The relationship between hyperactivated motility and protein tyrosine phosphorylation in two different IVF media for bull, boar and stallion spermatozoa.

Abstract

This study is an orientating study with the aim to provide a comprehensive basic characterization of hyperactivated motility patterns in species with functional IVF systems, i.e. cattle and pigs. It was also aimed to compare the observed motility changes in stallion spermatozoa which are subjected to bovine or porcine in vitro fertilization (IVF) conditions. The occurrence of tyrosine phosphorylation in the tail of viable spermatozoa under the respective incubation conditions was visualized by indirect immunofluorescence. Spermatozoa of boar, bull and stallion were incubated under established IVF conditions. For boar sperm the IVF medium modified tris buffered medium (mTBM) was used and for bull sperm a modified TALP medium was used. Stallion spermatozoa were incubated in both media. The motility patterns after 0.25, 1-6, 8 hours incubation were analyzed with a CASA system and statistically divided into clusters by hierarchical cluster analysis. The occurrence of tyrosine phosphorylation in the tail of viable spermatozoa under the respective incubation conditions was visualized by indirect immunofluorescence at selected time points. Live - dead staining was performed using Ethidium homodimer-1 and Hoechst 33342. The basic characterization of hyperactivated motility under successful IVF circumstances was not possible due to immediate agglutination of both boar and bull spermatozoa. Furthermore the development of hyperactivated motility and protein tyrosine phosphorylation in stallion spermatozoa seemed independent. The bovine IVF protocol appeared to have a higher efficiency in inducing protein tyrosine phosphorylation of the sperm tail of viable stallion sperm In conclusion this thesis supports the idea that protein tyrosine phosphorylation of the sperm tail might not be relevant for fertilization.