Eye evolution: a question of genetic promiscuity.
Animal eyes have long served as a classical example of independent origin followed by convergence of structures onto a few different solutions. During the past decade this view has been challenged by the discovery of shared developmental regulatory genes. The Pax6 gene in particular is almost universally employed for eye formation in bilaterian animals, despite widely different embryological origins. The resulting controversy on the multiple or single origins of animal eyes has gradually been sharpened by continuing discoveries of further general similarities in the genetic regulatory circuits of eye development. Recent work on gene expression in specified cell types, together with comparative studies of developmental genes in cnidarians, now show some promise to a solution of the controversy.
Nilsson
Dan-E
DE
Department of Cell and Organism Biology, Lund University, Zoology building, Helgonavägen 3, 22362 Lund, Sweden. dan-e.nilsson@cob.lu.se
D000818:Animals; D005075:Biological Evolution; D003063:Cnidaria / Q000166:cytology / Q000196:embryology / Q000235:genetics; D019143:Evolution, Molecular; D005123:Eye / Q000166:cytology / Q000196:embryology* / Q000254:growth & development*; D005136:Eye Proteins; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D023421:Models, Animal; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000196:embryology / Q000254:growth & development; D012097:Repressor Proteins
D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins