Publications

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INOH: ontology-based highly structured database of signal transduction pathways.The Integrating Network Objects with Hierarchies (INOH) database is a highly structured, manually curated database of signal transduction pathways including Mammalia, Xenopus laevis, Drosophila melanogaster, Caenorhabditis elegans and canonical. Since most pathway knowledge resides in scientific articles, the database focuses on curating and encoding textual knowledge into a machine-processable form. We use a hierarchical pathway representation model with a compound graph, and every pathway comp ...201122120663
tbx5 overexpression favors a first heart field lineage in murine embryonic stem cells and in xenopus laevis embryos.the t-box transcription factor tbx5 is involved in several developmental processes including cardiogenesis. early steps of cardiac development are characterised by the formation of two cardiogenic lineages, the first (fhf) and the second heart field (shf) lineage, which arise from a common cardiac progenitor cell population. to further investigate the function of tbx5 during cardiogenesis, we generated a murine embryonic stem cell line constitutively overexpressing tbx5. differentiation of these ...201122072574
improved knockout methodology reveals that frog virus 3 mutants lacking either the 18k immediate-early gene or the truncated vif-2alpha gene are defective for replication and growth in vivo.to better assess the roles of frog virus 3 (fv3; genus ranavirus, family iridoviridae) genes in virulence and immune evasion, we have developed a reliable and efficient method to systematically knock out (ko) putative virulence genes by site-specific integration into the fv3 genome. our approach utilizes a dual selection marker consisting of the puromycin resistance gene fused in frame with the enhanced green fluorescent protein (egfp) reporter (puro-egfp cassette) under the control of the fv3 i ...201121865381
nitric oxide as a putative retinal axon pathfinding and target recognition cue in xenopus laevis.nitric oxide (no) is an atypical neurotransmitter synthesized by the enzyme nitric oxide synthase (nos) during many stages of the xenopus laevis life cycle. this research investigates whether the gas no is involved in axon guidance, the neurodevelopmental process in which axons travel through the brain to their appropriate target locations to form functional neural circuitry. through immunocytochemistry and direct labeling of the no gas with a fluorescent dye, we have found that nos expression c ...201121847432
discovery, characterization, and structure-activity relationships of an inhibitor of inward rectifier potassium (kir) channels with preference for kir2.3, kir3.x, and kir7.1.the inward rectifier family of potassium (kir) channels is comprised of at least 16 family members exhibiting broad and often overlapping cellular, tissue, or organ distributions. the discovery of disease-causing mutations in humans and experiments on knockout mice has underscored the importance of kir channels in physiology and in some cases raised questions about their potential as drug targets. however, the paucity of potent and selective small-molecule modulators targeting specific family me ...201122275899
Targeting of mouse guanylate cyclase 1 (Gucy2e) to Xenopus laevis rod outer segments.Photoreceptor guanylate cyclase (GC1) is a transmembrane protein and responsible for synthesis of cGMP, the secondary messenger of phototransduction. It consists of an extracellular domain, a single transmembrane domain, and an intracellular domain. It is unknown how GC1 targets to the outer segments where it resides. To identify a putative GC1 targeting signal, we generated a series of peripheral membrane and transmembrane constructs encoding extracellular and intracellular mouse GC1 fragments ...201121945483
aquaporin 4 is a ubiquitously expressed isoform in the dogfish (squalus acanthias) shark.the dogfish ortholog of aquaporin 4 (aqp4) was amplified from cdna using degenerate pcr followed by cloning and sequencing. the complete coding region was then obtained using 5' and 3' race techniques. alignment of the sequence with aqp4 amino acid sequences from other species showed that dogfish aqp4 has high levels (up to 65.3%) of homology with higher vertebrate sequences but lower levels of homology to agnathan (38.2%) or teleost (57.5%) fish sequences. northern blotting indicated that the d ...201122291652
developmental diversity of amphibians.the current model amphibian, xenopus laevis, develops rapidly in water to a tadpole which metamorphoses into a frog. many amphibians deviate from the x. laevis developmental pattern. among other adaptations, their embryos develop in foam nests on land or in pouches on their mother's back or on a leaf guarded by a parent. the diversity of developmental patterns includes multinucleated oogenesis, lack of rna localization, huge non-pigmented eggs, and asynchronous, irregular early cleavages. variat ...201122662314
the rna-binding protein xp54nrb isolated from a ca(2+)-dependent screen is expressed in neural structures during xenopus laevis development.in amphibian embryos, calcium (ca(2+)) signalling is a necessary and sufficient event to induce neural fate. transient elevations of [ca(2+)]i are recorded in neural tissue precursor cells in whole embryos during gastrulation. using a subtractive cdna library between control ectoderm (animal caps) and ectoderm induced toward a neural fate by ca(2+) release, we have isolated several ca(2+)-induced target genes. among the isolated genes, xp54nrb encodes a protein which exhibits the rrm domains cha ...201122252489
[two peroxiredoxins 6 of xenopus laevis].two different genes of peroxiredoxin 6 are encoded in the genome of xenopus laevis: xen1 (acc.no. embl data bank - bco54278) and xen2 (acc.no. embl data bank - bc540309). both genes were cloned and expressed in escherichi coil. proteins were purified and analyzed. the amino acid sequences of the enzymes xen1 and xen2 are 95% identical with the same peroxidase activity, ph and temperature optimums, as well as thermostability, being approximately equal. the expression of peroxiredoxin 6 genes sign ...201122295572
international amphibian micronucleus standardized procedure (iso 21427-1) for in vivo evaluation of double-walled carbon nanotubes toxicity and genotoxicity in water.considering the important production of carbon nanotubes (cnts), it is likely that some of them will contaminate the environment during each step of their life cycle. nevertheless, there is little known about their potential ecotoxicity. consequently, the impact of cnts on the environment must be taken into consideration. this work evaluates the potential impact of well characterized double-walled carbon nanotubes (dwnts) in the amphibian larvae xenopus laevis under normalized laboratory conditi ...201120014232
a proteome map of the pituitary melanotrope cell activated by black-background adaptation of xenopus laevis.upon transfer of xenopus laevis from a white to a black background, the melanotrope cells in the pituitary pars intermedia secrete alpha-melanocyte-stimulating hormone, which stimulates dispersion of melanin pigment in skin melanophores. this adaptive behavior is under the control of neurotransmitters and neuropeptides of hypothalamic origin. the alpha-melanocyte-stimulating hormone-producing cells and their hypothalamic control system provide an interesting model to study proteins required for ...201020029839
