. kelch-like ech-associated protein-1(keap1), a substrate adaptor component of the cullin3 (cul3)-based ubiquitin e3 ligase complex, mediates the ubiquitination of two key modulators, nf-e2-related factor 2 (nrf2) and iκb kinase β (ikkβ), which are involved in the redox control of gene transcription. however, compared to the keap1-nrf2 protein- ...201324066166
chromatin immunoprecipitation and deep sequencing in xenopus tropicalis and xenopus laevis.chromatin immunoprecipitation and deep sequencing (chip-seq) represents a powerful tool for identifying the genomic targets of transcription factors, chromatin remodeling factors, and histone modifications. the frogs xenopus laevis and xenopus tropicalis have historically been outstanding model systems for embryology and cell biology, with emerging utility as highly accessible embryos for genome-wide studies. here we focus on the particular strengths and limitations of xenopus cell biology and g ...201424064036
retinoic acid homeostasis regulates meiotic entry in developing anuran gonads and in bidder's organ through raldh2 and cyp26b1 proteins.the vitamin a (retinol) and its metabolites such as retinoic acid (ra) affect vertebrate gametogenesis. the level of ra in cells relies on the balance between its synthesis and degradation. the sex-dependent equilibrium is reached in different ways in various species. it is known that ra induces meiosis in developing gonads in mouse, chicken and urodel amphibians, but its role in anuran amphibians has not been studied. here we show in six anuran species (xenopus laevis, bombina bombina, hyla arb ...201624056063
identification and evolution of molecular domains involved in differentiating the cement gland-promoting activity of otx proteins in xenopus laevis.otx genes are a class of vertebrate homeobox genes, homologous to the orthodenticle gene of drosophila melanogaster, that play a crucial role in anterior embryo patterning and sensory organ formation. in the frog, xenopus laevis, at least three members of this class have been isolated: otx1, otx2 and otx5 (crx); they are involved in regulating both shared and differential processes during frog development. in particular, while otx2 and otx5 are both capable to promote cement gland (cg) formation ...201324056062
paf and ezh2 induce wnt/β-catenin signaling hyperactivation.fine control of wnt signaling is essential for various cellular and developmental decision-making processes. however, deregulation of wnt signaling leads to pathological consequences, one of which is cancer. here, we identify a function of paf, a component of translesion dna synthesis, in modulating wnt signaling. paf is specifically overexpressed in colon cancer cells and intestinal stem cells and is required for colon cancer cell proliferation. in xenopus laevis, ventrovegetal expression of pa ...201324055345
morpholino studies in xenopus brain development.antisense morpholino oligonucleotides (mos) have become a valuable method to knock down protein levels, to block mrna splicing, and to interfere with mirna function. mos are widely used to alter gene expression during development of xenopus and zebra fish, where they are typically injected into the fertilized egg or blastomeres. here, we present methods to use electroporation to target delivery of mos to the central nervous system of xenopus laevis or xenopus tropicalis tadpoles. briefly, mo ele ...201424048933
hydrostatic pressure activates atp-sensitive k+ channels in lung epithelium by atp release through pannexin and connexin hemichannels.lungs of air-breathing vertebrates are constantly exposed to mechanical forces and therefore are suitable for investigation of mechanotransduction processes in nonexcitable cells and tissues. freshly dissected xenopus laevis lungs were used for transepithelial short-circuit current (isc) recordings and were exposed to increased hydrostatic pressure (hp; 5 cm fluid column, modified ussing chamber). i(sc) values obtained under hp (i(5cm)) were normalized to values before hp (i(0cm)) application (i ...201424048216
the nedd4-binding protein 3 (n4bp3) is crucial for axonal and dendritic branching in developing neurons.circuit formation in the nervous system essentially relies on the proper development of neurons and their processes. in this context, the ubiquitin ligase nedd4 is a crucial modulator of axonal and dendritic branching.201324044555
tuning voltage-gated channel activity and cellular excitability with a sphingomyelinase.voltage-gated ion channels generate action potentials in excitable cells and help set the resting membrane potential in nonexcitable cells like lymphocytes. it has been difficult to investigate what kinds of phospholipids interact with these membrane proteins in their native environments and what functional impacts such interactions create. this problem might be circumvented if we could modify specific lipid types in situ. using certain voltage-gated k(+) (kv) channels heterologously expressed i ...201324043861
early evolution of the t-box transcription factor family.developmental transcription factors are key players in animal multicellularity, being members of the t-box family that are among the most important. until recently, t-box transcription factors were thought to be exclusively present in metazoans. here, we report the presence of t-box genes in several nonmetazoan lineages, including ichthyosporeans, filastereans, and fungi. our data confirm that brachyury is the most ancient member of the t-box family and establish that the t-box family diversifie ...201324043797
