Xenopus laevis
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PROVIDER: PRJNA242206 | ENA |
REPOSITORIES: ENA
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Project description:Induction of Xenopus laevis larvae metamorphosis is dependent on exposure to TH. Metamorphosis involves the regression, growth or remodeling of almost all the tissues in the animals body. Metamorphosis in frogs is induced by thyroid hormone. Each organ system has a unique morphological and genetic program that it follows while undergoing metamorphosis involving both the upregulation and downregulation of genes. In this array we examined the change in gene expression in the tail of larvae undergoing precocious metamorphosis following induction with thyroid hormone.
2010-07-01 | GSE22643 | GEO
Project description:Induction of Xenopus laevis larvae metamorphosis is dependent on exposure to TH. Metamorphosis involves the regression, growth or remodeling of almost all the tissues in the animals body. Metamorphosis in frogs is induced by thyroid hormone. Each organ system has a unique morphological and genetic program that it follows while undergoing metamorphosis involving both the upregulation and downregulation of genes. In this array we examined the change in gene expression in the tail of larvae undergoing precocious metamorphosis following induction with thyroid hormone. Whole stage 54 xenopus larvae were exposed to either vehicle for 48 hours or 20 nM T3 for 6 or 48 hours. Total RNA was then purified from tail tissue and the samples were examined by hybridization to the Affymetrix Xenopus array. Developmental stage 51-54 Xenopus larvae were selected because these stages do not express high levels of endogenous T3 but are still capable of morphologically responding to exposure.
2010-07-30 | E-GEOD-22643 | biostudies-arrayexpress
Project description:Nanoparticles (NPs) are engineered in the nanoscale (<100nm) to have unique physico-chemical properties from their bulk counterparts. Nanosilver (nAg) is the most prevalent nanoparticle in consumer products due to its strong antimicrobial action. While nAg toxicity at high concentrations has been well described, the sublethal effects at or below regulatory guidelines are relatively unknown. Amphibian metamorphosis is mediated by thyroid hormone (TH), and initial studies indicate that low concentrations of nAg disrupt TH-dependent responses in precociously induced premetamorphic bullfrog (Rana catesbeiana) tadpoles. The present study examined the effects of environmentally-relevant nAg concentrations (LoAg, 0.018 µg/L; MedAg, 0.18 µg/L; HiAg, 1.8 µg/L) on naturally metamorphosing Xenopus laevis tadpoles in two 28-day chronic exposures beginning with pre- and prometamorphic stages, respectively. nAg was found to significantly bioaccumulate in tadpoles after 28 days. While nAg didn’t alter metamorphic timing, it increased hindlimb length during early premetamorphosis and in post-metamorphic juvenile tadpoles. Using MAGEX microarray and QPCR transcript analyses, 7 markers of nAg exposure were discovered and validated, 5 of which showed nAg-induced disruption of their TH-response. The increased mRNA abundance of two peroxidase genes suggests that nAg could generate reactive oxygen species (ROS) even at low, environmental concentrations. Furthermore, differential responsiveness to nAg was observed between developmental stages. Therefore, low concentrations of nAg had endocrine disruptive effects at both the physiological and molecular level, indicating that regulatory guidelines for silver may need revision.
2016-12-23 | GSE56012 | GEO
Project description:Xenopus laevis laevis Transcriptome or Gene expression
| PRJNA247381 | ENA
Project description:To adapt to its changing dietary environment, the digestive tract is extensively remodeled from the embryo to the adult during vertebrate development. Xenopus laevis metamorphosis is an excellent model system for studying mammalian gastrointestinal development and is used to determine the genes and signaling programs essential for intestinal development and maturation. The metamorphosing intestine can be divided into four distinct developmental time points and these were analyzed with X. laevis microarrays. Due to the high level of conservation in developmental signaling programs and homology to mammalian genes, annotations and bioinformatics analysis were based on human orthologs. Clustering of the expression patterns revealed co-expressed genes involved in essential cell processes such as apoptosis and proliferation. The two largest clusters of genes have expression peaks and troughs at the climax of metamorphosis respectively. Novel conserved gene ontology categories regulated during this period include transcriptional activity, signal transduction, and metabolic processes. Interestingly, the induced genes associated with metamorphic climax correlated with the gene expression peaks observed around birth in the mouse intestine. Thus both mouse and amphibian, share similarities at the molecular levels for intestinal maturation and remodeling, which appears to be under the influence of increasing levels of circulating thyroid hormone. Moreover, our genome-wide analysis of the intestine during development identified larval/embryo- and adult-specific genes. Detailed analysis revealed 17 larval specific genes that may represent molecular markers for human colonic cancers, while many adult specific genes are associated with dietary enzymes. This global developmental expression study provides the first detailed molecular description of intestinal remodeling and maturation during postembryonic development, which should help improve our understanding of intestinal organogenesis and human diseases. This study significantly contributes towards our understanding of the dynamics of molecular regulation during development and tissue renewal, which is important for future basic and clinical research and for medicinal applications. Time series experiment through natural metamorphosis of intestine in Xenopus laevis. Biological replicates: 3 replicates for each stage of major change during amphibian metamorphosis (except in the climax where 2 bioogical replicates were used). Universal reference design was used instead of dye-swap design for 2-color hybridizations.