effects of roundup and glyphosate formulations on intracellular transport, microtubules and actin filaments in xenopus laevis melanophores.glyphosate containing herbicides, such as roundup, are commonly used and generally considered to be safe. however, some toxic effects are found on amphibians in vivo and human and mouse cells in vitro. in this study the effects of roundup, glyphosate, glyphosateisopropylamine and isopropylamine were studied on intracellular transport by measuring aggregation capacity in xenopus laevis melanophores. the chemicals inhibited retrograde transport of melanosomes in the range of 0.5-5mm. cellular morp ...201020036731
metamorphosis delay in xenopus laevis (daudin) tadpoles exposed to a 50 hz weak magnetic field.the experiment was performed to prove that exposure to a relatively weak extremely low frequency (elf) magnetic field retards tadpoles' development.201020070214
expression of immune genes during metamorphosis of xenopus: a survey.this review focuses on what is known about the immune transcriptome during metamorphosis of xenopus laevis and silurana (xenopus) tropicalis. this subject is of importance to obtain a global understanding of the physiological changes operating during metamorphosis. in turn, a good knowledge of the physiology of amphibian metamorphosis may contribute to the fight against amphibian decline and help the development of alternative toxicologic assays. by examining what is known on the expression of i ...201020036824
fgfr3 expression in xenopus laevis.we studied the expression of fgf receptor 3 (fgfr3) mrna throughout early development of xenopus laevis by rt-pcr and in situ hybridization. rt-pcr shows that fgfr3 mrna is localized within the gastrula; regionalized staining is detected by the neural plate stage and continues throughout embryonic development. strong expression is seen in developing neural structures, especially in the forebrain and hindbrain, including the developing eyes, and in lateral mesoderm. comparison of these data with ...201020044036
analysis of histones and chromatin in xenopus laevis egg and oocyte extracts.histones are the major protein components of chromatin, the physiological form of the genome in all eukaryotic cells. chromatin is the substrate of information-directed biological processes, such as gene regulation and transcription, replication, and mitosis. a long-standing experimental model system to study many of these processes is the extract made from the eggs of the anuran xenopus laevis. since work in recent years has solidified the importance of post-translational modification of histon ...201020051265
using fluorometry and ion-sensitive microelectrodes to study the functional expression of heterologously-expressed ion channels and transporters in xenopus oocytes.the xenopus laevis oocyte is a model system for the electrophysiological study of exogenous ion transporters. three main reasons make the oocyte suitable for this purpose: (a) it has a large cell size (approximately 1mm diameter), (b) it has an established capacity to produce-from microinjected mrnas or crnas-exogenous ion transporters with close-to-physiological post-translational modifications and actions, and (c) its membranes contain endogenous ion-transport activities which are usually smal ...201020051266
two non-steroidal anti-inflammatory drugs, niflumic acid and diclofenac, inhibit the human glutamate transporter eaat1 through different mechanisms.we investigated the effects of non-steroidal anti-inflammatory drugs on substrate-induced currents of l-glutamate (l-glu) transporter eaat1 expressed in xenopus laevis oocytes. niflumic acid (nfa) and diclofenac inhibited l-glu-induced current through eaat1 in a non-competitive manner. nfa produced a leftward shift in reversal potential (e(rev)) of l-glu-induced current and increased current amplitude at the potentials more negative than -100 mv. diclofenac had no effects on e(rev) and inhibited ...201020051656
sperm-borne protein, pawp, initiates zygotic development in xenopus laevis by eliciting intracellular calcium release.we previously reported postacrosomal sheath ww domain binding protein (pawp) as a candidate sperm borne, oocyte-activating factor. pawp enters the oocyte during fertilization and induces oocyte activation events including meiotic resumption, pronuclear formation, and egg cleavage. however, in order to provide proof that pawp is a primary initiator of zygotic development it is imperative to show that pawp initiates intracellular calcium signaling, which is considered essential for oocyte activati ...201020017143
arabidopsis thaliana polyol/monosaccharide transporters 1 and 2: fructose and xylitol/h+ symporters in pollen and young xylem cells.the genome of arabidopsis thaliana contains six genes, atpmt1 to atpmt6 (arabidopsis thaliana polyol/monosaccharide transporter 1-6), which form a distinct subfamily within the large family of more than 50 monosaccharide transporter-like (mst-like) genes. so far, only atpmt5 [formerly named atplt5 (at3g18830)] has been characterized and was shown to be a plasma membrane-localized h(+)-symporter with broad substrate specificity. the characterization of atpmt1 (at2g16120) and atpmt2 (at2g16130), t ...201019969532
observing xenopus laevis oocyte plasma membrane by atomic force microscopy.this paper describes the use of atomic force microscopy (afm) to investigate the plasma membrane of xenopus laevis oocyte. different protocols of sample preparation to perform an afm investigation of both external and intracellular sides of the oocyte plasma membrane are presented and discussed. reproducible afm images allowed visualization and dimensional characterization of protein complexes differently arranged on both sides of the oocyte plasma membrane. in particular, two different arrangem ...201019995606
selective potentiation of homomeric p2x2 ionotropic atp receptors by a fast non-genomic action of progesterone.p2x receptors are ligand-gated ion channels activated by atp that are widely expressed in the organism and regulate many physiological functions. we have studied the effect of progesterone (prog) on native p2x receptors present in rat dorsal root ganglion (drg) neurons and on recombinant p2x receptors expressed in hek293 cells or xenopus laevis oocytes. the effects of prog were observed and already maximal during the first coapplication with atp and did not need any preincubation of the cells wi ...201020004677
effects of s-adenosylmethionine decarboxylase, polyamines, amino acids, and weak bases (amines and ammonia) on development and ribosomal rna synthesis in xenopus embryos.we have been studying control mechanisms of gene expression in early embryogenesis in a south african clawed toad xenopus laevis, especially during the period of midblastula transition (mbt), or the transition from the phase of active cell division (cleavage stage) to the phase of extensive morphogenesis (post-blastular stages). we first found that ribosomal rna synthesis is initiated shortly after mbt in xenopus embryos and those weak bases, such as amines and ammonium ion, selectively inhibit ...201020013010
raman spectroscopy of xenopus laevis oocytes.this work reports on the application of raman spectroscopy for the analysis of xenopus laevis oocytes (stage-i). a two-color home-made microscope has been used for this investigation. in particular, a 785nm raman probe has been used to acquire the spontaneous raman scattering from the oocyte cytoplasm, while a 532nm probe has been employed to detect carotenoids through resonant raman scattering. finally, the distribution of beta-carotene along a diameter of a single oocyte has been investigated.201020035873
