Activity of 1,3-β-D-Glucanases and Expression of CG-GLU1 in the Mussel Crenomytilus grayanus (Bivalvia) in Three Bays of the Sea of Japan

The level of the specific activity of digestive enzymes and expression of their corresponding glucanase genes (Cg-glu1) were studied in Gray's mussels, Crenomytilus grayanus, collected from the mussels' assemblages in different parts of Peter the Great Bay (northwestern part of the Sea of Japan). Both methods demonstrated similar independent results: there is variability in the contribution of phytoplankton to the nutrition of mussels in different parts of Peter the Great Bay. The highest level of the specific activity of 1,3-β-D-glucanases and expression of the glucanase genes were detected in the mussels from Amursky Bay: the differences were significantly increased (p < 0.05) compared with the level of the specific activity of the digestive enzyme 1,3-β-D-glucanases in mussels from Vostok Bay and Ussuriisky Bay. In all three bays, young mussels consumed phytoplankton more actively than 20-year-old mussels.