Cobalt oxide nanoparticles aggravate DNA damage and cell death in eggplant via mitochondrial swelling and NO signaling pathway

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 (APm) 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. CONCLUSION: 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.

MicroRNA in carcinogenesis & cancer diagnostics: A new paradigm.

MicroRNAs (miRNAs) are small 22-25 nucleotides long non-coding RNAs, that are conserved during evolution, and control gene expression in metazoan animals, plants, viruses, and bacteria primarily at post-transcriptional and transcriptional levels. MiRNAs ultimately regulate target gene expression by degrading the corresponding mRNA and/or inhibiting their translation. Currently, the critical functions of miRNAs have been established in regulating immune system, cell proliferation, differentiation and development, cancer and cell cycle by as yet unknown control mechanism. MiRNAs play an essential role in malignancy, and as tumour suppressors and oncogenes. Thus, discovery of new miRNAs will probably change the landscape of cancer genetics. Significantly different miRNA profiles can be assigned to various types of tumours, which could serve as phenotypic signatures for different cancers for their exploitation in cancer diagnostics, prognostics and therapeutics. If miRNA profiles can accurately predict malignancies, this technology could be exploited as a tool to surmount the diagnostic challenges. This review provides comprehensive and systematic information on miRNA biogenesis and their implications in human health.