In our laboratory, we use Xenopus laevis, commonly known as the African clawed frog (learn more on wikipedia). Xenopus laevis is a great model system for dissecting the molecular pathways in DNA replication and the maintenance of genomic stability. Cell-free extracts made from Xenopus eggs contain all the proteins necessary to undergo 12 rounds of cell-cycle regulated, semi-conservative DNA replication in the absence of transcription. Events in these extracts are highly synchronous, allowing the analysis of short-lived intermediates and the dissection of signal transduction cascades. Particularly, the function of essential proteins can be addressed by immunodepletion or neutralization of these proteins, coupled to rescue with recombinant proteins. Xenopus cell-free extracts are generated by centrifuging unfertilized Xenopus eggs and isolating the cytoplasmic layer. Female Xenopus can be induced to lay an abundance of eggs after hormone injection. In fact, Xenopus laevis were used as a pregnancy ...

Although thoroughly studied in terms of structural, biochemical and biophysical characteristics, the biological functions of avidins are not fully understood. Here, we expand the research on avidins by reporting xenavidin, the first avidin-like protein from a frog, which was identified as an expressed sequence tag (EST) from the Xenopus tropicalis genome project. Avidins appear to be conserved among egg-laying vertebrates [3, 4, 6] and are thought to have a role as defence proteins against microbial infections [43, 44]. Bird eggs contain egg yolk, the compartment for embryonic development, and the egg white that surrounds the egg yolk provides both nutrients and protection for the embryo. In frogs, the equivalent to egg white is called egg jelly [45]. The avidin content of egg jelly may have an important role in the embryonic development of frogs, a hypothesis that is also supported by recent studies within natural bird populations, in which the concentration of avidin in egg white appears to be ...

The community effect is an interaction among a group of many nearby precursor cells, necessary for them to maintain tissue-specific gene expression and differentiate co-ordinately. During Xenopus myogenesis, the muscle precursor cells must be in group contact throughout gastrulation in order to develop into terminally differentiated muscle. The molecular basis of this community interaction has not to date been elucidated. We have developed an assay for testing potential community factors, in which isolated muscle precursor cells are treated with a candidate protein and cultured in dispersion. We have tested a number of candidate factors and we find that only eFGF protein is able to mediate a community effect, stimulating stable muscle-specific gene expression in demonstrably single muscle precursor cells. In contrast, Xwnt8, bFGF, BMP4 and TGF(β)2 do not show this capacity. We show that eFGF is expressed in the muscle precursor cells at the right time to mediate the community effect. Moreover, ...

Genetically identical cells often show significant variation in gene expression profile and behaviour even in the same physiological condition. Notably, embryonic cells destined to the same tissue maintain a uniform transcriptional regulatory state and form a homogeneous cell group. One mechanism to keep the homogeneity within embryonic tissues is the so-called community effect in animal development. The community effect is an interaction among a group of many nearby precursor cells, and is necessary for them to maintain tissue-specific gene expression and differentiate in a coordinated manner. Although it has been shown that the cell-cell communication by a diffusible factor plays a crucial role, it is not immediately obvious why a community effect needs many cells. In this work, we propose a model of the community effect in development, which consists in a linear gene cascade and cell-cell communication. We examined the properties of the model theoretically using a combination of stochastic and

The amphibian Xenopus has long been a comparative model system of choice for a number of different biological research areas, including immunology. Specifically, the evolutionary distance between amphibians and mammals, including humans, allows for the study of both species-specific adaptations, as well as conserved features of the immune system. Furthermore, the Xenopus genus includes species with multiple levels of polyploidy, thereby providing a unique model to study whole genome duplication and its effects thereof on individual genes. To better exploit this amphibian model, the development and innovative applications of novel research tools have been a priority. In this regard, recent advances in adapting the transgenesis approach to Xenopus have allowed for in vivo studies of the impact of loss and gain of function of specific genes at the level of the whole organism, further enhancing the potential uses of Xenopus as an important biomedical model system. This review highlights some of the major

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TY - JOUR. T1 - The Wnt signaling mediator tcf1 is required for expression of foxd3 during Xenopus gastrulation. AU - Janssens, Sylvie. AU - van den Broekm, Olaf. AU - Davenport, Ian R.. AU - Akkers, Robbert C.. AU - Liu, Fei. AU - Veenstr, Gert Jan C.. AU - Hoppler, Stefan. AU - Vleminckx, Kris. AU - Destree, Olivier. N1 - We thank Dr. B. Gumbiner for providing the rabbit polyclonal antibody against Xenopus b-catenin and S.A. Blythe for sharing the Xenopus ChIP protocol. We thank Tim Deceunink,Thomas Roose and Yvonne Turnbull for animal care taking and Amin Bredan for editing the manuscript. O.v.d.B. and O.D. were supported by the IOP Genomics program (IGE01010), which is subsidized by the Dutch Ministry of Economic Affairs. We acknowledge additional support by the BBSRC (I.R.D. and S.H.) the AICR (F.L. and S.H.), the Netherlands Organization for Scientific Research, Earth and Life Sciences Council (NWO-ALW VIDI 864.03.002, R.C.A. and G.J.C.V.), the Research Foundation-Flanders, the ...

Exhibits mesoderm-dorsalizing activity and neural-inducing activity, but lacks mesoderm-inducing activity. Regulates the expression of specific mesodermal and neural genes. Induces convergent extension movements at the embryonic midline by activating the fgf signaling pathway to induce t/bra expression in the organizer region. Acts with wnt11 to induce Spemann organizer cells and induce axis formation. The unprocessed protein antagonizes bmp-signaling. [-] ...

