Low Levels Of Hydrogen Peroxide Research Articles

Peroxiredoxin 1 promotes proliferation and inhibits differentiation of MC3T3-E1 cells via AKT1 / NF-κB signaling pathway

ObjectivesOsteoporosis is the most common metabolic bone disease worldwide. The decrease in bone mass is primarily accompanied by a decrease in the number and activity of osteoblasts. Peroxiredoxins (PRDXs) are proteins that detect extremely low peroxide levels and act as sensors that regulate oxidation signals, thereby regulating various cellular functions. This study aimed to evaluate the effects of PRDX1 and estrogen on the biological behavior of osteoblasts, including their proliferation and differentiation. MethodsOvariectomized (OVX) mice were used to establish a model of osteoporosis and perform morphological and immunohistochemical analyses. Prdx1 gene knockout and overexpression were performed in mouse MC3T3-E1 pre-osteoblasts to assess proliferation and osteogenic differentiation using the cell counting kit-8, quantitative reverse transcription polymerase chain reaction, western blotting (WB), Alizarin Red S staining, etc. ResultsThe OVX mice exhibited osteoporosis and PRDX1 expression increased. In vitro experiments showed that during the osteogenic differentiation of osteoblasts, PRDX1 expression decreased, while the expression of COL1 and RUNX2 increased. After Prdx1 knockout, the proliferation of osteoblasts decreased; expression of Runx2, ALP, and COL1 increased; and mineralization increased. However, after Prdx1 overexpression, osteoblast proliferation was enhanced, whereas osteogenic differentiation and mineralization were inhibited. Estrogen inhibits the H2O2-induced decrease in osteoblastic differentiation and increase in PRDX1 expression. WB revealed that when LY294002 inhibited the AKT signaling pathway, the levels of p-AKT1, p-P65, and PRDX1 protein in MC3T3-E1 cells decreased. However, when pyrrolidine dithiocarbamate (PDTC) inhibited the NF-κB signaling pathway, the expression of p-AKT1 and PRDX1 did not change except for a significant reduction of p-P65 expression. Furthermore, PDTC reversed the decreased expression of RUNX2, ALP, and COL1 caused by PRDX1 overexpression. ConclusionsPRDX1 promotes the proliferation of osteoblasts and inhibits osteogenic differentiation. Estrogen regulated osteoblastic differentiation by affecting the expression of PRDX1 in osteoblasts, and the effect is related to the AKT1/NF-κB signaling pathway.

At-home bleaching with carbamide peroxide with concentrations below 10%: bleaching efficacy and permeability in the pulp chamber.

To evaluate the bleaching efficacy and permeability of hydrogen peroxide (HP) in the pulp chamber of human teeth bleached with lower concentrations of carbamide peroxide gel (4%, 5% and 7% CP). Bleaching gels with lower concentrations were formulated and a commercial standard gel, 10% CP, was used as a reference. Fifty-six human premolars were randomly divided into four groups. Applications of the bleaching gel were made for 3h for 21 days. The bleaching efficacy was evaluated by digital spectrophotometry on 1, 7, 14 and 21 days, with analysis in the ∆Eab, ∆E00 and WID color spaces. The concentration of HP in the pulp chamber was measured in the same periods by UV-Vis spectrophotometry (µg/mL). Two-way repeated analysis of variance (ANOVA) examined bleaching efficacy and HP permeability, followed by Tukey's post-hoc test (α = 0.05). All groups showed significant color changes, with no statistical differences after the second and third week of bleaching (p > 0.05). The 'time' factor was statistically different (p < 0.05), increasing the bleaching efficacy throughout the treatment. The 4% CP group had lower HP levels in the pulp chamber (p < 0.05). The results seem promising, revealing that low concentration gels are as effective as 10% CP with the benefit of reducing the amount of HP in the pulp chamber. Low concentration 4% PC and 5% PC maintains bleaching efficacy, reduces the penetration of HP peroxide into the pulp chamber, and may reduce tooth sensitivity.

Genome-Wide Analysis of the Liriodendron chinense Hsf Gene Family under Abiotic Stress and Characterization of the LcHsfA2a Gene.