delta-notch signaling is involved in the segregation of the three germ layers in xenopus laevis.in vertebrates, the induction of the three germ layers (ectoderm, mesoderm and endoderm) has been extensively studied, but less is known about how they segregate. here, we investigated whether delta-notch signaling is involved in this process. activating the pathway in the marginal zone with notch(icd) resulted in an expansion of endodermal and neural ectoderm precursors, leaving a thinner mesodermal ring around the blastopore at gastrula stage, when germ layers are segregated. on the other hand ...201020079726
arginine methylation of vasa protein is conserved across phyla.recent studies have uncovered an unexpected relationship between factors that are essential for germline development in drosophila melanogaster: the arginine protein methyltransferase 5 (dprmt5/csul/dart5) and its cofactor valois, methylate the piwi family protein aub, enabling it to bind tudor. the rna helicase vasa is another essential protein in germline development. here, we report that mouse (mouse vasa homolog), xenopus laevis, and d. melanogaster vasa proteins contain both symmetrical and ...201020080973
microinjection of xenopus laevis oocytes as a system for studying nuclear transport of viruses.microinjection of xenopus laevis oocytes is an excellent system for studying nuclear transport because of the large size of the oocyte and its high nuclear pore complex (npc) density. in addition, the fact that xenopus oocytes are not permissive for most mammalian viruses makes this system especially useful for studying nuclear transport of viruses in the absence of the confounding factor of virus replication. in this article, we briefly discuss the contribution of microinjection of xenopus oocy ...201020138149
identification of a novel bves function: regulation of vesicular transport.blood vessel/epicardial substance (bves) is a transmembrane protein that influences cell adhesion and motility through unknown mechanisms. we have discovered that bves directly interacts with vamp3, a snare protein that facilitates vesicular transport and specifically recycles transferrin and beta-1-integrin. two independent assays document that cells expressing a mutated form of bves are severely impaired in the recycling of these molecules, a phenotype consistent with disruption of vamp3 funct ...201020057356
mast cells in the amphibian brain during development.this is the first descriptive study of ontogenesis and anatomical distribution of mast cells in the developing brain of three different amphibian species. in the toad and the green frog, mast cells are preferentially located in: (i) the meningeal lining (pia mater), (ii) the choroid plexuses, both anterior and posterior, and (iii) the neuropil, in close association with the epithelial cell lining of blood vessels. it is only in the perennially aquatic african clawed frog that mast cells never ap ...201020070424
effects of protons on macroscopic and single-channel currents mediated by the human p2x7 receptor.human p2x7 receptors (hp2x7rs) belong to the p2x family, which opens an intrinsic cation channel when challenged by extracellular atp. hp2x7rs are expressed in cells of the inflammatory and immune system. during inflammation, atp and protons are secreted into the interstitial fluid. therefore, we investigated the effect of protons on the activation of hp2x7rs. hp2x7rs were expressed in xenopus laevis oocytes and activated by the agonists atp or benzoyl-benzoyl-atp (bzatp) at different ph values. ...201020138022
gene expression profiling--clusters of possibilities.advances in qpcr technology allow studies of increasingly large systems comprising many genes and samples. the increasing data sizes allow expression profiling both in the gene and the samples dimension while also putting higher demands on sound statistical analysis and expertise to handle and interpret its results. we distinguish between exploratory and confirmatory statistical studies. in this paper we demonstrate several techniques available for exploratory studies on a system of xenopus laev ...201020079843
life cycle studies of the hexose transporter of plasmodium species and genetic validation of their essentiality.a plasmodium falciparum hexose transporter (pfht) has previously been shown to be a facilitative glucose and fructose transporter. its expression in xenopus laevis oocytes and the use of a glucose analogue inhibitor permitted chemical validation of pfht as a novel drug target. following recent re-annotations of the p. falciparum genome, other putative sugar transporters have been identified. to investigate further if pfht is the key supplier of hexose to p. falciparum and to extend studies to di ...201020132450
molecular cloning and phylogenetic analysis of small gtpase protein tscdc42 from trichinella spiralis.a full-length of complementary deoxyribonucleic acid (tscdc42) encoding a putative rho-family small gtpase gene cdc42 was isolated from trichinella spiralis, an economically important parasitic nematode of zoonosis. the uninterrupted open reading frame of tscdc42 encodes a predicted protein of 147 amino acids and containing a highly conserved domain of cdc42. comparison with selected sequences from the free-living nematode caenorhabditis elegans, drosophila melanogaster, xenopus laevis, danio re ...201020111874
the pax3 and pax7 paralogs cooperate in neural and neural crest patterning using distinct molecular mechanisms, in xenopus laevis embryos.pax3 and pax7 paralogous genes have functionally diverged in vertebrate evolution, creating opportunity for a new distribution of roles between the two genes and the evolution of novel functions. here we focus on the regulation and function of pax7 in the brain and neural crest of amphibian embryos, which display a different pax7 expression pattern, compared to the other vertebrates already described. pax7 expression is restricted to the midbrain, hindbrain and anterior spinal cord, and pax7 act ...201020116373
replication factory activation can be decoupled from the replication timing program by modulating cdk levels.in the metazoan replication timing program, clusters of replication origins located in different subchromosomal domains fire at different times during s phase. we have used xenopus laevis egg extracts to drive an accelerated replication timing program in mammalian nuclei. although replicative stress caused checkpoint-induced slowing of the timing program, inhibition of checkpoint kinases in an unperturbed s phase did not accelerate it. lowering cyclin-dependent kinase (cdk) activity slowed both ...201020083602
[bioinformatics analysis and function prediction of the novel gene ay358935].to obtain the functional information of ay358935 gene.201020159687
hplc-based activity profiling: discovery of piperine as a positive gaba(a) receptor modulator targeting a benzodiazepine-independent binding site.a plant extract library was screened for gaba(a) receptor activity making use of a two-microelectrode voltage clamp assay on xenopus laevis oocytes. an ethyl acetate extract of black pepper fruits [piper nigrum l. (piperaceae) 100 microg/ml] potentiated gaba-induced chloride currents through gaba(a) receptors (composed of alpha(1), beta(2), and gamma(2s) subunits) by 169.1 +/- 2.4%. with the aid of an hplc-based activity profiling approach, piperine (5) was identified as the main active compound ...201020085307
lbx1 expression and frog limb development.in order to identify prospective limb muscle cells in a frog, we cloned lbx1 from the direct developing frog eleutherodactylus coqui. like in embryos of the frog xenopus laevis but unlike in other vertebrates, eclbx1 is expressed in all trunk somites. like in embryos of chick, mouse, and zebrafish, cells expressing eclbx1 are then found in limb buds, consistent with migration of those cells from somites. eclbx1 is also expressed in the dorsal spinal cord as in other vertebrates.201020091319
photoreceptor development in premetamorphic and metamorphic xenopus laevis.transgenic xenopus laevis are commonly used to study gene expression in photoreceptors, but only red rods and red cones are known to exist in the pre-metamorphic stages commonly used in transgenic studies. using rt-pcr, this study shows that violet cones develop in early pre-metamorphic stages (stage 35) with the red rods and red cones. green rod development began in stage 53 with the onset of metamorphosis.201020091886
endocytosis is required for efficient apical constriction during xenopus gastrulation.coordinated apical constriction (ac) in epithelial sheets drives tissue invagination [1, 2] and is required for diverse morphogenetic movements such as gastrulation [3], neurulation [4, 5], and organogenesis [6]. we showed previously that actomyosin contractility drives ac in xenopus laevis bottle cells [7]; however, it remained unclear whether it does so in concert with other processes. here we report that endocytosis-driven membrane remodeling is required for efficient ac. we found endosomes e ...201020096583
kinetic study of anti-viral ribavirin uptake mediated by hcnt3 and hent1 in xenopus laevis oocytes.transport across the cell membrane is crucial in drug delivery. however, the process is complicated because nucleoside derivatives that are commonly used as anti-viral drugs are transported through two different types of specific transporters: concentrative transporters and equilibrative transporters. cross-disciplinary approaches involving both biological experiments and theoretical considerations are therefore necessary to study the transport of nucleoside analogues such as ribavirin. here we ...201020096989
shorter exposures to harder x-rays trigger early apoptotic events in xenopus laevis embryos.a long-standing conventional view of radiation-induced apoptosis is that increased exposure results in augmented apoptosis in a biological system, with a threshold below which radiation doses do not cause any significant increase in cell death. the consequences of this belief impact the extent to which malignant diseases and non-malignant conditions are therapeutically treated and how radiation is used in combination with other therapies. our research challenges the current dogma of dose-depende ...201020126466
blocking effect of methylflavonolamine on human na(v)1.5 channels expressed in xenopus laevis oocytes and on sodium currents in rabbit ventricular myocytes.to investigate the blocking effects of methylflavonolamine (mfa) on human na(v)1.5 channels expressed in xenopus laevis oocytes and on sodium currents (i(na)) in rabbit ventricular myocytes.201020173760
quantifying calcium fluxes underlying calcium puffs in xenopus laevis oocytes.we determine the calcium fluxes through inositol 1,4,5-trisphosphate receptor/channels underlying calcium puffs of xenopus laevis oocytes using a simplified version of the algorithm of ventura et al. an analysis of 130 puffs obtained with fluo-4 indicates that ca2+ release comes from a region of width approximately 450 nm, that the release duration is peaked around 18 s and that the underlying ca2+ currents range between 0.12 and 0.95 pa. all these parameters are independent of ip(3) concentrati ...201020097419
preparation of a highly active cell-free translation system from immature xenopus laevis oocytes.understanding mechanisms of post-transcriptional control of gene expression has come under much scrutiny in recent years. a key question in this field is how the translation of specific mrnas is activated or repressed both spatially and temporally in a given cell. in oocytes of the frog xenopus laevis a number of mrnas are localized early in oogenesis and subsequently translated at later stages. we have developed a highly active cell-free translation system from oocytes in the early stages of oo ...201020123127
tissue-tissue interaction-triggered calcium elevation is required for cell polarization during xenopus gastrulation.the establishment of cell polarity is crucial for embryonic cells to acquire their proper morphologies and functions, because cell alignment and intracellular events are coordinated in tissues during embryogenesis according to the cell polarity. although much is known about the molecules involved in cell polarization, the direct trigger of the process remains largely obscure. we previously demonstrated that the tissue boundary between the chordamesoderm and lateral mesoderm of xenopus laevis is ...201020126393
a trk/hkt-type k+ transporter from trypanosoma brucei.the molecular mechanisms of k(+) homeostasis are only poorly understood for protozoan parasites. trypanosoma brucei subsp. parasites, the causative agents of human sleeping sickness and nagana, are strictly extracellular and need to actively concentrate k(+) from their hosts' body fluids. the t. brucei genome contains two putative k(+) channel genes, yet the trypanosomes are insensitive to k(+) antagonists and k(+) channel-blocking agents, and they do not spontaneously depolarize in response to ...201020190075
transport of the advanced glycation end products alanylpyrraline and pyrralylalanine by the human proton-coupled peptide transporter hpept1.the glycation compound pyrraline, which originates from the advanced maillard reaction, appears in urine after consumption of pyrraline-containing food. we hypothesized that the absorption of pyrraline occurs in the form of dipeptides rather than the free amino acid. the human intestinal peptide transporter hpept1 was transiently expressed in hela cells. in hpept1-transfected cells but not in cells transfected with empty vector, the uptake of [(14)c]glycylsarcosine was strongly inhibited by alan ...201020104847
mate calling behavior of male south african clawed frogs (xenopus laevis) is suppressed by the antiandrogenic endocrine disrupting compound flutamide.several environmental pollutants have been identified as antiandrogenic endocrine disrupting chemicals (edc), with flutamide (flu) being a model compound for this type of action. despite impacts of edc interfering with sexual differentiation and reproduction in amphibians, established information about suggested effects on sexual behavior is still lacking. in this study adult male xenopus laevis were injected with human chorionic gonadotropin (hcg) to initiate mate calling behavior. after one da ...201020138181
the zebrafish genome encodes the largest vertebrate repertoire of functional aquaporins with dual paralogy and substrate specificities similar to mammals.aquaporins are integral membrane proteins that facilitate the transport of water and small solutes across cell membranes. these proteins are vital for maintaining water homeostasis in living organisms. in mammals, thirteen aquaporins (aqp0-12) have been characterized, but in lower vertebrates, such as fish, the diversity, structure and substrate specificity of these membrane channel proteins are largely unknown.201020149227
