Resumen de Ecotoxicological assessment of phthalates in the freshwater gastropod Physella acuta and the sea urchin Paracentrotus lividus
Ecotoxicological assessment of phthalates in the freshwater gastropod Physella acuta and the sea urchin Paracentrotus lividus Phthalates are a group of synthetic chemicals with a broad spectrum of uses, mainly employed as plasticizers in polyvinyl chloride production. Thus, these compounds are found in hundreds of food packaging, medical devices, paints, building materials, or cosmetics. Due to their massive production, phthalates are widely disseminated in the environment, including soil, air, sediment, and waters. Besides, its use has been restricted in certain products due to their potential endocrine-disrupting properties. However, studies on the effects of phthalates in invertebrates are scarce. This work assessed the impact of three phthalates in two aquatic invertebrates: Physa acuta and Paracentrotus lividus. The phthalates selected were butyl benzyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), and diethyl phthalate (DEP).
Juveniles and adults of the freshwater gastropod, P. acuta, were exposed to different exposure times and concentrations of BBP, DEHP, and DEP, and the changes in gene expression were analyzed. The genes studied are related to different physiological processes: endocrine system (Hsp90) and stress response (sHsp16.6, sHsp17.9, Hsp60, Hsc70-4, Grp78, Cat), oxidative stress response (SOD Mn, SOD Cu/Zn, and HIF1α), detoxification (Cyp2u1, Cyp3a7, Cyp4f22, Cyp72a15, GSTk1, GSTm1, GSTo1, GSTt2, and MRP1), DNA repair (rad21 and rad50), apoptosis (Casp3 and AIF3), epigenetics (KAT6B, HDAC1, and DNMT1), nervoussystem (AChE), immunity (ApA), energy reserves (PYGL), and lipid transport (ORP8). The GST enzymatic activity was also assessed in juveniles. Besides, the embryotoxic effects of BBP in P. acuta were evaluated.
The phthalates did not affect P. acuta survival, but BBP affected embryonic development. Regarding the gene expression analysis, the results show that while DEP and DEHP did not cause any alteration, BBP modulated almost all the analyzed genes after one-week exposure of P. acuta adults. However, after longer exposure times of juvenile individuals (15 and 30 days), BBP altered the expression of just three genes (Hsp90, Hsc70-4, and GSTt2).
Regarding P. lividus, an embryotoxicity test with the planktonic stages (embryos and larvae) was performed by exposing the embryos to several concentrations of BBP, DEHP, and DEP. Concentration-dependent morphological anomalies were observed in plutei formed after embryo exposure. Besides, their swimming speed was altered after exposure to the three phthalates.
This is the first work that evaluates the effects of the phthalates BBP, DEHP, and DEP at the transcriptional level of several genes in the mollusk P. acuta and the developmental and behavioral effects on the early life stages of the sea urchin P. lividus, providing novel results on the differential effects of BBP, DEHP and DEP in the two species studied.
The results show that, unlike DEHP and DEP, BBP strongly alters different pathways involved in response to toxicants, like stress response and detoxification, DNA repair, apoptosis, epigenetic regulation, immunity, and energy metabolism, being toxic for P. acuta at the environmentally relevant concentrations used. It can be concluded that in P. acuta, the impact of BBP is extensive at the molecular level. Still, additional research is needed to elucidate the differences observed in the impact of these compounds on the gastropod. The developmental anomalies and swimming speed alterations of P. lividus early stages after exposure to BBP, DEHP, and DEP strengthen the known endocrine-disrupting character of this group of chemicals.
