Different Types Of Environmental Stress Research Articles

Poliovirus infection induces the co-localization of cellular protein SRp20 with TIA-1, a cytoplasmic stress granule protein

Different types of environmental stress cause mammalian cells to form cytoplasmic foci, termed stress granules, which contain mRNPs that are translationally silenced. These foci are transient and dynamic, and contain components of the cellular translation machinery as well as certain mRNAs and RNA binding proteins. Stress granules are known to be induced by conditions such as hypoxia, nutrient deprivation, and oxidative stress, and a number of cellular factors have been identified that are commonly associated with these foci. More recently it was discovered that poliovirus infection also induces the formation of stress granules, although these cytoplasmic foci appear to be somewhat compositionally unique. Work described here examined the punctate pattern of SRp20 (a host cell mRNA splicing protein) localization in the cytoplasm of poliovirus-infected cells, demonstrating the partial co-localization of SRp20 with the stress granule marker protein TIA-1. We determined that SRp20 does not co-localize with TIA-1, however, under conditions of oxidative stress, indicating that the close association of these two proteins during poliovirus infection is not representative of a general response to cellular stress. We confirmed that the expression of a dominant negative version of TIA-1 (TIA-1-PRD) results in the dissociation of stress granules. Finally, we demonstrated that expression of wild type TIA-1 or dominant negative TIA-1-PRD in cells during poliovirus infection does not dramatically affect viral translation. Taken together, these studies provide a new example of the unique cytoplasmic foci that form during poliovirus infection.

FSRD: fungal stress response database

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.Database URL: http://internal.med.unideb.hu/fsrd

Antioxidants in Different Potato Genotypes: Effect of Drought and Wounding Stress

Potatoes are regarded as a significant antioxidant source in human nutrition. However, different types of environmental stress may affect the level of antioxidants in their tuber tissue. In this study, two purple breeding clones and the yellow fleshed cultivar (cv.) Agave were grown in the glasshouse under control with drought stress conditions for two consecutive years. After harvest, the tubers were analysed for concentrations of antioxidants measured as ascorbic acid equivalent (ACE) and trolox equivalent (TXE) in fresh tissue and after wounding. In addition, the peroxidase enzyme (POD) activities and total amounts of anthocyanins (Ac) were assayed. Drought stress caused a significant decrease in tuber yield but had no significant effect on Ac, POD, ACE and TXE. Wounding stress significantly induced the POD activity in control and drought stressed tubers of all genotypes. Also the ACE and TXE were notably increased by wounding in cv. Agave. This was less pronounced in the purple clones which in general displayed a higher level of antioxidants. The results revealed significant differences between genotypes and that the effect of drought stress on the level of antioxidants is smaller than that of wounding stress.

The spectral response of Buxus sempervirens to different types of environmental stress – A laboratory experiment

The European Mediterranean regions are expected to encounter drier summer conditions and warmer temperatures for the winter of +2°C and of +5°C for the summer in the next six decennia. As a result the natural vegetation will face harsher conditions due to lower water availability, longer summer droughts and higher temperatures resulting in plant stress conditions. To monitor vegetation conditions like stress and leaf area index dynamics in our study area in Mediterranean France we use earth observation techniques like imaging spectroscopy. To assist image analysis interpretation we carried out a laboratory experiment to investigate the spectral and visible response of Buxus sempervirens, a common Mediterranean species, to five different types of stress: drought, drought-and-heat, light deprivation, total saturation and chlorine poisoning. For 52days plants were subjected to stress. We collected data on the visible and spectral signs, and calculated thirteen vegetation indices. The plant’s response time to different stress types varied from 10 to 32days. Spectroscopic techniques revealed plant stress up to 15days earlier than visual inspection. Visible signs of stress of the plants included curling and shrinking of the leaves, de-colouring of the leaves, leaves becoming breakable, opening up of the plant’s canopy and sagging of the branches. Spectral signs of stress occurred first in the water absorption bands at 1450 and 1940nm, followed by reduced absorption in the visible wavelengths, and next by reduced reflectance in near infrared. Light deprivation did not result in any stress signs, while drought, drought and heat and chlorine poisoning resulted in significant stress. The spectral response did not show differences for different stress types. Analysis of the vegetation indices identified the Carter-2 (R695/R760), the Red–Green Index (R690/R550) and the Vogelman-2 (R734−R747)/(R715+R726) as the best performing ones to identify stress. The lab experiment shows that spectroscopic techniques are useful to detect stress status of plants and in an earlier stage than visible signs of stress become apparent, but that spectroscopy does not reveal the type of plant stress.

Diversity and composition of fungal endophytes in semiarid Northwest Venezuela

Fungal endophytes grow asymptomatically within the tissues of all vascular plants and some are known to provide their host plants with tolerance to different types of environmental stress. The diversity and incidence of fungal endophytes has been negatively correlated with latitude. However, fungal endophyte communities from arid and semiarid environments do not follow this pattern, arguably due to their extreme conditions. In this study, fungal endophytes were cultured from dominant grasses and sedges growing at three different environments in the neotropical semiarid region of Northwest Venezuela. Operational Taxonomic Units were clearly differentiated using phylogenetic analysis of the ITSrDNA region. The results indicated that the incidence and diversity of fungal endophytes in these samples were comparable with those in other tropical plant communities and those in semiarid temperate grasslands. The most common OTUs within the grasses and sedges were related to Cochliobolus sp. and Phoma sp. (Order Pleosporales). This supports the notion that dark septate fungal endophytes dominate semiarid grasslands worldwide.

A Novel Mechanism for SUMO System Control: Regulated Ulp1 Nucleolar Sequestration

The small ubiquitin-related modifiers (SUMOs) are evolutionarily conserved polypeptides that are covalently conjugated to protein targets to modulate their subcellular localization, half-life, or activity. Steady-state SUMO conjugation levels increase in response to many different types of environmental stresses, but how the SUMO system is regulated in response to these insults is not well understood. Here, we characterize a novel mode of SUMO system control: in response to elevated alcohol levels, the Saccharomyces cerevisiae SUMO protease Ulp1 is disengaged from its usual location at the nuclear pore complex (NPC) and sequestered in the nucleolus. We further show that the Ulp1 region previously demonstrated to interact with the karyopherins Kap95 and Kap60 (amino acids 150 to 340) is necessary and sufficient for nucleolar targeting and that enforced sequestration of Ulp1 in the nucleolus significantly increases steady-state SUMO conjugate levels, even in the absence of alcohol. We have thus characterized a novel mechanism of SUMO system control in which the balance between SUMO-conjugating and -deconjugating activities at the NPC is altered in response to stress via relocalization of a SUMO-deconjugating enzyme.

Differential responses of sweetpotato peroxidases to heavy metals

Oxidative stress is one of the major causes of damage in plants exposed to different types of environmental stress, including heavy metals. Accumulation of heavy metals in plants can disrupt many cellular functions and plant growth. To assess the contribution of oxidative stress to heavy metal toxicity in plants, young sweetpotato plants ( Ipomoea batatas) were treated with increasing concentrations of Cd, Cu and Zn, and grown in half Murashige and Skoog nutrient solution culture. Plant growth was significantly inhibited and internal metal content was increased in a dose-dependent manner for each metal. The generation of H 2O 2 in leaves and fibrous roots correlated positively with metal dose. The specific activity of peroxidases (PODs) in fibrous roots was markedly enhanced by metal treatment, whereas in leaves, activity was low and only slightly affected by metal treatment. Analysis of 13 POD genes revealed differential expression of PODs in response to heavy metals. Several genes for acidic PODs ( swpa2, swpa3 and swpa4) and basic PODs ( swpb1, swpb3 and swpab4) were strongly expressed under all metal treatment conditions in leaves or fibrous roots. The expression of swpa1 was increased in leaves and fibrous roots by Cd and Cu treatment, whereas swpb5 expression was reduced by all metals in fibrous roots. These results indicate that increased H 2O 2 levels in response to heavy metal stress are closely linked to an improved antioxidant defense capability mediated by POD.

The 26S Proteasome Function and Hsp90 Activity Involved in the Regulation of HsfA2 Expression in Response to Oxidative Stress

Heat shock transcription factor A2 (HsfA2) is induced under environmental stress and regulates transcription of various defense-related genes. Thus HsfA2 plays an important role in induction of defenses against different types of environmental stress, but its mode of regulation remains unknown. To clarify the signal transduction pathway involved in the regulation of HsfA2 expression, we investigated the effect of MG132, a 26S proteasome inhibitor, or geldanamycin (GDA), a heat shock protein 90 (Hsp90) inhibitor, on the transcription of HsfA2 and its targets, Hsp18.1-CI and ascorbate peroxidase 2 (Apx2), in Arabidopsis T87 cells. The levels of transcripts were significantly increased by treatment with MG132 or GDA. Overexpression of a dexamethazone-inducible dominant-negative form of Hsp90.2 in Arabidopsis plants caused significant expression of HsfA2 and its target gene on treatment with the compound. Treatment with MG132 or GDA had no effect on intracellular levels of reactive oxygen species (ROS). Interestingly, the levels of polyubiquitinated proteins as well as the levels of HsfA2 transcript were rapidly increased under oxidative stress derived from treatment with H2O2 or methylviologen, while they were completely suppressed by pre-treatment with ascorbate, a scavenger of ROS, under oxidative stress. The present findings suggest that the inhibition of 26S proteasome function and/or Hsp90 activity is involved in the induction of HsfA2 expression in response to oxidative stress.

