RNA was isolated by TRIzol-chloroform extraction, followed by cleanup using RNA Clean & Concentrator-5 (Zymo Research Cat#R1013). cDNA was prepared using the manufacturer's protocol for NEBNext Single Cell/Low Input cDNA Synthesis & Amplification Module (New Englang Biolabs Cat#E6421). Libraries were constructed using the manufacturer's protocol for SMRTbell prep kit 3.0 (PacBio Cat#102-182-700).