Nanoparticle (NP) accumulation through terrestrial food chains is being evaluated at the physiological and molecular level. Specifically, CeO2 and La2O3 bulk and NP were added to vermiculite or soil (0-1000 mg/kg) with zucchini, tomato or lettuce plants. Additional studies have been initiated in which lettuce was added to soil 0 or 70 d after amendment with CuO NP, bulk and ions (0-400 mg/kg) and with zucchini exposed to binary combinations of NP CeO2, La2O3, CuO, ZnO and CdS quantum dots (100-500 mg/L). The response of 70 identified target genes within the plants was evaluated through transcriptomic/proteomic analyses. A systems biology approach links the target genes in a complex network, representing molecular pathways, cellular components and biological processes involved in plant response; this work is ongoing. In addition, the plant element accumulation was determined by ICP-MS. Select tissues were fed to crickets or darkling beetles for 14 days. Crickets were then fed to secondary consumers: wolf spiders, mantids or lizards for 7 or 14 days. The metal content of the primary/secondary consumers and cricket/lizard feces were also measured. Results from the Ce experiment showed that zucchini Ce content was significantly greater with the NP exposure. The flowers, leaves, stems, and roots of bulk exposed plants contained 93.3, 707, 331, and 119,000 ng/g, respectively; nanoceria-exposed plants contained 153, 1510, 479 and 567,000 ng/g, respectively. Crickets fed bulk and NP-exposed leaves contained 15 and 34 ng/g, respectively. Spiders consuming bulk-exposed crickets had non-detectable Ce but NP-fed spiders contained Ce at 4.9 ng/g. Upon lanthanum exposure, lettuce mass was reduced across all treatments but there was no difference in lettuce La content based on particle size. Although the CuO experiment is ongoing, preliminary results from biomass and pigment content/production showed no significant effects in lettuce from the two soils (0 or 70-d weathered Cu) upon Cu exposure. Interestingly, expression levels of several target genes involved in Cu transport suggest that the mechanisms involved in CuO NPs accumulation are differentially regulated as compared to ionic Cu. Additional physiological and molecular results focused on the toxicity and accumulation of Cu in plant, crickets and lizard tissues will also be presented, as well as molecular plant response data from the ongoing binary NP exposure experiment.

Accumulation and transfer of engineered nanoparticles in terrestrial food chains: Correlating physiological and molecular response

253rd National Meeting (2017)

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