Research Paper Volume 10, Issue 4 pp 622—631

Stress resistance and lifespan enhanced by downregulation of antimicrobial peptide genes in the Imd pathway

Figure 1. Imd AMP genes are downregulated in adult flies developed at 18°C. (A) Increased stress resistance of 2-day-old (white) and 30-day-old (black) male adult flies developed at 18 °C, which were compared from 2- and 30-day-old flies developed at 25 °C (0%), respectively. The median survival times of flies under each stress (starvation, oxidation or heat) were calculated from the survival curves of 3 ~ 5 independent experiments, and then the changed percentage is represented as average ± standard error of mean (SEM) following normalization with the median of flies developed at 25 °C (starvation: 28.2 and 11.1 hours; oxidation: 15.4 and 8.0 hours; heat: 15.3 and 1.7 hours of 2- and 30-day-old flies, respectively). P-value (*): Student’s t-test. (B) The gene expression analyses between 2-day-old male flies developed at 18°C and 25°C. From three independent microarray experiments, the fold changes of gene expression (18C/25C) were averaged with SEM. (C) With the genes changed more than 1.5 fold (total 176 in B), the gene ontology was analyzed using a DAVID web tool (http://david.abcc.ncifcrf.gov/home.jsp). %: involved genes/total 176 genes; p-value: a modified Fisher Exact. (D) Expressional changes of genes in Toll (Tl, Def, Drs-l, Drs, Mtk), Imd (imd, DptB, AttA, AttB, AttC, CecB, CecC, Dro) and JNK (bsk, GstD1, Thor) pathways from the microarray experiments (B). (E) RT and real-time PCR analyses of AMP genes in Imd pathway. Gene expression folds (18C/25C) of 2- and 30-day-old male flies were averaged from 4 ~ 8 independent experiments using four different RNA batches.