title: Differential reparative phenotypes between zebrafish and medaka after cardiac injury.
abstract: BACKGROUND
  Zebrafish have the ability for heart regeneration. However, another teleost animal model, the medaka, had not yet been investigated for this capacity.
  
  
  RESULTS
  Compared with zebrafish, the medaka heart responded differently to an injury: An excessive fibrotic response occurred in the medaka heart, and existing cardiomyocytes or cardiac progenitor cells remained dormant, resulting in no numerical difference between the uncut and injured heart with respect to the number of EdU-incorporated cardiomyocytes. The results obtained from the analysis of the medaka raldh2-GFP transgenic line showed a lack of raldh2 expression in the endocardium. Regarding periostin expression, the localization of medaka periostin-b, a marker of fibrillogenesis, in the medaka heart remained at the wound site at 30 dpa; whereas zebrafish periostin-b was no longer localized at the wound but was detected in the epicardium at that time.
  
  
  CONCLUSIONS
  Compared with zebrafish heart regeneration, the medaka heart phenotypes suggest the possibility that the medaka could hardly regenerate its heart tissue or that these phenotypes for heart regeneration showed a delay.
authors.affiliation: Department of Biological Information, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Ito
authors.forename: Mai
authors.initials: M
authors.lastname: Morioka
authors.forename: Shun
authors.initials: S
authors.lastname: Kimura
authors.forename: Mai
authors.initials: M
authors.lastname: Tasaki
authors.forename: Keiji
authors.initials: K
authors.lastname: Inohaya
authors.forename: Akira
authors.initials: A
authors.lastname: Kudo
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D049109:Cell Proliferation; D006321:Heart / Q000502:physiology*; D006335:Heart Injuries / Q000503:physiopathology*; D009206:Myocardium / Q000378:metabolism; D009990:Oryzias; D010641:Phenotype; D012038:Regeneration / Q000502:physiology*; D015027:Zebrafish
keywords: heart regeneration; heart repair; medaka; periostin; raldh2; zebrafish