Clark T. Fontaine

Observations on the phagocytosis and elimination of carmine particles injected into the abdominal musculature of the white shrimp, Penaeus setiferus☆

Abstract White shrimp, Penaeus setiferus, were injected in the abdominal musculature with 0.03 ml of a 1.4% carmine-saline solution and were kept at a temperature of 26°–28°C and a salinity of 23–26‰. Tissue samples were taken at hourly intervals of 1, 6, 12, 18, 24, 30, 36, 42, and 72 hr and at 4, 6, 8, 10, 12, 16, 19, and 33 days post-injection and were examined histologically to determine the sites of phagocytosis and elimination of foreign particulate matter. Within 1 hr post-injection, extracellular clumps of the carmine particles were formed in the hemolymph. These clumps had been invaded by hemocytes at 18 hr, but they persisted throughout the study. Phagocytosis of the particles was accomplished by hemocytes circulating in the hemolymph and by fixed phagocytes in the gill, heart, loose connective tissue, and blood sinusoids in the abdomen. The fate of some phagocytized carmine was climination by the migration of hemocytes through the epithelium of the gills, gut, hepatopancreas, and through the extremities of the pereiopods and the pleopods. Encapsulations or brown nodules were formed in the musculature of the pereiopods around necrotic hemocytes that had phagocytized carmine. A large blister or cyst filled with carmine was formed in the gill cover of one specimen. The obsevation of carmine particles at 33 days post-injection indicates a slow clearance rate of large amounts of abiotic particulate matter in penaeid shrimp.

A mycosis of the American lobster, Homarus americanus, caused by Fusarium sp.

Abstract A mycosis in cultured American lobsters, Homarus americanus , is described. The causative agent, a pigment-producing Fusarium sp., was isolated from diseased lobsters from an experimental “lobster farm” in New York. Affected lobsters had “black spots” of various sizes on the exoskeleton and appendages and brownish discoloration of the gills. Hyphae and conidia of the Fusarium sp. were present in or on these lesions.

Observations on the process of wound repair in penaeid shrimp

Abstract The Petersen disk tag is a standard mark for penaeid shrimp, and attachment of the tag involves the insertion of a stainless steel pin through the shrimps abdomen, resulting in a relatively large puncture wound. The wound healing process first observed at 24 hr post-tagging showed a pronounced hemocytic infiltration of the wound area. Hemocytes in contact with the pin became fusiform, began adhering to one another, and formed several concentric layers around the pin. Scattered foci of bacteria or nercrotic tissue in the vicinity of the would also became encapsulated by concentric layers of fusiform hemocytes, thereby forming nodules. Melanin appeared in association with the layers of hemocytes nearest the pin and in the nodules. Hemocytic infiltration was lollowed by the appearance of fibrocytes and the deposition of collagenlike fibers along the would channel 48 hr after wounding. Involution of epidermis and consequential cuticular involution into the would channel began at 96 hr after wounding. Complete epidermal and cuticular formation along the wound occurrd by 384 hr post-tagging.

A new fungus disease of the white shrimp Penaeus setiferus.

Abstract A primary mycosis of larvae of the white shrimp, Penaeus setiferus, is described. The disease first became apparent in larvae in the second protozoeal stage and disappeared as the shrimp reached the first mysis stage. Affected shrimp became immobilized by near complete tissue destruction and replacement by the expanding mycelium. The fungus was found to be Lagenidium sp. and was infective to larval brown shrimp, Penaeus aztecus.

Host response in the white shrimp, Penaeus setiferus, to infection by the larval trypanorhynchid cestode, Prochristianella penaei

Abstract White shrimp, Penaeus setiferus, infected by the plerocercoid larva of the trypanorhynchid cestode, Prochristianella penaei, respond to infections in the heptaopancreas by developing a progressively denser cyst, composed of hemocytes, fibroblasts, and collagenlike fibers, around the parasite. The pleocercoid is eventually destroyed and resorbed leaving a dense fibrous capsule in the hepatopancreas. Worms in the adjacent hemocoel are encapsulated by a thin host cyst and a less intense infiltration of cells and deposition of fibers, insufficient to destroy the pleroceroid. It is believed that the resorption process explains the drop in intensity of infection in juvenile white shrimp after a certain size is attained.

Histopathological response to turpentine in the white shrimp, Penaeus setiferus☆

Abstract Observations are presented on the inflammatory response to a highly irritative substance, turpentine, injected into the abdominal musculature of the white shrimp, Penaeus setiferus . Injections of the irritant were administered with a tuberculin syringe between the fifth and sixth segments. Penaeid shrimp were found to be highly sensitive to turpentine, even when administered in small dosages. When sterile petroleum jelly was mixed with the turpentine to reduce the dispersion rate, the shrimps “internal defense mechanism” was able to combat effectively the effect of the irritant. Postinjection observations of the tissues at the site of injection, gill, heart, and hepatopancreas were made at 8, 16, 24, 32, 40, 48, 72, 96, 120, 168, and 240 hr, and at 15, 20, 30, 40, 50, 60, and 120 days. The induced cellular inflammatory response consisted of infiltrating hemocytes and fibrocytes resulting in the formation of fibrous capsules, brown melanized nodules, and fibrous scar tissue in all tissues examined. The gills and hepatopancreas showed considerable tissue destruction early, but were eventually cleared of the histopathological effects of the turpentine and later appeared normal. However, extensive tissue destruction was easily distinguishable in the heart and abdominal muscle even at 120 days postinjection.