Important Environmental Stressor Research Articles

Antagonist Effects of Sodium Chloride on the Biological Responses of an Aquatic Plant (Ceratophyllum demersum L.) Exposed to Hexavalent Chromium

In this study, the concentration-dependent joint action of chromium (Cr) and salt (NaCl), two important environmental stressors, was examined in aquatic plants. Ceratophyllum demersum L. plants were exposed to Cr (0–10 mM) for 5 days in the presence and absence of NaCl (0–500 mM). The effect of Cr, Na, and Cl accumulations on certain biological parameters (water content, ion leakage, relative growth rate, photosynthetic pigments, and protein and proline contents) was determined. Furthermore, the interactive effects of NaCl and Cr were evaluated using a mathematical model developed on the basis of the theory of probabilities. The highest Cr accumulation (0.42 mmol g−1) was found in plants treated with 10 mM Cr + 125 mM NaCl. Treatment with 125 mM NaCl resulted in an increase in Cr accumulation compared with that in the control. However, 250 and 500 mM NaCl concentrations decreased Cr accumulation. Proline and water contents were not affected by increasing Cr concentration. However, NaCl did have a significant effect on any of the studied parameters. Furthermore, the interactive effects of Cr and NaCl on all studied parameters except for proline and water contents were determined. Except for photosynthetic pigments and proline content, effect of NaCl was higher than Cr on all studied parameters. The interactive effects were mostly antagonistic or additive. However, the mode of action for ion leakage was synergistic or additive. These results suggest that the coexistence of NaCl and Cr in aquatic ecosystems does not pose an additional ecological risk for aquatic plants.

Quantification of health impacts from food crop consumption in Europe

Background. Food crop consumption is the predominant exposure pathway of the general public toward pesticides. Until now, health impacts of overall human exposure to pesticides used for specific crops have never been quantified. Aims. We aimed at quantifying the human health impacts of pesticides, detailing how pesticides contributed annual impacts to the value of an average burden of lifetime lost per person across Europe in 2003. Methods. We investigated human exposure to 133 pesticides applied in 24 European countries in 2003. We looked at the five most extensively used pesticides per crop using a combination of a dynamic multi-crop uptake model and a steady-state fate and exposure assessment tool, to characterize how pesticides affected the general population. From the results, we created a table of health impacts per kilogram of applied pesticide. Results. Overall, pesticides contributed annually to around 2000 disability-adjusted life years in Europe, to which only 13 substances applied to grapes/vines, fruit trees, and vegetables accounted for 90% of total annual health impacts. The burden per person in hours lost over lifetime was 2.6. Compared with figures for the burden from particulate matter in the air (195 days) or passive smoking (24 days), this figure is relatively low. However, uncertainties in our results highlight the figure could be somewhat higher, ranking pesticides with other important environmental stressors in health impact terms. On a positive note, 33 of the 133 assessed substances (which accounted for 20% of health impacts) are now banned in Europe. Conclusions. Our research has important policy implications, as the first attempt to quantify the extent of pesticides’ health impacts in Europe at the level of individual pesticides, crop classes and country. However, some uncertainty will always remain, due to the fact that pesticides cannot ethically be tested on humans to find out their health effects directly.

Molecular characterization and expression analysis of PPP1R3C in hypoxia-tolerant Indian catfish, Clarias batrachus (Linnaeus, 1758) under hypoxia

Hypoxia is an important environmental stressor that leads to rapid adaptive changes in metabolic organization. However, the molecular mechanisms of hypoxia tolerance in fish remain largely unknown. The present work was focused on understanding the molecular mechanisms and signaling pathways that may lead to tolerance of Clarias batrachus to hypoxic stress. Protein phosphatase 1 regulatory subunit 3C (PPP1R3C) is a new hypoxia-inducible factor (HIF) targeted gene and is regulated by HIF-1 under hypoxic conditions. Overexpression of PPP1R3C increases glycogen accumulation through activation of several enzymes and processes. In this study, for the first time, full length cDNA of PPP1R3C from C. batrachus was characterized and its expression pattern in the brain, liver, muscle and spleen under short (progressive hypoxia; PH, 1h, 6h and 12h) and long-term (natural) hypoxic conditions was investigated. The complete cDNA of PPP1R3C was of 1499bp, encoding 285 amino acid residues. The identified protein had a protein phosphatase 1 binding motif and a carbohydrate binding domain, thought to be involved in the regulation of glycogen metabolism. Short-term hypoxia exposure caused significant increase in PPP1R3C transcripts in the liver (6h; 6.96 fold and 12h; 3.91 fold) and muscle (progressive hypoxia; 3.46 fold), while, after long-term hypoxia exposure, significant up-regulation in the liver (7.77 fold) and spleen (6.59 fold) tissues was observed. No significant differences were observed in the brain for any time periods. Thus PPP1R3C may play an important role in the tolerance of C. batrachus to hypoxia.

A framework for understanding noise impacts on wildlife: an urgent conservation priority

Anthropogenic noise is an important environmental stressor that is rapidly gaining attention among biologists, resource managers, and policy makers. Here we review a substantial literature detailing the impacts of noise on wildlife and provide a conceptual framework to guide future research. We discuss how several likely impacts of noise exposure have yet to be rigorously studied and outline how behavioral responses to noise are linked to the nature of the noise stimulus. Chronic and frequent noise interferes with animals' abilities to detect important sounds, whereas intermittent and unpredictable noise is often perceived as a threat. Importantly, these effects can lead to fitness costs, either directly or indirectly. Future research should consider the range of behavioral and physiological responses to this burgeoning pollutant and pair measured responses with metrics that appropriately characterize noise stimuli. This will provide a greater understanding of the mechanisms that govern wildlife responses to noise and help in identifying practical noise limits to inform policy and regulation.

Impact of Heat Stress on Poultry Production.

Simple SummaryDue to the common occurrence of environmental stressors worldwide, many studies have investigated the detrimental effects of heat stress on poultry production. It has been shown that heat stress negatively affects the welfare and productivity of broilers and laying hens. However, further research is still needed to improve the knowledge of basic mechanisms associated to the negative effects of heat stress in poultry, as well as to develop effective interventions.Understanding and controlling environmental conditions is crucial to successful poultry production and welfare. Heat stress is one of the most important environmental stressors challenging poultry production worldwide. The detrimental effects of heat stress on broilers and laying hens range from reduced growth and egg production to decreased poultry and egg quality and safety. Moreover, the negative impact of heat stress on poultry welfare has recently attracted increasing public awareness and concern. Much information has been published on the effects of heat stress on productivity and immune response in poultry. However, our knowledge of basic mechanisms associated to the reported effects, as well as related to poultry behavior and welfare under heat stress conditions is in fact scarce. Intervention strategies to deal with heat stress conditions have been the focus of many published studies. Nevertheless, effectiveness of most of the interventions has been variable or inconsistent. This review focuses on the scientific evidence available on the importance and impact of heat stress in poultry production, with emphasis on broilers and laying hens.

Albatross as Sentinels of Heavy Metal Pollution: Local and Global Factors

Heavy metal pollution in the Pacific Ocean has garnered significant attention in recent years, especially with regard to rising mercury emissions from Asia. Uncertainty exists over the extent to which mercury in biota may have resulted from increases in anthropogenic emissions over time. Albatrosses, including those inhabiting the North Pacific, are wide-ranging, long-lived, keystone, avian predators. Consequently, they serve as ideal sentinel species for investigating the effects of historical and contemporary pollution as well as local and global factors related to heavy metal exposure, bioaccumulation, and ecotoxicological risk. To date, high levels of mercury and lead have been documented in albatross species throughout the Pacific. To address biotic exposure to these multiple stressors, here we synthesize and conduct meta-analyses of total mercury, methylmercury, and lead exposure data in Black-footed albatross (Phoebastria nigripes) and Laysan albatross (Phoebastria immutabilis). Our approach includes data from the field and literature, and for total mercury and methyl mercury, we use measurements from museum feathers spanning the past 130 years for Black-Footed albatross. We discuss the use and application of stable isotopes (δ15N and δ13C) as a way to control for temporal changes in trophic structure and diet and we demonstrate the importance of conducting speciation analyses for mercury to account for historical, curator-mediated, inorganic mercury contamination of specimens. Our data showed higher levels of inorganic mercury in older specimens of Black-Footed albatross as well as two non-pelagic species (control samples) lacking historical sources of bioavailable mercury exposure, which suggests that studies on bioaccumulation should measure methylmercury rather than total mercury when utilizing museum collections. Changes in methylmercury levels in Black-Footed albatross were consistent with historical global and recent regional increases observed among published estimates and proxies of anthropogenic mercury emissions. At the local scale, previous research has also reported that lead paint exposure from buildings was also an important environmental stressor for Laysan albatross. Thus, albatross species face heavy metal exposure threats at both local (lead) and global scales (mercury, and potentially heavy metals in plastics). Specific types of plastic pollution entering marine environments have been documented to contain heavy metals at levels, which if bio-available, may present a non-localized source of lead exposure in albatross species known to ingest (and regurgitate to their young) large amounts of marine plastic. Heavy metal toxicity along with other stressors may undermine current and future reproductive outcomes in these seabird species, although unraveling effects from specific metals in the context of a complex metal mixture presents some challenges. Collectively, our findings and review of the literature suggest that albatrosses in this region may be an effective marine flagship species and raising the profile of these organisms likely would successfully support broader biodiversity conservation efforts in the North Pacific.

Noise impact in a residential development in Zapopan Jalisco, Mexico.

Altagracia is a residential development in Zapopan Jalisco. Here noise due to stationary and mobile sources is an important environmental stressor, since the settlement is close to industry complexes and the major periphery road of the metropolis. As a way of getting knowledge about what noise sources contribute the most to the noise impact within the development, a noise environmental assessment was performed. 14 samples were taken to evaluate the contribution of mobile and stationary sources. Sampling sites were established as a result of a pilot experiment at which the highest noise levels were recorded. Data processing and analysis were performed taking into account national standards for stationary sources (NOM 081-ECOL-94), and mean values for the mobile sources, since there is not specific regulation for them. Results of the study, highlights mobile sources as the major contributor of noise impact within the residential area.

Effects of Traffic Noise on Sleep in an Urban Population

Urban noise is an important environmental stressor, and sleep disturbance is its major health effect. Substantial inter-individual variance in these effects might partly be explained by different sensitivity to noise. The aim of this study was to assess the effects of urban noise on sleep and the relation between self-estimated sensitivity to noise and sleep disturbance. A cross-sectional questionnaire survey was performed on 911 adult residents of Nis, Serbia, of whom 388 were men (42.6 %) and 523 women (57.4 %). The streets were regarded as noisy if night equivalent noise level (Leq) was higher than 45 dB(A) and quiet if night Leq was < or =45 dB(A). Noise sensitivity was measured with the Weinstein's Noise Sensitivity Scale. The study showed that respondents from noisy area significantly more often reported difficulty in falling asleep, being woken up, poor sleep quality, tiredness after sleep, and use of sleep medication than residents from quiet streets (p<0.001). Noise sensitivity significantly correlated with sleep disturbances (p<0.001).

Sublethal stress: Impact of solar UV radiation on protein synthesis in the copepod Acartia tonsa

Aquatic organisms respond to environmental challenges such as thermal stress with the rapid induction of highly conserved polypeptides known as stress proteins or heat shock proteins (Hsps). Solar ultraviolet radiation (UVR, 280–400 nm) is an important environmental stressor in marine ecosystems. Here, we present results of experiments conducted with the marine copepod Acartia tonsa to follow the de novo protein synthesis and measure the level of constitutive and inducible isoforms of the Hsp70 gene family of stress proteins after UV exposure. Animals were collected from Tampa Bay, Florida (USA), and exposed to solar radiation (full spectrum), UV-A (320–400 nm) and PAR (400–700 nm), or PAR only, for periods of 0.5–4 h. Controls were kept in the dark. Protein synthesis was robust under all treatments when the copepods were exposed to low solar radiation intensities. Conversely, high solar radiation intensities (both UV-B and UV-A) caused an overall suppression in the protein synthesis of the copepods with no detectable induction of stress-inducible isoforms of Hsps. Immunochemical assays (western blotting) showed that UVR increased levels (3.5–4-fold increase compared to the dark control) of the constitutively expressed 70 kDa heat-shock (Hsc70) protein in A. tonsa, without indication of inducible isoform upregulation.

Baseline values for acute and chronic stress indicators in sexually immature red porgy ( Pagrus pagrus)

The aim of the present study was to develop, evaluate and set up baseline values for reliable acute and chronic stress indicators in sexually immature red porgy, Pagrus pagrus. The effects of anaesthesia, acute (chasing for 10 min followed by air exposure for 3–4 min) and chronic (different stocking densities: 5 vs. 25 kg m − 3 and water temperatures: 15 °C, 19 °C, 25 °C) stressors on stress indicators were studied. Cortisol, lactate, norepinephrine, epinephrine, glucose, electrolytes, and prothrombin time were found to be reliable indicators of acute stress, whereas lactate and catecholamines were found to be reliable indicators of chronic stress. Baseline values were: glucose, 2.05–5.17 mmol l − 1 ; lactate, 0.15–1.5 mmol l − 1 ; cortisol, 0.8–24.9 ng ml − 1 ; potassium, 1.5–4.5 mmol l − 1 ; sodium, 167–206 mmol l − 1 ; chloride, 165–180 mmol l − 1 ; and prothrombin time, 9.26–14.65 s. Plasma epinephrine and norepinephrine concentrations after minimum handling were 2.4–43.2 nM and 9.6–74.5 nM, respectively. The present study also revealed that stocking density expressed in kg m − 3 is not an appropriate measure to describe and compare the physiological status of fish under intensive culture conditions. Results suggested that when group and tank sizes are reduced, even at a low stocking density (5 kg m − 3 ), the maintenance cost is higher than the one at high stocking density (25 kg m − 3 ). In addition, low (15 °C) and high (25 °C) water temperatures were important environmental stressors for Pagrus pagrus, as shown by the observed elevated (mean ± SEM) norepinephrine (15 °C: 110.8 ± 17.6 nM, 19 °C: 84.0 ± 6.0 nM, 25 °C: 160.8 ± 24.6 nM) plasma concentrations.

Temperature-dependent effects of cadmium and purine nucleotides on mitochondrial aconitase from a marine ectotherm,Crassostrea virginica: a role of temperature in oxidative stress and allosteric enzyme regulation

Temperature and heavy metals such as cadmium (Cd) are important environmental stressors that can strongly affect mitochondrial function of marine poikilotherms. In this study, we investigated the combined effects of temperature (20 degrees C and 30 degrees C) and Cd stress on production of reactive oxygen species (ROS) and oxidative stress in a marine poikilotherm Crassostrea virginica (the eastern oyster) using mitochondrial aconitase as a sensitive biomarker of oxidative damage. We also assessed potential involvement of mitochondrial uncoupling proteins (UCPs) in antioxidant protection in oyster mitochondria using purine nucleotides (GDP, ATP and ADP) as specific inhibitors, and free fatty acids as stimulators, of UCPs. Our results show that exposure to Cd results in elevated ROS production and oxidative damage as indicated by aconitase inactivation which is particularly pronounced at elevated temperature. Unexpectedly, oyster mitochondrial aconitase was inhibited by physiologically relevant levels of ATP (IC(50)=1.93 and 3.04 mmol l(-1) at 20 degrees C and 30 degrees C, respectively), suggesting that allosteric regulation of aconitase by this nucleotide may be involved in regulation of the tricarboxylic acid flux in oysters. Aconitase was less sensitive to ATP inhibition at 30 degrees C than at 20 degrees C, consistent with the elevated metabolic flux at higher temperatures. ADP and GDP also inhibited mitochondrial aconitase but at the levels well above the physiological concentrations of these nucleotides (6-11 mmol l(-1)). Our study shows expression of at least three UCP isoforms in C. virginica gill tissues but provides no indication that UCPs protect mitochondrial aconitase from oxidative inactivation in oysters. Overall, the results of this study indicate that temperature stress exaggerates toxicity of Cd leading to elevated oxidative stress in mitochondria, which may have important implications for survival of poikilotherms in polluted environments during seasonal warming and/or global climate change, and suggest a novel temperature-dependent mechanism of allosteric regulation of TCA flux in oyster mitochondria.

Environmental stress and 3-day eventing: effects of altitude.

Three-day event horses are subject to various external environmental stresses including changes in ambient temperature, humidity, altitude, and test severity. Considerable research on the adverse effects of increased heat and humidity preceded the 1996 Olympic Summer Games in Atlanta, Georgia USA, but no research has been done previously on the effects of altitude on 3-day eventing. Physical and venous blood gas data were collected on horses (n = 24) competing in the High Prairie Preliminary (CCN*) and Intermediate (CCN**) 3-day events and Preliminary Horse Trials in Parker, Colorado (1900 m above sea level). Despite the increased altitude, only post exercise rectal temperature and pH were higher (P < 0.05) whereas heart rate (HR), [K+], and ionized calcium (ICa++) were lower (P < 0.05) in 3-day event horses compared to horse trial horses. All other variables (respiratory rate [RR], PCV, [Hb], PCO2, [tCO2], [HCO3-], BE, and [Na+]) were not different between groups (P > 0.05). When these preliminary horse trial horses in Colorado were compared to those previously studied at preliminary horse trials at sea level in Arizona, post exercise HR and RR were higher (P < 0.05) and pH, PCO2, [tCO2], [HCO3-], BE and [iCa++] were lower (P < 0.05) at altitude. These data show that increased altitude (1900 m above sea level) was more stressful for 3-day event horses, but did not result in the severe physiological changes and inability to complete prescribed exercise tests seen in previous studies with increased heat and humidity. It is clear from these and previous data that increased heat and humidity are the more important environmental stressors in 3-day eventing.

Antler asymmetry and immunity in reindeer

Fluctuating asymmetry (FA) measures an individual's ability to undergo identical development in bilaterally symmetrical characters and may indicate sensitivity to environmental stress. FA in ornamental characters is often positively related to parasite intensities, which are important environmental stressors. Parasites affect and are affected by several parts of the immune system, and the ability to resist parasites may be signalled via FA in ornaments. In this study we examined reindeer antlers, which show FA, demonstrated to be caused by parasite infections. We measured antler FA, immune parameters (i.e. densities of different classes of leukocytes, IgG levels and abomasal lymph node numbers) and intensity of abomasal nematodes in free-ranging 1.5-year-old male reindeer slaughtered in the early part of their rutting period. We found a relationship between parasite intensity and immune parameters suggesting that our measures of immune activity reflect density of current parasite infections. More important, these immune parameters were associated with FA in both the main beam length and numbers of antler tines. The immune parameters were, however, only weakly correlated to antler size. This indicates that FA, but not size, of antlers grown during exposure to a multitude of environmental stressors may reveal information about individual immunity that can be important for host-parasite interactions. Antler FA may therefore communicate an individual's quality during the rut in reindeer.

The structure of organizational stress and mental health

In the studies of organizational stress conducted in the U. S. and western Europian countries, human relations at work place has been treated as one of the important environmental stressors. In Japanese work organizations, however, human relations should be regarded as a factor which moderates (buffers) the negative effects of organizational stress. That is why, Japanese workers seem to cope with stress effectively on the basis of good relationships at work. The present study was designed to examine the stress buffering effects of human relations in organizational stress-mental health relationships. Survey data obtained from 334 Japanese white-collar workers of a large supermarket chain and a bank were analyzed by using the moderated multiple regression technique and the subgroup method. The results suggested the buffering effects of human relations in organizational stress (workload, role ambiguity, and role conflict)-mental health (somatization, anxiety, and particularly depression) relationship. Arguments were advanced for the future application of the present findings to the social support study in work settings.