INVITRO DAMAGE OF CULTURED OOKINETES OF PLASMODIUM-GALLINACEUM BY DIGESTIVE PROTEINASES FROM SUSCEPTIBLE AEDES-AEGYPTI
- 1 January 1979
- journal article
- research article
- Vol. 36 (3) , 243-252
Abstract
After exposure to extracts from blood-fed A. aegypti cultured ookinetes of P. gallinaceum (a blood parasite of chickens) were damaged to various, defined extents. Immature ookinetes were more sensitive to damage than mature ones. Damage was dependent on the digestion time after which the A. aegypti extracts had been prepared and was correlated with the proteolytic activity in the extracts. Control experiments demonstrated that the factors responsible for damage were neither present in unfed mosquitoes nor in blood alone and that the damage was not a result of osmotic stress. After treatment of the A. aegypti extracts with lima bean trypsin inhibitor, the ookinete damage was much less, indicating that the A. aegypti trypsin was the major agent of damage. These results were supported by experiments in which the tryptic activity of the extracts was eliminated by thermal denaturation. In the mosquito midgut most of the ookinetes are damaged by digestive enzymes and this is 1 factor leading to the discrepancy between the number of ingested macrogametocytes and the number of oocysts which is usually found in nature. It seems that the only ookinetes which have a chance of surviving are those which develop in the center of the blood clot, away from the site of enzyme action.This publication has 0 references indexed in Scilit: