Journal Article
Eye degeneration and loss of otx5b expression in the cavefish Sinocyclocheilus tileihornes
Huang, Z., Titus, T., Postlethwait, J.H. and Meng, F.
Record Number:
4389
Year:
2019
Journal:
Journal of Molecular Evolution
Abstract:
Cave animals possess remarkable phenotypes associated with existence in their dark environments. The Chinese cavefish
Sinocyclocheilus tileihornes shows substantial eye degeneration, a trait shared by most cave species. The extent to which
independent evolution of troglomorphic traits uses convergent molecular genetic mechanisms is as yet unknown. We performed
transcriptome-wide gene expression profiling in S. tileihornes eyes and compared results with those from the closely
related surface species S. angustiporus and an independently derived congeneric cavefish, S. anophthalmus. In total, 52.85
million 100 bp long paired-end clean reads were generated for S. tileihornes, and we identified differentially expressed genes
between the three possible pairs of species. Functional analysis of genes differentially expressed between S. tileihornes
and S. angustiporus revealed that phototransduction (KEGG id: dre04744) was the most significantly enriched pathway,
indicating the obvious differences in response to captured photons between the cavefish S. tileihornes and the surface species
S. angustiporus. Analysis of key genes regulating eye development showed complete absence of otx5b (orthodenticle
homolog 5) expression in S. tileihornes eyes, probably related to degradation of rods, but normal expression of crx (cone-rod
homeobox). The enriched pathways and Otx5 are involved in phototransduction, photoreceptor formation, and regulation of
photoreceptor-related gene expression. Unlike the S. tileihornes reported here, S. anophthalmus has reduced crx and otx5
expression. These results show that different species of cavefish within the same genus that independently evolved troglodyte
characteristics can have different genetic mechanisms of eye degeneration.
Times Cited:
2