PHYSIOLOGICAL RESPONSE OF SOME TOMATO GENOTYPES (LYCOPERSICON ESCULENTUM L.) TO HIGH TEMPERATURE STRESS

Cultivated plants are often exposed to different types of environmental stress, which limits their development and productivity. High temperature stress induces considerable changes in the biochemistry and physiology of plants. The aim of the present investigation was to evaluate the physiological response of some tomato genotypes to a high temperature stress. Experiments were carried out during the stress period and after its elimination. Valuation of the tolerance of plants was carried out by means of a physiological test. It was observed that the high temperature stress has an inhibitory effect on the physiological state of tomato plants. The degree of its inhibited action was individual, depending on the genotype.

Response of taxonomic groups in streams to gradients in resource and habitat characteristics

SummaryCompared to other ecosystem types, a wide variety of biomonitoring methods are available for rivers. Few studies have, however, compared the response of bioindicators (i.e. different river inhabiting taxonomic groups) to different types of environmental stress.We regressed diversity, taxonomic distinctness and assemblage composition of fish, invertebrates, macrophytes and benthic diatoms to multivariate gradients in nutrient enrichment and habitat degradation using data from 66 lowland and 77 mountain streams.In lowland streams, the composition of benthic diatom assemblages, measured by Detrended Correspondence Analysis, showed the strongest response to elevated nutrient concentrations (R2 = 0·830), followed by macrophytes (0·711), fish (0·443) and invertebrates (0·391). Macrophyte richness was slightly better correlated with the habitat gradient (0·253) than diatom richness (0·235) and both were better predictors than either fish (0·147) or invertebrate (0·140) assemblage composition.For mountain streams, invertebrate assemblage composition was the best predictor of changes in nutrient concentrations (R2 = 0·749), followed by macrophyte (0·396) and benthic diatom (0·325) assemblages and fish diversity (0·099). Invertebrate assemblage composition was also slightly better correlated with the habitat gradient (0·391) compared to macrophyte richness (0·323) and both were better than either benthic diatom assemblage composition (0·206) or fish abundance (0·161).Macrophyte and benthic diatom assemblages in lowland streams and fish and invertebrate assemblages in mountain streams were correlated with the other taxonomic groups, implying that these taxonomic groups may be used as surrogates for indicating wholesale change in diversity.Synthesis and applications. Our findings show that response trajectories differ between taxonomic groups and stressor, and even with stream type. For this reason, streams and other ecosystem type's response signatures and first and second principle relations should be considered in the selection of robust, complementary and cost‐effective measures for biomonitoring. For instance, our findings of asymmetric response to stress show how different taxonomic groups can be used to strengthen inference of change.

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

BackgroundOur 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.ResultsWe 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, a total of 324 gene loci were differentially expressed. Many heat-responsive genes had functions associated with protein turnover, metabolism, and the response to oxidative stress. We were also able to identify groups of co-regulated genes, the genes within which shared similar functions.ConclusionThis is the first environmental genomic study to measure gene regulation in response to different environmental stressors in a natural population of a warm-adapted ectothermic vertebrate. We have shown that different types of environmental stress induce expression changes in genes with similar gene functions, but that the responses of individual genes vary between stress types. The functions of heat-responsive genes suggest that prolonged heat exposure leads to oxidative stress and protein damage, a challenge of the immune system, and the re-allocation of energy sources. This study hence offers insight into the effects of environmental stress on biological function and sheds light on the expected sensitivity of coral reef fishes to elevated temperatures in the future.

GroES/GroEL and DnaK/DnaJ Have Distinct Roles in Stress Responses and during Cell Cycle Progression inCaulobacter crescentus

Misfolding and aggregation of protein molecules are major threats to all living organisms. Therefore, cells have evolved quality control systems for proteins consisting of molecular chaperones and proteases, which prevent protein aggregation by either refolding or degrading misfolded proteins. DnaK/DnaJ and GroES/GroEL are the best-characterized molecular chaperone systems in bacteria. In Caulobacter crescentus these chaperone machines are the products of essential genes, which are both induced by heat shock and cell cycle regulated. In this work, we characterized the viabilities of conditional dnaKJ and groESL mutants under different types of environmental stress, as well as under normal physiological conditions. We observed that C. crescentus cells with GroES/EL depleted are quite resistant to heat shock, ethanol, and freezing but are sensitive to oxidative, saline, and osmotic stresses. In contrast, cells with DnaK/J depleted are not affected by the presence of high concentrations of hydrogen peroxide, NaCl, and sucrose but have a lower survival rate after heat shock, exposure to ethanol, and freezing and are unable to acquire thermotolerance. Cells lacking these chaperones also have morphological defects under normal growth conditions. The absence of GroE proteins results in long, pinched filamentous cells with several Z-rings, whereas cells lacking DnaK/J are only somewhat more elongated than normal predivisional cells, and most of them do not have Z-rings. These findings indicate that there is cell division arrest, which occurs at different stages depending on the chaperone machine affected. Thus, the two chaperone systems have distinct roles in stress responses and during cell cycle progression in C. crescentus.

Regulation of genes encoding subunits of the trehalose synthase complex in Saccharomyces cerevisiae: novel variations of STRE-mediated transcription control?

Saccharomyces cerevisiae cells show under suboptimal growth conditions a complex response that leads to the acquisition of tolerance to different types of environmental stress. This response is characterised by enhanced expression of a number of genes which contain so-called stress-responsive elements (STREs) in their promoters. In addition, the cells accumulate under suboptimal conditions the putative stress protectant trehalose. In this work, we have examined the expression of four genes encoding subunits of the trehalose synthase complex, GGS1/TPS1, TPS2, TPS3 and TSL1. We show that expression of these genes is coregulated under stress conditions. Like for many other genes containing STREs, expression of the trehalose synthase genes is also induced by heat and osmotic stress and by nutrient starvation, and negatively regulated by the Ras-cAMP pathway. However, during fermentative growth only TSL1 shows an expression pattern like that of the STRE-controlled genes CTT1 and SSA3, while expression of the three other trehalose synthase genes is only transiently down-regulated. This difference in expression might be related to the known requirement of trehalose biosynthesis for the control of yeast glycolysis and hence for fermentative growth. We conclude that the mere presence in the promoter of (an) active STRE(s) does not necessarily imply complete coregulation of expression. Additional mechanisms appear to fine tune the activity of STREs in order to adapt the expression of the downstream genes to specific requirements.

Psychoneuroimmunology: An area of interest for the psychopharmacologist?

Anecdotal evidence suggesting a causal relationship between psychiatric illness, environmental stress and a malfunctioning immune system goes back to antiquity. Recently, clinical and experimental studies have established the interrelationship between neuro- endocrine regulation, the immune system and abnormalities in central neurotransmission which may be deranged as a consequence of stressful events. This short review is an attempt to assess the evidence implicating altered immune responsiveness in depression and to consider the impact of different types of environmental stress in triggering the immune malfunction. While these findings are of considerable biological importance, it is presently unclear whether the immunological changes are primary or secondary to the disease states.

Stress, the immune system and psychiatric illness

AbstractAnecdotal evidence suggesting a causal relationship between psychiatric illness, environmental stress and a malfunctioning immune system goes back to antiquity. Recently, clinical and experimental studies have established the interrelationship between neuroendocrine regulation, the immune system and abnormalities in central neurotransmission which may be deranged as a consequence of stressful events. This short review is an attempt to assess the evidence implicating altered immune responsiveness in depression and schizophrenia and to consider the impact of different types of environmental stress in triggering the immune malfunction. While these findings are of considerable biological importance, it is presently unclear whether the immunological changes are primary or secondary to the disease states.

Dynamic fragility concepts for equipment design and qualification

Fragility concepts are explored for use in the design and qualification of nuclear plant equipment and for relating the ultimate capability of equipment to that of the overall plant. In the most general sense, the fragility level of a device may depend on several different types of environmental stress or challenge factors (i.e., heat, nuclear radiation, vibration, etc.) that influence its operation. However, emphasis is concentrated on the dynamic and particularly the seismic fragility levels of equipment. A general definition of dynamic fragility and various methods for its measurement are described. The state of published data on nuclear equipment fragility is discussed, and limitations on its use are noted. From there, the concept of a standardized seismic fragility data base and its potential uses are considered. Various gaps in the methodology are identified, and recommendations for further research are suggested.