Genetic ecotoxicology: an overview

The techniques currently available for detecting genotoxin exposure are briefly described and evaluated with regard to the goals of genetic ecotoxicology. The occurrence and significance of genotoxin-induced neoplasia in marine organisms is described. Although there are numerous examples of hotspots where tumour incidences in fish and shellfish have been correlated with raised concentrations of anthropogenic chemicals, causal mechanisms are seldom established. Insufficient information is available to gauge the seriousness of genotoxicity for marine organisms on regional or global scales. The possibility of using marine organisms as sentinels to provide early warning of potential threats to Man is examined. Recognition of the genotoxic disease syndrome in lower animals highlights the need to explore the relationships between DNA damage (adduct formation, gene mutations, etc.) and its phenotypic consequences. Within a given population, not all individuals are equally susceptible to pollutant toxicity (including genotoxicity). The potential for using similarities in phenotypic traits to recognise subsets of individuals within populations possessing similar genotypes is discussed. Changes in heterozygosity and the evolution of genetically resistant populations following exposure to pollution are evaluated in the context of genetic ecotoxicology. Risk assessment procedures are required which enable genotoxin exposure to be related to specific consequences at the community and ecosystem levels. This necessitates both a sound scientific understanding of the mechanisms involved and the development of pragmatic ecotoxicological tools that can be employed by environmental managers.     

Helminths and protozoans of aquatic organisms as bioindicators of chemical pollution

There is no doubt that the aquatic environments receive large quantities of chemicals as consequence of human activities and that those substances have a detrimental effect on human health. Despite the obvious need for effective disposal of these substances, we need to understand and prevent the outcome of harmful environmental exposures. Thus, we need biomarkers and bioindicators to advance our understanding to these harmful exposures and their biological effects. In the last three decades a large number of publications has suggested that aquatic organisms and their parasites (mainly helminths and ciliate protozoans) are useful bioindicators of chemical pollution. However, the main weakness of this approach is that after exposure the population size of these parasites can increase or decrease without a consistent pattern. I suggest that this is in part due to the lack of focus on the correct spatial or temporal scales at which the environment is acting over our study object. Thus, I propose to use spatially explicit (= georeferenced) data for determining whether there is spatial structure in our study area. Spatial structure is the tendency of nearby samples to have attribute values more similar than those farther apart. These attributes are shaped by environmental variables acting at specific spatial and temporal scales. Thus, I suggest to consider these tools for determining the correct spatial or temporal scales of study, but also to record pollutant concentrations, bioindicators, biomarkers and parasites at individual host level. Combining this information with long-term monitoring programs is likely to improve our understanding of the effects of chemical pollutants over the aquatic environments.     

Managing riparian zones for river health improvement: an integrated approach

Riparian zones are among the most valuable ecosystems on the earth. They act as the ecological engineers that improve river health through delivering a range of ecosystem functions. Stream bank stabilization, pollutant and sediment buffering, temperature regulation, provision of energy to river food webs and communities, groundwater recharge and provision of ecological corridors and habitat for wildlife, are among major ecosystem functions of riparian zones that play a great role in river health. Besides these ecosystem functions, riparian zones also provide various ecosystem goods and services for human well-being. But in the current scenario, riparian zones are under severe threat due to agricultural activities, urbanization, river flow alteration, overexploitation, climate change, pollution, and biological invasion. In the present and probable future scenarios of declining river health and global environmental changes, there is a pressing need of an integrated approach for managing riparian zones. This review article aims to advocate an integrated approach for riparian zone management based on various components such as riparian condition assessment, policy framework, stakeholder’s participation, management practices, legislation, and awareness. Authors also discussed riparian zones in context of their concepts, features, functions, and threats.

     

环状RNA及其在生态毒理学研究中的应用进展

环状RNA（circular RNAs,circRNAs）是一类共价闭合环状非编码RNA,具有进化上保守、结构上稳定、组织特异性表达等特点。CircRNAs可作为miRNAs海绵影响其对基因的调控,还可与RNA结合蛋白（RNA binding proteins,RBPs）相互作用,也有研究表明某些circRNAs还具有被翻译成蛋白质的潜能。CircRNAs已被证实对某些疾病具有特异性、稳定性和调节功能,如癌症、糖尿病、心血管疾病、神经退行性疾病等,其可作为潜在的诊断、预后生物标志物和治疗靶点。最近,有研究发现circRNAs参与了环境化学污染物诱导的毒性效应发生及发展的过程。目前,生态毒理学研究中评价环境化学污染物和毒效应之间关系的毒性终点通常会受遗传多态性和表观遗传学影响,考虑到经环境化学污染物暴露后生物体内circRNAs差异性表达的现象,或许在生态毒理学研究中circRNAs也有作为生物标志物的可能性。基于此,对circRNAs的生物合成与降解、生物学功能、分析方法及其目前在生态毒理学研究中的应用展开综述,并对其作为分子生物标志物在环境污染物暴露早期诊断和生态风险评价中的应用进行了展望,以期为生态毒理学研究和环境风险评价提供参考。     

A New Online Database on Chemicals in Accordance with REACH Regulation

The need for comprehensive and reliable risk management of chemicals requires appropriate information, data integration, and sharing, as suggested in Europe by Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation. REACH requires more sharing of responsibilities among authorities, chemical manufacturers, importers, and users to manage the risks that chemicals can pose to human health and the environment throughout their life cycle. This has obviously enlarged the audience of people who could be interested in gathering this information. A major bottleneck is that information sources on chemicals are frequently sparsely distributed, collected, and managed by different institutions, with different aims, resulting in several practical problems. This article describes the conceptual design and implementation of a free online access database (DESC) as an integrated information system on chemical substances in compliance with the REACH regulation. An interdisciplinary approach was applied by involving several experts from different disciplines (ecotoxicologists, chemists, information technology specialists, regulators). DESC contains relevant environmental and toxicological data (physico-chemical and ecotoxicological data, inclusion in priority lists, current classification and labeling, etc.) on more than 651 chemicals, which can be easily consulted by people with different degrees of expertise interested in knowing the risk from exposure to chemicals and their safe use.     

Mutagen sensitivity assays in population studies

Human population monitoring studies are frequently conducted to determine if exposure to environmental mutagenic agents can cause health problems or not. In these studies, a variety of biomarkers are used to identify biological events that are predictive of health consequences. An emphasis in this report is on the use of mutagen sensitivity assays to understand health risk. The assay is based on the assumption that exposure to mutagenic chemicals or mixtures of chemicals for a long time can cause cellular changes that are expressed as mutagen sensitivity. From experience in using these assays in cancer patients and in mutagen-exposed populations, it is clear that the expression of mutagen sensitivity is based on the interactions between mutagen exposure and individual susceptibility. When studies are conducted under appropriate conditions, expression of mutagen sensitivity is suggestive of increased risk for environmental disease such as cancer.     

Molecular cloning and characterization of Cpn60 in the free-living nematode Plectus acuminatus

Heat shock proteins (Hsps) have provoked interest not only because of their involvement in human diseases but also for their potential as biomarkers of environmental pollution. Whereas the former interest is covered by numerous reports, the latter is an exciting new field of research. We report the isolation of the full-length cpn60 messenger ribonucleic acid (mRNA) and partial genomic deoxyribonucleic acid from the free-living, environmental sentinel nematode Plectus acuminatus, a species used in classical ecotoxicity tests. Although the primary sequence displays high identity scores to other nematodes and human Cpn60 (75% and 70%, respectively), the intron-exon structure differs markedly. Furthermore, although mRNA levels remained constant after exposure to ZnCl2 (0-330 microM) under laboratory conditions, protein levels increased significantly in a dose-dependent manner. In conclusion, this first account of molecular genetic similarities and differences of Cpn60 in a neglected nematode taxon provides a valuable insight into its potential uses in gene-based ecotoxicological risk assessment exercises.     

The sensitivity of Afromontane tarns in the Maloti-Drakensberg region of South Africa and Lesotho to acidic deposition

Despite their remoteness from sources of atmospheric pollutant emissions, the Afromontane tarns in the Maloti-Drakensberg region are perfect candidates to study the negative effects of acidifying atmospheric pollution, because mountain lakes are widely recognised as sentinel ecosystems, unimpacted by direct human disturbance within their catchments. Thirty-four tarns were sampled in the Maloti-Drakensberg region and most were found to be extremely sensitive to acidic deposition, as indicated by their low acid neutralising capacity. There are very few studies of freshwater critical loads for any region within South Africa. The steady-state water chemistry model (SSWC) was adapted and used to determine critical loads, whereas exceedance was estimated relative to modelled regional deposition data, in order to understand the risk of harmful effects to aquatic ecosystems. Seventy-six percent of sampled sites across the Maloti-Drakensberg would exceed critical loads even at the lowest modelled deposition levels, but there are no current measured deposition data for the region. The sensitivity of the Maloti-Drakensberg tarns needs to be considered in future policy formulation regarding acceptable levels of acidifying atmospheric pollution from South Africa’s energy sector and indicates the need for assessing aquatic ecosystem impacts in other regions of South Africa.     

Manatees as Sentinels of Marine Ecosystem Health: Are They the 2000-pound Canaries?

The order Sirenia is represented by three species of manatees and one species of dugong distributed in tropical and subtropical regions of the world and considered vulnerable to extinction. The sentinel species concept is useful to identify indicators of the environment and may reflect the quality of health in marine ecosystems. The single species approach to evaluate ecological health may provide a series of snap shots of environmental changes to determine if animal, human, or ecosystem health may be affected. Under this concept, marine vertebrates may be good integrators of changes over space and time, and excellent sentinels of ecosystem health. Based on their life history, manatees may or may not be ideal sentinels, as they are robust, long-lived species and appear remarkably resilient to natural disease and the effects of human-related injury and trauma. These characteristics might be the result of an efficient and responsive immune system compared to other marine mammals. Although relatively immune to infectious agents, manatees face other potentially serious threats, including epizootic diseases and pollution while in large aggregations. Manatees can serve as excellent sentinels of harmful algal blooms due to their high sensitivity, specifically to brevetoxicosis, which has caused at least two major die-offs in recent times. Threats to manatees worldwide, such as illegal hunting and boat collisions, are increasing. Habitat is being lost at an alarming rate and the full effects of uncontrolled human population growth on the species are unknown. The manatee may serve as a sentinel species, prognosticating the deleterious effects of unhealthy marine and aquatic ecosystems on humans. We have identified a number of critical research needs and opportunities for transdisciplinary collaboration that could help advance the use of the sentinel species concept in marine ecosystem health and monitoring of disease emergence using our knowledge on these magnificent sirenians.     

Oxidative stress biomarkers indicate sublethal health effects in a sentinel small mammal species,the deer mouse (Peromyscus maniculatus), on reclaimed oil sands areas

Oxidative stress biomarkers can provide highly relevant insights into the physiological state of an organism. We compared endogenous oxidative stress biomarkers (lipid peroxidation and glutathione redox status) in the liver and testes as well as the hepatic antioxidant vitamins A and E in deer mice (Peromyscus maniculatus) collected from a reclaimed mine site on the Athabasca Oil Sands Region (northern Alberta, Canada), with those from a non-industrial reference site within the same natural macroregion. Both glutathione redox and vitamin A status in the liver as well as glutathione redox status in the testes were disrupted in mice from the reclaimed site, indicating oxidative stress in these organs. Increased oxidative stress in the liver was associated with greater exposure to Co, Se, and Tl and contributed to poorer body condition and lowered testis size in animals from the reclaimed site (data from companion study). These results confirm health effects and biological costs in this native, sentinel small mammal from exposure to pollutants at the reclaimed mine site. This work provides compelling information and insight into the value of oxidative stress biomarkers as physiological tools that can indicate the health status and fitness of local wild animals. In particular, this approach can be used by risk assessors and other stakeholders from the oil sands region in future environmental risk assessments to improve wildlife management and conservation practices.     

污染胁迫下的蚯蚓蛋白质组学研究进展

随着蛋白质组学的发展和每年有大量环境污染物进入土壤环境中,污染胁迫模式动物的相关生物标志物受到日益关注。蚯蚓,作为土壤中最大的无脊椎动物,是研究和评价土壤生态污染良好的模式动物。研究蚯蚓的蛋白质组学,对于寻找环境生态污染相关生物标志物和阐明生态毒理学机制有着十分重要的现实意义。目前已知的污染胁迫下蚯蚓蛋白质组学研究,提供了几个特定污染物胁迫蚯蚓的蛋白表达谱。这些蛋白涉及许多生物学过程,例如信号传导、糖酵解、能量代谢、分子伴侣和转录调节,提示了相关污染物可能的生态毒理学机制,有望成为潜在的生物标志物,用于有毒污染物的监测,但其特异性需要进一步试验的验证。对蚯蚓受污染胁迫的蛋白质组表达谱及潜在生物标志物进行简要综述。     

Simulating Microdosimetry in a Virtual Hepatic Lobule

The liver plays a key role in removing harmful chemicals from the body and is therefore often the first tissue to suffer potentially adverse consequences. To protect public health it is necessary to quantitatively estimate the risk of long-term low dose exposure to environmental pollutants. Animal testing is the primary tool for extrapolating human risk but it is fraught with uncertainty, necessitating novel alternative approaches. Our goal is to integrate in vitro liver experiments with agent-based cellular models to simulate a spatially extended hepatic lobule. Here we describe a graphical model of the sinusoidal network that efficiently simulates portal to centrilobular mass transfer in the hepatic lobule. We analyzed the effects of vascular topology and metabolism on the cell-level distribution following oral exposure to chemicals. The spatial distribution of metabolically inactive chemicals was similar across different vascular networks and a baseline well-mixed compartment. When chemicals were rapidly metabolized, concentration heterogeneity of the parent compound increased across the vascular network. As a result, our spatially extended lobule generated greater variability in dose-dependent cellular responses, in this case apoptosis, than were observed in the classical well-mixed liver or in a parallel tubes model. The mass-balanced graphical approach to modeling the hepatic lobule is computationally efficient for simulating long-term exposure, modular for incorporating complex cellular interactions, and flexible for dealing with evolving tissues.     

Ecological theory meets soil ecotoxicology: Challenge and chance

The degradation of soils due to various anthropogenic stress factors is alarming. Although chemicals are a major reason for soil degradation, most ecologists are not interested in studying such effects. We try to wake their interest by addressing a number of unsolved soil ecotoxicological problems that are related to disturbance ecology, biodiversity, ecosystem functioning and modelling. Features distinguishing chemical from natural stress render promising new aspects in disturbance ecology. Ecotoxicological studies are ideal models of disturbance, particularly regarding frequency, intensity or multitude of stress. Patterns of secondary succession after a major chemical damage can directly be related to the intermediate disturbance hypothesis. More knowledge on altered life history patterns following stress could support both evolutionary ecology and risk assessment. We raise the question if inherent resource competition makes communities more vulnerable to stress. Three aspects of ecotoxicological risk assessment are introduced: (1) exposure and bioavailability, which is directly connected to environmental heterogeneity; (2) tests on ecosystem functioning, suffering from major drawbacks; and (3) modelling. Here, promising approaches exist but need substantial input for being applicable to soils. Ecological modelling should put more emphasis on simulating both natural and chemical disturbances, including behavioural aspects and environmental variability. Finally, research needs for ecological risk assessment in soils are derived such as a simple system to assess the impact of chemicals on soil biodiversity, the inclusion of behavioural changes of keystone species or the consideration of density-dependent effects. Common research efforts of basic ecologists and soil ecotoxicologists could render a lot of mutual benefits.     

Environmental impacts of gold mining in Essakane site of Burkina Faso

In this study, environmental impacts on air, water, and soil pollution caused by the exploit of Essakane gold mine, which is located in North Eastern part of Burkina Faso were investigated. Analyses on drinking water were made in the laboratory to determine the concentration of essential chemicals used in gold mining. Dust fallouts have been measured to assess the level of air pollution. The results showed that exploiting of gold mine directly or indirectly contributes to air pollution in Essakane district. The use of chemicals such as cyanide (industrial gold mining) and mercury (artisanal gold mining) to obtain the gold from the ore constitutes a potential risk for the ecosystem, the local population's health, and livestock production. The results also showed that there is a significant degradation of natural landscape and topography of the soil by open-pits mining (industrial mine) and holes dug by artisanal miners.     

基于生物标志物指数法的海洋环境评价方法综述

生物标志物对化学污染物具有“早期预警”功能,在海洋环境评价中应用广泛.以生物标志物为基础的综合指数能够整合多种标志物对环境状况的响应,因而成为评价环境质量的有用工具.这些综合指数方法包括多生物标志物污染指数(MPI)、综合生物标志物响应指数(IBR)、生物效应评价指数(BAI)、生物标志物响应指数(BRI)、健康状态指数(HIS)等.本文从生物标志物指标体系确定、综合指数计算方法、污染程度分级、应用效果等方面对这些评价方法进行综述,并对基于生物标志物指数的海洋环境评价方法存在的问题和改进建议进行了探讨.     

水生态系统中微囊藻毒素的分布及其生态毒理效应研究进展

有毒蓝藻产生的蓝藻毒素对淡水生态系统构成了严重的全球性环境威胁,其中微囊藻毒素(MCs)是所有蓝藻毒素中分布最广、危害最大的一类肝毒素。MCs已对水生态系统的结构、功能和稳定性造成了不良影响,并对人类健康构成威胁。本文综述了当前MCs在水体、沉积物和水生动物体内的分布,以及MCs的生物毒性机制,在此基础上,总结了MCs对水生动物、水生植物及陆生植物的生态毒理效应,及其引发的人类健康风险,并关注了MCs的生物防治方法。最后,针对当前MCs相关研究领域中存在的不足提出展望,旨在为淡水水体中MCs的风险评估与治理管控提供参考。     

Prospects for incorporation of epigenetic biomarkers in human health and environmental risk assessment of chemicals

Epigenetic mechanisms have gained relevance in human health and environmental studies, due to their pivotal role in disease, gene × environment interactions and adaptation to environmental change and/or contamination. Epigenetic mechanisms are highly responsive to external stimuli and a wide range of chemicals has been shown to determine specific epigenetic patterns in several organisms. Furthermore, the mitotic/meiotic inheritance of such epigenetic marks as well as the resulting changes in gene expression and cell/organismal phenotypes has now been demonstrated. Therefore, epigenetic signatures are interesting candidates for linking environmental exposures to disease as well as informing on past exposures to stressors. Accordingly, epigenetic biomarkers could be useful tools in both prospective and retrospective risk assessment but epigenetic endpoints are currently not yet incorporated into risk assessments. Achieving a better understanding on this apparent impasse, as well as identifying routes to promote the application of epigenetic biomarkers within environmental risk assessment frameworks are the objectives of this review. We first compile evidence from human health studies supporting the use of epigenetic exposure‐associated changes as reliable biomarkers of exposure. Then, specifically focusing on environmental science, we examine the potential and challenges of developing epigenetic biomarkers for environmental fields, and discuss useful organisms and appropriate sequencing techniques to foster their development in this context. Finally, we discuss the practical incorporation of epigenetic biomarkers in the environmental risk assessment of chemicals, highlighting critical data gaps and making key recommendations for future research within a regulatory context.