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‣ Repeated stressors do not provoke habituation or accumulation of the stress response in the catfish Rhamdia quelen

Koakoski,Gessi; Kreutz,Luiz Carlos; Fagundes,Michele; Oliveira,Thiago Acosta; Ferreira,Daiane; Rosa,Joao Gabriel Santos da; Barcellos,Leonardo Jose Gil
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 Português
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578.0302%
Fish repeatedly experience stressful situations under experimental and aquaculture conditions, even in their natural habitat. Fish submitted to sequential stressors can exhibit accumulation or habituation on its cortisol response. We posed a central question about the cortisol response profiles after exposure to successive acute stressors of a similar and different nature in Rhamdia quelen. We have shown that successive acute stressors delivered with 12-h, 48-h, and 1-week intervals provoked similar cortisol responses in juvenile R. quelen, without any habituation or accumulation. The cumulative stress response is more associated to short acute stressors with very short intervals of minutes to hours. In our work, we used an interval as short as 12h, and no cumulative response was found. However, if the length of time between stressors is of a day or week as used in our work the most common and an expected phenomenon is the attenuation of the response. Thus, also, the absence of both accumulation of the stress response and the expected habituation is an intriguing result. Our results show that R. quelen does not show habituation or accumulation in its stress responses to repeated stressors, as reported for other fish species

‣ Stress-induced Gene Expression in Candida albicans: Absence of a General Stress Response D⃞

Enjalbert, Brice; Nantel, André; Whiteway, Malcolm
Fonte: The American Society for Cell Biology Publicador: The American Society for Cell Biology
Tipo: Artigo de Revista Científica
Publicado em /04/2003 Português
Relevância na Pesquisa
480.03375%
We used transcriptional profiling to investigate the response of the fungal pathogen Candida albicans to temperature and osmotic and oxidative stresses under conditions that permitted >60% survival of the challenged cells. Each stress generated the transient induction of a specific set of genes including classic markers observed in the stress responses of other organisms. We noted that the classical hallmarks of the general stress response observed in Saccharomyces cerevisiae are absent from C. albicans; no C. albicans genes were significantly induced in a common response to the three stresses. This observation is supported by our inability to detect stress cross-protection in C. albicans. Similarly, in C. albicans there is essentially no induction of carbohydrate reserves like glycogen and trehalose in response to a mild stress, unlike the situation in S. cerevisiae. Thus C. albicans lacks the strong general stress response exhibited by S. cerevisiae.

‣ Evidence that heat and ultraviolet radiation activate a common stress-response program in plants that is altered in the uvh6 mutant of Arabidopsis thaliana.

Jenkins, M E; Suzuki, T C; Mount, D W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1997 Português
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677.6984%
The uvh6 mutant of Arabidopsis was previously isolated in a screen for increased sensitivity to ultraviolet (UV) radiation. uvh6 mutant plants were killed by incubation at 37 degrees C for 4 d, a treatment not lethal to wild-type plants. Furthermore, under permissive conditions, uvh6 plants were yellow-green with an approximately one-third lower chlorophyll content. Genetic analysis of the uvh6 mutant strongly suggested that all three mutant phenotypes were due to mutation at the same genetic locus. To understand UVH6 function more fully, the response of wild-type plants to growth at elevated temperatures and exposure to UV radiation was analyzed. Wild-type plants grown at 30 degrees C were as UV-hypersensitive and yellow-green as uvh6 mutant plants grown at 24 degrees C. Mutant uvh6 plants induced heat-shock protein HSP21 at a lower threshold temperature than wild-type plants, indicating that the uvh6 mutant was exhibiting signs of heat stress at a 4 to 5 degrees C lower temperature than wild-type plants. We propose the UV damage and heat induce a common stress response in plants that leads to tissue death and reduced chloroplast function, and that the UVH6 product is a negative regulator of this response.

