Role of egg surface glycoconjugate in the fertilization of the rock shrimp Rhynchocinetes typus (Milne-Edwards, 1837)

During first gamete interaction, oligosaccharides on the glycoproteins present in oocyte envelopes of the rock shrimp, Rhynchocinetes typus, play an important role in spermatozoon recognition prior to the onset of penetration. These oligosaccharides have terminal monosaccharides that may be recognized by means of specific lectins. A variety of marine species have monosaccharides on their oocyte envelopes, allowing them to interact with the spermatozoa. The number and location of the monosaccharides varies during oocyte maturation. However, this phenomenon has not been studied in shrimp. The present study evaluates the presence and location of monosaccharides on oocyte envelopes during maturation using seven specific lectins conjugated to FITC (GNL, LCA, Con-A BS-1, LTA, GLS-II,DBA); these recognize mannose (α 1-3) mannose, α-mannose, α-glucose, glucose, galactose, fucose, N-acetyl-glucosamine, and N-acetylgalactosamine, respectively. Participation of these carbohydrates in the fertilization process was determined through the insemination of fresh oocytes with spermatozoa previously incubated with the different monosaccharides that block the active sites of the spermatozoa, inhibiting fertilization. The results showed the presence of N-acetyl-glucosamine and mannose on the oocyte envelopes, indicating that these sugars could be the receptors during the first gamete interaction. The results also suggested that glucose could be a complementary receptor to N-acetyl-glucosamine and mannose since, despite the low concentration of glucose on the envelope, this sugar generated a high degree of fertilization inhibition.