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characterization of the r162w kir7.1 mutation associated with snowflake vitreoretinopathy.kcnj13 encodes kir7.1, an inwardly rectifying k(+) channel that is expressed in multiple ion-transporting epithelia. a mutation in kcnj13 resulting in an arginine-to-tryptophan change at residue 162 (r162w) of kir7.1 was associated with snowflake vitreoretinal degeneration, an inherited autosomal-dominant disease characterized by vitreous degeneration and mild retinal degeneration. we used the xenopus laevis oocyte expression system to assess the functional properties of the r162w (mutant) kir7. ...201323255580
[characteristic and effect of cadmium on atp-activated currents mediated by p2x4 receptors].to investigate the characteristic and effect of cadmium on atp-activated currents (i(atp)) mediated by p2x4 purinoceptors.201223252297
cardiac differentiation in xenopus is initiated by mespa.future cardiac repair strategies will require a profound understanding of the principles underlying cardiovascular differentiation. owing to its extracorporal and rapid development, xenopus laevis provides an ideal experimental system to address these issues in vivo. whereas mammalian mesp1 is currently regarded as the earliest marker for the cardiovascular system, several mesp1-related factors from xenopus-mespa, mespb, and mespo-have been assigned only to somitogenesis so far. we, therefore, a ...201323241315
employing the biology of successful fracture repair to heal critical size bone defects.bone has the natural ability to remodel and repair. fractures and small noncritical size bone defects undergo regenerative healing via coordinated concurrent development of skeletal and vascular elements in a soft cartilage callus environment. within this environment bone regeneration recapitulates many of the same cellular and molecular mechanisms that form embryonic bone. angiogenesis is intimately involved with embryonic bone formation and with both endochondral and intramembranous bone forma ...201323239235
neurogenesis is required for behavioral recovery after injury in the visual system of xenopus laevis.nonmammalian vertebrates have a remarkable capacity to regenerate brain tissue in response to central nervous system (cns) injury. nevertheless, it is not clear whether animals recover lost function after injury or whether injury-induced cell proliferation mediates recovery. we address these questions using the visual system and visually-guided behavior in xenopus laevis tadpoles. we established a reproducible means to produce a unilateral focal injury to optic tectal neurons without damaging re ...201323238877
regeneration of functional pronephric proximal tubules after partial nephrectomy in xenopus laevis.while the renal system is critical for maintaining homeostatic equilibrium within the body, it is also susceptible to various kinds of damage. tubule dysfunction in particular contributes to acute renal injury and chronic kidney disease in millions of patients worldwide. because current treatments are highly invasive and often unavailable, gaining a better understanding of the regenerative capacity of renal structures is vital. although the effects of various types of acute damage have been prev ...201323233460
withaferin a induces proteasome inhibition, endoplasmic reticulum stress, the heat shock response and acquisition of thermotolerance.in the present study, withaferin a (wa), a steroidal lactone with anti-inflammatory and anti-tumor properties, inhibited proteasome activity and induced endoplasmic reticulum (er) and cytoplasmic hsp accumulation in xenopus laevis a6 kidney epithelial cells. proteasomal inhibition by wa was indicated by an accumulation of ubiquitinated protein and a decrease in chymotrypsin-like activity. additionally, immunoblot analysis revealed that treatment of cells with wa induced the accumulation of hsps ...201223226310
implication of the smn complex in the biogenesis and steady state level of the signal recognition particle.spinal muscular atrophy is a severe motor neuron disease caused by reduced levels of the ubiquitous survival of motoneurons (smn) protein. smn is part of a complex that is essential for spliceosomal usnrnp biogenesis. signal recognition particle (srp) is a ribonucleoprotein particle crucial for co-translational targeting of secretory and membrane proteins to the endoplasmic reticulum. srp biogenesis is a nucleo-cytoplasmic multistep process in which the protein components, except srp54, assemble ...201323221635
axonal growth towards xenopus skin in vitro is mediated by matrix metalloproteinase activity.we have previously demonstrated that the growth of peripheral nervous system axons is strongly attracted towards limb buds and skin explants in vitro. here, we show that directed axonal growth towards skin explants of xenopus laevis in matrigel is associated with expression of matrix metalloproteinase (mmp)-18 and also other mmps, and that this long-range neurotropic activity is inhibited by the broad-spectrum mmp inhibitors bb-94 and gm6001. we also show that forced expression of mmp-18 in cos- ...201323216618
connexin26-mediated transfer of laterality cues in xenopus.a cilia-driven leftward flow of extracellular fluid breaks bilateral symmetry in the dorsal midline of the neurula stage vertebrate embryo. the left-specific nodal signaling cascade in the lateral plate mesoderm (lpm) is key to asymmetric morphogenesis and placement of organs during subsequent development. the nature of the initial asymmetric cue(s) as well as the transfer of information from the midline to the left side has remained elusive. gap junctional communication has been previously invo ...201223213439
resting potential, oncogene-induced tumorigenesis, and metastasis: the bioelectric basis of cancer in vivo.cancer may result from localized failure of instructive cues that normally orchestrate cell behaviors toward the patterning needs of the organism. steady-state gradients of transmembrane voltage (v(mem)) in non-neural cells are instructive, epigenetic signals that regulate pattern formation during embryogenesis and morphostatic repair. here, we review molecular data on the role of bioelectric cues in cancer and present new findings in the xenopus laevis model on how the microenvironment's biophy ...201223196890
characterization of a novel α-conotoxin from conus textile that selectively targets α6/α3β2β3 nicotinic acetylcholine receptors.α6β2 nicotinic acetylcholine receptors (nachrs) expressed by dopaminergic neurons in the cns are potential therapeutic targets for the treatment of several neuropsychiatric diseases, including nicotine addiction and parkinson disease. however, recent studies indicate that the α6 subunit can also associate with the β4 subunit to form α6β4 nachrs that are difficult to pharmacologically distinguish from α6β2, α3β4, and α3β2 subtypes. the current study characterized a novel 16-amino acid α-conotoxin ...201323184959
in vivo activation of azipropofol prolongs anesthesia and reveals synaptic targets.general anesthetic photolabels have been instrumental in discovering and confirming protein binding partners and binding sites of these promiscuous ligands. we report the in vivo photoactivation of meta-azipropofol, a potent analog of propofol, in xenopus laevis tadpoles. covalent adduction of meta-azipropofol in vivo prolongs the primary pharmacologic effect of general anesthetics in a behavioral phenotype we termed "optoanesthesia." coupling this behavior with a tritiated probe, we performed u ...201323184948
