| dicalcin, a zona pellucida protein that regulates fertilization competence of the egg coat in xenopus laevis. | fertilization is a highly coordinated process whereby sperm interact with the egg-coating envelope (called the zona pellucida, zp) in a taxon-restricted manner, fertilization triggers the resumption of the cell cycle of the egg, ultimately leading to generation of a new organism that contains hereditary information of the parents. the complete sperm-zp interaction comprises sperm recognition of the zp, the acrosome reaction, penetration of the zp, and fusion with the egg. recent evidence suggest ... | 2015 | 26420688 |
| exposure to 3,3',5-triiodothyronine affects histone and rna polymerase ii modifications, but not dna methylation status, in the regulatory region of the xenopus laevis thyroid hormone receptor βα gene. | thyroid hormones (ths) play a critical role in amphibian metamorphosis, during which the th receptor (tr) gene, thrb, is upregulated in a tissue-specific manner. the xenopus laevis thrb gene has 3 th response elements (tres) in the 5' flanking regulatory region and 1 tre in the exon b region, around which cpg sites are highly distributed. to clarify whether exposure to 3,3',5-triiodothyronine (t3) affects histone and rna polymerase ii (rnapii) modifications and the level of dna methylation in th ... | 2015 | 26417689 |
| low concentrations of metal mixture exposures have adverse effects on selected biomarkers of xenopus laevis tadpoles. | polluted ecosystems may contain mixtures of metals, such that the combinations of metals, even in low concentrations, may cause adverse effects. in the present study, we focused on toxic effects of mixtures of selected metals, the lc50 values, and also their safety limit in aquatic systems imposed by the european legislation using a model organism. xenopus laevis tadpoles were used as test organisms. they were exposed to metals or their combinations due to 96-h lc50 values. glutathione s-transfe ... | 2015 | 26415005 |
| joint effects of pesticides and ultraviolet-b radiation on amphibian larvae. | a combination of multiple stressors may be linked to global amphibian declines. of these, pesticides and uvb radiation co-exposures were examined on the african clawed frog (xenopus laevis) to provide information that may be useful for amphibian conservation. the independent action model and inferential statistics were used to examine interactions between pesticides (malathion, endosulfan, α-cypermethrin, or chlorothalonil) and environmentally relevant uvb exposures. uvb radiation alone caused 3 ... | 2015 | 26412264 |
| the role of flexible loops in folding, trafficking and activity of equilibrative nucleoside transporters. | equilibrative nucleoside transporters (ents) are integral membrane proteins, which reside in plasma membranes of all eukaryotic cells and mediate thermodynamically downhill transport of nucleosides. this process is essential for nucleoside recycling, and also plays a key role in terminating adenosine-mediated cellular signaling. furthermore, ents mediate the uptake of many drugs, including anticancer and antiviral nucleoside analogues. the structure and mechanism, by which ents catalyze trans-me ... | 2015 | 26406980 |
| isoform-specific phosphorylation-dependent regulation of connexin hemichannels. | connexins form gap junction channels made up of two connexons (hemichannels) from adjacent cells. unopposed hemichannels may open toward the extracellular space upon stimulation by, e.g., removal of divalent cations from the extracellular solution and allow isoform-specific transmembrane flux of fluorescent dyes and physiologically relevant molecules, such as atp and ions. connexin (cx)43 and cx30 are the major astrocytic connexins. protein kinase c (pkc) regulates cx43 in its cell-cell gap junc ... | 2015 | 26400258 |
| proteomics of xenopus development. | modern mass spectrometry-based methods provide an exciting opportunity to characterize protein expression in the developing embryo. we have employed an isotopic labeling technology to quantify the expression dynamics of nearly 6000 proteins across six stages of development in xenopus laevis from the single stage zygote through the mid-blastula transition and the onset of organogenesis. approximately 40% of the proteins show significant changes in expression across the development stages. the exp ... | 2016 | 26396253 |
| involvement of vat-1 in phosphatidylserine transfer from the endoplasmic reticulum to mitochondria. | mitochondria receive phosphatidylserine (ps) from the endoplasmic reticulum (er), but how ps is moved from the er to mitochondria is unclear. current models postulate a physical link between the organelles, but no involvement of cytosolic proteins. here, we have reconstituted ps transport from the er to mitochondria in vitro using xenopus egg components. transport is independent of er proteins, but is dependent on a cytosolic factor that has a preferential affinity for ps. crosslinking with a ph ... | 2015 | 26394711 |
| the xenopus orfeome: a resource that enables functional genomics. | functional characterisation of proteins and large-scale, systems-level studies are enabled by extensive sets of cloned open reading frames (orfs) in an easily-accessible format that enables many different applications. here we report the release of the first stage of the xenopus orfeome, which contains 8673 orfs from the xenopus gene collection (xgc) for xenopus laevis, cloned into a gateway® donor vector enabling rapid in-frame transfer of the orfs to expression vectors. this resource represent ... | 2015 | 26391338 |
| histone h3 lysine 9 trimethylation is required for suppressing the expression of an embryonically activated retrotransposon in xenopus laevis. | transposable elements in the genome are generally silenced in differentiated somatic cells. however, increasing evidence indicates that some of them are actively transcribed in early embryos and the proper regulation of retrotransposon expression is essential for normal development. although their developmentally regulated expression has been shown, the mechanisms controlling retrotransposon expression in early embryos are still not well understood. here, we observe a dynamic expression pattern ... | 2015 | 26387861 |
| incorporation of non-canonical amino acids. | in this chapter we discuss the strengths, caveats and technical considerations of three approaches for reprogramming the chemical composition of selected amino acids within a membrane protein. in vivo nonsense suppression in the xenopus laevis oocyte, evolved orthogonal trna and aminoacyl-trna synthetase pairs and protein ligation for biochemical production of semisynthetic proteins have been used successfully for ion channel and receptor studies. the level of difficulty for the application of e ... | 2015 | 26381943 |
| molecular cloning and functional expression of the equine k+ channel kv11.1 (ether à go-go-related/kcnh2 gene) and the regulatory subunit kcne2 from equine myocardium. | the kcnh2 and kcne2 genes encode the cardiac voltage-gated k+ channel kv11.1 and its auxiliary β subunit kcne2. kv11.1 is critical for repolarization of the cardiac action potential. in humans, mutations or drug therapy affecting the kv11.1 channel are associated with prolongation of the qt intervals on the ecg and increased risk of ventricular tachyarrhythmia and sudden cardiac death--conditions known as congenital or acquired long qt syndrome (lqts), respectively. in horses, sudden, unexplaine ... | 2015 | 26376488 |
| identification of a vxp targeting signal in the flagellar na+ /k+ -atpase. | na(+) /k(+) -atpase (nka) participates in setting electrochemical gradients, cardiotonic steroid signaling and cellular adhesion. distinct isoforms of nka are found in different tissues and subcellular localization patterns. for example, nka α1 is widely expressed, nka α3 is enriched in neurons and nka α4 is a testes-specific isoform found in sperm flagella. in some tissues, ankyrin, a key component of the membrane cytoskeleton, can regulate the trafficking of nka. in the retina, nka and ankyrin ... | 2015 | 26373354 |
| gata2 regulates wnt signaling to promote primitive red blood cell fate. | primitive erythropoiesis is regulated in a non cell-autonomous fashion across evolution from frogs to mammals. in xenopus laevis, signals from the overlying ectoderm are required to induce the mesoderm to adopt an erythroid fate. previous studies in our lab identified the transcription factor gata2 as a key regulator of this ectodermal signal. to identify gata2 target genes in the ectoderm required for red blood cell formation in the mesoderm, we used microarray analysis to compare gene expressi ... | 2015 | 26365900 |
| role of n-glycosylation in renal betaine transport. | the osmolyte and folding chaperone betaine is transported by the renal na(+)-coupled gaba (γ-aminobutyric acid) symporter bgt-1 (betaine/gaba transporter 1), a member of the slc6 (solute carrier 6) family. under hypertonic conditions, the transcription, translation and plasma membrane (pm) insertion of bgt-1 in kidney cells are significantly increased, resulting in elevated betaine and gaba transport. re-establishing isotonicity involves pm depletion of bgt-1. the molecular mechanism of the regu ... | 2015 | 26348906 |
| kinetochore function is controlled by a phospho-dependent coexpansion of inner and outer components. | it is widely accepted that the kinetochore is built on cenp-a-marked centromeric chromatin in a hierarchical order from inner to outer kinetochore. recruitment of many kinetochore proteins depends on microtubule attachment status, but it remains unclear how their assembly/disassembly is orchestrated. applying 3d structured illumination microscopy to xenopus laevis egg extracts, here we reveal that in the absence of microtubule attachment, proteins responsible for lateral attachment and spindle c ... | 2015 | 26347137 |
| a zinc(ii) photocage based on a decarboxylation metal ion release mechanism for investigating homeostasis and biological signaling. | metal ion signaling in biology has been studied extensively with ortho-nitrobenzyl photocages; however, the low quantum yields and other optical properties are not ideal for these applications. we describe the synthesis and characterization of ntadecage, the first member in a new class of zn(2+) photocages that utilizes a light-driven decarboxylation reaction in the metal ion release mechanism. ntadecage binds zn(2+) with sub-pm affinity using a modified nitrilotriacetate chelator and exhibits a ... | 2015 | 26346802 |
| nf2/merlin is required for the axial pattern formation in the xenopus laevis embryo. | the nf2 gene product merlin is a ferm-domain protein possessing a broad tumor-suppressing function. nf2/merlin has been implicated in regulating multiple signaling pathways critical for cell growth and survival. however, it remains unknown whether nf2/merlin regulates wnt/β-catenin signaling during vertebrate embryogenesis. here we demonstrate that nf2/merlin is required for body pattern formation in the xenopus laevis embryo. depletion of the maternal nf2/merlin enhances organizer gene expressi ... | 2015 | 26344136 |
| phosphorylation at serine 52 and 635 does not alter the transport properties of glucosinolate transporter atgtr1. | little is known about how plants regulate transporters of defense compounds. in a. thaliana, glucosinolates are transported between tissues by npf2.10 (atgtr1) and npf2.11 (atgtr2). mining of the phosphat4.0 database showed two cytosol exposed phosphorylation sites for atgtr1 and one membrane-buried phosphorylation site for atgtr2. in this study, we investigate whether mutation of the two potential regulatory sites of atgtr1 affected transport of glucosinolates in xenopus oocytes. characterizati ... | 2016 | 26340317 |
| global analysis of asymmetric rna enrichment in oocytes reveals low conservation between closely related xenopus species. | rnas that localize to the vegetal cortex during xenopus laevis oogenesis have been reported to function in germ layer patterning, axis determination, and development of the primordial germ cells. here we report on the genome-wide, comparative analysis of differentially localizing rnas in xenopus laevis and xenopus tropicalis oocytes, revealing a surprisingly weak degree of conservation in respect to the identity of animally as well as vegetally enriched transcripts in these closely related speci ... | 2015 | 26337391 |
| hspa9 is required for pronephros specification and formation in xenopus laevis. | development of the pronephros in xenopus laevis is largely dependent on retinoic acid signaling at the time of kidney field specification with the simultaneous occurrence of a necessary calcium signaling. at the crossroads of these two signaling pathways, we studied the role of hspa9 (heat shock 70 kda protein 9) encoding a mitochondrial chaperone in pronephros development. | 2015 | 26335666 |
| sensory-evoked spiking behavior emerges via an experience-dependent plasticity mechanism. | the ability to generate action potentials (spikes) in response to synaptic input determines whether a neuron participates in information processing. how a developing neuron becomes an active participant in a circuit or whether this process is activity dependent is not known, especially as spike-dependent plasticity mechanisms would not be available to non-spiking neurons. here we use the optic tectum of awake xenopus laevis tadpoles to determine how a neuron becomes able to generate sensory-driv ... | 2015 | 26335647 |
| copy number variation and genetic diversity of mhc class iib alleles in an alien population of xenopus laevis. | xenopus laevis (the african clawed frog), which originated through hybridisation and whole genome duplication, has been used as a model for genetics and development for many years, but surprisingly little is known about immune gene variation in natural populations. the purpose of this study was to use an isolated population of x. laevis that was introduced to wales, uk in the past 50 years to investigate how variation at the mhc compares to that at other loci, following a severe population bottl ... | 2015 | 26329765 |
| characterization of ticlopidine-induced developmental and teratogenic defects in xenopus embryos and human endothelial cells. | ticlopidine is an anti-platelet drug that inhibits platelet aggregation via the functional alteration of platelet membranes. however, the mechanism underlying the adverse developmental effects of ticlopidine has not been clearly demonstrated. in this study, we evaluated the developmental toxicity and teratogenicity of ticlopidine on xenopus laevis embryos and in human umbilical vein endothelial cells (huvecs) using a frog embryo teratogenesis assay-xenopus (fetax) and blood and lymph vessel form ... | 2015 | 26327247 |
| glutathione release through connexin hemichannels: implications for chemical modification of pores permeable to large molecules. | cysteine-scanning mutagenesis combined with thiol reagent modification is a powerful method with which to define the pore-lining elements of channels and the changes in structure that accompany channel gating. using the xenopus laevis oocyte expression system and two-electrode voltage clamp, we performed cysteine-scanning mutagenesis of several pore-lining residues of connexin 26 (cx26) hemichannels, followed by chemical modification using a methanethiosulfonate (mts) reagent, to help identify t ... | 2015 | 26324677 |
