Metazoan Genome assembly Supported by High-Throughput Genome Mapping

Accurate decoding of small genomes, especially those of bacteria’s, has been made easier by recent advances of long read DNA sequencers and assemblers for their reads. On the other hand, large genomes of multicellular organisms are still too complicated to be decoded solely by sequencers. In conventional genome projects, this problem is solved by splitting the genome into small compartments, for example by constructing BAC library. Problem in this approach is that they are very expensive and difficult to raise its throughput, which prevents maximum utilization of high performance sequencing facility.

High-throughput genome mapping is one of the new technologies expected to overcome this problem by providing long-range information. BioNano Genomics’ Irys system is the first commercially available interpretation of this technology, which generates physical map of megabase-sized DNA molecules. In this system, DNA molecules are labeled in a sequence-motif based manner and loaded into nanochannel for imaging. From the image, lengths of the DNA molecules and distance between sequence motifs are optically determined, which provides physical map of the molecules. The whole reaction is operated in highly parallelized reusable channels for high-throughput: 90Gb in 20 hrs.

In this report, authors will present several metazoan non-model genome assembly projects using the Irys genome mapping method in combination with short-read NGS technologies. Hybrid scaffolding of NGS contigs and Irys consensus map significantly improved contiguity of the draft genome, which enables deeper understanding of the genome.