neuro-mesodermal patterns in artificially deformed embryonic explants: a role for mechano-geometry in tissue differentiation.the mutual arrangement of neural and mesodermal rudiments in artificially bent double explants of xenopus laevis suprablastoporal areas was compared with that of intact explants. while some of the bent explants straightened or became spherical, most retained and actively reinforced the imposed curvature, creating folds on their concave sides and expanding convex surfaces. in the intact explants, the arrangement of neural and mesodermal rudiments exhibited a distinct antero-posterior polarity, wi ...201020140909
isolation, sequence identification and expression profile of three novel genes rab2a, rab3a and rab7a from black-boned sheep (ovis aries).complete coding sequences of three black-boned sheep (ovis aries) genes rab2a, rab3a and rab7a were amplified using reverse transcription polymerase chain reaction (rt-pcr) based on the conserved sequence information of cattle or other mammals known to be highly homologous to sheep ests. the black-boned sheep rab2a gene encodes a protein of 226 amino acids which contains the conserved putative rabl2 domain and is highly homologous to the rab2a proteins of seven other species--cattle (96%), human ...201020198855
functional and evolutionary analysis of flatfish gonadotropin receptors reveals cladal- and lineage-level divergence of the teleost glycoprotein receptor family.pituitary gonadotropins, follicle-stimulating hormone (fsh), and luteinizing hormone (lh) act via their cognate glycoprotein hormone receptors (gphrs), fsh receptor (fshr), and lh/choriogonadotropin receptor (lhcgr) to regulate gonad physiology. here, we show that the flatfish senegalese sole (solea senegalensis) expresses functional isoforms of fshr and lhcgr, but the genomic origin, ligand activation, and tissue distribution of the receptor transcripts are more complex than expected. by integr ...201020200210
early temporal effects of three thyroid hormone synthesis inhibitors in xenopus laevis.thyroid axis disruption is an important consideration when evaluating risks associated with chemicals. bioassay methods that include thyroid-related endpoints have been developed in a variety of species, including amphibians, whose metamorphic development is thyroid hormone (th)-dependent. inhibition of th synthesis in these species leads to developmental delay, and assays designed to capture these effects take several weeks to complete. in an effort to develop a shorter term approach, the early ...201020153061
kinematics and hydrodynamics analysis of swimming anurans reveals striking inter-specific differences in the mechanism for producing thrust.this study aimed to compare the swimming kinematics and hydrodynamics within and among aquatic and semi-aquatic/terrestrial frogs. high-speed video was used to obtain kinematics of the leg joints and feet as animals swam freely across their natural range of speeds. blade element analysis was then used to model the hydrodynamic thrust as a function of foot kinematics. two purely aquatic frogs, xenopus laevis and hymenochirus boettgeri, were compared with two semi-aquatic/terrestrial frogs, rana p ...201020118313
cave canalem: how endogenous ion channels may interfere with heterologous expression in xenopus oocytes.xenopus laevis oocytes are an outstanding heterologous expression system for the investigation of ion channels. however, oocytes express an amazing variety of endogenous ion channels that can severely interfere with electrophysiological measurements. it is therefore necessary to be aware of the channels present in the oocyte and to be able to exclude artifacts they might cause during the analysis of heterologously expressed ion channels. research on xenopus endogenous ion channels has started ov ...201020123125
the nonpsychoactive cannabinoid cannabidiol inhibits 5-hydroxytryptamine3a receptor-mediated currents in xenopus laevis oocytes.the effect of the plant-derived nonpsychotropic cannabinoid, cannabidiol (cbd), on the function of hydroxytryptamine (5-ht)3a receptors expressed in xenopus laevis oocytes was investigated using two-electrode voltage-clamp techniques. cbd reversibly inhibited 5-ht (1 microm)-evoked currents in a concentration-dependent manner (ic50 = 0.6 microm). cbd (1 microm) did not alter specific binding of the 5-ht3a antagonist [3h]3-(5-methyl-1h-imidazol-4-yl)-1-(1-methylindol-3-yl)propan-1-one (gr65630), ...201020160007
negative feedback regulation of wnt4 signaling by eaf1 and eaf2/u19.previous studies indicated that eaf (ell-associated factor) family members, eaf1 and eaf2/u19, play a role in cancer and embryogenesis. for example, eaf2/u19 may serve as a tumor suppressor in prostate cancer. at the same time, eaf2/u19 is a downstream factor in the non-canonical wnt 4 signaling pathway required for eye development in xenopus laevis, and along with eaf1, contributes to convergence and extension movements in zebrafish embryos through wnt maintenance. here, we used zebrafish embry ...201020161747
the role of the rice aquaporin lsi1 in arsenite efflux from roots.*when supplied with arsenate (as(v)), plant roots extrude a substantial amount of arsenite (as(iii)) to the external medium through as yet unidentified pathways. the rice (oryza sativa) silicon transporter lsi1 (osnip2;1, an aquaporin channel) is the major entry route of arsenite into rice roots. whether lsi1 also mediates arsenite efflux was investigated. *expression of lsi1 in xenopus laevis oocytes enhanced arsenite efflux, indicating that lsi1 facilitates arsenite transport bidirectionally. ...201020163552
ultrastructural and neurochemical architecture of the pituitary neural lobe of xenopus laevis.the melanotrope cell in the amphibian pituitary pars intermedia is a model to study fundamental aspects of neuroendocrine integration. they release alpha-melanophore-stimulating hormone (alphamsh), under the control of a large number of neurochemical signals derived from various brain centers. in xenopus laevis, most of these signals are produced in the hypothalamic magnocellular nucleus (mg) and are probably released from neurohemal axon terminals in the pituitary neural lobe, to stimulate alph ...201020067800
the f-box protein cdc4/fbxw7 is a novel regulator of neural crest development in xenopus laevis.the neural crest is a unique population of cells that arise in the vertebrate ectoderm at the neural plate border after which they migrate extensively throughout the embryo, giving rise to a wide range of derivatives. a number of proteins involved in neural crest development have dynamic expression patterns, and it is becoming clear that ubiquitin-mediated protein degradation is partly responsible for this.201020047651
spatial expression profiles in the xenopus laevis oocytes measured with qpcr tomography.qpcr tomography was developed to study mrna localization in complex biological samples that are embedded and cryo-sectioned. after total rna extraction and reverse transcription, the spatial profiles of mrnas and other functional rnas were determined by qpcr. the xenopus laevis oocyte was selected as model, because of its large size (more than 1mm) and large amount of total rna (approximately 5microg). fifteen sections along the animal-vegetal axis were cut and prepared for quantification of 31 ...201020051264
