Characterization of Novel Long Non-coding RNAs and Their Roles as Indicators of Oocyte Quality in Cattle

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Commodities

• Animals: bovine

Practices

• Animal Production: genetics, livestock breeding
• Education and Training: extension, technical assistance, workshop
• Sustainable Communities: partnerships

In cattle, the fertilization rate is 90% with an average calving rate of about 55%, indicating an embryonic-fetal mortality rate of roughly 35% [1]. Further, 70-80% of total embryonic loss occurs during the first three weeks after insemination, particularly between days 7-16 in cattle [2]. It is estimated that there is a $1.2 billion a year industry loss due to embryonic mortality [2]. To achieve reproductive success, the oocyte must be able to display developmental competence. Meaning, the oocyte must display competence to resume meiosis, cleave upon fertilization, sustain early development (namely to activate its genome), establish pregnancy, and to sustain fetal growth and development until birth [3]. In mammals, proper development during early embryogenesis relies heavily on the regulation of maternal transcripts with gradual degradation while simultaneously activating the embryonic genome. Long non-coding RNAs (lncRNAs) are believed to regulate various cellular processes including modulation of gene expression and epigenetic status [4]. Previous studies have indicated that lncRNAs have essential regulatory roles in human and mouse embryonic development however, little information is available for bovine. Using RNA-sequencing, 1,535 lncRNAs were predicted by our lab in bovine GV and MII oocytes. Through experimental approaches, future studies will focus on characterizing the subcellular localization and functions of the top twenty lncRNAs predicted to have the greatest effect on oocyte quality. By selecting oocytes of higher quality based on their expression profiles of lncRNAs, embryos will undergo embryonic genome activation at higher rates, thus decreasing early embryonic loss and yielding higher pregnancy rates.

1. To characterize the temporal and spatial expression of oocyte-specific lncRNAs during early embryogenesis and determine if they are involved in fertilization.

2. To investigate oocyte quality by comparing lncRNA expression profiles in “good and bad” oocytes based on previously published methodologies; follicle size and cytoplasmic morphology.

3. To elucidate the regulatory role of specific lncRNAs in meiotic maturation, fertilization, cleavage, and developmental events characteristic to the maternal-to-embryonic transition.