Oral Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

Zincing outside the box: in vitro bovine embryo development by zinc chelation (#167)

Rhiannon J Gurkin 1 , Yasser Alrauji 1 , Margot Veron 1 , Patricio D Palacios Benitez 1 , Stephen Johnston 2 3 , Andres Gambini 1 3
  1. School of Agriculture and Food Sustainability , The University of Queensland, Gatton, QLD, Australia
  2. School of the Environment, The University of Queensland, Brisbane, QLD, Australia
  3. School of Veterinary Sciences, The University of Queensland, Gatton, QLD, Australia

In vitro embryo production is transforming the bovine industry. One crucial aspect of successful embryo production is oocyte activation (OA). This sperm-induced event involves oocyte calcium oscillations and zinc sparks that can be mimicked by calcium ionophores particularly ionomycin, or zinc chelators including 1,10-phenanthroline (PHEN). Although the role of calcium has been deeply studied, zinc involvement during OA in bovine remains less understood. This study aimed to evaluate if zinc supplementation during oocyte maturation improves efficiency of preimplantation development, and to test different PHEN concentrations and incubation timings to enhance embryo development and quality. Oocytes were collected from abattoir ovaries and matured for 24h at 38.5°C with or without the addition of 1 μg/mL zinc sulfate. Matured oocytes were activated with 5 μM ionomycin for 4 min (control) or by incubation in 250 or 500 μM PHEN for 30 or 60 min. Day 7 blastocysts were measured and stained to determine total cell number (DAPI), and the proportion of +γH2AX cells (DNA fragmentation, %), were analysed using confocal microscopy. Although no differences in blastocyst development rate, diameter, and cell number were observed with the addition of zinc between control and PHEN groups, maturation rates improved (269/341, 78.88% vs. 190/212, 89.62%), and blastocyst DNA fragmentation levels were reduced, regardless of the method of activation, mean ± SEM: 7.73 ± 0.79 vs. 4.80 ± 0.81. Surprisingly, 250 μM PHEN for 60 min achieved similar cleavage and blastocyst rates compared to the control with no differences in total cell number or DNA fragmentation levels (Table 1). Our study found that zinc supplementation during maturation does not impact on preimplantation development, but it reduces blastocyst DNA fragmentation levels. Outstandingly, the optimal zinc chelation treatment was achieved to effectively induce OA without impairing embryo development or quality. These results will significantly advance cattle breeding programs.66b46f0ce8f57-Table+1+SRB+Abstract.png