RNA sequencing of sperm from healthy cattle and horses reveals the presence of a large bacterial population
RNA molecules within ejaculated sperm can be characterized through whole transcriptome sequencing, enabling the identification of pivotal transcripts that may influence reproductive success. However, the profiling of sperm transcriptomes through next-generation sequencing has several limitations impairing the identification of functional transcripts. In this study, we explored the nature of the RNA sequences present in the sperm transcriptome of two livestock species, cattle and horses using RNA-Sequencing (RNA-Seq) technology. Low mapping rates observed during data processing were mainly attributed to the presence of ribosomal RNA and bacteria in sperm samples which led to a reduced sequencing depth or library size. To explore the possibility that unmapped reads could be associated with bacteria, we then identified bacteria-associated transcripts within RNA-Seq data derived from bovine and equine sperm cell preparations. This analysis revealed bacterial species that may closely interact with sperm and potentially influence male fertility. Identifying these potentially pathogenic or beneficial species and understanding how they may affect sperm quality in each species could be paramount to assess the breeding capacity of livestock. Overall design: Bacterial abundance estimation of transcriptome samples from sperm preparations of fertile bulls and stallions