Evolution of photosensory cell types
Schlosser, Gerhard
Schlosser, Gerhard
Loading...
Repository DOI
Publication Date
2021-06-18
Type
book part
Downloads
Citation
Schlosser, Gerhard. (2021). Evolution of photosensory cell types. In Gerhard Schlosser, Evolutionary origin of sensory and neurosecretory cell types: Vertebrate cranial placodes, Volume 2. Boca Raton: CRC Press.
Abstract
Chapter 4 reviews the evolution of photoreceptors in animals. It is shown that two lineages of photoreceptors, known as rhabdomeric and ciliary photoreceptors, respectively, are present throughout bilaterians. Ciliary photoreceptors use ciliary opsins and their specification depends on a core regulatory network (CoRN) involving transient Pax6, Rx and Otx transcription factors. Rhabdomeric photoreceptors instead use rhabdomeric opsins and depend on a CoRN involving persistent Pax6, Atonal, POU4 expression. Whereas shared dependence on Pax6 and similarities in phototransduction mechanisms suggests that ciliary and rhabdomeric photoreceptor originated by duplication and divergence of an ancestral photoreceptor, shared dependence on Atonal, POU4 and other transcription factors instead suggests a common origin of rhabdomeric photoreceptors and mechanoreceptors. Evidence from cnidarians indicates that both “ciliary” and rhabdomeric phototransduction mechanisms are present, but that there are no distinct “ciliary” and rhabdomeric photoreceptor cell types. Moreover, Atonal, POU4 and PaxB are expressed in mechano- as well as photosensory cells in cnidarians and many sensory cells appear to be multimodal. This suggests that rhabdomeric and ciliary photoreceptors and mechanoreceptors originated as distinct cell types from a common sensorineural precursor cell type only in the stem lineage of bilaterians.
Funder
Publisher
CRC Press
Publisher DOI
https://doi.org/10.1201/9781003160625
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International