Expression Profile of Genes as Indicators of Developmental Competence and Quality of In Vitro Fertilization and Somatic Cell Nuclear Transfer Bovine Embryos

Abstract

Reproductive biotechnologies such asin vitrofertilization (IVF) and somatic cell nuclear transfer (SCNT) enable improvedreproductive efficiency of animals. However, the birth rate ofin vitro-derived embryos still lags behind that of theirin vivocounterparts. Thus, it is critical to develop an accurate evaluation and prediction system of embryo competence, both forcommercial purposes and for scientific research. Previous works have demonstrated thatin vitroculture systems inducealterations in the relative abundance (RA) of diverse transcripts and thus compromise embryo quality. The aim of this workwas to analyze the RA of a set of genes involved in cellular stress (heat shock protein 70-kDa, HSP70), endoplasmic reticulum(ER) stress (immunoglobulin heavy chain binding protein, Bip; proteasome subunitb5, PSMB5) and apoptosis (BCL-2associated X protein, Bax; cysteine aspartate protease-3, Caspase-3) in bovine blastocysts produced by IVF or SCNT andcompare it with that of theirin vivocounterparts. Poly (A)+mRNA was isolated from three pools of 10 blastocysts pertreatment and analyzed by real-time RT-PCR. The RA of three of the stress indicators analyzed (Bax, PSMB5 and Bip) wassignificantly increased in SCNT embryos as compared with that ofin vivo-derived blastocysts. No significant differences werefound in the RA of HSP70 and Caspase-3 gene transcripts. This study could potentially complement morphological analysesin the development of an effective and accurate technique for the diagnosis of embryo quality, ultimately aiding to improvethe efficiency of assisted reproductive techniques (ART).