Molecular mechanisms involved in the activation of Amphibian sperm motility

EMMA O’BRIEN; DARIO KRAPF; PABLO E. VISCONTI; CABADA MO; SILVIA E. ARRANZ

Holderness School, Plymouth, NH, EEUU

Conferencia; Gordon Research Conference on Fertilization and Activation of Development.; 2009

Gordon Researach Conferences

Molecular mechanisms involved in the activation of motility in Bufo arenarum spermatozoa In animals with external fertilization as amphibians, gamete interactions are first established between sperm and molecules of the egg jelly coat released into the water. Hypotonic solution containing these substances is called egg water (EW). Spermatozoa are stored in a quiescent state in the testis, but after spawning, dilution into water triggers the activation of motility. The aim of the present work was to study the signaling pathway of sperm motility activation in Bufo arenarum. Sperm were immotile in artificial seminal plasma (ASP) and became motile in hypotonic solutions (ASP 10% and EW). A direct correlation could be observed between motility and protein ser/thr phosphorilation. However, the pattern of phospho-proteins, and the percentage of progressive movement were different between EW or ASP10% preincubated sperm. Using PKA inhibitors (H98) and activators (db-cAMP, 8Br-cAMP), we showed that cAMP and PKA activity play a key role in B. arenarum sperm flagellar activation. Sperm incubation in forskolin-containing isotonic solutions also triggers protein phosphorilation and motility, suggesting that a transmembrane adenylyl cyclase could be involve in flagellar activation. The absent of the mammalian soluble adenylyl cyclase activators, HCO3- and Ca2+, in hypotonic incubation media did not prevent ser/thr protein phosphorilation. Our results suggest that the tmAC/cAMP/PKA signaling pathway is required for the motility activation in Bufo arenarum sperm.