Involved in the transcriptional regulation of genes required for mesoderm formation and differentiation. Causes dorsal mesodermal differentiation of animal cap ectoderm when co-expressed with wnt8 and noggin. None of these molecules causes dorsal mesoderm formation when expressed alone. Establishes the left/right axis at early gastrula stage by directly up-regulating mesodermal expression of zic3. [-] ...

Signal transduction induced by generations of second messengers from membrane phospholipids is a major regulatory mechanism in the control of cell proliferation. Indeed, oncogenic p21ras alters the intracellular levels of phospholipid metabolites in both mammalian cells and Xenopus oocytes. However, it is still controversial whether this alteration it is biologically significant. We have analyzed the ras-induced signal transduction pathway in Xenopus oocytes and have correlated its mechanism of activation with that of the three most relevant phospholipases (PLs). After microinjection, ras-p21 induces a rapid PLD activation followed by a late PLA2 activation. By contrast, phosphatidylcholine-specific PLC was not activated under similar conditions. When each of these PLs was studied for its ability to activate intracellular signalling kinases, all of them were found to activate maturation-promoting factor efficiently. However, only PLD was able to activate MAP kinase and S6 kinase II, a similar ...

For over a century, amphibian embryos have been a source of significant insight into developmental mechanisms, including fundamental discoveries about the process of induction. The recently developed transgenesis for Xenopus offers new approaches to these poorly understood processes, particularly wh …

All modes of Xenopus research (embryos, cell-free extracts, and oocytes) are commonly used in direct studies of human disease genes and to study the basic science underlying initiation and progression of cancer.[19] Xenopus embryos for in vivo studies of human disease gene function: Xenopus embryos are large and easily manipulated, and moreover, thousands of embryos can be obtained in a single day. Indeed, Xenopus was the first vertebrate animal for which methods were developed to allow rapid analysis of gene function using misexpression (by mRNA injection [20]). Injection of mRNA in Xenopus that led to the cloning of interferon.[21] Moreover, the use of morpholino-antisense oligonucleotides for gene knockdowns in vertebrate embryos, which is now widely used, was first developed by Janet Heasman using Xenopus.[22] In recent years, these approaches have played in important role in studies of human disease genes. The mechanism of action for several genes mutated in human cystic kidney disorders ...

Membrane potential and resistance were measured in eggs, cleavage stages and blastulae of the South African toad Xenopus laevis, using intracellular microelectrodes.. The membrane potential increased from −6·5 ± 2mV in eggs to −57 ± 8·0mV at the mid-blastula stage.. The input resistance of fertile eggs ranged from 0·5 MΩ to 5·0 MΩ corresponding to a specific resistance of 20-200kΩcm2. During the first two or three division cycles the input resistance usually decreased by a factor of 2-10 and then subsequently rose during the blastula stages from a mean value of 600 ± 100kΩ at stage 5 to 2·0 ± 0·5 MΩ at stage 8.. At all developmental stages examined, point polarization of a surface cell in the embryo by rectangular current pulses of 0·5−6 × 10−8 A produced voltage deflexions in other surface cells. This was seen even when several (7-8) cell junctions intervened between the current passing and voltage recording microelectrodes at distances of more than 1 mm. These ...

ID XENTR44_2_PE17 STANDARD; PRT; 490 AA. AC XENTR44_2_PE17; Q6GL03; DT 00-JAN-0000 (Rel. 1, Created) DT 00-JAN-0000 (Rel. 2, Last sequence update) DT 00-JAN-0000 (Rel. 3, Last annotation update) DE SubName: Full=Ariadne homolog 2; (XENTR44_2.PE17). GN Name=arih2; Synonyms=Arih2; ORFNames=TNeu126e05.1-001; OS XENOPUS (SILURANA) TROPICALIS. OC Eukaryota; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; OC Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; OC Sarcopterygii; Tetrapoda; Amphibia; Batrachia; Anura; Mesobatrachia; OC Pipoidea; Pipidae; Xenopodinae; Xenopus. OX NCBI_TaxID=8364; RN [0] RP -.; RG -.; RL -.; CC -!- SEQ. DATA ORIGIN: Translated from the HOGENOM CDS XENTR44_2.PE17. CC Xenopus tropicalis scaffold scaffold_44 JGI4.1 partial sequence CC 1000001..1992362 annotated by Ensembl CC -!- ANNOTATIONS ORIGIN:Q6GL03_XENTR CC -!- SIMILARITY: Contains 1 IBR-type zinc finger. CC -!- GENE_FAMILY: HOG000216611 [ FAMILY / ALN / TREE ] DR ...

In Drosophila embryos, the dorsal gene, a member of the rel family of transcription factors, is a maternal gene required for dorsal/ventral axis specification and mesoderm and neural migration and differentiation. In this report, the presence and distribution of Xrel-1 protein, a Xenopus homologue o …

Xenopus laevis is an essential model organism in several areas of biology. In addition to the key attributes of these embryos for in vivo imaging, cell-free extracts from Xenopus provide among the most powerful in vitro systems for studies of cell and molecular biology. A complete sequence of the X. laevis genome is an essential resource for accurate identification of peptides for mass-spec analyses, for cloning of an ORFeome, for identifying evolutionarily conserved regulatory regions, and for design of morpholino-oligonucleotides for gene knockdowns. The Wallingford and Marcotte labs have obtained funding from the Texas Institute for Drug and Diagnostic Development (TI3D), in coordination with projects funded by the National Institutes of Health, to begin sequencing of the X. laevis genome. We are primarily working with Scott Hunicke-Smith at the University of Texas Genome Sequencing and Analysis facility, with funding sufficient for ~20x coverage of the X. laevis genome using ABI SOLiD ...

Xenopus laevis is an essential model organism in several areas of biology. In addition to the key attributes of these embryos for in vivo imaging, cell-free extracts from Xenopus provide among the most powerful in vitro systems for studies of cell and molecular biology. A complete sequence of the X. laevis genome is an essential resource for accurate identification of peptides for mass-spec analyses, for cloning of an ORFeome, for identifying evolutionarily conserved regulatory regions, and for design of morpholino-oligonucleotides for gene knockdowns. The Wallingford and Marcotte labs obtained funding from the Texas Institute for Drug and Diagnostic Development (TI3D), in conjunction with projects funded by the National Institutes of Health, to begin sequencing of the X. laevis genome. We began the project with Scott Hunicke-Smith at the University of Texas Genome Sequencing and Analysis facility, with funding sufficient for ~20x coverage of the X. laevis genome using ABI SOLiD next-generation ...

Xenopus laloo protein: involved in induction of mesoderm by fibroblast growth factor; isolated from Xenopus laevis; amino acid sequence in first source; GenBank AF081803

UNSPECIFIED. (1987) THE DEVELOPMENT OF ANIMAL CAP CELLS IN XENOPUS - A MEASURE OF THE START OF ANIMAL CAP COMPETENCE TO FORM MESODERM. DEVELOPMENT, 101 (3). pp. 557-563. ISSN 0950-1991 ...

Xenopus MLC3F protein: marker of somitic muscle differentiation; isolated from Xenopus laevis; amino acid sequence in first source

Protein phosphatase 1 (PP1) is essential for cell division, and participates in the regulation of glycogen metabolism, muscle contractility and protein synthesis. Promotes nuclear envelope reassembly by targeting nuclear membrane vesicles to chromatin at the end of mitosis. Acts by dephosphorylating membrane proteins such as lamin B receptor (lbr) to regulate the binding of membrane proteins to chromatin (By similarity).

Xenopus embryos contain a considerable amount of a polysialo-ganglioside not yet fully characterized; in this paper, we will refer to it as ganglioside XI. Preliminary experiments indicate asialo-GMI as the core structure of the ganglioside XI and pa

BioAssay record AID 145963 submitted by ChEMBL: Inhibition of the NMB evoked increases in chloride currents in xenopus oocytes expressing human NMB receptor.

A novel role of TCF family in body axis formation. Revolutionary high impact discoveries are described, elucidating the missing link in the Wnt pathway and protein-TCF combinations with dual functions. By studying the primary axis formation of Xenopus laevis, it was firstly shown that, in combination with beta-catenin, TCF acts as a potent activator of proto-oncogenes. Secondly, it was discovered that in combination with the Groucho family of proteins, TCF acts as suppressor of oncogene transcription. Stronlgy suggesting that TCF controls oncogene transcription in a dual fashion. These discoveries contributed to the origination of a major area of cancer research and opened multiple angles for cancer therapy development ...

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TY - JOUR. T1 - The heat shock response in xenopus oocytes, embryos, and somatic cells. T2 - A regulatory role for chromatin. AU - Landsberger, N.. AU - Ranjan, M.. AU - Almouzni, G.. AU - Stump, D.. AU - Wolffe, A. P.. PY - 1995. Y1 - 1995. N2 - The heat shock response in Xenopus laevis has been reported to be developmentally regulated at the transcriptional level. We find that the heat shock response of an exogenous Xenopus hsp70 gene introduced into Xenopus oocytes, embryos, and somatic cells is dependent on the transcriptional assay conditions employed. Under conditions of efficient chromatin assembly, transcription from the Xenopus hsp70 gene promoter is repressed in oocytes and embryos, yet the promoter responds to heat shock by activating transcription. Under conditions of inefficient chromatin assembly, the Xenopus hsp70 gene is constitutively active in oocytes and somatic cells. Our results resolve previous controversy concerning the existence of a heat shock response for the hsp70 ...

The African clawed frogs Xenopus laevis and Xenopus tropicalis are prominent animal model organisms. Xenopus research contributes to the understanding of genetic, developmental and molecular mechanisms underlying human disease. The Xenopus Anatomy Ontology (XAO) reflects the anatomy and embryological development of Xenopus. The XAO provides consistent terminology that can be applied to anatomical feature descriptions along with a set of relationships that indicate how each anatomical entity is related to others in the embryo, tadpole, or adult frog. The XAO is integral to the functionality of Xenbase ( http://www.xenbase.org ), the Xenopus model organism database. We significantly expanded the XAO in the last five years by adding 612 anatomical terms, 2934 relationships between them, 640 synonyms, and 547 ontology cross-references. Each term now has a definition, so database users and curators can be certain they are selecting the correct term

This approach effectively reduces the size of the cDNA library to be screened and increases the probability of successful isolation of the target cDNA. The vocal apparatus of the clawed frog is designed for underwater sound production (Deuchar, 1975). The first step of this physiological process seems to involve a target site at the oocyte membrane, as shown by a variety of experimental data (4). Here we demonstrate cytoplasmic microinjection of Xenopus laevis oocytes with a nuclear import substrate, as well as preparation of the injected oocytes for visualization by … Their large nuclei and mitochondrial masses are clearly visible in the intact oocyte. The incision is sutured with surgical silk and the frog is placed in shallow water in a small tank to allow it to recover from anesthesia before placing it in a special tank for postoperative frogs. XENOPUS OOCYTES The oocyte from the South African clawed frog Xenopus laevis is an often used functional expression system. Two species of Xenopus ...