n-terminal serine dephosphorylation is required for kcc3 cotransporter full activation by cell swelling.the k(+):cl(-) cotransporter (kcc) activity is modulated by phosphorylation/dephosphorylation processes. in isotonic conditions, kccs are inactive and phosphorylated, whereas hypotonicity promotes their dephosphorylation and activation. two phosphorylation sites (thr-991 and thr-1048) in kcc3 have been found to be critical for its regulation. however, here we show that the double mutant kcc3-t991a/t1048a could be further activated by hypotonicity, suggesting that additional phosphorylation site( ...201324043619
characterization of the nutritional endoderm in the direct developing frog eleutherodactylus coqui.unlike xenopus laevis, eleutherodactylus coqui develops without a tadpole. the yolk-rich vegetal region of the embryo forms a transient nutritive tissue, the nutritional endoderm (ne). the definitive endoderm (de) in e. coqui comes from cells closer to the animal pole in contrast to its vegetal origin in x. laevis. rna important for initiating the endoderm specification network is absent in presumptive ne cells, raising the question whether signaling occurs in them. we explored the nature of ne ...201324043604
the poz-zf transcription factor kaiso (zbtb33) induces inflammation and progenitor cell differentiation in the murine intestine.since its discovery, several studies have implicated the poz-zf protein kaiso in both developmental and tumorigenic processes. however, most of the information regarding kaiso's function to date has been gleaned from studies in xenopus laevis embryos and mammalian cultured cells. to examine kaiso's role in a relevant, mammalian organ-specific context, we generated and characterized a kaiso transgenic mouse expressing a murine kaiso transgene under the control of the intestine-specific villin pro ...201324040197
rab8b is required for activity and caveolar endocytosis of lrp6.wnt/β-catenin signaling plays an important role in embryonic development and adult tissue homeostasis. when wnt ligands bind to the receptor complex, lrp5/6 coreceptors are activated by phosphorylation and concomitantly endocytosed. in vertebrates, wnt ligands induce caveolin-dependent endocytosis of lrp6 to relay signal downstream, whereas antagonists such as dickkopf promote clathrin-dependent endocytosis, leading to inhibition. however, little is known about how lrp6 is directed to different ...201324035388
overexpression of the vacuolar sugar carrier atsweet16 modifies germination, growth, and stress tolerance in arabidopsis.here, we report that sugars will eventually be exported transporter (sweet16) from arabidopsis (arabidopsis thaliana) is a vacuole-located carrier, transporting glucose (glc), fructose (fru), and sucrose (suc) after heterologous expression in xenopus laevis oocytes. the sweet16 gene, similar to the homologs gene sweet17, is mainly expressed in vascular parenchyma cells. application of glc, fru, or suc, as well as cold, osmotic stress, or low nitrogen, provoke the down-regulation of sweet16 messe ...201324028846
c-jun n-terminal kinase phosphorylation of heterogeneous nuclear ribonucleoprotein k regulates vertebrate axon outgrowth via a posttranscriptional mechanism.c-jun n-terminal kinase (jnk) mediates cell signaling essential for axon outgrowth, but the associated substrates and underlying mechanisms are poorly understood. we identified in xenopus laevis embryos a novel posttranscriptional mechanism whereby jnk regulates axonogenesis by phosphorylating a specific site on heterogeneous nuclear ribonucleoprotein k (hnrnp k). both jnk inhibition and hnrnp k knockdown inhibited axon outgrowth and translation of hnrnp k-regulated cytoskeletal rnas (tau and ne ...201324027268
coco regulates dorsoventral specification of germ layers via inhibition of tgfβ signalling.one of the earliest steps in embryonic development is the specification of the germ layers, the subdivision of the blastula embryo into endoderm, mesoderm and ectoderm. maternally expressed members of the transforming growth factor β (tgfβ) family influence all three germ layers; the ligands are required to induce endoderm and mesoderm, whereas inhibitors are required for formation of the ectoderm. here, we demonstrate a vital role for maternal coco, a secreted antagonist of tgfβ signalling, in ...201324026124
studying epigenetic dna modifications in undergraduate laboratories using complementary bioinformatic and molecular approaches.epigenetic inheritance is the inheritance of genetic information that is not based on dna sequence alone. one type of epigenetic information that has come to the forefront in the last few years is modified dna bases. the most common modified dna base in nature is 5-methylcytosine. herein, we describe a laboratory experiment that combines bioinformatic and molecular approaches to study the presence and abundance of 5-methylcytosine in different organisms. students were originally provided with th ...201324022990
planar cell polarity proteins differentially regulate extracellular matrix organization and assembly during zebrafish gastrulation.zebrafish gastrulation cell movements occur in the context of dynamic changes in extracellular matrix (ecm) organization and require the concerted action of planar cell polarity (pcp) proteins that regulate cell elongation and mediolateral alignment. data obtained using xenopus laevis gastrulae have shown that integrin-fibronectin interactions underlie the formation of polarized cell protrusions necessary for pcp and have implicated pcp proteins themselves as regulators of ecm. by contrast, the ...201324021482
identification of cysteine residues in human cationic amino acid transporter hcat-2a that are targets for inhibition by n-ethylmaleimide.in most cells, cationic amino acids such as l-arginine, l-lysine, and l-ornithine are transported by cationic (cat) and y(+)l (y(+)lat) amino acid transporters. in human erythrocytes, the cysteine-modifying agent n-ethylmaleimide (nem) has been shown to inhibit system y(+) (most likely cat-1), but not system y(+)l (devés, r., angelo, s., and chávez, p. (1993) j. physiol. 468, 753-766). we thus wondered if sensitivity to nem distinguishes generally all cat and y(+)lat isoforms. transport assays i ...201324019517
functional assays for insect olfactory receptors in xenopus oocytes.reconstitution of olfactory or pheromone receptors in heterologous expression systems greatly facilitates the functional analysis of these receptors. xenopus laevis oocytes can be used to efficiently express insect olfactory or pheromone receptors. in this chapter, we describe how to use xenopus laevis oocytes for functional assays of insect olfactory receptors. the procedure can be subdivided into the four following steps: (1) in vitro complementary rna (crna) synthesis, (2) isolation of oocyte ...201324014357
phytochemical profiling of curcuma kwangsiensis rhizome extract, and identification of labdane diterpenoids as positive gabaa receptor modulators.an ethyl acetate extract of curcuma kwangsiensis s.g. lee & c.f. liang (zingiberaceae) rhizomes (100 μg/ml) enhanced the gaba-induced chloride current (igaba) through gabaa receptors of the α1β2γ2s subtype by 79.0±7.0%. potentiation of igaba was measured using the two-microelectrode voltage-clamp technique and xenopus laevis oocytes. hplc-based activity profiling of the crude extract led to the identification of 11 structurally related labdane diterpenoids, including four new compounds. structur ...201324011802
two phloem nitrate transporters, nrt1.11 and nrt1.12, are important for redistributing xylem-borne nitrate to enhance plant growth.this study of the arabidopsis (arabidopsis thaliana) nitrate transporters nrt1.11 and nrt1.12 reveals how the interplay between xylem and phloem transport of nitrate ensures optimal nitrate distribution in leaves for plant growth. functional analysis in xenopus laevis oocytes showed that both nrt1.11 and nrt1.12 are low-affinity nitrate transporters. quantitative reverse transcription-polymerase chain reaction and immunoblot analysis showed higher expression of these two genes in larger expanded ...201324006285
the xenopus amygdala mediates socially appropriate vocal communication signals.social interaction requires that relevant sensory information is collected, classified, and distributed to the motor areas that initiate an appropriate behavioral response. vocal exchanges, in particular, depend on linking auditory processing to an appropriate motor expression. because of its role in integrating sensory information for the purpose of action selection, the amygdala has been implicated in social behavior in many mammalian species. here, we show that two nuclei of the extended amyg ...201324005304
procaine, a state-dependent blocker, inhibits herg channels by helix residue y652 and f656 in the s6 transmembrane domain.the article evaluated the inhibitory action of procaine on wild-type and mutated herg potassium channel current (i(herg)) to determine whether mutations in the s6 region are important for the inhibition of i(herg) by procaine. herg channels (wt, y652a, and f656a) were expressed in xenopus laevis oocytes and studied using the standard two-microelectrode voltage-clamp technique. the results revealed that wt herg is blocked in a concentration-, voltage-, and state-dependent manner by procaine ([ic₅ ...201324005047
in vivo time-lapse imaging of neuronal development in xenopus.in vivo fluorescence imaging of cells in the developing nervous system is greatly facilitated in specimens in which cells are brightly but sparsely labeled. in this article, we describe a number of techniques that can be used for delivering fluorophore to neurons in the albino xenopus laevis tadpole. fluorescent dye or dna that encodes a fluorescent protein can be delivered to single cells by electroporation. alternatively, multiple cells can be labeled with fluorescent dye introduced by local i ...201324003201
rilpivirine inhibits drug transporters abcb1, slc22a1, and slc22a2 in vitro.rilpivirine is a nonnucleoside reverse transcriptase inhibitor approved for treatment of hiv-1 infection in antiretroviral-naive adult patients. potential interactions with drug transporters have not been fully investigated. transport by and inhibition of drug transporters by rilpivirine were analyzed to further understand the mechanisms governing rilpivirine exposure and determine the potential for transporter-mediated drug-drug interactions. the ability of rilpivirine to inhibit or be transpor ...201324002095
