Endogenous ascorbate level modulates ozone tolerance in Euglena gracilis cells

Bilodeau, Charles; Chevrier, Normand

doi:10.1016/s0981-9428(98)80019-3

Cited by 7 publications

(3 citation statements)

References 31 publications

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“…Glu‐6‐P‐dehydrogenase (G6PDH) activity was determined according to Bilodeau and Chevrier (1998), as an indication of changes in the demand for reducing equivalents in response to oxidative stress during ageing of WT and FAD 3+7 tubers. G6PDH activity was calculated as nmol NADPH min −1 mg −1 protein using the extinction coefficient of 6.2 m M −1 cm −1 .…”

Section: Methodsmentioning

confidence: 99%

Oxidative metabolism and the physiological age of seed potatoes are affected by increased α‐linolenate content

Zabrouskov

Kumar

Spychalla

et al. 2002

Physiologia Plantarum

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The effects of high alpha-linolenate content on lipid peroxidation, oxidative stress and loss of plant growth potential during ageing of potato (Solanum tuberosum L.) seed-tubers was examined. Endoplasmic reticulum (FAD3) and plastidal (FAD7) 18:2 fatty acid desaturases were upregulated in potato (cv. Desiree), resulting in a 2-fold average increase in mol percentage 18:3 in the total lipid fraction across all transgenic clones. In double-transformed (FAD3+7) tubers, high alpha-linolenate phenotype effected accelerated ageing, resulting in growth responses characteristic of older seed-tubers. Although respiration rates of wild-type (WT) and FAD3+7 tubers were equal at 7 months of storage, rates had increased by 23% and 50% in WT and FAD3+7 tubers, respectively, by 19 months of storage. Electrolyte leakage of tissue from 19-month-old FAD3+7 tubers was significantly greater than that from WT tubers of the same age, indicating that the high alpha-linolenate phenotype was detrimental to membrane integrity during long-term storage. On average, indices of lipid peroxidation (malondialdehyde, ethane, C-6 aldehydes) were higher in older FAD3+7 tubers, relative to WT tubers. Activities of glucose-6-phosphate dehydrogenase, peroxidase, glutathione reductase, ascorbate peroxidase and monodehydroascorbate reductase increased in tubers with advancing age and were higher, on average, in FAD3+7 tubers. Dehydroascorbate reductase activity decreased with age, with no difference between transgenic and WT lines. Collectively, these results indicate that FAD3+7 tubers underwent a higher degree of oxidative stress during ageing. The age-induced increase in respiration of FAD3+7 tubers was at least partly a response to fuel increased free radical scavenging through the ascorbate-glutathione antioxidant pathway. By affecting the susceptibility of lipids to peroxidation, the degree of fatty acid unsaturation influenced the development of oxidative stress and the overall rate at which growth potential was lost from seed-tubers during ageing. Thus, oxidative stress plays an integral role in modulating the ageing process to affect growth potential from potato seed-tubers.

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Section: Methodsmentioning

confidence: 99%

Oxidative metabolism and the physiological age of seed potatoes are affected by increased α‐linolenate content

Zabrouskov

Kumar

Spychalla

et al. 2002

Physiologia Plantarum

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“…The AA content was found to be higher in Bel B plants than in Bel W3 unfumigated plants. A close relationship between ascorbate and ozone tolerance has been reported in two types of Euglena gracilis cells (Bilodeau & Chevrier 1998), as well as in several ozone‐sensitive and ozone‐tolerant plant selections (Wellburn & Wellburn 1996).…”

Section: Discussionmentioning

confidence: 79%

Effects of short‐term ozone fumigation on tobacco plants: response of the scavenging system and expression of the glutathione reductase

