Structural and functional dissection of differentially expressed tomato WRKY transcripts in host defense response against the vascular wilt pathogen (Fusarium oxysporum f. sp. lycopersici).

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Aamir, Mohd; Singh, Vinay Kumar; Dubey, Manish Kumar; Kashyap, Sarvesh Pratap; Zehra, Andleeb; Upadhyay, Ram Sanmukh; Singh, Surendra

2018-01-01

The WRKY transcription factors have indispensable role in plant growth, development and defense responses. The differential expression of WRKY genes following the stress conditions has been well demonstrated. We investigated the temporal and tissue-specific (root and leaf tissues) differential expression of plant defense-related WRKY genes, following the infection of Fusarium oxysporum f. sp. lycopersici (Fol) in tomato. The genome-wide computational analysis revealed that during the Fol infection in tomato, 16 different members of WRKY gene superfamily were found to be involved, of which only three WRKYs (SolyWRKY4, SolyWRKY33, and SolyWRKY37) were shown to have clear-cut differential gene expression. The quantitative real time PCR (qRT-PCR) studies revealed different gene expression profile changes in tomato root and leaf tissues. In root tissues, infected with Fol, an increased expression for SolyWRKY33 (2.76 fold) followed by SolyWRKY37 (1.93 fold) gene was found at 24 hrs which further increased at 48 hrs (5.0 fold). In contrast, the leaf tissues, the expression was more pronounced at an earlier stage of infection (24 hrs). However, in both cases, we found repression of SolyWRKY4 gene, which further decreased at an increased time interval. The biochemical defense programming against Fol pathogenesis was characterized by the highest accumulation of H2O2 (at 48 hrs) and enhanced lignification. The functional diversity across the characterized WRKYs was explored through motif scanning using MEME suite, and the WRKYs specific gene regulation was assessed through the DNA protein docking studies The functional WRKY domain modeled had β sheets like topology with coil and turns. The DNA-protein interaction results revealed the importance of core residues (Tyr, Arg, and Lys) in a feasible WRKY-W-box DNA interaction. The protein interaction network analysis revealed that the SolyWRKY33 could interact with other proteins, such as mitogen-activated protein kinase 5 (MAPK

Interplay of Pathogen-Induced Defense Responses and Symbiotic Establishment in Medicago truncatula

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Tao Chen

2017-05-01

Full Text Available Suppression of host innate immunity appears to be required for the establishment of symbiosis between rhizobia and host plants. In this study, we established a system that included a host plant, a bacterial pathogen and a symbiotic rhizobium to study the role of innate immunity during symbiotic interactions. A pathogenic bacterium, Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000, was shown to cause chlorosis in Medicago truncatula A17. Sinorhizobium meliloti strain Sm2011 (Sm2011 and Pst DC3000 strain alone induced similar defense responses in M. truncatula. However, when co-inoculated, Sm2011 specifically suppressed the defense responses induced by Pst DC3000, such as MAPK activation and ROS production. Inoculation with Sm2011 suppressed the transcription of defense-related genes triggered by Pst DC3000 infection, including the receptor of bacterial flagellin (FLS2, pathogenesis-related protein 10 (PR10, and the transcription factor WRKY33. Interestingly, inoculation with Pst DC3000 specifically inhibited the expression of the symbiosis marker genes nodule inception and nodulation pectate lyase and reduced the numbers of infection threads and nodules on M. truncatula A17 roots, indicating that Pst DC3000 inhibits the establishment of symbiosis in M. truncatula. In addition, defense-related genes, such as MAPK3/6, RbohC, and WRKY33, exhibited a transient increase in their expression in the early stage of symbiosis with Sm2011, but the expression dropped down to normal levels at later symbiotic stages. Our results suggest that plant innate immunity plays an antagonistic role in symbiosis by directly reducing the numbers of infection threads and nodules.

Roles of arabidopsis WRKY18, WRKY40 and WRKY60 transcription factors in plant responses to abscisic acid and abiotic stress

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Chen Zhixiang; Xiao Yong; Shi Junwei; Lai Zhibing; Chen Han; Xu Xinping

2010-01-01

Abstract Background WRKY transcription factors are involved in plant responses to both biotic and abiotic stresses. Arabidopsis WRKY18, WRKY40, and WRKY60 transcription factors interact both physically and functionally in plant defense responses. However, their role in plant abiotic stress response has not been directly analyzed. Results We report that the three WRKYs are involved in plant responses to abscisic acid (ABA) and abiotic stress. Through analysis of single, double, and triple muta...

Transcriptional regulation of the grape cytochrome P450 monooxygenase gene CYP736B expression in response to Xylella fastidiosa infection

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Walker M Andrew

2010-07-01

Full Text Available Abstract Background Plant cytochrome P450 monooxygenases (CYP mediate synthesis and metabolism of many physiologically important primary and secondary compounds that are related to plant defense against a range of pathogenic microbes and insects. To determine if cytochrome P450 monooxygenases are involved in defense response to Xylella fastidiosa (Xf infection, we investigated expression and regulatory mechanisms of the cytochrome P450 monooxygenase CYP736B gene in both disease resistant and susceptible grapevines. Results Cloning of genomic DNA and cDNA revealed that the CYP736B gene was composed of two exons and one intron with GT as a donor site and AG as an acceptor site. CYP736B transcript was up-regulated in PD-resistant plants and down-regulated in PD-susceptible plants 6 weeks after Xf inoculation. However, CYP736B expression was very low in stem tissues at all evaluated time points. 5'RACE and 3'RACE sequence analyses revealed that there were three candidate transcription start sites (TSS in the upstream region and three candidate polyadenylation (PolyA sites in the downstream region of CYP736B. Usage frequencies of each transcription initiation site and each polyadenylation site varied depending on plant genotype, developmental stage, tissue, and treatment. These results demonstrate that expression of CYP736B is regulated developmentally and in response to Xf infection at both transcriptional and post-transcriptional levels. Multiple transcription start and polyadenylation sites contribute to regulation of CYP736B expression. Conclusions This report provides evidence that the cytochrome P450 monooxygenase CYP736B gene is involved in defense response at a specific stage of Xf infection in grapevines; multiple transcription initiation and polyadenylation sites exist for CYP736B in grapevine; and coordinative and selective use of transcription initiation and polyadenylation sites play an important role in regulation of CYP736B expression

Response of sunflower (Helianthus annuus L.) leaf surface defenses to exogenous methyl jasmonate.

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Rowe, Heather C; Ro, Dae-kyun; Rieseberg, Loren H

2012-01-01

Helianthus annuus, the common sunflower, produces a complex array of secondary compounds that are secreted into glandular trichomes, specialized structures found on leaf surfaces and anther appendages of flowers. The primary components of these trichome secretions are sesquiterpene lactones (STL), a diverse class of compounds produced abundantly by the plant family Compositae and believed to contribute to plant defense against herbivory. We treated wild and cultivated H. annuus accessions with exogenous methyl jasmonate, a plant hormone that mediates plant defense against insect herbivores and certain classes of fungal pathogens. The wild sunflower produced a higher density of glandular trichomes on its leaves than the cultivar. Comparison of the profiles of glandular trichome extracts obtained by liquid chromatography-mass spectroscopy (LC-MS) showed that wild and cultivated H. annuus were qualitatively similar in surface chemistry, although differing in the relative size and proportion of various compounds detected. Despite observing consistent transcriptional responses to methyl jasmonate treatment, we detected no significant effect on glandular trichome density or LC-MS profile in cultivated or wild sunflower, with wild sunflower exhibiting a declining trend in overall STL production and foliar glandular trichome density of jasmonate-treated plants. These results suggest that glandular trichomes and associated compounds may act as constitutive defenses or require greater levels of stimulus for induction than the observed transcriptional responses to exogenous jasmonate. Reduced defense investment in domesticated lines is consistent with predicted tradeoffs caused by selection for increased yield; future research will focus on the development of genetic resources to explicitly test the ecological roles of glandular trichomes and associated effects on plant growth and fitness.

GBF1 differentially regulates CAT2 and PAD4 transcription to promote pathogen defense in Arabidopsis thaliana.

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Giri, Mrunmay K; Singh, Nidhi; Banday, Zeeshan Z; Singh, Vijayata; Ram, Hathi; Singh, Deepjyoti; Chattopadhyay, Sudip; Nandi, Ashis K

2017-09-01

G-BOX BINDING FACTOR 1 (GBF1) influences light-regulated seedling development in Arabidopsis, and inhibits CATALASE 2 (CAT2) expression during senescence. CAT2 functions as a scavenger of hydrogen peroxide. The role of GBF1 in the defense response is not known. We report here that GBF1 positively influences the defense against virulent and avirulent strains of Pseudomonas syringae. The gbf1 mutants are susceptible, whereas GBF1 over-expresser transgenic plants are resistant to bacterial pathogens. GBF1 negatively regulates pathogen-induced CAT2 expression and thereby positively regulates the hypersensitive response. In addition to CAT2 promoter, GBF1 binds to the G-box-like element present in the intron of PHYTOALEXIN DEFICIENT 4 (PAD4). This association of GBF1 with PAD4 intron is enhanced upon pathogenesis. GBF1 positively regulates PAD4 transcription in an intron-dependent manner. GBF1-mediated positive regulation of PAD4 expression is also evident in gbf1 mutant and GBF1 over-expression lines. Similar to pad4 mutants, pathogen-induced camalexin and salicylic acid (SA) accumulation, and expression of SA-inducible PATHOGENESIS RELATED1 (PR1) gene are compromised in the gbf1 mutant. Exogenous application of SA rescues the loss-of-defense phenotypes of gbf1 mutant. Thus, altogether, our results demonstrate that GBF1 is an important component of the plant defense response that functions upstream of SA accumulation and, by oppositely regulating CAT2 and PAD4, promotes disease resistance in Arabidopsis. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Transcriptomics of the rice blast fungus Magnaporthe oryzae in response to the bacterial antagonist Lysobacter enzymogenes reveals candidate fungal defense response genes.

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Sandra M Mathioni

Full Text Available Plants and animals have evolved a first line of defense response to pathogens called innate or basal immunity. While basal defenses in these organisms are well studied, there is almost a complete lack of understanding of such systems in fungal species, and more specifically, how they are able to detect and mount a defense response upon pathogen attack. Hence, the goal of the present study was to understand how fungi respond to biotic stress by assessing the transcriptional profile of the rice blast pathogen, Magnaporthe oryzae, when challenged with the bacterial antagonist Lysobacter enzymogenes. Based on microscopic observations of interactions between M. oryzae and wild-type L. enzymogenes strain C3, we selected early and intermediate stages represented by time-points of 3 and 9 hours post-inoculation, respectively, to evaluate the fungal transcriptome using RNA-seq. For comparative purposes, we also challenged the fungus with L. enzymogenes mutant strain DCA, previously demonstrated to be devoid of antifungal activity. A comparison of transcriptional data from fungal interactions with the wild-type bacterial strain C3 and the mutant strain DCA revealed 463 fungal genes that were down-regulated during attack by C3; of these genes, 100 were also found to be up-regulated during the interaction with DCA. Functional categorization of genes in this suite included those with roles in carbohydrate metabolism, cellular transport and stress response. One gene in this suite belongs to the CFEM-domain class of fungal proteins. Another CFEM class protein called PTH11 has been previously characterized, and we found that a deletion in this gene caused advanced lesion development by C3 compared to its growth on the wild-type fungus. We discuss the characterization of this suite of 100 genes with respect to their role in the fungal defense response.

Phytohormone and Putative Defense Gene Expression Differentiates the Response of ‘Hayward’ Kiwifruit to Psa and Pfm Infections

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Kirstin V. Wurms

2017-08-01

Full Text Available Pseudomonas syringae pv. actinidiae (Psa and Pseudomonas syringae pv. actinidifoliorum (Pfm are closely related pathovars infecting kiwifruit, but Psa is considered one of the most important global pathogens, whereas Pfm is not. In this study of Actinidia deliciosa ‘Hayward’ responses to the two pathovars, the objective was to test whether differences in plant defense responses mounted against the two pathovars correlated with the contrasting severity of the symptoms caused by them. Results showed that Psa infections were always more severe than Pfm infections, and were associated with highly localized, differential expression of phytohormones and putative defense gene transcripts in stem tissue closest to the inoculation site. Phytohormone concentrations of jasmonic acid (JA, jasmonate isoleucine (JA-Ile, salicylic acid (SA and abscisic acid were always greater in stem tissue than in leaves, and leaf phytohormones were not affected by pathogen inoculation. Pfm inoculation induced a threefold increase in SA in stems relative to Psa inoculation, and a smaller 1.6-fold induction of JA. Transcript expression showed no effect of inoculation in leaves, but Pfm inoculation resulted in the greatest elevation of the SA marker genes, PR1 and glucan endo-1,3-beta-glucosidase (β-1,3-glucosidase (32- and 25-fold increases, respectively in stem tissue surrounding the inoculation site. Pfm inoculation also produced a stronger response than Psa inoculation in localized stem tissue for the SA marker gene PR6, jasmonoyl-isoleucine-12-hydrolase (JIH1, which acts as a negative marker of the JA pathway, and APETALA2/Ethylene response factor 2 transcription factor (AP2 ERF2, which is involved in JA/SA crosstalk. WRKY40 transcription factor (a SA marker was induced equally in stems by wounding (mock inoculation and pathovar inoculation. Taken together, these results suggest that the host appears to mount a stronger, localized, SA-based defense response to Pfm

PAMP-induced defense responses in potato require both salicylic acid and jasmonic acid.

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Halim, Vincentius A; Altmann, Simone; Ellinger, Dorothea; Eschen-Lippold, Lennart; Miersch, Otto; Scheel, Dierk; Rosahl, Sabine

2009-01-01

To elucidate the molecular mechanisms underlying pathogen-associated molecular pattern (PAMP)-induced defense responses in potato (Solanum tuberosum), the role of the signaling compounds salicylic acid (SA) and jasmonic acid (JA) was analyzed. Pep-13, a PAMP from Phytophthora, induces the accumulation of SA, JA and hydrogen peroxide, as well as the activation of defense genes and hypersensitive-like cell death. We have previously shown that SA is required for Pep-13-induced defense responses. To assess the importance of JA, RNA interference constructs targeted at the JA biosynthetic genes, allene oxide cyclase and 12-oxophytodienoic acid reductase, were expressed in transgenic potato plants. In addition, expression of the F-box protein COI1 was reduced by RNA interference. Plants expressing the RNA interference constructs failed to accumulate the respective transcripts in response to wounding or Pep-13 treatment, neither did they contain significant amounts of JA after elicitation. In response to infiltration of Pep-13, the transgenic plants exhibited a highly reduced accumulation of reactive oxygen species as well as reduced hypersensitive cell death. The ability of the JA-deficient plants to accumulate SA suggests that SA accumulation is independent or upstream of JA accumulation. These data show that PAMP responses in potato require both SA and JA and that, in contrast to Arabidopsis, these compounds act in the same signal transduction pathway. Despite their inability to fully respond to PAMP treatment, the transgenic RNA interference plants are not altered in their basal defense against Phytophthora infestans.

32 CFR 13.4 - Duties and responsibilities of the defense.

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2010-07-01

... COMMISSIONS RESPONSIBILITIES OF THE CHIEF DEFENSE COUNSEL, DETAILED DEFENSE COUNSEL, AND CIVILIAN DEFENSE COUNSEL § 13.4 Duties and responsibilities of the defense. (a) Regular duties. The Defense shall perform... 32 National Defense 1 2010-07-01 2010-07-01 false Duties and responsibilities of the defense. 13.4...

Identification and expression analysis of WRKY transcription factor genes in canola (Brassica napus L. in response to fungal pathogens and hormone treatments

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Deyholos Michael K

2009-06-01

Full Text Available Abstract Background Members of plant WRKY transcription factor families are widely implicated in defense responses and various other physiological processes. For canola (Brassica napus L., no WRKY genes have been described in detail. Because of the economic importance of this crop, and its evolutionary relationship to Arabidopsis thaliana, we sought to characterize a subset of canola WRKY genes in the context of pathogen and hormone responses. Results In this study, we identified 46 WRKY genes from canola by mining the expressed sequence tag (EST database and cloned cDNA sequences of 38 BnWRKYs. A phylogenetic tree was constructed using the conserved WRKY domain amino acid sequences, which demonstrated that BnWRKYs can be divided into three major groups. We further compared BnWRKYs to the 72 WRKY genes from Arabidopsis and 91 WRKY from rice, and we identified 46 presumptive orthologs of AtWRKY genes. We examined the subcellular localization of four BnWRKY proteins using green fluorescent protein (GFP and we observed the fluorescent green signals in the nucleus only. The responses of 16 selected BnWRKY genes to two fungal pathogens, Sclerotinia sclerotiorum and Alternaria brassicae, were analyzed by quantitative real time-PCR (qRT-PCR. Transcript abundance of 13 BnWRKY genes changed significantly following pathogen challenge: transcripts of 10 WRKYs increased in abundance, two WRKY transcripts decreased after infection, and one decreased at 12 h post-infection but increased later on (72 h. We also observed that transcript abundance of 13/16 BnWRKY genes was responsive to one or more hormones, including abscisic acid (ABA, and cytokinin (6-benzylaminopurine, BAP and the defense signaling molecules jasmonic acid (JA, salicylic acid (SA, and ethylene (ET. We compared these transcript expression patterns to those previously described for presumptive orthologs of these genes in Arabidopsis and rice, and observed both similarities and differences in

Prunus domestica pathogenesis-related protein-5 activates the defense response pathway and enhances the resistance to fungal infection.

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Ashraf El-kereamy

Full Text Available Pathogenesis-related protein-5 (PR-5 has been implicated in plant disease resistance and its antifungal activity has been demonstrated in some fruit species. However, their roles, especially their interactions with the other defense responses in plant cells, are still not fully understood. In this study, we have cloned and characterized a new PR-5 cDNA named PdPR5-1 from the European plum (Prunus domestica. Expression of PdPR5-1 was studied in different cultivars varying in resistance to the brown rot disease caused by the necrotrophic fungus Monilinia fructicola. In addition transgenic Arabidopsis, ectopically expressing PdPR5-1 was used to study its role in other plant defense responses after fungal infection. We show that the resistant cultivars exhibited much higher levels of transcripts than the susceptible cultivars during fruit ripening. However, significant rise in the transcript levels after infection with M. fructicola was observed in the susceptible cultivars too. Transgenic Arabidopsis plants exhibited more resistance to Alternaria brassicicola. Further, there was a significant increase in the transcripts of genes involved in the phenylpropanoid biosynthesis pathway such as phenylalanine ammonia-lyase (PAL and phytoalexin (camalexin pathway leading to an increase in camalexin content after fungal infection. Our results show that PdPR5-1 gene, in addition to its anti-fungal properties, has a possible role in activating other defense pathways, including phytoalexin production.

WRKY transcription factors in plant responses to stresses.

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Jiang, Jingjing; Ma, Shenghui; Ye, Nenghui; Jiang, Ming; Cao, Jiashu; Zhang, Jianhua

2017-02-01

The WRKY gene family is among the largest families of transcription factors (TFs) in higher plants. By regulating the plant hormone signal transduction pathway, these TFs play critical roles in some plant processes in response to biotic and abiotic stress. Various bodies of research have demonstrated the important biological functions of WRKY TFs in plant response to different kinds of biotic and abiotic stresses and working mechanisms. However, very little summarization has been done to review their research progress. Not just important TFs function in plant response to biotic and abiotic stresses, WRKY also participates in carbohydrate synthesis, senescence, development, and secondary metabolites synthesis. WRKY proteins can bind to W-box (TGACC (A/T)) in the promoter of its target genes and activate or repress the expression of downstream genes to regulate their stress response. Moreover, WRKY proteins can interact with other TFs to regulate plant defensive responses. In the present review, we focus on the structural characteristics of WRKY TFs and the research progress on their functions in plant responses to a variety of stresses. © 2016 Institute of Botany, Chinese Academy of Sciences.

Assessing the Role of ETHYLENE RESPONSE FACTOR Transcriptional Repressors in Salicylic Acid-Mediated Suppression of Jasmonic Acid-Responsive Genes.

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Caarls, Lotte; Van der Does, Dieuwertje; Hickman, Richard; Jansen, Wouter; Verk, Marcel C Van; Proietti, Silvia; Lorenzo, Oscar; Solano, Roberto; Pieterse, Corné M J; Van Wees, Saskia C M

2017-02-01

Salicylic acid (SA) and jasmonic acid (JA) cross-communicate in the plant immune signaling network to finely regulate induced defenses. In Arabidopsis, SA antagonizes many JA-responsive genes, partly by targeting the ETHYLENE RESPONSE FACTOR (ERF)-type transcriptional activator ORA59. Members of the ERF transcription factor family typically bind to GCC-box motifs in the promoters of JA- and ethylene-responsive genes, thereby positively or negatively regulating their expression. The GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Here, we investigated whether SA-induced ERF-type transcriptional repressors, which may compete with JA-induced ERF-type activators for binding at the GCC-box, play a role in SA/JA antagonism. We selected ERFs that are transcriptionally induced by SA and/or possess an EAR transcriptional repressor motif. Several of the 16 ERFs tested suppressed JA-dependent gene expression, as revealed by enhanced JA-induced PDF1.2 or VSP2 expression levels in the corresponding erf mutants, while others were involved in activation of these genes. However, SA could antagonize JA-induced PDF1.2 or VSP2 in all erf mutants, suggesting that the tested ERF transcriptional repressors are not required for SA/JA cross-talk. Moreover, a mutant in the co-repressor TOPLESS, that showed reduction in repression of JA signaling, still displayed SA-mediated antagonism of PDF1.2 and VSP2. Collectively, these results suggest that SA-regulated ERF transcriptional repressors are not essential for antagonism of JA-responsive gene expression by SA. We further show that de novo SA-induced protein synthesis is required for suppression of JA-induced PDF1.2, pointing to SA-stimulated production of an as yet unknown protein that suppresses JA-induced transcription. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Plant methyl salicylate induces defense responses in the rhizobacterium Bacillus subtilis.

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Kobayashi, Kazuo

2015-04-01

Bacillus subtilis is a rhizobacterium that promotes plant growth and health. Cultivation of B. subtilis with an uprooted weed on solid medium produced pleat-like architectures on colonies near the plant. To test whether plants emit signals that affect B. subtilis colony morphology, we examined the effect of plant-related compounds on colony morphology. Bacillus subtilis formed mucoid colonies specifically in response to methyl salicylate, which is a plant-defense signal released in response to pathogen infection. Methyl salicylate induced mucoid colony formation by stimulating poly-γ-glutamic acid biosynthesis, which formed enclosing capsules that protected the cells from exposure to antimicrobial compounds. Poly-γ-glutamic acid synthesis depended on the DegS-DegU two-component regulatory system, which activated DegSU-dependent gene transcription in response to methyl salicylate. Bacillus subtilis did not induce plant methyl salicylate production, indicating that the most probable source of methyl salicylate in the rhizosphere is pathogen-infected plants. Methyl salicylate induced B. subtilis biosynthesis of the antibiotics bacilysin and fengycin, the latter of which exhibited inhibitory activity against the plant pathogenic fungus Fusarium oxysporum. We propose that B. subtilis may sense plants under pathogen attack via methyl salicylate, and express defense responses that protect both B. subtilis and host plants in the rhizosphere. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

OsWRKY53, a versatile switch in regulating herbivore-induced defense responses in rice

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Hu, Lingfei; Ye, Meng; Li, Ran; Lou, Yonggen

2016-01-01

ABSTRACT WRKY proteins, which belong to a large family of plant-specific transcription factors, play important roles in plant defenses against pathogens and herbivores by regulating defense-related signaling pathways. Recently, a rice WRKY transcription factor OsWRKY53 has been reported to function as a negative feedback modulator of OsMPK3/OsMPK6 and thereby to control the size of the investment a rice plant makes to defend against a chewing herbivore, the striped stem borer Chilo suppressalis. We investigated the performance of a piecing-sucking herbivore, the brown planthopper (BPH) Nilaparvata lugens, on transgenic plants that silence or overexpress OsWRKY53, and found that OsWRKY53 activates rice defenses against BPH by activating an H2O2 burst and suppressing ethylene biosynthesis. These findings suggest that OsWRKY53 functions not only as a regulator of plants' investment in specific defenses, but also as a switch to initiate new defenses against other stresses, highlighting the versatility and importance of OsWRKY53 in herbivore-induced plant defenses. PMID:27031005

OsWRKY53, a versatile switch in regulating herbivore-induced defense responses in rice

OpenAIRE

Hu, Lingfei; Ye, Meng; Li, Ran; Lou, Yonggen

2016-01-01

ABSTRACT WRKY proteins, which belong to a large family of plant-specific transcription factors, play important roles in plant defenses against pathogens and herbivores by regulating defense-related signaling pathways. Recently, a rice WRKY transcription factor OsWRKY53 has been reported to function as a negative feedback modulator of OsMPK3/OsMPK6 and thereby to control the size of the investment a rice plant makes to defend against a chewing herbivore, the striped stem borer Chilo suppressal...

Meta-Analysis of Transcriptional Responses to Mastitis-Causing Escherichia coli.

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Sidra Younis

Full Text Available Bovine mastitis is a widespread disease in dairy cows, and is often caused by bacterial mammary gland infection. Mastitis causes reduced milk production and leads to excessive use of antibiotics. We present meta-analysis of transcriptional profiles of bovine mastitis from 10 studies and 307 microarrays, allowing identification of much larger sets of affected genes than any individual study. Combining multiple studies provides insight into the molecular effects of Escherichia coli infection in vivo and uncovers differences between the consequences of E. coli vs. Staphylococcus aureus infection of primary mammary epithelial cells (PMECs. In udders, live E. coli elicits inflammatory and immune defenses through numerous cytokines and chemokines. Importantly, E. coli infection causes downregulation of genes encoding lipid biosynthesis enzymes that are involved in milk production. Additionally, host metabolism is generally suppressed. Finally, defensins and bacteria-recognition genes are upregulated, while the expression of the extracellular matrix protein transcripts is silenced. In PMECs, heat-inactivated E. coli elicits expression of ribosomal, cytoskeletal and angiogenic signaling genes, and causes suppression of the cell cycle and energy production genes. We hypothesize that heat-inactivated E. coli may have prophylactic effects against mastitis. Heat-inactivated S. aureus promotes stronger inflammatory and immune defenses than E. coli. Lipopolysaccharide by itself induces MHC antigen presentation components, an effect not seen in response to E. coli bacteria. These results provide the basis for strategies to prevent and treat mastitis and may lead to the reduction in the use of antibiotics.

Transcriptional profiling in human HaCaT keratinocytes in response to kaempferol and identification of potential transcription factors for regulating differential gene expression

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Kang, Byung Young; Lee, Ki-Hwan; Lee, Yong Sung; Hong, Il; Lee, Mi-Ock; Min, Daejin; Chang, Ihseop; Hwang, Jae Sung; Park, Jun Seong; Kim, Duck Hee

2008-01-01

Kaempferol is the major flavonol in green tea and exhibits many biomedically useful properties such as antioxidative, cytoprotective and anti-apoptotic activities. To elucidate its effects on the skin, we investigated the transcriptional profiles of kaempferol-treated HaCaT cells using cDNA microarray analysis and identified 147 transcripts that exhibited significant changes in expression. Of these, 18 were up-regulated and 129 were down-regulated. These transcripts were then classified into 12 categories according to their functional roles: cell adhesion/cytoskeleton, cell cycle, redox homeostasis, immune/defense responses, metabolism, protein biosynthesis/modification, intracellular transport, RNA processing, DNA modification/ replication, regulation of transcription, signal transduction and transport. We then analyzed the promoter sequences of differentially-regulated genes and identified over-represented regulatory sites and candidate transcription factors (TFs) for gene regulation by kaempferol. These included c-REL, SAP-1, Ahr-ARNT, Nrf-2, Elk-1, SPI-B, NF-κB and p65. In addition, we validated the microarray results and promoter analyses using conventional methods such as real-time PCR and ELISA-based transcription factor assay. Our microarray analysis has provided useful information for determining the genetic regulatory network affected by kaempferol, and this approach will be useful for elucidating gene-phytochemical interactions. PMID:18446059

The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots

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Carmen eGómez-Lama Cabanás

2014-09-01

Full Text Available Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets, many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR experiments aiming to: (i validate the induction of these genes, and (ii shed light on their expression pattern along time (from 1 to 15 days. Induction of olive genes potentially coding for lypoxigenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e. jerf, bHLH, WRKYs, as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mount a wide array of systemic defense responses in distant tissues (stems, leaves. This sheds light on how olive plants respond to the ‘non-hostile’ colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7.

Arabidopsis flower specific defense gene expression patterns affect resistance to pathogens

KAUST Repository

Ederli, Luisa

2015-02-20

We investigated whether the Arabidopsis flower evolved protective measures to increase reproductive success. Firstly, analyses of available transcriptome data show that the most highly expressed transcripts in the closed sepal (stage 12) are enriched in genes with roles in responses to chemical stimuli and cellular metabolic processes. At stage 15, there is enrichment in transcripts with a role in responses to biotic stimuli. Comparative analyses between the sepal and petal in the open flower mark an over-representation of transcripts with a role in responses to stress and catalytic activity. Secondly, the content of the biotic defense-associated phytohormone salicylic acid (SA) in sepals and petals is significantly higher than in leaves. To understand whether the high levels of stress responsive transcripts and the higher SA content affect defense, wild-type plants (Col-0) and transgenic plants defective in SA accumulation (nahG) were challenged with the biotrophic fungus Golovinomyces cichoracearum, the causal agent of powdery mildew, and the necrotrophic fungus Botrytis cinerea. NahG leaves were more sensitive than those of Col-0, suggesting that in leaves SA has a role in the defense against biotrophs. In contrast, sepals and petals of both genotypes were resistant to G. cichoracearum, indicating that in the flower, resistance to the biotrophic pathogen is not critically dependent on SA, but likely dependent on the up-regulation of stress-responsive genes. Since sepals and petals of both genotypes are equally susceptible to B. cinerea, we conclude that neither stress-response genes nor increased SA accumulation offers protection against the necrotrophic pathogen. These results are interpreted in the light of the distinctive role of the flower and we propose that in the early stages, the sepal may act as a chemical defense barrier of the developing reproductive structures against biotrophic pathogens.

Arabidopsis MYC Transcription Factors Are the Target of Hormonal Salicylic Acid/Jasmonic Acid Cross Talk in Response to Pieris brassicae Egg Extract.

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Schmiesing, André; Emonet, Aurélia; Gouhier-Darimont, Caroline; Reymond, Philippe

2016-04-01

Arabidopsis (Arabidopsis thaliana) plants recognize insect eggs and activate the salicylic acid (SA) pathway. As a consequence, expression of defense genes regulated by the jasmonic acid (JA) pathway is suppressed and larval performance is enhanced. Cross talk between defense signaling pathways is common in plant-pathogen interactions, but the molecular mechanism mediating this phenomenon is poorly understood. Here, we demonstrate that egg-induced SA/JA antagonism works independently of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor ORA59, which controls the ERF branch of the JA pathway. In addition, treatment with egg extract did not enhance expression or stability of JASMONATE ZIM-domain transcriptional repressors, and SA/JA cross talk did not involve JASMONATE ASSOCIATED MYC2-LIKEs, which are negative regulators of the JA pathway. Investigating the stability of MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that additively control jasmonate-related defense responses, we found that egg extract treatment strongly diminished MYC protein levels in an SA-dependent manner. Furthermore, we identified WRKY75 as a novel and essential factor controlling SA/JA cross talk. These data indicate that insect eggs target the MYC branch of the JA pathway and uncover an unexpected modulation of SA/JA antagonism depending on the biological context in which the SA pathway is activated. © 2016 American Society of Plant Biologists. All Rights Reserved.

WRKY transcription factors involved in PR-1 gene expression in Arabidopsis

NARCIS (Netherlands)

Hussain, Rana Muhammad Fraz

2012-01-01

Salicylic acid (SA) is involved in mediating defense against biotrophic pathogens. The current knowledge of the SA-mediated signaling pathway and its effect on the transcriptional regulation of defense responses are reviewed in this thesis. PR-1 is a marker gene for systemic acquired resistance

Arabidopsis MYC Transcription Factors Are the Target of Hormonal Salicylic Acid/Jasmonic Acid Cross Talk in Response to Pieris brassicae Egg Extract1[OPEN

Science.gov (United States)

Schmiesing, André; Gouhier-Darimont, Caroline

2016-01-01

Arabidopsis (Arabidopsis thaliana) plants recognize insect eggs and activate the salicylic acid (SA) pathway. As a consequence, expression of defense genes regulated by the jasmonic acid (JA) pathway is suppressed and larval performance is enhanced. Cross talk between defense signaling pathways is common in plant-pathogen interactions, but the molecular mechanism mediating this phenomenon is poorly understood. Here, we demonstrate that egg-induced SA/JA antagonism works independently of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor ORA59, which controls the ERF branch of the JA pathway. In addition, treatment with egg extract did not enhance expression or stability of JASMONATE ZIM-domain transcriptional repressors, and SA/JA cross talk did not involve JASMONATE ASSOCIATED MYC2-LIKEs, which are negative regulators of the JA pathway. Investigating the stability of MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that additively control jasmonate-related defense responses, we found that egg extract treatment strongly diminished MYC protein levels in an SA-dependent manner. Furthermore, we identified WRKY75 as a novel and essential factor controlling SA/JA cross talk. These data indicate that insect eggs target the MYC branch of the JA pathway and uncover an unexpected modulation of SA/JA antagonism depending on the biological context in which the SA pathway is activated. PMID:26884488

Peptidoglycan from Fermentation By-Product Triggers Defense Responses in Grapevine

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Chen, Yang; Takeda, Taito; Aoki, Yoshinao; Fujita, Keiko; Suzuki, Shunji; Igarashi, Daisuke

2014-01-01

Plants are constantly under attack from a variety of microorganisms, and rely on a series of complex detection and response systems to protect themselves from infection. Here, we found that a by-product of glutamate fermentation triggered defense responses in grapevine, increasing the expression of defense response genes in cultured cells, foliar chitinase activity, and resistance to infection by downy mildew in leaf explants. To identify the molecule that triggered this innate immunity, we fractionated and purified candidates extracted from Corynebacterium glutamicum, a bacterium used in the production of amino acids by fermentation. Using hydrolysis by lysozyme, a silkworm larva plasma detection system, and gel filtration analysis, we identified peptidoglycan as inducing the defense responses. Peptidoglycans of Escherichia coli, Bacillus subtilis, and Staphylococcus aureus also generated similar defensive responses. PMID:25427192

Mycobacterium tuberculosis Transcription Machinery: Ready To Respond to Host Attacks

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Flentie, Kelly; Garner, Ashley L.

2016-01-01

Regulating responses to stress is critical for all bacteria, whether they are environmental, commensal, or pathogenic species. For pathogenic bacteria, successful colonization and survival in the host are dependent on adaptation to diverse conditions imposed by the host tissue architecture and the immune response. Once the bacterium senses a hostile environment, it must enact a change in physiology that contributes to the organism's survival strategy. Inappropriate responses have consequences; hence, the execution of the appropriate response is essential for survival of the bacterium in its niche. Stress responses are most often regulated at the level of gene expression and, more specifically, transcription. This minireview focuses on mechanisms of regulating transcription initiation that are required by Mycobacterium tuberculosis to respond to the arsenal of defenses imposed by the host during infection. In particular, we highlight how certain features of M. tuberculosis physiology allow this pathogen to respond swiftly and effectively to host defenses. By enacting highly integrated and coordinated gene expression changes in response to stress, M. tuberculosis is prepared for battle against the host defense and able to persist within the human population. PMID:26883824

Rickettsia conorii transcriptional response within inoculation eschar.

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Patricia Renesto

Full Text Available BACKGROUND: Rickettsia conorii, the causative agent of the Mediterranean spotted fever, is transmitted to humans by the bite of infected ticks Rhipicephalus sanguineus. The skin thus constitutes an important barrier for the entry and propagation of R. conorii. Given this, analysis of the survival strategies used by the bacterium within infected skin is critical for our understanding of rickettsiosis. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report the first genome-wide analysis of R. conorii gene expression from infected human skin biopsies. Our data showed that R. conorii exhibited a striking transcript signature that is remarkably conserved across patients, regardless of genotype. The expression profiles obtained using custom Agilent microarrays were validated by quantitative RT-PCR. Within eschars, the amount of detected R. conorii transcripts was of 55%, this value being of 74% for bacteria grown in Vero cells. In such infected host tissues, approximately 15% (n = 211 of the total predicted R. conorii ORFs appeared differentially expressed compared to bacteria grown in standard laboratory conditions. These genes are mostly down-regulated and encode proteins essential for bacterial replication. Some of the strategies displayed by rickettsiae to overcome the host defense barriers, thus avoiding killing, were also pointed out. The observed up-regulation of rickettsial genes associated with DNA repair is likely to correspond to a DNA-damaging agent enriched environment generated by the host cells to eradicate the pathogens. Survival of R. conorii within eschars also involves adaptation to osmotic stress, changes in cell surface proteins and up-regulation of some virulence factors. Interestingly, in contrast to down-regulated transcripts, we noticed that up-regulated ones rather exhibit a small nucleotide size, most of them being exclusive for the spotted fever group rickettsiae. CONCLUSION/SIGNIFICANCE: Because eschar is a site for rickettsial

Silverleaf whitefly induces salicylic acid defenses and suppresses effectual jasmonic acid defenses.

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Zarate, Sonia I; Kempema, Louisa A; Walling, Linda L

2007-02-01

The basal defenses important in curtailing the development of the phloem-feeding silverleaf whitefly (Bemisia tabaci type B; SLWF) on Arabidopsis (Arabidopsis thaliana) were investigated. Sentinel defense gene RNAs were monitored in SLWF-infested and control plants. Salicylic acid (SA)-responsive gene transcripts accumulated locally (PR1, BGL2, PR5, SID2, EDS5, PAD4) and systemically (PR1, BGL2, PR5) during SLWF nymph feeding. In contrast, jasmonic acid (JA)- and ethylene-dependent RNAs (PDF1.2, VSP1, HEL, THI2.1, FAD3, ERS1, ERF1) were repressed or not modulated in SLWF-infested leaves. To test for a role of SA and JA pathways in basal defense, SLWF development on mutant and transgenic lines that constitutively activate or impair defense pathways was determined. By monitoring the percentage of SLWF nymphs in each instar, we show that mutants that activate SA defenses (cim10) or impair JA defenses (coi1) accelerated SLWF nymphal development. Reciprocally, mutants that activate JA defenses (cev1) or impair SA defenses (npr1, NahG) slowed SLWF nymphal development. Furthermore, when npr1 plants, which do not activate downstream SA defenses, were treated with methyl jasmonate, a dramatic delay in nymph development was observed. Collectively, these results showed that SLWF-repressed, JA-regulated defenses were associated with basal defense to the SLWF.

Jasmonate is essential for insect defense in Arabidopsis.

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McConn, M; Creelman, R A; Bell, E; Mullet, J E; Browse, J

1997-05-13

The signaling pathways that allow plants to mount defenses against chewing insects are known to be complex. To investigate the role of jasmonate in wound signaling in Arabidopsis and to test whether parallel or redundant pathways exist for insect defense, we have studied a mutant (fad3-2 fad7-2 fad8) that is deficient in the jasmonate precursor linolenic acid. Mutant plants contained negligible levels of jasmonate and showed extremely high mortality ( approximately 80%) from attack by larvae of a common saprophagous fungal gnat, Bradysia impatiens (Diptera: Sciaridae), even though neighboring wild-type plants were largely unaffected. Application of exogenous methyl jasmonate substantially protected the mutant plants and reduced mortality to approximately 12%. These experiments precisely define the role of jasmonate as being essential for the induction of biologically effective defense in this plant-insect interaction. The transcripts of three wound-responsive genes were shown not to be induced by wounding of mutant plants but the same transcripts could be induced by application of methyl jasmonate. By contrast, measurements of transcript levels for a gene encoding glutathione S-transferase demonstrated that wound induction of this gene is independent of jasmonate synthesis. These results indicate that the mutant will be a good genetic model for testing the practical effectiveness of candidate defense genes.

Distinct roles of jasmonates and aldehydes in plant-defense responses.

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E Wassim Chehab

Full Text Available BACKGROUND: Many inducible plant-defense responses are activated by jasmonates (JAs, C(6-aldehydes, and their corresponding derivatives, produced by the two main competing branches of the oxylipin pathway, the allene oxide synthase (AOS and hydroperoxide lyase (HPL branches, respectively. In addition to competition for substrates, these branch-pathway-derived metabolites have substantial overlap in regulation of gene expression. Past experiments to define the role of C(6-aldehydes in plant defense responses were biased towards the exogenous application of the synthetic metabolites or the use of genetic manipulation of HPL expression levels in plant genotypes with intact ability to produce the competing AOS-derived metabolites. To uncouple the roles of the C(6-aldehydes and jasmonates in mediating direct and indirect plant-defense responses, we generated Arabidopsis genotypes lacking either one or both of these metabolites. These genotypes were subsequently challenged with a phloem-feeding insect (aphids: Myzus persicae, an insect herbivore (leafminers: Liriomyza trifolii, and two different necrotrophic fungal pathogens (Botrytis cinerea and Alternaria brassicicola. We also characterized the volatiles emitted by these plants upon aphid infestation or mechanical wounding and identified hexenyl acetate as the predominant compound in these volatile blends. Subsequently, we examined the signaling role of this compound in attracting the parasitoid wasp (Aphidius colemani, a natural enemy of aphids. PRINCIPAL FINDINGS: This study conclusively establishes that jasmonates and C(6-aldehydes play distinct roles in plant defense responses. The jasmonates are indispensable metabolites in mediating the activation of direct plant-defense responses, whereas the C(6-aldehyes are not. On the other hand, hexenyl acetate, an acetylated C(6-aldehyde, is the predominant wound-inducible volatile signal that mediates indirect defense responses by directing tritrophic

Overexpression of stress-related genes in Cuscuta campestris in response to host defense reactions

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Hamed Rezaei

2017-07-01

Full Text Available Herb dodder ( Cuscuta spp. is one of the most important parasitic plants that can severely affect crop yields in the world. So far, interactions of this parasitic plant with hosts were not investigated adequately. Here, we conducted a differential expression analyzes and identified a number of genes that were differentially expressed in haustorium tissue compared with the stem of Cuscuta campestris growing on Alfalfa. We obtained 439 cDNA fragments from haustoria (parasite-host connection zone and stems (25 cm away from connections zones using the cDNA-AFLP (Amplified Fragment Length Polymorphism method with eight different primer combinations. Of 439 transcript-derived fragments (TDFs that were detected, 145 fragments were identified as differentially expressed genes. Five TDF sequences were similar to known functional genes involved in signal transduction, metabolism, respiration, and stress responses. Genes encoding DEAD-box ATP-dependent RNA helicase, potential heme-binding protein, lysine-specific demethylase 5A were selected for qRT-PCR. The qRT-PCR analyzes confirmed the results obtained using cDNA-AFLP. Our findings shed light on the elicitation of dodder defense responses in the connection zone to overcome plant defense reactions.

Transcriptional Dynamics Driving MAMP-Triggered Immunity and Pathogen Effector-Mediated Immunosuppression in Arabidopsis Leaves Following Infection with Pseudomonas syringae pv tomato DC3000.

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Lewis, Laura A; Polanski, Krzysztof; de Torres-Zabala, Marta; Jayaraman, Siddharth; Bowden, Laura; Moore, Jonathan; Penfold, Christopher A; Jenkins, Dafyd J; Hill, Claire; Baxter, Laura; Kulasekaran, Satish; Truman, William; Littlejohn, George; Prusinska, Justyna; Mead, Andrew; Steinbrenner, Jens; Hickman, Richard; Rand, David; Wild, David L; Ott, Sascha; Buchanan-Wollaston, Vicky; Smirnoff, Nick; Beynon, Jim; Denby, Katherine; Grant, Murray

2015-11-01

Transcriptional reprogramming is integral to effective plant defense. Pathogen effectors act transcriptionally and posttranscriptionally to suppress defense responses. A major challenge to understanding disease and defense responses is discriminating between transcriptional reprogramming associated with microbial-associated molecular pattern (MAMP)-triggered immunity (MTI) and that orchestrated by effectors. A high-resolution time course of genome-wide expression changes following challenge with Pseudomonas syringae pv tomato DC3000 and the nonpathogenic mutant strain DC3000hrpA- allowed us to establish causal links between the activities of pathogen effectors and suppression of MTI and infer with high confidence a range of processes specifically targeted by effectors. Analysis of this information-rich data set with a range of computational tools provided insights into the earliest transcriptional events triggered by effector delivery, regulatory mechanisms recruited, and biological processes targeted. We show that the majority of genes contributing to disease or defense are induced within 6 h postinfection, significantly before pathogen multiplication. Suppression of chloroplast-associated genes is a rapid MAMP-triggered defense response, and suppression of genes involved in chromatin assembly and induction of ubiquitin-related genes coincide with pathogen-induced abscisic acid accumulation. Specific combinations of promoter motifs are engaged in fine-tuning the MTI response and active transcriptional suppression at specific promoter configurations by P. syringae. © 2015 American Society of Plant Biologists. All rights reserved.

Limited response of ponderosa pine bole defenses to wounding and fungi.

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Gaylord, Monica L; Hofstetter, Richard W; Kolb, Thomas E; Wagner, Michael R

2011-04-01

Tree defense against bark beetles (Curculionidae: Scolytinae) and their associated fungi generally comprises some combination of constitutive (primary) and induced (secondary) defenses. In pines, the primary constitutive defense against bark beetles consists of preformed resin stored in resin ducts. Induced defenses at the wound site (point of beetle entry) in pines may consist of an increase in resin flow and necrotic lesion formation. The quantity and quality of both induced and constitutive defenses can vary by species and season. The inducible defense response in ponderosa pine is not well understood. Our study examined the inducible defense response in ponderosa pine using traumatic mechanical wounding, and wounding with and without fungal inoculations with two different bark beetle-associated fungi (Ophiostoma minus and Grosmannia clavigera). Resin flow did not significantly increase in response to any treatment. In addition, necrotic lesion formation on the bole after fungal inoculation was minimal. Stand thinning, which has been shown to increase water availability, had no, or inconsistent, effects on inducible tree defense. Our results suggest that ponderosa pine bole defense against bark beetles and their associated fungi is primarily constitutive and not induced.

TcNPR3 from Theobroma cacao functions as a repressor of the pathogen defense response.

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Shi, Zi; Zhang, Yufan; Maximova, Siela N; Guiltinan, Mark J

2013-12-06

Arabidopsis thaliana (Arabidopsis) NON-EXPRESSOR OF PR1 (NPR1) is a transcription coactivator that plays a central role in regulating the transcriptional response to plant pathogens. Developing flowers of homozygous npr3 mutants are dramatically more resistant to infection by the pathogenic bacterium Pseudomonas syringae, suggesting a role of NPR3 as a repressor of NPR1-mediated defense response with a novel role in flower development. We report here the characterization of a putative NPR3 gene from the tropical tree species Theobroma cacao (TcNPR3). Like in Arabidopsis, TcNPR3 was constitutively expressed across a wide range of tissue types and developmental stages but with some differences in relative levels compared to Arabidopsis. To test the function of TcNPR3, we performed transgenic complementation analysis by introducing a constitutively expressing putative TcNPR3 transgene into an Arabidopsis npr3 mutant. TcNPR3 expressing Arabidopsis plants were partially restored to the WT pathogen phenotype (immature flowers susceptible to bacterial infection). To test TcNPR3 function directly in cacao tissues, a synthetic microRNA targeting TcNPR3 mRNA was transiently expressed in cacao leaves using an Agrobacterium-infiltration method. TcNPR3 knock down leaf tissues were dramatically more resistance to infection with Phytophthora capsici in a leaf bioassay, showing smaller lesion sizes and reduced pathogen replication. We conclude that TcNPR3 functions similar to the Arabidopsis NPR3 gene in the regulation of the cacao defense response. Since TcNPR3 did not show a perfect complementation of the Arabidopsis NPR3 mutation, the possibility remains that other functions of TcNPR3 remain to be found. This novel knowledge can contribute to the breeding of resistant cacao varieties against pathogens through molecular markers based approaches or biotechnological strategies.

Differential Timing of Spider Mite-Induced Direct and Indirect Defenses in Tomato Plants1[w

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Kant, Merijn R.; Ament, Kai; Sabelis, Maurice W.; Haring, Michel A.; Schuurink, Robert C.

2004-01-01

Through a combined metabolomics and transcriptomics approach we analyzed the events that took place during the first 5 d of infesting intact tomato (Lycopersicon esculentum) plants with spider mites (Tetranychus urticae). Although the spider mites had caused little visible damage to the leaves after 1 d, they had already induced direct defense responses. For example, proteinase inhibitor activity had doubled and the transcription of genes involved in jasmonate-, salicylate-, and ethylene-regulated defenses had been activated. On day four, proteinase inhibitor activity and particularly transcript levels of salicylate-regulated genes were still maintained. In addition, genes involved in phospholipid metabolism were up-regulated on day one and those in the secondary metabolism on day four. Although transcriptional up-regulation of the enzymes involved in the biosynthesis of monoterpenes and diterpenes already occurred on day one, a significant increase in the emission of volatile terpenoids was delayed until day four. This increase in volatile production coincided with the increased olfactory preference of predatory mites (Phytoseiulus persimilis) for infested plants. Our results indicate that tomato activates its indirect defenses (volatile production) to complement the direct defense response against spider mites. PMID:15122016

Neonicotinoid insecticides induce salicylate-associated plant defense responses

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Ford, Kevin A.; Casida, John E.; Chandran, Divya; Gulevich, Alexander G.; Okrent, Rachel A.; Durkin, Kathleen A.; Sarpong, Richmond; Bunnelle, Eric M.; Wildermuth, Mary C.

2010-01-01

Neonicotinoid insecticides control crop pests based on their action as agonists at the insect nicotinic acetylcholine receptor, which accepts chloropyridinyl- and chlorothiazolyl-analogs almost equally well. In some cases, these compounds have also been reported to enhance plant vigor and (a)biotic stress tolerance, independent of their insecticidal function. However, this mode of action has not been defined. Using Arabidopsis thaliana, we show that the neonicotinoid compounds, imidacloprid (IMI) and clothianidin (CLO), via their 6-chloropyridinyl-3-carboxylic acid and 2-chlorothiazolyl-5-carboxylic acid metabolites, respectively, induce salicylic acid (SA)-associated plant responses. SA is a phytohormone best known for its role in plant defense against pathogens and as an inducer of systemic acquired resistance; however, it can also modulate abiotic stress responses. These neonicotinoids effect a similar global transcriptional response to that of SA, including genes involved in (a)biotic stress response. Furthermore, similar to SA, IMI and CLO induce systemic acquired resistance, resulting in reduced growth of a powdery mildew pathogen. The action of CLO induces the endogenous synthesis of SA via the SA biosynthetic enzyme ICS1, with ICS1 required for CLO-induced accumulation of SA, expression of the SA marker PR1, and fully enhanced resistance to powdery mildew. In contrast, the action of IMI does not induce endogenous synthesis of SA. Instead, IMI is further bioactivated to 6-chloro-2-hydroxypyridinyl-3-carboxylic acid, which is shown here to be a potent inducer of PR1 and inhibitor of SA-sensitive enzymes. Thus, via different mechanisms, these chloropyridinyl- and chlorothiazolyl-neonicotinoids induce SA responses associated with enhanced stress tolerance. PMID:20876120

Gene expression analysis of molecular mechanisms of defense induced in Medicago truncatula parasitized by Orobanche crenata.

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Die, José Vicente; González Verdejo, Clara I; Dita, Miguel A; Nadal, Salvador; Román, Belén

2009-07-01

The infection of Medicago truncatula Gaertn. roots with the obligate parasite Orobanche crenata Forsk. is a useful model for studying the molecular events involved in the legumes-parasite interaction. In order to gain insight into the identification of gene-regulatory elements involved in the resistance mechanism, the temporal expression pattern of ten defense-related genes was carried out using real-time quantitative reverse-transcription polymerase chain reaction assays. The induction of all of the analyzed transcripts significantly increased over a range from 2- to 321-fold higher than the control depending on the gene and time point. The transcriptional changes observed in response to O. crenata infection suggest that resistance could rely on both, the induction of general defense-related genes and more specific responses.

Plant Mediator complex and its critical functions in transcription regulation.

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Yang, Yan; Li, Ling; Qu, Li-Jia

2016-02-01

The Mediator complex is an important component of the eukaryotic transcriptional machinery. As an essential link between transcription factors and RNA polymerase II, the Mediator complex transduces diverse signals to genes involved in different pathways. The plant Mediator complex was recently purified and comprises conserved and specific subunits. It functions in concert with transcription factors to modulate various responses. In this review, we summarize the recent advances in understanding the plant Mediator complex and its diverse roles in plant growth, development, defense, non-coding RNA production, response to abiotic stresses, flowering, genomic stability and metabolic homeostasis. In addition, the transcription factors interacting with the Mediator complex are also highlighted. © 2015 Institute of Botany, Chinese Academy of Sciences.

Silverleaf Whitefly Induces Salicylic Acid Defenses and Suppresses Effectual Jasmonic Acid Defenses1[W][OA

Science.gov (United States)

Zarate, Sonia I.; Kempema, Louisa A.; Walling, Linda L.

2007-01-01

The basal defenses important in curtailing the development of the phloem-feeding silverleaf whitefly (Bemisia tabaci type B; SLWF) on Arabidopsis (Arabidopsis thaliana) were investigated. Sentinel defense gene RNAs were monitored in SLWF-infested and control plants. Salicylic acid (SA)-responsive gene transcripts accumulated locally (PR1, BGL2, PR5, SID2, EDS5, PAD4) and systemically (PR1, BGL2, PR5) during SLWF nymph feeding. In contrast, jasmonic acid (JA)- and ethylene-dependent RNAs (PDF1.2, VSP1, HEL, THI2.1, FAD3, ERS1, ERF1) were repressed or not modulated in SLWF-infested leaves. To test for a role of SA and JA pathways in basal defense, SLWF development on mutant and transgenic lines that constitutively activate or impair defense pathways was determined. By monitoring the percentage of SLWF nymphs in each instar, we show that mutants that activate SA defenses (cim10) or impair JA defenses (coi1) accelerated SLWF nymphal development. Reciprocally, mutants that activate JA defenses (cev1) or impair SA defenses (npr1, NahG) slowed SLWF nymphal development. Furthermore, when npr1 plants, which do not activate downstream SA defenses, were treated with methyl jasmonate, a dramatic delay in nymph development was observed. Collectively, these results showed that SLWF-repressed, JA-regulated defenses were associated with basal defense to the SLWF. PMID:17189328

Induced Genome-Wide Binding of Three Arabidopsis WRKY Transcription Factors during Early MAMP-Triggered Immunity.

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Birkenbihl, Rainer P; Kracher, Barbara; Somssich, Imre E

2017-01-01

During microbial-associated molecular pattern-triggered immunity (MTI), molecules derived from microbes are perceived by cell surface receptors and upon signaling to the nucleus initiate a massive transcriptional reprogramming critical to mount an appropriate host defense response. WRKY transcription factors play an important role in regulating these transcriptional processes. Here, we determined on a genome-wide scale the flg22-induced in vivo DNA binding dynamics of three of the most prominent WRKY factors, WRKY18, WRKY40, and WRKY33. The three WRKY factors each bound to more than 1000 gene loci predominantly at W-box elements, the known WRKY binding motif. Binding occurred mainly in the 500-bp promoter regions of these genes. Many of the targeted genes are involved in signal perception and transduction not only during MTI but also upon damage-associated molecular pattern-triggered immunity, providing a mechanistic link between these functionally interconnected basal defense pathways. Among the additional targets were genes involved in the production of indolic secondary metabolites and in modulating distinct plant hormone pathways. Importantly, among the targeted genes were numerous transcription factors, encoding predominantly ethylene response factors, active during early MTI, and WRKY factors, supporting the previously hypothesized existence of a WRKY subregulatory network. Transcriptional analysis revealed that WRKY18 and WRKY40 function redundantly as negative regulators of flg22-induced genes often to prevent exaggerated defense responses. © 2016 American Society of Plant Biologists. All rights reserved.

Dual RNA-seq reveals no plastic transcriptional response of the coccidian parasite Eimeria falciformis to host immune defenses.

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Ehret, Totta; Spork, Simone; Dieterich, Christoph; Lucius, Richard; Heitlinger, Emanuel

2017-09-05

Parasites can either respond to differences in immune defenses that exist between individual hosts plastically or, alternatively, follow a genetically canalized ("hard wired") program of infection. Assuming that large-scale functional plasticity would be discernible in the parasite transcriptome we have performed a dual RNA-seq study of the lifecycle of Eimeria falciformis using infected mice with different immune status as models for coccidian infections. We compared parasite and host transcriptomes (dual transcriptome) between naïve and challenge infected mice, as well as between immune competent and immune deficient ones. Mice with different immune competence show transcriptional differences as well as differences in parasite reproduction (oocyst shedding). Broad gene categories represented by differently abundant host genes indicate enrichments for immune reaction and tissue repair functions. More specifically, TGF-beta, EGF, TNF and IL-1 and IL-6 are examples of functional annotations represented differently depending on host immune status. Much in contrast, parasite transcriptomes were neither different between Coccidia isolated from immune competent and immune deficient mice, nor between those harvested from naïve and challenge infected mice. Instead, parasite transcriptomes have distinct profiles early and late in infection, characterized largely by biosynthesis or motility associated functional gene groups, respectively. Extracellular sporozoite and oocyst stages showed distinct transcriptional profiles and sporozoite transcriptomes were found enriched for species specific genes and likely pathogenicity factors. We propose that the niche and host-specific parasite E. falciformis uses a genetically canalized program of infection. This program is likely fixed in an evolutionary process rather than employing phenotypic plasticity to interact with its host. This in turn might limit the potential of the parasite to adapt to new host species or niches, forcing

Relative roles of the cellular and humoral responses in the Drosophila host defense against three gram-positive bacterial infections.

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Nadine T Nehme

2011-03-01

Full Text Available Two NF-kappaB signaling pathways, Toll and immune deficiency (imd, are required for survival to bacterial infections in Drosophila. In response to septic injury, these pathways mediate rapid transcriptional activation of distinct sets of effector molecules, including antimicrobial peptides, which are important components of a humoral defense response. However, it is less clear to what extent macrophage-like hemocytes contribute to host defense.In order to dissect the relative importance of humoral and cellular defenses after septic injury with three different gram-positive bacteria (Micrococcus luteus, Enterococcus faecalis, Staphylococcus aureus, we used latex bead pre-injection to ablate macrophage function in flies wildtype or mutant for various Toll and imd pathway components. We found that in all three infection models a compromised phagocytic system impaired fly survival--independently of concomitant Toll or imd pathway activation. Our data failed to confirm a role of the PGRP-SA and GNBP1 Pattern Recognition Receptors for phagocytosis of S. aureus. The Drosophila scavenger receptor Eater mediates the phagocytosis by hemocytes or S2 cells of E. faecalis and S. aureus, but not of M. luteus. In the case of M. luteus and E. faecalis, but not S. aureus, decreased survival due to defective phagocytosis could be compensated for by genetically enhancing the humoral immune response.Our results underscore the fundamental importance of both cellular and humoral mechanisms in Drosophila immunity and shed light on the balance between these two arms of host defense depending on the invading pathogen.

Arabidopsis flower specific defense gene expression patterns affect resistance to pathogens

KAUST Repository

Ederli, Luisa; Dawe, Adam; Pasqualini, Stefania; Quaglia, Mara; Xiong, Liming; Gehring, Christoph A

2015-01-01

mark an over-representation of transcripts with a role in responses to stress and catalytic activity. Secondly, the content of the biotic defense-associated phytohormone salicylic acid (SA) in sepals and petals is significantly higher than in leaves

Partial activation of SA- and JA-defensive pathways in strawberry upon Colletotrichum acutatum interaction

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FRANCISCO AMIL-RUIZ

2016-07-01

Full Text Available Understanding the nature of pathogen host interaction may help improve strawberry (Fragaria × ananassa cultivars. Plant resistance to pathogenic agents usually operates through a complex network of defense mechanisms mediated by a diverse array of signaling molecules. In strawberry, resistance to a variety of pathogens has been reported to be mostly polygenic and quantitatively inherited, making it difficult to associate molecular markers with disease resistance genes. Colletotrichum acutatum spp. is a major strawberry pathogen, and completely resistant cultivars have not been reported. Moreover, strawberry defense network components and mechanisms remain largely unknown and poorly understood. Assessment of the strawberry response to C. acutatum included a global transcript analysis, and acidic hormones SA and JA measurements were analyzed after challenge with the pathogen. Induction of transcripts corresponding to the SA and JA signaling pathways and key genes controlling major steps within these defense pathways was detected. Accordingly, SA and JA accumulated in strawberry after infection. Contrastingly, induction of several important SA, JA, and oxidative stress-responsive defense genes, including FaPR1-1, FaLOX2, FaJAR1, FaPDF1, and FaGST1, was not detected, which suggests that specific branches in these defense pathways (those leading to FaPR1-2, FaPR2-1, FaPR2-2, FaAOS, FaPR5 and FaPR10 were activated. Our results reveal that specific aspects in SA and JA dependent signaling pathways are activated in strawberry upon interaction with C. acutatum. Certain described defense-associated transcripts related to these two known signaling pathways do not increase in abundance following infection. This finding suggests new insight into a specific putative molecular strategy for defense against this pathogen.

Transcriptional profile of sweet orange in response to chitosan and salicylic acid.

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Coqueiro, Danila Souza Oliveira; de Souza, Alessandra Alves; Takita, Marco Aurélio; Rodrigues, Carolina Munari; Kishi, Luciano Takeshi; Machado, Marcos Antonio

2015-04-12

Resistance inducers have been used in annual crops as an alternative for disease control. Wood perennial fruit trees, such as those of the citrus species, are candidates for treatment with resistance inducers, such as salicylic acid (SA) and chitosan (CHI). However, the involved mechanisms in resistance induced by elicitors in citrus are currently few known. In the present manuscript, we report information regarding the transcriptional changes observed in sweet orange in response to exogenous applications of SA and CHI using RNA-seq technology. More genes were induced by SA treatment than by CHI treatment. In total, 1,425 differentially expressed genes (DEGs) were identified following treatment with SA, including the important genes WRKY50, PR2, and PR9, which are known to participate in the salicylic acid signaling pathway, and genes involved in ethylene/Jasmonic acid biosynthesis (ACS12, AP2 domain-containing transcription factor, and OPR3). In addition, SA treatment promoted the induction of a subset of genes involved in several metabolic processes, such as redox states and secondary metabolism, which are associated with biotic stress. For CHI treatment, there were 640 DEGs, many of them involved in secondary metabolism. For both SA and CHI treatments, the auxin pathway genes were repressed, but SA treatment promoted induction in the ethylene and jasmonate acid pathway genes, in addition to repressing the abscisic acid pathway genes. Chitosan treatment altered some hormone metabolism pathways. The DEGs were validated by quantitative Real-Time PCR (qRT-PCR), and the results were consistent with the RNA-seq data, with a high correlation between the two analyses. We expanded the available information regarding induced defense by elicitors in a species of Citrus that is susceptible to various diseases and identified the molecular mechanisms by which this defense might be mediated.

Discriminative identification of transcriptional responses of promoters and enhancers after stimulus

KAUST Repository

Kleftogiannis, Dimitrios A.

2016-10-17

Promoters and enhancers regulate the initiation of gene expression and maintenance of expression levels in spatial and temporal manner. Recent findings stemming from the Cap Analysis of Gene Expression (CAGE) demonstrate that promoters and enhancers, based on their expression profiles after stimulus, belong to different transcription response subclasses. One of the most promising biological features that might explain the difference in transcriptional response between subclasses is the local chromatin environment. We introduce a novel computational framework, PEDAL, for distinguishing effectively transcriptional profiles of promoters and enhancers using solely histone modification marks, chromatin accessibility and binding sites of transcription factors and co-activators. A case study on data from MCF-7 cell-line reveals that PEDAL can identify successfully the transcription response subclasses of promoters and enhancers from two different stimulations. Moreover, we report subsets of input markers that discriminate with minimized classification error MCF-7 promoter and enhancer transcription response subclasses. Our work provides a general computational approach for identifying effectively cell-specific and stimulation-specific promoter and enhancer transcriptional profiles, and thus, contributes to improve our understanding of transcriptional activation in human.

