Meeting Abstract
S10-1.6 Monday, Jan. 7 Transcriptomics and the evolution of stomatopod visual systems PORTER, M.L..*; CALDWELL, R.L.; OAKLEY, T.H.; CRONIN, T.W.; University of South Dakota; University of California, Berkeley; University of California, Santa Barbara; University of Maryland Baltimore County Megan.Porter@usd.edu
Stomatopod crustaceans have complex and diverse visual systems, containing unique features that exist in no other animals. These features include a specialized ommatidial region, intrarhabdomal filtering of photoreceptors, and receptors devoted to polarized light detection. The most complex stomatopod eye type contains 16 physiologically different photoreceptor classes, although there is variation in eye complexity among species. In order to investigate this visual system diversity and complexity at the molecular level, transcriptomes have been sequenced from 4 species exhibiting variations in eye design. Transcripts from genes involved in visual signal transduction were identified from assembled transcriptomes using sequences of full-length genes from the Drosophila melanogaster genome as queries. The stomatopod species investigated vary in the number of arthropod visual-pigment (R-Type) opsin genes expressed from 12 (Hemisquilla californiensis) to 25 (Neogonodactylus oerstedii). Based on these results we hypothesize that the diversity of opsin genes expressed has increased during the evolution of the group, with the largest expansion of copy number occurring in the short-wavelength sensitive opsin classes. In all four species sequenced (H. californiensis, N. oerstedii, Squilla empusa, and Pseudosquilla ciliata) more opsin genes are expressed than physiologically documented photoreceptors present in the visual system; preliminary in situ hybridization work in N. oerstedii shows that many photoreceptor types express multiple opsin genes. Additionally, there is variation among species in the number of expressed transcripts of other key cascade components, including G-proteins and visual arrestins, suggesting further complexity in visual signal transduction.
