library_construction_protocol: RNA was isolated from the pups' hearts extracted at P1 by using the Qiagen miRNeasy Micro Kit (Cat# 210874), following the manufacturer's protocol after homogenizing tissue in Qiazol Messenger RNA was purified from total RNA using poly-T oligo-attached magnetic beads. After fragmentation, the first strand cDNA was synthesized using random hexamer primers, followed by the second strand cDNA synthesis using either dUTP for directional library. The library was checked with Qubit and real-time PCR for quantification and bioanalyzer for size distribution detection. Quantified libraries will be pooled and sequenced on Illumina platforms, according to effective library concentration and data amount.