Interactive Effects Of Stress Research Articles

بررسی تأثیر دو گونه قارچ میکوریزا-آربوسکولار در سطوح مختلف تنش رطوبتی بر برخی ویژگیهای رشدی ذرت

در شرایط تنش ، همزیستی گونه‌های قارچ میکوریزا-آربوسکولار با ریشه گیاه میزبان، تأثیر مستقیمی بر تحمل خشکی در گیاهان دارد. به‌منظور بررسی تأثیر دو گونه قارچ میکوریزا-آربوسکولار در سطوح مختلف تنش رطوبتی بر برخی ویژگی‌های رشدی ذرت، این آزمایش به‌صورت فاکتوریل با دو عامل در قالب طرح پایه کاملا تصادفی با پنج تکرار در شرایط گلخانه اجرا گردید. عامل اول مربوط به سطوح تنش رطوبتی شامل 60، 80 و 100% ظرفیت زراعی و عامل دوم مربوط به دو گونه قارچ میکوریزا شامل Glomus intraradices و Glomus mosseae و شاهد (عدم تلقیح) بودند. نتایج نشان داد که تنش رطوبتی موجب کاهش ارتفاع بوته و وزن خشک اندام هوایی به ترتیب به میزان13% و17% شد. تنش رطوبتی بر وزن خشک ریشه بی تاثیر بود ولی، قارچ‌های مایکوریزا وزن خشک ریشه را افزایش داده و تاثیر G. mosseae نسبت به گونه G. intraradices بیشتر بود. علیرغم افزایش شدت تنش رطوبتی، قارچ­های مایکوریزا شاخص کلروفیل SPAD را افزایش داد. بیشترین شاخص کلروفیل مربوط به تیمار تلقیح با قارچ G. mosseae در 0.6 ظرفیت زراعی معادل 37.02 بود. گیاه تلقیح شده با قارچ G. mosseae نسبت به G. intraradices کارایی بیشتری در حفظ رطوبت نسبی آب برگ در شرایط تنش رطوبتی داشت. بیشترین درصد کلونیزاسیون ریشه معادل 39.04 در تیمار تلقیح با قارچ mosseae G. در 60% رطوبت زراعی به دست آمد. به‌طورکلی، نتایج پیشنهاد می­کنند که در شرایط تنش رطوبتی، گونه G. mosseae قادر به برقراری ارتباط همزیستی مؤثرتری با ریشه گیاه ذرت تحت شرایط انجام این آزمایش بود.

Environmental tobacco smoke (ETS) and hyperlipidemia modified by perceived work stress.

BackgroundAccumulating evidence has shown that exposure to environmental tobacco smoke (ETS) is associated with cardiovascular diseases (CVDs) However, few studies have assessed both exposure to ETS and high-perceived work stress on hyperlipidemia. The aim of the present study is to assess the interaction effect of ETS exposure and high-perceived work stress on the risk of hyperlipidemia.MethodsA total of 11,875 middle-aged civil servants from 647 registered institutions employed by the Taiwan government were randomly selected using multistage stratified cluster sampling based on proportional probabilistic sampling. Each participant anonymously and independently filled out a web-based questionnaire and informed consent.ResultsThe prevalence of hyperlipidemia in middle-aged civil servants diagnosed by physicians was 11.5% for men and 6.1% for women. Hyperlipidemia was significantly associated with smoking, alcohol consumption, betel nut chewing, weight gain and perceived work stress. In both the obesity and smoking groups, there were consistent interaction effects of ETS exposure and perceived work stress on hyperlipidemia for middle-aged civil servants. Non-obese and non-smoking groups were more at risk for hyperlipidemia from exposure to both ETS and high-perceived work stress.ConclusionThere is an interaction effect of ETS exposure and high-perceived work stress on hyperlipidemia, regardless of obesity and smoking. It is crucial to immediately reduce ETS exposure and stressful work by enforcing smoke-free policies and reducing pressure for civil servants.

Effect of Drought Stress on Certain Morphological and Physiological Characteristics of a Resistant and a Sensitive Canola Cultivar.

Water stress is one of the main abiotic factors that reduces plant growth, mainly due to high evaporative demand and low water availability. In order to evaluate the effects of drought stress on certain morphological and physiological characteristics of two canola cultivars, we conducted a factorial experiment based on a completely randomized design. The findings show that drought stress exacerbations result in the plant's response to stress due to increased canola resistance caused by changes in plant pigments, proline, catalase, ascorbate peroxidase, peroxidase, superoxide dismutase and malondialdehyde, glucose, galactose, rhamnose and xylose. These in turn ultimately influence the morphological characteristics of canola. Drought stress reduces the concentration of carotenoids, chlorophyll a, chlorophyll b, total chlorophylls; however, glucose, galactose, rhamnose, xylose, proline, catalase, ascorbate peroxidase, peroxidase, superoxide dismutase, malondialdehyde (in leaves and roots) and the chlorophyll a and b ratios were increased. Reduction of plant height, stem height, root length, fresh and dry weight of canola treated with 300 g/l PEG compared to non-treatment were 0.264, 0.236, 0.394, 0.183 and 0.395, respectively. From the two canola cultivars, the morphological characteristics of the NIMA increased compared to the Ks7 cultivar. Interaction effects of cultivar and drought stress showed that NIMA cultivar without treatment had the highest number of morphological characteristics such as carotenoid concentration, chlorophyll a, chlorophyll b, total chlorophylls a and b, whereas the cultivar with 300 g/l PEG (drought stress) had the highest amount of proline, malondialdehyde, soluble sugars and enzymes in leaves and roots. Increasing activity of oxidative enzymes and soluble sugars in canola under drought stress could be a sign of their relative tolerance to drought stress.

Can Smart City Development Promote Residents’ Emotional Well-Being? Evidence From China

The rapid development of smart cities has raised concerns about residents' emotional well-being (EWB). To enhance EWB when developing smart cities, policy-makers should take residents' perceptions and attitudes into account. How can residents' perceptions about smart city development help promote their EWB? In this paper, we constructed a comprehensive model to explore the effect mechanism of perceived smart city developments on residents' EWB by considering the factors of stress, convenience, and life satisfaction (LS). Using a sample of 428 urban residents in a Chinese smart city, the paper verified the conceptual model by using a structural equation model (SEM) analysis. The results showed that: (1) perceived smart public service (PSPS) can increase EWB by reducing stress; it can also increase EWB by the mechanism of improved LS, brought about by this reduced stress. Perceived smart infrastructure (PSI) will reduce EWB by increasing stress; it can also decrease EWB by the mechanism of reduced LS, brought about by increased stress. (2) Perceived smart public administration (PSPA), PSPS, PSI, and perceived smart environmental protection (PSEP) can enhance EWB via the mechanism of increasing convenience and thereby improving LS. (3) Finally, the statistically insignificant relationship between convenience and LS may be due to the interaction effect of stress and convenience, because the interaction term between convenience and stress has a significant effect on LS, resulting in four insignificant indirect effects involving PSPA, PSPS, PSI, PSEP and EWB vis-a-vis convenience. Overall, this paper contributes to cross-disciplinary research on residents' perceptions with respect to smart city development, and provides guidelines for governmental policy-making in the planning of smart cities.

Deconvolution of Stress Interaction Effects from Atomic Force Spectroscopy Data across Polymer−Particle Interfaces

Atomic force microscopy (AFM) is a powerful technique for imaging polymer nanocomposites as well as other systems with heterogeneous material properties on the nanoscale. However, the quantitative ...

