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Results for “Environmental stress”

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At least 19 recordsLinked to original sources
PubMed2000

Multiple pathways regulating fission yeast mitosis upon environmental stresses.

Environmental signals, such as nutrient availability and physiological stresses, modulate the cell cycle and cell size of the fission yeast Schizosaccharomyces pombe. However, little is known about how these signals are transmitted to the central cell cycle regulator, Cdc2, the cyclin-dependent kinase that induces mitosis. We show here genetic evidence that medium alkalization stimulates mitosis and consequently reduces cell size, either through the Nim1-Wee1 cascade, which regulates the inhibitory phosphorylation of Cdc2 at Tyr(15), or through the Cdc2-activating phosphatase, Cdc25. Alkaline stress stimulates phosphorylation of Nim1, accumulation of Cdc25 and dephosphorylation of Cdc2 at Tyr(15). We also show that osmostress stimulates mitosis through two independent pathways: one stimulates accumulation of Cdc25, and another dephosphorylation of Cdc2 at Tyr(15). However, our analysis demonstrates that these environmental stresses can stimulate mitosis independently of dephosphorylation of Cdc2 at Tyr(15). The S. pombe MAP kinase, Spc1, was required for the steady-state level of Cdc25 in the normal cell cycle and for its accumulation in response to alkaline stress and nutritional starvation.

CDC2 Protein Kinase↗
PubMed1994

[Effect of calcium antagonist (benidipine) and alpha 1 blocker (urapidil) on renal hemodynamic responses to two acute environmental stresses in spontaneously hypertensive rats (SHR)].

Renal hemodynamic responses were studied in spontaneously hypertensive rats (SHR) and Wistar-Kyoto Rats (WKY) to two acute stresses: environmental stress (foot shock (FS) and air jet (AS)). The effects of calcium channel blocker (benidipine) and alpha 1 blocker (urapidil) on these responses were studied using an ultrasonic pulsed Doppler flowmeter. The increments in mean arterial pressure (MAP) and renal vascular resistance (RVR) were greater in SHR during both stresses. On the other hand, the decrease in the renal blood flow (RBF) with these stresses almost disappeared with renal denervation. These renal hemodynamic responses in SHR disappeared with alpha 1 blocker (urapidil), but not with calcium channel blocker (benidipine). The sympathetic nervous system became hyperactive in SHR under environmental stress, Which induced specific renal hemodynamic change. These results suggest that investigations on essential hypertension should focus on clarifying not only systemic hypertensive reaction, but also changes in renal hemodynamics. Furthermore, it is necessary for antihypertensive therapy to take these hemodynamic changes into consideration.

Acute Disease↗
PubMed1986

Renal nerve activity and renal function during environmental stress in DOCA-NaCl rats.

The effects of a stressful environmental stimulus (air stress) on mean arterial pressure, heart rate, renal sympathetic nerve activity, and renal function were studied in conscious deoxycorticosterone acetate-sodium chloride (DOCA-NaCl) hypertensive rats, sham DOCA-NaCl normotensive rats, and DOCA-NaCl rats with renal denervation. In conscious DOCA-NaCl hypertensive rats, air stress decreased urine flow rate [36% from 17.9 +/- 3.0 microliter X min-1 X 100 g body wt-1 (BW)], urinary sodium excretion (39% from 3.1 +/- 0.5 microeq X min-1 X 100 g BW-1), fractional water excretion (24% from 4.72 +/- 1.00%), and fractional sodium excretion (28% from 5.72 +/- 1.08%) and increased renal sympathetic nerve activity (94% from 8.3 +/- 0.6 integrator resets/min), but no changes occurred in glomerular filtration rate (-15% from 0.40 +/- 0.06 ml X min-1 X 100 g BW-1) or effective renal plasma flow (-7% from 2.50 +/- 0.53 ml X min-1 X 100 g BW-1). Air stress had no effect on these measures in conscious sham DOCA-NaCl normotensive rats or DOCA-NaCl rats with renal denervation. Mean arterial pressure and heart rate were unaffected by air stress in these three groups. Renal denervation lowered base-line mean arterial pressure in DOCA-NaCl rats. Thus DOCA-NaCl hypertensive rats respond to environmental stress with increased renal sympathetic nerve activity and, consequently, antidiuresis and antinatriuresis.

