B. Howarth

Carbohydrate Involvement in Sperm-EGG Interaction in the Chicken

The solubilized perivitelline layer (PL) of the chicken ovum contains one or more components which behave in a manner analogous to sperm-receptors. Electrophoretic analyses of solubilized PL confirmed the existence of three major glycoproteins having apparent molecular weights of 33,000, 53,500 and greater than 200,000. The role of carbohydrate in sperm receptor activity was evaluated by extensive deglycosylation of the solubilized PL with trifluoromethanesulfonic acid (TFMS). Sperm receptor activity as measured by an in vitro competition assay was extremely sensitive to TFMS. Pretreatment of spermatozoa with solubilized PL exposed only to TFMS buffers inhibited sperm attachment and digestion of intact PL by 81% (9.67 +/- 1.76 sperm/mm2) as compared with the controls (i.e., no pretreatment of spermatozoa with solubilized PL; 51.33 +/- 6.24 sperm/mm2), a value similar to that observed with spermatozoa exposed to untreated solubilized PL (0.17 +/- 0.17 sperm/mm2). In comparison, PL treated with TFMS inhibited sperm attachment and digestion of intact PL by less than 26% (38.33 +/- 5.88 sperm/mm2) as compared with the control. These data indicate that removal of both N- and O-linked oligosaccharides from components of the chicken PL results in elimination of its sperm receptor activity.