Induction of actin gene expression in the mosquito midgut by blood ingestion correlates with striking changes of cell shape

Ingestion of a blood meal by the female mosquito Anopheles gambiae (L., Diptera: Culicidae), results in a dramatic distention of the midgut epithelium. Here, we report that these events correlate with a transient increase of actin mRNA and protein abundance. The newly synthesized actin may provide a pool of actin protein needed to remodel epithelial cell cytoarchitecture. We also document changes in midgut epithelial cell morphology. Upon blood ingestion, the columnar cells flatten accompanied by the loss of microvilli on the lumenal side and the unfolding of the labyrinth on the basal side. These changes correlate with the large increase of epithelial surface area needed to accommodate the blood meal. Actin gene expression, actin synthesis and cell morphology all return to the pre-feeding state by 24 h after blood intake.