rapid stimulation of human renal enac by camp in xenopus laevis oocytes.among the compensatory mechanisms restoring circulating blood volume after severe haemorrhage, increased vasopressin secretion enhances water permeability of distal nephron segments and stimulates na(+) reabsorption in cortical collecting tubules via epithelial sodium channels (enac). the ability of vasopressin to upregulate enac via a camp-dependent mechanism in the medium to long term is well established. this study addressed the acute regulatory effect of camp on human enac (henac) and thus t ...201323184731
regulation of primitive hematopoiesis by class i histone deacetylases.histone deacetylases (hdacs) regulate multiple developmental processes and cellular functions. however, their roles in blood development have not been determined, and in xenopus laevis a specific function for hdacs has yet to be identified. here, we employed the class i selective hdac inhibitor, valproic acid (vpa), to show that hdac activity is required for primitive hematopoiesis.201323184530
predictability of visual perturbation during locomotion: implications for corrective efference copy signaling.in guiding adaptive behavior, efference copy signals or corollary discharge are traditionally considered to serve as predictors of self-generated sensory inputs and by interfering with their central processing are able to counter unwanted consequences of an animal's own actions. here, in a speculative reflection on this issue, we consider a different functional role for such intrinsic predictive signaling, namely in stabilizing gaze during locomotion where resultant changes in head orientation i ...201223179256
inhibition of the thyroid hormone pathway in xenopus laevis by 2-mercaptobenzothiazole.determining the effects of chemicals on the thyroid system is an important aspect of evaluating chemical safety from an endocrine disrupter perspective. since there are numerous chemicals to test and limited resources, prioritizing chemicals for subsequent in vivo testing is critical. 2-mercaptobenzothiazole (mbt), a high production volume chemical, was tested and shown to inhibit thyroid peroxidase (tpo) enzyme activity in vitro, a key enzyme necessary for the synthesis of thyroid hormone. to d ...201323178179
n-terminal phosphorylation of p60 katanin directly regulates microtubule severing.proteins of the aaa (atpases associated with various cellular activities) family often have complex modes of regulation due to their central position in important cellular processes. p60 katanin, an aaa protein that severs and depolymerizes microtubules, is subject to multiple modes of regulation including a phosphorylation in the n-terminal domain involved in mitotic control of severing. phosphorylation decreases severing activity in xenopus egg extracts and is involved in controlling spindle l ...201323178168
the new kcnq2 activator 4-chlor-n-(6-chlor-pyridin-3-yl)-benzamid displays anticonvulsant potential.kcnq2-5 channels are voltage-gated potassium channels that regulate neuronal excitability and represent suitable targets for the treatment of hyperexcitability disorders. the effect of chlor-n-(6-chlor-pyridin-3-yl)-benzamid was tested on kcnq subtypes for its ability to alter neuronal excitability and for its anticonvulsant potential.201323176257
a competition-based mechanism mediates developmental refinement of tectal neuron receptive fields.neural activity plays an important role in development and maturation of visual circuits in the brain. activity can be instructive in refining visual projections by directly mediating formation and elimination of specific synaptic contacts through competition-based mechanisms. alternatively, activity could be permissive-regulating production of factors that create a favorable environment for circuit refinement. here we used the xenopus laevis tadpole visual system to test whether activity is ins ...201223175839
early development of the thymus in xenopus laevis.although xenopus laevis has been a model of choice for comparative and developmental studies of the immune system, little is known about organogenesis of the thymus, a primary lymphoid organ in vertebrates. here we examined the expression of three transcription factors that have been functionally associated with pharyngeal gland development, gcm2, hoxa3, and foxn1, and evaluated the neural crest contribution to thymus development.201323172757
bath salts components mephedrone and methylenedioxypyrovalerone (mdpv) act synergistically at the human dopamine transporter.bath salts is the street name for drug combinations that contain synthetic cathinone analogues, among them possibly mephedrone (meph) and certainly methylenedioxypyrovalerone (mdpv). in animal studies, cathinone and certain cathinone analogues release dopamine (da), similar to the action of amphetamine (amph) and methamphetamine (meth). amph and meth act on the human da transporter (hdat); thus, we investigated meph and mdpv acting at hdat.201323170765
on-off asymmetries in oxygen consumption kinetics of single xenopus laevis skeletal muscle fibres suggest higher-order control.the mechanisms controlling skeletal muscle oxygen consumption (v(o)₂) during exercise are not well understood. we determined whether first-order control could explain v(o)₂kinetics at contractions onset (v(o)₂(on)) and cessation (v(o)₂off)) in single skeletal muscle fibres differing in oxdidative capacity, and across stimulation intensities up to v(o)₂(max). xenopus laevis fibres (n = 21) were suspended in a sealed chamber with a fast response p(o)₂ electrode to measure v(o)₂ every second before ...201323165768
overexpression of a wheat aquaporin gene, taaqp8, enhances salt stress tolerance in transgenic tobacco.aquaporin (aqp) proteins have been shown to transport water and other small molecules through biological membranes, which is crucial for plants to combat salt stress. however, the precise role of aqp genes in salt stress response is not completely understood in plants. in this study, a pip1 subgroup aqp gene, designated taaqp8, was cloned and characterized from wheat. transient expression of taaqp8-green fluorescent protein (gfp) fusion protein revealed its localization in the plasma membrane. t ...201223161856
microrna-mediated mrna translation activation in quiescent cells and oocytes involves recruitment of a nuclear micrornp.micrornas can promote translation of specific mrnas in quiescent (g0) mammalian cells and immature xenopus laevis oocytes. we report that microrna-mediated upregulation of target mrnas in oocytes is dependent on nuclear entry of the microrna; cytoplasmically-injected microrna repress target mrnas. components of the activation micrornp, ago, fxr1 (fxr1-iso-a) and mir16 are present in the nucleus and cytoplasm. importantly, microrna target mrnas for upregulation, myt1, tnfα and a reporter bearing ...201223150790
generation of transgenic x. laevis models of retinal degeneration.transgenic models are invaluable tools for researching retinal degenerative disease mechanisms. however, they are time-consuming and expensive to generate and maintain. we have developed an alternative to transgenic rodent models of retinal degeneration using transgenic xenopus laevis. we have optimized this system to allow rapid analysis of transgene effects in primary transgenic animals, thereby providing an alternative to establishing transgenic lines, and simultaneously allowing rigorous com ...201323150364
