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Artigos de revistas sobre o assunto "Stress (Psychology) Physiological effect"
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Hoareau, Violette, Christelle Godin, Frédéric Dutheil e Marion Trousselard. "The Effect of Stress Management Programs on Physiological and Psychological Components of Stress: The Influence of Baseline Physiological State". Applied Psychophysiology and Biofeedback 46, n.º 3 (12 de maio de 2021): 243–50. http://dx.doi.org/10.1007/s10484-021-09508-0.
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AbstractMilitary personnel are particularly exposed to stressful events, and overexposure to stress is both physically and mentally unhealthy. While stress management programs, such as the Tactics of Optimized Potential (TOP) and Heart Coherence (HC) have been implemented, their efficiency remains to be evaluated. The objective of this randomized control trial was to evaluate the effectiveness of the two programs among a young male population of 180 military fire fighter recruits. Based on two psychological, and one physiological measurement, namely heart rate variability (HRV), we found that both TOP and HC programs significantly increased HRV. This is promising as we know that higher HRV is consistent with better health, in most cases. Moreover, the TOP program significantly reduced perceived stress and negative mood, unlike the HC program. Combining these results, we conclude that while both TOP and HC programs influence physiological measurements, only the TOP modifies psychological evaluations. Finally, we distinguished the effects of the programs on two samples characterized by their HRV level. For the low HRV group, both programs tended to increase their HRV level, while for the high HRV group neither program had a significant effect.
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Rusconi, Maria Luisa, Stefano F. Cappa, Michele Scala e Francesca Meneghello. "A Lexical Stress Effect in Neglect Dyslexia." Neuropsychology 18, n.º 1 (2004): 135–40. http://dx.doi.org/10.1037/0894-4105.18.1.135.
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Kotlyar, Michael, Mustafa al’Absi, Paul Thuras, John P. Vuchetich, David E. Adson, April L. Nowack e Dorothy K. Hatsukami. "Effect of Paroxetine on Physiological Response to Stress and Smoking". Psychosomatic Medicine 75, n.º 3 (abril de 2013): 236–43. http://dx.doi.org/10.1097/psy.0b013e3182898f6d.
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Kemeny, Margaret E. "The Psychobiology of Stress". Current Directions in Psychological Science 12, n.º 4 (agosto de 2003): 124–29. http://dx.doi.org/10.1111/1467-8721.01246.
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Stressful life experience can have significant effects on a variety of physiological systems, including the autonomic nervous system, the hypothalamic-pituitary-adrenal axis, and the immune system. These relationships can be bidirectional; for example, immune cell products can act on the brain, altering mood and cognition, potentially contributing to depression. Although acute physiological alterations may be adaptive in the short term, chronic or repeated provocation can result in damage to health. The central dogma in the field of stress research assumes a stereotyped physiological response to all stressors (the generality model). However, increasing evidence suggests that specific stressful conditions and the specific way an organism appraises these conditions can elicit qualitatively distinct emotional and physiological responses (the integrated specificity model). For example, appraisals of threat (vs. challenge), uncontrollability, and negative social evaluation have been shown to provoke specific psychobiological responses. Emotional responses appear to have specific neural substrates, which can result in differentiated alterations in peripheral physiological systems, so that it is incorrect to presume a uniform stress response.
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Wofford, J. C. "Cognitive–Affective Stress Response: Effects of Individual Stress Propensity on Physiological and Psychological Indicators of Strain". Psychological Reports 88, n.º 3 (junho de 2001): 768–84. http://dx.doi.org/10.2466/pr0.2001.88.3.768.
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The purpose of this study was to define further the role of individual stress propensity in physiological arousal and subsequent subjective stress and strain by measuring stress-induced reactivity in a laboratory setting. Individual predisposition to stress is conceptualized as a latent construct, cognitive–affective stress propensity, that is manifested as multiple trait indicators, e.g., negative affectivity, anger-irritability, and negative self-esteem. For 80 undergraduates experimental treatments were two stressors, time pressure and performance feedback. Physiological arousal indices included skin temperature, blood volume, and electromyographic activity. Results provide some support for the hypotheses that this propensity moderates the relationships between stressor and physiological arousal and between physiological arousal and subjective stress and strain.
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Martimportugués-Goyenechea, Clara, e Luis Gómez-Jacinto. "Simultaneous Multiple Stressors in the Environment: Physiological Stress Reactions, Performance, and Stress Evaluation". Psychological Reports 97, n.º 3 (dezembro de 2005): 867–74. http://dx.doi.org/10.2466/pr0.97.3.867-874.
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Interactive effects of two environmental stressors when simultaneously present, i.e., noise and crowding, were analyzed. Four experimental conditions with two intensities of stress for each stressor (high versus low) were created. The stressors were concurrently introduced in laboratory conditions and their effects analyzed using several methodological approaches. More intense and negative effects were expected when the two highest intensities of noise and crowding concurred. 40 people (20 men and 20 women) participated in a study with a 2 × 2 factorial design. Analysis showed an increase in the measures of hemodynamic, endocrine, and neuroendocrine values of participants after being exposed simultaneously to noise and crowding. Similarly, their performance on complex tasks decreased, and they reported a subjective increase in stress. Capacity to cope was indicated by a statistically significant lower mean on the Dimension of Stress scale, tolerance of frustration during the multiple stress condition.
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Stepanova, Elena V., David J. Echevarria, Adam D. Collier, Cristobal S. Cruz, Nafiyah Kirkland e David J. Drobes. "Discrimination, Stress and Reactivity to Alcohol Cues". Journal of Social and Clinical Psychology 38, n.º 10 (dezembro de 2019): 836–59. http://dx.doi.org/10.1521/jscp.2019.38.10.836.
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Introduction: Our study investigated whether discrimination affects psychologi-cal/physiological stress and alcohol craving. Method: Participants (N = 92) were asked to recall and write about (a) a neutral, (b) a negative, or (c) a discriminatory experience in the past and then completed a cue-reactivity procedure assessing their alcohol craving. In addition, we assessed levels of perceived stress before and after the discrimination manipulation, chronic substance use and craving, prior perceived discrimination, and strength of racial/ethnic identity. Results: Results revealed a small effect in which the discrimination condition increased alcohol cue-elicited craving relative to the other conditions. Chronic craving moderated effects of discrimination on cortisol levels. Self-reported stress levels were increased in the discrimination and negative memory conditions relative to baseline. Strength of racial identity served as a protective factor for substance abuse in those who reported chronic high levels of discrimination. Discussion: We discussed the direct link established between acute exposure to discrimination and craving, and experimental evidence for the relationship between discrimination and self-reported stress, but also addressed potential limitations of this work. It is further discussed how some individual differences factors (e.g., chronic craving) predict physiological stress in discriminatory settings. This work underscored the role of racial identity as a protective factor against alcohol abuse in individuals reporting high levels of discrimination.
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Hartman, Sarah, Sara M. Freeman, Karen L. Bales e Jay Belsky. "Prenatal Stress as a Risk—and an Opportunity—Factor". Psychological Science 29, n.º 4 (7 de fevereiro de 2018): 572–80. http://dx.doi.org/10.1177/0956797617739983.
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Two separate lines of research indicate (a) that prenatal stress is associated with heightened behavioral and physiological reactivity and (b) that these postnatal phenotypes are associated with increased susceptibility to both positive and negative developmental experiences. Therefore, prenatal stress may increase sensitivity to the rearing environment. We tested this hypothesis by manipulating prenatal stress and rearing-environment quality, using a cross-fostering paradigm, in prairie voles. Results showed that prenatally stressed voles, as adults, displayed the highest behavioral and physiological reactivity when cross-fostered to low-contact (i.e., low-quality) rearing but the lowest behavioral and physiological reactivity when cross-fostered to high-contact (i.e., high-quality) rearing; non-prenatally stressed voles showed no effect of rearing condition. Additionally, while neither prenatal stress nor rearing condition affected oxytocin receptor binding, prenatally stressed voles cross-fostered to high-contact rearing showed the highest vasopressin-1a receptor binding in the amygdala. Results indicate that prenatal stress induces greater environmental sensitivity, making it both a risk and an opportunity factor.
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Deffenbacher, Jerry L., e Jeffrey M. Shepard. "Evaluating a Seminar on Stress Management". Teaching of Psychology 16, n.º 2 (abril de 1989): 79–81. http://dx.doi.org/10.1207/s15328023top1602_11.
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A psychology seminar on stress management is described and evaluated. Though instruments changed in six classes over a 6- year period, students reported significantly less general anxiety, general anger, situational stress reactivity, and stress-related physiological reactivity after the class than before. Follow-ups conducted with two classes showed maintenance of these effects. These results suggest that the classroom can be a practical medium for increasing academic knowledge about and personal skills for stress reduction.
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Ennis, Jeffrey, e Umair Majid. "The Widowhood Effect: Explaining the Adverse Outcomes After Spousal Loss Using Physiological Stress Theories, Marital Quality, and Attachment". Family Journal 28, n.º 3 (3 de junho de 2020): 241–46. http://dx.doi.org/10.1177/1066480720929360.
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The loss of a loved one is one of the most ubiquitous life experiences. There have been multiple reviews that have found adverse health outcomes for individuals experiencing spousal loss, particularly the widowhood effect that characterizes an increased risk of mortality after loss. However, there is a lack of clarity on the relationship between physiological stress and the widowhood effect. This commentary uses the literature on stress, marital quality, and attachment to explain the widowhood effect and other adverse physical health outcomes. We discuss three points: (1) the chronic nature of stress may be the source of adverse outcomes, (2) the quality and quantity of available resources may moderate the effects of stress, and (3) the level and style of attachment may explain why these outcomes may persist many years after spousal loss.
Teses / dissertações sobre o assunto "Stress (Psychology) Physiological effect"
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Poirier, Patrick. "Effect of chronic stress on prefrontal cortical function". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86861.
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The prefrontal cortex (PFC) is a brain region thought to mediate cognitive functions such as working memory. Chronic stress has been shown to reduce working memory. In this thesis study, the effect of chronic stress on PFC functions was assessed in adult rats.First, contrary to previous evidences, chronic stress induces working memory performance alterations differentially in two populations of rats. One group displayed a decrease of performance only at 30 second delay, while the other had a decrease and increase at 0 and 30 seconds respectively.
Then, the effect of chronic stress on synaptic plasticity induction in the hippocampus-PFC network was investigated. High-frequency tetanic stimulation (HFS) of the dorsal hippocampus that induced long-term potentiation (LTP) in the prelimbic and infralimbic cortex in normal conditions was unable to induce LTP after chronic stress in the infralimbic cortex, whereas long-term depression (LTD) instead of LTP was induced in the prelimbic cortex.
Given that synaptic plasticity has been shown to depend on NMDA receptors in the PFC, NMDA subunit expressions before and after chronic stress was examined. There was a decrease of NR1 subunits expression in the prelimbic, but not infralimbic cortex. In contrast, the NR2A/NR2B ratio was increased in the infralimbic, but not prelimbic cortex. These results suggest that chronic stress disrupts PFC functions through dynamic modulation of distinct neural networks within the PFC.
Le cortex préfrontal (PFC) est une région du cerveau qui contrôle les fonctions cognitives comme la mémoire de travail. Dans cette thèse, l'effet du stress chronique sur des fonctions du PFC a été analysé chez des rats adultes.
Premièrement, les performances de la mémoire de travail ont été mesurées avant et après exposition au stress chronique. Nous avons constaté que le stress chronique induit des changements de performances de la mémoire de travail différemment selon deux populations de rats. Une des populations a démontré une diminution de performance seulement à 30 secondes de délai. Au contraire, l'autre a démontré une diminution de performance à 0 seconde et une amélioration de performance à 30 secondes.
En plus, nous avons évalué l'effet du stress chronique sur l'induction de la plasticité synaptique dans le réseau reliant l'hippocampe au PFC. Dans les conditions initiales, une stimulation tétanique à haute fréquence (HFS) dans l'hippocampe dorsal provoquait une potentialisation à long terme (LTP) dans le cortex prélimbique et infralimbique Or après exposition au stress chronique, une stimulation tétanique à haute fréquence n'a pas entraîné de potentialisation à long terme dans le cortex infralimbique. De plus, une exposition au stress chronique a provoqué l'apparition dans le cortex prélimbique d'une dépression à long terme (LTD) plutôt qu'une potentialisation à long terme.
Étant donné que la plasticité synaptique dépend des récepteurs de NMDA dans le PFC, nous avons examiné l'expression de sous-unité de NMDA avant et après exposition au stress chronique. En accord avec les changements synaptiques distincts de plasticité entre le cortex prélimbique et infralimbique après exposition au stress chronique, nous avons observé que l'expression de la sous-unité NR1 a diminué dans le prélimbique, mais non dans l'infralimbique. En revanche, le ratio de NR2A/NR2B a augmenté dans le cortex infralimbique, mais non dans le prélimbique. Ces résultats suggèrent que le stress chronique perturbe les fonctions du PFC par la modulation dynamique des réseaux distincts neurologiques dans le PFC.
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France, Christopher R. (Christopher Robert). "Cardiovascular responses to psychological stress and caffeine". Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74649.
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While considerable information exists regarding the independent effects of caffeine and psychological stress on cardiovascular activity, there is relatively little information on their combined effects. Since caffeine may enhance cardiovascular responsivity to psychological stress, research on hemodynamic responses to caffeine-stress combinations may help elucidate mechanisms of hypertension development. In a series of studies, regular consumers of caffeine were exposed to laboratory and naturalistic stressors with and without prior caffeine intake. Among the findings were (1) caffeine and stress produced additive increases in blood pressure, (2) caffeine appears to potentiate beta-adrenergic responsivity to active coping, but not passive coping, stressors, (3) caffeine enhanced emotional responses to stress, and (4) cardiovascular responses to caffeine and stress in a naturalistic setting were similar to those observed in the laboratory. These results indicate that caffeine may enhance cardiovascular and psychological responses to stress, and that these responses may contribute to risk for essential hypertension.
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Walker, Douglas W. (Douglas Wallace). "Effects of Experimental Psychological Stress on Human Physiological Functioning: Mediation by Affiliation". Thesis, University of North Texas, 1995. https://digital.library.unt.edu/ark:/67531/metadc277708/.
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This investigation sought to identify differences in the human psychophysiological stress response when mediated by affiliation, by assessing heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), electrodermal activity (EDA), serum Cortisol (SC) concentration, interleukin-2 (IL-2) concentration, and state anxiety among subjects who underwent an anagram solution task. Thirty male subjects from the University of North Texas were randomly assigned to one of two experimental conditions and asked to solve a series of difficult anagrams either alone or with a companion. Subjects assigned to the control condition were asked to copy permutations of the anagrams. Before, and immediately after the anagram/copying tasks HR, SBP, DBP were measured, blood samples drawn, and The State-Trait Anxiety Inventory (STAI) administered to all subjects. EDA was measured throughout all trials. Changes from baseline through the experimental period for all dependent variables were analyzed by employing difference scores derived from contrasting baseline and experimental measures. These scores were subjected to an analysis of variance (ANOVA) resulting in one significant between group effect among all dependent variables examined. Contrary to stated hypotheses, the alone condition significantly differed from the companion and control conditions by demonstrating a significant decrease in systolic blood pressure from baseline through the experimental period. It was concluded that the decrease in systolic blood pressure from baseline through the experimental period for the alone group was a result of chance sampling of individuals possessing unique psychophysiological response patterns. Appraisals of inter-group differences in response patterns across all dependent variables suggest that an insufficient stressor, and limitations in design, statistical analysis, and measurement may have contributed to this investigation's results. Implications of findings were discussed along with suggestions for future research.
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Lee, Suhyun. "Long-term metabolic effects of stress and antidepressants : a novel paradigm of antidepressant-induced weight gain in the post-stress acclimation period". Phd thesis, Canberra, ACT : The Australian National University, 2014. http://hdl.handle.net/1885/125029.
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Despite the frequent use of antidepressants and the high incidence of obesity in Australia and many other developed countries, the relationship between major depressive disorder, obesity and antidepressant use remains complex. The association between antidepressant use and body weight gain has been widely reported. However, the pathophysiological mechanisms of this association are still poorly understood. In this thesis, an animal paradigm that addresses the "paradoxical" weight loss of rodents during antidepressant treatment was developed. The paradigm referred here as the SAD model and consisting of short-term exposure to recurrent restraint stress (RRS) and antidepressant treatment for two weeks, followed by long-term high-fat diet was evaluated in male Sprague-Dawley rats for 296 days. The phenotypic characteristics of the SAD model were compared to the diet-induced obesity (DIO) model, a model of obesity solely induced by high-fat diet. Immediately after the RRS period, groups of animals that underwent RRS had significantly lower body weight in comparison to the DIO group. The rate of weight gain during the catch up growth phase was significantly greater in the SAD model than in the DIO model. During the post-restraint period, the SAD model of fluoxetine-treated group became heavier than the DIO model, however this happened only in the animals in the upper half of body weight gain, i.e. the obesity prone group. Body weight gain in the SAD model in comparison to the DIO model was referred as "SAD-induced weight gain". The SAD model of fluoxetine-treated group had significantly greater body length and enhanced morphological features of the trabecular and cortical bones in comparison to the DIO model, these findings suggest that the SAD-induced weight gain was accompanied by growth via the growth hormone (GH)/Insulin-like growth factor-I (IGF-I) somatotropic axis. However, pituitary GH and plasma IGF-I levels were not different at the end point of the experiment. Igf-1 mRNA expression in the liver was significantly higher in groups that underwent RRS, which may have occurred as a compensatory mechanism for the decreased IGF-I levels during the RRS period. We also investigated whether "SAD-induced weight gain" was accompanied by a metabolic/lipid dysregulations. Plasma leptin, cholesterol, vanilmandelic acid, and free fatty acid levels were not significantly different between groups. Thus, SAD-induced weight gain is not accompanied by further increases in fat mass or metabolic dysregulations. Our results showed that the RRS and the fluoxetine treatment result in decreased plasma triglyceride levels when compared to the DIO model. Thus, the "protective" effect of fluoxetine in metabolic dysregulations may be sustained long-term. Our results suggest that individuals who are already prone to obesity may have increased risk of weight gain with antidepressant treatment. Antidepressant-induced weight gain is more likely to be associated with growth during the post-stress acclimation period, rather than with increases in fat mass and metabolic dysregulations. However, mechanisms behind the antidepressant-induced weight gain require further investigation. This thesis has contributed towards a better understanding of long-term effects of environmental factors such as stress and diet, and antidepressants in post-stress acclimation weight gain.
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Amstadter, Ananda Beth Laura L. Vernon Laura L. Burkhart Barry R. "Physiological effects of suppression of neutral and traumatic thoughts in posttraumatic stress disorder". Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Psychology/Dissertation/AMSTADTER_ANA_20.pdf.
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Van, Stavel Rosemary. "Effects of exercise on stress : a meta-analysis". Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30159.
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Physical exercise is frequently prescribed by clinicians and researchers as an effective stress reduction technique. There has been some research to support this assertion, however the research has been varied in its methodological rigor. The design problems, variations in exercise programs, and the use of a wide range of psychological measures have made results difficult to interpret. Additionally, the psychological benefits and underlying change processes have not been clearly delineated. The purpose of this study was to conduct a meta-analysis of the research in this area in an attempt to answer specific questions regarding the role of exercise in stress reduction. This meta-analytic approach was
chosen because it permits the quantitative integration of findings of several studies and consideration of the variables that may influence the variance in study outcomes. The effectiveness of exercise as a treatment for stress, the type of exercise that was most beneficial, and the type of individual who gained the most from the exercise intervention was examined.
The 61 effect sizes, which were calculated from 24 studies included in the meta-analysis, were coded along with other variables considered important. Study components such as design type, stress level, type of exercise program, program length, frequency of exercise sessions, attrition rate, psychological measure, composition of sample, gender, and
study type were coded as independent variables. Effect size
was the dependent variable. Analysis of variance revealed that
exercise was an effective stress reducer, stressed people
gained a greater stress reduction effect than minimally
stressed people, and there were no differences between trait
and state anxiety reduction from pre- to post-exercise
program. In addition, a one-way ANOVA indicated that there was
a significant difference between program lengths. Examination
of the means revealed that an 8- to 12-week program was most
effective in reducing stress. Although there was a greater effect size for unpublished studies than published studies, the pattern of change for each study type was similar.
The significance of these results and recommendations for future studies are discussed.Education, Faculty of
Curriculum and Pedagogy (EDCP), Department of
Graduate
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Yake, Melissa L. "The effect of stress on eating practices among university faculty". Virtual Press, 2006. http://liblink.bsu.edu/uhtbin/catkey/1339600.
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The purpose of this study was to examine the relationship between comfort food preferences of college faculty when under normal (non-stressful) and stressful conditions. Thirty-four percent (n=63) of the participants were males and 66 percent (n=121) were females. Sixty-seven percent (n=123) experienced a change in appetite when stressed, with 69 percent (n=85) experiencing an increase and 31 percent (n=38) experiencing a decrease in appetite. Participants chose a significantly wider variety of foods when under stressful conditions for both sweet (p=<.001) and salty/crunchy food categories (p=.004). High restrained eaters chose significantly more types of sweet foods (p=.031) and beverages (p=.020) than low restrained eaters when comparing stressful and normal conditions. These findings suggest the majority of adults may experience changes in appetite with stress, specifically an increased appetite, and may choose more types of sweet and salty/crunchy foods. An individual's restraint level, gender, and age may also play a role in comfort food choice.Department of Family and Consumer Sciences
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Bowin, Beth Marie. "Effects of Canines on Humans' Physiological and Perceived Stress". ScholarWorks, 2019. https://scholarworks.waldenu.edu/dissertations/7368.
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The bond between pet and owner has been shown to decrease stress-related physical, mental, and emotional disorders by lowering blood pressure and heart rate. The purpose of this study was to examine whether a nonpet canine would have the same effect in reducing physical symptoms of stress as a known dog. Human-animal bond theory, Human pressor test. Data were analyzed using repeated measures, analyses of variance, and t tests. Results indicated that interaction with a strange dog lowered heart rate and blood pressure significantly faster in the experimental group than in the control group. The positive social change implications of this research include policy and procedural accommodations for the use of canines as comfort animals for individuals in stressful conditions.
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Kim, Seong-Han. "The effects of heat stress on operator perceived workload in tracking". Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-02132009-171117/.
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Sarkissian, Meline Sadanand Ghazar. "Building Spiritual Capital| The Effects of Kundalini Yoga on Adolescent Stress, Emotional Affect, and Resilience". Thesis, Loyola Marymount University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3561861.
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In order to integrate a mind, body, spirit approach in school settings, yoga programming such as Y.O.G.A. for Youth was introduced to one public and two charter schools in Los Angeles area urban neighborhoods. The study examined the effectiveness of the overall program and its effect on adolescent stress, emotional affect, and resilience. A survey was administered to measure the three dependent variables and informal interviews were conducted to determine the overall effectiveness of the program. The results of the mixed method approach indicated that the overall program was effective in creating a general sense of well-being and statistically significant in alleviating stress (p < .05), increasing positive affect (p < .05), and resilience (p < .001), in the participants (N=30).
Livros sobre o assunto "Stress (Psychology) Physiological effect"
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Moch, Annie. Les stress de l'environnemment: De la perception au stress. Saint Denis: Presses Universitaires de Vincennes, 1989.
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Hart, Archibald D. Adrenalin and stress: [the exciting new breakthrough that helps you overcome stress damage]. Dallas, Tex: Word Pub., 1991.
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Hart, Archibald D. The hidden link between adrenalin & stress: The exciting new breakthrough that helps you overcome stress damage. Waco, Tex: Word Books, 1986.
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Susan, Suffes, ed. The serotonin solution: The potent substance that can help you stop bingeing, lose weight, and feel great. New York: Fawcett Columbine, 1996.
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P, Plotnikoff Nicholas, ed. Enkephalins and endorphins: Stress and the immune system. New York: Plenum Press, 1986.
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Stress, the aging brain, and the mechanisms of neuron death. Cambridge, Mass: MIT Press, 1992.
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Stress, catecholamines, and cardiovascular disease. New York: Oxford University Press, 1995.
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K, Erickson Carlton, ed. Drugs, the brain and behavior: The pharmacology of abuse and dependence. New York, N.Y: Haworth Press, 1999.
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Pathak, Bhawani. Cold stress. Hamilton, Ont: Canadian Centre for Occupational Health and Safety, 1987.
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Knauer, Virginia H. Special report on cold stress (hypothermia) and heat stress. Washington, D.C: U.S. Office of Consumer Affairs, 1987.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Stress (Psychology) Physiological effect"
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Bhattacharya, A. "Effect of Low Temperature Stress on Photosynthesis and Allied Traits: A Review". In Physiological Processes in Plants Under Low Temperature Stress, 199–297. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-9037-2_3.
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Bhattacharya, A. "Effect of Low Temperature on Dry Matter, Partitioning, and Seed Yield: A Review". In Physiological Processes in Plants Under Low Temperature Stress, 629–734. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-9037-2_7.
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Bhattacharya, A. "Effect of Low-Temperature Stress on Germination, Growth, and Phenology of Plants: A Review". In Physiological Processes in Plants Under Low Temperature Stress, 1–106. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-9037-2_1.
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Wang, Tianhao, Chenming Li e Yan Wang. "The Effect of Personal Protective Equipment on the Physiological Stress of Rescue Workers". In Lecture Notes in Electrical Engineering, 661–69. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8779-1_75.
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Kohlmann, Carl-Walter. "Development of the Repression-Sensitization Construct: With Special Reference to the Discrepancy Between Subjective and Physiological Stress Reactions". In The Concept of Defense Mechanisms in Contemporary Psychology, 184–204. New York, NY: Springer New York, 1993. http://dx.doi.org/10.1007/978-1-4613-8303-1_12.
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Anrijs, Sarah, Klaas Bombeke, Wouter Durnez, Kristin Van Damme, Bart Vanhaelewyn, Peter Conradie, Elena Smets et al. "MobileDNA: Relating Physiological Stress Measurements to Smartphone Usage to Assess the Effect of a Digital Detox". In HCI International 2018 – Posters' Extended Abstracts, 356–63. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-92279-9_48.
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Selvakumar, Gopal, Kiyoon Kim, Shuijin Hu e Tongmin Sa. "Effect of Salinity on Plants and the Role of Arbuscular Mycorrhizal Fungi and Plant Growth-Promoting Rhizobacteria in Alleviation of Salt Stress". In Physiological Mechanisms and Adaptation Strategies in Plants Under Changing Environment, 115–44. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-8591-9_6.
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Abbas, Mohamed S., Hattem M. El-Shabrawi, Mai A. Selim e Amira Sh Soliman. "Effect of Salt Stress on Physiological and Biochemical Parameters of African Locust Bean {Parkia biglobosa (Jacq.) Benth.} Cell Suspension Culture". In Mitigating Environmental Stresses for Agricultural Sustainability in Egypt, 215–47. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-64323-2_8.
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Kapoor, Riti Thapar. "Effect of Calcium Silicate Supplementation on the Growth of Trigonella Foenum-Graecum L. Variety Hisar Sonali Under Saline Conditions". In Proceedings of the Conference BioSangam 2022: Emerging Trends in Biotechnology (BIOSANGAM 2022), 214–24. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_21.
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AbstractSalinity is a major abiotic stress which decreases crop productivity. Salt stress also causes osmotic, water, ionic and oxidative stresses. Plants exposure to salt can check their growth by reduction in water and nutrient uptake, osmotic imbalance and cytotoxicity incited by sodium and chloride ions. Present study deals with the impact of salt on germination, growth and physiological components of fenugreek and its alleviation by the application of calcium silicate. The salt stress reduced fenugreek germination and growth but supplementation of calcium silicate to salt stressed seedlings mitigated deleterious impacts of salinity. Various parameters like germination, seedling length, biomass, pigment and protein contents of fenugreek seedlings were significantly improved with calcium silicate under salt stress. Maximum reduction 53.3% in protein amount was recorded in fenugreek seedlings treated with NaCl (10 mM) over control. Significant increase in total antioxidant content in fenugreek seedlings was observed with calcium silicate as it showed the following order: Ca2SiO4 > NaCl + Ca2SiO4 > NaCl > Control. Hence, application of calcium silicate can be useful for the fenugreek plants growing under saline conditions.
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Decarli, Alessandro, Blaise Pierrehumbert, André Schulz e Claus Vögele. "Mental Health and Well-Being in Adolescence: The Role of Child Attachment and Parental Reflective Functioning". In Wohlbefinden und Gesundheit im Jugendalter, 129–49. Wiesbaden: Springer Fachmedien Wiesbaden, 2022. http://dx.doi.org/10.1007/978-3-658-35744-3_7.
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AbstractAdolescence is a sensitive developmental period, with important changes occurring at biological, cognitive, emotional and social levels. As evidenced by several studies, adolescence is also a vulnerable period for the onset of serious mental disorders, which then tend to persist into adulthood. While there is ample evidence concerning risk factors of mental disorders in adolescence, a lot less is known about protective factors: however, one important protective factor to have emerged from recent research concerns attachment security. The aim of the current paper is to explore the effects of attachment on emotion regulation (in terms of physiological reactivity), autonomy and relatedness, and behavioral problems in adolescence, and how attachment is in turn influenced by parental reflective functioning (PRF), parenting behaviors (operationalized in terms of behaviors promoting and undermining autonomy relatedness) and parenting stress (in terms of cortisol reactivity). The findings point to the potential utility of interventions aimed at enhancing attachment security, thus allowing a better psychological adjustment, and at improving PRF, especially in divorced families, given its protective effect on parenting stress and parenting behaviors.
Trabalhos de conferências sobre o assunto "Stress (Psychology) Physiological effect"
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Seiter, Natasha. "Mindful Partnering and Lesser Biological Stress". In 7th International Conference on Spirituality and Psychology. Tomorrow People Organization, 2022. http://dx.doi.org/10.52987/icsp.2022.006.
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Abstract Mindful partnering is a newly conceptualized construct to measure interpersonal mindfulness in the relationship with one's intimate partner. Mindful partnering is characterized by mindful awareness toward one’s partner as well as compassion and acceptance of one’s partner. We hypothesized that higher levels of mindful partnering would be associated with lesser physiological reactivity to relationship conflict (i.e., less biological stress during relationship conflict). Seventeen couple pairs (N= 34) visited the laboratory to complete several tasks, including questionnaires and a conflict discussion in which they discussed the largest areas of conflict in their relationship. Participants had their Respiratory Sinus Arrythmia (RSA), a measure of nervous system activation, measured during the baseline period and conflict discussion. Participants completed the Mindful Partnering Measure (MPM) to measure the extent to which one demonstrates mindful partnering in their relationship with their romantic partner, including the subscales of MPM- Mindful Awareness and MPM- Acceptance/Compassion. Regression analyses suggested that MPM-Mindful Awareness significantly predicted partner’s greater RSA, indicating that 9% of the variance in RSA was accounted for by partner’s MPM- mindful awareness (a small effect), suggesting greater relaxation and a less pronounced stress response. These results suggest that when one’s partner is fully present and attentive, it may relieve the potential stress of marital disagreement. Being present with full attention in this way may soothe a partner’s nervous system by creating a feeling of being fully listened to and understood in the context of conflict. Keywords: Mindfulness, Marriage, Marital Conflict, Respiratory Sinus Arrythmia, Physiological Reactivity
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Pertsov, Sergey. "CYTOKINES IN NEUROIMMUNE REGULATION OF PHYSIOLOGICAL FUNCTIONS DURING STRESS LOADS". In XVIII INTERNATIONAL INTERDISCIPLINARY CONGRESS NEUROSCIENCE FOR MEDICINE AND PSYCHOLOGY. LCC MAKS Press, 2022. http://dx.doi.org/10.29003/m2885.sudak.ns2022-18/267-268.
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Riaz, Roha, Nuzhat Naz, Mnahil Javed, Farhat naz e Hamza Toor. "Effect of Mental Workload Related Stress on Physiological Signals". In 2020 IEEE-EMBS Conference on Biomedical Engineering and Sciences (IECBES). IEEE, 2021. http://dx.doi.org/10.1109/iecbes48179.2021.9398833.
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Jan, Zala, Christian Gostečnik e Veronika Kralj-Iglič. "Adverse Human Health Outcomes Associated with Psychologi-cal Trauma: A review". In Socratic Lectures 7. University of Lubljana Press, 2022. http://dx.doi.org/10.55295/psl.2022.d7.
