We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Size-dependent modulation of tetracycline hydrochloride toxicity by polystyrene micro/nanoplastics in the model freshwater ciliate Paramecium tetraurelia
Summary
Scientists found that tiny plastic particles (like those breaking down from everyday plastic waste) can make the antibiotic tetracycline more harmful to living cells—and the size of the plastic particle matters a lot. Smaller plastics (50 and 500 nanometers) worsened cell damage and stress, while slightly larger plastic particles (5 micrometers) actually reduced the antibiotic's harmful effects. This matters because plastics and antibiotic residues often show up together in water supplies, and this research (done in a single-celled organism, not humans) suggests we can't assess the risk of these pollutants separately—their
The co-occurrence of micro/nanoplastics and antibiotics in aquatic environments presents complex ecological risks. This study investigated how polystyrene micro/nanoplastics (PS-MNPs) of different sizes (50 nm, 500 nm, and 5 μm) modulate the toxicity of tetracycline hydrochloride (TCH) in the eukaryotic model Paramecium tetraurelia by integrating phenotypic, physiological, fluorescence imaging, and transcriptomic analyses. Fluorescence imaging showed that combined exposure increased membrane permeability and enhanced cell-associated or retained PS-MNP fluorescence in washed cells in a size-dependent manner. Compared with TCH alone, co-exposure with 50 nm and 500 nm PS-MNPs intensified growth inhibition, reactive oxygen species accumulation, antioxidant enzyme imbalance, and morphological impairment, with the 50 nm group showing pronounced cellular shrinkage and the 500 nm group exhibiting the strongest population decline. Transcriptomic profiles further showed particle-size-dependent molecular response patterns. Co-exposure with 50 nm and 500 nm PS-MNPs involved changes in energy-related metabolism, lipid metabolism, transport-related pathways, protein processing, antioxidant responses, and DNA repair-related processes, with the 500 nm group showing a more prominent redox- and lipid-metabolic profile. In contrast, 5 μm microplastics attenuated TCH-induced population inhibition under the present exposure conditions, suggesting a distinct size-dependent co-exposure response. Overall, these findings suggest that PS-MNPs can act as size-dependent modulators of antibiotic ecotoxicity, highlighting the need to consider particle size and interaction-dependent responses in ecological risk assessment of antibiotic-plastic co-contamination.