Papers by Mohammed Zeeshan
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2016
Copper, an essential microelement, is known to be toxic to aquatic life at concentrations higher ... more Copper, an essential microelement, is known to be toxic to aquatic life at concentrations higher than that could be 18 tolerated. Copper-induced oxidative stress has been documented in vitro, yet the in vivo effects of metal-induced 19 oxidative stress have not been extensively studied in the lower invertebrates. The objective of the present study 20 has been to find the effect of ROS-mediated toxicity of environmentally relevant concentrations of copper at or-21 ganismal and cellular levels in Hydra magnipapillata. Exposure to copper at sublethal concentrations (0.06 and 22 0.1 mg/L) for 24 or 48 h resulted in generation of significant levels of intracellular reactive oxygen species 23 (ROS). We infer that the free radicals here originate predominantly at the lysosomes but partly at the mitochon-24 dria also as visualized by H 2-DHCFDA staining. Quantitative real-time PCR of RNA extracted from copper-exposed 25 polyps revealed dose-dependent up-regulation of all antioxidant response genes (CAT, SOD, GPx, GST, GR, G6PD). 26 Concurrent increase of Hsp70 and FoxO genes suggests the ability of polyps to respond to stress, which at 48 h 27 was not the same as at 24 h. Interestingly, the transcript levels of all genes were down-regulated at 48 h as com-28 pared to 24 h incubation period. Comet assay indicated copper as a powerful genotoxicant, and the DNA damage 29 was dose-as well as duration-dependent. Western blotting of proteins (Bax, Bcl-2 and caspase-3) confirmed 30 ROS-mediated mitochondrial cell death in copper-exposed animals. These changes correlated well with changes 31 in morphology, regeneration and aspects of reproduction. Taken together, the results indicate increased produc-32 tion of intracellular ROS in Hydra on copper exposure.
Scientific Reports, 2016
Nanotechnology has emerged as a powerful field of applied research. However, the potential toxici... more Nanotechnology has emerged as a powerful field of applied research. However, the potential toxicity of nano-materials is a cause of concern. A thorough toxicological investigation is required before a nanomaterial is evaluated for application of any kind. In this context, there is concerted effort to find appropriate test systems to assess the toxicity of nanomaterials. Toxicity of a nanomaterial greatly depends on its physicochemical properties and the biological system with which it interacts. The present research was carried out with a view to generate data on eco-toxicological impacts of copper oxide nanorod (CuO NR) in Hydra magnipapillata 105 at organismal, cellular and molecular levels. Exposure of hydra to CuO NR resulted in severe morphological alterations in a concentration- as well as duration-dependent manner. Impairment of feeding, population growth, and regeneration was also observed. In vivo and in vitro analyses revealed induction of oxidative stress, genotoxicity, a...
Environmental pollution (Barking, Essex : 1987), 2017
The mechanisms underlying cobalt toxicity in aquatic species in general and cnidarians in particu... more The mechanisms underlying cobalt toxicity in aquatic species in general and cnidarians in particular remain poorly understood. Herein we investigated cobalt toxicity in a Hydra model from morphological, histological, developmental, and molecular biological perspectives. Hydra, exposed to cobalt (0-60 mg/L), were altered in morphology, histology, and regeneration. Exposure to standardized sublethal doses of cobalt impaired feeding by affecting nematocytes, which in turn affected reproduction. At the cellular level, excessive ROS generation, as the principal mechanism of action, primarily occurred in the lysosomes, which was accompanied by the upregulation of expression of the antioxidant genes SOD, GST, GPx, and G6PD. The number of Hsp70 and FoxO transcripts also increased. Interestingly, the upregulations were higher in the 24-h than in the 48-h time-point group, indicating that ROS overwhelmed the cellular defense mechanisms at the latter time-point. Comet assay revealed DNA damage...
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Papers by Mohammed Zeeshan