rhamm mrna expression in proliferating and migrating cells of the developing central nervous system.extracellular matrix components can influence cell behaviour by modulating a wide variety of events. in particular, the glycosaminoglycan hyaluronan is involved in many processes of the normal and pathological adult cells and it is essential for embryonic development. two main ha receptors have been characterized in vertebrate developing embryos: cd44 and rhamm. these receptors display completely different characteristics apart from their ability to bind hyaluronan. rhamm is still the most myste ...201020044037
functional characterization of a partial loss-of-function mutation of the epithelial sodium channel (enac) associated with atypical cystic fibrosis.loss-of-function mutations of the epithelial sodium channel (enac) may contribute to pulmonary symptoms resembling those of patients with atypical cystic fibrosis (cf). recently, we identified a loss-of-function mutation in the alpha-subunit of enac (alphaf61l) in an atypical cf patient without mutations in cftr. to investigate the functional effect of this mutation, we expressed human wild-type alpha beta gamma-enac or mutant alpha(f61l) beta gamma-enac in xenopus laevis oocytes. the alphaf61l ...201020054153
phylotypic expression of the bhlh genes neurogenin2, neurod, and mash1 in the mouse embryonic forebrain.in the anamniote model animals, zebrafish and xenopus laevis, highly comparable early forebrain expression patterns of proneural basic helix-loop-helix (bhlh) genes relevant for neurogenesis (atonal homologs, i.e., neurogenins/neurod and achaete-scute homologs, i.e., ascl/ash) were previously revealed during a particular period of development (zebrafish: 3 days; frog: stage 48). neurogenins/neurod on the one hand and ascl1/ash1 on the other hand exhibit essentially mutually exclusive spatial pat ...201020058311
comparative transcriptomic analysis of follicle-enclosed oocyte maturational and developmental competence acquisition in two non-mammalian vertebrates.in vertebrates, late oogenesis is a key period during which the oocyte acquires its ability to resume meiosis (i.e. maturational competence) and to develop, once fertilized, into a normal embryo (i.e. developmental competence). however, the molecular mechanisms involved in these key biological processes are far from being fully understood. in order to identify key mechanisms conserved among teleosts and amphibians, we performed a comparative analysis using ovarian tissue sampled at successive st ...201020059772
the bioactive dipeptide anserine is transported by human proton-coupled peptide transporters.the bioactive dipeptide derivative anserine (beta-alanyl-1-n-methyl-l-histidine) is absorbed from the human diet in intact form at the intestinal epithelium. the purpose of this study was to investigate whether anserine is a substrate of the h(+)/peptide cotransporters 1 and 2 (pept1 and pept2). we first assessed the effects of anserine on [(14)c]glycylsarcosine ([(14)c]gly-sar) uptake into caco-2 cells expressing human pept1 and into spontaneous hypertensive rat kidney proximal tubule (skpt) ce ...201020067523
neurodevelopmental effects of chronic exposure to elevated levels of pro-inflammatory cytokines in a developing visual system.imbalances in the regulation of pro-inflammatory cytokines have been increasingly correlated with a number of severe and prevalent neurodevelopmental disorders, including autism spectrum disorder, schizophrenia and down syndrome. although several studies have shown that cytokines have potent effects on neural function, their role in neural development is still poorly understood. in this study, we investigated the link between abnormal cytokine levels and neural development using the xenopus laev ...201020067608
roles of werner syndrome protein in protection of genome integrity.werner syndrome protein (wrn) is one of a family of five human recq helicases implicated in the maintenance of genome stability. the conserved recq family also includes recq1, bloom syndrome protein (blm), recq4, and recq5 in humans, as well as sgs1 in saccharomyces cerevisiae, rqh1 in schizosaccharomyces pombe, and homologs in caenorhabditis elegans, xenopus laevis, and drosophila melanogaster. defects in three of the recq helicases, recq4, blm, and wrn, cause human pathologies linked with canc ...201020075015
regulation of the ca(2+) channel trpv6 by the kinases sgk1, pkb/akt, and pikfyve.the serum- and glucocorticoid-inducible kinase sgk1 and the protein kinase pkb/akt presumably phosphorylate and, by this means, activate the mammalian phosphatidylinositol-3-phosphate-5-kinase pikfyve (pip5k3), which has in turn been shown to regulate transporters and channels. sgk1-regulated channels include the ca(2+) channel trpv6, which is expressed in a variety of epithelial and nonepithelial cells including tumor cells. sgk1 and protein kinase b pkb/akt foster tumor growth. the present stu ...201020041238
visualizing rna localization in xenopus oocytes.rna localization is a conserved mechanism of establishing cell polarity. vg1 mrna localizes to the vegetal pole of xenopus laevis oocytes and acts to spatially restrict gene expression of vg1 protein. tight control of vg1 distribution in this manner is required for proper germ layer specification in the developing embryo. rna sequence elements in the 3' utr of the mrna, the vg1 localization element (vle) are required and sufficient to direct transport. to study the recognition and transport of v ...201020075839
hydroxylated polychlorinated biphenyls (oh-pcbs) induce vitellogenin through estrogenic activity in primary-cultured hepatocytes of the xenopus laevis.vitellogenin (vtg)-inducing activities of 21 kinds of hydroxylated polychlorinated biphenyls (oh-pcbs) were investigated by an assay system using the primary-cultured hepatocyte of the adult male xenopus laevis. an enzyme-linked immunoabsorbent assay (elisa) was able to detect vtg at a minimum detection limit of 0.2ngml(-1). the levels of vtg production in hepatocytes of male x. laevis exposed to six kinds of oh-pcb isomers (2'-oh-cb30, 3'-oh-cb30, 4'-oh-cb30, 4'-oh-cb50, 4'-oh-cb61 4'-oh-cb65) ...201020060147
channel-like characteristics of the low-affinity barley phosphate transporter pht1;6 when expressed in xenopus oocytes.remobilization of inorganic phosphate (p(i)) within a plant is critical for sustaining growth and seed production under external p(i) fluctuation. the barley (hordeum vulgare) transporter hvpht1;6 has been implicated in p(i) remobilization. in this report, we expressed hvpht1;6 in xenopus laevis oocytes, allowing detailed characterization of voltage-dependent fluxes and currents induced by hvpht1;6. hvpht1;6 increased efflux of p(i) near oocyte resting membrane potentials, dependent on external ...201020053709
regulation of renal tubular glucose reabsorption by akt2/pkbss.akt/pkb is known to regulate the facilitative glucose carrier glut4. nothing is known, however, of the role of akt/pkb in the regulation of renal epithelial transport. to explore, whether akt2/pkbbeta influences the na(+)-coupled glucose cotransporter sglt1, human sglt1 was expressed in xenopus oocytes with or without akt/pkb and electrogenic glucose transport determined by dual electrode voltage clamp. the coexpression of akt/pkb in sglt1-expressing oocytes was followed by an increase in glucos ...201020164156
expression profiles of lhbeta, fshbeta and their gonadal receptor mrnas during sexual differentiation of xenopus laevis tadpoles.the gonadotropins, luteinising hormone (lh) and follicle stimulating hormone (fsh), are important hormones regulating reproductive biology in vertebrates, especially the processes of steroidogenesis and gamete maturation. despite the role of gonadotropins during the reproductive cycle in amphibians is well established, much less is known about the functional maturation of the hypothalamus-pituitary-gonad axis during larval development. therefore, the present study aimed to analyze the expression ...201020171219
