The genetic control of eye development and its implications for the evolution of the various eye-types.
Mutations in the Pax 6 homologs of mammals and insects prevent eye development and targeted expression of both mammal and insect Pax 6 homologs is capable of inducing functional ectopic eyes. Supported by RNA interference experiments in planarians and nemerteans, these findings indicate that Pax 6 is a universal master control gene for eye morphogenesis. Since all metazoan eyes use rhodopsin as a photoreceptor molecule and the same master control gene for eye development, we postulate a monophyletic origin of the various eye types. The finding of well developed eyes in jellyfish which essentially lack a brain, leads us to propose that the eye as a sensory organ evolved before the brain which is an information processing organ. The finding of highly developed eyes with a lens, vitreous body, stacked membranes like a retina and shielding pigment in unicellular dinoflagellates, raises the possibility that the prototypic eyes might have been acquired from symbionts.
Gehring
Walter J
WJ
Biozentrum, University of Basel, Switzerland. Walter.Gehring@unibas.ch
D000818:Animals; D005123:Eye / Q000196:embryology*; D005136:Eye Proteins; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D009799:Ocular Physiological Phenomena; D020411:Oligonucleotide Array Sequence Analysis; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012313:RNA / Q000378:metabolism; D012097:Repressor Proteins
D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D012313:RNA