FIGURE 1.

Models to study regeneration. (A) Schematic view of third instar larvae indicating the brain, wing imaginal discs, and the gut. (B) Third instar wing imaginal discs in which apoptosis is induced in the pouch using a specific Gal4-promoter. (Left) The induction of the apoptotic gene occurs through a controlled temperature switch. At 18°C, Gal80 binds to Gal4, repressing its activity and preventing its expression. However, when the temperature is switched to 29°C, Gal80 expression is suppressed, releasing Gal4 from inhibition and initiating the expression of the apoptotic gene and cell death (Hariharan and Serras, 2017). (Middle) After a few hours, animals are switched to the permissive temperature of 18°C to block apoptosis, allowing regeneration to occur with the formation of the blastema (green) that expands until a fully recovered pouch is obtained (Right). (C) Representation of the adult gut with the zone that characterizes its function (R0-5) (Buchon et al., 2013). (D) Model of the midgut epithelium where regeneration occurs upon injury. Cells are color-coded as in panel (E), where the stem-cell niche is represented: ISC: Intestinal Stem Cell, EB: Enteroblast, EE: Enteroendocrine cell, EC: Enterocyte. (F) Schematic representation of the adult brain indicating the most common structures MB: mushroom body, OL: Optical Lobe. The inset represents a site of injury with neuron and glial cells represented in green and brown. (G) Representation of neuroblasts division. Neuroblasts (NB) divide asymmetrically, generating a ganglion mother cell (GMC), which then divides to produce a postmitotic neuron or glial cell (Homem and Knoblich, 2012). (H) Schematic representation of a third instar larva indicating the mushroom body (MB), the Optical lobe (OL) and the neurons (green). In red is a common site for injury in the Ventral Neural Cord (VNC). The figure was created using BioRender Premium, license (XV26VCD8GB), and further refined using Adobe Photoshop for its final appearance.