Nickel uptake and release in nickel-resistant and - sensitive strains of Scenedesmus Acutus F. Alternans (Chlorophyceae)

Autor: Xiaolei Jin, Czeslawa Nalewajko, Donn J. Kushner
Rok vydání: 1996
Předmět:
Zdroj: Environmental and Experimental Botany. 36:401-411
ISSN: 0098-8472
DOI: 10.1016/s0098-8472(96)01030-1
Popis: Intracellular uptake and extracellular adsorption of Ni2+ were compared in three Niresistant (B4, Cu-Tol, and Ni-Tol) and one Ni-sensitive (UTEX 72) strains of Scenedesmus acutus f. alternans, to assess the role of these processes in Ni-resistance. Intracellular uptake was highest in the most sensitive strain (UTEX 72) during a 24 h exposure to 50 fmol Ni2+ per cell (equivalent to 50 μM). However, B4 could grow longer and accumulated substantially more Ni2+ than UTEX 72 after a 3 days exposure period, suggesting that B4 is a Ni-accumulator. Ni2+ transport rate in Cu-Tol and Ni-Tol was only about 1 3 that in UTEX 72, indicating that Ni-Tol and Cu-Tol exclude Ni2+. A positive linear relationship was found between intracellular uptake and extracellular adsorption and Ni2+ dosage in all four strains in the range of 2–500 fmol Ni2+ per cell. Although extracellular adsorption as percentage of total uptake was lowest in UTEX 72 in most cases studied, all four strains bound substantial amounts of Ni2+ to their cell surface, suggesting that extracellular binding contributes only slightly to Ni-resistance in these strains. That low temperature and darkness strongly inhibited but did not abolish Ni2+ uptake in all four strains suggests that active transport was the major means of Ni2+ uptake, but that passive Ni2+ transport also existed. All four strains released more Ni2+ in dark than under light after 28 h of resuspension in Ni-free medium, suggesting that Ni2+ release is a passive process which is counteracted by active Ni2+ uptake in the light. Ni-resistance in these strains can not be attributed to active Ni2+ release.
Databáze: OpenAIRE
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