Abstract

Caspases are crucial mediators of programmed cell death (apoptosis). Apoptosis can occur in spermatozoa during spermatogenesis or epididymal transit, as well as in ejaculated spermatozoa. A high proportion of apoptotic sperm would be a poor indicator of the freezability of a raw seminal sample. Alpaca spermatozoa are notoriously difficult to freeze successfully. Therefore, the objectives of this study were to study caspase activation during incubation (37 degrees C) of fresh alpaca spermatozoa, as well as before and after cryopreservation, to gain some insight into the mechanisms behind the vulnerability of alpaca spermatozoa. Eleven sperm samples were incubated for 4 h at 37 degrees C (Study 1), and 23 samples were frozen using an automated system (Study 2). Caspase-3/ 7 activation was assessed at 0,1,2,3, and 4 h in samples incubated at 37 degrees C (Study 1); and before/after cryopreservation (Study 2) using CellEventT Caspase 3/7 Green Detection Reagent and flow cytometry. The proportions of alpaca spermatozoa with caspase-3/7 activated increased (p < 0.05) after 3-4 h of incubation at 37 degrees C; however, caspase activation was similar before and after cryopreservation (36.2 +/- 11.2% vs. 36.6 +/- 33.7%, p > 0.05). The high standard deviation found after freezing could be explained by the existence of two subpopulations: one subpopulation where caspase-3/7 activation decreased during cryopreservation (from 36.6 +/- 9.1% to 1.5 +/- 2.2%), and the other subpopulation where caspase-3/ 7 activation increased after cryopreservation (from 37.7 +/- 13.0% to 64.3 +/- 16.7%). In conclusion, after 3-4 h of incubation, caspase-3/7 activation increased in fresh alpaca sperm, whereas cryopreservation affects alpaca sperm samples in different ways.

Keywords

alpaca; apoptosis; Caspase-3/7; cryopreservation; spermatozoa

Published in

Reproduction in Domestic Animals
2023, Volume: 58, number: 7, article number: 5

SLU Authors

• Morrell, Jane

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Clinical Science


Publication identifier

DOI: https://doi.org/10.1111/rda.14397

Permanent link to this page (URI)

https://res.slu.se/id/publ/122500