Project description:Premetamorphic Xenopus laevis tadpole tail respond to thyroid hormone by resorption. The goal of this experiment is to identify the genes involved in the TH-induced resorption tadpole tail and compare it to TH-induced proliferation and differentiation program in tadpole limb and brain. Xenopus tadpoles (NF54) were treated with 100 nM T3 in 0.1 x MMR for another 24h and 48h or without T3 for 48h (control group). NF 61 tadpoles were in 0.1 X MMR till they reached NF stage 62. The tails were dissected after the experiment. Keywords: development or differentiation design,organism part comparison design,reference design,replicate design,time series design
Project description:Premetamorphic Xenopus laevis tadpoles brain ventricle cells respond to thyroid hormone by proliferation and subsequent differentiation. The goal of this experiment is to identify the genes involved in the TH-induced proliferation pathway in tadpole brain and compare it to TH-induced proliferation and differentiation program in tadpole limb. Xenopus tadpoles (NF54) were treated with 1 mM methimazole in 0.1 X MMR solution for 1 week to block the endogenous TH production and reduce the TH present in the system of the tadpole. They were then treated with 100 nM T3 in 1 mM methimazole and 0.1 x MMR for another 24h and 48h or without T3 for 48h (control group). Brains from the tadpoles were dissected at the end of the experiment. Keywords: development or differentiation design,organism part comparison design,reference design,replicate design,time series design
Project description:Premetamorphic Xenopus laevis tadpoles limb bud cells respond to thyroid hormone by proliferation and subsequent differentiation. The goal of this experiment is to identify the genes involved in the TH-induced proliferation pathway in developing tadpole limb bud and compare it to TH-induced proliferation and differentiation program in tadpole brain. Xenopus tadpoles (NF54) were treated with 1 mM methimazole in 0.1 X MMR solution for 1 week to block the endogenous TH production and reduce the TH present in the system of the tadpole. They were then treated with 100 nM T3 in 1 mM methimazole and 0.1 x MMR for another 24h and 48h or without T3 for 48h (control group). Limb buds were dissected at the end of the experiment. Keywords: development or differentiation design,organism part comparison design,reference design,replicate design,time series design
Project description:Premetamorphic Xenopus laevis tadpole tail respond to thyroid hormone by resorption. The goal of this experiment is to identify the genes involved in the TH-induced resorption tadpole tail and compare it to TH-induced proliferation and differentiation program in tadpole limb and brain. Xenopus tadpoles (NF54) were treated with 100 nM T3(triioodthyronine) in 0.1 x MMR for another 24h and 48h or without T3 for 48h (control group). NF 61 tadpoles were in 0.1 X MMR till they reached NF stage 62. The tails were dissected after the experiment.
Project description:Thyroid hormone (TH) controls the remodeling of the pancreas and the liver. TH-induces dedifferentiation of the exocrine pancreas to a progenitor state (Proc. Nat. Acad Sci. 105, 8962-8967 (2008)) and it remodels the endocrine pancreas (Dev. Biol. 328, 384-391 (2009)). The redifferentiated frog pancreas resembles closely the pancreas of other typical vertebrates. Two pancreas arrays were carried out. The first one studied gene expression changes at different developmental stages of Xenopus laevis during metamorphosis. The second array studies gene expression changes at varying times after the addition of TH to premetamorphic tadpoles. Keywords: cell cycle design,co-expression design,reference design,time series design Thyroid hormone (TH) controls remodeling of the pancreas. The micro array was carried out to identify changes in gene expression between the tadpole and frog pancreas. This is part 1, done on the 44K Xenopus platform. This dataset was used only for one pancreas experiment with several data points (control, 12h, 24h, 48h and frog). Each was made in triplicate. Samples in all 3 parts of the study received the same thyroid hormone levels.
Project description:Premetamorphic Xenopus laevis tadpoles limbs develop in response to thyroid hormone by proliferation and subsequent differentiation. We have previously reported that inhibiting the thyroid hormone action using a dominant negative receptor in limbs of developing tadpoles inhibits its growth and the tadpole limb has almost no muscle. The goal of this experiment is to study the role of thyroid hormone in the maintenance of limb muscle using transgenic tadpoles carrying a doxycyline inducible dominant negative thyroid receptor transgene expressed exclusively in the muscle using a muscle specific promoter and identify the genes involved in the degenerative process . F1 progeny of transgenic Xenopus frogs and their nontransgenic siblings (at stages NF55 and NF66) were treated with 50µg doxycycline hyclate in 0.1 X MMR solution for 2 weeks or 6 weeks to induce the over-expression of the transgene. Limbs from the tadpoles were dissected at the end of the experiment. Keywords: development or differentiation design,reference design,replicate design,time series design
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.
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.