A correlated morphological and biochemical study of capsular fluid of Nucella lapillus (Gastropoda: Prosobranchia: Muricidae)

The extra-embryonic albuminous capsule fluid of the marine prosobranch Nucella lapillus L., collected from March to May 1988 in Brittany, France, has been investigated by sodium dodecylsulfate-polyacrylamide-gelelectrophoresis (SDS-PAGE) and biochemical assays. The fluid at the gastrula- and early veliger stage of the snail embryo was analysed for proteins on SDS-gels, i.e., for acid phosphatase, alkaline phosphatase, -glucuronidase and arylsulfatase activities. The protein and inorganic phosphorous contents were also determined. Electrophoresis revealed the presence of different proteins and a variation in the band pattern during early developmental stages. The total protein content of the capsule fluid decreases significantly from gastrula to early veliger stage. In the differentiated developmental stage the acid phosphatase activity was higher than the poorly differentiated gastrula stage. The detected activity of arylsulfatase indicates that acid mucopolysaccharides are present. In general, observed changes in the organic components of the intracapsular fluid of N. lapillus substantiate the nutritive value for developing embryos.