Karen Smeets

Karen Smeets
Hasselt University · Centre for Environmental Sciences (CMK)

About

97
Publications
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5,332
Citations

Publications

Publications (97)
Article
Full-text available
Many species‐rich ecological communities emerge from adaptive radiation events. Yet the effects of adaptive radiation on community assembly remain poorly understood. Here, we explore the well‐documented radiations of African cichlid fishes and their interactions with the flatworm gill parasites Cichlidogyrus spp., including 10,529 reported infectio...
Article
A substantial portion of biodiversity has evolved through adaptive radiation. However, the effects of explosive speciation on species interactions remain poorly understood. Metazoan parasites infecting radiating host lineages could improve our knowledge because of their intimate host relationships. Yet limited molecular, phenotypic and ecological d...
Article
During colonial times, Nile tilapia Oreochromis niloticus (Linnaeus, 1758) was introduced into non‐native parts of the Congo Basin (Democratic Republic of the Congo, DRC) for the first time. Currently, it is the most farmed cichlid in the DRC, and is present throughout the Congo Basin. Although Nile tilapia has been reported as an invasive species,...
Article
Background/Aim Glyphosate, a broad-spectrum herbicide, and its main metabolite aminomethylphosphonic acid (AMPA) are persistent in the environment. Studies showed associations between glyphosate or AMPA exposure and several adverse cellular processes, including metabolic alterations and oxidative stress. Objective To determine the association betw...
Article
Dactylogyridae is one of the most studied families of parasitic flatworms with more than 1000 species and 166 genera described to date including ecto- and endoparasites. Dactylogyrid monogeneans were suggested as model organisms for host-parasite macroevolutionary and biogeographical studies due to the scientific and economic importance of some of...
Article
In a polluted environment, metals are present as complex mixtures. As a result, organisms are exposed to different metals at the same time, which affects both metal-specific as well as overall toxicity. Detailed information about the molecular mechanisms underlying the adverse effects of combined exposures remains limited in terms of different life...
Preprint
Full-text available
Many species-rich ecological communities result from adaptive radiation events. The effects of these explosive speciation events on community assembly remain poorly understood. Here, we explore the well-documented radiations of African cichlid fishes and interactions with their flatworm gill parasites (Cichlidogyrus spp.) including 10529 reported i...
Preprint
Full-text available
Dactylogyridae are one of the most studied families of parasitic flatworms with more than 1000 species and 166 genera described to date including ecto- and endoparasites. Dactylogyrid monogeneans were suggested as model organisms for host-parasite macroevolutionary and biogeographical studies due to the scientific and economic importance of some of...
Article
Full-text available
Species interactions are a key aspect of evolutionary biology. Parasites, specifically, are drivers of the evolution of species communities and impact biosecurity and public health. However, when using interaction networks for evolutionary studies, interdependencies between distantly related species in these networks are shaped by ancient and compl...
Article
Full-text available
Many nominal species of microscopic animals traditionally fitting the ‘everything is everywhere’ paradigm have been revealed to be complexes of cryptic species. Here, we explore species diversity within the micrometazoan flatworm Gyratrix hermaphroditus—unique among meiofauna because of its global occurrence in a wide variety of brackish, freshwate...
Article
Full-text available
A strict coordination between pro- and antioxidative molecules is needed for normal animal physiology, although their exact function and dynamics during regeneration and development remains largely unknown. Via in vivo imaging, we were able to locate and discriminate between reactive oxygen species (ROS) in real-time during different physiological...
Article
The taxon Koinocystididae is the third most species-rich family within Eukalyptorhynchia. However, its diversity and phylogeny have been largely neglected in former studies. We introduce three new genera and twelve new species of Koinocystididae including Simplexcystis asymmetrica gen. n. sp. n., Galapagetula cubensis sp. n., eight species of Reinh...
