Genetic and environmental basis of aggression in zebrafish

Aggression is an important behaviour that animals use to protect themselves and their offspring and to acquire resources such as food or territory. Excessive human aggression is often problematic and is a common symptom of several psychiatric diseases including attention-deficit/hyperactivity disorder (ADHD), conduct disorder and schizophrenia. The reason why some people are more aggressive than others is thought to be due to individual differences in genetic makeup and the environments they experience. In fact, several recent studies have linked individual genes to aggression. People with mutations in these genes are more likely to be aggressive than the general population, but the changes to brain function which lead to this increased aggression are not known. The zebrafish has emerged as an important model for biomedical research because of its well- characterised behavioural repertoire and the ease of manipulating its genes. In this research project called: Analysis of the genetic and environmental basis of aggression using zebrafish I will use zebrafish to investigate the role of selected genes in aggression as well as the effect of selective breeding on aggression. For this, I will create novel stable mutant lines that lack the function of these genes as well as a novel artificial selection line for aggressive behaviour. I will then examine the consequences of these interventions by measuring behaviour with a special focus on whether these zebrafish are more aggressive than normal fish. In the brain I will also measure the levels of neurotransmitters and genes/proteins related to neurotransmitter production, degradation or transport. Neurotransmitters, especially serotonin, can promote aggression suggesting that these signals may be altered in the novel lines. Finally I will assess whether living environment (tank setup) will change zebrafish aggression levels. For this, mutant, selectively-bred and control zebrafish will be kept in differentially equipped and sized tanks before their behaviour and neurotransmitter levels will be analysed. I hypothesize that these novel zebrafish lines will be more aggressive than control animals, and that their brains will show unique neurotransmitter changes depending on the living environment. This project will be performed in the lab of Dr Norton at the University of Leicester, because he is a leading expert in aggression and zebrafish research with access to all the techniques necessary to complete this project. I expect that the novel zebrafish lines created during this project will provide further insights into how the brain controls aggression with the potential to develop better treatments for this behaviour in the future.