Oviductal protease and trypsin treatment enhance sperm-envelope interaccion in Bufo arenarum coelomic eggs

LLANOS RICARDO; BARRERA ANTONIO DANIEL; VALZ GIANINET JORGE N; MICELI DORA CRISTINA

Journal of Experimental Zoology

WILEY lISS

Lugar: New York; Año: 2006 vol. 306 p. 872 - 882

1932-5223

Oviductal Protease and Trypsin Treatment Enhance Sperm–envelope Interaction in Bufo arenarum Coelomic Eggs RICARDO J. LLANOS, DANIEL BARRERA, JORGE N. VALZ-GIANINET, AND DORA C. MICELI _ Departamento de Biologý´a del Desarrollo, Instituto Superior de Investigaciones Biolo´gicas (INSIBIO), T4000ILI San Miguel de Tucuma´n, Repu´blica Argentina ABSTRACT We describe the morphological and biochemical changes in Bufo arenarum coelomic egg envelopes (CE) following passage through the oviduct. In this species, the transformation of the CE into the vitelline envelope (VE) leads to the acquisition of fertilizability and involves the cleavage of a glycoprotein component. Electrophoretic patterns indicate that a pars recta oviductal protease selectively hydrolyzes in vitro the 84 and the 55 kDa glycoproteins of the CE. During the CE to VE transformation, the relative concentrations of gp48, 42 and 39 kDa also change. In in vitro tests, sperm binding to envelope glycoprotein occurs when they are exposed to VE but not when treated with CE, and VE labeled glycoproteins bind to the head and mid piece of the sperm. The gp39 VE component has 100% identity with internal domains of the sequence deduced from ovarian cDNA for the homologous zona pellucida glycoprotein type C (ZPC) protein precursor in B. arenarum. The effects of trypsin as a substitute for oviductal protease were also examined. Trypsin selectively attacks the 84 and the 55 kDa glycoproteins without hydrolyzing other components and renders coelomic eggs fertilizable in a jelly water preparation. Therefore, trypsin can mimic in vitro the biological action of the oviductal protease. However, it does not wholly mimic the biological action of the oviduct which, in B. arenarum at least, exceeds a mere proteolytic effect. This fact was verified by the lower fertility rates and the abnormal embryo development found when trypsin-treated coelomic eggs were fertilized in vitro. J. Exp. Zool. 305A:872–882, 2006. JOURNAL OF EXPERIMENTAL ZOOLOGY 305A:872–882 (2006)