Antarctic ecosystem
Climate
Krill (Euphausia superba)
The Enormous Repetitive Antarctic Krill Genome
Summary
This groundbreaking study presents the first complete genome of Antarctic krill, revealing it to be the largest animal genome ever assembled at 48.01 gigabases - about 16 times larger than the human genome. The enormous size results from extensive repetitive DNA elements (72% of genome). Key findings include genetic adaptations for extreme Antarctic conditions through expanded gene families for continuous molting and energy metabolism, plus a functional circadian clock system. Population analysis of 75 individuals from four Antarctic regions shows high genetic connectivity with no major geographic barriers, but environmental selection is occurring. The genome provides crucial insights into how Earth's most abundant animal species has adapted to one of the planet's most extreme environments.
Key Findings
1
Genome Architecture: At 48.01 Gb, this represents the largest animal genome ever sequenced, with 72% composed of repetitive sequences, particularly DNA transposons 2
Environmental Adaptations: Identification of expanded gene families (25 significantly expanded) associated with continuous molting and energy metabolism, enabling survival in extreme seasonal Antarctic conditions 3
Circadian System: Complete molecular architecture of Antarctic krill circadian clock revealed, showing dual-feedback loop mechanism with seasonal expression differences 4
Population Structure: High genetic connectivity across Antarctica with no clear geographic differentiation, but evidence of environmental selection across different regions 5
Evolutionary History: Population bottleneck ~10 million years ago followed by expansion ~100,000 years ago, coinciding with major climate events Abstract
Antarctic krill (Euphausia superba) is Earth's most abundant wild animal, and its enormous biomass is vital to the Southern Ocean ecosystem. Here, we report a 48.01-Gb chromosome-level Antarctic krill genome, whose large genome size appears to have resulted from inter-genic transposable element expansions. Our assembly reveals the molecular architecture of the Antarctic krill circadian clock and uncovers expanded gene families associated with molting and energy metabolism, providing insights into adaptations to the cold and highly seasonal Antarctic environment. Population-level genome re-sequencing from four geographical sites around the Antarctic continent reveals no clear population structure but highlights natural selection associated with environmental variables. An apparent drastic reduction in krill population size 10 mya and a subsequent rebound 100 thousand years ago coincides with climate change events. Our findings uncover the genomic basis of Antarctic krill adaptations to the Southern Ocean and provide valuable resources for future Antarctic research.Published in
Cell, Volume 186, Pages 1279-1294
2023Authors
Changwei Shao, Shuai Sun, Kaiqiang Liu, Jiahao Wang, Shuo Li, Qun Liu, Bruce E. Deagle, Inge Seim, Alberto Biscontin, Qian Wang, Xin Liu, So Kawaguchi, Yalin Liu, Simon Jarman, Yue Wang, Hong-Yan Wang, Guodong Huang, Jiang Hu, Bo Feng, Cristiano De Pittà , Shanshan Liu, Rui Wang, Kailong Ma, Yiping Ying, Gabrielle Sales, Tao Sun, Xinliang Wang, Yaolei Zhang, [and 47 additional authors]Institutions
Multiple institutions led by Yellow Sea Fisheries Research Institute (Chinese Academy of Fishery Sciences), BGI-Qingdao, Alfred Wegener Institute, Australian Antarctic Division, and others
Methods
Biological sampling Data
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