Localization of egg-surface carbohydrates and fertilization in Discoglossus pictus (Anura).
The distribution of carbohydrates on the unfertilized egg surface in regions receptive or refractory to sperm penetration was analysed in the anuran amphibian Discoglossus pictus by means of a panel of lectins at the level of both the light and electron microscope. Results showed that a gradient of fucosyl-containing glycoconjugates was present at the pre-determined site of sperm entrance and topographically overlapped a similar gradient in sperm entry previously reported. Of a number of simple and complex carbohydrates examined for their ability to inhibit fertilization, fucoidan, ascophyllan and fucose affected the sperm-egg interaction. These sugars, although not decreasing sperm motility or triggering the acrosome reaction, rendered the sperm unable to penetrate the egg jelly coats. The possible involvement of fucosyl-containing glycoconjugates in the sperm-egg interaction in Discoglossus pictus is discussed.
Gualtieri
R
R
Dipartimento di Biologia Evolutiva e Comparata, Università di Napoli "Federico II", Via Mezzocannone 8, I-80134 Napoli, Italy.
Andreuccetti
P
P
D000818:Animals; D001001:Anura / Q000378:metabolism*; D002241:Carbohydrates / Q000032:analysis*; D005260:Female; D005643:Fucose / Q000032:analysis; D006001:Glycoconjugates / Q000737:chemistry* / Q000502:physiology; D037102:Lectins; D008297:Male; D008854:Microscopy, Electron; D009865:Oocytes / Q000737:chemistry*; D011134:Polysaccharides / Q000032:analysis; D013084:Sperm-Ovum Interactions; D013499:Surface Properties
D002241:Carbohydrates; D006001:Glycoconjugates; D037102:Lectins; D011134:Polysaccharides; C058519:ascophyllin; D005643:Fucose; C007789:fucoidan