Indagine sulle modificazioni post-traduzionali della tubulina e caratterizzazione funzionale dell’ovocita di ovino adulto e prepubere maturato in vitro e vitrificato

Study on tubulin post-translational modifications and functional characterization of ovine oocytes in vitro matured and vitrified.In the present thesis morphological, ultrastructural and metabolic conditions of adult and prepubertal IVM and vitrified ovine oocytes were explored, In IVM oocytes, by immunofluorescence, several tubulin post-translational modifications (total, tyrosinated, acetylated and detyrosinated, polyglutamylated and Δ2 tubulin) were investigated for the first time. Results revealed a well detectable signal only for total, tyrosinated and acetylated α-tubulin in both sheep and lamb oocytes. As regard tyrosinated and acetylated tubulin, there were no significant differences in their expression in sheep, while in lamb the acetylated level was predominant in comparison with tyrosinated. The different microtubular pattern between adult and prepubertal oocytes, suggest a possible role of microtubules in the acquisition of oocytes competence.In vitrified adult and prepubertal oocyte we assessed the ability to recover from vitrification-induced damages after warming. Tyrosinated and acetylated α-tubulin levels, mithocondrial pattern, ROS levels and developmental competence were investigated. Results revealed that vitrified/warmed sheep oocytes need an extra time to restore damage due the cryopreservation procedures. On the contrary the vitrified/warmed lamb oocytes showed structural damages in spindle and chromatin, with high rates of parthenogenetic activations, displaying a lack of molecular tools useful for both cytoskeleton reorganization and developmental competence.