Efeito Da α-L-Fucosidase sobre a modulação da zona pelucida e desenvolvimento de embriões bovinos produzidos in vitro

Abstract

Polyspermy during in vitro fertilization is still an important limitation in advances in in the production of bovine embryos in vitro, resulting in reduced embryonic development, early embryonic death or miscarriage. The oviduct is a reproductive organ with several functions, such as gamete transport, oocyte maturation, fertilization, early embryonic development, in addition to being responsible for the production of oviductal fluid. The glycoprotein α-L-fucosidase (FUCA), a glucosidase found in the oviductial fluid of mammals, is involved in the hydrolytic degradation of fucose, its substrate present in the zona pellucida (ZP), participating in the spermatozoa-oocyte connection through interactions with complementary glycans on the surface of the ZP, acting in the control of polyspermy. Our objective was to investigate the effect of the addition of FUCA during pre-IVF on the modulation of the zona pellucida, polyspermy control, embryonic development and quality of bovine blastocysts produced in vitro. In the frst experiment, the efect of FUCA (0.125 U/mL) was evaluated during the entire in vitro fertilization (IVF). However, it was demonstrated to be embryotoxic by completely inhibiting the blastocyst formation. In the second experiment, the FUCA (0.125 U/mL) was tested as short-term incubation before IVF (pre-fertilization step) for 30 min or 2 h, which demonstrated that FUCA treatment for 30 min resulted in ZP hardening. In the third experiment, a pre-fertilization FUCA treatment (1 h) at diferent concentrations (0, 0.0625, and 0.125 U/mL) showed that FUCA (0.0625 U/mL) improved pre-fertilization ZP hardening and tended to increase monospermic fertilization rates but did not improve embryo yield and quality. Together, it has been demonstrated that FUCA can induce oocyte pre-fertilization ZP hardening and might improve monospermic fertilization performance, and this efect is dependent on both variables (protein concentration and incubation time).