Variability of metabolic, protective, antioxidant, and lysosomal gene transcriptional profiles and microbiota composition of Mytilus galloprovincialis farmed in the North Adriatic Sea (Italy)

Highlights: • Natural seasonality, gender bias, and gonadal cycle effects on mussel digestive gland (DG) gene transcriptions were evaluated. • Composition of the DG microbiome was assessed. • Temperature and gonadal maturation mostly explained the transcriptional changes of females. • Salinity, oxygen, transparency affected transcriptional profiles of males. • Microbiome composition resembled metabolic accommodations to face season progression and reproductive cycle. This study evaluates the transcriptional profiles of genes related to physiological responses in digestive glands (DG) of Mytilus galloprovincialis under the influence of seasonal changes of environmental variables, gender bias, and gonadal development. Composition of the DG microbiome was also explored. Mussels were collected across 7 months encompassing 3 seasons from a farm in the Northwestern Adriatic Sea. All gene products showed complex transcriptional patterns across seasons. Salinity, surface oxygen and transparency significantly correlate with transcriptional profiles of males, whereas in females temperature and gonadal maturation mostly explained the observed transcriptional changes. Seasonal variations and gender-specific differences were observed in DG microbiome composition, with variations resembling metabolic accommodations likely facing season progression and reproductive cycle. Results provide baseline information to improve actual monitoring strategies of mussel farming conditions and forecast potential detrimental impacts of climatological/environmental changes in the study area.