Recovery of MC-LR in fish liver tissue.
Cyanotoxins, particularly microcystins (MCs), have been shown to be a hazard to human health. MCs accumulate in aquatic organisms probably as a result of irreversible binding to liver protein phosphatases. The aim of this study was to describe the recovery of MC from fish liver using various detection methods, with MC-LR as the representative congener. These findings are discussed in conjunction with the current procedures and limit values used for human risk assessment. Following incubation of liver homogenates with various MC-LR concentrations, the homogenates were extracted by a water/methanol/butanol mixture via different treatments and subsequently analyzed via the colorimetric protein phosphatase inhibition assay (cPPA), HPLC, and anti-Adda ELISA. Detection via cPPA appeared to yield the highest recovery of MC-LR, although the presence of unspecific background may have resulted in overestimation of the true recovery. The recoveries determined via HPLC and anti-Adda ELISA were comparable to each other. The limits of detection were 0.01-2.4 microg MC-LR/g liver tissue, depending on the method used. Maximum MC-LR recovery from samples incubated with 10 and 100 microg MC-LR/g ranged between 44% and 101%. Recovery from samples incubated with 1 microg MC-LR/g liver tissue was below 3%. Lower recovery is assumed to result from irreversible, covalent MC protein binding, as confirmed by Western blotting of liver homogenates with anti-Adda immunoprobing. The results demonstrate that further investigation of and improvement in routinely applied MC methods for fish tissue and/or food analyses are needed for a reliable risk assessment.
Ernst
Bernhard
B
Environmental Toxicology, University of Konstanz, P.O. Box X-918, D-78457 Konstanz, Germany.
Dietz
Lisa
L
Hoeger
Stefan J
SJ
Dietrich
Daniel R
DR
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003124:Colorimetry; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D008099:Liver / Q000737:chemistry*; D008387:Marine Toxins; D052998:Microcystins; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000032:analysis*
D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C057862:cyanoginosin LR