Response of Plasmodium refractory and susceptible strains of Anopheles gambiae to inoculated Sephadex beads.
A refractory strain of the mosquito, Anopheles gambiae, melanotically encapsulates and destroys malaria parasites in the midgut. Normal development of parasites is observed in a closely related susceptible strain. To examine the basis for the difference in response, the two strains were compared for responses to inoculated Sephadex beads of varying charge. Negatively charged C-25 beads elicited a much stronger reaction in the refractory strain where 49% of the beads were strongly melanized by 24 h, compared with only 5% in the susceptible strain. Male mosquitoes of each strain responded similarly, with 100% of the beads strongly melanized by 24 h in the refractory strain compared with only 5% in the susceptible strain males. A time course revealed that the melanization in refractory but not susceptible mosquitoes increases substantially over time; 91% of C-25 beads were melanized in refractory females at 72 h compared with 9% in the susceptible sample. Neutral G-25 beads and positively charged A-25 beads were melanized in both strains, demonstrating that the capacity to melanize foreign particles is present in susceptible mosquitoes.
Paskewitz
S
S
Department of Entomology, University of Wisconsin, Madison 53706.
Riehle
M A
MA
D000818:Animals; D000852:Anopheles / Q000469:parasitology / Q000502:physiology*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003911:Dextrans; D005260:Female; D006790:Host-Parasite Interactions; D007113:Immunity, Innate; D007303:Insect Vectors / Q000469:parasitology / Q000502:physiology*; D008297:Male; D008543:Melanins / Q000502:physiology; D008863:Microspheres; D014442:Monophenol Monooxygenase / Q000378:metabolism; D010961:Plasmodium / Q000502:physiology*; D012737:Sex Factors; D013045:Species Specificity
D003911:Dextrans; D008543:Melanins; C025614:sephadex; D014442:Monophenol Monooxygenase