Xenopus (/ˈzɛnəpəs/) (Gk., ξενος, xenos=strange, πους, pous=foot, commonly known as the clawed frog) is a genus of highly aquatic frogs native to sub-Saharan Africa. Twenty species are currently described in the Xenopus genus. The two best-known species of this genus are Xenopus laevis and Xenopus tropicalis, which are commonly studied as model organisms for developmental biology, cell biology, toxicology, neuroscience and for modelling human disease and birth defects. The genus is also known for its polyploidy, with some species having up to 12 sets of chromosomes. All species of Xenopus have flattened, somewhat egg-shaped and streamlined bodies, and very slippery skin (because of a protective mucus covering). The frogs skin is smooth, but with a lateral line sensory organ that has a stitch-like appearance. The frogs are all excellent swimmers and have powerful, fully webbed toes, though the fingers lack webbing. Three of the toes on each foot have conspicuous black claws. The ...

The first 12 cell divisions of Xenopus laevis embryos do not require gene transcription. This means that the regulation of gene expression during this period is controlled at post transcriptional levels and makes Xenopus early development a potentially interesting biological system with which to study the mechanisms involved. We describe here the stability characteristics of several maternal Xenopus mRNAs which are deadenylated soon after fertilisation (J. Paris and M. Philippe, Dev. Biol., in press). We show that these mRNAs were only degraded in the embryo after the midblastula transition (MBT), when gene transcription was initiated. The kinetics with which the deadenylated maternal mRNAs decreased in the post-MBT embryos showed sequence specificity. The degradation of these mRNAs after the MBT was inhibited by cycloheximide but was not affected by dactinomycin. Therefore, the destabilization of these mRNAs does not appear to be initiated by new embryonic gene transcripts. Sequence comparisons ...

Nine peptides with differential growth inhibitory activity against Escherichia coli and Staphylococcus aureus were isolated from norepinephrine-stimulated skin secretions of the tetraploid frog Xenopus borealis Parker, 1936 (Pipidae). Structural characterization of the peptides demonstrated that they were orthologous to magainin-2 (1 peptide), peptide glycine-leucine-amide, PGLa (2 peptides), caerulein-precursor fragments, CPF (4 peptides), and xenopsin-precursor fragments, XPF (2 peptides), previously isolated from Xenopus laevis and X. amieti. In addition, a second magainin-related peptide (G**KFLHSAGKFGKAFLGEVMIG) containing a two amino acid residue deletion compared with magainin-2 was identified that had only weak antimicrobial activity. The peptide with the greatest potential for development into a therapeutically valuable anti-infective agent was CPF-B1 (GLGSLLGKAFKIGLKTVGKMMGGAPREQ) with MIC=5 microM against E. coli, MIC=5 microM against S. aureus, and MIC=25 microM against Candida albicans, and

In this work, we report an efficient method to easily study transmitter receptors originally assembled in cultured cell lines and then microtransplanted to a sturdy and convenient host cell system, the Xenopus oocyte. This method has been recently used to transplant assembled transmitter receptors from human brain to Xenopus oocyte (7), following a method developed a few years ago to microtransplant AcChoRs and chloride channels from the electric organ of Torpedo to the Xenopus oocyte membrane (5, 6). Here, we injected membrane vesicles prepared from cultured cell lines, and this approach led to a rapid incorporation of neurotransmitter receptors in the oocyte plasma membrane. In this way, functional AMPA-type GluR1, α7-AcChoRs, and α4β2-AcChoRs from cultured cells were microtransplanted to the oocytes, and their respective transmitter-activated currents were analyzed.. We report here that the gross electrophysiological and pharmacological characteristics of the transmitter-gated receptors ...

TY - JOUR. T1 - Xenopus Staufen is a component of a ribonucleoprotein complex containing Vg1 RNA and kinesin. AU - Yoon, Young J.. AU - Mowry, Kimberly L.. PY - 2004/7. Y1 - 2004/7. N2 - RNA localization is a key mechanism for generating cell and developmental polarity in a wide variety of organisms. We have performed studies to investigate a role for the Xenopus homolog of the double-stranded RNA-binding protein, Staufen, in RNA localization during oogenesis. We have found that Xenopus Staufen (XStau) is present in a ribonucleoprotein complex, and associates with both a kinesin motor protein and vegetally localized RNAs Vg1 and VegT. A functional role for XStau was revealed through expression of a dominant-negative version that blocks localization of Vg1 RNA in vivo. Our results suggest a central role for XStau in RNA localization in Xenopus oocytes, and provide evidence that Staufen is a conserved link between specific mRNAs and the RNA localization machinery.. AB - RNA localization is a key ...

