Cholecystokinin-like Immunoreactivity in the Dungeness Crab, Cancer Magister

ab, £. magister were found to contain cholecystokinin-like peptides by radioimmunoassay. Pyloric (2.3 pmol/g), gastric mill (4.6 pmol/g), and cardiac (13.0 pmol/g) stomach regions contained extractable immunoreactive material. Other tissues, including CNS and eyestalks, had unmeasureable levels. Fractionation of a stomach extract on Sephadex G-50 revealed three major peaks, one corresponding to the void volume, one at the approximate position of gastrin-17, and one intermediate in size. Blood samples from fasted and fed crabs contained measureable immunoreactivity (109.1 fmol/ml) which did not fluctuate significantly over a 24 hour period. Conclusions: (1) £. maglster stomachs contain cholecystokinin-llke peptides. (2) The immunoreactivity can be fractionated Into at least three MW forms, (3) Substantial immunoreactivity is present in £. maglater blood but does not appear to change after feeding.