Digestive enzymes in the ontogenetic stages of the southern king crab, Lithodes santolla

REINHARD SABOROWSKI,; KLAUS ANGER,; JAVIER CALCAGNO,; GUSTAVO ALEJANDRO LOVRICH

MARINE BIOLOGY

Año: 2006 vol. 149 p. 865 - 873

0025-3162

Abstract The early ontogenetic stages of the sub-Antarcticking crab Lithodes santolla were analyzed for thepresence and activities of a set of important digestiveenzymes. The eggs and non-feeding larvae (zoea I-III,megalopa) showed high activities of esterases, phosphatases,and exopeptidases indicating the enzymaticability to utilize endogeneous yolk reserves. SDS-PAGEshowed a continuous decrease of proteins or proteids inthe range of 59–81 kDa during ontogenetic developmentfrom the eggs through the zoeal stages to the first juvenilecrab stage, CI. This reduction reflects the degradationof storage compounds during lecithotrophic larvaldevelopment. Activities of the endopeptidases, trypsinand chymotrypsin, were low in eggs and larvae but increasedsignificantly in the first juvenile crab stage. Theseenzymes typically facilitate the first steps of proteolysisin the extra-cellular spaces of the midgut gland and inthe stomach. Their scarcity indicates that the larvae ofL. santolla are physiologically not prepared to digestexternal food. This ability seems to appear first in the CIstage. Extracts of juvenile midgut glands and the gastricfluids of adults showed high activities of a variety ofdigestive enzymes including phosphatases, carbohydrases,as well as endo- and exopeptidases. High activitiesof digestive enzymes in adults may compensate forscarce food supply and rate-limiting low temperatures inthe predominantly sub-Antarctic habitats of L. santolla.