Morphology and genome of a snailfish from the Mariana Trench provide insights into deep-sea adaptation.
Wang, K., Shen, Y.J., Yang, Y.Z., Gan, X.N., Liu, G.C., Hu, K., et al.
Nature Ecology and Evolution
It is largely unknown how living organisms—especially vertebrates—survive and thrive in the coldness, darkness and high pressures
of the hadal zone. Here, we describe the unique morphology and genome of Pseudoliparis swirei—a recently described
snailfish species living below a depth of 6,000 m in the Mariana Trench. Unlike closely related shallow sea species, P. swirei
has transparent, unpigmented skin and scales, thin and incompletely ossified bones, an inflated stomach and a non-closed
skull. Phylogenetic analyses show that P. swirei diverged from a close relative living near the sea surface about 20 million years
ago and has abundant genetic diversity. Genomic analyses reveal that: (1) the bone Gla protein (bglap) gene has a frameshift
mutation that may cause early termination of cartilage calcification; (2) cell membrane fluidity and transport protein activity in
P. swirei may have been enhanced by changes in protein sequences and gene expansion; and (3) the stability of its proteins may
have been increased by critical mutations in the trimethylamine N-oxide-synthesizing enzyme and hsp90 chaperone protein.
Our results provide insights into the morphological, physiological and molecular evolution of hadal vertebrates.