Nanoplastic and metal-oxides transcriptomic responses and oxygen consumption analysis in the Antarctic clam Laternula elliptica

Human activities are impacting even the most remote regions of our planet, including Antarctica. The Fildes Bay coastal area (King George Island) is among those considered more at risk to anthropogenic stressors, with increasing concern on consequences to marine life. Here we investigated the potential hazard posed by contaminants of emerging concern (CECs) as nanoplastics and metal-oxide nanomaterials either as single or combined exposure in the Antarctic clam Laternula elliptica. The digestive gland was used to assess the transcriptomic response and oxygen consumption upon in vivo exposure to polystyrene (PS-COOH-NP) and titanium-dioxide nanoparticles (TiO2-NP) at environmental realistic concentrations (5–50 µg · L-1). A total of 2852 differentially expressed genes were found in clams exposed to either single contaminant or in combination versus the control group. The transcript functions affected included autophagy, cell cycle, proteases co-chaperones and their transcription factors, antioxidants, membrane fatty acids, cell pH balance enzymes, mitochondria stress and ATP production in PS-COOH-NP (5 µg · L-1) and TiO2-NP (5 and 50 µg · L-1) groups as well as in co-exposure at 50 µg · L-1. Exposure to TiO2-NP (5 and 50 µg · L-1) and co-exposure at 50 µg · L-1 affected transmembrane transport enzymes and histones. Co-exposure at 5 µg · L-1 shows ribosomal proteins, protease and apoptosis transcripts affected and PS-COOH-NP (at 50 µg · L-1 only) protease as transcripts with known functions. Oxygen consumption decreased significantly upon combined exposure to nano-pollutants at the two concentrations, suggesting a synergistic effect impairing clam metabolism. Our results highlighted several molecular pathways affected by treatments and metabolism decreased in co-exposures, demonstrating the hazardous behavior and toxicity of these nanoparticles.