Diet

The sunray venus (SRV) clam (Macrocallista nimbosa), is an alternative shellfish aquaculture species to hard clams (Mercenaria mercenaria) for Florida. Production of high-quality hatchery seed is dependent on diet. This study was initiated to determine an optimal live microalgae diet and test the efficacy of commercially available microalgae concentrates as partial or complete replacements for live algae. Benefits were seen with multiple algal species combinations. Both clam species achieved highest growth and survival when fed a multi-species quad-algal live diet, although hard clams performed well when fed I. galbana and C. gracilis or I. galbana and P. lutheri. Neither species performed well with complete replacement diets, but showed good production with partial replacement diets. The fatty acid (FA) profile of clams reflected the FA profile of the fed diet. Clams fed multi-species diets of live algae had a well-balanced FA profile consisting of high n3/n6, EPA/DHA and EPA/ARA ratios.

Animals rely on the integration of a variety of external cues to understand and respond appropriately to their environment. The relative amounts of food and constitutively secreted pheromone detected by the nematode C. elegans determines how it will develop and grow. Starvation conditions cause the animal to enter a protective stage, termed dauer. Dauer animals are non-eating, long-lived and stress resistant. Yet, when these animals are introduced to food replete conditions they will recover from dauer and proceed into normal development. Furthermore, food restriction has been demonstrated to extend the lifespan of a wide-range of species including C. elegans. However, the exact mechanism by which food signals are detected and transduced by C. elegans to influence development and longevity remains unknown. Here, we identify a G protein-coupled receptor (GPCR) DCAR-1 that acts in two chemosensory neurons to mediate food signaling in an autophagy-related manner. The DCAR-1 ligand Dihydrocaffeic acid (DHCA) competes with dauer-inducing pheromone to promote growth. DHCA is a key intermediate in the shikimate pathway, which is required to synthesize folate and aromatic amino acids. We report that dcar-1 mutations influence dauer formation and extend wildtype lifespan via a mechanism of dietary restriction. Moreover, we show that the lifespan extension of dcar-1 mutants is completely dependent on autophagy gene atg- 18. Furthermore, our data suggests metabolites derived from shikimate are food signals that control aging and dauer development through GPCR signaling in C. elegans. These studies will contribute to the delineation of mechanisms behind the beneficial effects of dietary restriction in eukaryotic organisms.

In the modern United States, capitalism is the predominant cultural value that structures the food system. The current American relationship to food is strained, at best, as two-thirds of Americans experience overweight and obesity and are at risk for a number of serious health complications. An understanding of the historic and political-economic aspects of the American food system is necessary to address the effects of our modern food habits on our ideas of our selves. This thesis analyzes the types of foods Americans eat, why they make the food choices that they do, how they feel about their eating habits and their habits' effects on their bodies, and how this all relates to our sense of identity as Americans.