Mechanisms of ROS-induced mitochondria-dependent apoptosis in Phaeodactylum tricornutum under AgNPs exposure

IntroductionNanomaterials such as silver nanoparticles (AgNPs) have gained widespread application across various fields. However, the large-scale production and application of AgNPs have raised concerns about their distribution in the environment and potential pollution issues.MethodsThis study investigates the toxic effects of AgNPs on the diatom Phaeodactylum tricornutum by employing electron microscopy for cellular observation, quantifying apoptotic cell numbers, and measuring antioxidant indicators. The research examines how varying concentrations of AgNPs induce stress in P. tricornutum and the specific mechanisms of the toxic effect.ResultsThe findings reveal that AgNPs induce apoptosis in P. tricornutum cells by triggering a mitochondria-mediated pathway, marked by a decrease in mitochondrial membrane potential and the activation of caspase enzymes. Additionally, AgNP exposure results in an overproduction of reactive oxygen species (ROS) within the algal cells, leading to lipid peroxidation of the cell membrane and a consequent increase in malondialdehyde (MDA) levels. This oxidative stress response induces the upregulation of antioxidant enzyme activities in an attempt to mitigate the excessive ROS.DiscussionROS is identified as the primary factor responsible for inducing mitochondria-mediated apoptosis. The research results will provide a theoretical basis for understanding the toxic effects and mechanisms of AgNPs on marine microalgae.