The Fat Body of the Hematophagous Insect, Panstrongylus megistus (Hemiptera: Reduviidae): Histological Features and Participation of the β-Chain of ATP Synthase in the Lipophorin-Mediated Lipid Transfer

Abstract

In insects, lipid transfer to the tissues is mediated by lipophorin, the major circulating lipoprotein, mainly through a nonendocytic pathway involving docking receptors. Currently, the role of such receptors in lipid metabolism remains poorly understood. In this work, we performed a histological characterization of the fat body of the Chagas’ disease vector, Panstrongylus megistus (Burmeister), subjected to different nutritional conditions. In addition, we addressed the role of the β-chain of ATP synthase (β-ATPase) in the process of lipid transfer from lipophorin to the fat body. Fifth-instar nymphs in either fasting or fed condition were employed in the assays. Histological examination revealed that the fat body was composed by diverse trophocyte phenotypes. In the fasting condition, the cells were smaller and presented a homogeneous cytoplasmic content. The fat body of fed insects increased in size mainly due to the enlargement of lipid stores. In this condition, trophocytes contained abundant lipid droplets, and the rough endoplasmic reticulum was highly developed and mitochondria appeared elongated. Immunofluorescence assays showed that the β-ATPase, a putative lipophorin receptor, was located on the surface of fat body cells colocalizing partially with lipophorin, which suggests their interaction. No changes in β-ATPase expression were found in fasting and fed insects. Blocking the lipophorin–β-ATPase interaction impaired the lipophorin-mediated lipid transfer to the fat body. The results showed that the nutritional status of the insect influenced the morphohistological features of the tissue. Besides, these findings suggest that β-ATPase functions as a lipophorin docking receptor in the fat body.

Histopathology of Chironomus riparius (Diptera, Chironomidae) exposed to metal oxide nanoparticles

“…The types and concentrations of lipids in the insect fat body are variable under stress situations such as exposure to insecticides [55]. Such variations in fat body content may cause morphological changes in the tissue [56]. Nano-TiO2 particles can penetrate cells of the midgut and accumulate there, as noted in a study of Ceriodaphnia dubia [57].…”

Proteomic changes in various organs of Haemaphysalis longicornis under long-term starvation

“…This was corroborated in a study where succinate dehydrogenase, ATP synthase, and cytochrome c oxidase genes were up-regulated after three weeks of starvation in Paralichthys adspersus [ 27 ]. However, there was no significant increase in ATP synthase expression in the fat bodies of the blood sucking insect Panstrongylus megistus , which had been starved for 7 days [ 28 ]. This may be related to tissue specificity.…”

Gene Sequences of Potential Targets of Insecticidal PF2 Lectin Identified from the Larval De Novo Transcriptome of the Mexican Bean Weevil (Zabrotes Subfasciatus; Boheman 1833)

“…Other putative receptors for PF2 in Z. subfasciatus are mitochondrial ATP synthase and Vacuolar-type ATPase. While ATP synthase is mainly associated with cell energy production, recent reports indicate that the beta subunit of mitochondrial ATP synthase is also located on the plasma membrane of insect cells where it acts as receptor of a circulating lipoprotein for the midgut and fat body cells of Panstrongylus megistus, probably mediating lipid transfer to the insect's fat body [31]. Vacuolar-type ATPases belong to a family of ATP-dependent proton pumps relevant in various membrane trafficking pathways that also function to acidify the lumen of some organelles and cellular compartments.…”