Reactive Oxygen Scavenging Enzymes Research Articles

Sulfur-Oxidizing Bacteria From Coal Mine Enhance Sulfur Nutrition in Pigeonpea (Cajanus cajan L.)

The present investigation was carried out to isolate, identify, and characterize sulfur-oxidizing bacteria (SOB) from coal mines and to evaluate the efficient strains for their ability to influence plant growth and S uptake in pigeonpea. Thirteen bacterial isolates belonging to Stenotrophomonas maltophilia (2), Stenotrophomonas pavanii (2), Rhizobium pusense (5), Bacillus velezensis (2), and Paenibacillus massiliensis (2) were obtained. Among these, seven strains that could reduce the pH of thiosulfate broth were further characterized for sulfur oxidation, plant growth-promoting (PGP) attributes, and in planta studies. Among the seven strains characterized, maximum sulfate ion was recorded for S. maltophilia DRC-18-7A (311.43 mg L−1) closely followed by S. pavanii DRC-18-7B (273.44 mg L−1) and S. maltophilia DRC-18-10 (265.75 mg L−1) after 21 days of inoculation. Among the PGP attributes quantified, maximum P solubilization was recorded in case of S. maltophilia DRC-18-7A (24.39 μg ml−1), while highest siderophore production and IAA production were recorded in S. maltophilia DRC-18-10 (14.25%) and R. pusense DRC-18-25 (15.21 μg ml−1), respectively. S. maltophilia DRC-18-7A closely followed by S. pavanii DRC-18-7B outperformed others in enhancing seed germination (%) and vigour indices. Results clearly indicated that microbial inoculants colonized the plant roots and developed biofilm on the root surface. It was further observed that plants treated with microbial inoculants induce an early formation of secondary and tertiary roots in the pigeonpea compared to the untreated control which was further confirmed by assessing the root architecture using the root scanner. Inoculation of these two strains to pigeonpea significantly enhanced plant growth parameters, the activity of reactive oxygen scavenging (ROS) enzymes, and accumulation of flavonoids, carotenoids, and proline both under sterilized and non-sterilized growth medium (sand and soil in 1:3 ratio). The application of microbial inoculants significantly increased the uptake of nitrogen, phosphorus, potassium, and sulfur in plant shoots. Further, transcript level of phosphate, potassium, and sulfur transporter genes significantly increases upon microbial inoculation leading to increased uptake and translocation of P, K, and S in the pigeonpea. The results indicate that S. maltophilia DRC-18-7A and S. pavanii DRC-18-7B could be recommended as inoculants for pigeonpea to improve its growth and sulfur nutrition.

Physiological and Dual Transcriptional Analysis of Microalga Graesiella emersonii–Amoeboaphelidium protococcarum Pathosystem Uncovers Conserved Defense Response and Robust Pathogenicity

The underlying mechanisms of microalgal host–pathogen interactions remain largely unknown. In this study, we applied physiological and simultaneous dual transcriptomic analysis to characterize the microalga Graesiella emersonii–Amoeboaphelidium protococcarum interaction. Three infection stages were determined according to infection rate and physiological features. Dual RNA-seq results showed that the genes expression of G. emersonii and A. protococcarum were strongly dynamically regulated during the infection. For microalgal hosts, similar to plant defense response, the expression of defense genes involved in the pattern recognition receptors, large heat shock proteins, and reactive oxygen scavenging enzymes (glutathione, ferritin, and catalase) were significantly upregulated during infection. However, some genes encoding resistance proteins (R proteins) with a leucine-rich repeat domain exhibited no significant changes during infection. For endoparasite A. protococcarum, genes for carbohydrate-active enzymes, pathogen–host interactions, and putative effectors were significantly upregulated during infection. Furthermore, the genes in cluster II were significantly enriched in pathways associated with the modulation of vacuole transport, including endocytosis, phagosome, ubiquitin-mediated proteolysis, and SNARE interactions in vesicular transport pathways. These results suggest that G. emersonii has a conserved defense system against pathogen and that endoparasite A. protococcarum possesses a robust pathogenicity to infect the host. Our study characterizes the first transcriptomic profile of microalgae–endoparasite interaction, providing a new promising basis for complete understanding of the algal host defense strategies and parasite pathogenicity.

