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Shock Response (shock + response)
Kinds of Shock Response Selected AbstractsThe stress response is repressed during fermentation in brewery strains of yeastJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2000M.P. Brosnan Yeast cells encounter a variety of environmental stresses during brewing and must respond to ensure cell survival. Cells can respond to stress by inducing a Heat Shock Response in which heat shock proteins (Hsps) are synthesized. In laboratory strains of Saccharomyces cerevisiae, the heat shock protein, Hsp104, plays a major role in the acquisition of tolerance to a variety of stresses such as heat, ethanol and sodium arsenite, and as such acts as an excellent stress indicator. The induction of Hsp104 in bottom-and top-fermenting brewery strains was examined when grown under laboratory and industrial fermentation conditions, and it was found that each brewing strain exhibits its own unique pattern of Hsp104 expression. During industrial fermentations, brewery strains are capable of mounting a stress response at the early stages of fermentation. However, as the fermentation proceeds, the response is repressed. The results suggest that conditions experienced in industrial brewing prevent the activation of the stress response. This study increases our understanding of alterations in gene expression patterns during the brewing process, and yields information that will aid in the definition of best practice in yeast management. [source] Protection of DNA during early development: adaptations and evolutionary consequencesEVOLUTION AND DEVELOPMENT, Issue 1 2003David Epel SUMMARY The rapidly dividing cleavage stages of embryos do not have the typical responses to cell damage, such as induction of the heat shock response, use of mitotic checkpoints, or use of apoptosis to eliminate severely damaged cells. This could create problems with integrity of DNA, but the solution in these embryos appears to be a "be prepared" approach, in which specific adaptations are used to minimize DNA damage during cleavage and the use of apoptosis at the mid-blastula transition to remove any cells that were nevertheless damaged. It has been assumed that this approach has evolved because of the advantage of rapid production of a motile larvae. Alternatively, this particular approach may have the selective advantage of increasing mutation rate when there are greater environmental stresses. This could provide more variants on which selective pressures could act and thus accelerate evolution during environmentally stressful periods. [source] Comparative analysis of changes in gene expression due to RNA melting activities of translation initiation factor IF1 and a cold shock protein of the CspA familyGENES TO CELLS, Issue 11 2009Sangita Phadtare In Escherichia coli, temperature downshift elicits cold shock response, which is characterized by induction of cold shock proteins. CspA, the major cold shock protein of E. coli, helps cells to acclimatize to low temperature by melting the secondary structures in nucleic acids and acting as a transcription antiterminator. CspA and its homologues contain the cold shock domain and belong to the oligomer binding protein family, which also includes S1 domain proteins such as IF1. Structural similarity between IF1 and CspA homologues suggested a functional overlap between these proteins. Indeed IF1 can melt secondary structures in RNA and acts as transcription antiterminator in vivo and in vitro. Here, we show that in spite of having these critical activities, IF1 does not complement cold-sensitivity of a csp quadruple deletion strain. DNA microarray analysis shows that overproduction of IF1 and Csp leads to changes in expression of different sets of genes. Importantly, several genes which were previously shown to require Csp proteins for their expression at low temperature did not respond to IF1. Moreover, in vitro, we show that a transcription terminator responsive to Csp does not respond to IF1. Our results suggest that Csp proteins and IF1 have different sets of target genes as they may be suppressing the function of different types of transcription termination elements in specific genes. [source] Adaptive response of the skin to UVB damage: role of the p53 proteinINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2006L. Verschooten Synopsis Different adaptation mechanisms like heat shock response, cell cycle arrest and DNA repair, melanin pigmentation and thickening of the epidermis are present in the human skin to protect against the adverse effects of solar UV irradiation. When DNA damage is beyond repair, cells undergo apoptosis to prevent their replication. We discuss the current knowledge on these different adaptation mechanisms to UVB damage, the most energetic fraction of solar UV that reaches the skin. As p53 protein, the guardian of the genome, plays a key role in protective response to genotoxic damage, its role in this adaptive response of the skin to UV will be further discussed. Résumé Pour se protéger contre les effets néfastes de l'irradiation UV de la lumière solaire, la peau humaine dispose de différents mécanismes de protection adaptatifs: résistance au choc thermique, arrêt du cycle cellulaire et réparation de l'ADN, pigmentation mélanique et épaississement de l'épiderme. Quand les altèrations dépassent les capacités de réparation, les cellules