TY - JOUR. T1 - RNA transport to the vegetal cortex of Xenopus oocytes. AU - Zhou, Yi. AU - King, Mary Lou. N1 - Funding Information: We thank Kim L. Mowry for providing us with the XβG, XβG-340/3′, and pSP73XβM5′ constructs, Joel K. Yisraeli for sharing his in situ hybridization protocol, and the members of the King laboratory, especially Jian Zhang and Caryl Forristall, for helpful advice and discussions. This was supported by NIH Grant GM 33932 to M. L. King.. PY - 1996/10/10. Y1 - 1996/10/10. N2 - Xcat-2 RNA, a component of the germ plasm in Xenopus, localizes with the mitochondrial cloud material to the vegetal cortex in stage II oocytes. Vg1 RNA also localizes to the vegetal cortex, but later in stage III/IV oocytes, using a microtubule dependent pathway. To further analyze the mechanisms involved in RNA transport, in situ hybridization and autoradiography were used to follow the localization of endogenous Vg1 and injected Xcat-2 transcripts in stage IV oocytes. We show that Xcat-2 ...

The vertebrate Otx gene family is related to otd, a gene contributing to head development in Drosophila. We previously reported on the expression of Xotx2 gene, homologous to the murine Otx2 gene, during early Xenopus development. In the present paper we report an extensive analysis of the expression pattern of Xotx2 during later stages of development and also the cloning and developmental expression of two additional Otx Xenopus genes, Xotx1 and Xotx4. These latter two genes bear a good degree of homology to murine Otx1, higher for Xotx1 than for Xorx4. Both these genes are expressed in the forebrain and midbrain regions and their developmental patterns of expression are very similar, although not perfectly superimposable. Spatial and temporal expression patterns of the three Xotx genes suggest that they may be involved in the early subdivision of the rostral brain, providing antero-posterior positional information within the most anterior districts of the neuraxis. The three Xotx genes are ...

BioAssay record AID 710275 submitted by ChEMBL: Antagonist activity at rat GluK1 receptor expressed in Xenopus oocytes by two-electrode voltage-clamp at membrane potential -60 to -80 mV electrophysiology assay.

The common laboratory frog Xenopus laevis has puzzled researchers because it has twice the normal number of genes. A newly published genome sequence shows why: between 15 and 20 million years ago, two different species interbred and produced a hybrid, which then mated with its parent species to eventually form a new organism with a doubled genome. The frog has since adapted to the excess by losing or disabling many of these genes.

The goal of this laboratory course is to introduce vertebrate developmental biology to undergraduate students, emphasizing both classical and contemporary aspects of this field. During the course, the students combine the use of living Xenopus laevis material with active tutorial participation, with the aim of illustrating how the fertilized egg can generate the diversity of cell types and complexity of pattern seen only a few days later in the embryo. Special emphasis is given to the observation and manipulation of living material. The laboratory course includes a comprehensive analysis of both oogenesis and early development and is divided into two overlapping parts that combine tutorial and practical approaches. The first part is devoted to oogenesis; oocytes are sorted out, allowed to mature in vitro and observed in histological section. In the second part, students perform an in vitro fertilization of Xenopus eggs and a mesoderm and neural induction assay of animal cap explants. Successful

Author: Schmidt, A. et al.; Genre: Journal Article; Published in Print: 2005-02-15; Keywords: cell cycle; anaphase-promoting complex/cyclosome; Xenopus; polo-like kinase; cytostatic factor; mitotic exit; Title: Xenopus polo-like kinase Plx1 regulates XErp1, a novel inhibitor of APC/C activity

TY - JOUR. T1 - Cloning and expression of Xenopus laevis xSox12 cDNA. AU - Komatsu, Naoki. AU - Hiraoka, Yoshiki. AU - Shiozawa, Masahide. AU - Ogawa, Motoyuki. AU - Aiso, Sadakazu. PY - 1996/3/1. Y1 - 1996/3/1. N2 - A family of SRY-related genes has been termed SOX. We have isolated and sequenced a cDNA encoding xSox12 from Xenopus laevis ovary. The cDNA contained an open reading frame (ORF) coding for 470 amino acids encompassing an HMG box characteristic of the SOX family, a leucine zipper motif and glutamine-rich segments. The size of the xSox12 mRNA was determined to be 3.0 knt by Northern analysis. The ovary was the most prominent in the expression of the Sox mRNA among the various tissues of adult frog as far as examined.. AB - A family of SRY-related genes has been termed SOX. We have isolated and sequenced a cDNA encoding xSox12 from Xenopus laevis ovary. The cDNA contained an open reading frame (ORF) coding for 470 amino acids encompassing an HMG box characteristic of the SOX family, a ...

An ontology of anatomical, cellular, and gene function phenotypes in Xenopus, the African clawed frogs. The Xenopus Phenotype Ontology represents and standardizes anatomical, cellular, and gene function phenotypes in Xenopus, the African clawed frogs. The XPO is being designed primarily to support phenotype curation in Xenbase, the model organism database for Xenopus, and to facilitate mappings between frog phenotypes and human disease ...

TY - JOUR. T1 - Wnt6 expression in epidermis and epithelial tissues during Xenopus organogenesis. AU - Lavery, Danielle L.. AU - Davenport, Ian R.. AU - Turnbull, Yvonne D.. AU - Wheeler, Grant N.. AU - Hoppler, Stefan. PY - 2008/3. Y1 - 2008/3. N2 - Here, we report the localization within embryonic tissues of xWnt6 protein; together with the temporal and spatial expression of Xenopus laevis Wnt6 mRNA. Wnt6 expression in Xenopus embryos is low until later stages of neurulation, when it is predominantly found in the surface ectoderm. Wnt6 expression increases during early organogenesis in the epidermis overlaying several developing organs, including the eye, heart, and pronephros. At later stages of development, Wnt6 mRNA and protein generally localize in epithelial tissues and specifically within the epithelial tissues of these developing organs. Wnt6 localization correlates closely with sites of both epithelial to mesenchymal transformations and mesenchymal to epithelial transformations. ...

