Genome sequencing of Mnemiopsis leidyi
High molecular weight DNA was isolated from 5-8 animals (3-5 cm) starved for 24 hours prior to flash-freezing. Frozen tissues were powdered with mortar and pestle, dissolved in 10 ml of urea extraction buffer (50 mM Tris-HCl (pH 8.0), 7M Urea, 312.5 mM NaCl, 20 mM EDTA (pH 8.0), 1% w/v N-Lauroylsarcosine sodium salt) and incubated for 10 min at RT on a rocking platform 20 rpm. Genomic DNA was then purified twice with a phenol-chloroform-isoamyl alcohol mixture pH 7.7-8.3 (Sigma-Aldrich, 77617), precipitated with 0.7 volume of 100% isopropanol, and subsequently washed twice with 70% ethanol. Finally, the isolated DNA was subjected to another round of purification with Nanobind Tissue kit (Circulomics, NB-900-701-01), followed by short-read elimination with SRE Kit (Circulomics, SS-100-101-01). Sequencing was performed on Oxford Nanopore using PromethION flow cell (R9.4).