2.3 Long DNA library construction and sequencing
Long fragments of extracted high-quality DNA from fresh muscle were selected using a Blue Pippin System (Sage Science, MA, USA), with a peak value of 20 kb. After the short reads were reduced, the long fragments were used for nanopore sequencing. The sequencing adapters were ligated to the ends of the long fragments, according to the manufacturer’s instructions for the 1D Ligation Sequencing Kit (SQK-LSK109, Nanopore, Oxford, UK). Finally, the 20 kb genomic DNA libraries were quantified using a Qubit 3.0 Fluorometer (Invitrogen, Camarillo, USA). Meanwhile, three 20 kb libraries (three 1D prep) were prepared and sequenced on one flow cell using the Nanopore PromethION DNA sequencer (Oxford Nanopore, Oxford, UK), according to the manufacturer’s instructions.