Competitive Stress Research Articles

Adverse role of colonial morphology and favorable function of microcystins for Microcystis to compete with Scenedesmus

In eutrophic freshwaters, Microcystis usually becomes dominant in phytoplankton communities due to the synergistic effects of its special eco-physiological traits and environmental factors. Colonial morphology can protect Microcystis from zooplankton grazing, which indirectly favors Microcystis to outcompete other phytoplankton, although the colonial form is not conducive to the absorption of nutrients. Moreover, unicellular Microcystis usually has competitive advantages over other phytoplankton due to its efficient absorption capacity for nutrients and releasing microcystins. However, the consequence of direct competition between toxic colonial Microcystis and green algae without external grazing pressure still remained unknown. In this study, the competition between toxic colonial Microcystis aeruginosa and a common green alga Scenedesmus obliquus was explored. Results showed that: (1) colonial M. aeruginosa had a higher requirement for key macro-nutrient phosphorus than S. obliquus, and thus its population declined and was replaced by S. obliquus eventually; (2) microcystins released by colonial M. aeruginosa inhibited the photosynthetic activity and growth of S. obliquus at early stage of the competition; (3) the photosynthetic potential of colonial M. aeruginosa was stimulated in response to the competitive stress from S. obliquus, although the population of colonial M. aeruginosa declined eventually; (4) microcystin production of colonial M. aeruginosa was enhanced by phosphorus limitation due to S. obliquus competition and was positively related to photosynthetic potential of colonial M. aeruginosa. These results indicated that, in the absence of complex natural environment, colonial Microcystis cannot outcompete Scenedesmus in a pure competition, although microcystins can play a favorable role in the competition, which clarified the opposite role of colonies and microcystins in the competition of colonial Microcystis against other phytoplankton.

Neighborhood dissimilarity consistently attenuates competition stress on tree growth under altered water availability in a natural boreal forest

Tree growth regulates forest productivity and carbon sequestration. Although there has been evidence showing positive effects of neighborhood diversity on tree growth, few have experimentally demonstrated how tree growth may respond to neighborhood diversity in natural forests under altered water availability, which is anticipated to occur more frequently with ongoing global climate change. We examined three-year individual tree basal area growth under the water alteration treatments of reduced (-25% throughfall during the growing season), ambient and added (+25% throughfall during the growing season) rainfall in the broadleaf stands, conifer stands and their mixtures of a young natural boreal forest. We quantified neighborhood drought tolerance dissimilarity, phylogeny dissimilarity and neighborhood crowding based on individual tree sizes and the distance between them. We found that the tree growth on average did not change significantly with water alteration but decreased with neighborhood crowding, with the negative crowding effect being more pronounced in water reduction treatment than in ambient and water addition treatments. Higher neighborhood dissimilarity of drought tolerance and phylogeny promoted tree growth consistently across all water conditions. Moreover, the positive effects of neighborhood dissimilarity of drought tolerance and phylogeny became more pronounced with increasing neighborhood crowding. Our results suggest that promoting species mixtures in boreal forests may sustain higher boreal forest productivity under changing water availability.

The role of plant-soil feedback in long-term species coexistence cannot be predicted from its effects on plant performance.

Despite many studies on the importance of competition and plants' associations with mutualists and pathogens on plant performance and community organization, the joint effects of these two factors remain largely unexplored. Even less is known about how these joint effects vary through a plant's life in different environmental conditions and how they contribute to the long-term coexistence of species. We investigated the role of plant-soil feedback (PSF) in intra- and interspecific competition, using two co-occurring dry grassland species as models. A two-phase PSF experiment was used. In the first phase, soil was conditioned by the two plant species. In the second, we assessed the effect of soil conditioning, competition and drought stress on seedling establishment, plant growth in the first and second vegetation season, and fruit production. We also estimated effects of different treatments on overall population growth rates and predicted the species' potential coexistence. Soil conditioning played a more important role in the early stages of the plants' life (seedling establishment and early growth) than competition. Specifically, we found strong negative intraspecific PSF for biomass production in the first year in both species. Although the effects of soil conditioning persisted in later stages of plant's life, competition and drought stress became more important. Surprisingly, models predicting species coexistence contrasted with the effects on individual life stages, showing that our model species benefit from their self-conditioned soil in the long run. We provide evidence that the effects of PSF vary through plants' life stages. Our study suggests that we cannot easily predict the effects of soil conditioning on long-term coexistence of species using data only on performance at a single time as commonly done in PSF studies. We also show the importance of using as realistic environmental conditions as possible (such as drought stress experienced in dry grasslands) to draw reasonable conclusions on species coexistence.

