Research Dries Knapen

Abstract

Background: The exposome encompasses the totality of environmental exposures of an individual or organism throughout life (including exposure to chemicals, diet, lifestyle, climate factors, stress), and how these exposures impact biology (e.g., metabolites, hormones, etc.) and health. In particular, exposure to endocrine disrupting chemicals (EDCs), including metabolic disrupting chemicals (MDCs), has been linked to a broad range of non-communicable diseases and environmental health effects. Workflows for gathering and interpreting exposome data are still in development and are currently focusing on elucidating physiological pathways that link exposure to adverse effects. Ultimately, this will lead to a holistic understanding of how exposures interact with the phenotype to cause adverse health outcomes with potentially large societal, economic, and ecological costs. Aims: We will use innovative approaches to decipher the human exposome from early life on up to adulthood and its association with endocrine and metabolic alterations (leading to disorders, such as liver diseases, metabolic syndrome, diabetes, and obesity), as well as effects on other important physiological processes mostly driven by endocrine and metabolic signaling.

Researcher(s)

• Promoter: Covaci Adrian
• Co-promoter: Bervoets Lieven
• Co-promoter: Bittremieux Wout
• Co-promoter: De Boeck Gudrun
• Co-promoter: Hermans Nina
• Co-promoter: Jorens Philippe
• Co-promoter: Knapen Dries
• Co-promoter: Leroy Jo
• Co-promoter: van Nuijs Alexander

Research team(s)

• Toxicological Centre

Project type(s)

• Research Project

Abstract

The EU has flagged endocrine disrupting chemicals (EDCs), which interfere with normal hormonal function leading to adverse health effects, of particular concern. Within different EU regulatory programmes the assessment of EDCs has recently changed significantly and continues to evolve rapidly. Advances in test methods for assessment of EDCs are needed to meet these changing regulatory requirements, and a new generation of toxicologists must be trained to support the implementation of the most advanced approaches. NeXED will address three critical challenges in this area. First, human and environmental EDC assessment have historically been separate disciplines while there is an increasing need to use data across species in a One Health approach. Second, EDC assessment currently addresses single compounds while in an environmentally realistic scenario organisms are faced with complex mixtures of EDCs. Third, new test methods for EDC assessment are needed, covering less well-characterised mechanisms and effects. NeXED aims to facilitate a paradigm shift in EDC assessment by training a new generation of cross-disciplinary toxicologists specialised in using harmonised approaches in a One Health framework. NeXED will train its 14 doctoral candidates through research, secondments and training events using an interdisciplinary and intersectoral training programme. NeXED brings together 10 Beneficiaries and 10 Associated Partners from 10 countries, building upon long-standing collaborations through existing projects including the Horizon 2020 EURION projects and the Horizon Europe Partnership on the Assessment of Risk from Chemicals (PARC). The consortium includes leading researchers from institutions with excellent doctoral training programmes who are all experts in ED assessment, as well as industry partners, regulatory agencies, SMEs and consultancy firms. With its complementary expertise the consortium is ideally placed to train the NeXED generation of toxicologists.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Covaci Adrian
• Co-promoter: van Nuijs Alexander
• Co-promoter: Vergauwen Lucia

Research team(s)

• Veterinary physiology and biochemistry

Project website

Project type(s)

• Research Project

Abstract

Chemicals risk assessors and managers are faced with data and knowledge gaps and lack of tools and methods, to speed up and prioritise risk assessments and capture risks from existing and emerging substances across regulatory domains. The lack of available or accessible information increases the risk of 'regrettable' substitutions and slows down the design of safer chemicals. A diverse landscape of regulatory frameworks and actors carrying out risk assessment of chemicals for their specific purpose has resulted in a fragmented approach. Risks to human and environmental health are still in certain cases considered separately, while in most cases they are inherently interrelated. To enable risk assessors and risk managers to respond to current and future challenges, the Partnership should stimulate research and innovation in chemicals risk assessment by developing a collaborative network with public research entities. A common research and innovation programme should be established by national and EU risk assessors and risk managers in consultation with relevant stakeholders (academia, industry, associations and others). Activities of the Partnership should be complementary and subsidiary to obligations under existing regulatory frameworks, and should coordinate with these as relevant. The Partnership should become a reference centre for research questions related to chemicals risk assessment, including those emerging from other Horizon Europe partnerships or missions. The Partnership is expected to establish relevant collaborations with other Horizon Europe partnerships and missions as set out in the working document on 'Coherence and Synergies of candidate European partnerships under Horizon Europe' as well as to explore collaborations with other relevant activities at EU and international level. The Partnership should align with EU-wide initiatives on open access and FAIR data.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Bervoets Lieven
• Co-promoter: Blust Ronny
• Co-promoter: Covaci Adrian
• Co-promoter: Groffen Thimo
• Co-promoter: Poma Giulia
• Co-promoter: van Nuijs Alexander
• Co-promoter: Vergauwen Lucia

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

The ongoing population and consumption growth is rapidly increasing the demand for agricultural food production. At the same time, increasing environmental awareness raises concerns about the choice of agricultural practices in terms of their impact on ecosystem functioning and biodiversity. As the need to satisfy these demands is further exacerbated by the interrelated impact of climate change, the agriculture sector is left with the challenge to meet the growing demand for food through climate-adapted methods that alleviate the environmental impact of agriculture and increase the resilience to climate change. Dealing with this challenge requires a multifaceted global approach, including an optimized use of nutrient input and an increased crop tolerance to environmental stress. To this end, innovative technologies based on bioresources include the use of microalgal biostimulants to improve crop yield while lowering the environmental footprint of agriculture. However, the limited amount of scientific evidence that 1) microalgal biostimulants effectively improve agronomic efficiency, including a lack of understanding on the underlying mode of action, and that 2) microalgal biostimulants do not present a risk to the natural environment hampers the further development and establishment of this technology. Moreover, market success of microalgal biostimulants hinges on an optimized cultivation process to ensure a high yield and a standardized content of microalgal products. The VIGOROUS research consortium will address these knowledge gaps to facilitate evidence-based application of microalgal biostimulants and to support a science-based biostimulants industry to sustainably intensify agricultural production with an enhanced resilience to climate change.

