Location of Iron and Ferritin in the Midgut of the yellow fever mosquito, Aedes aegypti

Abstract

Dengue and Yellow Fever are caused by viruses transmitted by mosquitoes that each year infect 390 million and 200,000 people, respectively, and cause more than 2 million deaths. For mosquito eggs to develop and produce viable offspring, iron is required as an essential nutrient from the blood meal. Our previous research has shown iron from the blood meal is absorbed and transported by ferritin from the midgut to the ovaries in Aedes aegypti (yellow fever mosquito). Thus, understanding iron accumulation and utilization in the mosquito midgut is important to finding potential strategies to interfere with mosquito fecundity, decrease mosquito populations, and reduce transmission rates of vector‐borne diseases. However, it is unknown where in the midgut iron accumulates after a blood meal. To demonstrate this, Ae. aegypti midguts were dissected from sugar fed, 24 h post‐blood meal (PBM), and 72 h PBM animals to measure tissue iron accumulation after a blood meal by iron inductively coupled plasma mass spectrometry (ICP‐MS). Dissected midguts were also stained with Prussian Blue to visualize ferric iron deposition. Our results indicate that iron is present in the midgut prior to a blood meal, accumulates at 24 h PBM, and decreases by 72 h PBM, and the deposition of ferric iron is observed throughout the tissue before and after a blood meal. Further, immunohistochemistry studies of the midguts show three different subunits of the iron storage and transport protein, ferritin. Coalescence of ferritin and iron in mosquito midguts confirms the role of ferritin in this tissue for export of iron to other tissues, including the ovaries for oogenesis and ovarian homeostasis.Support or Funding InformationThis research was supported by funds from the Arizona Agricultural Experiment Station, the College of Agriculture and Life Sciences, the Undergraduate Biology Research Program, and the Honors College at the University of Arizona.