Effects of LPS injection on circulating haemocytes in crustaceans in vivo

Lipopolysaccharide (LPS) endotoxin is an integral component of the outer me mbrane of Gram-negative bacteria. In crustaceans, it elicits rapid and mass ive degranulation of haemocytes in vitro and often depletion of haemocytes (haemocytopenia) in vivo. LPS toxicity, however, has never been tested syst ematically 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 (Fa br.) characterized by different habitats, temperature ranges or water quali ty. Moreover, it investigates the differential effects of temperature accli matization on LPS tolerance, and describes the effects of injected LPS on c irculating blood cell counts (THC) in the following decapods-Nephrops norve gicus (L.), Munida rugosa (Fabr.), Paguristes oculatus (Fabr.), Pilumnus hi rtellus (L.), Macropipus vernalis (Risso), Parthenope massena (Roux) and Il ia 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 i s lower (by two orders of magnitude) than in P. elegans, C. crangon or M. v ernalis. This difference in sensitivity to LPS is not related to a differen ce between stomatopod and decapod taxa or to the initial number of circulat ing haemocytes. Instead it may relate to life habits. The results show that LPS causes a decrease in the number of circulating haemocytes as a general ized response in crustaceans, but the time to reach maximum haemocytopenia and the extent of cell loss are species-specific and not affected by temper ature. (C) 1999 Academic Press.