Glufosinate ammonium-induced pathogen inhibition and defense responses culminate in disease protection in bar-transgenic rice.

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Ahn, Il-Pyung

2008-01-01

Glufosinate ammonium diminished developments of rice (Oryza sativa) blast and brown leaf spot in 35S:bar-transgenic rice. Pre- and postinoculation treatments of this herbicide reduced disease development. Glufosinate ammonium specifically impeded appressorium formation of the pathogens Magnaporthe grisea and Cochliobolus miyabeanus on hydrophobic surface and on transgenic rice. In contrast, conidial germination remained unaffected. Glufosinate ammonium diminished mycelial growth of two pathogens; however, this inhibitory effect was attenuated in malnutrition conditions. Glufosinate ammonium caused slight chlorosis and diminished chlorophyll content; however, these alterations were almost completely restored in transgenic rice within 7 d. Glufosinate ammonium triggered transcriptions of PATHOGENESIS-RELATED (PR) genes and hydrogen peroxide accumulation in transgenic rice and PR1 transcription in Arabidopsis (Arabidopsis thaliana) wild-type ecotype Columbia harboring 35S:bar construct. All transgenic Arabidopsis showed robust hydrogen peroxide accumulation by glufosinate ammonium. This herbicide also induced PR1 transcription in etr1 and jar1 expressing bar; however, no expression was observed in NahG and npr1. Fungal infection did not alter transcriptions of PR genes and hydrogen peroxide accumulation induced by glufosinate ammonium. Infiltration of glufosinate ammonium did not affect appressorium formation of M. grisea in vivo but inhibited blast disease development. Hydrogen peroxide scavengers nullified blast protection and transcriptions of PR genes by glufosinate ammonium; however, they did not affect brown leaf spot progression. In sum, both direct inhibition of pathogen infection and activation of defense systems were responsible for disease protection in bar-transgenic rice.

An elm EST database for identifying leaf beetle egg-induced defense genes

Directory of Open Access Journals (Sweden)

Büchel Kerstin

2012-06-01

Full Text Available Abstract Background Plants can defend themselves against herbivorous insects prior to the onset of larval feeding by responding to the eggs laid on their leaves. In the European field elm (Ulmus minor, egg laying by the elm leaf beetle ( Xanthogaleruca luteola activates the emission of volatiles that attract specialised egg parasitoids, which in turn kill the eggs. Little is known about the transcriptional changes that insect eggs trigger in plants and how such indirect defense mechanisms are orchestrated in the context of other biological processes. Results Here we present the first large scale study of egg-induced changes in the transcriptional profile of a tree. Five cDNA libraries were generated from leaves of (i untreated control elms, and elms treated with (ii egg laying and feeding by elm leaf beetles, (iii feeding, (iv artificial transfer of egg clutches, and (v methyl jasmonate. A total of 361,196 ESTs expressed sequence tags (ESTs were identified which clustered into 52,823 unique transcripts (Unitrans and were stored in a database with a public web interface. Among the analyzed Unitrans, 73% could be annotated by homology to known genes in the UniProt (Plant database, particularly to those from Vitis, Ricinus, Populus and Arabidopsis. Comparative in silico analysis among the different treatments revealed differences in Gene Ontology term abundances. Defense- and stress-related gene transcripts were present in high abundance in leaves after herbivore egg laying, but transcripts involved in photosynthesis showed decreased abundance. Many pathogen-related genes and genes involved in phytohormone signaling were expressed, indicative of jasmonic acid biosynthesis and activation of jasmonic acid responsive genes. Cross-comparisons between different libraries based on expression profiles allowed the identification of genes with a potential relevance in egg-induced defenses, as well as other biological processes, including signal transduction

An elm EST database for identifying leaf beetle egg-induced defense genes.

Science.gov (United States)

Büchel, Kerstin; McDowell, Eric; Nelson, Will; Descour, Anne; Gershenzon, Jonathan; Hilker, Monika; Soderlund, Carol; Gang, David R; Fenning, Trevor; Meiners, Torsten

2012-06-15

Plants can defend themselves against herbivorous insects prior to the onset of larval feeding by responding to the eggs laid on their leaves. In the European field elm (Ulmus minor), egg laying by the elm leaf beetle ( Xanthogaleruca luteola) activates the emission of volatiles that attract specialised egg parasitoids, which in turn kill the eggs. Little is known about the transcriptional changes that insect eggs trigger in plants and how such indirect defense mechanisms are orchestrated in the context of other biological processes. Here we present the first large scale study of egg-induced changes in the transcriptional profile of a tree. Five cDNA libraries were generated from leaves of (i) untreated control elms, and elms treated with (ii) egg laying and feeding by elm leaf beetles, (iii) feeding, (iv) artificial transfer of egg clutches, and (v) methyl jasmonate. A total of 361,196 ESTs expressed sequence tags (ESTs) were identified which clustered into 52,823 unique transcripts (Unitrans) and were stored in a database with a public web interface. Among the analyzed Unitrans, 73% could be annotated by homology to known genes in the UniProt (Plant) database, particularly to those from Vitis, Ricinus, Populus and Arabidopsis. Comparative in silico analysis among the different treatments revealed differences in Gene Ontology term abundances. Defense- and stress-related gene transcripts were present in high abundance in leaves after herbivore egg laying, but transcripts involved in photosynthesis showed decreased abundance. Many pathogen-related genes and genes involved in phytohormone signaling were expressed, indicative of jasmonic acid biosynthesis and activation of jasmonic acid responsive genes. Cross-comparisons between different libraries based on expression profiles allowed the identification of genes with a potential relevance in egg-induced defenses, as well as other biological processes, including signal transduction, transport and primary metabolism

A translational study on looming-evoked defensive response and the underlying subcortical pathway in autism.

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Hu, Yu; Chen, Zhuoming; Huang, Lu; Xi, Yue; Li, Bingxiao; Wang, Hong; Yan, Jiajian; Lee, Tatia M C; Tao, Qian; So, Kwok-Fai; Ren, Chaoran

2017-11-07

Rapidly approaching objects indicating threats can induce defensive response through activating a subcortical pathway comprising superior colliculus (SC), lateral posterior nucleus (LP), and basolateral amygdala (BLA). Abnormal defensive response has been reported in autism, and impaired synaptic connections could be the underlying mechanism. Whether the SC-LP-BLA pathway processes looming stimuli abnormally in autism is not clear. Here, we found that looming-evoked defensive response is impaired in a subgroup of the valproic acid (VPA) mouse model of autism. By combining the conventional neurotracer and transneuronal rabies virus tracing techniques, we demonstrated that synaptic connections in the SC-LP-BLA pathway were abnormal in VPA mice whose looming-evoked defensive responses were absent. Importantly, we further translated the finding to children with autism and observed that they did not present looming-evoked defensive response. Furthermore, the findings of the DTI with the probabilistic tractography showed that the structural connections of SC-pulvinar-amygdala in autism children were weak. The pulvinar is parallel to the LP in a mouse. Because looming-evoked defensive response is innate in humans and emerges much earlier than do social and language functions, the absence of defensive response could be an earlier sign of autism in children.

Reducing Defensive Responses to Thoughts of Death: Meditation, Mindfulness, and Buddhism.

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Park, Young Chin; Pyszczynski, Tom

2017-08-24

Three studies investigated the effects of meditation on responses to reminders of death. Study 1 took a quasi-experimental approach, comparing defensive responses to mortality salience (MS) of South Korean participants with varying levels of experience with Buddhism and meditation. Whereas non-Buddhists without meditation showed the typical increase in worldview defense after mortality salience (MS), this effect was not found among non-Buddhists immediately after an initial meditation experience, nor among lay Buddhists who meditated regularly or Buddhist monks with intensive meditation experience. Study 2, a fully randomized experiment, showed that MS increased worldview defense among South Koreans at a meditation training who were assessed before meditating but not among participants assessed after their first meditation experience. Study 3 showed that whereas American students without prior meditation experience showed increased worldview defense and suppression of death-related thoughts after MS, these effects were eliminated immediately after an initial meditation experience. Death thought accessibility mediated the effect of MS on worldview defense without meditation, but meditation eliminated this mediation. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Transcriptional responses of earthworm (Eisenia fetida) exposed to naphthenic acids in soil

International Nuclear Information System (INIS)

Wang, Jie; Cao, Xiaofeng; Sun, Jinhua; Chai, Liwei; Huang, Yi; Tang, Xiaoyan

2015-01-01

In this study, earthworms (Eisenia fetida) were exposed to commercial NAs contaminated soil, and changes in the levels of reactive oxygen species (ROS) and gene expressions of their defense system were monitored. The effects on the gene expression involved in reproduction and carcinogenesis were also evaluated. Significant increases in ROS levels was observed in NAs exposure groups, and the superoxide dismutase (SOD) and catalase (CAT) genes were both up-regulated at low and medium exposure doses, which implied NAs might exert toxicity by oxidative stress. The transcription of CRT and HSP70 coincided with oxidative stress, which implied both chaperones perform important functions in the protection against oxidative toxicity. The upregulation of TCTP gene indicated a potential adverse effect of NAs to terrestrial organisms through induction of carcinogenesis, and the downregulation of ANN gene indicated that NAs might potentially result in deleterious reproduction effects. - Highlights: • The first attempt to study gene ecotoxicity of NAs in terrestrial environment. • NAs exert toxicity by oxidative stress on earthworm. • NAs might cause carcinogenesis and reproductive disruption to earthworm. - NAs induced oxidative stress and altered transcriptions of genes involved in defense, reproduction, and carcinogenesis

Role of WRKY Transcription Factors in Arabidopsis Development and Stress Responses

OpenAIRE

Li, Jing

2014-01-01

It has been well established that environmentally induced alterations in gene expression are mediated by transcription factors (TFs). One of the important plant-specific TF groups is the WRKY (TFs containing a highly conserved WRKY domain) family, which is involved in regulation of various physiological programs including biotic and abiotic defenses, senescence and trichome development. Two members of WRKY group III in Arabidopsis thaliana, WRKY54 and WRKY70, are demonstrated in this study to...

Defense response in Nopal Cladodes infiltrated with Salmonella Typhimurium

Science.gov (United States)

Foodborne outbreaks associated with fresh produce have increased in recent years. Pre-harvest contamination of fresh produce via irrigation water, soil, or other animal vectors may be responsible for many of these outbreaks. We evaluated defense response of nopal plants when contaminated in intern...

Integration of ethylene and jasmonic acid signaling pathways in the expression of maize defense protein Mir1-CP.

Science.gov (United States)

Ankala, A; Luthe, D S; Williams, W P; Wilkinson, J R

2009-12-01

In plants, ethylene and jasmonate control the defense responses to multiple stressors, including insect predation. Among the defense proteins known to be regulated by ethylene is maize insect resistance 1-cysteine protease (Mir1-CP). This protein is constitutively expressed in the insect-resistant maize (Zea mays) genotype Mp708; however, its abundance significantly increases during fall armyworm (Spodoptera frugiperda) herbivory. Within 1 h of herbivory by fall armyworm, Mir1-CP accumulates at the feeding site and continues to increase in abundance until 24 h without any increase in its transcript (mir1) levels. To resolve this discrepancy and elucidate the role of ethylene and jasmonate in the signaling of Mir1-CP expression, the effects of phytohormone biosynthesis and perception inhibitors on Mir1-CP expression were tested. Immunoblot analysis of Mir1-CP accumulation and quantitative reverse-transcriptase polymerase chain reaction examination of mir1 levels in these treated plants demonstrate that Mir1-CP accumulation is regulated by both transcript abundance and protein expression levels. The results also suggest that jasmonate functions upstream of ethylene in the Mir1-CP expression pathway, allowing for both low-level constitutive expression and a two-stage defensive response, an immediate response involving Mir1-CP accumulation and a delayed response inducing mir1 transcript expression.

Biochemical Plant Responses to Ozone (IV. Cross-Induction of Defensive Pathways in Parsley (Petroselinum crispum L.) Plants).

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Eckey-Kaltenbach, H.; Ernst, D.; Heller, W.; Sandermann, H.

1994-01-01

Parsley (Petroselinum crispum L.) is known to respond to ultraviolet irradiation by the synthesis of flavone glycosides, whereas fungal or elicitor stress leads to the synthesis of furanocoumarin phytoalexins. We tested how these defensive pathways are affected by a single ozone treatment (200 nL L-1; 10 h). Assays were performed at the levels of transcripts, for enzyme activities, and for secondary products. The most rapid transcript accumulation was maximal at 3 h, whereas flavone glycosides and furanocoumarins were maximally induced at 12 and 24 h, respectively, after the start of ozone treatment. Ozone acted as a cross-inducer because the two distinct pathways were simultaneously induced. These results are consistent with the previously observed ozone induction of fungal and viral defense reactions in tobacco, spruce, and pine. PMID:12232062

Transcriptome-wide identification of Camellia sinensis WRKY transcription factors in response to temperature stress.

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Wu, Zhi-Jun; Li, Xing-Hui; Liu, Zhi-Wei; Li, Hui; Wang, Yong-Xin; Zhuang, Jing

2016-02-01

Tea plant [Camellia sinensis (L.) O. Kuntze] is a leaf-type healthy non-alcoholic beverage crop, which has been widely introduced worldwide. Tea is rich in various secondary metabolites, which are important for human health. However, varied climate and complex geography have posed challenges for tea plant survival. The WRKY gene family in plants is a large transcription factor family that is involved in biological processes related to stress defenses, development, and metabolite synthesis. Therefore, identification and analysis of WRKY family transcription factors in tea plant have a profound significance. In the present study, 50 putative C. sinensis WRKY proteins (CsWRKYs) with complete WRKY domain were identified and divided into three Groups (Group I-III) on the basis of phylogenetic analysis results. The distribution of WRKY family transcription factors among plantae, fungi, and protozoa showed that the number of WRKY genes increased in higher plant, whereas the number of these genes did not correspond to the evolutionary relationships of different species. Structural feature and annotation analysis results showed that CsWRKY proteins contained WRKYGQK/WRKYGKK domains and C2H2/C2HC-type zinc-finger structure: D-X18-R-X1-Y-X2-C-X4-7-C-X23-H motif; CsWRKY proteins may be associated with the biological processes of abiotic and biotic stresses, tissue development, and hormone and secondary metabolite biosynthesis. Temperature stresses suggested that the candidate CsWRKY genes were involved in responses to extreme temperatures. The current study established an extensive overview of the WRKY family transcription factors in tea plant. This study also provided a global survey of CsWRKY transcription factors and a foundation of future functional identification and molecular breeding.

Identifying salt stress-responsive transcripts from Roselle ( Hibiscus ...

African Journals Online (AJOL)

Hibiscus sabdariffa L.). Identifying the potentially novel transcripts responsible for salt stress tolerance in roselle will increase knowledge of the molecular mechanism underlying salt stress responses. In this study, differential display reverse ...

Priming by Rhizobacterium Protects Tomato Plants from Biotrophic and Necrotrophic Pathogen Infections through Multiple Defense Mechanisms

Science.gov (United States)

Ahn, Il-Pyung; Lee, Sang-Woo; Kim, Min Gab; Park, Sang-Ryeol; Hwang, Duk-Ju; Bae, Shin-Chul

2011-01-01

A selected strain of rhizobacterium, Pseudomonas putida strain LSW17S (LSW17S), protects tomato plants (Lycopersicon esculentum L. cv. Seokwang) from bacterial speck by biotrophic Pseudomonas syringae pv. tomato strain DC3000 (DC3000) and bacterial wilt by necrotrophic Ralstonia solanacearum KACC 10703 (Rs10703). To investigate defense mechanisms induced by LSW17S in tomato plants, transcription patterns of pathogenesis-related (PR) genes and H2O2 production were analyzed in plants treated with LSW17S and subsequent pathogen inoculation. LSW17S alone did not induce transcriptions of employed PR genes in leaves and roots. DC3000 challenge following LSW17S triggered rapid transcriptions of PR genes and H2O2 production in leaves and roots. Catalase infiltration with DC3000 attenuated defense-related responses and resistance against DC3000 infection. Despite depriving H2O2 production and PR1b transcription by the same treatment, resistance against Rs10703 infection was not deterred significantly. H2O2 is indispensable for defense signaling and/or mechanisms primed by LSW17S and inhibition of bacterial speck, however, it is not involved in resistance against bacterial wilt. PMID:21710203

Maternal programming of defensive responses through sustained effects on gene expression.

Science.gov (United States)

Zhang, Tie-Yuan; Bagot, Rose; Parent, Carine; Nesbitt, Cathy; Bredy, Timothy W; Caldji, Christian; Fish, Eric; Anisman, Hymie; Szyf, Moshe; Meaney, Michael J

2006-07-01

There are profound maternal effects on individual differences in defensive responses and reproductive strategies in species ranging literally from plants to insects to birds. Maternal effects commonly reflect the quality of the environment and are most likely mediated by the quality of the maternal provision (egg, propagule, etc.), which in turn determines growth rates and adult phenotype. In this paper we review data from the rat that suggest comparable forms of maternal effects on defensive responses stress, which are mediated by the effects of variations in maternal behavior on gene expression. Under conditions of environmental adversity maternal effects enhance the capacity for defensive responses in the offspring. In mammals, these effects appear to 'program' emotional, cognitive and endocrine systems towards increased sensitivity to adversity. In environments with an increased level of adversity, such effects can be considered adaptive, enhancing the probability of offspring survival to sexual maturity; the cost is that of an increased risk for multiple forms of pathology in later life.

Root defense analysis against Fusarium oxysporum reveals new regulators to confer resistance

Science.gov (United States)

Chen, Yi Chung; Wong, Chin Lin; Muzzi, Frederico; Vlaardingerbroek, Ido; Kidd, Brendan N.; Schenk, Peer M.

2014-01-01

Fusarium oxysporum is a root-infecting fungal pathogen that causes wilt disease on a broad range of plant species, including Arabidopsis thaliana. Investigation of the defense response against this pathogen had primarily been conducted using leaf tissue and little was known about the root defense response. In this study, we profiled the expression of root genes after infection with F. oxysporum by microarray analysis. In contrast to the leaf response, root tissue did not show a strong induction of defense-associated gene expression and instead showed a greater proportion of repressed genes. Screening insertion mutants from differentially expressed genes in the microarray uncovered a role for the transcription factor ETHYLENE RESPONSE FACTOR72 (ERF72) in susceptibility to F. oxysporum. Due to the role of ERF72 in suppressing programmed cell death and detoxifying reactive oxygen species (ROS), we examined the pub22/pub23/pub24 U-box type E3 ubiquitin ligase triple mutant which is known to possess enhanced ROS production in response to pathogen challenge. We found that the pub22/23/24 mutant is more resistant to F. oxysporum infection, suggesting that a heightened innate immune response provides protection against F. oxysporum. We conclude that root-mediated defenses against soil-borne pathogens can be provided at multiple levels. PMID:24998294

Stage-Related Defense Response Induction in Tomato Plants by Nesidiocoris tenuis

Science.gov (United States)

Naselli, Mario; Urbaneja, Alberto; Siscaro, Gaetano; Jaques, Josep A.; Zappalà, Lucia; Flors, Víctor; Pérez-Hedo, Meritxell

2016-01-01

The beneficial effects of direct predation by zoophytophagous biological control agents (BCAs), such as the mirid bug Nesidiocoris tenuis, are well-known. However, the benefits of zoophytophagous BCAs’ relation with host plants, via induction of plant defensive responses, have not been investigated until recently. To date, only the females of certain zoophytophagous BCAs have been demonstrated to induce defensive plant responses in tomato plants. The aim of this work was to determine whether nymphs, adult females, and adult males of N. tenuis are able to induce defense responses in tomato plants. Compared to undamaged tomato plants (i.e., not exposed to the mirid), plants on which young or mature nymphs, or adult males or females of N. tenuis fed and developed were less attractive to the whitefly Bemisia tabaci, but were more attractive to the parasitoid Encarsia formosa. Female-exposed plants were more repellent to B. tabaci and more attractive to E. formosa than were male-exposed plants. When comparing young- and mature-nymph-exposed plants, the same level of repellence was obtained for B. tabaci, but mature-nymph-exposed plants were more attractive to E. formosa. The repellent effect is attributed to the signaling pathway of abscisic acid, which is upregulated in N. tenuis-exposed plants, whereas the parasitoid attraction was attributed to the activation of the jasmonic acid signaling pathway. Our results demonstrate that all motile stages of N. tenuis can trigger defensive responses in tomato plants, although these responses may be slightly different depending on the stage considered. PMID:27472328

Erwinia carotovora elicitors and Botrytis cinerea activate defense responses in Physcomitrella patens

Directory of Open Access Journals (Sweden)

Bentancor Marcel

2007-10-01

Full Text Available Abstract Background Vascular plants respond to pathogens by activating a diverse array of defense mechanisms. Studies with these plants have provided a wealth of information on pathogen recognition, signal transduction and the activation of defense responses. However, very little is known about the infection and defense responses of the bryophyte, Physcomitrella patens, to well-studied phytopathogens. The purpose of this study was to determine: i whether two representative broad host range pathogens, Erwinia carotovora ssp. carotovora (E.c. carotovora and Botrytis cinerea (B. cinerea, could infect Physcomitrella, and ii whether B. cinerea, elicitors of a harpin (HrpN producing E.c. carotovora strain (SCC1 or a HrpN-negative strain (SCC3193, could cause disease symptoms and induce defense responses in Physcomitrella. Results B. cinerea and E.c. carotovora were found to readily infect Physcomitrella gametophytic tissues and cause disease symptoms. Treatments with B. cinerea spores or cell-free culture filtrates from E.c. carotovoraSCC1 (CF(SCC1, resulted in disease development with severe maceration of Physcomitrella tissues, while CF(SCC3193 produced only mild maceration. Although increased cell death was observed with either the CFs or B. cinerea, the occurrence of cytoplasmic shrinkage was only visible in Evans blue stained protonemal cells treated with CF(SCC1 or inoculated with B. cinerea. Most cells showing cytoplasmic shrinkage accumulated autofluorescent compounds and brown chloroplasts were evident in a high proportion of these cells. CF treatments and B. cinerea inoculation induced the expression of the defense-related genes: PR-1, PAL, CHS and LOX. Conclusion B. cinerea and E.c. carotovora elicitors induce a defense response in Physcomitrella, as evidenced by enhanced expression of conserved plant defense-related genes. Since cytoplasmic shrinkage is the most common morphological change observed in plant PCD, and that harpins and B

Duox, Flotillin-2, and Src42A are required to activate or delimit the spread of the transcriptional response to epidermal wounds in Drosophila.

Directory of Open Access Journals (Sweden)

Michelle T Juarez

2011-12-01

Full Text Available The epidermis is the largest organ of the body for most animals, and the first line of defense against invading pathogens. A breach in the epidermal cell layer triggers a variety of localized responses that in favorable circumstances result in the repair of the wound. Many cellular and genetic responses must be limited to epidermal cells that are close to wounds, but how this is regulated is still poorly understood. The order and hierarchy of epidermal wound signaling factors are also still obscure. The Drosophila embryonic epidermis provides an excellent system to study genes that regulate wound healing processes. We have developed a variety of fluorescent reporters that provide a visible readout of wound-dependent transcriptional activation near epidermal wound sites. A large screen for mutants that alter the activity of these wound reporters has identified seven new genes required to activate or delimit wound-induced transcriptional responses to a narrow zone of cells surrounding wound sites. Among the genes required to delimit the spread of wound responses are Drosophila Flotillin-2 and Src42A, both of which are transcriptionally activated around wound sites. Flotillin-2 and constitutively active Src42A are also sufficient, when overexpressed at high levels, to inhibit wound-induced transcription in epidermal cells. One gene required to activate epidermal wound reporters encodes Dual oxidase, an enzyme that produces hydrogen peroxide. We also find that four biochemical treatments (a serine protease, a Src kinase inhibitor, methyl-ß-cyclodextrin, and hydrogen peroxide are sufficient to globally activate epidermal wound response genes in Drosophila embryos. We explore the epistatic relationships among the factors that induce or delimit the spread of epidermal wound signals. Our results define new genetic functions that interact to instruct only a limited number of cells around puncture wounds to mount a transcriptional response, mediating

Transcriptional profiling of the bovine hepatic response to experimentally induced E. coli mastitis

DEFF Research Database (Denmark)

Jørgensen, Hanne Birgitte Hede; Buitenhuis, Bart; Røntved, Christine Maria

2012-01-01

The mammalian liver works to keep the body in a state of homeostasis and plays an important role in systemic acute phase response to infections. In this study we investigated the bovine hepatic acute phase response at the gene transcription level in dairy cows with experimentally E. coli-induced ......The mammalian liver works to keep the body in a state of homeostasis and plays an important role in systemic acute phase response to infections. In this study we investigated the bovine hepatic acute phase response at the gene transcription level in dairy cows with experimentally E. coli......-induced mastitis. At time = 0, each of 16 periparturient dairy cows received 20-40 CFU of live E. coli in one front quarter of the udder. A time series of liver biopsies was collected at -144, 12, 24 and 192 hours relative to time of inoculation. Changes in transcription levels in response to E. coli inoculation...... were analyzed using the Bovine Genome Array and tested significant for 408 transcripts over the time series (adjusted p0.05; abs(fold-change)>2). After 2-D clustering, transcripts represented three distinct transcription profiles: 1) regulation of gene transcription and apoptosis, 2) responses...

The WRKY57 Transcription Factor Affects the Expression of Jasmonate ZIM-Domain Genes Transcriptionally to Compromise Botrytis cinerea Resistance.

Science.gov (United States)

Jiang, Yanjuan; Yu, Diqiu

2016-08-01

Although necrotrophic pathogens cause many devastating plant diseases, our understanding of the plant defense response to them is limited. Here, we found that loss of function of WRKY57 enhanced the resistance of Arabidopsis (Arabidopsis thaliana) against Botrytis cinerea infection. Further investigation suggested that the negative regulation of WRKY57 against B cinerea depends on the jasmonic acid (JA) signaling pathway. Chromatin immunoprecipitation experiments revealed that WRKY57 directly binds to the promoters of JASMONATE ZIM-DOMAIN1 (JAZ1) and JAZ5, encoding two important repressors of the JA signaling pathway, and activates their transcription. In vivo and in vitro experiments demonstrated that WRKY57 interacts with nuclear-encoded SIGMA FACTOR BINDING PROTEIN1 (SIB1) and SIB2. Further experiments display that the same domain, the VQ motif, of SIB1 and SIB2 interact with WRKY33 and WRKY57. Moreover, transient transcriptional activity assays confirmed that WRKY57 and WRKY33 competitively regulate JAZ1 and JAZ5, SIB1 and SIB2 further enhance these competitions of WRKY57 to WRKY33. Therefore, coordinated regulation of Arabidopsis against B cinerea by transcription activators and repressors would benefit plants by allowing fine regulation of defense. © 2016 American Society of Plant Biologists. All Rights Reserved.

Early transcriptional responses of internalization defective Brucella abortus mutants in professional phagocytes, RAW 264.7.

Science.gov (United States)

Cha, Seung Bin; Lee, Won Jung; Shin, Min Kyoung; Jung, Myung Hwan; Shin, Seung Won; Yoo, An Na; Kim, Jong Wan; Yoo, Han Sang

2013-06-27

Brucella abortus is an intracellular zoonotic pathogen which causes undulant fever, endocarditis, arthritis and osteomyelitis in human and abortion and infertility in cattle. This bacterium is able to invade and replicate in host macrophage instead of getting removed by this defense mechanism. Therefore, understanding the interaction between virulence of the bacteria and the host cell is important to control brucellosis. Previously, we generated internalization defective mutants and analyzed the envelope proteins. The present study was undertaken to evaluate the changes in early transcriptional responses between wild type and internalization defective mutants infected mouse macrophage, RAW 264.7. Both of the wild type and mutant infected macrophages showed increased expression levels in proinflammatory cytokines, chemokines, apoptosis and G-protein coupled receptors (Gpr84, Gpr109a and Adora2b) while the genes related with small GTPase which mediate intracellular trafficking was decreased. Moreover, cytohesin 1 interacting protein (Cytip) and genes related to ubiquitination (Arrdc3 and Fbxo21) were down-regulated, suggesting the survival strategy of this bacterium. However, we could not detect any significant changes in the mutant infected groups compared to the wild type infected group. In summary, it was very difficult to clarify the alterations in host cellular transcription in response to infection with internalization defective mutants. However, we found several novel gene changes related to the GPCR system, ubiquitin-proteosome system, and growth arrest and DNA damages in response to B. abortus infection. These findings may contribute to a better understanding of the molecular mechanisms underlying host-pathogen interactions and need to be studied further.

Transcriptional Response to Lactic Acid Stress in the Hybrid Yeast Zygosaccharomyces parabailii.

Science.gov (United States)

Ortiz-Merino, Raúl A; Kuanyshev, Nurzhan; Byrne, Kevin P; Varela, Javier A; Morrissey, John P; Porro, Danilo; Wolfe, Kenneth H; Branduardi, Paola

2018-03-01

Lactic acid has a wide range of applications starting from its undissociated form, and its production using cell factories requires stress-tolerant microbial hosts. The interspecies hybrid yeast Zygosaccharomyces parabailii has great potential to be exploited as a novel host for lactic acid production, due to high organic acid tolerance at low pH and a fermentative metabolism with a high growth rate. Here we used mRNA sequencing (RNA-seq) to analyze Z. parabailii 's transcriptional response to lactic acid added exogenously, and we explore the biological mechanisms involved in tolerance. Z. parabailii contains two homeologous copies of most genes. Under lactic acid stress, the two genes in each homeolog pair tend to diverge in expression to a significantly greater extent than under control conditions, indicating that stress tolerance is facilitated by interactions between the two gene sets in the hybrid. Lactic acid induces downregulation of genes related to cell wall and plasma membrane functions, possibly altering the rate of diffusion of lactic acid into cells. Genes related to iron transport and redox processes were upregulated, suggesting an important role for respiratory functions and oxidative stress defense. We found differences in the expression profiles of genes putatively regulated by Haa1 and Aft1/Aft2, previously described as lactic acid responsive in Saccharomyces cerevisiae Furthermore, formate dehydrogenase ( FDH ) genes form a lactic acid-responsive gene family that has been specifically amplified in Z. parabailii in comparison to other closely related species. Our study provides a useful starting point for the engineering of Z. parabailii as a host for lactic acid production. IMPORTANCE Hybrid yeasts are important in biotechnology because of their tolerance to harsh industrial conditions. The molecular mechanisms of tolerance can be studied by analyzing differential gene expression under conditions of interest and relating gene expression patterns

Capsella rubella TGA4, a bZIP transcription factor, causes delayed flowering in Arabidopsis thaliana

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Li Maofu

2016-01-01

Full Text Available Flowering time is usually regulated by many environmental factors and endogenous signals. TGA family members are bZIP transcription factors that bind to the octopine synthase element, which has been closely linked to defense/stress responses. Most TGA factors interact with non-expressor of PR1 (NPR1 and plant defense responses are strengthened by this interaction. TGA1and TGA4factors bind to NPR1 only in salicylic acid (SA-induced leaves, suggesting that TGA4 has another function during plant development. Here, we isolated a bZIP transcription factor gene, TGA4, from Capsella rubella. TGA4transcripts were detected in most tissues, with high expression in leaves, low expression in stems and flowering buds, and undetectable in siliques. CruTGA4was over expressed in Arabidopsis thaliana wild typeCol-0 plants. Flowering time and total leaf number in the transgenic plants showed that overexpression of CruTGA4could delay flowering in A. thaliana. Our findings suggest that TGA4 may act as flowering regulator that controls plant flowering.

A WRKY transcription factor from Withania somnifera regulates triterpenoid withanolide accumulation and biotic stress tolerance through modulation of phytosterol and defense pathways.

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Singh, Anup Kumar; Kumar, Sarma Rajeev; Dwivedi, Varun; Rai, Avanish; Pal, Shaifali; Shasany, Ajit K; Nagegowda, Dinesh A

2017-08-01

Withania somnifera produces pharmacologically important triterpenoid withanolides that are derived via phytosterol pathway; however, their biosynthesis and regulation remain to be elucidated. A jasmonate- and salicin-inducible WRKY transcription factor from W. somnifera (WsWRKY1) exhibiting correlation with withaferin A accumulation was functionally characterized employing virus-induced gene silencing and overexpression studies combined with transcript and metabolite analyses, and chromatin immunoprecipitation assay. WsWRKY1 silencing resulted in stunted plant growth, reduced transcripts of phytosterol pathway genes with corresponding reduction in phytosterols and withanolides in W. somnifera. Its overexpression elevated the biosynthesis of triterpenoids in W. somnifera (phytosterols and withanolides), as well as tobacco and tomato (phytosterols). Moreover, WsWRKY1 binds to W-box sequences in promoters of W. somnifera genes encoding squalene synthase and squalene epoxidase, indicating its direct regulation of triterpenoid pathway. Furthermore, while WsWRKY1 silencing in W. somnifera compromised the tolerance to bacterial growth, fungal infection, and insect feeding, its overexpression in tobacco led to improved biotic stress tolerance. Together these findings demonstrate that WsWRKY1 has a positive regulatory role on phytosterol and withanolides biosynthesis, and defense against biotic stress, highlighting its importance as a metabolic engineering tool for simultaneous improvement of triterpenoid biosynthesis and plant defense. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

AP2/ERF Transcription Factors Involved in Response to Tomato Yellow Leaf Curly Virus in Tomato

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Ying Huang

2016-07-01

Full Text Available Tomato yellow leaf curly virus (TYLCV, transmitted by the whitefly (, causes leaf curling and yellowing, plant dwarfism, and growth inhibition in tomato ( L.. The APETALA2 (AP2 and ethylene response factor (ERF transcription factor (TF family, the largest plant-specific TF family, was identified to function in plant development and pathogen defense. Our study aimed to analyze the mechanism underlying the function of ERF (SlERF TFs in response to TYLCV infection and improve useful information to increase the resistance to TYLCV in tomato. A total of 22 tomato AP2/ERF TFs in response to TYLCV were identified according to transcriptome database. Five ERF-B3 TFs were identified in cultivars Hongbeibei (highly resistant, Zheza-301, Zhefen-702 (both resistant, Jinpeng-1, and Xianke-6 (both susceptible. Interaction network indicated that SlERF TFs could interact with mitogen-activated protein kinase (MAPK. Expression profiles of five ERF-B3 genes (, , , , and were detected by quantitative real-time–polymerase chain reaction (qRT-PCR after TYLCV infection in five tomato cultivars. expression was upregulated in five tomato cultivars. The expressions of three genes (, , and were upregulated in Zheza-301 and Zhefen-702. and expressions were downregulated in Hongbeibei and Xianke-6, respectively. Yeast one-hybrid showed that the GCC-box binding ability of ERF-B3 TFs differed in resistant and susceptible tomato cultivars. Expression profiles were related to the GCC-box binding ability of SlERF TFs in resistant and susceptible tomato cultivars. The defense mechanism underlying the tomato’s response to TYLCV involved a complicated network, which provided important information for us in breeding and genetic analysis.

Larval Helicoverpa zea Transcriptional, Growth and Behavioral Responses to Nicotine and Nicotiana tabacum

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Linus Gog

2014-09-01

Full Text Available The polyphagous feeding habits of the corn earworm, Helicoverpa zea (Boddie, underscore its status as a major agricultural pest with a wide geographic distribution and host plant repertoire. To study the transcriptomic response to toxins in diet, we conducted a microarray analysis of H. zea caterpillars feeding on artificial diet, diet laced with nicotine and Nicotiana tabacum (L. plants. We supplemented our analysis with growth and aversion bioassays. The transcriptome reflects an abundant expression of proteases, chitin, cytochrome P450 and immune-related genes, many of which are shared between the two experimental treatments. However, the tobacco treatment tended to elicit stronger transcriptional responses than nicotine-laced diet. The salivary factor glucose oxidase, known to suppress nicotine induction in the plant, was upregulated by H. zea in response to tobacco but not to nicotine-laced diet. Reduced caterpillar growth rates accompanied the broad regulation of genes associated with growth, such as juvenile hormone epoxide hydrolase. The differential expression of chemosensory proteins, such as odorant binding-protein-2 precursor, as well as the neurotransmitter nicotinic-acetylcholine-receptor subunit 9, highlights candidate genes regulating aversive behavior towards nicotine. We suggest that an observed coincidental rise in cannibalistic behavior and regulation of proteases and protease inhibitors in H. zea larvae signify a compensatory response to induced plant defenses.

RNA-Seq analysis of Citrus reticulata in the early stages of Xylella fastidiosa infection reveals auxin-related genes as a defense response.

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Rodrigues, Carolina M; de Souza, Alessandra A; Takita, Marco A; Kishi, Luciano T; Machado, Marcos A

2013-10-03

Citrus variegated chlorosis (CVC), caused by Xylella fastidiosa, is one the most important citrus diseases, and affects all varieties of sweet orange (Citrus sinensis L. Osb). On the other hand, among the Citrus genus there are different sources of resistance against X. fastidiosa. For these species identifying these defense genes could be an important step towards obtaining sweet orange resistant varieties through breeding or genetic engineering. To assess these genes we made use of mandarin (C. reticulata Blanco) that is known to be resistant to CVC and shares agronomical characteristics with sweet orange. Thus, we investigated the gene expression in Ponkan mandarin at one day after infection with X. fastidiosa, using RNA-seq. A set of genes considered key elements in the resistance was used to confirm its regulation in mandarin compared with the susceptible sweet orange. Gene expression analysis of mock inoculated and infected tissues of Ponkan mandarin identified 667 transcripts repressed and 724 significantly induced in the later. Among the induced transcripts, we identified genes encoding proteins similar to Pattern Recognition Receptors. Furthermore, many genes involved in secondary metabolism, biosynthesis and cell wall modification were upregulated as well as in synthesis of abscisic acid, jasmonic acid and auxin. This work demonstrated that the defense response to the perception of bacteria involves cell wall modification and activation of hormone pathways, which probably lead to the induction of other defense-related genes. We also hypothesized the induction of auxin-related genes indicates that resistant plants initially recognize X. fastidiosa as a necrotrophic pathogen.

Overcompensation of herbivore reproduction through hyper-suppression of plant defenses in response to competition.

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Schimmel, Bernardus C J; Ataide, Livia M S; Chafi, Rachid; Villarroel, Carlos A; Alba, Juan M; Schuurink, Robert C; Kant, Merijn R

2017-06-01

Spider mites are destructive arthropod pests on many crops. The generalist herbivorous mite Tetranychus urticae induces defenses in tomato (Solanum lycopersicum) and this constrains its fitness. By contrast, the Solanaceae-specialist Tetranychus evansi maintains a high reproductive performance by suppressing tomato defenses. Tetranychus evansi outcompetes T. urticae when infesting the same plant, but it is unknown whether this is facilitated by the defenses of the plant. We assessed the extent to which a secondary infestation by a competitor affects local plant defense responses (phytohormones and defense genes), mite gene expression and mite performance. We observed that T. evansi switches to hyper-suppression of defenses after its tomato host is also invaded by its natural competitor T. urticae. Jasmonate (JA) and salicylate (SA) defenses were suppressed more strongly, albeit only locally at the feeding site of T. evansi, upon introduction of T. urticae to the infested leaflet. The hyper-suppression of defenses coincided with increased expression of T. evansi genes coding for salivary defense-suppressing effector proteins and was paralleled by an increased reproductive performance. Together, these observations suggest that T. evansi overcompensates its reproduction through hyper-suppression of plant defenses in response to nearby competitors. We hypothesize that the competitor-induced overcompensation promotes competitive population growth of T. evansi on tomato. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

IBR5 Modulates Temperature-Dependent, R Protein CHS3-Mediated Defense Responses in Arabidopsis.

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Jingyan Liu

2015-10-01

Full Text Available Plant responses to low temperature are tightly associated with defense responses. We previously characterized the chilling-sensitive mutant chs3-1 resulting from the activation of the Toll and interleukin 1 receptor-nucleotide binding-leucine-rich repeat (TIR-NB-LRR-type resistance (R protein harboring a C-terminal LIM (Lin-11, Isl-1 and Mec-3 domains domain. Here we report the identification of a suppressor of chs3, ibr5-7 (indole-3-butyric acid response 5, which largely suppresses chilling-activated defense responses. IBR5 encodes a putative dual-specificity protein phosphatase. The accumulation of CHS3 protein at chilling temperatures is inhibited by the IBR5 mutation. Moreover, chs3-conferred defense phenotypes were synergistically suppressed by mutations in HSP90 and IBR5. Further analysis showed that IBR5, with holdase activity, physically associates with CHS3, HSP90 and SGT1b (Suppressor of the G2 allele of skp1 to form a complex that protects CHS3. In addition to the positive role of IBR5 in regulating CHS3, IBR5 is also involved in defense responses mediated by R genes, including SNC1 (Suppressor of npr1-1, Constitutive 1, RPS4 (Resistance to P. syringae 4 and RPM1 (Resistance to Pseudomonas syringae pv. maculicola 1. Thus, the results of the present study reveal a role for IBR5 in the regulation of multiple R protein-mediated defense responses.

Global Transcriptional Responses to Osmotic, Oxidative, and Imipenem Stress Conditions in Pseudomonas putida.

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Bojanovič, Klara; D'Arrigo, Isotta; Long, Katherine S

2017-04-01

Bacteria cope with and adapt to stress by modulating gene expression in response to specific environmental cues. In this study, the transcriptional response of Pseudomonas putida KT2440 to osmotic, oxidative, and imipenem stress conditions at two time points was investigated via identification of differentially expressed mRNAs and small RNAs (sRNAs). A total of 440 sRNA transcripts were detected, of which 10% correspond to previously annotated sRNAs, 40% to novel intergenic transcripts, and 50% to novel transcripts antisense to annotated genes. Each stress elicits a unique response as far as the extent and dynamics of the transcriptional changes. Nearly 200 protein-encoding genes exhibited significant changes in all stress types, implicating their participation in a general stress response. Almost half of the sRNA transcripts were differentially expressed under at least one condition, suggesting possible functional roles in the cellular response to stress conditions. The data show a larger fraction of differentially expressed sRNAs than of mRNAs with >5-fold expression changes. The work provides detailed insights into the mechanisms through which P. putida responds to different stress conditions and increases understanding of bacterial adaptation in natural and industrial settings. IMPORTANCE This study maps the complete transcriptional response of P. putida KT2440 to osmotic, oxidative, and imipenem stress conditions at short and long exposure times. Over 400 sRNA transcripts, consisting of both intergenic and antisense transcripts, were detected, increasing the number of identified sRNA transcripts in the strain by a factor of 10. Unique responses to each type of stress are documented, including both the extent and dynamics of the gene expression changes. The work adds rich detail to previous knowledge of stress response mechanisms due to the depth of the RNA sequencing data. Almost half of the sRNAs exhibit significant expression changes under at least one

Glufosinate Ammonium-Induced Pathogen Inhibition and Defense Responses Culminate in Disease Protection in bar-Transgenic Rice1[C

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Ahn, Il-Pyung

2008-01-01

Glufosinate ammonium diminished developments of rice (Oryza sativa) blast and brown leaf spot in 35S:bar-transgenic rice. Pre- and postinoculation treatments of this herbicide reduced disease development. Glufosinate ammonium specifically impeded appressorium formation of the pathogens Magnaporthe grisea and Cochliobolus miyabeanus on hydrophobic surface and on transgenic rice. In contrast, conidial germination remained unaffected. Glufosinate ammonium diminished mycelial growth of two pathogens; however, this inhibitory effect was attenuated in malnutrition conditions. Glufosinate ammonium caused slight chlorosis and diminished chlorophyll content; however, these alterations were almost completely restored in transgenic rice within 7 d. Glufosinate ammonium triggered transcriptions of PATHOGENESIS-RELATED (PR) genes and hydrogen peroxide accumulation in transgenic rice and PR1 transcription in Arabidopsis (Arabidopsis thaliana) wild-type ecotype Columbia harboring 35S:bar construct. All transgenic Arabidopsis showed robust hydrogen peroxide accumulation by glufosinate ammonium. This herbicide also induced PR1 transcription in etr1 and jar1 expressing bar; however, no expression was observed in NahG and npr1. Fungal infection did not alter transcriptions of PR genes and hydrogen peroxide accumulation induced by glufosinate ammonium. Infiltration of glufosinate ammonium did not affect appressorium formation of M. grisea in vivo but inhibited blast disease development. Hydrogen peroxide scavengers nullified blast protection and transcriptions of PR genes by glufosinate ammonium; however, they did not affect brown leaf spot progression. In sum, both direct inhibition of pathogen infection and activation of defense systems were responsible for disease protection in bar-transgenic rice. PMID:17981989

Ascorbate oxidase-dependent changes in the redox state of the apoplast modulate gene transcript accumulation leading to modified hormone signaling and orchestration of defense processes in tobacco.

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Pignocchi, Cristina; Kiddle, Guy; Hernández, Iker; Foster, Simon J; Asensi, Amparo; Taybi, Tahar; Barnes, Jeremy; Foyer, Christine H

2006-06-01

The role of the redox state of the apoplast in hormone responses, signaling cascades, and gene expression was studied in transgenic tobacco (Nicotiana tabacum) plants with modified cell wall-localized ascorbate oxidase (AO). High AO activity specifically decreased the ascorbic acid (AA) content of the apoplast and altered plant growth responses triggered by hormones. Auxin stimulated shoot growth only when the apoplastic AA pool was reduced in wild-type or AO antisense lines. Oxidation of apoplastic AA in AO sense lines was associated with loss of the auxin response, higher mitogen-activated protein kinase activities, and susceptibility to a virulent strain of the pathogen Pseudomonas syringae. The total leaf glutathione pool, the ratio of reduced glutathione to glutathione disulfide, and glutathione reductase activities were similar in the leaves of all lines. However, AO sense leaves exhibited significantly lower dehydroascorbate reductase and ascorbate peroxidase activities than wild-type and antisense leaves. The abundance of mRNAs encoding antioxidant enzymes was similar in all lines. However, the day/night rhythms in the abundance of transcripts encoding the three catalase isoforms were changed in response to the AA content of the apoplast. Other transcripts influenced by AO included photorespiratory genes and a plasma membrane Ca(2+) channel-associated gene. We conclude that the redox state of the apoplast modulates plant growth and defense responses by regulating signal transduction cascades and gene expression patterns. Hence, AO activity, which modulates the redox state of the apoplastic AA pool, strongly influences the responses of plant cells to external and internal stimuli.

Enhancement of defense responses by oligandrin against Botrytis ...

African Journals Online (AJOL)

Oligandrin is an elicitin-like protein with a molecular mass of ∼10 kDa secreted by Pythium oligandrum. Here, the effect of oligandrin on defense response against Botrytis cinerea in tomato leaves is reported. Tomato seedlings were pretreated with 5 ml oligandrin (10 g/ml) by root submerging and then inoculated with B.

Metagenomic screening for aromatic compound-responsive transcriptional regulators.

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Taku Uchiyama

Full Text Available We applied a metagenomics approach to screen for transcriptional regulators that sense aromatic compounds. The library was constructed by cloning environmental DNA fragments into a promoter-less vector containing green fluorescence protein. Fluorescence-based screening was then performed in the presence of various aromatic compounds. A total of 12 clones were isolated that fluoresced in response to salicylate, 3-methyl catechol, 4-chlorocatechol and chlorohydroquinone. Sequence analysis revealed at least 1 putative transcriptional regulator, excluding 1 clone (CHLO8F. Deletion analysis identified compound-specific transcriptional regulators; namely, 8 LysR-types, 2 two-component-types and 1 AraC-type. Of these, 9 representative clones were selected and their reaction specificities to 18 aromatic compounds were investigated. Overall, our transcriptional regulators were functionally diverse in terms of both specificity and induction rates. LysR- and AraC- type regulators had relatively narrow specificities with high induction rates (5-50 fold, whereas two-component-types had wide specificities with low induction rates (3 fold. Numerous transcriptional regulators have been deposited in sequence databases, but their functions remain largely unknown. Thus, our results add valuable information regarding the sequence-function relationship of transcriptional regulators.

The Two Translationally Controlled Tumor Protein Genes, CsTCTP1 and CsTCTP2, Are Negative Modulators in the Cucumis sativus Defense Response to Sphaerotheca fuliginea

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Xiangnan Meng

2018-04-01

Full Text Available Pathogen stress often significantly decreases cucumber production. However, knowledge regarding the molecular mechanism and signals of cucumber disease resistance is far from complete. Here, we report two translationally controlled tumor protein genes, CsTCTP1 and CsTCTP2, that are both negative modulators in the Cucumis sativus defense response to Sphaerotheca fuliginea. Subcellular localization analysis showed that CsTCTP1 and CsTCTP2 were both localized in the cytoplasm. Expression analysis indicated that the transcript levels of CsTCTP1 and CsTCTP2 were linked to the degree of cucumber resistance to S. fuliginea. Transient overexpression of either CsTCTP1 or CsTCTP2 in cucumber cotyledons impaired resistance to S. fuliginea, whereas silencing of either CsTCTP1 or CsTCTP2 enhanced cucumber resistance to S. fuliginea. The relationship of several defense-related genes and ABA and target of rapamycin (TOR signaling pathway-related genes to the overexpressing and silencing of CsTCTP1/CsTCTP2 in non-infested cucumber plants was investigated. The results indicated that CsTCTP1 participates in the defense response to S. fuliginea by regulating the expression of certain defense-associated genes and/or ABA signaling pathway-associated genes, and CsTCTP2 participates through regulating the expression of TOR signaling pathway-associated genes. Our findings will guide enhancing the resistance of cucumber to powdery mildew.

Integrated mRNA and microRNA analysis identifies genes and small miRNA molecules associated with transcriptional and post-transcriptional-level responses to both drought stress and re-watering treatment in tobacco.

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Chen, Qiansi; Li, Meng; Zhang, Zhongchun; Tie, Weiwei; Chen, Xia; Jin, Lifeng; Zhai, Niu; Zheng, Qingxia; Zhang, Jianfeng; Wang, Ran; Xu, Guoyun; Zhang, Hui; Liu, Pingping; Zhou, Huina

2017-01-10

Drought stress is one of the most severe problem limited agricultural productivity worldwide. It has been reported that plants response to drought-stress by sophisticated mechanisms at both transcriptional and post-transcriptional levels. However, the precise molecular mechanisms governing the responses of tobacco leaves to drought stress and water status are not well understood. To identify genes and miRNAs involved in drought-stress responses in tobacco, we performed both mRNA and small RNA sequencing on tobacco leaf samples from the following three treatments: untreated-control (CL), drought stress (DL), and re-watering (WL). In total, we identified 798 differentially expressed genes (DEGs) between the DL and CL (DL vs. CL) treatments and identified 571 DEGs between the WL and DL (WL vs. DL) treatments. Further analysis revealed 443 overlapping DEGs between the DL vs. CL and WL vs. DL comparisons, and, strikingly, all of these genes exhibited opposing expression trends between these two comparisons, strongly suggesting that these overlapping DEGs are somehow involved in the responses of tobacco leaves to drought stress. Functional annotation analysis showed significant up-regulation of genes annotated to be involved in responses to stimulus and stress, (e.g., late embryogenesis abundant proteins and heat-shock proteins) antioxidant defense (e.g., peroxidases and glutathione S-transferases), down regulation of genes related to the cell cycle pathway, and photosynthesis processes. We also found 69 and 56 transcription factors (TFs) among the DEGs in, respectively, the DL vs. CL and the WL vs. DL comparisons. In addition, small RNA sequencing revealed 63 known microRNAs (miRNA) from 32 families and 368 novel miRNA candidates in tobacco. We also found that five known miRNA families (miR398, miR390, miR162, miR166, and miR168) showed differential regulation under drought conditions. Analysis to identify negative correlations between the differentially expressed mi

NFE2-Related Transcription Factor 2 Coordinates Antioxidant Defense with Thyroglobulin Production and Iodination in the Thyroid Gland.

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Ziros, Panos G; Habeos, Ioannis G; Chartoumpekis, Dionysios V; Ntalampyra, Eleni; Somm, Emmanuel; Renaud, Cédric O; Bongiovanni, Massimo; Trougakos, Ioannis P; Yamamoto, Masayuki; Kensler, Thomas W; Santisteban, Pilar; Carrasco, Nancy; Ris-Stalpers, Carrie; Amendola, Elena; Liao, Xiao-Hui; Rossich, Luciano; Thomasz, Lisa; Juvenal, Guillermo J; Refetoff, Samuel; Sykiotis, Gerasimos P

2018-06-01

The thyroid gland has a special relationship with oxidative stress. While generation of oxidative substances is part of normal iodide metabolism during thyroid hormone synthesis, the gland must also defend itself against excessive oxidation in order to maintain normal function. Antioxidant and detoxification enzymes aid thyroid cells to maintain homeostasis by ameliorating oxidative insults, including during exposure to excess iodide, but the factors that coordinate their expression with the cellular redox status are not known. The antioxidant response system comprising the ubiquitously expressed NFE2-related transcription factor 2 (Nrf2) and its redox-sensitive cytoplasmic inhibitor Kelch-like ECH-associated protein 1 (Keap1) defends tissues against oxidative stress, thereby protecting against pathologies that relate to DNA, protein, and/or lipid oxidative damage. Thus, it was hypothesized that Nrf2 should also have important roles in maintaining thyroid homeostasis. Ubiquitous and thyroid-specific male C57BL6J Nrf2 knockout (Nrf2-KO) mice were studied. Plasma and thyroids were harvested for evaluation of thyroid function tests by radioimmunoassays and of gene and protein expression by real-time polymerase chain reaction and immunoblotting, respectively. Nrf2-KO and Keap1-KO clones of the PCCL3 rat thyroid follicular cell line were generated using CRISPR/Cas9 technology and were used for gene and protein expression studies. Software-predicted Nrf2 binding sites on the thyroglobulin enhancer were validated by site-directed in vitro mutagenesis and chromatin immunoprecipitation. The study shows that Nrf2 mediates antioxidant transcriptional responses in thyroid cells and protects the thyroid from oxidation induced by iodide overload. Surprisingly, it was also found that Nrf2 has a dramatic impact on both the basal abundance and the thyrotropin-inducible intrathyroidal abundance of thyroglobulin (Tg), the precursor protein of thyroid hormones. This effect is mediated

The transcriptional response of microbial communities in thawing Alaskan permafrost soils

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Coolen, Marco J. L.; Orsi, William D.

2015-01-01

Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gasses, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throughput Illumina HiSeq sequencing of reverse transcribed messenger RNA to obtain a detailed overview of active metabolic pathways and responsible organisms in up to 70 cm deep permafrost soils at a moist acidic tundra location in Arctic Alaska. The transcriptional response of the permafrost microbial community was compared before and after 11 days of thaw. In general, the transcriptional profile under frozen conditions suggests a dominance of stress responses, survival strategies, and maintenance processes, whereas upon thaw a rapid enzymatic response to decomposing soil organic matter (SOM) was observed. Bacteroidetes, Firmicutes, ascomycete fungi, and methanogens were responsible for largest transcriptional response upon thaw. Transcripts indicative of heterotrophic methanogenic pathways utilizing acetate, methanol, and methylamine were found predominantly in the permafrost table after thaw. Furthermore, transcripts involved in acetogenesis were expressed exclusively after thaw suggesting that acetogenic bacteria are a potential source of acetate for acetoclastic methanogenesis in freshly thawed permafrost. Metatranscriptomics is shown here to be a useful approach for inferring the activity of permafrost microbes that has potential to improve our understanding of permafrost SOM bioavailability and biogeochemical mechanisms contributing to greenhouse gas emissions as a result of permafrost thaw. PMID:25852660

The transcriptional response of microbial communities in thawing Alaskan permafrost soils

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M J L Coolen

2015-03-01

Full Text Available Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gases, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throughput Illumina HiSeq sequencing of reverse transcribed messenger RNA to obtain a detailed overview of active metabolic pathways and responsible organisms in up to 70 cm deep permafrost soils at a moist acidic tundra location in Arctic Alaska. The transcriptional response of the permafrost microbial community was compared before and after eleven days of thaw. In general, the transcriptional profile under frozen conditions suggests a dominance of stress responses, survival strategies, and maintenance processes, whereas upon thaw a rapid enzymatic response to decomposing soil organic matter (SOM was observed. Bacteroidetes, Firmicutes, ascomycete fungi, and methanogens were responsible for largest transcriptional response upon thaw. Transcripts indicative of heterotrophic methanogenic pathways utilizing acetate, methanol, and methylamine were found predominantly in the permafrost table after thaw. Furthermore, transcripts involved in acetogenesis were expressed exclusively after thaw suggesting that acetogenic bacteria are a potential source of acetate for acetoclastic methanogenesis in freshly thawed permafrost. Metatranscriptomics is shown here to be a useful approach for inferring the activity of permafrost microbes that has potential to improve our understanding of permafrost SOM bioavailability and biogeochemical mechanisms contributing to greenhouse gas emissions as a result of permafrost thaw.

Promoter-Based Integration in Plant Defense Regulation

DEFF Research Database (Denmark)

Li, Baohua; Gaudinier, Allison; Tang, Michelle

2014-01-01

A key unanswered question in plant biology is how a plant regulates metabolism to maximize performance across an array of biotic and abiotic environmental stresses. In this study, we addressed the potential breadth of transcriptional regulation that can alter accumulation of the defensive...... glucosinolate metabolites in Arabidopsis (Arabidopsis thaliana). A systematic yeast one-hybrid study was used to identify hundreds of unique potential regulatory interactions with a nearly complete complement of 21 promoters for the aliphatic glucosinolate pathway. Conducting high-throughput phenotypic...... validation, we showed that >75% of tested transcription factor (TF) mutants significantly altered the accumulation of the defensive glucosinolates. These glucosinolate phenotypes were conditional upon the environment and tissue type, suggesting that these TFs may allow the plant to tune its defenses...

Phytohormone signaling pathway analysis method for comparing hormone responses in plant-pest interactions

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Studham Matthew E

2012-07-01

Full Text Available Abstract Background Phytohormones mediate plant defense responses to pests and pathogens. In particular, the hormones jasmonic acid, ethylene, salicylic acid, and abscisic acid have been shown to dictate and fine-tune defense responses, and identification of the phytohormone components of a particular defense response is commonly used to characterize it. Identification of phytohormone regulation is particularly important in transcriptome analyses. Currently there is no computational tool to determine the relative activity of these hormones that can be applied to transcriptome analyses in soybean. Findings We developed a pathway analysis method that provides a broad measure of the activation or suppression of individual phytohormone pathways based on changes in transcript expression of pathway-related genes. The magnitude and significance of these changes are used to determine a pathway score for a phytohormone for a given comparison in a microarray experiment. Scores for individual hormones can then be compared to determine the dominant phytohormone in a given defense response. To validate this method, it was applied to publicly available data from previous microarray experiments that studied the response of soybean plants to Asian soybean rust and soybean cyst nematode. The results of the analyses for these experiments agreed with our current understanding of the role of phytohormones in these defense responses. Conclusions This method is useful in providing a broad measure of the relative induction and suppression of soybean phytohormones during a defense response. This method could be used as part of microarray studies that include individual transcript analysis, gene set analysis, and other methods for a comprehensive defense response characterization.

The MAP kinase substrate MKS1 is a regulator of plant defense responses

DEFF Research Database (Denmark)

Andreasson, E.; Jenkins, T.; Brodersen, P.

2005-01-01

Arabidopsis MAP kinase 4 (MPK4) functions as a regulator of pathogen defense responses, because it is required for both repression of salicylic acid (SA)-dependent resistance and for activation of jasmonate (JA)-dependent defense gene expression. To understand MPK4 signaling mechanisms, we used...

Both live and dead Enterococci activate Caenorhabditis elegans host defense via immune and stress pathways.

Science.gov (United States)

Yuen, Grace J; Ausubel, Frederick M

2018-12-31

The innate immune response of the nematode Caenorhabditis elegans has been extensively studied and a variety of Toll-independent immune response pathways have been identified. Surprisingly little, however, is known about how pathogens activate the C. elegans immune response. Enterococcus faecalis and Enterococcus faecium are closely related enterococcal species that exhibit significantly different levels of virulence in C. elegans infection models. Previous work has shown that activation of the C. elegans immune response by Pseudomonas aeruginosa involves P. aeruginosa-mediated host damage. Through ultrastructural imaging, we report that infection with either E. faecalis or E. faecium causes the worm intestine to become distended with proliferating bacteria in the absence of extensive morphological changes and apparent physical damage. Genetic analysis, whole-genome transcriptional profiling, and multiplexed gene expression analysis demonstrate that both enterococcal species, whether live or dead, induce a rapid and similar transcriptional defense response dependent upon previously described immune signaling pathways. The host response to E. faecium shows a stricter dependence upon stress response signaling pathways than the response to E. faecalis. Unexpectedly, we find that E. faecium is a C. elegans pathogen and that an active wild-type host defense response is required to keep an E. faecium infection at bay. These results provide new insights into the mechanisms underlying the C. elegans immune response to pathogen infection.

Herbivore Oral Secreted Bacteria Trigger Distinct Defense Responses in Preferred and Non-Preferred Host Plants.

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Wang, Jie; Chung, Seung Ho; Peiffer, Michelle; Rosa, Cristina; Hoover, Kelli; Zeng, Rensen; Felton, Gary W

2016-06-01

Insect symbiotic bacteria affect host physiology and mediate plant-insect interactions, yet there are few clear examples of symbiotic bacteria regulating defense responses in different host plants. We hypothesized that plants would induce distinct defense responses to herbivore- associated bacteria. We evaluated whether preferred hosts (horsenettle) or non-preferred hosts (tomato) respond similarly to oral secretions (OS) from the false potato beetle (FPB, Leptinotarsa juncta), and whether the induced defense triggered by OS was due to the presence of symbiotic bacteria in OS. Both horsenettle and tomato damaged by antibiotic (AB) treated larvae showed higher polyphenol oxidase (PPO) activity than those damaged by non-AB treated larvae. In addition, application of OS from AB treated larvae induced higher PPO activity compared with OS from non-AB treated larvae or water treatment. False potato beetles harbor bacteria that may provide abundant cues that can be recognized by plants and thus mediate corresponding defense responses. Among all tested bacterial isolates, the genera Pantoea, Acinetobacter, Enterobacter, and Serratia were found to suppress PPO activity in tomato, while only Pantoea sp. among these four isolates was observed to suppress PPO activity in horsenettle. The distinct PPO suppression caused by symbiotic bacteria in different plants was similar to the pattern of induced defense-related gene expression. Pantoea inoculated FPB suppressed JA-responsive genes and triggered a SA-responsive gene in both tomato and horsenettle. However, Enterobacter inoculated FPB eliminated JA-regulated gene expression and elevated SA-regulated gene expression in tomato, but did not show evident effects on the expression levels of horsenettle defense-related genes. These results indicate that suppression of plant defenses by the bacteria found in the oral secretions of herbivores may be a more widespread phenomenon than previously indicated.

The Role of the Transcriptional Response to DNA Replication Stress.

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Herlihy, Anna E; de Bruin, Robertus A M

2017-03-02

During DNA replication many factors can result in DNA replication stress. The DNA replication stress checkpoint prevents the accumulation of replication stress-induced DNA damage and the potential ensuing genome instability. A critical role for post-translational modifications, such as phosphorylation, in the replication stress checkpoint response has been well established. However, recent work has revealed an important role for transcription in the cellular response to DNA replication stress. In this review, we will provide an overview of current knowledge of the cellular response to DNA replication stress with a specific focus on the DNA replication stress checkpoint transcriptional response and its role in the prevention of replication stress-induced DNA damage.

The Role of the Transcriptional Response to DNA Replication Stress

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Herlihy, Anna E.; de Bruin, Robertus A.M.

2017-01-01

During DNA replication many factors can result in DNA replication stress. The DNA replication stress checkpoint prevents the accumulation of replication stress-induced DNA damage and the potential ensuing genome instability. A critical role for post-translational modifications, such as phosphorylation, in the replication stress checkpoint response has been well established. However, recent work has revealed an important role for transcription in the cellular response to DNA replication stress. In this review, we will provide an overview of current knowledge of the cellular response to DNA replication stress with a specific focus on the DNA replication stress checkpoint transcriptional response and its role in the prevention of replication stress-induced DNA damage. PMID:28257104

A genomic approach to identify regulatory nodes in the transcriptional network of systemic acquired resistance in plants.