| prepatterning and patterning of the thalamus along embryonic development of xenopus laevis. | previous developmental studies of the thalamus (alar part of the diencephalic prosomere p2) have defined the molecular basis for the acquisition of the thalamic competence (preparttening), the subsequent formation of the secondary organizer in the zona limitans intrathalamica, and the early specification of two anteroposterior domains (rostral and caudal progenitor domains) in response to inducing activities and that are shared in birds and mammals. in the present study we have analyzed the embr ... | 2015 | 26321920 |
| aquaporins mediate silicon transport in humans. | in animals, silicon is an abundant and differentially distributed trace element that is believed to play important biological functions. one would thus expect silicon concentrations in body fluids to be regulated by silicon transporters at the surface of many cell types. curiously, however, and even though they exist in plants and algae, no such transporters have been identified to date in vertebrates. here, we show for the first time that the human aquaglyceroporins, i.e., aqp3, aqp7, aqp9 and ... | 2015 | 26313002 |
| effect of a grin2a de novo mutation associated with epilepsy and intellectual disability on nmda receptor currents and mg(2+) block in cultured primary cortical neurons. | background grin2a encodes the glun2a subunit of the nmda receptor (nmdar), an ionotropic glutamate receptor that has important roles in synaptogenesis and synaptic plasticity. some individuals with early onset epilepsies and intellectual disability carry heterozygous missense mutations in this gene, including a de-novo mutation in the receptor pore region (glun2a(n615k)). we hypothesised that this mutation underlies the carrier's brain disorder and sought to explore its functional consequences. | 2015 | 26312887 |
| prediction of functionally important phospho-regulatory events in xenopus laevis oocytes. | the african clawed frog xenopus laevis is an important model organism for studies in developmental and cell biology, including cell-signaling. however, our knowledge of x. laevis protein post-translational modifications remains scarce. here, we used a mass spectrometry-based approach to survey the phosphoproteome of this species, compiling a list of 2636 phosphosites. we used structural information and phosphoproteomic data for 13 other species in order to predict functionally important phospho- ... | 2015 | 26312481 |
| targeted inhibition of snail activity in breast cancer cells by using a co(iii) -ebox conjugate. | the transition from a non-invasive to an invasive phenotype is an essential step in tumor metastasis. the snail family of transcription factors (tfs) is known to play a significant role in this transition. these tfs are zinc fingers that bind to the caggtg ebox consensus sequence. co(iii) -ebox is a cobalt(iii) complex attached to an ebox oligonucleotide that confers specificity towards snail tfs. co(iii) -ebox has been shown to inhibit snail-mediated embryonic neural crest development in xenopu ... | 2015 | 26305708 |
| metamorphic remodeling of the olfactory organ of the african clawed frog, xenopus laevis. | the amphibian olfactory system undergoes massive remodeling during metamorphosis. the transition from aquatic olfaction in larvae to semiaquatic or airborne olfaction in adults requires anatomical, cellular, and molecular modifications. these changes are particularly pronounced in pipidae, whose adults have secondarily adapted to an aquatic life style. in the fully aquatic larvae of xenopus laevis, the main olfactory epithelium specialized for sensing water-borne odorous substances lines the pri ... | 2016 | 26294036 |
| glutamate cycling may drive organic anion transport on the basal membrane of human placental syncytiotrophoblast. | the organic anion transporter oat4 (slc22a11) and organic anion transporting polypeptide oatp2b1 (slco2b1) are expressed in the basal membrane of the placental syncytiotrophoblast. these transporters mediate exchange whereby uptake of one organic anion is coupled to efflux of a counter-ion. in placenta, these exchangers mediate placental uptake of substrates for oestrogen synthesis as well as clearing waste products and xenobiotics from the fetal circulation. however, the identity of the counter ... | 2015 | 26277985 |
| xenopus pkdcc1 and pkdcc2 are two new tyrosine kinases involved in the regulation of jnk dependent wnt/pcp signaling pathway. | protein kinase domain containing, cytoplasmic (pkdcc) is a protein kinase which has been implicated in longitudinal bone growth through regulation of chondrocytes formation. nevertheless, the mechanism by which this occurs remains unknown. here, we identified two new members of the pkdcc family, pkdcc1 and pkdcc2 from xenopus laevis. interestingly, our knockdown experiments revealed that these two proteins are both involved on blastopore and neural tube closure during gastrula and neurula stages ... | 2015 | 26270962 |
| identification of genes expressed in the migrating primitive myeloid lineage of xenopus laevis. | during primitive hematopoiesis in xenopus, cebpa and spib expressing myeloid cells emerge from the anterior ventral blood island. primitive myeloid cells migrate throughout the embryo and are critical for immunity, healing, and development. although definitive hematopoiesis has been studied extensively, molecular mechanisms leading to the migration of primitive myelocytes remain poorly understood. we hypothesized these cells have specific extracellular matrix modifying and cell motility gene exp ... | 2016 | 26264370 |
| the small heat shock protein, hsp30, is associated with aggresome-like inclusion bodies in proteasomal inhibitor-, arsenite-, and cadmium-treated xenopus kidney cells. | in the present study, treatment of xenopus laevis a6 kidney epithelial cells with the proteasomal inhibitor, mg132, or the environmental toxicants, sodium arsenite or cadmium chloride, induced the accumulation of the small heat shock protein, hsp30, in total and in both soluble and insoluble protein fractions. immunocytochemical analysis revealed the presence of relatively large hsp30 structures primarily in the perinuclear region of the cytoplasm. all three of the stressors promoted the formati ... | 2015 | 26260897 |
| fluorescent ratiometric ph indicator sypher2: applications in neuroscience and regenerative biology. | sypher is a genetically encoded fluorescent ph-indicator with a ratiometric readout, suitable for measuring fast intracellular ph shifts. however, the relatively low brightness of the indicator limits its use. | 2015 | 26259819 |
| cell cycle synchronization in xenopus egg extracts. | many important discoveries in cell cycle research have been made using cell-free extracts prepared from the eggs of the south african clawed frog xenopus laevis. these extracts efficiently support the key nuclear functions of the eukaryotic cell cycle in vitro under apparently the same controls that exist in vivo. the xenopus cell-free system is therefore uniquely suited to the study of the mechanisms, dynamics and integration of cell cycle regulated processes at a biochemical level. here, we de ... | 2016 | 26254920 |
| asymmetries in kinesin-2 and cytoplasmic dynein contributions to melanosome transport. | the mechanisms involved in bidirectional transport along microtubules remain largely unknown. we explored the collective action of kinesin-2 and dynein motors during transport of melanosomes in xenopus laevis melanophores. these motors are attached to organelles through accessory proteins establishing a complex molecular linker. we determined both the stiffness of this linker and the organelles speed and observed that these parameters depended on the organelle size and cargo direction. our resul ... | 2015 | 26247430 |
| conservation of structure and function in vertebrate c-flip proteins despite rapid evolutionary change. | cellular flice-like inhibitory protein (c-flip, gene symbol cflar) was first identified as a negative regulator of death receptor-mediated apoptosis in mammals. to understand the ubiquity and diversity of the c-flip protein subfamily during evolution, c-flip orthologs were identified from a comprehensive range of vertebrates, including birds, amphibians, and fish, and were characterized by combining experimental and computational analysis. predictions of three-dimensional protein structures and ... | 2015 | 29124180 |
| g protein-coupled receptors flop1 and flop2 inhibit wnt/β-catenin signaling and are essential for head formation in xenopus. | patterning of the vertebrate anterior-posterior axis is regulated by the coordinated action of growth factors whose effects can be further modulated by upstream and downstream mediators and the cross-talk of different intracellular pathways. in particular, the inhibition of the wnt/β-catenin signaling pathway by various factors is critically required for anterior specification. here, we report that flop1 and flop2 (flop1/2), g protein-coupled receptors related to gpr4, contribute to the regulati ... | 2015 | 26244992 |
| fertilization competence of the egg-coating envelope is regulated by direct interaction of dicalcin and gp41, the xenopus laevis zp3. | fertilization begins with species-restricted interaction of sperm and the egg-coating envelope, which includes a three-dimensional meshwork of filaments composed of glycoproteins (called zp proteins). growing evidence has unveiled the molecular nature of zp proteins; however, the structural property conferring fertilization competence to the egg-coating envelope remains unknown. here, we show the molecular mechanism that mediates direct interaction between dicalcin, a novel fertilization-suppres ... | 2015 | 26243547 |
| astrocytes phagocytose focal dystrophies from shortening myelin segments in the optic nerve of xenopus laevis at metamorphosis. | oligodendrocytes can adapt to increases in axon diameter through the addition of membrane wraps to myelin segments. here, we report that myelin segments can also decrease their length in response to optic nerve (on) shortening during xenopus laevis metamorphic remodeling. em-based analyses revealed that myelin segment shortening is accomplished by focal myelin-axon detachments and protrusions from otherwise intact myelin segments. astrocyte processes remove these focal myelin dystrophies using k ... | 2015 | 26240339 |
| kinesin family 17 (osmotic avoidance abnormal-3) is dispensable for photoreceptor morphology and function. | in caenorhabditis elegans, homodimeric [kinesin family (kif) 17, osmotic avoidance abnormal-3 (osm-3)] and heterotrimeric (kif3) kinesin-2 motors are required to establish sensory cilia by intraflagellar transport (ift) where kif3 and kif17 cooperate to build the axoneme core and kif17 builds the distal segments. however, the function of kif17 in vertebrates is unresolved. we expressed full-length and motorless kif17 constructs in mouse rod photoreceptors using adeno-associated virus in xenopus ... | 2015 | 26229057 |
| do nanoparticle physico-chemical properties and developmental exposure window influence nano zno embryotoxicity in xenopus laevis? | the growing global production of zinc oxide nanoparticles (znonps) suggests a realistic increase in the environmental exposure to such a nanomaterial, making the knowledge of its biological reactivity and its safe-by-design synthesis mandatory. in this study, the embryotoxicity of znonps (1-100 mg/l) specifically synthesized for industrial purposes with different sizes, shapes (round, rod) and surface coatings (peg, pvp) was tested using the frog embryo teratogenesis assay-xenopus (fetax) to ide ... | 2015 | 26225989 |
| regulation of growth rate and developmental timing by xenopus thyroid hormone receptor α. | thyroid hormone (th) is critical for vertebrate postembryonic development, a period around birth in mammals when plasma th levels are high. interestingly, th receptors (trs), especially trα, are expressed prior to the synthesis and secretion of zygotic th, suggesting the existence of unliganded tr during development. however, the role of unliganded tr during mammalian development has been difficult to study, in part due to the relatively weak phenotype of tr knockout mice. amphibian metamorphosi ... | 2016 | 26219216 |
| atp4 and ciliation in the neuroectoderm and endoderm of xenopus embryos and tadpoles. | during gastrulation and neurulation, foxj1 expression requires atp4a-dependent wnt/β-catenin signaling for ciliation of the gastrocoel roof plate (walentek et al. cell rep. 1 (2012) 516-527.) and the mucociliary epidermis (walentek et al. dev. biol. (2015)) of xenopus laevis embryos. these data suggested that atp4a and wnt/β-catenin signaling regulate foxj1 throughout xenopus development. here we analyzed whether foxj1 expression was also atp4a-dependent in other ciliated tissues of the developi ... | 2015 | 26217756 |
| coexistence of y, w, and z sex chromosomes in xenopus tropicalis. | homomorphic sex chromosomes and rapid turnover of sex-determining genes can complicate establishing the sex chromosome system operating in a given species. this difficulty exists in xenopus tropicalis, an anuran quickly becoming a relevant model for genetic, genomic, biochemical, and ecotoxicological research. despite the recent interest attracted by this species, little is known about its sex chromosome system. direct evidence that females are the heterogametic sex, as in the related species xe ... | 2015 | 26216983 |
| how does the xenopus laevis embryonic cell cycle avoid spatial chaos? | theoretical studies have shown that a deterministic biochemical oscillator can become chaotic when operating over a sufficiently large volume and have suggested that the xenopus laevis cell cycle oscillator operates close to such a chaotic regime. to experimentally test this hypothesis, we decreased the speed of the post-fertilization calcium wave, which had been predicted to generate chaos. however, cell divisions were found to develop normally, and eggs developed into normal tadpoles. motivate ... | 2015 | 26212326 |
| xenopus lap2β protein knockdown affects location of lamin b and nucleoporins and has effect on assembly of cell nucleus and cell viability. | xenopus lap2β protein is the single isoform expressed in xtc cells. the protein localizes on heterochromatin clusters both at the nuclear envelope and inside a cell nucleus. the majority of xlap2β fraction neither colocalizes with tpx2 protein during interphase nor can be immunoprecipitated with xlap2β antibody. knockdown of the xlap2β protein expression in xtc cells by synthetic sirna and plasmid encoded sirna resulted in nuclear abnormalities including changes in shape of nuclei, abnormal chro ... | 2016 | 26209045 |
| light sensitivity in a vertebrate mechanoreceptor? | using immunohistochemistry and western blot analysis, we demonstrate that melanopsin is localised in cells around the central pore of lateral line neuromasts in the african clawed frog, xenopus laevis. since melanopsin is a known photoreceptor pigment with diverse functions in vertebrates, we suggest that the lateral line of xenopus laevis, which is primarily a mechanoreceptor, might also be light sensitive. potential functions of such photosensitivity are discussed, including its role in mediat ... | 2015 | 26206352 |
| concentration-response relationship of the α7 nicotinic acetylcholine receptor agonist frm-17874 across multiple in vitro and in vivo assays. | pharmacological activation of α7 nicotinic acetylcholine receptors (α7 nachrs) may improve cognition in schizophrenia and alzheimer's disease. the present studies describe an integrated pharmacological analysis of the effects of frm-17874, an analogue of encenicline, on α7 nachrs in vitro and in behavioral and neurophysiological assays relevant to cognitive function. frm-17874 demonstrated high affinity binding to human α7 nachrs, displacing [(3)h]-methyllacaconitine (ki=4.3nm). in xenopus laevi ... | 2015 | 26206187 |
| the n-methyl-d-aspartate receptor's neglected subunit - glun1 matters under normal and hyperbaric conditions. | professional deep-water divers exposed to hyperbaric pressure (hp) above 1.1 mpa develop high-pressure neurological syndrome, which is associated with central nervous system hyperexcitability. it was previously reported that hp augments n-methyl-d-aspartate receptor (nmdar) synaptic responses, increases neuronal excitability, and potentially causes irreversible neuronal damage. in addition, we have reported that hp (10.1 mpa) differentially affects ionic currents, measured by the two-electrode v ... | 2015 | 26202884 |
| kruppel-like factor family genes are expressed during xenopus embryogenesis and involved in germ layer formation and body axis patterning. | kruppel-like factors (klfs) are a family of transcription factors consisting of 17 members in mammals, klf1-klf17, which are involved in fundamental cellular physiological procedures, such as cell proliferation, differentiation, and apoptosis. however, their functions in embryonic development have been poorly understood. our previous study has demonstrated that the pluripotency factor klf4 participates in germ layer formation and axis patterning of xenopus embryos by means of the regulation of k ... | 2015 | 26198170 |
| selective depolarization of transmembrane potential alters muscle patterning and muscle cell localization in xenopus laevis embryos. | the correct anatomical placement and precise determination of specific cell types is required for the establishment of normal embryonic patterning. understanding these processes is also important for progress in regenerative medicine and cancer biology. transmembrane voltage gradients across embryonic tissues can mediate cellular communication to regulate the processes of proliferation, migration, and differentiation. our past work showed that selective depolarization of an endogenous instructor ... | 2015 | 26198143 |
| local and long-range endogenous resting potential gradients antagonistically regulate apoptosis and proliferation in the embryonic cns. | bioelectric signals, particularly transmembrane voltage potentials (vmem), play an important role in large-scale patterning during embryonic development. endogenous bioelectric gradients across tissues function as instructive factors during eye, brain, and other morphogenetic processes. an important and still poorly-understood aspect is the control of cell behaviors by the voltage states of distant cell groups. here, experimental alteration of endogenous vmem was induced in xenopus laevis embryo ... | 2015 | 26198142 |
| functional integration of mrna translational control programs. | regulated mrna translation plays a key role in control of cell cycle progression in a variety of physiological and pathological processes, including in the self-renewal and survival of stem cells and cancer stem cells. while targeting mrna translation presents an attractive strategy for control of aberrant cell cycle progression, mrna translation is an underdeveloped therapeutic target. regulated mrnas are typically controlled through interaction with multiple rna binding proteins (rbps) but the ... | 2015 | 26197342 |
| flexible subunit stoichiometry of functional human p2x2/3 heteromeric receptors. | the aim of the present work was to clarify whether heterotrimeric p2x2/3 receptors have a fixed subunit stoichiometry consisting of one p2x2 and two p2x3 subunits as previously suggested, or a flexible stoichiometry containing also the inverse subunit composition. for this purpose we transfected hek293 cells with p2x2 and p2x3 encoding cdna at the ratios of 1:2 and 4:1, and analysed the biophysical and pharmacological properties of the generated receptors by means of the whole-cell patch-clamp t ... | 2015 | 26184350 |
| annexin a3 regulates early blood vessel formation. | annexins are a large family of calcium binding proteins that associate with cell membrane phospholipids and are involved in various cellular processes including endocytosis, exocytosis and membrane-cytoskeletal organization. despite studies on numerous annexin proteins, the function of annexin a3 (anxa3) is largely unknown. our studies identify anxa3 as a unique marker of the endothelial and myeloid cell lineages of xenopus laevis during development. anxa3 transcripts are also detected in endoth ... | 2015 | 26182056 |
| the mutation p.t613a in the pore helix of the kv 11.1 potassium channel is associated with long qt syndrome. | loss-of-function mutations in the voltage gated potassium channel kv 11.1 have been associated with the long qt syndrome (lqts) type 2. we identified the p.t613a mutation in kv 11.1 in a family with lqts. t613a is located in the outer part of the pore helix, a structure that is involved in c-type inactivation. here we characterize the effect of p.t613a on the functional properties of kv 11.1. | 2015 | 26173150 |
| retention of duplicated itam-containing transmembrane signaling subunits in the tetraploid amphibian species xenopus laevis. | the itam-bearing transmembrane signaling subunits (tss) are indispensable components of activating leukocyte receptor complexes. the tss-encoding genes map to paralogous chromosomal regions, which are thought to arise from ancient genome tetraploidization(s). to assess a possible role of tetraploidization in the tss evolution, we studied tss and other functionally linked genes in the amphibian species xenopus laevis whose genome was duplicated about 40 myr ago. we found that x. laevis has retain ... | 2015 | 26170006 |
| dehydration triggers differential microrna expression in xenopus laevis brain. | african clawed frogs, xenopus laevis, although primarily aquatic, have a high tolerance for dehydration, being capable of withstanding the loss of up to 32-35% of total water body water. recent studies have shown that micrornas play a role in the response to dehydration by the liver, kidney and ventral skin of x. laevis. micrornas act by modulating the expression of mrna transcripts, thereby affecting diverse biochemical pathways. in this study, 43 micrornas were assessed in frog brains comparin ... | 2015 | 26169019 |
| developing xenopus embryos recover by compacting and expelling single wall carbon nanotubes. | single wall carbon nanotubes are high aspect ratio nanomaterials being developed for use in materials, technological and biological applications due to their high mechanical stiffness, optical properties and chemical inertness. because of their prevalence, it is inevitable that biological systems will be exposed to nanotubes, yet studies of the effects of nanotubes on developing embryos have been inconclusive and are lacking for single wall carbon nanotubes exposed to the widely studied model or ... | 2016 | 26153061 |
| functional analysis of phosphorylation of the mitotic centromere-associated kinesin by aurora b kinase in human tumor cells. | mitotic centromere-associated kinesin (mcak) is the best characterized member of the kinesin-13 family and plays important roles in microtubule dynamics during mitosis. its activity and subcellular localization is tightly regulated by an orchestra of mitotic kinases, such as aurora b. it is well known that serine 196 of mcak is the major phosphorylation site of aurora b in xenopus leavis extracts and that this phosphorylation regulates its catalytic activity and subcellular localization. in the ... | 2015 | 26148251 |
