High-throughput phenotyping of health biomarkers in Crassostrea gigas by magnetic resonance imaging

High-throughput phenotyping of shellfish’s traits constitutes a challenge due to the specificities of aquatic animals. Appropriate measuring tools have often to be developed or adapted, in order to continuously and automatically acquire data of biomarkers of interest. IMAGIGAS project aimed to explore a non-destructive and non-invasive approach by using magnetic resonance imaging (MRI) to monitor at high-throughput two biomarkers (body weight and temperature) of the pacific oyster, before and during infectious challenges by Ostreid Herpesvirus type 1 (OsHV-1). Pacific oysters and OsHV-1 suspension and contaminated seawater were produced at Ifremer facilities. The experiments were conducted in 2016-2017 by three staffs (Ifremer LGPMM, Irstea IRM Food, Universite de La Rochelle LIENSs) at PRISM platform of Irstea at Rennes who provided a Siemens Avanto 1,5 T MRI. One objective was to monitor body weight of numerous individuals. Protocols were inspired by previous Ifremer / Irstea collaborative works and allowed to increase the throughput of measure to 69 oysters every 45 minutes. The estimation of body weight is based on a relation established between the sum of pixels whose grey level is greater than a particular value in pictures taken by MRI and the weight of drained then lyophilized flesh of oysters measured by precision balance. Each development experiments were completed by application experiments with infection of oysters by OsHV-1 and measures of body weight.