Epigenetic and maternal effects of toxicants with different MOA in zebrafish (Danio rerio)

We all know that since the beginning of the 20th century, the industry is the driving force behind the introduction of new chemicals. A lot of these chemicals arrive in the environment, where they can cause harm. In the study of ecotoxicology, they try to unravel these impacts on humanity and biota by working out classical toxicity tests (acute and chronic) within one generation. Nevertheless, it becomes clear that effects aren’t necessarily expressed in exposed organisms. Studies have shown that some agents can result in genetic or developmental defects in the offspring or the F1 generation from an exposed gestating mother. These effects can be the result of natural selection, more specifically adaptation, where the genetic composition of the population changes. On the other hand, there exist several mechanisms that can in a reversible way induce heritable changes in gene function, without changing the DNA sequence. These mechanisms are called epigenetic. So, the ability of an external agent to induce a transgenerational effect requires stable chromosomal alterations or an epigenetic phenomenon.
In this research project I will take a look at the maternal and epigentic mechanisms by exposing zebrafish (Danio rerio) to several substances. A lot of different exposing strategies will be carried out, with the possibility for multigeneration experiments. The impact of the substance will be examined at several levels such as transcriptome, physiology and epigenetic. To analyse the first I will use microarray technology. The physiological parameters will also be examined, such as reproduction, morphological abnormalities, body weight and condition. Eventually the effects will be analysed and I will search for the underlying mechanisms who induce these effects. I will use several techniques, like whole mount in situ hybrisisation (for the localisation of the maternal mRNAs), miRNA microarray technology (for tracing miRNAs) and ChIP-on-Chip technology (for DNA methylation and histon modification). By working out all of these techniques, I can get a better overview of the impact of toxicants on organisms and I can conclude which are the underlying, epigenetic mechanisms involved. The ultimate aim is to obtain a better model for risk evaluation. For this, I will incorporate this essential part in the study of ecotoxicology.