Transcriptome pyrosequencing of the Antarctic brittle star Ophionotus victoriae.

Brittle stars are included within a whole range of species, which contribute to knowledge in the medically important area of tissue regeneration. All brittle stars regenerate lose limbs, but the rate at which this occurs is highly variable and species-specific. One of the slowest rates of arm regeneration reported so far is that of the Antarctic Ophionotus victoriae. Additionally, O. victoriae also has an unusual delay in the onset of regeneration of about 5months. Both processes are of interest for the areas of regeneration biology and adaptation to cold environments. One method of understanding the details of regeneration events in brittle stars is to characterise the genes involved. In the largest transcriptome study of any ophiuroid to date, we describe the results of mRNA pyrosequencing from pooled samples of regenerating arms of O. victoriae. The sequencing reads resulted in 18,000 assembled contiguous sequences of which 19% were putatively annotated by blast sequence similarity searching. We focus on the identification of major gene families and pathways with potential relevance to the regenerative processes including the Wnt/β-catenin pathway, Hox genes, the SOX gene family and the TGF beta signalling pathways. These data significantly increase the amount of ophiuroid sequences publicly available and provide candidate transcripts for the further investigation of the unusual regenerative process in this Antarctic ophiuroid.