Frequency- and incident-angle-dependent P-wave properties influenced by dynamic stress interactions in fractured porous media

The effect of stress interactions on the effective poroelastic properties in saturated porous media has not been well-understood, especially for rocks with a fracture density larger than the dilute limit assumption. Frequency- and angle-dependent characteristics of stress interactions are analyzed by finite-element numerical tests with a least-squares procedure. We have investigated two types of fractured media: a stacked fractured model with stress shielding and a coplanar fractured model with stress amplification. We evaluate the effect of stress interactions from different spatial distributions of fractures on seismic attenuation and dispersion, with a specific focus on their frequency- and angle-dependent characteristics. We determine with numerical examples that a greater shielding effect corresponds to a larger frequency corresponding to maximum attenuation but a smaller peak attenuation. In contrast, a larger amplification effect leads to a higher attenuation. Due to the excluded diffusion energy outside the representative volume element, increasing the incidence angle ([Formula: see text]) leads to decreasing attenuation, whereas stress amplification is enhanced as the incidence angle increases continuously ([Formula: see text]), corresponding to increasing attenuation. This suggests that different incidence angles reshape the spatial distribution of stress interactions, in turn contributing to different frequency-dependent behaviors.

Mindful Nonreactivity Moderates the Relationship between Chronic Stress and Pain Interference in Law Enforcement Officers.

With high levels of both chronic stress and chronic pain, law enforcement provides a unique population in which to study the potential mitigating impact of cognitive and affective reactivity on the stress-pain link. The primary aim of the present study was to examine the moderating role of mindful nonreactivity in the relationship between chronic stress and pain interference in law enforcement officers (n = 60). A regression analysis was conducted to determine if chronic stress predicted pain interference, and subsequently, to compute an estimate of the interaction effect of the chronic stress and mindful nonreactivity on pain interference. Results demonstrated the overall model was significant, F (3,55) = 5.29, p =.003, R2 = .47. When controlling for mindful nonreactivity, chronic stress significantly predicted pain interference, b = .76, t (55) = 3.40, p = .001, such that every one unit increase in chronic stress was associated with a .76 unit increase in pain interference. Results also demonstrated a significant interaction effect of mindful nonreactivity and chronic stress on pain interference, b = -.04, t (55) = -2.86, p = .006. The Johnson-Neyman technique was conducted and revealed among individuals with low levels of mindful nonreactivity, chronic stress significantly predicted pain interference. However, for individuals with greater levels of mindful nonreactivity, chronic stress no longer predicted pain interference. Findings contribute to a growing understanding of how mindfulness can mitigate harmful effects of stress.

Effects of spermidine and salinity stress on growth and biochemical response of paraquat‐susceptibe and ‐resistant goosegrass (Eleusine indica L.)

This study aimed to investigate the interaction effect of spermidine (Spd) and salinity stress on growth, photosynthetic rate, antioxidant system and free polyamines (PAs) contents of goosegrass (Eleusine indica L.) seedlings. E. indica was raised in a growth chamber under normal and toxic salt stress (100 mM of NaCl) and sprayed with 0 and 1.00 mM of Spd. The degree of growth inhibition caused by salt stress was lower in a paraquat‐resistant (R) biotype compared to a paraquat‐susceptible (S) biotype. Salt stress significantly elevated the accumulation of malondialdehyde, electrolyte leakage and proline and resulted in the degradation of chlorophyll; reduction in chlorophyll fluorescence; and a decrease in photosynthetic rate, relative water content and biomass. Spd‐treated plants maintained higher activities of antioxidant enzymes (catalase, superoxide dismutase and peroxidase), a greater rate of photosynthesis and lower osmotic pressure than untreated plants in the S biotype. Endogenous Spd content was reduced significantly in response to salt stress in both biotypes, but free PAs content in the S biotype was remarkably enhanced with exogenous Spd application under normal or salinity stress conditions. The result indicated that the S biotype was more sensitive to salinity than the R biotype; meanwhile, exogenous Spd maybe play an important role in protecting S biotype plants from salt stress.

A simulation study comparing the Texas two-step and the multistage consecutive fracturing method

Multistage hydraulic fracturing in horizontal wells is a critical technique for developing unconventional oil and gas resources. Stress interactions among neighboring fractures cause immature fracture development. The Texas two-step fracturing (TTSF) method is a new technique that aims to enhance fracture complexity and conductivity. This paper compares the fracture development of consecutive fracturing and the TTSF. The fracturing sequence in the multistage fracturing method has a significant effect on the fracture length, fracture width and injection pressure. The consecutive fracturing results in relatively uneven fracture length and width. Certain fractures in consecutive fracturing are restrained to be closed due to the strong stress shadowing effect. In contrast, TTSF has considerable potential for alleviating the negative effects of stress interactions and producing a larger stimulated reservoir volume.

