Molecular aspects of eye development and regeneration in the Australian redclaw crayfish, Cherax quadricarinatus

The compound eye evolved over 500 million years ago and enables mosaic vision in most arthropod species. The molecular regulation of the development of the compound eye has been primarily studied in the fruit fly Drosophila melanogaster. However, due to the nature of holometabolous insects halting growth after their terminal metamorphosis into the adult form, they lack the capacity to regenerate. Crustaceans, unlike holometabolous insects, continue to grow during adulthood, achieved through regular shedding of their exoskeleton, in a cyclic process known as molting. This therefore offers crustaceans as a highly suitable model to study ocular regeneration in the adult arthropod eye. We have assessed the regenerative capacity of the retinal section of the Cherax quadricarinatus (red-claw crayfish) eye, following ablation and successive post-metamorphic molts. This work then provides a transcriptomic description of the outer, pigmented retinal tissue (the ommatidia and lamina ganglionaris) and the basal, non-pigmented neuroendocrine ocular tissue (the X-organ Sinus Gland complex, hemiellipsoid body and optic nerve). Using comparative analysis, we identified all the transcripts in the C. quadricarinatus ocular transcriptome that are known to function in compound eye development in D. melanogaster. Differentially and uniquely transcribed genes of the retina are described, suggesting proposed mechanisms that may regulate ocular regeneration in decapod Crustacea. This research exemplifies the application C. quadricarinatus holds as an optimal model to study the regulation of ocular regeneration. Further in-depth transcriptomic analyses are now required, sampled throughout the regeneration process to better define the regulatory mechanism.