Heat shock factors (Hsfs) play a crucial role in plant defense processes. However, the distribution and functional characteristics of Hsf genes in the relict plant Liriodendron chinense are still unclear. In this study, a total of 19 LcHsfs were identified and divided into three separate subgroups, comprising 10 LcHsfA, 7 LcHsfB, and 2 LcHsfC genes, respectively, based on their phylogenetic tree and the presence/absence of conserved protein domains. Whole-genome duplication and segmental duplication led to an expansion of the LhHsf gene family. The promoters of LcHsf genes are enriched for different types of cis-acting elements, including hormone responsive and abiotic-stress-responsive elements. The expression of LcHsfA3, LcHsfA4b, LcHsfA5, LcHsfB1b, and LcHsfB2b increased significantly as a result of both cold and drought treatments. LcHsfA2a, LcHsfA2b, and LcHsfA7 act as important genes whose expression levels correlate strongly with the expression of the LcHsp70, LcHsp110, and LcAPX genes under heat stress. In addition, we found that transiently transformed 35S:LcHsfA2a seedlings showed significantly lower levels of hydrogen peroxide (H2O2) after heat stress and showed a stronger thermotolerance. This study sheds light on the possible functions of LcHsf genes under abiotic stress and identifies potentially useful genes to target for molecular breeding, in order to develop more stress-resistant varieties.

Triazine-Porphyrin-based aminal linked porous organic polymer as self-enhanced photo/enzyme synergistic antibacterial agent for wound healing

Here, a series of heteroatom-rich porous organic polymers (POPs) with aminal-linkage were facilely synthesized via Schiff base polycondensation reaction between the triazine-Porphyrin based monomer bearing eight amino groups and low cost monomer containing a single aldehyde moiety (Ferrocene, imidazole, 4-bromomethylbenzaldehyde, p-hydroxybenzaldehyde and 3,5-dimethoxybenzaldehyde). The combination of photoactive triazine-Porphyrin with redox-active Ferrocene endowed the self-enhanced photothermal, photodynamic, as well as peroxidase-like activity with the special POP (TPF-POP), which could function as a smart collaborative antimicrobial antibacterial platform. Notably, in vitro experiments verified TPF-POP could not only effectively excite the generation of reactive oxygen species (ROS) from the ambient oxygen and low levels of hydrogen peroxide (H2O2), but also transform the light energy into local heat exerting photothermal effects, presenting an effective bacterial killing effect towards both the S. aureus and E. coli at a low concentration (200 μg/mL). In vivo animal experiments demonstrated the wound coverage of TPF-POP-treated mice with back wound infection model was significantly reduced to 9.53 % within 9 days. These results confirmed TPF-POP with concurrently photocatalytic and enzymatic activity featured broad application prospect for promoting the repairing of infected wound. The as-proposed methods are available for the low-cost preparation of POPs with specific functions.

Melatonin enhances drought tolerance by affecting jasmonic acid and lignin biosynthesis in wheat (Triticum aestivum L.)

Drought severely affects the yield of wheat (Triticum aestivum L.), which is mainly grown in arid and semi-arid regions. Melatonin plays an important role in various types of stress resistance in plants, including drought resistance. However, the molecular mechanism through which melatonin affects drought tolerance remains largely unknown. In this study, we revealed that melatonin (100 μM) significantly improved drought resistance during the maturation stage of Chinese Spring, Shi4185, and Hanxuan10 varieties, but not Chang6878. Further physiological, transcriptomic, and proteomic data analysis at the wheat seedling stage revealed that melatonin increased jasmonic acid (JA) content, upregulating the expression of JA genes (LOX1.5 and LOX2.1) and two transcription factors (HY5 and MYB86) under drought conditions. It also upregulated genes related to lignin biosynthesis (4CL2, P5CS1, and CCR2) as well as starch and sucrose metabolism (PME53 and SUS4). Additionally, melatonin alleviated photosynthetic and cell membrane damage caused by drought stress through maintaining low levels of hydrogen peroxide. The current results elucidate melatonin-regulated pathways in wheat and provide evidence for using melatonin as a potential biostimulant to improve wheat drought resistance under field conditions in the future.

