Cloning of CAT genes in Satsuma mandarin and their expression characteristics in response to environmental stress and arbuscular mycorrhizal fungi

KEY MESSAGE

CitCAT1 and CitCAT2 were cloned and highly expressed in mature leaves. High temperatures up-regulated CitCAT1 expression, while low temperatures and Diversispora versiformis up-regulated CitCAT2 expression, maintaining a low oxidative damage. Catalase (CAT), a tetrameric heme-containing enzyme, removes hydrogen peroxide (H2O2) to maintain low oxidative damage in plants exposed to environmental stress. This study aimed to clone CAT genes from Citrus sinensis cv. "Oita 4" and analyze their expression patterns in response to environmental stress, exogenous abscisic acid (ABA), and arbuscular mycorrhizal fungal inoculation. Two CAT genes, CitCAT1 (NCBI accession: PP067858) and CitCAT2 (NCBI accession: PP061394) were cloned, and the open reading frames of their proteins were 1479 bp and 1539 bp, respectively, each encoding 492 and 512 amino acids predicted to be localized in the peroxisome, with CitCAT1 being a stable hydrophilic protein and CitCAT2 being an unstable hydrophilic protein. The similarity of their amino acid sequences reached 83.24%, and the two genes were distantly related. Both genes were expressed in stems, leaves, flowers, and fruits, accompanied by the highest expression in mature leaves. In addition, CitCAT1 expression was mainly up-regulated by high temperatures (37 °C), exogenous ABA, and PEG stress within a short period of time, whereas CitCAT2 expression was up-regulated by exogenous ABA and low-temperature (4 °C) stress. Low temperatures (0 °C) for 12 h just up-regulated CitCAT2 expression in Diversispora versiformis-inoculated plants, and D. versiformis inoculation up-regulated CitCAT2 expression, along with lower hydrogen peroxide and malondialdehyde levels in mycorrhizal plants at low temperatures. It is concluded that CitCAT2 has an important role in resistance to low temperatures as well as mycorrhizal enhancement of host resistance to low temperatures.

Preliminary study of low-dose photodynamic therapy on the oxidative stress response of Cutibacterium acnes

PURPOSE

The objective of this study was to investigate the influence of photodynamic therapy (PDT) employing different, lower 5-aminolevulinic acid (ALA) dosages on the proliferative activity of Cutibacterium acnes (C. acnes).

METHODS

In this in vitro bacterial experiment, we examined the effects of PDT using different doses of ALA (0.05 mmol/L; 0.1 mmol/L; 0.5 mmol/L; 1.0 mmol/L; 2.5 mmol/L). To elucidate the underlying mechanisms, we assessed colony-forming units (CFUs), bacterial staining for live/dead, antioxidant enzyme activity, and gene expression of oxidative stress markers following treatment with different doses of ALA-PDT.

RESULTS

Our findings demonstrate that CFU, bacterial staining for live/dead, as well as the activity and gene expression of superoxide dismutase (SOD) and catalase (CAT), all exhibited significant increases when the ALA concentration was 0.1/0.5 mmol/L. However, both CFU and cell growth of C. acnes decreased when the ALA concentration reached 1.0 mmol/L.

CONCLUSION

Lower concentration of ALA-PDT (0.1/0.5 mmol/L) appears to promote the growth of C.acnes while higher doses (1.0 /2.5 mmol/L) are associated with eradication. The procedure is possibly mediated by the activation of antioxidant-related genes and enzyme expression in cells.

Effects of microplastics and cadmium on growth rate, photosynthetic pigment content and antioxidant enzymes of duckweed (Lemma minor)

Cadmium (Cd) and polyethylene (PE) seriously contaminate the aquatic environment and threaten human health. Many studies have reported the toxic effects of Cd and PE on plants, whereas few have reported the combined contamination of these two pollutants. In this study, duckweed (Lemma minor) was used as an indicator to explore the effect of PE microplastics (PE-MPs) at concentrations of 10, 50, 100, 200, and 500 mg/L on tolerance to 1 mg/L Cd. The results showed that different concentrations of PE-MPs inhibited the growth rate and chlorophyll content of duckweed to different degrees, both of which were minimal at 50 mg/L PE-MPs, 0.11 g/d, and 0.32 mg/g, respectively. The highest Cd enrichment (7.77 mg/kg) and bioaccumulation factors (94.22) of duckweed were detected when Cd was co-exposed with 50 mg/L of PE-MPs. Catalase and peroxidase activity first decreased and then increased with increasing PE-MPs concentrations, showing "hormesis effects", with minimum values of 11.47 U/g and 196.00 U/g, respectively. With increasing concentrations of PE-MPs, the effect on superoxide dismutase activity increased and then declined, peaking at 162.05 U/g, and displaying an "inverted V" trend. The amount of malondialdehyde rose with different PE-MPs concentrations. This research lay a foundation for using duckweed to purify water contaminated with MPs and heavy metals.

