Elucidating a novel vitamin C synthesis pathway in Caenorhabditis elegans
Authors:Alexander N. Patananan, Maria Pedraza
Mentor:Steven G. Clarke, Professor of Chemistry and Biochemistry, University of California, Los Angeles
Vitamin C is an important antioxidant that neutralizes free radicals in cells, participates in a variety of enzymatic reactions, and protects against human diseases. There are three main vitamers of vitamin C, including dehydroascorbate, D-isoascorbate, and the most common L-ascorbate. Much is known about the important roles ascorbate has in vertebrates, yet little is known about its significance in invertebrates. Caenorhabditis elegans, a commonly used invertebrate model organism, has several enzymes whose homologs in vertebrate organisms require ascorbate. Therefore, we investigated the levels of ascorbate and similar species in C. elegans and explored how these vitamers are biosynthesized. To identify these compounds, we optimized several methods using normal and reverse phase high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Interestingly, we detected the presence of ascorbate in eggs, L1 larvae, mixed worms, and gravid adults despite C. elegans lacking many of the enzymes plants and animals require for ascorbate biosynthesis. Furthermore, we incubated intact worms with various sugars known to be necessary for ascorbate biosynthesis in other organisms, but none increased the amount of ascorbate in the different life stages, suggesting a novel pathway. The presence of ascorbate in C. elegans is a first for invertebrate organisms, and we are currently elucidating the biochemical pathways for the biosynthesis of this molecule. Finding a novel pathway in C. elegans will broaden our understanding of vitamin C synthesis and its importance to organisms, as well as answering questions about the evolutionary patterns of ascorbate synthesis.