Floating and submerged leaves of Potamogeton nodosus exhibit distinct variation in the antioxidant system as an ecophysiological adaptive strategy

2016 ◽  
Vol 43 (4) ◽  
pp. 346 ◽  
Author(s):  
Nisha Shabnam ◽  
P. Pardha-Saradhi
Keyword(s):  
Adaptive Strategy ◽  
Monodehydroascorbate Reductase ◽  
Guaiacol Peroxidase ◽  
Total Carotenoids ◽  
Carboxylase Activity ◽  
Nonenzymatic Antioxidants ◽  
Photosynthetic Machinery ◽  
Detoxifying Enzyme ◽  
Floating Leaves ◽  
Potamogeton Nodosus

During evaluations of the ecophysiological adaptations of floating and submerged leaves of Potamogeton nodosus Poir, investigations were carried to assess their antioxidant status. Floating leaves possessed a significantly higher level of C skeletons per unit of area compared with submerged leaves as they possessed greater PSI and PSII activity (hence had superior potential to harness absorbed light energy and generate assimilatory power) and carboxylase activity of Rubisco (hence superior potential to fix CO2) compared with the latter. Interestingly, submerged leaves possessed ~2 times higher H2O2 levels compared with floating leaves. In contrast, the activity of all antioxidant enzymes tested (catalase, guaiacol peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase) were significantly higher in floating leaves than in submerged leaves. Amazingly, catalase activity (a H2O2 detoxifying enzyme) was over fourfold higher in floating leaves than in submerged leaves. Among the nonenzymatic antioxidants, although levels of phenolics, ascorbate and thiols did not vary significantly between floating and submerged leaves, the level of total carotenoids was significantly higher in the former than the latter. In summary, floating leaves possess superior and efficient photosynthetic machinery for light and dark reactions, and also possess strong and superior enzymatic antioxidant machinery for scavenging reactive oxygen species and maintenance of the NAD(P)H to NAD(P)+ ratio compared with submerged leaves. Accordingly, floating leaves possessed superior potential to withstand photodamage compared with submerged leaves. We believe that excess H2O2 provides an ideal defence tool for submerged leaves to counter predators, pests and pathogens.

scholarly journals Comparisons between Orange- and Green-fleshed Non-netted and Orange-fleshed Netted Muskmelons: Antioxidant Changes following Different Harvest and Storage Periods

2006 ◽  
Vol 131 (1) ◽  
pp. 110-117 ◽  
Author(s):  
D. Mark Hodges ◽  
Gene E. Lester
Keyword(s):  
Lipid Peroxidation ◽  
Cucumis Melo ◽  
Pathogenic Bacteria ◽  
Storage Period ◽  
Beta Carotene ◽  
Monodehydroascorbate Reductase ◽  
Guaiacol Peroxidase ◽  
Human Illness ◽  
And Storage ◽  
Retail Conditions

The consumption of netted muskmelons (Cucumis melo L. Reticulatus group) has raised health concerns due to pathogenic bacteria attaching to sites on the netted rind inaccessible to sanitation. The purpose of this study was to compare 1) the enzymic and nonenzymic antioxidant capacity between representative cultivars of netted muskmelon and both green- and orange-fleshed honey dew muskmelons during storage for 17 days and 2) levels of non-nutrient phytochemicals between these genotypes in consideration of ultimately substituting netted orange-fleshed with non-netted orange-fleshed muskmelon. Netted muskmelon (`Cruiser'), green-fleshed (`Honey Brew'), and orange-fleshed (`Orange Dew') muskmelons were harvested in Texas at the beginning (21 May) and at the end (11 June) of the production season in 2004. Fruit were analyzed immediately (day 0) or stored simulating retail conditions for 7 or 14 days at 7 °C and 95% ± 2% relative humidity plus 3 days at 21 °C. Both `Orange Dew' and `Honey Brew' non-netted cultivars evinced similar and less lipid peroxidation, and hence postharvest senescence, during the 17-day storage period than the netted muskmelon `Cruiser'. In comparison with `Cruiser', `Orange Dew' generally exhibited higher concentrations of ß-carotene and phenolics and, with few exceptions, higher activities of the antioxidant enzymes ascorbate peroxidase (AsPX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT), guaiacol peroxidase (POX), and superoxide dismutase (SOD). Higher AsPX and SOD activities in both `Orange Dew' and `Honey Brew' appear to confer a greater resistance to lipid peroxidation in these muskmelon genotypes than to the netted `Cruiser'. `Orange Dew' also appears to be a healthier food choice not only due to its lack of a netted rind which could potentially harbour human illness-related pathogens, but also that it is superior to both `Cruiser' and `Honey Brew' in overall beta-carotene and phenolic levels.