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Until 30 years ago it was believed that psychological stress increases cortisol secretion, but later stud-ies gave contradictory results. Decrease in cortisol levels in post-traumatic stress disorder (PTSD) reflects a nonnormative and inadequate response to severe stressors, with its pathophysiology in-volving maladaptation or dysfunction in stress-regulatory systems. To have more insights in re-sponse of human body to physiological stress, inflammatory signals, oxidative stress parameters and other health parameters were measured. As for the cortisol level results, also inflammatory signals, including proinflammatory and anti-inflammatory cytokines and C-reactive protein (CRP), have been reported to increase and decrease in PTSD. Levels of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumour necrosis factor (TNF)-α, interferon gamma (IFN-γ) and CRP were reported higher and lower in blood samples of individuals with PTSD. Some studies report that dysregulation of the stress axis could have direct effects on brain regions responsible for the regulation of fear and anxiety (such as the prefrontal cortex, insula, amygdala, and hippocampus). Early-life stress, such as child-hood adversity (abuse, neglect, or family disfunction), is a potent risk factor for developing PTSD in response to later trauma, and elevated peripheral markers of inflammation are one of the best-repli-cated findings in children and adults with early-life stress. Those who develop PTSD may have an inability or failure to activate an innate immune response. PTSD can also result in other adverse outcomes, such as heightened oxidative stress (OXS), eating disorders, metabolic disorder, and car-diovascular disease (CVD). Since the results are very contradictory for PTSD and inflammation re-sponse of the human body, further research is important. Small cellular particles that can be isolated from body fluids present potential biomarkers of the clinical status and will be considered in plan-ning the future research. This contribution presents perspectives in assessment of psychological stress by objective parameters. Keywords: Cortisol; Post-traumatic stress disorder; Inflammatory response; Oxidative stress; Cyto-kines; Eating disorders; Metabolic disorder; Cardiovascular disease; Small cellular particles as stress markers, Extracellular vesicles as stress markers
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Medvedeva, Nina. "THE DESTRUCTIVE EFFECT OF STRESS ENVIRONMENT ON THE EMOTIONAL HEALTH OF A PERSON". In XV International interdisciplinary congress "Neuroscience for Medicine and Psychology". LLC MAKS Press, 2019. http://dx.doi.org/10.29003/m486.sudak.ns2019-15/295-296.
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Broshevitskaya, Nadezda, Irina Pavlova e Maria Zaichenko. "THE EFFECT OF EARLY-LIFE PROINFLUMMATORY STRESS ON SOCIAL BEHAVIOR OF ADULT WISTAR RATS". In XVIII INTERNATIONAL INTERDISCIPLINARY CONGRESS NEUROSCIENCE FOR MEDICINE AND PSYCHOLOGY. LCC MAKS Press, 2022. http://dx.doi.org/10.29003/m2700.sudak.ns2022-18/81-82.
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Karmiyati, Diah, e Siti Zuhana Sari. "The Comparison Between Laughter and Seft Therapies Effect Towards Stress for The Elderly People". In 3rd ASEAN Conference on Psychology, Counselling, and Humanities (ACPCH 2017). Paris, France: Atlantis Press, 2018. http://dx.doi.org/10.2991/acpch-17.2018.37.
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Kolesnikova, Inna, Natalia Budennaya, Yurii Severiukhin, Kristina Lyakhova, Dina Utina e Victor Gaevsky. "THE EFFECT ON MORPHOLOGICAL CHANGES IN THE CENTRAL NERVOUS SYSTEM AND PHYSIOLOGICAL MEASUREMENTS OF AGED MICE AFTER TOTAL IRRADIATION BY GAMMA RAYS". In XVII INTERNATIONAL INTERDISCIPLINARY CONGRESS NEUROSCIENCE FOR MEDICINE AND PSYCHOLOGY. LCC MAKS Press, 2021. http://dx.doi.org/10.29003/m2165.sudak.ns2021-17/193-194.
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Zhang, Enze, Lijin Lin, Mingjun Miao, Yanhong Li e Yi Tang. "Effect of Spraying Indoleacetic acid on Physiological Characteristics of Aluminum Stress of Chinese cabbage seedlings". In 2017 6th International Conference on Energy and Environmental Protection (ICEEP 2017). Paris, France: Atlantis Press, 2017. http://dx.doi.org/10.2991/iceep-17.2017.197.
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Xu, Jingtao, Jian Zhang, Congcong Zhao, Cong Li, Huijun Xie e Shanshan Wang. "Effect of Ammonia Stress on Physiological and Biochemical Character of Phragmites australis in Constructed Wetland". In 2012 Third International Conference on Digital Manufacturing and Automation (ICDMA). IEEE, 2012. http://dx.doi.org/10.1109/icdma.2012.83.
Texto completo da fonteRelatórios de organizações sobre o assunto "Stress (Psychology) Physiological effect"
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Bolek, Kevin J., e Michael E. Persia. The Effect of Chick Methionine Status on Broiler Performance and Physiological Response to Acute and Chronic Heat Stress. Ames (Iowa): Iowa State University, janeiro de 2013. http://dx.doi.org/10.31274/ans_air-180814-821.
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Mosquna, Assaf, e Sean Cutler. Systematic analyses of the roles of Solanum Lycopersicum ABA receptors in environmental stress and development. United States Department of Agriculture, janeiro de 2016. http://dx.doi.org/10.32747/2016.7604266.bard.
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Drought and other abiotic stresses have major negative effects on agricultural productivity. The plant hormone abscisic acid (ABA) regulates many responses to environmental stresses and can be used to improve crop performance under stress. ABA levels rise in response to diverse abiotic stresses to coordinate physiological and metabolic responses that help plants survive stressful environments. In all land plants, ABA receptors are responsible for initiating a signaling cascade that leads to stomata closure, growth arrest and large-scale changes in transcript levels required for stress tolerance. We wanted to test the meaning of root derived ABA signaling in drying soil on water balance. To this end we generated transgenic tomato lines in which ABA signaling is initiated by a synthetic agonist- mandipropamid. Initial study using a Series of grafting experiments indicate that that root ABA signaling has no effect on the immediate regulation of stomata aperture. Once concluded, these experiments will enable us to systematically dissect the physiological role of root-shoot interaction in maintaining the water balance in plants and provide new tools for targeted improvement of abiotic stress tolerance in crop plants.
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Fromm, Hillel, e Joe Poovaiah. Calcium- and Calmodulin-Mediated Regulation of Plant Responses to Stress. United States Department of Agriculture, setembro de 1993. http://dx.doi.org/10.32747/1993.7568096.bard.
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We have taken a molecular approach to clone cellular targets of calcium/calmodulin (Ca2+/CaM). A 35S-labeled recombinant CaM was used as a probe to screen various cDNA expression libraries. One of the isolated clones from petunia codes for the enzyme glutamate decarboxylase (GAD) which catalyzes the conversion of glutamate to g-aminobutyric acid (GABA). The activity of plant GAD has been shown to be dramatically enhanced in response to cold and heat shock, anoxia, drought, mechanical manipulations and by exogenous application of the stress phytohormone ABA in wheat roots. We have purified the recombinant GAD by CaM-affinity chromatography and studied its regulation by Ca2+/CaM. At a physiological pH range (7.0-7.5), the purified enzyme was inactive in the absence of Ca2+ and CaM but could be stimulated to high levels of activity by the addition of exogenous CaM (K0.5 = 15 nM) in the presence of Ca2+ (K 0.5 = 0.8 mM). Neither Ca2+ nor CaM alone had any effect on GAD activity. Transgenic tobacco plants expressing a mutant petunia GAD lacking the CaM-binding domain, or transgenic plants expressing the intact GAD were prepared and studied in detail. We have shown that the CaM-binding domain is necessary for the regulation of glutamate and GABA metabolism and for normal plant development. Moreover, we found that CaM is tightly associated with a 500 kDa GAD complex. The tight association of CaM with its target may be important for the rapid modulation of GAD activity by Ca2+ signaling in response to stresses.
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Cohen, Roni, Kevin Crosby, Menahem Edelstein, John Jifon, Beny Aloni, Nurit Katzir, Haim Nerson e Daniel Leskovar. Grafting as a strategy for disease and stress management in muskmelon production. United States Department of Agriculture, janeiro de 2004. http://dx.doi.org/10.32747/2004.7613874.bard.
