The Antarctic Weddell seal genome reveals evidence of selection on cardiovascular phenotype and lipid handling

• Main Authors: Noh, Hyun Ji, Turner-Maier, Jason, Schulberg, S Anne, Fitzgerald, Michael L, Johnson, Jeremy, Allen, Kaitlin N, Hückstädt, Luis A, Batten, Annabelle J, Alfoldi, Jessica, Costa, Daniel P, Karlsson, Elinor K, Zapol, Warren M, Buys, Emmanuel S, Lindblad-Toh, Kerstin, Hindle, Allyson G
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2022
• Subjects: Human Genome; Biotechnology; Genetics; Animals; Antarctic Regions; Gene Expression Regulation; Genome; Genome-Wide Association Study; Lipid Metabolism; Oxygen; Phylogeny; Seals; Earless; Species Specificity; Antarctic; The Antarctic; Weddell; Antarc*; harbor seal; Weddell Seal; Weddell Seals
• Online Access: https://escholarship.org/uc/item/5b78m5sm

The Weddell seal (Leptonychotes weddellii) thrives in its extreme Antarctic environment. We generated the Weddell seal genome assembly and a high-quality annotation to investigate genome-wide evolutionary pressures that underlie its phenotype and to study genes implicated in hypoxia tolerance and a lipid-based metabolism. Genome-wide analyses included gene family expansion/contraction, positive selection, and diverged sequence (acceleration) compared to other placental mammals, identifying selection in coding and non-coding sequence in five pathways that may shape cardiovascular phenotype. Lipid metabolism as well as hypoxia genes contained more accelerated regions in the Weddell seal compared to genomic background. Top-significant genes were SUMO2 and EP300; both regulate hypoxia inducible factor signaling. Liver expression of four genes with the strongest acceleration signals differ between Weddell seals and a terrestrial mammal, sheep. We also report a high-density lipoprotein-like particle in Weddell seal serum not present in other mammals, including the shallow-diving harbor seal.