| Exosomes are small extracellular vesicles with a round monolayer structure.which are produced through a series of cell regulatory processes such as endocytosis,fusion and exocytosis.These vesicles are uniform size with 40 to 200 nm in diameter.Exosomes are considered as important nanocarriers with regulating intercellular communnciation.In the research field of mosquitoes and fruit flies,researchers have found that exosomes play an important role in virus transmission and signal regulation.Tick is a kind of blood-sucking arthropod and is also an important vector of pathogen.At present,there are few researches on tick's exosome.Salivary glands of ticks play a role in pathogen transmission.Saliva is the carrier of interaction between ticks and host.Is there exosomes in tick saliva? What is its composition? None of these have been reported.This experiment was conducted on the tick Rhipicephalus haemaphysaloides,and the exosomes of tick saliva were isolated and their protein components were identified.The role of ferritin,one of proteins in exosomes,was explored furtherly.The objective of this study is to provide a basis for understanding the molecular interaction between tick and host.Engorgement female ticks were injected with 5% pilocarpine and then collected tick's saliva.Isolating exosomes of saliva by kits and centrifugal separation technology.Exosomes were characterized by Electron microscopy(50-100 nm in size).A total of 804 proteins in saliva were identified by LC-MS,which included 489 tick proteins,host proteins(315).Ferritin,a kind of protein found in exosomes,was studied furtherly.The molecular structure of ferritin was analyzed and its antigenic epitope was predicted.The expression characteristic of Ferritin was studied during tick blood feeding by RT-q PCR and Western blot.The results showed that ferritin was expressed in the three stages such as larvae nymph and adult,and in the all organs of the blood sucking adult ticks.Through RNA interference experiments,ferritin can affect the reproductive and oviposition of ticks.The detection of vitelloprotein,the key molecule of the tick's reproductive and oviposition,showed that the four subunits of vitellin(Vg1 VG2 vg3 and vg4)decreased at the transcription level,but Western blot showed that only the expression of vg3 was significantly reduced by ferritin silencing.Cell death programm were considered as the main mechanism of tick salivary glands degeneration after tick engorgement.We found that the expression of ferritin decreased in salivary gland of engorgement ticks.While the expression of GPx4,the key molecule of ferroptosis,dramatically decreased on the third day of engorgement.The expression of Nox1 suddenly increased in salivary gland of engorgement.The morphology of mitochondria in salivary gland was smaller by Electron microscopy.These results suggest that ferritosis of ferritin relation may be involved in the degradation of salivary gland,and the relevant mechanism needs further study.In this study,the exosomes of saliva in the ticks were successfully isolated and identified.By using LC-MS / MS technology,804 kinds protein of exosomes were identified,including 489 kinds of tick derived proteins and 315 kinds of rabbit derived proteins.At the same time,it was found that ferritin may be involved in the process of salivary gland degeneration in the ticks.These results provide an important basis for the prevention and control of ticks and tick-borne diseases... |
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