Tolerance of Shore Crabs to Tetrodotoxin and Saxitoxin and Antagonistic Effect of Their Body Fluid against the Toxins

Abstract

Lethal effects of tetrodotoxin (TTX) and saxitoxin (STX) on 6 species of nontoxic marine crabs, as well as effects of the toxins on their nerves, were investigated. There was wide variance among species examined for the lethal effect of TTX and STX. The tolerances of nerves are almost compatible to lethal tolerance with the exception of Hemigrapsus sanguineus. This species showed relatively high resistance to TTX, but its nerve was at almost the same level of tolerance as those of other TTX-sensitive crabs. In order to elucidate the mechanism for high TTX-resis-tance in H. sanguineus, nerve tolerance was measured in the presence of its body fluid. The body fluid reduced the effect of TTX on the nerves, while no effect was observed for STX. It is also confirmed that pre-injection of the body fluid of H. sanguineus into a mouse was effective to some extent in protecting the mouse from TTX attack. © 1992, The Japanese Society of Fisheries Science. All rights reserved.