Ecobarotoxicology of persistent organic pollutants in deep-sea fish


***Wednesday, September 5, 2012
Redfield Auditorium - 12:00 Noon
Dr. Benjamin Lemaire
Postdoc Fellow, Biology

Although remote from sources of emission, the deep-sea act as a global sink for persistent organic pollutants (POPs) such as organochlorine pesticides and polycyclic aromatic hydrocarbons. Consequently, top-predator deep-sea fish are highly contaminated. The toxicity associated is largely unknown, due to the absence of a culture model allowing dose-response studies on living cells of these fish.

During my thesis, I focused on the deep-sea fish Coryphaenoides rupestris (bathy-demersal) as a preliminar biochemical study on liver samples suggested that POPs could exert toxicity by oxidative stress in this fish. I planned to validate an in vitro culture system to allow hyperbaric exposures of C. rupestris liver cells to POPs at levels of hydrostatic pressure (HP) typical of the deep-sea. The technology of precision-cut liver slices (PCLS) was selected for that purpose. Exposure to POPs at various HP levels were first conducted with PCLS of two shallow fish (Salmo salar and Dicentrarchus labrax), as to validate the methodology and collect a set of data to be compared with the deep-sea fish. The model was then successfully transposed to C. rupestris individuals collected in a Norwegian fjord (PCLS were generated on the ship). In each species, high HP strikingly affected the inducibility of the detoxification enzyme cytochrome P4501A. Other parameters studied were also impacted by high HP in a species-dependent manner. The validation of PCLS of deep-sea fish paves the way for understanding POP effects in this remote fauna.

I also plan to expose some results of on-going investigations at WHOI. This time, I focus on the deep-sea fish Coryphaenoides armatus (abyssal). Cloning-sequencing of the coding-sequence of detoxification enzymes and subsequent in silico studies are conducted to understand the molecular features allowing these enzymes to function under the constraints of the deep-sea (i.e., very high HP).