The toxin alpha-sarcin specifically cuts 28 S rRNA at a single position 393 nucleotides from its 3 end in isolated rat liver polysomes, provided the ribosomes are pretreated with EDTA or puromycin (Endo, Y. & Wool, I. G. (1982) J. Biol. Chem. 257, 9054-9060). In addition, alpha-sarcin behaves as a purine-specific RNase on deproteinized RNA, cleaving on the 3 side of purines in both single- and double-stranded RNA (Endo, Y., Huber, P. W., and Wool, I. G. (1983) J. Biol. Chem. 258, 2662-2667). Since alpha-sarcin does not readily enter tissue culture cells, we have injected it into Xenopus oocytes in order to determine whether the toxin cleaves after all purines or if it specifically makes a single cut in 28 S rRNA in intact cells. We report here that in oocytes alpha-sarcin specifically cuts 28 S rRNA 377 nucleotides from its 3 end, even when used at concentrations that would degrade deproteinized RNA. alpha-Sarcin does not behave as a general nuclease when injected into Xenopus oocytes nor does it

TY - JOUR. T1 - Characterization of glutamate receptors induced in Xenopus oocytes after injection of rat brain mRNA. AU - Hirono, Chikara. AU - Ito, Isao. AU - Yamagishi, Shunichi. AU - Sugiyama, Hiroyuki. PY - 1988/12. Y1 - 1988/12. N2 - Xenopus oocytes in which poly(A)+ mRNA isolated from rat brains were previously injected, exhibited at least 3 categories of current responses to excitatory amino acids. They were oscillatory responses to glutamate (Glu) or quisqualate (QA), smooth large responses to kainate (KA), and smooth small responses to Glu and QA. Oscillatory responses were mediated by a metabotropic type of Glu receptor which is coupled to a G-protein but not directly to an ionic channel. Amplitudes of smooth Glu responses and smooth QA responses were similar in size, and were not additive to each other, suggesting a common receptor mediating both responses. l-Glutamylglycine inhibited KA responses in a competitive manner without affecting smooth Glu/QA responses, indicating that KA ...

Background: Astaxanthin (ATX) is a lipophilic compound found in many marine organisms. Studies have shown that ATX has many strong biological properties, including antioxidant, antiviral, anticancer, cardiovascular, anti-inflammatory, neuro-protective and anti-diabetic activities. However, no research has elucidated the effect of ATX on ionic channels. ATX can be extracted from shrimp by-products. Our work aims to characterize ATX cell targets to lend value to marine by-products. Methods: We used the Xenopus oocytes cell model to characterize the pharmacological target of ATX among endogenous Xenopus oocytes ionic channels and to analyze the effects of all carotenoid-extract samples prepared from shrimp by-products using a supercritical fluid extraction (SFE) method. Results: ATX inhibits amiloride-sensitive sodium conductance, xINa, in a dose-dependent manner with an IC50 of 0.14 µg, a maximum inhibition of 75% and a Hill coefficient of 0.68. It does not affect the potential of half ...

Rödder, D., Ihlow, F., Courant, J., Secondi, J., Herrel, A., Rebelo, R., Measey, G. J., et al. (2017): Global realized niche divergence in the African clawed frog Xenopus laevis. - Ecology and Evolution 2017: 1-15; DOI: 10.1002/ece3.3010

Poly (A) binding proteins are intimately implicated in controlling a number of events in mRNA metabolism from nuclear polyadenylation to cytoplasmic translation and stability. The known poly(A) binding proteins can be divided into three distinct structural groups (prototypes PABP1, PABPN1/PABP2 and Nab2p) and two functional families, showing that similar functions can be accomplished by differing structural units. This has prompted us to perform a screen for novel poly(A) binding proteins using Xenopus laevis. A novel poly(A) binding protein of 32 kDa (p32) was identified. Sequence analysis showed that p32 has about 50% identity to the known nuclear poly(A) binding proteins (PABPN1) but is more closely related to a group of mammalian proteins of unknown function. The expression of Xenopus laevis ePABP2 is restricted to early embryos. Accordingly, we propose that p32 is the founder member of a novel class of poly(A) binding proteins named ePABP2.

TY - JOUR. T1 - Cell behaviors associated with somite segmentation and rotation in Xenopus laevis. AU - Afonin, Bonnie. AU - Ho, Minh. AU - Gustin, Jean K.. AU - Meloty-Kapella, Caroline. AU - Domingo, Carmen R.. PY - 2006/12/1. Y1 - 2006/12/1. N2 - During vertebrate development the formation of somites is a critical step, as these structures will give rise to the vertebrae, muscle, and dermis. In Xenopus laevis, somitogenesis consists of the partitioning of the presomitic mesoderm into somites, which undergo a 90-degree rotation to become aligned parallel to the notochord. Using a membrane-targeted green fluorescent protein to visualize cell outlines, we examined the individual cell shape changes occurring during somitogenesis. We show that this process is the result of specific, coordinated cell behaviors beginning with the mediolateral elongation of cells in the anterior presomitic mesoderm and then the subsequent bending of these elongated cells to become oriented parallel with the ...

