placentaRNA-seq of blcattle black cattle
placentaRNA-seq of blcattle black cattle
The six experimental cattle used in this study were sourced from Shandong Zhaofu Animal Husbandry Technology Co., Ltd. The barns provided adequate lighting and ventilation, with suitable temperature and humidity, and all animals were maintained under consistent feeding conditions. The study protocol was approved by the Qingdao Agricultural University Institutional Animal Care and Use Committee (IACUC) (Approval No. DKY20220805, dated August 5, 2022). Placental tissues were collected postpartum, and their length, width, thickness, and weight were measured. Cotyledon tissues from the same anatomical location were collected and stored in liquid nitrogen at -80°C. calf birth weight, body height, chest circumference, and waistline were recorded. Based on placental weight, the cattle were divided into Group P (≥5.5 kg, n=3) and Group S (<5.5 kg, n=3). Total RNA was extracted using Trizol reagent kit (Invitrogen, Carlsbad, CA,USA) according  to the manufacturer's protocol. RNA quality was assessed on an Agilent 2100 Bioanalyzer  (Agilent Technologies, Palo Alto, CA, USA) and checked using RNase free agarose gel  electrophoresis.  After total RNA was extracted, eukaryotic mRNA was enriched by Oligo(dT) beads.Then the enriched  mRNA was fragmented into short fragments using fragmentation buffer and reversly  transcribed into cDNA by using NEBNext Ultra RNA Library Prep Kit for Illumina(NEB  #7530,New England Biolabs, Ipswich, MA, USA).The purified double-stranded cDNA  fragments were end repaired, A base added, and ligated to Illumina sequencing adapters.The  ligation reaction was purified with the AMPure XP Beads(1.0X).Ligated fragments were  subjected to size selection by agarose gel electrophoresis and polymerase chain reaction  (PCR) amplified.The resulting cDNA library was sequenced using Illumina Novaseq6000 by  Gene Denovo Biotechnology Co. (Guangzhou, China).