Timing is everything….from the fluke encounter in a romantic comedy, to your rush to make the bus/train/plane this morning, to the development of an organism. Today’s image is from a paper describing the temporal patterning involved in the development of the fruit fly optic lobe.
In the fruit fly optic lobe, the medulla processes visual information using 40,000 neurons of over 70 different cell types. The medulla develops from a crescent-shaped tissue from which the neuronal progenitors divide, requiring several different transcription factors. A recent paper describes the sequential patterning of five transcription factors as the medulla neuroblasts age. Li and colleagues found that this temporal patterning of transcription factors is necessary for the diversity of cell types found in the medulla. The images of the developing medulla above show the sequential expression of these five transcription factors—Homothorax (Hth), Eyeless (Ey), Sloppy paired 1 and 2 (Slp), Dichaete (D), and Tailless (Tll)—in five consecutive stripes. Hth is found in the youngest neuroblasts. Ey, Slp, and D are required for turning on the next transcription factor in the cascade. Slp and D are also required for turning off the preceding transcription factor.
Li X, Erclik T, Bertet C, Chen Z, Voutev R, Venkatesh S, Morante J, Celik A, & Desplan C (2013). Temporal patterning of Drosophila medulla neuroblasts controls neural fates. Nature, 498 (7455), 456-62 PMID: 23783517
Adapted by permission from Macmillan Publishers Ltd, copyright ©2013