A team of researchers in China has sequenced and assembled the high-quality reference genome for the Yap hadal snailfish, which was captured at a depth of 7,000 m in the Yap Trench in the western Pacific Ocean.
The Yap hadal snailfish. Image credit: Mu et al., doi: 10.1371/journal.pgen.100953.
Hadal environments (depths below 6,000 m) are characterized by extremely high hydrostatic pressures, low temperatures, a scarce food supply, and little light.
Fish are the only vertebrates inhabiting the hadal zone, and hadal snailfishes have been found in at least five geographically separated marine trenches.
However, the genetic mechanisms that allow vertebrates to live in such extreme conditions are not well understood.
To understand how hadal snailfishes have adapted to life in the deep sea, Dr. Xinhua Chen of the Fujian Agriculture and Forestry University and colleagues sequenced the whole genome of a snailfish from the Yap Trench.
The analysis of the genome revealed multiple adaptations for living in a cold, dark, high-pressure environment.
The scientists also found that the Yap hadal snailfish carries extra genes for DNA repair, which may help keep its genome intact under high pressures.
The fish also has five copies of a gene for an enzyme that takes a compound produced by bacteria in its gut and transforms it into one that stabilizes the structure of proteins under high hydrostatic pressure.
It has also lost certain genes involved in vision, taste and smell, which are likely unnecessary in its dark, food-limited environment.
“Many genes associated with DNA repair show evidence of positive selection and have expanded copy numbers in the genome of the Yap hadal snailfish, which potentially reflect the difficulty of maintaining DNA integrity under high hydrostatic pressure,” Dr. Chen said.
“The five copies of the trimethylamine N-oxide (TMAO)-generating enzyme flavin-containing monooxygenase-3 gene (fmo3) and the abundance of trimethylamine (TMA)-generating bacteria in the gut of the Yap hadal snailfish could provide enough TMAO to improve protein stability under hadal conditions.”
“Our results provide new insights into the molecular mechanisms underlying the adaptation of hadal organisms to the deep-sea environment and valuable genomic resources that will help further clarify hadal adaptations,” the authors concluded.
The findings were published in the journal PLoS Genetics.
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Y. Mu et al. 2021. Whole genome sequencing of a snailfish from the Yap Trench (~7,000 m) clarifies the molecular mechanisms underlying adaptation to the deep sea. PLoS Genet 17 (5): e1009530; doi: 10.1371/journal.pgen.100953
Source link: https://www.sci.news/genetics/yap-hadal-snailfish-genome-09657.html
