iScience (Jul 2020)

Insights into the Evolution of Neoteny from the Genome of the Asian Icefish Protosalanx chinensis

  • Jie Zhang,
  • Jiwei Qi,
  • Fanglei Shi,
  • Huijuan Pan,
  • Meng Liu,
  • Ran Tian,
  • Yuepan Geng,
  • Huaying Li,
  • Yujie Qu,
  • Jinping Chen,
  • Inge Seim,
  • Ming Li

Journal volume & issue
Vol. 23, no. 7
p. 101267


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Summary: Salangids, known as Asian icefishes, represent a peculiar radiation within the bony fish order Protacanthopterygii where adult fish retain larval characteristics such as transparent and miniaturized bodies and a cartilaginous endoskeleton into adulthood. Here, we report a de novo genome of Protosalanx chinensis, the most widely distributed salangid lineage. The P. chinensis genome assembly is more contiguous and complete than a previous assembly. We estimate that P. chinensis, salmons, trouts, and pikes diverged from a common ancestor 185 million years ago. A juxtaposition with other fish genomes revealed loss of the genes encoding ectodysplasin-A receptor (EDAR), SCPP1, and four Hox proteins and likely lack of canonical fibroblast growth factor 5 (FGF5) function. We also report genomic variations of P. chinensis possibly reflecting the immune system repertoire of a species with a larval phenotype in sexually mature individuals. The new Asian icefish reference genome provides a solid foundation for future studies.