Sensory protein kinase signalling in ' Schistosoma mansoni ' Cercariae: host location and invasion

Schistosoma mansoni cercariae display specific behavioural responses to abiotic/biotic stimuli enabling them to locate and infect the definitive human host. Here we report the effect of such stimulants on signalling pathways of cercariae in relation to host finding and invasion. Cercariae exposed to various light/temperature regimes displayed modulated protein kinase C (PKC), extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38 MAPK) activities, with distinct responses at 37°C and intense light/dark, when compared to 24°C under normal light. Kinase activities were localized to regions including the oral sensory papillae, acetabular ducts, tegument, acetabular glands, and nervous system. Furthermore, linoleic acid (LA) modulated PKC and ERK activities concurrent with the temporal release of acetabular gland components. Attenuation of PKC, ERK and p38 MAPK activities significantly reduced gland component release, particularly in response to LA, demonstrating the importance of these signalling pathways to host penetration mechanisms.