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
揭示三江源国家公园典型高寒草地的冷季牧草营养特征和食草动物承载力,对园区内草地与食草动物平衡管理具有重要意义,然而相关地面研究鲜有报道.本研究于2019年12月对三江源国家公园长江源园区的紫花针茅草原、藏嵩草草甸和青藏苔草草...揭示三江源国家公园典型高寒草地的冷季牧草营养特征和食草动物承载力,对园区内草地与食草动物平衡管理具有重要意义,然而相关地面研究鲜有报道.本研究于2019年12月对三江源国家公园长江源园区的紫花针茅草原、藏嵩草草甸和青藏苔草草原进行调查取样,分析了该地区冷季牧草地上现存量和营养品质,同时结合农业行业标准(NY/T635-2015)核算了冷季数量承载力、可消化蛋白承载力和代谢能承载力.结果表明:(1)冷季牧草干物质现存量表现为藏嵩草草甸(103.03 g DM/m^2)>紫花针茅草原(72.24 g DM/m^2)>青藏苔草草原(21.08 g DM/m^2)(P<0.01);(2)冷季牧草粗蛋白含量表现为藏嵩草草甸(5.16%)极显著高于紫花针茅草原(3.95%)和青藏苔草草原(4.32%)(P<0.01);(3)冷季牧草干物质、粗蛋白和代谢能的单位草地面积输出总量均表现为藏嵩草草甸>紫花针茅草原>青藏苔草草原(P<0.01);(4)三类典型草地冷季承载力均表现为代谢能承载力>数量承载力>可消化蛋白承载力,表明代谢能承载力可以满足食草动物需求,采用可消化蛋白承载力有助于缓解国家公园内天然草地放牧压力,更符合生态保护的目标.紫花针茅草原、藏嵩草草甸和青藏苔草草原冷季的可消化蛋白承载力分别为0.84±0.04、1.57±0.07和0.27±0.02 SHU/ha(标准羊单位/公顷),对应草地代表性食草动物承载力分别为0.17±0.01家牦牛/ha、0.39±0.02藏野驴/ha和0.22±0.02藏羚羊/ha;(5)三江源国家公园高寒草地冷季食草动物承载力整体偏低,建议在国家公园内牧业生产区,通过转变畜牧业经营方式(如放牧家畜暖季末期适时出栏、冷季异地舍饲出栏等)加快家畜周转速率,减少国家公园内放牧家畜存栏数量,为野生动物保护释放草地资源和生态空间.展开更多
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.
文摘揭示三江源国家公园典型高寒草地的冷季牧草营养特征和食草动物承载力,对园区内草地与食草动物平衡管理具有重要意义,然而相关地面研究鲜有报道.本研究于2019年12月对三江源国家公园长江源园区的紫花针茅草原、藏嵩草草甸和青藏苔草草原进行调查取样,分析了该地区冷季牧草地上现存量和营养品质,同时结合农业行业标准(NY/T635-2015)核算了冷季数量承载力、可消化蛋白承载力和代谢能承载力.结果表明:(1)冷季牧草干物质现存量表现为藏嵩草草甸(103.03 g DM/m^2)>紫花针茅草原(72.24 g DM/m^2)>青藏苔草草原(21.08 g DM/m^2)(P<0.01);(2)冷季牧草粗蛋白含量表现为藏嵩草草甸(5.16%)极显著高于紫花针茅草原(3.95%)和青藏苔草草原(4.32%)(P<0.01);(3)冷季牧草干物质、粗蛋白和代谢能的单位草地面积输出总量均表现为藏嵩草草甸>紫花针茅草原>青藏苔草草原(P<0.01);(4)三类典型草地冷季承载力均表现为代谢能承载力>数量承载力>可消化蛋白承载力,表明代谢能承载力可以满足食草动物需求,采用可消化蛋白承载力有助于缓解国家公园内天然草地放牧压力,更符合生态保护的目标.紫花针茅草原、藏嵩草草甸和青藏苔草草原冷季的可消化蛋白承载力分别为0.84±0.04、1.57±0.07和0.27±0.02 SHU/ha(标准羊单位/公顷),对应草地代表性食草动物承载力分别为0.17±0.01家牦牛/ha、0.39±0.02藏野驴/ha和0.22±0.02藏羚羊/ha;(5)三江源国家公园高寒草地冷季食草动物承载力整体偏低,建议在国家公园内牧业生产区,通过转变畜牧业经营方式(如放牧家畜暖季末期适时出栏、冷季异地舍饲出栏等)加快家畜周转速率,减少国家公园内放牧家畜存栏数量,为野生动物保护释放草地资源和生态空间.
