Influence Of Environmental Stressors Research Articles

Glyphosate-environmental variables interaction: How does it affect the parasite Chordodes nobilii?

The worldwide used herbicide Glyphosate can interact with environmental variables, but there is limited information on the influence of environmental stressors on its toxicity. Environmental changes could modify glyphosate effects on non-target organisms, including parasites such as gordiids. The freshwater microscopic larvae of the gordiid Chordodes nobilii are sensitive to several pollutants and environmental variables, but their combined effect has not been evaluated yet. The aim of this study was to evaluate the impact of temperature, pH and exposure time on the toxicity of Glyphosate to C. nobilii larvae. A protocol was followed to evaluate the infectivity of larvae treated with factorial combinations of concentration (0 and 0.067 mg/L), exposure time (24 and 48 h), temperature (18, 23 and 28 °C), and pH (7, 8 and 9). The reference values were 23 °C, pH 8 and 48 h. The interaction effect on the infectivity of gordiid larvae was assessed post-exposure using Aedes aegyptii larvae as host. Results were evaluated using GLMM, which does not require data transformation. The modeling results revealed three highly significant triple interactions. Glyphosate toxicity varied depending on the combination of variables, with a decrease being observed after 24 h-exposure at pH 7 and 23 °C. Glyphosate and 28 °C combination led to slightly reduced infectivity compared to temperature alone. This study is the first to report the combined effects of glyphosate, temperature, pH and time on a freshwater animal. It demonstrates that a specific combination of factors determines the effect of glyphosate on a non-target organism. The potential use of C. nobilli as a bioindicator is discussed. In the context of global warming and considering that the behavioral manipulation of terrestrial hosts by gordiids can shape community structure and the energy flow through food webs, our results raise concerns about possible negative effects of climate change on host-parasite dynamics.

Effects of temperature and feeding regime on cortisol concentrations in scales of Atlantic salmon post-smolts

Anadromous fish are vulnerable to anthropogenic and environmental stressors including pollution, rising temperatures, and changes in food availability. Knowledge of how fish respond to specific stressors aid our understanding of population declines and inform predictions of how populations will react to future environmental change. There is increasing interest in using cortisol measurements from fish scales to measure chronic stress in fish, however the effects of increased metabolic rate on scale cortisol dynamics must also be considered. This study examines the effect of temperature and feeding conditions on scale cortisol in Atlantic salmon (Salmo salar). Post-smolts were subjected to three different temperatures (6, 10.5 and 15 °C) and four feeding/starvation treatments over a 12-week period. Females held at 6 and 15 °C had significantly higher scale cortisol levels than those held at 10.5 °C, while rearing temperature had no effect on scale cortisol in males. The increase in scale cortisol at 6 °C indicated that temperature related differences were not driven solely by metabolic rate. A two-week starvation period produced an increase in scale cortisol in males and females held at 10.5 °C but not at 6 °C or 15 °C. The study demonstrates that scale cortisol fluctuations can be detected in a low amount (∼10 mg) of Atlantic salmon scales for monitoring of the physiological stress response. Scale cortisol shows potential for monitoring physiological responses during the marine phase in Atlantic salmon. However, the influence of environmental stressors on scale cortisol needs to be better understood, with consideration for sex-specific and interactive effects.

Metabolomics insight into the influence of environmental factors in responses of freshwater biofilms to the model herbicide diuron.

Freshwater biofilms have been increasingly used during the last decade in ecotoxicology due to their ecological relevance to assess the effect(s) of environmental stress at the community level. Despite growing knowledge about the effect of various stressors on the structure and the function of these microbial communities, a strong research effort is still required to better understand their response to chemical stress and the influence of environmental stressors in this response. To tackle this challenge, untargeted metabolomics is an approach of choice because of its capacity to give an integrative picture of the exposure to multiple stress and associated effect as well as identifying the molecular pathways involved in these responses. In this context, the present study aimed to explore the use of an untargeted metabolomics approach to unravel at the molecular/biochemical level the response of the whole biofilm to chemical stress and the influence of various environmental factors in this response. To this end, archived high-resolution mass spectrometry data from previous experiments at our laboratory on the effect of the model photosynthesis inhibitor diuron on freshwater biofilm were investigated by using innovative solutions for OMICs data (e.g., DRomics) and more usual chemometric approaches (multivariate and univariate statistical analyses). The results showed a faster (1 min) and more sensitive response of the metabolome to diuron than usual functional descriptors, including photosynthesis. Also, the metabolomics response to diuron resulted from metabolites following various trends (increasing, decreasing, U/bell shape) along increasing concentration and time. This metabolomics response was influenced by the temperature, photoperiod, and flow. A focus on a plant-specific omega-3 (eicosapentaenoic acid) playing a key role in the trophic chain highlighted the potential relevance of metabolomics approach to establish the link between molecular alteration and ecosystem structure/functioning impairment but also how complex is the response and the influence of all the tested factors on this response at the metabolomics level. Altogether, our results underline that more fundamental researches are needed to decipher the metabolomics response of freshwater biofilm to chemical stress and its link with physiological, structural, and functional responses toward the unraveling of adverse outcome pathways (AOP) for key ecosystem functions (e.g., primary production).

Phenotypic differentiation among native, expansive and introduced populations influences invasion success

AbstractAimHumans influence species distributions by modifying the environment and by dispersing species beyond their natural ranges. Populations of species that have established in disjunct regions of the world may exhibit trait differentiation from native populations due to founder effects and adaptations to selection pressures in each distributional region. We compared multiple native, expansive and introduced populations of a single species across the world, considering the influence of environmental stressors and transgenerational effects.LocationUnited States Gulf and Atlantic coasts, United States interior, European Atlantic and Mediterranean coasts, east coast of Australia.TaxonBaccharis halimifolia L. (eastern baccharis).MethodsWe monitored seed germination, seedling emergence, survival and early growth in a common garden experiment, conducted with over 18,200 seeds from 80 populations. We also evaluated the influence of environmental stress and maternal traits on progeny performance.ResultsIntroduced European Atlantic populations had faster germination and early growth than native populations. However, this was not the case for the more recently naturalized European Mediterranean populations. Introduced Australian populations grew faster than native populations in non‐saline environments but had lower survival in saline conditions commonly encountered in the native range. Similarly, expansive inland US populations germinated faster than coastal native populations in non‐saline environments but grew and germinated more slowly in saline environments. Maternal inflorescence and plant size were positively related with seed germination and seedling survival, whereas flower abundance was positively correlated with seedling early growth and survival. However, maternal traits explained a much lower fraction of the total variation in early demographic stages of B. halimifolia than did distributional range.Main conclusionsPhenotypic differentiation could allow B. halimifolia to adapt to different biotic and abiotic selection pressures found in each distributional range, potentially contributing to its success in introduced and expansive ranges.

Medieval versus recent environmental conditions in the Baltic Proper, what was different a thousand years ago?

A sediment record from the western Gotland Basin, northwestern Baltic Proper, covering the last 1200 years, was investigated for past changes in climate and the environment using diatoms as a proxy. The aim is to compare the environmental conditions reconstructed during Medieval times with settings occurring the last century under influence of environmental stressors like eutrophication and climate change. The study core records more marine conditions in the western Gotland Basin surface waters during the Medieval Climate Anomaly (MCA; 950–1250C.E.), with a salinity of at least 8 psu compared to the present 6.5 psu. The higher salinity together with a strong summer-autumn stratification caused by warmer climate resulted in extensive long-lasting diatom blooms of Pseudosolenia calcar-avis, effectively enhancing the vertical export of organic carbon to the sediment and contributing to benthic hypoxia. Accordingly, our data support that a warm and dry climate induced the extensive hypoxic areas in the open Baltic Sea during the MCA. During the Little ice Age (LIA; 1400–1700C.E.), the study core records oxic bottom water conditions, decreasing salinity and less primary production. This was succeeded during the 20th century, about 1940, by environmental changes caused by human-induced eutrophication. Impact of climate change is visible in the diatom composition data starting about 1975C.E. and becoming more pronounced 2000C.E., visible as an increase of taxa that thrived in stratified waters during autumn blooms typically due to climate warming.

Offshore workers and health behaviour change: an exploration using the Theoretical Domains Framework.

Previous research has identified the importance of promoting behaviour change within the offshore workforce. This qualitative study sought to: identify self-care behaviours perceived to require behaviour change within the offshore workforce, and explore perceived potential behavioural determinants. This study included the perspectives of both offshore workers (OWs, n = 16) and healthcare practitioners (HCPs, n = 12) from the global workforce. Telephone interviews were conducted, recorded electronically and transcribed. Transcripts were analysed independently by two researchers using a Framework Approach and the Theoretical Domains Framework (TDF) to support coding. Healthy eating and alcohol intake were behaviours perceived by OWs and HCPs to require change within the offshore workforce. Knowledge (e.g. availability of nutritional knowledge), intentions (e.g. role of motivation), memory, attention and decision process (e.g. effect of boredom), environmental context and resources (e.g. influence of environmental stressors), social influences (e.g. influence of others), emotion (e.g. influence of emotional state) and behavioural regulation (e.g. influence of willpower). TDF domains were reported by both OWs and HCPs in relation to OWs' healthy eating and physical activity behaviours. The determinants identified as mechanisms of behaviour may be targeted in future interventions which aim to promote engagement in self-care within the offshore workforce.

M31 - Gene Expression In Blood of Children And Adolescents: Influence of Environmental Stressors On Major Depressive Disorder

Background Studies investigating major depressive disorder (MDD) in childhood and adolescence are relevant to understand relative contributions from either genetic and environmental factors on MDD, since early stages of disease have less influence of illness exposure. We aimed to investigate peripheral mRNA expression of 12 genes related to HPA axis (NR3C1, FKBP5), inflammation (TNF, TNFR1, TNFR2, IL1B), neurodevelopment (DISC1, PDE4B, QKI), and neurotransmission (SLC1A4, GLUL, COMT) in blood of children and adolescents with MDD and to test if history of childhood maltreatment (CM) or prenatal alcohol (PA) and tobacco (PT) exposure (environmental stressors that influences psychiatry disorders risk) could affect MDD via gene expression. Methods mRNA levels in whole blood were compared among 20 children and adolescents with MDD diagnosis (MDD group), 48 subjects without MDD diagnosis but with high levels of depressive symptoms (DS group) and 61 healthy controls (HC group). We also performed a mediation model in which CM/PA/PT exposure was the independent variable, MDD was the outcome and gene expression was the intermediary variable. Results NR3C1, TNF, TNFR1 and IL1B expression levels were significantly lower in MDD group compared to the other groups. The direct effects of CM, PA and PT exposure on MDD were not significant. Moreover, there was not an indirect effect of PA or PT exposure on MDD. However, there was an indirect effect on the aggregation of these four genes expressions, mediating the relationship between CM and MDD. Discussion In the largest study investigating gene expression in children with MDD, we demonstrated that the NR3C1, TNF, TNFR1 and IL1B expression are related to the MDD and conjunctly mediated the effect of history of CM on risk of developing the disorder, supporting a role of glucocorticoids and inflammation as possible effectors of environmental distress on this disorder.

Gastric acid response to acute exposure to hypergravity.

The influence of environmental stressors on the pathogenesis of gastrointestinal disease has received increased awareness. Stress affects different physiological functions of the gastrointestinal tract, including gastric acid secretion and mucosal blood flow. Repeated exposures of rapid-onset, highly-sustained hypergravity cause severe physical stress in the pilot. Although the effects of exposure to hypergravity on cardiovascular and cerebral functions have been the subjects of numerous studies, crucial information regarding pathophysiological changes in the gastrointestinal tract following hypergravity exposure is lacking. In this study, we investigated the effects of acute exposure to hypergravity on gastric secretory activity and gastrin release. Male Sprague-Dawley rats were exposed to +10Gz three times for 3 min. Gastric juice and blood were collected. The volume and total acidity of gastric juice, and the plasma gastrin level was measured. Acute exposure to +10Gz significantly decreased the gastric juice parameters. The gastric juice volume and total acidity of hypergravity-exposed rats were 3.54 ± 0.32 mL/100 g and 84.90 ± 5.17 mEq/L, respectively, which were significantly lower than those of the nonexposed rats (4.62 ± 0.39 mL/100 g and 97.37 ± 5.42 mEq/L; P < 0.001 and P < 0.001, respectively). In contrast, plasma gastrin level was not significantly altered following hypergravity exposure. We demonstrated that acute exposure to hypergravity led to a significant decrease in the gastric juice volume and acidity but did not alter the plasma gastrin level.

Influence of environmental stressors and grazer immigration on ecosystem properties of an experimental eelgrass community

Anthropogenic stressors associated with climate change and shoreline development are increasingly impacting important habitats. But when multiple stressors act simultaneously, the results are often difficult to predict. Effects of multiple anthropogenic stressors and their interactions with community processes are of particular concern in estuarine habitats because of their vulnerability to anthropogenic impacts and their provision of valuable ecosystem services such as fisheries production and sediment stabilization. Two stressors, warming temperatures and reduced light availability due to suspended materials, are expected to simultaneously affect important habitats such as seagrass systems, but the impacts of these stressors may be influenced by community processes such as immigration. Immigration of propagules can alter diversity and relative species abundances, rescue populations from extinction, and modify the capacity of communities to respond to environmental conditions. Using an experimental eelgrass (Zostera marina) system, we examined how warming, reduced light availability (shading), and periodic immigration of crustacean grazers influenced diversity, biomass, and structure of this community. Shading generally had large effects, and reduced biomass of all primary producers but did not affect grazer biomass. Warming reduced epiphytic algal biomass but only in the absence of grazers, while it increased sessile invertebrate biomass overall. Immigration of crustacean grazers did not interact significantly with stressors, and had little effect overall. Immigration did not influence diversity of grazers, relative abundance of grazer species, or biomass of primary producers and sessile invertebrates, however, it did increase biomass of grazers. Overall, reduced light availability by shading had strong effects on primary producers, whereas warming generally had weaker effects that differed with grazer presence. Thus, our results show that the impacts of reduced light availability and warming were independent and context specific, while crustacean grazer immigration effects were minimal in this model eelgrass system.

Assessing the effects of disease and bleaching on Florida Keys corals by fitting population models to data

Coral diseases have increased in frequency over the past few decades and have important influences on the structure and composition of coral reef communities. However, there is limited information on the etiologies of many coral diseases, and pathways through which coral diseases are acquired and transmitted are still in question. Furthermore, it is difficult to assess the impacts of disease on coral populations because outbreaks often co-occur with temperature-induced bleaching and anthropogenic stressors. We developed spatially explicit population models of coral disease and bleaching dynamics to quantify the impact of six common diseases on Florida Keys corals, including aspergillosis, dark spots, white band, white plague, white patch, and Caribbean yellow band. Models were fit to an 8-year data set of coral abundance, disease prevalence, and bleaching prevalence. Model selection was used to assess alternative pathways for disease transmission, and the influence of environmental stressors, including sea temperature and human population density, on disease prevalence and coral mortality. Classic disease transmission from contagious to susceptible colonies provided the best-fit model only for aspergillosis. For other diseases, external disease forcing, such as through a vector or directly from pathogens in the environment, provided the best fit to observed data. Estimates of disease reproductive ratio values ( R 0) were less than one for each disease, indicating coral colonies were below densities required for diseases to become established through contagious spread alone. Incidences of white band and white patch disease were associated with greater susceptibility or slower recovery of bleached colonies, and no disease outbreaks were associated with periods of elevated sea temperatures alone. Projections of best-fit models indicated that, atleast during the period of this study, disease and bleaching did not have substantial impacts on populations and impaired rates of population growth appeared to be attributable to other stressors. By applying epidemiological models to field data, our study gives qualitative insights into the dynamics of coral diseases, relative stressor impacts, and directions for future research.

Adaptability in tropical beef cattle: genetic parameters of growth, adaptive and temperament traits in a crossbred population

Adaptability in tropical beef cattle can be assessed by measurable traits such as growth under the influence of environmental stressors, by parasite resistance as measured by indicator traits such as tick counts (TICK) and faecal egg counts of worms (EPG), by heat resistance as measured by indicator traits such as rectal temperatures (TEMP) and coat scores (COAT) and, to a certain extent, temperament of the animal as measured by flight time (FT). Data from a crossbreeding experiment involving various genotypes derived from tropically adapted British, Sanga-derived, Zebu cross, Zebu and Continental beef cattle breeds were analysed to estimate variance components and genetic parameters of growth, adaptive and temperament traits. Breed group differences were accounted for by including fractional coefficients of direct and maternal additive and dominance genetic effects as covariates. In the univariate analyses, 6 models were compared ranging from the simplest model with animal as the only random effect to the full model comprising direct and maternal additive genetic variance and their covariance and the permanent environment effect due to dam (growth traits) and animal (adaptive and temperament traits). The heritability estimates were 0.41, 0.21, 0.19, 0.28, 0.41 and 0.15 for birth weight (BWT), weaning weight (WWT), preweaning average daily gain (PREADG), yearling weight (YWT), final weight at about 18 months of age (FWT) and post-weaning average daily gain (POADG), respectively. The maternal component of additive genetic variance as a proportion of phenotypic variance in BWT, WWT and PREADG was 0.15, 0.10 and 0.10, respectively. The heritability estimates for TICK, EPG, TEMP, COAT and FT were 0.13, 0.24, 0.12, 0.26 and 0.20, respectively. High positive genetic and phenotypic correlations were observed among growth traits. Low (insignificant) genetic correlations were observed between TICK, EPG and growth traits. However, genetic correlations between growth traits and heat tolerance traits (TEMP and COAT) were moderately negative implying that as the ability of an animal to handle heat stress increases, growth also increases at the genetic level. Genetic correlations among TICK, EPG and TEMP were moderately positive, suggesting that closely-linked genes affect these adaptive traits. The significant negative genetic relationship between TEMP and FT suggests that cattle with high heat resistance have desirable temperament. With the increasing crossbred populations in the northern Australian beef cattle industry, the best breeding strategy should aim to exploit both crossbreeding and within population selection to make improvements in growth, adaptive and temperament traits to increase overall productivity of the enterprise.

Lack of effect of psychosocial stress on maternal corticotropin-releasing factor and catecholamine levels at 28 weeks' gestation

Corticotropin-releasing factor (CRF) and catecholamines are among the major hormones activated during the adaptive response to stressful stimuli. In pregnant women, serum CRF and catecholamines levels increase during labor and preterm delivery. The aim of the present study was to evaluate whether psychosocial stress measures are correlated with serum CRF or urinary catecholamine [ie, epinephrine, norepinephrine (NE), dopamine (DA)] levels in healthy midtrimester pregnant women. A large group of white pregnant women (n = 382) participated in the present study. The Work Conditions Questionnaire and the Psychiatric Epidemiology Research Interview were administered to measure job stress and general life stress, respectively. Urine and blood specimens were collected at 28 weeks of gestation at the time of psychosocial evaluation. Epinephrine, NE, and DA were quantified in the urine by a highly sensitive method based on an amperometric detector. Serum CRF and cortisol levels were measured in blood specimens by using specific radioimmunoassays. Serum CRF and cortisol levels did not vary between patients with high and low scores on psychological tests, and no correlation was found between CRF and cortisol levels. One job stress measure, low job latitude, was significantly associated with a mild increase in NE and DA levels in the afternoon and night (P < .05, analysis of variance). Serum cortisol levels were inversely correlated with NE in the morning (r = -0.447; P =.002) and night segments (r = -0.391; P = .007) and with DA in the night period (r = -0.367; P = .013). The absence of a significant relationship between CRF/cortisol and psychosocial stress measures in pregnant women suggests that the hypothalamic-pituitary-adrenal response to psychosocial stress may be masked at midtrimester by the constantly high levels of placental CRF, whose control is beyond the influence of environmental stressors.

Biology and medicine of soccer: An update

Recent literature on the biology and medicine of soccer (primarily since 1990) has been accumulated by a combination of computer searching of relevant databases and review of the author's extensive files. From a total of 9681 papers, 540 were selected for closer scrutiny and 370 are discussed in the present review. These articles cover patterns of play and the resulting energy demands, the nutritional requirements of soccer, the anthropometric, physiological, biochemical and immunological characteristics of successful players, the influence of environmental stressors (heat, cold, hypoxia and time zone shifts), special features of female and junior competitors, selected issues in training, and the incidence and prevention of injuries. The information presented has important implications for the safety and success of soccer players; the challenge is now to ensure that this information is understood and acted upon by coaches and individual team members.