A Susceptible Scion Reduces Rootstock Tolerance to Ralstonia solanacearum in Grafted Eggplant

The bacterial wilt pathogen (Ralstonia solanacearum) is a highly pathogenic soil-borne bacterium that invades the vascular system of a host plant leading to plant wilting and death. In agricultural systems, tolerant rootstocks are usually used to enhance disease resistance and tolerance in crop plants to soil-borne pathogens. Here, two distinct eggplant cultivars with different tolerances to R. solanacearum infection, the disease-tolerant cultivar ‘S21′ and the disease-susceptible cultivar ‘Rf’, were used to investigate if scion tolerance level can affect tolerance of rootstock upon an infection of the same pathogen. Three scion/rootstock grafted combinations were considered: Rf/S21, S21/S21, and Rf/Rf. Plants that resulted from the combination Rf/S21, composed of the susceptible scion grafts, showed weak tolerance to R. solanacearum infection, and exhibited the poorest growth compared to the tolerant scion grafts (S21/S21). As expected, the combination Rf/Rf showed the lowest level of disease tolerance. Furthermore, a high level of exopolysaccharides (EPSs) and cell wall degrading enzymes (CWDEs) were detected in susceptible scion grafts. These factors are involved in plant growth inhibition due to blocking transport between scion and rootstock and damage of vascular tissues in the plant. A high level of reactive oxygen species (ROS) and active oxygen scavenging enzymes were also detected in susceptible scion grafts. Excess accumulation of these substances harms the dynamic balance in plant vascular systems. These results indicated that the use of a susceptible scion in scion/rootstock eggplant grafts contributed to a reduction in rootstock tolerance to Ralstonia solanacearum.

Oxidation of phenylalanyl-tRNA synthetase positively regulates translational quality control

Accurate translation of the genetic code is maintained in part by aminoacyl-tRNA synthetases (aaRS) proofreading mechanisms that ensure correct attachment of a cognate amino acid to a transfer RNA (tRNA). During environmental stress, such as oxidative stress, demands on aaRS proofreading are altered by changes in the availability of cytoplasmic amino acids. For example, oxidative stress increases levels of cytotoxic tyrosine isomers, noncognate amino acids normally excluded from translation by the proofreading activity of phenylalanyl-tRNA synthetase (PheRS). Here we show that oxidation of PheRS induces a conformational change, generating a partially unstructured protein. This conformational change does not affect Phe or Tyr activation or the aminoacylation activity of PheRS. However, in vitro and ex vivo analyses reveal that proofreading activity to hydrolyze Tyr-tRNAPhe is increased during oxidative stress, while the cognate Phe-tRNAPhe aminoacylation activity is unchanged. In HPX-, Escherichia coli that lack reactive oxygen-scavenging enzymes and accumulate intracellular H2O2, we found that PheRS proofreading is increased by 11%, thereby providing potential protection against hazardous cytoplasmic m-Tyr accumulation. These findings show that in response to oxidative stress, PheRS proofreading is positively regulated without negative effects on the enzyme's housekeeping activity in translation. Our findings also illustrate that while the loss of quality control and mistranslation may be beneficial under some conditions, increased proofreading provides a mechanism for the cell to appropriately respond to environmental changes during oxidative stress.

Genome wide identification of the trihelix transcription factors and overexpression of Gh_A05G2067 (GT-2), a novel gene contributing to increased drought and salt stresses tolerance in cotton.

We identified 102, 51 and 51 proteins encoded by the trihelix genes in Gossypium hirsutum, Gossypium arboreum and Gossypium raimondii, respectively. RNA sequence data and real‐time quantitative polymerase chain reaction analysis showed that Gh_A05G2067 (GT‐2) was highly upregulated under drought and salt stress conditions. Transient expression of GT‐2‐green fluorescent protein fusion protein in protoplast showed that GT‐2 was localized in the nucleus. The overexpression of GT‐2 conferred an enhanced drought tolerance to cotton, with lower malondialdehyde, hydrogen peroxide contents and higher reactive oxygen scavenging enzyme activities. Moreover, chlorophyll content, relative leaf water content (RLWC), excised leaf water loss (ELWL) and cell membrane stability (CMS) were relatively stable in the GT‐2‐overexpressed lines compared to wild‐type (WT). Similarly, stress‐responsive genes RD29A, SOS1, ABF4 and CBL1 were highly upregulated in the GT‐2‐overexpressed lines but were significantly downregulated in WT. In addition, the GT‐2‐silenced cotton plants exhibited a high level of oxidation injury, due to high levels of oxidant enzymes, in addition to negative effects on CMS, ELWL, RLWC and chlorophyll content. These results mark the foundation for future exploration of the trihelix genes in cotton, with an aim of developing more resilient, versatile and highly tolerant cotton genotypes.

Phytotoxicity and oxidative stress perspective of two selected nanoparticles in Brassica juncea.

This study elaborates the consequences of oxidative stress caused by copper oxide (CuO) and titanium dioxide (TiO2) nanoparticles (NPs) in Brassica juncea. Effect of these two NPs on plant physiology, reactive oxygen scavenging enzyme system (ascorbate peroxidase, catalase, superoxide dismutase), proline content and lipid peroxidation has been estimated in leaves as well as root tissues. Bioaccumulation of NPs has also been evaluated in the current study and the interrelated cascade of the enzymatic system with H2O2 production was identified. The uptake of NPs in plant leaves was confirmed by scanning electron microscopy, X-ray diffraction, and Fourier Transform Infrared Spectroscopy. Plant growth was found to be diminished with elevated levels of CuO NPs whereas TiO2 NPs had shown an opposite effect. The plant species accumulated lower concentration of NPs and displayed considerable tolerance against stress, probably due to well-organized and coordinated defense system at the root and shoot level by the intonation of antioxidative enzymes.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-016-0550-3) contains supplementary material, which is available to authorized users.

Antidiabetic andantioxidant properties, and α-amylase and α-glucosidase inhibition effects of triterpene saponins from Piper auritum.

Bioactivity-guided fractionation of methanol extracts from leaves of Piper auritum produced four triterpenoid saponin compounds 1-4. Structures were established based on interpretation of mass spectrometry (MS), nuclear magnetic resonance (NMR) data. 21-(p-methoxycinnamoyl)-olean-12-ene-28oic cid-3-O-α-L-arabinopyranosyl-(1→2)-β-D-glucopyranoside (1) and olean-12-ene-28 methyl ester-3-O-α-L-arabinofuranosyl-(1→2)-β-D-glucopyranoside (2) were orally administered to diabetic mice at dosage of 10 mg/kg of body weight per day for 30 days and resultant biochemical parameters were studied. Both compounds significantly (p<0.05) decreased serum glucose, total cholesterol, and triglyceride levels, compared with controls. Low density lipoprotein and high density lipoprotein cholesterol levels were ameliorated. The effects of lipid peroxidation and oxidative stress in the liver, pancreas, and kidney were reversed, with reductions insulin resistance and stimulation of insulin production. β-Glucosidase activities were studied in vitro. Compounds 1 and 2 can be used to improve glucose and lipid metabolism and to reduce the imbalance between generation of reactive oxygen species and scavenging enzyme activities for prevention of diabetic complications.

Changes of reactive oxygen species and scavenging enzymes of persimmon fruit treated with CO2 deastringency and the effect of hydroxyl radicals on breakdown of cell wall polysaccharides in vitro

Few studies have examined the non-enzymatic disassembly of cell walls in persimmon fruits. The objective of the study was to investigate the changes in the levels of reactive oxygen species and in the activity of antioxidative enzymes and, to evaluate the effect of OH on the in vitro breakdown of cell wall polysaccharides of persimmon fruit at different ripening stages. After harvest, persimmon (Diospyros kaki, ‘Mopan’) fruits were treated with 95% CO2 at room temperature, and the results showed that fruit firmness rapidly decreased and the respiratory and ethylene release rates increased. At the same time, hydroxyl radicals (OH) and O2− rapidly accumulated, and the activities of related antioxidant enzymes such as dismutase peroxidase, catalase and peroxidase superoxide, also changed. The effects of OH induced by the Fenton reaction on the cell wall materials in vitro were investigated; the water soluble pectin and CDTA-soluble pectin contents increased, and Na2CO3-soluble pectin content decreased. Due to the increasing levels of reactive oxygen species, especially OH, during persimmon fruit softening, and the in vitro effect of OH on the scission of cell wall polysaccharides, we postulated that OH may be involved in persimmon fruit softening.

