Effects of vitamins A and D on shell biomineralization of abalone Haliotis discus hannai, Ino

A 152-day feeding trial was conducted in a recirculating water system to investigate the effects of vitamins A (retinol) and D (cholecalciferol) on shell biomineralization of the abalone Haliotis discus hannai Ino. Triplicate groups of juvenile abalone (initial weight: 0.35 +/- 0.03 g; initial shell length: 11.3 +/- 0.25 mm) were fed to satiation daily with one of the 16 semipurified diets containing 0.1 x 10(3), 1 x 10(5), 1 X 10(6) IU/kg vitamin A and 0, 500 1 x 10(3), 5 x 10(3) IU/kg vitamin D in a 4 x 4 factorial design. The results showed that vitamin D significantly increased the ratio of calcite/aragonite in the shelf, in the case of deficient (0 IU/kg) or excessive (1 X 10(6) IU/kg) dietary vitamin A supplementation. When dietary vitamin A supplementation ranged from 1 X 10(3) to 1 X 10(5) IU/kg, vitamin D significantly decreased the ratio of calcite/aragonite in the shell. The concentrations of Mg, Zn, and Sr in the shell were independent of the supplementation of these two vitamins. Meanwhile, the contents of Ca, P, and Cu in abalone shell increased with supplementation of the vitamins A and D, and significant interaction between vitamin A and D was observed on the concentrations of both Ca and Cu in shell. Vitamin A, instead of vitamin D, significantly increased Fe concentration in shell. Trends of the ratio of acidic/basic amino acids [(Asx + Glx)/(Lys + Arg + His)] in the shell soluble matrix protein (SMP) changing with dietary vitamin A and D were in agreement with those of the ratio of calcite/aragonite in the shell. The two vitamins did not change the shell ultrastructure as shown by scanning electron microscopy (SEM) and components of SMP expressed by SDS-PAGE.