Progresos y retos de la Toxicología Genética / Progress and challenges of Genetic Toxicology

Resumen: Esta revisión resume los principales avances de la citogenética y proporciona una perspectiva sobre el futuro de la toxicología genética, desde el pasado, presente y futuro, tanto desde el punto de vista genético como epigenético. Los principios de la citogenética clásica han evolucionado con el tiempo, interactuando con enfoques de toxicología para dar lugar a la toxicología genética o mutagénesis ambiental. Actualmente, están surgiendo estudios toxicogenómicos basados en estudios de toxicología genética estándar, y uno de los principales objetivos de la toxicogenómica es detectar relaciones entre cambios en la expresión génica global y criterios de valoración toxicológicos, con el fin de comprender el papel de las interacciones gen-ambiente en la enfermedad. Para alcanzar este objetivo, la toxicogenómica combina la toxicología, la genética, tecnologías de perfiles moleculares de alto rendimiento como la transcriptómica, proteómica, metabolómica y la bioinformática. En este campo, muchas limitaciones restringen el papel de los nuevos hallazgos y enfoques. Por ejemplo, el costo de las nuevas tecnologías; sin embargo, su aplicación contribuirá a una mejor comprensión de las interacciones gen-ambiente y de esta manera, establecer políticas orientadas a prevenir riesgos para la salud, para que se viva una vida más saludable en un ambiente más favorable. (AU)

This review summarizes the main advances of cytogenetic and provides a perspective on the future of genetic toxicology, reviewing from past, present, and future, both genetics and epigenetic point of view. The principles of classical cytogenetics have evolved over time, interacting with toxicology approaches to give rise to genetic toxicology or environmental mutagenesis. Currently, toxicogenomic studies are emerging based on standard genetic toxicology studies, and one major goal of toxicogenomic is to detect relationships between changes in global gene expression and toxicological endpoints, in order to understand the role of gene-environment interactions in disease. To reach this goal, toxicogenomics combines toxicology, genetic, with genomics or other high throughput molecular profiling technologies such as transcriptomics, proteomics, metabolomics, and bioinformatics. In this field, many limitations are restricting the role of the novel findings and approaches. For example, the cost of new technologies; however, its application will contribute to a better understanding of gene-environment interactions and in this way, establish policies aimed at preventing health risks, so that a healthier life is lived in a friendlier environment. (AU)

Trends in the Application of "Omics" to Ecotoxicology and Stress Ecology.

Our ability to predict and assess how environmental changes such as pollution and climate change affect components of the Earth's biome is of paramount importance. This need positioned the fields of ecotoxicology and stress ecology at the center of environmental monitoring efforts. Advances in these interdisciplinary fields depend not only on conceptual leaps but also on technological advances and data integration. High-throughput "omics" technologies enabled the measurement of molecular changes at virtually all levels of an organism's biological organization and thus continue to influence how the impacts of stressors are understood. This bibliometric review describes literature trends (2000-2020) that indicate that more different stressors than species are studied each year but that only a few stressors have been studied in more than two phyla. At the same time, the molecular responses of a diverse set of non-model species have been investigated, but cross-species comparisons are still rare. While transcriptomics studies dominated until 2016, a shift towards proteomics and multiomics studies is apparent. There is now a wealth of data at functional omics levels from many phylogenetically diverse species. This review, therefore, addresses the question of how to integrate omics information across species.

A review on in vivo and in vitro nanotoxicological studies in plants: A headlight for future targets.

Owing to the unique properties and useful applications in numerous fields, nanomaterials (NMs) received a great attention. The mass production of NMs has raised major concern for the environment. Recently, some altered growth patterns in plants have been reported due to the plant-NMs interactions. However, for NMs safe applications in agriculture and medicine, a comprehensive understanding of bio-nano interactions is crucial. The main goal of this review article is to summarize the results of the toxicological studies that have shown the in vitro and in vivo interactions of NMs with plants. The toxicity mechanisms are briefly discussed in plants as the defense mechanism works to overcome the stress caused by NMs implications. Indeed, the impact of NMs on plants varies significantly with many factors including physicochemical properties of NMs, culture media, and plant species. To investigate the impacts, dose metrics is an important analysis for assaying toxicity and is discussed in the present article to broadly open up different aspects of nanotoxicological investigations. To access reliable quantification and measurement in laboratories, standardized methodologies are crucial for precise dose delivery of NMs to plants during exposure. Altogether, the information is significant to researchers to describe restrictions and future perspectives.

Micronucleus test in tadpole erythrocytes: Trends in studies and new paths.

The micronucleus test has been applied for more than three decades in tadpoles, generating an early warning of environmental quality. In this study, we reviewed 48 articles on the micronucleus test in tadpoles, published between 1987 and 2018. The findings reveal that pesticides have been the main topic discussed in the induction of micronucleus and other nuclear abnormalities in anuran larvae to the detriment of the widespread use of compounds used in agriculture. In addition to pesticides, a number of other xenobiotic agents have been targeted for genotoxic damage, such as heavy metals, radiation and wastewater. An appeal is reported to environmental contaminants, which when released naturally into the environment or because of human activities may contaminate aquatic habitats, threatening populations of tadpoles that depend on these environments for their survival. Larvae can bioaccumulate these contaminants that cause progressive impacts, ranging from DNA damage to metamorphosis delays, as well as malformations. We found that Argentina is the main driving force for the application of this test in anuran larvae along with Brazil. Different erythrocyte malformations have been reported for the erythrocyte nuclear abnormalities test, binucleated cells, nuclear buds, notched, lobed, reniform, nuclear bebbled, anucleated, picnotic and apoptotic cells are the most cited. In summary, the presence of chemical or physical agents, along with other disturbances of the habitat, can have a significant impact on the life history of the species, contributing to the decline of anuran populations.

Global Perspective on Careers in Environmental Toxicologic Pathology: The 2019 Society of Toxicologic Pathology Annual Symposium Lunchtime Career Development Session.

A wide range of career options is available globally in the environmental toxicologic pathology (ETP) arena including academia, government, contract research organizations, and the agrichemical/chemical industry. This small and specialized subset of toxicologic pathologists addresses the effects of contaminants and pollutants on human, animal, and ecological health (One Health). Veterinary students and pathology trainees are primarily exposed to diagnostic pathology and often have limited exposure to toxicologic pathology and even less so to the issues and opportunities in environmental toxicology. The speakers provided a brief overview of global opportunities in their work sector and personal perspectives of their careers in ETP. The following panel discussion provided an opportunity to discuss issues related to careers in this specialty.

Copper environmental toxicology, recent advances, and future outlook: a review.

Copper (Cu) is one of the micronutrients needed by living organisms. In plants, Cu plays key roles in chlorophyll formation, photosynthesis, respiratory electron transport chains, oxidative stress protection as well as protein, carbohydrate, and cell wall metabolism. Therefore, deficiency of Cu can alter various functions of plant metabolism. However, Cu-based agrochemicals have traditionally been used in agriculture and being excessively released into the environment by anthropogenic activities. Continuous and extensive release of Cu is an imperative issue with various documented cases of phytotoxicity by the overproduction of reactive oxygen species (ROS) and damage to carbohydrates, lipids, proteins, and DNA. The mobility of Cu from soil to plant tissues has several concerns including its adverse effects on humans. In this review, we have described about importance and occurrence of Cu in environment, Cu homeostasis and toxicity in plants as well as remediation and progress in research so far done worldwide in the light of previous findings. Furthermore, present review provides a comprehensive ecological risk assessment on Cu in soils and thus provides insights for agricultural soil management and protection.

Analytical approaches for characterizing and quantifying engineered nanoparticles in biological matrices from an (eco)toxicological perspective: old challenges, new methods and techniques.

To promote the safer by design strategy and assess environmental risks of engineered nanoparticles (ENPs), it is essential to understand the fate of ENPs within organisms. This understanding in living organisms is limited by challenges in characterizing and quantifying ENPs in biological media. Relevant literature in this area is scattered across research from the past decade or so, and it consists mostly of medically oriented studies. This review first introduces those modern techniques and methods that can be used to extract, characterize, and quantify ENPs in biological matrices for (eco)toxicological purposes. It then summarizes recent research developments within those areas most relevant to the context and field that are the subject of this review paper. These comprise numerous in-situ techniques and some ex-situ techniques. The former group includes techniques allowing to observe specimens in their natural hydrated state (e.g., scanning electron microscopy working in cryo mode and high-pressure freezing) and microscopy equipped with elemental microanalysis (e.g., energy-dispersive X-ray spectroscopy); two-photon laser and coherent anti-Stokes Raman scattering microscopy; absorption-edge synchrotron X-ray computed microtomography; and laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS). The latter group includes asymmetric flow field flow fractionation coupled with ICP-MS and single particle-ICP-MS. Our review found that most of the evidence gathered for ENPs actually focused on a few metal-based ENPs and carbon nanotube and points to total mass concentration but no other particles properties, such as size and number. Based on the obtained knowledge, we developed and presented a decision scheme and analytical toolbox to help orient scientists toward selecting appropriate ways for investigating the (eco)toxicity of ENPs that are consistent with their properties.

Interactions between anthropogenic litter and birds: A global review with a 'black-list' of species.

The interaction of anthropogenic litter (by incorporation litter in nests, ingestion, and entanglement) with birds was systematically reviewed using Google Scholar database. A 'black-list' of 258 species was compiled. Among them 206 (79.8%) were seabirds. Four seabird orders (Gaviiformes, Phaetontiformes, Procellariformes, Sphenisciformes) showed the highest percentage of interacting species. At family level, >70% of species of Gaviidae, Diomedeidae, Sulidae, Stercoraridae and Alcidae were involved in interactions with litter. We observed (i) a significant correlation between Scholar recurrences and species citations about anthropogenic litter only when considering seabirds; (ii) a low number of references before 1981 with a bimodal pattern showing a first peak in 1986-90 and a progressively increasing trend in the 2000s. Regarding the type of interaction, there was a significantly higher percentage of species involved in ingestion when compared to the percentage involved in entanglement. We suggest the use of consolidated standardized litter nomenclature and characterization and the adoption of a logical causal chain helping researchers in defining suitable frameworks.

Ecotoxicoproteomics: A decade of progress in our understanding of anthropogenic impact on the environment.

Anthropogenic pollutants are found worldwide. Their fate and effects on human and ecosystem health must be appropriately monitored. Today, ecotoxicology is focused on the development of new methods to assess the impact of pollutant toxicity on living organisms and ecosystems. In situ biomonitoring often uses sentinel animals for which, ideally, molecular biomarkers have been defined thanks to which environmental quality can be assessed. In this context, high-throughput proteomics methods offer an attractive approach to study the early molecular responses of organisms to environmental stressors. This approach can be used to identify toxicity pathways, to quantify more precisely novel biomarkers, and to draw the possible adverse outcome pathways. In this review, we discuss the major advances in ecotoxicoproteomics made over the last decade and present the current state of knowledge, emphasizing the technological and conceptual advancements that allowed major breakthroughs in this field, which aims to "make our planet great again". SIGNIFICANCE: Ecotoxicoproteomics is a protein-centric methodology that is useful for ecotoxicology and could have future applications as part of chemical risk assessment and environmental monitoring. Ecotoxicology employing non-model sentinel organisms with highly divergent phylogenetic backgrounds aims to preserve the functioning of ecosystems and the overall range of biological species supporting them. The classical proteomics workflow involves protein identification, functional annotation, and extrapolation of toxicity across species. Thus, it is essential to develop multi-omics approaches in order to unravel molecular information and construct the most suitable databases for protein identification and pathway analysis in non-model species. Current instrumentation and available software allow relevant combined transcriptomic/proteomic studies to be performed for almost any species. This review summarizes these approaches and illustrates how they can be implemented in ecotoxicology for routine biomonitoring.

General introduction and outline of the special issue "Emerging advances and challenges in pesticide ecotoxicology".

The aim of this special issue was to bring together papers dealing with current challenges and trends in pesticide ecotoxicology. The special issue is composed of 25 papers into various topics, ranging from the development of more ecological ecotoxicological test approaches to an evaluation of citation bias in pesticide ecotoxicology literature. This paper provides a general introduction and an index of the various papers in the special issue. This special issue is trusted to provide a valuable contribution in addressing current challenges in pesticide ecotoxicology.

Corticosterone in American alligator (Alligator mississippiensis) tail scutes: Evaluating the feasibility of using unconventional samples for investigating environmental stressors.

Baseline plasma corticosterone (CORT) concentrations have been widely used to investigate the effects of stressors in wild and captive crocodilians. However, collecting baseline plasma CORT samples from wild crocodilians may be particularly difficult due to the capture and handling protocols used for large individuals. Thus, it may prove beneficial to use recently modified techniques for extracting CORT deposited in keratinized and non-keratinized tissues to better quantify the effects of long-term stress in crocodilians. In this study, we investigated the feasibility of using American alligator (Alligator mississippiensis) tail scute tissues to quantify CORT by collecting blood and tail scutes from 40 alligators before and after a short-term handling stressor. The objective of the current study was to better understand CORT deposition in crocodilian scutes and whether short-term increases in CORT could be detected. We found that CORT can be reliably extracted from alligator scute tissue and quantified using a commercially available enzyme immunoassay. However, there was a significant increase in scute CORT concentrations following an alligator being exposed to a short-term stressor (p = 0.017), although the magnitude of change was less than observed in plasma samples from the same individuals (p = 0.002). Furthermore, our results indicate that there was a significant effect of body condition on an alligator's post-stressor CORT concentration (p = 0.02). While our study is among the first to experimentally examine the usefulness of tissue CORT in crocodilians, a combination of field and laboratory experiments are needed to better understand deposition rates of CORT in scute tissues and to further validate the usefulness of tissue glucocorticoids for evaluating the effects of stress.

Historical Highlights of Air Pollution Toxicology.

Air pollution has a compelling history in the development of human cultures. Fossil fuels opened a new human cultural chapter of extraordinary technical and economic growth while bringing about noxious and unhealthful combustion byproducts to breathe. Toxicology saw its birth in the modern world with demonstrating the potential harmful effects of breathing smoke in its various forms. The empirical nature of toxicology provided insights and underpinnings to epidemiological studies providing biological plausibility and relative risk attributions. As toxicology evolves with its sister sciences, there will be gains in fundamental understandings of susceptibility and potential long-term risks of air pollution with revelation of potential interventions and remedies for those affected.

A Data Fusion Pipeline for Generating and Enriching Adverse Outcome Pathway Descriptions.

Increasing amounts of systems toxicology data, including omics results, are becoming publically available and accessible in databases. Data-driven and informatics-tool supported pipeline schemas for fitting such data into Adverse Outcome Pathway (AOP) descriptions could potentially aid the development of nonanimal-based hazard and risk assessment methods. We devised a 6-step workflow that integrated diverse types of toxicology data into a novel AOP scheme for pulmonary fibrosis. Mining of literature references and diverse data sources covering previous pathway descriptions and molecular results were coupled in a stepwise manner with informatics tools applications that enabled gene linkage and pathway identification in molecular interaction maps. Ultimately, a network of functional elements coupled 64 pulmonary fibrosis-associated genes into a novel, open-source AOP-linked molecular pathway, now available for commenting and improvements in WikiPathways (WP3624). Applying in silico-based knowledge extraction and modeling, the pipeline enabled screening and fusion of many different complex data types, including the integration of omics results. Overall, the taken, stepwise approach should be generally useful to construct novel AOP descriptions as well as to enrich developing AOP descriptions in progress.

Applying 'omics technologies in chemicals risk assessment: Report of an ECETOC workshop.

Prevailing knowledge gaps in linking specific molecular changes to apical outcomes and methodological uncertainties in the generation, storage, processing, and interpretation of 'omics data limit the application of 'omics technologies in regulatory toxicology. Against this background, the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) convened a workshop Applying 'omics technologies in chemicals risk assessment that is reported herein. Ahead of the workshop, multi-expert teams drafted frameworks on best practices for (i) a Good-Laboratory Practice-like context for collecting, storing and curating 'omics data; (ii) the processing of 'omics data; and (iii) weight-of-evidence approaches for integrating 'omics data. The workshop participants confirmed the relevance of these Frameworks to facilitate the regulatory applicability and use of 'omics data, and the workshop discussions provided input for their further elaboration. Additionally, the key objective (iv) to establish approaches to connect 'omics perturbations to phenotypic alterations was addressed. Generally, it was considered promising to strive to link gene expression changes and pathway perturbations to the phenotype by mapping them to specific adverse outcome pathways. While further work is necessary before gene expression changes can be used to establish safe levels of substance exposure, the ECETOC workshop provided important incentives towards achieving this goal.

The challenge of the application of 'omics technologies in chemicals risk assessment: Background and outlook.

This survey by the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) highlights that 'omics technologies are generally not yet applied to meet standard information requirements during regulatory hazard assessment. While they are used within weight-of-evidence approaches to investigate substances' modes-of-action, consistent approaches for the generation, processing and interpretation of 'omics data are not applied. To date, no 'omics technology has been standardised or validated. Best practices for performing 'omics studies for regulatory purposes (e.g., microarrays for transcriptome profiling) remain to be established. Therefore, three frameworks for (i) establishing a Good-Laboratory Practice-like context for collecting, storing and curating 'omics data; (ii) 'omics data processing; and (iii) quantitative WoE approaches to interpret 'omics data have been developed, that are presented in this journal supplement. Application of the frameworks will enable between-study comparison of results, which will facilitate the regulatory applicability of 'omics data. The frameworks do not constitute prescriptive protocols precluding any other data analysis method, but provide a baseline for analysis that can be applied to all data allowing ready cross-comparison. Data analysis that does not follow the frameworks can be justified and the resulting data can be compared with the Framework-based common analysis output.

The evolution of environmental metalloproteomics over the last 15 years through bibliometric techniques.

Metalloproteomic studies in environmental scenarios are of significant value in elucidating metal uptake, trafficking, accumulation and metabolism linked to biomolecules in biological systems. The advent of this field occurred in the early 2000s, and it has since become an interesting and growing area of interdisciplinary research, although the number of publications in Environmental Metalloprotemics is still very low compared to other metallomic areas. In this context, the evolution of Environmental Metalloprotemics in the last decades was evaluated herein through the use of bibliometric techniques, identifying variables that may aid researchers in this area to form collaborative networks with established scientists in this regard, such as main authors, published articles, institutions, countries and established collaborations involved in academic research on this subject. Results indicate a growing trend of publications over time, reflecting the interest of the scientific community in Environmental Metalloprotemics, but also demonstrated that the research interactions in this field are still country- and organization-specific. Higher amounts of publications are observed from the late 2000's onwards, related to the increasing technological advances in the area, such as the development of techniques combining atomic spectroscopy and biochemical or proteomic techniques. The retrieved publications also indicate that the recent advances in genomic, proteomic and metallomic areas have allowed for extended applications of Environmental Metalloprotemics in non-model organisms. The results reported herein indicate that Environmental Metalloprotemics seems to now be reaching a more mature stage, in which analytical techniques are now well established and can be routinely applied in environmental scenarios, benefitting researchers and allowing for further insights into this fascinating field.

(Q)SARs to predict environmental toxicities: current status and future needs.

The current state of the art of (Quantitative) Structure-Activity Relationships ((Q)SARs) to predict environmental toxicity is assessed along with recommendations to develop these models further. The acute toxicity of compounds acting by the non-polar narcotic mechanism of action can be well predicted, however other approaches, including read-across, may be required for compounds acting by specific mechanisms of action. The chronic toxicity of compounds to environmental species is more difficult to predict from (Q)SARs, with robust data sets and more mechanistic information required. In addition, the toxicity of mixtures is little addressed by (Q)SAR approaches. Developments in environmental toxicology including Adverse Outcome Pathways (AOPs) and omics responses should be utilised to develop better, more mechanistically relevant, (Q)SAR models.