The microalgae-based wastewater treatment system coupled with Cerium: A potential way for energy saving and microalgae boost

The microalgae-based system attracts more attention in wastewater treatment for high quality effluent, low carbon emission, and resource utilization. Light is the key factor for algae growth, but the light masking in sewage will cause low efficiency of the system. This study designed laboratory scale experiments with Chlorella to investigate the influence of cerium on the nutrient removal by algae wastewater treatment system under different light intensities. The best removal rates of NH₄-N, TP, and COD were 72.43%, 88.87%, and 68.08% under 50 µmol/(m ²·s) light intensity and 1 mg/L Ce. Low concentration of Ce could activate protein synthesis, electron transfer, and antioxidase, while excessive Ce might cause toxicity which could be relieved by strong light for energy supply and further activating superoxide dismutase (SOD) and catalase (CAT). Comparing to other similar experiences, this system reached an equal or greater performance on nutrients removal with better efficiency in light utilization. It might provide a new idea for microalgae-based system development.

Zinc supplementation and light intensity affect 2-acetyl-1-pyrroline (2AP) formation in fragrant rice

BACKGROUND

Improving the yield and aroma content of fragrant rice is the focus of fragrant rice research. Light and Zinc (Zn) management generally cause regulations in the 2-acetyl-1-pyrroline (2AP) accumulation in fragrant rice. In addition, Zn promotes rice growth and improves rice yield, which has the potential to compensate for the negative impact of low light on fragrant rice yield. However, the potential of Zn to improve fragrant rice yield and 2AP content under shading conditions has not been verified.

METHODS

Field experiments were conducted in the rice season (May-September) in 2019 to 2021. Two light i.e., normal light (NL) and low light (LL) and four Zn levels i.e., 0 kg Zn ha^- 1 (N0), 1 kg Zn ha^- 1 (Zn1), 2 kg Zn ha^- 1(Zn2), and 3 kg Zn ha^- 1 (Zn3), which applied at booting stage was set up. The grain yield, 2AP contents, Zn content in polished rice, photosynthesis related indicators, MDA content, antioxidant enzyme activity and the biochemical parameters related to 2AP formation were investigated.

RESULTS

Shading reduced yield by 8.74% and increased 2AP content by 24.37%. In addition, shading reduced net photosynthetic rate (Pn), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and increased proline, γ-aminobutyric acid (GABA), and pyrroline-5-carboxylic acid (P5C), proline dehydrogenase (PDH), △1-pyrroline-5-carboxylic acid synthetase (P5CS), malondialdehyde (MDA). With increasing Zn application levels, yield, 2AP, Zn content in polished rice, Pn, proline, P5C, GABA, PDH, P5CS, SOD, CAT and POD increased, and MDA decreased. Significant Light and Zn interaction effect on 2AP content was detected, and both shading and increasing Zn application increased the 2AP content.

CONCLUSION

Shading can increase the 2AP content but reduce the yield of fragrant rice. Increasing Zn application under shading conditions can further promote the biosynthesis of 2AP, but the effect of improving yield is limited.

Analysis of nutrients in Apriona germari and treatment of diarrhea in mice fed with insect powder

The insect larvae of Apriona germari, Apriona swainsoni and other closely related species are related to the insects that bore through the stems of the Caesalpinia decapetala. Because of therich nutritional as well as medicinal value of edible A. germari, it is often used to nourish the body, enhance immunity, and to treat ailments such as diarrhea. The soluble protein content of A. germari was determined using Kjeldahl and Soxhlet extraction methods. The crude fat content and the content of various fatty acids was determined by the normalization method, normalization method refers to that after the fat in the sample is extracted by hydrolysis ether solution, it is saponified and methylated under alkaline conditions to generate fatty acids and methyl esters, which are analyzed by capillary column gas chromatography and quantitatively measured by area normalization method. Amino acid content determined using an amino acid analyzer after acid hydrolysis showed 17 kinds of amino acids. A diarrhea mouse model was established by injecting a suspension of Escherichia coli into the abdominal cavity of mice. The mice were then fed with A. germari fodders at dose concentrations of 12%, 8%, 4% and 0%. The number of E. coli was determined from the intestinal tracts of mice; the activities of antioxidant enzymes and digestive enzymes in the serum were determined. Eleven kinds of fatty acids were detected in A. germari; unsaturated fatty acids accounted for 71.87% of the total fatty acids. A. germari is an edible resource insect with high nutritional value. Mice fed with A. germari showed an increase in the activity of antioxidant enzymes and digestive enzymes in the serum, which helped in the effective inhibition and reduction in the total number of intestinal bacteria and E. coli. The results indicate that A. germari has high nutritional value; A. germari also has a certain therapeutic effect on diarrhea caused by E. coli in mice.

Increasing temperature during early spring increases winter wheat grain yield by advancing phenology and mitigating leaf senescence

High temperature usually reduces wheat yield, especially at critical growth stages, such as anthesis and grain filling. However, effects of increasing temperature during wintering period on winter wheat growth and development are rarely reported. Hence, this three-year field experiment evaluated how artificial warming during early spring (wintering period) affects winter wheat. The warming treatment (WT) advanced the wheat reviving, jointing, anthesis, and maturity stages, but the average temperature in each growing stage reduced, thus extending the duration of tillering, spike differentiation, and grain filling. Concurrently, the leaf area index and biomass accumulation were obviously increased. Additionally, WT showed a lower leaf senescence rate compared with that of control (CK). Also, the photosynthesis rate and SPAD of WT were increased relative to CK. WT increased superoxide dismutase and peroxidase activities, and reduced malondialdehyde content in flag leaf during the grain filling stage, suggesting WT during early spring could delay leaf senescence after anthesis, which contributed to a high filling rate and long filling duration. Correspondingly, the final spike number, kernel number, and kernel weight of WT were significantly increased compared with CK. In the three seasons, grain yield was increased by 18.2%-37.5% in WT compared with CK. Results of this study provided a new viewpoint that increasing temperature could shorten the wintering period but extend the effective growth phase, and increase grain yield in winter wheat.

Does the Anionic Surfactant Isopropylamine Dodecylbenzene Sulfonate Induce Hepatic Oxidative Stress and Impairment in Carassius auratus gibelio?

Isopropylamine dodecylbenzene sulfonate (IDS) is a new kind of anionic surfactant (ANS). To preliminarily evaluate the aquatic toxicity of IDS, this study took gibel carp (Carassius auratus gibelio) as the research object. The well-acclimatized fish were divided into six groups and exposed to 0 mg/L, 0.5 mg/L, 1.0 mg/L, 2.0 mg/L, 4.0 mg/L, or 8.0 mg/L of IDS for 7, 14, 21 or 28 days. Our results showed that the superoxide dismutase (SOD) activity and malondialdehyde (MDA) content of the liver were unaffected by IDS exposure, while glutathione peroxidase (GSH-Px) activity was significantly inhibited. Hepatic tissue exhibited pathological damage, characterized by nuclear migration and dissolution and cell boundary blurring. The results suggest that IDS does not cause oxidative stress in the liver, but cause hepatic histopathological damage. GSH-Px can be considered as a biomarker of IDS exposure in gibel carp.

Toxic effects of 2,4,4'- trichlorobiphenyl (PCB-28) on growth, photosynthesis characteristics and antioxidant defense system of Lemna minor L

Polychlorinated biphenyls (PCBs) are a common category of persistent man-made organic pollutants that are widespread in the ambient environment. Although Lemna minor L. is an extensively applied plant for aquatic remediation in ecotoxicology research worldwide, little is known regarding its responses to the potentially toxic effects of PCBs. For this study, a 14-day dissolved exposure was conducted to explore the effects of 2,4,4'- trichlorobiphenyl (PCB-28) on the growth, photosynthesis characteristics and antioxidant defense system of L. minor plants. We found that 100 and 200 μg/L of PCB-28 decreased the fresh weight, chlorophyll and protein content, and activities of superoxide dismutase, peroxidase, glutathione S-transferase, and nitroreductase, whereas plasma membrane permeability, and the malondialdehyde and reactive oxygen species concentrations were increased. However, it was observed that 5 and 20 μg/L of PCB-28 had no significant effects on these physiological indices. The ultra-structure of chloroplast demonstrated that 100 and 200 μg/L PCB-28 severely damaged the chloroplast structures. Moreover, correlation analysis revealed that the content of reactive oxygen species had negative correlations with the fresh weight, chlorophyll and protein content, as well as the activities of superoxide dismutase, peroxidase, glutathione S-transferase, and nitroreductase, but had positive correlations with the malondialdehyde content and plasma membrane permeability. This work provides valuable data toward elucidating the physiology and biochemistry of PCBs induced phytotoxicity.

