Comparative analysis of a teleost skeleton transcriptome provides insight into its regulation

An articulated endoskeleton that is calcified is a unifying innovation of the vertebrates, however the molecular basis of the structural divergence between terrestrial and aquatic vertebrates, such as teleost fish, has not yet been established. In the present study long-read next generation sequencing (NGS, Roche 454 platform) was used to characterise acellular perichondral bone (vertebrae) and chondroid bone (gill arch) in the sea bream (Sparus auratus). A total of 15.97Mb were produced from vertebrae cDNA library yielding 32,374 contigs (consensus sequences) with an average length of 493bp. For the gill arches cDNA library a total of 14.53 Mb were produced, assembling into 28,371 contigs with an average length of 514bp. 10,455 and 10,625 sequences from vertebrae and gill arches respectively were annotated with Gene Ontology (GO) terms. Comparative analysis of the global transcriptome revealed 4249 unique transcripts in vertebrae, 4201 unique transcripts in the gill arches and 3700 common transcripts with several core gene networks identified that are conserved between sea bream and mammals. Moreover, transcripts for putative endocrine factors were identified suggesting that the “acellular” bone of sea bream, in common with mammalian bone, can act as an endocrine tissue. The responsiveness at a molecular level of acellular vertebrae to a short fast suggests, in contrast to current opinion based on histological analysis that it may be rapidly mobilized in response to a challenge.