Proteome of seminal plasma and sperm associated with sperm survival following cryopreservation in the Red Wolf (Canis rufus)

Understanding of the impacts of seminal plasma and sperm proteins on both animal and human fertility has expanded rapidly in the last decade. However, little is known about the reproductive proteomes of endangered species. In this study, we characterized for the first time the seminal plasma and sperm proteomes of the critically endangered Red Wolf and evaluated differences in proteomic signatures between ejaculates which experienced "High" versus "Baseline" (i.e. population average) sperm cryo-resilience. Highly cryo-resilient ejaculates (High_CR, n = 5) maintained > 50% sperm total motility relative to fresh samples following cryopreservation and post-thaw incubation, as well as acrosome integrity post-thaw. These samples had significantly higher expression of A1BG, APBB1, KRT1, KRT10, LOC609402 and LOC100685620 (AGP) proteins in seminal plasma, and significantly reduced expression of RHOA, NUP62, SMYD4, ARHGD1B, CAPG, CSTB, and CFL1 proteins in sperm compared with Baseline cryo-resilient samples (Base_CR, n = 5). Differences in protein expression indicated that alterations in physiological pathways including blood clotting cascades (seminal plasma) and both actin dynamics and immune pathways (sperm) are associated with sperm cryo-resilience. This new knowledge may prove useful in future optimization of semen cryopreservation and assisted reproductive technologies for the critically endangered Red Wolf.