Effects of Nrf2-Keap1 signaling pathway on antioxidant defense system and oxidative damage in the clams Ruditapes philippinarum exposure to PAHs

NF-E2-related factor 2 (Nrf2) is a master regulator of antioxidant defense system which can maintain the oxidation balance in the cell. In our previous study, we first cloned the Nrf2 gene in clams and preliminarily explored the role of the Nrf2 at the transcription level. In this study, RNA interference (RNAi) technology was used to interfere with the expression of Nrf2 after being exposed to benzo(a)pyrene (BaP) for 5 days to verify the role of Nrf2 in the antioxidant defense system. Besides, we examined the mRNA expression and enzyme activities of antioxidases and the oxidative damage. The positive correlations between the Nrf2 with the mRNA expression and the enzyme activities of antioxidases indicated that Nrf2 was required for the induction of these antioxidant genes. Additionally, the mRNA expression and the enzyme activities of the glutathione peroxidase (GPx) in the Nrf2-dsRNA group were significantly higher than those in the control groups on the fifth day, indicating that the GPx is more sensitive to oxidative stress. Moreover, the oxidative damage in the RpNrf2-dsRNA group was markedly increased than control groups, indicating that Nrf2 transcriptional regulation may play an essential role in defending against oxidative damage. This study provides a foundation for further research on the mechanism of detoxification and antioxidation of polycyclic aromatic hydrocarbons (PAHs) in the clams at the transcription level and the protein level.

Hydrogen sulfide regulates the activity of antioxidant enzymes through persulfidation and improves the resistance of tomato seedling to Copper Oxide nanoparticles (CuO NPs)-induced oxidative stress

Hydrogen sulfide (H₂S), a small gaseous signaling molecule, regulates antioxidase activity and improves plant tolerance to oxidative stress. The phytotoxic effect of Copper Oxide (II) nanoparticles (CuO NPs) is due to oxidative stress. Here, we show that H₂S-mediated persulfidation of antioxidase is essential for an effective stress response of tomato exposed to CuO NPs. The CuO NP-induced increase in hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) levels was significantly reduced by treatment with the H₂S donor NaHS. In vivo, NaHS increased superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POD) activities under CuO NP stress. In vitro, NaHS increased APX and POD activities but decreased catalase (CAT) activity. Persulfidation existed in recombinant SlCAT1, SlcAPX1 and SlPOD5 proteins. The persulfidatied cysteine (Cys) residues were verified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), revealing their position on the protein surface. Cys234 of SlCAT1 is located in the immune-responsive domain and close to the enzyme activity domain. Cys234 of SlcAPX1 and Cys 61 SlPOD5 are located in the enzyme activity domain. Persulfidation increased SlcAPX1 and SlPOD5 activities but decreased SlCAT1 activity. These data indicate that H₂S-mediated persulfidation posttranslationally regulates the activities of CAT, APX and POD, thereby enhancing the plant's response to oxidative stress. Additionally, this work provides an experimental approach for the study of persulfidation in plants.

Analysis of 2,4-epibrassinolide created an enhancement tolerance on Cd toxicity in Solanum nigrum L

Contamination of soils with cadmium (Cd) is a serious problem worldwide. Solanum nigrum L. is reported as a Cd hyperaccumulator, but its enrichment capacity is limited. 2,4-Epibrassinolide (2,4-EBL) plays important roles in plant response to various stresses. Little is known about its effect on Cd tolerance in S. nigrum. Current study was performed to demonstrate effects of 2,4-EBL on plant growth, photosynthesis activity, activities of antioxidants, and Cd concentration in plants by nutrient solution contaminated with Cd. Results revealed that S. nigrum exhibited toxicity to Cd stress, including reducing plant height, root length, and chlorophyll content and increasing malondialdehyde (MDA) content. Exogenous application of 2,4-EBL significantly enhanced the contents of proline and soluble sugar and decreased the MDA content. Meanwhile, the levels of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) markedly increased compared with the control. Interesting, 2,4-EBL promoted photosynthesis by increasing the chlorophyll content, Fv/Fm. And increase in chlorophyll content is caused by increased expression of synthetic genes and decreased expression of degraded genes. 2,4-EBL also decreased accumulation of Cd in S. nigrum compared with single Cd stress. According to the present results, 2,4-EBL can effectively be used to alleviate the damage of Cd stress in S. nigrum and probably in other solanaceae.

Interactions between decabromodiphenyl ether and lead in soil-plant system

Pot experiments were conducted under abiotic conditions to investigate the interactive influence of decabromodiphenyl ether (BDE-209) and lead (Pb) on the seed germination, germ length, root exudation and physiological characteristics of tall fescue (Festuca arundinaceae), and the uptake, accumulation of Pb and BDE-209 in the plant tissues. Results show that seed germination and germ length were impacted by Pb but less influenced by BDE-209. BDE-209 spiking (10 and 50 mg/L) could alleviate the toxicity of high Pb concentration on seed germination and growth. The chlorophyll content was significantly increased at 500 mg/kg Pb but declined at 2000 mg/kg Pb. Low-level Pb contamination (500 mg/kg) activated antioxidase activity; however, 2000 mg/kg Pb significantly reduced the antioxidase activity. Plant biomass slightly decreased at 500 mg/kg Pb but significantly declined at 2000 mg/kg Pb. The addition of a moderate dosage of BDE-209 (10-50 mg/kg) lessened Pb phytotoxicity, leading to improved plant growth relative to the case of Pb spiking alone. The exudate secretion was significantly enhanced by Pb addition, but BDE-209 spiking only caused slightly increased secretion. Pb could interfere with BDE-209 adsorption and translocation of tall fescue by affecting physiological behavior of the plant, but BDE-209 exhibited little influence on the Pb fate in the plant. Overall, BDE-209 had slight interference on the impact of Pb towards tall fescue. The results demonstrate the complex interactive effects of organic pollutants and heavy metals in the soil-plant system.

Effect of low-temperature conditioning combined with methyl jasmonate treatment on the chilling resistance of eggplant (Solanum melongena L.) fruit

Chilling injury (CI) can injure harvested eggplants and lead to a reduction in postharvest quality. The present study examined the effect of low-temperature conditioning (LTC) combined with a methyl jasmonate (MeJA) treatment on CI by analyzing the visual appearance and physiology of eggplants stored at 4 °C. Results indicated that treatment of eggplants with LTC + MeJA effectively maintained the visual quality of eggplants, inhibited a decline in chlorophyll and total phenolics, delayed the accumulation of malondialdehyde (MDA), decreased polyphenol oxidase (PPO) gene expression and enzyme activity, and enhanced the activity of the antioxidant enzymes, catalase (CAT) and peroxidase (POD), as well as the expression of their corresponding genes. Collectively, the data indicate that LTC combined with MeJA effectively improves the CI tolerance of postharvest eggplant fruit stored at 4 °C, by enhancing the activity and relative gene expression of antioxidant enzymes.

Dynamic responses of Haloxylon ammodendron to various degrees of simulated drought stress

Haloxylon ammodendron, a C4 perennial, succulent and xero-halophytic shrub, is highly resistant to harsh environments, therefore, exploring the stress resistance mechanism will be beneficial for the use of xerophytes to prevent desertification. To determine osmotic adjustment (OA) and antioxidase functions under simulated drought stress, 8-week-old seedlings were treated with sorbitol solutions to maintain osmotic potentials (Ψs) at a control and -0.5 and -1.0 MPa. Under -0.5 MPa osmotic stress, H. ammodendron stably maintained the water content of assimilating branches, a result that was not significantly different from the result of the control group. Moreover, the Ψs decreased significantly, which helped plants absorb water efficiently from the environment, as H. ammodendron accumulated massive osmotic regulators in its assimilating branches to adjust shoot Ψs. Specifically, the contribution of Na⁺ to shoot Ψs was up to 45%, and Na⁺ became the main osmotic regulator of OA. During the treatments, the content and contribution of K⁺ remained stable. However, the total contribution of three organic osmotic regulators (free proline, betaine and soluble sugar) was only 20%, and betaine was the main organic osmotic regulator, accounting for approximately 15% of the 20% contribution. Moreover, H. ammodendron seedlings presented strong antioxidases, especially when there was a high activity level of superoxide dismutase, and with an increase in treatment time and degree of osmotic stress, the activity of peroxidase and catalase increased significantly. Substantial accumulation of osmotic adjustment substances was an important strategy for H. ammodendron to cope with simulated drought stress, in particular, H. ammodendron absorbed much Na⁺ and transported Na⁺ into the assimilating branch for OA. The scavenging of reactive oxygen species by antioxidases was another adaptation strategy for H. ammodendron to adapt to simulated drought stress.