Antioxidant Levels and Activities of Reactive Oxygen-Scavenging Enzymes in Crab Apple Fruits (Malus baccata)

Crab apple (Malus baccata) fruits show higher antioxidant activity, phenols and activities of antioxidant enzymes namely, ascorbate oxidase, catalase, peroxidase, superoxide dismutase except ascorbic acid content as compared to ‘Red Delicious’. Superoxide dismutase was purified and characterized from pulp extract of crab apple fruits by ammonium sulphate precipitation, gel filtration and ion exchange chromatography. Three isoforms of superoxide dismutase were eluted with water, 0.1 molar (M) and 0.2 M potassium chloride (KCl) on anion exchanger. The molecular weight of purified superoxide dismutase isoforms were 15, 17 and 20 kilodaltons (kDa), respectively. Superoxide dismutase isoforms were heat stable up to 90 °C and had pH optima of 7.8. The activity of all the three isoforms increased with increase in concentrations of zinc (Zn2+) ions in the reaction mixture. Keeping in view the importance of superoxide dismutase enzyme as a free radical scavenger and its role in stress tolerance in plants, there is a need to identify novel genes of this enzyme from native germplasm.

Responses of reactive oxygen scavenging enzymes, proline and malondialdehyde to water deficits among six secondary successional seral species in Loess Plateau.

Drought can impact local vegetation dynamics in a long term. In order to predict the possible successional pathway of local community under drought, the responses of some drought resistance indices of six successional seral species in the semi-arid Loss Hilly Region of China were illustrated and compared on three levels of soil water deficits along three growing months (7, 8 and 9). The results showed that: 1) the six species had significant differences in SOD, POD activities and MDA content. The rank correlations between SOD, POD activities and the successional niche positions of the six species were positive, and the correlation between MDA content and the niche positions was negative; 2) activities of SOD, CAT and POD, and content of proline and MDA had significant differences among the three months; 3) there existed significant interactions of SOD, CAT, POD activities and MDA content between months and species. With an exception, no interaction of proline was found. Proline in leaves had a general decline in reproductive month; 4) SOD, CAT, POD activities and proline content had negative correlations with MDA content. Among which, the correlation between SOD activity and MDA content was significant. The results implied that, in arid or semiarid region, the species at later successional stage tend to have strong drought resistance than those at early stage. Anti-drought indices can partially interpret the pathway of community succession in the drought impacted area. SOD activity is more distinct and important on the scope of protecting membrane damage through the scavenging of ROS on exposure to drought.

Microarray Analysis of bacterial blight resistance 1 mutant rice infected with Xanthomonas oryzae pv. oryzae

So Young Yi, Ha Yeon Lee, Hyun A Kim, Chan Ju Lim, Woong Bom Kim, Hyun A Jang, Jong-Seong Jeon, and Suk-Yoon Kwon. Plant Breeding and Biotechnology 2013;1:354-65. https://doi.org/10.9787/PBB.2013.1.4.354

Salinity-induced oxidative stress and regulation of antioxidant defense system in the marine macroalga Ulva prolifera

The physiological and biochemical responses to salinity stresses in Ulva prolifera were investigated, including growth rate, level of oxidative stress and regulation of antioxidant defense system. A six-day exposure to hyposaline (10‰) and hypersaline (60‰) conditions resulted in a significant decrease in growth rate and maximum photosynthetic quantum efficiency (Fv/Fm) compared with the control (30‰). Increases in H 2O 2 contents correlated to the level of lipid peroxidation, which suggested that oxidative damage occurred in salinity stress and was more severe at 60‰ than at 10‰. The amount of total soluble protein (TSP) significantly increased in a hypersaline condition. The fluctuations of four antioxidant substrates and four antioxidant enzymes were determined after the long-term salinity stress. Compared to growth at 30‰, low salinities led to a major increase in activities of catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR), coupled with an increase in contents of ascorbate, glutathione and β-carotenoid. Thalli exposed to hypersaline conditions rapidly accumulated glutathione and did not affect the content of ascorbate, α-tocopherol and β-carotenoid. The activities of CAT, SOD, ascorbate peroxidase (APX) and GR increased in hypersaline conditions, suggesting that reactive oxygen scavenging enzymes played an important role in U. prolifera for adapting to the hypersaline condition. The alterations in antioxidant enzymes and substrates are not consistent between hyposaline and hypersaline stresses in U. prolifera, but the regulation of antioxidant defense system was a vital tolerance mechanism involved in the oxidative stress.

Photosynthesis and photoinhibition in two differently coloured varieties of Oxalis triangularis - the effect of anthocyanin content

The purpose of this study was to clarify effects of anthocyanins on photosynthesis and photoinhibition in green and red leaves of Oxalis triangularis. Gas analysis indicated that green plants had the highest apparent quantum yield for CO2 assimilation [0.051 vs. 0.031 &mu;mol(CO2) &mu;mol-1(photon)] and the highest maximum photosynthesis [10.07 vs. 7.24 &mu;mol(CO2) m-2 s-1], while fluorescence measurements indicated that red plants had the highest PSII quantum yield [0.200 vs. 0.143 &mu;mol(e-) &mu;mol-1(photon)] and ETRmax [66.27 vs. 44.34 &mu;mol(e-) m-2 s-1]. Red plants had high contents of anthocyanins [20.11 mg g-1(DM)], while green plants had low and undetectable levels of anthocyanin. Red plants also had statistically significantly (0.05&gt;p&gt;0.01) lower contents of xanthophyll cycle components [0.63 vs. 0.76 mg g-1(DM)] and higher activities of the reactive oxygen scavenging enzyme ascorbate peroxidase [41.2 vs. 10.0 nkat g-1(DM)]. Anthocyanins act as a sunscreen, protecting the chloroplasts from high light intensities. This shading effect causes a lower photosynthetic CO2 assimilation in red plants compared to green plants, but a higher quantum efficiency of photosystem II (PSII). Anthocyanins contribute to photoprotection, compensating for lower xanthophyll content in red plants, and red plants are less photoinhibited than green plants, as illustrated by the Fv/Fm ratio.

Antioxidant metabolism in pearl millet genotypes during compatible and incompatible interaction with downy mildew pathogen

In this study, the ascorbic acid content, lipid peroxidation product, reactive oxygen generation and scavenging enzyme activities were determined in pearl millet [Pennisetum glaucum (L.) R.Br.] leaves. These parameters were analysed at two stages: (i) pre-infection [45 days after sowing (DAS)] and (ii) post-infection [7 days after infection (DAI), i.e. 57 DAS]. Lipid peroxidation product (malondialdehyde content) was recorded higher in compatible interaction at pre-infection stage while it was increased in incompatible interaction at post-infection stage. Resistant genotypes had higher ascorbic acid content at both the stages of analysis. Superoxide dismutase (SOD) activity was higher in susceptible genotypes at pre-infection but after infection it was found to be higher in resistant genotypes. Ascorbate peroxidase, catalase (CAT) and lipoxygenase activities were higher in resistant genotypes at both the stages of analysis. Native PAGE isozyme banding pattern of SOD, CAT, APX and esterase showed some inducible band(s) due to disease infection.

Seed pre-treatment in rice reduces damage, enhances carbohydrate mobilization and improves emergence and seedling establishment under flooded conditions.

Early flooding helps control weeds but reduces seedling establishment in direct-seeded rice (Oryza sativa). When combined with appropriate management practices, the use of genotypes that better tolerate flooding during emergence can enhance crop establishment in flood-prone areas. Management options include seed pre-treatment and we tested the influence of pre-soaking for 24 h prior to sowing or of priming (soaking for 24 or 48 h followed by drying). The effects on seedling establishment after 21-day flooding of pre-soaking seeds for 24 h before sowing and/or of priming seeds were examined together with physiological responses connected with reactive oxygen scavenging. Seeds of four lines with contrasting abilities to tolerate flooding at the germination stage were compared. Seeds were primed using KCl solutions (48 h) or water (24 h) and pre-soaked using water. Lipid peroxidation and activities of reactive oxygen-scavenging enzymes were measured in seeds before sowing. Carbohydrate mobilization in germinating seeds and seedling growth were also monitored at intervals. Seed pre-treatment by pre-soaking or by priming increased survival of flooding and accelerated and improved seedling establishment, especially in tolerant genotypes. Primed seeds had less lipid peroxidation and higher superoxide dismutase (SOD) and catalase (CAT) activities than non-primed seeds. Amylase activities and starch breakdown were also hastened in primed seeds. Survival after flooding was positively correlated with amylase activity but negatively correlated with the extent of lipid peroxidation. Pre-soaking and priming improved seedling establishment in flooded soil, enhanced the capacity to scavenge reactive oxygen species in seeds by increasing SOD and CAT activities, and hastened carbohydrate mobilization. Tolerant genotypes responded better to these treatments, emphasizing the effectiveness of combining genetic tolerance with appropriate seed pre-treatment to improve seedling establishment of rice sown in flooded soils.

Fe-Chlorophyllin Promotes the Growth of Wheat Roots Associated with Nitric Oxide Generation

Effects of Fe-chlorophyllin on the growth of wheat root were investigated in this study. We found that Fe-chlorophyllin can promote root growth. The production of nitric oxide in wheat root was detected using DAF-2DA fluorescent emission. The intensity of fluorescent in the presence of 0.1 mg/L Fe-chlorophyllin was near to that observed with the positive control of sodium nitroprusside (SNP), the nitric oxide donor. IAA oxidase activity decreased with all treatments of Fe-chlorophyllin from 0.01 to 10 mg/L. At the relatively lower Fe-chlorophyllin concentration of 0.1 mg/L, the activity of IAA oxidase displayed a remarkable decrease, being 40.1% lower than the control. Meanwhile, Fe-chlorophyllin treatment could increase the activities of reactive oxygen scavenging enzymes, such as superoxide dismutase (SOD) and peroxidase (POD), as determined using non-denaturing polyacrylamide gel electrophoresis. These results indicate that Fe-chlorophyllin contributes to the growth of wheat root associated with nitric oxide generation.

Effects of Acetylsalicylic Acid and Calcium Chloride on Photosynthetic Apparatus and Reactive Oxygen-Scavenging Enzymes in Chrysanthemum Under Low Temperature Stress with Low Light

The effects of acetylsalicylic acid (ASA), CaCl 2, and ASA + CaCl 2 on the photosynthetic apparatus and antioxidant enzyme activities were investigated in chrysanthemum Jinba (a cut flower cultivar) under low temperature stress with low light (TL stress) (16/12°C, day/night, PFD 100 μmol m -2 s -1). The results showed that under TL stress, the net photosynthesis rate (Pn), carboxylation efficiency (CE), apparent quantum yield (AQY), maximal photochemical efficiency (Fv/Fm) of PSII, quantum yield of PSII electron transport (øPSII), and photochemical quenching (qP) of the chrysanthemum leaves in all treatments were significantly decreased, but the decreases were alleviated by ASA, CaCl 2, and ASA + CaCl 2 treatments compared with the controls. The alleviating effect of ASA + CaCl 2 was better than either ASA or CaCl 2 single treatment. Moreover, the ASA + CaCl 2 treatment highly improved the chlorophyll content, relatively improved the number and size of chloroplast and starch grain in the leaves of chrysanthemum plants compared with ASA and CaCl 2 treatments. It was indicated that ASA and/or CaCl 2 could regulate the photosynthetic functions in the leaves of chrysanthemum plants to enhance the resistance against TL stress. On the other hand, reduction in relative conductance rate implied that ASA and/ or CaCl 2 could protect from membrane injury in leaves of chrysanthemum plants. The activities of SOD, POD, and CAT in the treated leaves of chrysanthemum were increased as compared with the controls. It was suggested that ASA and/or CaCl 2 had positive regulation effects on the defence enzyme activities in chrysanthemum leaves which could protect the photosynthetic apparatus to a certain degree under the TL stress. In brief, the treatment of ASA together with CaCl 2 was better for chrysanthemum plants to adapt TL stress than single ASA or CaCl 2 treatments.

