The origin and loss of periodic patterning in the turtle shell.
Development
; 141(15): 3033-9, 2014 Aug.
Article
em En
| MEDLINE
| ID: mdl-25053434
ABSTRACT
The origin of the turtle shell over 200 million years ago greatly modified the amniote body plan, and the morphological plasticity of the shell has promoted the adaptive radiation of turtles. The shell, comprising a dorsal carapace and a ventral plastron, is a layered structure formed by basal endochondral axial skeletal elements (ribs, vertebrae) and plates of bone, which are overlain by keratinous ectodermal scutes. Studies of turtle development have mostly focused on the bones of the shell; however, the genetic regulation of the epidermal scutes has not been investigated. Here, we show that scutes develop from an array of patterned placodes and that these placodes are absent from a soft-shelled turtle in which scutes were lost secondarily. Experimentally inhibiting Shh, Bmp or Fgf signaling results in the disruption of the placodal pattern. Finally, a computational model is used to show how two coupled reaction-diffusion systems reproduce both natural and abnormal variation in turtle scutes. Taken together, these placodal signaling centers are likely to represent developmental modules that are responsible for the evolution of scutes in turtles, and the regulation of these centers has allowed for the diversification of the turtle shell.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Tartarugas
/
Padronização Corporal
/
Exoesqueleto
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Development
Assunto da revista:
BIOLOGIA
/
EMBRIOLOGIA
Ano de publicação:
2014
Tipo de documento:
Article