Air↗
PubMed1985

Renal responses to stressful environmental stimuli.

The effects of stressful environmental stimuli on urinary sodium excretion in conscious dogs, rats, and humans are reviewed. Environmental stress can increase sympathetic neural outflow and decrease sodium excretion. The antinatriuretic response to environmental stress is accompanied by an unchanged renal blood flow and glomerular filtration rate, which indicates mediation via an increased renal tubular sodium reabsorption. The antinatriuresis resulting from environmental stress is associated with increased renal sympathetic nerve activity, and is abolished by surgical renal denervation. In the central nervous system, but not in the kidney, beta adrenoceptors mediate the increased renal sympathetic nerve activity and antinatriuretic responses to environmental stress. The increased renal sympathetic nerve activity and antinatriuretic responses to environmental stress are greater in spontaneously hypertensive rats (SHR) than in normotensive Wistar-Kyoto (WKY) rats. In SHR, but not WKY rats, the increased renal sympathetic nerve activity and antinatriuretic responses are enhanced by a high-sodium diet. Similarly, stressful competition in human young adult males results in an antinatriuresis only if a positive family history of hypertension is present. Thus, environmental stress can increase renal tubular sodium reabsorption via a central beta-adrenoceptor mechanism with activation of the renal sympathetic nerves in both conscious dogs and SHR. The antinatriuretic response to environmental stress is greater in rats and humans with a genetic predisposition to develop hypertension.

Adult↗
PubMed1993

Clinical study on the effectiveness of tear drainage with a single canalicular system under environmental stress.

Sixteen asymptomatic volunteers had their right lower puncta occluded with a Freeman silicone plug. They then went about their normal daily activities for approximately 1 week under the stress of a cold Chicago winter. Of the 16 eyes that were plugged, 4 had epiphora. The episodes were of short duration and did not have any effect on the subjects' daily activities. When comparing the incidence of epiphora between the plugged eyes and the control eyes, there was no statistically significant difference (p = 0.082). Also, when comparing the modified Jones I test and Schirmer tests, with and without anesthesia, there was no significant difference in the values between the plugged and the control eyes (p > 0.05). The only difference noted was in the dye disappearance test (p < 0.05). These results support the hypothesis that in selected patients, even under stressful environmental conditions, a single healthy canaliculus may provide sufficient tear drainage from a normal eye to prevent bothersome subjective symptoms.

Adult↗
PubMed2000

The relationships among objective and subjective environmental stress levels and serum uric acid: the moderating effect of perceived control.

This study was designed to investigate the effects of objective and subjective stress levels and perceived control on serum uric acid (SUA). Respondents were 2,504 male and 1,176 female manufacturing employees. Objective job-related stress was assessed by the Ergonomic Stress Level (ESL) inventory (S. Melamed, D. Yekutieli, P. Froom, E. Kristal-Boneh, & J. Ribak, 1999). As expected, ESL was positively associated with SUA, but among male respondents only. The measure of subjective stress, environmental annoyance, was negatively related with SUA for male respondents, thus not confirming the hypothesis. Perceived control was not found to have a direct effect on SUA, after controlling for the ESL measure. For male respondents only, perceived control moderated the relationship between ESL and SUA: This relationship was negative for those reporting above-average control and positive for those reporting below-average control.

Adult↗
PubMed1994

[Induction of gene expression of cancer-related genes by environmental stresses].

Many environmental elements induce the stress response in organisms. In order to examine whether the space condition brings cancer causing on mammals, we propose the importance of the study about the effects of various environmental stresses on the gene expression of oncogenes and tumor-suppressor genes. Then we reviewed numerous findings about the induction of gene expression by environmental stresses. Many investigators have reported that three oncogenes of c-fos, c-jun and c-myc, so called "Early Response Genes", were induced at transcriptional level by a diverse set of stresses such as heat, UV and ionizing radiation, and that the accumulation of the product of a tumor-suppressor gene, p53 was induced at post-translational level by the same stresses.

Animals↗
PubMed2006

Stressed out! Effects of environmental stress on mRNA metabolism.

Exposure of yeast cells to environmental stresses can disrupt essential intracellular processes, especially those carried out by large macromolecular complexes. The production of mature, translatable mRNAs is most sensitive to stress owing to the inhibition of messenger RNA splicing and alterations in the export of mRNA from the nucleus. Changes in the cytoplasmic pools of mRNAs also occur following exposure to stress conditions. Messenger RNAs accumulate in discrete cytoplasmic foci such as processing bodies and stress granules. These dynamic changes in RNA metabolism, following exposure to stress, ensure the preferential production and export of heat-shock mRNAs and the sequestering of general cellular mRNAs in the nucleus or in cytoplasmic foci, thus allowing for a redirection of the translational machinery to encode stress proteins, which aid in cellular recovery following stress. Stress proteins, such as Hsp70p and Hsp104p, have been shown to play a direct role in the repair of macromolecular complexes involved in RNA metabolism in yeast cells, thus ensuring that the cell returns to homeostasis.

Cell Nucleus↗
PubMed1997

Genetic and environmental stress, and the persistence of populations.

Many populations of endangered species have to cope both with stressful and deteriorating environmental conditions (mostly the primary cause of the endangerment) and with an increase in homozygosity due to genetic drift and/or inbreeding in small isolated populations. The latter will result in genetic stress often accompanied by a decrease in fitness (inbreeding depression). We have studied the consequences of genetic stress, under optimal as well as stressful environmental conditions, for the fitness and persistence of small populations using Drosophila melanogaster as a model system. The results show that, already under optimal environmental conditions, an increase in homozygosity or inbreeding both impairs fitness and increases the extinction risk of populations significantly. Under environmental stress, however, these effects become greatly enhanced. More important, the results show that the impact of environmental stress becomes significantly greater for higher inbreeding levels. This explicitly demonstrates that genetic and environmental stress are not independent but can act synergistically. This apparent interaction may have important consequences for the conservation of endangered species.

Animals↗
PubMed1996

Identification and characterization of the Yersinia enterocolitica gsrA gene, which protectively responds to intracellular stress induced by macrophage phagocytosis and to extracellular environmental stress.

Yersinia enterocolitica is able to resist the microbicidal mechanisms of macrophages and to grow within phagocytic cells. Some bacteria including Y. enterocolitica have been shown to respond to the hostile environment in macrophages by producing a set of stress proteins which are also induced by environmental stresses. To understand the role of stress proteins in intracellular survival of bacteria, we identified and cloned a Y. enterocolitica gene, called gsrA (global stress requirement). The gsrA gene was identified because its insertional inactivation by a transposon resulted in the inability of the organism to grow at an elevated temperature and to survive within macrophages after phagocytosis. The gsrA gene was sequenced and shown to encode a basic, 49,500-Da protein. The GsrA protein shows significant amino acid sequence homology to the HtrA stress protein which was originally identified in Escherichia coli. Furthermore, the genetically defined Y. enterocolitica gsrA mutant was constructed and characterized. The insertional mutation of gsrA resulted in inhibition of growth at temperatures above 39 degrees C and greatly increased susceptibility to oxidative and osmotic stresses. The mutant additionally lost the ability to survive and replicate within macrophages. These results, taken together, indicate that the gsrA gene is an essential component of the protection mechanism employed by Y. enterocolitica, allowing it to respond to the intracellular stress in macrophages as well as extracellular environmental stress.

Amino Acid Sequence↗
PubMed1992

[Neurobiology of physical environmental stress].

