title: Regulatory Differences in Natal Down Development between Altricial Zebra Finch and Precocial Chicken.
abstract: Birds can be classified into altricial and precocial. The hatchlings of altricial birds are almost naked, whereas those of precocial birds are covered with natal down. This regulatory divergence is thought to reflect environmental adaptation, but the molecular basis of the divergence is unclear. To address this issue, we chose the altricial zebra finch and the precocial chicken as the model animals. We noted that zebra finch hatchlings show natal down growth suppressed anterior dorsal (AD) skin but partially down-covered posterior dorsal (PD) skin. Comparing the transcriptomes of AD and PD skins, we found that the feather growth promoter SHH (sonic hedgehog) was expressed higher in PD skin than in AD skin. Moreover, the data suggested that the FGF (fibroblast growth factor)/Mitogen-activated protein kinase (MAPK) signaling pathway is involved in natal down growth suppression and that FGF16 is a candidate upstream signaling suppressor. Ectopic expression of FGF16 on chicken leg skin showed downregulation of SHH, upregulation of the feather growth suppressor FGF10, and suppression of feather bud elongation, similar to the phenotype found in zebra finch embryonic AD skin. Therefore, we propose that FGF16-related signals suppress natal down elongation and cause the naked AD skin in zebra finch. Our study provides insights into the regulatory divergence in natal down formation between precocial and altricial birds.
authors.affiliation: Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Chih-Kuan
authors.initials: CK
authors.lastname: Chen
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Chen Siang
authors.initials: CS
authors.lastname: Ng
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Siao-Man
authors.initials: SM
authors.lastname: Wu
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Jiun-Jie
authors.initials: JJ
authors.lastname: Chen
authors.affiliation: Department of Life Science, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Po-Liang
authors.initials: PL
authors.lastname: Cheng
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles.
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Mei-Yeh Jade
authors.initials: MY
authors.lastname: Lu
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Di-Rong
authors.initials: DR
authors.lastname: Chen
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles Center for the Integrative and Evolutionary Galliformes Genomics (iEGG Center), National Chung Hsing University, Taichung, Taiwan Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Cheng-Ming
authors.initials: CM
authors.lastname: Chuong
authors.affiliation: Department of Life Science, National Chung Hsing University, Taichung, Taiwan Center for the Integrative and Evolutionary Galliformes Genomics (iEGG Center), National Chung Hsing University, Taichung, Taiwan whli@sinica.edu.tw ctting@ntu.edu.tw hcheng@dragon.nchu.edu.tw.
authors.forename: Hsu-Chen
authors.initials: HC
authors.lastname: Cheng
authors.affiliation: Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan Department of Life Science, National Taiwan University, Taipei, Taiwan whli@sinica.edu.tw ctting@ntu.edu.tw hcheng@dragon.nchu.edu.tw.
authors.forename: Chau-Ti
authors.initials: CT
authors.lastname: Ting
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan Center for the Integrative and Evolutionary Galliformes Genomics (iEGG Center), National Chung Hsing University, Taichung, Taiwan Department of Ecology and Evolution, University of Chicago whli@sinica.edu.tw ctting@ntu.edu.tw hcheng@dragon.nchu.edu.tw.
authors.forename: Wen-Hsiung
authors.initials: WH
authors.lastname: Li
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002645:Chickens / Q000254:growth & development* / Q000378:metabolism; D019143:Evolution, Molecular; D005241:Feathers / Q000254:growth & development* / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism; D046369:Finches / Q000254:growth & development* / Q000378:metabolism; D005786:Gene Expression Regulation; D053823:Hedgehog Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D053823:Hedgehog Proteins; D005346:Fibroblast Growth Factors; D020928:Mitogen-Activated Protein Kinases
keywords: altricial bird; feather evolution; natal down; precocial bird