| lack of phosphomannomutase 2 affects xenopus laevis morphogenesis and the non-canonical wnt5a/ror2 signalling. | reduced phosphomannomutase 2 activity in man leads to hypoglycosylation of glycoconjugates causing pmm2-cdg, the most common type of congenital disorders of glycosylation. here we show that an antisense morpholino-mediated knockdown of the xenopus laevis phosphomannomutase 2 gene provoked a general underglycosylation in frog embryos, which led to an altered phenotype and reduced glycosylation of wnt5a as member of the non-canonical wnt signalling. loss of function experiments in hemi-sectioned e ... | 2015 | 26141167 |
| evolution of courtship songs in xenopus : vocal pattern generation and sound production. | the extant species of african clawed frogs (xenopus and silurana) provide an opportunity to link the evolution of vocal characters to changes in the responsible cellular and molecular mechanisms. in this review, we integrate several robust lines of research: evolutionary trajectories of xenopus vocalizations, cellular and circuit-level mechanisms of vocalization in selected xenopus model species, and xenopus evolutionary history and speciation mechanisms. integrating recent findings allows us to ... | 2015 | 26138673 |
| 3d bio-etching of a complex composite-like embryonic tissue. | morphogenesis involves a complex series of cell signaling, migration and differentiation events that are coordinated as tissues self-assemble during embryonic development. collective cell movements such as those that occur during morphogenesis have typically been studied in 2d with single layers of cultured cells adhering to rigid substrates such as glass or plastic. in vivo, the intricacies of the 3d microenvironment and complex 3d responses are pivotal in the formation of functional tissues. t ... | 2015 | 26138309 |
| distinct functional roles of amphibian (xenopus laevis) colony-stimulating factor-1- and interleukin-34-derived macrophages. | although mϕ represent the most primordial immune cell subsets, the mechanisms governing their functional heterogeneity remain poorly defined. however, it is well established that the csf-1 cytokine contributes to monopoiesis and to this heterogeneity, whereas the unrelated il-34 also binds the csf-1r toward poorly understood immunologic roles. to delineate the molecular and evolutionary basis behind vertebrate mϕ functional heterogeneity, we performed comprehensive transcriptional and functional ... | 2015 | 26136505 |
| sumoylation of the c-terminal domain of dna topoisomerase iiα regulates the centromeric localization of claspin. | dna topoisomerase ii (topoii) regulates dna topology by its strand passaging reaction, which is required for genome maintenance by resolving tangled genomic dna. in addition, topoii contributes to the structural integrity of mitotic chromosomes and to the activation of cell cycle checkpoints in mitosis. post-translational modification of topoii is one of the key mechanisms by which its broad functions are regulated during mitosis. sumoylation of topoii is conserved in eukaryotes and plays a crit ... | 2015 | 26131587 |
| using xenopus to discover new genes involved in branchiootorenal spectrum disorders. | congenital hearing loss is an important clinical problem because, without early intervention, affected children do not properly acquire language and consequently have difficulties developing social skills. although most newborns in the us are screened for hearing deficits, even earlier diagnosis can be made with prenatal genetic screening. genetic screening that identifies the relevant mutated gene can also warn about potential congenital defects in organs not related to hearing. we will discuss ... | 2015 | 26117063 |
| spak and osr1 sensitivity of excitatory amino acid transporter eaat3. | kinases involved in the regulation of epithelial transport include spak (sps1-related proline/alanine-rich kinase) and osr1 (oxidative stress-responsive kinase 1). spak and osr1 are both regulated by wnk (with-no-k(lys)) kinases. the present study explored whether spak and/or osr1 influence the excitatory amino acid transporter eaat3, which accomplishes glutamate and aspartate transport in kidney, intestine and brain. | 2015 | 26112741 |
| structure and gating of the nuclear pore complex. | nuclear pore complexes (npcs) perforate the nuclear envelope and allow the exchange of macromolecules between the nucleus and the cytoplasm. to acquire a deeper understanding of this transport mechanism, we analyse the structure of the npc scaffold and permeability barrier, by reconstructing the xenopus laevis oocyte npc from native nuclear envelopes up to 20 å resolution by cryo-electron tomography in conjunction with subtomogram averaging. in addition to resolving individual protein domains of ... | 2015 | 26112706 |
| benchmarking transcriptome quantification methods for duplicated genes in xenopus laevis. | xenopus is an important model organism for the study of genome duplication in vertebrates. with the full genome sequence of diploid xenopus tropicalis available, and that of allotetraploid x. laevis close to being finished, we will be able to expand our understanding of how duplicated genes have evolved. one of the key features in the study of the functional consequence of gene duplication is how their expression patterns vary across different conditions, and rna-seq seems to have enough resolut ... | 2015 | 26112470 |
| melanopsins: localization and phototransduction in xenopus laevis melanophores. | xenopus laevis melanophores express two melanopsins, opn4x and opn4m. we identified opn4x immunoreactivity throughout the melanophore cytoplasm and in the cell membrane. the strongest immunopositivity for opn4m was observed in the nuclear region, and no labeling was seen in the cell membrane. this immunodistribution suggests opn4x as the functional photopigment. in x. laevis melanophores, light triggers pigment dispersion and clock gene induction at blue wavelength, which maximally activates mel ... | 2015 | 26108966 |
| bh3 domain-independent apolipoprotein l1 toxicity rescued by bcl2 prosurvival proteins. | the potent trypanolytic properties of human apolipoprotein l1 (apol1) can be neutralized by the trypanosome variant surface antigen gene product known as serum resistance-associated protein. however, two common apol1 haplotypes present uniquely in individuals of west african ancestry each encode apol1 variants resistant to serum resistance-associated protein, and each confers substantial resistance to human african sleeping sickness. in contrast to the dominantly inherited anti-trypanosomal acti ... | 2015 | 26108665 |
| structure-activity relationships of bumetanide derivatives: correlation between diuretic activity in dogs and inhibition of the human nkcc2a transporter. | the n-k-cl cotransporters (nkccs) mediate the coupled, electroneutral movement of na+ , k+ and cl- ions across cell membranes. there are two isoforms of this cation co-transporter, nkcc1 and nkcc2. nkcc2 is expressed primarily in the kidney and is the target of diuretics such as bumetanide. bumetanide was discovered by screening ∼5000 3-amino-5-sulfamoylbenzoic acid derivatives, long before nkcc2 was identified in the kidney. therefore, structure-activity studies on effects of bumetanide derivat ... | 2015 | 26101812 |
| melanopsin photoreception in the eye regulates light-induced skin colour changes through the production of α-msh in the pituitary gland. | how skin colour adjusts to circadian light/dark cycles is poorly understood. melanopsin (opn4) is expressed in melanophores, where in vitro studies suggest it regulates skin pigmentation through a 'primary colour response' in which light photosensitivity is translated directly into pigment movement. however, the entrainment of the circadian rhythm is regulated by a population of melanopsin-expressing retinal ganglion cells (mrgcs) in the eye. therefore, in vivo, melanopsin may trigger a 'seconda ... | 2015 | 26095528 |