study of the dna damage checkpoint using xenopus egg extracts.on a daily basis, cells are subjected to a variety of endogenous and environmental insults. to combat these insults, cells have evolved dna damage checkpoint signaling as a surveillance mechanism to sense dna damage and direct cellular responses to dna damage. there are several groups of proteins called sensors, transducers and effectors involved in dna damage checkpoint signaling (figure 1). in this complex signaling pathway, atr (atm and rad3-related) is one of the major kinases that can respo ...201223149695
co-expression of na(v)β subunits alters the kinetics of inhibition of voltage-gated sodium channels by pore-blocking μ-conotoxins.voltage-gated sodium channels (vgscs) are assembled from two classes of subunits, a pore-bearing α-subunit (nav 1) and one or two accessory β-subunits (nav βs). neurons in mammals can express one or more of seven isoforms of nav 1 and one or more of four isoforms of nav β. the peptide μ-conotoxins, like the guanidinium alkaloids tetrodotoxin (ttx) and saxitoxin (stx), inhibit vgscs by blocking the pore in nav 1. hitherto, the effects of nav β-subunit co-expression on the activity of these toxins ...201323146020
thyroid hormone regulation of adult intestinal stem cell development: mechanisms and evolutionary conservations.the adult mammalian intestine has long been used as a model to study adult stem cell function and tissue renewal as the intestinal epithelium is constantly undergoing self-renewal throughout adult life. this is accomplished through the proliferation and subsequent differentiation of the adult stem cells located in the crypt. the development of this self-renewal system is, however, poorly understood. a number of studies suggest that the formation/maturation of the adult intestine is conserved in ...201223136549
pearls are novel cajal body-like structures in the xenopus germinal vesicle that are dependent on rna pol iii transcription.we have identified novel nuclear bodies, which we call pearls, in the giant oocyte nuclei of xenopus laevis and xenopus tropicalis. pearls are attached to the lampbrush chromosomes at specific loci that are transcribed by rna polymerase iii, and they disappear after inhibition of polymerase iii activity. pearls are enriched for small cajal body-specific rnas (scarnas), which are guide rnas that modify specific nucleotides on splicing snrnas. surprisingly, snrnas themselves are not present in pea ...201223135638
local application of drugs to study nicotinic acetylcholine receptor function in mouse brain slices.tobacco use leads to numerous health problems, including cancer, heart disease, emphysema, and stroke. addiction to cigarette smoking is a prevalent neuropsychiatric disorder that stems from the biophysical and cellular actions of nicotine on nicotinic acetylcholine receptors (nachrs) throughout the central nervous system. understanding the various nachr subtypes that exist in brain areas relevant to nicotine addiction is a major priority. experiments that employ electrophysiology techniques suc ...201223128482
xenbase: expansion and updates of the xenopus model organism database.xenbase (http://www.xenbase.org) is a model organism database that provides genomic, molecular, cellular and developmental biology content to biomedical researchers working with the frog, xenopus and xenopus data to workers using other model organisms. as an amphibian xenopus serves as a useful evolutionary bridge between invertebrates and more complex vertebrates such as birds and mammals. xenbase content is collated from a variety of external sources using automated and semi-automated pipeline ...201323125366
identification of small molecule inhibitors of cytokinesis and single cell wound repair.screening of small molecule libraries offers the potential to identify compounds that inhibit specific biological processes and, ultimately, to identify macromolecules that are important players in such processes. to date, however, most screens of small molecule libraries have focused on identification of compounds that inhibit known proteins or particular steps in a given process, and have emphasized automated primary screens. here we have used "low tech" in vivo primary screens to identify sma ...201223125193
evaluation of in vitro and in vivo toxic effects of newly synthesized benzimidazole-based organophosphorus compounds.this paper reports the toxic properties of eight newly synthesized benzimidazole-based organophosphorus (op) compounds in xenopus laevis in both in vivo and in vitro conditions. for both experiments, a commercial solution of azinphos methyl (azm, gusathion m wp25) was used as a reference compound. the 24-h median lethal concentrations (lc₅₀) of all tested compounds were determined for 46th stage tadpoles in the range of 9.54-140.0 μm. for evaluation of the lethality of the compounds, the activit ...201323116621
discovery of novel human aquaporin-1 blockers.human aquaporin-1 (haqp1) is a water channel found in many tissues and potentially involved in several human pathologies. selective inhibitors of haqp1 are discussed as novel treatment opportunities for glaucoma, brain edema, inflammatory pain, and certain types of cancer. however, only very few potent and chemically attractive blockers have been reported to date. in this study we present three novel haqp1 blockers that have been identified by virtual screening and inhibit water flux through haq ...201323113556
interactions of external k+ and internal blockers in a weak inward-rectifier k+ channel.we investigated the effects of changing extracellular k(+) concentrations on block of the weak inward-rectifier k(+) channel kir1.1b (romk2) by the three intracellular cations mg(2+), na(+), and tea(+). single-channel currents were monitored in inside-out patches made from xenopus laevis oocytes expressing the channels. with 110 mm k(+) in the inside (cytoplasmic) solution and 11 mm k(+) in the outside (extracellular) solution, these three cations blocked k(+) currents with a range of apparent a ...201223109715
functional and structural effects of amyloid-β aggregate on xenopus laevis oocytes.xenopus laevis oocytes exposed to amyloid-β aggregate generated oscillatory electric activity (blips) that was recorded by two-microelectrode voltage-clamp. the cells exhibited a series of "spontaneous" blips ranging in amplitude from 3.8 ± 0.9 na at the beginning of the recordings to 6.8 ± 1.7 na after 15 min of exposure to 1 μm aggregate. these blips were similar in amplitude to those induced by the channel-forming antimicrobial agents amphotericin b (7.8 ± 1.2 na) and gramicidin (6.3 ± 1.1 na ...201223104436
a mutation in the β-subunit of enac identified in a patient with cystic fibrosis-like symptoms has a gain-of-function effect.in some patients with atypical cystic fibrosis (cf), only one allele of the cf transmembrane conductance regulator (cftr) gene is affected. mutations of the epithelial sodium channel (enac) may contribute to the pathophysiology of the disease in these patients. to functionally characterize a mutation in the β-subunit of enac (βv348m) recently identified in a patient with severe cf-like symptoms (mutesa et al. 2009), we expressed wild-type (wt) αβγenac or mutant αβv348mγenac in xenopus laevis ooc ...201323087020
the vestibuloocular reflex of tadpoles (xenopus laevis) after knock-down of the isthmus-related transcription factor xtcf-4.development of the amphibian vestibular organ is regulated by molecular and neuronal mechanisms and by environmental input. the molecular component includes inductive signals derived from neural tissue of the hindbrain and from the surrounding mesoderm. the integrity of hindbrain patterning, on the other hand, depends on instructive signals from the isthmus organizer of the midbrain, including the transcription factor xtcf-4. if the development of the vestibular system depends on the integrity o ...201323077160
cell type-specific translational profiling in the xenopus laevis retina.translating ribosome affinity purification (trap), a method recently developed to generate cell type-specific translational profiles, relies on creating transgenic lines of animals in which a tagged ribosomal protein is placed under regulatory control of a cell type-specific promoter. an antibody is then used to affinity purify the tagged ribosomes so that cell type-specific mrnas can be isolated from whole tissue lysates.201223074098
molecular mechanism for depolarization-induced modulation of kv channel closure.voltage-dependent potassium (kv) channels provide the repolarizing power that shapes the action potential duration and helps control the firing frequency of neurons. the k(+) permeation through the channel pore is controlled by an intracellularly located bundle-crossing (bc) gate that communicates with the voltage-sensing domains (vsds). during prolonged membrane depolarizations, most kv channels display c-type inactivation that halts k(+) conduction through constriction of the k(+) selectivity ...201223071266
activation of group i metabotropic glutamate receptors potentiates heteromeric kainate receptors.kainate receptors (kars), a family of ionotropic glutamate receptors, are widely expressed in the central nervous system and are critically involved in synaptic transmission. kar activation is influenced by metabotropic glutamate receptor (mglu) signaling, but the underlying mechanisms are not understood. we undertook studies to examine how mglu modulation affects activation of kars. confocal immunohistochemistry of rat hippocampus and cultured rat cortex revealed colocalization of the high-affi ...201323066089
a study of subunit selectivity, mechanism and site of action of the delta selective compound 2 (ds2) at human recombinant and rodent native gaba(a) receptors.most gaba(a) receptor subtypes comprise 2α, 2β and 1γ subunit, although for some isoforms, a δ replaces a γ-subunit. extrasynaptic δ-gaba(a) receptors are important therapeutic targets, but there are few suitable pharmacological tools. we profiled ds2, the purported positive allosteric modulator (pam) of δ-gaba(a) receptors to better understand subtype selectivity, mechanism/site of action and activity at native δ-gaba(a) receptors.201323061935
on the cellular and developmental lethality of a xenopus nucleocytoplasmic hybrid.nucleocytoplasmic hybrid (cybrid) embryos result from the combination of the nucleus of one species, and the egg cytoplasm of another species. cybrid embryos can be obtained either in the haploid state by the cross-fertilization or intra-cytoplasmic injection of an enucleated egg with sperm from another species, or in the diploid state by the technique of interspecies somatic cell nuclear transfer (iscnt). cybrids that originate from the combination of the nucleus and the cytoplasm of distantly ...201223060954
disease-causing r1185c mutation of wnk4 disrupts a regulatory mechanism involving calmodulin binding and sgk1 phosphorylation sites.the r1185c mutation in wnk4 is associated with pseudohypoaldosteronism type ii (phaii). unlike other phaii-causing mutations in the acidic motif, the r1185c mutation is located in the cooh-terminal region of wnk4. the goal of the study is to determine what properties of wnk4 are disrupted by the r1185c mutation. we found that the r1185c mutation is situated in the middle of a calmodulin (cam) binding site and the mutation reduces the binding of wnk4 to ca(2+)/cam. the r1185c mutation is also clo ...201323054253
development and characterization of xl1, a xenopus laevis chondrocyte-like cell culture.we describe the development and characterization of a new cell line, designated xl1, derived from vertebra and long bones of xenopus laevis. these cells can mineralize their extracellular matrix upon addition of an inorganic phosphate donor and vitamin c, as characterized by von kossa staining. in addition they express genes such as matrix gla protein (mgp), alkaline phosphatase, type ii collagen, and retinoic acid receptors, representing a valuable tool to analyze expression and regulation of x ...201323054192
pharmacologic parameters of ms222 and physiologic changes in frogs (xenopus laevis) after immersion at anesthetic doses.we evaluated the anesthetic efficacy of ms222 (dose, 1 or 2 g/l; ph 7) administered as an immersion bath (duration, 20 min) for nonbreeding female xenopus leavis frogs (n = 33; average body weight, 103 ± 16 g). the acid acetic test, the withdrawal reflex, righting behavior, heart rate, respiratory frequency, and blood oxygen saturation were used to evaluate the level of anesthesia. acetic acid and withdrawal reflex responses were present at 30 and 60 min following immersion for the 1- and 2-g/l ...201223043812
calcium-binding protein 39 facilitates molecular interaction between ste20p proline alanine-rich kinase and oxidative stress response 1 monomers.x-ray crystallography of the catalytic domain of oxidative stress response 1 (osr1) has provided evidence for dimerization and domain swapping. however, the functional significance of dimer formation or domain swapping has yet to be addressed. in this study, we used nine glutamine residues to link the carboxyl end of one spak (related ste20 kinase) monomer to the amino end of another spak monomer to assess the role of kinase monomers versus dimers in na-k-2cl cotransporter 1 (nkcc1) activation. ...201223034389
robust photoregulation of gaba(a) receptors by allosteric modulation with a propofol analogue.photochemical switches represent a powerful method for improving pharmacological therapies and controlling cellular physiology. here we report the photoregulation of gaba(a) receptors (gaba(a)rs) by a derivative of propofol (2,6-diisopropylphenol), a gaba(a)r allosteric modulator, which we have modified to contain photoisomerizable azobenzene. using α(1)β(2)γ(2) gaba(a)rs expressed in xenopus laevis oocytes and native gaba(a)rs of isolated retinal ganglion cells, we show that the trans-azobenzen ...201223033071
the antiestrogens tamoxifen and fulvestrant abolish estrogenic impacts of 17α-ethinylestradiol on male calling behavior of xenopus laevis.various synthetic chemicals released to the environment can interfere with the endocrine system of vertebrates. many of these endocrine disrupting compounds (edcs) exhibit estrogenic activity and can interfere with sexual development and reproductive physiology. more recently, also chemicals with different modes of action (moas), such as antiestrogenic, androgenic and antiandrogenic edcs, have been shown to be present in the environment. however, to date edc-research primarily focuses on exposur ...201223028589
