Isolation of total ribonucleic acid from fresh and frozen-thawed boar semen and its relevance in transcriptome studies

Abstract

The main objective of this study was to isolate high-quality total ribonucleic acid (RNA) from raw fresh semen and frozen-thawed boar semen, using a protocol comprising the conventional TRIzol assay and a membrane-based technique, the PureLink RNA mini kit. Bioanalyzer profile revealed that the sperm RNA size distributions comprised mainly intact RNA ranging from 1500 to 1800 bp, without any detectable residual genomic deoxyribonucleic acid (DNA) or 28S ribosomal RNA (rRNA). Spectrophotometric quantifications of the total RNA yielded 1.64 to 2.44 μg/10⁶ spermatozoa, irrespective of the sperm source. The TRIzol/PureLink protocol allowed the isolation of high-quality intact RNA from boar spermatozoa, which is required for transcriptome analysis on high-throughput RNA-sequencing (RNA-Seq) data. Such an approach is relevant to identifying sperm messenger RNA (mRNA transcripts) that are associated with boar semen freezability.

Keywords: cryopreservation, RNA-Seq, semen quality