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The overall objective of this research was to elucidate the horticultural, pathological, physiological and molecular factors impacting melon varieties (scion) grafted onto M. cannonballus resistant melon and squash rootstocks. Specific objectives were- to compare the performance of resistant melon germplasm (grafted and non-grafted) when exposed to M. cannoballus in the Lower Rio Grande valley and the Wintergarden, Texas, and in the Arava valley, Israel; to address inter-species relationships between a Monosporascus resistant melon rootstock and susceptible melon scions in terms of fruit-set, fruit quality and yield; to study the factors which determine the compatibility between the rootstock and the scion in melon; to compare the responses of graft unions of differing compatibilities under disease stress, high temperatures, deficit irrigation, and salinity stress; and to investigate the effect of rootstock on stress related gene expression in the scion. Some revisions were- to include watermelon in the Texas investigations since it is much more economically important to the state, and also to evaluate additional vine decline pathogens Didymella bryoniae and Macrophomina phaseolina. Current strategies for managing vine decline rely heavily on soil fumigation with methyl bromide, but restrictions on its use have increased the need for alternative management strategies. Grafting of commercial melon varieties onto resistant rootstocks with vigorous root systems is an alternative to methyl bromide for Monosporascus root rot/vine decline (MRR/VD) management in melon production. Extensive selection and breeding has already produced potential melon rootstock lines with vigorous root systems and disease resistance. Melons can also be grafted onto Cucurbita spp., providing nonspecific but efficient protection from a wide range of soil-borne diseases and against some abiotic stresses, but compatibility between the scion and the rootstock can be problematic. During the first year experiments to evaluate resistance to the vine decline pathogens Monosporascus cannonballus, Didymella bryoniae, and Macrophomina phaseolina in melon and squash rootstocks proved the efficacy of these grafted plants in improving yield and quality. Sugars and fruit size were better in grafted versus non-grafted plants in both Texas and Israel. Two melons (1207 and 124104) and one pumpkin, Tetsukabuto, were identified as the best candidate rootstocks in Texas field trials, while in Israel, the pumpkin rootstock RS59 performed best. Additionally, three hybrid melon rootstocks demonstrated excellent resistance to both M. cannonballus and D. bryoniae in inoculated tests, suggesting that further screening for fruit quality and yield should be conducted. Experiments with ABA in Uvalde demonstrated a significant increase in drought stress tolerance and concurrent reduction in transplant shock due to reduced transpiration for ‘Caravelle’ plants. In Israel, auxin was implicated in reducing root development and contributing to increased hydrogen peroxide, which may explain incompatibility reactions with some squash rootstocks. However, trellised plants responded favorably to auxin (NAA) application at the time of fruit development. Gene expression analyses in Israel identified several cDNAs which may code for phloem related proteins, cyclins or other factors which impact the graft compatibility. Manipulation of these genes by transformation or traditional breeding may lead to improved rootstock cultivars. Commercial applications of the new melon rootstocks as well as the ABA and TIBA growth regulators have potential to improve the success of grafted melons in both Israel and Texas. The disease resistance, fruit quality and yield data generated by the field trials will help producers in both locations to decide what rootstock/scion combinations will be best.
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Meiri, Noam, Michael D. Denbow e Cynthia J. Denbow. Epigenetic Adaptation: The Regulatory Mechanisms of Hypothalamic Plasticity that Determine Stress-Response Set Point. United States Department of Agriculture, novembro de 2013. http://dx.doi.org/10.32747/2013.7593396.bard.
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Our hypothesis was that postnatal stress exposure or sensory input alters brain activity, which induces acetylation and/or methylation on lysine residues of histone 3 and alters methylation levels in the promoter regions of stress-related genes, ultimately resulting in long-lasting changes in the stress-response set point. Therefore, the objectives of the proposal were: 1. To identify the levels of total histone 3 acetylation and different levels of methylation on lysine 9 and/or 14 during both heat and feed stress and challenge. 2. To evaluate the methylation and acetylation levels of histone 3 lysine 9 and/or 14 at the Bdnfpromoter during both heat and feed stress and challenge. 3. To evaluate the levels of the relevant methyltransferases and transmethylases during infliction of stress. 4. To identify the specific localization of the cells which respond to both specific histone modification and the enzyme involved by applying each of the stressors in the hypothalamus. 5. To evaluate the physiological effects of antisense knockdown of Ezh2 on the stress responses. 6. To measure the level of CpG methylation in the promoter region of BDNF in thermal treatments and free-fed, 12-hour fasted, and re-fed chicks during post-natal day 3, which is the critical period for feed-control establishment, and 10 days later to evaluate longterm effects. 7. The phenotypic effect of antisense “knock down” of the transmethylaseDNMT 3a. Background: The growing demand for improvements in poultry production requires an understanding of the mechanisms governing stress responses. Two of the major stressors affecting animal welfare and hence, the poultry industry in both the U.S. and Israel, are feed intake and thermal responses. Recently, it has been shown that the regulation of energy intake and expenditure, including feed intake and thermal regulation, resides in the hypothalamus and develops during a critical post-hatch period. However, little is known about the regulatory steps involved. The hypothesis to be tested in this proposal is that epigenetic changes in the hypothalamus during post-hatch early development determine the stress-response set point for both feed and thermal stressors. The ambitious goals that were set for this proposal were met. It was established that both stressors i.e. feed and thermal stress, can be manipulated during the critical period of development at day 3 to induce resilience to stress later in life. Specifically it was established that unfavorable nutritional conditions during early developmental periods or heat exposure influences subsequent adaptability to those same stressful conditions. Furthermore it was demonstrated that epigenetic marks on the promoter of genes involved in stress memory are altered both during stress, and as a result, later in life. Specifically it was demonstrated that fasting and heat had an effect on methylation and acetylation of histone 3 at various lysine residues in the hypothalamus during exposure to stress on day 3 and during stress challenge on day 10. Furthermore, the enzymes that perform these modifications are altered both during stress conditioning and challenge. Finally, these modifications are both necessary and sufficient, since antisense "knockdown" of these enzymes affects histone modifications, and as a consequence stress resilience. DNA methylation was also demonstrated at the promoters of genes involved in heat stress regulation and long-term resilience. It should be noted that the only goal that we did not meet because of technical reasons was No. 7. In conclusion: The outcome of this research may provide information for the improvement of stress responses in high yield poultry breeds using epigenetic adaptation approaches during critical periods in the course of early development in order to improve animal welfare even under suboptimum environmental conditions.
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Pesis, Edna, Elizabeth J. Mitcham, Susan E. Ebeler e Amnon Lers. Application of Pre-storage Short Anaerobiosis to Alleviate Superficial Scald and Bitter Pit in Granny Smith Apples. United States Department of Agriculture, janeiro de 2013. http://dx.doi.org/10.32747/2013.7593394.bard.
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There is increased demand for high quality fruit produced and marketed with reduced chemical inputs to minimize toxic effects on human health and the environment. Granny Smith (GS) apple quality is reduced by two major physiological disorders, superficial scald and bitter pit (BP). These disorders cause great loss to apple growers worldwide. Superficial scald is commonly controlled by chemical treatments, mainly the antioxidant diphenylamine (DPA) and/or the ethylene action inhibitor, 1-methylcyclopropene (1–MCP). Both chemicals are ineffective in controlling bitter pit incidence. We proposed to investigate the beneficial use of non-chemical, abiotic stress with low O2 (LO2) applied for 10d at 20°C on GS apple fruit. During the project we expanded the treatment to more apple cultivars, Golden Delicious (GD) and Starking Delicious (SD) and another pome fruit, the pear. Apple and pear have similar physiological disorders that develop during cold storage and we examined if the LO2 treatment would also be effective on pear. Application of 0.5% LO2 atmosphere for 10d at 20°C or 500ppb 1-MCP at 20°C prior to cold storage at 0°C, was effective in reducing superficial scald in GS apple. Moreover, LO2 pretreatment was also effective in reducing bitter pit (BP) development in California GS and Israeli GD and SD apples The BP symptoms in GS from California were much more prominent, so the effect of LO2 was more dramatic than the effect on the Israeli cvs. GD and SD, nevertheless the LO2 treatment showed the same trend in all cultivars in reducing BP. The LO2 and 1-MCP -treated fruit exhibited lower levels of ethylene, - farnesene and its oxidation product, 6-methyl-5-hepten-2-one (MHO), as determined by SPME/GC-MS analysis. In addition, LO2 pretreatment applied to California Bartlett or Israeli Spadona pears was effective in reducing superficial scald, senescent scald and internal breakdown after 4 m of cold storage at 0°C. For GS apple, low-temperature storage resulted in oxidative stress and chilling injury, caused by increased production of superoxide anions which in turn led to the generation of other dangerous reactive oxygen species (ROS). Using confocal laser-scanning microscopy and H2O2 measurements of apple peel, we observed ROS accumulation in control fruit, while negligible amounts were found in LO2 and 1-MCP treated fruit. Gene-expression levels of ROS-scavenging enzymes were induced by the various pretreatments: catalase was induced by LO2 treatment, whereas Mn superoxide dismutase was induced by 1-MCP treatment. We assume that LO2 and 1-MCP pretreated fruit remained healthier due to reduced production of ethylene and reactive oxygen substances, such as MHO, during cold storage. The LO2-treated apple exhibited greener peel and firmer fruit after 6 m of cold storage, and the fruit had high crispiness leading to high taste preference. In both pear cultivars, the LO2 treatment led to a reduction in internal breakdown and browning around the seed cavity. We tested the LO2 pre-storage treatment on a semi-commercial scale that would be applicable to a small organic grower by sealing the fruit within the plastic field bins. The treatment was most effective with a continuous flow of nitrogen through the bins; however, a single 6 hour flush of nitrogen was also fairly effective. In addition, we determined that it was very important to have the oxygen levels below 0.5% for approximately 10 days to achieve good scald control, not counting the time required to reduce the oxygen concentration. Our LO2 technology has been proven in this project to be effective in reducing several physiological disorders developed in pome fruit during cold storage. We hope that our non-chemical treatment which is friendly to the environment will be used in the near future for the organic apple and pear industry. The next step should be an analysis of the cost-benefits and commercial feasibility.
