RNA extraction, sequencing, and data processing
DNA and RNA were extracted from chest skin biopsies using TRIzol™ Reagent and the Zymo Quick-DNA/RNA™ Microprep Plus Kit (Zymo Research, Irvine, CA). We quantified RNA integrity (RQN) using a Fragment Analyzer 5200 (Agilent Technology, Inc., Santa Clara, CA). RNA-sequencing libraries were prepared using 200 ng of total RNA following a recently developed 3’-based protocol, TM3’seq (Pallares et al., 2020). Libraries were amplified with 16 PCR cycles. All other procedures followed the published protocol or manufacturer recommendations. Libraries were combined in equimolar quantities and sequenced on one lane of an Illumina NovaSeq S4 flow cell (Illumina Inc.) of 100 bp single-end with an average of 2.17 million reads per sample mapping to the transcriptome. Reads were mapped to the Macaca mulattareference assembly Mmul_10 (Warren et al., 2020) using kallisto (v0.43.1) (Bray et al., 2016). We chose the genome of Macaca mulatta , a closely related cercopithecoid, as its richer annotation yielded a higher number of mapped reads compared to the Theropithecus gelada genome (Chiou et al., 2022).