Mechanism of Regulation on the Infection of Ascogregarina Taiwanensis in Its Mosquito Host---Cell Death of Unmigrated Trophozoites

The parasitism of Aedes albopictus/Ascogregarina taiwanensis is evidently suitable as a model of investigating parasite/host interrelationships on the basis of its unique characteristics including high specificity, low lethality, short life cycle, and easy havest of materials. In order to explore the process of gregarine infection to its mosquito host, a series of experiments, covering ultrastructural changes of developing trophozoites, host endocrine effects on gregarine defelopment, trophozoite migration and so forth, have been carried out with this model. It is now known trophozoites of As. taiwanensis developing in mosquito midgut must migrate to Malpighian tubules for sexual reproduction around the period of pupation. However, a limited number of trophozoites that fail to complete migration usually remain in the midgut and end up with death, presumasably apoptosis, in consequence. This phenomenum is supposed beneficial for adjustment of parasite load within the host. As a result, it would be interesting to understand in deatal the mechanism and patway of residual trophozoites heading for cell death. The primary goal of this study aims at confirming the mechanism of cell death among unmigrated trophozoites. Tests including DNA ladders, and TUNEL assay, as well as electron microscopy for ultrastructural observation will be applied for apoptosis analysis in this sutdy. In addition, the pathway of programmed cell death will be confirmed through measurement of mitochondrial membrane potentia and cytochrome c release as well as analysis on caspase activity. In order to identify genes that might be involved in successful infetion of gregarines in the mosquito host, an EST (expressed sequence tag) library will be established in order to identify important genes. Further, selected genes will be cloned for protein expression; which will certainly be useful for further study of gregarine infection in the future.

Project ID:PC9706-0313
External Project ID:NSC96-2320-B182-016-MY3