Fig. 8

20E reduces the midgut microflora abundance likely by up-regulating the expression of immunity proteins. a Cultivable microflora in the midguts from IV-3:12 h to V-1:0 h. The total number of bacterial colonies significantly decreased when larvae entered the fourth molting stage. The number of midgut bacteria increased again after food was provided. b Expression of immunity proteins in the midguts during the molting stage as assayed by Western blot. Two antibodies against Manduca sexta βGRP2 [31] and Serpin-3 [32] were used for detection of the corresponding proteins in the molting midguts. These two proteins were observed to increase when either approaching or during the molting stage. c–e 20E was injected as described in methods. At 24–36 h post 20E injection, when the insects appeared to be in a molting state, midgut contents were removed for enumeration of cultivable bacteria. DMSO (solvent for 20E) injection was used as a control. 20E injection significantly decreased the abundance of the microflora within the midgut contents. Columns represent the means of independent measurements ± SEM (n = 8)