Xenopus laevis
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ABSTRACT:
PROVIDER: PRJNA98515 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Expression data for brain samples in a metamorphosis assay for thyroid axis disruption - inhibitors
| PRJNA104133 | ENA
Project description:Expression data for brain samples in a metamorphosis assay for thyroid axis disruption
| PRJNA104035 | ENA
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: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
Project description:Thyroid hormones (TH), thyroxine (T4) and 3, 5, 3’-triiodothyronine (T3), play crucial roles in regulation of growth, development and metabolism in vertebrates and are targets for endocrine disruptive agents. Perturbations in TH action can contribute to the development of disease states and the U.S. Environmental Protection Agency is developing a high throughput screen using TH-dependent metamorphosis of the Xenopus laevis tadpole as an assay platform. Currently this methodology relies on external morphological endpoints and changes in central thyroid axis parameters. However, exposure-related changes in gene expression in TH-sensitive tissue types that occur over shorter time frames have the potential to augment this screen. Using a combination of cDNA array and real time quantitative polymerase chain reaction (QPCR) analyses, this study identifies molecular markers in tissues peripheral to the central thyroid axis. We examine the hindlimb and tail of tadpoles up to 96 hours of continuous exposure to T3, T4, methimazole, propylthiouracil, or perchlorate. Several novel biomarker candidates are indicated that include transcripts encoding importin, RNA helicase II/Gu, and defender against death protein, DAD1. In combination with previously-identified biomarker candidates, these transcripts will greatly augment the predictive and diagnostic power of the Xenopus metamorphosis assay for perturbation of TH action. Keywords: time course
2007-05-12 | GSE7051 | GEO
Project description:Chronic sublethal exposure to silver nanoparticles disrupts thyroid hormone signaling during Xenopus laevis metamorphosis
| PRJNA242206 | ENA
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