ACTIVITIES OF THREE DIGESTIVE ENZYMES DURING DEVELOPMENT IN THE CRAYFISH PROCAMBARUS CLARKII (DECAPODA)

Enzyme extracts were used to characterize α-amylase-, trypsin-, and nonspecific-esterase-specific and total activities during the early life-history stages of the red swamp crayfish Procambarus clarkii. Significant increases in the specific activities of all three digestive enzymes were observed prior to the onset of feeding, suggesting that digestive competence is attained prior to feeding and appears to be controlled genetically. After the onset of feeding, the digestive-enzyme-specific and total activity increased steadily through the 42nd day of development, after which point activity did not change significantly. We hypothesize that the observed increase in specific activity reflects the maturation of the hepatopancreas, as greater amounts of digestive enzymes are being produced per unit weight of tissue. As individuals exceeded approximately 100 mg in total weight, specific activity was variable and did not change substantially. Further increases in total enzyme activity (total digestive ca...