analysis of oxygen affinity in aquatic amphibian; homology modelling of the major haemoglobin component hba1 from the african clawed frog (xenopus laevis, anura).the homology model of major haemoglobin component hba1 of the african clawed frog was predicted using the pigeon (columba livia) haemoglobin as a template. the model was built with the help of modeller9v8. the models were evaluated with prosa and procheck. in x. laevis gln38α is unable to form a hydrogen bond with β97his or β99asp, which is responsible for the increase in oxygen affinity of the xenopus hba1. the hydrogen bond between α34thr and β124pro, which stabilises the deoxy state of the ha ...201324001722
monna, a potent and selective blocker for transmembrane protein with unknown function 16/anoctamin-1.transmembrane protein with unknown function 16/anoctamin-1 (ano1) is a protein widely expressed in mammalian tissues, and it has the properties of the classic calcium-activated chloride channel (cacc). this protein has been implicated in numerous major physiological functions. however, the lack of effective and selective blockers has hindered a detailed study of the physiological functions of this channel. in this study, we have developed a potent and selective blocker for endogenous ano1 in xen ...201323997117
a nuclear f-actin scaffold stabilizes ribonucleoprotein droplets against gravity in large cells.the size of a typical eukaryotic cell is of the order of ∼10 μm. however, some cell types grow to very large sizes, including oocytes (immature eggs) of organisms from humans to starfish. for example, oocytes of the frog xenopus laevis grow to a diameter ≥1 mm. they have a correspondingly large nucleus (germinal vesicle) of ∼450 μm in diameter, which is similar to smaller somatic nuclei, but contains a significantly higher concentration of actin. the form and structure of this nuclear actin rema ...201323995731
irt1 degradation factor1, a ring e3 ubiquitin ligase, regulates the degradation of iron-regulated transporter1 in arabidopsis.fe is an essential micronutrient for plant growth and development; plants have developed sophisticated strategies to acquire ferric fe from the soil. nongraminaceous plants acquire fe by a reduction-based mechanism, and graminaceous plants use a chelation-based mechanism. in arabidopsis thaliana, which uses the reduction-based method, iron-regulated transporter1 (irt1) functions as the most important transporter for ferrous fe uptake. rapid and constitutive degradation of irt1 allows plants to q ...201323995086
d-amino acid oxidase and presence of d-proline in xenopus laevis.we purified d-amino acid oxidase (ec 1.4.3.3, dao) from xenopus laevis tadpoles. the optimal temperature and ph for enzyme activity were 35-40 °c and 8.3-9.0, respectively, depending on the substrate amino acids available to the enzyme; the highest activity was observed with d-proline followed by d-phenylalanine. activity was significantly inhibited by p-hydroxymercuribenzoate, but only moderately by p-chloromercuribenzoate or benzoate. enzyme activity was increased until the final tadpole stage ...201323994361
propofol modulation of α1 glycine receptors does not require a structural transition at adjacent subunits that is crucial to agonist-induced activation.pentameric glycine receptors (glyrs) couple agonist binding to activation of an intrinsic ion channel. substitution of the r271 residue impairs agonist-induced activation and is associated with the human disease hyperekplexia. on the basis of a homology model of the α1 glyr, we substituted residues in the vicinity of r271 with cysteines, generating r271c, q226c, and d284c single-mutant glyrs and r271c/q226c and r271c/d284c double-mutant glyrs. we then examined the impact of interactions between ...201323992940
control of dna replication by the nucleus/cytoplasm ratio in xenopus.the nucleus/cytoplasm (n/c) ratio controls s phase dynamics in many biological systems, most notably the abrupt remodeling of the cell cycle that occurs at the midblastula transition in early xenopus laevis embryos. after an initial series of rapid cleavage cycles consisting only of s and m phases, a critical n/c ratio is reached, which causes a sharp increase in the length of s phase as the cell cycle is reconfigured to resemble somatic cell cycles. how the n/c ratio determines the length of s ...201323986447
attenuation of bone morphogenetic protein signaling during amphibian limb development results in the generation of stage-specific defects.the vertebrate limb is one of the most intensively studied organs in the field of developmental biology. limb development in tetrapod vertebrates is highly conserved and dependent on the interaction of several important molecular pathways. the bone morphogenetic protein (bmp) signaling cascade is one of these pathways and has been shown to be crucial for several aspects of limb development. here, we have used a xenopus laevis transgenic line, in which expression of the inhibitor noggin is under ...201323981117
xmap215 activity sets spindle length by controlling the total mass of spindle microtubules.metaphase spindles are microtubule-based structures that use a multitude of proteins to modulate their morphology and function. today, we understand many details of microtubule assembly, the role of microtubule-associated proteins, and the action of molecular motors. ultimately, the challenge remains to understand how the collective behaviour of these nanometre-scale processes gives rise to a properly sized spindle on the micrometre scale. by systematically engineering the enzymatic activity of ...201323974040
