Elephant shark genome provides unique insights into gnathostome evolution

Article

关键词: CARTILAGINOUS FISH;    METABOLIC-RATE;    VERTEBRATES;    ORIGIN;    REPERTOIRE;    PHYLOGENY;    RECEPTORS;    SEQUENCE;    IMMUNITY;    LAMPREY;   

DOI  :  10.1038/nature12826

来源: SCIE

【 摘 要 】

The emergence of jawed vertebrates (gnathostomes) fromjawless vertebrates was accompanied by major morphological and physiological innovations, such as hinged jaws, paired fins and immunoglobulin-based adaptive immunity. Gnathostomes subsequently diverged into two groups, the cartilaginous fishes and the bony vertebrates. Here we report the whole-genome analysis of a cartilaginous fish, the elephant shark (Callorhinchus milii). We find that the C. milii genome is the slowest evolving of all known vertebrates, including the ` living fossil' coelacanth, and features extensive synteny conservation with tetrapod genomes, making it a goodmodel for comparative analyses of gnathostome genomes. Our functional studies suggest that the lack of genes encoding secreted calcium-binding phosphoproteins in cartilaginous fishes explains the absence of bone in their endoskeleton. Furthermore, the adaptive immune system of cartilaginous fishes is unusual: it lacks the canonical CD4 co-receptor and most transcription factors, cytokines and cytokine receptors related to the CD4 lineage, despite the presence of polymorphic major histocompatibility complex class II molecules. It thus presents a new model for understanding the origin of adaptive immunity.

【 授权许可】

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