PosterPrint
- 1. Introduction Drosophila melanogaster isa useful model organism because it has a short generation time, requires little maintenance, and most importantly shares many disease-causing genes with humans. Obesity, a growing concern for humans, can be studied using Drosophila to identify responsible genes and study their activities. Drosophila selected for starvation resistance have the ability to survive longer than controls when starved. These flies are also larger and appear more "obese" when physically compared to non-selected populations. To investigate how diet might affect fat storage in these flies, we reared larvae on media containing different caloric contents and different levels of dietary sugar and protein. Methods & Materials Larvae from 3 replicated starvation- selected and 3 replicated non-selected control populations were reared on low, medium, and high (L, M, H) caloric foods of 10g, 20g, and 30g per 100ml of water. Each caloric level was made of sugar and yeast with sugar fractions of 10, 30, 50, 70, and 90% (e.g. a low caloric level of 10% sugar would contain 1g of sugar and 9g of yeast per 100 ml). The eclosing flies were collected starting on day 8 and were collected every 24 hours until all flies had eclosed. Development data were collected for all eclosed flies. Only females were used for energy content assays. Female flies, 2 per sample and 6- 8 samples per replicated population, were homogenized in lysis buffer. Triglyceride assays were carried out used the Infinity Triglyceride kit (Thermo Scientific) and protein assays were conducted using the bicinchoninic acid method (Smith et al., 1985). Data for these assays were collected using a 96- well plate reader. Conclusions • Protein levels were less affected than triglyceride levels for all populations, which suggests that selected flies in general and control flies on a high sugar diet are not simply bigger but are specifically more obese. • High sugar diets caused delayed development time. Because the flies gain the majority of their fat stores as larvae, flies that took longer to develop were fatter when they eclosed. • Starvation selected flies had higher triglyceride concentrations for all caloric levels and sugar fractions when compared to controls. Control flies fed the highest caloric amount and with the highest sugar fraction were able to match triglyceride concentration ranges of selected flies on the lowest sugar fraction. Acknowledgements References Masek. P., L.A. Reynolds, W.L. Bollinger, C. Moody, A. Mehta, A.G. Gibbs and A.C. Keene (2014). Altered regulation of sleep and feeding contributes to starvation resistance in Drosophila. Journal of Experimental Biology 217: 3122-3132. Smith, PK, Krohn, RI, Hermanson, GT et al. (1985). Measurement of protein using bicinchoninic acid. Analytical Biochemistry 150: 76-85. Funding for this program was provided by the National Science Foundation grant DBI REU 1358896. Additional funding was provided by National Science Foundation grant IOS-1355210. Special thanks to Maeleen Morrison for figures 3 and 4. Effects of Altered Diets on Development and Energy Content of Drosophila melanogaster Paige E. Jacobs1,3, Alyssa A. Caplan2,3, Allen G. Gibbs3 1Department of Biology, SUNY Fredonia, Fredonia, NY, 14063, USA 2Department of Biology, Vassar College, Poughkeepsie, NY, 12604, USA 3School of Life Sciences, University of Nevada, Las Vegas, NV, 89154, USA Effect (F/R) SS df MS F p Selection Fixed 38.99 1 38.99 13.763 0.020656 Replication (Selection) Random 11.33 4 2.83 4.006 0.003951 Calorie Level Fixed 66.67 2 33.34 47.143 0.000000 Fraction Sugar Fixed 683.87 4 170.97 241.781 0.000000 Sex Fixed 0.00 1 0.00 0.003 0.953843 Error 118.09 167 0.71 Development Time Triglyceride Content Protein Content Effect (F/R) SS df MS F p {1}Selection Fixed 13509.4 1 13509.4 3.3655 0.140486 Replicate (Selection) Random 16056.2 4 4014.1 7.8059 0.002733 {3}CalorieLevel Fixed 1344.9 2 672.5 1.7084 0.241096 2(1*3) Random 3149.0 8 393.6 3.6181 0.002994 Selection* CalorieLevel Fixed 465.8 2 232.9 0.5916 0.575926 {4}FractionSugar Fixed 3999.8 4 1000.0 4.3590 0.014219 2(1*4) Random 3670.4 16 229.4 2.1086 0.028374 CalorieLevel* FractionSugar Fixed 1734.0 8 216.8 1.9923 0.072532 Selection* FractionSugar Fixed 1854.0 4 463.5 2.0205 0.139908 Error 4351.7 40 108.8 Effect (F/R) SS df MS F p {1}Selection Fixed 84281.2 1 84281.2 46.4806 0.002420 {3}CalorieLevel Fixed 2215.7 2 1107.8 2.8657 0.115214 Selection* CalorieLevel Fixed 525.9 2 262.9 0.6801 0.533584 {4}FractionSugar Fixed 33390.6 4 8347.7 54.0441 0.000000 CalorieLevel* FractionSugar Fixed 1796.9 8 224.6 2.3929 0.032755 Selection* FractionSugar Fixed 9635.2 4 2408.8 15.5950 0.000022 Replicate(Selection) Random 7253.0 4 1813.3 4.0548 0.033857 2*4(1) Random 2471.4 16 154.5 1.6455 0.100827 2*3(1) Random 3092.7 8 386.6 4.1185 0.001176 Error 3754.6 40 93.9 L M H 0 20 40 60 80 100 120 140 160 10 30 50 70 90 140-160 120-140 100-120 80-100 60-80 40-60 20-40 0-20 Sugar Fraction (%) TriglycerideConc. CaloricLevel Starvation Selection Figure 1. Selection method for starvation resistant flies. Eclosed are flies transferred to agar and starved until 80% of the population is dead. Surviving flies go on to produce the next generation and the process is repeated. The control flies did not undergo starvation but the remaining methods were the same. This process was conducted for A, B, and C populations of both control and selected flies. Figure 2. Triglyceride concentrations (mg/fly) as a function of sugar fraction and caloric level. Starvation selected levels shown on top with controls below. Figure 3. Protein levels (mg/fly) of flies reared on different caloric levels (L,M,H) and sugar to yeast ratios (ex. 3/7). Light yellow indicates the highest protein concentrations while dark blue indicates the lowest concentrations. Control data are presented on the left while starvation resistant data are shown on the right. Figure 4. Development times (days) of flies reared on different caloric levels (L,M,H) and sugar to yeast ratios (ex. 3/7). Light yellow indicates longer development times, while dark blue indicates more rapid development. Control data are presented on the left while starvation resistant data are shown on the right. Results: • Starvation-selected flies have higher triglyceride levels than controls • Increasing sugar fraction increases triglyceride levels • Longer development time correlates positively with triglyceride levels Results: • Starvation selected flies developed more slowly • Higher sugar fractions of all populations had increased development time Results: • Protein levels were consistently higher for starvation selected flies but only slightly • Protein levels decreased as sugar fractions increased, especially in control flies Yeast (g)Yeast (g) Sugar(g) Sugar(g) Yeast (g)Yeast (g) Sugar(g) Sugar(g) Control Selected SelectedControl