Common Environmental Stressors Research Articles

Outcrossing in Caenorhabditis elegans increases in response to food limitation.

Theory predicts that organisms should diversify their offspring when faced with a stressful environment. This prediction has received empirical support across diverse groups of organisms and stressors. For example, when encountered by Caenorhabditis elegans during early development, food limitation (a common environmental stressor) induces the nematodes to arrest in a developmental stage called dauer and to increase their propensity to outcross when they are subsequently provided with food and enabled to develop to maturity. Here we tested whether food limitation first encountered during late development/early adulthood can also induce increased outcrossing propensity in C. elegans. Previously well-fed C. elegans increased their propensity to outcross when challenged with food limitation during the final larval stage of development and into early adulthood, relative to continuously well-fed (control) nematodes. Our results thus support previous research demonstrating that the stress of food limitation can induce increased outcrossing propensity in C. elegans. Furthermore, our results expand on previous work by showing that food limitation can still increase outcrossing propensity even when it is not encountered until late development, and this can occur independently of the developmental and gene expression changes associated with dauer.

Investigating the efficacy of topical application of Ipomoea carnea herbal cream in preventing skin damage induced by UVB radiation in a rat model

Ultraviolet-B irradiation is a common environmental stressor that has detrimental effects on human skin. Natural sunscreens are well-known for their ability to benefit inflamed sunburn and dry skin. This study examined the effect of formulated Ipomoea carnea herbal cream on UVB-induced skin damage. We screened the bioactive compounds of I. carnea crude extract, showing significant antioxidant activity. Additionally, we evaluated the cytotoxicity, revealing that I. carnea extract has less toxicity to vero cells (IC50 98.45 μg/mL) than to A375 cells (IC50 48.95 μg/mL). Based on this, we formulated the I. carnea herbal cream (FIHC) at 50, 100 and 200 mg concentrations and evaluated its organoleptic characteristics. Then, the rats were exposed to UVB radiation (32,800 J/m2) four times/week (on alternate days) before the cream was applied topically to the dorsal skin surface. Under UVB stress without treatment, rats showed deep dermal damage. In contrast, rats treated with the FIHC exhibited significantly reduced sunburn. Moreover, the histopathological and biochemical assays were confirmed by the topical application of FIHC, which had potentially reduced the skin elasticity and maintained the imbalanced enzyme and non-enzymatic antioxidant activity. Our findings amply demonstrate that the FIHC significantly accelerated the recovery of UVB-induced lesions through antioxidant and down-regulation of skin photodamage.

