Regulatory factors controlling tick salivary glands (SGs) are direct upstream neural signaling pathways arising from the tick's central nervous system. Here we investigated the cholinergic signaling pathway in the SG of two hard tick species. We reconstructed the organization of the cholinergic gene locus, and then used in situ hybridization to localize mRNA encoding choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) in specific neural cells in the Ixodes synganglion. Immunohistochemical staining revealed that cholinergic axonal projections exclusively reached type I acini in the SG of both Ixodes species. In type I acini, the rich network of cholinergic axons terminate within the basolateral infoldings of the lamellate cells. We also characterized two types (A and B) of muscarinic acetylcholine receptors (mAChRs), which were expressed in Ixodes SG. We pharmacologically assessed mAChR-A to monitor intracellular calcium mobilization upon receptor activation. In vivo injection of vesamicol-a VAChT blocker-at the cholinergic synapse, suppressed forced water uptake by desiccated ticks, while injection of atropine, an mAChR-A antagonist, did not show any effect on water volume uptake. This study has uncovered a novel neurotransmitter signaling pathway in Ixodes SG, and suggests its role in water uptake by type I acini in desiccated ticks.
- MeSH
- acinární buňky metabolismus fyziologie MeSH
- axony metabolismus MeSH
- centrální nervový systém metabolismus MeSH
- cholin-O-acetyltransferasa genetika metabolismus MeSH
- cholinergní látky metabolismus MeSH
- klíště metabolismus MeSH
- messenger RNA metabolismus MeSH
- neurony cholinergní metabolismus fyziologie MeSH
- neurony metabolismus MeSH
- signální transdukce genetika MeSH
- slinné žlázy metabolismus fyziologie MeSH
- vezikulární transportní proteiny acetylcholinu genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The different components of the mouthparts of hard ticks (Ixodidae) enable these parasites to penetrate host skin, secrete saliva, embed, and suck blood. Moreover, the tick's mouthparts represent a key route for saliva-assisted pathogen transmission as well as pathogen acquisition from blood meal during the tick feeding process. Much has been learned about the basic anatomy of the tick's mouthparts and in the broad outlines of how they function in previous studies. However, the precise mechanics of these functions are little understood. Here, we propose for the first time an animated model of the orchestration of the tick mouthparts and associated structures during blood meal acquisition and salivation. These two actions are known to alternate during tick engorgement. Specifically, our attention has been paid to the mechanism underlining the blood meal uptake into the pharynx through the mouth and how ticks prevent mixing the uptaken blood with secreted saliva. We animated function of muscles attached to the salivarium and their possible opening /closing of the salivarium, with a plausible explanation of the movement of saliva within the salivarium and massive outpouring of saliva.
- MeSH
- infestace klíšťaty parazitologie MeSH
- klíště anatomie a histologie MeSH
- mikroskopie elektronová rastrovací MeSH
- myši MeSH
- nymfa anatomie a histologie parazitologie MeSH
- salivace * MeSH
- stravovací zvyklosti * MeSH
- ústa anatomie a histologie parazitologie MeSH
- zobrazování trojrozměrné MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH