Involvement Of Antioxidant Enzymes Research Articles

Effects of Chromium Exposure on the Gene Expression of the Midgut in Silkworms, Bombyx mori.

Chromium is a severe heavy metal pollutant with significant environmental risks. The effects of Chromium on the digestion of Bombyx mori (silkworms) are of particular importance due to their ecological and economic significance. Herein, RNA sequencing was conducted on nine midgut samples from silkworms exposed to control, 12 g/kg and 24 g/kg Chromium chemical diets. Comparative transcriptomics revealed that under moderate Chromium exposure, there was a significant increase in up-regulated genes (1268 up-regulated to 857 down-regulated), indicating a stimulation response. At higher stress levels, a weakened survival response was observed, with a decrease in up-regulated genes and an increase in down-regulated genes (374 up-regulated to 399 down-regulated). A notable shift in cellular responses under medium chromium exposure was exposed, signifying the activation of crucial metabolic and transport systems and an elevation in cellular stress and toxicity mechanisms. The observation of up-regulated gene expression within xenobiotic metabolism pathways suggests a heightened defense against Chromium-induced oxidative stress, which was primarily through the involvement of antioxidant enzymes. Conversely, high-dose Chromium exposure down-regulates the folate biosynthesis pathway, indicating biological toxicity. Two novel genes responsive to pressure were identified, which could facilitate future stress adaptation understanding. The findings provide insights into the molecular mechanisms underlying silkworms' digestion response to Chromium exposure and could inform its biological toxicity.

Biochemical changes in Quercus robur L. leaves after Erysiphe alphitoides infection

AbstractAlthough powdery mildew caused by Erysiphe alphitoides is a major foliage diseases of young oak forest plantations, the knowledge of defence responses of the tree to infection by this pathogen is limited. We investigated biochemical changes characteristic of the defence responses in oak leaves infected to different degrees. Foliage was screened for selected reactive oxygen and nitrogen species using biochemical and histochemical methods in July, August and September over three vegetation seasons. High‐performance liquid chromatography or gas chromatograph‐mass spectrometry analyses of phenolic compounds and volatile organic compounds, respectively, were performed. Changes in the activity of the antioxidant enzymes, that is superoxide dismutase, catalase and peroxidase, were also analysed with biochemical and electrophoresis methods. Infection‐induced biochemical responses occurred in oak leaves in all months, mainly in August, including increased catalase and peroxidase activities and the accumulation of hydrogen peroxide, nitric oxide and phenolic compounds of the flavonoid and derivatives of hydroxybenzoic and cinnamic acids classes. Volatile organic compounds, including lipoxygenase products, isoprenoids and methyl salicylate, were produced with high intensity in all the infected leaves. These results suggested that enhanced production of reactive oxygen and nitrogen species, and phenolic compounds, and the involvement of antioxidant enzymes plus induced emissions of volatile organic compounds may be essential components of the defence response of pedunculate oak to infection by E. alphitoides.

Interactive effects of salt stress and Pseudomonas syringae pv. lachrymans infection in cucumber: Involvement of antioxidant enzymes, abscisic acid and salicylic acid

Under natural conditions plants have to cope with a wide range of abiotic and biotic stressors that occur simultaneously or in sequence, and phytohormones and reactive oxygen species are key mediators of plant stress response. However, their role in defence against abiotic and biotic stresses acting in combination still needs elucidation. We studied the involvement of reactive oxygen species, antioxidant enzymes, abscisic acid and salicylic acid in the response of cucumber plants exposed to individual or sequential action of salt stress (50mM or 100mM NaCl) and Pseudomonas syringae pv. lachrymans. Salt stress was more harmful than infection, especially with respect to leaf growth and stomata opening. The effects were most severe when the stresses were combined. Cucumber response to the pathogen infection was negatively affected by prior NaCl treatment. NaCl-induced changes promoted the pathogen growth and intensified the disease symptoms. It also provoked specific interactions between stress signalling components at the levels of hormones and the prooxidant/antioxidant mechanisms, exemplified by stronger H2O2 accumulation and Fe superoxide dismutase activation, changed salicylic acid/abscisic acid balance and modified PR1 gene expression.