Researcher(s)

• Promoter: Knapen Dries

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

This PhD project will investigate life-stage specific effects in zebrafish embryos exposed to thyroid hormone system disrupting chemicals. Specifically, we study the impact on the function of the hypothalamus pituitary thyroid axis and the development of target organs. We use swim bladder and eye development as model organs and we distinguish between effects on early and late embryonic development. This knowledge is crucial to advance the use of the zebrafish embryo as alternative to animal testing in thyroid hormone system disruption research and in applications for chemical safety evaluation.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Vergauwen Lucia
• Fellow: Van Dingenen Imke

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

We will develop a pioneering holistic framework based on innovative approaches to explore the human exposome in terms of exposure leading to adverse effects with a focus on endocrine-modulated neurological and metabolic disorders by: i. Identifying and characterizing the exposure sources of relevant chemicals in the context of the xposome framework; ii. developing and applying in silico, in vitro and in vivo human and animal models to investigate the absorption, distribution, metabolism, and excretion processes after exposure to chemicals; iii. setting up relevant clinical/epidemiological exposure-wide association studies to better understand the associations between exposure and neurological and metabolic disorders in longitudinal and (nested) casecontrol cohorts and including birth cohorts to understand transgenerational mechanisms; iv. using targeted and untargeted omics techniques (e.g. metabolomics and transcriptomics) in human and animal biological systems to aid data-driven discovery of causal factors for adverse health effects; v. linking exposure to mixtures by integrating exposome research with the adverse outcome pathway concept, a novel toxicological framework structuring the cascade of biological events from an initial molecular-level perturbation of a biological system to an adverse health outcome.

Researcher(s)

• Promoter: Covaci Adrian
• Co-promoter: Bervoets Lieven
• Co-promoter: Blust Ronny
• Co-promoter: Eens Marcel
• Co-promoter: Jorens Philippe
• Co-promoter: Knapen Dries
• Co-promoter: van Nuijs Alexander

Research team(s)

• Toxicological Centre

Project type(s)

• Research Project

Abstract

Chemicals risk assessors and managers are faced with data and knowledge gaps and lack of tools and methods, to speed up and prioritise risk assessments and capture risks from existing and emerging substances across regulatory domains. The lack of available or accessible information increases the risk of 'regrettable' substitutions and slows down the design of safer chemicals. A diverse landscape of regulatory frameworks and actors carrying out risk assessment of chemicals for their specific purpose has resulted in a fragmented approach. Risks to human and environmental health are still in certain cases considered separately, while in most cases they are inherently interrelated. In this context, the present project contributes to the development of a mechanistic Integrated Approaches for Testing and Assessment (IATA) model for the identification of thyroid hormone system disrupting chemicals.

Researcher(s)

• Promoter: Knapen Dries

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

Brugada syndrome (BrS) is an inherited arrhythmic disorder and is estimated to account for up to 12% of all sudden cardiac death cases, especially in the young (< 40 years old). Only in circa 30% of BrS patients the underlying genetic cause can be identified with current diagnostic arrhythmia gene panels. Moreover, the use of these panels result in detection of numerous genetic "Variants of Uncertain Significance" (so called VUS), but currently functional models to prove their causality are lacking. Therefore, in my project I will create two proof-of-concept models for a known pathogenic CACNA1C mutation associated with BrS: a cardiomyocyte cell model, created from human stem cells, and a novel transgenic zebrafish model with built-in fluorescent calcium and voltage indicators. By functionally characterising these models with innovative imaging and electrophysiological techniques, I will assess the mutation's effect on a cellular level and in the whole heart, proving its contribution to disease causation. After validating these models, I will apply this strategy to functionally assess the pathogenicity of two VUS identified in two BrS patients. Ultimately, by establishing the use of these state-of-the-art study models to predict the pathogenicity of BrS-related VUS, a more accurate risk stratification and proficient use of specialized prevention strategies can be implemented in the future, potentially also for other electrical disorders of the heart.

Researcher(s)

• Promoter: Loeys Bart
• Co-promoter: Alaerts Maaike
• Co-promoter: Knapen Dries
• Co-promoter: Labro Alain
• Co-promoter: Schepers Dorien
• Co-promoter: Snyders Dirk
• Fellow: Vandendriessche Bert

Research team(s)

• Medical Genetics (MEDGEN)

Project type(s)

• Research Project

Abstract

About 10-15% of all animals used as laboratory animals in Flanders are fish. While the assessment of animal welfare is well established for mammals, the optimal conditions for guaranteeing fish welfare are less known or documented. A formal framework for optimizing and monitoring zebrafish welfare does currently not exist. This project therefore aims to develop a guidance document providing scientific and practical instructions for improving zebrafish welfare in laboratory animal facilities. The guidance document will be relevant to animal caretakers, technicians, responsible scientists, members of ethical committees, and animal welfare inspectors.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: De Boeck Gudrun
• Co-promoter: Van Ginneken Chris
• Co-promoter: Vergauwen Lucia

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

The project will bring part of the SPHERE research group to ISO 17025 "General requirements for the competence of testing and calibration laboratories" accreditation. The main activities of the project are all focused on different points of the ISO standard: validation of methods, training of personnel, establishing a quality management system, etc. Additionally we foresee a limited investment in equipment which needs to be compliant to the standard in terms of validation possibilities and the prevention of use by SPHERE members not trained in the quality system. As to valorization, we will operate as a service lab with an open eye for spinoff creation in the future.

