This research seeks to identify the pigments responsible for the ground color in pearls and pearl shell nacre, and to develop compounds and delivery systems which would provide better control of the color of pearls harvested on any farm. APPROACH: The presence of melanins and porphyrins would be inferred from trials for screening of different promoters or inhibitors. Reduced levels of tyrosinase activity in adult oysters exposed to tyrosinase inhibitory compounds will also be used to infer the presence of melanins. Carotenoids would be identified by spectrophotometric scans of extracts of nacre, and subsequent HPLC analysis. Spat trials will screen various compounds to see if they inhibit or promote formation of specific pigments. Tests will be evaluated by comparison by naked eye, tyrosinase activity assays, and carotenoid identification by HPLC. A novel delivery system, the Consumable Clod Card (CCC), will be tested and refined as a means to administer these promoters or inhibitors in a commercial farm situation. NON-TECHNICAL SUMMARY: The color of nacre is one of the most significant criteria in determining the value of a pearl. Nacre color is due to both schemochromic phenomena and biochromes (pigments). The vast majority of pearl farm profits comes from the small percentage of pearls that have a perfect surface, good color, and high luster. Even small increases in these quality factors can radically increase profits. Positive results from this work will allow us to gain some control over these important characteristics and produce higher value pearls. This patentable technology would increase the profitability of BPI affiliated farms, and allow additional income through licensing agreements with other farms.
Keywords: pearl culture; pearl oyster; pigment; nacre
