Search

Leptographium qinlingensis is one of the major fungal associates of the Chinese white pine beetle (Dendroctonus armandi) and is an active participant in the large-scale death of Pinus armandi. Beetles and associated fungi have evolved efficient systems for overcoming the toxicity of host defense chemicals, which consist of a multitude of monoterpenes and diterpenes. As fungal cytochromes (CYPs) can detoxify and degrade various xenobiotic compounds, we identified 11 CYPs from L. qinlingensis to analyze their potential function in detoxifying or degrading host chemical defense. These 11 CYPs of L. qinlingensis belong to 6 clans and cluster into 3 clades, clade 2, clade 8 and clade 10, based on their phylogenetic relationships. Moreover, we also analyzed the transcript levels of CYPs following treatment with terpenes or expression in mycelia grown on terpenoids as a carbon source. The results in this paper showed that several CYPs were upregulated after treatment with terpenes or growth on terpenoids as the only carbon source. Our research provides some insight into the function of CYPs from bark beetle symbiotic fungi in the detoxification of pine defense compounds or their relationships with the utilization of terpenoids. [ABSTRACT FROM AUTHOR]

Lipopolysaccharides (LPSs) released by gut microbiota are correlated with the pathophysiology of osteoarthritis (OA). Exercise remodels the composition of gut microbiota. The present study investigated the hypothesis that wheel-running exercise prevents knee OA induced by high-fat diet (HFD) via reducing LPS from intestinal microorganisms. Male C57BL/6 J mice were treated with sedentary or wheel-running exercise, standard diet (13.5% kcal) or HFD (60% kcal), berberine or not according to their grouping. Knee OA severity, blood and synovial fluid LPS, cecal microbiota, and TLR4 and MMP-13 expression levels were determined. Our findings reveal that HFD treatment decreased gut microbial diversity. Increase in endotoxin-producing bacteria, decrease in gut barrier-protecting bacteria, high LPS levels in the blood and synovial fluid, high TLR4 and MMP-13 expression levels, and severe cartilage degeneration were observed. By contrast, voluntary wheel running caused high gut microbial diversity. The gut microbiota were reshaped, LPS levels in the blood and synovial fluid and TLR4 and MMP-13 expression levels were low, and cartilage degeneration was ameliorated. Berberine treatment reduced LPS levels in the samples, but decreased the diversity of intestinal flora with similar changes to that caused by HFD. In conclusion, unlike taking drugs, exercising can remodel gut microbial ecosystems, reduce the circulating levels of LPS, and thereby contribute to the relief of chronic inflammation and OA. Our findings showed that moderate exercise is a potential therapeutic approach for preventing and treating obesity-related OA. [ABSTRACT FROM AUTHOR]

Two contrasting rapeseed (Brassica napus L.) genotypes, Qinyou 8 (drought-sensitive) and Q2 (drought-tolerant), were studied under drought stress with or without pretreatment with melatonin to (i) explore whether melatonin enhances drought resistance by regulating root growth and (ii) determine the relationship between the belowground and aboveground responses to melatonin under drought stress. Results show that the light-saturated rate of photosynthesis (P n), stomatal conductance (g s), water use efficiency (WUE) and chlorophyll content were decreased by drought for Qinyou 8, whereas drought only decreased P n and chlorophyll content for Q2. Drought decreased actual photochemical efficiency in saturated light (F v '/F m '), actual photochemical efficiency (PhiPSⅡ), quenching of photochemical efficiency (qL) and electron transport rate (ETR) in Qinyou 8. However drought only decreased F v '/F m ' and qL in Q2. Drought increased malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2) contents in the roots of both genotypes. Melatonin had no significant additional effects on root guaiacol peroxidase (POD) and superoxide dismutase (SOD) activities, but enhanced root catalase (CAT) activity of droughted plants further. Melatonin promoted taproot and lateral root growth under drought stress. Melatonin also promoted stomatal opening resulting in enhanced photosynthesis in the two genotypes. The two mechanisms induced by melatonin synergistically enhance drought resistance of rapeseed as indicated by enhanced gas exchange parameters under melatonin pretreatment. The findings provide evidence for a physiological role of melatonin in improving drought resistance, especially in belowground parts. Image 1 • Melatonin promoted taproot and a lateral root growth and root CAT activity under drought. • Melatonin promoted stomata opening under drought. • The enhanced root growth by melatonin may contribute to preventing stomata from closing. [ABSTRACT FROM AUTHOR]

The association of polycyclic aromatic hydrocarbons (PAHs) with gestational diabetes mellitus (GDM) and gestational hypertension during pregnancy has not yet been established. To investigate the association between PAH exposure and GDM and gestational hypertension, we conducted a cross-sectional study of 4206 pregnant women from the Zunyi birth cohort in southwestern China. Gas chromatography/mass spectrometry was used to detect the urinary levels of 10 monohydroxylated PAHs (OH-PAHs). GDM and gestational hypertension were diagnosed and the relevant information was documented by specialist obstetricians and gynecologists. Logistic regression and restricted cubic spline regression were employed to investigate their single and nonlinear associations. Stratified analyses of pregnancy and body mass index data were conducted to determine their moderating effects on the abovementioned associations. Compared with the first quartile of urinary ∑OH-PAHs, the third or fourth quartile in all study participants was associated with an increased risk of GDM (quartile 3: odds ratio [ OR ] = 1.35, 95% confidence interval [CI]: 1.03–1.77) and gestational hypertension (quartile 3: OR = 1.88, 95% CI: 1.26–2.81; quartile 4: OR = 1.58, 95% CI: 1.04–2.39), respectively. Nonlinear associations of 1-OH-PYR with GDM (cutoff level: 0.02 μg/g creatinine [Cr]) and 1-OH-PHE with gestational hypertension (cutoff level: 0.06 μg/g Cr) were also observed. In pregnant women with overweight or obesity, 1-OH-PHE and 3-OH-PHE were more strongly associated with gestational hypertension. Our results indicate that exposure to PAH during pregnancy may significantly increase the maternal risks of GDM and gestational hypertension; however, this finding still needs to be confirmed through larger-scale prospective studies and biological evidence. [Display omitted] • PAHs are associated with an increased risk of GDM and gestational hypertension. • The Safety thresholds for PAHs in GDM and gestational hypertension are low. • Prepregnancy weight control might reduce the risk of gestational hypertension. • Prevention of PAH-associated risk of both conditions is critical in pregnant women. [ABSTRACT FROM AUTHOR]

Abstract To investigate whether nitrogen (N) load affects the ozone (O 3) stomatal flux-effect relationship for birch biomass, three-year old birch saplings were exposed to seven different O 3 profiles (24 h mean of 35–66 ppb) and four different N loads (10, 30, 50 and 70 kg ha−1 yr−1) in precision-controlled hemispherical glasshouses (solardomes) in 2012 and 2013. Stomatal conductance (g s) under optimal growth conditions was stimulated by enhanced N supply but was not significantly affected by enhanced O 3 exposure. Birch root, woody (stem + branches) and total biomass (root + woody) were not affected by the Phytotoxic Ozone Dose (POD 1 SPEC) after two seasons of O 3 exposure, and enhanced N supply stimulated biomass production independent of POD 1 SPEC (i.e. there were no POD 1 SPEC × N interactions). There was a strong linear relationship between the stem cross-sectional area and tree biomass at the end of the experiment, which was not affected by O 3 exposure or N load. Enhanced N supply stimulated the stem cross-sectional area at the end of season 2, but not at the end of season 1, which suggests a time lag before tree biomass responded to enhanced N supply. There was no significant effect of POD 1 SPEC on stem cross-sectional area after either the first or second growing season of the experiment. Contrasting results reported in the literature on the interactive impacts of O 3 and N load on tree physiology and growth are likely due to species-specific responses, different duration of the experiments and/or a limitation of the number of O 3 and N levels tested. Graphical abstract Unlabelled Image Highlights • O 3 flux-effect relationships investigated for birch at 7 O 3 profiles and 4 N loads • g s under optimal conditions was stimulated by N but not affected by O 3. • O 3 flux-effect relationships for biomass were not affected by N supply. • O 3 reduced stem cross-sectional area after the first season only. • N stimulation of stem cross-sectional area increased in the second season. [ABSTRACT FROM AUTHOR]

Abstract Apoplastic ascorbate (ASC apo) is an important contributor to the detoxification of ozone (O 3). The objective of the study is to explore whether ASC apo is stimulated by elevated O 3 concentrations. The detoxification of O 3 by ASC apo was quantified in tobacco (Nicotiana L), soybean (Glycine max (L.) Merr.) and poplar (Populus L), which were exposed to charcoal-filtered air (CF) and elevated O 3 treatments (E-O 3). ASC apo in the three species were significantly increased by E-O 3 compared with the values in the filtered treatment. For all three species, E-O 3 significantly increased the malondialdehyde (MDA) content and decreased light-saturated rate of photosynthesis (A sat), suggesting that high O 3 has induced injury/damage to plants. E-O 3 significantly increased redox state in the apoplast (redox state apo) for all species, whereas no effect on the apoplastic dehydroascorbate (DHA apo) was observed. In leaf tissues, E-O 3 significantly enhanced reduced-ascorbate (ASC) and total ascorbate (ASC+DHA) in soybean and poplar, but significantly reduced these in tobacco, indicating different antioxidative capacity to the high O 3 levels among the three species. Total antioxidant capacity in the apoplast (TAC apo) was significantly increased by E-O 3 in tobacco and poplar, but leaf tissue TAC was significantly enhanced only in tobacco. Leaf tissue superoxide anion (O 2 •-) in poplar and hydrogen peroxide (H 2 O 2) in tobacco and soybean were significantly increased by E-O 3. The diurnal variation of ASC apo , with maximum values occurring in the late morning and lower values experienced in the afternoon, appeared to play an important role in the harmful effects of O 3 on tobacco, soybean and poplar. Graphical abstract Image 1 Highlights • Apoplastic antioxidant was investigated in three species under two O 3 treatments. • Apoplastic reduced-ascorbate is induced by high instantaneous O 3 concentrations. • Apoplastic reduced-ascorbate displays a diurnal variation. • Increase of apoplastic ascorbate induced by O 3 is insufficient to protect plants from O 3. Apoplastic ascorbate was induced by high ozone. [ABSTRACT FROM AUTHOR]

Euwallacea interjectus (Curculionidae: Scolytinae) is an ambrosia beetle species in its early stages of research. Therefore, studying the related molecular mechanism associated with the development and egg laid is essential. Transcriptome sequencing was used in this study to compare the gene expression of the beetles at different developmental stages and female adults before and after oviposition. A total of 40,047 annotated unigenes were obtained. There were 4225 differentially expressed unigenes (DEUs) from larva to prepupa stage, 3651 DEUs between prepupa and pupa, 1675 DEUs generated from pupa to adult, and 4762 DEUs between females before and after oviposition. The most significant pathway differences between different development stages and before and after oviposition were selected through functional annotation of DEUs between different stages. Among them, there were many pathways related to protein metabolism including: neuroactive ligand-receptor interaction, endoplasmic reticulum and RNA transport. This study provides valuable information on the molecular regulation mechanism of development and the egg laid of E. interjectus. [Display omitted] • Transcriptome sequencing was used to compare the gene expression of E. interjectus development. • The most significant pathway differences between different development stages was related to protein metabolism. • The higher expression of Hsp90 in adult female E. interjectus before oviposition indicating a large amount of vitellogenin before oviposition. [ABSTRACT FROM AUTHOR]

To evaluate the ozone (O 3 ) sensitivity among peach tree ( Prunus persica ) cultivars widely planted in Beijing region and explore the possible eco-physiological response mechanisms, thirteen cultivars of peach seedlings were exposed to either charcoal-filtered air or elevated O 3 (E-O 3 , non-filtered ambient air plus 60 ppb) for one growing season in open-top chambers. Leaf structure, stomatal structure, gas exchange and chlorophyll a fluorescence, photosynthetic pigments, antioxidant defense system and lipid peroxidation were measured in three replicated chambers. Results showed that E-O 3 significantly reduced abaxial epidemis thickness, but no effects on the thicknesses of adaxial epidemis, palisade parenchyma and spongy parenchyma. Stomatal area, density and conductance were not significantly affected by E-O 3 . E-O 3 significantly accelerated leaf senescence, as indicated by increased lipid peroxidation and more declines in light-saturated photosynthetic rate and pigments contents. The reduced ascorbate content (ASC) was decreased but antioxidant enzyme activity (CAT, APX and SOD) and total antioxidant capacity (TAC) were significantly increased by E-O 3 among cultivars. The cultivars with visible symptoms also had more reductions in net photosynthetic rate than those without visible symptoms. Ozone sensitivity among cultivars was strongly linked to leaf mass per area (LMA), antioxidant enzymes activity e.g. SOD, APX rather than stomatal parameters (stomatal area, density and conductance) and ASC. Results could provide a theoretical basis for selecting and breeding the ozone-resistant cultivars of peach trees grown in high O 3 -polluted regions. [ABSTRACT FROM AUTHOR]