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Yahav, Shlomo, John McMurtry e Isaac Plavnik. Thermotolerance Acquisition in Broiler Chickens by Temperature Conditioning Early in Life. United States Department of Agriculture, 1998. http://dx.doi.org/10.32747/1998.7580676.bard.
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The research on thermotolerance acquisition in broiler chickens by temperature conditioning early in life was focused on the following objectives: a. To determine the optimal timing and temperature for inducing the thermotolerance, conditioning processes and to define its duration during the first week of life in the broiler chick. b. To investigate the response of skeletal muscle tissue and the gastrointestinal tract to thermal conditioning. This objective was added during the research, to understand the mechanisms related to compensatory growth. c. To evaluate the effect of early thermo conditioning on thermoregulation (heat production and heat dissipation) during 3 phases: (1) conditioning, (2) compensatory growth, (3) heat challenge. d. To investigate how induction of improved thermotolerance impacts on metabolic fuel and the hormones regulating growth and metabolism. Recent decades have seen significant development in the genetic selection of the meat-type fowl (i.e., broiler chickens); leading to rapid growth and increased feed efficiency, providing the poultry industry with heavy chickens in relatively short growth periods. Such development necessitates parallel increases in the size of visceral systems such as the cardiovascular and the respiratory ones. However, inferior development of such major systems has led to a relatively low capability to balance energy expenditure under extreme conditions. Thus, acute exposure of chickens to extreme conditions (i.e., heat spells) has resulted in major economic losses. Birds are homeotherms, and as such, they are able to maintain their body temperature within a narrow range. To sustain thermal tolerance and avoid the deleterious consequences of thermal stresses, a direct response is elicited: the rapid thermal shock response - thermal conditioning. This technique of temperature conditioning takes advantage of the immaturity of the temperature regulation mechanism in young chicks during their first week of life. Development of this mechanism involves sympathetic neural activity, integration of thermal infom1ation in the hypothalamus, and buildup of the body-to-brain temperature difference, so that the potential for thermotolerance can be incorporated into the developing thermoregulation mechanisms. Thermal conditioning is a unique management tool, which most likely involves hypothalamic them1oregulatory threshold changes that enable chickens, within certain limits, to cope with acute exposure to unexpected hot spells. Short-tem1 exposure to heat stress during the first week of life (37.5+1°C; 70-80% rh; for 24 h at 3 days of age) resulted in growth retardation followed immediately by compensatory growth" which resulted in complete compensation for the loss of weight gain, so that the conditioned chickens achieved higher body weight than that of the controls at 42 days of age. The compensatory growth was partially explained by its dramatic positive effect on the proliferation of muscle satellite cells which are necessary for further muscle hypertrophy. By its significant effect of the morphology and functioning of the gastrointestinal tract during and after using thermal conditioning. The significant effect of thermal conditioning on the chicken thermoregulation was found to be associated with a reduction in heat production and evaporative heat loss, and with an increase in sensible heat loss. It was further accompanied by changes in hormones regulating growth and metabolism These physiological responses may result from possible alterations in PO/AH gene expression patterns (14-3-3e), suggesting a more efficient mechanism to cope with heat stress. Understanding the physiological mechanisms behind thermal conditioning step us forward to elucidate the molecular mechanism behind the PO/AH response, and response of other major organs. The thermal conditioning technique is used now in many countries including Israel, South Korea, Australia, France" Ecuador, China and some places in the USA. The improvement in growth perfom1ance (50-190 g/chicken) and thermotolerance as a result of postnatal thermal conditioning, may initiate a dramatic improvement in the economy of broiler's production.
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Yahav, Shlomo, John Brake e Orna Halevy. Pre-natal Epigenetic Adaptation to Improve Thermotolerance Acquisition and Performance of Fast-growing Meat-type Chickens. United States Department of Agriculture, setembro de 2009. http://dx.doi.org/10.32747/2009.7592120.bard.
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: The necessity to improve broiler thermotolerance and performance led to the following hypothesis: (a) thethermoregulatory-response threshold for heat production can be altered by thermal manipulation (TM) during incubation so as to improve the acquisition of thermotolerance in the post-hatch broiler;and (b) TM during embryogenesis will improve myoblast proliferation during the embryonic and post-hatch periods with subsequent enhanced muscle growth and meat production. The original objectives of this study were as follow: 1. to assess the timing, temperature, duration, and turning frequency required for optimal TM during embryogenesis; 2. to evaluate the effect of TM during embryogenesis on thermoregulation (heat production and heat dissipation) during four phases: (1) embryogenesis, (2) at hatch, (3) during growth, and (4) during heat challenge near marketing age; 3. to investigate the stimulatory effect of thermotolerance on hormones that regulate thermogenesis and stress (T₄, T₃, corticosterone, glucagon); 4. to determine the effect of TM on performance (BW gain, feed intake, feed efficiency, carcass yield, breast muscle yield) of broiler chickens; and 5. to study the effect of TM during embryogenesis on skeletal muscle growth, including myoblast proliferation and fiber development, in the embryo and post-hatch chicks.This study has achieved all the original objectives. Only the plasma glucagon concentration (objective 3) was not measured as a result of technical obstacles. Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” In order to sustain or even improve broiler performance, TM during the period of embryogenesis when satellite cell population normally expand should increase absolute pectoralis muscle weight in broilers post-hatch. Major conclusions: Intermittent TM (39.5°C for 12 h/day) during embryogenesis when the thyroid and adrenal axis was developing and maturing (E7 to E16 inclusive) had a long lasting thermoregulatory effect that improved thermotolerance of broiler chickens exposed to acute thermal stress at market age by lowering their functional Tb set point, thus lowering metabolic rate at hatch, improving sensible heat loss, and significantly decreasing the level of stress. Increased machine ventilation rate was required during TM so as to supply the oxygen required for the periods of increased embryonic development. Enhancing embryonic development was found to be accomplished by a combination of pre-incubation heating of embryos for 12 h at 30°C, followed by increasing incubation temperature to 38°C during the first 3 days of incubation. It was further facilitated by increasing turning frequency of the eggs to 48 or 96 times daily. TM during critical phases of muscle development in the late-term chick embryo (E16 to E18) for 3 or 6 hours (39.5°C) had an immediate stimulatory effect on myoblast proliferation that lasted for up to two weeks post-hatch; this was followed by increased hypertrophy at later ages. The various incubation temperatures and TM durations focused on the fine-tuning of muscle development and growth processes during late-term embryogenesis as well as in post-hatch chickens.