2010-04-14 | E-GEOD-21303 | biostudies-arrayexpress
Project description:Hydroxylated polychlorinated biphenyls are the metabolites produced from polychlorinated biphenyls (PCBs) by drug-metabolizing enzyme cytochrome P450 1A1. These compounds are bound to transthyretin, a major plasma thyroid hormone-binding protein in amphibian tadpoles. The compounds-transthyretin complexes are transferred into the brain across the blood brain barrier in mammals. Thus these compounds are suspected to disrupt neural development in brain. We studied about the effects of hydroxylated PCBs on the thyroid system in brain using metamorphosing tadpoles of African clawed toad, Xenopus laevis. The metamorphosis assay revealed that these compounds had inhibitory effects on the thyroid hormone-induced metamorphosis. This in vivo assay was a powerful tool to detect thyroid-disrupting activities, because we were not able to detect the inhibitory effects of these compounds using thyroid hormone-responsive reporter gene assay in a cultured Xenopus cell line. A genome-wide gene expression analysis in brain following short-term exposure to these compounds demonstrated that the delay of metamorphosis and the morphological thyroid-disrupting changes could be caused partially by disruption of the thyroid hormone-induced gene expression by hydroxylated PCBs. Furthermore, we associated functional ontology terms with the transcripts whose expression were altered by thyroid hormone alone, or thyroid hormone and hydroxylated PCBs. We suggested that these approachs using a technique of bioinformatics revealed molecular mechanism of thyroid-disrupting activities in vivo. Thyroid hormones induce amphibian metamorphosis and alter a lot of thyroid hormone-responsive gene expression. We studied about the effects of hydroxylated PCBs on TH-induced gene expression. Premetamorphic tadpoles were treated with 500 nM hydroxylated PCBs in the presence of 1 nM thyroid hormone for 4 days. After exposure period total RNA was extracted from brain. Study included at least three replicate of each treatment.
2010-12-31 | E-GEOD-23154 | biostudies-arrayexpress
Project description:Hydroxylated polychlorinated biphenyls are the metabolites produced from polychlorinated biphenyls (PCBs) by drug-metabolizing enzyme cytochrome P450 1A1. These compounds are bound to transthyretin, a major plasma thyroid hormone-binding protein in amphibian tadpoles. The compounds-transthyretin complexes are transferred into the brain across the blood brain barrier in mammals. Thus these compounds are suspected to disrupt neural development in brain. We studied about the effects of hydroxylated PCBs on the thyroid system in brain using metamorphosing tadpoles of African clawed toad, Xenopus laevis. The metamorphosis assay revealed that these compounds had inhibitory effects on the thyroid hormone-induced metamorphosis. This in vivo assay was a powerful tool to detect thyroid-disrupting activities, because we were not able to detect the inhibitory effects of these compounds using thyroid hormone-responsive reporter gene assay in a cultured Xenopus cell line. A genome-wide gene expression analysis in brain following short-term exposure to these compounds demonstrated that the delay of metamorphosis and the morphological thyroid-disrupting changes could be caused partially by disruption of the thyroid hormone-induced gene expression by hydroxylated PCBs. Furthermore, we associated functional ontology terms with the transcripts whose expression were altered by thyroid hormone alone, or thyroid hormone and hydroxylated PCBs. We suggested that these approachs using a technique of bioinformatics revealed molecular mechanism of thyroid-disrupting activities in vivo.
2010-12-31 | GSE23154 | GEO