Doctor of Philosophy (PhD)


School of Nutrition and Food Sciences

Document Type



Dietary bioactive compounds benefit health while some might induce pathological processes. Parkinson’s disease (PD) is the second most common neurodegenerative disease. Braak and Hawkes hypothesized that the gastrointestinal tract may be a potential site of neuronal invasion by an “unknown pathogen” leading to some Parkinsonism. Neurotoxin botulinum or ricin can trans-synaptically transport in nervous system. Our hypothesis 1: dietary plant lectins might be responsible for the “unknown pathogen” causing PD. Pomegranate juice (PJ) have antioxidant and anti-obesity effects. Our hypothesis 2: PJ increases lifespan in C. elegans and reduces fat storage. Study 1: Post-feeding rhodamine or TRITC tagged dietary lectins was tracked from gut to dopaminergic (DAergic) neurons in C. elegans BZ555 (egIs1[Pdat-1::GFP]) that has Green Fluorescent Protein (GFP) gene fused to a dopamine transport protein gene labeling DAergic neurons. Although this observation was tested with specific inhibiting sugars (SIS), supplemented with Escherichia coli, the high concentrations of monosaccharides necessary may have their own side effects. Results showed that Amaranthus caudatus agglutinin, Euonymus europaeus agglutinin and Arachis hypogaea agglutinin co- localized with DAergic neurons. Lectins affected the number, size or intensity of DAergic neurons, reduced the mobility and affected the lifespan of C. elegans to different extents, with the SIS either augmenting or mitigating the effects. Our observations are a tantalizing possible explanation for why dietary plants have been linked to a risk of developing PD. Study 2: Lifespan of C. elegans was increased by PJ treatment in wild type (N2, 56%) and daf-16 mutant (daf-16(mgDf50)I) (GR1307, 18%), by POMx in N2 (28%) and in GR1307 (10%), or by EA (11%). PJ reduced intestinal fat deposition (IFD) in N2 (-68%) or in GR1307 (-33%). The IFD was increased by POMx in N2 (137%) and in GR1307 (26%), by EA in N2 (66%) and in GR1307 (74%), or by UA in N2 (57%) and in GR1307 (43%). Both lectins and PJ are bioactive compounds, playing important roles in life. These studies may provide useful information for an alternative etiology of PD and offer solutions of using PJ to delay aging and prevent obesity in humans.



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Committee Chair

Zheng, Jolene



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