‣ Histatin 5 Initiates Osmotic Stress Response in Candida albicans via Activation of the Hog1 Mitogen-Activated Protein Kinase Pathway▿

Vylkova, Slavena; Jang, Woong Sik; Li, Wansheng; Nayyar, Namrata; Edgerton, Mira
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Português
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Histatin 5 (Hst 5) is a salivary cationic peptide that has toxicity for Candida albicans by inducing rapid cellular ion imbalance and cell volume loss. Microarray analyses of peptide-treated cells were used to evaluate global gene responses elicited by Hst 5. The major transcriptional response of C. albicans to Hst 5 was expression of genes involved in adaptation to osmotic stress, including production of glycerol (RHR2, SKO1, and PDC11) and the general stress response (CTA1 and HSP70). The oxidative-stress genes AHP1, TRX1, and GPX1 were mildly induced by Hst 5. Cell defense against Hst 5 was dependent on the Hog1 mitogen-activated protein kinase (MAPK) pathway, since C. albicans hog1/hog1 mutants were significantly hypersensitive to Hst 5 but not to Mkc1 MAPK or Cek1 MAPK mutants. Activation of the high-osmolarity glycerol (HOG) pathway was demonstrated by phosphorylation of Hog1 MAPK as well as by glycerol production following Hst 5 treatment in a dose-dependent manner. C. albicans cells prestressed with sorbitol were less sensitive to subsequent Hst 5 treatment; however, cells treated concurrently with osmotic stress and Hst 5 were hypersensitive to Hst 5. In contrast, cells subjected to oxidative stress had no difference in sensitivity to Hst 5. These results suggest a common underlying cellular response to osmotic stress and Hst 5. The HOG stress response pathway likely represents a significant and effective challenge to physiological levels of Hst 5 and other toxic peptides in fungal cells.

‣ Molecular and Physiological Analysis of Drought Stress in Arabidopsis Reveals Early Responses Leading to Acclimation in Plant Growth1[C][W][OA]

Harb, Amal; Krishnan, Arjun; Ambavaram, Madana M.R.; Pereira, Andy
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Português
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477.9758%
Plant drought stress response and resistance are complex biological processes that need to be analyzed at a systems level using genomics and physiological approaches to dissect experimental models that address drought stresses encountered by crops in the field. Toward this goal, a controlled, sublethal, moderate drought (mDr) treatment system was developed in Arabidopsis (Arabidopsis thaliana) as a reproducible assay for the dissection of plant responses to drought. The drought assay was validated using Arabidopsis mutants in abscisic acid (ABA) biosynthesis and signaling displaying drought sensitivity and in jasmonate response mutants showing drought resistance, indicating the crucial role of ABA and jasmonate signaling in drought response and acclimation. A comparative transcriptome analysis of soil water deficit drought stress treatments revealed the similarity of early-stage mDr to progressive drought, identifying common and specific stress-responsive genes and their promoter cis-regulatory elements. The dissection of mDr stress responses using a time-course analysis of biochemical, physiological, and molecular processes revealed early accumulation of ABA and induction of associated signaling genes, coinciding with a decrease in stomatal conductance as an early avoidance response to drought stress. This is accompanied by a peak in the expression of expansin genes involved in cell wall expansion...

‣ Extensive Translatome Remodeling during ER Stress Response in Mammalian Cells

Ventoso, Iván; Kochetov, Alex; Montaner, David; Dopazo, Joaquín; Santoyo, Javier
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/05/2012 Português
Relevância na Pesquisa
478.51395%
In this work we have described the translatome of two mammalian cell lines, NIH3T3 and Jurkat, by scoring the relative polysome association of ∼10,000 mRNA under normal and ER stress conditions. We have found that translation efficiencies of mRNA correlated poorly with transcript abundance, although a general tendency was observed so that the highest translation efficiencies were found in abundant mRNA. Despite the differences found between mouse (NIH3T3) and human (Jurkat) cells, both cell types share a common translatome composed by ∼800–900 mRNA that encode proteins involved in basic cellular functions. Upon stress, an extensive remodeling in translatomes was observed so that translation of ∼50% of mRNA was inhibited in both cell types, this effect being more dramatic for those mRNA that accounted for most of the cell translation. Interestingly, we found two subsets comprising 1000–1500 mRNA whose translation resisted or was induced by stress. Translation arrest resistant class includes many mRNA encoding aminoacyl tRNA synthetases, ATPases and enzymes involved in DNA replication and stress response such as BiP. This class of mRNA is characterized by high translation rates in both control and stress conditions. Translation inducible class includes mRNA whose translation was relieved after stress...

