For Nanopore Ultra-long DNA libraries (with N50 values of 100Kb and 200Kb), long-fragment DNA (>50kb) was isolated and recovered using the Sage HLS system (Sage Science, USA). The DNA underwent damage repair and end repair using the NEBNext FFPE Repair Mix (Cat #M6630, NEB, USA) and the NEBNext Ultra II End Repair/dA-Tailing Module (Cat #E7546, NEB, USA). Adapter ligation and purification were performed with the Ligation Sequencing Kit SQK-LSK114 (Oxford Nanopore Technologies, UK). The library DNA was accurately quantified using a Qubit3.0 Fluorometer (Invitrogen, USA). Finally, sequencing was carried out on the Nanopore PromethION platform (Oxford Nanopore Technologies, UK).