title: Potential of fluorescence imaging techniques to monitor mutagenic PAH uptake by microalga.
abstract: Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH), is one of the major environmental pollutants that causes mutagenesis and cancer. BaP has been shown to accumulate in phytoplankton and zooplankton. We have studied the localization and aggregation of BaP in Chlorella sp., a microalga that is one of the primary producers in the food chain, using fluorescence confocal microscopy and fluorescence lifetime imaging microscopy with the phasor approach to characterize the location and the aggregation of BaP in the cell. Our results show that BaP accumulates in the lipid bodies of Chlorella sp. and that there is Förster resonance energy transfer between BaP and photosystems of Chlorella sp., indicating the close proximity of the two molecular systems. The lifetime of BaP fluorescence was measured to be 14 ns in N,N-dimethylformamide, an average of 7 ns in Bold's basal medium, and 8 ns in Chlorella cells. Number and brightness analysis suggests that BaP does not aggregate inside Chlorella sp. (average brightness = 5.330), while it aggregates in the supernatant. In Chlorella grown in sediments spiked with BaP, in 12 h the BaP uptake could be visualized using fluorescence microscopy.
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, University of South Australia and CRC CARE , Mawson Lakes, Adelaide, South Australia 5095, Australia.
authors.forename: Suresh Ramraj
authors.initials: SR
authors.lastname: Subashchandrabose
authors.forename: Kannan
authors.initials: K
authors.lastname: Krishnan
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
authors.forename: Mallavarapu
authors.initials: M
authors.lastname: Megharaj
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
mesh_terms: D001564:Benzo(a)pyrene / Q000378:metabolism*; D002708:Chlorella / Q000378:metabolism*; D004126:Dimethylformamide / Q000737:chemistry; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer; D058086:Microalgae / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009153:Mutagens / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D009153:Mutagens; D014874:Water Pollutants, Chemical; D001564:Benzo(a)pyrene; D004126:Dimethylformamide