Sdf1a patterns zebrafish melanophores and links the somite and melanophore pattern defects in choker mutants.
Pigment pattern formation in zebrafish presents a tractable model system for studying the morphogenesis of neural crest derivatives. Embryos mutant for choker manifest a unique pigment pattern phenotype that combines a loss of lateral stripe melanophores with an ectopic melanophore ;collar' at the head-trunk border. We find that defects in neural crest migration are largely restricted to the lateral migration pathway, affecting both xanthophores (lost) and melanophores (gained) in choker mutants. Double mutant and timelapse analyses demonstrate that these defects are likely to be driven independently, the collar being formed by invasion of melanophores from the dorsal and ventral stripes. Using tissue transplantation, we show that melanophore patterning depends upon the underlying somitic cells, the myotomal derivatives of which--both slow--and fast-twitch muscle fibres--are themselves significantly disorganised in the region of the ectopic collar. In addition, we uncover an aberrant pattern of expression of the gene encoding the chemokine Sdf1a in choker mutant homozygotes that correlates with each aspect of the melanophore pattern defect. Using morpholino knock-down and ectopic expression experiments, we provide evidence to suggest that Sdf1a drives melanophore invasion in the choker mutant collar and normally plays an essential role in patterning the lateral stripe. We thus identify Sdf1 as a key molecule in pigment pattern formation, adding to the growing inventory of its roles in embryonic development.
Svetic
Valentina
V
Centre for Regenerative Medicine and Developmental Biology Programme, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
Hollway
Georgina E
GE
Elworthy
Stone
S
Chipperfield
Thomas R
TR
Davison
Claire
C
Adams
Richard J
RJ
Eisen
Judith S
JS
Ingham
Philip W
PW
Currie
Peter D
PD
Kelsh
Robert N
RN
D000818:Animals; D019521:Body Patterning; D002465:Cell Movement; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008547:Melanophores / Q000166:cytology / Q000502:physiology*; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology; D009154:Mutation; D009432:Neural Crest / Q000502:physiology*; D010858:Pigmentation; D019170:Somites / Q000166:cytology / Q000502:physiology*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics / Q000502:physiology*
D054377:Chemokine CXCL12; D019743:Chemokines, CXC