Mercury-Induced Oxidative Stress Response in Benthic Foraminifera: An In Vivo Experiment on Amphistegina lessonii

Abstract

The evaluation of the effects of pollution (e.g., Hg pollution) is a difficult task and relies mostly on biomonitoring based on bioindicators. The application of biomarkers may represent a complementary or alternative approach in environmental biomonitoring. Mercury is known to pose a significant health hazard due to its ability to cross cellular membranes, bioaccumulate, and biomagnify. In the present research, the effects of short-term (i.e., 24 h) Hg exposure in the symbiont-bearing benthic foraminiferal species Amphistegina lessonii are evaluated using several biomarkers (i.e., proteins and enzymes). Mercury leads to significant changes in the biochemistry of cells. Its effects are mainly associated with oxidative stress (i.e., production of reactive oxygen species: ROS), depletion of glutathione (GSH), and alteration of protein synthesis. Specifically, our findings reveal that exposure to Hg leads to the consumption of GSH by GPx and GST for the scavenging of ROS and the activation of antioxidant-related enzymes, including SOD and GSH-enzymes (GST, GSR, GPx, and Se-GPx), that are directly related to a defense mechanism against ROS. The Hg exposure also activates the MAPK (e.g., p-p38) and HSP (e.g., HSP 70) pathways. The observed biochemical alterations associated with Hg exposure may represent effective and reliable proxies (i.e., biomarkers) for the evaluation of stress in A. lessonii and lead to a possible application for the detection of early warning signs of environmental stress in biomonitoring.

Foraminifera and plastic pollution: Knowledge gaps and research opportunities

“…For instance, recent advances in omics technologies have provided new tools to understand the effects of contaminants, which, in turn, may serve as biomarkers to be used in environmental monitoring as early warning of pollution (Tomanek 2011;Ciacci et al 2022).…”

“…Alve 1995, Francescangeli et al 2016, Polovodova Asteman et al 2015, such as oil spills (e.g. Morvan et al 2004) (Frontalini et al 2018a), physiological changes (Losada Ros et al 2020), proteom modifications (Ciacci et al 2022) and changes in species composition of foraminiferal communities in mesocosm (Frontalini et al 2018b) in response to, respectively, copper, oil-based drilling muds, element trace metals, cadmium and mercury exposure.…”