Bark beetles oxidize the defensive allelochemicals of their host trees both to detoxify them and convert them into components of their pheromone systems which were catalyzed by cytochrome P450 enzymes (CYPs) and occur in different tissues of the insect. We study P450 genes in the Chinese white pine beetle ( Dendroctonus armandi ), and some bio-information analysis was done for the full-length deduced amino acid sequences. The tissue specificity of these P450 genes was determined in three tissues (antenna, gut and reproductive organs). Differential expression of the P450 genes was observed between sexes, and within these significant differences exposed to stimuli (α-pinene (1:1 racemic mix), (S)-(−)-α-pinene, (S)-(−)-β-pinene, (+)-3-carene, (±)-limonene and turpentine oil) at 24 h. Increased expression of P450 genes suggested that they play a role in the detoxification of monoterpenes released by the host trees. The different transcript accumulation patterns of these bark beetle P450 genes provided insight into ecological interactions of D . armandi with its host pine. [ABSTRACT FROM AUTHOR]

Bark beetles oxidize the defensive allelochemicals from their host trees to both detoxify and convert these materials into components of their pheromone system. The ability of this insect to adapt to its chemical environment might be explained by the action of major detoxification enzymes such as cytochrome P450s (or CYPs). Sixty-four sequences coding for P450s were identified, and most of the transcripts were found to be expressed in the larvae, pupae and adults of Dendroctonus armandi . To gain information on how these genes help D. armandi overcome the host defense, differential transcript levels of the CYP genes were observed between sexes and within the sexes. Significant differences were observed among developmental stages, in feeding on the phloem of Pinus armandi and in exposure to stimuli ((±)-α-pinene, (S)-(−)-α-pinene, (S)-(−)-β-pinene, (+)-3-carene, (±)-limonene and turpentine oil) for 8 h. We investigated the effect of sex and generations on the survivorship of individual D. armandi that were exposed to host volatiles at concentrations comparable to constitutive and induced levels of defense using fumigant exposure to understand the ability of the beetles to tolerate host defensive chemicals. The differential transcript accumulation patterns of CYP genes of these bark beetle provided insight into the ecological interactions of D. armandi with its host pine. [ABSTRACT FROM AUTHOR]

We isolated two full-length cDNAs encoding 3-hydroxy-3-methyl-glutaryl coenzyme A synthase ( HMG-S ) and 3-hydroxy-3-methylglutaryl coenzyme A reductase ( HMG-R ) from the Chinese white pine beetle ( Dendroctonus armandi ), and carried out some bioinformatic analysis on the full-length nucleic acid sequences and deduced amino acid sequences. Differential expression of the DaHMG-S and DaHMG-R genes was observed between sexes (emerged adults), and within these significant differences among development stage, tissue distribution, fed on phloem of Pinus armandi and topically applied juvenile hormone (JH) III. Increase of DaHMG-S and DaHMG-R mRNA levels in males suggested that they may play a role in mevalonate pathway. Information from the present study might contribute to understanding the relationship between D. armandi and its semiochemical production. [ABSTRACT FROM AUTHOR]

The Chinese white pine beetle, Dendroctonus armandi Tsai and Li, is a serious native pest in the Qinling Mountains of China. exo -Bevicomin, as the main component of bark beetle pheromone, is released by the female D. armandi. In this paper, we identified two genes encoding, (Z)-6-nonen-2-ol dehydrogenase and CYP6CR, that are known to be involved in xo-brevicomin synthesis to improve the understanding of exo -brevicomin biosynthesis in the Chinese white pine beetle. The two protiens had high homology with their orthologs in the exo -brevicomin biosynthesis pathway from D. ponderosae. The expression profiles of CYP6CR12 and DaZnoDH in D. armandi females are closely correlated with exo -brevicomin biosynthesis. The expression levels of CYP6CR12 and DaZnoDH are also regulated by feeding behavior and juvenile hormone levels. Since they are also expressed in males, CYP6CR12 and DaZnoDH are not only important for exo -brevicomin biosynthesis that this might be potential role for the semichemical biosysthesis pathways. Unlabelled Image • The two genes were identified as CYP6CR12 and DaZnoDH from the Chinese white pine beetle. • The expression levels of CYP6CR12 and DaZnoDH are regulated by feeding behavior and juvenile hormone levels. • CYP6CR12 and DaZnoDH are important for exo-brevicomin biosynthesis, as well as other semiochemical biosynthesis. [ABSTRACT FROM AUTHOR]

