Chemical properties of egg-mass mucin complexes of the ommastrephid squid Todarodes pacificus

Abstract

This paper describes the properties of egg-mass glycoproteins from the Japanese common squid Todarodes pacificus (Steenstrup, 1880) and provides chemical evidence for the role of a nidamental mucosubstance in the formation of egg masses. Samples were collected from the surface layer and the interior jelly of an egg mass spawned in captivity, and the interior jelly was separated into fibrils and the liquid portion of the jelly. Mucosubstances in the nidamental and oviducal glands of maturing squid were then isolated and compared with those of each part of the egg mass. The surface layer and the interior fibrils were found to be composed of distinct types of mucin complexes and to have originated from the water-soluble and insoluble fractions of nidamental mucosubstance, respectively. Oviducal mucosubstance, however, appeared to play no role in the formation of the fibrils. These results suggest the egg-mass surface layer is derived from the water-soluble fraction of the nidamental mucosubstance, and the fibrils within the mass are derived from the insoluble fraction of the mucosubstance.