Although effects of physical environmental stress, including noise and whole-body vibration, on human psychological activities and emotion are not negligible for environmental and occupational hygiene, attempts to elucidate their physiological and biomedical mechanisms have been not made until recently. Neurobiological researches on the effects of the physical environment, e.g., noise and whole-body vibration on organisms were reviewed. It has been well accepted that such effects can be classified into specific and nonspecific reactions to the stressor. Activations of the mesofrontal and the meso-accumbens dopaminergic (DA) systems and changes of frontal substance P (SP) have been reported to play a part in emotional changes and to be induced by acute physical environmental stressors as a nonspecific reaction. On the basis of data demonstrating that these three systems do not show the same changes with the chronic exposure, it is assumed that emotional changes may account for the differences among the systems. Specific responses of amygdaline DA and SP to noise suggest that the psychopharmacological mechanisms by which actions of DA and SP in the cortical association areas for the sensory systems of hearing, as well as in the amygdala and the mesencephalon together, cause the specific sensation of noise, and furthermore lead to psychological and physical nonspecific reactions. In these mechanisms, descending amygdalofugal neural systems of SP, neurotensin (NT) and somatostatin are activated as a common pathway, and subsequently relayed to the hypothalamus-pituitary system responsible for several endocrinological hormones. The involvements of the hippocampal VIP in whole-body vibration and of the DA and NT in cold exposure have been pointed out. Further researches to elucidate the roles of central neurotransmitters in physical environmental stress will be important in the study of human high-level mental activity.

Animals↗
PubMed2000

Managing Environmental Stress: An Evaluation of Environmental Management of the Long Point Sandy Barrier, Lake Erie, Canada.

/ This paper assesses the extent to which key geomorphic components, processes, and stresses have been reflected in the management of a coastal sandy barrier environment. The management policies and practices of selected agencies responsible for Long Point, a World Biosphere Reserve along Lake Erie, Canada, were evaluated for consistency with these principles of environmental management for sandy barriers: maintaining natural stresses essential to sandy barrier development and maintenance;protecting sediment sources, transfers, and storage; recognizing spatial variability and cyclicity of natural stresses, such as barrier overwash events; and accepting and planning for long-term evolutionary changes in the sandy barrier environment. Generally, management policies and practices have not respected the dynamic and sensitive environment of Long Point because of limited mandates of the agencies involved, inconsistent policies, and failure to apply or enforce existing policies. This is particularly evident with local municipalities and less so for the Canadian Wildlife Service, the federal agency responsible for managing National Wildlife Areas at the point. In the developed areas of Long Point, landward sediment transfers and sediment storage in dunes have been impacted by cottage development, shore protection, and maintenance of roads and parking lots. Additionally, agencies responsible for managing Long Point have no jurisdiction over sediment sources as far as 95 km away. Evolutionary change of sandy barriers poses the greatest challenge to environmental managers.

Journal Article↗
PubMed1989

The mediating effects of psychophysiological reactivity and recovery on the relationship between environmental stress and illness.

The present study investigated the association between psychophysiological reactivity and recovery and physical and psychological symptoms both directly and interactively with environmental stress. Symptoms, environmental stress, and psychophysiological reactivity to and recovery from a laboratory stressor were measured in 50 subjects. As in previous research, the results indicated a significant relationship between environmental stress and symptoms of illness. Although the data did not support a direct relationship between psychophysiological activity and illness, support for a buffering effect was found. Those individuals with greater physiological arousal to or slower recovery from a laboratory stressor exhibited a stronger relationship between environmental stress and symptoms than those who were less reactive or faster to recover. Implications of these results were discussed in the context of theoretical models relating stress and illness.

Arousal↗
PubMed2000

Evolution in stressful environments. I. Phenotypic variability, phenotypic selection, and response to selection in five distinct environmental stresses.

