UMB 7: Characterization of The Toxicity of UV and Gamma Radiation to Lemna Minor
K.E. Tollefsen (NIVA/NMBU-IMV), L. Xie (NIVA), A.C. Almeida (NIVA), T. Gomes (NIVA), H.C. Teien (IMV-NMBU), K.A. Solhaug (INA-NMBU), B. Johnsen (NRPA).
Background: UV and gamma radiation may cause direct cellular damage by breakage of DNA strands and induction of oxidative stress in aquatic organisms. However, the exact molecular mechanisms causing toxicity have still not been thoroughly characterized and the effects of combined exposures to the two stressors are largely unknown.
Objectives: Assess the toxicity of ultraviolet radiation (UV) and a combination of UV and gamma radiation in the aquatic plant Lemna minor by characterizing the stress responses and adverse effects.
Methods: Exposure studies with Lemna minor will be conducted with UVB (0.37 W/m2) alone and in combination with gamma radiation (10, 20 and 40 µGy/h) to characterize effects on growth, photosynthesis, production of reactive oxygen species (ROS), lipid peroxidation (LPO), frond pigmentation, uncoupling of oxidative phosphorylation (OXPHOS), frond malformations and DNA damage. Global transcriptional analysis will be considered used on basis of data generated.
Results: both UVB and gamma caused a dose-dependent increase in apical effects (growth), photosynthesis, pigments, ROS, and OXPHOS when exposed alone. The majority of these effects were reveresed after 7 days recovery. Combined studies with the two stresors showed endpoint-specific effect enhancement and antagonism. Most of these effects were reversed after 7 days recovery.
Project Manager: Knut Erik Tollefsen
(Photos: L. Xie, NIVA)