Figure 1.

The organs that regulate energy homeostasis and may link obesity to lifespan. The tissues that share similar functions in Drosophila and humans are depicted in the same colors. The median neurosecretory cells of the fly brain produce Insulin-like peptides 2, 3, and 5 (Ilp2, 3, and 5), which act similarly to human insulin produced in the pancreatic beta cells. The Drosophila analog of human glucagon—adipokinetic hormone—is produced in the corpora cardiaca, whereas human glucagon is produced in the alpha cells of the pancreas. In the fly, fat and glycogen are stored in the fat body, which is an organ fulfilling the functions of the human adipose tissue and liver. The dorsal vessel (fly heart) is a linear tube that pumps hemolymph into the open circulatory system, and is considered as a functional counterpart of the human heart. Pericardial nephrocytes are cells that filter fly hemolymph, and share morphological and functional features with podocytes, cells of the kidney glomerulus. See the text for further details.