Intraspecific differences in cadmium tolerance of Nitzschia palea (Kützing) W. Smith: a biochemical approach.
Intraspecific variability occurs in all types of organisms and is a driving force to speciation, conferring genotypic and phenotypic differences that enable adaptive responses to sub-lethal stimuli such as exposure to pollutants (including cadmium, Cd). Thus, differences in biochemical parameters are expected among isolates of the same species. Studying the extent of these differences throughout a stress range, will provide information for the development of approaches to mitigate habitat contamination. This work was designed to identify possible differences in Cd tolerance of five isolates of the freshwater diatom Nitzschia palea from different sampling sites. Each isolate was exposed to five increasing Cd concentrations during 10 days. Growth inhibition was assessed and intracellular accumulation of Cd was quantified. Superoxide dismutase and catalase activities were determined. Glutathione as well as lipid peroxidation (LPO) and intracellular protein content were quantified. The results obtained identified intraspecific differences among isolates. These differences were associated with different approaches of coping with Cd stress. Higher intracellular Cd concentrations induced lower tolerance in isolates, since antioxidant mechanisms were unable to fight effectively against higher oxidative stress. Reversely, lower intracellular accumulation of Cd induced lower oxidative damage and allowed cells to better tolerate exposure to Cd. LPO emerged as an excellent marker of oxidative stress in N. palea and its use can differentiate isolates according to their tolerance.
Department of Biology and CESAM, Centre for Environment and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.|Department of Biology and GeoBioTec - GeoBioSciences, GeoTechnologies and GeoEngineering Research Centre, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
José
J
Santos
Department of Biology and GeoBioTec - GeoBioSciences, GeoTechnologies and GeoEngineering Research Centre, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
Salomé F P
SF
Almeida
Department of Biology and CESAM, Centre for Environment and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
Rosa
R
Freitas
Department of Biology and CESAM, Centre for Environment and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
Cátia
C
Velez
Department of Biology and CESAM, Centre for Environment and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.|Department of Biology and GeoBioTec - GeoBioSciences, GeoTechnologies and GeoEngineering Research Centre, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
Sara
S
Esteves
Department of Biology and CESAM, Centre for Environment and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal. efigueira@ua.pt.
Etelvina
E
Figueira
D000222:Adaptation, Physiological; D015415:Biomarkers / Q000378:metabolism; D002104:Cadmium / Q000633:toxicity*; D017377:Diatoms / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D015415:Biomarkers; D014874:Water Pollutants, Chemical; D002104:Cadmium; D013482:Superoxide Dismutase; D005978:Glutathione
Diatoms; Growth inhibition; Intraspecific variation; Oxidative stress