Effects of LPS injection on circulating haemocytes in crustaceansin vivo

Lipopolysaccharide (LPS) endotoxin is an integral component of the outer membrane of Gram-negative bacteria. In crustaceans, it elicits rapid and massive degranulation of haemocytesin vitroand often depletion of haemocytes (haemocytopenia)in vivo. LPS toxicity, however, has never been tested systematically on crustaceansin vivoso its effects on circulating blood cell counts are unknown. This paper defines LD50for LPS toxicity by injections intoPalaemon elegans(Rathke),Crangon crangon(L.) andSquilla 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) andIlia 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 LPSin vivoinS. mantisandN. norvegicusis lower (by two orders of magnitude) than inP. elegans,C. crangonorM. 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.