Impact of city light pollution on fish reproduction and pituitary gonadotrope plasticity
1 Purpose
Understanding the mechanistic pathway synchronizing gametogenesis with environmental conditions favorable for offspring survival is fundamental for biodiversity conservation. Accumulating evidence shows that light pollution from artificial light at night (ALAN) is dysregulating major physiological functions in various species, including reproduction in teleost fishes. In this project, we aim to understand how ALAN affects seasonal reproduction in fishes and the underlying biological mechanisms that control it. In fishes as in all vertebrates, reproduction is controlled through the brain – pituitary – gonad axis, in which Fsh and Lh gonadotropes in the pituitary play an essential role in maintaining reproductive homeostasis. We will therefore study (1) the impact of ALAN on fish reproduction and (2) the role Lh and Fsh cells play in the synchronization of reproductive events with light conditions.
2 Distress
Low to mild. We will use light regimes which are regularly used in the aquaculture industry to manipulate sexual maturation without any noticeable harm to the fish. We will also develop two new transgenic lines in which specific cells can be ablated using techniques previously used in model fish, targeting only a small number of cells to limit impact on fish welfare. To induce cell ablation, we will use bathing for chemical administration which is a commonly used technique for this approach. The stress protocol we will use to determine oxygen consumption in fishes is regularly used in other fish species and is not harmful as fish recover in only few minutes. Also, for analysis, repeated sperm sampling will be performed with no impact on fish health.
3 Expected benefit
If successful, these experiments will provide a lot of information on the role gonadotrope cells play in seasonal regulation of reproductive events and how they are affected by ALAN.
4 Number of animals, and what kind
We plan to use up to a total of 711 adult medaka fish in our experiments.
5 How to adhere to 3R
We need to use animal models in our research, as we are investigating a complex physiological system (control of reproduction) involving several organs (brain, pituitary, gonads). Therefore, we argue that ex vivo experiments are not suitable to obtain our aim. In addition, we have reduced the number of used animals to the minimum in order to get still relevant information and will collect many tissues from those fish to expand the amount of data collected from these experiments. We will also closely monitor fish health to take immediate action if a procedure induces discomfort or pain to the animals.
Understanding the mechanistic pathway synchronizing gametogenesis with environmental conditions favorable for offspring survival is fundamental for biodiversity conservation. Accumulating evidence shows that light pollution from artificial light at night (ALAN) is dysregulating major physiological functions in various species, including reproduction in teleost fishes. In this project, we aim to understand how ALAN affects seasonal reproduction in fishes and the underlying biological mechanisms that control it. In fishes as in all vertebrates, reproduction is controlled through the brain – pituitary – gonad axis, in which Fsh and Lh gonadotropes in the pituitary play an essential role in maintaining reproductive homeostasis. We will therefore study (1) the impact of ALAN on fish reproduction and (2) the role Lh and Fsh cells play in the synchronization of reproductive events with light conditions.
2 Distress
Low to mild. We will use light regimes which are regularly used in the aquaculture industry to manipulate sexual maturation without any noticeable harm to the fish. We will also develop two new transgenic lines in which specific cells can be ablated using techniques previously used in model fish, targeting only a small number of cells to limit impact on fish welfare. To induce cell ablation, we will use bathing for chemical administration which is a commonly used technique for this approach. The stress protocol we will use to determine oxygen consumption in fishes is regularly used in other fish species and is not harmful as fish recover in only few minutes. Also, for analysis, repeated sperm sampling will be performed with no impact on fish health.
3 Expected benefit
If successful, these experiments will provide a lot of information on the role gonadotrope cells play in seasonal regulation of reproductive events and how they are affected by ALAN.
4 Number of animals, and what kind
We plan to use up to a total of 711 adult medaka fish in our experiments.
5 How to adhere to 3R
We need to use animal models in our research, as we are investigating a complex physiological system (control of reproduction) involving several organs (brain, pituitary, gonads). Therefore, we argue that ex vivo experiments are not suitable to obtain our aim. In addition, we have reduced the number of used animals to the minimum in order to get still relevant information and will collect many tissues from those fish to expand the amount of data collected from these experiments. We will also closely monitor fish health to take immediate action if a procedure induces discomfort or pain to the animals.