β-1,3-glucan-binding Proteins From Plasma of the Fresh-water Crayfishes Astacus Astacus and Procambarus Clarkii

Abstract

ABSTRACT Two fresh-water crayfishes, Astacus astacus and Procambarus clarkii, and a marine crab, Carcinus maenas, were examined for the presence of β-1,3-glucan-binding proteins in their plasma. By the use of a monospecific rabbit polyclonal antiserum to the β-1,3-glucan-binding protein of Pacifastacus leniusculus, 2 proteins from the plasma of Astacus astacus with molecular masses of about 105 kDa and 95 kDa as well as a 100-kDa protein in the plasma of Procambarus clarkii could be detected. No protein in plasma of Carcinus maenas cross-reacted with the anti-Pacifastacus leniusculus β-1,3-glucan-binding protein antibodies. The cross-reactive proteins from plasma of Astacus astacus were purified by immuno-affinity chromatography. The isolated proteins were homogenous as judged by electrophoresis on SDS-PAGE. Isoelectric focusing of the purified proteins gave pIs of about 6.1 and 6.4. The purified proteins from the plasma of Astacus astacus enhanced the activity of a hemocyte lysate supernatant-derived phenoloxidase of Pacifastacus leniusculus as did the β-1,3-glucanbinding protein of Pacifastacus leniusculus.