title: Proliferating cells in suborbital tissue drive eye migration in flatfish.
abstract: The left/right asymmetry of adult flatfishes (Pleuronectiformes) is remarkable given the external body symmetry of the larval fish. The best-known change is the migration of their eyes: one eye migrates from one side to the other. Two extinct primitive pleuronectiformes with incomplete orbital migration have again attracted public attention to the mechanism of eye migration, a subject of speculation and research for over a century. Cranial asymmetry is currently believed to be responsible for eye migration. Contrary to that hypothesis, we show here that the initial migration of the eye is caused by cell proliferation in the suborbital tissue of the blind side and that the twist of frontal bone is dependent on eye migration. The inhibition of cell proliferation in the suborbital area of the blind side by microinjected colchicine was able to prevent eye migration and, thereafter, cranial asymmetry in juvenile Solea senegalensis (right sideness, Soleidae), Cynoglossus semilaevis (left sideness, Cynoglossidae), and Paralichthys olivaceus (left sideness, Paralichthyidae) with a bottom-dwelling lifestyle. Our results correct the current misunderstanding that eye migration is driven by the cranial asymmetry and simplify the explanation for broken left/right eye-symmetry. Our findings should help to focus the search on eye migration-related genes associated with cell proliferation. Finally, a novel model is proposed in this research which provides a reasonable explanation for differences in the migrating eye between, and sometimes within, different species of flatfish and which should aid in our overall understanding of eye migration in the ontogenesis and evolution of Pleuronectiformes.
authors.affiliation: The Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai 201306, PR China. blbao@shou.edu.cn
authors.forename: Baolong
authors.initials: B
authors.lastname: Bao
authors.forename: Zhonghe
authors.initials: Z
authors.lastname: Ke
authors.forename: Jubin
authors.initials: J
authors.lastname: Xing
authors.forename: Eric
authors.initials: E
authors.lastname: Peatman
authors.forename: Zhanjiang
authors.initials: Z
authors.lastname: Liu
authors.forename: Caixia
authors.initials: C
authors.lastname: Xie
authors.forename: Bing
authors.initials: B
authors.lastname: Xu
authors.forename: Junwei
authors.initials: J
authors.lastname: Gai
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Gong
authors.forename: Guimei
authors.initials: G
authors.lastname: Yang
authors.forename: Yan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Wenqiao
authors.initials: W
authors.lastname: Tang
authors.forename: Daming
authors.initials: D
authors.lastname: Ren
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D005123:Eye / Q000166:cytology / Q000254:growth & development*; D005146:Facial Asymmetry / Q000196:embryology*; D005412:Flatfishes / Q000033:anatomy & histology / Q000254:growth & development*; D007814:Larva / Q000254:growth & development; D008675:Metamorphosis, Biological / Q000502:physiology*; D009915:Orbit / Q000166:cytology*