Transcriptomic analysis of clam extra pallial fluids reveals immunity and cytoskeleton alterations in the first week of Brown Ring Disease development

Alexandra Rahmani (1) , Erwan Corre (2, 3) , Gaelle Richard (1) , Adeline Bidault (1) , Christophe Lambert (1) , Louisi Oliveira (4) , Cristiane Thompson (4) , Fabiano Thompson (4) , Vianney Pichereau (1) , Christine Paillard (1)

1 LEMAR - Laboratoire des Sciences de l'Environnement Marin (LEMAR)
2 SBR - Station biologique de Roscoff = Roscoff Marine Station
3 FR2424 - Fédération de recherche de Roscoff
4 UFRJ - Universidade Federal do Rio de Janeiro [Brasil] = Federal University of Rio de Janeiro [Brazil] = Université fédérale de Rio de Janeiro [Brésil]

The Brown Ring Disease is an infection caused by the bacterium Vibrio tapetis on the Manila clam Ruditapes philippinarum. The process of infection, in the extrapallial fluids (EPFs) of clams, involves alteration of immune functions, in particular on hemocytes which are the cells responsible of phagocytosis. Disorganization of the actincytoskeleton in infected clams is a part of what leads to this alteration. This study is the first transcriptomic approach based on collection of extrapallial fluids on living animals experimentally infected by V. tapetis. We performed differential gene expression analysis of EPFs in two experimental treatments (healthy-against infectedclams by V. tapetis), and showed the deregulation of 135 genes. In infected clams, a downregulation of transcripts implied in immune functions (lysosomal activity and complement- and lectin-dependent PRR pathways) was observed during infection. We also showed a deregulation of transcripts encoding proteins involved in the actin cytoskeleton organization such as an overexpression of beta 12-Thymosin (which is an actin sequestration protein) or a downregulation of proteins that closely interact with capping proteins such as Coactosin, that counteract action of capping proteins, or Profilin. We validated these transcriptomic results by cellular physiological analyses that showed a decrease of the lysosome amounts and the disorganization of actin cytoskeleton in infected hemocytes.

Mots clés: FSW; Filter Sterilized Seawater; ABP; Actin Binding Protein; BRD; Brown Ring Disease; EPF; Extrapallial Fluids; ACL

Domaines: Biodiversité et Ecologie

Alexandra Rahmani, Erwan Corre, Gaelle Richard, Adeline Bidault, Christophe Lambert, et al.. Transcriptomic analysis of clam extra pallial fluids reveals immunity and cytoskeleton alterations in the first week of Brown Ring Disease development. Fish and Shellfish Immunology, 2019, 93, pp.940-948. ⟨10.1016/j.fsi.2019.08.025⟩. ⟨hal-02409065⟩