Chromosomal-scale De novo Genome Assemblies of Cynomolgus Macaque and Common Marmoset

Abstract

Cynomolgus macaque (Macaca fascicularis) and common marmoset (Callithrix jacchus) have been widely used in human biomedical research. Their genomes were sequenced and assembled initially using short-read sequences, with the advent of massively parallel sequencing. However, the resulting contig sequences tended to remain fragmentary, and long-standing primate genome assemblies used the human genome as a reference for ordering and orienting the assembled fragments into chromosomes. Here we performed de novo genome assembly of these two species without any human genome-based bias observed in the genome assemblies released earlier. Firstly we assembled PacBio long reads, and the resultant contigs were scaffolded with Hi-C data. The scaffolded sequences obtained were further refined based on assembly results of alternate de novo assemblies and Hi-C contact maps by resolving identified inconsistencies. The final assemblies achieved N50 lengths of 149 Mb and 137 Mb for cynomolgus macaque and common marmoset, respectively, and the numbers of scaffolds longer than 10Mb are equal to their chromosome numbers. The high fidelity of our assembly is ascertained by concordance to the BAC-end read pairs observed for common marmoset, as well as a high resemblance of their karyotypic organization. Our assembly of cynomolgus macaque outperformed all the available assemblies of this species in terms of contiguity. The chromosome-scale genome assemblies produced in this study are valuable resources for non-human primate models and provide an important baseline in human biomedical research.