| herg channel inhibitory daphnane diterpenoid orthoesters and polycephalones a and b with unprecedented skeletons from gnidia polycephala. | the herg channel is an important antitarget in safety pharmacology. several drugs have been withdrawn from the market or received severe usage restrictions because of herg-related cardiotoxicity. in a screening of medicinal plants for herg channel inhibition using a two-microelectrode voltage clamp assay with xenopus laevis oocytes, a dichloromethane extract of the roots of gnidia polycephala reduced the peak tail herg current by 58.8 ± 13.4% (n = 3) at a concentration of 100 μg/ml. by means of ... | 2015 | 26091146 |
| functional characteristics of l1156f-cftr associated with alcoholic chronic pancreatitis in japanese. | although cystic fibrosis is rare in japanese, measurement of sweat cl(-) has suggested mild dysfunction of cystic fibrosis transmembrane conductance regulator (cftr) in some patients with chronic pancreatitis. in the present study, we have investigated the association of cftr variants and chronic pancreatitis in japanese and the functional characteristics of a japanese- and pancreatitis-specific cftr variant, l1156f. seventy patients with alcoholic chronic pancreatitis, 18 patients with idiopath ... | 2015 | 26089335 |
| direct activation of amidohydrolase domain-containing 1 gene by thyroid hormone implicates a role in the formation of adult intestinal stem cells during xenopus metamorphosis. | the t3-dependent anuran metamorphosis resembles postembryonic development in mammals, the period around birth when plasma t3 levels peak. in particular, the remodeling of the intestine during metamorphosis mimics neonatal intestinal maturation in mammals when the adult intestinal epithelial self-renewing system is established. we have been using intestinal metamorphosis to investigate how the organ-specific adult stem cells are formed during vertebrate development. early studies in xenopus laevi ... | 2015 | 26086244 |
| spermidine and ca(2+), but not na(+), can permeate nmda receptors consisting of glun1 and glun2a or glun2b in the presence of mg(2+). | n-methyl-d-aspartate receptors (nmda receptors) are known to be permeable to na(+) and ca(2+) ions. in this study, we tested whether polyamines (putrescine, spermidine, spermine), organic cations found in cells, can permeate nmda receptors expressed in xenopus laevis oocytes and hek293 cells. it was found that polyamines, especially spermidine, can permeate nmda channels expressed from glun1/glun2a or glun1/glun2b activated by glycine and glutamate. furthermore, spermidine and ca(2+) influx thro ... | 2015 | 26086092 |
| expression, sorting and transport studies for the orphan carrier slc10a4 in neuronal and non-neuronal cell lines and in xenopus laevis oocytes. | slc10a4 belongs to the solute carrier family slc10 whose founding members are the na(+)/taurocholate co-transporting polypeptide (ntcp, slc10a1) and the apical sodium-dependent bile acid transporter (asbt, slc10a2). these carriers maintain the enterohepatic circulation of bile acids between the liver and the gut. slc10a4 was identified as a novel member of the slc10 carrier family with the highest phylogenetic relationship to ntcp. the slc10a4 protein was detected in synaptic vesicles of choline ... | 2015 | 26084360 |
| kbot55, purified from buthus occitanus tunetanus venom, represents the first member of a novel α-ktx subfamily. | kbot55 is a 39 amino acid peptide isolated from the venom of the tunisian scorpion buthus occitanus tunetanus. this peptide is cross-linked by 3 disulfide bridges and has a molecular mass of 4128.65da. kbot55 is very low represented in the venom and thus represents a challenge for biochemical characterization. in this study, kbot55 has been subjected to a screening on ion channels expressed in xenopus laevis oocytes. it was found that kbot55 targets voltage-gated potassium channels with high aff ... | 2016 | 26079392 |
| identification of amino acids involved in histamine potentiation of gaba a receptors. | histamine is a neurotransmitter involved in a number of physiological and neuronal functions. in mammals, such as humans, and rodents, the histaminergic neurons found in the tuberomamillary nucleus project widely throughout the central nervous system. histamine acts as positive modulator of gabaa receptors (gabaars) and, in high concentrations (10 mm), as negative modulator of the strychnine-sensitive glycine receptor. however, the exact molecular mechanisms by which histamine acts on gabaars ar ... | 2015 | 26074818 |
| recovery capabilities of xenopus laevis after exposure to cadmium and zinc. | the present investigation evaluates the recovery capabilities of xenopus laevis following 12days of exposure to 30μg cdl(-1) and 1000μg znl(-1) alone or mixed, followed by a depuration phase in laboratory conditions. focused endpoints, which were investigated at different times of depuration, are bioaccumulation of cd and zn, micronucleus induction, quantification of metallothioneins (mts), and expression of genes involved in metal toxicity mechanisms. the results show that at the end of the con ... | 2015 | 26073702 |
| molecular polymorphism and divergence of duplicated genes in tetraploid african clawed frogs (xenopus). | genome duplication creates redundancy in proteins and their interaction networks, and subsequent smaller-scale gene duplication can further amplify genetic redundancy. mutations then lead to the loss, maintenance or functional divergence of duplicated genes. genome duplication occurred many times in african clawed frogs (genus xenopus), and almost all extant species in this group evolved from a polyploid ancestor. to better understand the nature of selective constraints in a polyploid genome, we ... | 2015 | 26066830 |
| high incidence of functional ion-channel abnormalities in a consecutive long qt cohort with novel missense genetic variants of unknown significance. | the long qt syndrome (lqts) is a disorder characterized by a prolongation of the qt interval and a propensity to ventricular tachyarrhythmias, which may lead to syncope, cardiac arrest, or sudden death. our objective was to (1) determine the incidence of variants with unknown significance (vus) in a cohort of consecutive lqts patients and (2) to determine the percentage of those with novel missense vus that have demonstrable functional channel abnormalities from a single referral center. we perf ... | 2015 | 26066609 |
| intracellular microrna profiles form in the xenopus laevis oocyte that may contribute to asymmetric cell division. | asymmetric distribution of fate determinants within cells is an essential biological strategy to prepare them for asymmetric division. in this work we measure the intracellular distribution of 12 maternal micrornas (mirna) along the animal-vegetal axis of the xenopus laevis oocyte using qpcr tomography. we find the mirnas have distinct intracellular profiles that resemble two out of the three profiles we previously observed for mrnas. our results suggest that mirnas in addition to proteins and m ... | 2015 | 26059897 |
| netrin-1 directs dendritic growth and connectivity of vertebrate central neurons in vivo. | netrins are a family of extracellular proteins that function as chemotropic guidance cues for migrating cells and axons during neural development. in the visual system, netrin-1 has been shown to play a key role in retinal ganglion cell (rgc) axon growth and branching at the target, where presynaptic rgc axons form partnerships with the dendrites of tectal neurons. however, the signals that guide the connections between rgc axons and their postsynaptic partners are yet unknown. here, we explored ... | 2015 | 26058786 |
