The impacts of pollutants on freshwater and deep-sea marine fish

The deep sea is a sink for pollutants. 
Among marine fishes, those thriving in the deep sea are particularly exposed to pollutants as these tend to absorb on organic matter particles sinking to the bottom of the oceans. Few studies were carried out on these deep-sea species, yet they reveal organochlorine concentrations up to 500-time higher than in surface species.  These pollutants are known to accumulate in the liver and trigger the production of reactive oxygen species (ROS) which may damage cell constituants and lead to cell dysfunction.

PCB and DDT contamination threatens dee-sea fish. 
Our work demonstrates that OCs have become a major factor influencing the expression levels of antioxidant enzymes in the Roundnose Grenadier, a rattail species thriving down to 2500 meters (Lemaire et al., 2010).  This suggests that dee)sea fish may respond to the accumulationf of OCS in their liver by an increase in hepatic defense mechanisms.  Since obtaining and keeping live deep-sea fish specimens is virtually impossible, we apply the Precision-Cut Liver Slices technology to deep-sea fish species (Lemaire et al., 2012).  Liver slices are incubated in a culture medium and kept in hyperbaric chambers with pressure set at deep-sea values (5-15 MPA).  Results suggest that deep-sea fish liver cells respond to pollutants similarly to their shallow counterplarts, but that their response is strongly repressed by high hydrostatic pressure (Lemaire et al., 2011; 2016).

Are European eels affected by pollutants. 
Another species of interest is the eel Anguilla anguilla, a species migrating back and forth between the deep ocean and European rivers where they accumulate very high amounts of pollutants.  We investigate the possible role of brain and liver contamination with mercury, OCs, Aluminium, ... in the decline of this species (Bonnineau et al, 2016).

The crosstalk between pollutants and nutritional factors could affect the sensitivity of fish to pollution. 
In particular, we study the mechanisms through which some polyunsaturated fatty acids, abundant in fish tissue and associated to many positive health effects in animals, may protect fish (trout and zebrafish) cells against metal such mercury and cadmium.  For this we also use in vitro cell culture to investigate mechanisms at the cellular level as well as in vivo experimentation (Ferain et al., 2016).