Physiology in Perspective

EditorialPhysiology in PerspectiveNikki ForresterNikki ForresterAmerican Physiological Society, Rockville, MarylandPublished Online:20 Jan 2023https://doi.org/10.1152/physiol.00002.2023MoreSectionsPDF (79 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat This issue of Physiology features four outstanding review articles that summarize current knowledge and uncover areas for future research across a range of topics in physiology. First, we analyze how developmental hypoxia affects the vertebrate cardiovascular system. Next, we describe the role of coupling delay in synchronized oscillations, with a focus on the segmentation clock. Third, we evaluate mechanistic models for how the insular cortex regulates the physiological needs of organisms and their need-driven behaviors. Finally, we explore how breakthroughs in precision medicine can improve diagnoses and treatments for people with mental illness.The environment during early development can have profound effects on an organism’s morphology, physiology, function, and behavior. Adaptive responses to adverse temperature, oxygen, or pH conditions can persist throughout an organism’s lifetime and even across generations through epigenetic changes. Hypoxia, or an insufficient supply of oxygen, is a particularly common and disruptive environmental stressor. Whereas oxygen levels are tightly regulated in mammalian wombs, embryonic birds and ectothermic vertebrates can experience highly variable oxygen levels during development. Because the vertebrate cardiovascular system is heavily involved in mitigating oxygen deprivation, it is especially sensitive to developmental hypoxia. In this review, Galli et al. (1) conduct a comparative analysis of vertebrate cardiovascular responses to developmental hypoxia to identify common and novel responses as well as potential medical and ecological implications.In segmented animals, cells must be able to communicate with one another to ensure the proper segmentation of somites. Cells achieve this by sending and receiving information via signaling pathways, such as the Notch signaling pathway. The Notch signaling pathway plays a critical role in somitogenesis by coordinating the segmentation clock, which is a molecular oscillator that regulates the periodic formation of somites in embryos. If these oscillations are out of synchrony between cells, then somite segmentation does not occur properly, potentially causing respiratory complications or death. Mathematical models suggest that the time required to transmit signals between cells, or coupling delay, is important for oscillatory dynamics, but the biological implications of coupling delay remain less understood. In this review, Kageyama et al. (2) describe the biological importance of coupling delay in synchronized oscillations of the segmentation clock and reveal areas for future analysis.All cellular organisms must maintain the appropriate intracellular environment. When the necessary conditions for homeostasis are not met by the environment and cannot be regulated internally, organisms must take actions to fulfill their physiological needs. In multicellular animals, this process often involves powerful motivations, such as thirst or hunger, and the concerted action of different tissues and organs. However, the neural basis of the motivations that drive these behaviors is relatively unclear. Animal models suggest that the insular cortex receives internal sensory information and regulates physiological needs and need-driven behavior. In this review, Prilutski and Livneh (3) discuss mechanistic models for how the insular cortex regulates physiological needs, develop a framework for testing these models, and outline implications for various diseases and disorders.Diagnostic errors in mental disorders are common, with low inter-reliability and some studies reporting misdiagnosis rates of up to 66%. Even when patients are correctly diagnosed, the lack of clinical guidelines for drug selection can complicate a psychiatrist’s ability to select accurate treatments. Precision medicine holds the potential to improve care for patients with mental illness, in part through comprehensively exploring the physiological basis of such conditions. In addition, recent advancements in multi-omics technologies and data analytics can pave the way for better diagnostic tests and treatment decisions. In this review, Scala et al. (4) explore how breakthroughs in precision medicine and multi-omic physiological profiling can improve disease classification, psychiatric diagnoses, and treatments.No conflicts of interest, financial or otherwise, are declared by the author.

Long-term tracking and quantification of individual behavior in bumble bee colonies

Social insects are ecologically dominant and provide vital ecosystem services. It is critical to understand collective responses of social insects such as bees to ecological perturbations. However, studying behavior of individual insects across entire colonies and across timescales relevant for colony performance (i.e., days or weeks) remains a central challenge. Here, we describe an approach for long-term monitoring of individuals within multiple bumble bee (Bombus spp.) colonies that combines the complementary strengths of multiple existing methods. Specifically, we combine (a) automated monitoring, (b) fiducial tag tracking, and (c) pose estimation to quantify behavior across multiple colonies over a 48 h period. Finally, we demonstrate the benefits of this approach by quantifying an important but subtle behavior (antennal activity) in bumble bee colonies, and how this behavior is impacted by a common environmental stressor (a neonicotinoid pesticide).

Reprotoxic Impact of Environment, Diet, and Behavior.

Reproductive health is progressively declining due to multiples endogenous and exogenous factors, such as environmental contaminants, diet and behavior. Accumulated evidences confirm that fertility and reproductive function have been adversely affected by exposure to chemical contaminants released in the environment. Today, the impact of diet and behavior on reproductive processes is also receiving special attention from the scientific community. Indeed, a close relationship between diet and fertility has been proven. Furthermore, a combination of unhealthy behavior, such as exposure to hazardous compounds and stress factors, poses living organisms at higher risk of reprotoxic effects. In particular, it has been described that poor life behaviors are associated with reduced male and female fertility due to decreased gamete quality and function. Most of the erroneous behaviors are, furthermore, a source of oxidative stress that, leading to epigenetic alterations, results in an impaired reproductive fitness. This review reports the detrimental impact of the most common environmental chemical stressors, diet, and behavior on reproductive functionality and success. Although clear evidences are still scarce, reassuring data are provided that a healthy diet and reverting unhealthy lifestyles may be of help to recover physiological reproductive conditions.

Physiological and Molecular Responses in the Gill of the Swimming Crab Portunus trituberculatus During Long-Term Ammonia Stress

Ammonia is a common environmental stressor encountered during aquaculture, and is a significant concern due to its adverse biological effects on vertebrate and invertebrate including crustaceans. However, little information is available on physiological and molecular responses in crustaceans under long-term ammonia exposure, which often occurs in aquaculture practices. Here, we investigated temporal physiological and molecular responses in the gills, the main ammonia excretion organ, of the swimming crab Portunus trituberculatus following long-term (4 weeks) exposure to three different ammonia nitrogen concentrations (2, 4, and 8 mg l–1), in comparison to seawater (ammonia nitrogen below 0.03 mg l–1). The results revealed that after ammonia stress, the ammonia excretion and detoxification pathways were initially up-regulated. These processes appear compromised as the exposure duration extended, leading to accumulation of hemolymph ammonia, which coincided with the reduction of adenosine 5′-triphosphate (ATP) and adenylate energy charge (AEC). Considering that ammonia excretion and detoxification are highly energy-consuming, the depression of these pathways are, at least partly, associated with disruption of energy homeostasis in gills after prolonged ammonia exposure. Furthermore, our results indicated that long-term ammonia exposure can impair the antioxidant defense and result in increased lipid peroxidation, as well as induce endoplasmic reticulum stress, which in turn lead to apoptosis through p53-bax pathway in gills of the swimming crab. The findings of the present study further our understanding of adverse effects and underlying mechanisms of long-term ammonia in decapods, and provide valuable information for aquaculture management of P. trituberculatus.

Immune responses to ZnO nanoparticles are modulated by season and environmental temperature in the blue mussels Mytilus edulis

Increased production and release of ZnO nanoparticles (nZnO) can cause toxic effects on marine ecosystems and aquatic organisms. However, nZnO toxicity and its modulation by common environmental stressors such as temperature are not yet fully understood. We examined the responses of immune cells (hemocytes) of the blue mussels (Mytilus edulis) exposed to different concentrations (0, 10, 100 μg l−1) of nZnO or dissolved zinc combined with two temperatures (ambient (10 °C in winter and 15 °C in summer) and warming (+5 °C above ambient temperature)) in winter and summer for 21 days. In winter mussels, exposure to nZnO induced a strong transcriptomic response in multiple immune and inflammation-related genes, stimulated phagocytosis and hemocyte mortality yet suppressed adhesion capacity of hemocytes. In summer mussels, the immune cell responses to nZnO were blunted. The transcriptional responses of hemocytes to dissolved Zn were qualitatively similar but weaker than the responses to nZnO. In the absence of the toxic stress, +5 °C warming lead to dysregulation of the transcription of key immune-related genes in the summer but not the winter mussels. Seasonal warm acclimatization and additional warming in summer suppressed the nZnO-induced transcriptional upregulation of antimicrobial peptides, Toll-like receptors and the complement system. These findings demonstrate that nZnO act as an immunogen in M. edulis and indicate that +5 °C warming might have detrimental effect on innate immunity of the temperate mussel populations in summer when exposure to pathogens is especially high.Capsule: ZnO nanoparticles act as an immunotoxicant inducing a strong immune response in the mussels which is dysregulated by warming in summer but not in winter.

Abstract 2084: Single-cell multimodal glioma analyses reveal epigenetic regulators of cellular plasticity and environmental stress response

Abstract Glioma intratumoral heterogeneity enables adaptation to challenging microenvironments and contributes to universal therapeutic resistance. Here, we integrated 914 single-cell DNA methylomes, 55,284 single-cell transcriptomes, and bulk multi-omic profiles across 11 adult IDH-mutant or IDH-wild-type gliomas to delineate sources of intratumoral heterogeneity. We found that local DNA methylation instability, or epimutation burden, was elevated in more aggressive tumors, reflected intratumoral variability, linked with transcriptional disruption, and associated with environmental stress response. We show that the activation of cell-state specific transcription factors is impacted by epimutations and that loosened epigenetic control may facilitate cellular plasticity. We validated the impact that the common environmental stressor hypoxia has on the epigenetic stability and shifts in cell states through perturbation-based in vitro experiments coupled with single-cell genomics. Our analyses support that glioma cells under stress hijack epigenetic mechanisms that regulate cell state transitions to overcome challenges posed by nutrient-poor microenvironments and therapeutic insults. We confirmed the link between cellular stress and epigenetic instability by analyzing larger cohorts of bulk longitudinally collected and spatially separated DNA methylation data. Increased DNA methylation instability was associated with accelerated disease progression, and recurrently selected DNA methylation changes were enriched for environmental stress response pathways. Our work provides an integrative framework to better understand glioma evolution and highlights the importance of epigenetic heterogeneity in shaping therapeutic response. Citation Format: Kevin C. Johnson, Kevin J. Anderson, Elise T. Courtois, Amit D. Gujar, Floris P. Barthel, Frederick S. Varn, Diane Luo, Martine Seignon, Eunhee Yi, Hoon Kim, Marcos R. Estecio, Ming Tang, Nicholas E. Navin, Rahul Maurya, Chew Yee Ngan, Niels Verburg, Philip C. De Witt Hamer, Ketan Bulsara, Michael L. Samuels, Sunit Das, Paul Robson, Roel G. Verhaak. Single-cell multimodal glioma analyses reveal epigenetic regulators of cellular plasticity and environmental stress response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2084.

Warm perches: a novel approach for reducing cold stress effect on production, plasma hormones, and immunity in laying hens

Cold temperature is a common environmental stressor that induces pathophysiological stress in birds with profound economic losses. Current methods used for preventing cold stress, such as reducing ventilation and using gas heaters, are facing challenges due to poor indoor air quality and deleterious effects on bird and caretaker health. The aim of this study was to examine if the novel designed warmed perch system, as a thermal device, can reduce cold stress-associated adverse effects on laying hens. Seventy-two 32-week-old DeKalb hens were randomly assigned to 36 cages arranged to 3 banks. The banks were assigned to 1 of 3 treatments: cages with warmed perches (WP; perches with circulating water at 30°C), air perches (AP, regular perches only), or no perches (NP) for a 21-d trial. The room temperature was set at 10°C during the entire experimental period. Rectal temperature and body weight were measured from the same bird of each cage at d 1, 8, 15, and 21 during the cold exposure. Egg production was recorded daily. Feed intake, egg and eggshell quality were determined during the 1st and 3rd wk of cold stress. Plasma levels of corticosterone, thyroid hormones (3, 3’, 5-triiodothyronine and thyroxine), interleukin (IL)-6 and IL-10, were determined after 1 d and 21 d of cold exposure. Compared to both AP and NP hens, WP hens were able to maintain their body temperature without increasing feed intake and losing BW. The eggs from WP hens had thicker eggshell during the 3rd wk of cold exposure. Warmed perch hens also had a lower thyroxine conversion rate (3, 3’, 5-triiodothyronine/thyroxine) at d 1, while higher plasma concentrations of IL-6 at d 21. Plasma levels of corticosterone, 3, 3’, 5-triiodothyronine, and IL-10 were not different among treatments. Our results indicate that the warmed perch system can be used as a novel thermal device for preventing cold stress-induced negative effects on hen health and welfare through regulating immunity and metabolic hormonal homeostasis.

Characterizing children hospitalized for suicide-related thoughts and behaviors.

Despite alarming increases in suicide deaths among preadolescent children, knowledge of the precipitants of suicide risk and the characteristics of children who seek treatment for suicidality is limited. This study's purpose is to describe children (ages 6-12) hospitalized for suicide-related concerns and compare demographic and diagnostic differences between children and adolescent (ages 13-18) patients. This retrospective study analyzed medical records of 502 children and adolescents ages 6-18 admitted for suicide-related risk to one psychiatric inpatient hospital in southeastern United States between 2015 and 2018. Patients were predominantly White (63.5%), female (64.5%), and non-Hispanic/Latino (85.1%). We conducted descriptive analyses and a series of logistic regressions comparing children and adolescents with data extracted from discharge summaries, (i.e. primary reasons for admission, environmental stressors, and diagnostic categories). Common environmental stressors included school (63.2%) and family (60.7%), and the most common diagnosis included depressive disorders. Compared to adolescents, children were more likely to be Black (OR=1.99), male (OR=1.94), and receive neurodevelopmental disorder (aOR=3.0) or trauma and stress-related disorder (aOR=2.6) diagnoses, but less likely to be diagnosed with a depressive disorder (aOR=0.4). Across both age-groups, Black patients were more likely to be diagnosed with neurodevelopmental disorders and less likely to receive internalizing disorder diagnoses. Characteristics of children hospitalized for suicide-related risk are relatively similar to characteristics of children dying by suicide. Compared to adolescents, hospitalized children are more likely to be Black, male, and have a neurodevelopmental disorder diagnosis. Proactively identifying and providing strengths-based supports for Black boys and families appear critical for suicide prevention in children.

Modulation of mitochondrial site-specific hydrogen peroxide efflux by exogenous stressors

Oxygen (O2) deprivation and metals are common environmental stressors and their exposure to aquatic organisms can induce oxidative stress by disrupting cellular reactive oxygen species (ROS) homeostasis. Mitochondria are a major source of ROS in the cell wherein a dozen sites located on enzymes of the electron transport system (ETS) and substrate oxidation produce superoxide anion radicals (O2˙‾) or hydrogen peroxide (H2O2). Sites located on ETS enzymes can generate ROS by forward electron transfer (FET) and reverse electron transfer (RET) reactions; however, knowledge of how exogenous stressors modulate site-specific ROS production is limited. We investigated the effects of anoxia-reoxygenation and cadmium (Cd) on H2O2 emission in fish liver mitochondria oxidizing glutamate-malate, succinate or palmitoylcarnitine-malate. We find that anoxia-reoxygenation attenuates H2O2 emission while the effect of Cd depends on the substrate, with monotonic responses for glutamate-malate and palmitoylcarnitine-malate, and a biphasic response for succinate. Anoxia-reoxygenation exerts a substrate-dependent inhibition of mitochondrial respiration which is more severe with palmitoylcarnitine-malate compared with succinate or glutamate-malate. Additionally, specific mitochondrial ROS-emitting sites were sequestered using blockers of electron transfer and the effects of anoxia-reoxygenation and Cd on H2O2 emission were evaluated. Here, we find that site-specific H2O2 emission capacities depend on the substrate and the direction of electron flow. Moreover, anoxia-reoxygenation alters site-specific H2O2 emission rates during succinate and glutamate-malate oxidation whereas Cd imposes monotonic or biphasic H2O2 emission responses depending on the substrate and site. Contrary to our expectation, anoxia-reoxygenation blunts the effect of Cd. These results suggest that the effect of exogenous stressors on mitochondrial oxidant production is governed by their impact on energy conversion reactions and mitochondrial redox poise. Moreover, direct increased ROS production seemingly does not explain the increased adverse effects associated with combined exposure of aquatic organisms to Cd and low dissolved oxygen levels.

Effects of subsurface drip irrigation on alfalfa (Medicago sativa L.) growth and soil microbial community structures in arid and semi-arid areas of northern China

Water shortage is a common environmental stressor encountered by agricultural production in arid and semiarid areas of the world. Under this situation, the impacts of different irrigation methods on the forage yield, select soil physiochemical properties, and soil microbial community structures were identified after alfalfa was planted for three years in Ningxia, northern China. The experiment consisted of five irrigation methods/treatments with three replicates for each treatment, including flood irrigation (FL), sprinkler irrigation (SP), and three subsurface drip irrigation systems, with drip tapes buried at a depth of 10 cm (SSL), 20 cm (SSM) and 30 cm (SSD). The results showed that all water-conserving irrigation methods increased the soil water content compared with FL, but only SSM and SSD presented higher potential in increasing alfalfa yield by improving soil water content, pH value and available P. Moreover, compared with FL, SSM and SSD also presented greater effects in altering microbial community structures, such as the α-diversity, β-diversity, and bacterial composition at the order level, but did not significantly affect microbial taxon composition at the phylum level. Among all determined parameters, alfalfa yield was detected as the strongest factor, which simultaneously associated with the bacterial and fungal community composition, α-diversity, and β-diversity. Moreover, the abundance changes of predicted microbial functional genes revealed that improved alfalfa growth also resulted in more nutrient exhaustion and organic matter depletion in those soils under SSM and SSD treatments. In addition, the changes in bacterial community structure were more sensitive than those in the fungal community structure to soil physicochemical properties and alfalfa growth. In conclusion, the SSM and SSD treatments have great potential to improve alfalfa growth and alter soil microbial community structures in the arid and semiarid areas of northern China.

Effects of polycyclic aromatic hydrocarbons and abiotic stressors on Fundulus grandis cardiac transcriptomics

Following the 2010 Deepwater Horizon oil spill, extensive research has been conducted on the toxicity of oil and polycyclic aromatic hydrocarbons (PAHs) in the aquatic environment. Many studies have identified the toxicological effects of PAHs in estuarine and marine fishes, however, only recently has work begun to identify the combinatorial effect of PAHs and abiotic environmental factors such as hypoxia, salinity, and temperature. This study aims to characterize the combined effects of abiotic stressors and PAH exposure on the cardiac transcriptomes of developing Fundulus grandis larvae. In this study, F. grandis larvae were exposed to varying environmental conditions (dissolved oxygen (DO) 2, 6 ppm; temperature 20, 30 °C; and salinity 3, 30 ppt) as well as to a single concentration of high energy water accommodated fraction (HEWAF) (∑PAHs 15 ppb). Whole larvae were sampled for RNA and transcriptional changes were quantified using RNA-Seq followed by qPCR for a set of target genes. Analysis revealed that exposure to oil and abiotic stressors impacts signaling pathways associated with cardiovascular function. Specifically, combined exposures appear to reduce development of the systemic vasculature as well as strongly impact the cardiac musculature through cardiomyocyte proliferation resulting in inhibited cardiac function and modulated blood pressure maintenance. Results of this study provide a holistic view of impacts of PAHs and common environmental stressors on the cardiac system in early life stage estuarine species. To our knowledge, this study is one of the first to simultaneously manipulate oil exposure with abiotic factors (DO, salinity, temperature) and the first to analyze cardiac transcriptional responses under these co-exposures.

Energy reserves, oxidative stress and development traits of Spodoptera exigua Hübner individuals from cadmium strain

Cadmium as a common environmental stressor may exert highly toxic effects on herbivorous insects. The question was whether possible elevation of an oxidative stress and imbalance of energetic reserves in insects may depend on developmental stage, sex and insect population’s multigenerational history of exposure to cadmium. So, the aim of this study was to compare of the development traits, total antioxidant capacity, lipid peroxidation, RSSR to RSH ratio and the concentration of carbohydrates, glycogen, lipids and proteins in whole individuals (larvae or pupae) of Spodoptera exigua originating from two strains: control and selected over 120 generations with sublethal metal concentration (44 Cd mg per dry weight of diet). Generally, the increase of the protein, carbohydrates, glycogen concentration and lipid peroxidation decrease with age of the larvae were found. Revealed cases of a higher mobilisation of carbohydrates and proteins, and changes in total antioxidant capacity or lipid peroxidation, in individuals being under metal exposure, occurred in strain-depended mode. Short-term Cd exposure effect was connected with possible higher engagement of proteins and glycogen in detoxification processes, but also higher concentration of lipid peroxidation. In turn, for long-term Cd exposure effect lower lipids concentration and higher thiols usage seemed to be more specific.

Anti‐photoaging Activity of Ginseng Seed in UVB‐irradiated Human Skin Fibroblasts

Ultraviolet (UV) radiation from the sun is the most common environmental stressor to damage the skin. Excessive UV radiation usually causes photoaging, inflammation, and even skin carcinogenesis. The seed of Korean ginseng (Panax ginseng C.A. Meyer) contains various phytochemicals including phytosterols, fatty acids, and ginsenosides. Ginseng seed is known to exhibit antioxidant, hepatoprotective, and melanin inhibitory activities. However, not much is known about the anti‐photoaging activities of ginseng seed. The aim of this study was to investigate the protective effect of ginseng seed embryo (GSE) and ginseng seed coat (GSC) on UVB‐induced photoaging in human fibroblasts cell line (Hs68 cells). The contents of total polyphenols and total flavonoids were higher in GSC compared to GSE. Linoleic acid was the major fatty acid in GSE (57.69%) and GSC (39.95%). The content of ginsenoside Rh4 of GSC was about 13 times higher than that of GSE. GSE and GSC significantly attenuated UVB‐induced expression of matrix metalloproteinases (MMPs) and increased the production of collagen in Hs68 cells. Furthermore, UVB‐induced ROS generation was markedly attenuated by pretreatment with GSE and GSC in a dose‐dependent manner, demonstrating that ginseng seed is to be a potent ROS scavenger. These results indicate that ginseng seed protects human skin fibroblasts from UVB‐induced photoaging and therefore has the potential for use in cosmeceutical preparations.

Environmental Stress Increases Synergistic Effects of Pesticide Mixtures on Daphnia magna.

Some widely used pesticide mixtures produce more than additive effects according to conventional combined effect models. However, synergistic effects have been so far generally observed at unrealistically high pesticide concentrations. Here, we used Daphnia magna as a test organism and investigated how food limitation-a common ecological stressor-affects the mixture toxicity of a pyrethroid insecticide and azole fungicide. We also compared three models regarding the prediction of mixture effects, including concentration addition (CA), effect addition (EA), and stress addition model (SAM). We revealed that especially under low food, the strength of synergism between esfenvalerate and prochloraz increased with an increasing concentration of prochloraz independent of the null model. Under high food conditions and at concentrations of prochloraz ≥32 μg/L, we observed a marginal synergistic effect with a model deviation ratio (MDR) = 2.1 at 32 μg/L prochloraz and 2.2 at 100 μg/L prochloraz when using CA as the null model. In contrast, the combination of both pesticides and food stress caused synergistic effects shown by an MDR = 10.9 even at 1 μg/L of prochloraz that is frequently detected in the environment. The combined effects of pesticides and food stress could be predicted best with the SAM that showed the lowest mean deviation between effect observation and prediction (mean deviation SAM = 16 [SD = 28], EA = 1072 [2105], CA = 1345 [2644]). We conclude that common environmental stressors can strongly increase the synergistic effects of toxicants. This knowledge is especially relevant considering current efforts to include the additional risk of pesticide mixtures and environmental stressors into the environmental risk assessment of pesticides.

Nano-TiO2 impairs digestive enzyme activities of marine mussels under ocean acidification

With the development of nanotechnology and increased nanomaterial application, TiO2 nanoparticles have been released into the aquatic environment, causing potential ecotoxicological effects on aquatic organisms. Ocean acidification caused by anthropogenic CO2 is one of the most common environmental stressors, occurring simultaneously with marine contaminants, e.g., nanoparticles. Marine bivalves can accumulate nanoparticles and their digestive functions may be affected. In this study, we investigated the potential influences of TiO2 nanoparticles on the digestive enzyme activities of marine mussels Mytilus coruscus under ocean acidification. Mussels were exposed to combined treatments with three concentrations of nano-TiO2 (0, 2.5, 10 mg/L) and two pH values (8.1, 7.3) for 14 days, and then recovered under ambient condition (pH 8.1 and no nanoparticle) for 7 days. Samples were taken on the 1st, 3rd, 7th, 14th, and 21st day, the digestive enzymes, including amylase, pepsin, trypsin, lipase, and lysozyme, were investigated. Our results showed that nano-TiO2 and low pH had negative effects on amylase, pepsin, trypsin, and lipase, while both of them led an increase in lysozyme activity. Nano-TiO2 showed greater effects on the digestive capacity of M. coruscus rather than low pH. Moreover, a recovery period of 7 days was not sufficient for these enzymes to fully recover.

Integrating miRNA and mRNA expression profiles in plasma of laying hens associated with heat stress.

High temperature is one of the most common environmental stressors plaguing animal husbandry worldwide. Little is known about the regulatory roles of miRNAs in response to heat stress in laying hens. To systematically identify heat stress-responsive miRNAs and their targets in laying hens, the differential expression of miRNAs and mRNAs was compared under heat stress and normal temperature. We identified 16 miRNAs and 502 genes that were significantly changed in heat-stressed laying hens. By comparing the differentially expressed genes (DEGs) and the putative targets of the altered miRNAs based on bioinformatics prediction, 82 coordinated genes were identified. Gene ontology classification analyses of the 82 putative target genes showed that the biological category 'cellular response to stress' was prominently annotated. Notably, the response-related gene autophagy-related protein 9A was most likely controlled by the upregulated miRNAs gga-miR-92-5p, gga-miR-1618-5p, gga-miR-1737, and gga-miR-6557 in response to heat stress. Analysis of DEGs also revealed an increase in lipid metabolism in heat-stressed laying hens. Some of these genes were negatively correlated with the altered miRNAs, suggesting that they are potential targets of the miRNAs. Taken together, our results advance our understanding of the regulatory mechanism of heat-stress-induced injury in laying hens, specifically with regard to miRNAs.

Effects of dietary antioxidants and environmental stressors on immune function and condition in Lithobates (Rana) sylvaticus

The negative effects of abiotic and biotic stressors on animal condition, physiology, behaviour, and fitness have become increasingly recognized, making it critical to understand how these may be mitigated, such as through diet. When consumed, dietary antioxidants (secondary metabolites produced by plants) provide protection from oxidative damage that can result from exposure to stressors. We examined the effects of dietary antioxidants (β-carotene and vitamin E) on the ability of Lithobates sylvaticus (wood frog) tadpoles to overcome the detrimental effects imposed by two common environmental stressors – exposure to the herbicide atrazine or infection by a pathogenic helminth parasite (Echinostoma trivolvis). Tadpoles which were fed high concentrations of either vitamin E or β-carotene had a greater immune response compared to those given trace diets of either compound as measured by circulating white blood cells and a phytohemaglutination assay (PHA). Similarly, tadpoles in the herbicide and parasitism treatments that were given trace antioxidant diets had significant weight loss, whereas those consuming high levels of vitamin E or β-carotene did not. Our results suggest that dietary antioxidants, specifically β-carotene and vitamin E, have a positive effect on tadpole immune systems and overall condition that likely allows them to better cope with natural stressors, with potential implications for their foraging behaviour.

The effect of moisture on soil microbial properties and nitrogen cyclers in Mediterranean sweet orange orchards under organic and inorganic fertilization

Water shortage and soil degradation are common environmental stressors encountered in the Mediterranean area. We evaluated how different soil moisture levels, dependent on distance from drip irrigation points, impact on the biological, chemical and physical properties of citrus soil under organic and inorganic fertilization. We measured soil physicochemical properties, basal soil respiration, soil microbial biomass carbon, soil microbial community structure (phospholipid fatty acid assay), bacterial load (16S rRNA gene abundance), enzymatic activities (urease, dehydrogenase, β-glucosidase and acid phosphatase) and abundance of microbial nitrogen cyclers (quantitative PCR). A field experiment was established in an orange orchard (Citrus sinensis) in southeast Spain and eighteen soil samples were taken from each plot to compare the impacts of soil moisture: near (wet, w) or away (dry, d) from drip-irrigation points, in plots with inorganic fertilizers under intensive ploughing (PI) or organic fertilization (OA). The results showed that changes in microbial properties and soil microbial indexes were strongly associated with soil moisture content under both organic and inorganic fertilization, and with organic carbon content. Soil moisture influenced soil aggregation, basal soil respiration, phosphatase activity, bacterial and fungal load (PLFAs) and the abundances of bacterial N cycling genes, including nifH (nitrogen fixation) nirS/K and nosZ genes (denitrification) and amoA-B (bacterial nitrification). The potential for N fixation and denitrification, two microbial processes that are crucial for determining the amount of N in the soil, were improved by increased soil moisture in the proximity of the drip irrigation. Soil OC and total N, which are higher under organic fertilization than under inorganic fertilization, were also shown to be highly correlated with the abundance of the N cycling genes. By controlling irrigation doses and applying organic amendments, it may be possible to increase the microbial abundance and function in soil and support greater fertility of soils.