Loss of eyes in zebrafish caused by mutation of chokh/rx3.
The vertebrate eye forms by specification of the retina anlage and subsequent morphogenesis of the optic vesicles, from which the neural retina differentiates. chokh (chk) mutant zebrafish lack eyes from the earliest stages in development. Marker gene analysis indicates that retinal fate is specified normally, but optic vesicle evagination and neuronal differentiation are blocked. We show that the chk gene encodes the homeodomain-containing transcription factor, Rx3. Loss of Rx3 function in another teleost,medaka, has also been shown to result in an eyeless phenotype. The medaka rx3 locus can fully rescue the zebrafish mutant phenotype. We provide evidence that the regulation of rx3 is evolutionarily conserved, whereas the downstream cascade contains significant differences in gene regulation. Thus, these mutations in orthologous genes allow us to study the evolution of vertebrate eye development at the molecular level.
Loosli
Felix
F
Developmental Biology Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, PO Box 10.2209, 69012 Heidelberg, Germany.
Staub
Wendy
W
Finger-Baier
Karin C
KC
Ober
Elke A
EA
Verkade
Heather
H
Wittbrodt
Joachim
J
Baier
Herwig
H
D000818:Animals; D005124:Eye Abnormalities / Q000235:genetics*; D005136:Eye Proteins; D029941:Fish Proteins / Q000235:genetics*; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D017354:Point Mutation; D012097:Repressor Proteins; D012160:Retina / Q000196:embryology / Q000378:metabolism; D015027:Zebrafish / Q000235:genetics*; D029961:Zebrafish Proteins / Q000096:biosynthesis / Q000235:genetics; D000097607:Homeobox Protein SIX3
D005136:Eye Proteins; D029941:Fish Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D029961:Zebrafish Proteins; D000097607:Homeobox Protein SIX3; C121293:Rx3 protein, Oryzias latipes; C464524:rx1 protein, zebrafish