Genomics, Proteomics & Bioinformatics (Dec 2022)

Comparative Genomics Reveals Evolutionary Drivers of Sessile Life and Left-right Shell Asymmetry in Bivalves

  • Yang Zhang,
  • Fan Mao,
  • Shu Xiao,
  • Haiyan Yu,
  • Zhiming Xiang,
  • Fei Xu,
  • Jun Li,
  • Lili Wang,
  • Yuanyan Xiong,
  • Mengqiu Chen,
  • Yongbo Bao,
  • Yuewen Deng,
  • Quan Huo,
  • Lvping Zhang,
  • Wenguang Liu,
  • Xuming Li,
  • Haitao Ma,
  • Yuehuan Zhang,
  • Xiyu Mu,
  • Min Liu,
  • Hongkun Zheng,
  • Nai-Kei Wong,
  • Ziniu Yu

Journal volume & issue
Vol. 20, no. 6
pp. 1078 – 1091

Abstract

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Bivalves are species-rich mollusks with prominent protective roles in coastal ecosystems. Across these ancient lineages, colony-founding larvae anchor themselves either by byssus production or by cemented attachment. The latter mode of sessile life is strongly molded by left-right shell asymmetry during larval development of Ostreoida oysters such as Crassostrea hongkongensis. Here, we sequenced the genome of C. hongkongensis in high resolution and compared it to reference bivalve genomes to unveil genomic determinants driving cemented attachment and shell asymmetry. Importantly, loss of the homeobox gene Antennapedia (Antp) and broad expansion of lineage-specific extracellular gene families are implicated in a shift from byssal to cemented attachment in bivalves. Comparative transcriptomic analysis shows a conspicuous divergence between left-right asymmetrical C. hongkongensis and symmetrical Pinctada fucata in their expression profiles. Especially, a couple of orthologous transcription factor genes and lineage-specific shell-related gene families including that encoding tyrosinases are elevated, and may cooperatively govern asymmetrical shell formation in Ostreoida oysters.

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