Mitochondrial electron transport protects floating leaves of long leaf pondweed (Potamogeton nodosus Poir) against photoinhibition: comparison with submerged leaves

2014 ◽  
Vol 125 (1-2) ◽  
pp. 305-319 ◽  
Author(s):  
Nisha Shabnam ◽  
P. Sharmila ◽  
Anuradha Sharma ◽  
Reto J. Strasser ◽  
Govindjee ◽  
...  
Keyword(s):  
Electron Transport ◽  
Floating Leaves ◽  
Potamogeton Nodosus

scholarly journals (33) Effect of Natural Products on Decay and Antioxidant Activities of Fresh-cut Papayas

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1004E-1005
Author(s):  
Chien Wang ◽  
Korakot Chanjirakul ◽  
Shiow Wang ◽  
Jingtair Siriphanich
Keyword(s):  
Antioxidant Activities ◽  
Antimicrobial Properties ◽  
Allyl Isothiocyanate ◽  
Monodehydroascorbate Reductase ◽  
Antioxidant Enzyme Activities ◽  
Guaiacol Peroxidase ◽  
Tea Tree ◽  
Naturally Occurring ◽  
Fresh Cut ◽  
Glutathione Cycle

The effect of naturally occurring volatile compounds on decay and antioxidant activities in fresh-cut papayas (Carica papaya L.) was studied. Exposure to methyl jasmonate (MJ), methyl salicylate (MS) or allyl isothiocyanate (AITC) substantially delayed the onset and reduced the severity of decay during and after storage at 5 °C. Treatment with tea tree oil (TTO) or ethanol (ETOH) was also effective in retarding decay, but to a lesser extent. No beneficial effect was obtained with the use of vinegar vapor. MJ and MS increased oxygen radical absorbance capacity and elevated the activities of several antioxidant enzymes, including glutathione reductase, glutathione peroxidase, guaiacol peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and superoxide dismutase. The nonenzyme components in the ascorbate-glutathione cycle were also increased by MJ and MS treatments, including ascorbate and glutathione. It is possible that MJ and MS treatments enhanced the antioxidant system and increased the resistance of tissue to decay. However, while AITC also suppressed the development of decay in papaya slices, it had little effect on antioxidant levels and antioxidant enzyme activities. Apparently, AITC exerted its effect through different mechanisms. Studies are in progress to determine if AITC inhibits decay directly via its antimicrobial properties.

scholarly journals Alpha lipoic acid treatment induces the antioxidant system and ameliorates lipid peroxidation in maize seedlings under osmotic stress

2018 ◽  
Vol 70 (3) ◽  
pp. 503-511 ◽  
Author(s):  
Rabiye Terzi ◽  
Güler Saruhan ◽  
Funda Güven ◽  
Asim Kadioglu
Keyword(s):  
Lipid Peroxidation ◽  
Drought Stress ◽  
Osmotic Stress ◽  
Lipoic Acid ◽  
Physiological Role ◽  
Monodehydroascorbate Reductase ◽  
Guaiacol Peroxidase ◽  
Enzymatic Antioxidants ◽  
Alpha Lipoic Acid ◽  
Maize Cultivars

Plants are markedly affected by drought stress caused by fluctuations in global climate, reduction in rainfall and a decrease in soil fertility. Therefore, some mechanistic strategies to cope with adverse effects of drought stress are needed. Alpha lipoic acid (ALA), a potent antioxidant molecule, is known to function in abiotic stress tolerance. In the current study, we investigated the ALA-stimulated physiological role in tolerance to osmotic stress induced by polyethylene glycol in two maize (Zea mays L.) cultivars (cv. Helen and cv. Akpinar). Application of ALA increased the leaf water potential of maize cultivars under stressful and stress-free conditions but decreased lipid peroxidation and the hydrogen peroxide (H2O2) content. Additionally, enhanced activity of the antioxidant defense system was observed following ALA application. Exogenous ALA elevated the activities of enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR) under osmotic stress as compared to seedlings not exposed to ALA. Conversely, ascorbate peroxidase (APX) activity was decreased by ALA application in both cultivars. Higher GR and MDHAR activities of both cultivars were simultaneously observed in ALA treatments under osmotic stress. Taken together, the data indicated that exogenous ALA may function in arranging resilience against osmotic stress by reducing oxidative damage through induction of the antioxidant machinery in maize cultivars.

Overexpression of AtDREB1 and BcZAT12 Genes Confers Drought Tolerance by Reducing Oxidative Stress in Double Transgenic Tomato (Solanum Lycopersicum Mill.)

