Isolation and identification of a novel toxin in scallop mantle tissue

Abstract

Scallops are one of the main marine products of Hokkaido, Japan. In addition to adductor muscle, scallop mantle tissue is often consumed in Japan. Previously, we showed that feeding mice a diet containing 1% mantle tissue resulted in lower food consumption and, ultimately, death. In this study, we isolated and identified toxic substances from scallop mantle tissue. The isolated toxic substances were protein complexes with molecular weights of 18 kDa and 29 kDa. Feeding mice a diet containing 0.05% toxic substances led to their death at five weeks. Based on LC-MS/MS analysis, the 29-kDa and 18-kDa proteins were identified as an actin fragment and the N-terminal fragment of the gelsolin-like protein, respectively. The 18-kDa protein was expressed in the mantle, gill, and ovary but not in the adductor muscle, testis, or midgland. Toxicity was observed only in mouse tissues expressing the 18-kDa protein. Feeding mice a diet containing only the 18-kDa protein did not induce decreased food consumption or death, implying that both the 29-kDa and 18-kDa complexes are essential for toxicity. This is the first study to identify a novel toxin in scallop tissues.