Glycobiology of sperm-egg interactions in deuterostomes

Abstract

The process of fertilization begins when sperm contact the outermost egg investment and ends with fusion of the two haploid pronuclei in the egg cytoplasm. Many steps in fertilization involve carbohydrate-based molecular recognition between sperm and egg. Although there is conservation of gamete recognition molecules within vertebrates, their homologues have not yet been discovered in echinoderms and ascidians (the invertebrate deuterostomes). In echinoderms, long sulfated polysaccharides act as ligands for sperm receptors. Ascidians employ egg coat glycosides that are recognized by sperm surface glycosidases. Vertebrate egg coats contain zona pellucida (ZP) family glycoproteins, whose carbohydrates bind to sperm receptors. Several candidate sperm receptors for vertebrate ZP proteins have been identified and are discussed here. This brief review focuses on new information concerning fertilization in deuterostomes (the phylogenetic group including echinoderms, ascidians, and vertebrates) and highlights protein-carbohydrate interactions involved in this process.

A Role for Acp29AB, a Predicted Seminal Fluid Lectin, in Female Sperm Storage inDrosophila melanogaster

“…Protein-carbohydrate interactions play important roles in many aspects of reproduction across a wide range of animal species. Such interactions are vital for sperm-egg fusion in both invertebrates and vertebrates (Rosati et al 2000;Mengerink and Vacquier 2001;Intra et al 2006), with egg glycoproteins acting as primary sperm receptors in many species. Moreover, recent studies have shown that protein-carbohydrate interactions are directly /Df(2L)ED611 (M) males in each of four replicates is shown.…”

Characterization of the Sperm Receptor for Acrosome Reaction-Inducing Substance of the Starfish, Asterias Amurensis

“…It is well established that saccharide chains of the egg coats play pivotal roles in the induction of acrosome reaction, but their structures remain to be determined except for some echinoderms (for reviews see Miller and Ax, 1990;Litscher and Wassarman, 1993;Mengerink and Vacquier, 2001). In these animals, a very long sulfated linear polysaccharide chain plays a key role in the induction of acrosome reaction and the sperm seem to recognize the highly ordered spatial arrangement of the sulfate moieties (Hoshi et al, 1999).…”

“…It involves the exocytosis of the acrosomal vesicle to expose the devices for penetration through the egg coats and for subsequent fusion with the egg plasma membrane (Longo, 1997). Although it is well established that the egg coat contains signal molecules for the induction of acrosome reaction, our knowledge on the chemical structure of such molecules is much limited except for some echinoderms (for reviews see Miller and Ax, 1990;Litscher and Wassarman, 1993;Mengerink and Vacquier, 2001). In sea urchins, egg jelly polysaccharides such as the fucose sulfate polymer (FSP) (Vacquier and Moy, 1997;Alves et al , 1997Alves et al , , 1998VilelaSilva et al ., 1999) plays a key role for the induction of acrosome reaction though some other jelly components are involved in the induction (Yamaguchi et al ., 1987;Hirohashi and Vacquier, 2002).…”

High Molecular Mass Egg Fucose Sulfate Polymer Is Required for Opening Both Ca2+ Channels Involved in Triggering the Sea Urchin Sperm Acrosome Reaction

“…Linear polymers of ␣-L-1,3-sulfofucose are only known in echinoderms (10), the single invertebrate phylum leading to the evolution of vertebrates (29). In addition to egg jelly coats, these polymers are also found in the extracellular matrix of the adult body wall in echinoderms (30).…”