‣ FSRD: fungal stress response database

Karányi, Zsolt; Holb, Imre; Hornok, László; Pócsi, István; Miskei, Márton
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em 11/06/2013 Português
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480.15094%
Adaptation to different types of environmental stress is a common part of life for today’s fungi. A deeper understanding of the organization, regulation and evolution of fungal stress response systems may lead to the development of novel antifungal drugs and technologies or the engineering of industrial strains with elevated stress tolerance. Here we present the Fungal Stress Response Database (http://internal.med.unideb.hu/fsrd) aimed to stimulate further research on stress biology of fungi. The database incorporates 1985 fungal stress response proteins with verified physiological function(s) and their orthologs identified and annotated in 28 species including human and plant pathogens, as well as important industrial fungi. The database will be extended continuously to cover other fully sequenced fungal species. Our database, as a starting point for future stress research, facilitates the analysis of literature data on stress and the identification of ortholog groups of stress response proteins in newly sequenced fungal genomes.

‣ Dysfunctional Astrocytic and Synaptic Regulation of Hypothalamic Glutamatergic Transmission in a Mouse Model of Early-Life Adversity: Relevance to Neurosteroids and Programming of the Stress Response

Gunn, Benjamin G.; Cunningham, Linda; Cooper, Michelle A.; Corteen, Nicole L.; Seifi, Mohsen; Swinny, Jerome D.; Lambert, Jeremy J.; Belelli, Delia
Fonte: Society for Neuroscience Publicador: Society for Neuroscience
Tipo: Artigo de Revista Científica
Publicado em 11/12/2013 Português
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Adverse early-life experiences, such as poor maternal care, program an abnormal stress response that may involve an altered balance between excitatory and inhibitory signals. Here, we explored how early-life stress (ELS) affects excitatory and inhibitory transmission in corticotrophin-releasing factor (CRF)-expressing dorsal-medial (mpd) neurons of the neonatal mouse hypothalamus. We report that ELS associates with enhanced excitatory glutamatergic transmission that is manifested as an increased frequency of synaptic events and increased extrasynaptic conductance, with the latter associated with dysfunctional astrocytic regulation of glutamate levels. The neurosteroid 5α-pregnan-3α-ol-20-one (5α3α-THPROG) is an endogenous, positive modulator of GABAA receptors (GABAARs) that is abundant during brain development and rises rapidly during acute stress, thereby enhancing inhibition to curtail stress-induced activation of the hypothalamic-pituitary-adrenocortical axis. In control mpd neurons, 5α3α-THPROG potently suppressed neuronal discharge, but this action was greatly compromised by prior ELS exposure. This neurosteroid insensitivity did not primarily result from perturbations of GABAergic inhibition, but rather arose functionally from the increased excitatory drive onto mpd neurons. Previous reports indicated that mice (dams) lacking the GABAAR δ subunit (δ0/0) exhibit altered maternal behavior. Intriguingly...

‣ Broad-Spectrum Anti-biofilm Peptide That Targets a Cellular Stress Response

de la Fuente-Núñez, César; Reffuveille, Fany; Haney, Evan F.; Straus, Suzana K.; Hancock, Robert E. W.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 22/05/2014 Português
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Bacteria form multicellular communities known as biofilms that cause two thirds of all infections and demonstrate a 10 to 1000 fold increase in adaptive resistance to conventional antibiotics. Currently, there are no approved drugs that specifically target bacterial biofilms. Here we identified a potent anti-biofilm peptide 1018 that worked by blocking (p)ppGpp, an important signal in biofilm development. At concentrations that did not affect planktonic growth, peptide treatment completely prevented biofilm formation and led to the eradication of mature biofilms in representative strains of both Gram-negative and Gram-positive bacterial pathogens including Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, methicillin resistant Staphylococcus aureus, Salmonella Typhimurium and Burkholderia cenocepacia. Low levels of the peptide led to biofilm dispersal, while higher doses triggered biofilm cell death. We hypothesized that the peptide acted to inhibit a common stress response in target species, and that the stringent response, mediating (p)ppGpp synthesis through the enzymes RelA and SpoT, was targeted. Consistent with this, increasing (p)ppGpp synthesis by addition of serine hydroxamate or over-expression of relA led to reduced susceptibility to the peptide. Furthermore...

