Hong-Nong Chou

Accumulation and depuration of paralytic shellfish poisoning toxins by purple clam Hiatula rostrata Lighttoot.

Purple clams (Hiatula rostrata Lighttoot) accumulated paralytic shellfish poisoning (PSP) toxins produced by a toxic strain of the dinoflagellate Alexandrium minutum Halim for subsequent study of toxin distribution during depuration (detoxification by a nontoxic microalgal diet or starvation). The results confirm the data in the literature concerning the high toxicity of the digestive gland, and the depuration efficiency between feed with nontoxic microalgae and starvation is similar. The toxin profile of the purple clams was similar with that of Alexandrium minutum at the end of the exposure period; GTX4 and GTX1 were dominant. However, at the end of the depuration period, GTX3 and GTX2 were dominant. The non-visceral tissues were toxic after feeding with toxic algae. The toxicity was low and the profile were also similar with that of the toxic algae. No PSP toxins other than GTX-1, 2, 3 and 4 were detected in the experimental period.

Transmission of the paralytic shellfish poisoning toxins, from dinoflagellate to gastropod

Purple clams, Hiatula diphos Linnaeus, are filter-feeding bivalves and maculated ivory shells. Babylonia areolata Link are carnivorous gastropods. Both shellfishes are popular seafood delicacies among the Taiwanese. Hiatula diphos were forced to contain gonyautoxins (GTXs) in this research by feeding them with cells of Alexandrium minutum Halim, a toxic dinoflagellate species responsible for the paralytic shellfish poisonings in Taiwan. The intoxicated purple clams of known toxicity and toxin composition were fed to B. areolata to observe the transmission and transformation of GTXs among this shellfish. It was found that the toxin composition in bivalve and gastropod were similar to that in dinoflagellate. Our data provide evidence for food-chain transmission of paralytic shellfish poisoning toxins, from dinoflagellate to gastropod through a filter-feeding bivalve. The transmitted GTX-I. -II. -III and -IV of A. minutum could only be found in the viscera of these shellfish. There was a notable degradation of GTX-I in the ivory shell that resulted in a decrease in toxicity while the total amount of toxins was accumulatively increasing.

First report of microcystins in Taiwan

This is the first report on microcystins from Microcystis aeruginosa Kützing in Taiwan. A total of nine strains of cyanobacteria have been isolated from eutrophic aquaculture ponds and water reservoirs. By mouse toxicity assay, six of the nine strains had LD100 in the range of 25-100 mg per kg mouse for dried bacterial mass. Microcystin-LR and -RR were found in all toxic strains and their contents ranged from 0.11-10.06 microg and 0.08 2.21 microg per mg of dried bacteria, respectively. Microcystin-RA, a minor component found only in M. TN-2 and M. CY-1 strains, was identified as a new microcystin. All three toxins were isolated by a serial separation on an LH-20 column, Si-flash column chromatography and reverse phase HPLC. Toxins were further identified by comparing their FABMS, 1H and 1H-1H COSY NMR spectra with the authentic microcystin-LR. Several other microcystin-like compounds were also found in the cultured strains and their structures are being determined.

Uptake and transfer of high PCB concentrations from phytoplankton to aquatic biota

The uptake and transfer of 2,2′,4,4′-tetrachlorobiphenyl (an isomer of polychlorinated biphenyls, PCBs) in the culture of two species of phytoplankton, Nannochloropsis oculata and Isochrysis galbana, to brine shrimp (Artemia sp.) nauplii and hard shell clam (Meretrix lusoria) were investigated in a short-term laboratory ecosystem. Three PCB concentrations, 0 ppb, 50 ppb and 500 ppb, were prepared in the algal culture for examing the levels of PCB bioaccumulation and growth effects on these biota. Artemia and hard shell clam each when exposed to 500 ppb contaminated Nannochloropsis and Isochrysis for 4 d could significantly bioaccumulate PCB concentrations up to 318.81 ppm and 22.55 ppm (dry basis), respectively. This may account for the high PCB residues that bioaccumulated in contaminated Nannochloropsis (257.52 ppm) and Isochrysis (64.22 ppm) through the aquatic food chain. Biomass of PCB treated algae were apparently depressed (p < 0.05) relative to that of the control group (0 ppb). Growth conditions (length and larva/mL) of Artemia when fed with Nannochloropsis under PCB environments also showed stronger inhibition effects compared to that of the control group (p < 0.05).

Screening of Red Algae Filaments As a Potential Alternative Source of Eicosapentaenoic Acid

Abstract: Lipids were extracted by a supercritical fluid extraction method from 10 species of filamentous red algae obtained from culture collections and their fatty acid compositions were determined. The fatty acid profiles of the 10 species were similar. The major fatty acids were 16:0, 20:4ω6 and 20:5ω3 (eicosapentaenoic acid, EPA), which amounted to over 70% of the total fatty acids. The highest EPA content (29.8 mg/L), as a percentage of total fatty acids, was produced by Liagora boergesenii filaments, which has good potential for EPA mass production in pilot plants.

Isolation and Identification of Seven Microcystins from a Cultured M.TN-2 Strain of Microcystis Aeruginosa

Seven microcystins (MCYSTs), three major and four minor ones, were isolated from a cultured Microcystis aeruginosa strain M.TN-2 isolated from an eel pond in southern Taiwan in the summer of 1993. Microcystins were separated by a column separation of LH-20 gel filtration chromatography. a subsequent silica gel flash column chromatography, and then purified by a reversed phase high performance liquid chromatography. MCYST-LR, -RR, -RA, -FR, -WR, [D-Asp^3] MCYST-FR, and [D-Asp3] MCYST-WR were characterized and determined by amino acid analysis, MALDI-TOF mass spectrometry, (superscript 1)H and DQF-COSY nuclear magnetic resonance spectroscopy and UV spectroscopy. Among them, [D-Asp^3] MCYST-FR and [D-Asp^3] MCYST-WR, two new compounds, were the desmethyl variants of MCYST-FR and MCYST-WR, respectively.

A modified high-performance liquid chromatography method for analysis of PSP toxins in dinoflagellate, Alexandrium minutum, and shellfish from Taiwan

Paralytic shellfish poisoning (PSP) toxins are highly toxic natural compounds produced by dinoflagellates commonly present in marine phytoplankton. Shellfish accumulate PSP toxins during toxic algal blooms. PSP poses a significant public health threat and economic loss to the shellfish industry. For this reason, many methods have been developed to analyse PSP toxins in suspected toxic shellfish samples. In our study, we simplified the sample preparation method and set up a rapid and accurate high-performance liquid chromatography (HPLC) system to detect PSP toxins in algae and shellfish on a routine basis. The toxins profile of two strains of dinoflagellate Alexandrium minutum and shellfish samples collected from southwestern locations in Taiwan has been analysed with this HPLC method. Only A. minutum and purple clam Hiatula rostrata contained PSP toxins, with GTX-1, 2, 3, 4 being the major toxins.