Gene expression and biochemical patterns in the digestive gland of the mussel Mytilus galloprovincialis (Lamarck, 1819) exposed to 17 ? -ethinylestradiol.

Contaminants of emerging concern (CECs) are a class of chemicals that can spread throughout the environment
and may cause adverse biological and ecological effects. While there are many different classes of CECs, one of
the most well documented in the aquatic environment are pharmaceutical drugs, such as natural and synthetic
estrogens. In particular, the widespread presence of the synthetic estrogen 17 ?-Ethinylestradiol (EE2) in water
may lead to bioaccumulation in sediment and biota. EE2 is the primary component in contraceptive pills, and is a
derivative of the natural hormone estradiol (E2). In this study, the mussel Mytilus galloprovincialis was exposed to
EE2 in a semi-static and time-dependent experiment, for a total exposure period of 28 days. Biochemical and
transcriptomics analyses were performed on mussel digestive glands after exposure for 14 (T14) and 28 (T28)
days. Metabolic and DNA impairments, as well as activation of antioxidant and biotransformation enzymes
activation, were detected in T28 exposed mussels. RNA-Seq analysis showed significant differential expression of
160 (T14 compared to controls), 33 (T28 compared to controls) and 79 (T14 compared to T28) genes. Signs of
stress after EE2 treatment included up-regulation of gene/proteins involved with immune function, lipid
transport, and metabolic and antibacterial properties. This study elucidates the underlying mechanisms of EE2 in
a filter feeding organisms to elucidate the effects of this human pharmaceutical on aquatic biota.