Effects of LPS injection on circulating haemocytes in crustaceans in vivo

Abstract

Lipopolysaccharide (LPS) endotoxin is an integral component of the outer membrane of Gram-negative bacteria. In crustaceans, it elicits rapid and massive degranulation of haemocytes in vitro and often depletion of haemocytes (haemocytopenia) in vivo. LPS toxicity, however, has never been tested systematically on crustaceans in vivo so its effects on circulating blood cell counts are unknown. This paper defines LD50 for LPS toxicity by injections into Palaemon elegans (Rathke), Crangon crangon (L.) and Squilla mantis (Fabr.) characterized by different habitats, temperature ranges or water quality. Moreover, it investigates the differential effects of temperature acclimatization on LPS tolerance, and describes the effects of injected LPS on circulating blood cell counts (THC) in the following decapods - Nephrops norvegicus (L.), Munida rugosa (Fabr.), Paguristes oculatus (Fabr.), Pilumnus hirtellus (L.), Macropipus vernalis (Risso), Parthenope massena (Roux) and Ilia nucleus (L.) - thus clarifying the lethal level of haemocytopenia and the time course of recovery to sublethal doses of this lipopolysaccharide. Our results show that tolerance to LPS in vivo in S. mantis and N. norvegicus is lower (by two orders of magnitude) than in P. elegans, C. crangon or M. vernalis. This difference in sensitivity to LPS is not related to a difference between stomatopod and decapod taxa or to the initial number of circulating haemocytes. Instead it may relate to life habits. The results show that LPS causes a decrease in the number of circulating haemocytes as a generalized response in crustaceans, but the time to reach maximum haemocytopenia and the extent of cell loss are species-specific and not affected by temperature. © 1999 Academic Press.