Life-Cycle Approaches to Understand the Interactions Between Crops and Engineered Nanoparticles at Molecular Level

<p>NON-TECHNICAL SUMMARY:<br/> Engineered nanoparticles (ENPs) are used in cosmetics, hygiene products, biomedical applications, electronics, optics, food packaging textile, water treatment, fuel cells, sensors, and environmental remediation. They have unique physicochemical properties that are not found in bulk materials with the same chemical composition. Because of their unique properties and interactions with the environment, some ENPs are reported to be harmful to human and other ecosystem components. With rapidly growing demand and production, ENPs are finding their way into the environment via air, water, and soil routes. Plants, being the primary components of the food chain, are the most important gateways through which nanoparticles may enter the food chain, contribute to their bioaccumulation, and find their way to human receptors. This is an emerging threat to
human food safety and health. This research will study the life-cycles of two ENPs (zinc oxide and carbon nanotube) in plants from germination to maturity. Uptake and transport of ENPs, their effects on plant growth, and impacts at the genetic and genomic levels will be studied in a fresh crop (spinach) and a major food crop (rice). The research findings are expected to throw lights on accumulation of ENPs and their genetic manifestations in human foods. The computer-based models developed by this research will pave the way to simulate other nanoparticles for different food crops. The findings will help in stimulating new research on environmentally compatible nanomaterials and ENPs for use in plant nutrient and animal drug delivery.
<p>APPROACH:<br/> The project involves the study of the life-cycles of ENPs in plants starting from plant germination to maturity. ENPs with specific functionalities will be synthesized within this project and task specific characterization will be done. The particles will be used for in-vivo studies using Spinacea oleracea and Oryza sativa as the model plants. Interactions between Spinacea oleracea cells and ENPs will be studied during in-vitro experiments under different environmental conditions. New characterization techniques using atomic force microscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy will be developed to better interpret ENP-plant interactions. The observations made during macro- and microscopic studies will be verified and validated in genetic and genomic levels. The results from in-vivo, in-vitro, characterization,
genetic, and genomic studies will be integrated into molecular dynamics simulation models. The models will specifically address ENP-DNA and ENP-cell wall protein interactions. The findings from the model simulations will be used to relate the experimental findings from the plant cell and whole plant level to molecular level changes, and further relate them to overall plant health. The information generated by this research project will be used to educate students at the undergraduate and graduate levels. The research results will be communicated to other researchers through peer reviewed journal articles, book chapters, seminars, workshops, symposia, and conferences. The success of this project will be measured by the impacts the research results will have in the field of food safety, plant science, environmental nanotechnology, and biological system modeling. The primary indicators of
success of this project will be the number of peer reviewed articles in reputed journals, technical reports generated, and responses from peers at meetings and presentations. Another measure of success for this project will be the additional research developed based on the results obtained from this project.
<p>PROGRESS: 2012/01 TO 2013/01<br/>OUTPUTS: In-vivo experiments included exposure of spinach plants grown in hydroponic culture to ZnO nanoparticles (NPs, 0, 2, 50, 500 micromol/L). Sampling protocol are prepared for simultaneous collection of mature plant samples for genomic, microscopy, and metal-uptake analyses. Studies with single walled carbon nanotubes (SWNTs) are planned. Allium studies are ongoing to evaluate impacts of ZnO NPs and SWNTs on root chromosomes. In in-vitro experiments, spinach DNAs were isolated from laboratory grown plants and exposed to SWNTs in batch experiments. PCR and qPCR experiments were conducted to detect possible genome DNA damage caused by SWNT. Fourier transform infrared spectroscopy (FTIR) experiments were conducted to investigate the molecular structure and interactions of DNA exposed to SWNTs and ZnO NPs. Chromosome-2 of japonica
subspecies of oryza sativa was chosen for the molecular modeling studies. The obtained double stranded chromosome DNA structure (built using a DNA sequence builder) was 969 base pairs long. For molecular modeling simulations, models comprised of 48 base pairs of this DNA. The SWNT (diameter = 1 nm and length = 48 base pair long DNA) structure was obtained using CNT builder in VMD software. Two models were constructed. The first model consisted of the DNA and SWNT, and the other had DNA but no SWNT. Both models are solvated in water. The TIP3P model of water was used in both the simulation models. Simulation box size of both models is similar. The simulations were performed using 6 nodes, 8 processors (total processors = 48) and wall-time for each simulation was 84-90 hours (8-10 days). Global gene expression assays will be performed using next gen sequencing to generate large amounts of
data and would be disseminated by creating a easily searchable database. The database architecture and framework has been developed with Microsoft SQL Server 2008 using an existing data set. The future users of the database will be able to retrieve data using webforms (e.g., keyword or gene-id). The dataset contains gene expression values for different contigs generated through de novo assembly of RNA seq reads. A pipeline to overlay gene expression data on metabolic pathways for effective visualization has been developed. PARTICIPANTS: 1. Achintya Bezbaruah (PD) 2. Dinesh Katti (PI) 3. Marinus Otte (PI) 4. Kalpana Katti (PI) 5. Donna Jacob (PI) 6. Jose Gonzalez (PI) 7. Amanda Grosz (Undergraduate student) 8. Anurag Sharma (Graduate student) 9. Chunju Gu (Graduate student, Volunteer researcher) 10. Khurram Sheikh (Graduate student) 11. Michael Quamme (Graduate student) 12. Mohammad
Enayet Hossain (Graduate student) 13. Navaratnam Leelaruban (Graduate student) 14. Padmapriya Swaminathan (Graduate student) 15. Shashindra Pradhan (Graduate student) TARGET AUDIENCES: Researchers in food safety and nanotoxicity areas will be targeted. The PD and PIs will attend conferences and seminars in the coming year. Journal publications are expected. PD Bezbaruah will discuss results from this project in his Environmental Nanotechnology (CE 471/671) course in the coming fall semester. The other PIs and graduate/undergraduate students involved will be invited present their findings in that class. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.