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Dong Wang

2006-11-01

Full Text Available Many biological processes are controlled by intricate networks of transcriptional regulators. With the development of microarray technology, transcriptional changes can be examined at the whole-genome level. However, such analysis often lacks information on the hierarchical relationship between components of a given system. Systemic acquired resistance (SAR is an inducible plant defense response involving a cascade of transcriptional events induced by salicylic acid through the transcription cofactor NPR1. To identify additional regulatory nodes in the SAR network, we performed microarray analysis on Arabidopsis plants expressing the NPR1-GR (glucocorticoid receptor fusion protein. Since nuclear translocation of NPR1-GR requires dexamethasone, we were able to control NPR1-dependent transcription and identify direct transcriptional targets of NPR1. We show that NPR1 directly upregulates the expression of eight WRKY transcription factor genes. This large family of 74 transcription factors has been implicated in various defense responses, but no specific WRKY factor has been placed in the SAR network. Identification of NPR1-regulated WRKY factors allowed us to perform in-depth genetic analysis on a small number of WRKY factors and test well-defined phenotypes of single and double mutants associated with NPR1. Among these WRKY factors we found both positive and negative regulators of SAR. This genomics-directed approach unambiguously positioned five WRKY factors in the complex transcriptional regulatory network of SAR. Our work not only discovered new transcription regulatory components in the signaling network of SAR but also demonstrated that functional studies of large gene families have to take into consideration sequence similarity as well as the expression patterns of the candidates.

Orienting-defense responses and psychophysiological reactivity in isolated clinic versus sustained hypertension.

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García-Vera, María Paz; Sanz, Jesús; Labrador, Francisco J

2007-04-01

This study sought to determine whether patients with white-coat or isolated clinic hypertension (ICH) show, in comparison to patients with sustained hypertension (SH), a defense response pattern to novel stimuli and an enhanced psychophysiological reactivity to stress. Forty-three patients with essential hypertension were divided into two groups after 16 days of self-monitoring blood pressure (BP): ICH (24 men; self-measured BP men; self-measured BP >or= 135/85 mmHg). Defense responses were measured as the cardiac changes to phasic non-aversive auditory stimuli. Psychophysiological reactivity (heart and breath rate, blood volume pulse, electromyography, and skin conductance) was measured during mental arithmetic and video game tasks. The standard deviation of self-measured BPs and the difference between mean BPs at work and at home were used as indicators of cardiovascular reactivity to daily stress. No significant differences were seen in defense responses or psychophysiological reactivity to laboratory or naturally occurring stressors. These results do not support the hypothesis that ICH can be explained in terms of a generalized hyperreactivity to novel or stressful stimuli.

Control of Carbon Assimilation and Partitioning by Jasmonate: An Accounting of Growth–Defense Tradeoffs

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Nathan E. Havko

2016-01-01

Full Text Available Plant growth is often constrained by the limited availability of resources in the microenvironment. Despite the continuous threat of attack from insect herbivores and pathogens, investment in defense represents a lost opportunity to expand photosynthetic capacity in leaves and absorption of nutrients and water by roots. To mitigate the metabolic expenditure on defense, plants have evolved inducible defense strategies. The plant hormone jasmonate (JA is a key regulator of many inducible defenses. Synthesis of JA in response to perceived danger leads to the deployment of a variety of defensive structures and compounds, along with a potent inhibition of growth. Genetic studies have established an important role for JA in mediating tradeoffs between growth and defense. However, several gaps remain in understanding of how JA signaling inhibits growth, either through direct transcriptional control of JA-response genes or crosstalk with other signaling pathways. Here, we highlight recent progress in uncovering the role of JA in controlling growth-defense balance and its relationship to resource acquisition and allocation. We also discuss tradeoffs in the context of the ability of JA to promote increased leaf mass per area (LMA, which is a key indicator of leaf construction costs and leaf life span.

The transcription factor ABI4 Is required for the ascorbic acid-dependent regulation of growth and regulation of jasmonate-dependent defense signaling pathways in Arabidopsis.

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Kerchev, Pavel I; Pellny, Till K; Vivancos, Pedro Diaz; Kiddle, Guy; Hedden, Peter; Driscoll, Simon; Vanacker, Hélène; Verrier, Paul; Hancock, Robert D; Foyer, Christine H

2011-09-01

Cellular redox homeostasis is a hub for signal integration. Interactions between redox metabolism and the ABSCISIC ACID-INSENSITIVE-4 (ABI4) transcription factor were characterized in the Arabidopsis thaliana vitamin c defective1 (vtc1) and vtc2 mutants, which are defective in ascorbic acid synthesis and show a slow growth phenotype together with enhanced abscisic acid (ABA) levels relative to the wild type (Columbia-0). The 75% decrease in the leaf ascorbate pool in the vtc2 mutants was not sufficient to adversely affect GA metabolism. The transcriptome signatures of the abi4, vtc1, and vtc2 mutants showed significant overlap, with a large number of transcription factors or signaling components similarly repressed or induced. Moreover, lincomycin-dependent changes in LIGHT HARVESTING CHLOROPHYLL A/B BINDING PROTEIN 1.1 expression were comparable in these mutants, suggesting overlapping participation in chloroplast to nucleus signaling. The slow growth phenotype of vtc2 was absent in the abi4 vtc2 double mutant, as was the sugar-insensitive phenotype of the abi4 mutant. Octadecanoid derivative-responsive AP2/ERF-domain transcription factor 47 (ORA47) and AP3 (an ABI5 binding factor) transcripts were enhanced in vtc2 but repressed in abi4 vtc2, suggesting that ABI4 and ascorbate modulate growth and defense gene expression through jasmonate signaling. We conclude that low ascorbate triggers ABA- and jasmonate-dependent signaling pathways that together regulate growth through ABI4. Moreover, cellular redox homeostasis exerts a strong influence on sugar-dependent growth regulation.

How salicylic acid takes transcriptional control over jasmonic acid signaling

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Lotte eCaarls

2015-03-01

Full Text Available Transcriptional regulation is a central process in plant immunity. The induction or repression of defense genes is orchestrated by signaling networks that are directed by plant hormones of which salicylic acid (SA and jasmonic acid (JA are the major players. Extensive cross-communication between the hormone signaling pathways allows for fine tuning of transcriptional programs, determining resistance to invaders and trade-offs with plant development. Here, we give an overview of how SA can control transcriptional reprogramming of JA-induced genes in Arabidopsis thaliana. SA can influence activity and/or localization of transcriptional regulators by post-translational modifications of transcription factors and co-regulators. SA-induced redox changes, mediated by thioredoxins and glutaredoxins, modify transcriptional regulators that are involved in suppression of JA-dependent genes, such as NPR1 and TGA transcription factors, which affects their localization or DNA binding activity. Furthermore, SA can mediate sequestering of JA-responsive transcription factors away from their target genes by stalling them in the cytosol or in complexes with repressor proteins in the nucleus. SA also affects JA-induced transcription by inducing degradation of transcription factors with an activating role in JA signaling, as was shown for the ERF transcription factor ORA59. Additionally, SA can induce negative regulators, among which WRKY transcription factors, that can directly or indirectly inhibit JA-responsive gene expression. Finally, at the DNA level, modification of histones by SA-dependent factors can result in repression of JA-responsive genes. These diverse and complex regulatory mechanisms affect important signaling hubs in the integration of hormone signaling networks. Some pathogens have evolved effectors that highjack hormone crosstalk mechanisms for their own good, which are described in this review as well.

Global transcriptional responses of Bacillus subtilis to xenocoumacin 1.

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Zhou, T; Zeng, H; Qiu, D; Yang, X; Wang, B; Chen, M; Guo, L; Wang, S

2011-09-01

To determine the global transcriptional response of Bacillus subtilis to an antimicrobial agent, xenocoumacin 1 (Xcn1). Subinhibitory concentration of Xcn1 applied to B. subtilis was measured according to Hutter's method for determining optimal concentrations. cDNA microarray technology was used to study the global transcriptional response of B. subtilis to Xcn1. Real-time RT-PCR was employed to verify alterations in the transcript levels of six genes. The subinhibitory concentration was determined to be 1 μg ml(-1). The microarray data demonstrated that Xcn1 treatment of B. subtilis led to more than a 2.0-fold up-regulation of 480 genes and more than a 2.0-fold down-regulation of 479 genes (q ≤ 0.05). The transcriptional responses of B. subtilis to Xcn1 were determined, and several processes were affected by Xcn1. Additionally, cluster analysis of gene expression profiles after treatment with Xcn1 or 37 previously studied antibiotics indicated that Xcn1 has similar mechanisms of action to protein synthesis inhibitors. These microarray data showed alterations of gene expression in B. subtilis after exposure to Xcn1. From the results, we identified various processes affected by Xcn1. This study provides a whole-genome perspective to elucidate the action of Xcn1 as a potential antimicrobial agent. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

Pipecolic Acid Orchestrates Plant Systemic Acquired Resistance and Defense Priming via Salicylic Acid-Dependent and -Independent Pathways.

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Bernsdorff, Friederike; Döring, Anne-Christin; Gruner, Katrin; Schuck, Stefan; Bräutigam, Andrea; Zeier, Jürgen

2016-01-01

We investigated the relationships of the two immune-regulatory plant metabolites, salicylic acid (SA) and pipecolic acid (Pip), in the establishment of plant systemic acquired resistance (SAR), SAR-associated defense priming, and basal immunity. Using SA-deficient sid2, Pip-deficient ald1, and sid2 ald1 plants deficient in both SA and Pip, we show that SA and Pip act both independently from each other and synergistically in Arabidopsis thaliana basal immunity to Pseudomonas syringae. Transcriptome analyses reveal that SAR establishment in Arabidopsis is characterized by a strong transcriptional response systemically induced in the foliage that prepares plants for future pathogen attack by preactivating multiple stages of defense signaling and that SA accumulation upon SAR activation leads to the downregulation of photosynthesis and attenuated jasmonate responses systemically within the plant. Whereas systemic Pip elevations are indispensable for SAR and necessary for virtually the whole transcriptional SAR response, a moderate but significant SA-independent component of SAR activation and SAR gene expression is revealed. During SAR, Pip orchestrates SA-dependent and SA-independent priming of pathogen responses in a FLAVIN-DEPENDENT-MONOOXYGENASE1 (FMO1)-dependent manner. We conclude that a Pip/FMO1 signaling module acts as an indispensable switch for the activation of SAR and associated defense priming events and that SA amplifies Pip-triggered responses to different degrees in the distal tissue of SAR-activated plants. © 2016 American Society of Plant Biologists. All rights reserved.

Circulating RNA transcripts identify therapeutic response in cystic fibrosis lung disease.

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Saavedra, Milene T; Hughes, Grant J; Sanders, Linda A; Carr, Michelle; Rodman, David M; Coldren, Christopher D; Geraci, Mark W; Sagel, Scott D; Accurso, Frank J; West, James; Nick, Jerry A

2008-11-01

Circulating leukocyte RNA transcripts are systemic markers of inflammation, which have not been studied in cystic fibrosis (CF) lung disease. Although the standard assessment of pulmonary treatment response is FEV(1), a measure of airflow limitation, the lack of systemic markers to reflect changes in lung inflammation critically limits the testing of proposed therapeutics. We sought to prospectively identify and validate peripheral blood leukocyte genes that could mark resolution of pulmonary infection and inflammation using a model by which RNA transcripts could increase the predictive value of spirometry. Peripheral blood mononuclear cells were isolated from 10 patients with CF and acute pulmonary exacerbations before and after therapy. RNA expression profiling revealed that 10 genes significantly changed with treatment when compared with matched non-CF and control subjects with stable CF to establish baseline transcript abundance. Peripheral blood mononuclear cell RNA transcripts were prospectively validated, using real-time polymerase chain reaction amplification, in an independent cohort of acutely ill patients with CF (n = 14). Patients who responded to therapy were analyzed using general estimating equations and multiple logistic regression, such that changes in FEV(1)% predicted were regressed with transcript changes. Three genes, CD64, ADAM9, and CD36, were significant and independent predictors of a therapeutic response beyond that of FEV(1) alone (P < 0.05). In both cohorts, receiver operating characteristic analysis revealed greater accuracy when genes were combined with FEV(1). Circulating mononuclear cell transcripts characterize a response to the treatment of pulmonary exacerbations. Even in small patient cohorts, changes in gene expression in conjunction with FEV(1) may enhance current outcomes measures for treatment response.

A Benzothiadiazole Primes Parsley Cells for Augmented Elicitation of Defense Responses

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Katz, Vera A.; Thulke, Oliver U.; Conrath, Uwe

1998-01-01

Systemic acquired resistance is an important component of the disease-resistance arsenal of plants, and is associated with an enhanced potency for activating local defense responses upon pathogen attack. Here we demonstrate that pretreatment with benzothiadiazole (BTH), a synthetic activator of acquired resistance in plants, augmented the sensitivity for low-dose elicitation of coumarin phytoalexin secretion by cultured parsley (Petroselinum crispum L.) cells. Enhanced coumarin secretion was associated with potentiated activation of genes encoding Phe ammonia-lyase (PAL). The augmentation of PAL gene induction was proportional to the length of pretreatment with BTH, indicating time-dependent priming of the cells. In contrast to the PAL genes, those for anionic peroxidase were directly induced by BTH in the absence of elicitor, thus confirming a dual role for BTH in the activation of plant defenses. Strikingly, the ability of various chemicals to enhance plant disease resistance correlated with their capability to potentiate parsley PAL gene elicitation, emphasizing an important role for defense response potentiation in acquired plant disease resistance. PMID:9701589

Priming of antiherbivore defensive responses in plants

Institute of Scientific and Technical Information of China (English)

Jinwon Kim; Gary W.Felton

2013-01-01

Defense priming is defined as increased readiness of defense induction.A growing body of literature indicates that plants (or intact parts of a plant) are primed in anticipation of impending environmental stresses,both biotic and abiotic,and upon the following stimulus,induce defenses more quickly and strongly.For instance,some plants previously exposed to herbivore-inducible plant volatiles (HIPVs) from neighboring plants under herbivore attack show faster or stronger defense activation and enhanced insect resistance when challenged with secondary insect feeding.Research on priming of antiherbivore defense has been limited to the HIPV-mediated mechanism until recently,but significant advances were made in the past three years,including non-HIPV-mediated defense priming,epigenetic modifications as the molecular mechanism of priming,and others.It is timely to consider the advances in research on defense priming in the plantinsect interactions.

Effector-triggered immunity: from pathogen perception to robust defense.

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Cui, Haitao; Tsuda, Kenichi; Parker, Jane E

2015-01-01

In plant innate immunity, individual cells have the capacity to sense and respond to pathogen attack. Intracellular recognition mechanisms have evolved to intercept perturbations by pathogen virulence factors (effectors) early in host infection and convert it to rapid defense. One key to resistance success is a polymorphic family of intracellular nucleotide-binding/leucine-rich-repeat (NLR) receptors that detect effector interference in different parts of the cell. Effector-activated NLRs connect, in various ways, to a conserved basal resistance network in order to transcriptionally boost defense programs. Effector-triggered immunity displays remarkable robustness against pathogen disturbance, in part by employing compensatory mechanisms within the defense network. Also, the mobility of some NLRs and coordination of resistance pathways across cell compartments provides flexibility to fine-tune immune outputs. Furthermore, a number of NLRs function close to the nuclear chromatin by balancing actions of defense-repressing and defense-activating transcription factors to program cells dynamically for effective disease resistance.

Water extracts from winery by-products as tobacco defense inducers.

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Benouaret, Razik; Goujon, Eric; Trivella, Aurélien; Richard, Claire; Ledoigt, Gérard; Joubert, Jean-Marie; Mery-Bernardon, Aude; Goupil, Pascale

2014-10-01

Water extracts from winery by-products exhibited significant plant defense inducer properties. Experiments were conducted on three marc extracts containing various amounts of polyphenols and anthocyanins. Infiltration of red, white and seed grape marc extracts into tobacco leaves induced hypersensitive reaction-like lesions with cell death evidenced by Evans Blue staining. The infiltration zones and the surrounding areas revealed accumulation of autofluorescent compounds under UV light. Leaf infiltration of the three winery by-product extracts induced defense gene expression. The antimicrobial PR1, β-1,3-glucanase PR2, and chitinase PR3 target genes were upregulated locally in tobacco plants following grape marc extract treatments. The osmotin PR5 transcripts accumulated as well in red marc extract treated-tobacco leaves. Overall, the winery by-product extracts elicited an array of plant defense responses making the grape residues a potential use of high value compounds.

Spatiotemporal heterogeneity of tomato induced defense responses affects spider mite performance and behavior.

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Schimmel, Bernardus C J; Ataide, Livia M S; Kant, Merijn R

2017-10-03

When feeding from tomato (Solanum lycopersicum), the generalist spider mite Tetranychus urticae induces jasmonate (JA)- and salicylate (SA)-regulated defense responses that hamper its performance. The related T. evansi, a Solanaceae-specialist, suppresses these defenses, thereby upholding a high performance. On a shared leaf, T. urticae can be facilitated by T. evansi, likely via suppression of defenses by the latter. Yet, when infesting the same plant, T. evansi outcompetes T. urticae. Recently, we found that T. evansi intensifies suppression of defenses locally, i.e., at its feeding site, after T. urticae mites were introduced onto adjacent leaf tissue. This hyper-suppression is paralleled by an increased oviposition rate of T. evansi, probably promoting its competitive population growth. Here we present additional data that not only provide insight into the spatiotemporal dynamics of defense induction and suppression by mites, but that also suggest T. evansi to manipulate more than JA and SA defenses alone.

Host-selective toxins of Pyrenophora tritici-repentis induce common responses associated with host susceptibility.

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Iovanna Pandelova

Full Text Available Pyrenophora tritici-repentis (Ptr, a necrotrophic fungus and the causal agent of tan spot of wheat, produces one or a combination of host-selective toxins (HSTs necessary for disease development. The two most studied toxins produced by Ptr, Ptr ToxA (ToxA and Ptr ToxB (ToxB, are proteins that cause necrotic or chlorotic symptoms respectively. Investigation of host responses induced by HSTs provides better insight into the nature of the host susceptibility. Microarray analysis of ToxA has provided evidence that it can elicit responses similar to those associated with defense. In order to evaluate whether there are consistent host responses associated with susceptibility, a similar analysis of ToxB-induced changes in the same sensitive cultivar was conducted. Comparative analysis of ToxA- and ToxB-induced transcriptional changes showed that similar groups of genes encoding WRKY transcription factors, RLKs, PRs, components of the phenylpropanoid and jasmonic acid pathways are activated. ROS accumulation and photosystem dysfunction proved to be common mechanism-of-action for these toxins. Despite similarities in defense responses, transcriptional and biochemical responses as well as symptom development occur more rapidly for ToxA compared to ToxB, which could be explained by differences in perception as well as by differences in activation of a specific process, for example, ethylene biosynthesis in ToxA treatment. Results of this study suggest that perception of HSTs will result in activation of defense responses as part of a susceptible interaction and further supports the hypothesis that necrotrophic fungi exploit defense responses in order to induce cell death.

Modularization and Response Curve Engineering of a Naringenin-Responsive Transcriptional Biosensor.

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De Paepe, Brecht; Maertens, Jo; Vanholme, Bartel; De Mey, Marjan

2018-05-18

To monitor the intra- and extracellular environment of micro-organisms and to adapt their metabolic processes accordingly, scientists are reprogramming nature's myriad of transcriptional regulatory systems into transcriptional biosensors, which are able to detect small molecules and, in response, express specific output signals of choice. However, the naturally occurring response curve, the key characteristic of biosensor circuits, is typically not in line with the requirements for real-life biosensor applications. In this contribution, a natural LysR-type naringenin-responsive biosensor circuit is developed and characterized with Escherichia coli as host organism. Subsequently, this biosensor is dissected into a clearly defined detector and effector module without loss of functionality, and the influence of the expression levels of both modules on the biosensor response characteristics is investigated. Two collections of ten unique synthetic biosensors each are generated. Each collection demonstrates a unique diversity of response curve characteristics spanning a 128-fold change in dynamic and 2.5-fold change in operational ranges and 3-fold change in levels of Noise, fit for a wide range of applications, such as adaptive laboratory evolution, dynamic pathway control and high-throughput screening methods. The established biosensor engineering concepts, and the developed biosensor collections themselves, are of use for the future development and customization of biosensors in general, for the multitude of biosensor applications and as a compelling alternative for the commonly used LacI-, TetR- and AraC-based inducible circuits.

The role of defensive ecological interactions in the evolution of conotoxins.

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Prashanth, J R; Dutertre, S; Jin, A H; Lavergne, V; Hamilton, B; Cardoso, F C; Griffin, J; Venter, D J; Alewood, P F; Lewis, R J

2016-01-01

Venoms comprise of complex mixtures of peptides evolved for predation and defensive purposes. Remarkably, some carnivorous cone snails can inject two distinct venoms in response to predatory or defensive stimuli, providing a unique opportunity to study separately how different ecological pressures contribute to toxin diversification. Here, we report the extraordinary defensive strategy of the Rhizoconus subgenus of cone snails. The defensive venom from this worm-hunting subgenus is unusually simple, almost exclusively composed of αD-conotoxins instead of the ubiquitous αA-conotoxins found in the more complex defensive venom of mollusc- and fish-hunting cone snails. A similarly compartmentalized venom gland as those observed in the other dietary groups facilitates the deployment of this defensive venom. Transcriptomic analysis of a Conus vexillum venom gland revealed the αD-conotoxins as the major transcripts, with lower amounts of 15 known and four new conotoxin superfamilies also detected with likely roles in prey capture. Our phylogenetic and molecular evolution analysis of the αD-conotoxins from five subgenera of cone snails suggests they evolved episodically as part of a defensive strategy in the Rhizoconus subgenus. Thus, our results demonstrate an important role for defence in the evolution of conotoxins. © 2015 John Wiley & Sons Ltd.

Hypotonicity-induced reduction of aquaporin-2 transcription in mpkCCD cells is independent of the tonicity responsive element, vasopressin, and cAMP.

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Kortenoeven, Marleen L A; van den Brand, Michiel; Wetzels, Jack F M; Deen, Peter M T

2011-04-15

The syndrome of inappropriate antidiuretic hormone secretion is characterized by excessive water uptake and hyponatremia. The extent of hyponatremia, however, is less than anticipated, which is ascribed to a defense mechanism, the vasopressin-escape, and is suggested to involve a tonicity-determined down-regulation of the water channel aquaporin-2 (AQP2). The underlying mechanism, however, is poorly understood. To study this, we used the mouse cortical collecting duct (mpkCCD) cell line. MpkCCD cells, transfected with an AQP2-promoter luciferase construct showed a reduced and increased AQP2 abundance and transcription following culture in hypotonic and hypertonic medium, respectively. This depended on tonicity rather than osmolality and occurred independently of the vasopressin analog dDAVP, cAMP levels, or protein kinase A activity. Although prostaglandins and nitric oxide reduced AQP2 abundance, inhibition of their synthesis did not influence tonicity-induced AQP2 transcription. Also, cells in which the cAMP or tonicity-responsive element (CRE/TonE) in the AQP2-promoter were mutated showed a similar response to hypotonicity. Instead, the tonicity-responsive elements were pin-pointed to nucleotides -283 to -252 and -157 to -126 bp. In conclusion, our data indicate that hypotonicity reduces AQP2 abundance and transcription, which occurs independently of vasopressin, cAMP, and the known TonE and CRE in the AQP2-promoter. Increased prostaglandin and nitric oxide, as found in vivo, may contribute to reduced AQP2 in vasopressin-escape, but do not mediate the effect of hypotonicity on AQP2 transcription. Our data suggest that two novel segments (-283 to -252 and -157 to -126 bp) in the AQP2-promoter mediate the hypotonicity-induced AQP2 down-regulation during vasopressin-escape.

Transcriptional profiling of the dose response: a more powerful approach for characterizing drug activities.

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Rui-Ru Ji

2009-09-01

Full Text Available The dose response curve is the gold standard for measuring the effect of a drug treatment, but is rarely used in genomic scale transcriptional profiling due to perceived obstacles of cost and analysis. One barrier to examining transcriptional dose responses is that existing methods for microarray data analysis can identify patterns, but provide no quantitative pharmacological information. We developed analytical methods that identify transcripts responsive to dose, calculate classical pharmacological parameters such as the EC50, and enable an in-depth analysis of coordinated dose-dependent treatment effects. The approach was applied to a transcriptional profiling study that evaluated four kinase inhibitors (imatinib, nilotinib, dasatinib and PD0325901 across a six-logarithm dose range, using 12 arrays per compound. The transcript responses proved a powerful means to characterize and compare the compounds: the distribution of EC50 values for the transcriptome was linked to specific targets, dose-dependent effects on cellular processes were identified using automated pathway analysis, and a connection was seen between EC50s in standard cellular assays and transcriptional EC50s. Our approach greatly enriches the information that can be obtained from standard transcriptional profiling technology. Moreover, these methods are automated, robust to non-optimized assays, and could be applied to other sources of quantitative data.

Endoplasmic reticulum stress-responsive transcription factor ATF6α directs recruitment of the Mediator of RNA polymerase II transcription and multiple histone acetyltransferase complexes.

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Sela, Dotan; Chen, Lu; Martin-Brown, Skylar; Washburn, Michael P; Florens, Laurence; Conaway, Joan Weliky; Conaway, Ronald C

2012-06-29

The basic leucine zipper transcription factor ATF6α functions as a master regulator of endoplasmic reticulum (ER) stress response genes. Previous studies have established that, in response to ER stress, ATF6α translocates to the nucleus and activates transcription of ER stress response genes upon binding sequence specifically to ER stress response enhancer elements in their promoters. In this study, we investigate the biochemical mechanism by which ATF6α activates transcription. By exploiting a combination of biochemical and multidimensional protein identification technology-based mass spectrometry approaches, we have obtained evidence that ATF6α functions at least in part by recruiting to the ER stress response enhancer elements of ER stress response genes a collection of RNA polymerase II coregulatory complexes, including the Mediator and multiple histone acetyltransferase complexes, among which are the Spt-Ada-Gcn5 acetyltransferase (SAGA) and Ada-Two-A-containing (ATAC) complexes. Our findings shed new light on the mechanism of action of ATF6α, and they outline a straightforward strategy for applying multidimensional protein identification technology mass spectrometry to determine which RNA polymerase II transcription factors and coregulators are recruited to promoters and other regulatory elements to control transcription.

The Transcription Factor ABI4 Is Required for the Ascorbic Acid–Dependent Regulation of Growth and Regulation of Jasmonate-Dependent Defense Signaling Pathways in Arabidopsis[C][W

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Kerchev, Pavel I.; Pellny, Till K.; Vivancos, Pedro Diaz; Kiddle, Guy; Hedden, Peter; Driscoll, Simon; Vanacker, Hélène; Verrier, Paul; Hancock, Robert D.; Foyer, Christine H.

2011-01-01

Cellular redox homeostasis is a hub for signal integration. Interactions between redox metabolism and the ABSCISIC ACID-INSENSITIVE-4 (ABI4) transcription factor were characterized in the Arabidopsis thaliana vitamin c defective1 (vtc1) and vtc2 mutants, which are defective in ascorbic acid synthesis and show a slow growth phenotype together with enhanced abscisic acid (ABA) levels relative to the wild type (Columbia-0). The 75% decrease in the leaf ascorbate pool in the vtc2 mutants was not sufficient to adversely affect GA metabolism. The transcriptome signatures of the abi4, vtc1, and vtc2 mutants showed significant overlap, with a large number of transcription factors or signaling components similarly repressed or induced. Moreover, lincomycin-dependent changes in LIGHT HARVESTING CHLOROPHYLL A/B BINDING PROTEIN 1.1 expression were comparable in these mutants, suggesting overlapping participation in chloroplast to nucleus signaling. The slow growth phenotype of vtc2 was absent in the abi4 vtc2 double mutant, as was the sugar-insensitive phenotype of the abi4 mutant. Octadecanoid derivative-responsive AP2/ERF-domain transcription factor 47 (ORA47) and AP3 (an ABI5 binding factor) transcripts were enhanced in vtc2 but repressed in abi4 vtc2, suggesting that ABI4 and ascorbate modulate growth and defense gene expression through jasmonate signaling. We conclude that low ascorbate triggers ABA- and jasmonate-dependent signaling pathways that together regulate growth through ABI4. Moreover, cellular redox homeostasis exerts a strong influence on sugar-dependent growth regulation. PMID:21926335

Activating Transcription Factor 3 Regulates Immune and Metabolic Homeostasis

Science.gov (United States)

Rynes, Jan; Donohoe, Colin D.; Frommolt, Peter; Brodesser, Susanne; Jindra, Marek

2012-01-01

Integration of metabolic and immune responses during animal development ensures energy balance, permitting both growth and defense. Disturbed homeostasis causes organ failure, growth retardation, and metabolic disorders. Here, we show that the Drosophila melanogaster activating transcription factor 3 (Atf3) safeguards metabolic and immune system homeostasis. Loss of Atf3 results in chronic inflammation and starvation responses mounted primarily by the larval gut epithelium, while the fat body suffers lipid overload, causing energy imbalance and death. Hyperactive proinflammatory and stress signaling through NF-κB/Relish, Jun N-terminal kinase, and FOXO in atf3 mutants deregulates genes important for immune defense, digestion, and lipid metabolism. Reducing the dose of either FOXO or Relish normalizes both lipid metabolism and gene expression in atf3 mutants. The function of Atf3 is conserved, as human ATF3 averts some of the Drosophila mutant phenotypes, improving their survival. The single Drosophila Atf3 may incorporate the diversified roles of two related mammalian proteins. PMID:22851689

Activating transcription factor 3 regulates immune and metabolic homeostasis.

Science.gov (United States)

Rynes, Jan; Donohoe, Colin D; Frommolt, Peter; Brodesser, Susanne; Jindra, Marek; Uhlirova, Mirka

2012-10-01

Integration of metabolic and immune responses during animal development ensures energy balance, permitting both growth and defense. Disturbed homeostasis causes organ failure, growth retardation, and metabolic disorders. Here, we show that the Drosophila melanogaster activating transcription factor 3 (Atf3) safeguards metabolic and immune system homeostasis. Loss of Atf3 results in chronic inflammation and starvation responses mounted primarily by the larval gut epithelium, while the fat body suffers lipid overload, causing energy imbalance and death. Hyperactive proinflammatory and stress signaling through NF-κB/Relish, Jun N-terminal kinase, and FOXO in atf3 mutants deregulates genes important for immune defense, digestion, and lipid metabolism. Reducing the dose of either FOXO or Relish normalizes both lipid metabolism and gene expression in atf3 mutants. The function of Atf3 is conserved, as human ATF3 averts some of the Drosophila mutant phenotypes, improving their survival. The single Drosophila Atf3 may incorporate the diversified roles of two related mammalian proteins.

Response to Competitive Entry: A Rationale for Delayed Defensive Reaction

OpenAIRE

Ajay Kalra; Surendra Rajiv; Kannan Srinivasan

1998-01-01

Empirical studies examining responses to new product entries come to the puzzling conclusion that, in general, an incumbent reacts to a new entrant after a significant delay. Even easy-to-implement price cuts are observed after significant lag following entry. These findings seem to contradict the existing literature that either implicitly assumes or strongly advocates immediate defensive responses to limit competitive encroachment. When a competing firm enters the market, consumers may be un...

Piriformospora indica root colonization triggers local and systemic root responses and inhibits secondary colonization of distal roots.

Science.gov (United States)

Pedrotti, Lorenzo; Mueller, Martin J; Waller, Frank

2013-01-01

Piriformosporaindica is a basidiomycete fungus colonizing roots of a wide range of higher plants, including crop plants and the model plant Arabidopsis thaliana. Previous studies have shown that P. indica improves growth, and enhances systemic pathogen resistance in leaves of host plants. To investigate systemic effects within the root system, we established a hydroponic split-root cultivation system for Arabidopsis. Using quantitative real-time PCR, we show that initial P. indica colonization triggers a local, transient response of several defense-related transcripts, of which some were also induced in shoots and in distal, non-colonized roots of the same plant. Systemic effects on distal roots included the inhibition of secondary P. indica colonization. Faster and stronger induction of defense-related transcripts during secondary inoculation revealed that a P. indica pretreatment triggers root-wide priming of defense responses, which could cause the observed reduction of secondary colonization levels. Secondary P. indica colonization also induced defense responses in distant, already colonized parts of the root. Endophytic fungi therefore trigger a spatially specific response in directly colonized and in systemic root tissues of host plants.

Transcriptional responses in honey bee larvae infected with chalkbrood fungus.

Science.gov (United States)

Aronstein, Katherine A; Murray, Keith D; Saldivar, Eduardo

2010-06-21

Diseases and other stress factors working synergistically weaken honey bee health and may play a major role in the losses of bee populations in recent years. Among a large number of bee diseases, chalkbrood has been on the rise. We present here the experimental identification of honey bee genes that are differentially expressed in response to infection of honey bee larvae with the chalkbrood fungus, Ascosphaera apis. We used cDNA-AFLP Technology to profile transcripts in infected and uninfected bee larvae. From 64 primer combinations, over 7,400 transcriptionally-derived fragments were obtained A total of 98 reproducible polymorphic cDNA-AFLP fragments were excised and sequenced, followed by quantitative real-time RT-PCR (qRT-PCR) analysis of these and additional samples.We have identified a number of differentially-regulated transcripts that are implicated in general mechanisms of stress adaptation, including energy metabolism and protein transport. One of the most interesting differentially-regulated transcripts is for a chitinase-like enzyme that may be linked to anti-fungal activities in the honey bee larvae, similarly to gut and fat-body specific chitinases found in mosquitoes and the red flour beetle. Surprisingly, we did not find many components of the well-characterized NF-kappaB intracellular signaling pathways to be differentially-regulated using the cDNA-AFLP approach. Therefore, utilizing qRT-PCR, we probed some of the immune related genes to determine whether the lack of up-regulation of their transcripts in our analysis can be attributed to lack of immune activation or to limitations of the cDNA-AFLP approach. Using a combination of cDNA-AFLP and qRT-PCR analyses, we were able to determine several key transcriptional events that constitute the overall effort in the honey bee larvae to fight natural fungal infection. Honey bee transcripts identified in this study are involved in critical functions related to transcriptional regulation, apoptotic

Deciphering molecular circuits from genetic variation underlying transcriptional responsiveness to stimuli.

Science.gov (United States)

Gat-Viks, Irit; Chevrier, Nicolas; Wilentzik, Roni; Eisenhaure, Thomas; Raychowdhury, Raktima; Steuerman, Yael; Shalek, Alex K; Hacohen, Nir; Amit, Ido; Regev, Aviv

2013-04-01

Individual genetic variation affects gene responsiveness to stimuli, often by influencing complex molecular circuits. Here we combine genomic and intermediate-scale transcriptional profiling with computational methods to identify variants that affect the responsiveness of genes to stimuli (responsiveness quantitative trait loci or reQTLs) and to position these variants in molecular circuit diagrams. We apply this approach to study variation in transcriptional responsiveness to pathogen components in dendritic cells from recombinant inbred mouse strains. We identify reQTLs that correlate with particular stimuli and position them in known pathways. For example, in response to a virus-like stimulus, a trans-acting variant responds as an activator of the antiviral response; using RNA interference, we identify Rgs16 as the likely causal gene. Our approach charts an experimental and analytic path to decipher the mechanisms underlying genetic variation in circuits that control responses to stimuli.

Sex-related differences in murine hepatic transcriptional and proteomic responses to TCDD

International Nuclear Information System (INIS)

Prokopec, Stephenie D.; Watson, John D.; Lee, Jamie; Pohjanvirta, Raimo; Boutros, Paul C.

2015-01-01

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant that produces myriad toxicities in most mammals. In rodents alone, there is a huge divergence in the toxicological response across species, as well as among different strains within a species. But there are also significant differences between males and females animals of a single strain. These differences are inconsistent across model systems: the severity of toxicity is greater in female rats than males, while male mice and guinea pigs are more sensitive than females. Because the specific events that underlie this difference remain unclear, we characterized the hepatic transcriptional response of adult male and female C57BL/6 mice to 500 μg/kg TCDD at multiple time-points. The transcriptional profile diverged significantly between the sexes. Female mice demonstrated a large number of altered transcripts as early as 6 h following treatment, suggesting a large primary response. Conversely, male animals showed the greatest TCDD-mediated response 144 h following exposure, potentially implicating significant secondary responses. Nr1i3 was statistically significantly induced at all time-points in the sensitive male animals. This mRNA encodes the constitutive androstane receptor (CAR), a transcription factor involved in the regulation of xenobiotic metabolism, lipid metabolism, cell cycle and apoptosis. Surprisingly though, changes at the protein level (aside from the positive control, CYP1A1) were modest, with only FMO3 showing clear induction, and no genes with sex-differences. Thus, while male and female mice show transcriptional differences in their response to TCDD, their association with TCDD-induced toxicities remains unclear. - Highlights: • Differences exist between the toxicity phenotypes to TCDD in male and female mice. • TCDD-mediated transcriptomic differences were identified between the sexes. • Resistant female mice displayed a large, early-onset, transcriptomic response. �

Sex-related differences in murine hepatic transcriptional and proteomic responses to TCDD

Energy Technology Data Exchange (ETDEWEB)

Prokopec, Stephenie D.; Watson, John D. [Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto (Canada); Lee, Jamie [Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto (Canada); Department of Pharmacology & Toxicology, University of Toronto, Toronto (Canada); Pohjanvirta, Raimo [Laboratory of Toxicology, National Institute for Health and Welfare, Kuopio Finland (Finland); Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki (Finland); Boutros, Paul C., E-mail: Paul.Boutros@oicr.on.ca [Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto (Canada); Department of Pharmacology & Toxicology, University of Toronto, Toronto (Canada); Department of Medical Biophysics, University of Toronto, Toronto (Canada)

2015-04-15

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant that produces myriad toxicities in most mammals. In rodents alone, there is a huge divergence in the toxicological response across species, as well as among different strains within a species. But there are also significant differences between males and females animals of a single strain. These differences are inconsistent across model systems: the severity of toxicity is greater in female rats than males, while male mice and guinea pigs are more sensitive than females. Because the specific events that underlie this difference remain unclear, we characterized the hepatic transcriptional response of adult male and female C57BL/6 mice to 500 μg/kg TCDD at multiple time-points. The transcriptional profile diverged significantly between the sexes. Female mice demonstrated a large number of altered transcripts as early as 6 h following treatment, suggesting a large primary response. Conversely, male animals showed the greatest TCDD-mediated response 144 h following exposure, potentially implicating significant secondary responses. Nr1i3 was statistically significantly induced at all time-points in the sensitive male animals. This mRNA encodes the constitutive androstane receptor (CAR), a transcription factor involved in the regulation of xenobiotic metabolism, lipid metabolism, cell cycle and apoptosis. Surprisingly though, changes at the protein level (aside from the positive control, CYP1A1) were modest, with only FMO3 showing clear induction, and no genes with sex-differences. Thus, while male and female mice show transcriptional differences in their response to TCDD, their association with TCDD-induced toxicities remains unclear. - Highlights: • Differences exist between the toxicity phenotypes to TCDD in male and female mice. • TCDD-mediated transcriptomic differences were identified between the sexes. • Resistant female mice displayed a large, early-onset, transcriptomic response. �

Transcriptome analysis of tobacco BY-2 cells elicited by cryptogein reveals new potential actors of calcium-dependent and calcium-independent plant defense pathways.

Science.gov (United States)

Amelot, Nicolas; Dorlhac de Borne, François; San Clemente, Hélène; Mazars, Christian; Grima-Pettenati, Jacqueline; Brière, Christian

2012-02-01

Cryptogein is a proteinaceous elicitor secreted by the oomycete Phytophthora cryptogea, which induces a hypersensitive response in tobacco plants. We have previously reported that in tobacco BY-2 cells treated with cryptogein, most of the genes of the phenylpropanoid pathway were upregulated and cell wall-bound phenolics accumulated. Both events were Ca(2+) dependent. In this study, we designed a microarray covering a large proportion of the tobacco genome and monitored gene expression in cryptogein-elicited BY-2 cells to get a more complete view of the transcriptome changes and to assess their Ca(2+) dependence. The predominant functional gene categories affected by cryptogein included stress- and disease-related proteins, phenylpropanoid pathway, signaling components, transcription factors and cell wall reinforcement. Among the 3819 unigenes whose expression changed more than fourfold, 90% were Ca(2+) dependent, as determined by their sensitivity to lanthanum chloride. The most Ca(2+)-dependent transcripts upregulated by cryptogein were involved in defense responses or the oxylipin pathway. This genome-wide study strongly supports the importance of Ca(2+)-dependent transcriptional regulation of regulatory and defense-related genes contributing to cryptogein responses in tobacco. Copyright © 2011 Elsevier Ltd. All rights reserved.

Elongator Plays a Positive Role in Exogenous NAD-Induced Defense Responses in Arabidopsis.

Science.gov (United States)

An, Chuanfu; Ding, Yezhang; Zhang, Xudong; Wang, Chenggang; Mou, Zhonglin

2016-05-01

Extracellular NAD is emerging as an important signal molecule in animal cells, but its role in plants has not been well-established. Although it has been shown that exogenous NAD(+) activates defense responses in Arabidopsis, components in the exogenous NAD(+)-activated defense pathway remain to be fully discovered. In a genetic screen for mutants insensitive to exogenous NAD(+) (ien), we isolated a mutant named ien2. Map-based cloning revealed that IEN2 encodes ELONGATA3 (ELO3)/AtELP3, a subunit of the Arabidopsis Elongator complex, which functions in multiple biological processes, including histone modification, DNA (de)methylation, and transfer RNA modification. Mutations in the ELO3/AtELP3 gene compromise exogenous NAD(+)-induced expression of pathogenesis-related (PR) genes and resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola ES4326, and transgenic expression of the coding region of ELO3/AtELP3 in elo3/Atelp3 restores NAD(+) responsiveness to the mutant plants, demonstrating that ELO3/AtELP3 is required for exogenous NAD(+)-induced defense responses. Furthermore, mutations in genes encoding the other five Arabidopsis Elongator subunits (ELO2/AtELP1, AtELP2, ELO1/AtELP4, AtELP5, and AtELP6) also compromise exogenous NAD(+)-induced PR gene expression and resistance to P. syringae pv. maculicola ES4326. These results indicate that the Elongator complex functions as a whole in exogenous NAD(+)-activated defense signaling in Arabidopsis.

Jasmonic acid carboxyl methyltransferase regulates development and herbivory-induced defense response in rice.

Science.gov (United States)

Qi, Jinfeng; Li, Jiancai; Han, Xiu; Li, Ran; Wu, Jianqiang; Yu, Haixin; Hu, Lingfei; Xiao, Yutao; Lu, Jing; Lou, Yonggen

2016-06-01

Jasmonic acid (JA) and related metabolites play a key role in plant defense and growth. JA carboxyl methyltransferase (JMT) may be involved in plant defense and development by methylating JA to methyl jasmonate (MeJA) and thus influencing the concentrations of JA and related metabolites. However, no JMT gene has been well characterized in monocotyledon defense and development at the molecular level. After we cloned a rice JMT gene, OsJMT1, whose encoding protein was localized in the cytosol, we found that the recombinant OsJMT1 protein catalyzed JA to MeJA. OsJMT1 is up-regulated in response to infestation with the brown planthopper (BPH; Nilaparvata lugens). Plants in which OsJMT1 had been overexpressed (oe-JMT plants) showed reduced height and yield. These oe-JMT plants also exhibited increased MeJA levels but reduced levels of herbivore-induced JA and jasmonoyl-isoleucine (JA-Ile). The oe-JMT plants were more attractive to BPH female adults but showed increased resistance to BPH nymphs, probably owing to the different responses of BPH female adults and nymphs to the changes in levels of H2 O2 and MeJA in oe-JMT plants. These results indicate that OsJMT1, by altering levels of JA and related metabolites, plays a role in regulating plant development and herbivore-induced defense responses in rice. © 2015 Institute of Botany, Chinese Academy of Sciences.

Mental imagery affects subsequent automatic defense responses

Directory of Open Access Journals (Sweden)

Muriel A Hagenaars

2015-06-01

Full Text Available Automatic defense responses promote survival and appropriate action under threat. They have also been associated with the development of threat-related psychiatric syndromes. Targeting such automatic responses during threat may be useful in populations with frequent threat exposure. Here, two experiments explored whether mental imagery as a pre-trauma manipulation could influence fear bradycardia (a core characteristic of freezing during subsequent analogue trauma (affective picture viewing. Image-based interventions have proven successful in the treatment of threat-related disorders, and are easily applicable. In Experiment 1 43 healthy participants were randomly assigned to an imagery script condition. Participants executed a passive viewing task with blocks of neutral, pleasant and unpleasant pictures after listening to an auditory script that was either related (with a positive or a negative outcome or unrelated to the unpleasant pictures from the passive viewing task. Heart rate was assessed during script listening and during passive viewing. Imagining negative related scripts resulted in greater bradycardia (neutral-unpleasant contrast than imagining positive scripts, especially unrelated. This effect was replicated in Experiment 2 (N = 51, again in the neutral-unpleasant contrast. An extra no-script condition showed that bradycardia was not induced by the negative related script, but rather that a positive script attenuated bradycardia. These preliminary results might indicate reduced vigilance after unrelated positive events. Future research should replicate these findings using a larger sample. Either way, the findings show that highly automatic defense behavior can be influenced by relatively simple mental imagery manipulations.

Coordination of frontline defense mechanisms under severe oxidative stress.

Science.gov (United States)

Kaur, Amardeep; Van, Phu T; Busch, Courtney R; Robinson, Courtney K; Pan, Min; Pang, Wyming Lee; Reiss, David J; DiRuggiero, Jocelyne; Baliga, Nitin S

2010-07-01

Complexity of cellular response to oxidative stress (OS) stems from its wide-ranging damage to nucleic acids, proteins, carbohydrates, and lipids. We have constructed a systems model of OS response (OSR) for Halobacterium salinarum NRC-1 in an attempt to understand the architecture of its regulatory network that coordinates this complex response. This has revealed a multi-tiered OS-management program to transcriptionally coordinate three peroxidase/catalase enzymes, two superoxide dismutases, production of rhodopsins, carotenoids and gas vesicles, metal trafficking, and various other aspects of metabolism. Through experimental validation of interactions within the OSR regulatory network, we show that despite their inability to directly sense reactive oxygen species, general transcription factors have an important function in coordinating this response. Remarkably, a significant fraction of this OSR was accurately recapitulated by a model that was earlier constructed from cellular responses to diverse environmental perturbations--this constitutes the general stress response component. Notwithstanding this observation, comparison of the two models has identified the coordination of frontline defense and repair systems by regulatory mechanisms that are triggered uniquely by severe OS and not by other environmental stressors, including sub-inhibitory levels of redox-active metals, extreme changes in oxygen tension, and a sub-lethal dose of gamma rays.

The Transcription Factor OsWRKY45 Negatively Modulates the Resistance of Rice to the Brown Planthopper Nilaparvata lugens

OpenAIRE

Huangfu, Jiayi; Li, Jiancai; Li, Ran; Ye, Meng; Kuai, Peng; Zhang, Tongfang; Lou, Yonggen

2016-01-01

WRKY transcription factors play a central role not only in plant growth and development but also in plant stress responses. However, the role of WRKY transcription factors in herbivore-induced plant defenses and their underlying mechanisms, especially in rice, remains largely unclear. Here, we cloned a rice WRKY gene OsWRKY45, whose expression was induced by mechanical wounding, by infestation of the brown planthopper (BPH, Nilaparvata lugens) and by treatment with jasmonic acid (JA) or salic...

Effects of internal and external factors on the budgeting between defensive and non-defensive responses in Aplysia.

Science.gov (United States)

Leod, Kaitlyn A Mac; Seas, Alexandra; Wainwright, Marcy L; Mozzachiodi, Riccardo

2018-04-25

Following exposure to aversive stimuli, organisms budget their behaviors by augmenting defensive responses and reducing/suppressing non-defensive behaviors. This budgeting process must be flexible to accommodate modifications in the animal's internal and/or external state that require the normal balance between defensive and non-defensive behaviors to be adjusted. When exposed to aversive stimuli, the mollusk Aplysia budgets its behaviors by concurrently enhancing defensive withdrawal reflexes (an elementary form of learning known as sensitization) and suppressing feeding. Sensitization and feeding suppression are consistently co-expressed following different training protocols and share common temporal domains, suggesting that they are interlocked. In this study, we attempted to uncouple the co-expression of sensitization and feeding suppression using: 1) manipulation of the animal's motivational state through prolonged food deprivation and 2) extended training with aversive stimuli that induces sensitization lasting for weeks. Both manipulations uncoupled the co-expression of the above behavioral changes. Prolonged food deprivation prevented the expression of sensitization, but not of feeding suppression. Following the extended training, sensitization and feeding suppression were co-expressed only for a limited time (i.e., 24 h), after which feeding returned to baseline levels as sensitization persisted for up to seven days. These findings indicate that sensitization and feeding suppression are not interlocked and that their co-expression can be uncoupled by internal (prolonged food deprivation) and external (extended aversive training) factors. The different strategies, by which the co-expression of sensitization and feeding suppression was altered, provide an example of how budgeting strategies triggered by an identical aversive experience can vary depending on the state of the organism. Copyright © 2018 Elsevier B.V. All rights reserved.

Transcriptional response of kidney tissue after 177Lu-octreotate administration in mice

International Nuclear Information System (INIS)

Schüler, Emil; Rudqvist, Nils; Parris, Toshima Z.; Langen, Britta; Helou, Khalil; Forssell-Aronsson, Eva

2014-01-01

Introduction: The kidneys are one of the main dose limiting organs in 177 Lu-octreotate therapy of neuroendocrine tumors. Therefore, biomarkers for radiation damage would be of great importance in this type of therapy. The purpose of this study was to investigate the absorbed dose dependency on early transcriptional changes in the kidneys from 177 Lu-octreotate exposure. Methods: Female Balb/c nude mice were i.v. injected with 1.3, 3.6, 14, 45 or 140 MBq 177 Lu-octreotate. The animals were killed 24 h after injection followed by excision of the kidneys. The absorbed dose to the kidneys ranged between 0.13 and 13 Gy. Total RNA was extracted from separated renal tissue samples, and applied to Illumina MouseRef-8 Whole-Genome Expression Beadchips to identify regulated transcripts after irradiation. Nexus Expression 2.0 and Gene Ontology terms were used for data processing and to determine affected biological processes. Results: Distinct transcriptional responses were observed following 177 Lu-octreotate administration. A higher number of differentially expressed transcripts were observed in the kidney medulla (480) compared to cortex (281). In addition, 39 transcripts were regulated at all absorbed dose levels in the medulla, compared to 32 in the cortex. Three biological processes in the cortex and five in the medulla were also shared by all absorbed dose levels. Strong association to metabolism was found among the affected processes in both tissues. Furthermore, an association with cellular and developmental processes was prominent in kidney medulla, while transport and immune response were prominent in kidney cortex. Conclusion: Specific biological and dose-dependent responses were observed in both tissues. The number of affected transcripts and biological processes revealed distinct response differences between the absorbed doses delivered to the tissues

Host transcription factors in the immediate pro-inflammatory response to the parasitic mite Psoroptes ovis.

Directory of Open Access Journals (Sweden)

Stewart T G Burgess

Full Text Available BACKGROUND: Sheep scab, caused by infestation with the ectoparasitic mite Psoroptes ovis, results in the rapid development of cutaneous inflammation and leads to the crusted skin lesions characteristic of the disease. We described previously the global host transcriptional response to infestation with P. ovis, elucidating elements of the inflammatory processes which lead to the development of a rapid and profound immune response. However, the mechanisms by which this response is instigated remain unclear. To identify novel methods of intervention a better understanding of the early events involved in triggering the immune response is essential. The objective of this study was to gain a clearer understanding of the mechanisms and signaling pathways involved in the instigation of the immediate pro-inflammatory response. RESULTS: Through a combination of transcription factor binding site enrichment and pathway analysis we identified key roles for a number of transcription factors in the instigation of cutaneous inflammation. In particular, defined roles were elucidated for the transcription factors NF-kB and AP-1 in the orchestration of the early pro-inflammatory response, with these factors being implicated in the activation of a suite of inflammatory mediators. CONCLUSIONS: Interrogation of the host temporal response to P. ovis infestation has enabled the further identification of the mechanisms underlying the development of the immediate host pro-inflammatory response. This response involves key regulatory roles for the transcription factors NF-kB and AP-1. Pathway analysis demonstrated that the activation of these transcription factors may be triggered following a host LPS-type response, potentially involving TLR4-signalling and also lead to the intriguing possibility that this could be triggered by a P. ovis allergen.

Hepcidin mediates transcriptional changes that modulate acute cytokine-induced inflammatory responses in mice.

Science.gov (United States)

De Domenico, Ivana; Zhang, Tian Y; Koening, Curry L; Branch, Ryan W; London, Nyall; Lo, Eric; Daynes, Raymond A; Kushner, James P; Li, Dean; Ward, Diane M; Kaplan, Jerry

2010-07-01

Hepcidin is a peptide hormone that regulates iron homeostasis and acts as an antimicrobial peptide. It is expressed and secreted by a variety of cell types in response to iron loading and inflammation. Hepcidin mediates iron homeostasis by binding to the iron exporter ferroportin, inducing its internalization and degradation via activation of the protein kinase Jak2 and the subsequent phosphorylation of ferroportin. Here we have shown that hepcidin-activated Jak2 also phosphorylates the transcription factor Stat3, resulting in a transcriptional response. Hepcidin treatment of ferroportin-expressing mouse macrophages showed changes in mRNA expression levels of a wide variety of genes. The changes in transcript levels for half of these genes were a direct effect of hepcidin, as shown by cycloheximide insensitivity, and dependent on the presence of Stat3. Hepcidin-mediated transcriptional changes modulated LPS-induced transcription in both cultured macrophages and in vivo mouse models, as demonstrated by suppression of IL-6 and TNF-alpha transcript and secreted protein. Hepcidin-mediated transcription in mice also suppressed toxicity and morbidity due to single doses of LPS, poly(I:C), and turpentine, which is used to model chronic inflammatory disease. Most notably, we demonstrated that hepcidin pretreatment protected mice from a lethal dose of LPS and that hepcidin-knockout mice could be rescued from LPS toxicity by injection of hepcidin. The results of our study suggest a new function for hepcidin in modulating acute inflammatory responses.

Global Transcriptional Responses to Osmotic, Oxidative, and Imipenem Stress Conditions in Pseudomonas putida

DEFF Research Database (Denmark)

Bojanovic, Klara; D'Arrigo, Isotta; Long, Katherine

2017-01-01

functional roles in the cellular response to stress conditions. The data show a larger fraction of differentially expressed sRNAs than of mRNAs with >5-fold expression changes. The work provides detailed insights into the mechanisms through which P. putida responds to different stress conditions...... intergenic and antisense transcripts, were detected, increasing the number of identified sRNA transcripts in the strain by a factor of 10. Unique responses to each type of stress are documented, including both the extent and dynamics of the gene expression changes. The work adds rich detail to previous......Bacteria cope with and adapt to stress by modulating gene expression in response to specific environmental cues. In this study, the transcriptional response of Pseudomonas putida KT2440 to osmotic, oxidative, and imipenem stress conditions at two time points was investigated via identification...

Candida albicans infection of Caenorhabditis elegans induces antifungal immune defenses.

Directory of Open Access Journals (Sweden)

Read Pukkila-Worley

2011-06-01

Full Text Available Candida albicans yeast cells are found in the intestine of most humans, yet this opportunist can invade host tissues and cause life-threatening infections in susceptible individuals. To better understand the host factors that underlie susceptibility to candidiasis, we developed a new model to study antifungal innate immunity. We demonstrate that the yeast form of C. albicans establishes an intestinal infection in Caenorhabditis elegans, whereas heat-killed yeast are avirulent. Genome-wide, transcription-profiling analysis of C. elegans infected with C. albicans yeast showed that exposure to C. albicans stimulated a rapid host response involving 313 genes (124 upregulated and 189 downregulated, ~1.6% of the genome many of which encode antimicrobial, secreted or detoxification proteins. Interestingly, the host genes affected by C. albicans exposure overlapped only to a small extent with the distinct transcriptional responses to the pathogenic bacteria Pseudomonas aeruginosa or Staphylococcus aureus, indicating that there is a high degree of immune specificity toward different bacterial species and C. albicans. Furthermore, genes induced by P. aeruginosa and S. aureus were strongly over-represented among the genes downregulated during C. albicans infection, suggesting that in response to fungal pathogens, nematodes selectively repress the transcription of antibacterial immune effectors. A similar phenomenon is well known in the plant immune response, but has not been described previously in metazoans. Finally, 56% of the genes induced by live C. albicans were also upregulated by heat-killed yeast. These data suggest that a large part of the transcriptional response to C. albicans is mediated through "pattern recognition," an ancient immune surveillance mechanism able to detect conserved microbial molecules (so-called pathogen-associated molecular patterns or PAMPs. This study provides new information on the evolution and regulation of the innate

Variation in plant defense against invasive herbivores: evidence for a hypersensitive response in eastern hemlocks (Tsuga canadensis).

Science.gov (United States)

Radville, Laura; Chaves, Arielle; Preisser, Evan L

2011-06-01

Herbivores can trigger a wide array of morphological and chemical changes in their host plants. Feeding by some insects induces a defensive hypersensitive response, a defense mechanism consisting of elevated H(2)O(2) levels and tissue death at the site of herbivore feeding. The invasive hemlock woolly adelgid Adelges tsugae ('HWA') and elongate hemlock scale Fiorinia externa ('EHS') feed on eastern hemlocks; although both are sessile sap feeders, HWA causes more damage than EHS. The rapid rate of tree death following HWA infestation has led to the suggestion that feeding induces a hypersensitive response in hemlock trees. We assessed the potential for an herbivore-induced hypersensitive response in eastern hemlocks by measuring H(2)O(2) levels in foliage from HWA-infested, EHS-infested, and uninfested trees. Needles with settled HWA or EHS had higher H(2)O(2) levels than control needles, suggesting a localized hypersensitive plant response. Needles with no direct contact to settled HWA also had high H(2)O(2) levels, suggesting that HWA infestation may induce a systemic defense response in eastern hemlocks. There was no similar systemic defensive response in the EHS treatment. Our results showed that two herbivores in the same feeding guild had dramatically different outcomes on the health of their shared host.

Global Transcriptome Analysis of Gracilaria changii (Rhodophyta) in Response to Agarolytic Enzyme and Bacterium.

Science.gov (United States)

Lim, Ee-Leen; Siow, Rouh-San; Abdul Rahim, Raha; Ho, Chai-Ling

2016-04-01

Many bacterial epiphytes of agar-producing seaweeds secrete agarase that degrade algal cell wall matrix into oligoagars which elicit defense-related responses in the hosts. The molecular defense responses of red seaweeds are largely unknown. In this study, we surveyed the defense-related transcripts of an agarophyte, Gracilaria changii, treated with β-agarase through next generation sequencing (NGS). We also compared the defense responses of seaweed elicited by agarase with those elicited by an agarolytic bacterium isolated from seaweed, by profiling the expression of defense-related genes using quantitative reverse transcription real-time PCR (qRT-PCR). NGS detected a total of 391 differentially expressed genes (DEGs) with a higher abundance (>2-fold change with a p value <0.001) in the agarase-treated transcriptome compared to that of the non-treated G. changii. Among these DEGs were genes related to signaling, bromoperoxidation, heme peroxidation, production of aromatic amino acids, chorismate, and jasmonic acid. On the other hand, the genes encoding a superoxide-generating NADPH oxidase and related to photosynthesis were downregulated. The expression of these DEGs was further corroborated by qRT-PCR results which showed more than 90 % accuracy. A comprehensive analysis of their gene expression profiles between 1 and 24 h post treatments (hpt) revealed that most of the genes analyzed were consistently upregulated or downregulated by both agarase and agarolytic bacterial treatments, indicating that the defense responses induced by both treatments are highly similar except for genes encoding vanadium bromoperoxidase and animal heme peroxidase. Our study has provided the first glimpse of the molecular defense responses of G. changii to agarase and agarolytic bacterial treatments.

Transcriptome changes in the phenylpropanoid pathway of Glycine max in response to Pseudomonas syringae infection

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Gonzalez Delkin O

2006-11-01

Full Text Available Abstract Background Reports of plant molecular responses to pathogenic infections have pinpointed increases in activity of several genes of the phenylpropanoid pathway leading to the synthesis of lignin and flavonoids. The majority of those findings were derived from single gene studies and more recently from several global gene expression analyses. We undertook a global transcriptional analysis focused on the response of genes of the multiple branches of the phenylpropanoid pathway to infection by the Pseudomonas syringae pv. glycinea with or without the avirulence gene avrB to characterize more broadly the contribution of the multiple branches of the pathway to the resistance response in soybean. Transcript abundance in leaves was determined from analysis of soybean cDNA microarray data and hybridizations to RNA blots with specific gene probes. Results The majority of the genes surveyed presented patterns of increased transcript accumulation. Some increased rapidly, 2 and 4 hours after inoculation, while others started to accumulate slowly by 8 – 12 hours. In contrast, transcripts of a few genes decreased in abundance 2 hours post inoculation. Most interestingly was the opposite temporal fluctuation in transcript abundance between early responsive genes in defense (CHS and IFS1 and F3H, the gene encoding a pivotal enzyme in the synthesis of anthocyanins, proanthocyanidins and flavonols. F3H transcripts decreased rapidly 2 hours post inoculation and increased during periods when CHS and IFS transcripts decreased. It was also determined that all but one (CHS4 family member genes (CHS1, CHS2, CHS3, CHS5, CHS6 and CHS7/8 accumulated higher transcript levels during the defense response provoked by the avirulent pathogen challenge. Conclusion Based on the mRNA profiles, these results show the strong bias that soybean has towards increasing the synthesis of isoflavonoid phytoalexins concomitant with the down regulation of genes required for the

Opposing roles of Toll-like receptor and cytosolic DNA-STING signaling pathways for Staphylococcus aureus cutaneous host defense.

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Philip O Scumpia

2017-07-01

Full Text Available Successful host defense against pathogens requires innate immune recognition of the correct pathogen associated molecular patterns (PAMPs by pathogen recognition receptors (PRRs to trigger the appropriate gene program tailored to the pathogen. While many PRR pathways contribute to the innate immune response to specific pathogens, the relative importance of each pathway for the complete transcriptional program elicited has not been examined in detail. Herein, we used RNA-sequencing with wildtype and mutant macrophages to delineate the innate immune pathways contributing to the early transcriptional response to Staphylococcus aureus, a ubiquitous microorganism that can activate a wide variety of PRRs. Unexpectedly, two PRR pathways-the Toll-like receptor (TLR and Stimulator of Interferon Gene (STING pathways-were identified as dominant regulators of approximately 95% of the genes that were potently induced within the first four hours of macrophage infection with live S. aureus. TLR signaling predominantly activated a pro-inflammatory program while STING signaling activated an antiviral/type I interferon response with live but not killed S. aureus. This STING response was largely dependent on the cytosolic DNA sensor cyclic guanosine-adenosine synthase (cGAS. Using a cutaneous infection model, we found that the TLR and STING pathways played opposite roles in host defense to S. aureus. TLR signaling was required for host defense, with its absence reducing interleukin (IL-1β production and neutrophil recruitment, resulting in increased bacterial growth. In contrast, absence of STING signaling had the opposite effect, enhancing the ability to restrict the infection. These results provide novel insights into the complex interplay of innate immune signaling pathways triggered by S. aureus and uncover opposing roles of TLR and STING in cutaneous host defense to S. aureus.

Global transcription profiling reveals comprehensive insights into hypoxic response in Arabidopsis.

