First epigenetic insights in the diatom Haslea ostrearia exposed to UVR and diuron

Orlane Bosson1, Romain Gastineau2, Jean-Luc Mouget1, Myriam Badawi1, Aurore Caruso1,  Pierre-François Cartron3

 

1 Laboratoire Mer Molécules Santé, Le Mans Université, 72000 Le Mans, France.

2 U. Szczecin, Szczecin, Poland

3 Équipe Apoptose et Progression Tumorale, Centre de Recherche en Cancérologie et Immunologie Nantes Angers (CRCINA), INSERM U1232, 44000 Nantes, France.

 

Keywords: diatom, diuron epigenetics, ultraviolet.

 

Abstract

It has long been known that pollutants' fate, in particular of plant protection chemicals, is to  accumulate in the oceans. For instance, diuron used in agriculture as weed killer but also as an antifouling compound against algae in ship hull, can be observed at a high concentration in coastal waters. In the French Atlantic coast, diuron concentration can reach up to 4 µg/L. Diuron inhibits photosynthesis by blocking electron transfer around photosystem II. It has therefore become important to know the impact that this pollutant can have on photosynthetic organisms, and more particularly on diatoms, which are the basis of most food chains in aquatic ecosystems. The study was therefore carried out on two pennate diatom species, Haslea ostrearia and Phaeodactylum tricornutum. Haslea ostrearia is known to product a blue pigment, name marennine, responsible for the greening of oyster gills in oyster ponds in Western France.

Phaeodactylum tricornutum has already been studied extensively, and has notably its genome already sequenced. First results have been obtained, after physiology and epigenetics studies. Indeed, a decrease in growth, with low concentration of diuron can be observed. Moreover, epigenetics tests (5mC and 5hmC) allow to reveal a global hypomethylation of genome of these two species when concentration of diuron increasing.

Further studies are underway, on Haslea ostrearia. In fact, this diatom being able to realize sexual reproduction, it is so possible for this species to study transgenerational effects. This phenomenon is not possible for many other species like Phaeodactylum tricornutum. Epigenetics tests will therefore be again realized on different diatom’s generation in order to know if epigenetics markers are transmitted of transgenerational manner. In addition to that, genome sequencing and marker sequencing will be studied, in order to compare modifications involved by diuron and other parameters studied on Haslea ostrearia.