2021 ◽  
Author(s):  
Ram Krishna ◽  
Waquar Akhter Ansari ◽  
Durgesh Kumar Jaiswal ◽  
Ram Prasad ◽  
JAY PRAKASH VERMA ◽  
...  
Keyword(s):  
Antioxidant Enzymes ◽  
Drought Stress ◽  
Drought Tolerance ◽  
Yield Potential ◽  
Monodehydroascorbate Reductase ◽  
Guaiacol Peroxidase ◽  
Enzymatic Antioxidants ◽  
Tomato Plants ◽  
Element Binding Protein ◽  
Responsive Element

Abstract A large number of genes has been targeted at the molecular level and transferred in tomato varieties from different sources for drought stress tolerance. Developed single transgenic (ST) plants exhibited better yield under drought stress, although the yield was comparatively lower and the plant growth was reduced. Hence, double transgenic plants were developed to improve yield potential without compromising drought tolerance; for this Dehydration Responsive Element Binding protein 1A (AtDREB1A) and Brassica carinata Zinc finger proteins (BcZAT12) genes were stacked. Developed double transgenic (DT) tomato plants by co-over expressing of both the genes exhibited more enzymatic and non-enzymatic antioxidative activities than control. Double transgenic (DZ1-DZ5) tomato lines, co-overexpressing AtDREB1A and BcZAT12 showed enhanced drought tolerance than their counterpart and wild type (WT) plants at 0, 07, 14, and 21 days of water deficit (DWD), respectively. DT plants showed increased activity of antioxidant enzymes, like catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and guaiacol peroxidase (POD) and accumulation of non-enzymatic antioxidants like ascorbic acid, glutathione as compared to ST and WT. Additionally, the transcript analysis of antioxidant enzymes revealed the level of gene expression in DT tomato plants. In the present study, co-overexpression of AtDREB1A and BcZAT12 genes in tomato showed superior drought tolerance as compared to ST and WT by elevating activity and quantity of enzymatic and non-enzymatic antioxidants. This is the primary report in tomato, which forms the basis for a multigene transgenic approach to cope with drought stress.

Immunocytochemical studies on the behavior of RuBisCO and LHCP II during the cell cycle of synchronized Euglena gracilis

1990 ◽  
Vol 48 (3) ◽  
pp. 662-663
Author(s):  
Tetsuaki Osafune ◽  
Shuji Sumida ◽  
Tomoko Ehara ◽  
Eiji Hase ◽  
Jerome A. Schiff
Keyword(s):  
Cell Cycle ◽  
Immunoelectron Microscopy ◽  
Growth Phase ◽  
Euglena Gracilis ◽  
Dark Period ◽  
Light Period ◽  
Carboxylase Activity ◽  
Immunocytochemical Studies ◽  
Lhcp Ii

Changes in the morphology of pyrenoid and the distribution of RuBisCO in the chloroplast of Euglena gracilis were followed by immunoelectron microscopy during the cell cycle in a light (14 h)- dark (10 h) synchronized culture under photoautotrophic conditions. The imrnunoreactive proteins wereconcentrated in the pyrenoid, and less densely distributed in the stroma during the light period (growth phase, Fig. 1-2), but the pyrenoid disappeared during the dark period (division phase), and RuBisCO was dispersed throughout the stroma. Toward the end of the division phase, the pyrenoid began to form in the center of the stroma, and RuBisCO is again concentrated in that pyrenoid region. From a comparison of photosynthetic CO2-fixation with the total carboxylase activity of RuBisCO extracted from Euglena cells in the growth phase, it is suggested that the carboxylase in the pyrenoid functions in CO2-fixation in photosynthesis.

Smiling won’t make you feel better: Response-focused emotion regulation strategies have little impact on cognitive, behavioural, physiological, and subjective outcomes

2020 ◽  
Author(s):  
Nancy Bahl ◽  
Allison Ouimet
Keyword(s):  
Emotion Regulation ◽  
Negative Emotion ◽  
Electrodermal Activity ◽  
Adaptive Strategy ◽  
Expressive Suppression ◽  
Memory Accuracy ◽  
Cognitive Behavioural ◽  
Regulation Strategies ◽  
The Common ◽  
Subjective Outcomes

Background and Objectives. Response-focused emotion regulation (RF-ER) strategies may alter people’s evoked emotions, influencing psychophysiology, memory accuracy, and affect. Researchers have found that participants engaging in expressive suppression (ES; a RF-ER strategy) experience increased sympathetic nervous system arousal, affect (i.e., higher subjective anxiety and negative emotion), and lowered memory accuracy. It is unclear, however, whether all RF-ER strategies exert maladaptive effects. Expressive dissonance (ED; displaying an expression opposite from how one feels) is a RF-ER strategy, and thus likely considered “maladaptive”. As outlined by the facial feedback hypothesis, however, smiling may increase positive emotion, suggesting it may be an adaptive strategy. We compared the effects of ED and ES to a control condition on psychophysiology, memory accuracy, and affect, to assess whether ED is an adaptive RF-ER strategy, relative to ES. Methods. We randomly assigned 144 female participants to engage in ED, ES, or to naturally observe, while viewing negative and arousing images. We recorded electrodermal activity and self-reported affect throughout the experiment and participants completed memory tasks. Results. There were no differences between groups across outcomes. Conclusion. Engaging in ES or ED may not lead to negative or positive impacts, shedding doubt on the common conclusion that specific strategies are categorically adaptive or maladaptive.

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