PSIII-17 Transcriptome Response of Granulosa Cells to Seasonal Heat Stress in Beef Cows

Abstract Investigation of cellular responses to thermal heat stress can lead identifying novel targets intervention tackle the increasing fertility decline due climate change-associated seasonal stress. We aimed study response granulosa cells Dry beef cows (n=11) were kept together during and subjected synchronization stimulation for follicular dynamics. Ovum pick-up (OPU) was conducted on all animals in winter summer. Once OPU-fluid settled, cumulus-oocyte-complexes (COCs) isolated form OPU fluid stored a -80 freezer after snap freezing. In addition, blood samples rectal temperature data collected each OPU. Environmental daily three weeks before using Florida Automated Weather Network. Data analyzed Glimmix procedure SAS. are presented as mean ± standard error mean. RNA extracted from five pools followed by library preparation sequencing (NovaSeq; Illumina). As expected, environmental conditions contrasting: average air (11.5°C vs. 27.5°C), max (16.9°C 33.7°C), relative humidity (83.5% 82.3%), temperature-humidity index (53.39 79.16) summer, respectively. Average higher (P = 0.03) summer (39.2 0.2°C) than (38.8 0.2°C). Of total differentially expressed genes, showed up down regulation 971 1038 transcripts, respectively compared season (Fold Change ≤ -2 or ≥ 2 FDR p-value 0.05). Those upregulated transcripts found be involved cell cycle division, death, steroid biosynthesis, progesterone mediated oocyte maturation meiosis pathways. conclusion, exposure induce significant alteration transcriptome which may have negative impact physiology.