Effects of dietary zinc on the shell biomineralization in abalone Haliotis discus hannai Ino

A study was conducted to investigate the relationship between dietary zinc and shell biomineralization in abalone Haliotis discus hannai Inc. Seven triplicate groups of juvenile abalone (mean weight: 0.74 +/- 0.01 g; mean shell length: 16.41 +/- 0.04 mm) were fed with one of seven semi-purified diets containing graded levels of dietary zinc (5.6, 10.7, 15.1, 25.2, 34.7, 45.3 and 84.6 mg/kg). To better understand the effects of dietary zinc on the shell deposition, the newly grown shell (NS) was separated from the old shell (OS) after a 16-week rearing period. Mineralogical (aragonite, calcite and dolomite [CaMg(CO3)(2)]) and chemical (Zn, Fe, Mg, Cu and Sr) compositions in both NS and OS were analyzed. Soluble matrix proteins (SMP) were extracted from both OS and NS, followed by amino acid composition analyses. The results showed that mineralogical and chemical compositions in OS were not significantly influenced by dietary zinc. In NS, however, increasing dietary zinc significantly decreased aragonite content, but significantly increased calcite content. Concentrations of Zn and Fe in NS significantly increased with dietary zinc. Patterns of amino acid compositions in NS significantly changed with dietary zinc levels. The ratio of acidic/basic amino acids positively correlated with the ratio of calcite/aragonite in NS. (C) 2003 Elsevier Science B.V. All rights reserved.