Preprint
Full-text available
A substantial portion of global biodiversity evolved through adaptive radiation. However, the effects of explosive speciation on species interactions remain poorly understood. Metazoan parasites infecting radiating host lineages could improve our knowledge because of the intimate host-parasite relationships. Yet limited molecular, phenotypic, and e...
Article
Full-text available
Despite extensive research on molecular pathways controlling the process of regeneration in model organisms, little is known about the actual initiation signals necessary to induce regeneration. Recently, the activation of ERK signaling has been shown to be required to initiate regeneration in planarians. However, how ERK signaling is activated rem...
Article
Silver nanoparticles (AgNPs) are widely incorporated in household, consumer and medical products. Their unintentional release via wastewaters raises concerns on their environmental impact, particularly for aquatic organisms and their associated bacterial communities. It is known that the microbiome plays an important role in its host’s health and p...
Article
Full-text available
Given the global decline of many invertebrate food resources, it is fundamental to understand the dietary requirements of insectivores. We give new insights into the functional relationship between the spatial habitat use, food availability, and diet of a crepuscular aerial insectivore, the European Nightjar (Caprimulgus europaeus) by relating spat...
Article
The first three mitochondrial (mt) genomes of endosymbiotic turbellarian flatworms are characterised for the rhabdocoels Graffilla buccinicola, Syndesmis echinorum and S. kurakaikina. Interspecific comparison of the three newly obtained sequences and the only previously characterised rhabdocoel, the free-living species Bothromesostoma personatum, r...
Article
Pluripotent stem cells hold great potential for regenerative medicine. Increased replication and division, such is the case during regeneration, concomitantly increases the risk of adverse outcomes through the acquisition of mutations. Seeking for driving mechanisms of such outcomes, we challenged a pluripotent stem cell system during the tightly c...
Article
Full-text available
Nutrition during early childhood is linked to metabolic programming. We hypothesized that breastfeeding has long-term consequences on the energy metabolism exemplified by mitochondrial DNA (mtDNA). As part of the third cycle of the Flemish Environment and Health Study (FLEHSIII) cohort, 303 adolescents aged 14–15 years were included. We associated...
Preprint
Full-text available
Despite the extensive research on molecular pathways controlling the process of regeneration in planarians and other regeneration models, little is known about the actual initiation signals necessary to induce regeneration. Previously the involvement of ROS, EGFR and MAPK/ERK has been demonstrated during planarian regeneration, however the exact in...
Article
Silver nanoparticles (AgNPs) belong to the most commercialized nanomaterials, used in both consumer products and medical applications. Despite its omnipresence, in-depth knowledge on the potential toxicity of nanosilver is still lacking, especially for developing organisms. Research on vertebrates is limited due to ethical concerns, and planarians...
Article
Full-text available
Planarians have been long known for their regenerative ability, which hinges on pluripotency. Recently, however, the planarian model has been successfully established for routine toxicological screens aimed to assess over-proliferation, mutagenicity and tumorigenesis. In this study, we focused on planarian tumor suppressor genes (TSGs) and their ro...
Article
Full-text available
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
Article
Full-text available
When complementary resources are required for an optimal life cycle, most animals need to move between different habitats. However, the level of connectivity between resources can vary and, hence, influence individuals' behaviour. We show that landscape composition and configuration affect the connectivity between breeding (heathlands) and foraging...
Article
Aiming to in vivo characterise the responses of pluripotent stem cells and regenerative tissues to carcinogenic stress, we employed the highly regenerative organism Schmidtea mediterranea. Its broad regenerative capacities are attributable to a large pool of pluripotent stem cells, which are considered key players in the lower vulnerability towards...
Article
Full-text available
One of the major challenges in the development of alternative carcinogenicity assays is the prediction of non-genotoxic carcinogens. The variety of non-genotoxic cancer pathways complicates the search for reliable parameters expressing their carcinogenicity. As non-genotoxic and genotoxic carcinogens have different cancer risks, the objective of th...
Article
Accurate and reliable carcinogenicity assays are imperative, as cancer risks are directly associated with the type and potency of a compound. A challenge for the development of alternative test methods is the prediction of non-genotoxic carcinogens, which entail different assessments of human cancer risk. The variety of non-genotoxic cancer pathway...
Article
Full-text available
Flatworms are acknowledged for their stem cell system and consecutive regenerative ability. From a toxicological point of view, stem cells are an interesting object of study, as they enable organisms to cope with stress. Previous research on the freshwater flatworm and model organism Schmidtea mediterranea revealed a substantially higher general (s...
Article
A delicate balance exists between the process of carcinogenesis and tissue regeneration. A number of malignant tumours are considered the outcome of an impaired or incomplete regeneration process, resulting in persistently dividing cells. Regeneration-competent tissues and animals are able to prevent and counteract growth abnormalities and seem to...
Article
Full-text available
Background: Telomere length and mitochondrial DNA (mtDNA) content are markers of aging and aging-related diseases. There is inconclusive evidence concerning the mechanistic effects of airborne particulate matter (PM) exposure on biomolecular markers of ageing OBJECTIVE: The present study examines the association between short- and long-term PM exp...
Article
The importance of nerve-derived signalling for correct regeneration has been the topic of research for more than a hundred years, but we are just beginning to identify the underlying molecular pathways of this process. Within the current review, we attempt to provide an extensive overview of the neural influences during early and late phases of bot...
Article
Full-text available
Flatworms possess adult pluripotent stem cells whose dynamics can easily be experimentally assessed in vivo. This feature provides the unique opportunity to be used in a pharmacological context to test the safety of chemicals. The objective of this study was to develop and assess the applicability of an alternative in vivo test with a low-level org...
Article
Full-text available
Recent research highlighted the impact of ROS as upstream regulators of tissue regeneration. We investigated their role and targeted processes during the regeneration of different body structures using the planarian Schmidtea mediterranea, an organism capable of regenerating its entire body, including its brain. The amputation of head and tail comp...
Data
Supplementary Figure 1: Quantification of the ROS-induced fluorescence is presented as well as figures showing the lack of autofluorescence and visualization of ROS production in neuronal-like structures. Supplementary Figure 2: The ratio of mitochondrial DNA versus nuclear DNA is presented. Supplementary Figure 3: Shows the visualization and quant...
Article
A delicate balance exists between the process of carcinogenesis and tissue regeneration. A number of malignant tumours are considered the outcome of an impaired or incomplete regeneration process, resulting in persistently dividing cells. Regeneration-competent tissues and animals are able to prevent and counteract growth abnormalities and seem to...
Article
Stem cells or undifferentiated cells can cope more easily with external stresses. To evaluate the impact of toxic compounds on stem cell dynamics in vivo, in relation to other biological responses, we use the carcinogenic element cadmium and the regenerating model organism Macrostomum lignano. Through both BrdU and anti-histone H3 immunostainings,...
Article
Cadmium (Cd2+) induces oxidative stress that ultimately defines cell fate and pathology. Mitochondria are the main energy-producing organelles in mammalian cells, but they also have a central role in formation of reactive oxygen species, cell injury, and death signaling. As the kidney is the major target in Cd2+ toxicity, the roles of oxidative sig...
Article
Full-text available
Reverse transcription-quantitative PCR (RT-qPCR) has been widely adopted to measure differences in mRNA levels; however, biological and technical variation strongly affects the accuracy of the reported differences. RT-qPCR specialists have warned that, unless researchers minimize this variability, they may report inaccurate differences and draw inc...
Article
Cadmium (Cd) is a toxic metal with a long half-life in biological systems. This half-life is partly as a result of metallothioneins (MTs), metal-binding proteins with a high affinity for Cd. The high retention properties of the kidneys reside in proximal tubular cells that possess transport mechanisms for Cd-MT uptake, ultimately leading to more Cd...