| peptoid-substituted hybrid antimicrobial peptide derived from papiliocin and magainin 2 with enhanced bacterial selectivity and anti-inflammatory activity. | antimicrobial peptides (amps) are important components of the host innate immune system. papiliocin is a 37-residue amp purified from larvae of the swallowtail butterfly papilio xuthus. magainin 2 is a 23-residue amp purified from the skin of the african clawed frog xenopus laevis. we designed an 18-residue hybrid peptide (papma) incorporating n-terminal residues 1-8 of papiliocin and n-terminal residues 4-12 of magainin 2, joined by a proline (pro) hinge. papma showed high antimicrobial activit ... | 2015 | 26053120 |
| usp18 sensitivity of peptide transporters pept1 and pept2. | usp18 (ubiquitin-like specific protease 18) is an enzyme cleaving ubiquitin from target proteins. usp18 plays a pivotal role in antiviral and antibacterial immune responses. on the other hand, ubiquitination participates in the regulation of several ion channels and transporters. usp18 sensitivity of transporters has, however, never been reported. the present study thus explored, whether usp18 modifies the activity of the peptide transporters pept1 and pept2, and whether the peptide transporters ... | 2015 | 26046984 |
| regulation of neuronal high-voltage activated ca(v)2 ca(2+) channels by the small gtpase rhoa. | high-voltage-activated (hva) ca(2+) channels are known regulators of synapse formation and transmission and play fundamental roles in neuronal pathophysiology. small gtpases of rho and rgk families, via their action on both cytoskeleton and ca(2+) channels are key molecules for these processes. while the effects of rgk gtpases on neuronal hva ca(2+) channels have been widely studied, the effects of rhoa on the hva channels remains however elusive. using heterologous expression in xenopus laevis ... | 2015 | 26044639 |
| locomotor corollary activation of trigeminal motoneurons: coupling of discrete motor behaviors. | during motor behavior, corollary discharges of the underlying motor commands inform sensory-motor systems about impending or ongoing movements. these signals generally limit the impact of self-generated sensory stimuli but also induce motor reactions that stabilize sensory perception. here, we demonstrate in isolated preparations of xenopus laevis tadpoles that locomotor corollary discharge provokes a retraction of the mechanoreceptive tentacles during fictive swimming. in the absence of sensory ... | 2015 | 26041033 |
| probing the redox states of sodium channel cysteines at the binding site of μo§-conotoxin gviij. | μo§-conotoxin gviij is a 35-amino acid peptide that readily blocks six of eight tested nav1 subunit isoforms of voltage-gated sodium channels. μo§-gviij is unusual in having an s-cysteinylated cysteine (at residue 24). a proposed reaction scheme involves the peptide-channel complex stabilized by a disulfide bond formed via thiol-disulfide exchange between cys24 of the peptide and a cys residue at neurotoxin receptor site 8 in the pore module of the channel (specifically, cys910 of rat nav1.2). t ... | 2015 | 26039939 |
| an endocannabinoid system is present in the mouse olfactory epithelium but does not modulate olfaction. | endocannabinoids modulate a diverse array of functions including progenitor cell proliferation in the central nervous system, and odorant detection and food intake in the mammalian central olfactory system and larval xenopus laevis peripheral olfactory system. however, the presence and role of endocannabinoids in the peripheral olfactory epithelium have not been examined in mammals. we found the presence of cannabinoid type 1 (cb1) and cannabinoid type 2 (cb2) receptor protein and mrna in the ol ... | 2015 | 26037800 |
| toxicological aspects of photocatalytic degradation of selected xenobiotics with nano-sized mn-doped tio2. | the toxic effects of two selected xenobiotics, bisphenol a (bpa) and atrazine (atz), were evaluated after photocatalytic degradation using nano-sized, mn-doped tio2. undoped and mn-doped tio2 nanoparticles were synthesized. the samples were characterized by x-ray diffractometry (xrd), scanning electron microscopy (sem), uv-vis-diffuse reflectance spectra (drs), x-ray fluorescence spectroscopy (xrf), and bet surface area. the photocatalytic efficiency of the undoped and mn-doped tio2 was evaluate ... | 2015 | 26037099 |
| investigation of blood flow and the effect of vasoactive substances in cutaneous blood vessels of xenopus laevis. | in the present study, a preparation of frog skin was presented, which can be used to demonstrate the basic concepts of blood flow regulation in a very clear and attractive way to high school and university students. in a freshly euthanized xenopus, a patch of abdominal skin was exposed from the internal side and viewed with a usb microscope while it remained connected to a functioning circulatory system. in this way, it was possible to obtain sharp images of arteries and veins and to visualize b ... | 2015 | 26031724 |
| inhibition of monocarboxylate transporter by n-cyanosulphonamide s0859. | the synthetic compound n-cyanosulphonamide s0859 has been described as a selective inhibitor of sodium-bicarbonate cotransporters (nbc, slc4) in mammalian heart (ch'en et al., 2008). first, for comparison, the electrogenic human nbce1 (slc4a4) was heterologously expressed in xenopus laevis oocytes, where its transport activity was inhibited by s0859 with an ic50 of 9µm. the activity of monocarboxylate transporter (mct) isoforms 1, 2, and 4 (slc16a1, slc16a7, slc16a3), which transport lactate, py ... | 2015 | 26027796 |
| [comparative characteristics of free-living ultramicroscopical bacteria obtained from extremal biotopes]. | we isolated 50 strains of free-living ultrasmall bacteria with a cell volume that varies from 0.02 to 1.3 microm3 from a range of extremal natural biotopes, namely permafrost soils, oil slime, soils, lake silt, thermal swamp moss, and the skin integuments of the clawed frog, xenopus laevis. of them, 15 isolates, characterized by a cell size of less than 0.1 microm3 and a genome size from 1.5 to 2.4 mb, were subsumed to ultramicrobacteria belonging to different philogenetic groups (alphaproteobac ... | 2015 | 26027350 |
| g-quadruplex dna and ligand interaction in living cells using nmr spectroscopy. | gathering structural information from biologically relevant molecules inside living cells has always been a challenging task. in this work, we have used multidimensional nmr spectroscopy to probe dna g-quadruplexes inside living xenopus laevis oocytes. some of these structures can be found in key regions of chromosomes. g-quadruplexes are considered potential anticancer therapeutic targets and several lines of evidence indirectly point out roles in key biological processes, such as cell prolifer ... | 2015 | 28706695 |
| desformylflustrabromine modulates α4β2 neuronal nicotinic acetylcholine receptor high- and low-sensitivity isoforms at allosteric clefts containing the β2 subunit. | alterations in expression patterns of α4β2 nicotinic acetylcholine receptors have been demonstrated to alter cholinergic neurotransmission and are implicated in neurologic disorders, including autism, nicotine addiction, alzheimer's disease, and parkinson's disease. positive allosteric modulators (pams) represent promising new leads in the development of therapeutic agents for the treatment of these disorders. this study investigates the involvement of the β2-containing subunit interfaces of α4β ... | 2015 | 26025967 |