title: Loss of the six3/6 controlling pathways might have resulted in pinhole-eye evolution in Nautilus.
abstract: Coleoid cephalopods have an elaborate camera eye whereas nautiloids have primitive pinhole eye without lens and cornea. The Nautilus pinhole eye provides a unique example to explore the module of lens formation and its evolutionary mechanism. Here, we conducted an RNA-seq study of developing eyes of Nautilus and pygmy squid. First, we found that evolutionary distances from the common ancestor to Nautilus or squid are almost the same. Although most upstream eye development controlling genes were expressed in both species, six3/6 that are required for lens formation in vertebrates was not expressed in Nautilus. Furthermore, many downstream target genes of six3/6 including crystallin genes and other lens protein related genes were not expressed in Nautilus. As six3/6 and its controlling pathways are widely conserved among molluscs other than Nautilus, the present data suggest that deregulation of the six3/6 pathway led to the pinhole eye evolution in Nautilus.
authors.affiliation: Ochadai Academic Production, Ochanomizu University, Tokyo, 112-8610, Japan. aogu@whelix.info
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ogura
authors.forename: Masa-aki
authors.initials: MA
authors.lastname: Yoshida
authors.forename: Takeya
authors.initials: T
authors.lastname: Moritaki
authors.forename: Yuki
authors.initials: Y
authors.lastname: Okuda
authors.forename: Jun
authors.initials: J
authors.lastname: Sese
authors.forename: Kentaro K
authors.initials: KK
authors.lastname: Shimizu
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Sousounis
authors.forename: Panagiotis A
authors.initials: PA
authors.lastname: Tsonis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D003459:Crystallins / Q000737:chemistry / Q000235:genetics; D049832:Decapodiformes / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D005123:Eye / Q000196:embryology / Q000378:metabolism; D005136:Eye Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D053263:Gene Regulatory Networks; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007908:Lens, Crystalline / Q000196:embryology / Q000378:metabolism; D049850:Nautilus / Q000196:embryology / Q000235:genetics* / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D000097607:Homeobox Protein SIX3
chemical_list: D003459:Crystallins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D000097607:Homeobox Protein SIX3