‣ A conserved cell growth cycle can account for the environmental stress responses of divergent eukaryotes

Slavov, Nikolai; Airoldi, Edoardo Maria; van Oudenaarden, A.; Botstein, D.
Fonte: American Society for Cell Biology (ASCB) Publicador: American Society for Cell Biology (ASCB)
Tipo: Artigo de Revista Científica
Português
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The respiratory metabolic cycle in budding yeast (Saccharomyces cerevisiae) consists of two phases most simply defined phenomenologically: low oxygen consumption (LOC) and high oxygen consumption (HOC). Each phase is associated with the periodic expression of thousands of genes, producing oscillating patterns of gene-expression found in synchronized cultures and in single cells of slowly growing unsynchronized cultures. Systematic variation in the durations of the HOC and LOC phases can account quantitatively for well-studied transcriptional responses to growth rate differences. Here we show that a similar mechanism, transitions from the HOC phase to the LOC phase, can account for much of the common environmental stress response (ESR) and for the cross protection by a preliminary heat stress (or slow growth rate) to subsequent lethal heat-stress. Similar to the budding yeast metabolic cycle, we suggest that a metabolic cycle, coupled in a similar way to the ESR, in the distantly related fission yeast, Schizosaccharomyces pombe, and in human can explain gene-expression and respiratory patterns observed in these organisms. Although metabolic cycling is associated with the G0/G1 phase of the cell division cycle of slowly growing budding yeast...

‣ TDP-43 régule la dynamique et la fonction des Granules de Stress via G3BP1

Aulas, Anaïs
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
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Les Granule de Stress (GS) sont des inclusions cytoplasmiques contenant des protéines et des ARNm qui s’assemblent en réponse à l’exposition à un stress. Leur formation fait partie intégrante de la réponse cellulaire au stress et est considérée comme une étape déterminante pour la résistance au stress et la survie cellulaire. Actuellement, les GS sont reliés à divers pathologies allant des infections virales aux maladies neurovégétatives. L’une d’entre elle, la Sclérose Latérale Amyotrophique (SLA) est particulièrement agressive, caractérisée par une perte des neurones moteurs aboutissant à la paralysie et à la mort du patient en cinq ans en moyenne. Les mécanismes de déclenchement de la pathologie restent encore à déterminer. TDP-43 (TAR DNA binding protein 43) et FUS (Fused in liposarcoma) sont deux protéines reliées à la pathologie qui présentent des similarités de structure et de fonction, suggérant un mécanisme commun de toxicité. TDP-43 et FUS sont toutes les deux recrutées au niveau des GS en condition de stress. Nous avons démontré pour la première fois que la fonction des GS est de protéger les ARNm de la dégradation induite par l’exposition au stress. Cette fonction n’était que suspectée jusqu’alors. De plus nous avons mis en évidence que G3BP1 (Ras GTPase-activating protein-binding protein 1) est l’effectrice de cette fonction via son implication dans la dynamique de formation des GS. TDP-43 étant un régulateur de G3BP1...

‣ Studies on the oxidative stress response of porphyromonas gingivalis

Díaz, Patricia I.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2003 Português
Relevância na Pesquisa
571.8207%
Porphyromonas gingivalis is a Gram-negative anaerobic cocco-bacillus strongly implicated in the aetiology of adult periodontitis. During the colonisation of the oral cavity it is likely that P. gingivalis encounters different sources of oxidative stress. Adaptation to this challenge is necessary for the microorganism to survive and establish in the periodontal environment. The aim of the present study was, therefore, to investigate the oxidative stress survival mechanisms of P. gingivalis. P. gingivalls was grown under different oxygenated environments in a continuous culture system under conditions of haemin-limitation and excess. Steady state was achieved under moderately oxygenated atmospheres, although a decrease in cell viability was observed as the oxygen concentration in the gas mixture increased. Haemin-excess conditions seemed to increase the ability of a culture to cope with a determined oxygen concentration. The main change in fermentation end-products characterising oxygen stressed cultures was an increase in the production of acetate. Scanning electron micrographs showed that oxygen triggers a change in the cell shape from a cocco-bacillary to a short rod. The effect of oxygen on the expression of cysteine proteinases...

‣ From transcriptome to biological function: environmental stress in an ectothermic vertebrate, the coral reef fish Pomacentrus moluccensis

Kassahn, K.S.; Crozier, R.H.; Ward, A.C.; Stone, G.; Caley, M.J.
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em //2007 Português
Relevância na Pesquisa
489.67758%
Background: Our understanding of the importance of transcriptional regulation for biological function is continuously improving. We still know, however, comparatively little about how environmentally induced stress affects gene expression in vertebrates, and the consistency of transcriptional stress responses to different types of environmental stress. In this study, we used a multi-stressor approach to identify components of a common stress response as well as components unique to different types of environmental stress. We exposed individuals of the coral reef fish Pomacentrus moluccensis to hypoxic, hyposmotic, cold and heat shock and measured the responses of approximately 16,000 genes in liver. We also compared winter and summer responses to heat shock to examine the capacity for such responses to vary with acclimation to different ambient temperatures. Results: We identified a series of gene functions that were involved in all stress responses examined here, suggesting some common effects of stress on biological function. These common responses were achieved by the regulation of largely independent sets of genes; the responses of individual genes varied greatly across different stress types. In response to heat exposure over five days...

‣ Animal performance and stress: responses and tolerance limits at different levels of biological organisation

Kassahn, K.S.; Crozier, R.H.; Pörtner, H.O.; Caley, M.J.
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
494.00125%
Recent advances in molecular biology and the use of DNA microarrays for gene expression profiling are providing new insights into the animal stress response, particularly the effects of stress on gene regulation. However, interpretation of the complex transcriptional changes that occur during stress still poses many challenges because the relationship between changes at the transcriptional level and other levels of biological organisation is not well understood. To confront these challenges, a conceptual model linking physiological and transcriptional responses to stress would be helpful. Here, we provide the basis for one such model by synthesising data from organismal, endocrine, cellular, molecular, and genomic studies. We show using available examples from ectothermic vertebrates that reduced oxygen levels and oxidative stress are common to many stress conditions and that the responses to different types of stress, such as environmental, handling and confinement stress, often converge at the challenge of dealing with oxygen imbalance and oxidative stress. As a result, a common set of stress responses exists that is largely independent of the type of stressor applied. These common responses include the repair of DNA and protein damage...

‣ Anticipation of Nitric Oxide Stress in the Human Commensal Fungus Candida albicans

Lynn, Jed
Fonte: Universidade Rice Publicador: Universidade Rice
Português
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480.0107%
Candida albicans is the most common human commensal fungus, able to colonize host niches such as skin, mouth and gastrointestinal tract. Colonization of diverse microenvironments requires the ability to evade or overcome innate host protection and adapt to rapid transitions between environments with different stresses and nutrient availability. Colonization of the gastrointestinal tract requires passage through the stomach containing toxic levels of nitric oxide, generated from acidification of nitrite in the low pH of the stomach. Although resistance of C. albicans to nitric oxide is mediated by the flavohemoglobin Yhb1, little is known about the physiologically relevant ligands that regulate YHB1 expression. Here I propose the hypothesis that nontoxic saliva chemicals induce YHB1 expression and promote resistance to nitric oxide generated in the stomach. Supporting this hypothesis is the observation that two ions actively concentrated in the saliva – nitrate and thiocyanate – induce YHB1 expression. Indeed, whole-genome transcriptional analysis of C. albicans treated with nitrate or thiocyanate produce gene expression profiles nearly identical to cells treated with nitrite or nitric oxide. Pretreatment of C. albicans with either of these two nontoxic compounds increases resistance of the yeast to nitric oxide. I propose that this is an evolved response in which C. albicans anticipates nitric oxide stress generated in the stomach. C. albicans thus upregulates nitric oxide stress response genes in response to saliva signals that precede nitric oxide formation further on in the gut. Only a few examples of anticipatory signaling have so far been identified and it is not known how common this type of regulation is among microbes. Expression of the YHB1 gene in response to nitric oxide is regulated by the transcription factor Cta4. I show that Cta4 binds to the YHB1 promoter in vivo as a homodimer and is necessary...

‣ Uncovering Mechanisms of Bistability and Ultrasensitivity in Bacterial Stress Response

Tiwari, Abhinav
Fonte: Universidade Rice Publicador: Universidade Rice
Português
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675.81125%
Bacteria have evolved optimized biochemical and genetic networks to sense diverse stimuli and implement appropriate dynamic responses. Despite the remarkable progress in experimental approaches and the increasingly common use of mathematical modeling, very few examples exist of general design principles that relate a network’s structure to its response. To improve this understanding we develop biochemically accurate models of networks that contain well-conserved regulatory modules, which allows us to make both specific and biologically-relevant predictions. First, we analyze the mycobacterial stress-response network which consists of the MprA/MprB two-component system and the alternative sigma factor Sig E. This network contains multiple positive feedback loops which may give rise to bistability, thereby making it a good candidate for controlling the mycobacterial persistence switch. We find that neither the positive autoregulation in the two-component system nor the Sig E-mediated feedback is sufficient to induce bistability. Nonetheless, including the post-translational regulation of SigE by RseA increases system’s effective cooperativity resulting in bistability. We predict that overexpression or deletion of RseA, the key element controlling the ultrasensitive response...

‣ Extensive translatome remodeling during ER stress response in mammalian cells

Ventoso, Iván; Kochetov, Alex; Montaner, David; Dopazo, Joaquín; Santoyo, Javier
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
478.51395%
In this work we have described the translatome of two mammalian cell lines, NIH3T3 and Jurkat, by scoring the relative polysome association of ~10,000 mRNA under normal and ER stress conditions. We have found that translation efficiencies of mRNA correlated poorly with transcript abundance, although a general tendency was observed so that the highest translation efficiencies were found in abundant mRNA. Despite the differences found between mouse (NIH3T3) and human (Jurkat) cells, both cell types share a common translatome composed by ~800-900 mRNA that encode proteins involved in basic cellular functions. Upon stress, an extensive remodeling in translatomes was observed so that translation of ~50% of mRNA was inhibited in both cell types, this effect being more dramatic for those mRNA that accounted for most of the cell translation. Interestingly, we found two subsets comprising 1000-1500 mRNA whose translation resisted or was induced by stress. Translation arrest resistant class includes many mRNA encoding aminoacyl tRNA synthetases, ATPases and enzymes involved in DNA replication and stress response such as BiP. This class of mRNA is characterized by high translation rates in both control and stress conditions. Translation inducible class includes mRNA whose translation was relieved after stress...

‣ Inactivation of Drosophila DJ-1 leads to impairments of oxidative stress response and phosphatidylinositol 3-kinase/Akt signaling

Yang, Yufeng; Gehrke, Stephan; Haque, Md. Emdadul; Imai, Yuzuru; Kosek, Jon; Yang, Lichuan; Beal, M. Flint; Nishimura, Isao; Wakamatsu, Kazumasa; Ito, Shosuke; Takahashi, Ryosuke; Lu, Bingwei
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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479.81316%
Parkinson's disease (PD) is the most common movement disorder characterized by dopaminergic dysfunction and degeneration. The cause of most PD cases is unknown, although postmortem studies have implicated the involvement of oxidative stress. The identification of familial PD-associated genes offers the opportunity to study mechanisms of PD pathogenesis in model organisms. Here, we show that DJ-1A, a Drosophila homologue of the familial PD-associated gene DJ-1, plays an essential role in oxidative stress response and neuronal maintenance. Inhibition of DJ-1A function through RNA interference (RNAi) results in cellular accumulation of reactive oxygen species, organismal hypersensitivity to oxidative stress, and dysfunction and degeneration of dopaminergic and photoreceptor neurons. To identify other genes that may interact with DJ-1A in regulating cell survival, we performed genetic interaction studies and identified components of the phosphatidylinositol 3-kinase (PI3K)/Akt-signaling pathway as specific modulators of DJ-1A RNAi-induced neurodegeneration. PI3K signaling suppresses DJ-1A RNAi phenotypes at least in part by reducing cellular reactive oxygen species levels. Consistent with the genetic interaction results, we also found reduced phosphorylation of Akt in DJ-1A RNAi animals...

‣ Carotenoid-Based Colours Reflect the Stress Response in the Common Lizard

Fitze, Patrick S.; Cote, Julien; San José, Luis M.; Meylan, Sandrine; Isaksson, Caroline; Andersson, Staffan; Rossi, Jean-Marc; Clobert, Jean
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artículo Formato: 384548 bytes; application/pdf
Português
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478.36273%
10 pages, 4 figures and 2 tables.; [Abstract] Under chronic stress, carotenoid-based colouration has often been shown to fade. However, the ecological and physiological mechanisms that govern colouration still remain largely unknown. Colour changes may be directly induced by the stressor (for example through reduced carotenoid intake) or due to the activation of the physiological stress response (PSR, e.g. due to increased blood corticosterone concentrations). Here, we tested whether blood corticosterone concentration affected carotenoid-based colouration, and whether a trade-off between colouration and PSR existed. Using the common lizard (Lacerta vivipara), we correlatively and experimentally showed that elevated blood corticosterone levels are associated with increased redness of the lizard's belly. In this study, the effects of corticosterone did not depend on carotenoid ingestion, indicating the absence of a trade-off between colouration and PSR for carotenoids. While carotenoid ingestion increased blood carotenoid concentration, colouration was not modified. This suggests that carotenoid-based colouration of common lizards is not severely limited by dietary carotenoid intake. Together with earlier studies, these findings suggest that the common lizard's carotenoid-based colouration may be a composite trait...

‣ High-resolution mass spectrometry based proteomic analysis of the response to vancomycin-induced cell wall stress in Streptomyces coelicolor A3(2)

Hesketh, Andrew; Deery, Michael; Hong, Hee-Jon
Fonte: ACS Publications Publicador: ACS Publications
Tipo: Article; published version
Português
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This is the final version of the article. It first appeared from ACS Publications via http://dx.doi.org/10.1021/acs.jproteome.5b00242; Understanding how bacteria survive periods of cell wall stress is of fundamental interest and can help generate ideas for improved antibacterial treatments. In this study we use tandem mass tagging to characterize the proteomic response of vancomycin resistant Streptomyces coelicolor to the exposure to sublethal levels of the antibiotic. A common set of 804 proteins were identified in triplicate experiments. Contrasting changes in the abundance of proteins closely associated with the cytoplasmic membrane with those taking place in the cytosol identified aspects of protein spatial localization that are associated with the response to vancomycin. Enzymes for peptidoglycan precursor, mycothiol, ectoine and menaquinone biosynthesis together with a multisubunit nitrate reductase were recruited to the membrane following vancomycin treatment. Many proteins with regulatory functions (including sensor protein kinases) also exhibited significant changes in abundance exclusively in the membrane-associated protein fraction. Several enzymes predicted to be involved in extracellular peptidoglycan crossbridge formation became significantly depleted from the membrane. A comparison with data previously acquired on the changes in gene transcription following vancomycin treatment identified a common high-confidence set of changes in gene expression. Generalized changes in protein abundance indicate roles for proteolysis...