In this work, we have analyzed the pathways by which
lipophorin (Lp) delivers its
lipid cargo to developing oocytes of Panstrongylus megistus, a hematophagous vector of
Chagas' disease. Lp,
vitellin, total
lipids and
proteins were measured in ovarian tissues at different stages of the reproductive cycle. Localization of Lp in developing oocytes, mainly at their cortical area, was demonstrated by immunofluorescence assays using an anti-Lp antibody labeled with
FITC. In vivo approaches injecting fluorescently labeled Lp to follow the course of the entire particle (Lp-DiI or Lp-Oregon
Green) or its
lipid cargo (Lp-
Bodipy-FA) were monitored by
laser scanning confocal microscopy. Significant increases in the amounts of
lipids,
proteins and
vitellin were observed in ovarian tissue with the progress of vitellogenesis. Unexpectedly, an increase in the amount of Lp was also observed. The experiments in vivo demonstrated that the uptake of fluorescent Lp labeled on its
protein or
lipid moiety by developing oocytes occurred very fast, being impaired at low temperatures. The co-injection of fluorescent Lp and
vitellogenin (Vg) showed that both particles co-localized inside yolk bodies, confirming the endocytic pathway for Lp. When the fate of
lipids transferred to oocytes was evaluated in vitellogenic females by co-injecting Lp-
Bodipy-FA and Lp-DiI, the signal for
Bodipy-FA was found in both lipid droplets and yolk bodies. In contrast, in injected females kept at 4°C the fluorescence was reduced, being observed exclusively in lipid droplets, implying that
lipid transfer to the oocyte was diminished but not abolished. Taken together, the results demonstrate that in the hematophagous P. megistus, the storage of
lipid resources by developing oocytes occurs by the convergence of different pathways by which Lp maximizes the delivery of its
lipid cargo. In addition, it was also shown that, to some extent,
lipids stored in the oocyte lipid droplets can also originate from endocytosed Vg. The relevance of these events in the context of the physiology of reproduction in P. megistus is discussed.