cryptochrome genes are highly expressed in the ovary of the african clawed frog, xenopus tropicalis.cryptochromes (crys) are flavoproteins sharing high homology with photolyases. some of them have function(s) including transcription regulation in the circadian clock oscillation, blue-light photoreception for resetting the clock phase, and light-dependent magnetoreception. vertebrates retain multiple sets of cry or cry-related genes, but their functions are yet unclear especially in the lower vertebrates. although crys and the other circadian clock components have been extensively studied in th ...201020174658
hvalmt1 from barley is involved in the transport of organic anions.members of the almt gene family contribute to the al(3+) resistance of several plant species by facilitating malate efflux from root cells. the first member of this family to be cloned and characterized, taalmt1, is responsible for most of the natural variation of al(3+) resistance in wheat. the current study describes the isolation and characterization of hvalmt1, the barley gene with the greatest sequence similarity to taalmt1. hvalmt1 is located on chromosome 2h which has not been associated ...201020176888
synaptic maturation of the xenopus retinotectal system: effects of brain-derived neurotrophic factor on synapse ultrastructure.synaptogenesis is a dynamic process that involves structural changes in developing axons and dendrites as synapses form and mature. the visual system of xenopus laevis has been used as a model to study dynamic changes in axons and dendrites as synapses form in the living brain and the molecular mechanisms that control these processes. brain-derived neurotrophic factor (bdnf) contributes to the establishment and refinement of visual connectivity by modulating retinal ganglion cell (rgc) axon arbo ...201020127801
inhibition of na+-taurocholate co-transporting polypeptide-mediated bile acid transport by cholestatic sulfated progesterone metabolites.sulfated progesterone metabolite (p4-s) levels are raised in normal pregnancy and elevated further in intrahepatic cholestasis of pregnancy (icp), a bile acid-liver disorder of pregnancy. icp can be complicated by preterm labor and intrauterine death. the impact of p4-s on bile acid uptake was studied using two experimental models of hepatic uptake of bile acids, namely cultured primary human hepatocytes (phh) and na(+)-taurocholate co-transporting polypeptide (ntcp)-expressing xenopus laevis oo ...201020177056
diclofenac-induced stimulation of smct1 (slc5a8) in a heterologous expression system: a rpe specific phenomenon.smct1 is a na(+)-coupled monocarboxylate transporter expressed in a variety of tissues including kidney, thyroid, small intestine, colon, brain, and retina. we found recently that several non-steroidal anti-inflammatory drugs (nsaids) inhibit the activity of smct1. here we evaluated the effect of diclofenac, also a nsaid, on smct1. smct1 cdna was expressed heterologously in the human retinal pigment epithelial cell lines hrpe and arpe-19, the human mammary epithelial cell line mcf7, and in xenop ...201020178774
fmr1/fxr1 and the mirna pathway are required for eye and neural crest development.fmr1 and fxr1 are rna binding proteins interacting with the mirna-induced silencing complex, risc. here we describe for the first time the function of these proteins during eye and neural crest (nc) development in xenopus laevis. a loss of fmr1 or fxr1 results in abnormal eye development as well as defects in cranial cartilage derived from cranial nc cells. we further investigated the possible mechanism of these phenotypes by showing that a depletion of dicer, an important enzyme for generating ...201020197067
temporal and spatial patterning of axial myotome fibers in xenopus laevis.somites give rise to the vertebral column and segmented musculature of adult vertebrates. the cell movements that position cells within somites along the anteroposterior and dorsoventral axes are not well understood. using a fate mapping approach, we show that at the onset of xenopus laevis gastrulation, mesoderm cells undergo distinct cell movements to form myotome fibers positioned in discrete locations within somites and along the anteroposterior axis. we show that the distribution of presomi ...201020235228
commd1 downregulates the epithelial sodium channel through nedd4-2.the epithelial sodium channel (enac) is important for the long-term control of na(+) homeostasis and blood pressure. our previous studies demonstrated that copper metabolism murr1 domain-containing protein 1 (commd1; previously known as murr1), a protein involved in copper metabolism, inhibited amiloride-sensitive current in xenopus laevis oocytes expressing enac (j biol chem 279: 5429, 2004). in this study, we report that commd1 inhibits amiloride-sensitive current in mammalian epithelial cells ...201020237237
xenopus dna2 is a helicase/nuclease that is found in complexes with replication proteins and-1/ctf4 and mcm10 and dsb response proteins nbs1 and atm.we have used the xenopus laevis egg extract system to study the roles of vertebrate dna2 in dna replication and double-strand-break (dsb) repair.  we first establish that xenopus dna2 is a helicase, as well as a nuclease.  we further show that dna2 is a nuclear protein that is actively recruited to dna only after replication origin licensing.  dna2 co-localizes in foci with rpa and is found in a complex with replication fork components and-1 and mcm10.  dna2 interacts with the dsb repair and che ...201020237432
molecular cloning and functional expression of atlantic salmon peptide transporter 1 in xenopus oocytes reveals efficient intestinal uptake of lysine-containing and other bioactive di- and tripeptides in teleost fish.atlantic salmon (salmo salar l.) is one of the most economically important cultured fish and also a key model species in fish nutrition. during digestion, dietary proteins are enzymatically cleaved and a fraction of degradation products in the form of di- and tripeptides translocates from the intestinal lumen into the enterocyte via the peptide transporter 1 (pept1). with this in mind, a full-length cdna encoding the atlantic salmon pept1 (aspept1) was cloned and functionally characterized. when ...201020220205
peptide sr11a from conus spurius is a novel peptide blocker for kv1 potassium channels.more than a hundred conotoxins are known today and from them, only seven conopeptides have been identified to target voltage-gated potassium channels (kv). conotoxin sr11a belongs to the i(2)-superfamily which is characterized by four disulfide bridges and provokes muscle stiffness when injected intracranially in mice. the aim of this work was to test the biological activity of sr11a on recombinant voltage-gated kv1 potassium channels expressed in xenopus laevis oocytes. peptide sr11a was purifi ...201020403399
multiple mechanisms of herg liability: k+ current inhibition, disruption of protein trafficking, and apoptosis induced by amoxapine.the antidepressant amoxapine has been linked to cases of qt prolongation, acute heart failure, and sudden death. inhibition of cardiac herg (kv11.1) potassium channels causes prolonged repolarization and is implicated in apoptosis. apoptosis in association with amoxapine has not yet been reported. this study was designed to investigate amoxapine effects on herg currents, herg protein trafficking, and herg-associated apoptosis in order to elucidate molecular mechanisms underlying cardiac side eff ...201020229012