Elevated level of chilling tolerance in cucumber fruit was obtained by β-aminobutyric acid via the regulation of antioxidative response and metabolism of energy, proline and unsaturated fatty acid

• BABA treatment enhances the chilling tolerance in cucumber fruit. • BABA application improved the antioxidant capacity of harvested cucumber fruit. • BABA-treated fruit exhibited higher level of energy status. • BABA promoted proline accumulation and maintained higher level of UFA contents. This experimental study was conducted to investigate the effects of β-aminobutyric acid (BABA) on chilling injury in cold-stored cucumber fruit. Results showed that BABA decreased the development of chilling injury in cucumber fruit. BABA-treated fruit exhibited elevated antioxidant ability, indicated by high activities of superoxide dismutase (SOD) and catalase (CAT) and low levels of hydrogen peroxide and superoxide anion. BABA treatment maintained a high level of energy status by promoting the activities and genes expression of H + -ATPase, Ca 2+ -ATPase, succinate dehydrogenase (SDH) and cytochrome C oxidase (CCO). Increased enzymes activities and genes expression of Δ 1 -pyrroline-5-carboxylate synthase (PCS) and ornithine-δ-aminotransferase (OAT) and depressed enzyme activity and gene expression of proline dehydrogenase (PDH) in BABA-treated cucumber collectively promoted the accumulation of proline. Furthermore, BABA treatment delayed the decreasing trend of unsaturated fatty acid content in cucumber. Thus, BABA is effective in enhancing chilling tolerance in cucumber fruit possibly by improving the antioxidant ability and adjusting the metabolism of energy, proline and unsaturated fatty acids.

Overexpression of an NF-YC2 gene confers alkali tolerance to transgenic alfalfa (Medicago sativa L.).

Alkaline stress severely limits plant growth and yield worldwide. NF-YC transcription factors (TFs) respond to abiotic stress by activating gene expression. However, the biological function of NF-YC TFs in alfalfa (Medicago sativa L.) is not clear. In our study, an NF-YC2 gene was identified and transgenic plants were obtained by constructing overexpression vector and cotyledon node transformation system in alfalfa. The open reading frame of MsNF-YC2 is 879 bp with 32.4 kDa molecular mass. MsNF-YC2 showed tissue expression specificity and was induced by a variety of abiotic stresses including drought, salt, and alkali stress in alfalfa. Under alkali stress treatment, transgenic plants exhibited higher levels of antioxidant enzyme activities and proline (Pro), correlating with a lower levels of hydrogen peroxide (H2O2), superoxide anion (O2–) compared with wild-type (WT) plants. Transcriptomic results showed that overexpression of MsNF-YC2 regulated the expression of phytohormone signal transduction and photosynthesis-related genes under normal and alkaline stress treatments. These results suggest that the MsNF-YC2 gene plays crucial role enhance alkali adaptation abilities in alfalfa.

Quality of lipid-carotinoid concentrate from shrimps Palaemon adspersus Rathke, 1837

Introduction. The nutritional status of the population of Ukraine is characterized by imbalance, in particular in the composition of the lipid component. The human diet is deficient in polyunsaturated fatty acids, the source of which are marine fish and crustaceans. Problem. Ukraine has its own resources of Black Sea shrimp P. adpersus Rathke, 1837, the meat of which is in great demand, but inedible parts, as in most crustaceans, range from 39 to 50 %. That is why the search for technologies for the use of inedible parts of the body of shrimp is relevant. Lipid-carotenoid concentrate (LCC) was isolated from shrimp cephalopods to investigate its quality. The aim of the article is to evaluate the quality of lipid-carotenoid concentrate of Black Sea shrimp P. adspersus Rathke, 1837 by the method of creating a spectrum of flavor and a set of physicochemical parameters. Methods. The object of study – shrimp Palaemon adspersus Rathke, 1837, spring (May) and autumn (September) catch in 2020 near the northwestern Black Sea coast of Odessa region. Sensory characteristics of LCC were determined by the method of creating a flavor spectrum, physicochemical parameters – by standard methods, carotenoid content – by spectrophotometric method. Commercial krill fish oil was used as a control sample. Results. Descriptors have been developed to characterize the intensity of odor, taste and consistency of LCC. The method of creating the spectrum of flavor proved that the LCC isolated from the autumn period of shrimp fishing was characterized by the highest scores of all descriptors of odor, taste and consistency in comparison with the control and the LCC from the spring catch. Tasting assessment of LCC is consistent with a set of physico-chemical quality indicators (carotenoids, PUFA (iodine value), low levels of peroxide, acid and thiobarbitur numbers). Conclusions. Lipid-carotenoid concentrate from inedible parts of the body of the Black Sea shrimp Palaemon adspersus Rathke, 1837 in different periods of fishing is characterized by high tasting properties in terms of odor, taste and consistency, which are characteristic of lipids from crustaceans. Physico-chemical quality indicators indicate the high biological value of this product.

Effect of Trichoderma asperellum on Wheat Plants' Biochemical and Molecular Responses, and Yield under Different Water Stress Conditions.

Eight Trichoderma strains were evaluated for their potential to protect wheat seedlings against severe (no irrigation within two weeks) water stress (WS). Considering the plant fresh weight and phenotype, T. asperellum T140, which displays 1-aminocyclopropane-1-carboxylic acid deaminase activity and which is able to produce several phytohormones, was selected. The molecular and biochemical results obtained from 4-week-old wheat seedlings linked T140 application with a downregulation in the WS-response genes, a decrease in antioxidant activities, and a drop in the proline content, as well as low levels of hydrogen peroxide and malondialdehyde in response to severe WS. All of these responses are indicative of T140-primed seedlings having a higher tolerance to drought than those that are left untreated. A greenhouse assay performed under high nitrogen fertilization served to explore the long-term effects of T140 on wheat plants subjected to moderate (halved irrigation) WS. Even though all of the plants showed acclimation to moderate WS regardless of T140 application, there was a positive effect exerted by T. asperellum on the level of tolerance of the wheat plants to this stress. Strain T140 modulated the expression of a plant ABA-dependent WS marker and produced increased plant superoxide dismutase activity, which would explain the positive effect of Trichoderma on increasing crop yields under moderate WS conditions. The results demonstrate the effectiveness of T. asperellum T140 as a biostimulant for wheat plants under WS conditions, making them more tolerant to drought.

Chemical-functional composition of Terminalia catappa oils from different varieties

This study aimed to extract and physical-chemically characterize Terminalia catappa L. kernel oil from purple (CR) and yellow (CA) varieties. Physical-chemical parameters, composition of fatty acids, nutritional quality indices, bioactive compounds and antioxidant capacity of both oil varieties were evaluated according to the literature. Both oils presented low levels of acidity and peroxides, besides the predominance of unsaturated fatty acids, ~63% of oleic and ~26% of linoleic acids, which influenced its nutritional indices. The CR oil variety exhibited a higher content in anthocyanin (18.3 ± 1.5 mg·100 g-1), ascorbic acid (68.4 ± 2.02 mg·100 g-1) and total polyphenol contents (152.3 ± 2.4 mg GAE·g-1), and a good antioxidant activity (38.6 ± 2.2 μg TE·g-1) determined by TEAC assay, when compared to the CA oil (p &lt; 0.05). Therefore, the results confirm the importance of T. catappa as a lipid source for human consumption to be used in the development of food products.

Melatonin Improves the Resistance of Oxidative Stress-Induced Cellular Senescence in Osteoporotic Bone Marrow Mesenchymal Stem Cells.

Accumulation of senescent bone marrow-derived mesenchymal stem cells (BMMSCs) has led to an age-related bone loss. However, the role of stem cell senescence in estrogen deficiency-induced osteoporosis remains elusive. Though melatonin plays a vital role in bone metabolism regulation, the underlying mechanisms of melatonin-mediated antiosteoporosis are partially elucidated. Therefore, this study purposed to explore (1) whether estrogen deficiency causes cellular senescence of BMMSCs, and if so, (2) the potential of melatonin in preventing bone loss via senescence signaling inhibition. BMMSCs derived from ovariectomized (OVX) rats (OVX BMMSCs) showed an impaired osteogenic capacity, albeit having comparable levels of senescence biomarkers than the sham cells. When exposed to low levels of hydrogen peroxide (H2O2), OVX BMMSCs rapidly exhibited senescence-associated phenotypes such as the increased activity of senescence-associated β-galactosidase (SA-β-gal) and upregulation of cell cycle inhibitors. Notably, the in vitro treatment with melatonin hindered H2O2-induced senescence in OVX BMMSCs and restored their osteogenic capacity. Treatment with either SIRT1 inhibitor (sirtinol) or melatonin receptor antagonists (luzindole and 4-P-PDOT) eliminated melatonin protective effects, thus indicating its potential in preventing stem cell senescence via SIRT1 activation through the melatonin membrane receptors. Following in vivo intravenous administration with melatonin, it successfully protected the bone microstructure and preserved the antisenescence property of BMMSCs in OVX rats. Collectively, our findings demonstrated that melatonin protected against estrogen deficiency-related bone loss by improving the resistance of BMMSCs to cellular senescence. Therefore, melatonin-mediated antisenescence effect on stem cells provides vital information to facilitate the development of a novel and effective strategy for treating postmenopausal OP.

Ferrocene-appended anthraquinone and coumarin as redox-active cytotoxins.

Appending of ferrocene (Fc) to biologically-active organic backbones can generate novel multi-functional species for targeting bacteria and cancer. In this work Fc was linked to coumarin and anthraquinone with the goal of harnessing the redox-active Fc centre to generate new compounds that exhibit cytoxicity through the generation of toxic reactive oxygen species (ROS). A Cu(I)-catalyzed azide-alkyne cycloaddition "click" reaction was used to connect the organic and Fc components via a triazole linker. Cyclic voltammetry shows that the Fc potentials are suitable for oxidation by biological hydrogen peroxide to give reactive ferrocenium (Fc+) species, which can then generate hydroxyl radicals. The ability of the compounds to generate hydroxyl radicals in the presence of hydrogen peroxide was shown directly using EPR spin-trapping experiments. Furthermore, in vitro studies in MCF-7 breast cancer cells show significant increases in ROS following incubation with the Fc-functionalized compounds. Screening for antibacterial activity produced negative results for all of the Fc compounds, consitent with low levels of hydrogen peroxide typically found in bacteria. By contrast, Fc-coumarin showed cytotoxicity against A549 lung cancer and SKOV3 ovarian cancer cell lines, whereas the parent compound was inactive. This is consistent both with the cytoxic potential of the Fc group and the elevated hydrogen peroxide levels found in many cancers. Interestingly, the anthraquinone compounds showed the opposite effect with the parent compounds showing modest activity against A549 cells, but the Fc compounds being inactive. This demonstrates other potential negative impacts of including Fc, such as significantly increased lipophilicity.

Cattle manure compost and biochar supplementation improve growth of Onobrychis viciifolia in coal-mined spoils under water stress conditions

Surface mining is a critical anthropogenic activity that significantly alters the ecosystem, while the use of appropriate revegetation techniques can be considered an important and feasible strategy in the way to improve the ecosystem services of degraded land. In the present study, we carried out a pot experiment to investigate the effects of three different variables on morpho-physiological and biochemical parameters of Onobrychis viciifolia to assess the capability of this species to be used for restoration purposes. Specifically, the variables studied were: (a) water (W) regime, working at five values as regards field capacity (FC) (i.e., 80% FC = highest, 72% FC = high, 60% FC = moderate, 48% FC = low, and 40% FC = very-low dose); and (b) rates of cattle manure compost (CMC) and wood biochar (BC) (weight/weight ratio), working at five rates (i.e., 4.0% = highest, 3.2% = high, 2.0% = moderate, 0.8% = low, and 0% = either no-CMC or no-BC dose). In addition, soil physical-chemical properties and enzyme activities were also investigated at the end of the experimental period. It was found that morphological growth attributes such as plant height, maximum root length, and dry biomass significantly increased with W, CMC and BC applications. Compared to control, moderate-to-high W, CMC and BC doses (W80CMC2BC2) increased net photosynthesis rate (by 42%), stomatal conductance (by 50%), transpiration rate (by 29%), water use efficiency (by 10%), chlorophyll contents (by 73%), carotenoid content (by 81%), leaf relative water content (by 33%) and leaf membrane stability index (by 30%). Under low-W content, the application of CMC and BC enhanced osmotic adjustments by increasing the content of soluble sugar and the activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, decreasing the oxidative stress, as verified by low levels of hydrogen peroxide, superoxide anion, malondialdehyde and proline contents in leaf tissues. Moreover, application of W, CMC and BC significantly improved soil water holding capacity, available nitrogen, phosphorus and potassium, urease and catalase activities, which facilitate plant growth. These results would aid in designing an appropriate strategy for achieving a successful revegetation of O. viciifolia, providing optimum doses of W (64% field capacity), CMC (2.4%) and BC (1.7%), with the final aim of reaching ecological restoration in arid degraded lands.

Utilization of agroindustrial residue from passion fruit (Passiflora edulis) seeds as a source of fatty acids and bioactive substances

The aim of this study was to evaluate the properties of the oil extracted from passion fruit seeds (Passiflora edulis), an agroindustrial residue from juice industries, as a potential source of polyunsaturated fatty acids and bioactive substances. The oil presented low levels of free fatty acids and peroxides, as well a great amount of polyunsaturated fatty acids 58.4%, especially linoleic and linolenic acids, which indicates lower oxidation and good source of lipids. A relevant antioxidant activity as a result of a satisfactory content of bioactive substances, such as polyphenols, flavonoids, carotenoids and ascorbic acid, were determined in the passion fruit seed oil. The thermodegradation behavior of the oil suggested high thermal stability and the infrared spectroscopy exhibited high intensity bands between 1745 cm-1 to 1163 cm-1 correlated to the functional groups of fatty acids. Due to their bioactivity and presence of nutritious substances, the passion fruit seed oil may have beneficial properties to health and to extend the shelf-life foods products when present in dietary foods. Furthermore, the use of this by-product could reduce agroindustrial waste, expand and add value to the production chain when used as an industrial lipid matrix.

Artisanal oil obtained from insects’ larvae (Speciomerus ruficornis): fatty acids composition, physicochemical, nutritional and antioxidant properties for application in food

A novel insect oil (SRO) from Speciomerus ruficornis Germar larvae was obtained by artisanal non-solvent extraction and its physicochemical properties were investigated. The SRO presented low levels of acidity and peroxides, which is an indication of good quality and conservation standards. The composition of fatty acids showed major content of oleic (32.2%), lauric (21.3%), myristic (19.0%) and palmitic (17.6%) acids. The nutritional quality of its lipid fractions was evaluated through the atherogenicity (~ 3.1) and thrombogenicity (~ 2.2) indices, hypocholesterolemic/hypercholesterolemic (1.0) ratio, and calculated oxidability value (~ 0.82). SRO presented significant amounts of polyphenols, ~ 56 µg GAE mL−1 of oil, and a relevant antioxidant capacity, ~ 42 µg TE g−1 of oil, which could offer protection against oxidative agents. The FTIR spectra revealed high intensity bands ranging between 2924 and 2854 cm−1 and 1745 cm−1, related to the functional groups from long-branched fatty acids and triglycerides. The SRO presented great thermal behavior determined through thermogravimetric and differential scanning calorimetry analysis, which displayed peak temperature at ~ 388 °C and an endothermic peak around 10 °C related to crystallization of SFAs, respectively. The results of this study shows that SRO is an interesting solvent-free source of fatty acids with significant antioxidant capacity and good thermal behavior. Furthermore, different technologies to obtain SRO can be thought to increase its valuable application as a butter-like product in the food.

Chloroplast thylakoid ascorbate peroxidase PtotAPX plays a key role in chloroplast development by decreasing hydrogen peroxide in Populus tomentosa.

