title: Transcriptome profiles of metamorphosis in the ornamented pygmy frog Microhyla fissipes clarify the functions of thyroid hormone receptors in metamorphosis.
abstract: Anuran metamorphosis is an excellent system in which to study postembryonic development. Studies on Xenopus (Mesobatrachia) show that thyroid hormone receptors (TRs) regulate metamorphosis in a ligand-dependent manner by coordinating the action of hundreds of genes. However, whether this mechanism is conserved among amphibians is still unknown. To understand the molecular mechanism of this universal phenomenon, we report the transcriptional profiles of the three key developmental stages in Microhyla fissipes (Neobatrachia): premetamorphosis (PM), metamorphic climax (MC) and completion of metamorphosis (CM). In total, 2,293 differentially expressed genes were identified from comparisons of transcriptomes, and these genes showed stage-specific expression patterns. Unexpectedly, we found that TRα was highly expressed in Xenopus laevis and Bufo gargarizans at premetamorphosis but showed low expression in M. fissipes. In contrast, TRβ was highly expressed during metamorphosis in M. fissipes and X. laevis. This result may imply that TRβ is essential for initiating metamorphosis, at least in M. fissipes. Thus, our work not only identifies genes that are likely to be involved in Neobatrachia metamorphosis but also clarifies the roles of unliganded TRα in regulating tadpole growth and timing of metamorphosis, which may be conserved in anurans, and the role of liganded TRβ in launching metamorphosis.
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Lanying
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Lusha
authors.initials: L
authors.lastname: Liu
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Shouhong
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Hongyuan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Jiang
mesh_terms: D000818:Animals; D001001:Anura / Q000254:growth & development*; D008675:Metamorphosis, Biological; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D011988:Receptors, Thyroid Hormone