You are here:
Development of molecular indicators to track the effects of nanoparticle toxicity in Arabidopsis thaliana
Citation:
Tumburu, L., C. P. ANDERSEN, M. G. JOHNSON, P. T. RYGIEWICZ, G. KING, AND J. Betts. Development of molecular indicators to track the effects of nanoparticle toxicity in Arabidopsis thaliana. Presented at SETAC, Boston, MA, November 13 - 17, 2011.
Impact/Purpose:
The emergence of nanotechnology and incorporation of nanoparticles in consumer products necessitates risk assessment from an environmental and health safety standpoint.
Description:
The emergence of nanotechnology and incorporation of nanoparticles in consumer products necessitates risk assessment from an environmental and health safety standpoint. To date, very few studies have examined nanoparticle effects on terrestrial species, especially plants. Preliminary results from an Arabidopsis thaliana Columbia (Col-0) study performed with titanium dioxide (TiO2) NP (P-25) using five test concentrations indicated reduced cotyledon expansion at 10 ppm and slowed germination at the highest concentration, suggesting that different mechanisms of response may be involved at the two concentrations. To examine the molecular basis for response, a study was conducted to examine how different concentrations of TiO2 affected different life stages of A. thaliana. Dynamic Light Scattering/Electrophoretic Light Scattering (DLS/ELS) technique was used to characterize TiO2 suspensions (concentrations 5mg/L and 500 mg/L).Particle suspensions were determined to be in the <100 nm diameter range. A. thaliana plants were exposed starting in the seed stage, to weekly suspensions of these mixtures. Subsequently, with the growth of plants, both root and shoot systems were exposed to the mixtures until they reached senescence. Following exposure, five different tissues (cotyledons, roots, leaves flowers, and siliques) at different developmental stages were harvested. Following the extraction of RNA from the tissues, and subsequent reverse transcription to cDNA, and conversion to cRNA, hybridization was performed with commercially available Arabidopsis DNA microarrays (Affymetrix) to obtain the tissue-specific transcriptome profile of Arabidopsis. The results varied with developmental stage, and showed that while some differences in gene up- and down-regulation were observed between the two concentrations, some differences may be related to differences in particle dispersion rather than concentration. Fully characterizing particle suspensions using DLS as well as other approaches such as Small-Angle X-Ray Scattering [SAXS], X-Ray Defraction [XRD] was important. The findings of this research will help to elucidate mechanisms of action associated with NP-induced toxicity and provide primary screening information for terrestrial ecological risk assessments.