Wastewater toxicity assessment using the electrophysiological response of a charophyte Nitellopsis obtusa

Abstract

A biotesting method for the assessment of acute sublethal toxicity to charophyte cells of Nitellopsis obtusa was developed and applied for the study of Vilnius and Visaginas wastewaters (WW). This computer-assisted testing procedure was based on the recording of the electrophysiological response of up to 16 single algal cells simultaneously. Membrane parameters of living cells were measured according to the K+-anaesthesia method modified for multichannel recording with extracellular electrodes. Concentration-dependent monotonical decrease of cell resting potential, induced by toxic WW action, was used to determine an effective concentration (EC) values. A multistep time-saving procedure, when the cell group was exposed to subsequent treatment with increasing WW concentrations (30 min per treatment), proved to be adequate for biotesting. The ECs obtained by this procedure were in good agreement with those obtained alternatively by undertaking onestep testing (i.e., 60 min exposure per concentration per cell group). The relative sensitivity of the cellular electrophysiological response, as a toxicity end point, was confirmed by comparing it with lethal concentration (LC) responses in 96-and 192-h exposure tests conducted on the same N. obtusa cells. For Vilnius WW samples taken on different dates, the EC5, s ranged from 27 to 46% WW and corresponded to 96-h LC5, s of 28-50% WW. In contrast, Visaginas WWs sampled before and after chlorination showed no toxic effect either at the membrane or whole cell level. 0 7995 by John Wiley & Sons, Inc.of the food web and contributors of oxygen in the aquatic ecosystem, are scarcely employed in biotesting. It is clear, however, that some species of charophytes, for example, could certainly satisfy the requirements characterizing microbiotesting (Blake, 1991).Stoneworts are widely distributed, abundantly grow in the ground plantations of clean fresh or brackish waters (Minkevieius and Trainauskaite, 1957), and are sensitive to pollution. The giant charophyte cell separated from talloma and kept in artificial pond water can be considered to be a single organism that maintains

Investigations of Toxic and Genotoxic Effects of Heavy Metals and their Model Mixture on Plants

“…Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. (Schubert, 1988;Kandeler, 1987;Wang, 1990Wang, , 1991Manusadþianas et al, 1995;Marèiulionienë et al, 1996) (Lakatos et al, 1993;Makadi et al, 1995). American scientists presented a comparison of toxic effect of heavy metals on duckweed and on fish (Table 1; Wang, 1991).…”

Modifying action of tritium on the charophytes bioelectrical response to anthropogenic pollution

“…Therefore these cells are intensively used for electrophysiology studies and environmental monitoring. The rapid depolarization of membane potential (E,^) proved to be a relevant endpoint to assess contaminants toxicity and tight correlation between the electrophysiological response and the cell lethality induced Stressors [10]. Moreover, for Nitellopsis obtusa is typical to generate AP in response to the exogenous stimulation, injury etc., thus it is a suitable model system for study of possible effects of different contaminants on the membrane transport systems activity [11].…”

Microbiological degradation of a spent offset-printing developer

“…The details of the computer-assisted experimental setup, testing procedures for range finding and EC 50 -determining tests and the methods for measurement of cell transmembrane resting potential (RP) have been published previously [15,16]. Briefly, bioelectrical activity of up to 32 living internodal cells was measured simultaneously according to K-anaesthesia method [17], modified for multichannel recording with extra cellular chlorinated silver wire electrodes [15]. Two independent tests were performed at the same time, by dividing 32 cells into two groups.…”