Evaluation of Erythrocyte 5-Aminolevulinic Acid Dehydratase Activity in the Blood of Crucian Carp, Curassius

The activity of 5-aminolevulinic acid dehydratase (ALA-D) in the blood of crucian carp, Carassius auratus langsdorfiii, was measured under a variety of lead exposure conditions. A three-week exposure of crucian carp to water lead concentrations of 3, 10, and 30 ppb inhibited their ALA-D activities with increasing water lead concentrations. When crucian carp were exposed to a water lead concentration of 30 ppb, depressed activity of ALA-D became visible after two days, and this activity became even more depressed with increasing exposure periods. The ALA-D activity of crucian carp after the fish were transferred from a water lead concentration of 100 ppb (two weeks of exposure) to lead-free water recovered to only 40% of the value seen in the fish at the beginning of the exposure test, even after four weeks. Therefore, these characteristics concerning ALA-D in crucian carp blood indicate that this enzyme is useful as an indicator of lead pollution in fresh water.