Chromosomal-scale genome assembly of the near-extinction big-head schizothorcin (Aspiorhynchus laticeps).

The big-head schizothorcin (Aspiorhynchus laticeps) is an endemic and near-extinction freshwater fish in Xinjiang, China. In this study, a chromosome-scale genome assembly of A. laticeps was generated using PacBio and Hi-C techniques. The PacBio sequencing data resulted in a 1.58 Gb assembly with a contig N50 of 1.27 Mb. Using Hi-C scaffolding approach, 88.38% of the initial assembled sequences were anchored and oriented into a chromosomal-scale assembly. The final assembly consisted of 25 pseudo-chromosomes that yielded 1.37 Gb of sequence, with a scaffold N50 of 44.02 Mb. BUSCO analysis showed a completeness score of 93.7%. The genome contained 48,537 predicted protein-coding genes and 58.31% of the assembly was annotated as repetitive sequences. Whole genome duplication events were further confirmed using 4dTv analysis. The genome assembly of A. laticeps should be valuable and important to understand the genetic adaptation and endangerment process of this species, which could lead to more effective management and conservation of the big-head schizothorcin and related freshwater fish species.