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Exploring metabolic behavior of Caenorhabditis elegans exposed to Chlorogenic acid and thermal stress

Andrea del Valle Carranza

University of Georgia

Vegetables are foods with nutraceutical characteristics, fundamental to the diet, since they provide multiple natural bioactive compounds (CNB) essential for the preservation of health and the prevention of diseases. Tomato is widely consumed around the world and its consumption is considered beneficial to reduce the risk of several chronic diseases such as cardiovascular diseases and certain types of cancer. In this project we propose to investigate the molecular and biochemical mechanisms by which CNBs derived from tomato fruit regulate the cellular and tissue processes associated with stress. To this end, it was proposed to use the organism Caenorhabditis elegans (C. elegans) to provide responses to the way food acts in response to stress and to identify active principles. A survival test of a population of C elegans under conditions of deadly heat stress was used to evaluate the activity of tomato extracts to confer thermotolerance on worms. The activity of hydrophilic extracts was evaluated in a population of Andean landraces and wild species. With this study, Chlorogenic acid (CGA) was especially related to this bioactivity mentioned above. Further studies that aim to investigate in C elegans the molecular mechanisms for CGA assimilation and the mechanisms underlying in the thermotolerance conferred by CGA were performed. For this, studied the entry and bioconvertion route of CGA in C elegans, which is unknown in this organism. Studies demonstrated that CGA needs viable bacteria to be bioactive. Based in previous results and as part of this project, we have hypothesized that CGA is inducing metabolites in bacteria responsible for bioactivity in C elegans or CGA is metabolized by bacteria in a different way of mammals. Our hypothesis of study shows that CGA interacts with intracellular signaling pathways and transcriptions factors activating processes related to the adaptation to the stress of the cells; one of them is HIF-1 hypoxia-dependent transcription factor. In C elegans, HIF-1 could be modulating longevity and resistance to different types of stress. These results represent new evidence of the mechanism associated thermotolerance induced in C elegans by CGA and constitute a contribution to the understanding of the functions of HIF-1 in normoxia. In the present Project we are interested in studying if CGA exposition before and during thermal stress modulate the metabolism of C elegans through HIF-1. Moreover we want to identify the metabolic change that occurs in the bacteria and worm by CGA exposition before and after thermal stress treatment. Dr. Edison Lab has developed LC-MS and RMN platforms for metobolomic studies. Using both platforms, more than 60 metabolites were found modified in C elegans and bacteria (C elegans food) under thermal stress. For Metabolic analysis a technique called isotopic ratio outlier analysis (IROA), which utilizes samples that are isotopically labeled with 5% (test) and 95% (control) 13C is proposed for this study. This labeling strategy leads to characteristic isotopic patterns that allow the differentiation of biological signals from artifacts and yield the exact number of carbons, significantly reducing possible molecular formulae. With the information obtained, it is proposed to answer the following questions: Is the bacterium responsible for inducing CGA bioconversion in C elegans, and responsible for its resulting bioactivity? Is CGA a probiotic agent that modifies the nematode's physiology? Is CGA producing a hormetic mechanism in C elegans modulating the metabolism before thermal stress?

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