physiological concentrations of zinc reduce taurine-activated glyr responses to drugs of abuse.taurine is an endogenous ligand acting on glycine receptors in many brain regions, including the hippocampus, prefrontal cortex, and nucleus accumbens (nacc). these areas also contain low concentrations of zinc, which is known to potentiate glycine receptor responses. despite an increasing awareness of the role of the glycine receptor in the rewarding properties of drugs of abuse, the possible interactions of these compounds with zinc has not been thoroughly addressed. two-electrode voltage-clam ...201323973295
comparative studies of apoptosis in xenopus laevis and mouse thymoma cell lines.with the use of in vitro methods and cell lines, functional aspects of apoptosis in the xenopus laevis b3/b7 and mouse el4 thymoma cell lines are revealed. moreover, by using information gleaned from digital imaging and immunocytochemistry, changes in locations of key proteins implicated in apoptotic anti-cancer responses, e.g. p53 and mdm2, are shown. suggestions are offered as to what these results might mean with respect to the evolutionary conservation of the function and structure of these ...201323971701
expression profiling of intestinal tissues implicates tissue-specific genes and pathways essential for thyroid hormone-induced adult stem cell development.the study of the epithelium during development in the vertebrate intestine touches upon many contemporary aspects of biology: to name a few, the formation of the adult stem cells (ascs) essential for the life-long self-renewal and the balance of stem cell activity for renewal vs cancer development. although extensive analyses have been carried out on the property and functions of the adult intestinal stem cells in mammals, little is known about their formation during development due to the diffi ...201323970787
molecular crowding drives active pin1 into nonspecific complexes with endogenous proteins prior to substrate recognition.proteins and nucleic acids maintain the crowded interior of a living cell and can reach concentrations in the order of 200-400 g/l which affects the physicochemical parameters of the environment, such as viscosity and hydrodynamic as well as nonspecific strong repulsive and weak attractive interactions. dynamics, structure, and activity of macromolecules were demonstrated to be affected by these parameters. however, it remains controversially debated, which of these factors are the dominant caus ...201323968199
signals governing the trafficking and mistrafficking of a ciliary gpcr, rhodopsin.rhodopsin is a cilia-specific gpcr essential for vision. rhodopsin mislocalization is associated with blinding diseases called retinal ciliopathies. the mechanism by which rhodopsin mislocalizes in rod photoreceptor neurons is not well understood. therefore, we investigated the roles of trafficking signals in rhodopsin mislocalization. rhodopsin and its truncation mutants were fused to a photoconvertible fluorescent protein, dendra2, and expressed in xenopus laevis rod photoreceptors. photoconve ...201323966685
coarse architecture of the transient receptor potential vanilloid 1 (trpv1) ion channel determined by fluorescence resonance energy transfer.the transient receptor potential vanilloid 1 ion channel is responsible for the perception of high temperatures and low extracellular ph, and it is also involved in the response to some pungent compounds. importantly, it is also associated with the perception of pain and noxious stimuli. here, we attempt to discern the molecular organization and location of the n and c termini of the transient receptor potential vanilloid 1 ion channel by measuring fret between genetically attached enhanced yell ...201323965996
menthol inhibits 5-ht3 receptor-mediated currents.the effects of alcohol monoterpene menthol, a major active ingredient of the peppermint plant, were tested on the function of human 5-hydroxytryptamine type 3 (5-ht3) receptors expressed in xenopus laevis oocytes. 5-ht (1 μm)-evoked currents recorded by two-electrode voltage-clamp technique were reversibly inhibited by menthol in a concentration-dependent (ic50 = 163 μm) manner. the effects of menthol developed gradually, reaching a steady-state level within 10-15 minutes and did not involve g-p ...201323965380
[the obtaining and analysis of physiological activity of secreted proteins of noggin family].we have developed methods for producing recombinant proteins of noggin family (noggin1 and noggin2 of the xenopus laevis frog) that can interact with bmp factors of tgf-beta superfamily. the genetic constructs which allow one to effectively obtain noggin1 and noggin2 from synthetic mrna microinjected into xenopus laevis early embryos, as well as in the prokaryotic expression system, were generated. the obtained proteins contain three myc-tag epitopes on their n-terminus. this allow one to compar ...201323964527
conformational changes represent the rate-limiting step in the transport cycle of maize sucrose transporter1.proton-driven suc transporters allow phloem cells of higher plants to accumulate suc to more than 1 m, which is up to ~1000-fold higher than in the surrounding extracellular space. the carrier protein can accomplish this task only because proton and suc transport are tightly coupled. this study provides insights into this coupling by resolving the first step in the transport cycle of the suc transporter sut1 from maize (zea mays). voltage clamp fluorometry measurements combining electrophysiolog ...201323964025