Ca2+-activated Cl- channels (CaCCs) participate in many important physiological processes. However, the lack of effective and selective blockers has hindered the study of these channels, mostly due to the lack of good assay system. Here, we have developed a reliable drug screening method for better blockers of CaCCs, using the endogeneous CaCCs in Xenopus laevis oocytes and two-electrode voltage-clamp (TEVC) technique. Oocytes were prepared with a treatment of Ca2+ ionophore, which was followed by a treatment of thapsigargin which depletes Ca2+ stores to eliminate any contribution of Ca2+ release. TEVC was performed with micropipette containing chelerythrine to prevent PKC dependent run-up or run-down. Under these conditions, Ca2+-activated Cl- currents induced by bath application of Ca2+ to oocytes showed stable peak amplitude when repetitively activated, allowing us to test several concentrations of a test compound from one oocyte. Inhibitory activities of commercially available blockers and

In animals like Drosophila, C. elegans, zebrafish and Xenopus, the primordial germ cells (PGC), the precursors of the gametes, are specified through the inheritance of germ plasm. Early PGC development is regulated by the genetic program coded by unique maternal factors in the germ plasm. However, the biological functions of these germ plasm components and their molecular mechanisms are poorly understood. We found that Dzip1 (Daz-interacting protein1) is a novel component of germ plasm in Xenopus oocytes and embryos. The loss-of-function analysis showed that Dzip1 regulates the first wave of PGC proliferation. Overexpression of Dzip1 and Xvelo stabilize each other in the germ plasm during oocyte maturation. In vitro analysis suggests that Dzip1 decreases the solubility of Xvelo and induces Xvelo to form aggregates in the cytoplasm. Therefore we argue that Dzip1, by interacting and stabilizing Xvelo, regulates the integrity of germ plasm. In addition, our results reveal that Dzip1, by interacting ...

tadpole-spinal-cord-models This is the source code for three compuational models used for generating connectivity and swimming functionality of spinal cord neurons in the Xenopus tadpoles using biological data. 1. The first model uses biological data to reconstruct a complete map of synaptic interactions between spinal neuron (anatomical connectome), in the folder anatomical model. 2. The second model generalizes the anatomical model by averaging a number of anatomical connectomes and thus generating a matrix of connection probabilities between the neurons, in the folder probabilistic model. 3. The third model uses the previous two to generate connectivity between neurons and simulates the dynamics of this circuit using Neuron (tested with version 7.3), in the folder functional model. A README file contained in the folder of each piece of the model explains how to run the simulations and give a description of the models. For a more complete description of these models have a look at ...

During the conversion to the mitotic state, higher eukaryotic cells activate a cascade of reactions which result in the disintegration of the nuclear envelope, the condensation of the DNA into chromosomes, and the reorganization of the cytoskeleton. In Xenopus, the induction of the mitotic state appears to be under the control of a cytoplasmic factor(s) known as mitosis-promoting factor or MPF. We have developed a rapid and highly sensitive version of an in vitro assay for MPF. The assay uses reconstituted nuclei in interphase cytoplasm from activated Xenopus eggs. The MPF-induced conversion from interphase to mitosis is conveniently monitored by the visual observation of the loss of the nuclear envelope from the substrate nuclei. At near saturating concentrations of MPF, nuclear breakdown requires 20-30 min. Preincubation experiments have revealed that the action of MPF requires only a few minutes and that the disassembly process itself takes up the remainder of the incubation period. Using ...

Delineation of apical and basolateral membrane domains is a critical step in the epithelialization of the outer layer of cells in the embryo. We have examined the initiation of polarized membrane traffic in Xenopus and show that membrane traffic is not polarized in oocytes but polarized membrane domains appear at first cleavage. The following proteins encoded by injected RNA transcripts were used as markers to monitor membrane traffic: (a) VSV G, a transmembrane glycoprotein preferentially inserted into the basolateral surface of polarized epithelial cells; (b) GThy-1, a fusion protein of VSV G and Thy-1 that is localized to the apical domains of polarized epithelial cells; and (c) prolactin, a peptide hormone that is not polarly secreted. In immature oocytes, there is no polarity in the expression of VSV G or GThy-1, as shown by the constitutive expression of both proteins at the surface in the animal and vegetal hemispheres. At meiotic maturation, membrane traffic to the surface is blocked; ...

TY - JOUR. T1 - Chromatin immunoprecipitation for studying transcriptional regulation in Xenopus oocytes and tadpoles.. AU - Stewart, David. AU - Tomita, Akihiro. AU - Shi, Yun Bo. AU - Wong, Jiemin. N1 - Copyright: This record is sourced from MEDLINE/PubMed, a database of the U.S. National Library of Medicine. PY - 2006. Y1 - 2006. N2 - Understanding the accurate temporal and spatial regulation of gene expression during development requires knowledge of the spectrum of transcription factors and cofactors involved and their functional interplay with chromatin. Chromatin immunoprecipitation (ChIP) has become a powerful technique that allows us to do so. A typical ChIP assay involves (1) treating cells or tissues with formaldehyde to rapidly crosslink chromatin-associated proteins to DNA, (2) shearing chromatin by sonication into small fragments, (3) immunoprecipitation of the proteins of interest, (4) reversal of crosslinking, and (5) quantitating the specific associated DNA sequences by PCR. ...