Antioxidative Response of Quinoa Exposed to Iso‐Osmotic, Ionic and Non‐Ionic Salt Stress

AbstractAntioxidants play an important role in adapting plants to abiotic stress by detoxifying reactive oxygen species (ROS). Involvement of antioxidant enzymes in abiotic stress tolerance of highly stress‐tolerant quinoa was studied in a climatic chamber at 6 mOsm (milliosmolar) ionic (300 mm NaCl) and non‐ionic (600 mm mannitol) salts combined with increasing levels of potassium K1 and K2 (6, 12 mm), respectively. Fifteen days of salt treatment (both ionic and non‐ionic) decreased plant growth (shoot and root fresh weight), stomatal conductance and chlorophyll content index. Furthermore, both forms of salt stress increased the activities of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase up to 2.33‐, 3.98‐, 4.78‐ and 5.55‐folds, respectively, compared to no salt treatment, whereas membrane stability index decreased corresponding to increase in lipid peroxidation (malondialdehyde), with salt treatments compared to non‐stressed plants. However, no significant effect of potassium and salt treatments has been noticed on the maximal photochemical efficiency of PSII. The results suggested that enhanced antioxidant enzymes activity under salt stress could be one of the factors responsible for abiotic stress tolerance in quinoa.

Dominant Role of Peroxiredoxin/JNK Axis in Stemness Regulation During Neurogenesis from Embryonic Stem Cells

Redox balance has been suggested as an important determinant of "stemness" in embryonic stem cells (ESCs). In this study, we demonstrate that peroxiredoxin (Prx) plays a pivotal role in maintenance of ESC stemness during neurogenesis through suppression of reactive oxygen species (ROS)-sensitive signaling. During neurogenesis, Prx I and Oct4 are expressed in a mutually dependent manner and their expression is abruptly downregulated by an excess of ROS. Thus, in Prx I(-/-) or Prx II(-/-) ESCs, rapid loss of stemness can occur due to spontaneous ROS overload, leading to their active commitment into neurons; however, stemness is restored by the addition of an antioxidant or an inhibitor of c-Jun N-terminal kinase (JNK). In addition, Prx I and Prx II appear to have a tight association with the mechanism underlying the protection of ESC stemness in developing teratomas. These results suggest that Prx functions as a protector of ESC stemness by opposing ROS/JNK cascades during neurogenesis. Therefore, our findings have important implications for understanding of maintenance of ESC stemness through involvement of antioxidant enzymes and may lead to development of an alternative stem cell-based therapeutic strategy for production of high-quality neurons in large quantity.

Involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation ofReaumuria soongoricato salt stress

Involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation of<i>Reaumuria soongorica</i>to salt stress

Study of Antioxidant Enzymes Activity during Organogenesis and In Vitro Propagation of Asiatic Hybrid Lily

A protocol for indirect differentiation of shoots / roots from leaf callus of Asiatic hybrid lily was developed through in vitro methods. The involvement of antioxidant enzymes, like, SOD, POX and CAT, and their isoenzymes during organogenesis in the morphogenetic callus was stud ied.The activity of these enzymes was increased during early development and differentiation of callus. SOD activity increased significantly as compared to POX and CAT during root formation, while it decreased in shoot formation and the decrease was significant in POX and CAT enzymes. The results indicate that the organogenesis is a very complicated biological process involving up and down regulation of a number of antioxidant enzymes, which seem to play an important role during organogenesis of Lilium callus.

Changes in antioxidant enzymes, hydrogen peroxide, salicylic acid and oxidative stress in compatible and incompatible host-tobamovirus interaction