The psychological impact of social problem solving under stress in adults: Debased life satisfaction, heightened depressed mood, or both?

The present study sought to examine how social problem solving and stress are involved in psychological adjustment in an adult sample of 336 (262 females & 74 males) college students. We were interested in examining whether stress might play an additive, as well as interactive, role in the prediction of psychological adjustment (viz., life satisfaction & depressive symptoms) above and beyond social problem solving. Results from regression analyses indicated that strengths in social problem solving, especially high positive problem orientation and low negative problem orientation, and lack of stress were important and unique predictors of life satisfaction. Specifically, deficits in social problem solving, especially low positive problem orientation and high negative problem orientation, and presence of stress were important and unique predictors of depressive symptoms. Moreover, we found support for a specific Negative Problem Orientation × Stress interaction effect in predicting depressive symptoms, but not life satisfaction. A plot of the interaction showed that among those holding a negative problem orientation and experiencing stress, they reported “borderline clinical depression” levels of symptoms. Some implications of the present findings are discussed.

Moderator Effects of Life Stress on the Association between MAOA-uVNTR, Depression, and Burnout

Background: The serotonergic and noradrenergic systems have a strong impact on several affective disorders and are key targets for psychopharmacological therapy. With respect to pathogenesis, there is a growing body of evidence showing an influence of a promoter repeat polymorphism (MAOA-uVNTR) altering the expression rate of monoamine oxidase A. However, only a few studies investigate its influence on depression with only 2 of them considering the moderating effects of life stress. For burnout, there are no studies so far investigating the genetic basis. Objectives: The aim of the present study was to replicate an interaction effect of MAOA-uVNTR and life stress on depression, and extend these possible findings to the burnout syndrome. Especially, the latter one might help in understanding the underlying mechanisms of burnout and its association to depression. Method: A total of n = 1,541 participants (n = 1,099 healthy controls, n = 442 inpatients with affective disorders) provided genetic samples and filled in self-report questionnaires measuring depression, burnout, and the extent of experienced stressful life events (SLEs). Results: A life stress x MAOA-uVNTR interaction on depression and burnout was observed in women suggesting that carriers of the high expressing allele (MAO-H) with many SLEs had the highest scores in both burnout and depression. In men, there was only a weak effect of MAOA-uVNTR on depression. Conclusions: The results suggest a more pronounced reactivity to adverse environmental factors in carriers of the MAO-H allele. Especially the effect of life stress and MAOA-uVNTR on burnout should be independently replicated in the future as this is the first study showing this association.

Effect of Drought Stress and Bio-fertilizer on Yield and Yield Components of Guar Cyamopsis tetragonoloba (L.) Taub.

The effect of four different levels of irrigation periods, including normal irrigation, irrigation after 100, 150, and 200mm evaporation, with three different bio-fertilizer including control, Mycorrhiza, and Rhizobium were investigated on morphological and yield traits of guar. The experiment was conduct in form of split-plot design with irrigation periods as main plots and bio-fertilizers as sub-plots with three replications in research farm of Sarayan agricultural college-University of Birjand in2016.The results of analysis of variance showed significant effect of investigated irrigation periods on plant height, wilting, root length, pod length, number of pods per plant, grain yield, and biological yield at 1% probability level, and on chlorophyll content, height of the first branch, stem diameter, number of secondary branch, number of seeds per pod, and harvest index at 5% probability level. The interaction effect of drought stress×bio-fertilizers of bio-fertilizers was significant on wilting at 1% probability level and on chlorophyll and pod length at 5% probability level. The results of means comparison analysis revealed that the highest mean of wilting was achieved in severe drought stress induction in control, and application of both Mycorrhiza, and Rhizobium bio-fertilizers. Increasing levels of drought stress led to significant reduction in grain yield and harvest index of guar. Application of Mycorrhiza, and Rhizobium bio-fertilizers did not show significant effect on yield traits of guar under drought stress condition; however the protein percentage of guar’s seeds was increased in moderate drought stress and inoculation with Rhizobium. Based on the results of simple correlation analysis biological yield and harvest index had the highest positive and significant correlation with grain yield of guar and can used as selection criteria under drought stress condition.

Evaluating the effect of sowing date and drought stress on morphological and functional characteristics of three genotypes of winter oilseed rape (Brassica napus L.)

To assess the effects of drought stress and sowing date on phenological, morphological, and yield traits of three different cultivars of winter oilseed rape (Brassica napus L.), this study was conducted in research farm of Sarayan agricultural college- University of Birjand in 2016-2017 growing season. Experiment was conducted in a split-factorial based on the randomized complete block design with drought stress in the main plots and three sowing date (September 22, October 6, and October 22) along with three cultivars of canola (‘Homolious’, ‘Hayola50’, and ‘DK7070CL’) in the subplots in three replications. The results of analysis of variance and means comparison analysis showed significant and negative effect of drought stress on seed yield and biological yield traits of investigated cultivars of canola. The interaction effect of drought stress × sowing date × cultivar was only significant on leaf twisting trait at 1 % probability level. ‘Homolious’ was assigned as the most drought tolerance cultivar, based on SI, SSI, RDI, TOL, MP, STI, GMP, YI, YSI, and HARM drought tolerance indexes, whereas ‘Hayola50’ was assigned as most drought sensitive cultivar of oilseed rape.

The interactive effects of stress and coping style on cognitive function in patients with schizophrenia.

PurposePrevious studies have not determined the interactive effects of stress and coping style on cognitive function in patients with schizophrenia, and the current studies have been restricted to the relationship between stress and stress response, which may be associated with cognitive impairment in individuals with schizophrenia. The present research was aimed to determine whether stress is related to cognitive function in patients with schizophrenia. In addition, this research further investigates the moderating effects of coping style on the relationship between stress and cognitive function in patients with schizophrenia on the basis of stress and coping theory.Patients and methodsOur sample consisted of 274 patients with a confirmed diagnosis of schizophrenia, and all of them completed the Simple Cope Style Questionnaire, Social Readjustment Rating Scale, and cognitive function assessment. A multivariate regression analysis was performed to investigate the possible correlations between cognitive function and stress, and the moderating effects of coping style on the relationship between stress and cognitive function were tested using the PROCESS macro for SPSS.ResultsStress was negatively correlated with working memory. Negative coping but not positive coping moderated the relationship between stress and working memory in patients with schizophrenia, and the Johnson–Neyman technique showed that the moderating effect was significant only above this cutoff (38.32% of all negative coping scores). This means that when exposed to similar stress, patients adopting high negative coping had worse working memory than those who did not.ConclusionThese findings suggested that the assessment of stress and coping style may help estimate working memory impairment risk in patients with schizophrenia, and reducing negative coping may be a crucial intervention target to prevent further impairment of working memory in patients with schizophrenia suffering from great stress.

Response of tomato plants to interaction effects of magnetic (Fe3O4) nanoparticles and cadmium stress

ABSTRACT Research on nanotechnology as an emerging discipline has advanced several branches of technology. Although iron is considered as an essential element for plant growth, its role in mitigating abiotic stresses has not been studied widely. Therefore, in this research, it has been attempted to investigate the effect of magnetic Fe3o4 nanoparticles on tomato plants under cadmium stress using 5 levels of magnetic (Fe3O4) nanoparticles (nano-Fe3O4) (0, 10, 20, 50, 100 mg/L) and 3 levels of CdCl2 (0, 100, 200 μM). Cadmium reduced growth and photosynthesis parameters as well as nutritional elements and increased the content of MDA, H2O2, and proline in tomato plants. Meanwhile 20 mg/L nano-Fe3o4 was able to improve cadmium toxicity by reduction in cadmium accumulation and increase in nutrient intake. However, 20 mg/L nano-Fe3o4 is potentially useful for plant growth and may motivate the variations of plants defense mechanisms in response to cadmium toxicity.