Expressed sequence tag (EST) profiling in hyper saline shocked Dunaliella salina reveals high expression of protein synthetic apparatus components

The unicellular, halotolerant, green alga, Dunaliella salina (Chlorophyceae) has the unique ability to adapt and grow in a wide range of salt conditions from about 0.05 to 5.5 M. To better understand the molecular basis of its salinity tolerance, a complementary DNA (cDNA) library was constructed from D. salina cells adapted to 2.5 M NaCl, salt-shocked at 3.4 M NaCl for 5 h, and used to generate an expressed sequence tag (EST) database. ESTs were obtained for 2831 clones representing 1401 unique transcripts. Putative functions were assigned to 1901 (67.2%) ESTs after comparison with protein databases. An additional 154 (5.4%) ESTs had significant similarity to known sequences whose functions are unclear and 776 (27.4%) had no similarity to known sequences. For those D. salina ESTs for which functional assignments could be made, the largest functional categories included protein synthesis (35.7%), energy (photosynthesis) (21.4%), primary metabolism (13.8%) and protein fate (6.8%). Within the protein synthesis category, the vast majority of ESTs (80.3%) encoded ribosomal proteins representing about 95% of the approximately 82 subunits of the cytosolic ribosome indicating that D. salina invests substantial resources in the production and maintenance of protein synthesis. The increased mRNA expression upon salinity shock was verified for a small set of selected genes by real-time, quantitative reverse-transcription-polymerase chain reaction (qRT-PCR). This EST collection also provided important new insights into the genetic underpinnings for the biosynthesis and utilization of glycerol and other osmoprotectants, the carotenoid biosynthetic pathway, reactive oxygen-scavenging enzymes, and molecular chaperones (heat shock proteins) not described previously for D. salina. EST discovery also revealed the existence of RNA interference and signaling pathways associated with osmotic stress adaptation. The unknown ESTs described here provide a rich resource for the identification of novel genes associated with the mechanistic basis of salinity stress tolerance and other stress-adaptive traits.

Stress tolerance and antioxidant enzymatic activities in the metabolisms of the reactive oxygen species in two intertidal red algae Grateloupia turuturu and Palmaria palmata

This investigation was designed to compare the differential stress tolerance in young thalli of two similar intertidal red seaweeds, Grateloupia turuturu Yamada and Palmaria palmata Kuntze, and to identify whether the invasive alga G. turuturu was more stress tolerant than P. palmata to cope with adverse environmental conditions. To do so, we measured the production of reactive oxygen caused by methyl viologen (MV) by assessing the oxidation of dichlorohydrofluorescein (DCFH) to dichlorofluorescein (DCF), the activities of reactive oxygen scavenging enzymes and the changes of the optimal fluorescence quantum yield (Fv/Fm) when the thalli of the two species were exposed to oxidative stresses caused by the addition of MV, H 2O 2, 3(3, 4-dichlorophenyl)-1,1-dimethyl urea (DCMU), heavy metal, changes of salinities, heat and freezing. Results demonstrated that the activities of superoxide dismutase (SOD) and peroxidase (POD) in G. turuturu were much higher than in P. palmata. Fv/Fm in G. turuturu was less sensitive than that in P. palmata to MV, H 2O 2, DCMU, heavy metal, salinity and heat stress, indicating that G. turuturu could be better acclimatized to changing environments and thus had a higher threshold for oxidative stress than P. palmata. G. turuturu was shown to be more sensitive to freezing treatment (− 20 °C), which explained why the appearance of G. turuturu was rarely reported in colder water environments.

No. 6 Vol. 42, No. 2, pp. 121–127, 2008 Makeup inhibits reduction of reactive oxygen scavenging enzyme activity induced by mental stress

Recent studies showed that makeup reduces mental stress, indicated by not only psychological but also physiological values. In this study, we examined the relationship between mental stress and the activity of reactive oxygen scavenging enzymes such as superoxide dismutase (SOD) and catalase (CAT), and the effect of the mental stress reduction by makeup on the activity of reactive oxygen scavenging enzymes. In experiment 1, we measured the concentration of cortisol and activity of SOD in saliva after the addition of mental stress. In this result, the concentration of cortisol increased and the activity of SOD decreased significantly. As we examined the effect of makeup following the mental stress addition in experiment 2, the concentration of cortisol decreased and the activity of SOD and CAT increased. Moreover, we showed a decrease in the anxiety state and increase in spiritual health as the psychological effects. Those results suggest that makeup psychologically canceled anxiety and physiologically inhibited the reduction of reactive oxygen scavenging enzyme activity induced by the mental stress.