CLEARANCE OF BACTERIA INJECTED INTO THE HEMOLYMPH OF THE PENAEID SHRIMP, SICYONIA-INGENTIS

Shrimp rapidly removed four strains of bacteria from their hemolymph. Total hemocyte counts (THC) dropped to 20% of preinjection levels during the 24 hr after injection and returned to preinjection levels by 72-96 hr. Shrimp with reduced THC were still able to clear bacteria from their hemolymph. Saline injections caused only a slight decrease in THC; endotoxin and laminarin injections mimicked the injection of bacteria. The mitolic index of hematopoietic stem cells was elevated during the recovery period. Use of radiolabeled bacteria showed that the gills are the main sites of clearance and that the digestive gland is not involved. Clearance mechanisms in the shrimp are compared to those of other crustaceans. © 1993 Academic Press, Inc.