characterization of sfrp2-like in amphioxus: insights into the evolutionary conservation of wnt antagonizing function.wnt signaling plays a key role in embryonic patterning and morphogenetic movements. the secreted frizzled-related proteins (sfrps) antagonize wnt signaling, but their roles in development are poorly understood. to determine whether function of sfrps is conserved between amphioxus and vertebrates, we characterized sfrp2-like function in the amphioxus, branchiostoma belcheri tsingtauense (b. belcheri). as in other species of branchiostome, in b. belcheri, expression of sfrp2-like is restricted to ...201223017025
a maternally established soxb1/soxf axis is a conserved feature of chordate germ layer patterning.despite deep evolutionary roots in the metazoa, the gene regulatory network driving germ layer specification is surprisingly labile both between and within phyla. in xenopus laevis, soxb1- and soxf-type transcription factors are intimately involved in germ-layer specification, in part through their regulation of nodal signaling. however, it is unclear if x. laevis is representative of the ancestral vertebrate condition, as the precise roles of soxf and soxb1 in germ-layer specification vary amon ...201223016978
high ca(2+) permeability of a peptide-gated deg/enac from hydra.degenerin/epithelial na(+) channels (deg/enacs) are na(+) channels that are blocked by the diuretic amiloride. in general, they are impermeable for ca(2+) or have a very low permeability for ca(2+). we describe here, however, that a deg/enac from the cnidarian hydra magnipapillata, the hydra na(+) channel (hynac), is highly permeable for ca(2+) (p(ca)/p(na) = 3.8). hynac is directly gated by hydra neuropeptides, and in xenopus laevis oocytes expressing hynacs, rfamides elicit currents with bipha ...201223008433
measurement of photon statistics with live photoreceptor cells.we analyzed the electrophysiological response of an isolated rod photoreceptor of xenopus laevis under stimulation by coherent and pseudothermal light sources. using the suction-electrode technique for single cell recordings and a fiber optics setup for light delivery allowed measurements of the major statistical characteristics of the rod response. the results indicate differences in average responses of rod cells to coherent and pseudothermal light of the same intensity and also differences in ...201223005626
regulating contractility of the actomyosin cytoskeleton by ph.the local interaction of f-actin with myosin-ii motor filaments and crosslinking proteins is crucial for the force generation, dynamics, and reorganization of the intracellular cytoskeleton. by using a bottom-up approach, we are able to show that the contractility of reconstituted active actin systems is tightly controlled by the local ph. the ph-dependent intrinsic crossbridge strength of myosin-ii is identified to account for a sharp transition of the actin/myosin-ii activity from noncontracti ...201222999933
[using of the luciferase reporter constructs for investigation of the capacity of noggin2 protein to inhibit cell signaling pathways in early xenopus laevis embryos].noggin (noggin1) protein inhibits smad1-dependent tgf-beta signaling pathway by extracellular binding of bmp proteins. recently we found two previously unknown representatives of noggin family - noggin2 and noggin4. here we investigate by using the luciferase reporter constructs the ability of noggin2 to inhibit bmp-, activin/nodal- and wnt-signaling pathways in the early xenopus laevis embryos. the effectiveness of this inhibitory activity of noggin2 is comparing with that of well-known inhibit ...201222997712
positive modulation of the α9α10 nicotinic cholinergic receptor by ascorbic acid.the activation of α9α10 nicotinic cholinergic receptors (nachrs) present at the synapse between efferent olivocochlear fibres and cochlear hair cells can prevent acoustic trauma. hence, pharmacological potentiators of these receptors could be useful therapeutically. in this work, we characterize ascorbic acid as a positive modulator of recombinant α9α10 nachrs.201322994414
klf4 is required for germ-layer differentiation and body axis patterning during xenopus embryogenesis.klf4 is a transcription factor of the family of kruppel-like factors and plays important roles in stem cell biology; however, its function during embryogenesis is unknown. here, we report the characterization of a klf4 homologue in xenopus laevis during embryogenesis. klf4 is transcribed both maternally and zygotically and the transcript is ubiquitous in embryos during germ-layer formation. klf4 promotes endoderm differentiation in both nodal/activin-dependent and -independent manners. moreover, ...201222992953
oleoyl-l-carnitine inhibits glycine transport by glyt2.concentrations of extracellular glycine in the cns are regulated by two na(+)/cl(-) -dependent glycine transporters, glyt1 and glyt2. selective inhibitors of glyt1 have been developed for the treatment of schizophrenia, whilst selective inhibitors of glyt2 are analgesic in animal models of pain. we have assessed a series of endogenous lipids as inhibitors of glyt1 and glyt2.201322978602
central representation of spatial and temporal surface wave parameters in the african clawed frog.xenopus laevis employs mechano-sensory lateral lines to, for instance, capture arthropods on the surface of turbid waters with poor visibility based on incoming wave signals. to characterise central representations of surface waves emitted from different locations, responses to several wave parameters were extracellularly recorded across brainstem, midbrain and thalamic areas. overall, 339 of 411 statistically analysed responses showed significantly altered spike rates during the presentation of ...201222976940
the genomic structure and the expression profile of the xenopus laevis transthyretin gene.transthyretin (ttr) is a major thyroid hormone-binding protein in the amphibian tadpole whose plasma mrna and protein levels are altered during metamorphosis. while the temporal and spatial expression patterns and genomic structure of the ttr gene are well studied in higher vertebrates, detailed expression pattern in the extrahepatic tissues, the transcriptional regulation, and the genomic structure have not yet been identified in amphibians. in this study, we attempted to elucidate these mechan ...201222975210
pressure-selective modulation of nmda receptor subtypes may reflect 3d structural differences.professional deep-water divers exposed to high pressure (hp) above 1.1 mpa suffer from high pressure neurological syndrome (hpns), which is associated with cns hyperexcitability. we have previously reported that hp augments n-methyl-d-aspartate receptor (nmdar) synaptic responses, increases neuronal excitability, and potentially causes irreversible neuronal damage. we now report that hp (10.1 mpa) differentially affects eight specific nmdar subtypes. glun1(1a or 1b) was co-expressed with one of ...201222973194
xenopus laevis ric-3 enhances the functional expression of the c. elegans homomeric nicotinic receptor, acr-16, in xenopus oocytes.ric-3 enhances the functional expression of certain nicotinic acetylcholine receptors (nachrs) in vertebrates and invertebrates and increases the availability of functional receptors in cultured cells and xenopus laevis oocytes. maximal activity of ric-3 may be cell-type dependent, so neither mammalian nor invertebrate proteins is optimal in amphibian oocytes. we cloned the x. laevis ric-3 cdna and tested the frog protein in oocyte expression studies. x. laevis ric-3 shares 52% amino acid identi ...201222970690
intracellular calcium signals display an avalanche-like behavior over multiple lengthscales.many natural phenomena display "self-organized criticality" (soc), (bak et al., 1987). this refers to spatially extended systems for which patterns of activity characterized by different lengthscales can occur with a probability density that follows a power law with pattern size. differently from power laws at phase transitions, systems displaying soc do not need the tuning of an external parameter. here we analyze intracellular calcium (ca(2+)) signals, a key component of the signaling toolkit ...201222969730
thyroid hormone signaling in the xenopus laevis embryo is functional and susceptible to endocrine disruption.thyroid hormone (th) is essential for vertebrate brain development. most research on th and neuronal development focuses on late development, mainly the perinatal period in mammals. however, in human infants neuromotor development correlates best with maternal th levels in the first trimester of pregnancy, suggesting that th signaling could affect early brain development. studying th signaling in early embryogenesis in mammals is experimentally challenging. in contrast, free-living embryos, such ...201222968643
pip2 hydrolysis stimulates the electrogenic na+-bicarbonate cotransporter nbce1-b and -c variants expressed in xenopus laevis oocytes.electrogenic na(+)-bicarbonate cotransporter nbce1 variants contribute to ph(i) regulation, and promote ion reabsorption or secretion by many epithelia. most na(+)-coupled bicarbonate transporter (ncbt) families such as nbce1 contain variants with differences primarily at the cytosolic n and/or c termini that are likely to impart on the transporters different modes of regulation. for example, n-terminal regions of nbce1 autoregulate activity. our group previously reported that cytosolic phosphat ...201222966160
plasmin and chymotrypsin have distinct preferences for channel activating cleavage sites in the γ subunit of the human epithelial sodium channel.proteolytic activation of the epithelial sodium channel (enac) involves cleavage of its γ subunit in a critical region targeted by several proteases. our aim was to identify cleavage sites in this region that are functionally important for activation of human enac by plasmin and chymotrypsin. sequence alignment revealed a putative plasmin cleavage site in human γenac (k189) that corresponds to a plasmin cleavage site (k194) in mouse γenac. we mutated this site to alanine (k189a) and expressed hu ...201222966015
characterization of the hypothalamus of xenopus laevis during development. i. the alar regions.the patterns of expression of a set of conserved developmental regulatory transcription factors and neuronal markers were analyzed in the alar hypothalamus of xenopus laevis throughout development. combined immunohistochemical and in situ hybridization techniques were used for the identification of subdivisions and their boundaries. the alar hypothalamus was located rostral to the diencephalon in the secondary prosencephalon and represents the rostral continuation of the alar territories of the ...201322965483
a general approach to break the concentration barrier in single-molecule imaging.single-molecule fluorescence imaging is often incompatible with physiological protein concentrations, as fluorescence background overwhelms an individual molecule's signal. we solve this problem with a new imaging approach called phade (photoactivation, diffusion and excitation). a protein of interest is fused to a photoactivatable protein (mkikgr) and introduced to its surface-immobilized substrate. after photoactivation of mkikgr near the surface, rapid diffusion of the unbound mkikgr fusion o ...201222961247
hydroxylated biphenyl derivatives are positive modulators of human gaba(a) receptors.a series of 7 hydroxylated biphenyl derivatives (1-7) were prepared to evaluate their ability to modulate the function of several ligand gated ion channel (lgic) recombinant receptors expressed in xenopus laevis oocytes. compounds 1, 3, 4, 6 and 7 are natural occurring compounds whereas the synthesis of compounds 2 and 5 was previously reported (delogu et al., 2004; fabbri et al., 2007). none of the compounds tested were able to modify, the activity of the strychnine-sensitive glycine receptor, ...201222959356
pou-v factor oct25 regulates early morphogenesis in xenopus laevis.pou-v class proteins like oct4 are crucial for keeping cells in an undifferentiated state. an oct4 homologue in xenopus laevis, oct25, peaks in expression during early gastrulation, when many cells are still uncommitted. nevertheless, extensive morphogenesis is taking place in all germ layers at that time. phenotypical analysis of embryos with oct25 overexpression revealed morphogenesis defects, beginning during early gastrulation and resulting in spina-bifida-like axial defects. analysis of mar ...201222957893
extracellular quaternary ammonium blockade of transient receptor potential vanilloid subtype 1 channels expressed in xenopus laevis oocytes.transient receptor potential vanilloid subtype 1 (trpv1) channels are essential nociceptive integrators in primary afferent neurons. these nonselective cation channels are inhibited by local anesthetic compounds through an undefined mechanism. here, we show that lidocaine inhibits trpv1 channels expressed in xenopus laevis oocytes, whereas the neutral local anesthetic, benzocaine, does not, suggesting that a titratable amine is required for high-affinity inhibition. consistent with this possibil ...201222956771
immunoisolation of protein complexes from xenopus.the immunoaffinity isolation of protein complexes is an essential technique for the purification and -concentration of protein complexes from cells and tissues. in this chapter we present the methodologies for the purification of proteins and protein complexes from xenopus laevis and xenopus tropicalis. specific to this protocol are the techniques for the cryolysis of xenopus cells and tissues, a procedure that limits contamination from yolk proteins while preserving endogenous protein complexes ...201222956099
investigating alternative rna splicing in xenopus.alternative splicing, the process by which distinct mature mrnas can be produced from a single primary transcript, is a key mechanism to increase the organism complexity. the generation of alternative splicing pattern is a means to expand the proteome diversity and also to control gene expression through the regulation of mrna abundance. alternative splicing is therefore particularly prevalent during development and accordingly numerous splicing events are regulated in a tissue or temporal manne ...201222956098
a simple method of transgenesis using i-scei meganuclease in xenopus.here we present a protocol for generating transgenic embryos in xenopus using i-scei meganuclease. this method relies on integration of dna constructs, containing one or two i-scei meganuclease sites. it is a simpler method than the remi method of transgenesis, and it is ideally suited for generating transgenic lines in xenopus laevis and xenopus tropicalis. in addition to it being simpler than the remi method, this protocol also results in single copy integration events rather than tandem conca ...201222956090
