Beef heifer fertility issues contribute to a major economic loss in the cow-calf production industry. Therefore, identifying beef heifers with superior genetic potential for improved fertility would increase profitability. This study aimed to identify differences in the transcriptome profiles from granulosa and peripheral white blood cells (pWBCs) of beef heifers with varying reproductive potential. For this, Angus-Simmental crossbred heifers were subjected to an estrus synchronization and fixed-time artificial insemination (AI) protocol (7-D CO-Synch + CIDR) followed by exposure for 60-d to a fertile bull. Depending on the presence or absence of conceptus 120 d post-AI, heifers were classified as fertile (pregnant by AI) or sub-fertile (non-pregnant by AI or bull-breeding). Pregnancies were terminated, and all animals in both groups (fertile, n = 8; and sub-fertile, n = 5) were cycling when the blood and ovaries were collected from each heifer. Total RNA was extracted from the pWBCs and granulosa cells and subjected to library preparation and sequencing on the Nova-Seq platform. The read counts were obtained after data quality control using FastQC v0.11.9 and MultiQC v1.12 and alignment to the Ensemble’s ARS UCD1.2 Bos taurus genome reference using STAR aligner v2.7.5. The filtered data were subjected to differential expression analysis using DESeq2. We identified 1,061 and 72 significantly differentially expressed genes (DEGs) with P-values ≤ 0.05 and absolute (log2 fold change) ≥ 0.5 from pWBC and granulosa, respectively. Notably, 12 targets including 9 protein coding genes (PLCL1, DNER, GNAS, CDH3, PER1, ITGA2B, CXCL12, ENSBTAG00000048613, ENSBTAG00000051519), bta-mir-2887-1, 5-8S-rRNA and U5 were found as DEGs in both the tissues. Based on a differential co-expression analysis using PCIT, we identified GNAS and DNER as hub genes in pWBC and the granulosa cells of the sub-fertile heifer group. The 12 shared genes were over-represented for pathways such as NF kappa B and chemokine signaling, regulation of actin cytoskeleton, and platelet activation. Some of the identified genes have been previously associated with fertility, while others are novel. A detailed understanding of the underlying biological mechanisms of the top genes and a follow-up study with a larger sample size at different time points could validate the candidates identified in this study for their role as potential therapeutic targets.

中文翻译：

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PSVI-24 可育和低生育力小母牛颗粒和外周白细胞的基因表达谱


肉牛小母牛生育问题导致奶牛-小牛生产行业出现重大经济损失。因此，识别具有卓越遗传潜力以提高生育能力的肉牛将提高盈利能力。本研究旨在确定具有不同繁殖潜力的肉小母牛颗粒和外周白细胞 （pWBC） 转录组谱的差异。为此，安格斯-西门塔尔杂交小母牛进行发情同步和固定时间人工授精 （AI） 方案 （7-D CO-Synch + CIDR），然后暴露于可育公牛 60-d。根据 AI 后 120 天是否存在概念，小母牛被分类为可育小母牛（通过 AI 怀孕）或低生育力（通过 AI 或公牛繁殖未怀孕）。终止妊娠，当从每头小母牛收集血液和卵巢时，两组中的所有动物（可育，n = 8;和亚可育，n = 5）都在循环。从 pWBCs 和颗粒细胞中提取总 RNA，并在 Nova-Seq 平台上进行文库制备和测序。使用 FastQC v0.11.9 和 MultiQC v1.12 进行数据质量控制，并使用 STAR 对准器 v2.7.5 与集合的 ARS UCD1.2 Bos taurus 基因组参考比对后获得读取计数。使用 DESeq2 对过滤后的数据进行差异表达分析。我们鉴定了 1,061 个和 72 个显著差异表达基因 （DEGs），pWBC 和颗粒的 P 值分别为 0.05 ≤≥绝对 （log2 倍变化） 0.5。值得注意的是，在两个组织中发现了 12 个靶标，包括 9 个蛋白编码基因 （PLCL1、DNER、GNAS、CDH3、PER1、ITGA2B、CXCL12、ENSBTAG00000048613、ENSBTAG00000051519）、bta-mir-2887-1、5-8S-rRNA 和 U5 作为 DEGs。 基于使用 PCIT 的差异共表达分析，我们确定 GNAS 和 DNER 是 pWBC 和亚可育小母牛组颗粒细胞中的枢纽基因。这 12 个共享基因在 NF κ B 和趋化因子信号传导、肌动蛋白细胞骨架调节和血小板活化等通路中过度代表。一些已确定的基因以前与生育能力有关，而另一些则是新颖的。详细了解主要基因的潜在生物学机制并在不同时间点进行较大样本量的后续研究可以验证本研究中确定的候选基因作为潜在治疗靶点的作用。