Influence of zwitterionic pH buffers on the bioavailability and toxicity of copper to the alga Amphidinium carterae

• Type: Article in International Scientific Journal
• Date: 2000

Authors

teresa, m (Author) Other; vasconcelos, sd (Author) Other; almeida, cmr (Author) Other; lage, om (Author) Other; sansonetty, f (Author) Other

Journal

Title: Environmental Toxicology and Chemistry

Vol. 19

Pages: 2542-2550

ISSN: 0730-7268

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 7 Citations

Scopus - 9 Citations

Scientific classification

FOS: Natural sciences > Earth and related Environmental sciences

Other information

Authenticus ID: P-000-YTF

Abstract (EN): The culture and testing of algae frequently requires stabilization of pH levels to maintain the availability of trace metals. In this work we evaluated the influence of 25 x 10(-3) M N-[2-hydroxyethyl]piperazine-N'-[2-hydroxypropanesulfonic acid] (HEPPSO) and piperazine-N,N'-bis[2-hydroxypropanesulfonic acid] (POPSO) pH buffers, at pH 8.0, on the biological response of Amphidinium carterae Hulburt. Growth rate, copper uptake, mean cell size, mean cell complexity. and fluorescein labeling: of algae cultures were studied in enriched solutions of artificial seawater (ESAWs) containing a range of total copper(II) concentrations between 23 x 10(-9) M (level before copper addition) and 15 x 10(-6) M. The ESAW (without a pH buffer, initial pH = 8.0) was used as the control medium. Initial free copper (Cu-free) was between 53 x 10(-15) and 72 x 10(-10) M, which represents ranges of concentrations typical of unimpacted and polluted surface seawater. These ranges were achieved using ehtylenediaminetetraacetic acid (EDTA) alone and in combination with the two buffers. Biological data endpoints were interpreted based on the cellular copper (Cu-cellular, in fmol/cell) and on the estimated initial inorganic copper (Cu-inorg = Cu-free plus that bound with inorganic ligands) in the medium. At innocuous Cu-morg, up to 10 x 10(-9) M (Cu-free less than or equal to 4 x 10(-11) M), the Cu-cellular was independent of the presence of the buffer and very little dependent of Cu-inorg. For Cu-inorg up to 0.40 x 10(-9) M, the Cu-cellular was approximately constant (0.1-0.2 fmol/cell) and when Cu-inorg ranged between 1.1 x 10(-9) M and 10 x 10(-9) M the Cu-cellular was three rimes higher but also constant. The POPSO enhanced copper uptake and toxicity. The HEPPSO reduced uptake and toxicity of copper because of its enhanced binding capacity compared to POPSO. Both HEPPSO and POPSO altered copper effects on mean cell size, mean cell complexity and fluorescein labeling of A. carterae, but the inherent mechanisms differed between the two buffers. This present work demonstrated that the chemical binding affinity of HEPPSO and POPSO differed and that it resulted in altered uptake and effects of copper on algae. These observations have important implications in culture and testing of algae that require metals as micronutrients yet are sensitive to metals at concentrations that exceed basic metabolic needs.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9