[Relationship between hemolymph phenol oxidase and melanization of oocysts of Plasmodium yoelii in Anopheles stephensi].

OBJECTIVE: To explore the relationship between the hemolymph phenol oxidase and melanization of oocysts. METHODS: Anopheles stephensi-Plasmodium yoelii system was used to determine the activity of monophenol oxidase (MPO) and o-diphenol oxidase (o-DPO) in the hemolymph collected from 4 groups of mosquitoes by polyacrylamide gel electrophoresis (PAGE) followed by density scanning. The 4 groups of mosquitoes were: non-blood-fed (N), normal-blood-fed (B), infected-blood-fed (I) and nitroquine-administrated (D), respectively. RESULTS: No significant difference was found in the activities of MPO and o-DPO between groups N and B. The activities of MPO and o-DPO were not obviously modified in group I, but were significantly increased on day 10 and decreased on day 15 after blood feeding in the group D as compared with those in the groups N and B. CONCLUSION: The alteration in the mosquito hemolymph PO activity coincided at each time point with the melanization of Plasmodium yoelii oocysts.