library_construction_protocol: Nuclei were isolated using a modified version of a sucrose density gradient isolation protocol25. Briefly, thawed tissues were placed in 1 mL of lysis buffer (0.32 M sucrose, 5 mM CaCl2, 3 mM magnesium acetate, 0.1 mM EDTA, 10 mM Tris-HCl pH 8, 1 mM DTT, 0.1% Triton X-100) with 50 μL of 25 U/mL RNase inhibitor (Takara #2313B) in a dounce homogenizer (Wheaton #357538). Homogenization was performed with 20 strokes using a tight pestle. Another 1 mL of lysis buffer was added, followed by an additional 10 strokes. The resulting 2 mL homogenate was transferred to a 15 mL Open-Top Thinwall Polypropylene Tube (Beckman-Coulter #361707). The homogenizer and pestle were rinsed with 2 mL of lysis buffer, and this wash was combined with the homogenate for a total of 4 mL. The homogenate was carefully underlaid with 9 mL of sucrose solution (1.8 M sucrose, 3 mM magnesium acetate, 1 mM DTT, 10 mM Tris-HCl pH 8) and ultracentrifuged at 24,000 rpm for 1 hour at 4 °C using a Sorvall™ WX+ centrifuge. After centrifugation, the supernatant and debris at the interface were gently removed. The nuclear pellet was resuspended in 1 mL of resuspension buffer (0.02% bovine serum albumin in DPBS with 25 μL of 25 U/mL RNase inhibitor) and incubated on ice for 10 minutes. The suspension was passed through a 35 μm nylon mesh filter (Corning #352235) into a 1.5 mL RNase/DNase-free microcentrifuge tube and centrifuged at 2600 x g for 10 minutes at 4 °C. Supernatants were discarded, and nuclei were resuspended in 200 μL of resuspension buffer. A 10 μL aliquot of the nuclei suspension was stained with Trypan Blue to assess quality and concentration using a Countess 3 Automated Cell Counter. Nuclei suspensions were loaded onto a Chromium Single Cell 3′ chip (10X Genomics, v3) and processed according to the manufacturer's protocol, targeting 10,000 nuclei. Single-nuclei libraries were generated using the 10X Chromium Next GEM Single Cell 3′ v3.1 (Dual Index) protocol (CG000315 Rev A). Libraries were pooled, loaded onto a single 10B 100 Cycle Flowcell, and sequenced using an Illumina NovaSeq 6000 system to generate 25-30,000 paired-end 2 × 100 bp reads.