IN-VIVO ESTERASE-ACTIVITY IN PROTOPLASTS AS A BIOASSAY OF ENVIRONMENTAL-QUALITY

In this study, protoplasts of Posidonia oceanica (Linnaeus) Delile, Ulva rotundata Bliding and Ulva rigida C. Agardh were isolated for the first time. For Ulva spp., production yields ranged from 2 x 10(6) to 10(7) g-1 according to the species and the isolation procedure used. Concentrations of 1 mg l-1 N-NO3, 0.25 mg l-1 P-PO4 and 20 muM fluorescein diacetate as substrate were found to be optimum conditions for measuring in vivo the esterase activity of protoplasts. Various chemical compounds and effluents were tested to determine the optimum water sample process, range of incubation times, level of response, and sensitivity for a new ecotoxicological test. Inhibition concentration IC50 was found to vary from 0.6 mg l-1 (for Dichlorvos) to values above 100 mg l-1 (for TBT). This bioassay was used to determine the quality of seawater samples from various stations along the French Mediterranean coast. Significant differences in activity were measured with a ratio of 8 between six sites, indicating the existence of a dilution gradient for waste waters from the drainage canal flowing into Cortiou Inlet. This allowed the evaluation of contamination differences at four stations around Toulon harbor. These measurements also provide a new approach to understanding the molecular adaptation of macrophytes in a disturbed environment.