Abstract:
An understanding of eye development is necessary to comprehend proper functioning of
the eye, capacity for regeneration, and the developmental basis of disease. Many model
systems, both vertebrate and invertebrate, have historically provided much important
data about the developmental and genetic basis of eye formation. However, hurdles
exist studying eye development in model systems such as inherent biases in mutant
screens and the minimal amount of naturally occurring variation in eye size. One novel
approach allowing for a greater understanding of the developmental and genetic bases
of eye formation is to examine naturally occurring eye size variation in non-model
organisms, such as that occurs in cave animals. Our previous work demonstrated the
utility of using non-model organisms to model human disease when we found that a
commonly mutated gene in cases of human albinism was also responsible for albinism
in the cavefish, Astyanax mexicanus.
We initially chose the isopod crustacean, Asellus aquaticus as a model for studying eye
variation because of the extreme difference in eye size between cave and surface
dwelling populations. Our subsequent work on the species demonstrated further
advantages including multiple independent mechanisms of eye reduction/ loss within a
single cave population, multiple mechanisms of eye loss between different cave
populations, and the large genetic component influencing eye size. We have already
generated many molecular, developmental, and genetic tools and reagents that will
assist in studying this interesting species. Our proposal aims to understand the genetics
behind eye degeneration in this species. First, we use comparative transcriptome
sequencing of cave and surface embryonic samples as an unbiased method to identify
genes and pathways responsible for eye degeneration in the cave form. Second, we
sequence transcriptomes of hybrid embryos to identify genes that show allele specific
expression and that putatively contain cis-regulatory changes. Next, we validate genes
discovered from the transcriptome sequencing using linkage and functional techniques.
Our work provides a novel perspective on the developmental and genetic basis of eye
size differences and furthers the development of A. aquaticus as an important model for
eye degeneration and disease.