unliganded thyroid hormone receptor regulates metamorphic timing via the recruitment of histone deacetylase complexes.anuran metamorphosis involves a complex series of tissue transformations that change an aquatic tadpole to a terrestrial frog and resembles the postembryonic perinatal period in mammals. thyroid hormone (th) plays a causative role in amphibian metamorphosis and its effect is mediated by th receptors (trs). molecular analyses during xenopus development have shown that unliganded tr recruits histone deacetylase (hdac)-containing n-cor/smrt complexes and causes histone deacetylation at target genes ...201323962846
differential modulation of brain nicotinic acetylcholine receptor function by cytisine, varenicline, and two novel bispidine compounds: emergent properties of a hybrid molecule.partial agonist therapies for the treatment of nicotine addiction and dependence depend on both agonistic and antagonistic effects of the ligands, and side effects associated with other nachrs greatly limit the efficacy of nicotinic partial agonists. we evaluated the in vitro pharmacological properties of four partial agonists, two current smoking cessation drugs, varenicline and cytisine, and two novel bispidine compounds, bpc and bmsp, by using defined nachr subtypes expressed in xenopus laevi ...201323959137
dehydration mediated microrna response in the african clawed frog xenopus laevis.exposure to various environmental stresses induces metabolic rate depression in many animal species, an adaptation that conserves energy until the environment is again conducive to normal life. the african clawed frog, xenopus laevis, is periodically subjected to arid summers in south africa, and utilizes entry into the hypometabolic state of estivation as a mechanism of long term survival. during estivation, frogs must typically deal with substantial dehydration as their ponds dry out and x. la ...201323958654
site directed mutagenesis of stsut1 reveals target amino acids of regulation and stability.plant sucrose transporters (suts) are functional as sucrose-proton-cotransporters with an optimal transport activity in the acidic ph range. recently, the ph optimum of the solanum tuberosum sucrose transporter stsut1 was experimentally determined to range at an unexpectedly low ph of 3 or even below. various research groups have confirmed these surprising findings independently and in different organisms. here we provide further experimental evidence for a ph optimum at physiological extrema. s ...201323954800
vestibular lesion-induced developmental plasticity in spinal locomotor networks during xenopus laevis metamorphosis.during frog metamorphosis, the vestibular sensory system remains unchanged, while spinal motor networks undergo a massive restructuring associated with the transition from the larval to adult biomechanical system. we investigated in xenopus laevis the impact of a pre- (tadpole stage) or post-metamorphosis (juvenile stage) unilateral labyrinthectomy (ul) on young adult swimming performance and underlying spinal locomotor circuitry. the acute disruptive effects on locomotion were similar in both t ...201323951071
novel dicarboxylate selectivity in an insect glutamate transporter homolog.mammals express seven transporters from the slc1 (solute carrier 1) gene family, including five acidic amino acid transporters (eaat1-5) and two neutral amino acid transporters (asct1-2). in contrast, insects of the order diptera possess only two slc1 genes. in this work we show that in the mosquito culex quinquefasciatus, a carrier of west nile virus, one of its two slc1 eaat-like genes encodes a transporter that displays an unusual selectivity for dicarboxylic acids over acidic amino acids. in ...201323951049
acr-23 encodes a monepantel-sensitive channel in caenorhabditis elegans.monepantel is a member of the recently identified class of anthelmintics known as the amino-acetonitrile derivatives (aads). monepantel controls all major gastro-intestinal nematodes in sheep including those that are resistant to the classical anthelmintics. previous studies have shown that the caenorhabditis elegans acr-23 and the haemonchus contortus hco-mptl-1 genes may be prominent targets of monepantel. with this discovery it became possible to investigate the mode of action of monepantel i ...201323950710
nonclassical mhc class i-dependent invariant t cells are evolutionarily conserved and prominent from early development in amphibians.human and murine mhc nonclassical class ib-restricted invariant t (it) cell subsets, such as invariant natural killer t cells (inkt) and mucosal-associated invariant t cells, have specialized functions early in immune responses, especially in modulating subsequent adaptive immune responses. here, we characterize a prominent it population in the amphibian xenopus laevis and show the requirement of the class ib molecule, xenopus nonclassical gene 10, in its differentiation and function. using xeno ...201323940320
the severe autosomal dominant retinitis pigmentosa rhodopsin mutant ter349glu mislocalizes and induces rapid rod cell death.mutations in the rhodopsin gene cause approximately one-tenth of retinitis pigmentosa cases worldwide, and most result in endoplasmic reticulum retention and apoptosis. other rhodopsin mutations cause receptor mislocalization, diminished/constitutive activity, or faulty protein-protein interactions. the purpose of this study was to test for mechanisms by which the autosomal dominant rhodopsin mutation ter349glu causes an early, rapid retinal degeneration in patients. the mutation adds an additio ...201323940033
expression and functional characterization of xhmg-at-hook genes in xenopus laevis.high mobility group a proteins (hmga1 and hmga2) are architectural nuclear factors involved in development, cell differentiation, and cancer formation and progression. here we report the cloning, developmental expression and functional analysis of a new multi-at-hook factor in xenopus laevis (xhmg-at-hook) that exists in three different isoforms. xhmg-at-hook1 and 3 isoforms, but not isoform 2, are expressed throughout the entire development of xenopus, both in the maternal and zygotic phase. lo ...201323936116
crucial residue involved in l-lactate recognition by human monocarboxylate transporter 4 (hmct4).monocarboxylate transporters (mcts) transport monocarboxylates such as lactate, pyruvate and ketone bodies. these transporters are very attractive therapeutic targets in cancer. elucidations of the functions and structures of mcts is necessary for the development of effective medicine which targeting these proteins. however, in comparison with mct1, there is little information on location of the function moiety of mct4 and which constituent amino acids govern the transport function of mct4. the ...201323935841
characterization of monocarboxylate transporter 6: expression in human intestine and transport of the antidiabetic drug nateglinide.monocarboxylate transporter (mct) 6, encoded by slc16a5, is a member of the monocarboxylate transporter family. nateglinide, an oral hypoglycemic agent, quickly reaches the maximal serum concentration after its premeal administration. although the functional existence of uptake systems for nateglinide in the intestine has been demonstrated, these transport systems have not yet been identified at the molecular level. the aim of this study was to demonstrate the localization of mct6 in the human s ...201323935065
development: scaling to size by protease inhibition.the dorsal half of bisected xenopus laevis embryos can regenerate a well-proportioned organism on a smaller scale. a new study indicates that the removal of ventral tissue generates a steeper chordin gradient by reducing sizzled, a secreted inhibitor of tolloid chordinases.201323928082
enhanced hsp30 and hsp70 accumulation in xenopus cells subjected to concurrent sodium arsenite and cadmium chloride stress.heat shock proteins (hsps) are molecular chaperones that aid in protein folding, translocation and in preventing stress-induced protein aggregation. the present study examined the effect of simultaneous sodium arsenite and cadmium chloride treatment on the pattern of hsp30 and hsp70 accumulation in a6 kidney epithelial cells of the frog, xenopus laevis. immunoblot analysis revealed that hsp30 and hsp70 accumulation in concurrent stressor treatments were significantly higher than the sum of hsp30 ...201323919948
blastocoel-spanning filopodia in cleavage-stage xenopus laevis: potential roles in morphogen distribution and detection.in the frog xenopus laevis, dorsal-ventral axis specification involves cytoskeleton-dependent transport of localized transcripts and proteins during the first cell cycle, and activation of the canonical wnt pathway to locally stabilize translated beta-catenin which, by as early as the 32-cell stage, commits nuclei in prospective dorsal lineages to the subsequent expression of dorsal target genes. maternal ligands important for activating this dorsal-specific signaling pathway are thought to inte ...201323916849
titration of four replication factors is essential for the xenopus laevis midblastula transition.the rapid, reductive early divisions of many metazoan embryos are followed by the midblastula transition (mbt), during which the cell cycle elongates and zygotic transcription begins. it has been proposed that the increasing nuclear to cytoplasmic (n/c) ratio is critical for controlling the events of the mbt. we show that four dna replication factors--cut5, recq4, treslin, and drf1--are limiting for replication initiation at increasing n/c ratios in vitro and in vivo in xenopus laevis. the level ...201323907533
effects of perfluorooctanesulfonate and perfluorobutanesulfonate on the growth and sexual development of xenopus laevis.perfluorobutanesulfonate (pfbs), as a substitute for perfluorooctanesulfonate (pfos), is widespread in the environment and biotic samples as well as pfos. to investigate effects of pfos and pfbs on the growth and sexual development of amphibians, we exposed xenopus laevis tadpoles at a series of concentrations of pfos and pfbs (0.1; 1; 100; 1,000 μg/l) as well as 17-beta-estradiol (e2, 100 ng/l) and 5 alpha-androstan-17-beta-ol-3-one (dht, 100 ng/l) from stage 46/47 to 2 months postmetamorphosis ...201323907449
the phosphoinositide sensitivity of the k(v) channel family.recently, we screened several kv channels for possible dependence on plasma membrane phosphatidylinositol 4,5-bisphosphate (pi(4,5)p 2). the channels were expressed in tsa-201 cells and the pi(4,5)p 2 was depleted by several manipulations in whole-cell experiments with parallel measurements of channel activity. in contrast to reports on excised-patches using xenopus laevis oocytes, we found only kv 7, but none of the other tested kv channels, to be strongly dependent on pi(4,5)p 2. we now have e ...201723907203
bulk electroporation of retinal ganglion cells in live xenopus tadpoles.individual neurons in the developing nervous system of xenopus laevis can be visualized by the targeted delivery of a fluorophore. the fluorophore can be delivered as a fluorescent dye or dna that encodes a fluorescent protein. local iontophoresis is a method that works well for transfer of fluorescent dye to retinal ganglion cells (rgcs) in the eye, but it does not give a high yield for delivery of dna. this is largely because the degree of pigmentation of the eyes, even in albino strains, make ...201323906915
dye labeling retinal ganglion cell axons in live xenopus tadpoles.individual neurons in the developing nervous system can be visualized by the targeted delivery of a fluorophore. in this article, we describe a method for introducing a fluorescent dye via iontophoresis into retinal ganglion cell (rgc) axons in albino xenopus laevis tadpoles. iontophoresis is the enhanced permeation of molecules across biological membranes under the influence of an electrical field. lipophilic dyes such as dii are well suited to this method--being insoluble in the aqueous enviro ...201323906914
ontogenesis of the extra-bulbar olfactory pathway in xenopus laevis.although the development, anatomy, and physiology of the vertebrate olfactory system are fairly well understood, there is still no clear definition of the terminal nerve complex acknowledged by all. among the most debated matters is whether or not the extrabulbar projections found in anamniotes should or should not be considered part of the terminal nerve complex. in this context, we investigated the early development of the extrabulbar pathway in xenopus larvae from placodal differentiation to ...201323904212
an externally accessible linker region in the sodium-coupled phosphate transporter pit-1 (slc20a1) is important for transport function.members of the slc20 cotransporter family (pit-1, pit-2) are ubiquitously expressed in mammalian tissue and are thought to perform housekeeping functions for intracellular pi homeostasis as well as being implicated in vascular calcification and renal pi reabsorption. the aims of this study were to investigate the topology of a linker region in pit-1 between the predicted 2(nd) and 3(rd) transmembrane domains and to investigate the functional consequences of cysteine substitutions in this region.201323899881
neurotoxic unc-8 mutants encode constitutively active deg/enac channels that are blocked by divalent cations.ion channels of the deg/enac family can induce neurodegeneration under conditions in which they become hyperactivated. the caenorhabditis elegans deg/enac channel mec-4(d) encodes a mutant channel with a substitution in the pore domain that causes swelling and death of the six touch neurons in which it is expressed. dominant mutations in the c. elegans deg/enac channel subunit unc-8 result in uncoordinated movement. here we show that this unc-8 movement defect is correlated with the selective de ...201323898007
peptidomic analysis of skin secretions provides insight into the taxonomic status of the african clawed frogs xenopus victorianus and xenopus laevis sudanensis (pipidae).peptidomic analysis was used to compare the distribution of host-defense peptides in norepinephrine-stimulated skin secretions from xenopus victorianusahl, 1924 (also described as the subspecies x. laevis victorianus) and xenopus laevis sudanensisperret, 1966 with the previously determined distributions in xenopus laevis (daudin, 1802) and xenopus petersii bocage, 1895. peptides belonging to the magainin, peptide glycine-leucine-amide (pgla), and caerulein precursor fragment (cpf) families were ...201323896465
the structure and development of xenopus laevis cornea.the african clawed frog, xenopus laevis, is a widely used model organism for tissue development. we have followed the process of corneal development closely in xenopus and examined the corneal ultrastructure at each stage during its formation. xenopus cornea development starts at stage 25 from a simple embryonic epidermis overlying the developing optic vesicle. after detachment of the lens placode which takes place around stage 30, cranial neural crest cells start to invade the space between the ...201323896054
bcstx3 is a founder of a novel sea anemone toxin family of potassium channel blocker.sea anemone venoms have become a rich source of peptide toxins which are invaluable tools for studying the structure and functions of ion channels. in this work, bcstx3, a toxin found in the venom of a bunodosoma caissarum (population captured at the saint peter and saint paul archipelago, brazil) was purified and biochemically and pharmacologically characterized. the pharmacological effects were studied on 12 different subtypes of voltage-gated potassium channels (k(v)1.1-k(v)1.6; k(v)2.1; k(v) ...201323895459
mcm10 self-association is mediated by an n-terminal coiled-coil domain.minichromosome maintenance protein 10 (mcm10) is an essential eukaryotic dna-binding replication factor thought to serve as a scaffold to coordinate enzymatic activities within the replisome. mcm10 appears to function as an oligomer rather than in its monomeric form (or rather than as a monomer). however, various orthologs have been found to contain 1, 2, 3, 4, or 6 subunits and thus, this issue has remained controversial. here, we show that self-association of xenopus laevis mcm10 is mediated b ...201323894664
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