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Liu, Fenglong; Vantoai, Tara; Moy, Linda P; Bock, Geoffrey; Linford, Lara D; Quackenbush, John

2005-03-01

Plants have evolved adaptation mechanisms to sense oxygen deficiency in their environments and make coordinated physiological and structural adjustments to enhance their hypoxic tolerance. To gain insight into how plants respond to low-oxygen stress, gene expression profiling using whole-genome DNA amplicon microarrays was carried out at seven time points over 24 h, in wild-type and transgenic P(SAG12):ipt Arabidopsis (Arabidopsis thaliana) plants under normoxic and hypoxic conditions. Transcript levels of genes involved in glycolysis and fermentation pathways, ethylene synthesis and perception, calcium signaling, nitrogen utilization, trehalose metabolism, and alkaloid synthesis were significantly altered in response to oxygen limitation. Analysis based on gene ontology assignments suggested a significant down-regulation of genes whose functions are associated with cell walls, nucleosome structures, water channels, and ion transporters and a significant up-regulation of genes involved in transcriptional regulation, protein kinase activity, and auxin responses under conditions of oxygen shortage. Promoter analysis on a cluster of up-regulated genes revealed a significant overrepresentation of the AtMYB2-binding motif (GT motif), a sugar response element-like motif, and a G-box-related sequence, and also identified several putative anaerobic response elements. Finally, quantitative real-time polymerase chain reactions using 29 selected genes independently verified the microarray results. This study represents one of the most comprehensive analyses conducted to date investigating hypoxia-responsive transcriptional networks in plants.

MicroRNA regulated defense responses in Triticum aestivum L. during Puccinia graminis f.sp. tritici infection.

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Gupta, Om Prakash; Permar, Vipin; Koundal, Vikas; Singh, Uday Dhari; Praveen, Shelly

2012-02-01

Plants have evolved diverse mechanism to recognize pathogen attack and triggers defense responses. These defense responses alter host cellular function regulated by endogenous, small, non-coding miRNAs. To understand the mechanism of miRNAs regulated cellular functions during stem rust infection in wheat, we investigated eight different miRNAs viz. miR159, miR164, miR167, miR171, miR444, miR408, miR1129 and miR1138, involved in three different independent cellular defense response to infection. The investigation reveals that at the initiation of disease, accumulation of miRNAs might be playing a key role in hypersensitive response (HR) from host, which diminishes at the maturation stage. This suggests a possible host-fungal synergistic relation leading to susceptibility. Differential expression of these miRNAs in presence and absence of R gene provides a probable explanation of miRNA regulated R gene mediated independent pathways.

UV-B Irradiation Changes Specifically the Secondary Metabolite Profile in Broccoli Sprouts: Induced Signaling Overlaps with Defense Response to Biotic Stressors

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Mewis, Inga; Schreiner, Monika; Nguyen, Chau Nhi; Krumbein, Angelika; Ulrichs, Christian; Lohse, Marc; Zrenner, Rita

2012-01-01

Only a few environmental factors have such a pronounced effect on plant growth and development as ultraviolet light (UV). Concerns have arisen due to increased UV-B radiation reaching the Earth’s surface as a result of stratospheric ozone depletion. Ecologically relevant low to moderate UV-B doses (0.3–1 kJ m–2 d–1) were applied to sprouts of the important vegetable crop Brassica oleracea var. italica (broccoli), and eco-physiological responses such as accumulation of non-volatile secondary metabolites were related to transcriptional responses with Agilent One-Color Gene Expression Microarray analysis using the 2×204 k format Brassica microarray. UV-B radiation effects have usually been linked to increases in phenolic compounds. As expected, the flavonoids kaempferol and quercetin accumulated in broccoli sprouts (the aerial part of the seedlings) 24 h after UV-B treatment. A new finding is the specific UV-B-mediated induction of glucosinolates (GS), especially of 4-methylsulfinylbutyl GS and 4-methoxy-indol-3-ylmethyl GS, while carotenoids and Chl levels remained unaffected. Accumulation of defensive GS metabolites was accompanied by increased expression of genes associated with salicylate and jasmonic acid signaling defense pathways and up-regulation of genes responsive to fungal and bacterial pathogens. Concomitantly, plant pre-exposure to moderate UV-B doses had negative effects on the performance of the caterpillar Pieris brassicae (L.) and on the population growth of the aphid Myzus persicae (Sulzer). Moreover, insect-specific induction of GS in broccoli sprouts was affected by UV-B pre-treatment. PMID:22773681

Acetaminophen modulates the transcriptional response to recombinant interferon-beta.

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Aaron Farnsworth

Full Text Available BACKGROUND: Recombinant interferon treatment can result in several common side effects including fever and injection-site pain. Patients are often advised to use acetaminophen or other over-the-counter pain medications as needed. Little is known regarding the transcriptional changes induced by such co-administration. METHODOLOGY/PRINCIPAL FINDINGS: We tested whether the administration of acetaminophen causes a change in the response normally induced by interferon-beta treatment. CD-1 mice were administered acetaminophen (APAP, interferon-beta (IFN-beta or a combination of IFN-beta+APAP and liver and serum samples were collected for analysis. Differential gene expression was determined using an Agilent 22 k whole mouse genome microarray. Data were analyzed by several methods including Gene Ontology term clustering and Gene Set Enrichment Analysis. We observed a significant change in the transcription profile of hepatic cells when APAP was co-administered with IFN-beta. These transcriptional changes included a marked up-regulation of genes involved in signal transduction and cell differentiation and down-regulation of genes involved in cellular metabolism, trafficking and the IkappaBK/NF-kappaB cascade. Additionally, we observed a large decrease in the expression of several IFN-induced genes including Ifit-3, Isg-15, Oasl1, Zbp1 and predicted gene EG634650 at both early and late time points. CONCLUSIONS/SIGNIFICANCE: A significant change in the transcriptional response was observed following co-administration of IFN-beta+APAP relative to IFN-beta treatment alone. These results suggest that administration of acetaminophen has the potential to modify the efficacy of IFN-beta treatment.

Enhanceosomes as integrators of hypoxia inducible factor (HIF) and other transcription factors in the hypoxic transcriptional response.

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Pawlus, Matthew R; Hu, Cheng-Jun

2013-09-01

Hypoxia is a prevalent attribute of the solid tumor microenvironment that promotes the expression of genes through posttranslational modifications and stabilization of alpha subunits (HIF1α and HIF2α) of hypoxia-inducible factors (HIFs). Despite significant similarities, HIF1 (HIF1α/ARNT) and HIF2 (HIF2α/ARNT) activate common as well as unique target genes and exhibit different functions in cancer biology. More surprisingly, accumulating data indicates that the HIF1- and/or HIF2-mediated hypoxia responses can be oncogenic as well as tumor suppressive. While the role of HIF in the hypoxia response is well established, recent data support the concept that HIF is necessary, but not sufficient for the hypoxic response. Other transcription factors that are activated by hypoxia are also required for the HIF-mediated hypoxia response. HIFs, other transcription factors, co-factors and RNA poll II recruited by HIF and other transcription factors form multifactorial enhanceosome complexes on the promoters of HIF target genes to activate hypoxia inducible genes. Importantly, HIF1 or HIF2 requires distinct partners in activating HIF1 or HIF2 target genes. Because HIF enhanceosome formation is required for the gene activation and distinct functions of HIF1 and HIF2 in tumor biology, disruption of the HIF1 or HIF2 specific enhanceosome complex may prove to be a beneficial strategy in tumor treatment in which tumor growth is specifically dependent upon HIF1 or HIF2 activity. Copyright © 2013 Elsevier Inc. All rights reserved.

Functional and DNA-protein binding studies of WRKY transcription factors and their expression analysis in response to biotic and abiotic stress in wheat (Triticum aestivum L.).

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Satapathy, Lopamudra; Kumar, Dhananjay; Kumar, Manish; Mukhopadhyay, Kunal

2018-01-01

WRKY, a plant-specific transcription factor family, plays vital roles in pathogen defense, abiotic stress, and phytohormone signalling. Little is known about the roles and function of WRKY transcription factors in response to rust diseases in wheat. In the present study, three TaWRKY genes encoding complete protein sequences were cloned. They belonged to class II and III WRKY based on the number of WRKY domains and the pattern of zinc finger structures. Twenty-two DNA-protein binding docking complexes predicted stable interactions of WRKY domain with W-box. Quantitative real-time-PCR using wheat near-isogenic lines with or without Lr28 gene revealed differential up- or down-regulation in response to biotic and abiotic stress treatments which could be responsible for their functional divergence in wheat. TaWRKY62 was found to be induced upon treatment with JA, MJ, and SA and reduced after ABA treatments. Maximum induction of six out of seven genes occurred at 48 h post inoculation due to pathogen inoculation. Hence, TaWRKY (49, 50 , 52 , 55 , 57, and 62 ) can be considered as potential candidate genes for further functional validation as well as for crop improvement programs for stress resistance. The results of the present study will enhance knowledge towards understanding the molecular basis of mode of action of WRKY transcription factor genes in wheat and their role during leaf rust pathogenesis in particular.

Melatonin modulates the fetal cardiovascular defense response to acute hypoxia.

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Thakor, Avnesh S; Allison, Beth J; Niu, Youguo; Botting, Kimberley J; Serón-Ferré, Maria; Herrera, Emilio A; Giussani, Dino A

2015-08-01

Experimental studies in animal models supporting protective effects on the fetus of melatonin in adverse pregnancy have prompted clinical trials in human pregnancy complicated by fetal growth restriction. However, the effects of melatonin on the fetal defense to acute hypoxia, such as that which may occur during labor, remain unknown. This translational study tested the hypothesis, in vivo, that melatonin modulates the fetal cardiometabolic defense responses to acute hypoxia in chronically instrumented late gestation fetal sheep via alterations in fetal nitric oxide (NO) bioavailability. Under anesthesia, 6 fetal sheep at 0.85 gestation were instrumented with vascular catheters and a Transonic flow probe around a femoral artery. Five days later, fetuses were exposed to acute hypoxia with or without melatonin treatment. Fetal blood was taken to determine blood gas and metabolic status and plasma catecholamine concentrations. Hypoxia during melatonin treatment was repeated during in vivo NO blockade with the NO clamp. This technique permits blockade of de novo synthesis of NO while compensating for the tonic production of the gas, thereby maintaining basal cardiovascular function. Melatonin suppressed the redistribution of blood flow away from peripheral circulations and the glycemic and plasma catecholamine responses to acute hypoxia. These are important components of the fetal brain sparing response to acute hypoxia. The effects of melatonin involved NO-dependent mechanisms as the responses were reverted by fetal treatment with the NO clamp. Melatonin modulates the in vivo fetal cardiometabolic responses to acute hypoxia by increasing NO bioavailability. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Regulation of anti-Plasmodium immunity by a LITAF-like transcription factor in the malaria vector Anopheles gambiae.

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Ryan C Smith

Full Text Available The mosquito is the obligate vector for malaria transmission. To complete its development within the mosquito, the malaria parasite Plasmodium must overcome the protective action of the mosquito innate immune system. Here we report on the involvement of the Anopheles gambiae orthologue of a conserved component of the vertebrate immune system, LPS-induced TNFα transcription factor (LITAF, and its role in mosquito anti-Plasmodium immunity. An. gambiae LITAF-like 3 (LL3 expression is up-regulated in response to midgut invasion by both rodent and human malaria parasites. Silencing of LL3 expression greatly increases parasite survival, indicating that LL3 is part of an anti-Plasmodium defense mechanism. Electrophoretic mobility shift assays identified specific LL3 DNA-binding motifs within the promoter of SRPN6, a gene that also mediates mosquito defense against Plasmodium. Further experiments indicated that these motifs play a direct role in LL3 regulation of SRPN6 expression. We conclude that LL3 is a transcription factor capable of modulating SRPN6 expression as part of the mosquito anti-Plasmodium immune response.

Early transcriptional response of soybean contrasting accessions to root dehydration.

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José Ribamar Costa Ferreira Neto

Full Text Available Drought is a significant constraint to yield increase in soybean. The early perception of water deprivation is critical for recruitment of genes that promote plant tolerance. DeepSuperSAGE libraries, including one control and a bulk of six stress times imposed (from 25 to 150 min of root dehydration for drought-tolerant and sensitive soybean accessions, allowed to identify new molecular targets for drought tolerance. The survey uncovered 120,770 unique transcripts expressed by the contrasting accessions. Of these, 57,610 aligned with known cDNA sequences, allowing the annotation of 32,373 unitags. A total of 1,127 unitags were up-regulated only in the tolerant accession, whereas 1,557 were up-regulated in both as compared to their controls. An expression profile concerning the most representative Gene Ontology (GO categories for the tolerant accession revealed the expression "protein binding" as the most represented for "Molecular Function", whereas CDPK and CBL were the most up-regulated protein families in this category. Furthermore, particular genes expressed different isoforms according to the accession, showing the potential to operate in the distinction of physiological behaviors. Besides, heat maps comprising GO categories related to abiotic stress response and the unitags regulation observed in the expression contrasts covering tolerant and sensitive accessions, revealed the unitags potential for plant breeding. Candidate genes related to "hormone response" (LOX, ERF1b, XET, "water response" (PUB, BMY, "salt stress response" (WRKY, MYB and "oxidative stress response" (PER figured among the most promising molecular targets. Additionally, nine transcripts (HMGR, XET, WRKY20, RAP2-4, EREBP, NAC3, PER, GPX5 and BMY validated by RT-qPCR (four different time points confirmed their differential expression and pointed that already after 25 minutes a transcriptional reorganization started in response to the new condition, with important

Unraveling the WRKY transcription factors network in Arabidopsis Thaliana by integrative approach

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Mouna Choura

2015-06-01

Full Text Available The WRKY transcription factors superfamily are involved in diverse biological processes in plants including response to biotic and abiotic stresses and plant immunity. Protein-protein interaction network is a useful approach for understanding these complex processes. The availability of Arabidopsis Thaliana interactome offers a good opportunity to do get a global view of protein network. In this work, we have constructed the WRKY transcription factor network by combining different sources of evidence and we characterized its topological features using computational tools. We found that WRKY network is a hub-based network involving multifunctional proteins denoted as hubs such as WRKY 70, WRKY40, WRKY 53, WRKY 60, WRKY 33 and WRKY 51. Functional annotation showed seven functional modules particularly involved in biotic stress and defense responses. Furthermore, the gene ontology and pathway enrichment analysis revealed that WRKY proteins are mainly involved in plant-pathogen interaction pathways and their functions are directly related to the stress response and immune system process.

Specific transcripts are elevated in Saccharomyces cerevisiae in response to DNA damage

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McClanahan, T.; McEntee, K.

1984-01-01

Differential hybridization has been used to identify genes in Saccharomyces cerevisiae displaying increased transcript levels after treatment of cells with UV irradiation or with the mutagen/carcinogen 4-nitroquinoline-1-oxide (NQO). The authors describe the isolation and characterization of four DNA damage responsive genes obtained from screening ca. 9000 yeast genomic clones. Two of these clones, lambda 78A and pBR178C, contain repetitive elements in the yeast genome as shown by Southern hybridization analysis. Although the genomic hybridization pattern is distinct for each of these two clones, both of these sequences hybridize to large polyadenylated transcripts ca. 5 kilobases in length. Two other DNA damage responsive sequences, pBRA2 and pBR3016B, are single-copy genes and hybridize to 0.5- and 3.2-kilobase transcripts, respectively. Kinetic analysis of the 0.5-kilobase transcript homologous to pBRA2 indicates that the level of this RNA increases more than 15-fold within 20 min after exposure to 4-nitroquinoline-1-oxide. Moreover, the level of this transcript is significantly elevated in cells containing the rad52-1 mutation which are deficient in DNA strand break repair and gene conversion. These results provide some of the first evidence that DNA damage stimulates transcription of specific genes in eucaryotic cells

Arabidopsis transcriptional responses differentiate between O3 and herbicides

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Using published data based on Affymetrix ATH1 Gene-Chips we characterized the transcriptional response of Arabidopsis thaliana Columbia to O3 and a few other major environmental stresses including oxidative stress . A set of 101 markers could be extracted which provided a compo...

Anoxia-responsive regulation of the FoxO transcription factors in freshwater turtles, Trachemys scripta elegans.

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Krivoruchko, Anastasia; Storey, Kenneth B

2013-11-01

The forkhead class O (FoxO) transcription factors are important regulators of multiple aspects of cellular metabolism. We hypothesized that activation of these transcription factors could play crucial roles in low oxygen survival in the anoxia-tolerant turtle, Trachemys scripta elegans. Two FoxOs, FoxO1 and FoxO3, were examined in turtle tissues in response to 5 and 20h of anoxic submergence using techniques of RT-PCR, western immunoblotting and DNA-binding assays to assess activation. Transcript levels of FoxO-responsive genes were also quantified using RT-PCR. FoxO1 was anoxia-responsive in the liver, with increases in transcript levels, protein levels, nuclear levels and DNA-binding of 1.7-4.8fold in response to anoxia. Levels of phosphorylated FoxO1 also decreased to 57% of control values in response to 5h of anoxia, indicating activation. FoxO3 was activated in the heart, kidney and liver in response to anoxia, with nuclear levels increasing by 1.5-3.7fold and DNA-binding activity increasing by 1.3-2.9fold. Transcript levels of two FoxO-target genes, p27kip1 and catalase, also rose by 2.4-2.5fold in the turtle liver under anoxia. The results suggest that the FoxO transcription factors are activated in response to anoxia in T. scripta elegans, potentially contributing to the regulation of stress resistance and metabolic depression. This study provides the first demonstration of activation of FoxOs in a natural model for vertebrate anoxia tolerance, further improving understanding of how tissues can survive without oxygen. © 2013.

Physcomitrella patens Activates Defense Responses against the Pathogen Colletotrichum gloeosporioides

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Guillermo Reboledo

2015-09-01

Full Text Available The moss Physcomitrella patens is a suitable model plant to analyze the activation of defense mechanisms after pathogen assault. In this study, we show that Colletotrichum gloeosporioides isolated from symptomatic citrus fruit infects P. patens and cause disease symptoms evidenced by browning and maceration of tissues. After C. gloeosporioides infection, P. patens reinforces the cell wall by the incorporation of phenolic compounds and induces the expression of a Dirigent-protein-like encoding gene that could lead to the formation of lignin-like polymers. C. gloeosporioides-inoculated protonemal cells show cytoplasmic collapse, browning of chloroplasts and modifications of the cell wall. Chloroplasts relocate in cells of infected tissues toward the initially infected C. gloeosporioides cells. P. patens also induces the expression of the defense genes PAL and CHS after fungal colonization. P. patens reporter lines harboring the auxin-inducible promoter from soybean (GmGH3 fused to β-glucuronidase revealed an auxin response in protonemal tissues, cauloids and leaves of C. gloeosporioides-infected moss tissues, indicating the activation of auxin signaling. Thus, P. patens is an interesting plant to gain insight into defense mechanisms that have evolved in primitive land plants to cope with microbial pathogens.

Global transcriptional responses of Acidithiobacillus ferrooxidans Wenelen under different sulfide minerals.

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Latorre, Mauricio; Ehrenfeld, Nicole; Cortés, María Paz; Travisany, Dante; Budinich, Marko; Aravena, Andrés; González, Mauricio; Bobadilla-Fazzini, Roberto A; Parada, Pilar; Maass, Alejandro

2016-01-01

In order to provide new information about the adaptation of Acidithiobacillus ferrooxidans during the bioleaching process, the current analysis presents the first report of the global transcriptional response of the native copper mine strain Wenelen (DSM 16786) oxidized under different sulfide minerals. Microarrays were used to measure the response of At. ferrooxidans Wenelen to shifts from iron supplemented liquid cultures (reference state) to the addition of solid substrates enriched in pyrite or chalcopyrite. Genes encoding for energy metabolism showed a similar transcriptional profile for the two sulfide minerals. Interestingly, four operons related to sulfur metabolism were over-expressed during growth on a reduced sulfur source. Genes associated with metal tolerance (RND and ATPases type P) were up-regulated in the presence of pyrite or chalcopyrite. These results suggest that At. ferrooxidans Wenelen presents an efficient transcriptional system developed to respond to environmental conditions, namely the ability to withstand high copper concentrations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Proteomic identification of early salicylate- and flg22-responsive redox-sensitive proteins in Arabidopsis

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Liu, Peng; Zhang, Huoming; Yu, Boying; Xiong, Liming; Xia, Yiji

2015-01-01

in Arabidopsis cells during the early response to salicylate or flg22, two defense pathway elicitors that are known to disturb cellular redox homeostasis. Among the salicylate- and/or flg22-responsive redox-sensitive proteins are those involved in transcriptional

Comprehensive transcriptional profiling of NaCl-stressed Arabidopsis roots reveals novel classes of responsive genes

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Deyholos Michael K

2006-10-01

Full Text Available Abstract Background Roots are an attractive system for genomic and post-genomic studies of NaCl responses, due to their primary importance to agriculture, and because of their relative structural and biochemical simplicity. Excellent genomic resources have been established for the study of Arabidopsis roots, however, a comprehensive microarray analysis of the root transcriptome following NaCl exposure is required to further understand plant responses to abiotic stress and facilitate future, systems-based analyses of the underlying regulatory networks. Results We used microarrays of 70-mer oligonucleotide probes representing 23,686 Arabidopsis genes to identify root transcripts that changed in relative abundance following 6 h, 24 h, or 48 h of hydroponic exposure to 150 mM NaCl. Enrichment analysis identified groups of structurally or functionally related genes whose members were statistically over-represented among up- or down-regulated transcripts. Our results are consistent with generally observed stress response themes, and highlight potentially important roles for underappreciated gene families, including: several groups of transporters (e.g. MATE, LeOPT1-like; signalling molecules (e.g. PERK kinases, MLO-like receptors, carbohydrate active enzymes (e.g. XTH18, transcription factors (e.g. members of ZIM, WRKY, NAC, and other proteins (e.g. 4CL-like, COMT-like, LOB-Class 1. We verified the NaCl-inducible expression of selected transcription factors and other genes by qRT-PCR. Conclusion Micorarray profiling of NaCl-treated Arabidopsis roots revealed dynamic changes in transcript abundance for at least 20% of the genome, including hundreds of transcription factors, kinases/phosphatases, hormone-related genes, and effectors of homeostasis, all of which highlight the complexity of this stress response. Our identification of these transcriptional responses, and groups of evolutionarily related genes with either similar or divergent

Elicitor-induced transcription factors for metabolic reprogramming of secondary metabolism in Medicago truncatula

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Dixon Richard A

2008-12-01

Full Text Available Abstract Background Exposure of Medicago truncatula cell suspension cultures to pathogen or wound signals leads to accumulation of various classes of flavonoid and/or triterpene defense molecules, orchestrated via a complex signalling network in which transcription factors (TFs are essential components. Results In this study, we analyzed TFs responding to yeast elicitor (YE or methyl jasmonate (MJ. From 502 differentially expressed TFs, WRKY and AP2/EREBP gene families were over-represented among YE-induced genes whereas Basic Helix-Loop-Helix (bHLH family members were more over-represented among the MJ-induced genes. Jasmonate ZIM-domain (JAZ transcriptional regulators were highly induced by MJ treatment. To investigate potential involvement of WRKY TFs in signalling, we expressed four Medicago WRKY genes in tobacco. Levels of soluble and wall bound phenolic compounds and lignin were increased in all cases. WRKY W109669 also induced tobacco endo-1,3-β-glucanase (NtPR2 and enhanced the systemic defense response to tobacco mosaic virus in transgenic tobacco plants. Conclusion These results confirm that Medicago WRKY TFs have broad roles in orchestrating metabolic responses to biotic stress, and that they also represent potentially valuable reagents for engineering metabolic changes that impact pathogen resistance.

Under Secretary of Defense (Comptroller) > Budget

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functionalStatements OUSD(C) History FMR Budget Materials Budget Execution Financial Management Improving Financial Performance Reports Regulations Press Release | Budget Briefing | Transcripts: David L. Norquist, Under PDF document. Click on Excel icon for Excel document Overview - FY2019 Defense Budget Performance

Transcriptional expression of Stilbene synthase genes are regulated developmentally and differentially in response to powdery mildew in Norton and Cabernet Sauvignon grapevine.

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Dai, Ru; Ge, Hui; Howard, Susanne; Qiu, Wenping

2012-12-01

Stilbenic compounds are natural phytoalexins that have antimicrobial activities in plant defense against pathogens. Stilbene synthase (STS) is the key enzyme that catalyzes the biosynthesis of stilbenic compounds. Grapevine genome contains a family of preliminarily annotated 35 STS genes, the regulation of each STS gene needs to be studied to define their roles. In this study, we selected eight STS genes, STS8, STS27/31, STS16/22, STS13/17/23, and applied quantitative polymerase chain reaction (qPCR) to characterize their transcriptional expression profiles in leaf tissues upon infection by the powdery mildew fungus (PM), Erysiphe necator (Schw.) Burr. Their transcripts were also compared in young and old leaves as well as in the berry skin at five developmental stages in Vitis vinifera 'Cabernet Sauvignon' and Vitis aestivalis 'Norton'. The results showed that transcripts of selected STS genes increased significantly in Cabernet Sauvignon leaves at 24 and 48 h post inoculation with PM spores and remained unchanged in Norton leaves in response to the PM infection. Transcripts of STS8, STS27/31 and STS13/17/23 were more abundant in the old leaves of Norton than in Cabernet Sauvignon. STS genes showed lower expression levels in young leaves than in old leaves. Transcript levels of the eight STS genes increased drastically in the berry skin of Cabernet Sauvignon and Norton post véraison. In addition, the content of trans-resveratrol in the berry skin rapidly increased post véraison and reached the highest level at harvest. These assays demonstrated that individual STS genes are regulated differentially in response to PM infection and during development in the two grape varieties. The present study yields basic knowledge for further investigation of the regulation and function of each STS gene in grapevine and provides experimental evidences for the functional annotation of the STS gene family in the grapevine genome. Copyright © 2012 Elsevier Ireland Ltd. All

Transcriptional profiling uncovers a network of cholesterol-responsive atherosclerosis target genes.

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Josefin Skogsberg

2008-03-01

Full Text Available Despite the well-documented effects of plasma lipid lowering regimes halting atherosclerosis lesion development and reducing morbidity and mortality of coronary artery disease and stroke, the transcriptional response in the atherosclerotic lesion mediating these beneficial effects has not yet been carefully investigated. We performed transcriptional profiling at 10-week intervals in atherosclerosis-prone mice with human-like hypercholesterolemia and a genetic switch to lower plasma lipoproteins (Ldlr(-/-Apo(100/100Mttp(flox/flox Mx1-Cre. Atherosclerotic lesions progressed slowly at first, then expanded rapidly, and plateaued after advanced lesions formed. Analysis of lesion expression profiles indicated that accumulation of lipid-poor macrophages reached a point that led to the rapid expansion phase with accelerated foam-cell formation and inflammation, an interpretation supported by lesion histology. Genetic lowering of plasma cholesterol (e.g., lipoproteins at this point all together prevented the formation of advanced plaques and parallel transcriptional profiling of the atherosclerotic arterial wall identified 37 cholesterol-responsive genes mediating this effect. Validation by siRNA-inhibition in macrophages incubated with acetylated-LDL revealed a network of eight cholesterol-responsive atherosclerosis genes regulating cholesterol-ester accumulation. Taken together, we have identified a network of atherosclerosis genes that in response to plasma cholesterol-lowering prevents the formation of advanced plaques. This network should be of interest for the development of novel atherosclerosis therapies.

Physiological and transcriptional responses and cross protection of Lactobacillus plantarum ZDY2013 under acid stress.

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Huang, Renhui; Pan, Mingfang; Wan, Cuixiang; Shah, Nagendra P; Tao, Xueying; Wei, Hua

2016-02-01

Acid tolerance responses (ATR) in Lactobacillus plantarum ZDY2013 were investigated at physiological and molecular levels. A comparison of composition of cell membrane fatty acids (CMFA) between acid-challenged and unchallenged cells showed that acid adaptation evoked a significantly higher percentage of saturated fatty acids and cyclopropane fatty acids in acid-challenged than in unchallenged cells. In addition, reverse transcription-quantitative PCR analysis in acid-adapted cells at different pH values (ranging from 3.0 to 4.0) indicated that several genes were differently regulated, including those related to proton pumps, amino acid metabolism, sugar metabolism, and class I and class III stress response pathways. Expression of genes involved in fatty acid synthesis and production of alkali was significantly upregulated. Upon exposure to pH 4.5 for 2 h, a higher survival rate (higher viable cell count) of Lactobacillus plantarum ZDY2013 was achieved following an additional challenge to 40 mM hydrogen peroxide for 60 min, but no difference in survival rate of cells was found with further challenge to heat, ethanol, or salt. Therefore, we concluded that the physiological and metabolic changes of acid-treated cells of Lactobacillus plantarum ZDY2013 help the cells resist damage caused by acid, and further initiated global response signals to bring the whole cell into a state of defense to other stress factors, especially hydrogen peroxide. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

H3K36 Methylation Regulates Nutrient Stress Response in Saccharomyces cerevisiae by Enforcing Transcriptional Fidelity

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Stephen L. McDaniel

2017-06-01

Full Text Available Set2-mediated histone methylation at H3K36 regulates diverse activities, including DNA repair, mRNA splicing, and suppression of inappropriate (cryptic transcription. Although failure of Set2 to suppress cryptic transcription has been linked to decreased lifespan, the extent to which cryptic transcription influences other cellular functions is poorly understood. Here, we uncover a role for H3K36 methylation in the regulation of the nutrient stress response pathway. We found that the transcriptional response to nutrient stress was dysregulated in SET2-deleted (set2Δ cells and was correlated with genome-wide bi-directional cryptic transcription that originated from within gene bodies. Antisense transcripts arising from these cryptic events extended into the promoters of the genes from which they arose and were associated with decreased sense transcription under nutrient stress conditions. These results suggest that Set2-enforced transcriptional fidelity is critical to the proper regulation of inducible and highly regulated transcription programs.

Bmp indicator mice reveal dynamic regulation of transcriptional response.

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Anna L Javier

Full Text Available Cellular responses to Bmp ligands are regulated at multiple levels, both extracellularly and intracellularly. Therefore, the presence of these growth factors is not an accurate indicator of Bmp signaling activity. While a common approach to detect Bmp signaling activity is to determine the presence of phosphorylated forms of Smad1, 5 and 8 by immunostaining, this approach is time consuming and not quantitative. In order to provide a simpler readout system to examine the presence of Bmp signaling in developing animals, we developed BRE-gal mouse embryonic stem cells and a transgenic mouse line that specifically respond to Bmp ligand stimulation. Our reporter identifies specific transcriptional responses that are mediated by Smad1 and Smad4 with the Schnurri transcription factor complex binding to a conserved Bmp-Responsive Element (BRE, originally identified among Drosophila, Xenopus and human Bmp targets. Our BRE-gal mES cells specifically respond to Bmp ligands at concentrations as low as 5 ng/ml; and BRE-gal reporter mice, derived from the BRE-gal mES cells, show dynamic activity in many cellular sites, including extraembryonic structures and mammary glands, thereby making this a useful scientific tool.

The Venturia Apple Pathosystem: Pathogenicity Mechanisms and Plant Defense Responses

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Gopaljee Jha

2009-01-01

Full Text Available Venturia inaequalis is the causal agent of apple scab, a devastating disease of apple. We outline several unique features of this pathogen which are useful for molecular genetics studies intended to understand plant-pathogen interactions. The pathogenicity mechanisms of the pathogen and overview of apple defense responses, monogenic and polygenic resistance, and their utilization in scab resistance breeding programs are also reviewed.

Direct transcriptional activation of BT genes by NLP transcription factors is a key component of the nitrate response in Arabidopsis.

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Sato, Takeo; Maekawa, Shugo; Konishi, Mineko; Yoshioka, Nozomi; Sasaki, Yuki; Maeda, Haruna; Ishida, Tetsuya; Kato, Yuki; Yamaguchi, Junji; Yanagisawa, Shuichi

2017-01-29

Nitrate modulates growth and development, functioning as a nutrient signal in plants. Although many changes in physiological processes in response to nitrate have been well characterized as nitrate responses, the molecular mechanisms underlying the nitrate response are not yet fully understood. Here, we show that NLP transcription factors, which are key regulators of the nitrate response, directly activate the nitrate-inducible expression of BT1 and BT2 encoding putative scaffold proteins with a plant-specific domain structure in Arabidopsis. Interestingly, the 35S promoter-driven expression of BT2 partially rescued growth inhibition caused by reductions in NLP activity in Arabidopsis. Furthermore, simultaneous disruption of BT1 and BT2 affected nitrate-dependent lateral root development. These results suggest that direct activation of BT1 and BT2 by NLP transcriptional activators is a key component of the molecular mechanism underlying the nitrate response in Arabidopsis. Copyright © 2016 Elsevier Inc. All rights reserved.

HvWRKY10, HvWRKY19, and HvWRKY28 positively regulate Mla-triggered immunity and basal defense to barley powdery mildew

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WRKY proteins represent a large family of transcription factors (TFs), involved in plant development and defense responses. So far, fifty-five unique barley TFs have been annotated that contain the WRKY domain; twenty-six of these are present on the Barley1 GeneChip. We analyzed time-course expres...

Regulation of basophil and mast cell development by transcription factors

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Haruka Sasaki

2016-04-01

Full Text Available Basophils and mast cells play important roles in host defense against parasitic infections and allergic responses. Several progenitor populations, either shared or specific, for basophils and/or mast cells have been identified, thus elucidating the developmental pathways of these cells. Multiple transcription factors essential for their development and the relationships between them have been also revealed. For example, IRF8 induces GATA2 expression to promote the generation of both basophils and mast cells. The STAT5-GATA2 axis induces C/EBPα and MITF expression, facilitating the differentiation into basophils and mast cells, respectively. In addition, C/EBPα and MITF mutually suppress each other's expression. This review provides an overview of recent advances in our understanding of how transcription factors regulate the development of basophils and mast cells.

The nuclear immune receptor RPS4 is required for RRS1SLH1-dependent constitutive defense activation in Arabidopsis thaliana.

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Kee Hoon Sohn

2014-10-01

Full Text Available Plant nucleotide-binding leucine-rich repeat (NB-LRR disease resistance (R proteins recognize specific "avirulent" pathogen effectors and activate immune responses. NB-LRR proteins structurally and functionally resemble mammalian Nod-like receptors (NLRs. How NB-LRR and NLR proteins activate defense is poorly understood. The divergently transcribed Arabidopsis R genes, RPS4 (resistance to Pseudomonas syringae 4 and RRS1 (resistance to Ralstonia solanacearum 1, function together to confer recognition of Pseudomonas AvrRps4 and Ralstonia PopP2. RRS1 is the only known recessive NB-LRR R gene and encodes a WRKY DNA binding domain, prompting suggestions that it acts downstream of RPS4 for transcriptional activation of defense genes. We define here the early RRS1-dependent transcriptional changes upon delivery of PopP2 via Pseudomonas type III secretion. The Arabidopsis slh1 (sensitive to low humidity 1 mutant encodes an RRS1 allele (RRS1SLH1 with a single amino acid (leucine insertion in the WRKY DNA-binding domain. Its poor growth due to constitutive defense activation is rescued at higher temperature. Transcription profiling data indicate that RRS1SLH1-mediated defense activation overlaps substantially with AvrRps4- and PopP2-regulated responses. To better understand the genetic basis of RPS4/RRS1-dependent immunity, we performed a genetic screen to identify suppressor of slh1 immunity (sushi mutants. We show that many sushi mutants carry mutations in RPS4, suggesting that RPS4 acts downstream or in a complex with RRS1. Interestingly, several mutations were identified in a domain C-terminal to the RPS4 LRR domain. Using an Agrobacterium-mediated transient assay system, we demonstrate that the P-loop motif of RPS4 but not of RRS1SLH1 is required for RRS1SLH1 function. We also recapitulate the dominant suppression of RRS1SLH1 defense activation by wild type RRS1 and show this suppression requires an intact RRS1 P-loop. These analyses of RRS1SLH1 shed

Evaluating virulence of waterborne and clinical Aeromonas isolates using gene expression and mortality in neonatal mice followed by assessing cell culture’s ability to predict virulence based on transcriptional response

Energy Technology Data Exchange (ETDEWEB)

Hayes, S L; Rodgers, M R; Lye, D J; Stelma, G N; McKinstry, Craig A.; Malard, Joel M.; Vesper, Sephen J.

2007-10-01

Aims: To assess the virulence of Aeromonas spp. using two models, a neonatal mouse assay and a mouse intestinal cell culture. Methods and Results: After artificial infection with a variety of Aeromonas spp., mRNA extracts from the two models were processed and hydridized to murine microarrays to determine host gene response. Definition of virulence was determined based on host mRNA production in murine neonatal intestinal tissue and mortality of infected animals. Infections of mouse intestinal cell cultures were then performed to determine whether this simpler model system’s mRNA responses correlated to neonatal results and therefore be predictive of virulence of Aeromonas spp. Virulent aeromonads up-regulated transcripts in both models including multiple host defense gene products (chemokines, regulation of transcription and apoptosis and cell signalling). Avirulent species exhibited little or no host response in neonates. Mortality results correlated well with both bacterial dose and average fold change of up-regulated transcripts in the neonatal mice. Conclusions: Cell culture results were less discriminating but showed promise as potentially being able to be predictive of virulence. Jun oncogene up-regulation in murine cell culture is potentially predictive of Aeromonas virulence. Significance and Impact of the Study: Having the ability to determine virulence of waterborne pathogens quickly would potentially assist public health officials to rapidly assess exposure risks.

Nuclear Disarmament and the Insanity Defense: What Happened to Political Responsiveness?

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Fleming, John H.; Shaver, Kelly G.

A study which explored the degree to which belief in a politically responsive/unresponsive world might be related to opinions concerning nuclear disarmament, the insanity defense, and women's rights is described. A total of 206 male and female undergraduates completed a 63-item questionnaire consisting of 46 Likert-format I-E items and 17 attitude…

Hypoxia-Inducible Factor 3 Is an Oxygen-Dependent Transcription Activator and Regulates a Distinct Transcriptional Response to Hypoxia

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Peng Zhang

2014-03-01

Full Text Available Hypoxia-inducible factors (HIFs play key roles in the cellular response to hypoxia. It is widely accepted that whereas HIF-1 and HIF-2 function as transcriptional activators, HIF-3 inhibits HIF-1/2α action. Contrary to this idea, we show that zebrafish Hif-3α has strong transactivation activity. Hif-3α is degraded under normoxia. Mutation of P393, P493, and L503 inhibits this oxygen-dependent degradation. Transcriptomics and chromatin immunoprecipitation analyses identify genes that are regulated by Hif-3α, Hif-1α, or both. Under hypoxia or when overexpressed, Hif-3α binds to its target gene promoters and upregulates their expression. Dominant-negative inhibition and knockdown of Hif-3α abolish hypoxia-induced Hif-3α-promoter binding and gene expression. Hif-3α not only mediates hypoxia-induced growth and developmental retardation but also possesses hypoxia-independent activities. Importantly, transactivation activity is conserved and human HIF-3α upregulates similar genes in human cells. These findings suggest that Hif-3 is an oxygen-dependent transcription factor and activates a distinct transcriptional response to hypoxia.

Brassinosteroids-Induced Systemic Stress Tolerance was Associated with Increased Transcripts of Several Defence-Related Genes in the Phloem in Cucumis sativus.

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Pingfang Li

Full Text Available Brassinosteroids (BRs, a group of naturally occurring plant steroidal compounds, are essential for plant growth, development and stress tolerance. Recent studies showed that BRs could induce systemic tolerance to biotic and abiotic stresses; however, the molecular mechanisms by which BRs signals lead to responses in the whole plant are largely unknown. In this study, 24-epibrassinosteroid (EBR-induced systemic tolerance in Cucumis sativus L. cv. Jinyan No. 4 was analyzed through the assessment of symptoms of photooxidative stress by chlorophyll fluorescence imaging pulse amplitude modulation. Expression of defense/stress related genes were induced in both treated local leaves and untreated systemic leaves by local EBR application. With the suppressive subtractive hybridization (SSH library using cDNA from the phloem sap of EBR-treated plants as the tester and distilled water (DW-treated plants as the driver, 14 transcripts out of 260 clones were identified. Quantitative Real Time-Polymerase Chain Reaction (RT-qPCR validated the specific up-regulation of these transcripts. Of the differentially expressed transcripts with known functions, transcripts for the selected four cDNAs, which encode an auxin-responsive protein (IAA14, a putative ankyrin-repeat protein, an F-box protein (PP2, and a major latex, pathogenesis-related (MLP-like protein, were induced in local leaves, systemic leaves and roots after foliar application of EBR onto mature leaves. Our results demonstrated that EBR-induced systemic tolerance is accompanied with increased transcript of genes in the defense response in other organs. The potential role of phloem mRNAs as signaling components in mediating BR-regulated systemic resistance is discussed.

Defense Response in Slash Pine: Chitosan Treatment Alters the Abundance of Specific mRNAs

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Mary E. Mason; John M. Davis

1997-01-01

We used differential display to identify chitosan responsive cDNAs in slashpine cell cultures. Two clones that showed increased mRNA abundance had sequence similarity to genes with roles in major plant defense responses, clone 18 to cinnamic acid 4-hydroxylase, and clone 30 to chitinase.

Transcriptional Response of Rhodococcus aetherivorans I24 to Polychlorinated Biphenyl-Contaminated Sediments

KAUST Repository

Puglisi, Edoardo

2010-04-06

We used a microarray targeting 3,524 genes to assess the transcriptional response of the actinomycete Rhodococcus aetherivorans I24 in minimal medium supplemented with various substrates (e. g., PCBs) and in both PCB-contaminated and non-contaminated sediment slurries. Relative to the reference condition (minimal medium supplemented with glucose), 408 genes were upregulated in the various treatments. In medium and in sediment, PCBs elicited the upregulation of a common set of 100 genes, including gene-encoding chaperones (groEL), a superoxide dismutase (sodA), alkyl hydroperoxide reductase protein C (ahpC), and a catalase/peroxidase (katG). Analysis of the R. aetherivorans I24 genome sequence identified orthologs of many of the genes in the canonical biphenyl pathway, but very few of these genes were upregulated in response to PCBs or biphenyl. This study is one of the first to use microarrays to assess the transcriptional response of a soil bacterium to a pollutant under conditions that more closely resemble the natural environment. Our results indicate that the transcriptional response of R. aetherivorans I24 to PCBs, in both medium and sediment, is primarily directed towards reducing oxidative stress, rather than catabolism. © 2010 Springer Science+Business Media, LLC.

The response of Mycobacterium tuberculosis to reactive oxygen and nitrogen species

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Martin I Voskuil

2011-05-01

Full Text Available The bacteriostatic and bacteriocidal effects and the transcriptional response of Mycobacterium tuberculosis to representative oxidative and nitrosative stresses were investigated by growth and survival studies and whole genome expression analysis. The M. tuberculosis reaction to a range of hydrogen peroxide (H2O2 concentrations fell into three distinct categories: (1 low level exposure resulted in induction of a few highly sensitive H2O2-responsive genes, (2 intermediate exposure resulted in massive transcriptional changes without an effect on growth or survival, and (3 high exposure resulted in a muted transcriptional response and eventual death. M. tuberculosis appears highly resistant to DNA damage-dependent, mode-one killing caused by low millimolar levels of H2O2 and only succumbs to overwhelming levels of oxidative stress observed in mode-two killing. Nitric oxide (NO exposure initiated much the same transcriptional response as H2O2. However, unlike H2O2 exposure, NO exposure induced dormancy-related genes and caused dose-dependent bacteriostatic activity without killing. Included in the large shared response to H2O2 and NO was the induction of genes encoding iron-sulfur cluster repair functions including iron acquisition. Stress regulons controlled by IdeR, Sigma H, Sigma E, and FurA comprised a large portion of the response to both stresses. Expression of several oxidative stress defense genes was constitutive, or increased moderately from an already elevated constitutive level, suggesting that bacilli are continually primed for oxidative stress defense.

Transcriptional profiling of immune-related genes in Pacific white shrimp (Litopenaeus vannamei) during ontogenesis.

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Quispe, Ruth L; Justino, Emily B; Vieira, Felipe N; Jaramillo, Michael L; Rosa, Rafael D; Perazzolo, Luciane M

2016-11-01

We have performed here a gene expression analysis to determine the developmental stage at the main genes involved in crustacean immune response begin to be expressed and their changes in mRNA abundance during shrimp development. By using a quantitative PCR-based approach, we have measured the mRNA abundance of 24 immune-related genes from different functional categories in twelve developmental stages ranging from fertilized eggs to larval and postlarval stages and also in juveniles. We showed for the first time that the main genes from the RNAi-based post-transcriptional pathway involved in shrimp antiviral immunity are transcribed in all developmental stages, but exhibit a diverse pattern of gene expression during shrimp ontogenesis. On the other hand, hemocyte-expressed genes mainly involved in antimicrobial defenses appeared to be transcribed in larval stages, indicating that hematopoiesis initiates early in development. Moreover, transcript levels of some genes were early detected in fertilized eggs at 0-4 h post-spawning, suggesting a maternal contribution of immune-related transcripts to shrimp progeny. Altogether, our results provide important clues regarding the ontogenesis of hemocytes as well the establishment of antiviral and antimicrobial defenses in shrimp. Copyright © 2016 Elsevier Ltd. All rights reserved.

Transcriptomic changes during maize roots development responsive to Cadmium (Cd) pollution using comparative RNAseq-based approach

International Nuclear Information System (INIS)

Peng, Hua; He, Xiujing; Gao, Jian; Ma, Haixia; Zhang, Zhiming; Shen, Yaou; Pan, Guangtang; Lin, Haijian

2015-01-01

The heavy metal cadmium (Cd), acts as a widespread environmental contaminant, which has shown to adversely affect human health, food safety and ecosystem safety in recent years. However, research on how plant respond to various kinds of heavy metal stress is scarcely reported, especially for understanding of complex molecular regulatory mechanisms and elucidating the gene networks of plant respond to Cd stress. Here, transcriptomic changes during Mo17 and B73 seedlings development responsive to Cd pollution were investigated and comparative RNAseq-based approach in both genotypes were performed. 115 differential expression genes (DEGs) with significant alteration in expression were found co-modulated in both genotypes during the maize seedling development; of those, most of DGEs were found comprised of stress and defense responses proteins, transporters, as well as transcription factors, such as thaumatin-like protein, ZmOPR2 and ZmOPR5. More interestingly, genotype-specific transcriptional factors changes induced by Cd stress were found contributed to the regulatory mechanism of Cd sensitivity in both different genotypes. Moreover, 12 co-expression modules associated with specific biological processes or pathways (M1 to M12) were identified by consensus co-expression network. These results will expand our understanding of complex molecular mechanism of response and defense to Cd exposure in maize seedling roots. - Highlights: • Transcriptomic changes responsive to Cd pollution using comparative RNAseq-based approach. • 115 differential expression genes (DEGs) were found co-modulated in both genotypes. • Most of DGEs belong to stress and defense responses proteins, transporters, transcription factors. • 12 co-expression modules associated with specific biological processes or pathways. • Genotype-specific transcriptional factors changes induced by Cd stress were found

Transcriptomic changes during maize roots development responsive to Cadmium (Cd) pollution using comparative RNAseq-based approach

Energy Technology Data Exchange (ETDEWEB)

Peng, Hua [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China); Sichuan Tourism College, Chengdu, 610000, Sichuan (China); He, Xiujing [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China); Gao, Jian [Institute of Pathology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University, Key Laboratory of Tumor Immunopathology, Ministry of Education of China, Chongqing (China); Ma, Haixia; Zhang, Zhiming; Shen, Yaou [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China); Pan, Guangtang, E-mail: pangt@sicau.edu.cn [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China); Lin, Haijian, E-mail: linhj521@gmail.com [Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Wenjiang, Sichuan, 611130 (China)

2015-09-04

The heavy metal cadmium (Cd), acts as a widespread environmental contaminant, which has shown to adversely affect human health, food safety and ecosystem safety in recent years. However, research on how plant respond to various kinds of heavy metal stress is scarcely reported, especially for understanding of complex molecular regulatory mechanisms and elucidating the gene networks of plant respond to Cd stress. Here, transcriptomic changes during Mo17 and B73 seedlings development responsive to Cd pollution were investigated and comparative RNAseq-based approach in both genotypes were performed. 115 differential expression genes (DEGs) with significant alteration in expression were found co-modulated in both genotypes during the maize seedling development; of those, most of DGEs were found comprised of stress and defense responses proteins, transporters, as well as transcription factors, such as thaumatin-like protein, ZmOPR2 and ZmOPR5. More interestingly, genotype-specific transcriptional factors changes induced by Cd stress were found contributed to the regulatory mechanism of Cd sensitivity in both different genotypes. Moreover, 12 co-expression modules associated with specific biological processes or pathways (M1 to M12) were identified by consensus co-expression network. These results will expand our understanding of complex molecular mechanism of response and defense to Cd exposure in maize seedling roots. - Highlights: • Transcriptomic changes responsive to Cd pollution using comparative RNAseq-based approach. • 115 differential expression genes (DEGs) were found co-modulated in both genotypes. • Most of DGEs belong to stress and defense responses proteins, transporters, transcription factors. • 12 co-expression modules associated with specific biological processes or pathways. • Genotype-specific transcriptional factors changes induced by Cd stress were found.

Dynamic extrafloral nectar production: the timing of leaf damage affects the defensive response in Senna mexicana var. chapmanii (Fabaceae).

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Jones, Ian M; Koptur, Suzanne

2015-01-01

• Extrafloral nectar (EFN) mediates food for protection mutualisms between plants and defensive insects. Understanding sources of variation in EFN production is important because such variations may affect the number and identity of visitors and the effectiveness of plant defense. We investigated the influence of plant developmental stage, time of day, leaf age, and leaf damage on EFN production in Senna mexicana var. chapmanii. The observed patterns of variation in EFN production were compared with those predicted by optimal defense theory.• Greenhouse experiments with potted plants were conducted to determine how plant age, time of day, and leaf damage affected EFN production. A subsequent field study was conducted to determine how leaf damage, and the resulting increase in EFN production, affected ant visitation in S. chapmanii.• More nectar was produced at night and by older plants. Leaf damage resulted in increased EFN production, and the magnitude of the response was greater in plants damaged in the morning than those damaged at night. Damage to young leaves elicited a stronger defensive response than damage to older leaves, in line with optimal defense theory. Damage to the leaves of S. chapmanii also resulted in significantly higher ant visitation in the field.• Extrafloral nectar is an inducible defense in S. chapmanii. Developmental variations in its production support the growth differentiation balance hypothesis, while within-plant variations and damage responses support optimal defense theory. © 2015 Botanical Society of America, Inc.

A rice gene of de novo origin negatively regulates pathogen-induced defense response.

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Wenfei Xiao

Full Text Available How defense genes originated with the evolution of their specific pathogen-responsive traits remains an important problem. It is generally known that a form of duplication can generate new genes, suggesting that a new gene usually evolves from an ancestral gene. However, we show that a new defense gene in plants may evolve by de novo origination, resulting in sophisticated disease-resistant functions in rice. Analyses of gene evolution showed that this new gene, OsDR10, had homologs only in the closest relative, Leersia genus, but not other subfamilies of the grass family; therefore, it is a rice tribe-specific gene that may have originated de novo in the tribe. We further show that this gene may evolve a highly conservative rice-specific function that contributes to the regulation difference between rice and other plant species in response to pathogen infections. Biologic analyses including gene silencing, pathologic analysis, and mutant characterization by transformation showed that the OsDR10-suppressed plants enhanced resistance to a broad spectrum of Xanthomonas oryzae pv. oryzae strains, which cause bacterial blight disease. This enhanced disease resistance was accompanied by increased accumulation of endogenous salicylic acid (SA and suppressed accumulation of endogenous jasmonic acid (JA as well as modified expression of a subset of defense-responsive genes functioning both upstream and downstream of SA and JA. These data and analyses provide fresh insights into the new biologic and evolutionary processes of a de novo gene recruited rapidly.

Ubiquitin ligase activity of TFIIH and the transcriptional response to DNA damage.

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Takagi, Yuichiro; Masuda, Claudio A; Chang, Wei-Hau; Komori, Hirofumi; Wang, Dong; Hunter, Tony; Joazeiro, Claudio A P; Kornberg, Roger D

2005-04-15

Core transcription factor (TF) IIH purified from yeast possesses an E3 ubiquitin (Ub) ligase activity, which resides, at least in part, in a RING finger (RNF) domain of the Ssl1 subunit. Yeast strains mutated in the Ssl1 RNF domain are sensitive to ultraviolet (UV) light and to methyl methanesulfonate (MMS). This increased sensitivity to DNA-damaging agents does not reflect a deficiency in nucleotide excision repair. Rather, it correlates with reduced transcriptional induction of genes involved in DNA repair, suggesting that the E3 Ub ligase activity of TFIIH mediates the transcriptional response to DNA damage.

Proteomic identification of early salicylate- and flg22-responsive redox-sensitive proteins in Arabidopsis

KAUST Repository

Liu, Peng

2015-02-27

Accumulation of reactive oxygen species (ROS) is one of the early defense responses against pathogen infection in plants. The mechanism about the initial and direct regulation of the defense signaling pathway by ROS remains elusive. Perturbation of cellular redox homeostasis by ROS is believed to alter functions of redox-sensitive proteins through their oxidative modifications. Here we report an OxiTRAQ-based proteomic study in identifying proteins whose cysteines underwent oxidative modifications in Arabidopsis cells during the early response to salicylate or flg22, two defense pathway elicitors that are known to disturb cellular redox homeostasis. Among the salicylate- and/or flg22-responsive redox-sensitive proteins are those involved in transcriptional regulation, chromatin remodeling, RNA processing, post-translational modifications, and nucleocytoplasmic shuttling. The identification of the salicylate-/flg22-responsive redox-sensitive proteins provides a foundation from which further study can be conducted toward understanding biological significance of their oxidative modifications during the plant defense response.

Resistance to Plasmopara viticola in a grapevine segregating population is associated with stilbenoid accumulation and with specific host transcriptional responses

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Delledonne Massimo

2011-08-01

revealed that they belong to the categories defense response, photosynthesis, primary and secondary metabolism, signal transduction and transport. Conclusions This study reports the results of a combined metabolic and transcriptional profiling of a grapevine population segregating for resistance to P. viticola. Some resistant individuals were identified and further characterized at the molecular level. These results will be valuable to future grapevine breeding programs.

The global transcriptional response of fission yeast to hydrogen sulfide.

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Xu Jia

Full Text Available BACKGROUND: Hydrogen sulfide (H(2S is a newly identified member of the small family of gasotransmitters that are endogenous gaseous signaling molecules that have a fundamental role in human biology and disease. Although it is a relatively recent discovery and the mechanism of H(2S activity is not completely understood, it is known to be involved in a number of cellular processes; H(2S can affect ion channels, transcription factors and protein kinases in mammals. METHODOLOGY/PRINCIPAL FINDINGS: In this paper, we have used fission yeast as a model organism to study the global gene expression profile in response to H(2S by microarray. We initially measured the genome-wide transcriptional response of fission yeast to H(2S. Through the functional classification of genes whose expression profile changed in response to H(2S, we found that H(2S mainly influences genes that encode putative or known stress proteins, membrane transporters, cell cycle/meiotic proteins, transcription factors and respiration protein in the mitochondrion. Our analysis showed that there was a significant overlap between the genes affected by H(2S and the stress response. We identified that the target genes of the MAPK pathway respond to H(2S; we also identified that a number of transporters respond to H(2S, these include sugar/carbohydrate transporters, ion transporters, and amino acid transporters. We found many mitochondrial genes to be down regulated upon H(2S treatment and that H(2S can reduce mitochondrial oxygen consumption. CONCLUSION/SIGNIFICANCE: This study identifies potential molecular targets of the signaling molecule H(2S in fission yeast and provides clues about the identity of homologues human proteins and will further the understanding of the cellular role of H(2S in human diseases.

Effectors from Wheat Rust Fungi Suppress Multiple Plant Defense Responses.

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Ramachandran, Sowmya R; Yin, Chuntao; Kud, Joanna; Tanaka, Kiwamu; Mahoney, Aaron K; Xiao, Fangming; Hulbert, Scot H

2017-01-01

Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection, the fungus secretes a number of effector proteins. Although a large repository of putative effectors has been predicted using bioinformatic pipelines, the lack of available high-throughput effector screening systems has limited functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and P. striiformis to look for potential effectors that suppress host hypersensitive response (HR). Twenty small (wheat, confirming its activity in a homologous system. Overall, this study provides the first evidence for the presence of effectors in Puccinia species suppressing multiple plant defense responses.

Transcription-based prediction of response to IFNbeta using supervised computational methods.

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Sergio E Baranzini

2005-01-01

Full Text Available Changes in cellular functions in response to drug therapy are mediated by specific transcriptional profiles resulting from the induction or repression in the activity of a number of genes, thereby modifying the preexisting gene activity pattern of the drug-targeted cell(s. Recombinant human interferon beta (rIFNbeta is routinely used to control exacerbations in multiple sclerosis patients with only partial success, mainly because of adverse effects and a relatively large proportion of nonresponders. We applied advanced data-mining and predictive modeling tools to a longitudinal 70-gene expression dataset generated by kinetic reverse-transcription PCR from 52 multiple sclerosis patients treated with rIFNbeta to discover higher-order predictive patterns associated with treatment outcome and to define the molecular footprint that rIFNbeta engraves on peripheral blood mononuclear cells. We identified nine sets of gene triplets whose expression, when tested before the initiation of therapy, can predict the response to interferon beta with up to 86% accuracy. In addition, time-series analysis revealed potential key players involved in a good or poor response to interferon beta. Statistical testing of a random outcome class and tolerance to noise was carried out to establish the robustness of the predictive models. Large-scale kinetic reverse-transcription PCR, coupled with advanced data-mining efforts, can effectively reveal preexisting and drug-induced gene expression signatures associated with therapeutic effects.

Characterization of the rapid transcriptional response to long-term sensitization training in Aplysia californica.

Science.gov (United States)

Herdegen, Samantha; Holmes, Geraldine; Cyriac, Ashly; Calin-Jageman, Irina E; Calin-Jageman, Robert J

2014-12-01

We used a custom-designed microarray and quantitative PCR to characterize the rapid transcriptional response to long-term sensitization training in the marine mollusk Aplysia californica. Aplysia were exposed to repeated noxious shocks to one side of the body, a procedure known to induce a long-lasting, transcription-dependent increase in reflex responsiveness that is restricted to the side of training. One hour after training, pleural ganglia from the trained and untrained sides of the body were harvested; these ganglia contain the sensory nociceptors which help mediate the expression of long-term sensitization memory. Microarray analysis from 8 biological replicates suggests that long-term sensitization training rapidly regulates at least 81 transcripts. We used qPCR to test a subset of these transcripts and found that 83% were confirmed in the same samples, and 86% of these were again confirmed in an independent sample. Thus, our new microarray design shows strong convergent and predictive validity for analyzing the transcriptional correlates of memory in Aplysia. Fully validated transcripts include some previously identified as regulated in this paradigm (ApC/EBP and ApEgr) but also include novel findings. Specifically, we show that long-term sensitization training rapidly up-regulates the expression of transcripts which may encode Aplysia homologs of a C/EBPγ transcription factor, a glycine transporter (GlyT2), and a vacuolar-protein-sorting-associated protein (VPS36). Copyright © 2014 Elsevier Inc. All rights reserved.

Endoplasmic Reticulum Lipid Flux Influences Enterocyte Nuclear Morphology and Lipid-dependent Transcriptional Responses.

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Zeituni, Erin M; Wilson, Meredith H; Zheng, Xiaobin; Iglesias, Pablo A; Sepanski, Michael A; Siddiqi, Mahmud A; Anderson, Jennifer L; Zheng, Yixian; Farber, Steven A

2016-11-04

Responding to a high-fat meal requires an interplay between multiple digestive tissues, sympathetic response pathways, and the gut microbiome. The epithelial enterocytes of the intestine are responsible for absorbing dietary nutrients and preparing them for circulation to distal tissues, which requires significant changes in cellular activity, including both morphological and transcriptional responses. Following a high-fat meal, we observe morphological changes in the enterocytes of larval zebrafish, including elongation of mitochondria, formation and expansion of lipid droplets, and the rapid and transient ruffling of the nuclear periphery. Dietary and pharmacological manipulation of zebrafish larvae demonstrated that these subcellular changes are specific to triglyceride absorption. The transcriptional changes that occur simultaneously with these morphological changes were determined using RNA sequencing, revealing a cohort of up-regulated genes associated with lipid droplet formation and lipid transport via lipoprotein particles. Using a microsomal triglyceride transfer protein (MTP) inhibitor to block β-lipoprotein particle formation, we demonstrate that the transcriptional response to a high-fat meal is associated with the transfer of ER triglyceride to nascent β-lipoproteins, possibly through the activation of Creb3l3/cyclic AMP-responsive element-binding protein. These data suggest that a transient increase in ER lipids is the likely mediator of the initial physiological response of intestinal enterocytes to dietary lipid. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Endoplasmic Reticulum Lipid Flux Influences Enterocyte Nuclear Morphology and Lipid-dependent Transcriptional Responses*

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Zeituni, Erin M.; Wilson, Meredith H.; Zheng, Xiaobin; Iglesias, Pablo A.; Sepanski, Michael A.; Siddiqi, Mahmud A.; Anderson, Jennifer L.; Zheng, Yixian; Farber, Steven A.

2016-01-01

Responding to a high-fat meal requires an interplay between multiple digestive tissues, sympathetic response pathways, and the gut microbiome. The epithelial enterocytes of the intestine are responsible for absorbing dietary nutrients and preparing them for circulation to distal tissues, which requires significant changes in cellular activity, including both morphological and transcriptional responses. Following a high-fat meal, we observe morphological changes in the enterocytes of larval zebrafish, including elongation of mitochondria, formation and expansion of lipid droplets, and the rapid and transient ruffling of the nuclear periphery. Dietary and pharmacological manipulation of zebrafish larvae demonstrated that these subcellular changes are specific to triglyceride absorption. The transcriptional changes that occur simultaneously with these morphological changes were determined using RNA sequencing, revealing a cohort of up-regulated genes associated with lipid droplet formation and lipid transport via lipoprotein particles. Using a microsomal triglyceride transfer protein (MTP) inhibitor to block β-lipoprotein particle formation, we demonstrate that the transcriptional response to a high-fat meal is associated with the transfer of ER triglyceride to nascent β-lipoproteins, possibly through the activation of Creb3l3/cyclic AMP-responsive element-binding protein. These data suggest that a transient increase in ER lipids is the likely mediator of the initial physiological response of intestinal enterocytes to dietary lipid. PMID:27655916

PtrWRKY73, a salicylic acid-inducible poplar WRKY transcription factor, is involved in disease resistance in Arabidopsis thaliana.

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Duan, Yanjiao; Jiang, Yuanzhong; Ye, Shenglong; Karim, Abdul; Ling, Zhengyi; He, Yunqiu; Yang, Siqi; Luo, Keming

2015-05-01

A salicylic acid-inducible WRKY gene, PtrWRKY73, from Populus trichocarpa , was isolated and characterized. Overexpression of PtrWRKY73 in Arabidopsis thaliana increased resistance to biotrophic pathogens but reduced resistance against necrotrophic pathogens. WRKY transcription factors are commonly involved in plant defense responses. However, limited information is available about the roles of the WRKY genes in poplar defense. In this study, we isolated a salicylic acid (SA)-inducible WRKY gene, PtrWRKY73, from Populus trichocarpa, belonging to group I family and containing two WRKY domains, a D domain and an SP cluster. PtrWRKY73 was expressed predominantly in roots, old leaves, sprouts and stems, especially in phloem and its expression was induced in response to treatment with exogenous SA. PtrWRKY73 was localized to the nucleus of plant cells and exhibited transcriptional activation. Overexpression of PtrWRKY73 in Arabidopsis thaliana resulted in increased resistance to a virulent strain of the bacterial pathogen Pseudomonas syringae (PstDC3000), but more sensitivity to the necrotrophic fungal pathogen Botrytis cinerea. The SA-mediated defense-associated genes, such as PR1, PR2 and PAD4, were markedly up-regulated in transgenic plants overexpressing PtrWRKY73. Arabidopsis non-expressor of PR1 (NPR1) was not affected, whereas a defense-related gene PAL4 had reduced in PtrWRKY73 overexpressor plants. Together, these results indicated that PtrWRKY73 plays a positive role in plant resistance to biotrophic pathogens but a negative effect on resistance against necrotrophic pathogens.

A central regulatory system largely controls transcriptional activation and repression responses to phosphate starvation in Arabidopsis.

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Regla Bustos

2010-09-01

Full Text Available Plants respond to different stresses by inducing or repressing transcription of partially overlapping sets of genes. In Arabidopsis, the PHR1 transcription factor (TF has an important role in the control of phosphate (Pi starvation stress responses. Using transcriptomic analysis of Pi starvation in phr1, and phr1 phr1-like (phl1 mutants and in wild type plants, we show that PHR1 in conjunction with PHL1 controls most transcriptional activation and repression responses to phosphate starvation, regardless of the Pi starvation specificity of these responses. Induced genes are enriched in PHR1 binding sequences (P1BS in their promoters, whereas repressed genes do not show such enrichment, suggesting that PHR1(-like control of transcriptional repression responses is indirect. In agreement with this, transcriptomic analysis of a transgenic plant expressing PHR1 fused to the hormone ligand domain of the glucocorticoid receptor showed that PHR1 direct targets (i.e., displaying altered expression after GR:PHR1 activation by dexamethasone in the presence of cycloheximide corresponded largely to Pi starvation-induced genes that are highly enriched in P1BS. A minimal promoter containing a multimerised P1BS recapitulates Pi starvation-specific responsiveness. Likewise, mutation of P1BS in the promoter of two Pi starvation-responsive genes impaired their responsiveness to Pi starvation, but not to other stress types. Phylogenetic footprinting confirmed the importance of P1BS and PHR1 in Pi starvation responsiveness and indicated that P1BS acts in concert with other cis motifs. All together, our data show that PHR1 and PHL1 are partially redundant TF acting as central integrators of Pi starvation responses, both specific and generic. In addition, they indicate that transcriptional repression responses are an integral part of adaptive responses to stress.

Key Components of Different Plant Defense Pathways Are Dispensable for Powdery Mildew Resistance of the Arabidopsis mlo2 mlo6 mlo12 Triple Mutant.

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Kuhn, Hannah; Lorek, Justine; Kwaaitaal, Mark; Consonni, Chiara; Becker, Katia; Micali, Cristina; Ver Loren van Themaat, Emiel; Bednarek, Paweł; Raaymakers, Tom M; Appiano, Michela; Bai, Yuling; Meldau, Dorothea; Baum, Stephani; Conrath, Uwe; Feussner, Ivo; Panstruga, Ralph

2017-01-01

Loss of function mutations of particular plant MILDEW RESISTANCE LOCUS O ( MLO ) genes confer durable and broad-spectrum penetration resistance against powdery mildew fungi. Here, we combined genetic, transcriptomic and metabolomic analyses to explore the defense mechanisms in the fully resistant Arabidopsis thaliana mlo2 mlo6 mlo12 triple mutant. We found that this genotype unexpectedly overcomes the requirement for indolic antimicrobials and defense-related secretion, which are critical for incomplete resistance of mlo2 single mutants. Comparative microarray-based transcriptome analysis of mlo2 mlo6 mlo12 mutants and wild type plants upon Golovinomyces orontii inoculation revealed an increased and accelerated accumulation of many defense-related transcripts. Despite the biotrophic nature of the interaction, this included the non-canonical activation of a jasmonic acid/ethylene-dependent transcriptional program. In contrast to a non-adapted powdery mildew pathogen, the adapted powdery mildew fungus is able to defeat the accumulation of defense-relevant indolic metabolites in a MLO protein-dependent manner. We suggest that a broad and fast activation of immune responses in mlo2 mlo6 mlo12 plants can compensate for the lack of single or few defense pathways. In addition, our results point to a role of Arabidopsis MLO2, MLO6, and MLO12 in enabling defense suppression during invasion by adapted powdery mildew fungi.

Identification of PEG-induced water stress responsive transcripts using co-expression network in Eucalyptus grandis.

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Ghosh Dasgupta, Modhumita; Dharanishanthi, Veeramuthu

2017-09-05

Ecophysiological studies in Eucalyptus have shown that water is the principal factor limiting stem growth. Effect of water deficit conditions on physiological and biochemical parameters has been extensively reported in Eucalyptus. The present study was conducted to identify major polyethylene glycol induced water stress responsive transcripts in Eucalyptus grandis using gene co-expression network. A customized array representing 3359 water stress responsive genes was designed to document their expression in leaves of E. grandis cuttings subjected to -0.225MPa of PEG treatment. The differentially expressed transcripts were documented and significantly co-expressed transcripts were used for construction of network. The co-expression network was constructed with 915 nodes and 3454 edges with degree ranging from 2 to 45. Ninety four GO categories and 117 functional pathways were identified in the network. MCODE analysis generated 27 modules and module 6 with 479 nodes and 1005 edges was identified as the biologically relevant network. The major water responsive transcripts represented in the module included dehydrin, osmotin, LEA protein, expansin, arabinogalactans, heat shock proteins, major facilitator proteins, ARM repeat proteins, raffinose synthase, tonoplast intrinsic protein and transcription factors like DREB2A, ARF9, AGL24, UNE12, WLIM1 and MYB66, MYB70, MYB 55, MYB 16 and MYB 103. The coordinated analysis of gene expression patterns and coexpression networks developed in this study identified an array of transcripts that may regulate PEG induced water stress responses in E. grandis. Copyright © 2017 Elsevier B.V. All rights reserved.

Innate immune responses: Crosstalk of signaling and regulation of gene transcription

International Nuclear Information System (INIS)

Zhong Bo; Tien Po; Shu Hongbing

2006-01-01

Innate immune responses to pathogens such as bacteria and viruses are triggered by recognition of specific structures of invading pathogens called pathogen-associated molecular patterns (PAMPs) by cellular pattern recognition receptors (PRRs) that are located at plasma membrane or inside cells. Stimulation of different PAMPs activates Toll-like receptor (TLR)-dependent and -independent signaling pathways that lead to activation of transcription factors nuclear factor-κB (NF-κB), interferon regulatory factor 3/7 (IRF3/7) and/or activator protein-1 (AP-1), which collaborate to induce transcription of a large number of downstream genes. This review focuses on the rapid progress that has recently improved our understanding of the crosstalk among the pathways and the precise regulation of transcription of the downstream genes

Sugarcane genes differentially expressed in response to Puccinia melanocephala infection: identification and transcript profiling.

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Oloriz, María I; Gil, Víctor; Rojas, Luis; Portal, Orelvis; Izquierdo, Yovanny; Jiménez, Elio; Höfte, Monica

2012-05-01

Brown rust caused by the fungus Puccinia melanocephala is a major disease of sugarcane (Saccharum spp.). A sugarcane mutant, obtained by chemical mutagenesis of the susceptible variety B4362, showed a post-haustorial hypersensitive response (HR)-mediated resistance to the pathogen and was used to identify genes differentially expressed in response to P. melanocephala via suppression subtractive hybridization (SSH). Tester cDNA was derived from the brown rust-resistant mutant after inoculation with P. melanocephala, while driver cDNAs were obtained from the non-inoculated resistant mutant and the inoculated susceptible donor variety B4362. Database comparisons of the sequences of the SSH recombinant clones revealed that, of a subset of 89 non-redundant sequences, 88% had similarity to known functional genes, while 12% were of unknown function. Thirteen genes were selected for transcript profiling in the resistant mutant and the susceptible donor variety. Genes involved in glycolysis and C4 carbon fixation were up-regulated in both interactions probably due to disturbance of sugarcane carbon metabolism by the pathogen. Genes related with the nascent polypeptide associated complex, post-translational proteome modulation and autophagy were transcribed at higher levels in the compatible interaction. Up-regulation of a putative L-isoaspartyl O-methyltransferase S-adenosylmethionine gene in the compatible interaction may point to fungal manipulation of the cytoplasmatic methionine cycle. Genes coding for a putative no apical meristem protein, S-adenosylmethionine decarboxylase, non-specific lipid transfer protein, and GDP-L-galactose phosphorylase involved in ascorbic acid biosynthesis were up-regulated in the incompatible interaction at the onset of haustorium formation, and may contribute to the HR-mediated defense response in the rust-resistant mutant.

Transgenerational effects and impact of compensatory responses to changes in breeding phenology on antipredator defenses.

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Orizaola, Germán; Richter-Boix, Alex; Laurila, Anssi

2016-09-01

As organisms living in temperate environments often have only a short time window for growth and reproduction, their life-history strategies are expected to be influenced by these time constraints. Parents may alter the pace of offspring life-history as a response to changes in breeding phenology. However, the responses to changes in time constraints must be balanced with those against other stressors, such as predation, one of the strongest and more ubiquitous selective factors in nature. Here, after experimentally modifying the timing of breeding and hatching in the moor frog (Rana arvalis), we studied how compensatory responses to delayed breeding and hatching affect antipredator strategies in amphibian larvae. We examined the activity patterns, morphology and life-history responses in tadpoles exposed to different combinations of breeding and hatching delays in the presence and absence of predators. We found clear evidence of adaptive transgenerational effects since tadpoles from delayed breeding treatments increased growth and development independently of predation risk. The presence of predators reduced tadpole activity, tadpoles from delayed breeding treatments maintaining lower activity than non-delayed ones also in the absence of predators. Tadpoles reared with predators developed deeper tails and bodies, however, tadpoles from breeding delay treatments had reduced morphological defenses as compared to non-delayed individuals. No significant effects of hatching delay were detected in this study. Our study reveals that amphibian larvae exposed to breeding delay develop compensatory life-history responses even under predation risk, but these responses trade-off with the development of morphological antipredator defenses. These results suggest that under strong time constraints organisms are selected to develop fast growth and development responses, and rely on lower activity rates as their main antipredator defense. Examining how responses to changes in

Comparative transcriptional and translational analysis of leptospiral outer membrane protein expression in response to temperature.

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Lo, Miranda; Cordwell, Stuart J; Bulach, Dieter M; Adler, Ben

2009-12-08

Leptospirosis is a global zoonosis affecting millions of people annually. Transcriptional changes in response to temperature were previously investigated using microarrays to identify genes potentially expressed upon host entry. Past studies found that various leptospiral outer membrane proteins are differentially expressed at different temperatures. However, our microarray studies highlighted a divergence between protein abundance and transcript levels for some proteins. Given the abundance of post-transcriptional expression control mechanisms, this finding highlighted the importance of global protein analysis systems. To complement our previous transcription study, we evaluated differences in the proteins of the leptospiral outer membrane fraction in response to temperature upshift. Outer membrane protein-enriched fractions from Leptospira interrogans grown at 30 degrees C or overnight upshift to 37 degrees C were isolated and the relative abundance of each protein was determined by iTRAQ analysis coupled with two-dimensional liquid chromatography and tandem mass spectrometry (2-DLC/MS-MS). We identified 1026 proteins with 99% confidence; 27 and 66 were present at elevated and reduced abundance respectively. Protein abundance changes were compared with transcriptional differences determined from the microarray studies. While there was some correlation between the microarray and iTRAQ data, a subset of genes that showed no differential expression by microarray was found to encode temperature-regulated proteins. This set of genes is of particular interest as it is likely that regulation of their expression occurs post-transcriptionally, providing an opportunity to develop hypotheses about the molecular dynamics of the outer membrane of Leptospira in response to changing environments. This is the first study to compare transcriptional and translational responses to temperature shift in L. interrogans. The results thus provide an insight into the mechanisms used by L

Comparative transcriptional and translational analysis of leptospiral outer membrane protein expression in response to temperature.

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Miranda Lo

Full Text Available BACKGROUND: Leptospirosis is a global zoonosis affecting millions of people annually. Transcriptional changes in response to temperature were previously investigated using microarrays to identify genes potentially expressed upon host entry. Past studies found that various leptospiral outer membrane proteins are differentially expressed at different temperatures. However, our microarray studies highlighted a divergence between protein abundance and transcript levels for some proteins. Given the abundance of post-transcriptional expression control mechanisms, this finding highlighted the importance of global protein analysis systems. METHODOLOGY/PRINCIPAL FINDINGS: To complement our previous transcription study, we evaluated differences in the proteins of the leptospiral outer membrane fraction in response to temperature upshift. Outer membrane protein-enriched fractions from Leptospira interrogans grown at 30 degrees C or overnight upshift to 37 degrees C were isolated and the relative abundance of each protein was determined by iTRAQ analysis coupled with two-dimensional liquid chromatography and tandem mass spectrometry (2-DLC/MS-MS. We identified 1026 proteins with 99% confidence; 27 and 66 were present at elevated and reduced abundance respectively. Protein abundance changes were compared with transcriptional differences determined from the microarray studies. While there was some correlation between the microarray and iTRAQ data, a subset of genes that showed no differential expression by microarray was found to encode temperature-regulated proteins. This set of genes is of particular interest as it is likely that regulation of their expression occurs post-transcriptionally, providing an opportunity to develop hypotheses about the molecular dynamics of the outer membrane of Leptospira in response to changing environments. CONCLUSIONS/SIGNIFICANCE: This is the first study to compare transcriptional and translational responses to temperature

Tye7 regulates yeast Ty1 retrotransposon sense and antisense transcription in response to adenylic nucleotides stress.

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Servant, Géraldine; Pinson, Benoit; Tchalikian-Cosson, Aurélie; Coulpier, Fanny; Lemoine, Sophie; Pennetier, Carole; Bridier-Nahmias, Antoine; Todeschini, Anne Laure; Fayol, Hélène; Daignan-Fornier, Bertrand; Lesage, Pascale

2012-07-01

Transposable elements play a fundamental role in genome evolution. It is proposed that their mobility, activated under stress, induces mutations that could confer advantages to the host organism. Transcription of the Ty1 LTR-retrotransposon of Saccharomyces cerevisiae is activated in response to a severe deficiency in adenylic nucleotides. Here, we show that Ty2 and Ty3 are also stimulated under these stress conditions, revealing the simultaneous activation of three active Ty retrotransposon families. We demonstrate that Ty1 activation in response to adenylic nucleotide depletion requires the DNA-binding transcription factor Tye7. Ty1 is transcribed in both sense and antisense directions. We identify three Tye7 potential binding sites in the region of Ty1 DNA sequence where antisense transcription starts. We show that Tye7 binds to Ty1 DNA and regulates Ty1 antisense transcription. Altogether, our data suggest that, in response to adenylic nucleotide reduction, TYE7 is induced and activates Ty1 mRNA transcription, possibly by controlling Ty1 antisense transcription. We also provide the first evidence that Ty1 antisense transcription can be regulated by environmental stress conditions, pointing to a new level of control of Ty1 activity by stress, as Ty1 antisense RNAs play an important role in regulating Ty1 mobility at both the transcriptional and post-transcriptional stages.

Chk2 regulates transcription-independent p53-mediated apoptosis in response to DNA damage

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Chen Chen; Shimizu, Shigeomi; Tsujimoto, Yoshihide; Motoyama, Noboru

2005-01-01

The tumor suppressor protein p53 plays a central role in the induction of apoptosis in response to genotoxic stress. The protein kinase Chk2 is an important regulator of p53 function in mammalian cells exposed to ionizing radiation (IR). Cells derived from Chk2-deficient mice are resistant to the induction of apoptosis by IR, and this resistance has been thought to be a result of the defective transcriptional activation of p53 target genes. It was recently shown, however, that p53 itself and histone H1.2 translocate to mitochondria and thereby induces apoptosis in a transcription-independent manner in response to IR. We have now examined whether Chk2 also regulates the transcription-independent induction of apoptosis by p53 and histone H1.2. The reduced ability of IR to induce p53 stabilization in Chk2-deficient thymocytes was associated with a marked impairment of p53 and histone H1 translocation to mitochondria. These results suggest that Chk2 regulates the transcription-independent mechanism of p53-mediated apoptosis by inducing stabilization of p53 in response to IR

Different transcriptional response to Xanthomonas citri subsp. citri between kumquat and sweet orange with contrasting canker tolerance.

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Xing-Zheng Fu

Full Text Available Citrus canker disease caused by Xanthomonas citri subsp. citri (Xcc is one of the most devastating biotic stresses affecting the citrus industry. Meiwa kumquat (Fortunella crassifolia is canker-resistant, while Newhall navel orange (Citrus sinensis Osbeck is canker-sensitive. To understand the molecular mechanisms underlying the differences in responses to Xcc, transcriptomic profiles of these two genotypes following Xcc attack were compared by using the Affymetrix citrus genome GeneChip. A total of 794 and 1324 differentially expressed genes (DEGs were identified as canker-responsive genes in Meiwa and Newhall, respectively. Of these, 230 genes were expressed in common between both genotypes, while 564 and 1094 genes were only significantly expressed in either Meiwa or Newhall. Gene ontology (GO annotation and Singular Enrichment Analysis (SEA of the DEGs showed that genes related to the cell wall and polysaccharide metabolism were induced for basic defense in both Meiwa and Newhall, such as chitinase, glucanase and thaumatin-like protein. Moreover, apart from inducing basic defense, Meiwa showed specially upregulated expression of several genes involved in the response to biotic stimulus, defense response, and cation binding as comparing with Newhall. And in Newhall, abundant photosynthesis-related genes were significantly down-regulated, which may be in order to ensure the basic defense. This study revealed different molecular responses to canker disease in Meiwa and Newhall, affording insight into the response to canker and providing valuable information for the identification of potential genes for engineering canker tolerance in the future.

Identification of Biomarkers for Defense Response to Plasmopara viticola in a Resistant Grape Variety

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Giulia Chitarrini

2017-09-01

Full Text Available Downy mildew (Plasmopara viticola is one of the most destructive diseases of the cultivated species Vitis vinifera. The use of resistant varieties, originally derived from backcrosses of North American Vitis spp., is a promising solution to reduce disease damage in the vineyards. To shed light on the type and the timing of pathogen-triggered resistance, this work aimed at discovering biomarkers for the defense response in the resistant variety Bianca, using leaf discs after inoculation with a suspension of P. viticola. We investigated primary and secondary metabolism at 12, 24, 48, and 96 h post-inoculation (hpi. We used methods of identification and quantification for lipids (LC-MS/MS, phenols (LC-MS/MS, primary compounds (GC-MS, and semi-quantification for volatile compounds (GC-MS. We were able to identify and quantify or semi-quantify 176 metabolites, among which 53 were modulated in response to pathogen infection. The earliest changes occurred in primary metabolism at 24–48 hpi and involved lipid compounds, specifically unsaturated fatty acid and ceramide; amino acids, in particular proline; and some acids and sugars. At 48 hpi, we also found changes in volatile compounds and accumulation of benzaldehyde, a promoter of salicylic acid-mediated defense. Secondary metabolism was strongly induced only at later stages. The classes of compounds that increased at 96 hpi included phenylpropanoids, flavonols, stilbenes, and stilbenoids. Among stilbenoids we found an accumulation of ampelopsin H + vaticanol C, pallidol, ampelopsin D + quadrangularin A, Z-miyabenol C, and α-viniferin in inoculated samples. Some of these compounds are known as phytoalexins, while others are novel biomarkers for the defense response in Bianca. This work highlighted some important aspects of the host response to P. viticola in a commercial variety under controlled conditions, providing biomarkers for a better understanding of the mechanism of plant defense and a

Immediate and persistent transcriptional correlates of long-term sensitization training at different CNS loci in Aplysia californica.

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Samantha Herdegen

Full Text Available Repeated noxious stimulation produces long-term sensitization of defensive withdrawal reflexes in Aplysia californica, a form of long-term memory that requires changes in both transcription and translation. Previous work has identified 10 transcripts which are rapidly up-regulated after long-term sensitization training in the pleural ganglia. Here we use quantitative PCR to begin examining how these transcriptional changes are expressed in different CNS loci related to defensive withdrawal reflexes at 1 and 24 hours after long-term sensitization training. Specifically, we sample from a the sensory wedge of the pleural ganglia, which exclusively contains the VC nociceptor cell bodies that help mediate input to defensive withdrawal circuits, b the remaining pleural ganglia, which contain withdrawal interneurons, and c the pedal ganglia, which contain many motor neurons. Results from the VC cluster show different temporal patterns of regulation: 1 rapid but transient up-regulation of Aplysia homologs of C/EBP, C/EBPγ, and CREB1, 2 delayed but sustained up-regulation of BiP, Tolloid/BMP-1, and sensorin, 3 rapid and sustained up-regulation of Egr, GlyT2, VPS36, and an uncharacterized protein (LOC101862095, and 4 an unexpected lack of regulation of Aplysia homologs of calmodulin (CaM and reductase-related protein (RRP. Changes in the remaining pleural ganglia mirror those found in the VC cluster at 1 hour but with an attenuated level of regulation. Because these samples had almost no expression of the VC-specific transcript sensorin, our data suggests that sensitization training likely induces transcriptional changes in either defensive withdrawal interneurons or neurons unrelated to defensive withdrawal. In the pedal ganglia, we observed only a rapid but transient increase in Egr expression, indicating that long-term sensitization training is likely to induce transcriptional changes in motor neurons but raising the possibility of different

Functional link between DNA damage responses and transcriptional regulation by ATM in response to a histone deacetylase inhibitor TSA.

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Lee, Jong-Soo

2007-09-01

Mutations in the ATM (ataxia-telangiectasia mutated) gene, which encodes a 370 kd protein with a kinase catalytic domain, predisposes people to cancers, and these mutations are also linked to ataxia-telangiectasia (A-T). The histone acetylaion/deacetylation- dependent chromatin remodeling can activate the ATM kinase-mediated DNA damage signal pathway (in an accompanying work, Lee, 2007). This has led us to study whether this modification can impinge on the ATM-mediated DNA damage response via transcriptional modulation in order to understand the function of ATM in the regulation of gene transcription. To identify the genes whose expression is regulated by ATM in response to histone deaceylase (HDAC) inhibition, we performed an analysis of oligonucleotide microarrays with using the appropriate cell lines, isogenic A-T (ATM(-)) and control (ATM(+)) cells, following treatment with a HDAC inhibitor TSA. Treatment with TSA reprograms the differential gene expression profile in response to HDAC inhibition in ATM(-) cells and ATM(+) cells. We analyzed the genes that are regulated by TSA in the ATM-dependent manner, and we classified these genes into different functional categories, including those involved in cell cycle/DNA replication, DNA repair, apoptosis, growth/differentiation, cell- cell adhesion, signal transduction, metabolism and transcription. We found that while some genes are regulated by TSA without regard to ATM, the patterns of gene regulation are differentially regulated in an ATM-dependent manner. Taken together, these finding indicate that ATM can regulate the transcription of genes that play critical roles in the molecular response to DNA damage, and this response is modulated through an altered HDAC inhibition-mediated gene expression.

Transcriptional profiling reveals the expression of novel genes in response to various stimuli in the human dermatophyte Trichophyton rubrum

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Aquino-Ferreira Roseli

2010-02-01

Full Text Available Abstract Background Cutaneous mycoses are common human infections among healthy and immunocompromised hosts, and the anthropophilic fungus Trichophyton rubrum is the most prevalent microorganism isolated from such clinical cases worldwide. The aim of this study was to determine the transcriptional profile of T. rubrum exposed to various stimuli in order to obtain insights into the responses of this pathogen to different environmental challenges. Therefore, we generated an expressed sequence tag (EST collection by constructing one cDNA library and nine suppression subtractive hybridization libraries. Results The 1388 unigenes identified in this study were functionally classified based on the Munich Information Center for Protein Sequences (MIPS categories. The identified proteins were involved in transcriptional regulation, cellular defense and stress, protein degradation, signaling, transport, and secretion, among other functions. Analysis of these unigenes revealed 575 T. rubrum sequences that had not been previously deposited in public databases. Conclusion In this study, we identified novel T. rubrum genes that will be useful for ORF prediction in genome sequencing and facilitating functional genome analysis. Annotation of these expressed genes revealed metabolic adaptations of T. rubrum to carbon sources, ambient pH shifts, and various antifungal drugs used in medical practice. Furthermore, challenging T. rubrum with cytotoxic drugs and ambient pH shifts extended our understanding of the molecular events possibly involved in the infectious process and resistance to antifungal drugs.

Changes in transcript expression patterns as a result of cryoprotectant treatment and liquid nitrogen exposure in Arabidopsis shoot tips.

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Gross, Briana L; Henk, Adam D; Bonnart, Remi; Volk, Gayle M

2017-03-01

Transcripts related to abiotic stress, oxidation, and wounding were differentially expressed in Arabidopsis shoot tips in response to cryoprotectant and liquid nitrogen treatment. Cryopreservation methods have been implemented in genebanks as a strategy to back-up plant genetic resource collections that are vegetatively propagated. Cryopreservation is frequently performed using vitrification methods, whereby shoot tips are treated with cryoprotectant solutions, such as Plant Vitrification Solution 2 (PVS2) or Plant Vitrification Solution 3 (PVS3); these solutions remove and/or replace freezable water within the meristem cells. We used the model system Arabidopsis thaliana to identify suites of transcripts that are up- or downregulated in response to PVS2 and PVS3 treatment and liquid nitrogen (LN) exposure. Our results suggest that there are many changes in transcript expression in shoot tips as a result of cryoprotection and that these changes exceed the number detected as a result of LN exposure. In total, 180 transcripts showed significant changes in expression level unique to treatment with either the cryoprotectant or cryopreservation followed by recovery. Of these 180 transcripts, 67 were related to stress, defense, wounding, lipid, carbohydrate, abscisic acid, oxidation, temperature (cold/heat), or osmoregulation. The responses of five transcripts were confirmed using qPCR methods. The transcripts responding to PVS2 + LN suggest an oxidative response to this treatment, whereas the PVS3 + LN treatment invoked a more general metabolic response. This work shows that the choice of cryoprotectant can have a major influence on the patterns of transcript expression, presumably due to the level and extent of stress experienced by the shoot tip. As a result, there may be divergent responses of study systems to PVS2 and PVS3 treatments.

Heat shock factor-1 modulates p53 activity in the transcriptional response to DNA damage

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Logan, Ian R.; McNeill, Hesta V.; Cook, Susan; Lu, Xiaohong; Meek, David W.; Fuller-Pace, Frances V.; Lunec, John; Robson, Craig N.

2009-01-01

Here we define an important role for heat shock factor 1 (HSF1) in the cellular response to genotoxic agents. We demonstrate for the first time that HSF1 can complex with nuclear p53 and that both proteins are co-operatively recruited to p53-responsive genes such as p21. Analysis of natural and synthetic cis elements demonstrates that HSF1 can enhance p53-mediated transcription, whilst depletion of HSF1 reduces the expression of p53-responsive transcripts. We find that HSF1 is required for optimal p21 expression and p53-mediated cell-cycle arrest in response to genotoxins while loss of HSF1 attenuates apoptosis in response to these agents. To explain these novel properties of HSF1 we show that HSF1 can complex with DNA damage kinases ATR and Chk1 to effect p53 phosphorylation in response to DNA damage. Our data reveal HSF1 as a key transcriptional regulator in response to genotoxic compounds widely used in the clinical setting, and suggest that HSF1 will contribute to the efficacy of these agents. PMID:19295133

Global Transcription Profiling Reveals Comprehensive Insights into Hypoxic Response in Arabidopsis1[w

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Liu, Fenglong; VanToai, Tara; Moy, Linda P.; Bock, Geoffrey; Linford, Lara D.; Quackenbush, John

2005-01-01

Plants have evolved adaptation mechanisms to sense oxygen deficiency in their environments and make coordinated physiological and structural adjustments to enhance their hypoxic tolerance. To gain insight into how plants respond to low-oxygen stress, gene expression profiling using whole-genome DNA amplicon microarrays was carried out at seven time points over 24 h, in wild-type and transgenic PSAG12:ipt Arabidopsis (Arabidopsis thaliana) plants under normoxic and hypoxic conditions. Transcript levels of genes involved in glycolysis and fermentation pathways, ethylene synthesis and perception, calcium signaling, nitrogen utilization, trehalose metabolism, and alkaloid synthesis were significantly altered in response to oxygen limitation. Analysis based on gene ontology assignments suggested a significant down-regulation of genes whose functions are associated with cell walls, nucleosome structures, water channels, and ion transporters and a significant up-regulation of genes involved in transcriptional regulation, protein kinase activity, and auxin responses under conditions of oxygen shortage. Promoter analysis on a cluster of up-regulated genes revealed a significant overrepresentation of the AtMYB2-binding motif (GT motif), a sugar response element-like motif, and a G-box-related sequence, and also identified several putative anaerobic response elements. Finally, quantitative real-time polymerase chain reactions using 29 selected genes independently verified the microarray results. This study represents one of the most comprehensive analyses conducted to date investigating hypoxia-responsive transcriptional networks in plants. PMID:15734912

Genome wide analysis of stress responsive WRKY transcription factors in Arabidopsis thaliana

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Shaiq Sultan

2016-04-01

Full Text Available WRKY transcription factors are a class of DNA-binding proteins that bind with a specific sequence C/TTGACT/C known as W-Box found in promoters of genes which are regulated by these WRKYs. From previous studies, 43 different stress responsive WRKY transcription factors in Arabidopsis thaliana, identified and then categorized in three groups viz., abiotic, biotic and both of these stresses. A comprehensive genome wide analysis including chromosomal localization, gene structure analysis, multiple sequence alignment, phylogenetic analysis and promoter analysis of these WRKY genes was carried out in this study to determine the functional homology in Arabidopsis. This analysis led to the classification of these WRKY family members into 3 major groups and subgroups and showed evolutionary relationship among these groups on the base of their functional WRKY domain, chromosomal localization and intron/exon structure. The proposed groups of these stress responsive WRKY genes and annotation based on their position on chromosomes can also be explored to determine their functional homology in other plant species in relation to different stresses. The result of the present study provides indispensable genomic information for the stress responsive WRKY transcription factors in Arabidopsis and will pave the way to explain the precise role of various AtWRKYs in plant growth and development under stressed conditions.

Dehydration Stress Contributes to the Enhancement of Plant Defense Response and Mite Performance on Barley

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M. E. Santamaria

2018-04-01

Full Text Available Under natural conditions, plants suffer different stresses simultaneously or in a sequential way. At present, the combined effect of biotic and abiotic stressors is one of the most important threats to crop production. Understanding how plants deal with the panoply of potential stresses affecting them is crucial to develop biotechnological tools to protect plants. As well as for drought stress, the economic importance of the spider mite on agriculture is expected to increase due to climate change. Barley is a host of the polyphagous spider mite Tetranychus urticae and drought produces important yield losses. To obtain insights on the combined effect of drought and mite stresses on the defensive response of this cereal, we have analyzed the transcriptomic responses of barley plants subjected to dehydration (water-deficit treatment, spider mite attack, or to the combined dehydration-spider mite stress. The expression patterns of mite-induced responsive genes included many jasmonic acid responsive genes and were quickly induced. In contrast, genes related to dehydration tolerance were later up-regulated. Besides, a higher up-regulation of mite-induced defenses was showed by the combined dehydration and mite treatment than by the individual mite stress. On the other hand, the performance of the mite in dehydration stressed and well-watered plants was tested. Despite the stronger defensive response in plants that suffer dehydration and mite stresses, the spider mite demonstrates a better performance under dehydration condition than in well-watered plants. These results highlight the complexity of the regulatory events leading to the response to a combination of stresses and emphasize the difficulties to predict their consequences on crop production.

Dehydration Stress Contributes to the Enhancement of Plant Defense Response and Mite Performance on Barley

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Santamaria, M. E.; Diaz, Isabel; Martinez, Manuel

2018-01-01

Under natural conditions, plants suffer different stresses simultaneously or in a sequential way. At present, the combined effect of biotic and abiotic stressors is one of the most important threats to crop production. Understanding how plants deal with the panoply of potential stresses affecting them is crucial to develop biotechnological tools to protect plants. As well as for drought stress, the economic importance of the spider mite on agriculture is expected to increase due to climate change. Barley is a host of the polyphagous spider mite Tetranychus urticae and drought produces important yield losses. To obtain insights on the combined effect of drought and mite stresses on the defensive response of this cereal, we have analyzed the transcriptomic responses of barley plants subjected to dehydration (water-deficit) treatment, spider mite attack, or to the combined dehydration-spider mite stress. The expression patterns of mite-induced responsive genes included many jasmonic acid responsive genes and were quickly induced. In contrast, genes related to dehydration tolerance were later up-regulated. Besides, a higher up-regulation of mite-induced defenses was showed by the combined dehydration and mite treatment than by the individual mite stress. On the other hand, the performance of the mite in dehydration stressed and well-watered plants was tested. Despite the stronger defensive response in plants that suffer dehydration and mite stresses, the spider mite demonstrates a better performance under dehydration condition than in well-watered plants. These results highlight the complexity of the regulatory events leading to the response to a combination of stresses and emphasize the difficulties to predict their consequences on crop production. PMID:29681917

Functional analysis of jasmonate-responsive transcription factors in Arabidopsis thaliana

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Zarei, Adel

2007-01-01

The aim of the studies described in this thesis was the functional analysis of JA-responsive transcription factors in Arabidopsis with an emphasis on the interaction with the promoters of their target genes. In short, the following new results were obtained. The promoter of the PDF1.2 gene contains

Temporal and spatial resolution of activated plant defense responses in leaves of Nicotiana benthamiana infected with Dickeya dadantii

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María Luisa ePérez-Bueno

2016-01-01

Full Text Available The necrotrophic bacteria Dickeya dadantii is the causal agent of soft-rot disease in a broad range of hosts. The model plant Nicotiana benthamiana, commonly used as experimental host for a very broad range of plant pathogens, is susceptible to infection by D. dadantii. The inoculation with D. dadantii at high dose seems to overcome the plant defense capacity, inducing maceration and death of the tissue, although restricted to the infiltrated area. By contrast, the output of the defense response to low dose inoculation is inhibition of maceration and limitation in the growth, or even eradication, of bacteria. Responses of tissue invaded by bacteria (neighbouring the infiltrated areas after 2-3 days post-inoculation included: i inhibition of photosynthesis in terms of photosystem II efficiency; ii activation of energy dissipation as non-photochemical quenching in photosystem II, which is related to the activation of plant defense mechanisms; and iii accumulation of secondary metabolites in cell walls of the epidermis (lignins and the apoplast of the mesophyll (phytoalexins. Infiltrated tissues showed an increase in the content of the main hormones regulating stress responses, including abscisic acid (ABA, jasmonic acid (JA and salicylic acid (SA. We propose a mechanism involving the three hormones by which N. benthamiana could activate an efficient defense response against D. dadantii.

The transcriptional regulatory network mediated by banana (Musa acuminata) dehydration-responsive element binding (MaDREB) transcription factors in fruit ripening.

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Kuang, Jian-Fei; Chen, Jian-Ye; Liu, Xun-Cheng; Han, Yan-Chao; Xiao, Yun-Yi; Shan, Wei; Tang, Yang; Wu, Ke-Qiang; He, Jun-Xian; Lu, Wang-Jin

2017-04-01

Fruit ripening is a complex, genetically programmed process involving the action of critical transcription factors (TFs). Despite the established significance of dehydration-responsive element binding (DREB) TFs in plant abiotic stress responses, the involvement of DREBs in fruit ripening is yet to be determined. Here, we identified four genes encoding ripening-regulated DREB TFs in banana (Musa acuminata), MaDREB1, MaDREB2, MaDREB3, and MaDREB4, and demonstrated that they play regulatory roles in fruit ripening. We showed that MaDREB1-MaDREB4 are nucleus-localized, induced by ethylene and encompass transcriptional activation activities. We performed a genome-wide chromatin immunoprecipitation and high-throughput sequencing (ChIP-Seq) experiment for MaDREB2 and identified 697 genomic regions as potential targets of MaDREB2. MaDREB2 binds to hundreds of loci with diverse functions and its binding sites are distributed in the promoter regions proximal to the transcriptional start site (TSS). Most of the MaDREB2-binding targets contain the conserved (A/G)CC(G/C)AC motif and MaDREB2 appears to directly regulate the expression of a number of genes involved in fruit ripening. In combination with transcriptome profiling (RNA sequencing) data, our results indicate that MaDREB2 may serve as both transcriptional activator and repressor during banana fruit ripening. In conclusion, our study suggests a hierarchical regulatory model of fruit ripening in banana and that the MaDREB TFs may act as transcriptional regulators in the regulatory network. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

When defense becomes dangerous – transcription factor Nrf2 and cancer

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Adam Krysztofiak

2015-01-01

Full Text Available The transcription factor Nrf2 controls the expression of genes encoding cytoprotective enzymes and proteins. Its activation is related to conformational changes in the inhibitory protein Keap1 and/or Nrf2 phosphorylation by upstream kinases. Activation of Nrf2 can lead to the induction of phase II enzymes responsible for the inactivation of potential carcinogens. This may constitute an important strategy of chemoprevention. Moreover, these enzymatic systems participating in the biotransformation of drugs can reduce their therapeutic effects, contributing to drug resistance. For this reason, a clear understanding of the role of Nrf2 is essential to assess the beneficial and adverse effects of its up-regulation, particularly in relation to the prevention and treatment of cancer. This article summarizes the current state of knowledge on the significance of Nrf2 in tumorigenesis.

Transcriptional responses of Arabidopsis thaliana plants to As (V stress

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Yuan Joshua S

2008-08-01

Full Text Available Abstract Background Arsenic is toxic to plants and a common environmental pollutant. There is a strong chemical similarity between arsenate [As (V] and phosphate (Pi. Whole genome oligonucleotide microarrays were employed to investigate the transcriptional responses of Arabidopsis thaliana plants to As (V stress. Results Antioxidant-related genes (i.e. coding for superoxide dismutases and peroxidases play prominent roles in response to arsenate. The microarray experiment revealed induction of chloroplast Cu/Zn superoxide dismutase (SOD (at2g28190, Cu/Zn SOD (at1g08830, as well as an SOD copper chaperone (at1g12520. On the other hand, Fe SODs were strongly repressed in response to As (V stress. Non-parametric rank product statistics were used to detect differentially expressed genes. Arsenate stress resulted in the repression of numerous genes known to be induced by phosphate starvation. These observations were confirmed with qRT-PCR and SOD activity assays. Conclusion Microarray data suggest that As (V induces genes involved in response to oxidative stress and represses transcription of genes induced by phosphate starvation. This study implicates As (V as a phosphate mimic in the cell by repressing genes normally induced when available phosphate is scarce. Most importantly, these data reveal that arsenate stress affects the expression of several genes with little or unknown biological functions, thereby providing new putative gene targets for future research.

Discriminative identification of transcriptional responses of promoters and enhancers after stimulus

KAUST Repository

Kleftogiannis, Dimitrios A.; Kalnis, Panos; Arner, Erik; Bajic, Vladimir B.

2016-01-01

factors and co-activators. A case study on data from MCF-7 cell-line reveals that PEDAL can identify successfully the transcription response subclasses of promoters and enhancers from two different stimulations. Moreover, we report subsets of input markers

Defense Responses to Mycotoxin-Producing Fungi Fusarium proliferatum, F. subglutinans, and Aspergillus flavus in Kernels of Susceptible and Resistant Maize Genotypes.

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Lanubile, Alessandra; Maschietto, Valentina; De Leonardis, Silvana; Battilani, Paola; Paciolla, Costantino; Marocco, Adriano

2015-05-01

Developing kernels of resistant and susceptible maize genotypes were inoculated with Fusarium proliferatum, F. subglutinans, and Aspergillus flavus. Selected defense systems were investigated using real-time reverse transcription-polymerase chain reaction to monitor the expression of pathogenesis-related (PR) genes (PR1, PR5, PRm3, PRm6) and genes protective from oxidative stress (peroxidase, catalase, superoxide dismutase and ascorbate peroxidase) at 72 h postinoculation. The study was also extended to the analysis of the ascorbate-glutathione cycle and catalase, superoxide dismutase, and cytosolic and wall peroxidases enzymes. Furthermore, the hydrogen peroxide and malondialdehyde contents were studied to evaluate the oxidation level. Higher gene expression and enzymatic activities were observed in uninoculated kernels of resistant line, conferring a major readiness to the pathogen attack. Moreover expression values of PR genes remained higher in the resistant line after inoculation, demonstrating a potentiated response to the pathogen invasions. In contrast, reactive oxygen species-scavenging genes were strongly induced in the susceptible line only after pathogen inoculation, although their enzymatic activity was higher in the resistant line. Our data provide an important basis for further investigation of defense gene functions in developing kernels in order to improve resistance to fungal pathogens. Maize genotypes with overexpressed resistance traits could be profitably utilized in breeding programs focused on resistance to pathogens and grain safety.

Cooperative binding of transcription factors promotes bimodal gene expression response.

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Pablo S Gutierrez

Full Text Available In the present work we extend and analyze the scope of our recently proposed stochastic model for transcriptional regulation, which considers an arbitrarily complex cis-regulatory system using only elementary reactions. Previously, we determined the role of cooperativity on the intrinsic fluctuations of gene expression for activating transcriptional switches, by means of master equation formalism and computer simulation. This model allowed us to distinguish between two cooperative binding mechanisms and, even though the mean expression levels were not affected differently by the acting mechanism, we showed that the associated fluctuations were different. In the present generalized model we include other regulatory functions in addition to those associated to an activator switch. Namely, we introduce repressive regulatory functions and two theoretical mechanisms that account for the biphasic response that some cis-regulatory systems show to the transcription factor concentration. We have also extended our previous master equation formalism in order to include protein production by stochastic translation of mRNA. Furthermore, we examine the graded/binary scenarios in the context of the interaction energy between transcription factors. In this sense, this is the first report to show that the cooperative binding of transcription factors to DNA promotes the "all-or-none" phenomenon observed in eukaryotic systems. In addition, we confirm that gene expression fluctuation levels associated with one of two cooperative binding mechanism never exceed the fluctuation levels of the other.

Plant defense response against Fusarium oxysporum and strategies to develop tolerant genotypes in banana.

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Swarupa, V; Ravishankar, K V; Rekha, A

2014-04-01

Soil-borne fungal pathogen, Fusarium oxysporum causes major economic losses by inducing necrosis and wilting symptoms in many crop plants. Management of fusarium wilt is achieved mainly by the use of chemical fungicides which affect the soil health and their efficiency is often limited by pathogenic variability. Hence understanding the nature of interaction between pathogen and host may help to select and improve better cultivars. Current research evidences highlight the role of oxidative burst and antioxidant enzymes indicating that ROS act as an important signaling molecule in banana defense response against Fusarium oxysporum f.sp. cubense. The role of jasmonic acid signaling in plant defense against necrotrophic pathogens is well recognized. But recent studies show that the role of salicylic acid is complex and ambiguous against necrotrophic pathogens like Fusarium oxysporum, leading to many intriguing questions about its relationship between other signaling compounds. In case of banana, a major challenge is to identify specific receptors for effector proteins like SIX proteins and also the components of various signal transduction pathways. Significant progress has been made to uncover the role of defense genes but is limited to only model plants such as Arabidopsis and tomato. Keeping this in view, we review the host response, pathogen diversity, current understanding of biochemical and molecular changes that occur during host and pathogen interaction. Developing resistant cultivars through mutation, breeding, transgenic and cisgenic approaches have been discussed. This would help us to understand host defenses against Fusarium oxysporum and to formulate strategies to develop tolerant cultivars.

Differential regulation of defense-related proteins in soybean during compatible and incompatible interactions between Phytophthora sojae and soybean by comparative proteomic analysis.

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Jing, Maofeng; Ma, Hongyu; Li, Haiyang; Guo, Baodian; Zhang, Xin; Ye, Wenwu; Wang, Haonan; Wang, Qiuxia; Wang, Yuanchao

2015-07-01

Few proteomic studies have focused on the plant- Phytophthora interactions, our study provides important information regarding the use of proteomic methods for investigation of the basic mechanisms of plant-Phytophthora interactions. Phytophthora sojae is a fast-spreading and devastating pathogen that is responsible for root and stem rot in soybean crops worldwide. To better understand the response of soybean seedlings to the stress of infection by virulent and avirulent pathogens at the proteomic level, proteins extracted from the hypocotyls of soybean reference cultivar Williams 82 infected by P. sojae P6497 (race 2) and P7076 (race 19), respectively, were analyzed by two-dimensional gel electrophoresis. 95 protein spots were differently expressed, with 83 being successfully identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and subjected to further analysis. Based on the majority of the 83 defense-responsive proteins, and defense-related pathway genes supplemented by a quantitative reverse transcription PCR assay, a defense-related network for soybean infected by virulent and avirulent pathogens was proposed. We found reactive oxygen species (ROS) burst, the expression levels of salicylic acid (SA) signal pathway and biosynthesis of isoflavones were significantly up-regulated in the resistant soybean. Our results imply that following the P. sojae infection, ROS and SA signal pathway in soybean play the major roles in defense against P. sojae. This research will facilitate further investigation of the molecular regulatory mechanism of the defense response in soybean following infection by P. sojae.

Analyzing the dose-dependence of the Saccharomyces cerevisiae global transcriptional response to methyl methanesulfonate and ionizing radiation.

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Benton, Michael G; Somasundaram, Swetha; Glasner, Jeremy D; Palecek, Sean P

2006-12-01

One of the most crucial tasks for a cell to ensure its long term survival is preserving the integrity of its genetic heritage via maintenance of DNA structure and sequence. While the DNA damage response in the yeast Saccharomyces cerevisiae, a model eukaryotic organism, has been extensively studied, much remains to be elucidated about how the organism senses and responds to different types and doses of DNA damage. We have measured the global transcriptional response of S. cerevisiae to multiple doses of two representative DNA damaging agents, methyl methanesulfonate (MMS) and gamma radiation. Hierarchical clustering of genes with a statistically significant change in transcription illustrated the differences in the cellular responses to MMS and gamma radiation. Overall, MMS produced a larger transcriptional response than gamma radiation, and many of the genes modulated in response to MMS are involved in protein and translational regulation. Several clusters of coregulated genes whose responses varied with DNA damaging agent dose were identified. Perhaps the most interesting cluster contained four genes exhibiting biphasic induction in response to MMS dose. All of the genes (DUN1, RNR2, RNR4, and HUG1) are involved in the Mec1p kinase pathway known to respond to MMS, presumably due to stalled DNA replication forks. The biphasic responses of these genes suggest that the pathway is induced at lower levels as MMS dose increases. The genes in this cluster with a threefold or greater transcriptional response to gamma radiation all showed an increased induction with increasing gamma radiation dosage. Analyzing genome-wide transcriptional changes to multiple doses of external stresses enabled the identification of cellular responses that are modulated by magnitude of the stress, providing insights into how a cell deals with genotoxicity.

Analyzing the dose-dependence of the Saccharomyces cerevisiae global transcriptional response to methyl methanesulfonate and ionizing radiation

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Glasner Jeremy D

2006-12-01

Full Text Available Abstract Background One of the most crucial tasks for a cell to ensure its long term survival is preserving the integrity of its genetic heritage via maintenance of DNA structure and sequence. While the DNA damage response in the yeast Saccharomyces cerevisiae, a model eukaryotic organism, has been extensively studied, much remains to be elucidated about how the organism senses and responds to different types and doses of DNA damage. We have measured the global transcriptional response of S. cerevisiae to multiple doses of two representative DNA damaging agents, methyl methanesulfonate (MMS and gamma radiation. Results Hierarchical clustering of genes with a statistically significant change in transcription illustrated the differences in the cellular responses to MMS and gamma radiation. Overall, MMS produced a larger transcriptional response than gamma radiation, and many of the genes modulated in response to MMS are involved in protein and translational regulation. Several clusters of coregulated genes whose responses varied with DNA damaging agent dose were identified. Perhaps the most interesting cluster contained four genes exhibiting biphasic induction in response to MMS dose. All of the genes (DUN1, RNR2, RNR4, and HUG1 are involved in the Mec1p kinase pathway known to respond to MMS, presumably due to stalled DNA replication forks. The biphasic responses of these genes suggest that the pathway is induced at lower levels as MMS dose increases. The genes in this cluster with a threefold or greater transcriptional response to gamma radiation all showed an increased induction with increasing gamma radiation dosage. Conclusion Analyzing genome-wide transcriptional changes to multiple doses of external stresses enabled the identification of cellular responses that are modulated by magnitude of the stress, providing insights into how a cell deals with genotoxicity.

Myonuclear transcription is responsive to mechanical load and DNA content but uncoupled from cell size during hypertrophy.

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Kirby, Tyler J; Patel, Rooshil M; McClintock, Timothy S; Dupont-Versteegden, Esther E; Peterson, Charlotte A; McCarthy, John J

2016-03-01

Myofibers increase size and DNA content in response to a hypertrophic stimulus, thus providing a physiological model with which to study how these factors affect global transcription. Using 5-ethynyl uridine (EU) to metabolically label nascent RNA, we measured a sevenfold increase in myofiber transcription during early hypertrophy before a change in cell size and DNA content. The typical increase in myofiber DNA content observed at the later stage of hypertrophy was associated with a significant decrease in the percentage of EU-positive myonuclei; however, when DNA content was held constant by preventing myonuclear accretion via satellite cell depletion, both the number of transcriptionally active myonuclei and the amount of RNA generated by each myonucleus increased. During late hypertrophy, transcription did not scale with cell size, as smaller myofibers (transcriptional activity. Finally, transcription was primarily responsible for changes in the expression of genes known to regulate myofiber size. These findings show that resident myonuclei possess a significant reserve capacity to up-regulate transcription during hypertrophy and that myofiber transcription is responsive to DNA content but uncoupled from cell size during hypertrophy. © 2016 Kirby et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Changes in defensive functioning in a case of avoidant personality disorder.

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Presniak, Michelle D; Olson, Trevor R; Porcerelli, John H; Dauphin, V Barry

2010-03-01

This case study is based upon data from a male patient with Avoidant Personality Disorder who was in psychoanalytic treatment for 5 years. Defense mechanism use was assessed by 3 coders using the Defense Mechanisms Rating Scales. Session transcripts from intake, each year of therapy, and 1-year follow-up were used for the ratings. Over the course of psychoanalysis and follow-up, the patient's Overall Defensive Functioning and High-Adaptive defense level use increased and his use of the Disavowal defense level and Fantasy decreased. The pattern of change throughout treatment was also assessed. The patient's Overall Defensive Functioning decreased initially, followed by an increase through year 4. Overall Defensive Functioning decreased again prior to termination before increasing to its highest level at follow-up. The results demonstrated changes consistent with hypotheses and theory, including overall improvement in defensive functioning, an initial regression of defensive functioning, decline in functioning immediately prior to termination, and continued improvement posttermination. This pattern of defense change highlights the importance of assessing defenses in treatment research. PsycINFO Database Record (c) 2010 APA, all rights reserved

Simultaneous transcriptome analysis of Colletotrichum gloeosporioides and tomato fruit pathosystem reveals novel fungal pathogenicity and fruit defense strategies.

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Alkan, Noam; Friedlander, Gilgi; Ment, Dana; Prusky, Dov; Fluhr, Robert

2015-01-01

The fungus Colletotrichum gloeosporioides breaches the fruit cuticle but remains quiescent until fruit ripening signals a switch to necrotrophy, culminating in devastating anthracnose disease. There is a need to understand the distinct fungal arms strategy and the simultaneous fruit response. Transcriptome analysis of fungal-fruit interactions was carried out concurrently in the appressoria, quiescent and necrotrophic stages. Conidia germinating on unripe fruit cuticle showed stage-specific transcription that was accompanied by massive fruit defense responses. The subsequent quiescent stage showed the development of dendritic-like structures and swollen hyphae within the fruit epidermis. The quiescent fungal transcriptome was characterized by activation of chromatin remodeling genes and unsuspected environmental alkalization. Fruit response was portrayed by continued highly integrated massive up-regulation of defense genes. During cuticle infection of green or ripe fruit, fungi recapitulate the same developmental stages but with differing quiescent time spans. The necrotrophic stage showed a dramatic shift in fungal metabolism and up-regulation of pathogenicity factors. Fruit response to necrotrophy showed activation of the salicylic acid pathway, climaxing in cell death. Transcriptome analysis of C. gloeosporioides infection of fruit reveals its distinct stage-specific lifestyle and the concurrent changing fruit response, deepening our perception of the unfolding fungal-fruit arms and defenses race. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Trichoderma-Plant Root Colonization: Escaping Early Plant Defense Responses and Activation of the Antioxidant Machinery for Saline Stress Tolerance

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Brotman, Yariv; Landau, Udi; Cuadros-Inostroza, Álvaro; Takayuki, Tohge; Fernie, Alisdair R.; Chet, Ilan; Viterbo, Ada; Willmitzer, Lothar

2013-01-01

Trichoderma spp. are versatile opportunistic plant symbionts which can colonize the apoplast of plant roots. Microarrays analysis of Arabidopsis thaliana roots inoculated with Trichoderma asperelloides T203, coupled with qPCR analysis of 137 stress responsive genes and transcription factors, revealed wide gene transcript reprogramming, proceeded by a transient repression of the plant immune responses supposedly to allow root colonization. Enhancement in the expression of WRKY18 and WRKY40, which stimulate JA-signaling via suppression of JAZ repressors and negatively regulate the expression of the defense genes FMO1, PAD3 and CYP71A13, was detected in Arabidopsis roots upon Trichoderma colonization. Reduced root colonization was observed in the wrky18/wrky40 double mutant line, while partial phenotypic complementation was achieved by over-expressing WRKY40 in the wrky18 wrky40 background. On the other hand increased colonization rate was found in roots of the FMO1 knockout mutant. Trichoderma spp. stimulate plant growth and resistance to a wide range of adverse environmental conditions. Arabidopsis and cucumber (Cucumis sativus L.) plants treated with Trichoderma prior to salt stress imposition show significantly improved seed germination. In addition, Trichoderma treatment affects the expression of several genes related to osmo-protection and general oxidative stress in roots of both plants. The MDAR gene coding for monodehydroascorbate reductase is significantly up-regulated and, accordingly, the pool of reduced ascorbic acid was found to be increased in Trichoderma treated plants. 1-Aminocyclopropane-1-carboxylate (ACC)-deaminase silenced Trichoderma mutants were less effective in providing tolerance to salt stress, suggesting that Trichoderma, similarly to ACC deaminase producing bacteria, can ameliorate plant growth under conditions of abiotic stress, by lowering ameliorating increases in ethylene levels as well as promoting an elevated antioxidative capacity

Transcriptional Regulatory Network Analysis of MYB Transcription Factor Family Genes in Rice

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Shuchi eSmita

2015-12-01

Full Text Available MYB transcription factor (TF is one of the largest TF families and regulates defense responses to various stresses, hormone signaling as well as many metabolic and developmental processes in plants. Understanding these regulatory hierarchies of gene expression networks in response to developmental and environmental cues is a major challenge due to the complex interactions between the genetic elements. Correlation analyses are useful to unravel co-regulated gene pairs governing biological process as well as identification of new candidate hub genes in response to these complex processes. High throughput expression profiling data are highly useful for construction of co-expression networks. In the present study, we utilized transcriptome data for comprehensive regulatory network studies of MYB TFs by top down and guide gene approaches. More than 50% of OsMYBs were strongly correlated under fifty experimental conditions with 51 hub genes via top down approach. Further, clusters were identified using Markov Clustering (MCL. To maximize the clustering performance, parameter evaluation of the MCL inflation score (I was performed in terms of enriched GO categories by measuring F-score. Comparison of co-expressed cluster and clads analyzed from phylogenetic analysis signifies their evolutionarily conserved co-regulatory role. We utilized compendium of known interaction and biological role with Gene Ontology enrichment analysis to hypothesize function of coexpressed OsMYBs. In the other part, the transcriptional regulatory network analysis by guide gene approach revealed 40 putative targets of 26 OsMYB TF hubs with high correlation value utilizing 815 microarray data. The putative targets with MYB-binding cis-elements enrichment in their promoter region, functional co-occurrence as well as nuclear localization supports our finding. Specially, enrichment of MYB binding regions involved in drought-inducibility implying their regulatory role in drought

A systems biology perspective on the role of WRKY transcription factors in drought responses in plants.

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Tripathi, Prateek; Rabara, Roel C; Rushton, Paul J

2014-02-01

Drought is one of the major challenges affecting crop productivity and yield. However, water stress responses are notoriously multigenic and quantitative with strong environmental effects on phenotypes. It is also clear that water stress often does not occur alone under field conditions but rather in conjunction with other abiotic stresses such as high temperature and high light intensities. A multidisciplinary approach with successful integration of a whole range of -omics technologies will not only define the system, but also provide new gene targets for both transgenic approaches and marker-assisted selection. Transcription factors are major players in water stress signaling and some constitute major hubs in the signaling webs. The main transcription factors in this network include MYB, bHLH, bZIP, ERF, NAC, and WRKY transcription factors. The role of WRKY transcription factors in abiotic stress signaling networks is just becoming apparent and systems biology approaches are starting to define their places in the signaling network. Using systems biology approaches, there are now many transcriptomic analyses and promoter analyses that concern WRKY transcription factors. In addition, reports on nuclear proteomics have identified WRKY proteins that are up-regulated at the protein level by water stress. Interactomics has started to identify different classes of WRKY-interacting proteins. What are often lacking are connections between metabolomics, WRKY transcription factors, promoters, biosynthetic pathways, fluxes and downstream responses. As more levels of the system are characterized, a more detailed understanding of the roles of WRKY transcription factors in drought responses in crops will be obtained.

SUMO-, MAPK- and resistance protein-signaling converge at transcription complexes that regulate plant innate immunity

NARCIS (Netherlands)

Burg, van den H.A.; Takken, F.L.W.

2010-01-01

Upon pathogen perception plant innate immune receptors activate various signaling pathways that trigger host defenses. PAMP-triggered defense signaling requires mitogen-activated protein kinase (MAPK) pathways, which modulate the activity of transcription factors through phosphorylation. Here, we

SUMO-, MAPK-, and resistance protein-signaling converge at transcription complexes that regulate plant innate immunity

NARCIS (Netherlands)

van den Burg, H.A.; Takken, F.L.W.

2010-01-01

Upon pathogen perception plant innate immune receptors activate various signaling pathways that trigger host defenses. PAMP-triggered defense signaling requires mitogen-activated protein kinase (MAPK) pathways, which modulate the activity of transcription factors through phosphorylation. Here, we

Comparative transcriptome profiling of a resistant vs. susceptible tomato (Solanum lycopersicum cultivar in response to infection by tomato yellow leaf curl virus.

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Tianzi Chen

Full Text Available Tomato yellow leaf curl virus (TYLCV threatens tomato production worldwide by causing leaf yellowing, leaf curling, plant stunting and flower abscission. The current understanding of the host plant defense response to this virus is very limited. Using whole transcriptome sequencing, we analyzed the differential gene expression in response to TYLCV infection in the TYLCV-resistant tomato breeding line CLN2777A (R and TYLCV-susceptible tomato breeding line TMXA48-4-0 (S. The mixed inoculated samples from 3, 5 and 7 day post inoculation (dpi were compared to non-inoculated samples at 0 dpi. Of the total of 34831 mapped transcripts, 209 and 809 genes were differentially expressed in the R and S tomato line, respectively. The proportion of up-regulated differentially expressed genes (DEGs in the R tomato line (58.37% was higher than that in the S line (9.17%. Gene ontology (GO analyses revealed that similar GO terms existed in both DEGs of R and S lines; however, some sets of defense related genes and their expression levels were not similar between the two tomato lines. Genes encoding for WRKY transcriptional factors, R genes, protein kinases and receptor (-like kinases which were identified as down-regulated DEGs in the S line were up-regulated or not differentially expressed in the R line. The up-regulated DEGs in the R tomato line revealed the defense response of tomato to TYLCV infection was characterized by the induction and regulation of a series of genes involved in cell wall reorganization, transcriptional regulation, defense response, ubiquitination, metabolite synthesis and so on. The present study provides insights into various reactions underlining the successful establishment of resistance to TYLCV in the R tomato line, and helps in the identification of important defense-related genes in tomato for TYLCV disease management.

ATL9, a RING zinc finger protein with E3 ubiquitin ligase activity implicated in chitin- and NADPH oxidase-mediated defense responses.

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Marta Berrocal-Lobo

2010-12-01

Full Text Available Pathogen associated molecular patterns (PAMPs are signals detected by plants that activate basal defenses. One of these PAMPs is chitin, a carbohydrate present in the cell walls of fungi and in insect exoskeletons. Previous work has shown that chitin treatment of Arabidopsis thaliana induced defense-related genes in the absence of a pathogen and that the response was independent of the salicylic acid (SA, jasmonic acid (JA and ethylene (ET signaling pathways. One of these genes is ATL9 ( = ATL2G, which encodes a RING zinc-finger like protein. In the current work we demonstrate that ATL9 has E3 ubiquitin ligase activity and is localized to the endoplasmic reticulum. The expression pattern of ATL9 is positively correlated with basal defense responses against Golovinomyces cichoracearum, a biotrophic fungal pathogen. The basal levels of expression and the induction of ATL9 by chitin, in wild type plants, depends on the activity of NADPH oxidases suggesting that chitin-mediated defense response is NADPH oxidase dependent. Although ATL9 expression is not induced by treatment with known defense hormones (SA, JA or ET, full expression in response to chitin is compromised slightly in mutants where ET- or SA-dependent signaling is suppressed. Microarray analysis of the atl9 mutant revealed candidate genes that appear to act downstream of ATL9 in chitin-mediated defenses. These results hint at the complexity of chitin-mediated signaling and the potential interplay between elicitor-mediated signaling, signaling via known defense pathways and the oxidative burst.

TMV-Cg Coat Protein stabilizes DELLA proteins and in turn negatively modulates salicylic acid-mediated defense pathway during Arabidopsis thaliana viral infection.

Science.gov (United States)

Rodriguez, Maria Cecilia; Conti, Gabriela; Zavallo, Diego; Manacorda, Carlos Augusto; Asurmendi, Sebastian

2014-08-03

Plant viral infections disturb defense regulatory networks during tissue invasion. Emerging evidence demonstrates that a significant proportion of these alterations are mediated by hormone imbalances. Although the DELLA proteins have been reported to be central players in hormone cross-talk, their role in the modulation of hormone signaling during virus infections remains unknown. This work revealed that TMV-Cg coat protein (CgCP) suppresses the salicylic acid (SA) signaling pathway without altering defense hormone SA or jasmonic acid (JA) levels in Arabidopsis thaliana. Furthermore, it was observed that the expression of CgCP reduces plant growth and delays the timing of floral transition. Quantitative RT-qPCR analysis of DELLA target genes showed that CgCP alters relative expression of several target genes, indicating that the DELLA proteins mediate transcriptional changes produced by CgCP expression. Analyses by fluorescence confocal microscopy showed that CgCP stabilizes DELLA proteins accumulation in the presence of gibberellic acid (GA) and that the DELLA proteins are also stabilized during TMV-Cg virus infections. Moreover, DELLA proteins negatively modulated defense transcript profiles during TMV-Cg infection. As a result, TMV-Cg accumulation was significantly reduced in the quadruple-DELLA mutant Arabidopsis plants compared to wild type plants. Taken together, these results demonstrate that CgCP negatively regulates the salicylic acid-mediated defense pathway by stabilizing the DELLA proteins during Arabidopsis thaliana viral infection, suggesting that CgCP alters the stability of DELLAs as a mechanism of negative modulation of antiviral defense responses.

A damage-responsive DNA binding protein regulates transcription of the yeast DNA repair gene PHR1

International Nuclear Information System (INIS)

Sebastian, J.; Sancar, G.B.

1991-01-01

The PHR1 gene of Saccharomyces cerevisiae encodes the DNA repair enzyme photolyase. Transcription of PHR1 increases in response to treatment of cells with 254-nm radiation and chemical agents that damage DNA. The authors here the identification of a damage-responsive DNA binding protein, termed photolyase regulatory protein (PRP), and its cognate binding site, termed the PHR1 transcription after DNA damage. PRP activity, monitored by electrophoretic-mobility-shift assay, was detected in cells during normal growth but disappeared within 30 min after irradiation. Copper-phenanthroline footprinting of PRP-DNA complexes revealed that PRP protects a 39-base-pair region of PHR1 5' flanking sequence beginning 40 base pairs upstream from the coding sequence. Thus these observations establish that PRP is a damage-responsive repressor of PHR1 transcription

Transcriptional, proteomic, and metabolic responses to lithium in galactose-grown yeast cells

DEFF Research Database (Denmark)

Bro, Christoffer; Regenberg, Birgitte; Lagniel, G.

