Estratégias Inovadoras para Mitigar a Presença de Toxinas Marinhas na Aquacultura: Novos Métodos de Depuração de Bivalves e Conhecimentos sobre o Metabolismo de Xenobioticos

The prevailing method for mitigating waterborne contaminants in bivalves involves depuration with purified seawater (15), which effectively enhances the microbiological quality of bivalves by reducing their pathogen loads. However, this method often falls short of eliminating additional risks such as marine toxins. While depuration studies have shown relative or limited success for possible short-industrial applications, the challenge remains to develop new, highly efficient depuration methods that can effectively decontaminate bivalves and eliminate marine biotoxins, improving the competitiveness of the aquaculture industry. Interest in biologically based detoxification methods that are environmentally sound, safe and highly efficient has increased significantly in recent years. The chemical defensome is identified as a crucial mechanism for detoxifying marine toxins. This system is regulated by the aryl hydrocarbon receptor (AHR) and the pregnane x receptor (PXR) or VDR/PXR/CAR-like (NR1J1) in the case of bivalves (13, 14). The present project aims to develop a novel and highly effective depuration procedure for eliminating marine toxins. Ideally, this procedure should significantly reduce DST content in bivalves within approximately 48 hours of captivity with clean water, thereby reducing operational costs. The methodology for this procedure is structured around the functions of molecular receptors AHR and NR1J1, focusing on their role in regulating xenobiotic detoxification. All studies will be carried out on the marine mussel Mytilus galloprovincialis, a species of high commercial value extensively produced in Europe and Portugal. The project encompass the following specific objectives: SO1 - Isolation and characterization of AHR genes in Mytilus galloprovincialis: SO1 focuses on collecting gene sequences and function information, currently not available, from AHR genes in the mussel Mytilus galloprovincialis (Previous research efforts by the team have already gathered information on NR1J1 genes in this species – to be published); SO2 - Survey of NR1J1 and AHR activating compounds: SO2 aims to seek natural compounds exhibiting receptor-activating properties, employing highly reliable receptor transactivation assays (few natural compounds with the reported ability to activate bivalve NR1J1 receptors have been identified so far); SO3 - Assessing NR1J1/AHR-activating properties of natural compounds in vivo: building upon the compounds identified in SO2, SO3 involves testing these natural compounds with enhanced receptor-activating properties in adult bivalves. The goal is to assess the activation of xenobiotic detoxification mechanisms in vivo, outlining a protocol for testing contaminated bivalves; SO4 - Proof-of-concept: the protocol outlined in SO3 will be replicated and applied to bivalves contaminated with DSTs. This work assesses the applicability of the model/protocol. Advanced microencapsulation technology will be tested for compound delivery to bivalves; SO5 - Assessing model versatility: SO5 involves assessing the model’s capacity to treat bivalves contaminated with other biotoxins, as well as different bivalve species. The aim is to demonstrate the versatility of the developed model, allowing its application across various contexts of microalgae contamination.