How malaria parasites move from the skin to the liver or other organs after injected by mosquitoes?

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To observe how malaria parasites develop in living mosquitoes or mice, we prepared transgenic malaria parasites (Plasmodium berghei). Green fluorescent protein (GFP) gene or luciferase gene were introduced with DHFR-TS (pyrimethamine resistant) gene. Because the GFP transgenic parasites gave fluorescent when they received UV light, we could observe malaria parasites in mosquito midgut and salivary gland. When we used luciferase transgenic parasites, luciferase activity in mice was visualized through the imaging of whole bodies or dissected organs by using an in-vivo Imaging System (IVIS). Oocysts on the midgut and sporozoites in the salivary glands in mosquitoes were visualized with GFP. When we adopted luciferase-transgenic parasites, we obtained a phenomenon that sporozoites stay alive in the skin more than 24 hours after probing by infective mosquitoes. Forty-two hours after the probing, luciferase-transgenic parasites. were developed in the liver. We confirmed in the present study that liver is the specific organ for the malaria parasites for developing in number before invading in the erythrocytes. Furthermore we observed some lymph nodes giving luciferase activity at 42 hours after probing, suggesting that malaria parasites develop in the lymph nodes.