2003-01-01

Lithium is highly toxic to yeast when grown in galactose medium mainly because phosphoglucomutase, a key enzyme of galactose metabolism, is inhibited. We studied the global protein and gene expression profiles of Saccharomyces cerevisiae grown in galactose in different time intervals after addition...... of lithium. These results were related to physiological studies where both secreted and intracellular metabolites were determined. Microarray analysis showed that 664 open reading frames were down-regulated and 725 up-regulated in response to addition of lithium. Genes involved in transcription, translation......-regulated proteins were also identified as being changed on the mRNA level. Functional clusters obtained from proteome data were coincident with transcriptional clusters. Physiological studies showed that acetate, glycerol, and glycogen accumulate in response to lithium, as reflected in expression data, whereas...

Aedes aegypti uses RNA interference in defense against Sindbis virus infection.

Science.gov (United States)

Campbell, Corey L; Keene, Kimberly M; Brackney, Douglas E; Olson, Ken E; Blair, Carol D; Wilusz, Jeffrey; Foy, Brian D

2008-03-17

RNA interference (RNAi) is an important anti-viral defense mechanism. The Aedes aegypti genome encodes RNAi component orthologs, however, most populations of this mosquito are readily infected by, and subsequently transmit flaviviruses and alphaviruses. The goal of this study was to use Ae. aegypti as a model system to determine how the mosquito's anti-viral RNAi pathway interacts with recombinant Sindbis virus (SINV; family Togaviridae, genus Alphavirus). SINV (TR339-eGFP) (+) strand RNA, infectious virus titers and infection rates transiently increased in mosquitoes following dsRNA injection to cognate Ago2, Dcr2, or TSN mRNAs. Detection of SINV RNA-derived small RNAs at 2 and 7 days post-infection in non-silenced mosquitoes provided important confirmation of RNAi pathway activity. Two different recombinant SINV viruses (MRE16-eGFP and TR339-eGFP) with significant differences in infection kinetics were used to delineate vector/virus interactions in the midgut. We show virus-dependent effects on RNAi component transcript and protein levels during infection. Monitoring midgut Ago2, Dcr2, and TSN transcript levels during infection revealed that only TSN transcripts were significantly increased in midguts over blood-fed controls. Ago2 protein levels were depleted immediately following a non-infectious bloodmeal and varied during SINV infection in a virus-dependent manner. We show that silencing RNAi components in Ae. aegypti results in transient increases in SINV replication. Furthermore, Ae. aegypti RNAi is active during SINV infection as indicated by production of virus-specific siRNAs. Lastly, the RNAi response varies in a virus-dependent manner. These data define important features of RNAi anti-viral defense in Ae. aegypti.

Proteomic analysis of the defense response of wheat to the powdery mildew fungus, Blumeria graminis f. sp. tritici.

Science.gov (United States)

Mandal, Md Siddikun Nabi; Fu, Ying; Zhang, Sheng; Ji, Wanquan

2014-12-01

Powdery mildew of wheat is caused by Blumeria graminis f. sp. tritici (Bgt). Although many wheat cultivars resistant to this disease have been developed, little is known about their resistance mechanisms. The aim of this study was to identify proteins showing changes in abundance during the resistance response of the wheat line N0308 infected by Bgt. In two-dimensional electrophoresis analyses, 45 spots on the gels showed significant changes in abundance at 24, 48, and 72 h after inoculation, as compared to non-inoculated plants. Of these 45 proteins, 44 were identified by mass spectrometry analysis using the NCBInr database of Triticum aestivum (26 spots) and closely related species in the Triticum genus (18 spots). These proteins were associated with the defense response, photosynthesis, metabolism, and other cellular processes in wheat. Most of the up-regulated proteins were identified as stress- and defense-related proteins. In particular, the product of a specific powdery mildew resistance gene (Pm3b and its homolog) and some other defense- and pathogenesis-related proteins were overexpressed. The resistance gene product mediates the immune response and coordinates other cellular processes during the resistance response to Bgt.

Jasmonate-responsive transcription factors regulating plant secondary metabolism.

Science.gov (United States)

Zhou, Meiliang; Memelink, Johan

2016-01-01

Plants produce a large variety of secondary metabolites including alkaloids, glucosinolates, terpenoids and phenylpropanoids. These compounds play key roles in plant-environment interactions and many of them have pharmacological activity in humans. Jasmonates (JAs) are plant hormones which induce biosynthesis of many secondary metabolites. JAs-responsive transcription factors (TFs) that regulate the JAs-induced accumulation of secondary metabolites belong to different families including AP2/ERF, bHLH, MYB and WRKY. Here, we give an overview of the types and functions of TFs that have been identified in JAs-induced secondary metabolite biosynthesis, and highlight their similarities and differences in regulating various biosynthetic pathways. We review major recent developments regarding JAs-responsive TFs mediating secondary metabolite biosynthesis, and provide suggestions for further studies. Copyright © 2016 Elsevier Inc. All rights reserved.

Transcriptional Response of Rhodococcus aetherivorans I24 to Polychlorinated Biphenyl-Contaminated Sediments

KAUST Repository

Puglisi, Edoardo; Cahill, Matt J.; Lessard, Philip A.; Capri, Ettore; Sinskey, Anthony John; Archer, John A.C.; Boccazzi, Paolo

2010-01-01

the natural environment. Our results indicate that the transcriptional response of R. aetherivorans I24 to PCBs, in both medium and sediment, is primarily directed towards reducing oxidative stress, rather than catabolism. © 2010 Springer Science

Interacting signal pathways control defense gene expression in Arabidopsis in response to cell wall-degrading enzymes from Erwinia carotovora.

Science.gov (United States)

Norman-Setterblad, C; Vidal, S; Palva, E T

2000-04-01

We have characterized the role of salicylic acid (SA)-independent defense signaling in Arabidopsis thaliana in response to the plant pathogen Erwinia carotovora subsp. carotovora. Use of pathway-specific target genes as well as signal mutants allowed us to elucidate the role and interactions of ethylene, jasmonic acid (JA), and SA signal pathways in this response. Gene expression studies suggest a central role for both ethylene and JA pathways in the regulation of defense gene expression triggered by the pathogen or by plant cell wall-degrading enzymes (CF) secreted by the pathogen. Our results suggest that ethylene and JA act in concert in this regulation. In addition, CF triggers another, strictly JA-mediated response inhibited by ethylene and SA. SA does not appear to have a major role in activating defense gene expression in response to CF. However, SA may have a dual role in controlling CF-induced gene expression, by enhancing the expression of genes synergistically induced by ethylene and JA and repressing genes induced by JA alone.

Genome wide transcriptional response of Saccharomyces cerevisiae to stress-induced perturbations

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Hilal eTaymaz-Nikerel

2016-02-01

Full Text Available Cells respond to environmental and/or genetic perturbations in order to survive and proliferate. Characterization of the changes after various stimuli at different -omics levels is crucial to comprehend the adaptation of cells to changing conditions. Genome wide quantification and analysis of transcript levels, the genes affected by perturbations, extends our understanding of cellular metabolism by pointing out the mechanisms that play role in sensing the stress caused by those perturbations and related signaling pathways, and in this way guides us to achieve endeavors such as rational engineering of cells or interpretation of disease mechanisms. Saccharomyces cerevisiae as a model system has been studied in response to different perturbations and corresponding transcriptional profiles were followed either statically or/and dynamically, short- and long- term. This review focuses on response of yeast cells to diverse stress inducing perturbations including nutritional changes, ionic stress, salt stress, oxidative stress, osmotic shock, as well as to genetic interventions such as deletion and over-expression of genes. It is aimed to conclude on common regulatory phenomena that allow yeast to organize its transcriptomic response after any perturbation under different external conditions.

Transcriptome analysis reveals regulatory networks underlying differential susceptibility to Botrytis cinerea in response to nitrogen availability in Solanum lycopersicum.

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Andrea eVega

2015-11-01

Full Text Available Nitrogen (N is one of the main limiting nutrients for plant growth and crop yield. It is well documented that changes in nitrate availability, the main N source found in agricultural soils, influences a myriad of developmental programs and processes including the plant defense response. Indeed, many agronomical reports indicate that the plant N nutritional status influences their ability to respond effectively when challenged by different pathogens. However, the molecular mechanisms involved in N-modulation of plant susceptibility to pathogens are poorly characterized. In this work, we show that Solanum lycopersicum defense response to the necrotrophic fungus Botrytis cinerea is affected by plant N availability, with higher susceptibility in nitrate-limiting conditions. Global gene expression responses of tomato against B. cinerea under contrasting nitrate conditions reveals that plant primary metabolism is affected by the fungal infection regardless of N regimes. This result suggests that differential susceptibility to pathogen attack under contrasting N conditions is not only explained by a metabolic alteration. We used a systems biology approach to identify the transcriptional regulatory network implicated in plant response to the fungus infection under contrasting nitrate conditions. Interestingly, hub genes in this network are known key transcription factors involved in ethylene and jasmonic acid signaling. This result positions these hormones as key integrators of nitrate and defense against B. cinerea in tomato plants. Our results provide insights into potential crosstalk mechanisms between necrotrophic defense response and N status in plants.

Methyl Jasmonate-Elicited Transcriptional Responses and Pentacyclic Triterpene Biosynthesis in Sweet Basil1[C][W

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Misra, Rajesh Chandra; Maiti, Protiti; Chanotiya, Chandan Singh; Shanker, Karuna; Ghosh, Sumit

2014-01-01

Sweet basil (Ocimum basilicum) is well known for its diverse pharmacological properties and has been widely used in traditional medicine for the treatment of various ailments. Although a variety of secondary metabolites with potent biological activities are identified, our understanding of the biosynthetic pathways that produce them has remained largely incomplete. We studied transcriptional changes in sweet basil after methyl jasmonate (MeJA) treatment, which is considered an elicitor of secondary metabolites, and identified 388 candidate MeJA-responsive unique transcripts. Transcript analysis suggests that in addition to controlling its own biosynthesis and stress responses, MeJA up-regulates transcripts of the various secondary metabolic pathways, including terpenoids and phenylpropanoids/flavonoids. Furthermore, combined transcript and metabolite analysis revealed MeJA-induced biosynthesis of the medicinally important ursane-type and oleanane-type pentacyclic triterpenes. Two MeJA-responsive oxidosqualene cyclases (ObAS1 and ObAS2) that encode for 761- and 765-amino acid proteins, respectively, were identified and characterized. Functional expressions of ObAS1 and ObAS2 in Saccharomyces cerevisiae led to the production of β-amyrin and α-amyrin, the direct precursors of oleanane-type and ursane-type pentacyclic triterpenes, respectively. ObAS1 was identified as a β-amyrin synthase, whereas ObAS2 was a mixed amyrin synthase that produced both α-amyrin and β-amyrin but had a product preference for α-amyrin. Moreover, transcript and metabolite analysis shed light on the spatiotemporal regulation of pentacyclic triterpene biosynthesis in sweet basil. Taken together, these results will be helpful in elucidating the secondary metabolic pathways of sweet basil and developing metabolic engineering strategies for enhanced production of pentacyclic triterpenes. PMID:24367017

Integrative modeling of transcriptional regulation in response to antirheumatic therapy

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Thiesen Hans-Juergen

2009-08-01

Full Text Available Abstract Background The investigation of gene regulatory networks is an important issue in molecular systems biology and significant progress has been made by combining different types of biological data. The purpose of this study was to characterize the transcriptional program induced by etanercept therapy in patients with rheumatoid arthritis (RA. Etanercept is known to reduce disease symptoms and progression in RA, but the underlying molecular mechanisms have not been fully elucidated. Results Using a DNA microarray dataset providing genome-wide expression profiles of 19 RA patients within the first week of therapy we identified significant transcriptional changes in 83 genes. Most of these genes are known to control the human body's immune response. A novel algorithm called TILAR was then applied to construct a linear network model of the genes' regulatory interactions. The inference method derives a model from the data based on the Least Angle Regression while incorporating DNA-binding site information. As a result we obtained a scale-free network that exhibits a self-regulating and highly parallel architecture, and reflects the pleiotropic immunological role of the therapeutic target TNF-alpha. Moreover, we could show that our integrative modeling strategy performs much better than algorithms using gene expression data alone. Conclusion We present TILAR, a method to deduce gene regulatory interactions from gene expression data by integrating information on transcription factor binding sites. The inferred network uncovers gene regulatory effects in response to etanercept and thus provides useful hypotheses about the drug's mechanisms of action.

Bodily ownership modulation in defensive responses: physiological evidence in brain-damaged patients with pathological embodiment of other’s body parts

Science.gov (United States)

Fossataro, C.; Gindri, P.; Mezzanato, T.; Pia, L.; Garbarini, F.

2016-01-01

Do conscious beliefs about the body affect defensive mechanisms within the body? To answer this question we took advantage from a monothematic delusion of bodily ownership, in which brain-damaged patients misidentify alien limbs as their own. We investigated whether the delusional belief that an alien hand is their own hand modulates a subcortical defensive response, such as the hand-blink reflex. The blink, dramatically increases when the threated hand is inside the defensive peripersonal-space of the face. In our between-subjects design, including patients and controls, the threat was brought near the face either by the own hand or by another person’s hand. Our results show an ownership-dependent modulation of the defensive response. In controls, as well as in the patients’ intact-side, the response enhancement is significantly greater when the threat was brought near the face by the own than by the alien hand. Crucially, in the patients’ affected-side (where the pathological embodiment occurs), the alien (embodied) hand elicited a response enhancement comparable to that found when the threat is brought near the face by the real hand. These findings suggest the existence of a mutual interaction between our conscious beliefs about the body and the physiological mechanisms within the body. PMID:27292285

CRISPR transcript processing: a mechanism for generating a large number of small interfering RNAs

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Djordjevic Marko

2012-07-01

Full Text Available Abstract Background CRISPR/Cas (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated sequences is a recently discovered prokaryotic defense system against foreign DNA, including viruses and plasmids. CRISPR cassette is transcribed as a continuous transcript (pre-crRNA, which is processed by Cas proteins into small RNA molecules (crRNAs that are responsible for defense against invading viruses. Experiments in E. coli report that overexpression of cas genes generates a large number of crRNAs, from only few pre-crRNAs. Results We here develop a minimal model of CRISPR processing, which we parameterize based on available experimental data. From the model, we show that the system can generate a large amount of crRNAs, based on only a small decrease in the amount of pre-crRNAs. The relationship between the decrease of pre-crRNAs and the increase of crRNAs corresponds to strong linear amplification. Interestingly, this strong amplification crucially depends on fast non-specific degradation of pre-crRNA by an unidentified nuclease. We show that overexpression of cas genes above a certain level does not result in further increase of crRNA, but that this saturation can be relieved if the rate of CRISPR transcription is increased. We furthermore show that a small increase of CRISPR transcription rate can substantially decrease the extent of cas gene activation necessary to achieve a desired amount of crRNA. Conclusions The simple mathematical model developed here is able to explain existing experimental observations on CRISPR transcript processing in Escherichia coli. The model shows that a competition between specific pre-crRNA processing and non-specific degradation determines the steady-state levels of crRNA and is responsible for strong linear amplification of crRNAs when cas genes are overexpressed. The model further shows how disappearance of only a few pre-crRNA molecules normally present in the cell can lead to a large (two

Transcriptional regulatory network triggered by oxidative signals configures the early response mechanisms of japonica rice to chilling stress

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Wijaya Edward

2010-01-01

Full Text Available Abstract Background The transcriptional regulatory network involved in low temperature response leading to acclimation has been established in Arabidopsis. In japonica rice, which can only withstand transient exposure to milder cold stress (10°C, an oxidative-mediated network has been proposed to play a key role in configuring early responses and short-term defenses. The components, hierarchical organization and physiological consequences of this network were further dissected by a systems-level approach. Results Regulatory clusters responding directly to oxidative signals were prominent during the initial 6 to 12 hours at 10°C. Early events mirrored a typical oxidative response based on striking similarities of the transcriptome to disease, elicitor and wounding induced processes. Targets of oxidative-mediated mechanisms are likely regulated by several classes of bZIP factors acting on as1/ocs/TGA-like element enriched clusters, ERF factors acting on GCC-box/JAre-like element enriched clusters and R2R3-MYB factors acting on MYB2-like element enriched clusters. Temporal induction of several H2O2-induced bZIP, ERF and MYB genes coincided with the transient H2O2 spikes within the initial 6 to 12 hours. Oxidative-independent responses involve DREB/CBF, RAP2 and RAV1 factors acting on DRE/CRT/rav1-like enriched clusters and bZIP factors acting on ABRE-like enriched clusters. Oxidative-mediated clusters were activated earlier than ABA-mediated clusters. Conclusion Genome-wide, physiological and whole-plant level analyses established a holistic view of chilling stress response mechanism of japonica rice. Early response regulatory network triggered by oxidative signals is critical for prolonged survival under sub-optimal temperature. Integration of stress and developmental responses leads to modulated growth and vigor maintenance contributing to a delay of plastic injuries.

Transcriptional regulatory network triggered by oxidative signals configures the early response mechanisms of japonica rice to chilling stress

KAUST Repository

Yun, Kil-Young

2010-01-25

Background: The transcriptional regulatory network involved in low temperature response leading to acclimation has been established in Arabidopsis. In japonica rice, which can only withstand transient exposure to milder cold stress (10C), an oxidative-mediated network has been proposed to play a key role in configuring early responses and short-term defenses. The components, hierarchical organization and physiological consequences of this network were further dissected by a systems-level approach.Results: Regulatory clusters responding directly to oxidative signals were prominent during the initial 6 to 12 hours at 10C. Early events mirrored a typical oxidative response based on striking similarities of the transcriptome to disease, elicitor and wounding induced processes. Targets of oxidative-mediated mechanisms are likely regulated by several classes of bZIP factors acting on as1/ocs/TGA-like element enriched clusters, ERF factors acting on GCC-box/JAre-like element enriched clusters and R2R3-MYB factors acting on MYB2-like element enriched clusters.Temporal induction of several H2O2-induced bZIP, ERF and MYB genes coincided with the transient H2O2spikes within the initial 6 to 12 hours. Oxidative-independent responses involve DREB/CBF, RAP2 and RAV1 factors acting on DRE/CRT/rav1-like enriched clusters and bZIP factors acting on ABRE-like enriched clusters. Oxidative-mediated clusters were activated earlier than ABA-mediated clusters.Conclusion: Genome-wide, physiological and whole-plant level analyses established a holistic view of chilling stress response mechanism of japonica rice. Early response regulatory network triggered by oxidative signals is critical for prolonged survival under sub-optimal temperature. Integration of stress and developmental responses leads to modulated growth and vigor maintenance contributing to a delay of plastic injuries. 2010 Yun et al; licensee BioMed Central Ltd.

Bruchid egg induced transcript dynamics in developing seeds of black gram (Vigna mungo.

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Indrani K Baruah

Full Text Available Black gram (Vigna mungo seeds are a rich source of digestible proteins, however, during storage these seeds are severely damaged by bruchids (Callosobruchus spp., reducing seed quality and yield losses. Most of the cultivated genotypes of black gram are susceptible to bruchids, however, few tolerant genotypes have also been identified but the mechanism of tolerance is poorly understood. We employed Suppression Subtractive Hybridization (SSH to identify specifically, but rarely expressed bruchid egg induced genes in black gram. In this study, Suppression Subtractive Hybridization (SSH library was constructed to study the genes involved in defense response in black gram against bruchid infestation. An EST library of 277 clones was obtained for further analyses. Based on CAP3 assembly, 134 unigenes were computationally annotated using Blast2GOPRO software. In all, 20 defense related genes were subject to quantitative PCR analysis (qPCR out of which 12 genes showed up-regulation in developing seeds of the pods oviposited by bruchids. Few major defense genes like defensin, pathogenesis related protein (PR, lipoxygenase (LOX showed high expression levels in the oviposited population when compared with the non-oviposited plants. This is the first report on defense related gene transcript dynamics during the bruchid-black gram interaction using SSH library. This library would be useful to clone defense related gene(s such as defensin as represented in our library for crop improvement.

The endochitinase VDECH from Verticillium dahliae inhibits spore germination and activates plant defense responses

Science.gov (United States)

Chitinases function in the digestion of chitin molecules, which are present principally in insects and fungi. In plants, chitinase genes play important roles in defense, and their expression can be triggered in response to both biotic and abiotic stresses. In this study, we cloned and characterized ...

The US-Russia missile defense dialogue as a factor of the Russian defense policy

OpenAIRE

Dmitry Suslov

2013-01-01

To a big extent the Russian defense policy and, as a consequence, development of the Russian defense industrial complex, is determined by the prospects of the US missile defense policy and fate of the US-Russia negotiations in this area. As a cooperative solution seems improbable in the observable future, Russia plans to develop certain response measures of military nature, including creation of a new heavy ICBM, and to create its own missile defense by 2015. However, this policy does not see...

Transcriptome profiling confirmed correlations between symptoms and transcriptional changes in RDV infected rice and revealed nucleolus as a possible target of RDV manipulation.

Science.gov (United States)

Yang, Liang; Du, Zhenguo; Gao, Feng; Wu, Kangcheng; Xie, Lianhui; Li, Yi; Wu, Zujian; Wu, Jianguo

2014-05-06

Rice dwarf virus (RDV) is the causal agent of rice dwarf disease, which limits rice production in many areas of south East Asia. Transcriptional changes of rice in response to RDV infection have been characterized by Shimizu et al. and Satoh et al.. Both studies found induction of defense related genes and correlations between transcriptional changes and symptom development in RDV-infected rice. However, the same rice cultivar, namely Nipponbare belonging to the Japonic subspecies of rice was used in both studies. Gene expression changes of the indica subspecies of rice, namely Oryza sativa L. ssp. indica cv Yixiang2292 that show moderate resistance to RDV, in response to RDV infection were characterized using an Affymetrix Rice Genome Array. Differentially expressed genes (DEGs) were classified according to their Gene Ontology (GO) annotation. The effects of transient expression of Pns11 in Nicotiana benthaminana on the expression of nucleolar genes were studied using real-time PCR (RT-PCR). 856 genes involved in defense or other physiological processes were identified to be DEGs, most of which showed up-regulation. Ribosome- and nucleolus related genes were significantly enriched in the DEGs. Representative genes related to nucleolar function exhibited altered expression in N. benthaminana plants transiently expressing Pns11 of RDV. Induction of defense related genes is common for rice infected with RDV. There is a co-relation between symptom severity and transcriptional alteration in RDV infected rice. Besides ribosome, RDV may also target nucleolus to manipulate the translation machinery of rice. Given the tight links between nucleolus and ribosome, it is intriguing to speculate that RDV may enhance expression of ribosomal genes by targeting nucleolus through Pns11.

Seaweed Polysaccharides and Derived Oligosaccharides Stimulate Defense Responses and Protection Against Pathogens in Plants

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Alejandra Moenne

2011-11-01

Full Text Available Plants interact with the environment by sensing “non-self” molecules called elicitors derived from pathogens or other sources. These molecules bind to specific receptors located in the plasma membrane and trigger defense responses leading to protection against pathogens. In particular, it has been shown that cell wall and storage polysaccharides from green, brown and red seaweeds (marine macroalgae corresponding to ulvans, alginates, fucans, laminarin and carrageenans can trigger defense responses in plants enhancing protection against pathogens. In addition, oligosaccharides obtained by depolymerization of seaweed polysaccharides also induce protection against viral, fungal and bacterial infections in plants. In particular, most seaweed polysaccharides and derived oligosaccharides trigger an initial oxidative burst at local level and the activation of salicylic (SA, jasmonic acid (JA and/or ethylene signaling pathways at systemic level. The activation of these signaling pathways leads to an increased expression of genes encoding: (i Pathogenesis-Related (PR proteins with antifungal and antibacterial activities; (ii defense enzymes such as pheylalanine ammonia lyase (PAL and lipoxygenase (LOX which determine accumulation of phenylpropanoid compounds (PPCs and oxylipins with antiviral, antifugal and antibacterial activities and iii enzymes involved in synthesis of terpenes, terpenoids and/or alkaloids having antimicrobial activities. Thus, seaweed polysaccharides and their derived oligosaccharides induced the accumulation of proteins and compounds with antimicrobial activities that determine, at least in part, the enhanced protection against pathogens in plants.

Long non-coding RNAs as molecular players in plant defense against pathogens.

Science.gov (United States)

Zaynab, Madiha; Fatima, Mahpara; Abbas, Safdar; Umair, Muhammad; Sharif, Yasir; Raza, Muhammad Ammar

2018-05-31

Long non-coding RNAs (lncRNAs) has significant role in of gene expression and silencing pathways for several biological processes in eukaryotes. lncRNAs has been reported as key player in remodeling chromatin and genome architecture, RNA stabilization and transcription regulation, including enhancer-associated activity. Host lncRNAs are reckoned as compulsory elements of plant defense. In response to pathogen attack, plants protect themselves with the help of lncRNAs -dependent immune systems in which lncRNAs regulate pathogen-associated molecular patterns (PAMPs) and other effectors. Role of lncRNAs in plant microbe interaction has been studied extensively but regulations of several lncRNAs still need extensive research. In this study we discussed and provide as overview the topical advancements and findings relevant to pathogen attack and plant defense mediated by lncRNAs. It is hoped that lncRNAs would be exploited as a mainstream player to achieve food security by tackling different plant diseases. Copyright © 2018. Published by Elsevier Ltd.

Conservation and divergence of chemical defense system in the tunicate Oikopleura dioica revealed by genome wide response to two xenobiotics

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Yadetie Fekadu

2012-02-01

Full Text Available Abstract Background Animals have developed extensive mechanisms of response to xenobiotic chemical attacks. Although recent genome surveys have suggested a broad conservation of the chemical defensome across metazoans, global gene expression responses to xenobiotics have not been well investigated in most invertebrates. Here, we performed genome survey for key defensome genes in Oikopleura dioica genome, and explored genome-wide gene expression using high density tiling arrays with over 2 million probes, in response to two model xenobiotic chemicals - the carcinogenic polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP the pharmaceutical compound Clofibrate (Clo. Results Oikopleura genome surveys for key genes of the chemical defensome suggested a reduced repertoire. Not more than 23 cytochrome P450 (CYP genes could be identified, and neither CYP1 family genes nor their transcriptional activator AhR was detected. These two genes were present in deuterostome ancestors. As in vertebrates, the genotoxic compound BaP induced xenobiotic biotransformation and oxidative stress responsive genes. Notable exceptions were genes of the aryl hydrocarbon receptor (AhR signaling pathway. Clo also affected the expression of many biotransformation genes and markedly repressed genes involved in energy metabolism and muscle contraction pathways. Conclusions Oikopleura has the smallest number of CYP genes among sequenced animal genomes and lacks the AhR signaling pathway. However it appears to have basic xenobiotic inducible biotransformation genes such as a conserved genotoxic stress response gene set. Our genome survey and expression study does not support a role of AhR signaling pathway in the chemical defense of metazoans prior to the emergence of vertebrates.

Novel Fungal Pathogenicity and Leaf Defense Strategies Are Revealed by Simultaneous Transcriptome Analysis of Colletotrichum fructicola and Strawberry Infected by This Fungus

OpenAIRE

Liqing Zhang; Xin Huang; Chengyong He; Chengyong He; Qing-Yu Zhang; Xiaohua Zou; Ke Duan; Ke Duan; Qinghua Gao

2018-01-01

Colletotrichum fructicola, which is part of the C. gloeosporioides species complex, can cause anthracnose diseases in strawberries worldwide. However, the molecular interactions between C. fructicola and strawberry are largely unknown. A deep RNA-sequencing approach was applied to gain insights into the pathogenicity mechanisms of C. fructicola and the defense response of strawberry plants at different stages of infection. The transcriptome data showed stage-specific transcription accompanied...

Cyclic lipopeptides from Bacillus subtilis ABS-S14 elicit defense-related gene expression in citrus fruit

Science.gov (United States)

Effects of cyclic lipopeptides obtained from B. subtilis ABS-S14 on eliciting defense-related gene transcription and activity of defense-related enzymes glucanase (GLU), chitinase (CHI), peroxidase (POX) and lipoxygenase (LOX) in Citrus sinensis cv. Valencia fruit were determined. The maximum level ...

Plant defense against insect herbivores

DEFF Research Database (Denmark)

Fürstenberg-Hägg, Joel; Zagrobelny, Mika; Bak, Søren

2013-01-01

, defense compounds. These bioactive specialized plant defense compounds may repel or intoxicate insects, while defense proteins often interfere with their digestion. Volatiles are released upon herbivory to repel herbivores, attract predators or for communication between leaves or plants, and to induce......Plants have been interacting with insects for several hundred million years, leading to complex defense approaches against various insect feeding strategies. Some defenses are constitutive while others are induced, although the insecticidal defense compound or protein classes are often similar...... defense responses. Plants also apply morphological features like waxes, trichomes and latices to make the feeding more difficult for the insects. Extrafloral nectar, food bodies and nesting or refuge sites are produced to accommodate and feed the predators of the herbivores. Meanwhile, herbivorous insects...

32 CFR 13.3 - Office of the Chief Defense Counsel.

Science.gov (United States)

2010-07-01

... COMMISSIONS RESPONSIBILITIES OF THE CHIEF DEFENSE COUNSEL, DETAILED DEFENSE COUNSEL, AND CIVILIAN DEFENSE... II of the Affidavit And Agreement By Civilian Defense Counsel at Appendix B to 32 CFR part 14. (5... incur confidentiality obligations in the context of fulfilling their supervisory responsibilities with...

Microbial phylogeny determines transcriptional response of resistome to dynamic composting processes.

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Wang, Cheng; Dong, Da; Strong, P J; Zhu, Weijing; Ma, Zhuang; Qin, Yong; Wu, Weixiang

2017-08-16

Animal manure is a reservoir of antibiotic resistance genes (ARGs) that pose a potential health risk globally, especially for resistance to the antibiotics commonly used in livestock production (such as tetracycline, sulfonamide, and fluoroquinolone). Currently, the effects of biological treatment (composting) on the transcriptional response of manure ARGs and their microbial hosts are not well characterized. Composting is a dynamic process that consists of four distinct phases that are distinguished by the temperature resulting from microbial activity, namely the mesophilic, thermophilic, cooling, and maturing phases. In this study, changes of resistome expression were determined and related to active microbiome profiles during the dynamic composting process. This was achieved by integrating metagenomic and time series metatranscriptomic data for the evolving microbial community during composting. Composting noticeably reduced the aggregated expression level of the manure resistome, which primarily consisted of genes encoding for tetracycline, vancomycin, fluoroquinolone, beta-lactam, and aminoglycoside resistance, as well as efflux pumps. Furthermore, a varied transcriptional response of resistome to composting at the ARG levels was highlighted. The expression of tetracycline resistance genes (tetM-tetW-tetO-tetS) decreased during composting, where distinctive shifts in the four phases of composting were related to variations in antibiotic concentration. Composting had no effect on the expression of sulfonamide and fluoroquinolone resistance genes, which increased slightly during the thermophilic phase and then decreased to initial levels. As indigenous populations switched greatly throughout the dynamic composting, the core resistome persisted and their reservoir hosts' composition was significantly correlated with dynamic active microbial phylogenetic structure. Hosts for sulfonamide and fuoroquinolone resistance genes changed notably in phylognetic structure

Limited transcriptional responses of Rickettsia rickettsii exposed to environmental stimuli.

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Damon W Ellison

Full Text Available Rickettsiae are strict obligate intracellular pathogens that alternate between arthropod and mammalian hosts in a zoonotic cycle. Typically, pathogenic bacteria that cycle between environmental sources and mammalian hosts adapt to the respective environments by coordinately regulating gene expression such that genes essential for survival and virulence are expressed only upon infection of mammals. Temperature is a common environmental signal for upregulation of virulence gene expression although other factors may also play a role. We examined the transcriptional responses of Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, to a variety of environmental signals expected to be encountered during its life cycle. R. rickettsii exposed to differences in growth temperature (25 degrees C vs. 37 degrees C, iron limitation, and host cell species displayed nominal changes in gene expression under any of these conditions with only 0, 5, or 7 genes, respectively, changing more than 3-fold in expression levels. R. rickettsii is not totally devoid of ability to respond to temperature shifts as cold shock (37 degrees C vs. 4 degrees C induced a change greater than 3-fold in up to 56 genes. Rickettsiae continuously occupy a relatively stable environment which is the cytosol of eukaryotic cells. Because of their obligate intracellular character, rickettsiae are believed to be undergoing reductive evolution to a minimal genome. We propose that their relatively constant environmental niche has led to a minimal requirement for R. rickettsii to respond to environmental changes with a consequent deletion of non-essential transcriptional response regulators. A minimal number of predicted transcriptional regulators in the R. rickettsii genome is consistent with this hypothesis.

Glucosinolate metabolites required for an Arabidopsis innate immune response.

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Clay, Nicole K; Adio, Adewale M; Denoux, Carine; Jander, Georg; Ausubel, Frederick M

2009-01-02

The perception of pathogen or microbe-associated molecular pattern molecules by plants triggers a basal defense response analogous to animal innate immunity and is defined partly by the deposition of the glucan polymer callose at the cell wall at the site of pathogen contact. Transcriptional and metabolic profiling in Arabidopsis mutants, coupled with the monitoring of pathogen-triggered callose deposition, have identified major roles in pathogen response for the plant hormone ethylene and the secondary metabolite 4-methoxy-indol-3-ylmethylglucosinolate. Two genes, PEN2 and PEN3, are also necessary for resistance to pathogens and are required for both callose deposition and glucosinolate activation, suggesting that the pathogen-triggered callose response is required for resistance to microbial pathogens. Our study shows that well-studied plant metabolites, previously identified as important in avoiding damage by herbivores, are also required as a component of the plant defense response against microbial pathogens.

Set2 Methyltransferase Facilitates DNA Replication and Promotes Genotoxic Stress Responses through MBF-Dependent Transcription.

Science.gov (United States)

Pai, Chen-Chun; Kishkevich, Anastasiya; Deegan, Rachel S; Keszthelyi, Andrea; Folkes, Lisa; Kearsey, Stephen E; De León, Nagore; Soriano, Ignacio; de Bruin, Robertus Antonius Maria; Carr, Antony M; Humphrey, Timothy C

2017-09-12

Chromatin modification through histone H3 lysine 36 methylation by the SETD2 tumor suppressor plays a key role in maintaining genome stability. Here, we describe a role for Set2-dependent H3K36 methylation in facilitating DNA replication and the transcriptional responses to both replication stress and DNA damage through promoting MluI cell-cycle box (MCB) binding factor (MBF)-complex-dependent transcription in fission yeast. Set2 loss leads to reduced MBF-dependent ribonucleotide reductase (RNR) expression, reduced deoxyribonucleoside triphosphate (dNTP) synthesis, altered replication origin firing, and a checkpoint-dependent S-phase delay. Accordingly, prolonged S phase in the absence of Set2 is suppressed by increasing dNTP synthesis. Furthermore, H3K36 is di- and tri-methylated at these MBF gene promoters, and Set2 loss leads to reduced MBF binding and transcription in response to genotoxic stress. Together, these findings provide new insights into how H3K36 methylation facilitates DNA replication and promotes genotoxic stress responses in fission yeast. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Set2 Methyltransferase Facilitates DNA Replication and Promotes Genotoxic Stress Responses through MBF-Dependent Transcription

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Chen-Chun Pai

2017-09-01

Full Text Available Chromatin modification through histone H3 lysine 36 methylation by the SETD2 tumor suppressor plays a key role in maintaining genome stability. Here, we describe a role for Set2-dependent H3K36 methylation in facilitating DNA replication and the transcriptional responses to both replication stress and DNA damage through promoting MluI cell-cycle box (MCB binding factor (MBF-complex-dependent transcription in fission yeast. Set2 loss leads to reduced MBF-dependent ribonucleotide reductase (RNR expression, reduced deoxyribonucleoside triphosphate (dNTP synthesis, altered replication origin firing, and a checkpoint-dependent S-phase delay. Accordingly, prolonged S phase in the absence of Set2 is suppressed by increasing dNTP synthesis. Furthermore, H3K36 is di- and tri-methylated at these MBF gene promoters, and Set2 loss leads to reduced MBF binding and transcription in response to genotoxic stress. Together, these findings provide new insights into how H3K36 methylation facilitates DNA replication and promotes genotoxic stress responses in fission yeast.

Transcriptional Profiles of the Response to Ketoconazole and Amphotericin B in Trichophyton rubrum▿ †

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Yu, Lu; Zhang, Wenliang; Wang, Lingling; Yang, Jian; Liu, Tao; Peng, Junping; Leng, Wenchuan; Chen, Lihong; Li, Ruoyu; Jin, Qi

2007-01-01

Trichophyton rubrum is a pathogenic filamentous fungus of increasing medical concern. Two antifungal agents, ketoconazole (KTC) and amphotericin B (AMB), have specific activity against dermatophytes. To identify the mechanisms of action of KTC and AMB against T. rubrum, a cDNA microarray was constructed from the expressed sequence tags of the cDNA library from different developmental stages, and transcriptional profiles of the responses to KTC and AMB were determined. T. rubrum was exposed to subinhibitory concentrations of KTC and AMB for 12 h, and microarray analysis was used to examine gene transcription. KTC exposure induced transcription of genes involved in lipid, fatty acid, and sterol metabolism, including ERG11, ERG3, ERG25, ERG6, ERG26, ERG24, ERG4, CPO, INO1, DW700960, CPR, DW696584, DW406350, and ATG15. KTC also increased transcription of the multidrug resistance gene ABC1. AMB exposure increased transcription of genes involved in lipid, fatty acid, and sterol metabolism (DW696584, EB801458, IVD, DW694010, DW688343, DW684992), membrane transport (Git1, DW706156, DW684040, DMT, DW406136, CCH1, DW710650), and stress-related responses (HSP70, HSP104, GSS, AOX, EB801455, EB801702, TDH1, UBI4) but reduced transcription of genes involved in maintenance of cell wall integrity and signal transduction pathways (FKS1, SUN4, DW699324, GAS1, DW681613, SPS1, DW703091, STE7, DW703091, DW695308) and some ribosomal proteins. This is the first report of the use of microarray analysis to determine the effects of drug action in T. rubrum. PMID:17060531

Resistance-related gene transcription and antioxidant enzyme ...

African Journals Online (AJOL)

The two tobacco relatives of Nicotiana alata and Nicotiana longiflora display a high level of resistance against Colletotrichum nicotianae and the two genes NTF6 and NtPAL related to pathogen defense transcription were higher in N. alata and N. longiflora than the commercial cv. K326. Inoculation with C. nicotianae ...

Transcriptional 'memory' of a stress: transient chromatin and memory (epigenetic) marks at stress-response genes.

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Avramova, Zoya

2015-07-01

Drought, salinity, extreme temperature variations, pathogen and herbivory attacks are recurring environmental stresses experienced by plants throughout their life. To survive repeated stresses, plants provide responses that may be different from their response during the first encounter with the stress. A different response to a similar stress represents the concept of 'stress memory'. A coordinated reaction at the organismal, cellular and gene/genome levels is thought to increase survival chances by improving the plant's tolerance/avoidance abilities. Ultimately, stress memory may provide a mechanism for acclimation and adaptation. At the molecular level, the concept of stress memory indicates that the mechanisms responsible for memory-type transcription during repeated stresses are not based on repetitive activation of the same response pathways activated by the first stress. Some recent advances in the search for transcription 'memory factors' are discussed with an emphasis on super-induced dehydration stress memory response genes in Arabidopsis. © 2015 The Author The Plant Journal © 2015 John Wiley & Sons Ltd.

Transcriptional profiling of Medicago truncatula under salt stress identified a novel CBF transcription factor MtCBF4 that plays an important role in abiotic stress responses

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Su Zhen

2011-07-01

Full Text Available Abstract Background Salt stress hinders the growth of plants and reduces crop production worldwide. However, different plant species might possess different adaptive mechanisms to mitigate salt stress. We conducted a detailed pathway analysis of transcriptional dynamics in the roots of Medicago truncatula seedlings under salt stress and selected a transcription factor gene, MtCBF4, for experimental validation. Results A microarray experiment was conducted using root samples collected 6, 24, and 48 h after application of 180 mM NaCl. Analysis of 11 statistically significant expression profiles revealed different behaviors between primary and secondary metabolism pathways in response to external stress. Secondary metabolism that helps to maintain osmotic balance was induced. One of the highly induced transcription factor genes was successfully cloned, and was named MtCBF4. Phylogenetic analysis revealed that MtCBF4, which belongs to the AP2-EREBP transcription factor family, is a novel member of the CBF transcription factor in M. truncatula. MtCBF4 is shown to be a nuclear-localized protein. Expression of MtCBF4 in M. truncatula was induced by most of the abiotic stresses, including salt, drought, cold, and abscisic acid, suggesting crosstalk between these abiotic stresses. Transgenic Arabidopsis over-expressing MtCBF4 enhanced tolerance to drought and salt stress, and activated expression of downstream genes that contain DRE elements. Over-expression of MtCBF4 in M. truncatula also enhanced salt tolerance and induced expression level of corresponding downstream genes. Conclusion Comprehensive transcriptomic analysis revealed complex mechanisms exist in plants in response to salt stress. The novel transcription factor gene MtCBF4 identified here played an important role in response to abiotic stresses, indicating that it might be a good candidate gene for genetic improvement to produce stress-tolerant plants.

Transcriptional profiling of Medicago truncatula under salt stress identified a novel CBF transcription factor MtCBF4 that plays an important role in abiotic stress responses

Science.gov (United States)

2011-01-01

Background Salt stress hinders the growth of plants and reduces crop production worldwide. However, different plant species might possess different adaptive mechanisms to mitigate salt stress. We conducted a detailed pathway analysis of transcriptional dynamics in the roots of Medicago truncatula seedlings under salt stress and selected a transcription factor gene, MtCBF4, for experimental validation. Results A microarray experiment was conducted using root samples collected 6, 24, and 48 h after application of 180 mM NaCl. Analysis of 11 statistically significant expression profiles revealed different behaviors between primary and secondary metabolism pathways in response to external stress. Secondary metabolism that helps to maintain osmotic balance was induced. One of the highly induced transcription factor genes was successfully cloned, and was named MtCBF4. Phylogenetic analysis revealed that MtCBF4, which belongs to the AP2-EREBP transcription factor family, is a novel member of the CBF transcription factor in M. truncatula. MtCBF4 is shown to be a nuclear-localized protein. Expression of MtCBF4 in M. truncatula was induced by most of the abiotic stresses, including salt, drought, cold, and abscisic acid, suggesting crosstalk between these abiotic stresses. Transgenic Arabidopsis over-expressing MtCBF4 enhanced tolerance to drought and salt stress, and activated expression of downstream genes that contain DRE elements. Over-expression of MtCBF4 in M. truncatula also enhanced salt tolerance and induced expression level of corresponding downstream genes. Conclusion Comprehensive transcriptomic analysis revealed complex mechanisms exist in plants in response to salt stress. The novel transcription factor gene MtCBF4 identified here played an important role in response to abiotic stresses, indicating that it might be a good candidate gene for genetic improvement to produce stress-tolerant plants. PMID:21718548

Transcriptome Analysis Reveals Candidate Genes involved in Blister Blight defense in Tea (Camellia sinensis (L) Kuntze)

Science.gov (United States)

Jayaswall, Kuldip; Mahajan, Pallavi; Singh, Gagandeep; Parmar, Rajni; Seth, Romit; Raina, Aparnashree; Swarnkar, Mohit Kumar; Singh, Anil Kumar; Shankar, Ravi; Sharma, Ram Kumar

2016-07-01

To unravel the molecular mechanism of defense against blister blight (BB) disease caused by an obligate biotrophic fungus, Exobasidium vexans, transcriptome of BB interaction with resistance and susceptible tea genotypes was analysed through RNA-seq using Illumina GAIIx at four different stages during ~20-day disease cycle. Approximately 69 million high quality reads were assembled de novo, yielding 37,790 unique transcripts with more than 55% being functionally annotated. Differentially expressed, 149 defense related transcripts/genes, namely defense related enzymes, resistance genes, multidrug resistant transporters, transcription factors, retrotransposons, metacaspases and chaperons were observed in RG, suggesting their role in defending against BB. Being present in the major hub, putative master regulators among these candidates were identified from predetermined protein-protein interaction network of Arabidopsis thaliana. Further, confirmation of abundant expression of well-known RPM1, RPS2 and RPP13 in quantitative Real Time PCR indicates salicylic acid and jasmonic acid, possibly induce synthesis of antimicrobial compounds, required to overcome the virulence of E. vexans. Compendiously, the current study provides a comprehensive gene expression and insights into the molecular mechanism of tea defense against BB to serve as a resource for unravelling the possible regulatory mechanism of immunity against various biotic stresses in tea and other crops.

A Semi-Supervised Approach for Refining Transcriptional Signatures of Drug Response and Repositioning Predictions.

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Francesco Iorio

Full Text Available We present a novel strategy to identify drug-repositioning opportunities. The starting point of our method is the generation of a signature summarising the consensual transcriptional response of multiple human cell lines to a compound of interest (namely the seed compound. This signature can be derived from data in existing databases, such as the connectivity-map, and it is used at first instance to query a network interlinking all the connectivity-map compounds, based on the similarity of their transcriptional responses. This provides a drug neighbourhood, composed of compounds predicted to share some effects with the seed one. The original signature is then refined by systematically reducing its overlap with the transcriptional responses induced by drugs in this neighbourhood that are known to share a secondary effect with the seed compound. Finally, the drug network is queried again with the resulting refined signatures and the whole process is carried on for a number of iterations. Drugs in the final refined neighbourhood are then predicted to exert the principal mode of action of the seed compound. We illustrate our approach using paclitaxel (a microtubule stabilising agent as seed compound. Our method predicts that glipizide and splitomicin perturb microtubule function in human cells: a result that could not be obtained through standard signature matching methods. In agreement, we find that glipizide and splitomicin reduce interphase microtubule growth rates and transiently increase the percentage of mitotic cells-consistent with our prediction. Finally, we validated the refined signatures of paclitaxel response by mining a large drug screening dataset, showing that human cancer cell lines whose basal transcriptional profile is anti-correlated to them are significantly more sensitive to paclitaxel and docetaxel.

Inflammation response at the transcriptional level of HepG2 cells induced by multi-walled carbon nanotubes

International Nuclear Information System (INIS)

Piret, Jean-Pascal; Vankoningsloo, Sebastien; Noel, Florence; Saout, Christelle; Toussaint, Olivier; Mendoza, Jorge Mejia; Lucas, Stephane

2011-01-01

Poor information are currently available about the biological effects of multi-walled carbon nanotubes (MWCNT) on the liver. In this study, we evaluated the effects of MWCNT at the transcriptional level on the classical in vitro model of HepG2 hepatocarcinoma cells. The expression levels of 96 transcript species implicated in the inflammatory and immune responses was studied after a 24h incubation of HepG2 cells in presence of raw MWCNT dispersed in water by stirring. Among the 46 transcript species detected, only a few transcripts including mRNA coding for interleukine-7, chemokines receptor of the C-C families CCR7, as well as Endothelin-1, were statistically more abundant after treatment with MWCNT. Altogether, these data indicate that MWCNT can only induce a weak inflammatory response in HepG2 cells.

Inflammation response at the transcriptional level of HepG2 cells induced by multi-walled carbon nanotubes

Science.gov (United States)

Piret, Jean-Pascal; Vankoningsloo, Sébastien; Noël, Florence; Mejia Mendoza, Jorge; Lucas, Stéphane; Saout, Christelle; Toussaint, Olivier

2011-07-01

Poor information are currently available about the biological effects of multi-walled carbon nanotubes (MWCNT) on the liver. In this study, we evaluated the effects of MWCNT at the transcriptional level on the classical in vitro model of HepG2 hepatocarcinoma cells. The expression levels of 96 transcript species implicated in the inflammatory and immune responses was studied after a 24h incubation of HepG2 cells in presence of raw MWCNT dispersed in water by stirring. Among the 46 transcript species detected, only a few transcripts including mRNA coding for interleukine-7, chemokines receptor of the C-C families CCR7, as well as Endothelin-1, were statistically more abundant after treatment with MWCNT. Altogether, these data indicate that MWCNT can only induce a weak inflammatory response in HepG2 cells.

The Solanum lycopersicum WRKY3 Transcription Factor SlWRKY3 Is Involved in Salt Stress Tolerance in Tomato

Czech Academy of Sciences Publication Activity Database

Hichri, I.; Muhovski, Y.; Žižková, Eva; Dobrev, Petre; Gharbi, E.; Franco-Zorrilla, J.M.; Lopez-Vidriero, I.; Solano, R.; Clippe, A.; Errachid, A.; Motyka, Václav; Lutts, S.

2017-01-01

Roč. 8, JUL 31 (2017), č. článku 1343. ISSN 1664-462X R&D Projects: GA ČR(CZ) GA16-14649S Institutional support: RVO:61389030 Keywords : agrobacterium-mediated transformation * transgenic arabidopsis plants * dna-binding * salinity tolerance * defense responses * drought tolerance * abiotic stresses * water-stress * genes * tobacco * Solanum lycopersicum * SlWRKY3 * transcription factor * salinity tolerance * plant physiology Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 4.298, year: 2016

Exposure to 4100K fluorescent light elicits sex specific transcriptional responses in Xiphophorus maculatus skin.

Science.gov (United States)

Boswell, William T; Boswell, Mikki; Walter, Dylan J; Navarro, Kaela L; Chang, Jordan; Lu, Yuan; Savage, Markita G; Shen, Jianjun; Walter, Ronald B

2018-06-01

It has been reported that exposure to artificial light may affect oxygen intake, heart rate, absorption of vitamins and minerals, and behavioral responses in humans. We have reported specific gene expression responses in the skin of Xiphophorus fish after exposure to ultraviolet light (UV), as well as, both broad spectrum and narrow waveband visible light. In regard to fluorescent light (FL), we have shown that male X. maculatus exposed to 4100K FL (i.e. "cool white") rapidly suppress transcription of many genes involved with DNA replication and repair, chromosomal segregation, and cell cycle progression in skin. We have also detailed sex specific transcriptional responses of Xiphophorus skin after exposure to UVB. However, investigation of gender differences in global gene expression response after exposure to 4100K FL has not been reported, despite common use of this FL source for residential, commercial, and animal facility illumination. Here, we compare RNA-Seq results analyzed to assess changes in the global transcription profiles of female and male X. maculatus skin in response to 4100K FL exposure. Our results suggest 4100K FL exposure incites a sex-biased genetic response including up-modulation of inflammation in females and down modulation of DNA repair/replication in males. In addition, we identify clusters of genes that become oppositely modulated in males and females after FL exposure that are principally involved in cell death and cell proliferation. Copyright © 2017 Elsevier Inc. All rights reserved.

Salicylic acid-mediated and RNA-silencing defense mechanisms cooperate in the restriction of systemic spread of plum pox virus in tobacco.

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Alamillo, Josefa M; Saénz, Pilar; García, Juan Antonio

2006-10-01

Plum pox virus (PPV) is able to replicate in inoculated leaves of Nicotiana tabacum, but is defective in systemic movement in this host. However, PPV produces a systemic infection in transgenic tobacco expressing the silencing suppressor P1/HC-Pro from tobacco etch virus (TEV). In this work we show that PPV is able to move to upper non-inoculated leaves of tobacco plants expressing bacterial salicylate hydroxylase (NahG) that degrades salicylic acid (SA). Replication and accumulation of PPV is higher in the locally infected leaves of plants deficient in SA or expressing TEV P1/HC-Pro silencing suppressor. Accumulation of viral derived small RNAs was reduced in the NahG transgenic plants, suggesting that SA might act as an enhancer of the RNA-silencing antiviral defense in tobacco. Besides, expression of SA-mediated defense transcripts, such as those of pathogenesis-related (PR) proteins PR-1 and PR-2 or alternative oxidase-1, as well as that of the putative RNA-dependent RNA polymerase NtRDR1, is induced in response to PPV infection, and the expression patterns of these defense transcripts are altered in the TEV P1/HC-Pro transgenic plants. Long-distance movement of PPV is highly enhanced in NahG x P1/HC-Pro double-transgenic plants and systemic symptoms in these plants reveal that the expression of an RNA-silencing suppressor and the lack of SA produce additive but distinct effects. Our results suggest that SA might act as an enhancer of the RNA-silencing antiviral defense in tobacco, and that silencing suppressors, such as P1/HC-Pro, also alter the SA-mediated defense. Both an RNA-silencing and an SA-mediated defense mechanism could act together to limit PPV infection.

Transcriptional Changes during Naturally Acquired Zika Virus Infection Render Dendritic Cells Highly Conducive to Viral Replication.

Science.gov (United States)

Sun, Xiaoming; Hua, Stephane; Chen, Hsiao-Rong; Ouyang, Zhengyu; Einkauf, Kevin; Tse, Samantha; Ard, Kevin; Ciaranello, Andrea; Yawetz, Sigal; Sax, Paul; Rosenberg, Eric S; Lichterfeld, Mathias; Yu, Xu G

2017-12-19

Although dendritic cells are among the human cell population best equipped for cell-intrinsic antiviral immune defense, they seem highly susceptible to infection with the Zika virus (ZIKV). Using highly purified myeloid dendritic cells isolated from individuals with naturally acquired acute infection, we here show that ZIKV induces profound perturbations of transcriptional signatures relative to healthy donors. Interestingly, we noted a remarkable downregulation of antiviral interferon-stimulated genes and innate immune sensors, suggesting that ZIKV can actively suppress interferon-dependent immune responses. In contrast, several host factors known to support ZIKV infection were strongly upregulated during natural ZIKV infection; these transcripts included AXL, the main entry receptor for ZIKV; SOCS3, a negative regulator of ISG expression; and IDO-1, a recognized inducer of regulatory T cell responses. Thus, during in vivo infection, ZIKV can transform the transcriptome of dendritic cells in favor of the virus to render these cells highly conducive to ZIKV infection. Published by Elsevier Inc.

Defense radioactive waste management

International Nuclear Information System (INIS)

Hindman, T.B. Jr.

1988-01-01

The Office of Defense Programs (DP), U.S. Department of Energy, is responsible for the production of nuclear weapons and materials for national defense. Pursuant to this mission, DP operates a large industrial complex that employs over 60,000 people at various installations across the country. As a byproduct of their activities, these installations generate radioactive, hazardous, or mixed wastes that must be managed in a safe and cost-effective manner in compliance with all applicable Federal and STate environmental requirements. At the Federal level such requirements derive primarily from the Atomic Energy Act, the Resource Conservation and Recovery Act (RCRA), the comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Superfund Amendments and Reauthorization Act (SARA). Responsibility for DP activities in connection with the disposal of defense wastes is consolidated within the Office of Defense Waste and Transportation Management (DWTM). This paper discusses these activities which consist of five principal elements: the environmental restoration of inactive DP facilities and sites, the processing storage and disposal of wastes associated with ongoing operations at active DP facilities, research and development directed toward the long-term disposal of radioactive, hazardous, mixed wastes, technology development directly supporting regulatory compliance, and the development of policies, procedures, and technologies for assuring the safe transportation of radioactive and hazardous materials

Identification of bovine leukemia virus tax function associated with host cell transcription, signaling, stress response and immune response pathway by microarray-based gene expression analysis

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Arainga Mariluz

2012-03-01

Full Text Available Abstract Background Bovine leukemia virus (BLV is associated with enzootic bovine leukosis and is closely related to human T-cell leukemia virus type I. The Tax protein of BLV is a transcriptional activator of viral replication and a key contributor to oncogenic potential. We previously identified interesting mutant forms of Tax with elevated (TaxD247G or reduced (TaxS240P transactivation effects on BLV replication and propagation. However, the effects of these mutations on functions other than transcriptional activation are unknown. In this study, to identify genes that play a role in the cascade of signal events regulated by wild-type and mutant Tax proteins, we used a large-scale host cell gene-profiling approach. Results Using a microarray containing approximately 18,400 human mRNA transcripts, we found several alterations after the expression of Tax proteins in genes involved in many cellular functions such as transcription, signal transduction, cell growth, apoptosis, stress response, and immune response, indicating that Tax protein has multiple biological effects on various cellular environments. We also found that TaxD247G strongly regulated more genes involved in transcription, signal transduction, and cell growth functions, contrary to TaxS240P, which regulated fewer genes. In addition, the expression of genes related to stress response significantly increased in the presence of TaxS240P as compared to wild-type Tax and TaxD247G. By contrast, the largest group of downregulated genes was related to immune response, and the majority of these genes belonged to the interferon family. However, no significant difference in the expression level of downregulated genes was observed among the Tax proteins. Finally, the expression of important cellular factors obtained from the human microarray results were validated at the RNA and protein levels by real-time quantitative reverse transcription-polymerase chain reaction and western blotting

NAD1 Controls Defense-Like Responses in Medicago truncatula Symbiotic Nitrogen Fixing Nodules Following Rhizobial Colonization in a BacA-Independent Manner

Science.gov (United States)

Domonkos, Ágota; Kovács, Szilárd; Gombár, Anikó; Kiss, Ernő; Horváth, Beatrix; Kováts, Gyöngyi Z.; Farkas, Attila; Tóth, Mónika T.; Ayaydin, Ferhan; Bóka, Károly; Fodor, Lili; Endre, Gabriella; Kaló, Péter

2017-01-01

Legumes form endosymbiotic interaction with host compatible rhizobia, resulting in the development of nitrogen-fixing root nodules. Within symbiotic nodules, rhizobia are intracellularly accommodated in plant-derived membrane compartments, termed symbiosomes. In mature nodule, the massively colonized cells tolerate the existence of rhizobia without manifestation of visible defense responses, indicating the suppression of plant immunity in the nodule in the favur of the symbiotic partner. Medicago truncatula DNF2 (defective in nitrogen fixation 2) and NAD1 (nodules with activated defense 1) genes are essential for the control of plant defense during the colonization of the nitrogen-fixing nodule and are required for bacteroid persistence. The previously identified nodule-specific NAD1 gene encodes a protein of unknown function. Herein, we present the analysis of novel NAD1 mutant alleles to better understand the function of NAD1 in the repression of immune responses in symbiotic nodules. By exploiting the advantage of plant double and rhizobial mutants defective in establishing nitrogen-fixing symbiotic interaction, we show that NAD1 functions following the release of rhizobia from the infection threads and colonization of nodule cells. The suppression of plant defense is self-dependent of the differentiation status of the rhizobia. The corresponding phenotype of nad1 and dnf2 mutants and the similarity in the induction of defense-associated genes in both mutants suggest that NAD1 and DNF2 operate close together in the same pathway controlling defense responses in symbiotic nodules. PMID:29240711

NAD1 Controls Defense-Like Responses in Medicago truncatula Symbiotic Nitrogen Fixing Nodules Following Rhizobial Colonization in a BacA-Independent Manner

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Ágota Domonkos

2017-12-01

Full Text Available Legumes form endosymbiotic interaction with host compatible rhizobia, resulting in the development of nitrogen-fixing root nodules. Within symbiotic nodules, rhizobia are intracellularly accommodated in plant-derived membrane compartments, termed symbiosomes. In mature nodule, the massively colonized cells tolerate the existence of rhizobia without manifestation of visible defense responses, indicating the suppression of plant immunity in the nodule in the favur of the symbiotic partner. Medicago truncatula DNF2 (defective in nitrogen fixation 2 and NAD1 (nodules with activated defense 1 genes are essential for the control of plant defense during the colonization of the nitrogen-fixing nodule and are required for bacteroid persistence. The previously identified nodule-specific NAD1 gene encodes a protein of unknown function. Herein, we present the analysis of novel NAD1 mutant alleles to better understand the function of NAD1 in the repression of immune responses in symbiotic nodules. By exploiting the advantage of plant double and rhizobial mutants defective in establishing nitrogen-fixing symbiotic interaction, we show that NAD1 functions following the release of rhizobia from the infection threads and colonization of nodule cells. The suppression of plant defense is self-dependent of the differentiation status of the rhizobia. The corresponding phenotype of nad1 and dnf2 mutants and the similarity in the induction of defense-associated genes in both mutants suggest that NAD1 and DNF2 operate close together in the same pathway controlling defense responses in symbiotic nodules.

NAD1 Controls Defense-Like Responses in Medicago truncatula Symbiotic Nitrogen Fixing Nodules Following Rhizobial Colonization in a BacA-Independent Manner.

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Domonkos, Ágota; Kovács, Szilárd; Gombár, Anikó; Kiss, Ernő; Horváth, Beatrix; Kováts, Gyöngyi Z; Farkas, Attila; Tóth, Mónika T; Ayaydin, Ferhan; Bóka, Károly; Fodor, Lili; Ratet, Pascal; Kereszt, Attila; Endre, Gabriella; Kaló, Péter

2017-12-14

Legumes form endosymbiotic interaction with host compatible rhizobia, resulting in the development of nitrogen-fixing root nodules. Within symbiotic nodules, rhizobia are intracellularly accommodated in plant-derived membrane compartments, termed symbiosomes. In mature nodule, the massively colonized cells tolerate the existence of rhizobia without manifestation of visible defense responses, indicating the suppression of plant immunity in the nodule in the favur of the symbiotic partner. Medicago truncatula DNF2 (defective in nitrogen fixation 2) and NAD1 (nodules with activated defense 1) genes are essential for the control of plant defense during the colonization of the nitrogen-fixing nodule and are required for bacteroid persistence. The previously identified nodule-specific NAD1 gene encodes a protein of unknown function. Herein, we present the analysis of novel NAD1 mutant alleles to better understand the function of NAD1 in the repression of immune responses in symbiotic nodules. By exploiting the advantage of plant double and rhizobial mutants defective in establishing nitrogen-fixing symbiotic interaction, we show that NAD1 functions following the release of rhizobia from the infection threads and colonization of nodule cells. The suppression of plant defense is self-dependent of the differentiation status of the rhizobia. The corresponding phenotype of nad1 and dnf2 mutants and the similarity in the induction of defense-associated genes in both mutants suggest that NAD1 and DNF2 operate close together in the same pathway controlling defense responses in symbiotic nodules.

The CWI Pathway: Regulation of the Transcriptional Adaptive Response to Cell Wall Stress in Yeast

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Ana Belén Sanz

2017-12-01

Full Text Available Fungi are surrounded by an essential structure, the cell wall, which not only confers cell shape but also protects cells from environmental stress. As a consequence, yeast cells growing under cell wall damage conditions elicit rescue mechanisms to provide maintenance of cellular integrity and fungal survival. Through transcriptional reprogramming, yeast modulate the expression of genes important for cell wall biogenesis and remodeling, metabolism and energy generation, morphogenesis, signal transduction and stress. The yeast cell wall integrity (CWI pathway, which is very well conserved in other fungi, is the key pathway for the regulation of this adaptive response. In this review, we summarize the current knowledge of the yeast transcriptional program elicited to counterbalance cell wall stress situations, the role of the CWI pathway in the regulation of this program and the importance of the transcriptional input received by other pathways. Modulation of this adaptive response through the CWI pathway by positive and negative transcriptional feedbacks is also discussed. Since all these regulatory mechanisms are well conserved in pathogenic fungi, improving our knowledge about them will have an impact in the developing of new antifungal therapies.

Analysis of WRKY transcription factors and characterization of two Botrytis cinerea-responsive LrWRKY genes from Lilium regale.

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Cui, Qi; Yan, Xiao; Gao, Xue; Zhang, Dong-Mei; He, Heng-Bin; Jia, Gui-Xia

2018-06-01

A major constraint in producing lilies is gray mold caused by Botrytis elliptica and B. cinerea. WRKY transcription factors play important roles in plant immune responses. However, limited information is available about the WRKY gene family in lily plants. In this study, 23 LrWRKY genes with complete WRKY domains were identified from the Botrytis-resistant species Lilium regale. The putative WRKY genes were divided into seven subgroups (Group I, IIa-e, and III) according to their structural features. Sequence alignment revealed that LrWRKY proteins have a highly conserved WRKYGQK domain and a variant, the WRKYGKK domain, and these proteins generally contained similar motif compositions throughout the same subgroup. Functional annotation predicted they might be involved in biological processes related to abiotic and biotic stresses. A qRT-PCR analysis confirmed that expression of six LrWRKY genes in L. regale or the susceptible Asian hybrid 'Yale' was induced by B. cinerea infection. Among these genes, LrWRKY4, LrWRKY8 and LrWRKY10 were expressed at a higher level in L. regale than 'Yale', while the expression of LrWRKY6 and LrWRKY12 was lower in L. regale. Furthermore, LrWRKY4 and LrWRKY12 genes, which also respond to salicylic acid (SA) and methyl jasmonate (MeJA) treatments, were isolated from L. regale. Subcellular localization analysis determined that they were targeted to the nucleus. Constitutive expression of LrWRKY4 and LrWRKY12 in Arabidopsis resulted in plants that were more resistant to B. cinerea than wild-type plants. This resistance was coupled with the transcriptional changes of SA and JA-responsive genes. Overall, our study provides valuable information about the structural and functional characterization of LrWRKY genes that will not only deepen our understanding of the molecular mechanisms underlying the defense of lily against B. cinerea but also offer potential targets for cultivar improvement via biotechnology. Copyright © 2018 Elsevier Masson

Molecular Dynamics Simulation and Statistics Analysis Reveals the Defense Response Mechanism in Plants

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Liu, Zhichao; Zhao, Yunjie; Zeng, Chen; Computational Biophysics Lab Team

As the main protein of the bacterial flagella, flagellin plays an important role in perception and defense response. The newly discovered locus, FLS2, is ubiquitously expressed. FLS2 encodes a putative receptor kinase and shares many homologies with some plant resistance genes and even with some components of immune system of mammals and insects. In Arabidopsis, FLS2 perception is achieved by the recognition of epitope flg22, which induces FLS2 heteromerization with BAK1 and finally the plant immunity. Here we use both analytical methods such as Direct Coupling Analysis (DCA) and Molecular Dynamics (MD) Simulations to get a better understanding of the defense mechanism of FLS2. This may facilitate a redesign of flg22 or de-novo design for desired specificity and potency to extend the immune properties of FLS2 to other important crops and vegetables.

Sleep is not just for the brain: transcriptional responses to sleep in peripheral tissues

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2013-01-01

Background Many have assumed that the primary function of sleep is for the brain. We evaluated the molecular consequences of sleep and sleep deprivation outside the brain, in heart and lung. Using microarrays we compared gene expression in tissue from sleeping and sleep deprived mice euthanized at the same diurnal times. Results In each tissue, nearly two thousand genes demonstrated statistically significant differential expression as a function of sleep/wake behavioral state. To mitigate the influence of an artificial deprivation protocol, we identified a subset of these transcripts as specifically sleep-enhanced or sleep-repressed by requiring that their expression also change over the course of unperturbed sleep. 3% and 6% of the assayed transcripts showed “sleep specific” changes in the lung and heart respectively. Sleep specific transcripts in these tissues demonstrated highly significant overlap and shared temporal dynamics. Markers of cellular stress and the unfolded protein response were reduced during sleep in both tissues. These results mirror previous findings in brain. Sleep-enhanced pathways reflected the unique metabolic functions of each tissue. Transcripts related to carbohydrate and sulfur metabolic processes were enhanced by sleep in the lung, and collectively favor buffering from oxidative stress. DNA repair and protein metabolism annotations were significantly enriched among the sleep-enhanced transcripts in the heart. Our results also suggest that sleep may provide a Zeitgeber, or synchronizing cue, in the lung as a large cluster of transcripts demonstrated systematic changes in inter-animal variability as a function of both sleep duration and circadian time. Conclusion Our data support the notion that the molecular consequences of sleep/wake behavioral state extend beyond the brain to include peripheral tissues. Sleep state induces a highly overlapping response in both heart and lung. We conclude that sleep enhances organ specific

Sleep is not just for the brain: transcriptional responses to sleep in peripheral tissues.

Science.gov (United States)

Anafi, Ron C; Pellegrino, Renata; Shockley, Keith R; Romer, Micah; Tufik, Sergio; Pack, Allan I

2013-05-30

Many have assumed that the primary function of sleep is for the brain. We evaluated the molecular consequences of sleep and sleep deprivation outside the brain, in heart and lung. Using microarrays we compared gene expression in tissue from sleeping and sleep deprived mice euthanized at the same diurnal times. In each tissue, nearly two thousand genes demonstrated statistically significant differential expression as a function of sleep/wake behavioral state. To mitigate the influence of an artificial deprivation protocol, we identified a subset of these transcripts as specifically sleep-enhanced or sleep-repressed by requiring that their expression also change over the course of unperturbed sleep. 3% and 6% of the assayed transcripts showed "sleep specific" changes in the lung and heart respectively. Sleep specific transcripts in these tissues demonstrated highly significant overlap and shared temporal dynamics. Markers of cellular stress and the unfolded protein response were reduced during sleep in both tissues. These results mirror previous findings in brain. Sleep-enhanced pathways reflected the unique metabolic functions of each tissue. Transcripts related to carbohydrate and sulfur metabolic processes were enhanced by sleep in the lung, and collectively favor buffering from oxidative stress. DNA repair and protein metabolism annotations were significantly enriched among the sleep-enhanced transcripts in the heart. Our results also suggest that sleep may provide a Zeitgeber, or synchronizing cue, in the lung as a large cluster of transcripts demonstrated systematic changes in inter-animal variability as a function of both sleep duration and circadian time. Our data support the notion that the molecular consequences of sleep/wake behavioral state extend beyond the brain to include peripheral tissues. Sleep state induces a highly overlapping response in both heart and lung. We conclude that sleep enhances organ specific molecular functions and that it has a

Transcriptional profiles of Treponema denticola in response to environmental conditions.

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Ian McHardy

Full Text Available The periodontal pathogen T. denticola resides in a stressful environment rife with challenges, the human oral cavity. Knowledge of the stress response capabilities of this invasive spirochete is currently very limited. Whole genome expression profiles in response to different suspected stresses including heat shock, osmotic downshift, oxygen and blood exposure were examined. Most of the genes predicted to encode conserved heat shock proteins (HSPs were found to be induced under heat and oxygen stress. Several of these HSPs also seem to be important for survival in hypotonic solutions and blood. In addition to HSPs, differential regulation of many genes encoding metabolic proteins, hypothetical proteins, transcriptional regulators and transporters was observed in patterns that could betoken functional associations. In summary, stress responses in T. denticola exhibit many similarities to the corresponding stress responses in other organisms but also employ unique components including the induction of hypothetical proteins.

Volatile compounds from beneficial or pathogenic bacteria differentially regulate root exudation, transcription of iron transporters, and defense signaling pathways in Sorghum bicolor.

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Hernández-Calderón, Erasto; Aviles-Garcia, Maria Elizabeth; Castulo-Rubio, Diana Yazmín; Macías-Rodríguez, Lourdes; Ramírez, Vicente Montejano; Santoyo, Gustavo; López-Bucio, José; Valencia-Cantero, Eduardo

2018-02-01

Our results show that Sorghum bicolor is able to recognize bacteria through its volatile compounds and differentially respond to beneficial or pathogens via eliciting nutritional or defense adaptive traits. Plants establish beneficial, harmful, or neutral relationships with bacteria. Plant growth promoting rhizobacteria (PGPR) emit volatile compounds (VCs), which may act as molecular cues influencing plant development, nutrition, and/or defense. In this study, we compared the effects of VCs produced by bacteria with different lifestyles, including Arthrobacter agilis UMCV2, Bacillus methylotrophicus M4-96, Sinorhizobium meliloti 1021, the plant pathogen Pseudomonas aeruginosa PAO1, and the commensal rhizobacterium Bacillus sp. L2-64, on S. bicolor. We show that VCs from all tested bacteria, except Bacillus sp. L2-64, increased biomass and chlorophyll content, and improved root architecture, but notheworthy A. agilis induced the release of attractant molecules, whereas P. aeruginosa activated the exudation of growth inhibitory compounds by roots. An analysis of the expression of iron-transporters SbIRT1, SbIRT2, SbYS1, and SbYS2 and genes related to plant defense pathways COI1 and PR-1 indicated that beneficial, pathogenic, and commensal bacteria could up-regulate iron transporters, whereas only beneficial and pathogenic species could induce a defense response. These results show how S. bicolor could recognize bacteria through their volatiles profiles and highlight that PGPR or pathogens can elicit nutritional or defensive traits in plants.

Long noncoding RNAs responsive to Fusarium oxysporum infection in Arabidopsis thaliana.

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Zhu, Qian-Hao; Stephen, Stuart; Taylor, Jennifer; Helliwell, Chris A; Wang, Ming-Bo

2014-01-01

Short noncoding RNAs have been demonstrated to play important roles in regulation of gene expression and stress responses, but the repertoire and functions of long noncoding RNAs (lncRNAs) remain largely unexplored, particularly in plants. To explore the role of lncRNAs in disease resistance, we used a strand-specific RNA-sequencing approach to identify lncRNAs responsive to Fusarium oxysporum infection in Arabidopsis thaliana. Antisense transcription was found in c. 20% of the annotated A. thaliana genes. Several noncoding natural antisense transcripts responsive to F. oxysporum infection were found in genes implicated in disease defense. While the majority of the novel transcriptionally active regions (TARs) were adjacent to annotated genes and could be an extension of the annotated transcripts, 159 novel intergenic TARs, including 20 F. oxysporum-responsive lncTARs, were identified. Ten F. oxysporum-induced lncTARs were functionally characterized using T-DNA insertion or RNA-interference knockdown lines, and five were demonstrated to be related to disease development. Promoter analysis suggests that some of the F. oxysporum-induced lncTARs are direct targets of transcription factor(s) responsive to pathogen attack. Our results demonstrated that strand-specific RNA sequencing is a powerful tool for uncovering hidden levels of transcriptome and that IncRNAs are important components of the antifungal networks in A. thaliana. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Transcription factor assisted loading and enhancer dynamics dictate the hepatic fasting response

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Goldstein, Ido; Baek, Songjoon; Presman, Diego M.; Paakinaho, Ville; Swinstead, Erin E.; Hager, Gordon L.

2017-01-01

Fasting elicits transcriptional programs in hepatocytes leading to glucose and ketone production. This transcriptional program is regulated by many transcription factors (TFs). To understand how this complex network regulates the metabolic response to fasting, we aimed at isolating the enhancers and TFs dictating it. Measuring chromatin accessibility revealed that fasting massively reorganizes liver chromatin, exposing numerous fasting-induced enhancers. By utilizing computational methods in combination with dissecting enhancer features and TF cistromes, we implicated four key TFs regulating the fasting response: glucocorticoid receptor (GR), cAMP responsive element binding protein 1 (CREB1), peroxisome proliferator activated receptor alpha (PPARA), and CCAAT/enhancer binding protein beta (CEBPB). These TFs regulate fuel production by two distinctly operating modules, each controlling a separate metabolic pathway. The gluconeogenic module operates through assisted loading, whereby GR doubles the number of sites occupied by CREB1 as well as enhances CREB1 binding intensity and increases accessibility of CREB1 binding sites. Importantly, this GR-assisted CREB1 binding was enhancer-selective and did not affect all CREB1-bound enhancers. Single-molecule tracking revealed that GR increases the number and DNA residence time of a portion of chromatin-bound CREB1 molecules. These events collectively result in rapid synergistic gene expression and higher hepatic glucose production. Conversely, the ketogenic module operates via a GR-induced TF cascade, whereby PPARA levels are increased following GR activation, facilitating gradual enhancer maturation next to PPARA target genes and delayed ketogenic gene expression. Our findings reveal a complex network of enhancers and TFs that dynamically cooperate to restore homeostasis upon fasting. PMID:28031249

Regulation of Cancer Cell Responsiveness to Ionizing Radiation Treatment by Cyclic AMP Response Element Binding Nuclear Transcription Factor

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Francesca D’Auria

2017-05-01

Full Text Available Cyclic AMP response element binding (CREB protein is a member of the CREB/activating transcription factor (ATF family of transcription factors that play an important role in the cell response to different environmental stimuli leading to proliferation, differentiation, apoptosis, and survival. A number of studies highlight the involvement of CREB in the resistance to ionizing radiation (IR therapy, demonstrating a relationship between IR-induced CREB family members’ activation and cell survival. Consistent with these observations, we have recently demonstrated that CREB and ATF-1 are expressed in leukemia cell lines and that low-dose radiation treatment can trigger CREB activation, leading to survival of erythro-leukemia cells (K562. On the other hand, a number of evidences highlight a proapoptotic role of CREB following IR treatment of cancer cells. Since the development of multiple mechanisms of resistance is one key problem of most malignancies, including those of hematological origin, it is highly desirable to identify biological markers of responsiveness/unresponsiveness useful to follow-up the individual response and to adjust anticancer treatments. Taking into account all these considerations, this mini-review will be focused on the involvement of CREB/ATF family members in response to IR therapy, to deepen our knowledge of this topic, and to pave the way to translation into a therapeutic context.

Analysis of the transcriptional responses in inflorescence buds of Jatropha curcas exposed to cytokinin treatment.

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Chen, Mao-Sheng; Pan, Bang-Zhen; Wang, Gui-Juan; Ni, Jun; Niu, Longjian; Xu, Zeng-Fu

2014-11-30

Jatropha curcas L. is a potential biofuel plant. Application of exogenous cytokinin (6-benzyladenine, BA) on its inflorescence buds can significantly increase the number of female flowers, thereby improving seed yield. To investigate which genes and signal pathways are involved in the response to cytokinin in J. curcas inflorescence buds, we monitored transcriptional activity in inflorescences at 0, 3, 12, 24, and 48 h after BA treatment using a microarray. We detected 5,555 differentially expressed transcripts over the course of the experiment, which could be grouped into 12 distinct temporal expression patterns. We also identified 31 and 131 transcripts in J. curcas whose homologs in model plants function in flowering and phytohormonal signaling pathways, respectively. According to the transcriptional analysis of genes involved in flower development, we hypothesized that BA treatment delays floral organ formation by inhibiting the transcription of the A, B and E classes of floral organ-identity genes, which would allow more time to generate more floral primordia in inflorescence meristems, thereby enhancing inflorescence branching and significantly increasing flower number per inflorescence. BA treatment might also play an important role in maintaining the flowering signals by activating the transcription of GIGANTEA (GI) and inactivating the transcription of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) and TERMINAL FLOWER 1b (TFL1b). In addition, exogenous cytokinin treatment could regulate the expression of genes involved in the metabolism and signaling of other phytohormones, indicating that cytokinin and other phytohormones jointly regulate flower development in J. curcas inflorescence buds. Our study provides a framework to better understand the molecular mechanisms underlying changes in flowering traits in response to cytokinin treatment in J. curcas inflorescence buds. The results provide valuable information related to the mechanisms of cross-talk among

MicroRNA-Mediated Gene Silencing in Plant Defense and Viral Counter-Defense

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Sheng-Rui Liu

2017-09-01

Full Text Available MicroRNAs (miRNAs are non-coding RNAs of approximately 20–24 nucleotides in length that serve as central regulators of eukaryotic gene expression by targeting mRNAs for cleavage or translational repression. In plants, miRNAs are associated with numerous regulatory pathways in growth and development processes, and defensive responses in plant–pathogen interactions. Recently, significant progress has been made in understanding miRNA-mediated gene silencing and how viruses counter this defense mechanism. Here, we summarize the current knowledge and recent advances in understanding the roles of miRNAs involved in the plant defense against viruses and viral counter-defense. We also document the application of miRNAs in plant antiviral defense. This review discusses the current understanding of the mechanisms of miRNA-mediated gene silencing and provides insights on the never-ending arms race between plants and viruses.

Glucosinolate Metabolites Required for an Arabidopsis Innate Immune Response*

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Clay, Nicole K.; Adio, Adewale M.; Denoux, Carine; Jander, Georg; Ausubel, Frederick M.

2008-01-01

Summary The perception of pathogen or microbe-associated molecular pattern molecules by plants triggers a basal defense response analogous to animal innate immunity, and is defined in part by the deposition of the glucan polymer callose at the cell wall at the site of pathogen contact. Transcriptional and metabolic profiling in Arabidopsis mutants, coupled with the monitoring of pathogen triggered callose deposition, have identified major roles in pathogen response for the plant hormone ethylene and the secondary metabolite 4-methoxy-indol-3-ylmethylglucosinolate. Two genes, PEN2 and PEN3, are also necessary for resistance to pathogens and are required for both callose deposition and glucosinolate activation, suggesting that the pathogen triggered callose response is required for resistance to microbial pathogens. Our study shows that well-studied plant metabolites, previously identified as important in avoiding damage by herbivores, are also required as a component of the plant defense response against microbial pathogens. PMID:19095898

Ethylene Contributes to maize insect resistance1-Mediated Maize Defense against the Phloem Sap-Sucking Corn Leaf Aphid1[OPEN

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Louis, Joe; Basu, Saumik; Varsani, Suresh; Castano-Duque, Lina; Jiang, Victoria; Williams, W. Paul; Felton, Gary W.; Luthe, Dawn S.

2015-01-01

Signaling networks among multiple phytohormones fine-tune plant defense responses to insect herbivore attack. Previously, it was reported that the synergistic combination of ethylene (ET) and jasmonic acid (JA) was required for accumulation of the maize insect resistance1 (mir1) gene product, a cysteine (Cys) proteinase that is a key defensive protein against chewing insect pests in maize (Zea mays). However, this study suggests that mir1-mediated resistance to corn leaf aphid (CLA; Rhopalosiphum maidis), a phloem sap-sucking insect pest, is independent of JA but regulated by the ET-signaling pathway. Feeding by CLA triggers the rapid accumulation of mir1 transcripts in the resistant maize genotype, Mp708. Furthermore, Mp708 provided elevated levels of antibiosis (limits aphid population)- and antixenosis (deters aphid settling)-mediated resistance to CLA compared with B73 and Tx601 maize susceptible inbred lines. Synthetic diet aphid feeding trial bioassays with recombinant Mir1-Cys Protease demonstrates that Mir1-Cys Protease provides direct toxicity to CLA. Furthermore, foliar feeding by CLA rapidly sends defensive signal(s) to the roots that trigger belowground accumulation of the mir1, signifying a potential role of long-distance signaling in maize defense against the phloem-feeding insects. Collectively, our data indicate that ET-regulated mir1 transcript accumulation, uncoupled from JA, contributed to heightened resistance to CLA in maize. In addition, our results underscore the significance of ET acting as a central node in regulating mir1 expression to different feeding guilds of insect herbivores. PMID:26253737

Constitutively active Arabidopsis MAP Kinase 3 triggers defense responses involving salicylic acid and SUMM2 resistance protein

KAUST Repository

Genot, Baptiste

2017-04-12

Mitogen-activated protein kinases (MAPKs) are important regulators of plant immunity. Most of the knowledge about the function of these pathways is derived from loss-of-function approaches. Using a gain-of-function approach, we investigated the responses controlled by a constitutively active (CA) MPK3 in Arabidopsis thaliana. CA-MPK3 plants are dwarfed and display a massive de-repression of defense genes associated with spontaneous cell death as well as accumulation of reactive oxygen species (ROS), phytoalexins and the stress-related hormones ethylene and salicylic acid (SA). Remarkably CA-MPK3/sid2 and CA-MPK3/ein2-50 lines which are impaired in SA synthesis and ethylene signaling, respectively, retain most of the CA-MPK3-associated phenotypes, indicating that constitutive activity of MPK3 can bypass SA and ethylene signaling to activate defense responses. A comparative analysis of the molecular phenotypes of CA-MPK3 and mpk4 autoimmunity suggested convergence between the MPK3 and MPK4-guarding modules. In support of this model, CA-MPK3 crosses with summ1 and summ2, two known suppressors of mpk4, resulted in a partial reversion of the CA-MPK3 phenotypes. Overall, our data unravel a novel mechanism by which the MAPK signaling network contributes to a robust defense response system.

Characterization of WRKY transcription factors in Solanum lycopersicum reveals collinearity and their expression patterns under cold treatment.

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Chen, Lin; Yang, Yang; Liu, Can; Zheng, Yanyan; Xu, Mingshuang; Wu, Na; Sheng, Jiping; Shen, Lin

2015-08-28

WRKY transcription factors play an important role in cold defense of plants. However, little information is available about the cold-responsive WRKYs in tomato (Solanum lycopersicum). In the present study, a complete characterization of this gene family was described. Eighty WRKY genes in the tomato genome were identified. Almost all WRKY genes contain putative stress-responsive cis-elements in their promoter regions. Segmental duplications contributed significantly to the expansion of the SlWRKY gene family. Transcriptional analysis revealed notable differential expression in tomato tissues and expression patterns under cold stress, which indicated wide functional divergence in this family. Ten WRKYs in tomato were strongly induced more than 2-fold during cold stress. These genes represented candidate genes for future functional analysis of WRKYs involved in the cold-related signal pathways. Our data provide valuable information about tomato WRKY proteins and form a foundation for future studies of these proteins, especially for those that play an important role in response to cold stress. Copyright © 2015 Elsevier Inc. All rights reserved.

The Transcriptional Heat Shock Response of Salmonella Typhimurium Shows Hysteresis and Heated Cells Show Increased Resistance to Heat and Acid Stress

DEFF Research Database (Denmark)

Pin, C.; Hansen, Trine; Munoz-Cuevas, M.

2012-01-01

We investigated if the transcriptional response of Salmonella Typhimurium to temperature and acid variations was hysteretic, i.e. whether the transcriptional regulation caused by environmental stimuli showed memory and remained after the stimuli ceased. The transcriptional activity of non......, implying that down-regulation was significantly less synchronized than upregulation. The hysteretic transcriptional response to heat shock was accompanied by higher resistance to inactivation at 50uC as well as cross-resistance to inactivation at pH 3; however, growth rates and lag times at 43uC and at p......H 4.5 were not affected. The exposure to pH 5 only caused up-regulation of 12 genes and this response was neither hysteretic nor accompanied of increased resistance to inactivation conditions. Cellular memory at the transcriptional level may represent a mechanism of adaptation to the environment...

Transcriptional regulation of Arabidopsis MIR168a and argonaute1 homeostasis in abscisic acid and abiotic stress responses.

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Li, Wei; Cui, Xiao; Meng, Zhaolu; Huang, Xiahe; Xie, Qi; Wu, Heng; Jin, Hailing; Zhang, Dabing; Liang, Wanqi

2012-03-01

The accumulation of a number of small RNAs in plants is affected by abscisic acid (ABA) and abiotic stresses, but the underlying mechanisms are poorly understood. The miR168-mediated feedback regulatory loop regulates ARGONAUTE1 (AGO1) homeostasis, which is crucial for gene expression modulation and plant development. Here, we reveal a transcriptional regulatory mechanism by which MIR168 controls AGO1 homeostasis during ABA treatment and abiotic stress responses in Arabidopsis (Arabidopsis thaliana). Plants overexpressing MIR168a and the AGO1 loss-of-function mutant ago1-27 display ABA hypersensitivity and drought tolerance, while the mir168a-2 mutant shows ABA hyposensitivity and drought hypersensitivity. Both the precursor and mature miR168 were induced under ABA and several abiotic stress treatments, but no obvious decrease for the target of miR168, AGO1, was shown under the same conditions. However, promoter activity analysis indicated that AGO1 transcription activity was increased under ABA and drought treatments, suggesting that transcriptional elevation of MIR168a is required for maintaining a stable AGO1 transcript level during the stress response. Furthermore, we showed both in vitro and in vivo that the transcription of MIR168a is directly regulated by four abscisic acid-responsive element (ABRE) binding factors, which bind to the ABRE cis-element within the MIR168a promoter. This ABRE motif is also found in the promoter of MIR168a homologs in diverse plant species. Our findings suggest that transcriptional regulation of miR168 and posttranscriptional control of AGO1 homeostasis may play an important and conserved role in stress response and signal transduction in plants.

Transcriptional Profiling of Bone Marrow Stromal Cells in Response to Porphyromonas gingivalis Secreted Products

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Reddi, Durga; Belibasakis, Georgios N.

2012-01-01

Periodontitis is an infectious inflammatory disease that destroys the tooth-supporting (periodontal) tissues. Porphyromonas gingivalis is an oral pathogen highly implicated in the pathogenesis of this disease. It can exert its effects to a number of cells, including osteogenic bone marrow stromal cells which are important for homeostastic capacity of the tissues. By employing gene microarray technology, this study aimed to describe the overall transcriptional events (>2-fold regulation) elicited by P. gingivalis secreted products in bone marrow stromal cells, and to dissect further the categories of genes involved in bone metabolism, inflammatory and immune responses. After 6 h of challenge with P. gingivalis, 271 genes were up-regulated whereas 209 genes were down-regulated, whereas after 24 h, these numbers were 259 and 109, respectively. The early (6 h) response was characterised by regulation of genes associated with inhibition of cell cycle, induction of apoptosis and loss of structural integrity, whereas the late (24 h) response was characterised by induction of chemokines, cytokines and their associated intracellular pathways (such as NF-κB), mediators of connective tissue and bone destruction, and suppression of regulators of osteogenic differentiation. The most strongly up-regulated genes were lipocalin 2 (LCN2) and serum amyloid A3 (SAA3), both encoding for proteins of the acute phase inflammatory response. Collectively, these transcriptional changes elicited by P. gingivalis denote that the fundamental cellular functions are hindered, and that the cells acquire a phenotype commensurate with propagated innate immune response and inflammatory-mediated tissue destruction. In conclusion, the global transcriptional profile of bone marrow stromal cells in response to P. gingivalis is marked by deregulated homeostatic functions, with implications in the pathogenesis of periodontitis. PMID:22937121

Prediction of transcriptional regulatory elements for plant hormone responses based on microarray data

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Yamaguchi-Shinozaki Kazuko

2011-02-01

Full Text Available Abstract Background Phytohormones organize plant development and environmental adaptation through cell-to-cell signal transduction, and their action involves transcriptional activation. Recent international efforts to establish and maintain public databases of Arabidopsis microarray data have enabled the utilization of this data in the analysis of various phytohormone responses, providing genome-wide identification of promoters targeted by phytohormones. Results We utilized such microarray data for prediction of cis-regulatory elements with an octamer-based approach. Our test prediction of a drought-responsive RD29A promoter with the aid of microarray data for response to drought, ABA and overexpression of DREB1A, a key regulator of cold and drought response, provided reasonable results that fit with the experimentally identified regulatory elements. With this succession, we expanded the prediction to various phytohormone responses, including those for abscisic acid, auxin, cytokinin, ethylene, brassinosteroid, jasmonic acid, and salicylic acid, as well as for hydrogen peroxide, drought and DREB1A overexpression. Totally 622 promoters that are activated by phytohormones were subjected to the prediction. In addition, we have assigned putative functions to 53 octamers of the Regulatory Element Group (REG that have been extracted as position-dependent cis-regulatory elements with the aid of their feature of preferential appearance in the promoter region. Conclusions Our prediction of Arabidopsis cis-regulatory elements for phytohormone responses provides guidance for experimental analysis of promoters to reveal the basis of the transcriptional network of phytohormone responses.

A PR-4 gene identified from Malus domestica is involved in the defense responses against Botryosphaeria dothidea.

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Bai, Suhua; Dong, Chaohua; Li, Baohua; Dai, Hongyi

2013-01-01

Pathogenesis-related protein-4 (PR-4) family is a group of proteins with a Barwin domain in C-terminus and generally thought to be involved in plant defense responses. However, their detailed roles are poorly understood in defense of apple plant against pathogenic infection. In the present study, a new PR-4 gene (designated as MdPR-4) was identified from Malus domestica, and its roles in defense responses of apple were investigated. The open reading frame of MdPR-4 gene is of 447 bp encoding a protein of 148 amino acids with a Barwin domain in C-terminus and a signal peptide of 26 amino acids in N-terminus. Sequence and structural analysis indicated that MdPR-4 protein belongs to class II of PR-4 family. The high-level expression of MdPR-4 was observed in flowers and leaves as revealed by quantitative real time PCR. The temporal expression analysis demonstrated that MdPR-4 expression could be up-regulated by Botryosphaeria dothidea infection and salicylic acid (SA) or methyl jasmonate (MeJA) treatment, but suppressed by diethyldithiocarbamic acid (DIECA). In vitro assays, recombinant MdPR-4 protein exhibited ribonuclease activity specific for single strand RNA and significant inhibition to hyphal growth of three apple pathogenic fungi B. dothidea, Valsa ceratosperma and Glomerella cingulata. Moreover, the inhibition was reduced by the presence of 5'-ADP. Taken all together, the results indicate that MdPR-4 protein is involved in the defense responses of apple against pathogenic attack by directly inhibiting hyphal growth, and the inhibition is correlated with its ribonuclease activity, where as MdPR-4 expression is regulated by both SA and JA signaling pathway. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Structural characterization of a novel full-length transcript promoter from Horseradish Latent Virus (HRLV) and its transcriptional regulation by multiple stress responsive transcription factors.

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Khan, Ahamed; Shrestha, Ankita; Bhuyan, Kashyap; Maiti, Indu B; Dey, Nrisingha

2018-01-01

The promoter fragment described in this study can be employed for strong transgene expression under both biotic and abiotic stress conditions. Plant-infecting Caulimoviruses have evolved multiple regulatory mechanisms to address various environmental stimuli during the course of evolution. One such mechanism involves the retention of discrete stress responsive cis-elements which are required for their survival and host-specificity. Here we describe the characterization of a novel Caulimoviral promoter isolated from Horseradish Latent Virus (HRLV) and its regulation by multiple stress responsive Transcription factors (TFs) namely DREB1, AREB1 and TGA1a. The activity of full length transcript (Flt-) promoter from HRLV (- 677 to + 283) was investigated in both transient and transgenic assays where we identified H12 (- 427 to + 73) as the highest expressing fragment having ~ 2.5-fold stronger activity than the CaMV35S promoter. The H12 promoter was highly active and near-constitutive in the vegetative and reproductive parts of both Tobacco and Arabidopsis transgenic plants. Interestingly, H12 contains a distinct cluster of cis-elements like dehydration-responsive element (DRE-core; GCCGAC), an ABA-responsive element (ABRE; ACGTGTC) and as-1 element (TGACG) which are known to be induced by cold, drought and pathogen/SA respectively. The specific binding of DREB1, AREB1 and TGA1a to DRE, ABRE and as-1 elements respectively were confirmed by the gel-binding assays using H12 promoter-specific probes. Detailed mutational analysis of the H12 promoter suggested that the presence of DRE-core and as-1 element was indispensable for its activity which was further confirmed by the transactivation assays. Our studies imply that H12 could be a valuable genetic tool for regulated transgene expression under diverse environmental conditions.

Reduction in cab and psb A RNA transcripts in response to supplementary ultraviolet-B radiation.

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Jordan, B R; Chow, W S; Strid, A; Anderson, J M

1991-06-17

The cab and psb A RNA transcript levels have been determined in Pisum sativum leaves exposed to supplementary ultraviolet-B radiation. The nuclear-encoded cab transcripts are reduced to low levels after only 4 h of UV-B treatment and are undetectable after 3 days exposure. In contrast, the chloroplast-encoded psb A transcript levels, although reduced, are present for at least 3 days. After short periods of UV-B exposure (4 h or 8 h), followed by recovery under control conditions, cab RNA transcript levels had not recovered after 1 day, but were re-established to ca. 60% of control levels after 2 more days. Increased irradiance during exposure to UV-B reduced the effect upon cab transcripts, although the decrease was still substantial. These results indicate rapid changes in the cellular regulation of gene expression in response to supplementary UV-B and suggest increased UV-B radiation may have profound consequences for future productivity of sensitive crop species.

Coincidence in map positions between pathogen-induced defense-responsive genes and quantitative resistance loci in rice

Institute of Scientific and Technical Information of China (English)

熊敏; 王石平; 张启发

2002-01-01

Quantitative disease resistance conferred by quantitative trait loci (QTLs) is presumably of wider spectrum and durable. Forty-four cDNA clones, representing 44 defense-responsive genes, were fine mapped to 56 loci distributed on 9 of the 12 rice chromosomes. The locations of 32 loci detected by 27 cDNA clones were associated with previously identified resistance QTLs for different rice diseases, including blast, bacterial blight, sheath blight and yellow mottle virus. The loci detected by the same multiple-copy cDNA clones were frequently located on similar locations of different chromosomes. Some of the multiple loci detected by the same clones were all associated with resistance QTLs. These results suggest that some of the genes may be important components in regulation of defense responses against pathogen invasion and they may be the candidates for studying the mechanism of quantitative disease resistance in rice.

Early Lotus japonicus root transcriptomic responses to symbiotic and pathogenic fungal exudates

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Marco eGiovannetti

2015-06-01

Full Text Available The objective of this study is to evaluate Lotus japonicus transcriptomic responses to arbuscular mycorrhizal (AM germinated spore exudates (GSE, responsible for activating nuclear Ca2+ spiking in plant root epidermis. A microarray experiment was performed comparing gene expression in Lotus rootlets treated with GSE or water after 24 h and 48 h. The transcriptional pattern of selected genes that resulted to be regulated in the array was further evaluated upon different treatments and timings. In particular, Lotus rootlets were treated with: GSE from the pathogenic fungus Colletotrichum trifolii; short chitin oligomers (acknowledged AM fungal signals and long chitin oligomers (as activators of pathogenic responses. This experimental set up has revealed that AM GSE generates a strong transcriptomic response in Lotus roots with an extensive defense-related response after 24 hours and a subsequent downregulation after 48 hours. A similar subset of defense-related genes resulted to be upregulated also upon treatment with C. trifolii GSE, although with an opposite trend. Surprisingly, long chitin oligomers activated both defense-like and symbiosis-related genes. Among the genes regulated in the microarray, promoter-GUS assay showed that LjMATE1 activates in epidermal cells and root hairs.

Transcriptional repression of BODENLOS by HD-ZIP transcription factor HB5 in Arabidopsis thaliana.

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Smet, De I.; Lau, S.; Ehrismann, J.S.; Axiotis, I.; Kolb, M.; Kientz, M.; Weijers, D.; Jürgens, G.

2013-01-01

In Arabidopsis thaliana, the phytohormone auxin is an important patterning agent during embryogenesis and post-embryonic development, exerting effects through transcriptional regulation. The main determinants of the transcriptional auxin response machinery are AUXIN RESPONSE FACTOR (ARF)

Transcriptional effect of an Aframomum angustifolium seed extract on human cutaneous cells using low-density DNA chips.

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Bonnet-Duquennoy, Mathilde; Dumas, Marc; Debacker, Adeline; Lazou, Kristell; Talbourdet, Sylvie; Franchi, Jocelyne; Heusèle, Catherine; André, Patrice; Schnebert, Sylvianne; Bonté, Frédéric; Kurfürst, Robin

2007-06-01

Studying photoexposed and photoprotected skin biopsies from young and aged women, it has been found that a specific zone, composed of the basal layers of the epidermis, the dermal epidermal junction, and the superficial dermis, is major target of aging and reactive oxygen species. We showed that this zone is characterized by significant variations at a transcriptional and/or protein levels. Using low-density DNA chip technology, we evaluated the effect of a natural mixture of Aframomum angustifolium seed extract containing labdane diterpenoids on these aging markers. Expression profiles of normal human fibroblasts (NHF) were studied using a customized cDNA macroarray system containing genes covering dermal structure, inflammatory responses, and oxidative stress defense mechanisms. For normal human keratinocyte (NHK) investigations, we chose OLISA technique, a sensitive and quantitative method developed by BioMérieux specifically designed to investigate cell death, proliferation, epidermal structure, differentiation, and oxidative stress defense response. We observed that this extract strongly modified gene expression profiles of treated NHK, but weakly for NHF. This extract regulated antioxidant defenses, dermal-epidermal junction components, and epidermal renewal-related genes. Using low-density DNA chip technology, we identified new potential actions of A. angustifolium seed extract on skin aging.

Structurally distinct polycyclic aromatic hydrocarbons induce differential transcriptional responses in developing zebrafish

International Nuclear Information System (INIS)

Goodale, Britton C.; Tilton, Susan C.; Corvi, Margaret M.; Wilson, Glenn R.; Janszen, Derek B.; Anderson, Kim A.; Waters, Katrina M.; Tanguay, Robert L.

2013-01-01

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components of fossil fuels and by-products of combustion. These multi-ring chemicals differentially activate the aryl hydrocarbon receptor (AHR) in a structurally dependent manner, and induce toxicity via both AHR-dependent and -independent mechanisms. PAH exposure is known to induce developmental malformations in zebrafish embryos, and recent studies have shown cardiac toxicity induced by compounds with low AHR affinity. Unraveling the potentially diverse molecular mechanisms of PAH toxicity is essential for understanding the hazard posed by complex PAH mixtures present in the environment. We analyzed transcriptional responses to PAH exposure in zebrafish embryos exposed to benz(a)anthracene (BAA), dibenzothiophene (DBT) and pyrene (PYR) at concentrations that induced developmental malformations by 120 h post-fertilization (hpf). Whole genome microarray analysis of mRNA expression at 24 and 48 hpf identified genes that were differentially regulated over time and in response to the three PAH structures. PAH body burdens were analyzed at both time points using GC–MS, and demonstrated differences in PAH uptake into the embryos. This was important for discerning dose-related differences from those that represented unique molecular mechanisms. While BAA misregulated the least number of transcripts, it caused strong induction of cyp1a and other genes known to be downstream of the AHR, which were not induced by the other two PAHs. Analysis of functional roles of misregulated genes and their predicted regulatory transcription factors also distinguished the BAA response from regulatory networks disrupted by DBT and PYR exposure. These results indicate that systems approaches can be used to classify the toxicity of PAHs based on the networks perturbed following exposure, and may provide a path for unraveling the toxicity of complex PAH mixtures. - Highlights: • Defined global mRNA expression

Roles of Arabidopsis WRKY3 and WRKY4 Transcription Factors in Plant Responses to Pathogens

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Fan Baofang

2008-06-01

Full Text Available Abstract Background Plant WRKY DNA-binding transcription factors are involved in plant responses to biotic and abiotic responses. It has been previously shown that Arabidopsis WRKY3 and WRKY4, which encode two structurally similar WRKY transcription factors, are induced by pathogen infection and salicylic acid (SA. However, the role of the two WRKY transcription factors in plant disease resistance has not been directly analyzed. Results Both WRKY3 and WRKY4 are nuclear-localized and specifically recognize the TTGACC W-box sequences in vitro. Expression of WRKY3 and WRKY4 was induced rapidly by stress conditions generated by liquid infiltration or spraying. Stress-induced expression of WRKY4 was further elevated by pathogen infection and SA treatment. To determine directly their role in plant disease resistance, we have isolated T-DNA insertion mutants and generated transgenic overexpression lines for WRKY3 and WRKY4. Both the loss-of-function mutants and transgenic overexpression lines were examined for responses to the biotrophic bacterial pathogen Pseudomonas syringae and the necrotrophic fungal pathogen Botrytis cinerea. The wrky3 and wrky4 single and double mutants exhibited more severe disease symptoms and support higher fungal growth than wild-type plants after Botrytis infection. Although disruption of WRKY3 and WRKY4 did not have a major effect on plant response to P. syringae, overexpression of WRKY4 greatly enhanced plant susceptibility to the bacterial pathogen and suppressed pathogen-induced PR1 gene expression. Conclusion The nuclear localization and sequence-specific DNA-binding activity support that WRKY3 and WRKY4 function as transcription factors. Functional analysis based on T-DNA insertion mutants and transgenic overexpression lines indicates that WRKY3 and WRKY4 have a positive role in plant resistance to necrotrophic pathogens and WRKY4 has a negative effect on plant resistance to biotrophic pathogens.

Co-infection of Sweet Orange with Severe and Mild Strains of Citrus tristeza virus Is Overwhelmingly Dominated by the Severe Strain on Both the Transcriptional and Biological Levels

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Shimin Fu

2017-08-01

Full Text Available Citrus tristeza is one of the most destructive citrus diseases and is caused by the phloem-restricted Closterovirus, Citrus tristeza virus. Mild strain CTV-B2 does not cause obvious symptoms on indicators whereas severe strain CTV-B6 causes symptoms, including stem pitting, cupping, yellowing, and stiffening of leaves, and vein corking. Our laboratory has previously characterized changes in transcription in sweet orange separately infected with CTV-B2 and CTV-B6. In the present study, transcriptome analysis of Citrus sinensis in response to double infection by CTV-B2 and CTV-B6 was carried out. Four hundred and eleven transcripts were up-regulated and 356 transcripts were down-regulated prior to the onset of symptoms. Repressed genes were overwhelmingly associated with photosynthesis, and carbon and nucleic acid metabolism. Expression of genes related to the glycolytic, oxidative pentose phosphate (OPP, tricarboxylic acid cycle (TCA pathways, tetrapyrrole synthesis, redox homeostasis, nucleotide metabolism, protein synthesis and post translational protein modification and folding, and cell organization were all reduced. Ribosomal composition was also greatly altered in response to infection by CTV-B2/CTV-B6. Genes that were induced were related to cell wall structure, secondary and hormone metabolism, responses to biotic stress, regulation of transcription, signaling, and secondary metabolism. Transport systems dedicated to metal ions were especially disturbed and ZIPs (Zinc Transporter Precursors showed different expression patterns in response to co-infection by CTV-B2/CTV-B6 and single infection by CTV-B2. Host plants experienced root decline that may have contributed to Zn, Fe, and other nutrient deficiencies. Though defense responses, such as, strengthening of the cell wall, alteration of hormone metabolism, secondary metabolites, and signaling pathways, were activated, these defense responses did not suppress the spread of the pathogens

How Human Amygdala and Bed Nucleus of the Stria Terminalis May Drive Distinct Defensive Responses.

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Klumpers, Floris; Kroes, Marijn C W; Baas, Johanna M P; Fernández, Guillén

2017-10-04

The ability to adaptively regulate responses to the proximity of potential danger is critical to survival and imbalance in this system may contribute to psychopathology. The bed nucleus of the stria terminalis (BNST) is implicated in defensive responding during uncertain threat anticipation whereas the amygdala may drive responding upon more acute danger. This functional dissociation between the BNST and amygdala is however controversial, and human evidence scarce. Here we used data from two independent functional magnetic resonance imaging studies [ n = 108 males and n = 70 (45 females)] to probe how coordination between the BNST and amygdala may regulate responses during shock anticipation and actual shock confrontation. In a subset of participants from Sample 2 ( n = 48) we demonstrate that anticipation and confrontation evoke bradycardic and tachycardic responses, respectively. Further, we show that in each sample when going from shock anticipation to the moment of shock confrontation neural activity shifted from a region anatomically consistent with the BNST toward the amygdala. Comparisons of functional connectivity during threat processing showed overlapping yet also consistently divergent functional connectivity profiles for the BNST and amygdala. Finally, childhood maltreatment levels predicted amygdala, but not BNST, hyperactivity during shock anticipation. Our results support an evolutionary conserved, defensive distance-dependent dynamic balance between BNST and amygdala activity. Shifts in this balance may enable shifts in defensive reactions via the demonstrated differential functional connectivity. Our results indicate that early life stress may tip the neural balance toward acute threat responding and via that route predispose for affective disorder. SIGNIFICANCE STATEMENT Previously proposed differential contributions of the BNST and amygdala to fear and anxiety have been recently debated. Despite the significance of understanding their

Vibrio elicits targeted transcriptional responses from copepod hosts.

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Almada, Amalia A; Tarrant, Ann M

2016-06-01

Copepods are abundant crustaceans that harbor diverse bacterial communities, yet the nature of their interactions with microbiota are poorly understood. Here, we report that Vibrio elicits targeted transcriptional responses in the estuarine copepod Eurytemora affinis We pre-treated E. affinis with an antibiotic cocktail and exposed them to either a zooplankton specialist (Vibrio sp. F10 9ZB36) or a free-living species (Vibrio ordalii 12B09) for 24 h. We then identified via RNA-Seq a total of 78 genes that were differentially expressed following Vibrio exposure, including homologs of C-type lectins, chitin-binding proteins and saposins. The response differed between the two Vibrio treatments, with the greatest changes elicited upon inoculation with V. sp. F10 We suggest that these differentially regulated genes play important roles in cuticle integrity, the innate immune response, and general stress response, and that their expression may enable E. affinis to recognize and regulate symbiotic vibrios. We further report that V. sp. F10 culturability is specifically altered upon colonization of E. affinis These findings suggest that rather than acting as passive environmental vectors, copepods discriminately interact with vibrios, which may ultimately impact the abundance and activity of copepod-associated bacteria. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Development of novel metabolite-responsive transcription factors via transposon-mediated protein fusion.

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Younger, Andrew K D; Su, Peter Y; Shepard, Andrea J; Udani, Shreya V; Cybulski, Thaddeus R; Tyo, Keith E J; Leonard, Joshua N

2018-02-01

Naturally evolved metabolite-responsive biosensors enable applications in metabolic engineering, ranging from screening large genetic libraries to dynamically regulating biosynthetic pathways. However, there are many metabolites for which a natural biosensor does not exist. To address this need, we developed a general method for converting metabolite-binding proteins into metabolite-responsive transcription factors-Biosensor Engineering by Random Domain Insertion (BERDI). This approach takes advantage of an in vitro transposon insertion reaction to generate all possible insertions of a DNA-binding domain into a metabolite-binding protein, followed by fluorescence activated cell sorting to isolate functional biosensors. To develop and evaluate the BERDI method, we generated a library of candidate biosensors in which a zinc finger DNA-binding domain was inserted into maltose binding protein, which served as a model well-studied metabolite-binding protein. Library diversity was characterized by several methods, a selection scheme was deployed, and ultimately several distinct and functional maltose-responsive transcriptional biosensors were identified. We hypothesize that the BERDI method comprises a generalizable strategy that may ultimately be applied to convert a wide range of metabolite-binding proteins into novel biosensors for applications in metabolic engineering and synthetic biology. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Different gene-specific mechanisms determine the 'revised-response' memory transcription patterns of a subset of A. thaliana dehydration stress responding genes.

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Liu, Ning; Ding, Yong; Fromm, Michael; Avramova, Zoya

2014-05-01

Plants that have experienced several exposures to dehydration stress show increased resistance to future exposures by producing faster and/or stronger reactions, while many dehydration stress responding genes in Arabidopsis thaliana super-induce their transcription as a 'memory' from the previous encounter. A previously unknown, rather unusual, memory response pattern is displayed by a subset of the dehydration stress response genes. Despite robustly responding to a first stress, these genes return to their initial, pre-stressed, transcript levels during the watered recovery; surprisingly, they do not respond further to subsequent stresses of similar magnitude and duration. This transcriptional behavior defines the 'revised-response' memory genes. Here, we investigate the molecular mechanisms regulating this transcription memory behavior. Potential roles of abscisic acid (ABA), of transcription factors (TFs) from the ABA signaling pathways (ABF2/3/4 and MYC2), and of histone modifications (H3K4me3 and H3K27me3) as factors in the revised-response transcription memory patterns are elucidated. We identify the TF MYC2 as the critical component for the memory behavior of a specific subset of MYC2-dependent genes. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Potential roles of WRKY transcription factors in resistance to Aspergillus flavus colonization of immature maize kernels

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Resistance to Aspergillus flavus by maize (Zea mays L.) is mediated by several defense proteins; however the mechanism regulating the expression of these defenses is poorly understood. This study examined the potential roles of six maize WRKY transcription factors, ZmWRKY19, ZmWRKY21, ZmWRKY53, ZmW...

Epigenetic silencing of host cell defense genes enhances intracellular survival of the rickettsial pathogen Anaplasma phagocytophilum.

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Jose C Garcia-Garcia

2009-06-01

Full Text Available Intracellular bacteria have evolved mechanisms that promote survival within hostile host environments, often resulting in functional dysregulation and disease. Using the Anaplasma phagocytophilum-infected granulocyte model, we establish a link between host chromatin modifications, defense gene transcription and intracellular bacterial infection. Infection of THP-1 cells with A. phagocytophilum led to silencing of host defense gene expression. Histone deacetylase 1 (HDAC1 expression, activity and binding to the defense gene promoters significantly increased during infection, which resulted in decreased histone H3 acetylation in infected cells. HDAC1 overexpression enhanced infection, whereas pharmacologic and siRNA HDAC1 inhibition significantly decreased bacterial load. HDAC2 does not seem to be involved, since HDAC2 silencing by siRNA had no effect on A. phagocytophilum intracellular propagation. These data indicate that HDAC up-regulation and epigenetic silencing of host cell defense genes is required for A. phagocytophilum infection. Bacterial epigenetic regulation of host cell gene transcription could be a general mechanism that enhances intracellular pathogen survival while altering cell function and promoting disease.

ORA EST : functional analysis of jasmonate-responsive AP2/ERF-domain transcription factors in Arabidopsis thaliana

NARCIS (Netherlands)

Pré, Martial

2006-01-01

Plants defend themselves against stress, including pathogen or herbivore attack, via biosynthesis of defense proteins and of protective compounds called secondary metabolites. Stress induces these responses via a complex signal transduction network with jasmonic acid (JA) and related compounds as

The metal-responsive transcription factor-1 contributes to HIF-1 activation during hypoxic stress

International Nuclear Information System (INIS)

Murphy, Brian J.; Sato, Barbara G.; Dalton, Timothy P.; Laderoute, Keith R.

2005-01-01

Hypoxia-inducible factor-1 (HIF-1), the major transcriptional regulator of the mammalian cellular response to low oxygen (hypoxia), is embedded within a complex network of signaling pathways. We have been investigating the importance of another stress-responsive transcription factor, MTF-1, for the adaptation of cells to hypoxia. This article reports that MTF-1 plays a central role in hypoxic cells by contributing to HIF-1 activity. Loss of MTF-1 in transformed Mtf1 null mouse embryonic fibroblasts (MEFs) results in an attenuation of nuclear HIF-1α protein accumulation, HIF-1 transcriptional activity, and expression of an established HIF-1 target gene, glucose transporter-1 (Glut1). Mtf1 null (Mtf1 KO) MEFs also have constitutively higher levels of both glutathione (GSH) and the rate-limiting enzyme involved in GSH synthesis-glutamate cysteine ligase catalytic subunit-than wild type cells. The altered cellular redox state arising from increased GSH may perturb oxygen-sensing mechanisms in hypoxic Mtf1 KO cells and decrease the accumulation of HIF-1α protein. Together, these novel findings define a role for MTF-1 in the regulation of HIF-1 activity

Transcriptional Programs Controlling Perinatal Lung Maturation

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Xu, Yan; Wang, Yanhua; Besnard, Valérie; Ikegami, Machiko; Wert, Susan E.; Heffner, Caleb; Murray, Stephen A.; Donahue, Leah Rae; Whitsett, Jeffrey A.

2012-01-01

The timing of lung maturation is controlled precisely by complex genetic and cellular programs. Lung immaturity following preterm birth frequently results in Respiratory Distress Syndrome (RDS) and Broncho-Pulmonary Dysplasia (BPD), which are leading causes of mortality and morbidity in preterm infants. Mechanisms synchronizing gestational length and lung maturation remain to be elucidated. In this study, we designed a genome-wide mRNA expression time-course study from E15.5 to Postnatal Day 0 (PN0) using lung RNAs from C57BL/6J (B6) and A/J mice that differ in gestational length by ∼30 hr (B6controlling lung maturation. We identified both temporal and strain dependent gene expression patterns during lung maturation. For time dependent changes, cell adhesion, vasculature development, and lipid metabolism/transport were major bioprocesses induced during the saccular stage of lung development at E16.5–E17.5. CEBPA, PPARG, VEGFA, CAV1 and CDH1 were found to be key signaling and transcriptional regulators of these processes. Innate defense/immune responses were induced at later gestational ages (E18.5–20.5), STAT1, AP1, and EGFR being important regulators of these responses. Expression of RNAs associated with the cell cycle and chromatin assembly was repressed during prenatal lung maturation and was regulated by FOXM1, PLK1, chromobox, and high mobility group families of transcription factors. Strain dependent lung mRNA expression differences peaked at E18.5. At this time, mRNAs regulating surfactant and innate immunity were more abundantly expressed in lungs of B6 (short gestation) than in A/J (long gestation) mice, while expression of genes involved in chromatin assembly and histone modification were expressed at lower levels in B6 than in A/J mice. The present study systemically mapped key regulators, bioprocesses, and transcriptional networks controlling lung maturation, providing the basis for new therapeutic strategies to enhance lung function in preterm

Identification of the G13 (cAMP-response-element-binding protein-related protein) gene product related to activating transcription factor 6 as a transcriptional activator of the mammalian unfolded protein response.

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Haze, K; Okada, T; Yoshida, H; Yanagi, H; Yura, T; Negishi, M; Mori, K

2001-04-01

Eukaryotic cells control the levels of molecular chaperones and folding enzymes in the endoplasmic reticulum (ER) by a transcriptional induction process termed the unfolded protein response (UPR). The mammalian UPR is mediated by the cis-acting ER stress response element consisting of 19 nt (CCAATN(9)CCACG), the CCACG part of which is considered to provide specificity. We recently identified the basic leucine zipper (bZIP) protein ATF6 as a mammalian UPR-specific transcription factor; ATF6 is activated by ER stress-induced proteolysis and binds directly to CCACG. Here we report that eukaryotic cells express another bZIP protein closely related to ATF6 in both structure and function. This protein encoded by the G13 (cAMP response element binding protein-related protein) gene is constitutively synthesized as a type II transmembrane glycoprotein anchored in the ER membrane and processed into a soluble form upon ER stress as occurs with ATF6. The proteolytic processing of ATF6 and the G13 gene product is accompanied by their relocation from the ER to the nucleus; their basic regions seem to function as a nuclear localization signal. Overexpression of the soluble form of the G13 product constitutively activates the UPR, whereas overexpression of a mutant lacking the activation domain exhibits a strong dominant-negative effect. Furthermore, the soluble forms of ATF6 and the G13 gene product are unable to bind to several point mutants of the cis-acting ER stress response element in vitro that hardly respond to ER stress in vivo. We thus concluded that the two related bZIP proteins are crucial transcriptional regulators of the mammalian UPR, and propose calling the ATF6 gene product ATF6alpha and the G13 gene product ATF6beta.

Functions and Application of the AP2/ERF Transcription Factor Family in Crop Improvement

Institute of Scientific and Technical Information of China (English)

Zhao-Shi Xu; Ming Chen; Lian-Cheng Li; You-Zhi Ma

2011-01-01

Plants have acquired sophisticated stress response systems to adapt to changing environments. It is important to understand plants' stress response mechanisms in the effort to improve crop productivity under stressful conditions. The AP2/ERF transcription factors are known to regulate diverse processes of plant development and stress responses.In this study, the molecular characteristics and biological functions of AP2/ERFs in a variety of plant species were analyzed. AP2/ERFs,especially those in DREB and ERF subfamilies, are ideal candidates for crop improvement because their overexpression enhances tolerances to drought, salt, freezing, as well as resistances to multiple diseases in the transgenic plants. The comprehensive analysis of physiological functions is useful in elucidating the biological roles of AP2/ERF family genes in gene interaction, pathway regulation, and defense response under stress environments, which should provide new opportunities for the crop tolerance engineering.

Thiamine primed defense provides reliable alternative to systemic fungicide carbendazim against sheath blight disease in rice (Oryza sativa L.).

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Bahuguna, Rajeev Nayan; Joshi, Rohit; Shukla, Alok; Pandey, Mayank; Kumar, J

2012-08-01

A novel pathogen defense strategy by thiamine priming was evaluated for its efficacy against sheath blight pathogen, Rhizoctonia solani AG-1A, of rice and compared with that of systemic fungicide, carbendazim (BCM). Seeds of semidwarf, high yielding, basmati rice variety Vasumati were treated with thiamine (50 mM) and BCM (4 mM). The pot cultured plants were challenge inoculated with R. solani after 40 days of sowing and effect of thiamine and BCM on rice growth and yield traits was examined. Higher hydrogen peroxide content, total phenolics accumulation, phenylalanine ammonia lyase (PAL) activity and superoxide dismutase (SOD) activity under thiamine treatment displayed elevated level of systemic resistance, which was further augmented under challenging pathogen infection. High transcript level of phenylalanine ammonia lyase (PAL) and manganese superoxide dismutase (MnSOD) validated mode of thiamine primed defense. Though minimum disease severity was observed under BCM treatment, thiamine produced comparable results, with 18.12 per cent lower efficacy. Along with fortifying defense components and minor influence on photosynthetic pigments and nitrate reductase (NR) activity, thiamine treatment significantly reduced pathogen-induced loss in photosynthesis, stomatal conductance, chlorophyll fluorescence, NR activity and NR transcript level. Physiological traits affected under pathogen infection were found signatory for characterizing plant's response under disease and were detectable at early stage of infection. These findings provide a novel paradigm for developing alternative, environmentally safe strategies to control plant diseases. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Microbial phylogeny determines transcriptional response of resistome to dynamic composting processes

OpenAIRE

Wang, Cheng; Dong, Da; Strong, P. J.; Zhu, Weijing; Ma, Zhuang; Qin, Yong; Wu, Weixiang

2017-01-01

Background Animal manure is a reservoir of antibiotic resistance genes (ARGs) that pose a potential health risk globally, especially for resistance to the antibiotics commonly used in livestock production (such as tetracycline, sulfonamide, and fluoroquinolone). Currently, the effects of biological treatment (composting) on the transcriptional response of manure ARGs and their microbial hosts are not well characterized. Composting is a dynamic process that consists of four distinct phases tha...

Arabidopsis transcriptional responses differentiating closely related chemicals (herbicides) and cross-species extrapolation to Brassica

Science.gov (United States)

Using whole genome Affymetrix ATH1 GeneChips we characterized the transcriptional response of Arabidopsis thaliana Columbia 24 hours after treatment with five different herbicides. Four of them (chloransulam, imazapyr, primisulfuron, sulfometuron) inhibit acetolactate synthase (A...

Novel positive regulatory role for the SPL6 transcription factor in the N TIR-NB-LRR receptor-mediated plant innate immunity.

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Meenu S Padmanabhan

2013-03-01

Full Text Available Following the recognition of pathogen-encoded effectors, plant TIR-NB-LRR immune receptors induce defense signaling by a largely unknown mechanism. We identify a novel and conserved role for the SQUAMOSA PROMOTER BINDING PROTEIN (SBP-domain transcription factor SPL6 in enabling the activation of the defense transcriptome following its association with a nuclear-localized immune receptor. During an active immune response, the Nicotiana TIR-NB-LRR N immune receptor associates with NbSPL6 within distinct nuclear compartments. NbSPL6 is essential for the N-mediated resistance to Tobacco mosaic virus. Similarly, the presumed Arabidopsis ortholog AtSPL6 is required for the resistance mediated by the TIR-NB-LRR RPS4 against Pseudomonas syringae carrying the avrRps4 effector. Transcriptome analysis indicates that AtSPL6 positively regulates a subset of defense genes. A pathogen-activated nuclear-localized TIR-NB-LRR like N can therefore regulate defense genes through SPL6 in a mechanism analogous to the induction of MHC genes by mammalian immune receptors like CIITA and NLRC5.

Transcriptional and Proteomic Profiling of Aspergillus flavipes in Response to Sulfur Starvation.

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El-Sayed, Ashraf S A; Yassin, Marwa A; Ali, Gul Shad

2015-01-01

Aspergillus flavipes has received considerable interest due to its potential to produce therapeutic enzymes involved in sulfur amino acid metabolism. In natural habitats, A. flavipes survives under sulfur limitations by mobilizing endogenous and exogenous sulfur to operate diverse cellular processes. Sulfur limitation affects virulence and pathogenicity, and modulates proteome of sulfur assimilating enzymes of several fungi. However, there are no previous reports aimed at exploring effects of sulfur limitation on the regulation of A. flavipes sulfur metabolism enzymes at the transcriptional, post-transcriptional and proteomic levels. In this report, we show that sulfur limitation affects morphological and physiological responses of A. flavipes. Transcription and enzymatic activities of several key sulfur metabolism genes, ATP-sulfurylase, sulfite reductase, methionine permease, cysteine synthase, cystathionine β- and γ-lyase, glutathione reductase and glutathione peroxidase were increased under sulfur starvation conditions. A 50 kDa protein band was strongly induced by sulfur starvation, and the proteomic analyses of this protein band using LC-MS/MS revealed similarity to many proteins involved in the sulfur metabolism pathway.

Integrating nitric oxide into salicylic acid and jasmonic acid/ ethylene plant defense pathways.

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Mur, Luis A J; Prats, Elena; Pierre, Sandra; Hall, Michael A; Hebelstrup, Kim H

2013-01-01

Plant defense against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defense responses to be tailored to particular biotic stresses. Nitric oxide (NO) has emerged as a major signal influencing resistance mediated by both signaling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signaling along each pathway. NO will initiate SA biosynthesis and nitrosylate key cysteines on TGA-class transcription factors to aid in the initiation of SA-dependent gene expression. Against this, S-nitrosylation of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1) will promote the NPR1 oligomerization within the cytoplasm to reduce TGA activation. In JA biosynthesis, NO will initiate the expression of JA biosynthetic enzymes, presumably to over-come any antagonistic effects of SA on JA-mediated transcription. NO will also initiate the expression of ET biosynthetic genes but a suppressive role is also observed in the S-nitrosylation and inhibition of S-adenosylmethionine transferases which provides methyl groups for ET production. Based on these data a model for NO action is proposed but we have also highlighted the need to understand when and how inductive and suppressive steps are used.

A compendium of transcription factor and Transcriptionally active protein coding gene families in cowpea (Vigna unguiculata L.).

Science.gov (United States)

Misra, Vikram A; Wang, Yu; Timko, Michael P

2017-11-22

Cowpea (Vigna unguiculata (L.) Walp.) is the most important food and forage legume in the semi-arid tropics of sub-Saharan Africa where approximately 80% of worldwide production takes place primarily on low-input, subsistence farm sites. Among the major goals of cowpea breeding and improvement programs are the rapid manipulation of agronomic traits for seed size and quality and improved resistance to abiotic and biotic stresses to enhance productivity. Knowing the suite of transcription factors (TFs) and transcriptionally active proteins (TAPs) that control various critical plant cellular processes would contribute tremendously to these improvement aims. We used a computational approach that employed three different predictive pipelines to data mine the cowpea genome and identified over 4400 genes representing 136 different TF and TAP families. We compare the information content of cowpea to two evolutionarily close species common bean (Phaseolus vulgaris), and soybean (Glycine max) to gauge the relative informational content. Our data indicate that correcting for genome size cowpea has fewer TF and TAP genes than common bean (4408 / 5291) and soybean (4408/ 11,065). Members of the GROWTH-REGULATING FACTOR (GRF) and Auxin/indole-3-acetic acid (Aux/IAA) gene families appear to be over-represented in the genome relative to common bean and soybean, whereas members of the MADS (Minichromosome maintenance deficient 1 (MCM1), AGAMOUS, DEFICIENS, and serum response factor (SRF)) and C2C2-YABBY appear to be under-represented. Analysis of the AP2-EREBP APETALA2-Ethylene Responsive Element Binding Protein (AP2-EREBP), NAC (NAM (no apical meristem), ATAF1, 2 (Arabidopsis transcription activation factor), CUC (cup-shaped cotyledon)), and WRKY families, known to be important in defense signaling, revealed changes and phylogenetic rearrangements relative to common bean and soybean that suggest these groups may have evolved different functions. The availability of detailed

Identification and functional characterization of Rca1, a transcription factor involved in both antifungal susceptibility and host response in Candida albicans.

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Vandeputte, Patrick; Pradervand, Sylvain; Ischer, Françoise; Coste, Alix T; Ferrari, Sélène; Harshman, Keith; Sanglard, Dominique

2012-07-01

The identification of novel transcription factors associated with antifungal response may allow the discovery of fungus-specific targets for new therapeutic strategies. A collection of 241 Candida albicans transcriptional regulator mutants was screened for altered susceptibility to fluconazole, caspofungin, amphotericin B, and 5-fluorocytosine. Thirteen of these mutants not yet identified in terms of their role in antifungal response were further investigated, and the function of one of them, a mutant of orf19.6102 (RCA1), was characterized by transcriptome analysis. Strand-specific RNA sequencing and phenotypic tests assigned Rca1 as the regulator of hyphal formation through the cyclic AMP/protein kinase A (cAMP/PKA) signaling pathway and the transcription factor Efg1, but also probably through its interaction with a transcriptional repressor, most likely Tup1. The mechanisms responsible for the high level of resistance to caspofungin and fluconazole observed resulting from RCA1 deletion were investigated. From our observations, we propose that caspofungin resistance was the consequence of the deregulation of cell wall gene expression and that fluconazole resistance was linked to the modulation of the cAMP/PKA signaling pathway activity. In conclusion, our large-scale screening of a C. albicans transcription factor mutant collection allowed the identification of new effectors of the response to antifungals. The functional characterization of Rca1 assigned this transcription factor and its downstream targets as promising candidates for the development of new therapeutic strategies, as Rca1 influences host sensing, hyphal development, and antifungal response.

How salicylic acid takes transcriptional control over jasmonic acid signaling

NARCIS (Netherlands)

Caarls, Lotte|info:eu-repo/dai/nl/371746213; Pieterse, Corné M J|info:eu-repo/dai/nl/113115113; van Wees, Saskia C M|info:eu-repo/dai/nl/185445373

2015-01-01

Transcriptional regulation is a central process in plant immunity. The induction or repression of defense genes is orchestrated by signaling networks that are directed by plant hormones of which salicylic acid (SA) and jasmonic acid (JA) are the major players. Extensive cross-communication between

Tomato whole genome transcriptional response to Tetranychus urticae identifies divergence of spider mite-induced responses between tomato and Arabidopsis

NARCIS (Netherlands)

Martel, C.; Zhurov, V.; Navarro, M.; Martinez, M.; Cazaux, M.; Auger, P.; Migeon, A.; Santamaria, M.E.; Wybouw, N.; Diaz, I.; Van Leeuwen, T.; Navajas, M.; Grbic, M.; Grbic, V.

2015-01-01

The two-spotted spider mite Tetranychus urticae is one of the most significant mite pests in agriculture, feeding on more than 1,100 plant hosts, including model plants Arabidopsis thaliana and tomato, Solanum lycopersicum. Here, we describe timecourse tomato transcriptional responses to spider mite

Specificity of induced defenses, growth, and reproduction in lima bean (Phaseolus lunatus) in response to multispecies herbivory.

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Moreira, Xoaquín; Abdala-Roberts, Luis; Hernández-Cumplido, Johnattan; Cuny, Maximilien A C; Glauser, Gaetan; Benrey, Betty

2015-08-01

• Following herbivore attack, plants can either reduce damage by inducing defenses or mitigate herbivory effects through compensatory growth and reproduction. It is increasingly recognized that such induced defenses in plants are herbivore-specific, but less is known about the specificity of compensatory responses. Damage by multiple herbivores may also lead to synergistic effects on induction and plant fitness that differ from those caused by a single herbivore species. Although largely unstudied, the order of arrival and damage by different herbivore species might also play an important role in the impacts of herbivory on plants.• We investigated the specificity of defense induction (phenolics) and effects on growth (number of stems and leaves) and reproduction (number of seeds, seed mass, and germination rate) from feeding by two generalist leaf-chewing herbivores (Spodoptera eridania and Diabrotica balteata) on Phaseolus lunatus plants and evaluated whether simultaneous attack by both herbivores and their order of arrival influenced such dynamics.• Herbivory increased levels of leaf phenolics, but such effects were not herbivore-specific. In contrast, herbivory enhanced seed germination in an herbivore-specific manner. For all variables measured, the combined effects of both herbivore species did not differ from their individual effects. Finally, the order of herbivore arrival did not influence defense induction, plant growth, or seed number but did influence seed mass and germination.• Overall, this study highlights novel aspects of the specificity of plant responses induced by damage from multiple species of herbivores and uniquely associates such effects with plant lifetime fitness. © 2015 Botanical Society of America, Inc.

Nucleocytoplasmic shuttling of transcription factors

DEFF Research Database (Denmark)

Cartwright, P; Helin, K

2000-01-01

To elicit the transcriptional response following intra- or extracellular stimuli, the signals need to be transmitted to their site of action within the nucleus. The nucleocytoplasmic shuttling of transcription factors is a mechanism mediating this process. The activation and inactivation...... of the transcriptional response is essential for cells to progress through the cell cycle in a normal manner. The involvement of cytoplasmic and nuclear accessory molecules, and the general nuclear membrane transport components, are essential for this process. Although nuclear import and export for different...... transcription factor families are regulated by similar mechanisms, there are several differences that allow for the specific activation of each transcription factor. This review discusses the general import and export pathways found to be common amongst many different transcription factors, and highlights...

Defense response of susceptible and resistant Biomphalaria alexandrina snails against Schistosoma mansoni infection

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Iman F. Abou-El-Naga

2012-09-01

Full Text Available In Egypt, Biomphalaria alexandrina is the intermediate host for Schistosoma mansoni. The fates of Schistosoma miracidia in the snails varies between different species of Biomphalaria. The internal defense system is one of the factors that influence the susceptibility pattern of the snails. The interaction between Biomphalaria snails and S. mansoni needs to be identified for each species, and even between the members of the same species with different degrees of susceptibility. In the present study, the first generation of susceptible and resistant parents of B. alexandrina was examined histologically at the 30th day post exposure. The study includes the characterization of the immune response, as expressed by tissue reactions, of susceptible and resistant B. alexandrina snails against S. mansoni. It was also designed to determine the impact of the resistance increase in parent snails, on the mechanisms of interaction of their offspring against infection. The results showed that the infection rate of the offspring from the susceptible parents was 92%. No susceptible offspring was produced from the resistant parents. When the parents were of equal number of susceptible and resistant snails, they gave an offspring with an infection rate of 20%. Susceptible snails that had susceptible parents showed a higher degree of susceptibility than those that had both susceptible and resistant parents. A common feature of the resistant snails was the absence of any viable parasites. The tissue reactions of the resistant snails having only resistant parents occurred at the site of miracidial penetration. In resistant snails for which susceptible ones were included in their parents, the reactions occurred in the deep tissues. These results characterized the immune response of B. alexandrina snails against Schistosoma infection which was found to occur by two different mechanisms. One type of defense occurs in highly resistant snails, and employs direct

Sustained mitogen-activated protein kinase activation reprograms defense metabolism and phosphoprotein profile in Arabidopsis thaliana.

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Ines eLassowskat

2014-10-01

Full Text Available Mitogen-activated protein kinases (MAPKs target a variety of protein substrates to regulate cellular signaling processes in eukaryotes. In plants, the number of identified MAPK substrates that control plant defense responses is still limited. Here, we generated transgenic Arabidopsis thaliana plants with an inducible system to simulate in vivo activation of two stress-activated MAPKs, MPK3 and MPK6. Metabolome analysis revealed that this artificial MPK3/6 activation (without any exposure to pathogens or other stresses is sufficient to drive the production of major defense-related metabolites, including various camalexin, indole glucosinolate and agmatine derivatives. An accompanying (phosphoproteome analysis led to detection of hundreds of potential phosphoproteins downstream of MPK3/6 activation. Besides known MAPK substrates, many candidates on this list possess typical MAPK-targeted phosphosites and in many cases, the corresponding phosphopeptides were detected by mass spectrometry. Notably, several of these putative phosphoproteins have been reported to be associated with the biosynthesis of antimicrobial defense substances (e.g. WRKY transcription factors and proteins encoded by the genes from the PEN pathway required for penetration resistance to filamentous pathogens. Thus, this work provides an inventory of candidate phosphoproteins, including putative direct MAPK substrates, for future analysis of MAPK-mediated defense control. (Proteomics data are available with the identifier PXD001252 via ProteomeXchange, http://proteomecentral.proteomexchange.org.

The transcriptional regulatory network in the drought response and its crosstalk in abiotic stress responses including drought, cold and heat

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Kazuo eNakashima

2014-05-01

Full Text Available Drought negatively impacts plant growth and the productivity of crops around the world. Understanding the molecular mechanisms in the drought response is important for improvement of drought tolerance using molecular techniques. In plants, abscisic acid (ABA is accumulated under osmotic stress conditions caused by drought, and has a key role in stress responses and tolerance. Comprehensive molecular analyses have shown that ABA regulates the expression of many genes under osmotic stress conditions, and the ABA-responsive element (ABRE is the major cis-element for ABA-responsive gene expression. Transcription factors (TFs are master regulators of gene expression. ABRE-binding protein (AREB and ABRE-binding factor (ABF TFs control gene expression in an ABA-dependent manner. SNF1-related protein kinases 2, group A 2C-type protein phosphatases, and ABA receptors were shown to control the ABA signaling pathway. ABA-independent signaling pathways such as dehydration-responsive element-binding protein (DREB TFs and NAC TFs are also involved in stress responses including drought, heat and cold. Recent studies have suggested that there are interactions between the major ABA signaling pathway and other signaling factors in stress responses. The important roles of these transcription factors in crosstalk among abiotic stress responses will be discussed. Control of ABA or stress signaling factor expression can improve tolerance to environmental stresses. Recent studies using crops have shown that stress-specific overexpression of TFs improves drought tolerance and grain yield compared with controls in the field.

Proteomic Analysis of Differentially Accumulated Proteins in Cucumber (Cucumis sativus Fruit Peel in Response to Pre-storage Cold Acclimation

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Bin Wang

2018-01-01

Full Text Available Harvested fruits are still living organs and respond to environmental stimuli. Low temperature storage is effective in extending life of harvested fruit, but it may also cause chilling injury. Cold acclimation has been shown to induce chilling tolerance in plants, but what proteomic changes caused by cold acclimation are related to defense against chilling stress remains largely unclear. Here, 3 d of pre-storage cold acclimation (PsCA at 10°C reduced chilling injury and secondary disease severity in cucumber stored at 5°C by 51 and 94%, respectively, compared with the control which was directly stored at 5°C. Proteomic analysis of cucumber peel identified 21 significant differentially-accumulated proteins (SDAPs right after PsCA treatment and 23 after the following cold storage (PsCA+CS. These proteins are mainly related to stress response and defense (SRD, energy metabolism, protein metabolism, signal transduction, primary metabolism, and transcription. The SRD proteins, which made up 37% of the 21 and 47% of the 23, respectively, represented the largest class of SDAPs, and all but one protein were up-regulated, suggesting accumulation of proteins involved in defense response is central feature of proteomic profile changes brought about by PsCA. In fruit just after PsCA treatment, the identified SDAPs are related to responses to various stresses, including chilling, salt stress, dehydration, fungi, bacteria, insects, and DNA damage. However, after prolonged cold storage, the targeted proteins in acclimated fruit were narrowed down in scope to those involved in defense against chilling and pathogens. The change patterns at the transcription level of the majority of the up-regulated differentially-accumulated proteins were highly consistent with those at protein level. Taken all, the results suggest that the short-time cold acclimation initiated comprehensive defense responses in cucumber fruit at first, while the long term storage thereafter

Proteomic Analysis of Differentially Accumulated Proteins in Cucumber (Cucumis sativus) Fruit Peel in Response to Pre-storage Cold Acclimation.

Science.gov (United States)

Wang, Bin; Shen, Fei; Zhu, Shijiang

2017-01-01

Harvested fruits are still living organs and respond to environmental stimuli. Low temperature storage is effective in extending life of harvested fruit, but it may also cause chilling injury. Cold acclimation has been shown to induce chilling tolerance in plants, but what proteomic changes caused by cold acclimation are related to defense against chilling stress remains largely unclear. Here, 3 d of pre-storage cold acclimation (PsCA) at 10°C reduced chilling injury and secondary disease severity in cucumber stored at 5°C by 51 and 94%, respectively, compared with the control which was directly stored at 5°C. Proteomic analysis of cucumber peel identified 21 significant differentially-accumulated proteins (SDAPs) right after PsCA treatment and 23 after the following cold storage (PsCA+CS). These proteins are mainly related to stress response and defense (SRD), energy metabolism, protein metabolism, signal transduction, primary metabolism, and transcription. The SRD proteins, which made up 37% of the 21 and 47% of the 23, respectively, represented the largest class of SDAPs, and all but one protein were up-regulated, suggesting accumulation of proteins involved in defense response is central feature of proteomic profile changes brought about by PsCA. In fruit just after PsCA treatment, the identified SDAPs are related to responses to various stresses, including chilling, salt stress, dehydration, fungi, bacteria, insects, and DNA damage. However, after prolonged cold storage, the targeted proteins in acclimated fruit were narrowed down in scope to those involved in defense against chilling and pathogens. The change patterns at the transcription level of the majority of the up-regulated differentially-accumulated proteins were highly consistent with those at protein level. Taken all, the results suggest that the short-time cold acclimation initiated comprehensive defense responses in cucumber fruit at first, while the long term storage thereafter altered the

Dimer formation and transcription activation in the sporulation response regulator Spo0A.

Science.gov (United States)

Lewis, Richard J; Scott, David J; Brannigan, James A; Ladds, Joanne C; Cervin, Marguerite A; Spiegelman, George B; Hoggett, James G; Barák, Imrich; Wilkinson, Anthony J

2002-02-15

The response regulator Spo0A is the master control element in the initiation of sporulation in Bacillus subtilis. Like many other multi-domain response regulators, the latent activity of the effector, C-terminal domain is stimulated by phosphorylation on a conserved aspartic acid residue in the regulatory, N-terminal domain. If a threshold concentration of phosphorylated Spo0A is achieved, the transcription of genes required for sporulation is activated, whereas the genes encoding stationary phase sentinels are repressed, and sporulation proceeds. Despite detailed genetic, biochemical and structural characterisation, it is not understood how the phosphorylation signal in the receiver domain is transduced into DNA binding and transcription activation in the distal effector domain. An obstacle to our understanding of Spo0A function is the uncertainty concerning changes in quaternary structure that accompany phosphorylation. Here we have revisited this question and shown unequivocally that Spo0A forms dimers upon phosphorylation and that the subunit interactions in the dimer are mediated principally by the receiver domain. Purified dimers of two mutants of Spo0A, in which the phosphorylatable aspartic acid residue has been substituted, activate transcription from the spoIIG promoter in vitro, whereas monomers do not. This suggests that dimers represent the activated form of Spo0A. Copyright 2002 Elsevier Science Ltd.

ATM-mediated transcriptional and developmental responses to gamma-rays in Arabidopsis.

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Lilian Ricaud

Full Text Available ATM (Ataxia Telangiectasia Mutated is an essential checkpoint kinase that signals DNA double-strand breaks in eukaryotes. Its depletion causes meiotic and somatic defects in Arabidopsis and progressive motor impairment accompanied by several cell deficiencies in patients with ataxia telangiectasia (AT. To obtain a comprehensive view of the ATM pathway in plants, we performed a time-course analysis of seedling responses by combining confocal laser scanning microscopy studies of root development and genome-wide expression profiling of wild-type (WT and homozygous ATM-deficient mutants challenged with a dose of gamma-rays (IR that is sublethal for WT plants. Early morphologic defects in meristematic stem cells indicated that AtATM, an Arabidopsis homolog of the human ATM gene, is essential for maintaining the quiescent center and controlling the differentiation of initial cells after exposure to IR. Results of several microarray experiments performed with whole seedlings and roots up to 5 h post-IR were compiled in a single table, which was used to import gene information and extract gene sets. Sequence and function homology searches; import of spatio-temporal, cell cycling, and mutant-constitutive expression characteristics; and a simplified functional classification system were used to identify novel genes in all functional classes. The hundreds of radiomodulated genes identified were not a random collection, but belonged to functional pathways such as those of the cell cycle; cell death and repair; DNA replication, repair, and recombination; and transcription; translation; and signaling, indicating the strong cell reprogramming and double-strand break abrogation functions of ATM checkpoints. Accordingly, genes in all functional classes were either down or up-regulated concomitantly with downregulation of chromatin deacetylases or upregulation of acetylases and methylases, respectively. Determining the early transcriptional indicators of

The Longitudinal Transcriptional Response to Neoadjuvant Chemotherapy with and without Bevacizumab in Breast Cancer.

Science.gov (United States)

Silwal-Pandit, Laxmi; Nord, Silje; von der Lippe Gythfeldt, Hedda; Møller, Elen K; Fleischer, Thomas; Rødland, Einar; Krohn, Marit; Borgen, Elin; Garred, Øystein; Olsen, Tone; Vu, Phuong; Skjerven, Helle; Fangberget, Anne; Holmen, Marit M; Schlitchting, Ellen; Wille, Elisabeth; Nordberg Stokke, Mette; Moen Vollan, Hans Kristian; Kristensen, Vessela; Langerød, Anita; Lundgren, Steinar; Wist, Erik; Naume, Bjørn; Lingjærde, Ole Christian; Børresen-Dale, Anne-Lise; Engebraaten, Olav

2017-08-15

Purpose: Chemotherapy-induced alterations to gene expression are due to transcriptional reprogramming of tumor cells or subclonal adaptations to treatment. The effect on whole-transcriptome mRNA expression was investigated in a randomized phase II clinical trial to assess the effect of neoadjuvant chemotherapy with the addition of bevacizumab. Experimental Design: Tumor biopsies and whole-transcriptome mRNA profiles were obtained at three fixed time points with 66 patients in each arm. Altogether, 358 specimens from 132 patients were available, representing the transcriptional state before treatment start, at 12 weeks and after treatment (25 weeks). Pathologic complete response (pCR) in breast and axillary nodes was the primary endpoint. Results: pCR was observed in 15 patients (23%) receiving bevacizumab and chemotherapy and 8 patients (12%) receiving only chemotherapy. In the estrogen receptor-positive patients, 11 of 54 (20%) treated with bevacizumab and chemotherapy achieved pCR, while only 3 of 57 (5%) treated with chemotherapy reached pCR. In patients with estrogen receptor-positive tumors treated with combination therapy, an elevated immune activity was associated with good response. Proliferation was reduced after treatment in both treatment arms and most pronounced in the combination therapy arm, where the reduction in proliferation accelerated during treatment. Transcriptional alterations during therapy were subtype specific, and the effect of adding bevacizumab was most evident for luminal-B tumors. Conclusions: Clinical response and gene expression response differed between patients receiving combination therapy and chemotherapy alone. The results may guide identification of patients likely to benefit from antiangiogenic therapy. Clin Cancer Res; 23(16); 4662-70. ©2017 AACR . ©2017 American Association for Cancer Research.

The Complex Transcriptional Response of Acaryochloris marina to Different Oxygen Levels

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Miguel A. Hernández-Prieto

2017-02-01

Full Text Available Ancient oxygenic photosynthetic prokaryotes produced oxygen as a waste product, but existed for a long time under an oxygen-free (anoxic atmosphere, before an oxic atmosphere emerged. The change in oxygen levels in the atmosphere influenced the chemistry and structure of many enzymes that contained prosthetic groups that were inactivated by oxygen. In the genome of Acaryochloris marina, multiple gene copies exist for proteins that are normally encoded by a single gene copy in other cyanobacteria. Using high throughput RNA sequencing to profile transcriptome responses from cells grown under microoxic and hyperoxic conditions, we detected 8446 transcripts out of the 8462 annotated genes in the Cyanobase database. Two-thirds of the 50 most abundant transcripts are key proteins in photosynthesis. Microoxic conditions negatively affected the levels of expression of genes encoding photosynthetic complexes, with the exception of some subunits. In addition to the known regulation of the multiple copies of psbA, we detected a similar transcriptional pattern for psbJ and psbU, which might play a key role in the altered components of photosystem II. Furthermore, regulation of genes encoding proteins important for reactive oxygen species-scavenging is discussed at genome level, including, for the first time, specific small RNAs having possible regulatory roles under varying oxygen levels.

The Complex Transcriptional Response of Acaryochloris marina to Different Oxygen Levels

Science.gov (United States)

Hernández-Prieto, Miguel A.; Lin, Yuankui; Chen, Min

2016-01-01

Ancient oxygenic photosynthetic prokaryotes produced oxygen as a waste product, but existed for a long time under an oxygen-free (anoxic) atmosphere, before an oxic atmosphere emerged. The change in oxygen levels in the atmosphere influenced the chemistry and structure of many enzymes that contained prosthetic groups that were inactivated by oxygen. In the genome of Acaryochloris marina, multiple gene copies exist for proteins that are normally encoded by a single gene copy in other cyanobacteria. Using high throughput RNA sequencing to profile transcriptome responses from cells grown under microoxic and hyperoxic conditions, we detected 8446 transcripts out of the 8462 annotated genes in the Cyanobase database. Two-thirds of the 50 most abundant transcripts are key proteins in photosynthesis. Microoxic conditions negatively affected the levels of expression of genes encoding photosynthetic complexes, with the exception of some subunits. In addition to the known regulation of the multiple copies of psbA, we detected a similar transcriptional pattern for psbJ and psbU, which might play a key role in the altered components of photosystem II. Furthermore, regulation of genes encoding proteins important for reactive oxygen species-scavenging is discussed at genome level, including, for the first time, specific small RNAs having possible regulatory roles under varying oxygen levels. PMID:27974439

Defense Reutilization and Marketing Manual

Science.gov (United States)

1990-03-01

H -3 E Responsibilities of Defense Reutilization and Marketing Regions (D R M s...at Defense electronic products which produce radiation Reutilization and Marketing Offices, para- when energized. Among the principal radi- graph F... Sporting Equipment 7820 Games , Toys, and Wheeled Goods 7830 Recreational and Gymnastic Equipment 7910 Floor Polishers and Vacuum Cleaning Equipment

The small ethylene response factor ERF96 is involved in the regulation of the abscisic acid response in Arabidopsis

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Xiaoping eWang

2015-11-01

Full Text Available Ethylene regulates many aspects of plant growth and development including seed germination, leaf senescence, and fruit ripening, and of plant responses to environmental stimuli including both biotic and abiotic stresses. Ethylene Response Factors (ERFs are plant-specific transcription factors and are a subfamily of the AP2 (APETALA2/ERF transcription factor family. The function of many members in this large gene family remains largely unknown. ERF96, a member of the Group IX ERF family transcription factors, has recently been shown to be a transcriptional activator that is involved in plant defense response in Arabidopsis. Here we provide evidence that ERF96 is a positive regulator of abscisic acid (ABA responses. Bioinformatics analysis indicated that there are a total four small ERFs in Arabidopsis including ERF95, ERF96, ERF97 and ERF98, and that ERF96 forms a cluster with ERF95 and ERF97. By using quantitative RT-PCR, we found that ERF96 is expressed in all tissues and organs examined except roots, with relatively high expression in flowers and seeds. Results from the protoplast transfection assay results indicated that the EDLL motif-containing C-terminal domain is responsible for ERF96’s transcriptional activity. Although loss-of-function mutant of ERF96 was morphologically similar to wild type plants, transgenic plants overexpressing ERF96 had smaller rosette size and were delayed in flowering time. In ABA sensitivity assays, we found that ERF96 overexpression plants were hypersensitive to ABA in terms of ABA inhibition of seed germination, early seedling development and root elongation. Consistent with these observations, elevated transcript levels of some ABA-responsive genes including RD29A, ABI5, ABF3, ABF4, P5CS and COR15A were observed in the transgenic plants in the presence of ABA. However, in the absence of ABA treatment, the transcript levels of these ABA-responsive genes remained largely unchanged. Our experiments also showed

Transcription analysis of the porcine alveolar macrophage response to Mycoplasma hyopneumoniae.

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Li Bin

Full Text Available Mycoplasma hyopneumoniae is considered the major causative agent of porcine respiratory disease complex, occurs worldwide and causes major economic losses to the pig industry. To gain more insights into the pathogenesis of this organism, the high throughput cDNA microarray assays were employed to evaluate host responses of porcine alveolar macrophages to M. hyopneumoniae infection. A total of 1033 and 1235 differentially expressed genes were identified in porcine alveolar macrophages in responses to exposure to M. hyopneumoniae at 6 and 15 hours post infection, respectively. The differentially expressed genes were involved in many vital functional classes, including inflammatory response, immune response, apoptosis, cell adhesion, defense response, signal transduction, protein folding, protein ubiquitination and so on. The pathway analysis demonstrated that the most significant pathways were the chemokine signaling pathway, Toll-like receptor signaling pathway, RIG-I-like receptor signaling pathway, nucleotide-binding oligomerization domains (Nod-like receptor signaling pathway and apoptosis signaling pathway. The reliability of the data obtained from the microarray was verified by performing quantitative real-time PCR. The expression kinetics of chemokines was further analyzed. The present study is the first to document the response of porcine alveolar macrophages to M. hyopneumoniae infection. The data further developed our understanding of the molecular pathogenesis of M. hyopneumoniae.

Transcription analysis of the porcine alveolar macrophage response to Mycoplasma hyopneumoniae.

Science.gov (United States)

Bin, Li; Luping, Du; Bing, Sun; Zhengyu, Yu; Maojun, Liu; Zhixin, Feng; Yanna, Wei; Haiyan, Wang; Guoqing, Shao; Kongwang, He

2014-01-01

Mycoplasma hyopneumoniae is considered the major causative agent of porcine respiratory disease complex, occurs worldwide and causes major economic losses to the pig industry. To gain more insights into the pathogenesis of this organism, the high throughput cDNA microarray assays were employed to evaluate host responses of porcine alveolar macrophages to M. hyopneumoniae infection. A total of 1033 and 1235 differentially expressed genes were identified in porcine alveolar macrophages in responses to exposure to M. hyopneumoniae at 6 and 15 hours post infection, respectively. The differentially expressed genes were involved in many vital functional classes, including inflammatory response, immune response, apoptosis, cell adhesion, defense response, signal transduction, protein folding, protein ubiquitination and so on. The pathway analysis demonstrated that the most significant pathways were the chemokine signaling pathway, Toll-like receptor signaling pathway, RIG-I-like receptor signaling pathway, nucleotide-binding oligomerization domains (Nod)-like receptor signaling pathway and apoptosis signaling pathway. The reliability of the data obtained from the microarray was verified by performing quantitative real-time PCR. The expression kinetics of chemokines was further analyzed. The present study is the first to document the response of porcine alveolar macrophages to M. hyopneumoniae infection. The data further developed our understanding of the molecular pathogenesis of M. hyopneumoniae.

Cyclic AMP Receptor Protein Acts as a Transcription Regulator in Response to Stresses in Deinococcus radiodurans.

Directory of Open Access Journals (Sweden)

Su Yang

Full Text Available The cyclic AMP receptor protein family of transcription factors regulates various metabolic pathways in bacteria, and also play roles in response to environmental changes. Here, we identify four homologs of the CRP family in Deinococcus radiodurans, one of which tolerates extremely high levels of oxidative stress and DNA-damaging reagents. Transcriptional levels of CRP were increased under hydrogen peroxide (H2O2 treatment during the stationary growth phase, indicating that CRPs function in response to oxidative stress. By constructing all CRP single knockout mutants, we found that the dr0997 mutant showed the lowest tolerance toward H2O2, ultraviolet radiation, ionizing radiation, and mitomycin C, while the phenotypes of the dr2362, dr0834, and dr1646 mutants showed slight or no significant differences from those of the wild-type strain. Taking advantage of the conservation of the CRP-binding site in many bacteria, we found that transcription of 18 genes, including genes encoding chromosome-partitioning protein (dr0998, Lon proteases (dr0349 and dr1974, NADH-quinone oxidoreductase (dr1506, thiosulfate sulfurtransferase (dr2531, the DNA repair protein UvsE (dr1819, PprA (dra0346, and RecN (dr1447, are directly regulated by DR0997. Quantitative real-time polymerase chain reaction (qRT-PCR analyses showed that certain genes involved in anti-oxidative responses, DNA repair, and various cellular pathways are transcriptionally attenuated in the dr0997 mutant. Interestingly, DR0997 also regulate the transcriptional levels of all CRP genes in this bacterium. These data suggest that DR0997 contributes to the extreme stress resistance of D. radiodurans via its regulatory role in multiple cellular pathways, such as anti-oxidation and DNA repair pathways.

Defense through sensory inactivation: sea hare ink reduces sensory and motor responses of spiny lobsters to food odors.

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Love-Chezem, Tiffany; Aggio, Juan F; Derby, Charles D

2013-04-15

Antipredator defenses are ubiquitous and diverse. Ink secretion of sea hares (Aplysia) is an antipredator defense acting through the chemical senses of predators by different mechanisms. The most common mechanism is ink acting as an unpalatable repellent. Less common is ink secretion acting as a decoy (phagomimic) that misdirects predators' attacks. In this study, we tested another possible mechanism--sensory inactivation--in which ink inactivates the predator's reception of food odors associated with would-be prey. We tested this hypothesis using spiny lobsters, Panulirus argus, as model predators. Ink secretion is composed of two glandular products, one being opaline, a viscous substance containing concentrations of hundreds of millimolar of total free amino acids. Opaline sticks to antennules, mouthparts and other chemosensory appendages of lobsters, physically blocking access of food odors to the predator's chemosensors, or over-stimulating (short term) and adapting (long term) the chemosensors. We tested the sensory inactivation hypotheses by treating the antennules with opaline and mimics of its physical and/or chemical properties. We compared the effects of these treatments on responses to a food odor for chemoreceptor neurons in isolated antennules, as a measure of effect on chemosensory input, and for antennular motor responses of intact lobsters, as a measure of effect on chemically driven motor behavior. Our results indicate that opaline reduces the output of chemosensors by physically blocking reception of and response to food odors, and this has an impact on motor responses of lobsters. This is the first experimental demonstration of inactivation of peripheral sensors as an antipredatory defense.

Immune defense and host life history.

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Zuk, Marlene; Stoehr, Andrew M

2002-10-01

Recent interest has focused on immune response in an evolutionary context, with particular attention to disease resistance as a life-history trait, subject to trade-offs against other traits such as reproductive effort. Immune defense has several characteristics that complicate this approach, however; for example, because of the risk of autoimmunity, optimal immune defense is not necessarily maximum immune defense. Two important types of cost associated with immunity in the context of life history are resource costs, those related to the allocation of essential but limited resources, such as energy or nutrients, and option costs, those paid not in the currency of resources but in functional or structural components of the organism. Resource and option costs are likely to apply to different aspects of resistance. Recent investigations into possible trade-offs between reproductive effort, particularly sexual displays, and immunity have suggested interesting functional links between the two. Although all organisms balance the costs of immune defense against the requirements of reproduction, this balance works out differently for males than it does for females, creating sex differences in immune response that in turn are related to ecological factors such as the mating system. We conclude that immune response is indeed costly and that future work would do well to include invertebrates, which have sometimes been neglected in studies of the ecology of immune defense.

The role of antimicrobial peptides in animal defenses

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Hancock, Robert E. W.; Scott, Monisha G.

2000-08-01

It is becoming clear that the cationic antimicrobial peptides are an important component of the innate defenses of all species of life. Such peptides can be constitutively expressed or induced by bacteria or their products. The best peptides have good activities vs. a broad range of bacterial strains, including antibiotic-resistant isolates. They kill very rapidly, do not easily select resistant mutants, are synergistic with conventional antibiotics, other peptides, and lysozyme, and are able to kill bacteria in animal models. It is known that bacterial infections, especially when treated with antibiotics, can lead to the release of bacterial products such as lipopolysaccharide (LPS) and lipoteichoic acid, resulting in potentially lethal sepsis. In contrast to antibiotics, the peptides actually prevent cytokine induction by bacterial products in tissue culture and human blood, and they block the onset of sepsis in mouse models of endotoxemia. Consistent with this, transcriptional gene array experiments using a macrophage cell line demonstrated that a model peptide, CEMA, blocks the expression of many genes whose transcription was induced by LPS. The peptides do this in part by blocking LPS interaction with the serum protein LBP. In addition, CEMA itself has a direct effect on macrophage gene expression. Because cationic antimicrobial peptides are induced by LPS and are able to dampen the septic response of animal cells to LPS, we propose that, in addition to their role in direct and lysozyme-assisted killing of microbes, they have a role in feedback regulation of cytokine responses. We are currently developing variant peptides as therapeutics against antibiotic-resistant infections.

Corn defense responses to nitrogen availability and subsequent performance and feeding preferences of beet armyworm (Lepidoptera: Noctuidae).

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Ren, Li-Li; Hardy, Giles; Liu, Zhu-Dong; Wei, Wei; Dai, Hua-Guo

2013-06-01

Many studies have reported the effect of nitrogen (N) fertilization on plant constitutive defense responses; however, little is known about their effects on plant induced defense patterns and its consequence for insect herbivores. In our experiments, the effects of N availability on growth, nutritional quality (N content, protein/carbohydrate [P:C] ratio, modified gross energy [MGE]), and constitutive phenolics of corn, Zea mays L. were quantified. Moreover, the indirect effects of N fertilization on the beet armyworm, Spodoptera exigua Hübner through larval performance and feeding preference were examined. N fertilization increased plant growth, and depressed defense traits by increasing N content and the P:C ratio, as well as decreasing the constitutive concentration of phenolics. Subsequently, beet armyworm showed higher performance and preferentially fed on high-N corn because of its low defense traits. After beet armyworm feeding, high-N corn significantly deterred larval feeding, and had negative effects on the performance of beet armyworm through decreasing P:C ratio and increasing induced phenolics. On the contrary, there were no significant changes in P:C ratio and phenolics in low-N corn after feeding damage. Larval performance and preference were also not affected by induced compounds in low-N corn, which suggested that the expression of induced defense was dependent on N availability. The result indicates that N availability can exert a variety of bottom-up effect on plant defense patterns to influence insect population dynamics, and thereby may represent a source of variation in plant-insect interactions.

Dose-specific transcriptional responses in thyroid tissue in mice after 131I administration

International Nuclear Information System (INIS)

Rudqvist, Nils; Schüler, Emil; Parris, Toshima Z.; Langen, Britta; Helou, Khalil; Forssell-Aronsson, Eva

2015-01-01

Introduction: In the present investigation, microarray analysis was used to monitor transcriptional activity in thyroids in mice 24 h after 131 I exposure. The aims of this study were to 1) assess the transcriptional patterns associated with 131 I exposure in normal mouse thyroid tissue and 2) propose biomarkers for 131 I exposure of the thyroid. Methods: Adult BALB/c nude mice were i.v. injected with 13, 130 or 260 kBq of 131 I and killed 24 h after injection (absorbed dose to thyroid: 0.85, 8.5, or 17 Gy). Mock-treated mice were used as controls. Total RNA was extracted from thyroids and processed using the Illumina platform. Results: In total, 497, 546, and 90 transcripts were regulated (fold change ≥ 1.5) in the thyroid after 0.85, 8.5, and 17 Gy, respectively. These were involved in several biological functions, e.g. oxygen access, inflammation and immune response, and apoptosis/anti-apoptosis. Approximately 50% of the involved transcripts at each absorbed dose level were dose-specific, and 18 transcripts were commonly detected at all absorbed dose levels. The Agpat9, Plau, Prf1, and S100a8 gene expression displayed a monotone decrease in regulation with absorbed dose, and further studies need to be performed to evaluate if they may be useful as dose-related biomarkers for 131I exposure. Conclusion: Distinct and substantial differences in gene expression and affected biological functions were detected at the different absorbed dose levels. The transcriptional profiles were specific for the different absorbed dose levels. We propose that the Agpat9, Plau, Prf1, and S100a8 genes might be novel potential absorbed dose-related biomarkers to 131 I exposure of thyroid. Advances in knowledge: During the recent years, genomic techniques have been developed; however, they have not been fully utilized in nuclear medicine and radiation biology. We have used RNA microarrays to investigate genome-wide transcriptional regulations in thyroid tissue in mice after low

Role for β-catenin and HOX transcription factors in Caenorhabditis elegans and mammalian host epithelial-pathogen interactions

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Irazoqui, Javier E.; Ng, Aylwin; Xavier, Ramnik J.; Ausubel, Frederick M.

2008-01-01

We used the model nematode Caenorhabditis elegans infected with the human pathogen Staphylococcus aureus to identify components of epithelial immunity. Transcriptional profiling and reverse genetic analysis revealed that mutation of the C. elegans β-catenin homolog bar-1 or the downstream homeobox gene egl-5 results in a defective response and hypersensitivity to S. aureus infection. Epistasis analysis showed that bar-1 and egl-5 function in parallel to previously described C. elegans immune-response pathways. Overexpression of human homologs of egl-5 modulated NF-κB-dependent TLR2 signaling in epithelial cells. These data suggest that β-catenin and homeobox genes play an important and conserved role in innate immune defense. PMID:18981407

Role for beta-catenin and HOX transcription factors in Caenorhabditis elegans and mammalian host epithelial-pathogen interactions.

Science.gov (United States)

Irazoqui, Javier E; Ng, Aylwin; Xavier, Ramnik J; Ausubel, Frederick M

2008-11-11

We used the model nematode Caenorhabditis elegans infected with the human pathogen Staphylococcus aureus to identify components of epithelial immunity. Transcriptional profiling and reverse genetic analysis revealed that mutation of the C. elegans beta-catenin homolog bar-1 or the downstream homeobox gene egl-5 results in a defective response and hypersensitivity to S. aureus infection. Epistasis analysis showed that bar-1 and egl-5 function in parallel to previously described C. elegans immune-response pathways. Overexpression of human homologs of egl-5 modulated NF-kappaB-dependent TLR2 signaling in epithelial cells. These data suggest that beta-catenin and homeobox genes play an important and conserved role in innate immune defense.

Variation in the transcriptional response of threatened coral larvae to elevated temperatures.

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Polato, Nicholas R; Altman, Naomi S; Baums, Iliana B

2013-03-01

Coral populations have declined worldwide largely due to increased sea surface temperatures. Recovery of coral populations depends in part upon larval recruitment. Many corals reproduce during the warmest time of year when further increases in temperature can lead to low fertilization rates of eggs and high larval mortality. Microarray experiments were designed to capture and assess variability in the thermal stress responses of Acropora palmata larvae from Puerto Rico. Transcription profiles showed a striking acceleration of normal developmental gene expression patterns with increased temperature. The transcriptional response to heat suggested rapid depletion of larval energy stores via peroxisomal lipid oxidation and included key enzymes that indicated the activation of the glyoxylate cycle. High temperature also resulted in expression differences in key developmental signalling genes including the conserved WNT pathway that is critical for pattern formation and tissue differentiation in developing embryos. Expression of these and other important developmental and thermal stress genes such as ferritin, heat shock proteins, cytoskeletal components, cell adhesion and autophagy proteins also varied among larvae derived from different parent colonies. Disruption of normal developmental and metabolic processes will have negative impacts on larval survival and dispersal as temperatures rise. However, it appears that variation in larval response to high temperature remains despite the dramatic population declines. Further research is needed to determine whether this variation is heritable or attributable to maternal effects. © 2013 Blackwell Publishing Ltd.

Responses of human cells to ZnO nanoparticles: a gene transcription study†

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Moos, Philip J.; Olszewski, Kyle; Honeggar, Matthew; Cassidy, Pamela; Leachman, Sancy; Woessner, David; Cutler, N. Shane; Veranth, John M.

2013-01-01

The gene transcript profile responses to metal oxide nanoparticles was studied using human cell lines derived from the colon and skin tumors. Much of the research on nanoparticle toxicology has focused on models of inhalation and intact skin exposure, and effects of ingestion exposure and application to diseased skin are relatively unknown. Powders of nominally nanosized SiO2, TiO2, ZnO and Fe2O3 were chosen because these substances are widely used in consumer products. The four oxides were evaluated using colon-derived cell lines, RKO and CaCo-2, and ZnO and TiO2 were evaluated further using skin-derived cell lines HaCaT and SK Mel-28. ZnO induced the most notable gene transcription changes, even though this material was applied at the lowest concentration. Nano-sized and conventional ZnO induced similar responses suggesting common mechanisms of action. The results showed neither a non-specific response pattern common to all substances nor synergy of the particles with TNF-α cotreatment. The response to ZnO was not consistent with a pronounced proinflammatory signature, but involved changes in metal metabolism, chaperonin proteins, and protein folding genes. This response was observed in all cell lines when ZnO was in contact with the human cells. When the cells were exposed to soluble Zn, the genes involved in metal metabolism were induced but the genes involved in protein refoldling were unaffected. This provides some of the first data on the effects of commercial metal oxide nanoparticles on human colon-derived and skin-derived cells. PMID:21769377

Transcriptional Responses in the Hemiparasitic Plant Triphysaria versicolor to Host Plant Signals1[w

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Matvienko, Marta; Torres, Manuel J.; Yoder, John I.

2001-01-01

Parasitic plants in the Scrophulariaceae use chemicals released by host plant roots to signal developmental processes critical for heterotrophy. Haustoria, parasitic plant structures that attach to and invade host roots, develop on roots of the hemiparasitic plant Triphysaria versicolor within a few hours of exposure to either maize (Zea mays) root exudate or purified haustoria-inducing factors. We prepared a normalized, subtractive cDNA library enriched for transcripts differentially abundant in T. versicolor root tips treated with the allelopathic quinone 2,6-dimethoxybenzoquinone (DMBQ). Northern analyses estimated that about 10% of the cDNAs represent transcripts strongly up-regulated in roots exposed to DMBQ. Northern and reverse northern analyses demonstrated that most DMBQ-responsive messages were similarly up-regulated in T. versicolor roots exposed to maize root exudates. From the cDNA sequences we assembled a unigene set of 137 distinct transcripts and assigned functions by homology comparisons. Many of the proteins encoded by the transcripts are predicted to function in quinone detoxification, whereas others are more likely associated with haustorium development. The identification of genes transcriptionally regulated by haustorium-inducing factors provides a framework for dissecting genetic pathways recruited by parasitic plants during the transition to heterotrophic growth. PMID:11553755

Quadrennial Defense Review, National Defense Authorizatin Act for Fiscal Year 2000

National Research Council Canada - National Science Library

2002-01-01

Objectives of Overall JS QDR Effort Develop a QDR process that will shape defense policies Ensure the process is strategy-based, not budget-based Define a force structure responsive to the national...

Survival and interaction of Escherichia coli O104:H4 on Arabidopsis thaliana and lettuce (Lactuca sativa) in comparison to E. coli O157:H7: Influence of plant defense response and bacterial capsular polysaccharide.

Science.gov (United States)

Jang, Hyein; Matthews, Karl R

2018-06-01

Shiga toxin-producing Escherichia coli (STEC) has been associated with illnesses and outbreaks linked to fresh vegetables, prompting a growing public health concern. Most studies regarding interactions of STEC on fresh produce focused on E. coli O157:H7. Limited information is available about survival or fitness of E. coli O104:H4, non-O157 pathogen that was linked to one of the largest outbreaks of hemolytic uremic syndrome in 2011. In this study, survival of E. coli O104:H4 was evaluated on Arabidopsis thaliana plant and lettuce for 5 days compared with E. coli O157:H7, and expression of pathogenesis-realted gene (PR1; induction of plant defense response) was examined by reverse transcription quantitative PCR, and potential influence of capsular polysaccharide (CPS) on the bacterial fitness on plant was investigated. Populations of E. coli O104:H4 strains (RG1, C3493, and LpfA) on Arabidopsis and lettuce were significantly (P E. coli O157:H7 strains (7386 and sakai) at day 5 post-inoculation, indicating E. coli O104:H4 may have better survival ability on the plants. In addition, the E. coli O104:H4 strains produced significantly (P E. coli O157:H7 strains. RG1 strain (1.5-fold) initiated significantly (P E. coli O157:H7 strains 7386 (2.9-fold) and sakai (2.7-fold). Collectively, the results in this study suggests that different level of CPS production and plant defense response initiated by each STEC strain might influence the bacterial survival or persistence on plants. The present study provides better understanding of survival behavior of STEC, particularly E. coli O104:H4, using a model plant and vegetable under pre-harvest conditions with plant defense response. Copyright © 2018 Elsevier Ltd. All rights reserved.

Putative sugar transporters of the mustard leaf beetle Phaedon cochleariae: their phylogeny and role for nutrient supply in larval defensive glands.

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Magdalena Stock

Full Text Available BACKGROUND: Phytophagous insects have emerged successfully on the planet also because of the development of diverse and often astonishing defensive strategies against their enemies. The larvae of the mustard leaf beetle Phaedon cochleariae, for example, secrete deterrents from specialized defensive glands on their back. The secretion process involves ATP-binding cassette transporters. Therefore, sugar as one of the major energy sources to fuel the ATP synthesis for the cellular metabolism and transport processes, has to be present in the defensive glands. However, the role of sugar transporters for the production of defensive secretions was not addressed until now. RESULTS: To identify sugar transporters in P. cochleariae, a transcript catalogue was created by Illumina sequencing of cDNA libraries. A total of 68,667 transcripts were identified and 68 proteins were annotated as either members of the solute carrier 2 (SLC2 family or trehalose transporters. Phylogenetic analyses revealed an extension of the mammalian GLUT6/8 class in insects as well as one group of transporters exhibiting distinctive conserved motifs only present in the insect order Coleoptera. RNA-seq data of samples derived from the defensive glands revealed six transcripts encoding sugar transporters with more than 3,000 counts. Two of them are exclusively expressed in the glandular tissue. Reduction in secretions production was accomplished by silencing two of four selected transporters. RNA-seq experiments of transporter-silenced larvae showed the down-regulation of the silenced transporter but concurrently the up-regulation of other SLC2 transporters suggesting an adaptive system to maintain sugar homeostasis in the defensive glands. CONCLUSION: We provide the first comprehensive phylogenetic study of the SLC2 family in a phytophagous beetle species. RNAi and RNA-seq experiments underline the importance of SLC2 transporters in defensive glands to achieve a chemical defense

TCP Transcription Factors at the Interface between Environmental Challenges and the Plant's Growth Responses.

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Danisman, Selahattin

2016-01-01

Plants are sessile and as such their reactions to environmental challenges differ from those of mobile organisms. Many adaptions involve growth responses and hence, growth regulation is one of the most crucial biological processes for plant survival and fitness. The plant-specific TEOSINTE BRANCHED 1, CYCLOIDEA, PCF1 (TCP) transcription factor family is involved in plant development from cradle to grave, i.e., from seed germination throughout vegetative development until the formation of flowers and fruits. TCP transcription factors have an evolutionary conserved role as regulators in a variety of plant species, including orchids, tomatoes, peas, poplar, cotton, rice and the model plant Arabidopsis. Early TCP research focused on the regulatory functions of TCPs in the development of diverse organs via the cell cycle. Later research uncovered that TCP transcription factors are not static developmental regulators but crucial growth regulators that translate diverse endogenous and environmental signals into growth responses best fitted to ensure plant fitness and health. I will recapitulate the research on TCPs in this review focusing on two topics: the discovery of TCPs and the elucidation of their evolutionarily conserved roles across the plant kingdom, and the variety of signals, both endogenous (circadian clock, plant hormones) and environmental (pathogens, light, nutrients), TCPs respond to in the course of their developmental roles.

Defense responses in plants of Eucalyptus elicited by Streptomyces and challenged with Botrytis cinerea.

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Salla, Tamiris D; Astarita, Leandro V; Santarém, Eliane R

2016-04-01

Elicitation of E. grandis plants with Streptomyces PM9 reduced the gray-mold disease, through increasing the levels of enzymes directly related to the induction of plant defense responses, and accumulation of specific phenolic compounds. Members of Eucalyptus are economically important woody species, especially as a raw material in many industrial sectors. Species of this genus are susceptible to pathogens such as Botrytis cinerea (gray mold). Biological control of plant diseases using rhizobacteria is one alternative to reduce the use of pesticides and pathogen attack. This study evaluated the metabolic and phenotypic responses of Eucalyptus grandis and E. globulus plants treated with Streptomyces sp. PM9 and challenged with the pathogenic fungus B. cinerea. Metabolic responses were evaluated by assessing the activities of the enzymes polyphenol oxidase and peroxidase as well as the levels of phenolic compounds and flavonoids. The incidence and progression of the fungal disease in PM9-treated plants and challenged with B. cinerea were evaluated. Treatment with Streptomyces sp. PM9 and challenge with B. cinerea led to changes in the activities of polyphenol oxidase and peroxidase as well as in the levels of phenolic compounds in the plants at different time points. Alterations in enzymes of PM9-treated plants were related to early defense responses in E. grandis. Gallic and chlorogenic acids were on average more abundant, although caffeic acid, benzoic acid and catechin were induced at specific time points during the culture period. Treatment with Streptomyces sp. PM9 significantly delayed the establishment of gray mold in E. grandis plants. These results demonstrate the action of Streptomyces sp. PM9 in inducing plant responses against B. cinerea, making this organism a potential candidate for biological control in Eucalyptus.

The ABA-INSENSITIVE-4 (ABI4) transcription factor links redox, hormone and sugar signaling pathways.

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Foyer, Christine H; Kerchev, Pavel I; Hancock, Robert D

2012-02-01

The cellular reduction-oxidation (redox) hub processes information from metabolism and the environment and so regulates plant growth and defense through integration with the hormone signaling network. One key pathway of redox control involves interactions with ABSCISIC ACID (ABA). Accumulating evidence suggests that the ABA-INSENSITIVE-4 (ABI4) transcription factor plays a key role in transmitting information concerning the abundance of ascorbate and hence the ability of cells to buffer oxidative challenges. ABI4 is required for the ascorbate-dependent control of growth, a process that involves enhancement of salicylic acid (SA) signaling and inhibition of jasmonic acid (JA) signaling pathways. Low redox buffering capacity reinforces SA- JA- interactions through the mediation of ABA and ABI4 to fine-tune plant growth and defense in relation to metabolic cues and environmental challenges. Moreover, ABI4-mediated pathways of sugar sensitivity are also responsive to the abundance of ascorbate, providing evidence of overlap between redox and sugar signaling pathways.

The NAC transcription factor family in maritime pine (Pinus Pinaster): molecular regulation of two genes involved in stress responses.

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Pascual, Ma Belén; Cánovas, Francisco M; Ávila, Concepción

2015-10-24

NAC transcription factors comprise a large plant-specific gene family involved in the regulation of diverse biological processes. Despite the growing number of studies on NAC transcription factors in various species, little information is available about this family in conifers. The goal of this study was to identify the NAC transcription family in maritime pine (Pinus pinaster), to characterize ATAF-like genes in response to various stresses and to study their molecular regulation. We have isolated two maritime pine NAC genes and using a transient expression assay in N. benthamiana leaves estudied the promoter jasmonate response. In this study, we identified 37 NAC genes from maritime pine and classified them into six main subfamilies. The largest group includes 12 sequences corresponding to stress-related genes. Two of these NAC genes, PpNAC2 and PpNAC3, were isolated and their expression profiles were examined at various developmental stages and in response to various types of stress. The expression of both genes was strongly induced by methyl jasmonate (MeJA), mechanical wounding, and high salinity. The promoter regions of these genes were shown to contain cis-elements involved in the stress response and plant hormonal regulation, including E-boxes, which are commonly found in the promoters of genes that respond to jasmonate, and binding sites for bHLH proteins. Using a transient expression assay in N. benthamiana leaves, we found that the promoter of PpNAC3 was rapidly induced upon MeJA treatment, while this response disappeared in plants in which the transcription factor NbbHLH2 was silenced. Our results suggest that PpNAC2 and PpNAC3 encode stress-responsive NAC transcription factors involved in the jasmonate response in pine. Furthermore, these data also suggest that the jasmonate signaling pathway is conserved between angiosperms and gymnosperms. These findings may be useful for engineering stress tolerance in pine via biotechnological approaches.

Knockout of Arabidopsis accelerated-cell-death11 encoding a sphingosine transfer protein causes activation of programmed cell death and defense

DEFF Research Database (Denmark)

Brodersen, Peter; Petersen, Morten; Pike, Helen M

2002-01-01

by avirulent pathogens. Global transcriptional changes during programmed cell death (PCD) and defense activation in acd11 were monitored by cDNA microarray hybridization. The PCD and defense pathways activated in acd11 are salicylic acid (SA) dependent, but do not require intact jasmonic acid or ethylene...

Transcriptome-wide identification of bread wheat WRKY transcription factors in response to drought stress.

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Okay, Sezer; Derelli, Ebru; Unver, Turgay

2014-10-01

The WRKY superfamily of transcription factors was shown to be involved in biotic and abiotic stress responses in plants such as wheat (Triticum aestivum L.), one of the major crops largely cultivated and consumed all over the world. Drought is an important abiotic stress resulting in a considerable amount of loss in agronomical yield. Therefore, identification of drought responsive WRKY members in wheat has a profound significance. Here, a total of 160 TaWRKY proteins were characterized according to sequence similarity, motif varieties, and their phylogenetic relationships. The conserved sequences of the TaWRKYs were aligned and classified into three main groups and five subgroups. A novel motif in wheat, WRKYGQR, was identified. To putatively determine the drought responsive TaWRKY members, publicly available RNA-Seq data were analyzed for the first time in this study. Through in silico searches, 35 transcripts were detected having an identity to ten known TaWRKY genes. Furthermore, relative expression levels of TaWRKY16/TaWRKY16-A, TaWRKY17, TaWRKY19-C, TaWRKY24, TaWRKY59, TaWRKY61, and TaWRKY82 were measured in root and leaf tissues of drought-tolerant Sivas 111/33 and susceptible Atay 85 cultivars. All of the quantified TaWRKY transcripts were found to be up-regulated in root tissue of Sivas 111/33. Differential expression of TaWRKY16, TaWRKY24, TaWRKY59, TaWRKY61 and TaWRKY82 genes was discovered for the first time upon drought stress in wheat. These comprehensive analyses bestow a better understanding about the WRKY TFs in bread wheat under water deficit, and increased number of drought responsive WRKYs would contribute to the molecular breeding of tolerant wheat cultivars.

Systematic analysis of phloem-feeding insect-induced transcriptional reprogramming in Arabidopsis highlights common features and reveals distinct responses to specialist and generalist insects.

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Foyer, Christine H; Verrall, Susan R; Hancock, Robert D

2015-02-01

Phloem-feeding insects (PFIs), of which aphids are the largest group, are major agricultural pests causing extensive damage to crop plants. In contrast to chewing insects, the nature of the plant response to PFIs remains poorly characterized. Scrutiny of the literature concerning transcriptional responses of model and crop plant species to PFIs reveals surprisingly little consensus with respect to the transcripts showing altered abundance following infestation. Nevertheless, core features of the transcriptional response to PFIs can be defined in Arabidopsis thaliana. This comparison of the PFI-associated transcriptional response observed in A. thaliana infested by the generalists Myzus persicae and Bemisia tabaci with the specialist Brevicoryne brassicae highlights the importance of calcium-dependent and receptor kinase-associated signalling. We discuss these findings within the context of the complex cross-talk between the different hormones regulating basal immune response mechanisms in plants. We identify PFI-responsive genes, highlighting the importance of cell wall-associated kinases in plant-PFI interactions, as well as the significant role of kinases containing the domain of unknown function 26. A common feature of plant-PFI interaction is enhanced abundance of transcripts encoding WRKY transcription factors. However, significant divergence was observed with respect to secondary metabolism dependent upon the insect attacker. Transcripts encoding enzymes and proteins associated with glucosinolate metabolism were decreased following attack by the generalist M. persicae but not by the specialist B. brassicae. This analysis provides a comprehensive overview of the molecular patterns associated with the plant response to PFIs and suggests that plants recognize and respond to perturbations in the cell wall occurring during PFI infestation. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights

Identification and Expression Profiles of Six Transcripts Encoding Carboxylesterase Protein in Vitis flexuosa Infected with Pathogens

Directory of Open Access Journals (Sweden)

Md. Zaherul Islam

2016-08-01

Full Text Available Plants protect themselves from pathogen attacks via several mechanisms, including hypersensitive cell death. Recognition of pathogen attack by the plant resistance gene triggers expression of carboxylesterase genes associated with hypersensitive response. We identified six transcripts of carboxylesterase genes, Vitis flexuosa carboxylesterase 5585 (VfCXE5585, VfCXE12827, VfCXE13132, VfCXE17159, VfCXE18231, and VfCXE47674, which showed different expression patterns upon transcriptome analysis of V. flexuosa inoculated with Elsinoe ampelina. The lengths of genes ranged from 1,098 to 1,629 bp, and their encoded proteins consisted of 309 to 335 amino acids. The predicted amino acid sequences showed hydrolase like domains in all six transcripts and contained two conserved motifs, GXSXG of serine hydrolase characteristics and HGGGF related to the carboxylesterase family. The deduced amino acid sequence also contained a potential catalytic triad consisted of serine, aspartic acid and histidine. Of the six transcripts, VfCXE12827 showed upregulated expression against E. ampelina at all time points. Three genes (VfCXE5585, VfCXE12827, and VfCXE13132 showed upregulation, while others (VfCXE17159, VfCXE18231, and VfCXE47674 were down regulated in grapevines infected with Botrytis cinerea. All transcripts showed upregulated expression against Rhizobium vitis at early and later time points except VfCXE12827, and were downregulated for up to 48 hours post inoculation (hpi after upregulation at 1 hpi in response to R. vitis infection. All tested genes showed high and differential expression in response to pathogens, indicating that they all may play a role in defense pathways during pathogen infection in grapevines.

Supra-optimal expression of the cold-regulated OsMyb4 transcription factor in transgenic rice changes the complexity of transcriptional network with major effects on stress tolerance and panicle development

KAUST Repository

Park, Myoungryoul

2010-09-28

The R2R3-type OsMyb4 transcription factor of rice has been shown to play a role in the regulation of osmotic adjustment in heterologous overexpression studies. However, the exact composition and organization of its underlying transcriptional network has not been established to be a robust tool for stress tolerance enhancement by regulon engineering. OsMyb4 network was dissected based on commonalities between the global chilling stress transcriptome and the transcriptome configured by OsMyb4 overexpression. OsMyb4 controls a hierarchical network comprised of several regulatory sub-clusters associated with cellular defense and rescue, metabolism and development. It regulates target genes either directly or indirectly through intermediary MYB, ERF, bZIP, NAC, ARF and CCAAT-HAP transcription factors. Regulatory sub-clusters have different combinations of MYB-like, GCC-box-like, ERD1-box-like, ABRE-like, G-box-like, as1/ocs/TGA-like, AuxRE-like, gibberellic acid response element (GARE)-like and JAre-like cis-elements. Cold-dependent network activity enhanced cellular antioxidant capacity through radical scavenging mechanisms and increased activities of phenylpropanoid and isoprenoid metabolic processes involving various abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), ethylene and reactive oxygen species (ROS) responsive genes. OsMyb4 network is independent of drought response element binding protein/C-repeat binding factor (DREB/CBF) and its sub-regulons operate with possible co-regulators including nuclear factor-Y. Because of its upstream position in the network hierarchy, OsMyb4 functions quantitatively and pleiotrophically. Supra-optimal expression causes misexpression of alternative targets with costly trade-offs to panicle development. © 2010 Blackwell Publishing Ltd.

Supra-optimal expression of the cold-regulated OsMyb4 transcription factor in transgenic rice changes the complexity of transcriptional network with major effects on stress tolerance and panicle development.

Science.gov (United States)

Park, Myoung-Ryoul; Yun, Kil-Young; Mohanty, Bijayalaxmi; Herath, Venura; Xu, Fuyu; Wijaya, Edward; Bajic, Vladimir B; Yun, Song-Joong; De Los Reyes, Benildo G

2010-12-01

The R2R3-type OsMyb4 transcription factor of rice has been shown to play a role in the regulation of osmotic adjustment in heterologous overexpression studies. However, the exact composition and organization of its underlying transcriptional network has not been established to be a robust tool for stress tolerance enhancement by regulon engineering. OsMyb4 network was dissected based on commonalities between the global chilling stress transcriptome and the transcriptome configured by OsMyb4 overexpression. OsMyb4 controls a hierarchical network comprised of several regulatory sub-clusters associated with cellular defense and rescue, metabolism and development. It regulates target genes either directly or indirectly through intermediary MYB, ERF, bZIP, NAC, ARF and CCAAT-HAP transcription factors. Regulatory sub-clusters have different combinations of MYB-like, GCC-box-like, ERD1-box-like, ABRE-like, G-box-like, as1/ocs/TGA-like, AuxRE-like, gibberellic acid response element (GARE)-like and JAre-like cis-elements. Cold-dependent network activity enhanced cellular antioxidant capacity through radical scavenging mechanisms and increased activities of phenylpropanoid and isoprenoid metabolic processes involving various abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), ethylene and reactive oxygen species (ROS) responsive genes. OsMyb4 network is independent of drought response element binding protein/C-repeat binding factor (DREB/CBF) and its sub-regulons operate with possible co-regulators including nuclear factor-Y. Because of its upstream position in the network hierarchy, OsMyb4 functions quantitatively and pleiotrophically. Supra-optimal expression causes misexpression of alternative targets with costly trade-offs to panicle development. © 2010 Blackwell Publishing Ltd.

Defensive responses of Brandt's voles (Lasiopodomys brandtii) to stored cat feces.

Science.gov (United States)

Hegab, Ibrahim M; Jin, Yajuan; Ye, Manhong; Wang, Aiqin; Yin, Baofa; Yang, Shengmei; Wei, Wanhong

2014-01-17

Predator odors are non-intrusive natural stressors of high ethological relevance. Animals are daily challenged with stressors of varying intensity and it is essential for their survival to respond to a wide range of threats. Behavioral and hormonal responses and changes in the level of medial hypothalamic c-fos mRNA were examined in Brandt's voles (Lasiopodomys brandtii) exposed to the feces of a domestic cat (Felis catus) stored for different periods. One hundred voles were tested in the defensive withdrawal apparatus. The voles showed an aversion to freshly collected cat feces, indicated by high levels of flight-related behaviors, increased freezing behavior, and more vigilant rearing compared to old feces. The serum levels of adrenocorticotropic hormone and corticosterone significantly increased when the voles were exposed to fresh cat feces. The level of c-fos mRNA in the medial hypothalamic region was highest in the individuals exposed to fresh cat feces. All of these behavioral, endocrine and c-fos-mRNA responses were lower when voles were subjected to older cat feces. We conclude that these responses depend on volatile chemical constituents of cat feces rather than their physical characteristics and that this accounts for the lower responses to feces stored for longer periods. © 2013. Published by Elsevier Inc. All rights reserved.

Toxicological responses of the hard clam Meretrix meretrix exposed to excess dissolved iron or challenged by Vibrio parahaemolyticus

International Nuclear Information System (INIS)

Zhou, Qing; Zhang, Yong; Peng, Hui-Fang; Ke, Cai-Huan; Huang, He-Qing

2014-01-01

Highlights: • Fe accumulated in hepatopancreas tissues after iron-enriched exposure. • Ferritin expression was positively correlated with iron concentration in seawater. • Ferritin appears to be involved in iron homeostasis and immune defense mechanism of M. meretrix. • mRNAs of cytokine genes responded faster than antioxidant enzyme genes in immune defense mechanism. • The study gives a new potential biomarker for monitoring iron levels in seawater. - Abstract: The responses of genes encoding defense components such as ferritin, the lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF), the inhibitor of nuclear factor-κB (IκB), metallothionein, and glutathione peroxidase were assessed at the transcriptional level in order to investigate the toxicological and immune mechanism of the hard clam Meretrix meretrix (HCMM) following challenge with iron or a bacterium (Vibrio parahaemolyticus). Fe dissolved in natural seawater led to an increase of Fe content in both the hepatopancreas and gill tissue of HCMM between 4 and 15 days of exposure. The ferritin gene responded both transcriptionally as indicated by real-time quantitative PCR and translationally as shown by western blotting results to iron exposure and both transcriptional and translational ferritin expression in the hepatopancreas had a positive correlation with the concentration of dissolved iron in seawater. Both iron and V. parahaemolyticus exposure triggered immune responses with similar trends in clam tissues. There was a significant post-challenge mRNA expression of LITAF and IκB at 3 h, ferritin at 24 h, and metallothionein and glutathione peroxidase at 48 h. This behavior might be linked to their specific functions in physiological processes. These results suggested that similar signaling pathways were triggered during both iron and V. parahaemolyticus challenges. Here, we indicated that the ferritin of Meretrix meretrix was an intermediate in the pathway of iron homeostasis

Toxicological responses of the hard clam Meretrix meretrix exposed to excess dissolved iron or challenged by Vibrio parahaemolyticus

Energy Technology Data Exchange (ETDEWEB)

Zhou, Qing [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Zhang, Yong [Department of Chemistry, College of Chemistry and Chemical Engineering, and the Key Laboratory of Chemical Biology of Fujian Province, Xiamen University, Xiamen 361102 (China); Peng, Hui-Fang [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); Ke, Cai-Huan, E-mail: chke@xmu.edu.cn [State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Huang, He-Qing, E-mail: hqhuang@xmu.edu.cn [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Department of Chemistry, College of Chemistry and Chemical Engineering, and the Key Laboratory of Chemical Biology of Fujian Province, Xiamen University, Xiamen 361102 (China)

2014-11-15