Response to cobalt toxicity in lichen Pseudevernia furfuracea; uptake, photosynthetic quantum yield, membrane integrity and deoxyribonucleic acid fragmentation
Gürkan Yiğittürk1, Dilek Ünal-Özakça2, Türker Çavuşoğlu1,3, Kubilay Doğan Kılıç1, Yiğit Uyanıkgil1,3, Atakan Sukatar4
1Department of Histology and Embryology, Medical Faculty of Ege University, İzmir, Turkey
2Department of Molecular Biology and Genetics, Bilecik Seyh Edebali University, Faculty of Science and Art, Bilecik, Turkey
3Ege University, Cord blood, Cell-Tissue Research and Application Center, İzmir, Turkey
4Department of Biology, Ege University, Faculty of Applied Science, İzmir, Turkey
Keywords: Cobalt; deoxyribonucleic acid fragmentation; lichen; oxidative stress; Pseudevernia furfuracea; TUNEL.
Abstract
Objectives: This study aims to examine the toxic potential of Cobalt (Co) on photosystem II photosynthetic quantum yield, membrane integrity, and deoxyribonucleic acid (DNA) fragmentation formation.
Materials and methods: Oligonucleosomal DNA fragmentation was detected by terminal deoxynucleotidyl transferase-dUTP nick end labeling (TUNEL) assay. Lipid peroxidation was determined with malondialdehyde analyzing.
Results: The Fv/Fm ratio decreased in Pseudevernia furfuracea following exposure to various concentrations of Co (NO3)2 (5, 15 and 30 mM) for one, three and 24 hours. Co2+-treatment caused the accumulation of Co in lichen, induced severe oxidative stress by the generation of hydrogen peroxide, impaired the membrane integrity, and induced lipid peroxidation as measured by malondialdehyde. Samples treated with 15 mM and 30 mM of Co (NO3)2 had higher percentage of cell death than 5 mM-treated group.
Conclusion: To our knowledge, this is the first study detecting a high rate of DNA fragmentation in situ in phycobiont layer of Pseudevernia furfuracea; while it reveals that mycobiont layer has a lower rate of TUNEL-positive cells. It has been concluded that Co exposure results in impaired photosynthesis accompanied by oxidative stress and DNA fragmentation in Pseudevernia furfuracea; all these effects were concentration-dependent.