Article
To investigate hydrophobic test compounds in toxicological studies, solvents like dimethylsulfoxide (DMSO) are inevitable. However, using these solvents, the interpretation of test compound-induced responses can be biased. DMSO concentration guidelines are available, but are mostly based on acute exposures involving one specific toxicity endpoint....
Article
Full-text available
Two surveys of over 1,700 publications whose authors use quantitative real-time PCR (qPCR) reveal a lack of transparent and comprehensive reporting of essential technical information. Reporting standards are significantly improved in publications that cite the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guid...
Article
Full-text available
Two surveys of over 1,700 publications whose authors use quantitative real-time PCR (qPCR) reveal a lack of transparent and comprehensive reporting of essential technical information. Reporting standards are significantly improved in publications that cite the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guid...
Article
Full-text available
Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants that are formed in combustion processes. At the cellular level, exposure to PAHs causes oxidative stress and/or some of it congeners bind to DNA, which may interact with mitochondrial function. However, the influence of these pollutants on mitochondrial DNA (mtDNA) cont...
Article
Full-text available
Over the years, anthropogenic factors have led to cadmium (Cd) accumulation in the environment causing various health problems in humans. Although Cd is not a Fenton-like metal, it induces oxidative stress in various animal models via indirect mechanisms. The degree of Cd-induced oxidative stress depends on the dose, duration and frequency of Cd ex...
Article
The hypothesis that MAPK (mitogen-activated protein kinase) signalling is important in plant defences against metal stress has become accepted in recent years. To test the role of OXI1 (oxidative signal inducible kinase) in metal-induced oxidative signalling, the responses of oxi1 knock-out lines to environmentally realistic cadmium (Cd) and copper...
Article
This study aims to investigate the colonization of poplar by the endophyte Pseudomonas putida W619 and its capacity to promote plant growth. Poplar cuttings were inoculated with P. putida W619 (wild-type or gfp-labelled). The colonization of both strains was investigated and morphological, physiological and biochemical parameters were analyzed to e...
Article
Full-text available
The planarian Schmidtea mediterranea is a well-studied model organism for developmental research, because of its stem cell system. This characteristic also provides a unique opportunity to study stress management and the effect of stress on stem cells. In this study, we characterised the stress signature at different levels of biological organizati...
Article
Full-text available
Background: Studies emphasize the importance of particulate matter (PM) in the formation of reactive oxygen species and inflammation. We hypothesized that these processes can influence mitochondrial function of the placenta and fetus. Objective: We investigated the influence of PM10 exposure during pregnancy on the mitochondrial DNA content (mtDNA...
Article
Cholesterol synthesis and transport in oligodendrocytes are essential for optimal myelination and remyelination in pathological conditions such as multiple sclerosis. However, little is known about cholesterol homeostasis in the myelin-forming oligodendrocytes. Liver X receptors (LXRs) are nuclear oxysterol receptors that regulate genes involved in...
Article
Recent studies have emphasized the importance of PM, and its associated metal components, in the formation of reactive oxygen species (ROS) and inflammation. Mitochondria are the major intracellular sources and primary targets of ROS. Mitochondrial DNA (mtDNA) is particularly vulnerable to ROS-induced damage, resulting in a higher mutation rate tha...
Article
The flatworm species Schmidtea mediterranea and Macrostomum lignano have become new and innovative model organisms in stem cell, regeneration and tissue homeostasis research. Because of their unique stem cell system, (lab) technical advantages and their phylogenetic position within the Metazoa, they are also ideal candidate model organisms for toxi...
Article
When aiming to evaluate the environmental impact of uranium contamination, it is important to unravel the mechanisms by which plants respond to uranium stress. As oxidative stress seems an important modulator under other heavy metal stress, this study aimed to investigate oxidative stress related responses in Arabidopsis thaliana exposed to uranium...