The Red Flour Beetle Tribolium castaneum as a Model to Monitor Food Safety and Functionality.

: Food quality is a fundamental issue all over the world. There are two major requirements to provide the highest quality of food: having the lowest reachable concentrations of health-threatening ingredients or contaminants and having the optimal concentrations of health-improving functional ingredients. Often, the boundaries of both requirements are blurred, as might be best exemplified by nutraceuticals (enriched food products invented to prevent or even treat diseases), for which undesirable side effects have been reported sometimes. Accordingly, there is an increasing need for reliable methods to screen for health effects of wanted or unwanted ingredients in a complex food matrix before more complex model organisms or human probands become involved. In this chapter, we present the red flour beetle Tribolium castaneum as a model organism to screen for effects of complex foods on healthspan or lifespan by assessing the survival of the beetles under heat stress at 42 °C after feeding different diets. There is a higher genetic homology between T. castaneum and humans when compared to other invertebrate models, such as Drosophila melanogaster or Caenorhabditis elegans. Therefore, the red flour beetle appears as an interesting model to study interactions between genes and food ingredients, with relevance for stress resistance and lifespan. In that context, we provide data showing reduced lifespans of the beetles when the food-relevant contaminant benz(a)pyrene is added to the flour they were fed on, whereas a lifespan extension was observed in beetles fed on flour enriched with an extract of red wine.

Longevity in the red flour beetle Tribolium castaneum is enhanced by broccoli and depends on nrf-2, jnk-1 and foxo-1 homologous genes.

Diet is generally believed to affect the aging process. The effects of complex foods on life span can be investigated using simple models that produce rapid results and allow the identification of food-gene interactions. Here, we show that 1 % lyophilized broccoli, added to flour as a dietary source, significantly increases the life span of the red flour beetle (Tribolium castaneum) under physiological conditions (32 °C) and under heat stress (42 °C). The beneficial effects of broccoli could also be reproduced by supplementing flour with the isothiocyanate sulforaphane at concentrations found in the broccoli-supplemented diet. We identified stress-resistant genes responsible for these effects on longevity by microinjecting pupae with double-stranded RNA to induce RNA interference (RNAi). The knockdown of transcripts encoding homologs of Nrf-2, Jnk-1 and Foxo-1 reduced the life span of beetles and abrogated the beneficial effects of broccoli, whereas the knockdown of Sirt-1 and Sirt-3 had no impact in either scenario. In conclusion, T. castaneum is a suitable model organism to investigate food-gene interactions that affect stress resistance and longevity, and RNAi can be used to identify functionally relevant genes. As a proof of principle, we have shown here that broccoli increases the longevity of beetles and mediates its effect through signaling pathways that include key stress-resistant factors such as Nrf-2, Jnk-1 and Foxo-1.