Changes in digestive enzyme activities during different developmental stages of the crayfish Astacus leptodactylus Eschscholtz, 182

Abstract

The present study determined changes in protease, α-amylase and lipase activities during embryonic and post-embryonic developmental stages of the freshwater crayfish <em>Astacus leptodactylus</em> Eschscholtz, 1823. The embryonic stages studied comprised Phase III (blastula formation), Phase X (embryos with anlagen of masticatory) and Phase XIV (embryos with strongly developed posterior hepatopancreas lobes). The post-embryonic stages comprised Stage I (no feeding) and Stage II (prior to the onset of feeding). Protease and α-amylase activities were relatively high as compared with lipase activity. Protease activity values showed a steady increase from Phase III to Stage I. α-amylase and lipase activities were low in Phase XIV. The activities of these two enzymes tended to increase just before hatching and reached the highest levels in Stage II. Digestive enzyme activities increased in accordance with maturation of the hepatopancreas and prior to the onset of external feeding. Protease activity was high in the early stage of embryonic development and continued to increase in later stages. On the other hand, α-amylase and lipase activities were low until maturation of the hepatopancreas and then remained high. The results of the present study provide important information on changes in digestive enzyme levels during different developmental stages of <em>A. leptodactylus</em>.