Each specimen was thawed and then homogenized by vigorous shaking with some zirconia beads and 1% sarcosyl extraction buffer. The volume of extraction buffer was 200 μL. The samples were shaken for 15min at room temperature on a vortex mixer equipped with a multiple-vial head. The samples were then diluted with 10 mM Tris buffer (1.8 mL) to reduce the sarcosyl concentration to 0.1%, and were shaken again for 5min. They were then centrifuged (15 000g) for 10 min to separate insoluble copepod remains.