DOI 10.1095/biolreprod.108.068296 Molecular Mechanisms Determining Sperm Motility Initiation in Two Sparids (Sparus aurata and Lithognathus mormyrus)

Molecular mechanisms involved in sperm motility initiation in two sparids (Sparus aurata and Lithognathus mormyrus) have been studied. Our comparative study demonstrates that osmo-lality is the key signal in sperm motility activation in both species, whereas Kþ and Ca2þ do not have any role. The straight-line velocity that resulted, however, was significantly different when measured in sperm activated with non-ionic and/or calcium-free solutions with respect to that measured in seawater-activated sperm. In both species, motility initiation depends on cAMP-dependent protein phosphorylation. The phosphorylation/dephosphorylation patterns that resulted in gilthead and striped sea bream were quite different. In gilthead sea bream, the phosphorylated proteins have molecular weight