Seasonal changes in contractile activity of a toxic substance from the pedicellaria of the sea urchin Toxopneustes pileolus.

The seasonal change in the activity of an extract from the pedicellariae of the sea urchin Toxopneustes pileolus was investigated in terms of contraction of the longitudinal muscle of the isolated guinea-pig ileum. The protein level of the crude extract from the pedicellariae was high in May, June and July, but was not parallel to the activity of the extract which was low in summer (0.03 X 10(3)-0.33 X 10(3] and became higher in autumn and winter (0.51 X 10(3)-1.1 X 10(3]. The changes in protein level and the specific activity of the extract were also not closely correlated to the reproductive season of the sea urchins. The specific activity of Peak II fraction purified from the extract was high in spring (May), lowest in summer and elevated again in autumn and winter.