Sodium arsenite augments sensitivity of Echinococcus granulosus protoscoleces to albendazole

This study aimed to observe the effects of sodium arsenite (NaAsO₂) on apoptosis of Echinococcus granulosus protoscoleces induced by albendazole (ABZ), and to explore the potential mechanism of NaAsO₂. According to the following final concentrations, the experimental groups were divided into 10 μM NaAsO₂, 20 μM NaAsO₂, 80 μM ABZ, 10 μM NaAsO₂+80 μM ABZ, and 20 μM NaAsO₂+80 μM ABZ. Viability was detected with 0.1% eosin staining. The ultrastructural alterations were visualized by scanning electron microscopy. Caspase-3 activity was assessed with colorimetric assay. Meanwhile, ELISA or WST were applied to detect the activities of antioxidases in NaAsO₂ treatment groups. The maximum protoscolicidal effect was seen with the combination 20 μM NaAsO₂+80 μM ABZ. The ultrastructural damage detected after NaAsO₂+ABZ incubation were greater than those caused by ABZ alone and its primary damage site was the tegument of the parasite. The caspase-3 activity was clearly higher in protoscoleces treated with the combination of NaAsO₂+ABZ than when drugs were used separately. The activities of NQO-1, HO-1, GST, and SOD were significantly lower in protoscoleces incubated with NaAsO₂ than the untreated controls (P < 0.05). According to our results, ABZ could induce protoscoleces apoptosis, and NaAsO₂ could significantly augment sensitivity of protoscoleces to ABZ.

Toxic effects of copper sulfate on diploid and triploid fin cell lines in Misgurnus anguillicaudatus

The effects of different concentrations of copper sulfate on diploid and triploid fin cell lines (named DIMF and TRMF, respectively) in Misgurnus anguillicaudatus were studied. The LC₅₀ of copper sulfate estimated by an MTT assay was 268.39 in DIMF cells, and 311.54 μmol/L in TRMF cells, respectively. Activity of superoxide dismutase (SOD) in DIMF cells gradually increased as the concentration of copper sulfate increased (up to 200 μmol/L), and then gradually decreased. SOD activity in triploid loach fin cells, as well as glutathione peroxidase (GSH-Px) and glutathione-S-transferase (GST) activity in both diploid and triploid cells, decreased as the concentration of copper sulfate increased, which suggested that excessive copper exposure at the concentrations tested in this study was detrimental to anti-oxidative capability. In general, SOD, GST and GSH-Px activity was higher in triploid fin cells than in diploid cells. DNA breaks were observed by comet assays after 24 h exposure to 400 and 800 μM copper; DNA percent in the comet's tail was lower in TRMF than in DIMF. Ultrastructurally, there were no significant differences in the organelles of both cells, although a higher number of vesicles were observed in TRMF cells after copper exposure. Pathological changes induced by copper sulfate were similar in DIMF and TRMF cells, and were indicative of cell necrosis. Results above suggested that excessive copper sulfate exposure would lead to antioxidant enzymes activity reduction, along with antioxidant defenses disruption and superoxide radicals increasing, and then to DNA damage, ultrastructural changes and necrosis features in DIMF and TRMF M. anguillicaudatus fin cells. Triploid cell lines had higher resistance to copper than their diploid counterparts especially at higher concentrations of copper due to larger cells and higher intracellular content of detoxification enzymes to resist the toxicity of heavy metals.

