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 capacity) were dependent primarily on increases in the weight gain of the individual. We suggest that the first four to six weeks of development may represent a crucial stage in the development of the hepatopancreas and that perturbations that occur during this stage of development may impact future growth. The pattern of digestive enzyme expression in Procambarus clarkii indicates little or no change in nutritional requirements and is different from the patterns observed in decapod crustaceans that have planktotrophic life-history stages. The digestive enzyme activities indicate that crayfish can digest and utilize primarily carbohydrates, proteins and, to a lesser extent, lipids as macronutrients during early growth.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 20 • No. 4