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Figure 3: Attempt to recover IIS function in flies containing P3G5 bacteria
The small size and diabetic metabolism demonstrated in P3G5 A. Pomorum is also seen in other animals with defective insulin/insulin-like growth factor signaling (IIS). Additionally, PQQ-ADH activity is necessary for full expression of Drosophila insulin-like proteins (DILPs). Moreover, the transcription factor dFOXO was not retained in the cytoplasm, which is a step necessary for IIS activation. To test the hypothesis that the developmental delays and metabolic abnormalities of flies containing P3G5 A. Pomorum are due to a lack of IIS activity, the authors restored IIS activity by oxerexpressing DILP2
Image from Shin et al., 2011
Panel A: The three images display fluoresently tagged dFOXO in the cells of flies containing either WT bacteria, P3G5 bacteria, or P3G5 bacteria and overexpressing DILP2, respectively. In flies containing P3G5 bacteria but not overexpressing DILP2, dFOXO localization was restricted to the nucleus. With overexpression of DILP2, dFOXO was retained in the cytoplasm and the WT phenotype was recovered.
Panel B: The three images display larvae of flies containing either WT bacteria, P3G5 bacteria, or P3G5 bacteria and overexpressing DILP2, respecively, after 120 hours. The graph displays time to puparium formation (y-axis) for each of these three groups. Puparium formation was significantly delayed in flies containing P3G5 bacteria, but upon overexpression of DILP2, the WT phenotype was partially recovered.
Panel C: The three images display adult (five-day old) flies containing either WT bacteria, P3G5 bacteria, or P3G5 bacteria and overexpressing DILP2, respecively. The graph displays female body mass (y-axis) for all three groups. The mass of flies containing P3G5 bacteria was significantly smaller than the mass of flies containing WT bacteria, and that phenotype was partially recovered after overexpression of DILP2.
Panel D: The three images display the wings of adult (five-day) old flies containing either WT bacteria, P3G5 bacteria, or P3G5 bacteria and overexpressing DILP2, respecively. Graphs display wing size in area, cell size, and cell number (y-axis) as a function of the different groups (x-axis). For all three dependent variables, size or number was significantly reduced in flies containing P3G5 mutant bacteria, but the WT phenotype was partially recovered after overexpression of DILP2.
Panel E: Blood sugar and lipid levels (y-axis) are displayed for three groups: flies containing WT bacteria, P3G5 bacteria, or P3G5 bacteria and overexpressing DILP2. Both blood sugar and lipid levels were significantly increased in P3G5 mutant bacteria-containing flies, but upon over expression of DILP2, the WT phenotype was fully recovered.
Reference:
Shin, C. S., Kim, S., You, H., Kim, B., Kim, A. C., Lee, K., Yoon, J., Ryu, J., Lee, W. 2011. Drosophila Microbiome Modulates Host Development and Metabolic Homeostasis via Insulin Signaling. Science. 334: 670-674.
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