entrent en apoptose pour empêcher la réplication d'une cellule avec de l'ADN endommagé. Dans cet article, on passe en revue les connaissances actuelles sur les différents mécanismes d'adaptation de la peau aux altérations provoquées par les UVB, la fraction la plus énergétique des UV solaires qui atteint la peau. Puisque la protéine P53, gardienne du génome, joue un rôle clé dans la réponse de protection aux altérations génotoxiques, son rôle dans la réponse d'adaptation de la peau aux UV sera discuté en détail. [source] Physiological and molecular analysis of the stress response of Saccharomyces cerevisiae imposed by strong inorganic acid with implication to industrial fermentationsJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2010H.F. De Melo Abstract Aims:, This work aimed to identify the molecular mechanism that allows yeast cells to survive at low pH environments such as those of bioethanol fermentation. Methods and Results:, The industrial strain JP1 cells grown at pH 2 was evaluated by microarray analysis showing that most of the genes induced at low pH were part of the general stress response (GSR). Further, an acid-tolerant yeast mutant was isolated by adaptive selection that was prone to grow at low pH in inorganic but weak organic acid. It showed higher viability under acid-temperature synergistic treatment. However, it was deficient in some physiological aspects that are associated with defects in protein kinase A (PKA) pathway. Microarray analysis showed the induction of genes involved in inhibition of RNA and protein synthesis. Conclusions:, The results point out that low pH activates GSR, mainly heat shock response, that is important for long-term cell survival and suggest that a fine regulatory PKA-dependent mechanism that might affect cell cycle in order to acquire tolerance to acid environment. Significance and Impact of the Study:, These findings might guide the construction of a high-fermentative stress-tolerant industrial yeast strain that can be used in complex industrial fermentation processes. [source] The effect of culture growth phase on induction of the heat shock response in Yersinia enterocolitica and Listeria monocytogenesJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2000C.M.M. McMahon The effect of culture growth phase on induction of the heat shock response in Yersinia enterocolitica and Listeria monocytogenes, was examined. Exponential or stationary preconditioned cultures were heat shocked and survivor numbers estimated using selective and overlay/resuscitation recovery techniques. The results indicate that prior heat shock induced increased heat resistance in both micro-organisms to higher heat treatments. Heat-shocked cells of each micro-organism were able to survive much longer than non-heat-shocked cells when heated at 55 °C. The size of the change in heat resistance between heat-shocked and non-heat-shocked cells was greatest for exponential cultures (X:X). Results indicate that the overall relative thermal resistance of each pathogen was dependent on cell growth phase. Stationary cultures (S:S) were significantly (P < 0·01) more thermotolerant than exponential cultures (X:X) under identical processing conditions. Under most conditions, the use of an overlay/resuscitation recovery medium resulted in higher D -values (P < 0·05) compared with a selective recovery medium. [source] Phenotypic characterization of mouse embryonic fibroblasts lacking heat shock factor 2JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2003Liliana Paslaru Abstract In murine cells, the heat shock response is regulated by a transcription factor, HSF1, which triggers the transcription of heat shock genes. HSF2 has been shown to be involved in meiosis and mouse brain development. We characterized the effects of the absence of HSF2 in mouse embryonic fibroblasts (MEFs). The temperature threshold of the heat shock response appeared lowered in Hsf2 -/- MEFS as monitored by the synthesis of heat shock protein HSP70. In contrast to unstressed wild type MEFS, HSP70 and HSF1 are localized in the nucleus of unstressed Hsf2 -/- MEFS, a characteristic of stressed cells. HSF1 is not activated for DNA-binding at unstressed temperature in Hsf2 -/- MEFS. Therefore, the absence of HSF2 induces some but not all of the characteristics of the stress response. In addition, Hsf2 -/- MEFS exhibited proliferation defects, altered morphology, remodeling of the fibronectin network. [source] Diverse effects of Stat1 on the regulation of hsp90, gene under heat shock,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2007Xue-song Chen Abstract Stat1 has been known as a regulator of gene expression and a mediator of IFN, signaling in mammalian cells, while its effect in a heat shock response remains unclear. We used RNAi knockdown, point mutations, ChIP and promoter activity assays to study the effect of Stat1 on the heat-shock induction of the hsp90, gene under heat shock conditions. We found that Stat1 regulates the heat shock induction of its target genes, the hsp90, gene in a heat shock response while the constitutive activity of the gene remains unaffected. The result of Stat1 in complex with Stat3 and HSF1 that bound at the GAS to lead a moderate heat shock induction was designated as an "intrinsic" induction of the hsp90, gene. Additionally a reduced or an elevated level of heat shock induction was also controlled by the Stat1 on hsp90,. These diverse effects on the hsp90, gene were a "reduced" induction with over-expressed Stat1 elicited by transfection of wild-type Stat1 or IFN, treatment, bound at the GAS as homodimer; and an "enhanced" heat shock induction with a mutation-mediated prohibition of Stat1/GAS binding. In conclusion, the status and efficacy of Stat1 bound at the GAS of its target gene are pivotal in determining the impact of Stat1 under heat shock. The results provided the first evidence on the tumor suppressor Stat1 that it could play diverse roles on its target genes under heat shock that also shed lights on patients with fever or under thermotherapy. J. Cell. Biochem. 102: 1059,1066, 2007. © 2007 Wiley-Liss, Inc. [source] JNK phosphorylates the HSF1 transcriptional activation domain: Role of JNK in the regulation of the heat shock responseJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2001Jeonghyeon Park Abstract The role of c-Jun NH2 -terminal kinase (JNK) signaling cascade in the stress-inducible phosphorylation of heat shock factor 1 (HSF1) was investigated using known agonists and antagonists of JNK. We showed that treatment of HeLa cells with MG132, a proteasome inhibitor and known JNK activator, caused the transcriptional activation domain of HSF1 to be targeted and phosphorylated by JNK2 in vivo. Dose-response and time course studies of the effects of heat shock and anisomycin treatment showed a close correlation of the activation of JNK and hyperphosphorylation of HSF1. SB203580 inhibited JNK at the 100 ,M concentration and significantly reduced the amount of hyperphosphorylated HSF1 upon heat shock or anisomycin treatment. SB203580 and dominant-negative JNK suppress hsp70 promoter-driven reporter gene expression selectively at 45°C but not at 42°C heat stress, suggesting that JNK would be preferentially associated with the protective heat shock response against severe heat stress. The possibility that JNK-mediated phosphorylation of HSF1 may selectively stabilize the HSF1 protein and confers protection to cells under conditions of severe stress is discussed. J. Cell. Biochem. 82: 326,338, 2001. © 2001 Wiley-Liss, Inc. [source] Trigger Factor and DnaK possess overlapping substrate pools and binding specificitiesMOLECULAR MICROBIOLOGY, Issue 5 2003Elke Deuerling Summary Ribosome-associated Trigger Factor (TF) and the DnaK chaperone system assist the folding of newly synthesized proteins in Escherichia coli. Here, we show that DnaK and TF share a common substrate pool in vivo. In TF-deficient cells, ,tig, depleted for DnaK and DnaJ the amount of aggregated proteins increases with increasing temperature, amounting to 10% of total soluble protein (approximately 340 protein species) at 37°C. A similar population of proteins aggregated in DnaK depleted tig+ cells, albeit to a much lower extent. Ninety-four aggregated proteins isolated from DnaK- and DnaJ-depleted ,tig cells were identified by mass spectrometry and found to include essential cytosolic proteins. Four potential in vivo substrates were screened for chaperone binding sites using peptide libraries. Although TF and DnaK recognize different binding motifs, 77% of TF binding peptides also associated with DnaK. In the case of the nascent polypeptides TF and DnaK competed for binding, however, with competitive advantage for TF. In vivo, the loss of TF is compensated by the induction of the heat shock response and thus enhanced levels of DnaK. In summary, our results demonstrate that the co-operation of the two mechanistically distinct chaperones in protein folding is based on their overlap in substrate specificities. [source] The effects of low level laser irradiation on osteoblastic cellsORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 1 2001A. R. Coombe Low level laser therapy has been used in treating many conditions with reports of multiple clinical effects including promotion of healing of both hard and soft tissue lesions. Low level laser therapy as a treatment modality remains controversial, however. The effects of wavelength, beam type, energy output, energy level, energy intensity, and exposure regime of low level laser therapy remain unexplained. Moreover, no specific therapeutic window for dosimetry and mechanism of action has been determined at the level of individual cell types. The aim of this study was to investigate the effects of low level laser irradiation on the human osteosarcoma cell line, SAOS-2. The cells were irradiated as a single or daily dose for up to 10 days with a GaAlAs continuous wave diode laser (830 nm, net output of 90 mW, energy levels of 0.3, 0.5, 1, 2, and 4 Joules). Cell viability was not affected by laser irradiation, with the viability being greater than 90% for all experimental groups. Cellular proliferation or activation was not found to be significantly affected by any of the energy levels and varying exposure regimes investigated. Low level laser irradiation did result in a heat shock response at an energy level of 2 J. No significant early or late effects of laser irradiation on protein expression and alkaline phosphatase activity were found. Investigation of intracellular calcium concentration revealed a tendency of a transient positive change after irradiation. Low level laser irradiation was unable to stimulate the osteosarcoma cells utilised for this research at a gross cell population level. The heat shock response and increased intracellular calcium indicate that the cells do respond to low level laser irradiation. Further research is required, utilising different cell and animal models, to more specifically determine the effects of low level laser irradiation at a cellular level. These effects should be more thoroughly investigated before low level laser therapy can be considered as a potential accelerator stimulus for orthodontic tooth movement. [source] Odorants as cell-type specific activators of a heat shock response in the rat olfactory mucosaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2001Virginian McMillan Carr Abstract Heat shock, or stress, proteins (HSPs) are induced in response to conditions that cause protein denaturation. Activation of cellular stress responses as a protective and survival mechanism is often associated with chemical exposure. One interface between the body and the external environment and chemical or biological agents therein is the olfactory epithelium (OE). To determine whether environmental odorants affect OE HSP expression, rats were exposed to a variety of odorants added to the cage bedding. Odorant exposure led to transient, selective induction of HSP70, HSC70, HSP25, and ubiquitin immunoreactivities (IRs) in supporting cells and subepithelial Bowman's gland acinar cells, two OE non-neuronal cell populations involved with inhalant biotransformation, detoxification, and maintenance of overall OE integrity. Responses exhibited odor specificity and dose dependency. HSP70 and HSC70 IRs occurred throughout the apical region of supporting cells; ubiquitin IR was confined to a supranuclear cone-shaped region. Electron microscopic examination confirmed these observations and, additionally, revealed odor-induced formation of dense vesicular arrays in the cone-like regions. HSP25 IR occurred throughout the entire supporting cell cytoplasm. In contrast to classical stress responses, in which the entire array of stress proteins is induced, no increases in HSP40 and HSP90 IRs were observed. Extended exposure to higher odorant doses caused prolonged activation of the same HSP subset in the non-neuronal cells and severe morphological damage in both supporting cells and olfactory receptor neurons (ORNs), suggesting that non-neuronal cytoprotective stress response mechanisms had been overwhelmed and could no longer adequately maintain OE integrity. Significantly, ORNs showed no stress responses in any of our studies. These findings suggest a novel role for these HSPs in olfaction and, in turn, possible involvement in other normal neurophysiological processes. J. Comp. Neurol. 432:425,439, 2001. © 2001 Wiley-Liss, Inc. [source] Cloning and nucleotide sequencing of three heat shock protein genes (hsp90, hsc70, and hsp19.5) from the diamondback moth, Plutella xylostella (L.) and their expression in relation to developmental stage and temperatureARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2006Shoji Sonoda Abstract Heat shock protein genes, hsp90, hsc70, and hsp19.5, were cloned and sequenced from the diamondback moth, Plutella xylostella (L.) by RT-PCR and RACE method. The cDNA sequence analysis of hsp90 and hsp19.5 revealed open reading frames (ORFs) of 2,151 and 522 bp in length, which encode proteins with calculated molecular weights of 82.4 and 19.5 kDa, respectively. Analysis of cDNA from hsc70 revealed an ORF of 1,878 bp coding a protein with a calculated molecular weight of 69.3 kDa. Furthermore, the analysis of genomic DNA from hsc70 confirmed the presence of introns while no introns were apparent in hsp90 and hsp19.5. Southern blot analysis suggested the presence of multiple copies of each gene family in the DBM genome. Detectable expression of hsp19.5 was observed at the pupal stage while expression of hsp90 and hsc70 was detected at both pupal and adult stages. At adult stage, females showed a higher expression of hsp90 and hsc70 than males. An increased expression was observed in all three genes after exposure to a high temperature in both sexes. These results suggest that in addition to a heat shock response, these HSP genes might be involved in other functions during the course of development in DBM. Arch. Insect Biochem. Physiol. 62:80,90, 2006. © 2006 Wiley-Liss, Inc. [source] Preparing undergraduates to participate in the post-genome era: A capstone laboratory experience in proteomics,BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 6 2003Eric S. Eberhardt Abstract Proteomics is one of the important new disciplines to emerge from the genome sequencing projects of the last decade. In order to introduce our students to the techniques and promise of this emerging field, a capstone laboratory experience has been developed. The exercise involves multiple aspects of proteomics research including microbial culturing methods, two-dimensional gel electrophoresis techniques, matrix-assisted laser desorption-ionization time-of-flight mass spectrometry, and database mining. Over a 12-week semester, students design their own experiments and apply a proteomic approach to investigate the heat shock response in Escherichia coli. In the trial presented in this article, students successfully identified several major heat shock proteins. The laboratory outlined here can be readily adapted to explore a wide variety of responses in metabolic pathways or responses resulting from other environmental insults or stresses. Additionally, the laboratory can be modified to explore the proteomes of organelles, tissues, and other model organisms. [source] Animal performance and stress: responses and tolerance limits at different levels of biological organisationBIOLOGICAL REVIEWS, Issue 2 2009Karin S. Kassahn ABSTRACT 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, cell cycle arrest or apoptosis, changes in cellular metabolism that reflect the transition from a state of cellular growth to one of cellular repair, the release of stress hormones, changes in mitochondrial densities and properties, changes in oxygen transport capacities and changes in cardio-respiratory function. Changes at the transcriptional level recapitulate these common responses, with many stress-responsive genes functioning in cell cycle control, regulation of transcription, protein turnover, metabolism, and cellular repair. These common transcriptional responses to stress appear coordinated by only a limited number of stress-inducible and redox-sensitive transcription factors and signal transduction pathways, such as the immediate early genes c-fos and c-jun, the transcription factors NF,B and HIF - 1,, and the JNK and p38 kinase signalling pathways. As an example of environmental stress responses, we present temperature response curves at organismal, cellular and molecular levels. Acclimation and physiological adjustments that can shift the threshold temperatures for the onset of these responses are discussed and include, for example, adjustments of the oxygen delivery system, the heat shock response, cellular repair system, and transcriptome. Ultimately, however, an organism's ability to cope with environmental change is largely determined by its ability to maintain aerobic scope and to prevent loss in performance. These systemic constraints can determine an organism's long-term survival well before cellular and molecular functions are disturbed. The conceptual model we propose here discusses some of the crosslinks between responses at different levels of biological organisation and the central role of oxygen balance and oxidative stress in eliciting these responses with the aim to help the interpretation of environmental genomic data in the context of organismal function and performance. [source] Heat shock proteins as emerging therapeutic targetsBRITISH JOURNAL OF PHARMACOLOGY, Issue 6 2005Csaba Sõti Chaperones (stress proteins) are essential proteins to help the formation and maintenance of the proper conformation of other proteins and to promote cell survival after a large variety of environmental stresses. Therefore, normal chaperone function is a key factor for endogenous stress adaptation of several tissues. However, altered chaperone function has been associated with the development of several diseases; therefore, modulators of chaperone activities became a new and emerging field of drug development. Inhibition of the 90 kDa heat shock protein (Hsp)90 recently emerged as a very promising tool to combat various forms of cancer. On the other hand, the induction of the 70 kDa Hsp70 has been proved to be an efficient help in the recovery from a large number of diseases, such as, for example, ischemic heart disease, diabetes and neurodegeneration. Development of membrane-interacting drugs to modify specific membrane domains, thereby modulating heat shock response, may be of considerable therapeutic benefit as well. In this review, we give an overview of the therapeutic approaches and list some of the key questions of drug development in this novel and promising therapeutic approach. British Journal of Pharmacology (2005) 146, 769,780. doi:10.1038/sj.bjp.0706396 [source] Global regulation of virulence and the stress response by CsrA in the highly adapted human gastric pathogen Helicobacter pyloriMOLECULAR MICROBIOLOGY, Issue 1 2004Faye M. Barnard Summary Although successful and persistent colonization of the gastric mucosa depends on the ability to respond to changing environmental conditions and co-ordinate the expression of virulence factors during the course of infection, Helicobacter pylori possesses relatively few transcriptional regulators. We therefore investigated the contribution of the regulatory protein CsrA to global gene regulation in this important human pathogen. CsrA was necessary for full motility and survival of H. pylori under conditions of oxidative stress. Loss of csrA expression deregulated the oxidant-induced transcriptional responses of napA and ahpC, the acid induction of napA, cagA, vacA, the urease operon, and fur, as well as the heat shock responses of napA, groESL and hspR. Although the level of napA transcript was higher in the csrA mutant, its stability was similar in the wild-type and mutant strains, and less NapA protein was produced in the mutant strain. Finally, H. pylori strains deficient in the production of CsrA were significantly attenuated for virulence in a mouse model of infection. This work provides evidence that CsrA has a broad role in regulating the physiology of H. pylori in response to environmental stimuli, and may be important in facilitating adaptation to the different environments encountered during colonization of the gastric mucosa. Furthermore, CsrA appears to mediate its effects in H. pylori at the post-transcriptional level by influencing the processing and translation of target transcripts, with minimal effect on the stability of the target mRNAs. [source] | ||||||||||||||||