Effects of exogenous 6-BA and NAA on growth and contents of medicinal ingredient of Phellodendron chinense seedlings

Using Phellodendron chinense seedlings as material, and treated with different concentrations of exogenous 6-Benzylaminopurine (6-BA) and α-naphthyacetic acid (NAA), then observed the growth status. Furthermore, we detected the contents of chlorophyll and soluble sugar, the activities of antioxidases by spectrophotometry, and determined the contents of secondary metabolite by high performance liquid chromatograph. The results showed that different concentrations of exogenous 6-BA increases the fresh weights and plant heights of Phellodendron chinense seedlings, and enhances the contents of chlorophyll and soluble sugar. NAA promoted growth, but deduced the contents of soluble sugar. Compared with control, culturing for 40 d, proper concentrations 6-BA enhanced the activity levels of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), proper concentrations NAA increased the activity levels of SOD and CAT, but decreased the levels of POD compared with CK. Suitable concentrations 6-BA enhanced contents of berberine, phellodendrine and palmatine in stems, proper concentrations NAA increased contents of berberine and phellodendrine, but deduced contents of palmatine compared with CK. Based on these results, we concluded that the exogenous 6-BA and NAA had key regulation on the growth and contents of medicinal ingredient of Phellodendron chinense seedlings.

Enhanced immobilization of U(VI) on Mucor circinelloides in presence of As(V): Batch and XAFS investigation

The combined pollution of radionuclides and heavy metals has been given rise to widespread concern during uranium mining. The influence of As(V) on U(VI) immobilization by Mucor circinelloides (M. circinelloides) was investigated using batch experiments. The activity of antioxidative enzymes and concentrations of thiol compounds and organic acid in M. circinelloides increased to respond to different U(VI) and As(V) stress. The morphological structure of M. circinelloides changed obviously under U(VI) and As(V) stress by SEM and TEM analysis. The results of XANES and EXAFS analysis showed that U(VI) was mainly reduced to nano-uraninite (nano-UO₂, 30.1%) in U₄₀₀, while only 9.7% of nano-UO₂ was observed in the presence of As(V) in U₄₀₀-As₄₀₀ due to the formation of uranyl arsenate precipitate (Trögerite, 48.6%). These observations will provide the fundamental data for fungal remediation of uranium and heavy metals in uranium-contaminated soils.

Sodium dithionite-enhanced quality of radix scutellariae through modification of secondary metabolism

Introduction:

The quality of radix scutellariae is particularly associated with environmental stresses, but detailed mechanisms remained unclear. Plant under unfavorable situation generates redundant reactive oxygen species (ROS), and ROS can modify the secondary metabolism. The varied quality of radix scutellariae could be explained by ROS.

Materials and Methods:

.004, 0.4, and 40 μmol/L of sodium dithionite (Na₂S₂O₄), a material producing ROS, were applied to Scutellaria baicalensis to mimic unfavorable situation. The relationship between ROS, antioxidant enzymes activity, and secondary metabolite was investigated.

Results:

ROS level fails to rise due to both the antioxidase and the secondary metabolites. The activities of both superoxide dismutase and catalase in the roots of S. baicalensis showed a moderately improvement, meanwhile the phenylalanine ammonia lyase was strongly expressed, and the biosynthesis of flavonoids was heavily elevated. Although the glycosides such as baicalin and wogonoside changed little, the aglycones with the highest effective, such as baicalein and wogonin, were increased by approximately 50%-100%.

Conclusion:

This is very valuable in insight into the stress physiology and provides a strong tool to enhance the quality of radix scutellariae.

Helium preconditioning protects against neonatal hypoxia-ischemia via nitric oxide mediated up-regulation of antioxidases in a rat model

This study aimed to investigate the role of nitric oxide (NO) in the neuroprotective effects of helium preconditioning (He-PC) in a neonatal hypoxia/ischemia (HI) rat model. Seven-day old rat pups were divided into normal control group, He-PC group, HI group, He-PC+HI group, L-NAME+HI group and L-NAME+He-PC+HI group. HI was induced by exposure to 80% oxygen for 90 min. He-PC was conducted with 70% helium-30% oxygen for three 5-min periods. Three hours after He-PC, animals in control group and He-PC group were sacrificed, and the brain was collected for the detection of NO content. At 24h after HI, animals in control group, HI group, He-PC+HI group, and L-NAME+He-PC+HI group were sacrificed, and the brain was collected for detection of infarct ratio, antioxidases (SOD, HO-1 and Nrf2), DNA binding activity of Nrf2 and TUNEL staining. Three weeks later, the neurological function and brain atrophy were determined. Results showed pretreatment with L-NAME alone failed to exert protective effect on HI. He-PC significantly increased NO content, reduced the brain infarct area, increased anti-oxidases expression and DNA binding activity of Nrf2, decreased the apoptotic cells, and improved the neurological function and brain atrophy. In addition, this protection was markedly inhibited by L-NAME (a non-selective NOS inhibitor). These findings suggest that the He-PC may induce NO production to activate Nrf2, exerting neuroprotective effect on neonatal HI.