Competitive Relationship Between Cleistocalyx operculatus and Syzygium jambos Under Well-Watered Conditions Transforms Into a Mutualistic Relationship Under Waterlogging Stress.

Competition and abiotic stress such as waterlogging (WL) represent main factors limiting plant growth and determining plant resistance and distribution patterns in wetland ecosystems. One of the basic steps for wetland restoration is to plant trees to ensure a quicker recovery and prevent erosion. Plant survival and adaptation are considered criteria of principal priority for the screening of plant species for wetland ecosystem restoration. WL influences plant species in wetlands via the deterioration of the plant root environment which leads to oxygen deficiency that affects plant growth, photosynthesis, respiration, and other metabolic processes. A suitable plant species was determined according to tolerance to WL during wetland vegetation recovery activities. Thus, two tree species (Cleistocalyx operculatus and Syzygium jambos) that showed a certain waterlogging tolerance were chosen to study their behaviors in different planting model and environmental conditions. Given that interspecific relationship should be considered during plant community construction, the eco-physiological adaptable mechanisms between these woody plants under well-watered condition and waterlogging stress were explored. Results showed that both species were waterlogging-tolerant species due to their ability to adapt to submergence conditions for 120 days. Moreover, C. operculatus possessed stronger tolerance to waterlogging stress because of a significant adventitious roots biomass accumulation. A competitive relationship was found between C. operculatus and S. jambos under well-watered condition, and C. operculatus showed better growth performance benefited from morphological responses (plant height, number of blade and leaf area) and endogenous hormone variations. In comparison, S. jambos suffered some negative effects when the well-watered mixed planting was used. However, the competitive relationship under well-watered condition was transformed into mutualistic relationship under waterlogging stress. The mixed planting under waterlogging condition significantly improved the tolerance of C. operculatus and S. jambos to waterlogging stress, compared with the monoculture., Especially, S. jambos showed improvements in root length, root surface area, and redox equilibration between lower levels of relative conductivity, malondialdehyde, and and had increased levels of non-enzymatic antioxidant components, such as reduced glutathione and soluble proteins. The interspecific relationship between C. operculatus and S. jambos was altered by waterlogging stress, and both showed improved tolerance to waterlogging stress. This study can provide a glimmer of light on suitable plant species selection and plant community construction during the revegetation activities in wetland zones. C. operculatus and S. jambos represent potential candidates in wetland restoration in a mixed planting model.

Stakeholder insights into athlete attrition in the high-performance pathway

ObjectivesPrimary: To gain a system-wide perspective on factors leading to athlete attrition from a high-performance sport system (HPSS).Secondary: To identify what a sample of system-wide stakeholders and past athletes value as the most important and feasible attrition factors to address to retain talented athletes. DesignMixed-methods. MethodsConcept mapping was used for qualitative data collection and quantitative data analysis. Sixty-one participants including: (i) past athletes from an Australian state sporting institute; (ii) their families; and (iii) internal and external stakeholders to a HPSS who supported past athletes. ResultsParticipants brainstormed 83 unique statements (i.e. attrition factors) that were mapped into 13 clusters of attrition factors following multidimensional scaling and hierarchical cluster analysis performed on the participants sorting data: ‘abuse and mismanagement of health’; ‘athlete health’; ‘limited support/resourcing’; ‘coaching’; ‘inconsistent processes’; ‘financial and career support’; ‘pathway structure’; ‘organisational dynamics’; ‘competitive stress’; ‘performance potential’; ‘challenges with selection and transition’; ‘psychological state’; and ‘competing non-sport priorities’. ‘Abuse and mismanagement of health’ had the highest mean importance (3.76 out of 5) and feasibility (3.31) rating. The 13 clusters were further grouped into four overarching domains: ‘sport system policy, structure and processes’; ‘pathway structure, transition and support’; ‘individual athlete health and capability’; and ‘whole-of-life demands and priorities’. The domain ‘sport system policy, structure and processes’ contained the most important and feasible clusters. ConclusionsMacro (system-level) and micro (intrapersonal and interpersonal) level athlete attrition factors should be considered together. Athlete health was considered the most important athlete retention issue to address.

Observational Study of Glycemic Impact of Anticipatory and Early-Race Athletic Competition Stress in Type 1 Diabetes.

Athletic competitions and the associated psychological stress are a challenge for people with type 1 diabetes (T1D). This study aims to understand the influence of anticipatory and early race competition stress on blood glucose concentrations and to identify personality, demographic, or behavioral traits indicative in the scope of the impact. Ten recreational athletes with T1D competed in an athletic competition and an exercise-intensity matched non-competition "training" session for comparison. The two hours prior to exercise and the first 30 minutes of exercise were compared between the paired exercise sessions to assess the influence of anticipatory and early race stress. The effectiveness index, average CGM glucose, and the ingested carbohydrate to injected insulin ratio were compared between the paired sessions through regression. In 9 of 12 races studied, an elevated CGM for the race over the individual training session was observed. The rate of change of the CGM during the first 30 minutes of exercise notably differed between the race and training (p = 0.02) with a less rapid decline in CGM occurring during the race for 11 of 12 paired sessions and an increasing CGM trend during the race for 7 of the 12 sessions with the rate of change (mean ± standard deviation) as 1.36 ± 6.07 and -2.59 ± 2.68 mg/dL per 5 minutes for the race and training, respectively. Individuals with longer durations of diabetes often decreased their carbohydrate-to-insulin ratio on race day, taking more insulin, than on the training day while the reverse was noted for those newly diagnosed (r = -0.52, p = 0.05). The presence of athletic competition stress can impact glycemia. With an increasing duration of diabetes, the athletes may be expecting elevated competition glucose concentrations and take preventive measures.

Development of Cancer‐on‐a‐chip Technology for the Study of Tumor Microenvironment and Metabolism

Cancer metabolism has become an area of intense interest. In the 1920s, Otto Warburg showed that cancer cells metabolize glucose to produce lactate and ATP in the presence of oxygen, i.e. aerobic glycolysis, also known as the Warburg Effect. It is now appreciated that cancer cells display a complex metabolic phenotype. Metabolic reprogramming by oncogenes and tumor suppressor genes has been linked to the altered metabolic function of cancer cells. However, the tumor microenvironment (TME), which has different nutrient gradients for glucose, oxygen, and amino acids, has a dramatic effect on cancer cell growth and proliferation. In vivo studies have demonstrated a heterogeneous metabolic phenotype that is difficult to characterize. In addition, the exchange of nutrients and metabolites between the TME, vasculature, and tumor cells has been difficult to fully recapitulate. As a tumor grows, nutrients diffuse from the blood vessels to the cancer cells, in a process partially described by A. Krogh in 1919 through a reaction‐diffusion differential equation. Krogh’s work showed that for typical tissues the oxygen decay radius is around 150μm and we find approximately the same ‘Krogh radius’ for high glucose consumption cancer cells (e.g. MDA‐MB‐231). Thus, around 150μm from a blood vessel exists an oxygen deprived environment that imposes tremendous competitive stresses on the cancer cells for survival. There is rising evidence that this selection pressure favors the transformation to metastasis and causes invasive tumor cell lines to exhibit high glycolytic rates and overall metabolic reprogramming. However, most studies focused on defining the metabolic function of tumor cells have been conducted in vitro, under conditions that do not represent the physiological conditions accurately.Here, we present a cancer‐on‐a‐chip technology that produces a well‐defined 3D TME that can be exposed to precise nutrient stresses such as varying oxygen or other nutrient gradients. In addition, we can determine the metabolic phenotype of cancer cells with varying oncogenic changes and degrees of aggressiveness. Our technology should be able to address the question of the role of the TME on metabolic reprogramming and in particular glycolysis. Our design is based on growing tumor microenvironments inside 360µm ID capillary tubing that can be accessed by 360µm PEEK tubing. To allow/control perfusion through the microenvironment we embed a 70µm nylon fiber into a photocross‐linkable gelatin gel in which the cells are dispersed (MDA‐MB‐231/GFP). After exposing the gel to UV‐light for a few seconds, the nylon fiber is pulled, leaving a perfusable microchannel. Using this technique, we have successfully perfused cell‐laden hydrogels over weeks while observing cell‐growth in a fluorescence microscope.

Sleep and Mental Health Issues in Current and Former Athletes: A Mini Review.

Sleep and mental health are important aspects of human health that work concurrently. However, sleep and mental health disorders are often overlooked and undiagnosed in sport due to the negative stigma associated with them. Evidence suggests that athletes are disproportionately affected by mental health issues and sleep problems. Internal and external pressures contribute to psychological distress. Variable competition times, travel and stress are detrimental to sleep quality. Retirement from sport can deteriorate sleep and psychological wellbeing, particularly for those who retired involuntarily and identify strongly with their athletic role. When untreated, these issues can manifest into a range of clinical disorders. This is concerning, not only for compromised athletic performance, but for general health and wellbeing beyond sport. Previous research has focussed on sleep and health independently among currently competing, or former, athletes. To date, no research has comprehensively assessed and compared sleep complaints and mental health issues between these two cohorts. Moreover, research has failed to obtain data across a variety of different competition levels, sports, and genders, leaving the current scope of the literature narrow. Comorbid conditions (e.g., concussion history, obesity), ex-college athletes, and mental health has been the focus of existing literature post-retirement. Future research would benefit from employing both quantitative and qualitative methodologies to comprehensively assess the prevalence and severity of sleep and mental health disorders across current and retired athletes. Research outcomes would inform education strategies, safeguarding athletes from these issues by reducing negative stigmas associated with help-seeking in sport and ultimately increase self-guided treatment.

Contextual situations in competitions that influence well-being and recovery of Futsal athletes before home official matches

contextual variables associated with competitive stress may affect the perception of the well-being and recovery of futsal athletes. twenty male professional futsal players responded to the Hooper Index (HI) and Total Quality of Recovery Scale (TQR) two hours before eleven official matches. Data were collected on age, predicted game difficulty, distance from the previous game, time interval since the previous game, ranking of the team and opponent, and outcome of the previous game of the team and the opponent (defeat/draw/win). Multivariate logistic regression analysis and the Spearman rank-sum test were used to identify stressors that influenced HI and TQR scores, considering p <0.05. the HI was higher in the National League (11.2 ± 2.9 a.u., p <0.005) compared to the State championship (10.0 ± 2.4 a.u.). The DOMS were higher in National League ( p <0.001) and games preceded by victory ( p <0.005). The HI ( r =-0.53, p <0.001), age ( r =-0.18, p <0.01), and muscle pain ( r = -0.39, p <0.001) correlated with the TQR. The TQR was higher in games preceded by defeat (15.5 ± 1.6) compared to victory (14.6 ± 1.7, p <0.01). The pre-game HI and TQR scores were not significantly different ( p >0.05) in games that ended in victory, draw or defeat. the results suggest that the DOMS scores of HI and TQR reported before at home official Futsal games are correlated with contextual factors including the level of championship and outcome of the last game.

Unsuppressed Striatal Activity and Genetic Risk for Schizophrenia Associated With Individual Cognitive Performance Under Social Competition.

Social competition affects human behaviors by inducing psychosocial stress. The neural and genetic mechanisms of individual differences of cognitive-behavioral response to stressful situations in a competitive context remain unknown. We hypothesized that variation in stress-related brain activation and genetic heterogeneity associated with psychiatric disorders may play roles towards individually differential responses under stress. A total of 419 healthy subjects and 66 patients with schizophrenia were examined functional magnetic resonance imaging during working memory task including social competition stressors. We explored the correlation between stress-induced brain activity and individual working memory performance. The partial least squares regression was performed to examine the genetic correlates between stress-related activity and gene expression data from Allen Human Brain Atlas. Polygenic risk score (PRS) was used to assess individual genetic risk for schizophrenia. Greater suppression of bilateral striatal activity was associated with better behavioral improvement in working memory manipulation under social competition (left: rPearson = -0.245, P = 4.0 × 10-6, right: rPearson = -0.234, P = 1.0 × 10-5). Genes transcriptionally related to stress-induced activation were linked to genetic risk for schizophrenia (PFDR < 0.005). Participants with decreased accuracy under social competition exhibited higher PRS of schizophrenia (t = 2.328, P = .021). Patients with schizophrenia showed less suppressed striatal activity under social stress (F = 13.493, P = 3.5 × 10-4). Striatal activity change and genetic risk for schizophrenia might play a role in the individually behavioral difference in working memory manipulation under stress.

Primary carbon sources and self-induced metabolic landscapes shape community structure in soil bacterial hotspots

Direct observations of the complex and highly dynamic metabolic landscapes that affect the structure and functioning of bacterial communities in natural soil are limited by soil opacity and pore space complexity. In this study, we employ community metabolic network models to predict how the emerging bacterial community composition alters its structure and composition as a function of the primary carbon source in both well-mixed and spatially explicit systems. We provide systematic, experimental validation using a synthetic community comprised of four bacterial species grown on prescribed carbon sources and quantify their abundance using qPCR. Results suggest that community members may benefit from trophic interactions or suffer from increased competitive stress depending on the carbon source. The modeling is expanded to consider interactions in soil-like spatial context. Results show emergence of distinct bacterial community compositions as a function of primary carbon sources typical to soil hotspots (carbohydrates or organic acids). The ability to link genetic information with bacterial community trophic interactions in representative soil environments is a critical first step towards attaining predictability of soil ecological functioning.

Evaluating Sport Psychology Service Delivery for Elite USA Track and Field Athletes: Findings and Recommendations

In preparation for the 2020–2024 Olympic cycle, members of the USA Track and Field sport psychology (SP) subcommittee investigated the SP service provision needs and preferences of 88 elite Olympic-level athletes. A mixed-methods needs analysis was employed, which consisted of surveys, interviews, and a focus group, to help understand current SP usage and shape future SP services for USA Track and Field. Findings highlighted a lack of knowledge and exposure to SP services and a desire for increased contact with SP professionals among athletes, exposing gaps and room for improvement in service delivery. Athletes cited flexibility in terms of service delivery mode and shared common core preferences for mental training, including help managing stress, pressure, emotions, and other challenges of competition and training. The results are discussed in relation to strengthening the effectiveness of service provision through increasing visibility, accessibility, and education regarding the benefits of SP services.

Impact of agronomic practices onFusarium mycotoxin accumulation in maize grain

In the Great Lakes region of North America,Gibberella ear rot (GER), caused byFusarium graminearum, affects grain quality due to the accumulation of mycotoxins. GER severity is strongly influenced by environmental conditions; however, agronomic practices can also influence disease severity and mycotoxin accumulation. In this study, three separate small-plot experiments were conducted at Ridgetown, ON, Canada during 2019 and 2020 under an inoculated-misted system to determineFusarium mycotoxin accumulation as affected by: (1) plant population density; (2) in-row-plant developmental variability; and (3) the effect of integrated Bt refuge genetics. In this study, DON concentrations were at least 49% higher in maize at 113,600 plants/ha compared to 79,000 plants/ha. Moreover, mycotoxin accumulation was higher in plants that were delayed developmentally in the crop row; total DON concentrations were at least 310% higher in late silked plants adjacent to early silked plants. Results of the plant population density and in-row-plant developmental variability suggest that the main driver for mycotoxin accumulation was stress induced by plant competition rather than environmental conditions; this highlights the importance of avoiding plant competitive stress as a strategy to reduce the risks of mycotoxin accumulation. In this study, there was no statistical difference in DON accumulation between the Bt component and the non-Bt component in each of the four hybrids tested; however, there was evidence that hybrids varied in susceptibility, including the Bt and non-Bt components that were paired commercially in a bag of seed maize. Reducing mycotoxins in maize requires integrated management, which includes agronomic considerations. These results indicate that mycotoxins are favoured with high plant populations and plant-to-plant variability in the row, especially in susceptible hybrids.

Free Papers Compiled

Free Papers Compiled

Mental Strength among MSU Athletes in Sports Performance

This study used a descriptive-correlation type of research to assess the mental toughness among MSU Marawi athletes in sports performance in terms of level of competition and rank among male and female varsity athletes in the events of Athletics, Badminton, Basketball, Chess, Sepak Takraw, and Soccer. A total of 83 varsity athletes (16 females and 67 males) of the MSU in Marawi City were the respondents of the study. Data was gathered using the Mental Toughness Questionnaire made by Allan Goldberg (1998). The findings revealed that the playing experience showed significant relationship with the level of participation. It was concluded that the department of Athletics should give more emphasis on training and allow participation of MSU varsity in different competition or tournament in order to improve their talent and skills in various sports that they engaged, in order to manage competitive stress and to enhance their mental capability to handle those pressures, stressors and problems during the competition which contributes to their performance enhancement. To also, encourage more participation of the MSU varsity athletes, particularly newbie regardless of age, gender, and skills status.

Interactive effects of salinity and plant density on the growth of Cyperus arenarius, a sand dune stabilizer

Competition and environmental stress are crucial factors for structuring plant population in natural habitats. Cyperus arenarius, a sedge of coastal sand dunes habitat, is a suitable species for coastal restoration and dune stabilization, but how salinity and plant density interact in affecting its growth is still unknown. Here, growth, survival, and physiological responses of C. arenarius to salinity (sea-salt) and plant density were investigated. A set of growth experiments in which combinations of 4 salinity levels (0, 2, 4, and 6 S m-1 sea-salt) and 3 planting densities (2, 5, 8 plants pot-1) were tested under controlled greenhouse conditions. Plant biomass and height were optimal in 2 S m-1 sea-salt while biomass decreased considerably at 6 S m-1. The inhibitory effect of high salinity was more severe in shoot dry mass relative to that of root dry mass, which resulted in increasing root/shoot dry mass ratio. Tissue succulence declined while the accumulation of Na and Cl increased with the increment of salinity, especially in root. Plant nutrient (K+, Ca2+, and Mg2+) contents decreased under salinity. Plant height was more sensitive with increasing plant density than biomass. High plant density (8 plants pot-1) lowered tissue biomass and water content in non-saline conditions to the similar levels observed under the 6 S m-1 seasalt salinity. Moreover, the combined effect of high salinity and increasing plant density had highly negative effects on plant growth attributes and water relations than their individual effect.

Land Equivalent Ratio of Cowpea–Sorghum Relay Intercrop as Affected by Different Cattle Manure Application Rates Under Smallholder Farming System

Poor soil fertility is a major challenge to crop production in the communal farming areas of Zimbabwe. Intercropping legumes and cereals is a common soil fertility management technology among the farmers. A 3-year field experiment was conducted to evaluate cowpea–sorghum relay intercropping advantages in response to different cattle manure application rates. A 3 × 4 factorial experiment laid in a completely randomized block design (CRBD) with three replicates was conducted. The treatments were three cropping systems (sorghum sole, cowpea sole, and cowpea–sorghum intercrop) and four cattle manure application rates (0, 50, 75, and 100%). Crop growth rate (CGR), grain yield, harvest index (HI), relative competitive ability of each crop, and land equivalent ratio (LER) were measured. Analysis of variance and non-linear regression analyses were done to determine the yield benefits of cowpea–sorghum intercrop and estimate the relative competitive ability, respectively. Application of &amp;gt;75% cattle manure in a cowpea–sorghum intercrop enhanced the sorghum grain yield (75%) and HI (125%) of unmanured cowpea–sorghum plots. Cowpeas had higher CGR (159.6, 166.7 and 149.5 g m−2 day−1 at 7, 21, and 35 days after planting, respectively) at &amp;gt;75% cattle manure application rates on both intercrop and sole cropping than sorghum but with lower grain yield (1.4 t ha−1). Intraspecific competitive stress in sorghum was reduced at a high (&amp;gt;75%) quantity of manure applied. The effects of the intraspecific competition in cowpea were stronger (0.693) on grain yield than biomass at &amp;gt;75% manure application rates. The LER was &amp;gt;1 in all the treatments and was highest (2.73) under the cowpea–sorghum relay intercrop without cattle manure. Cattle manure application at 75% in a cowpea–sorghum intercrop enhanced the grain yield in sorghum and vegetative growth in cowpeas. It is therefore recommended to use the &amp;gt;75% cattle manure application rate in the intercrop if one wants higher grain in sorghum and high biomass in cowpeas possibly for fodder. Further studies are recommended to quantify the rate of increase in available N under the cowpea–sorghum relay intercrop with &amp;gt;75% cattle manure application rates.

Climate and Competitive Status Modulate the Variation in Secondary Metabolites More in Leaves Than in Fine Roots of Betula pendula.

Plant secondary metabolites have many important functions; they also determine the productivity and resilience of trees under climate change. The effects of environmental factors on secondary metabolites are much better understood in above-ground than in below-ground part of the tree. Competition is a crucial biotic stress factor, but little is known about the interaction effect of climate and competition on the secondary chemistry of trees. Moreover, competition effect is usually overlooked when analyzing the sources of variation in the secondary chemistry. Our aim was to clarify the effects of competitive status, within-crown light environment, and climate on the secondary chemistry of silver birch (Betula pendula Roth). We sampled leaves (from upper and lower crown) and fine roots from competitively dominant and suppressed B. pendula trees in plantations along a latitudinal gradient (56–67° N) in Fennoscandia, with mean annual temperature (MAT) range: −1 to 8°C. Secondary metabolites in leaves (SML) and fine roots (SMFR) were determined with an HPLC-qTOF mass spectrometer. We found that SML content increased significantly with MAT. The effect of competitive stress on SML strengthened in colder climates (MAT<4°C). Competition and shade initiated a few similar responses in SML. SMFR varied less with MAT. Suppressed trees allocated relatively more resources to SML in warmer climates and to SMFR in colder ones. Our study revealed that the content and profile of secondary metabolites (mostly phenolic defense compounds and growth regulators) in leaves of B. pendula varied with climate and reflected the trees’ defense requirements against herbivory, exposure to irradiance, and competitive status (resource supply). The metabolic profile of fine roots reflected, besides defense requirements, also different below-ground competition strategies in warmer and colder climates. An increase in carbon assimilation to secondary compounds can be expected at northern latitudes due to climate change.

The impact of competitive stress on photosynthetic indices in apple tree leaves

The impact of competitive stress on photosynthetic indices in apple tree leaves

Longitudinal analysis of stressors, stress, coping and coping effectiveness in elite esports athletes

ObjectiveThe current study aimed to longitudinally examine the stressors, stress appraisal, coping, and coping effectiveness experienced by elite esports athletes. DesignSix elite male League of Legends (LoL) athletes, competing in the Oceanic Challenger Series (OCS), completed diaries over the 2020 competitive season (87 days). MethodAthletes completed weekly diaries after three events: solo training, team training, and competitive matches. Each diary collected data on the stressors experienced, stressor intensity and threat/challenge perception (appraisal), coping strategies used, and perceived coping effectiveness. ResultsGeneral performance, outcome, critical moment performance, and teammate mistakes accounted for 55% of the stressors reported. More stressors were reported in competitive diaries than in training diaries. Competitive stressors were rated as being more intense than training stressors. There were no differences in overall challenge and threat perception, but performance stressors were more likely to be perceived as a challenge, and teammate stressors were more likely to be perceived as a threat. Problem-focused coping (PFC) was the most frequently employed coping strategy. PFC and emotion-focused coping (EFC) strategies were perceived as more effective at reducing stress than avoidance coping (AC). ConclusionsElite LoL athletes experienced a small number of reoccurring stressors over an 87-day competitive period. Athletes reported more stressors around competitive matches and perceived competitive stressors as more intense than team and solo training stressors. Similarly to traditional sports athletes, PFC strategies were the most frequently employed and, PFC and EFC were rated as being more effective than AC.