Tesis doctoral de Eva María Flores Valdepeñas
The aim of this work is to evaluate the effects of freezing-thawing process on different structures of porcine spermatozoa, such as nuclear structure, mitochondrial function and spermatic subpopulational structure. in the first study we tested the effect of freezing-thawing on the nuclear structure of porcine spermatozoa. Freezing-thawing did not cause dna fragmentation, although a clear destabilization of the protamine-1-dna complexes was apparent. This destabilization started after the cooling phase to 5ºc included in the freezing-thawing procedure. This indicates that this cooling phase is one of the most lethal phases during the freezing-thawing process of porcine spermatozoa. in the second study we evaluated the changes that the boar sperm motile subpopulational structure suffered during the freezing-thawing procedure taking into account the freezability of the ejaculates, as well as the mitochondrial activity and the mitochondrial formation of reactive oxygen species (ros). We observed 4 motile subpopulations in all the treatments (fresh and frozen-thawed) and all the freezabilities (good, average and bad freezers) studied. The response of the majority of the motility parameters studied after the freezing-thawing was very different in the bad freezers semen compared with the good freezers. Furthermore, in the study of the mitochondrial activity we observed that the bad freezers samples presented the lowest mitochondrial activity. finally, in the third work we studied the effect of the cryopreservation on the mitochondrial function of porcine spermatozoa. We evaluated the mitochondrial activity together with the rhythm of mitochondrial ros formation, as well as the expression and localization of two important proteins on the mitochondrial function, mitofusin-2 (mfn-2) and actin. We observed that mitochondrial activity as well as mitochondrial ros formation decreased during the freezing with an initial drop in the cooling phase. Furthermore we also observed changes on the expression and localization of mfn-2 and actin, which became apparent on the cooling phase. in conclusion, this study has demonstrated that the majority of the damage caused by the freezing-thawing process began during the cooling phase to 5ºc, being this step very important for sperm survival. The freezing-thawing process caused a nuclear destructuration, without causing nuclear fragmentation, as well as changes on the motile sperm subpopulational structure, being these changes more evident on ejaculates with the poorest freezing quality. Finally, freezing-thawing caused a decrease on the mitochondrial activity due to changes on the expression and localization of proteins which regulate mitochondrial function.
Datos académicos de la tesis doctoral «Effects of freezing-thawing on the nuclear structure, the mitochondrial function and the sperm subpopulational structure on porcine ejaculates«
- Título de la tesis: Effects of freezing-thawing on the nuclear structure, the mitochondrial function and the sperm subpopulational structure on porcine ejaculates
- Autor: Eva María Flores Valdepeñas
- Universidad: Autónoma de barcelona
- Fecha de lectura de la tesis: 06/11/2009
Dirección y tribunal
- Director de la tesis
- Juan Enrique Rodríguez Gil
- Tribunal
- Presidente del tribunal: sergi Bonet marull
- ann-sofi Bergqvist (vocal)
- (vocal)
- (vocal)