Toxicity of a neonicotinoid insecticide, guadipyr, in earthworm (Eisenia fetida)

Neonicotinoid insecticides are new class of pesticides and it is very meaningful to evaluate the toxicity of guadipyr to earthworm (Eisenia fetida). In the present study, effects of guadipyr on reproduction, growth, catalase(CAT), superoxide dismutase (SOD), acetylcholinesterase (AChE) and DNA damage in earthworm were assessed using an artificial soil medium. Guadipyr showed low toxicity to earthworms and did not elicit an effect on earthworm reproduction or growth in artificial soils at concentrations <100mg/kg. However, after exposure to guadipyr, the activity of SOD and CAT in earthworm increased and then decreased to control level. AChE activity decreased at day 3 at 50 and 100mg/kg and then increased to control level. Our data indicate that guadipyr did not induce DNA damage in earthworms at concentration of <100mg/kg.

Time-dependent stimulations of 1-alkyl-3-methylimidazolium chloride on redox reactants and antioxidases in Vibrio qinghaiensis sp.-Q67

Previously, 1-alkyl-3-methylimidazolium chloride ([Cnmim]Cl) showed time-dependent hormesis on Vibrio qinghaiensis sp.-Q67 (Q67). Yet, the underlying mechanism remained unexplored. Currently, the biochemical effects of [Cnmim]Cl in Q67 were studied by ELISA kits. [C2mim]Cl firstly inhibited (0.25h) and then stimulated flavin mononucleotide (FMN), nicotinamide adenine dinucleotide (NADH), superoxide dismutase (SOD) and catalase (CAT). The stimulations of [C2mim]Cl firstly increased (from 2 to 8h) and then decreased (from 8 to 12h). Positive correlations among FMN, NADH and luminescence indicated the essential role of NADH:FMN reaction in the light production system, and those among SOD, CAT and luminescence indicated a time-dependent generation of reactive oxygen species (ROS). Notably, the maximum stimulations of [C2mim]Cl on FMN and NADH were at 4h, and the stimulations were 184% and 186% higher than the control, respectively, earlier and stronger than those on luminescence. The FMN/NADH ratios were 3.7 at 0.25h and decreased to 1.15 at 12h, without a concentration-dependence. The maximum stimulations of [C4mim]Cl were at 8h and the stimulations were 48.8% and 47.9% higher than the control for FMN and NADH, respectively. Meanwhile, the inductions of [C4mim]Cl on SOD and CAT continuously increased from 2 to 12h. Thus, [C4mim]Cl showed lower stimulation levels and different time-dependences. [Cnmim]Cl (n=6, 8, 12) did not show significant biochemical effects. Therefore, the biochemical effects of [Cnmim]Cl depended on both time and side chain. Our findings demonstrated a common pattern, FMN/NADH stimulations and antioxidant inductions, in the hormesis of ILs, and also called for future mechanisms studies.

The physiological response of Artemisia annua L. to salt stress and salicylic acid treatment

Salinity has a great influence on plant growth and distribution. A few existing reports on Artemisia annua L. response to salinity are concentrated on plant growth and artemisinin content; the physiological response and salt damage mitigation are yet to be understood. In this study, the physiological response of varying salt stresses (50, 100, 200, 300, or 400 mM NaCl) on A. annua L. and the effect of exogenous salicylic acid (0.05 or 0.1 mM) at 300-mM salt stress were investigated. Plant growth, antioxidant enzyme activity, proline, and mineral element level were determined. In general, increasing salt concentration significantly reduced plant growth. Superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were stimulated by salt treatment to a higher enzyme activity in treated plants than those in untreated plants. Content of proline had a visible range of increment in the salt-treated plants. Distribution of mineral elements was in inconformity: Na(+) and Ca(2+) were mainly accumulated in the roots; K(+) and Mg(2+) were concentrated in leaves and stems, respectively. Alleviation of growth arrest was observed with exogenous applications of salicylic acid (SA) under salt stress conditions. The activity of SOD and POD was notably enhanced by SA, but the CAT action was suppressed. While exogenous SA had no discernible effect on proline content, it effectively inhibited excessive Na(+) absorption and promoted Mg(2+) absorption. Ca(2+) and K(+) contents showed a slight reduction when supplemented with SA. Overall, the positive effect of SA towards resistance to the salinity of A. annua will provide some practical basis for A. annua cultivation.