PARENT SESSION
4K Cyanobacterial toxins: health and environmental hazards
9:00 AM to 7:00 PM, Wednesday, 09 May 2001

(W/EH106) In vivo and in vitro effects of microcystins on several biomarkers of Brachydanio rerio.

Fernandes, Elisabete^1,2, Vasconcelos, Vitor², Guilhermino, Lúcia^1,3, ^{1 2 3}

ABSTRACT- The freshwater cynobacterium Microcystis aeruginosa, strain IZANCYA 3, produces mainly the hepatotoxin microcystin-LR. The toxicity of this cyclic heptapeptide is caused by the amino acid "ADDA". Microcystins are responsible for the inhibition of protein phosphatases 1 and 2A. The aim of this work was to investigate both in vitro and in vivo effects of microcystins on the activity of the enzymes acetylcolinesterase (AChE), glutathione S-transferase (GST), lactate dehydrogenase (LDH) and protein phosphatase serine/treonine. In vivo experiments were conducted with the fish Brachydanio rerio, at concentrations ranging from 15.25 g/l to 100 g/l of MCYST-LR. In vitro experiments were done with six concentrations from 60 g/l to 1920 g/l of MCYST-LR. In vivo exposure to M. aeruginosa toxin induced alterations in all the biomarkers studied. In vitro incubation of B. rerio homogenates with M. aeruginosa seems to affect AChE activity although no effects were observed on LDH and GST activities.

Key words: Cyanobacterium, Microcystin-LR, Brachydanio rerio, Enzymatic biomarkers