The preparation of an oil-enriched diet and its nutritional impact on Nothobrachius furzeri

Nothobranchius furzeri are the shortest-lived vertebrate kept in captivity and display ageing phenotypes similar to mammalians. As such, they are been gaining popularity to be used as alternative ageing models. Indeed, this species has demonstrated to be a good model to study neurodegenerative diseases as it accumulates ageing markers of neurodegeneration, cancers as it spontaneously develops tumours, dietary-induced obesity as it presents a higher visceral fat content in response to an increase intake of fat. Although, this killifish is an innovative model, no standardized diet yet exists for this species. However, dietary interventions on this model have successfully changed lifespan and delayed the onset of age-related markers. In regard to these findings, we believe that a formulated diet adapted to this fish and which could be supplemented with bioactive compounds, including oils, could be a great asset for nutritional studies. Hence, this thesis aims at developing such a food. The objective of this study was to elaborate a diet that would be enriched in pomegranate seed oil since the main fatty acid of this oil, punicic acid (PunA), is known to show health-promoting properties including anti-cancer activity. Two different diets were formulated: the first consisted of lyophilized bloodworms soaked in pomegranate seed oil, and the second was based on a mixture of alginate (1%) and filtered bloodworm homogenate enriched with pomegranate seed oil (30%). The reproductive and somatic parameters of the fish were measured in order to evaluate the suitability of the diet supplemented with oil. Furthermore, the killifish fatty acid profile was analyzed for the fish fed either diet. Measurements indicated that killifish growth was affected when fish were fed with the lyophilized bloodworms soaked in oil, suggesting that this diet was not suitable for the fish. However, results demonstrated that both diets were ingested since PunA was detected in large amounts in the body of the fish. Interestingly, PunA (C18:3c9t11c13) was converted into rumenic acid (C18:2c9t11) in very small proportions or not at all indicating that the production of the enzyme responsible for the saturation reaction was very low or was present in an inactive form at the studied ages (28 and 50 days). Overall, the alginate food seemed to be the more convenient diet for nutritional studies on killifish as the latter can be prepared with ease and as the amount of incorporated oil can be controlled.