Vitrification alters acH4K12 and acH4K16 levels in sheep oocytes at various developmental stages

Compelling evidence suggests that acetylation at histone H4 lysine 12 and 16 (acH4K12 and acH4K16) influence oocyte competence. The current study was conducted to determine the effect of vitrification on acH4K12 and acH4K16 patterns in sheep oocytes. Vitrified/warmed oocytes or fresh oocytes were collected at GV, GVBD, MI and MII, and acH4K12 and acH4k16 were assessed using fluorescent staining. Confocal microscopy analyses revealed that acH4K12 and acH4K16 at GV, MI and MII were significantly higher in vitrified/warmed oocytes than in fresh oocytes (P < 0.05). Vitrification failed to change acH4K12 and acH4K16 levels in sheep oocytes at the GVBD stage (P > 0.05). In summary, vitrification alters the acH4K12 and acH4K16 levels in mature and immature sheep oocytes, which likely contributes to the impaired development of vitrified oocytes after fertilization.