title: Functional toxicity and tolerance patterns of bioavailable Pd(II), Pt(II), and Rh(III) on suspended Saccharomyces cerevisiae cells assayed in tandem by a respirometric biosensor.
abstract: Toxicological implications of exposure to bioavailable platinum group metals, here Pd, Pt, and Rh, are still to be clarified. This study obtained by a biosensor-based method preliminary information on potential effects on cellular metabolism as well as on possible tolerance mechanisms. Aerobic respiration was taken as the toxicological end point to perform tandem tests, namely functional toxicity test and tolerance test. Cells were suspended in the absence of essential constituents for growth. The dose-response curves obtained by exposure (2 h) to the metals (nanogram per gram range) suggested the same mechanisms of action, with Rh showing the greatest curve steepness and the lowest EC50 value. Conservative (95% lower confidence interval) EC10 values were 187, 85 and 51 ng g(-1) for Pt, Pd, and Rh respectively. Tolerance patterns were tested during the same runs. The full tolerance obtained after 12 h of exposure to each metal suggested mitochondrial inhibition of aerobic respiration as a target effect. The hazard rating of the metals in the tolerance test changed in the Rh EC50 range, where Rh showed the lowest toxicity. The observed tolerance might suggest a protective mechanism such as metallothionein induction at concentrations around the EC50 values. The performance of the bioassay was satisfactory, in terms of the limit of detection, repeatability, reproducibility, roboustness, sensibility, and stability; the method's critical uncertainty sources were identified for improvements.
authors.affiliation: Department of Food Safety and Veterinary Public Health and WHO/FAO Collaborating Centre for Veterinary Public Health, Istituto Superiore di Sanità, V.le Regina Elena 299, 00161, Rome, Italy. chiara.frazzoli@iss.it
authors.forename: Chiara
authors.initials: C
authors.lastname: Frazzoli
authors.forename: Roberto
authors.initials: R
authors.lastname: Dragone
authors.forename: Alberto
authors.initials: A
authors.lastname: Mantovani
authors.forename: Cristiana
authors.initials: C
authors.lastname: Massimi
authors.forename: Luigi
authors.initials: L
authors.lastname: Campanella
mesh_terms: D001682:Biological Availability; D015374:Biosensing Techniques / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D010165:Palladium / Q000633:toxicity*; D010984:Platinum / Q000633:toxicity*; D012238:Rhodium / Q000633:toxicity*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000378:metabolism
chemical_list: D010984:Platinum; D010165:Palladium; D012238:Rhodium