Project description:Illumina RNA sequencing to assmeble a transcriptome for the oyster Ostrea lurida and identify genes signficantly differentially expressed among three populations of oysters that differ in their tolerance of low salinity. Our new transcripmotme provides an important genomic resource for future work in this species of conservation concern. Genes differentially expressed between oyster populations provide insight into mechanisms underlying different low salinity tolerances.
Project description:The European flat oyster (Ostrea edulis) production has suffered a severe decline in the last decades mostly due to bonamiosis disease. The responsible parasite, Bonamia ostreae, enters the oyster immune-effector cells, the haemocytes, causing their breakage and an acute inflammatory response frequently leading to oyster death. Here, we used an oyster immune-enriched oligo-microarray to understand the haemocyte response to B. ostreae using two different oyster stocks, naïve (NS) and long-term affected (AS), evaluated at three time points, 1 day post-challenge (dpc), 30 dpc and 90 dpc, using five biological replicates per condition. A total of 213 (134 up-, 79 down-regulated) and 538 (330 up-, 208 down-regulated) regulated genes (RGs) were detected in NS and AS stocks, respectively. AS oysters showed a remarkably higher response at 1 dpc when compared to NS (507 vs 86 RGs), while more RGs were found in NS at 90 dpc (127 vs 31 RGs in AS). No RGs were detected at 30 dpc, which suggests some kind of parasite latency during infection. Further, a total of 837 genes resulted differentially expressed (DE) when comparing NS and AS profiles. The stronger response of the AS stock at the early stage might be indicative of the process of selection for resistance. Genes related to extracellular matrix and proteases inhibitors, up-regulated in the AS oysters, and those related to histones, broadly down-regulated in NS, might have an important role during the infection process. A set of 24 candidate genes potentially related to B. ostreae resistance/susceptibility were identified and they should be further validated for selection programmes aimed to control this parasitosis.
