Apoptosis phenotype and gene expression in response to the parasite Perkinsus marinus in the eastern oyster, Crassotrea virginica

Authors: ROBERTS, ERIN - University Of Rhode Island; Proestou, Dina; WICKFORS, GARY - National Oceanic & Atmospheric Administration (NOAA); BEN-HORIN, TAL - University Of Rhode Island; Markey Lundgren, Kathryn; GOMEZ-CHIARRI, MARTA - University Of Rhode Island

Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/31/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Population levels and industry sustainability of the eastern oyster, Crassostrea virginica, have been negatively affected by the emergence of Dermo disease, caused by the alveolate parasite Perkinsus marinus. Apoptosis is a critical oyster immune defense response to infection playing a role in the pathogenesis of Dermo disease. Apoptosis regulation in oysters involves several gene families of inhibitors, Inhibitors of Apoptosis (IAP) and GTPase of the Immune Associated Proteins (GIMAP), with expanded copy number and varied transcriptional responses. This project investigated whether apoptosis phenotype and expression of apoptosis inhibitors varies in oysters from families with varying levels of disease resistance to Dermo, and whether apoptosis phenotype and gene expression can be used as markers of disease resistance. Juvenile oysters from selected families (A, B, D, E, J, L) with varying levels of disease resistance, as predicted by Estimated Breeding Values (EBV’s) for survival in the Chesapeake Bay, were challenged with P. marinus. At days 7 and 50 post-challenge, disease phenotype was assessed via oyster survival and infection load, oyster hemocyte apoptosis phenotype via flow cytometry, and gene expression via sequencing of transcriptomes. Analysis of percentages of apoptotic hemocytes revealed significant differences between oyster families in the relative abundance of granular and agranular live apoptotic hemocytes at day 7 (Figure 1). Within family, only Family A revealed significant differences between control and treated oysters in the percentage of apoptotic granular hemocytes. No clear relationship between oyster survival 50 days after challenge and percent of apoptotic hemocytes on day 7 was detected. A significant decrease in the percentage of apoptotic hemocytes may contribute to oyster mortality from Dermo disease in susceptible individuals. Correlation of apoptosis phenotype and GIMAP and IAP gene expression with survival and parasite load data will allow to determine the potential for apoptosis phenotype and gene expression to be additional markers of differential resistance between bred families.