Elsevier

Toxicon

Volume 49, Issue 6, May 2007, Pages 843-847
Toxicon

Toxicity assessment for the horseshoe crab Carcinoscorpius rotundicauda collected from Cambodia

https://doi.org/10.1016/j.toxicon.2006.12.004Get rights and content

Abstract

In this study, we assessed the toxicity of the horseshoe crab Carcinoscorpius rotundicauda collected from Cambodia within two successive months during rainy (April–May) and dry (December–January) seasons, respectively. Toxicity assessments of the collected specimens by standard mouse bioassay showed marked individual variation, and their toxin profiles by liquid chromatography/mass spectrometry (LC/MS) revealed tetrodotoxin (TTX) was the main toxin while no paralytic shellfish toxins (PSTs) were detected. All specimens were toxic and the highest toxicity values were 315, 113, 60, 47, 44 and 38 mouse units (MU)/g in the tissues of hepatic caecum, egg, viscera, muscle, intestine and testis, respectively. Although the current findings showed that the Cambodian C. rotundicauda was a moderately toxic species, they are not suitable for human consumption due to their toxicity. To the best of our knowledge, this is the first scientific study on toxic marine seafood ever investigated in Cambodian territorial waters.

Introduction

The puffer toxin, tetrodotoxin (TTX), has been continuously found in a wide range of organisms from both terrestrial and marine habitats (Miyazawa and Noguchi, 2001). The horseshoe crab Carcinoscorpius rotundicauda is one of such TTX-bearers, and Thai and Bangladeshi specimens of this species have so far been reported as toxic (Kungsuwan et al., 1987; Kanchanapongkul and Krittayapoositpot, 1995; Tanu and Noguchi, 1999) (Fig. 1). In the present study, we investigated the toxicity and toxin composition of C. rotundicauda specimens collected from Cambodia, in order to clarify the regional variation of toxicity or toxin profile in this species. In Cambodia, several anecdotes regarding the poisoning incidences caused by the ingestion of horseshoe crabs have been circulated in the fisherman community, but evidence or scientific records were not available yet. This study will also provide useful information for the Cambodian health authority and general public to prevent such food poisonings from occurring again in the future.

Section snippets

Specimen collection

Horseshoe crabs were collected along the seashore of Sihanouk Ville, Cambodia (Fig. 1) within two successive months during rainy (April–May 2005) and dry (December 2005–January 2006) seasons. The specimens were frozen immediately and transported to our laboratory by air inside insulation box prior to identification and toxicity analyzes.

Mouse bioassay

After thawing, the specimens were dissected into different anatomical tissues, and then each tissue was bioassayed according to the official guidelines of the

Results

All the horseshoe crab specimens collected were identified as C. rotundicauda, which is a common species in Southeast Asian waters. Anatomical distribution of toxicity of all the specimens collected in this study is summarized in Table 1. The frequencies of toxic samples were 100%, and their toxicities showed marked individual variation, ranging from 2 to 315 MU/g. No apparent sexual, anatomical and seasonal variations in toxicities were observed among the collected crabs in this study, except

Discussion

The results showed that the Cambodian horseshoe crab C. rotundicauda was toxic both in the dry and rainy seasons. The maximal toxicity of eggs (usual edible tissue; 113 MU/g) was much higher than those reported for the Thai and Bangladeshi specimens (16 and 7.4 MU/g, respectively) (Kungsuwan et al., 1987; Tanu and Noguchi, 1999).

The main toxic principle was identified as TTX, accounting for about 90% of the total toxicity. No PSTs were detected in the present study, but several unidentified peaks

Acknowledgments

The authors would like to express sincere thanks to Assistant Professor Samsur Mohamad, Faculty of Resource Science and Technology, University Malaysia Sarawak, for his useful suggestion. This work was partly supported by a grant-in-aid from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

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