apoptosis in amphibian organs during metamorphosis.during amphibian metamorphosis, the larval tissues/organs rapidly degenerate to adapt from the aquatic to the terrestrial life. at the cellular level, a large quantity of apoptosis occurs in a spatiotemporally-regulated fashion in different organs to ensure timely removal of larval organs/tissues and the development of adult ones for the survival of the individuals. thus, amphibian metamorphosis provides us a good opportunity to understand the mechanisms regulating apoptosis. to investigate this ...201020238476
skeletal advance and arrest in giant non-metamorphosing african clawed frog tadpoles (xenopus laevis: daudin).this study examines the skeletons of giant non-metamorphosing (gnm) xenopus laevis tadpoles, which arrest their development indefinitely before metamorphosis, and grow to excessively large sizes in the absence of detectable thyroid glands. cartilage growth is isometric; however, chondrocyte size is smaller in gnm tadpoles than in controls. most cartilages stain weakly with alcian blue, and several cartilages are calcified (unlike controls). however, cartilages subjacent to periosteum-derived bon ...201020402828
effects of cadmium, estradiol-17beta and their interaction on gonadal condition and metamorphosis of male and female african clawed frog, xenopus laevis.to assess interaction effects between cadmium (cd, a putative xenoestrogen) and estradiol-17beta (e(2)) on sex differentiation and metamorphosis, xenopus laevis were exposed to solvent-control (0.005% ethanol), cd (10microgl(-1)), e(2) (1microgl(-1)), or cd and e(2) (cd+e(2)) in fetax medium from fertilization to 75d postfertilization. each treatment was applied to four aquaria, each with 30 fertilized eggs. mortality was recorded and animals were sampled as they completed metamorphosis (nieuwko ...201020299069
echocardiographic assessment of cardiac morphology and function in xenopus.advances using xenopus as a model permit valuable inquiries into cardiac development from embryo to adult. noninvasive methods are needed to study cardiac function longitudinally. the objective of this study was to evaluate the feasibility of echocardiographic studies in xenopus and establish normative data of adult cardiac structure and function. doppler and 2d echocardiograms and electrocardiograms were acquired from adult xenopus laevis and x. tropicalis. frogs were exposed to either isoflura ...201020412684
dicalcin inhibits fertilization through its binding to a glycoprotein in the egg envelope in xenopus laevis.fertilization comprises oligosaccharide-mediated sperm-egg interactions, including sperm binding to an extracellular egg envelope, sperm penetration through the envelope, and fusion with an egg plasma membrane. we show that xenopus dicalcin, an s100-like ca(2+)-binding protein, present in the extracellular egg envelope (vitelline envelope (ve)), is a suppressive mediator of sperm-egg interaction. preincubation with specific antibody greatly increased the efficiency of in vitro fertilization, whe ...201020299459
cell adhesion glycoprotein vitronectin during xenopus laevis embryogenesis.vitronectin (vn) is a cell-adhesive glycoprotein present in blood and extracellular matrix of all vertebrates. in the present study we reported the cdna cloning of xenopus laevisvitronectin and its spatial and temporal expression pattern during the embryonic development of this important model organism. the deduced amino acid sequence of xenopus laevis vn showed 49%, 47% and 43% identity with human, chicken and zebrafish orthologs, respectively, whereas the comparison with xenopus tropicalis vn ...201020302971
molecular cloning and characterization of kifc1-like kinesin gene (ot-kifc1) from octopus tankahkeei.spermiogenesis in octopus tankahkeei involves striking cellular reorganization to generate a mature spermatozoon. this process may require spermatid-specific adaptation of cytoskeleton and associated molecular motor proteins. kifc1 is a c-terminal kinesin motor with important roles in acrosome biogenesis and nuclear reshaping during spermiogenesis in rat. here, we have cloned and characterized the gene encoding a homologue of rat kifc1, termed as ot-kifc1, from the testis of o. tankahkeei. the 2 ...201020304088
effects of protostane-type triterpenoids on the 5-ht3a receptor-mediated ion current in xenopus oocytes.alisol derivatives are unique protostane-type triterpenoid compounds that are isolated from alismatis rhizoma, which is a well-known traditional medicine in east asia. in the present study, we investigated the effects of protostane-type triterpenoids (aa, alisol a; ab, alisol b; ab-ac, alisol b 23-acetate; ac-ac, alisol c 23-aceteate) on 5-ht-induced currents mediated by the human 5-ht(3)a receptor expressed in xenopus laevis oocytes. co-treatment with triterpenoids regulated the 5-ht-induced in ...201020307506
midkine and pleiotrophin have bactericidal properties: preserved antibacterial activity in a family of heparin-binding growth factors during evolution.antibacterial peptides of the innate immune system combat pathogenic microbes, but often have additional roles in promoting inflammation and as growth factors during tissue repair. midkine (mk) and pleiotrophin (ptn) are the only two members of a family of heparin-binding growth factors. they show restricted expression during embryogenesis and are up-regulated in neoplasia. in addition, mk shows constitutive and inflammation-dependent expression in some non-transformed tissues of the adult. in t ...201020308059
guard cell anion channel slac1 is regulated by cdpk protein kinases with distinct ca2+ affinities.in response to drought stress, the phytohormone abscisic acid (aba) induces stomatal closure. thereby the stress hormone activates guard cell anion channels in a calcium-dependent, as well as -independent, manner. open stomata 1 protein kinase (ost1) and abi1 protein phosphatase (aba insensitive 1) represent key components of calcium-independent aba signaling. recently, the guard cell anion channel slac1 was identified. when expressed heterologously slac1 remained electrically silent. upon coexp ...201020385816
modulation of the arabidopsis kat1 channel by an activator of protein kinase c in xenopus laevis oocytes.the arabidopsis thaliana k(+) channel kat1 has been suggested to play a key role in the regulation of the aperture of stomatal pores on the surface of plant leaves. calcium-dependent and calcium-independent signaling pathways are involved in abscisic acid-mediated regulation of guard cell turgidity. although the activity of the kat1 channel is thought to be regulated by calcium-dependent protein kinases, the effect of phosphorylation on kat1 and the phosphorylated target sites remain elusive. be ...201020423459
a conserved methionine residue controls the substrate selectivity of a neuronal glutamate transporter.glutamate transporters located in the brain maintain low synaptic concentrations of the neurotransmitter by coupling its flux to that of sodium and other cations. in the binding pocket of the archeal homologue glt(ph), a conserved methionine residue has been implicated in the binding of the benzyl moiety of the nontransportable substrate analogue threo-beta-benzyloxyaspartate. to determine whether the corresponding methionine residue of the neuronal glutamate transporter eaac1, met-367, fulfills ...201020424168
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