Pasqualini

Batini

Ederli

et al. 2001

Plant Cell & Environment

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The role that the constituents of the ascorbate-glutathione cycle play in the mechanism of contrasting ozone sensitivities was examined in mature and old tobacco leaves after acute ozone-fumigation (150 p.p.b., 5 h). Levels of the enzyme activities associated with the detoxifying system were lower in ozone-sensitive Bel W3 control plants than in unfumigated ozone-tolerant Bel B plants. In particular, the endogenous activities of ascorbate peroxidase (APX) and glutathione reductase (GR), and the metabolites ascorbic acid (AA) and reduced glutathione (GSH) were more abundant in Bel B than Bel W3 control plants. These results suggest that the higher tolerance of Bel B to O 3 is associated with a greater initial content of the antioxidant enzymes or metabolites. Only in the mature leaves of the ozone-tolerant Bel B cv. did fumigation trigger activation of APX and, weakly, of dehydroascorbate reductase (DHAR). The activity of these enzymes was significantly lower after ozone treatment in both mature and old leaves of Bel W3 than in control plants. Fumigation had little effect on the ascorbate content. Its main effects on the glutathione pool were that it boosted the oxidized form and lowered the reduced form, particularly in mature Bel W3 leaves. Extractable GR activity remained unchanged in both Bel B and Bel W3 immediately after fumigation, but increased slightly 24 h later, particularly in mature leaves of Bel W3. Exposure to O 3 caused a sharp decline in chloroplastic GR mRNA levels in both cultivars. However, as Western blot analysis failed to detect any major changes in GR protein content at this time, the protein must be highly stable. There is therefore a good correlation between tolerance to O 3 and high endogenous levels of antioxidant metabolites such as AA and GSH in tobacco. In addition, the degree of inducibility of the system discriminates the two cultivars investigated.

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“…Particularly high Asc levels occur in the leaves of alpine plants, where Asc may constitute up to 19% of the leaf carbon pool (Gest et al 2013). Considering algae, Asc was detected in the examined species of green and red algae, as well as in euglenids, cryptophytes, haptophytes, diatoms, and some other clades of photosynthetic stramenopiles (Brown and Miller 1992;Bilodeau and Chevrier 1998).…”

Section: Hydrophilic Low-molecular-weight Antioxidantsmentioning

confidence: 99%

Heavy metal–induced stress in eukaryotic algae—mechanisms of heavy metal toxicity and tolerance with particular emphasis on oxidative stress in exposed cells and the role of antioxidant response

Nowicka

2022

Environ Sci Pollut Res

137

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Heavy metals is a collective term describing metals and metalloids with a density higher than 5 g/cm3. Some of them are essential micronutrients; others do not play a positive role in living organisms. Increased anthropogenic emissions of heavy metal ions pose a serious threat to water and land ecosystems. The mechanism of heavy metal toxicity predominantly depends on (1) their high affinity to thiol groups, (2) spatial similarity to biochemical functional groups, (3) competition with essential metal cations, (4) and induction of oxidative stress. The antioxidant response is therefore crucial for providing tolerance to heavy metal-induced stress. This review aims to summarize the knowledge of heavy metal toxicity, oxidative stress and antioxidant response in eukaryotic algae. Types of ROS, their formation sites in photosynthetic cells, and the damage they cause to the cellular components are described at the beginning. Furthermore, heavy metals are characterized in more detail, including their chemical properties, roles they play in living cells, sources of contamination, biochemical mechanisms of toxicity, and stress symptoms. The following subchapters contain the description of low-molecular-weight antioxidants and ROS-detoxifying enzymes, their properties, cellular localization, and the occurrence in algae belonging to different clades, as well as the summary of the results of the experiments concerning antioxidant response in heavy metal-treated eukaryotic algae. Other mechanisms providing tolerance to metal ions are briefly outlined at the end.

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Endogenous ascorbate level modulates ozone tolerance in Euglena gracilis cells

Cited by 7 publications

References 31 publications

Oxidative metabolism and the physiological age of seed potatoes are affected by increased α‐linolenate content

Oxidative metabolism and the physiological age of seed potatoes are affected by increased α‐linolenate content

Effects of short‐term ozone fumigation on tobacco plants: response of the scavenging system and expression of the glutathione reductase

Heavy metal–induced stress in eukaryotic algae—mechanisms of heavy metal toxicity and tolerance with particular emphasis on oxidative stress in exposed cells and the role of antioxidant response

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