Access to embryonic developmental stages is essential basic work for understanding how organisms develop. In this study, seven egg clutches（range 209–564 eggs） of ornamented pygmy frog Microhyla fissipes（Amphibia,...Access to embryonic developmental stages is essential basic work for understanding how organisms develop. In this study, seven egg clutches（range 209–564 eggs） of ornamented pygmy frog Microhyla fissipes（Amphibia, Anura, Microhylidae） were obtained from seven breeding pairs in laboratory. One egg clutch of them was observed for the embryonic development, and the staging table of normal development was constructed based on morphological and physiological characteristics. Forty-five developmental stages were defined for M. fissipes, and two major developmental periods were designated： 1） early embryonic development period（stages 1–28）, from fertilization to operculum completion stage, lasted for 82.6 hours at water temperature（WT） 23–25℃; 2） larval development period（stages 29–45）, from operculum completion to tail complete absorption stage, took 38 days at WT 22–26.5℃, showing that the embryos of this species develop rapidly. In addition, the tadpoles were transparent, which is similar to those in field. These characteristics suggest that M. fissipes would be a good model to study developmental biology, adaptive mechanisms from aquatic to terrestrial phases, environmental toxicology, and human disease.展开更多
To explore and enrich the molecular mechanisms of thyroid hormone receptors （TRs） in the metamorphosis of amphibians, the cDNA sequences of TRa and TRβ in Microhyla fissipes were cloned and characterized. TRa was 1...To explore and enrich the molecular mechanisms of thyroid hormone receptors （TRs） in the metamorphosis of amphibians, the cDNA sequences of TRa and TRβ in Microhyla fissipes were cloned and characterized. TRa was 1 706 bp in length with an open reading frame （ORF） of 1 257 bp encoding a predicted protein of 418 amino acids and TRβ was 1 422 bp with an ORF of 1 122 bp encoding a predicted protein of 373 amino acids. Their protein sequences contained 4 conserved domains of the nuclear receptor superfamily with two highly conserved cysteine-rich zinc fingers in the DNA-binding domain, whereas TRβ was 42 amino acids shorter in its A/B domain than TRot. Highly-conserved sequences and structures indicated their conserved functions during metamorphosis. TRa expression reached peak at 12 h and then decreased from 12 h to 48 h. While dramatically up-regulated TRβ was observed after exposure of T3 within 24 h, and it was down-regulated from 24 h to 48 h. The expression pattern of TRβ is similar to that in the natural metamorphosis. Furthermore, tadpoles treated 24 h also resembled the climax of metamorphosis tadpoles and TRβ expression had higher responsiveness than TRa to T3 in M. fissipes. These results suggest M. fissipes may serve as the model to assay environmental compounds on TH signaling disruption.展开更多
基金supported by Important Research Project of Chinese Academy of Sciences(KJZG-EW-L13)National Natural Science Foundation of China(NSFC No.31471964)+2 种基金2015 Western Light Talent Culture Project of the Chinese Academy of Sciences(Y6C3021)the Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization of CIB,CASthe Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province
文摘Access to embryonic developmental stages is essential basic work for understanding how organisms develop. In this study, seven egg clutches（range 209–564 eggs） of ornamented pygmy frog Microhyla fissipes（Amphibia, Anura, Microhylidae） were obtained from seven breeding pairs in laboratory. One egg clutch of them was observed for the embryonic development, and the staging table of normal development was constructed based on morphological and physiological characteristics. Forty-five developmental stages were defined for M. fissipes, and two major developmental periods were designated： 1） early embryonic development period（stages 1–28）, from fertilization to operculum completion stage, lasted for 82.6 hours at water temperature（WT） 23–25℃; 2） larval development period（stages 29–45）, from operculum completion to tail complete absorption stage, took 38 days at WT 22–26.5℃, showing that the embryos of this species develop rapidly. In addition, the tadpoles were transparent, which is similar to those in field. These characteristics suggest that M. fissipes would be a good model to study developmental biology, adaptive mechanisms from aquatic to terrestrial phases, environmental toxicology, and human disease.
基金funded by the Important Research Project of Chinese Academy of Sciences (KJZG-EW-L13)2015 Western Light Talent Culture Project of the Chinese Academy of Sciences (Y6C3021)the Basic Application Project of Sichuan Province (2017JY0339)
文摘To explore and enrich the molecular mechanisms of thyroid hormone receptors （TRs） in the metamorphosis of amphibians, the cDNA sequences of TRa and TRβ in Microhyla fissipes were cloned and characterized. TRa was 1 706 bp in length with an open reading frame （ORF） of 1 257 bp encoding a predicted protein of 418 amino acids and TRβ was 1 422 bp with an ORF of 1 122 bp encoding a predicted protein of 373 amino acids. Their protein sequences contained 4 conserved domains of the nuclear receptor superfamily with two highly conserved cysteine-rich zinc fingers in the DNA-binding domain, whereas TRβ was 42 amino acids shorter in its A/B domain than TRot. Highly-conserved sequences and structures indicated their conserved functions during metamorphosis. TRa expression reached peak at 12 h and then decreased from 12 h to 48 h. While dramatically up-regulated TRβ was observed after exposure of T3 within 24 h, and it was down-regulated from 24 h to 48 h. The expression pattern of TRβ is similar to that in the natural metamorphosis. Furthermore, tadpoles treated 24 h also resembled the climax of metamorphosis tadpoles and TRβ expression had higher responsiveness than TRa to T3 in M. fissipes. These results suggest M. fissipes may serve as the model to assay environmental compounds on TH signaling disruption.
