- Marine Ecosystems and oRganisms reSEArch Lab
Fundamental Research : Control of gamete emission and associated behaviors in marine molluscs. Principal model: the cuttlefish (Sepia officinalis).
Three types of regulators are being studied: (1) neuropeptides associated with the triggering of spawning, (2) ovarian regulatory peptides involved in controlling oocyte transport in the genital ducts and in the secretion of capsular products, and (3) peptidic and polypeptidic sex pheromones suspected of being responsible for mating and the grouping of spawners on spawning grounds.
The massive production of transcriptomic data carried out since 2012 from organs collected at different maturity stages allows for targeted in silico analyses based on structural criteria and the identification of expression products by mass spectrometry. A list of candidate (neuro)peptides relevant to the studied regulations is finally established based on tissue and temporal expression profiles.
The functional approach, carried out after synthesis of mimetic peptides, relies on myotropic tests (contraction of the oviduct, accessory glands of the genital tract, etc.), cellular tests (mainly ovarian follicles), and behavioral tests in a Y-maze or open space.
A comparative approach is also being developed using the and models to understand the respective levels of involvement of the three types of regulators identified in marine molluscs with very different lifestyles and reproductive behaviors.
A thesis funded by the Lower-Normandy Region (2014-2017) explores the control mechanisms of spawning with a comparative approach targeted at the two main marine mollusc models studied in the UMR: the cuttlefish and the Pacific oyster.
Applied Research : Feeding in marine aquaculture. Model: the European seabass (Dicentrarchus labrax).
The development of aquaculture is resulting in an increasing demand for aquafeeds. Due to the importance of low molecular weight (MW) nitrogen compounds for aquaculture species in feeding behavior, nutrition, and health, the use of marine co-products has become the specialty of our private partner, the company SPF DIANA. In this context, the AQUATIV subsidiary develops and offers functional hydrolysates for the formulation of feeds intended for farmed fish and shrimp. The application of controlled hydrolysis processes to marine raw materials generates high levels of low molecular weight peptides. While the performance of the hydrolysates has been demonstrated during zootechnical trials on several aquaculture species of interest, there remains a need for product characterization and understanding of the mechanisms of action, which are levers for optimizing their performance.
As part of a collaboration that began in 2011 with a thesis (2011-2014), and a renewal resulting in a second thesis (2015-2018), we are focusing on the structural and functional characterization of 2 functional hydrolysates derived respectively from the co-products of Litopenaeus vannamei and Oreochromis niloticus. A transcripto-peptidomic approach is being developed to create molecular mass profiles of the hydrolysates, for the identification of hydrolytic peptides, and to determine their tissue origin. Antibacterial tests on pathogenic strains encountered in intensive aquaculture farms are being carried out, as are antioxidant tests. Finally, in close collaboration with the R&D department of the private partner, zootechnical tests allow for the monitoring of specific biomarkers for intestinal absorption and immunity using q-PCR or RNAseq, in order to establish a link between the level of hydrolysis, growth, and the sanitary status of farmed sea bass.
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