library_construction_protocol: Whole organs were then dissected in the following order: brain, spleen, heart, swim bladder, tail fin, liver, ovary (female), gill, muscle, intestine and pancreas, and testis (male). The samples were quickly transferred into cold DPBS, washed and then manually pulverized using a mortar and pestle within a liquid nitrogen bath. The pulverized tissues were suspended in 1mL of Nuclear Isolation Buffer (NIB) and followed by incubation for 1.5-3 min to isolate the nuclei. The suspension of each tissue was transferred to 15 mL centrifuge tubes pre-filled with 5mL of WB (wash buffer, 0.2% BSA, 3 mM MgCl2 in DPBS), filtered through 40 μm strainers and centrifuged at 650 × g for 5 min at 4°C. We resuspended the nuclei in 1 mL of WB and filtered the suspension through 20 μm size strainers, pelleted at 650 × g for 5 min and resuspended in the appropriate amount of DPBS to give a final concentration of 25,000 nuclei per microlitre. Library preparations were performed with the UUATAC-seq protocol