Chloroplast development is a complex process that is critical to the growth and development of plants. However, the detailed mechanism of chloroplast development in woody plants remains unclear. In this study, we showed that chloroplasts with elaborate thylakoids could develop from proplastids in the cells of calli derived from leaf tissues of Populus tomentosa upon exposure to light. Chloroplast development was confirmed at the molecular and cellular levels. Transcriptome analysis revealed that genes related to photoreceptors and photosynthesis were significantly up-regulated during chloroplast development in a time-dependent manner. In light-induced chloroplast development, a key process was the removal of hydrogen peroxide, in which thylakoid-localized PtotAPX played a major role; light-induced chloroplast development was enhanced in PtotAPX-overexpressing transgenic P. tomentosa callus with lower levels of hydrogen peroxide, but was suppressed in PtotAPX antisense transgenic callus with higher levels of hydrogen peroxide. Moreover, the suppression of light-induced chloroplast development in PtotAPX antisense transgenic callus was relieved by the exogenous reactive oxygen species scavenging agent N,N'-dimethylthiourea (DMTU). Based on these results, we propose that PtotAPX-mediated removal of reactive oxygen species plays a key role in chloroplast development from proplastids upon exposure to light in P. tomentosa.

Overexpression of rice OsWNK9 promotes arsenite tolerance in transgenic Arabidopsis plants

Protein kinases are involved in the transfer of phosphate group to serine, threonine, and tyrosine residues of a target protein. With No Lysine (WNK) kinase is a member of the serine/threonine protein kinase family, which has conserved catalytic lysine (K) residue in subdomain I instead of being in subdomain II.The WNKs family members in plants are stress inducible and have been validated for their role in abiotic stress tolerance. In the present study, we have characterized Arabidopsis overexpressed lines of OsWNK9 regulated by the constitutive promoter under arsenite stress. Moreover, we have performed In silico expression analysis of OsWNK9 under nutrient deficiency and heavy metal stress. Three independent transgenic Arabidopsis (OsWNK9-OX T11, T12,andT13) lines showed tolerance to arsenite stress compared to wild-type (WT) plants. Under arsenite stress, transgenic lines T11, T12 and T13 showed 56.46, 57.8 and 51.66 % increased biomass respectively, as compared to WT plants. All three ArabidopsisOsWNK9-OX lines exhibited higher proline content, increased antioxidant enzyme activities and lower hydrogen peroxide levels under arsenite stress. Besides, the total antioxidant capacity in terms of DPPH (2, 2-diphenyl-1-picrylhydrazyl) free radical scavenging percentage was increased by 8–15 % in three independent OsWNK9-OX lines compared with those of WT plants. Protein-protein interaction analysis of OsWNK9 predicted interaction partners with protein kinase and oxidative stress-responsive protein. Co-expression analysis of OsWNK9 in phosphate deficiency and arsenate stress condition predicted various proteins including membrane transporter and transcription factors. Taken together, our results, for the first time, provide evidence that OsWNK9 could positively mediate arsenite stress tolerance in plants.

Neuromodulatory effect of GnRH from coeliac ganglion on luteal regression in the late pregnant rat.

The GnRH/GnRH receptor system has been found in several extrapituitary tissues, although its physiological significance has not yet been well established. Taking into account that the peripheral neural system can act as a modulator of pregnancy corpus luteum, the objective was to physiologically investigate the presence of the GnRH system in coeliac ganglion (CG) and to analyse its possible involvement in luteal regression through the superior ovarian nerve (SON) at the end of pregnancy in the rat. The integrated ex vivo CG-SON-Ovary system of rats on day 21 of pregnancy was used. Cetrorelix (CTX), a GnRH receptor antagonist, was added into the ganglionic compartment while the control systems were untreated. Ganglionic GnRH release was detected under basal conditions. Then, the CTX addition in CG increased it, which would indicate the blockade of the receptor. In turn, CTX in CG caused an increase in ovarian progesterone release. Furthermore, the luteal cells showed an increase in the expression of Hsd3b1 and a decrease in the expression of Akr1c3 (progesterone synthesis and degradation enzymes, respectively), reduced TUNEL staining according to an increase in the antioxidant defence system activity and low lipid peroxide levels. The ovarian and ganglionic nitric oxide (NO) release increased, while the luteal nitrotyrosine content, measured as nitrosative stress marker, decreased. CTX in CG decreased the ovarian noradrenaline release. The present study provides evidence that GnRH from CG may trigger neuronal signals that promote the luteal regression in late pregnancy by affecting the release of NO and noradrenaline in the ovary.

