Cone photoreceptor types in zebrafish are generated by symmetric terminal divisions of dedicated precursors

• DOI: 10.1073/pnas.1303551110
• Publication Date: 2013-08-27T02:24:39Z
• Authors: Sachihiro C. Suzuki; Adam Bleckert; Philip R. Williams; Masaki Takechi; Shoji Kawamura; Rachel O. L. Wong
• Keywords: Opsin; Cone (formal languages); Growth cone

Proper functioning of sensory systems requires the generation appropriate numbers and proportions neuronal subtypes that encode distinct information. Perception color relies on signals from multiple cone photoreceptor types. In cone-dominated retinas, each expresses a single opsin type with peak sensitivity to UV, long (L) (red), medium (M) (green), or short (S) (blue) wavelengths. The modes cell division generating types are unknown. We report here mechanism whereby zebrafish photoreceptors same produced by symmetric dedicated precursors. Transgenic fish in which thyroid hormone receptor β2 (trβ2) promoter drives fluorescent protein expression before L-cone precursors themselves permitted tracking their vivo. Every L local region resulted terminal an precursor, suggesting such divisions contribute significantly production. Analysis fate isolated pairs cones time-lapse observations suggest other can also arise divisions. Such may help rapidly attain final (L > M, UV S) larvae. Loss- gain-of-function experiments show L-opsin trβ2 activity differentiation. Ectopic after differentiation produces mixed opsins. Temporal differences onset could explain why some species have mixed, others pure,