STUDY ON THE RELATIONSHIP BETWEEN PROPHENOLOXIDASE IN THE MIDGUT OF ANOPHELES MOSQUITOES AND MELANIZATION IN OOCYSTS OF PLASMODIUM YOELII

Objective To explore the relationship between the melanotic encapsulation of Plasmodium yoelii and prophenoloxidase of the midgut by analysis the changes of prophenoloxidase in the midgut of Anopheles mosquitoes during melanotic encapsulation of oocysts of P. yoelii . Methods Midguts were dissected out from both Anopheles stephensi and An. dirus before and after infection with P. yoelii at 3、5、7、11 and 15 day. The homogenated midguts were analysed by SDSK-PAGE and Western blotting using Manduca sexta prophenoloxidase IgG polyantibody. The melanotic encapsulation of oocysts of P. yoelii was observed by microscope from 5 to 15 day after infection. Results One prophenoloxidase band with about molecular weight of 67 ku was displayed from both An. stephensi and An. dirus whether at pre-infection or at different days of post-infection with P. yoelii by Western blotting technique, and the prophenoloxidase bands were obviously enhanced after infection. However, the prophenoloxidase bands of midgut in the An. dirus were much more visible than those in the An. stephensi at the same time point after infection. Partial and complete melanotic encapsulation of P. yoelii in the midgut of An. dirus were observed from 7 to 15 day after infection. Conclusion The increasing content of prophenoloxidase in the midgut of Anopheles mosquitoes and keeping it for a long specially maybe have close correlation with the melanotic encapsulation of P. yoelii .