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

• Published in: Communications Biology
• Main Authors: Noh, Hyun Ji, Turner-Maier, Jason, Schulberg, S. Anne, Fitzgerald, Michael L., Johnson, Jeremy, Allen, Kaitlin N., Huckstadt, 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: English
• Published: Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi 2022
• Subjects: Genetics; Genetik; Antarctic; The Antarctic; Weddell; Antarc*; harbor seal; Weddell Seal; Weddell Seals
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-470460; https://doi.org/10.1038/s42003-022-03089-2

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. The Antarctic Weddell inhabits one of the most extreme environments on Earth. Comparative genomics with close relatives reveals the specific genetic adaptations for cardiovascular and fat metabolism that enable it to thrive.