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Brosh, Arieh, David Robertshaw, Yoav Aharoni, Zvi Holzer, Mario Gutman e Amichai Arieli. Estimation of Energy Expenditure of Free Living and Growing Domesticated Ruminants by Heart Rate Measurement. United States Department of Agriculture, abril de 2002. http://dx.doi.org/10.32747/2002.7580685.bard.
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Research objectives were: 1) To study the effect of diet energy density, level of exercise, thermal conditions and reproductive state on cardiovascular function as it relates to oxygen (O2) mobilization. 2) To validate the use of heart rate (HR) to predict energy expenditure (EE) of ruminants, by measuring and calculating the energy balance components at different productive and reproductive states. 3) To validate the use of HR to identify changes in the metabolizable energy (ME) and ME intake (MEI) of grazing ruminants. Background: The development of an effective method for the measurement of EE is essential for understanding the management of both grazing and confined feedlot animals. The use of HR as a method of estimating EE in free-ranging large ruminants has been limited by the availability of suitable field monitoring equipment and by the absence of empirical understanding of the relationship between cardiac function and metabolic rate. Recent developments in microelectronics provide a good opportunity to use small HR devices to monitor free-range animals. The estimation of O2 uptake (VO2) of animals from their HR has to be based upon a consistent relationship between HR and VO2. The question as to whether, or to what extent, feeding level, environmental conditions and reproductive state affect such a relationship is still unanswered. Studies on the basic physiology of O2 mobilization (in USA) and field and feedlot-based investigations (in Israel) covered a , variety of conditions in order to investigate the possibilities of using HR to estimate EE. In USA the physiological studies conducted using animals with implanted flow probes, show that: I) although stroke volume decreases during intense exercise, VO2 per one heart beat per kgBW0.75 (O2 Pulse, O2P) actually increases and measurement of EE by HR and constant O2P may underestimate VO2unless the slope of the regression relating to heart rate and VO2 is also determined, 2) alterations in VO2 associated with the level of feeding and the effects of feeding itself have no effect on O2P, 3) both pregnancy and lactation may increase blood volume, especially lactation; but they have no effect on O2P, 4) ambient temperature in the range of 15 to 25°C in the resting animal has no effect on O2P, and 5) severe heat stress, induced by exercise, elevates body temperature to a sufficient extent that 14% of cardiac output may be required to dissipate the heat generated by exercise rather than for O2 transport. However, this is an unusual situation and its affect on EE estimation in a freely grazing animal, especially when heart rate is monitored over several days, is minor. In Israel three experiments were carried out in the hot summer to define changes in O2P attributable to changes in the time of day or In the heat load. The animals used were lambs and young calves in the growing phase and highly yielding dairy cows. In the growing animals the time of day, or the heat load, affected HR and VO2, but had no effect on O2P. On the other hand, the O2P measured in lactating cows was affected by the heat load; this is similar to the finding in the USA study of sheep. Energy balance trials were conducted to compare MEI recovery by the retained energy (RE) and by EE as measured by HR and O2P. The trial hypothesis was that if HR reliably estimated EE, the MEI proportion to (EE+RE) would not be significantly different from 1.0. Beef cows along a year of their reproductive cycle and growing lambs were used. The MEI recoveries of both trials were not significantly different from 1.0, 1.062+0.026 and 0.957+0.024 respectively. The cows' reproductive state did not affect the O2P, which is similar to the finding in the USA study. Pasture ME content and animal variables such as HR, VO2, O2P and EE of cows on grazing and in confinement were measured throughout three years under twenty-nine combinations of herbage quality and cows' reproductive state. In twelve grazing states, individual faecal output (FO) was measured and MEI was calculated. Regression analyses of the EE and RE dependent on MEI were highly significant (P<0.001). The predicted values of EE at zero intake (78 kcal/kgBW0.75), were similar to those estimated by NRC (1984). The EE at maintenance condition of the grazing cows (EE=MEI, 125 kcal/kgBW0.75) which are in the range of 96.1 to 125.5 as presented by NRC (1996 pp 6-7) for beef cows. Average daily HR and EE were significantly increased by lactation, P<0.001 and P<0.02 respectively. Grazing ME significantly increased HR and EE, P<0.001 and P<0.00l respectively. In contradiction to the finding in confined ewes and cows, the O2P of the grazing cows was significantly affected by the combined treatments (P<0.00l ); this effect was significantly related to the diet ME (P<0.00l ) and consequently to the MEI (P<0.03). Grazing significantly increased O2P compared to confinement. So, when EE of grazing animals during a certain season of the year is estimated using the HR method, the O2P must be re measured whenever grazing ME changes. A high correlation (R2>0.96) of group average EE and of HR dependency on MEI was also found in confined cows, which were fed six different diets and in growing lambs on three diets. In conclusion, the studies conducted in USA and in Israel investigated in depth the physiological mechanisms of cardiovascular and O2 mobilization, and went on to investigate a wide variety of ruminant species, ages, reproductive states, diets ME, time of intake and time of day, and compared these variables under grazing and confinement conditions. From these combined studies we can conclude that EE can be determined from HR measurements during several days, multiplied by O2P measured over a short period of time (10-15 min). The study showed that RE could be determined during the growing phase without slaughtering. In the near future the development microelectronic devices will enable wide use of the HR method to determine EE and energy balance. It will open new scopes of physiological and agricultural research with minimizes strain on animals. The method also has a high potential as a tool for herd management.
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Fait, Aaron, Grant Cramer e Avichai Perl. Towards improved grape nutrition and defense: The regulation of stilbene metabolism under drought. United States Department of Agriculture, maio de 2014. http://dx.doi.org/10.32747/2014.7594398.bard.
Texto completo da fonteResumo:
The goals of the present research proposal were to elucidate the physiological and molecular basis of the regulation of stilbene metabolism in grape, against the background of (i) grape metabolic network behavior in response to drought and of (ii) varietal diversity. The specific objectives included the study of the physiology of the response of different grape cultivars to continuous WD; the characterization of the differences and commonalities of gene network topology associated with WD in berry skin across varieties; the study of the metabolic response of developing berries to continuous WD with specific attention to the stilbene compounds; the integration analysis of the omics data generated; the study of isolated drought-associated stress factors on the regulation of stilbene biosynthesis in plantaand in vitro. Background to the topic Grape quality has a complex relationship with water input. Regulated water deficit (WD) is known to improve wine grapes by reducing the vine growth (without affecting fruit yield) and boosting sugar content (Keller et al. 2008). On the other hand, irregular rainfall during the summer can lead to drought-associated damage of fruit developmental process and alter fruit metabolism (Downey et al., 2006; Tarara et al., 2008; Chalmers et al., 792). In areas undergoing desertification, WD is associated with high temperatures. This WD/high temperature synergism can limit the areas of grape cultivation and can damage yields and fruit quality. Grapes and wine are the major source of stilbenes in human nutrition, and multiple stilbene-derived compounds, including isomers, polymers and glycosylated forms, have also been characterized in grapes (Jeandet et al., 2002; Halls and Yu, 2008). Heterologous expression of stilbenesynthase (STS) in a variety of plants has led to an enhanced resistance to pathogens, but in others the association has not been proven (Kobayashi et al., 2000; Soleas et al., 1995). Tomato transgenic plants harboring a grape STS had increased levels of resveratrol, ascorbate, and glutathione at the expense of the anthocyanin pathways (Giovinazzo et al. 2005), further emphasizing the intermingled relation among secondary metabolic pathways. Stilbenes are are induced in green and fleshy parts of the berries by biotic and abiotic elicitors (Chong et al., 2009). As is the case for other classes of secondary metabolites, the biosynthesis of stilbenes is not very well understood, but it is known to be under tight spatial and temporal control, which limits the availability of these compounds from plant sources. Only very few studies have attempted to analyze the effects of different environmental components on stilbene accumulation (Jeandet et al., 1995; Martinez-Ortega et al., 2000). Targeted analyses have generally shown higher levels of resveratrol in the grape skin (induced), in seeded varieties, in varieties of wine grapes, and in dark-skinned varieties (Gatto et al., 2008; summarized by Bavaresco et al., 2009). Yet, the effect of the grape variety and the rootstock on stilbene metabolism has not yet been thoroughly investigated (Bavaresco et al., 2009). The study identified a link between vine hydraulic behavior and physiology of stress with the leaf metabolism, which the PIs believe can eventually lead to the modifications identified in the developing berries that interested the polyphenol metabolism and its regulation during development and under stress. Implications are discussed below.