Investigating the effect of water stress on yield, essential oil content and physiological characteristics of Thymbra spicata L.

هدف انجام این آزمایش بررسی تغییرات عملکرد بوته، اسانس و برخی ویژگی­های فیزیولوژیک برگ دو اکوتیپ گیاه داروئی زوفایی به اعمال تنش رطوبتی بود. آزمایش در قالب طرح کرت­های خرد­شده بر پایه بلوک­های کامل تصادفی در سه تکرار و در دو سال (1395 و 1396) در مزرعه تحقیقاتی دانشگاه ایلام انجام گرفت. کرت­های اصلی شامل سه سطح تنش رطوبتی (آبیاری نرمال، تنش ملایم و تنش شدید) و کرت­های فرعی دربرگیرنده فاکتور فرعی شامل دو اکوتیپ گیاه زوفایی بود. نتایج آزمایش نشان داد که سطوح مختلف تیمارهای تنش رطوبتی بر صفات موردبررسی ازجمله عملکرد خشک برگ و بوته، درصد و عملکرد اسانس، شاخص سطح برگ، ارتفاع بوته و رنگیزه­ های فتوسنتزی تأثیر معنی­داری داشت. به‌طوری‌که افزایش فاصله آبیاری از آبیاری نرمال تا تنش شدید سبب کاهش معنی­دار تمامی صفات مذکور شد. بیشترین عملکرد خشک برگ، بوته، شاخص سطح برگ و کلروفیل a در تیمار آبیاری نرمال و بیشترین میزان درصد و عملکرد اسانس، کلروفیل b، کلروفیل کل و کاروتنوئید در تیمار تنش ملایم حاصل گردید. با توجه به یافته­های آزمایش اکوتیپ ملکشاهی ازنظر عملکرد خشک برگ و بوته، درصد و عملکرد اسانس نسبت به اکوتیپ سومار برتری داشت. نتیجه بررسی دوساله آزمایش نشان داد که طی سال دوم به دلیل افزایش ارتفاع و شاخص سطح برگ بوته­ ها، میانگین صفاتی از قبیل عملکرد خشک برگ و بوته و عملکرد اسانس 1.7 درصد نسبت به سال اول آزمایش افزایش نشان داد. ازآنجاکه دو اکوتیپ مورد آزمایش در طبیعت به‌صورت خودرو بوده و با شرایط اقلیمی ناپایدار و نامنظم بارشی سازگاری یافته­اند، بنابراین اعمال آبیاری منظم در کشت آن‌ها به‌صورت زراعی در مقایسه با ایجاد محدودیت آبی ملایم موجب پاسخ منفی این گیاه ازنظر درصد و عملکرد اسانس و سایر خصوصیات رشدی می­گردد که در مدیریت زراعی آن باید در نظر گرفته شود.

Reduced competition enhances community temporal stability under conditions of increasing environmental stress.

The stress-gradient hypothesis predicts a switch from competition to facilitation, under increasing environmental stress. However, it is unclear how important is the change in competition-facilitation balance (i.e., the netoutcome of plant-plant interactions) along the stress gradient in the regulation of community temporal stability (i.e., the inverse of temporal variability in total biomass). Increasing environmental stress may enhance community temporal stability by reduced competition or eventually by leading to facilitative interactions between the dominant and subordinate species. Here, we present the results of a 5-yr mesocosm experiment that demonstrates the effects of interspecific interactions on the temporal stability of a riparian community across different drought-stress scenarios. We constructed artificial communities of dominant species (Carex elata) and three subordinate species to simulate the independent effects of environmental stress and interspecific interactions. Using removal of the dominant species, we evaluated the interplay of various mechanisms regulating the temporal stability of the subordinate species (competition-facilitation balance, species asynchrony, and dominant species stability). By simultaneous testing of these stabilizing mechanisms, we show their importance differs depending on environmental variability and harshness. The predominant role is taken by species asynchrony in a seasonally dry environment, whereas in a permanently dry environment, the importance of reduced competition increases. Reduced competition was stabilizing, in particular through increased total community biomass, whereas species asynchrony increased total community biomass and decreased biomass variation. These results suggest experiments and simulations that exclude interspecific interactions may not offer realistic predictions of the effects of changing hydrological regimes on ecosystem functioning.

Micromechanical evaluation of rock and fluid interactions

The deformation of the solid system in the process of fluid flow in deformable porous media, such as underground fluid flow, carbon-dioxide (CO2) sequestration, is the result of external stress, particle-particle, and fluid-particle interactions. Such behavior is very crucial in CO2 sequestration as it causes a significant instability and onset of displacements. The small-scale deformations of pore-pressure may trigger waking up of the pre-existing and unrevealed fractures and faults, which in turn cause seismicity. Thus, studying the effect of fluid flow on rock deformation is very important. In this paper, the effect of external stress and fluid-particle interactions on the deformation of porous media is elucidated through evaluating of micromechanical behaviors of rock and fluid under an external stress. To this end, packing of multi-size spherical particles in dry and wet conditions are used to represent the medium. Then, the deformation under different external stress is quantified using various morphological and flow properties, such as strain, pore-size distribution, porosity, and velocity field. The results indicate that as the external stress increases, the deformation of both dry and wet states increase. By increasing the external stress, the discrepancy between the deformation of the dry and wet cases declines, whereas the deformation of the dry cases is always bigger than that of the wet samples as the fluid-particle drag force inhibits the solid deformation.

Independent and relative effects of stress, depressive symptoms, and affect on college students' daily health behaviors.

Stress and depressive symptoms are associated with maladaptive health behavior practices such as unhealthy eating, sedentary behavior, insufficient sleep, and substance use. The relative and interactive effects of stress and depressive symptoms on health behavior practices are less well understood. The present study examined these processes in a daily diary study of 127 college students. Results from hierarchical generalized linear models indicated that depressive symptoms, and chronic and daily stress, but not acute stressful life events, were significantly associated with a composite score of daily maladaptive health behavior engagement (depressive symptomsb=.01, SE= .00, p < .01; chronic stress, b = .03, SE= .01, p < .01; daily stress, b = .01, SE= .01, p = .02); unexpectedly, the effect of stress on health behaviors was not moderated by depressive symptoms. Additionally, results demonstrated that the effect of depressive symptoms on health behaviors was mediated by fluctuations in daily negative affect. These results bear implications for intervention during a crucial period in the development of mental and physical health.

Influence of Serotonin Transporter SLC6A4 Genotype on the Effect of Psychosocial Stress on Cognitive Performance: An Exploratory Pilot Study.

Previous research has shown an effect of various psychosocial stressors on unconstrained cognitive flexibility, such as searching through a large set of potential solutions in the lexical-semantic network during verbal problem-solving. Functional magnetic resonance imaging has shown that the presence of the short (S) allele (lacking a 43-base pair repeat) of the promoter region of the gene (SLC6A4) encoding the serotonin transporter (5-HTT) protein is associated with a greater amygdalar response to emotional stimuli and a greater response to stressors. Therefore, we hypothesized that the presence of the S-allele is associated with greater stress-associated impairment in performance on an unconstrained cognitive flexibility task, anagrams. In this exploratory pilot study, 28 healthy young adults were genotyped for long (L)-allele versus S-allele promoter region polymorphism of the 5-HTT gene, SLC6A4. Participants solved anagrams during the Trier Social Stress Test, which included public speaking and mental arithmetic stressors. We compared the participants' cognitive response to stress across genotypes. A Gene×Stress interaction effect was observed in this small sample. Comparisons revealed that participants with at least one S-allele performed worse during the Stress condition. Genetic susceptibility to stress conferred by SLC6A4 appeared to modulate unconstrained cognitive flexibility during psychosocial stress in this exploratory sample. If confirmed, this finding may have implications for conditions associated with increased stress response, including performance anxiety and cocaine withdrawal. Future work is needed both to confirm our findings with a larger sample and to explore the mechanisms of this proposed effect.