Figure 2.

TSC1 autonomously controls cell and organ size. (A) Scanning electron micrograph of a compound eye carrying a clone of homozygous TSC1²⁹ cells. The mutant clone occupies the upper half of the eye in the picture. Note that the TSC1 mutant ommatidia are larger than their wild-type counterparts. (B) Section through a TSC1²⁹ clone in the adult eye. The mutant clone is marked by the absence of pigment. The rhabdomeres of mutant photoreceptor cells are increased in area by about 80% compared with heterozygous photoreceptor cells (measured by Axiovision software). At the clone border, mosaic ommatidia containing normal-sized heterozygous cells (arrowhead) and enlarged homozygous TSC1 mutant cells (arrow) can be seen, indicating that TSC1 controls cell size autonomously. (C) Wing-margin bristles containing a TSC1²⁹ mutant clone. Note that the TSC1 mutant bristles (marked by y^-, indicated by a line above the wing margin) are thicker and longer than the wild-type bristles, which have a dark color. (D–E) Images of a wild-type eye-antenna disc (D) and an eye-antenna disc in which TSC1 function was selectively removed in the eye by using the ey-Flp technique (E). The discs were also stained for glass-lacZ that is expressed in retinal cells. These images were taken under the same magnification. Note that the TSC1^– eye disc is much larger than the wild-type disc.