Influence of Dietary Yeast Restriction on Pathological Changes in the Body of the Fruit Fly under High Consumption of Amylose Starch

Nutrition is one of the important factors that affect both the longevity and quality of life. It is known that an excessive intake of all macronutrients, particularly carbohydrates, contributes to the development of obesity and oxidative damage. Hovewer, the nutritional properties of carbohydrates depend not only on their quantity, but also on the rate and extent of their digestion and absorption. Based on clinical and animal research, polysaccharide amylose starch had been proposed to be the most potentially beneficial starch fraction for human health. We aimed to study the safety of this fraction of starch for fruit fly, which is recognized to be a good model to study diseases associated with high carbohydrate consumption. It is known that the molecular mechanisms which regulate quality of life in both invertebrates and vertebrates are not only limited to the excessive consumption of carbohydrates, but also depend on amount of protein components. Thus, in our work we manipulated the macronutrient composition of the food by varying levels of amylase starch (carbohydrate) and yeast (protein). The D. melanogaster strain w1118 was obtained from Bloomington Stock Center (Bloomington, Indiana, USA). Experimental media contained 0.18% nipagin (v/v), 1% agar (w/v), 5% or 20% (w/v) amylose starch and yeast in a range of concentrations: 1%, 5%, 10% and 15% (w/v). Developmental survival was assessed as amount of eggs which were able to reach pupa stage. Median pupation time was calculated as the time at which 50% of total larvae had pupated (PT50). The pupation height was measured as the distance from the food surface. Triacylglyceride (TAG) levels were measured using a diagnostic kit Liquick Cor-TG (P.Z. Cormay S.A., Poland) following kit guidelines. Lipid hydroperoxides (LOOH) content was assayed by FOX method. The results of our study showed that diets with high concentrations of amylose starch (20%) and protein restriction (1%) significantly prolonged development time and delay pupation height in D. melanogaster, as compared to all other groups. In these conditions (20% starch and 1% yeast) we observed TAG accumulation in eight day-old-females. There was positive correlation between the levels of LOOH and consumed carbohydrate in two day-old-flies of both sexes under condition of protein restriction. However, consumption of diet with excessive amount of carbohydrate and middle (5-10%) or high (15%) protein content had no effect on the development and concentrations of TAG and LOOH in the body of fruit flies. In conclusion, we want to resume that a sufficient amount of protein in the diet reduces the negative effects of high-dose amylose starch.