Abstract We investigated the effects of elevated ozone (O 3) concentration on leaf nitrogen (N), a key determinant of plant photosynthesis, with two clones of poplar grown in open-top chambers. We focus on the difference between mass-based leaf N concentration (N mass) and area-based one (N area) in their responses to elevated O 3 , and the allocation of N to different leaf components: photosynthetic apparatus, cell walls, and others under elevated O 3 level. Our results showed that elevated O 3 significantly increased N mass , but reduced N area and leaf mass per area (LMA). The two clones showed no difference in N mass response to O 3 , but the more sensitive clone showed greater reduction of N area and LMA due to O 3. We also found positive relationships between N area and photosynthetic parameters, e.g. light-saturated photosynthetic rate (A sat). Furthermore, elevated O 3 significantly reduced photosynthetic N-use efficiency (PNUE) and leaf N allocation to photosynthetic components, while increasing N allocation to cell walls and other components. We concluded that plants invested more N in cell walls and other components to resist O 3 damages at the expense of photosynthetic N. The change of N allocation in plant leaves in response to elevated O 3 could have an impact on ecological processes, e.g. leaf litter decomposition. Graphical abstract Unlabelled Image Highlights • Ozone exposure-response relationships for leaf N concentration were established. • E-O 3 increased N mass of leaf, but reduced N area. • E-O 3 reduced leaf N allocation to photosynthesis (productivity). • E-O 3 increased leaf N allocation to cell walls (defense). [ABSTRACT FROM AUTHOR]

The sensitivity of Chinese soybean cultivars to ambient ozone (O 3 ) in the field is unknown, although soybean is a major staple food in China. Using ethylenediurea (EDU) as an O 3 protectant, we tested the gas exchange, pigments, antioxidants and biomass of 19 cultivars exposed to 28 ppm·hr AOT40 (accumulated O 3 over an hourly concentration threshold of 40 ppb) over the growing season at a field site in China. By comparing the average biomass with and without EDU, we estimated the cultivar-specific sensitivity to O 3 and ranked the cultivars from very tolerant (< 10% change) to highly sensitive (> 45% change), which helps in choosing the best-suited cultivars for local cultivation. Higher lipid peroxidation and activity of the ascorbate peroxidase enzyme were major responses to O 3 damage, which eventually translated into lower biomass production. The constitutional level of total ascorbate in the leaves was the most important parameter explaining O 3 sensitivity among these cultivars. Surprisingly, the role of stomatal conductance was insignificant. These results will guide future breeding efforts towards more O 3 -tolerant cultivars in China, while strategies for implementing control measures of regional O 3 pollution are being implemented. Overall, these results suggest that present ambient O 3 pollution is a serious concern for soybean in China, which highlights the urgent need for policy-making actions to protect this critical staple food. [ABSTRACT FROM AUTHOR]

Abstract Finite mesophyll conductance (g m) reduces the rate of CO 2 diffusion from the leaf intercellular space to the chloroplast and constitutes a major limitation of photosynthesis in trees. While it is well established that g m is decreased by stressors such as drought and high temperature, few studies have investigated if the phytotoxic air pollutant ozone (O 3) affects g m. We quantified the relative importance of three different types of limitations of photosynthesis in poplar trees exposed to elevated O 3 : decreases in stomatal conductance, g m and biochemical photosynthetic capacity. The O 3 -induced reductions in light-saturated net photosynthesis were linked to significant declines in g m and biochemical photosynthetic capacity (in particular carboxylation). There was no significant effect of O 3 on stomatal conductance. Of the O 3 -induced limitations on photosynthesis, g m limitation was by far the most important (−16%) while biochemical limitation (−8%) was rather small. Both limitations grew in magnitude over the study period and varied in response to leaf-specific O 3 exposure. Our findings suggest that declines in g m may play a key role in limiting photosynthesis of plants exposed to elevated O 3 , an effect hitherto overlooked. Graphical abstract Unlabelled Image Highlights • The photosynthetic response to elevated ozone was investigated in poplar trees. • Ozone exposure reduced leaf mesophyll conductance and carboxylation capacity. • Stomatal conductance was unaffected by elevated ozone. • The overall photosynthetic limitation increased with exposure time. • The main ozone-induced limitation to photosynthesis was reduced mesophyll conductance. [ABSTRACT FROM AUTHOR]