Considerable debate has accompanied efforts to integrate the selective impacts of environmental stresses into models of life-history evolution. This study was designed to determine if different environmental stresses have consistent phenotypic effects on life-history characters and whether selection under different stresses leads to consistent evolutionary responses. We created lineages of a wild mustard (Sinapis arvensis) that were selected for three generations under five stress regimes (high boron, high salt, low light, low water, or low nutrients) or under near-optimal conditions (control). Full-sibling families from the six selection histories were divided among the same six experimental treatments. In that test generation, lifetime plant fecundity and six phenotypic traits were measured for each plant. Throughout this greenhouse study, plants were grown individually and stresses were applied from the early seedling stage through senescence. Although all stresses consistently reduced lifetime fecundity and most size- and growth-related traits, different stresses had contrasting effects on flowering time. On average, stress delayed flowering compared to favorable conditions, although plants experiencing low nutrient stress flowered earliest and those experiencing low light flowered latest. Contrary to expectations of Grime's triangle model of life-history evolution, this ruderal species does not respond phenotypically to poor environments by flowering earlier. Most stresses enhanced the evolutionary potential of the study population. Compared with near-optimal conditions, stresses tended to increase the opportunity for selection as well as phenotypic variance, although both of these quantities were reduced in some stresses. Rather than favoring traits characteristic of stress tolerance, such as slow growth and delayed reproduction, phenotypic selection favored stress-avoidance traits: earlier flowering in all five stress regimes and faster seedling height growth in three stresses. Phenotypic correlations reinforced direct selection on these traits under stress, leading to predicted phenotypic change under stress, but no significant selection in the control environment. As a result of these factors, selection under stress resulted in an evolutionary shift toward earlier flowering. Environmental stresses may drive populations of ruderal plant species like S. arvensis toward a stress-avoidance strategy, rather than toward stress tolerance. Further studies will be needed to determine when selection in stressful environments leads to these alternative life-history strategies.

Biological Evolution↗
PubMed1989

Effect of environmental stress on neural control of renal function.

Environmental stress increases renal sympathetic nerve activity and decreases urinary sodium excretion to a greater degree in conscious hypertensive rats (spontaneously hypertensive rat; deoxycorticosterone-sodium chloride, Dahl salt-sensitive) than normotensive control rats. The dependence of the antinatriuretic response to environmental stress on the renal sympathetic nerves is indicated by the finding that renal denervation prevents the response. Central nervous system beta 2- and alpha 2-adrenoceptors mediated the renal sympathetic nerve activity and antinatriuretic responses to environmental stress in conscious spontaneously hypertensive rats. Increased renal sympathetic nerve activity and renal sodium retention may contribute to chronic stress hypertension.

Animals↗
PubMed2006

Copper sulphate and DCMU-herbicide treatments increase asymmetry between sister cells in the toxic cyanobacteria Microcystis aeruginosa: implications for detecting environmental stress.

Works correlating fluctuating asymmetry with environmental stress or genetic damages have been largely reported in multicellular organisms but not in single-celled ones. We hypothesize that asymmetry analysis could also be applied to single-celled organisms, because the asymmetry between two sister cells originated from a cellular division event (same genotype in similar environment) must tend to zero in the absence of environmental or genetic perturbations. Laboratory experiments with copper sulphate and DCMU-herbicide treatments as well as experiments in a water reservoir after treatment with copper sulphate algaecide show that environmental stress increases asymmetry between sister cells of Microcystis aeruginosa (Cyanobacteria). Even low Cu(2+) or DCMU doses, which were unable to reduce growth rate, considerably enlarge asymmetry with respect to untreated controls. Asymmetry between sister cells of cyanobacteria seems to be a reliable indicator of environmental perturbation. Analysis of asymmetry in single-celled organisms could become as important as fluctuating asymmetry of multicellular organisms is today.

Bacterial Toxins↗
PubMed1997

Gender differences in distress: mental health consequences of environmental stress among jail inmates.

The present study examines the influence of gender and environmental stress on the mental health of a sample of 198 male and female jail inmates. Environmental stress is conceptualized as the degree of congruence between inmates' demand and the jail's supply of several environmental features. A state of incongruence was hypothesized to increase the mental distress of jail inmates. In addition, it was hypothesized that female inmates would have higher levels of distress than male inmates, with environmental stress as a possible explanation for gender differences in distress. Female inmates were found to have significantly higher levels of mental distress than males. However, environmental stress was found to be equally detrimental to the mental health of both male and female inmates. Thus, although congruence between environmental demand and supply is a significant predictor of mental health, it is not an explanation for the alarmingly high levels of mental distress found among female inmates.

Cross-Sectional Studies↗