Evolution of the eye transcriptome under constant darkness in Sinocyclocheilus cavefish.

Mol Biol Evol 2013 Jul 23;30(7):1527-43. Epub 2013 Apr 23.

Institute of Zoology, Chinese Academy of Sciences, Beijing, China.

In adaptating to perpetual darkness, cave species gradually lose eyes and body pigmentation and evolve alternatives for exploring their environments. Although troglodyte features evolved independently many times in cavefish, we do not yet know whether independent evolution of these characters involves common genetic mechanisms. Surface-dwelling and many cave-dwelling species make the freshwater teleost genus Sinocyclocheilus an excellent model for studying the evolution of adaptations to life in constant darkness. We compared the mature retinal histology of surface and cave species in Sinocyclocheilus and found that adult cavefish showed a reduction in the number and length of photoreceptor cells. To identify genes and genetic pathways that evolved in constant darkness, we used RNA-seq to compare eyes of surface and cave species. De novo transcriptome assemblies were developed for both species, and contigs were annotated with gene ontology. Results from cave-dwelling Sinocyclocheilus revealed reduced transcription of phototransduction and other genes important for retinal function. In contrast to the blind Mexican tetra cavefish Astyanax mexicanus, our results on morphologies and gene expression suggest that evolved retinal reduction in cave-dwelling Sinocyclocheilus occurs in a lens-independent fashion by the reduced proliferation and downregulation of transcriptional factors shown to have direct roles in retinal development and maintenance, including cone-rod homeobox (crx) and Wnt pathway members. These results show that the independent evolution of retinal degeneration in cavefish can occur by different developmental genetic mechanisms.

Download full-text PDF

Source
http://mbe.oxfordjournals.org/content/30/7/1527.full.pdf
Web Search
http://mbe.oxfordjournals.org/cgi/doi/10.1093/molbev/mst079
Publisher Site
http://dx.doi.org/10.1093/molbev/mst079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3684860PMC
July 2013
17 Reads

Publication Analysis

Top Keywords

cave species
12
constant darkness
12
independent evolution
8
surface cave
8
genetic mechanisms
8
cave-dwelling sinocyclocheilus
8
species
5
cavefish
5
sinocyclocheilus
5
retinal
5
eyes surface
4
developed species
4
species novo
4
novo transcriptome
4
species contigs
4
assemblies developed
4
transcriptome assemblies
4
ontology cave-dwelling
4
reduced transcription
4
transcription phototransduction
4

Similar Publications