Long-term affected flat oyster (Ostrea edulis) haemocytes show differential gene expression profiles from naïve oysters in response to Bonamia ostreae

Abstract

European flat oyster (Ostrea edulis) production has suffered a severe decline due to bonamiosis. The responsible parasite enters in oyster haemocytes, causing an acute inflammatory response frequently leading to death. We used an immune-enriched oligo-microarray to understand the haemocyte response to Bonamia ostreae by comparing expression profiles between naïve (NS) and long-term affected (AS) populations along a time series (1 d, 30 d, 90 d). AS showed a much higher response just after challenge, which might be indicative of selection for resistance. No regulated genes were detected at 30 d in both populations while a notable reactivation was observed at 90 d, suggesting parasite latency during infection. Genes related to extracellular matrix and protease inhibitors, up-regulated in AS, and those related to histones, down-regulated in NS, might play an important role along the infection. Twenty-four candidate genes related to resistance should be further validated for selection programs aimed to control bonamiosis.

Phylogeography in an “oyster” shell provides first insights into the genetic structure of an extinct Ostrea edulis population

“…Because of the remote location combined with reduced water inflow and currents, pathogens and competitors like Bonamia ostreae and Magallana gigas appeared in the Limfjord later than at other locations in Europe 42,43 . Another hypothesis is based on the results of Ronza et al 44 : they showed that O. edulis has not developed any resistance to bonamiosis in the Limfjord yet. The presence of B. ostreae in the North Sea may therefore be a reason why the native oyster has not recolonized the Wadden Sea again 44 .…”

“…Another hypothesis is based on the results of Ronza et al 44 : they showed that O. edulis has not developed any resistance to bonamiosis in the Limfjord yet. The presence of B. ostreae in the North Sea may therefore be a reason why the native oyster has not recolonized the Wadden Sea again 44 . In the past, it has been observed that B. ostreae was eliminated during cold winters, while O. edulis was able to survive 45 .…”

Chromosome level reference genome for European flat oyster (Ostrea edulis L.)

“…Several studies have applied genetic and genomic tools to study O. edulis in the absence of a reference genome assembly. Such work has been strongly targeted towards understanding bonamiosis, either by identifying candidate quantitative trait loci (QTL) and genetic outliers linked to Bonamia resistance (Lallias et al, 2009; Harrang et al, 2015; Vera et al, 2019) or by studying gene expression responses to Bonamia infection (Pardo et al, 2016; Ronza et al, 2018). SNP genotyping arrays with low (Lapègue et al, 2014) and medium (Gutierrez et al, 2017) density have also been developed for genetics applications.…”

Host gene expression in wildlife disease: making sense of species‐level responses

“…While interspecific transcriptomic comparisons can be quite powerful (Evans, 2015), designs targeting intraspecific differences can also be used to address key questions in wildlife disease. These investigations are particularly informative when they contrast populations with varying historical pathogen exposure regimes: persistent exposure may drive divergence in gene expression, including gene regulation differences associated with the evolution of host resistance, which population‐level gene expression assays can dissect (Bonneaud et al, 2012; Campbell et al, 2018; Grogan, Cashins, et al, 2018; Ronza et al, 2018). Such approaches have been used to identify genes in exposed populations that are potential targets of selection for host resistance, even when the history of exposure is relatively brief in an evolutionary sense (i.e., decades).…”