EFFECT OF PROTEASES ON THE ECM OF AMPHIBIAN OOCYTES AND THEIR ROLE ON FERTILIZATION

LLANOS, RICARDO; VALZ-GIANINET, JORGE NELSON; BARRERA, DANIEL; MUSUMECI, HUMBERTO; MICELI, DORA CRISTINA

Tafí del Valle, Tucumán (Argentina)

Jornada; XVIII Jornadas Científicas de la Sociedad de Biología de Tucumán; 2001

Asociación de Biología de Tucumán

It is known that amphibian oviducal proteases produces changes in the oocyte´s ECM glycoproteins and that these changes would be responsible of the fertilizability acquired by eggs after crossing the oviduct. In previous studies, using isolated vitelline envelopes (VE) subjected to biotin conjugation, it was observed that union of labeled molecules to the sperm plasma membrane occured. In this work, the ultrastructural changes in B. arenarum coelomic VE (CE) after trypsin or oviducal pars recta fluid treatment was analyzed. It was also made an electrophoretic study of the isolated VEs, solubilized and then treated with trypsin. The trypsin treatment of CE affects the 84kD protein, which disappears after 3 min treatment. We observed that the trysin activity modifyed the proteins ranging 30 to 41 kD, giving a similar pattern to that of the uterine oocytes VE. At the ultrastructural level, after 60 seconds treatment with 0.001% trypsin, the VEs showed dispersion of the horizontal fibrils fascicles and disappearance of the characteristic spaces. The perpendicular fascicles to the surface are more diffuse, lossing their interaction with the horizontal fascicles. The internal face of the EV shows marked modifications, disappearing the reticular pattern and acquiring a diffuse aspect. The biological essays indicate that these transformations are related with the acquisition of the capacity of the VE to interactuate with the sperms.