Researcher(s)

• Promoter: Blust Ronny
• Co-promoter: Knapen Dries

Research team(s)

Project website

Project type(s)

• Research Project

Abstract

Mitochondria are the driving force behind virtually all vital cellular processes, including cellular proliferation, differentiation, cell death and epigenetic regulation. Consequently, their dysfunction is intricately connected to altered metabolic states and disease progression. We aim at acquiring a Seahorse XFp Analyzer, which can directly measure mitochondrial respiration and glycolysis through Oxygen Consumption Rate (OCR) and Extracellular Acidification Rate (ECAR) in different biological samples. Determination of cellular metabolic phenotype and mitochondrial activity is crucial for precise characterization of the research models and the pathophysiological alterations studied in various research disciplines across the University of Antwerp; including reproductive biology and toxicology, cell biology, neurodegenerative disease, cardiovascular function, cancer, obesity, diabetes, metabolic disorders, immunology, virology and toxicology, amongst others. This is also a key for drug screening and development of new treatment strategies. Seahorse XF analyzers offer the most sensitive and accurate technology with the highest throughput compared to other alternatives. It has contributed to ground-breaking discoveries demonstrated in an increasing number of publications in different research fields about the critical role of metabolism in a wide variety of diseases. It has been successfully applied on various types of cells and tissues including mammalian gametes, primary cells, adherent and suspension cell lines, cells differentiated from induced pluripotent stem cells, isolated mitochondria, 3D cultures, Zebrafish and mammalian embryos, roundworms, fruit flies and yeast. Adding to the broad applicability of the platform, the XF technology employs a label-free, non-invasive methodology allowing samples to be used post-measurement for other investigations. The Seahorse XFp Analyzer will directly contribute to several ongoing and future research within laboratories belonging to different departments and faculties at UA. Furthermore, this new platform will not only facilitate our on-site accessibility, but will also increase our national and international competitiveness. It will further support multidisciplinary networking and collaboration and shall further increase our scientific research excellence.

Researcher(s)

• Promoter: Leroy Jo
• Co-promoter: De Meyer Guido
• Co-promoter: Knapen Dries
• Co-promoter: Timmerman Vincent

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

ERGO presents a new approach that will support a paradigm shift in the regulatory use of standardized test guidelines (TGs) by breaking the existing wall between mammalian and non-mammalian vertebrate testing and assessment of endocrine disrupting chemicals (EDCs). The highly conserved thyroid system will be used as the "proof of concept", but also other conserved endocrine axes/systems such as the Retinoid X Receptor (RXR) and the Hypothalamus Pituitary Gonadal (HPG) axis can be adapted to the cross-vertebrate class approach. ERGO will investigate a battery of draft in vitro assays and evaluate thyroid-responsive biomarkers and endpoints (B/E) suitable for extrapolation of effects from fish and amphibian tests to humans and other mammals (and vice versa) and finally validate successful B/E for inclusion in existing in vivo or new in vitro OECD TGs. A cross-class adverse outcome pathway (AOP) network will provide the scientifically plausible and evidence-based foundation for the selection of B/E in lower vertebrate assays predictive of human health outcomes. In silico modeling and biotransformation data will support cross-vertebrate class effect extrapolation. Major outcomes of ERGO will be: 1) New thyroid-related B/E for inclusion in OECD TGs for improved identification of TDC. 2) An Integrated Approach to Testing and Assessment (IATA) of chemicals for TD based on a multi-class vertebrate AOP network connecting endocrine mechanisms in one vertebrate class to adverse outcomes in another class for safer regulation of EDCs. 3) A tool for TG end users, such as regulators and industry, to extrapolate thyroid effects between vertebrate classes. Implementation of the ERGO IATA strategy in regulations of EDC will make hazard and risk assessment faster, cheaper, simpler and safer and support industry in the development of EDC-free products beneficial for environmental and human safety.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Vergauwen Lucia

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

Obesity constitutes a major health problem, partly due to the increasing prevalence and secondly because of its associated morbidity. It is associated with increased amounts of adipose tissue as well as fat accumulation in non-adipose tissue such as liver and skeletal muscle. Accumulation of ectopic fat in the liver (non-alcoholic fatty liver disease, NAFLD) is a strong independent marker of dyslipidaemia and insulin resistance predisposing to the development of type 2 diabetes. Besides high caloric diet and lack of physical activity, pesticide exposure and endocrine disruptor pollutants are now also increasingly recognized as an "obesogenic" risk factor. Remarkably, recent genome- and epigenome wide associations studies highlight crosstalk of many obesity-associated genetic variants and environmental factors (diet, pesticides, exercise, alcohol consumption, smoking, drugs, medication) with DNA methylation changes at proximal promoters and enhancers. For example, we recently found a strong association between the paraoxonase 1 (PON1) p.Q192R genotype with pesticide exposure and adverse epigenetic (re)programming of endocrine pathways in obesity and high body fat content. PON members hydrolyze several pesticides, a number of exogenous and endogenous lactones and metabolizes toxic oxidized lipids of low density lipoproteins (LDL) and HDL. A decrease in PON1 expression promotes adverse lipid metabolism and is an important risk factor for cardiometabolic disease and has recently been found to be associated with childhood and adult obesity, liver steatosis and its more severe subtype of steatohepatitis. Differences in PON2 have been associated with obesity susceptibility in brown/white adipose tissue. Given the crucial role of PON members in protecting from adverse environmental exposure and from obesity, there is an urgent need for further molecular and clinical research on (epi)genetic PON(1-3) regulation mechanisms in this area. In this GOA, we want to further investigate associations of clinical characterized obesity phenotypes with PON(1-3) genetic variants/polymorphisms, associated epigenetic DNA methylation variation and PON(1-3) expression in samples (i.e. blood, serum, adipose or liver) of clinical patient cohorts diagnosed with obesity, NAFLD/NASH, in relation to adverse pesticide exposure or following therapeutic medical intervention (liraglutide or bariatric surgery). Functional investigation of genetic-epigenetic regulatory crosstalk of PON(1-3) expression in response to pollutant exposure or following medical interventions will be further investigated in relation to biochemical parameters of obesity/liver steatosis/adipocyte differentiation in cell models in vitro as well as in zebrafish in vivo. As such, a better understanding of variable PON(1-3) regulation of obesity-associated traits by adverse obesogenic pollutants or healthy intervention strategies may offer new perspectives to prevent obesity and/or promote cardiometabolic health.

Researcher(s)

• Promoter: Van Hul Wim
• Co-promoter: Francque Sven
• Co-promoter: Knapen Dries
• Co-promoter: Vanden Berghe Wim

Research team(s)

• Medical Genetics (MEDGEN)

Project type(s)

• Research Project

Abstract

The presence of certain toxicants/chemicals can perturb the endocrine system and induce a variety of responses, some of which can cause severe adverse effects in humans and wildlife. In order to protect human health and the environment, it is therefore important to identify those substances that can cause adverse effects via disruption of the endocrine system. Availability of test methods is an important factor in our ability to identify the substances that cause adverse effects via disruption of the endocrine system and in ensuring a high level of protection of human health and the environment. To ensure that test methods are internationally and mutually accepted a test guideline development programme has been established under the auspices of the OECD. Despite the progress achieved on the development and validation of test guidelines for evaluation of endocrine disruptors over the last 20 years, there are still some gaps and weaknesses in the current test methods for evaluation of endocrine disruptors. The objective of this study is to develop study protocols for testing of endocrine disrupting effects in biotic systems to improve the identification of substances disturbing the endocrine system by enhancing already existing test guidelines.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Vergauwen Lucia

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

Inherited Cardiac Arrhythmia (ICA) refers to a group of genetic disorders in which patients present with abnormal and potentially harmful heart rhythm. These episodes often go unnoticed, but can lead to fainting and sudden cardiac death. At present, over 50 ICA genes have been identified. With the advent of next generation sequencing technology it is possible to test all of these genes simultaneously in multiple ICA patients with a single test. This method proficiently identifies clear disease causing genetic alterations. However, as the number of genes involved increases through better mechanistic insight into disease modifier genes and polymorphisms, we are confronted with a high number of genetic alterations for which causality is unsure. These pose a major challenge for the management of ICA patients. Therefore, the aim of this project is to develop a functional tool that will allow to test the functional impact of variants of unknown significance. We have developed a zebrafish assay in which the electrical dynamics of the heart are reported by fluorescent light signals. As zebrafish are translucent in early development, this model lends itself perfectly to visualize these signals 'in vivo' and at an exceptional resolution. After validating this tool with known pathogenic alterations, we will apply this method to evaluate variants of unknown significance and test the possible arrhythmogenic side effects of some drugs. This innovative approach will allow the clinicians to deliver true personalized medicine.

Researcher(s)

• Promoter: Snyders Dirk
• Co-promoter: Knapen Dries
• Fellow: Schepers Dorien

Research team(s)

• Experimental Neurobiology Unit (ENU)

Project type(s)

• Research Project

Abstract

Metals play a pivotal role in various biochemical and physiological processes. They are widely found in nature, particularly in mineral deposits and soils, meaning that they are available to be taken up by plants and animals that serve as a food source for humans. Virtually, all metals, including the essential metal micronutrients, are toxic to both fresh and marine organisms as well as humans if exposure levels are sufficiently high. The toxicity of the most important metals such as copper, zinc, nickel, lead, cadmium, etc. have been extensively documented for various species and the results have been used to derive environmental standards. However, the studies on potential toxicity in combined metal scenarios via different routes of exposure and its comparison at different biological levels is scarce. Our study is a first of its kind, in which we will study mixed metal toxicity through different routes of exposure in different organisms. This will not only provide an insight into underlying molecular mechanisms in generic versus compound specific stress responses, but also compare the effects at different biological levels, via different routes of exposure. This will help to understand if the effects are species specific and whether the effects are dependent upon routes of exposure. We expect that with this study we should be able to predict the consequences of metal contamination not only from the toxicological view point but also from ecological point of view.

Researcher(s)

• Promoter: Knapen Dries

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

At least 60% of all industrial chemicals cause environmental toxicity through a mechanism called narcosis. In a toxicological context, the term narcosis refers to lipophilic chemicals accumulating in cellular membranes. There is an urgent need for a better understanding of sublethal narcosis effects to improve environmental risk assessment of this vast body of chemicals. Based on direct and indirect evidence from both our own preliminary results and literature, we hypothesize that narcotics impair mitochondrial membrane-bound processes. The central objective of this project is to develop a detailed description of the molecular, cellular and organismal cascade of events resulting from accumulation of narcotics in mitochondrial membranes. We will use cell lines and zebrafish embryos. First, we will study the impact of narcotics on mitochondrial structure and essential functions. Secondly, we will characterize organismal effects which are of direct ecological relevance for risk assessment. Thirdly, we will use specific mitochondrial inhibitors to validate whether they produce the same cascade of events, from the molecular (RNA-seq, whole transcriptome Next Generation Sequencing) to the organismal level. In the final and most challenging work package we will use state-of-the-art imaging technology to visualize the dynamics of accumulation of narcotics in live zebrafish embryos, and subcellular accumulation behaviour.

Researcher(s)

• Promoter: Blust Ronny
• Co-promoter: Knapen Dries

Research team(s)

Project type(s)

• Research Project

Abstract

The application concerns an innovative microscopy platform for visualizing cells, tissue specimen and living small model organisms in three dimensions at unprecedented speed and with excellent resolution and contrast. As a unique feature, the platform is equipped with a light-sheet module, which is based on an orthogonal configuration of laser-generated, micrometer-thin plane illumination and sensitive one-shot detection. Seamless integration with confocal modalities enables imaging the same sample from the micro- to the mesoscale. The device has a broad application radius in the neurosciences domain inter alia for studying neurodegeneration and -regeneration (e.g. whole brain imaging, optogenetics); but it also has direct utility in various other fields such as cardiovascular research (e.g. plaque formation and stability), plant developmental research (e.g. protein localization during plant growth) and ecotoxicology (e.g. teratogenicity and developmental defects in zebrafish). Furthermore, its modular construction will enable adaptation and targeted expansion for future imaging needs.

Researcher(s)

• Promoter: Timmermans Jean-Pierre
• Co-promoter: Adriaensen Dirk
• Co-promoter: De Meyer Guido
• Co-promoter: De Vos Winnok
• Co-promoter: D'Haese Patrick
• Co-promoter: Giugliano Michele
• Co-promoter: Jordanova Albena
• Co-promoter: Keliris Georgios A.
• Co-promoter: Knapen Dries
• Co-promoter: Maudsley Stuart
• Co-promoter: Ponsaerts Peter
• Co-promoter: Timmerman Vincent
• Co-promoter: Vissenberg Kris

Research team(s)

• Laboratory of cell biology and histology

Project type(s)

• Research Project

Abstract

This project aims to develop an alternative testing strategy to reduce the need for fish early life-stage toxicity tests (FELS) for the assessment of chronic toxicity of chemicals to fish, using the adverse outcome pathway (AOP) framework as a guidance for assay development. Currently, the FELS test (OECD TG 210) is one of the primary testing guidelines used to estimate the chronic toxicity of chemicals to fish. Results obtained using this TG are used to support risk assessment around the world. However, important limitations of this animal test are being recognized, including (1) the high numbers of fish used, (2) the relatively low-throughput, and (3) the lack of mechanistic information. In order to comply with the 3R principles, we are developing a non-animal testing strategy which includes both in vitro tests and in vivo whole organism alternative 120 hpf (hours post fertilization) ZFET (zebrafish embryo acute toxicity test) assays. One of the main research questions of this project is to what extent an assay development approach based on the AOP framework is capable of offering a mechanistic basis for selecting assays to develop an alternative testing strategy that allows the prediction of chronic FELS toxicity. This project is a follow-up of Cefic LRI-ECO20, and aims to validate assays that were developed during that project.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Blust Ronny
• Co-promoter: Vergauwen Lucia

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

This project aims to develop an alternative testing strategy to reduce the need for fish early life-stage toxicity tests (FELS) for the assessment of chronic toxicity of chemicals to fish, using the adverse outcome pathway (AOP) framework as a guidance for assay development. Currently, the FELS test (OECD TG 210) is one of the primary testing guidelines used to estimate the chronic toxicity of chemicals to fish. Results obtained using this TG are used to support risk assessment around the world. However, important limitations of this animal test are being recognized, including (1) the high numbers of fish used, (2) the relatively low-throughput, and (3) the lack of mechanistic information. In order to comply with the 3R principles, we are developing a non-animal testing strategy which includes both in vitro tests and in vivo whole organism alternative 120 hpf (hours post fertilization) ZFET (zebrafish embryo acute toxicity test) assays. One of the main research questions of this project is to what extent an assay development approach based on the AOP framework is capable of offering a mechanistic basis for selecting assays to develop an alternative testing strategy that allows the prediction of chronic FELS toxicity.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Stinckens Evelyn

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

Endocrine disruption is a major concern for the health of wildlife populations. Although many studies have shown reproductive impairment as a consequence of endocrine disruption in adult fish, knowledge of the consequences of endocrine disruption for vertebrate embryonic and larval development is scarce. The zebrafish embryo is an ideal model system to investigate the fundamental mechanisms of endocrine disruption. We will first describe the timing of the normal embryonic activation of the hormone synthesis machinery, as well as the hormone profiles, during the early stages of vertebrate development, which has never been done so far. Secondly, using well-described endocrine disrupting compounds, we will specifically disrupt these profiles and propose mechanisms linking the changed profiles to observed developmental effects. We will then validate the proposed mechanisms of toxicity using targeted disruption techniques, including knockout and morpholino knockdown. This project will offer the information that is needed for follow-up projects to develop assays to specifically assess the risk associated with exposure to different classes of EDCs on embryonic and larval development, allowing discrimination among ER and AR agonism and antagonism, as well as aromatase inhibition. Such assays would fit perfectly within both EU and USA regulatory priorities for screening and prioritizing potential EDCs.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: van Nuijs Alexander
• Co-promoter: Vergauwen Lucia
• Fellow: Periz Stanaćev Jelena

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

Environmental toxicology (named ecotoxicology further on) is by name a multidisciplinary field involving a wide span of scientifical domains These domains cover areas as biology (and several sub-disciplines thereof), ecology, biochemistry, toxicology, molecular genetics, industrial and process chemistry etc On top of that it touches the sociological field in terms of human and environmental hazard and risk, and even economy by setting environmental standards, thereby directly influencing industrial processes Water treatment technology and risk assessment are both important answers and tools offered to problems put forward by ecotoxicology Both offer and raise questions and problems to be answered It is my believe that ecotoxicology, in its broadest sense, holds the mother key in the solution but has yet to fully gain it.

Researcher(s)

• Promoter: Blust Ronny
• Co-promoter: Bols Peter
• Co-promoter: Covaci Adrian
• Co-promoter: De Wael Karolien
• Co-promoter: Geuens Luc
• Co-promoter: Janssens Koen
• Co-promoter: Knapen Dries
• Co-promoter: Lenaerts Silvia
• Co-promoter: Meire Patrick
• Co-promoter: Samson Roeland
• Fellow: Dardenne Freddy

Research team(s)

Project type(s)

• Research Project

Abstract

Pharmaceutical companies are obligated to perform an environmental risk assessment for each new drug that they launch on the market. The mandatory tests for potential endocrine disrupting compounds require a lot of time and laboratory animals. Therefore, the purpose of this study is to develop a zebrafish embryo test, which is not considered as animal test, that is capable of quickly detecting estrogenic properties of pharmaceuticals.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Van Cruchten Steven
• Fellow: Michiels Ellen

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

The zebrafish embryo is already being used for teratogenicity testing, i.e. in the Zebrafish Developmental Toxicity Assay (ZEDTA). However, in vitro data of our research group and in vivo data from other labs indicate that the zebrafish embryo shows no or low bioactivity. As such proteratogens, i.e. compounds that require bioactivation to exert their teratogenic potential, may be missed in the ZEDTA and lead to false negative results. Currently, rat exogenous metabolic activation system (MAS) is used to optimize the ZEDTA but it is controversial as it causes embryotoxicity by itself and its metabolic profile may be different than in man. The temperature of the co-incubation system may contribute to the observed embryotoxicity. Zebrafish embryos develop optimally between 26,5-28,5°C and do not tolerate the physiological temperature of rat MAS (38-39°C). Therefore, 32°C is often used in the coincubation system as a compromise. However, very recently we assessed temperature effects on zebrafish embryonic development and observed that 32,5°C causes embryotoxicty. Therefore, the aim of this research project is to develop a novel coincubation system (MAS) that functions at a non-embryotoxic temperature. Instead of rat MAS, we will evaluate in a first phase the bioactivity and embryotoxicity of human MAS (to obtain a human relevant metabolic profile) at different temperatures and of zebrafish MAS at 28,5°C (physiological condition for embryonic development). Regarding bioactivity, we will focus on xenobiotic metabolizing CYP families (i.e. CYP 1-3) and limit ourselves to fluorogenic substrates that are relevant to man and covering approx. 95% of human xenobiotic metabolism. Metabolite concentrations will be determined in the supernatans over-time by detection of the fluorescent signal. In a second phase we will evaluate biotransformation in the ZEDTA in presence and absence (controls) of hMAS and zMAS. This will be achieved by exposing early zebrafish embryos to the same substrates of the first phase. For the co-incubation, we will select the optimal temperature from the first phase. Metabolite concentrations will be determined over-time in the embryo and in the supernatans by detection of the fluorescent signal.

Researcher(s)

• Promoter: Van Cruchten Steven
• Co-promoter: Knapen Dries
• Fellow: Pype Casper

Research team(s)

• Comparative Perinatal Development (CoPeD)

Project website

Project type(s)

• Research Project

Abstract

Thyroid hormones (THs) play a crucial role in development. At present, experimental studies on the cellular and molecular mechanisms underlying TH-dependent development have mainly concentrated on the later stages of development, while the role of THs during early development is less clear. The objective of this study is to further elucidate the role of THs in vertebrate embryonic development using zebrafish embryos.

Researcher(s)

• Promoter: Hagenaars An
• Promoter: Knapen Dries

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand the Federal Public Service. UA provides the Federal Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Blust Ronny

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

Zebrafish (Danio rerio) are commonly used in drug development because of its advantages. As zebrafish are small, only little compound is needed compared to mammals. Furthermore, the expenses for the maintenance of the fish stock are limited and the fish show a high fecundity throughout the year. Moreover, the externally fertilised eggs develop in a similar way as higher vertebrate species, including humans. Because of these advantages, zebrafish are nowadays being used for screening new drugs for their teratogenic potential in the Zebrafish Teratogenicity Test (ZTT). However, optimal study conditions aren't available, indicating the need for further optimalisation of the test before it can be used as a valid screening model. Therefore, we will investigate the use of human- and zebrafish-derived liver microsomes in order to optimize the biotransformation of compounds.

Researcher(s)

• Promoter: Van Cruchten Steven
• Co-promoter: Knapen Dries
• Fellow: Pype Casper

Research team(s)

• Comparative Perinatal Development (CoPeD)

Project type(s)

• Research Project

Abstract

The main objective of this project is to use a mechanistic framework to develop and propose a high-throughput tiered-testing strategy for screening and prioritizing chemicals for FELS testing (OECD 210). The main objective can be divided into four parts: 1) Establish a database of toxicologically relevant FELS-specific AOPs, identify molecular initiating events and subsequent intermediate responses resulting into the apical outcome of interest 2) Propose Tier 1 in vitro screening toolbox to test for AOP-specific events and responses predictive for FELS chronic toxicity. 3) Propose Tier 2 whole-organism ZFET assays to test for AOP-specific events and responses predictive for FELS chronic toxicity and assess the potential of a ZFET molecular screening tool to predict cellular, organ and/or organism responses giving rise to FELS chronic toxicity. 4) Offering a proposal for implementation of a tiered-testing strategy in EU regulation. Assessment of usefulness and applicability of tiered testing strategy for global scientific and regulatory community.

Researcher(s)

• Promoter: Knapen Dries
• Co-promoter: Blust Ronny

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

The aim of this project is to develop a next generation sequencing (NGS) platform to advance in a collaborative way biological and medical research within the Antwerp research community. The consortium involves more than 16 research groups in various disciplines of medicine, biology and biomedical informatics. The goals are to identify new genes and mutations in various rare Mendelian disorders, to achieve more insights in the genetic causes of cancer and to unravel more precisely the genetic determinants of infectious diseases. This new knowledge will improve both the diagnosis and management of these human diseases. The project will also focus on the interaction between environment and genes. More specifically, the effect of environmental stressors on genetic variation in aquatic organisms, the effect of teratogenic factors on embryonic development in vertebrates and the effects of environmental conditions on growth in maize and Arabidopsis lines will be studied. The analysis of the large amount of genomic and transcriptomic data, generated by the various research groups, will be coordinated by the recently founded UZA/UA bioinformatics group Biomina

Researcher(s)

• Promoter: Mortier Geert
• Co-promoter: Beemster Gerrit
• Co-promoter: Blust Ronny
• Co-promoter: Goossens Herman
• Co-promoter: Knapen Dries
• Co-promoter: Laukens Kris
• Co-promoter: Peeters Marc
• Co-promoter: Van Hul Wim
• Co-promoter: Vrints Christiaan

Research team(s)

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand UGent. UA provides UGent research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Knapen Dries

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

Teratogenic chemicals are prioritized under the EU REACH legislation. Within this framework there is a need for routine testing tools to investigate the mechanistic basis of teratogenicity and to determine whether a substance has teratogenic potential. It has become clear that not only genetic factors (DNA nucleotide sequence) but also epigenetic factors such as DNA methylation, regulating gene behaviour, play a crucial role in teratogenicity. During vertebrate early embryonic development a vital epigenetic reprogramming event takes place (the sequential demethylation and de novo remethylation of the embryonic genome). The extent to which disturbance of methylation mechanisms during embryonic stages is involved in the development of teratogenic effects is still unclear and will be the subject of this study. This project will use the zebrafish embryo, which is already an established test system for the study of developmental effects, as an alternative to using mammals for the study of the role of epigenetic factors in teratogenicity. We aim to achieve two goals: first, we will determine to what extent DNA methylation changes are responsible for transcription changes involved in teratogenicity. Secondly, we will identify and confirm key genes and pathways involved in teratogenicity based on the integration of the molecular data with developmental parameters. Zebrafish embryos will be exposed to different concentrations of chemicals with known teratogenic mode of action during different stages of embryonic development, either during or after the de novo remethylation event. The embryos will be monitored individually until hatching. A large set of developmental parameters will be scored (e.g. heart rate and morphological malformations of body shape, somites and tail). Additionally, after pre and post de novo methylation exposure, RNA and DNA will be extracted which will be used in gene expression and DNA methylation microarray analyses. Based on these microarray data we will establish to what extent differential gene expression that is directly involved in teratogenicity is determined by differences in methylation status. Finally, we will statistically link these molecular data with the observed developmental effects. Key genes will thus be identified which are linked to specific developmental abnormalities. The selected key genes will be confirmed by both bisulfite sequencing (gene specific DNA methylation status) and real-time PCR (gene specific mRNA levels). Although a few previously published studies focused on general methylation patterning in zebrafish, we would be the first to study methylation dynamics in zebrafish embryos in detail on a genome wide scale, linking such data to classical gene expression data. Advancing the zebrafish embryo as an alternative test system for epigenomics research will pave the way for its application in several areas of research including the development of a classifier able to identify teratogenic compounds and the identification of targets for disease prevention or therapy.

Researcher(s)

• Promoter: Knapen Dries

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand KULeuven. UA provides KULeuven research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Knapen Dries

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

The project aims to gain mechanistic insight in the mode of action of radiation induced stress responses in Lemna minor to different radiation types at the molecular level. The responses will be studied in a time and dose resolved manner and compared to more classic development and growth related endpoints.

Researcher(s)

• Promoter: Blust Ronny
• Co-promoter: Knapen Dries

Research team(s)

Project type(s)

• Research Project

Abstract

A disturbed maternal metabolism may induce disappointing fertility and may jeopardize the offspring's health. Only recently, the importance of the early developmental stages in life has gained scientific attention in the study of the pathogenesis of subfertility. This project focuses on the metabolic and (epi)genetic consequences of long-term elevated non-esterified fatty acid serum concentrations in the dam on folliculogenesis, oocyte developmental competence and embryo quality.

Researcher(s)

• Promoter: Leroy Jo
• Co-promoter: Bols Peter
• Co-promoter: Knapen Dries

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand the Federal Public Service. UA provides the Federal Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Bols Peter
• Co-promoter: De Coen Wim
• Co-promoter: Knapen Dries
• Co-promoter: Leroy Jo

Research team(s)

• Veterinary physiology and biochemistry

Project type(s)

• Research Project

Abstract

The central aim of the proposed research project is the development of microarray derived molecular biomarkers for micro pollutants in the common carp (Cyprinus carpio) and validation of the selected set of biomarker genes under complex environmental relevant conditions. In order to be valuable in environmental risk evaluation the biomarker gene set has to meet several criteria.

Researcher(s)

• Promoter: Bervoets Lieven
• Co-promoter: Covaci Adrian
• Co-promoter: Jorens Philippe
• Co-promoter: Knapen Dries
• Co-promoter: Van der Ven Karlijn

Research team(s)

Project type(s)

• Research Project

Abstract

The overall aim of the study is to determine the role of THs in embryonic development in zebrafish, and vertebrates in general, prior to the onset of embryonic thyroid gland activity. More specifically we want to show how changes in intracellular T3 availability as a result of knockdown of both activating Ds influences major developmental processes such as gastrulation, neurulation and organogenesis.

Researcher(s)

• Promoter: Blust Ronny
• Co-promoter: Knapen Dries

Research team(s)

Project type(s)

• Research Project

Abstract

In the framework of this project we want to perform a comparative study of metal regulation, compartmentalisation and toxicity in the genetically well characterised zebrafish, Danio rerio, for two essential (copper and zinc) and one nonessential (cadmium) metals. We want to determine the similarities and differences in metal handling and resulting responses after exposure under three physiologically different conditions.

Researcher(s)

• Promoter: Blust Ronny
• Co-promoter: De Coen Wim
• Co-promoter: Knapen Dries
• Co-promoter: Witters Erwin

Research team(s)

Project type(s)

• Research Project

Abstract

Aquatic organisms are constantly being exposed to changes in their environment. These changes comprise both natural fluctuations (such as changes in environmental temperature) as well as anthropogenic disturbances (such as chemical pollution). This PhD combines these 2 kinds of stressors, investigating the influence of environmental temperature on cadmum toxicity in zebrafish (Danio rerio). A wide set of analyses ranges from gene expression changes to changes in swimming performance.

Researcher(s)

• Promoter: Blust Ronny
• Co-promoter: Knapen Dries
• Fellow: Vergauwen Lucia

Research team(s)

Project type(s)

• Research Project

Abstract

The Biological water quality in Flanders is assessed applying the Belgian Biotic Index (BBI). The aim of this proposal is the development of a biodiversity chip (DNA-array) for the identification of benthic macro invertebrate communities. We will start with the characterization of some key taxa of the BBI. With the biodiversity chip it will possible to assess the water quality in a correct and faster way compared to the classical identification of the BBI.

Researcher(s)

• Promoter: Bervoets Lieven
• Co-promoter: Knapen Dries
• Co-promoter: Van der Ven Karlijn

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Blust Ronny
• Fellow: Knapen Dries

Research team(s)

Project type(s)

• Research Project

Abstract

In Flanders (Belgium), many fish species are declining at an alarming rate, several species have gone extinct in the last few decades, and many more risk the same fate. Water pollution and river management practices have reduced and extensively altered aquatic habitats. For many species, the number of populations as well as the number of individuals per population have decreased dramatically. Moreover, it seems very difficult for individuals to develop genetic adaptations to their polluted habitats, since adaptation through natural selection is a relatively slow process. Surprisingly, previous studies reveal that various species are capable of developing adaptations to changing environments at fast rates. Studying the occurence of genetic adaptations in natural fish populations inhabiting polluted streams can therefore be of great value to evaluate the consequences of human activities on aquatic ecosystems. This is of vital importance for setting up conservation strategies. This study aims to investigate whether populations of the gudgeon (Gobio gobio) have become genetically adapted to the heavy metals that occur in their habitats. Firstly, populations from a downstream Cd and Zn pollution gradient will be sampled by means of electrofishing. At each site, the levels of water pollution will be examined. The individuals' and populations' fitness will be compared using a number of fitness-parameters. Secondly, microsatellites, mitochondrial d-loop sequences and allozymes will be used to genetically characterise the populations. Correlations of frequencies of certain unique genotypes with the pollution gradient may be due to selection pressures of pollutants in the past. Furthermore, levels of gene flow between sample populations can be investigated. This information is needed since gene flow can affect the evolution of adaptations by causing outbreeding depressions. In a later stage, these data will be used to delineate conservation units. Since the current definition of conservation units only allows their application in undisturbed populations, our goal is to adjust for this situation, so that for all endangered populations and species conservation measures can be taken. To investigate if selection has led to new adaptive genetypes we will determine the nucleotide sequences of metallothionein (MT) genes. These proteins are believed to have a detoxifying effect on heavy metal pollution. Therefore, selection may have lead to the existence of new genotypes. Furthermore, expression of MT-genes will be studied by quantifying MT-mRNA's in different tissues. This will be related to measured MT-concentrations in these tissues. Using this approach, genetic adaptations can be demonstrated in a direct way. The combination of both research strategies will lead to new insights in the long-term impact of industrial river pollution on aquatic ecosystems, and will help optimize future conservation efforts.

Researcher(s)

• Promoter: Blust Ronny
• Fellow: Knapen Dries

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Blust Ronny
• Fellow: Knapen Dries

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Blust Ronny
• Fellow: Knapen Dries

Research team(s)

Project type(s)

• Research Project