Fig. 6.

Bacterial challenge and increased internal NO concentrations activate PLA₂. a PLA₂ activity is increased in bacteria-infected (heat-killed X. hominickii (HK-Xh; 1 × 10⁵ bacterial cells per larva) larvae relative to naïve controls. The increased activity is blocked by cotreatments with the bacteria plus the NOS-specific inhibitor, L-NAME. Similar coinjections with the inactive D-NAME did not influence PLA₂ activity. At 8 h post-injection (PI), the fat body was collected to measure PLA₂ activity. Each treatment included 3 biologically independent replicates, 9 larvae/replicate. The histogram bars show mean PLA₂ activity and the error bars show 1 SD. b Influence of NO increase on PLA₂ activity. Each L5 larva was injected with the indicated concentrations of an NO donor, SNAP. At 8 h PI, fat body was collected to measure nitrate concentration (inset) and PLA₂ activity. Each treatment included 3 biologically independent replicates. Each point represents mean PLA₂ activity. Different letters above the SD bars indicate significant difference among means at type I error = 0.05 (LSD test). NAÏVE, PBS-injected controls.