INITIATION OF VITELLOGENIN UPTAKE AND PROTEIN-SYNTHESIS IN THE MOSQUITO (AEDES-AEGYPTI) OVARY IN RESPONSE TO A BLOOD MEAL

We studied the initiation of both vitellogenin endocytosis and non-vitellogenin protein synthesis in the mosquito ovary after a blood meal. Both these processes exhibited activation in two phases. The rate of endocytosis increased slowly during the first 2 h after feeding and was followed by a more rapid increase that peaked at 24 h after feeding. The rate of ovarian protein synthesis, which increased dramatically within the first 30 min after feeding, declined for the next 2 h and then increased again, gradually, reaching a peak at 8 h after a blood meal. Following a slight decline at 12 h, a steady rate was maintained for the next 12 h. Decapitation or isolation of the abdomen, within 5 min of the beginning of blood feeding, eliminated the second activation phase, but not the first one, for both these processes. In contrast, neither vitellogenin endocytosis nor ovarian protein synthesis was stimulated in abdomens isolated from previtellogenic females given an enema of blood and assayed 4 h late. The rate of ovarian protein synthesis became independent from the head at 8 h after feeding. In order to maintain the normal rates of vitellogenin endocytosis, the presence of the head was required for 16-20 h after a blood meal. Thus, both protein synthesis and vitellogenin endocytosis were first activated as a result of blood feeding itself. The second activation phase was also dependent on the head factors, and their continued release was essential for the maintenance of these ovarian functions.