Screening For Regulatory Fat Storage Genes By Transcriptome

Diet affects the development, metabolism, aging and life span of Caenorhabditis elegans (C. elegasns). C. elegans are fed by bacteria, and different bacterial diets can lead to different dietary responses. The bacterial strain Escherichia coli (E.coli) OP50 is the standard laboratory diet and another strain HT115 was used to feed worms while delivering RNAi to interrogate the genetic basis.C. elegans have four larval stages (L1, L2, L3, L4), young adult (YA), adult (A), and old adult (OA). Our project studied four stages worms (L3, L4, YA and A) fed by diffirent diets(E.coli OP50 and HT115). Anaylsed the samples by thin-layer chromatography, gas chromatography, Nile Red staining and transcriptome. Results show that the lipid droplets tended to be larger as worms mature gradually, when feeding by OP50 or HT115. Thin layer chromatography and gas chromatograpy were used to analyse the fatty acid and the changes in fatty acid content and we have found that the triglyceride (TAG) content decreased with the development of C. elegans on diffirent bacterial diets. Besides, there were several fatty acids were up or down regulated, such as C16:0, C18:0, C18:ln7, C20:4n3, C20:5n3 and so on.The transcriptomeice data suggested that when compare with L4 worms fed on OP50, the expression level of 154 genes varied along with development, or compared with L3 worms fed on HT115, the expression level of 944 genes varied along with development.The transcriptomeice data of the same aged worms showed that there are a lot of genes showed changed expression level at L3 and L4 despite different bacterial diets. Only one gene was up-regulated at the young adult, and 22 genes were down-regulated genes at adult. Hence we speculated that the expression level changes of almost genes happened during the development process, and genes’expression level changes at the young adult (YA) stage and the adult stage might result in aging and so on.Compared with L4 worms fed on OP50,2078 genes were up-regulated and 2292 genes were down-regulated at L3,592 genes were down-regulated and 582 genes were up-regulated at YA, and 923 genes were down-regulated and 976 genes were up-regulated at adult. Among these genes,154 genes (96 down-regulated genes and 58 up-regulated genes) changed along with the development of lipid droplets and worms mature gradually. Compared with L3 worms fed on HT115,2624 genes were down- regulated and 3301 genes were up-regulated at L4,805 genes were down-regulated and 1244 genes were up-regulated at young adult, and 5217 genes were down-regulated and 4777 genes were up-regulated at adult. Among these genes,944 genes (427 down-regulated genes and 517 up-regulated genes) changed along with the development of lipid droplets and worms mature gradually.RNA interference was used to screen for genes mentioned above regulating lipid metabolism. The size of lipid droplets were enlarged when T12F5.11 (sld-2), F39H2.5, DY3.2 (lmn-1), R07E5.15, R01H2.3(egg-2), C30A5.7 (unc-86), D1046.4, ZK593.7(lsm-7), K02H11.4, T05C12.10 (qua-1), T11F9.9 (col-157) were knock down. The size of lipid droplets were redunced when T08B2.12, F26H11.1 (kbp-3), F40F11.3 and F44B9.1 (dpf-6) were knock down.