The secretion and composition of the bivalve crystalline style

Abstract

Modern investigative tools including electron microscopy, electrophoresis, and gas chromatography have been used to ascertain mode of secretion of the crystalline style present in bivalves and its composition. Macomona liliana and Amphidesma australe are the principal animals examined in the study. In both species, the bottom few millimetres of the style sac are found to differ from the upper part. This basal region contains more secretory cell types than are present higher up. In the upper part of the style sac, two cell types (B and D) are found to be the major style secretory cells, although in Amphidesma in particular, other cell types could play minor roles in secretion. In Macomona about tem proteins constitute the style. A group of large, complex, glycoproteins and a smaller non-conjugated protein are found to be the main style constituents. These are thought to play structural roles while the minor proteins may be enzymes. A new method of purifying proteins is introduced and amino acid compositions are determined by GLC for whole styles and major style proteins. Gas chromatography is also used to analyse the carbohydrate composition of the style and amounts of fucose, xylose, mannose, galactose, N-acetyl glucosamine, N-acetylgalactosamine and an unidentified sugar are measured. Some of the carbohydrate in the glycoprotein is linked to the protein through O-glycosidic linkages to serine and threonine. Improvements in methods of electrophoresis, gas chromatographic analysis of amino acids and carbohydrates are introduced.