The effect of tobamovirus (TMV and ToMV) infection on changes in antioxidant enzymes, endogenous salicylic acid, endogenous hydrogen peroxide, lipid peroxidation and protein oxidation was studied in compatible (tomato and bell pepper) and incompatible hosts (Nicotiana glutinosa and Nicotiana tabacum cv. xanthi). A time course study of antioxidant enzymes such as peroxidase and catalase was studied in both interactions. Along with these studies, a time course change of endogenous hydrogen peroxide in both compatible and incompatible hosts against tobamoviruses was carried out spectrophotometrically. Histochemical changes in hydrogen peroxide were studied by using Starch-potassium iodide (KI) method. The endogenous levels of salicylic acid were quantified at 24 hours post inoculation (hpi). The effect of tobamoviruses on the lipid peroxidation levels along with protein oxidation was also studied at 24 hpi. The results showed increased peroxidase, salicylic acid, lipid peroxidation, protein oxidation, hydrogen peroxide and decreased catalase in incompatible host-tobamovirus interaction in comparison to compatible hosts. In incompatible hosts, more numbers of cells showed hydrogen peroxide accumulation at 24 hpi. These results suggested the involvement of antioxidant enzymes, salicylic acid, hydrogen peroxide and oxidative stress in incompatible host defense against tobamoviruses. As a consequence of tobamovirus infection, an oxidative stress, indicated by the increase in lipid peroxidation was observed in incompatible interaction. Slight changes in enzymes, lipid peroxidation and hydrogen peroxide in incompatible hosts indicate that these changes have roles in susceptible hosts.

Differential tolerance to Mn toxicity in perennial ryegrass genotypes: involvement of antioxidative enzymes and root exudation of carboxylates

Mechanisms underlying differential tolerance to Manganese (Mn) toxicity in perennial ryegrass (Lolium perenne L.) cultivars are poorly understood. We evaluated activity of antioxidative enzymes and root exudation of carboxylates in four ryegrass cultivars subjected to increasing Mn supply under nutrient solution conditions. A growth reduction caused by Mn toxicity was smaller in Jumbo and Kingston than Nui and Aries cultivars. Shoot Mn accumulation varied in the order Nui > Aries > Kingston > Jumbo. Ascorbate peroxidase and guaiacol peroxidase activities increased with Mn excess. Mn-tolerant Jumbo and Kingston had high activity of these enzymes and relatively low lipid peroxidation. Kingston was most tolerant to high tissue Mn concentrations and had the highest superoxide dismutase activity. Increased activity of antioxidative enzymes in Mn-tolerant cultivars could protect their tissues against oxidative stress triggered by Mn excess. Mn toxicity induced root exudation of carboxylates; oxalate and citrate may decrease Mn availability in the rhizosphere, thus enhancing Mn tolerance in ryegrass.

Involvement of antioxidative enzymes in the tolerance to NaCl-induced oxidative stress in leaves of Sesbania rostrata

Involvement of antioxidative enzymes in the tolerance to NaCl-induced oxidative stress in leaves of Sesbania rostrata

Non-optimal growth temperatures and antioxidants in the leaves of Sorghum bicolor (L.) Moench. II. Short-term acclimation

Summary In pursuing previous studies on long-term acclimation to non-optimal, non-stressing growth temperatures (Badiani et al., 1993 b; Paolacci et al., 1997; Fusari et al., in press), the foliar antioxidant status and the photosynthetic capacity were evaluated in two sorghum [ Sorghum bicolor (L.) Moench.] cultivars of different agroclimatic provenance, namely Aralba and ICSV 112, which were grown at the near-optimal temperature of 27 ± 0.3 °C and then gradually (1°Ch −1 ) and transiently (up to 120 h) exposed to suboptimal, 17 ± 0.4 °C, or supraoptimal, 37 ± 0.1 °C, temperatures, under moderate light intensity and ad libitum water and mineral nutrition. Comparative analysis of short-term and long-term responses to non-optimal growth temperatures suggested that: i ) even realistic, i.e. limited and gradual, upward or downward shifts from the normative growth temperature, incapable of causing evident stress symptoms, might per se enhance the formation of reactive oxygen species whose effect, albeit not drastic, appear to be more noxious during the early stages of the exposure; ii ) this disthermia-driven oxidative burst triggers almost immediate and extensive changes in all of the major antioxidant metabolites and scavenging enzymes. This could be aimed at preparing plant tissues in case moderate disthermia flows into authentic temperature stress; iii ) certain short-term antioxidant changes persist beyond the relief of the disthermic regimes; and iv ) however, in case the exposure to non-optimal growth temperatures becomes chronic, long-term adjustment processes take place, consisting of increases in protective pigments, ascorbic acid and glutathione, but without the involvement of antioxidant enzymes. Such a strategy might be aimed at keeping disthermia-dependent oxidative stress under control at the lowest possible price in terms of metabolic resources.