Effect of prolonged captivity on the hemolymph profile of Tachypleus gigas

Abstract

Horseshoe crabs amebocyte cells degranulate to form a gel clot when in contact with endotoxins. This phenomenon is the basis of both Horseshoe crab immune system and detection of endotoxin in biologicals. The present study investigates the amebocyte cells quality in Tachypleus gigas pre and post bleeding under captivity. Wild and captive horseshoe crabs (5 months captivity) were bled in 6 anticoagulant formulations (A, B, C, D, E and F). No profound difference in cell density between captive and wild groups with the mean value of 0.883x107 a cells/mL and 0.917x107 cells/mL, respectively. while, the cell viability of the captive group was significantly lower than the wild crabs (F=808.075, p<0.001). Anticoagulant formulation significantly affected cell viability and cell morphology in both captive and wild groups (p<0.001). Amebocyte cells collected from the wild T. gigas using optimum anticoagulant (formula C) showed 0.6 x107 cells/mL cell density and 86.9% cell viability, while morphology analysis revealed the percentage of contracted, granular flattened and degranulated flattened cells were 14.62%, 71.39% and 14%, respectively. The anticoagulant formulations showed varying capabilities in maintaining cell viability due to its buffering and chelating capacity. We conclude that captivity has a negative effect on the amebocyte cell quality. HIGHLIGHTSO_LICaptivity has a negative impact on amebocyte quality in horseshoe crab (Tachypleus gigas). C_LIO_LINo significant difference in cell density between captive and wild crabs. C_LIO_LIAnticoagulant formulations have significant impact on the cell density, viability and morphology C_LIO_LICaptive crabs were immunocompromised due to single specific feed intake. C_LI