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On November 16, 1998 a food poisoning incident due to ingestion of roe of Takifugu oblongus occurred in Bangladesh, affecting 8 people inclusive of 5 deaths. Their symptoms resembled those caused by tetrodotoxin (TTX) or paralytic shellfish poison (PSP). Immediately after the incident, twenty-two specimens of T. oblongus were collected from the seashore adjacent to the concerned poisoning area and their anatomical distribution of toxicity was determined. They showed a high level of toxicity in the ovary (24.5-323.8 MU/g), though the toxicity levels of the other tissues, skin, muscle, liver, testis, and the viscera (except liver), were relatively low (<2-21.3 MU/g). In contrast, a total of 336 specimens of three marine puffers, T. oblongus, Lagocephalus wheeleri and L. lunaris, which were collected on a regular sampling basis from Bangladesh, showed very low toxicity of less than 10 MU/g in all or most tissues including gonad. The toxin partially purified from the T. oblongus specimens, as well as from the other two species, was indistinguishable from TTX in HPLC analysis. From this result and the symptoms of the victims, the causative agent in the above incident was assumed to be TTX.

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The toxicity and toxic principle of the horseshoe crab Carcinoscorpius rotundicauda collected from Bangladesh during November to December, 1998 were examined. Although egg, testis and viscera were recognized to be toxic, their toxicity levels were comparatively low (under 10 MU/g; maximum of 7.4 MU/g in egg). The toxin was purified by ultrafiltration through a YM-1 membrane and two types of chromatography on Bio-Gel P-2 and Bio-Rex 70. The separated toxin was analyzed by HPLC, TLC, electrophoresis, and 1H-NMR, and identified as tetrodotoxin.This is the first report on the toxicity and toxic principle of the Bangladeshi horseshoe crab.

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Molluscs are the most important resources among all the seafood items in South-East Asian countries. However, very little information available on nutritional value of molluscs in these regions. In this study, we evaluated the 7 economically important species of molluscs in terms of proximate composition, amino acids profile, fatty acids profile, cholesterol and heavy metal contents in the bivalves (mussels, oysters, clams and cockles) and univalve (snail) collected from freshwater and marine environments of Bangladesh. The results of the proximate analyses revealed that significantly higher amount of crude protein contents were present in marine water oysters, clams and cockles (59.3 AE 0.3 to 75.4 AE 0.2%) than the freshwater mussels and snail (36.9 AE 0.4 to 49.6 AE 0.6%) on dry matter basis. However, carbohydrate contents were significantly higher in freshwater mussels and snail (30.2 AE 0.9 to 57.3 AE 0.2%) compared to the marine water bivalves (8.1 AE 0.4 to 20.2 AE 0.6%). Crude lipid contents were ranged from 2.5 AE 0.2 to 11.2 AE 0.1% and ash from 11.4 AE 0.1 to 16.8 AE 0.6% among the bivalves and snail species. The amino acid contents were comparatively higher in marine water bivalves than their freshwater counterparts. Saturated fatty acid contents were found to be higher in marine water bivalves than the freshwater mollusc species. The results also show that the omega-3 (eicosapentaenoic acid, EPA and docosahexaenoic acid, DHA) fatty acids were comparatively higher in oysters, clams and cockles in marine water than those in freshwater mussels and snail. However, omega-6 fatty acids like linoleic acid (LA), αlinolenic acid (ALA) and arachidonic acid (ARA) were higher in freshwater mussels and snail than in the marine bivalves. The n-3/n-6 ratio were significantly higher in oysters and cockle species than the other groups of bivalves and snail. The index of atherogenicity and index of thrombogenicity of the mollusc species ranged from 0.74 AE 0.1 to 1.74 AE 0.2 and 0.5 AE 0.1 to 2.6 AE 0.2, respectively. The results show that marine water bivalves contained higher amount of potassium, sodium, iron, chlorine especially oyster species contained significantly higher iodine than the freshwater bivalves and snail. However, freshwater mussels and snail showed significantly higher amount of zinc contents than the marine bivalves. The heavy metal contents such as arsenic, chromium and mercury were absent or present in very tiny amounts among the mollusc species. Significantly higher amount of cholesterol was present in marine bivalves and freshwater snail species than the freshwater mussels. Overall, the results indicate that marine bivalves can be good sources of high quality protein and lipid especially EPA and DHA. On the other hand, freshwater mussels and snails also could be good sources of protein, LA and ARA but scarcity of EPA and DHA.