Biochemical and physiological changes in maize plants supplied with silicon and infected by Exserohilum turcicum

AbstractNorthern leaf blight (NLB), caused by Exserohilum turcicum, is one of the most important diseases affecting maize production worldwide. The effect of silicon (Si) on maize resistance against NLB was investigated through an in‐depth analysis of physiological and biochemical changes (measurements of gas exchange and chlorophyll (Chl) a fluorescence parameters, activities of host defence enzymes and those involved in the antioxidative metabolism, and the determination of other metabolites) on plants non‐supplied (−Si) or supplied (+Si) with Si and inoculated with E. turcicum. Higher foliar Si concentration contributed to reducing the foliar NLB symptoms in +Si plants. Both antioxidant (ascorbate peroxidase, catalase, glutathione reductase and peroxidase) and host defence (chitinase, β‐1,3‐glucanase, polyphenoloxidase and phenylalanine ammonia‐lyase) enzymes had their activities greater for +Si plants compared to −Si plants. Lower levels of hydrogen peroxide and malondialdehyde were obtained for +Si plants in contrast to −Si plants. Net CO2 assimilation rate, stomatal conductance to water vapour, transpiration rate and internal CO2 concentration had their values significantly increased for +Si plants compared to −Si plants from 5 to 20 days after inoculation. The maximum quantum yield of photosystem II, effective quantum yield of the photosystem, quantum yield of regulated energy dissipation and quantum yield of non‐regulated energy dissipation were less impacted on the leaves of +Si plants compared to −Si plants. The Chl a concentration was kept higher for +Si plants than for −Si plants. Taken together, this study brings biochemical and physiological pieces of evidence that a more robust antioxidative metabolism, great activities of host defence‐related enzymes and the preservation of the photosynthetic machinery were all potentiated by Si contributing, therefore, for less NLB symptoms.

Identification and Functional Analysis of Two Purple Acid Phosphatases AtPAP17 and AtPAP26 Involved in Salt Tolerance in Arabidopsis thaliana Plant.

Tolerance to salinity is a complex genetic trait including numerous physiological processes, such as metabolic pathways and gene networks; thereby, identification of genes indirectly affecting, as well as those directly influencing, is of utmost importance. In this study, we identified and elucidated the functional characterization of AtPAP17 and AtPAP26 genes, as two novel purple acid phosphatases associated with high-salt tolerance in NaCl-stressed conditions. Here, the overexpression of both genes enhanced the expression level of AtSOS1, AtSOS2, AtSOS3, AtHKT1, AtVPV1, and AtNHX1 genes, involving in the K+/Na+ homeostasis pathway. The improved expression of the genes led to facilitating intracellular Na+ homeostasis and decreasing the ion-specific damages occurred in overexpressed genotypes (OEs). An increase in potassium content and K+/Na+ ratio was observed in OE17 and OE26 genotypes as well; however, lower content of sodium accumulated in these plants at 150 mM NaCl. The overexpression of these two genes resulted in the upregulation of the activity of the catalase, guaiacol peroxidase, and ascorbate peroxidase. Consequently, the overexpressed plants showed the lower levels of hydrogen peroxide where the lowest amount of lipid peroxidation occurred in these lines. Besides the oxidation resistance, the boost of the osmotic regulation through the increased proline and glycine-betaine coupled with a higher content of pigments and carbohydrates resulted in significantly enhancing biomass production and yield in the OEs under 150 mM NaCl. High-salt stress was also responsible for a sharp induction on the expression of both PAP17 and PAP26 genes. Our results support the hypothesis that these two phosphatases are involved in plant responses to salt stress by APase activity and/or non-APase activity thereof. The overexpression of PAP17 and PAP26 could result in increasing the intracellular APase activity in both OEs, which exhibited significant increases in the total phosphate and free Pi content compared to the wild-type plants. Opposite results witnessed in mutant genotypes (Mu17, Mu26, and DM), associating with the loss of AtPAP17 and AtPAP26 functions, clearly confirmed the role of these two genes in salt tolerance. Hence, these genes can be used as candidate genes in molecular breeding approaches to improve the salinity tolerance of crop plants.