Physiological modification of Bufo arenarum sperm during motility activation.

O´BRIEN E.; KRAPF, D.; CABADA, M.O.; ARRANZ, S.E.,

Carlos Paz, Córdoba, Argentina

Congreso; XLIV Reunión Anual – Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2008

Sociedad Argentina de Investigación Bioquímica

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). Immotile in the seminal tract, sperm initiate their motility upon spawning in hypotonic medium. The aim of present work is to identify physiological modifications during toad sperm motility activation guided by osmolarity changes and EW components. Both osmolarity and ionic composition of Bufo seminal plasma (SP) were determined. Membrane potential (Em) changes were analyzed using fluorescent dye DiSC3 (5) and sperm motility was studied using optical microscopy. Sperm protein phosphorylation was studied by western blot analisys. Sperm were immotile in artificial SP solution (ASP: 303 mOsm/Kg, [K+]=39 mM, [Na+]=105 mM) and presented a membrane depolarized state. Sperm became motile in solutions with osmolarities below 200 mOsm/Kg. Both Em hyperpolarization and ser/thr phospo-proteins were detected only in sperm preincubated in hypotonic solutions (10% ASP and EW). Fast and linearly swimming pathway was identified in EW preincubated spermatozoa suggesting that jelly components trigger sperm “hipermotility”. Our results suggest that toad sperm motility is correlated with changes in Em and protein phosphorylation.