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Nanotoxicity and Possible Health Risks
Published in Costas Demetzos, Stergios Pispas, Natassa Pippa, Drug Delivery Nanosystems, 2019
Elena Vlastou, Efstathios P. Efstathopoulos, Maria Gazouli
ROS formation is the basic mechanism that causes nanotoxicity. ROS generation is a physiological/biological procedure resulting from oxygen metabolism; it can affect the homeostatic process, and it plays a vital part in cell signaling. Hydroxyl radicals (●OH), singlet oxygen (1O2), superoxide anions (●O2-), hydrogen peroxide (H2O2), and hypochlorous acid (HOCl) are the primary oxidative species, and they are created either in or outside the cell. They result from physical cell functions, such as inflammatory response and mitochondrial respiratory, or external factors, such as radiation, atmospheric pollution, tobacco, drugs, and ENPs. However, cells have their own weapons to defeat ROS generation. More specifically, antioxidant production is the main procedure that follows ROS appearance—an attempt to detoxify the oxidative species. A superoxide radical could be transformed into a reduced-activity peroxide radical by superoxide dismutase [61], a primary antioxidant of the cell defense mechanism [57]. Catalase is able to destroy the peroxide radical by converting it to water and molecular oxygen [62], while a secondary defense antioxidant, known as glutathione peroxidase, has been found to minimize the production of plenty of hydroperoxides [63].
Abiotic Stress-Mediated Oxidative Damage in Plants
Published in Hasanuzzaman Mirza, Nahar Kamrun, Fujita Masayuki, Oku Hirosuke, Tofazzal M. Islam, Approaches for Enhancing Abiotic Stress Tolerance in Plants, 2019
Ruchi Rai, Shilpi Singh, Shweta Rai, Alka Shankar, Antra Chatterjee, L.C. Rai
Superoxide dismutase (SOD, EC 1.15.1.1) is ubiquitous and plays a central role in defense against oxidative stress in all aerobic organisms. The enzyme SOD belongs to the group of metalloenzymes and catalyzes the dismutation of superoxide molecules into hydrogen peroxide and oxygen (Alscher et al., 2002). It is present in most of the subcellular compartments that generate activated oxygen and has a metal cofactor, depending on which it can be classified in three different groups: (1) Fe SODs consisting of two species, one homodimer and one tetramer, found within both prokaryotes and eukaryotes. They are most abundantly localized inside plant chloroplasts, where they are indigenous. (2) Mn SODs consist of a homodimer and homotetramer species, each containing a single Mn (III) atom per subunit, found predominantly in mitochondrion and peroxisomes. (3) Cu/Zn-SODs are cyanide sensitive and have electrical properties very different from those of the other two classes, which are cyanide insensitive. These are concentrated in the chloroplast, cytosol and, in some cases, the extracellular space. The compartmentalization of different forms of SOD throughout the plant makes them counteract stress very effectively. All forms of SOD are nuclear encoded and targeted to their respective subcellular compartments by an amino-terminal targeting sequence (Bowler et al., 1992; Racchi et al., 2001). SOD activity has been reported to increase in plants exposed to various environmental stresses, including drought and metal toxicity (Sharma and Dubey, 2005; Borsetti et al., 2005). It was suggested that SOD can be used as an indirect selection criterion for screening drought-resistant plant materials (Zaefyzadeh et al., 2009). Overproduction of SOD has been reported to result in enhanced oxidative stress tolerance in plants (Gupta et al., 1993). SOD mRNA abundance increases whenever there is a chloroplast-localized oxidative stress, thus providing an insight into the way that each treatment affects the different subcellular compartments. Bowler and coworkers in 1991 developed transgenic tobacco plants from Nicotiana plumbaginifolia in which leaves of the transgenic plants showed reduced levels of membrane damage following exposure to methyl viologen (MV) and light. In addition, these plants were found to have increased protection from ozone damage (Bowler et al., 1991). Expression of the same chloroplastic Mn-SOD gene in alfalfa was found to provide increased tolerance to acifluorfen and freezing (McKersie et al., 1993, 1996).
An experimental investigation on the influence of storage container on the development of oxidised products in biofuel
Published in Biofuels, 2023
Paweł Grabowski, Magdalena Szostek
The peroxide anion is important in the process of reducing oxygen to generate other reactive oxygen species, such as hydrogen peroxide, the hydroxyl radical, and singlet oxygen. From the disproportionation of the peroxide anion, hydrogen peroxide is formed, which is a less reactive oxidant than peroxide. Superoxide dismutase catalyzes the dismutation of superoxide anions to hydrogen peroxide and oxygen. Hydroxyl radicals are formed from the radiolysis of water or the decomposition of hydrogen peroxide by ultraviolet (UV) light, catalase, or peroxidase. The reaction of a superoxide anion and hydrogen peroxide in the presence of transition metals produces a very reactive hydroxyl radical and singlet oxygen in the Haber-Weiss reaction. Singlet oxygen is most often produced by photosensitization reactions. A photosensitizer such as chlorophyll absorbs light energy and transfers it to triplet oxygen to form singlet oxygen. Peroxide radicals react with other peroxide radicals and produce singlet oxygen (Russell mechanism) [16].
Augmentation of metal-tolerant bacteria elevates growth and reduces metal toxicity in spinach
Published in Bioremediation Journal, 2021
K. M. Sarim, U. Sahu, M. S. Bhoyar, D. P. Singh, U. B. Singh, A. Sahu, A. Gupta, A. Mandal, J. K. Thakur, M. C. Manna
Antioxidative detoxification mechanism via antioxidant enzyme production in plants maintains ROS at optimum levels. During environmental stresses, the ROS production increases causing high oxidative damage, which is controlled by these antioxidant enzymes. Superoxide dismutase (SOD) is an antioxidant enzyme responsible for converting superoxide into H2O2. Altered activities of SOD have been reported as indicators of various types of heavy metal stress in different plants (Ekmekçi, Tanyolaç, and Ayhan 2008; Priya et al. 2014; Kisa 2018). In this study, SOD activity found to be more in metal-stressed plants than control, which further increased with bacterial amendment under metal-stressed conditions. This may be accounted for increased SOD gene expression in bacterial-inoculated plants (Gururani et al. 2012).
Effects of emerging persistent organic pollutant perfluorooctane sulfonate (PFOS) on the Crustacean Gammarus insensibilis
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Samir Touaylia, Abdelhafidh Khazri, Ali Mezni, Mustapha Bejaoui
PFOS have been produced due to their unique properties, such as anti-wetting or surfactant (Florentin et al.2011). It was reported to be toxic for aquatic biota (Chen et al.2016; Jeong et al.2016). We aimed at elaborating field application of the integrated use of biomarkers (AChE, SOD, and MDA) for detecting the possible exposure/effect induced by PFOS in native marine organisms from a coastal marine area, Bizerte lagoon, of high environmental value, but under constant anthropogenic pressure. The tests performed show a typical behavior of enzymatic activities that give information about the oxidative stress-induced. Acetylcholinesterase expression has been qualified to be at a safe rate which implies the capacity of the animal to protect the cholinergic system. The superoxide dismutase activity was qualified to be an effective barrier against oxidative stress. The study shows an induced oxidative stress after exposure of organisms to PFOS, the MDA secretion have to be well involved and mention clearly the oxidative aspect of the lipidic associated systems, defense enzymes may be also affected and worked together to neutralize the effect of the exposure. The information provided here also enhances our knowledge on the molecular responses of Gammarus insensibilis towards environmental pollution exposure and on the toxicological effect of this contaminant.