Phytotoxicities of Selected Chemicals and Industrial Effluents to Nitellopsis obtusa Cells, Assessed by Using a Rapid Electrophysiological Charophyte Test

Abstract

The acute phytotoxicities of seven heavy metals (Cd2+, Cu2+, Hg2+, Ni2+, Zn2+, Cr6+ and Co2+), three phenolic compounds (phenol, 3,5-dichlorophenol and pentachlorophenol) and nine industrial effluents were appraised by using a rapid electrophysiological test with cells of the charophyte, Nitellopsis obtusa. The EC50 values (concentrations causing a 50% decrease in resting potential) obtained for reference chemicals were compared with those of five microbiotests (Polytox®, Microtox®, Selenastrum capricornutum growth inhibition, Daphnia magna immobilisation and Rotoxkit F™) taken from the scientific literature. The 45-minute charophyte test, the freshwater Algaltoxkit F™, Daphtoxkit F™ and Rotoxkit F™ were conducted simultaneously to assess the toxicities of effluents. The Toxkit microbiotests were typically two orders of magnitude more sensitive than the electrophysiological charophyte test to pure chemicals. The electrophysiological charophyte test was generally more sensitive than the Toxkit microbiotests to complex effluents. The rapid electrophysiological test, employing the 45-minute membrane depolarisation of N. obtusa cells as an endpoint, demonstrated similar sensitivity to heavy metals and phenolic compounds as the 20-minute bacterial Polytox® test, but less sensitivity than the 15-minute Microtox® test. Therefore, this rapid macroalgal test appears to be valuable as a sublethal toxicity screening tool for effluents.

Toxicity of copper oxide nanoparticle suspensions to aquatic biota

“…The data on the kinetics of cell transmembrane resting potential for all 32 cells were plotted on a graphic display for visual control and stored for further analysis. The details of the computer-assisted experimental setup have been published previously [13,26]. To ameliorate the physiological state of charophyte cells throughout the prolonged measurement of their bioelectrical activity (up to 30 h), the full content of the control medium, such as APW instead of APW T [13], was used.…”

Dissolved humic substances – ecological driving forces from the individual to the ecosystem level?

“…The giant cell of Nitellopsis obtusa (Desvaux) Groves and other charophytes has been shown to be a highly suitable model for studying the electrical characteristics and ion‐transport phenomena of plant membranes under normal as well as under stress conditions (Manusadžianas et al. , 1999, 2002).…”

“…The giant cell of Nitellopsis obtusa (Desvaux) Groves and other charophytes has been shown to be a highly suitable model for studying the electrical characteristics and ion-transport phenomena of plant membranes under normal as well as under stress conditions (Manusadžianas et al, 1999(Manusadžianas et al, , 2002. For the interaction of chemical stressors with living systems, the cell membrane is the very first sensing site, from which chemical or physical signals are redirected toward a target site through a multilevel network of cellular reactions.…”

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].…”