Conference Paper
Transcriptome analysis in Astyanax mexicanus blind cavefish and sighted surface fish
Hinaux, H., Poulain, J., Da Silva, C., Noirot, C., Jeffery, W.R., Casane, D. and Rétaux, S.
Record Number:
5687
Year:
2013
Journal:
AIM 2013
Abstract:
Astyanax mexicanus, a teleost species with surface dwelling (surface fish) and cave adapted
(cavefish) morphs, is an important model system in evolutionary developmental biology
(evodevo). Astyanax cavefish differ from surface fish in numerous traits, including the
enhancement of non-visual sensory systems, and the loss of eyes and pigmentation. The
genetic bases for these differences are not fully understood as genomic and transcriptomic
data are lacking.
We here present de novo transcriptome sequencing of embryonic and larval stages of a
surface fish population and a cavefish population originating from the Pachón cave. This
effort represents the first large scale sequence and clone resource for the Astyanax research
community. The analysis of these sequences shows low levels of polymorphism in cavefish
compared to surface fish, confirming previous studies on a small number of genes. A high
proportion of the genes mutated in cavefish are known to be expressed in the zebrafish
developing visual system. Such a high number of mutations in cavefish putative eye genes
may be explained by relaxed selection for vision-related genes during the evolution in the
absence of light. Based on these sequence differences, we provide a list of 11 genes that are
potential candidates for having a role in cavefish visual system degeneration.
As the lens plays a major role in triggering eye degeneration in cavefish, we have surveyed
the cavefish and surface fish transcriptomes with particular attention for the crystalline gene
superfamily. In Astyanax, we uncovered 6 beta crystalline sequences (cryba1b, cryba1l,
cryba2, crybb1, crybb1d and crybb1c), at least 5 gamma crystalline sequences (crygn2,
crygn, crygmxb, crygm5 and genes related to crygm2), 2 sequences of the beta-gamma
family of crystallines (aim1a, crybg3), the lambda crystalline cryl1, the mu crystalline crym
and the zeta crystalline cryzl1. Among those, we found that crybb1c is strongly downregulated
in cavefish. Thus, at least two cristallines, crybb1c (this work) and cryaa (Behrens
et al., 1998) are misexpressed in the cavefish lens, and this may (partly) contribute to lens
apoptosis and lens degeneration in cavefish.
Times Cited:
1
Relevent Species: