title: Cobalt oxide nanoparticles aggravate DNA damage and cell death in eggplant via mitochondrial swelling and NO signaling pathway.
abstract: BACKGROUND
  Despite manifold benefits of nanoparticles (NPs), less information on the risks of NPs to human health and environment has been studied. Cobalt oxide nanoparticles (Co3O4-NPs) have been reported to cause toxicity in several organisms. In this study, we have investigated the role of Co3O4-NPs in inducing phytotoxicity, cellular DNA damage and apoptosis in eggplant (Solanum melongena L. cv. Violetta lunga 2). To the best of our knowledge, this is the first report on Co3O4-NPs showing phytotoxicity in eggplant.
  
  
  RESULTS
  The data revealed that eggplant seeds treated with Co3O4-NPs for 2 h at a concentration of 1.0 mg/ml retarded root length by 81.5 % upon 7 days incubation in a moist chamber. Ultrastructural analysis by transmission electron microscopy (TEM) demonstrated the uptake and translocation of Co3O4-NPs into the cytoplasm. Intracellular presence of Co3O4-NPs triggered subcellular changes such as degeneration of mitochondrial cristae, abundance of peroxisomes and excessive vacuolization. Flow cytometric analysis of Co3O4-NPs (1.0 mg/ml) treated root protoplasts revealed 157, 282 and 178 % increase in reactive oxygen species (ROS), membrane potential (ΔΨm) and nitric oxide (NO), respectively. Besides, the esterase activity in treated protoplasts was also found compromised. About 2.4-fold greater level of DNA damage, as compared to untreated control was observed in Comet assay, and 73.2 % of Co3O4-NPs treated cells appeared apoptotic in flow cytometry based cell cycle analysis.
  
  
  CONCLUSIONS
  This study demonstrate the phytotoxic potential of Co3O4-NPs in terms of reduction in seed germination, root growth, greater level of DNA and mitochondrial damage, oxidative stress and cell death in eggplant. The data generated from this study will provide a strong background to draw attention on Co3O4-NPs environmental hazards to vegetable crops.
authors.affiliation: Department of Botany and Microbiology, College of Sciences, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia. faisalm15@yahoo.com.
authors.forename: Mohammad
authors.identifier: http://orcid.org/0000-0002-8176-1527
authors.initials: M
authors.lastname: Faisal
authors.affiliation: A.R. Al-Jeraisy Chair for DNA Research, Zoology Department, College of Sciences, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.|Zoology Department, College of Sciences, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia.
authors.forename: Quaiser
authors.initials: Q
authors.lastname: Saquib
authors.affiliation: Department of Botany and Microbiology, College of Sciences, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia.
authors.forename: Abdulrahman A
authors.initials: AA
authors.lastname: Alatar
authors.affiliation: A.R. Al-Jeraisy Chair for DNA Research, Zoology Department, College of Sciences, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.|Zoology Department, College of Sciences, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia.
authors.forename: Abdulaziz A
authors.initials: AA
authors.lastname: Al-Khedhairy
authors.affiliation: Zoology Department, College of Sciences, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia.
authors.forename: Mukhtar
authors.initials: M
authors.lastname: Ahmed
authors.affiliation: Department of Botany and Microbiology, College of Sciences, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia.
authors.forename: Sabiha M
authors.initials: SM
authors.lastname: Ansari
authors.affiliation: Department of Botany and Microbiology, College of Sciences, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia.
authors.forename: Hend A
authors.initials: HA
authors.lastname: Alwathnani
authors.affiliation: Department of Agricultural Microbiology, Faculty of Agricultural Sciences, AMU, Aligarh, 202002, India.
authors.forename: Sourabh
authors.initials: S
authors.lastname: Dwivedi
authors.affiliation: Department of Agricultural Microbiology, Faculty of Agricultural Sciences, AMU, Aligarh, 202002, India.|Department of Biosciences and Biotechnology, Baba Ghulam Shah Badshah University, Rajouri, 185131, Jammu and Kashmir, India.
authors.forename: Javed
authors.initials: J
authors.lastname: Musarrat
authors.affiliation: Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, 110012, India.
authors.forename: Shelly
authors.initials: S
authors.lastname: Praveen
mesh_terms: D000704:Analysis of Variance; D016923:Cell Death / Q000187:drug effects*; D003035:Cobalt / Q000378:metabolism / Q000633:toxicity*; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D005434:Flow Cytometry; D046529:Microscopy, Electron, Transmission; D008933:Mitochondrial Swelling / Q000187:drug effects* / Q000502:physiology; D053758:Nanoparticles / Q000378:metabolism / Q000633:toxicity*; D009569:Nitric Oxide / Q000378:metabolism*; D010087:Oxides / Q000378:metabolism / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D032323:Solanum melongena / Q000187:drug effects* / Q000378:metabolism
chemical_list: D010087:Oxides; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D003035:Cobalt; C060728:cobalt oxide
keywords: Apoptosis; Cobalt oxide nanoparticles; DNA damage; Nanotoxicity; Oxidative stress