generating transgenic frog embryos by restriction enzyme mediated integration (remi).here we present a protocol for generating transgenic embryos in xenopus laevis and xenopus tropicalis. the method includes three steps: (1) the preparation of high-speed egg extracts, which facilitates the replacement of protamines in sperm nuclei with nucleosomes and decondenses the chromatin of sperm nuclei; (2) the isolation of sperm nuclei; and (3) the mixing of sperm nuclei, restriction enzyme, and high-speed extract in vitro, following by nuclear transplantation into unfertilized eggs to g ...201222956089
maternal mrna knock-down studies: antisense experiments using the host-transfer technique in xenopus laevis and xenopus tropicalis.the ability to inhibit the activity of maternally stored gene products in xenopus has led to numerous insights into early developmental mechanisms. oocytes can be cultured and manipulated in vitro and then implanted into the body cavity of a host female to make them competent for fertilization. here, we summarize the methods for obtaining, culturing, and fertilizing xenopus oocytes, with the goal of inhibiting maternal gene function through antisense oligonucleotide-mediated mrna knock-down. we ...201222956088
chemical genetics and drug discovery in xenopus.chemical genetics uses small molecules to modulate protein function and has the potential to perturb any biochemical event in a complex cellular context. the application of chemical genetics to dissect biological processes has become an attractive alternative to mutagenesis screens due to its technical simplicity, inexpensive reagents, and low-startup costs. xenopus embryos are particularly amenable to whole organism chemical genetic screens. here we describe the basic protocols we have develope ...201222956087
reverse genetic studies using antisense morpholino oligonucleotides.here we present a protocol, which allows loss-of-function studies in xenopus embryos using antisense morpholino oligonucleotides (mos). gene knockdown studies provide a critical method for assessing gene function in vitro and in vivo. such studies are currently performed in xenopus using primarily one of the two main methods: (1) overexpression of dominant negative constructs or (2) inhibition of gene function by using mos targeting either the initiation of translation or mrna splicing. while a ...201222956086
navigating the xenopus tropicalis genome.the frog xenopus laevis has for more than 60 years served as a model system for the study of vertebrate embryogenesis, molecular and cell biology, and physiology. recently, there has been great interest in the related species xenopus tropicalis, in part because it is diploid, unlike the allotetraploid x. laevis, and therefore amenable to forward genetics, adding to the strengths of the frog system. the genome sequence of x. tropicalis was published in 2010 and this resource is facilitating rapid ...201222956082
xenopus tropicalis as a model organism for genetics and genomics: past, present, and future.xenopus tropicalis was introduced as a model system for genetic, and then genomic research, in the early 1990s, complementing work on the widely used model organism xenopus laevis. its shorter generation time and diploid genome has facilitated a number of experimental approaches. it has permitted multigenerational experiments (e.g., preparation of transgenic lines and generation of mutant lines) that have added powerful approaches for research by the xenopus community. as a diploid animal, its s ...201222956079
transport properties of melanosomes along microtubules interpreted by a tug-of-war model with loose mechanical coupling.in this work, we explored theoretically the transport of organelles driven along microtubules by molecular motors of opposed polarities using a stochastic model that considers a langevin dynamics for the cargo, independent cargo-motor linkers and stepping motion for the motors. it has been recently proposed that the stiffness of the motor plays an important role when multiple motors collectively transport a cargo. therefore, we considered in our model the recently reported values for the stiffne ...201222952716
social discrimination by quantitative assessment of immunogenetic similarity.genes of the major histocompatibility complex (mhc) that underlie the adaptive immune system may allow vertebrates to recognize their kin. true kin-recognition genes should produce signalling products to which organisms can respond. allelic variation in the peptide-binding region (pbr) of mhc molecules determines the pool of peptides that can be presented to trigger an immune response. to examine whether these mhc peptides also might underlie assessments of genetic similarity, we tested whether ...201222951741
generation of monoclonal antibodies against the galβ1-4gal epitope: a key tool in studies of species-specific glycans expressed in fish, amphibians and birds.whereas the galβ1-4gal epitope is rarely found in mammalian glycans, it has been found in glycans of various species of non-mammalian vertebrates, such as fish, amphibians and birds. although glycans containing galβ1-4gal in these vertebrates were detected by precise structural analysis of the glycans using mass spectrometry and/or nmr spectrometry, there are no convenient methods to detect galβ1-4gal from various samples. to analyze systematically the distribution of galβ1-4gal in nature, we ge ...201322948803
reorientation and dimerization of the membrane-bound antimicrobial peptide pgla from microsecond all-atom md simulations.the membrane-active antimicrobial peptide pgla from xenopus laevis is known from solid-state (2)h-, (15)n-, and (19)f-nmr spectroscopy to occupy two distinct α-helical surface adsorbed states in membranes: a surface-bound s-state with a tilt angle of ~95° at low peptide/lipid molar ratio (p/l = 1:200), and an obliquely tilted t-state with a tilt angle of 127° at higher peptide concentration (p/l = 1:50). using a rapid molecular-dynamics insertion protocol in combination with microsecond-scale si ...201222947863
eif4a3 is required for accurate splicing of the xenopus laevis ryanodine receptor pre-mrna.the exon junction complex (ejc) plays a critical role in multiple posttranscriptional events, including rna subcellular localization, nonsense-mediated decay (nmd), and translation. we previously reported that knockdown of the ejc core component eukaryotic initiation factor 4a3 (eif4a3) results in full-body paralysis of embryos of the frog, xenopus laevis. here, we explore the cellular and molecular mechanisms underlying this phenotype. we find that cultured muscle cells derived from eif4a3 morp ...201222944195
expression of the tetraspanin family members tspan3, tspan4, tspan5 and tspan7 during xenopus laevis embryonic development.tetraspanins comprise a large family of integral membrane proteins involved in the regulation of cell adhesion, migration and fusion. in humans it consists of 33 members divided in four subfamilies. here, we examined the spatial and temporal gene expression of four related tetraspanins during the embryonic development of xenopus laevis by quantitative real-time pcr and in situ hybridization: tspan3 (encoded by the gene tm4sf8 gene) tspan4 (encoded by the gene tm4sf7), tspan5 (encoded by the gene ...201322940433
coding rate and duration of vocalizations of the frog, xenopus laevis.vocalizations involve complex rhythmic motor patterns, but the underlying temporal coding mechanisms in the nervous system are poorly understood. using a recently developed whole-brain preparation from which "fictive" vocalizations are readily elicited in vitro, we investigated the cellular basis of temporal complexity of african clawed frogs (xenopus laevis). male advertisement calls contain two alternating components--fast trills (∼300 ms) and slow trills (∼700 ms) that contain clicks repeated ...201222933794
transducing bioelectric signals into epigenetic pathways during tadpole tail regeneration.one important component of the cell-cell communication that occurs during regenerative patterning is bioelectrical signaling. in particular, the regeneration of the tail in xenopus laevis tadpoles both requires, and can be initiated at non-regenerative stages by, specific regulation of bioelectrical signaling (alteration in resting membrane potential and a subsequent change in sodium content of blastemal cells). although standing gradients of transmembrane voltage and ion concentration can provi ...201222933452
folic acid facilitates in vitro maturation of mouse and xenopus laevis oocytes.the water-soluble b vitamins, folate and folic acid, play an important role in reproductive health, but little is known about the effects of folic acid on infertility. the present study tested the hypothesis that folic acid affects oocyte maturation, a possible cause of female infertility. we have studied the in vitro maturation of mouse and xenopus oocytes. hypoxanthine (hx) was used as an inhibitor of mouse oocyte maturation to mimic in vivo conditions by maintaining high levels of cyclic-amp. ...201322932126
ancient t-independence of mucosal igx/a: gut microbiota unaffected by larval thymectomy in xenopus laevis.many studies address the influence of the gut microbiome on the immune system, but few dissect the effect of t cells on gut microbiota and mucosal responses. we have employed larval thymectomy in xenopus to study the gut microbiota with and without the influence of t lymphocytes. pyrosequencing of 16s ribosomal rna genes was used to assess the relative abundance of bacterial groups present in the stomach, small and large intestine. clostridiaceae was the most abundant family throughout the gut, ...201322929561
the grapevine root-specific aquaporin vvpip2;4n controls root hydraulic conductance and leaf gas exchange under well-watered conditions but not under water stress.we functionally characterized the grape (vitis vinifera) vvpip2;4n (for plasma membrane intrinsic protein) aquaporin gene. expression of vvpip2;4n in xenopus laevis oocytes increased their swelling rate 54-fold. northern blot and quantitative reverse transcription-polymerase chain reaction analyses showed that vvpip2;4n is the most expressed pip2 gene in root. in situ hybridization confirmed root localization in the cortical parenchyma and close to the endodermis. we then constitutively overexpr ...201222923680
crystal structure of human aurora b in complex with incenp and vx-680.we present the structure of the human aurora b kinase domain in complex with the c-terminal aurora-binding region of human incenp and the aurora kinase inhibitor vx-680. the structure unexpectedly reveals a dimeric arrangement of the aurora b:incenp complex, which was confirmed to exist in solution by analytical ultracentrifugation. the dimerization involves a domain swap of the activation loop, resulting in a different conformation of the dfg motif as compared to that seen in other kinase compl ...201222920039
functional consequences of sulfhydryl modification of the γ-aminobutyric acid transporter 1 at a single solvent-exposed cysteine residue.the aims of this study were to optimize the experimental conditions for labeling extracellularly oriented, solvent-exposed cysteine residues of γ-aminobutyric acid transporter 1 (gat1) with the membrane-impermeant sulfhydryl reagent [2-(trimethylammonium)ethyl]methanethiosulfonate (mtset) and to characterize the functional and pharmacological consequences of labeling on transporter steady-state and presteady-state kinetic properties. we expressed human gat1 in xenopus laevis oocytes and used rad ...201222918627
the c-terminal cavity of the na,k-atpase analyzed by docking and electrophysiology.the na,k-atpase is essential to all animals, since it maintains the electrochemical gradients that energize the plasma membrane. naturally occurring inhibitors of the pump from plants have been used pharmaceutically in cardiac treatment for centuries. the inhibitors block the pump by binding on its extracellular side and thereby locking it. to explore the possibilities for designing an alternative way of targeting the pump function, we have examined the structural requirements for binding to a p ...201322913437
enhancement of k2p2.1 (trek1) background currents expressed in xenopus oocytes by voltage-gated k+ channel β subunits.k(2p)2.1 (trek1) two-pore-domain potassium channels control electrical activity in the central nervous system (cns) and in the heart. auxiliary β subunits (kvβ) increase functional k+ channel diversity in the cns. based on similar tissue distribution and common functional significance of kvβ2 protein and k(2p)2.1 channels in neuronal excitability, we hypothesized that kvβ2 subunits modulate k2p2.1 currents.201222910181
wnt-11 and fz7 reduce cell adhesion in convergent extension by sequestration of papc and c-cadherin.wnt-11/planar cell polarity signaling polarizes mesodermal cells undergoing convergent extension during xenopus laevis gastrulation. these shape changes associated with lateral intercalation behavior require a dynamic modulation of cell adhesion. in this paper, we report that wnt-11/frizzled-7 (fz7) controls cell adhesion by forming separate adhesion-modulating complexes (amcs) with the paraxial protocadherin (papc; denoted as amcp) and c-cadherin (denoted as amcc) via distinct fz7 interaction d ...201222908314
effects of tributyltin on metamorphosis and gonadal differentiation of xenopus laevis at environmentally relevant concentrations.tributyltin (tbt), a well known endocrine disruptor, has high teratogenicity to embryos of amphibian (xenopus tropicalis). an amphibian metamorphosis assay (ama) and a complete ama (cama) were conducted for tbt. in ama, the body weight, the snout-to-vent length and the hind limb length of x. laevis tadpoles were decreased in tributyltin chloride (tbtcl; 12.5-200 ng/l) treatment groups after 7 days exposure. tbt greatly retarded the development of tadpoles, decreased the number of follicle and in ...201422903176
the permeability of reconstituted nuclear pores provides direct evidence for the selective phase model.nuclear pore complexes (npcs) maintain a permeability barrier between the nucleus and the cytoplasm through fg-repeat-containing nucleoporins (nups). we previously proposed a "selective phase model" in which the fg repeats interact with one another to form a sieve-like barrier that can be locally disrupted by the binding of nuclear transport receptors (ntrs), but not by inert macromolecules, allowing selective passage of ntrs and associated cargo. here, we provide direct evidence for this model ...201222901806
routing of biomolecules and transgenes' vectors in nuclei of oocytes.the molecular architecture of nuclear pore complexes (npcs), as well as the import and export of molecules through them, has been intensively studied in a variety of cells, including oocytes. however, the structures and mechanisms, involved in the transport of molecules beyond the npcs, remained unclear, until now. the specific aim of this work was, therefore, to determine, if there exist any intranuclear structures in continuum with the npcs. this information could help in explaining the mechan ...201222896814
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