MS Thesis: EXPRESSION AND FUNCTION OF WILLIAMS SYNDROME TRANSCRIPTION FACTOR (WSTF) IN THE NEURAL DEVELOPMENT OF XENOPUS LAEVIS Imitation Switch (ISWI) is a member of the SWI2/SNF2 superfamily of ATP-dependent chromatin remodelers. Twenty different ISWI complexes have been identified so far in yeast, Drosophila, Xenopus and mammals. Three ISWI-containing complexes, WICH, ACF and CHRAC, have been characterized in Xenopus. Loss of ISWI function in Xenopus embryos results in severe defects in neural and eye development, including loss of retinal differentiation and formation of cataracts. We have begun to dissect the contributions of individual ISWI-dependent complexes to development, by using in situ hybridization and antisense morpholino knockdowns against subunits unique to different ISWI-containing complexes. Here I have investigated the WICH complex in Xenopus and have targeted the WSTF subunit. Whole mount in situ hybridization shows WSTF localized in the neural tissue including eye, brain, ...

Garcia-Morales, Carla, Liu, Chiung-Hui, Abu-Elmagd, Muhammad, Hajihosseini, Mohammad K. and Wheeler, Grant N. (2009) Frizzled-10 promotes sensory neuron development in Xenopus embryos. Developmental Biology, 335 (1). pp. 143-155. ISSN 1095-564X Full text not available from this repository. (Request a copy ...

Expression of MHC Class II Antigens During Xenopus Development. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.

p>The checksum is a form of redundancy check that is calculated from the sequence. It is useful for tracking sequence updates.,/p> ,p>It should be noted that while, in theory, two different sequences could have the same checksum value, the likelihood that this would happen is extremely low.,/p> ,p>However UniProtKB may contain entries with identical sequences in case of multiple genes (paralogs).,/p> ,p>The checksum is computed as the sequence 64-bit Cyclic Redundancy Check value (CRC64) using the generator polynomial: x,sup>64,/sup> + x,sup>4,/sup> + x,sup>3,/sup> + x + 1. The algorithm is described in the ISO 3309 standard. ,/p> ,p class=publication>Press W.H., Flannery B.P., Teukolsky S.A. and Vetterling W.T.,br /> ,strong>Cyclic redundancy and other checksums,/strong>,br /> ,a href=http://www.nrbook.com/b/bookcpdf.php>Numerical recipes in C 2nd ed., pp896-902, Cambridge University Press (1993),/a>),/p> Checksum:i ...

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Freeze fracture replica of zonula occludens junctions from the small intestine of a Xenopus laevis tadpole. The occluding junction appears as a mesh...

Freeze fracture replica of zonula occludens junctions from the small intestine of a Xenopus laevis tadpole. The occluding junction appears as a mesh...

Fertilization of the Xenopus egg leads to the asymmetrical distribution of components of the Wnt/β-catenin pathway to what will become the dorsal side of the embryo. This leads to asymmetric signaling by Nodal, a transforming growth factor-β ligand critical to embryonic axis specification and to mesoderm induction. Martello et al. found that microRNAs (miRNAs) from gastrula-stage Xenopus embryos inhibited embryonic Nodal signaling. Computational analysis revealed binding sites for two related miRNAs, miR-15 and miR-16, in the 3′ untranslated region (3′ UTR) of mRNA encoding the type II Nodal receptor Acvr2a. Activity of a reporter containing a wild-type miR-15-binding site was reduced in Xenopus embryos and human HepG2 cells compared with that of a reporter containing a mutated binding site. In addition, activity of the former was further decreased by overexpression of miR-15 or its primary precursor (pri-miR-15/16). Injection of miR-15 inhibited endogenous Nodal signaling and attenuated ...

Background: Unexpected phenotypes resulting from morpholino-mediated translational knockdown of Pitx3 in Xenopus laevis required further investigation regarding the genetic networks in which the gene might play a role. Microarray analysis was, therefore, used to assess global transcriptional changes downstream of Pitx3. Results: From the large data set generated, selected candidate genes were confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization. Conclusions: We have identified four genes as likely direct targets of Pitx3 action: Pax6, beta Crystallin-b1 (Crybb1), Hes7.1, and Hes4. Four others show equivocal promise worthy of consideration: Vent2, and Ripply2 (aka Ledgerline or Stripy), eFGF and RXRa. We also describe the expression pattern of additional and novel genes that are Pitx3-sensitive but that are unlikely to be direct targets.

The Xenopus LIM-homeodomain protein Xlim5 regulates the differential adhesion properties of early ectoderm cells.: One of the earliest lineage restriction event

Cloning of Xenopus laevis nuclear poly(A)-rich RNA sequences. Evidence for post-transcriptional control.: cDNA/RNA hybridization experiments of polysomal and nu

Xenopus laevis is one of the best ectothermic vertebrate models for studying the phylogeny and ontogeny of the immune system. The evolutionary distance of X. la...

The ultrastructure of the glomus cells of the carotid labyrinth was investigated in the anuran, Xenopus laevis. These cells show many catecholamine containing granules. About 50 cells in groups of 3-5 are located near the sinusoids. Morphologically,

The addition of cyclopamine did not produce any cyclopic embryos, though mutations were seen in both the experimental and ethanol control groups. For example, this picture of 4 day old embryos shows changes in the eyes in both groups. While cyclopamine did not produce cyclopic embryos, it did produce more drastic changes.. ...

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The vertebrate planar cell polarity (PCP) pathway has been previously found to control polarized cell behaviors rather than cell fate. We report here that disruption of Xenopus laevis orthologs of the Drosophila melanogaster ...