A glimpse into dorso‐ventral patterning of the Drosophila eye

Abstract

During organogenesis in all multi-cellular organisms, axial patterning is required to transform a single layer organ primordium into a three-dimensional organ. The Drosophila eye model serves as an excellent model to study axial patterning. Dorso-ventral (DV) axis determination is the first lineage restriction event during axial patterning of the Drosophila eye. The early Drosophila eye primordium has a default ventral fate, and the dorsal eye fate is established by onset of dorsal selector gene pannier (pnr) expression in a group of cells on the dorsal eye margin. The boundary between dorsal and ventral compartments called the equator is the site for Notch (N) activation, which triggers cell proliferation and differentiation. This review will focus on (1) chronology of events during DV axis determination; (2) how early division of eye into dorsal and ventral compartments contributes towards the growth and patterning of the fly retina, and (3) functions of DV patterning genes. Developmental Dynamics 241:69-84,

The Hippo pathway effector Yki downregulates Wg signaling to promote retinal differentiation in the Drosophila eye

“…Drosophila eyes are derived from a set of eye imaginal discs (Poulson, 1950;Cohen, 1993) that grow during larval stages, and each give rise to an adult compound eye comprising 800 unit eyes or ommatidia (Ready et al, 1976;Wolff and Ready, 1993;Kumar, 2011;Singh et al, 2012;Tare et al, 2013a). Each ommatidium is made up of ∼20 cells, including eight photoreceptor neurons and non-neuronal cells such as pigment cells, cone cells and bristles (Ready et al, 1976;Held, 2002;Roignant and Treisman, 2009;Kumar, 2011Kumar, , 2013Singh et al, 2012).…”

“…Each ommatidium is made up of ∼20 cells, including eight photoreceptor neurons and non-neuronal cells such as pigment cells, cone cells and bristles (Ready et al, 1976;Held, 2002;Roignant and Treisman, 2009;Kumar, 2011Kumar, , 2013Singh et al, 2012). Cell fate specification and differentiation in the developing eye field are regulated by a group of genes referred to as retinal determination (RD) genes (Pappu and Mardon, 2004;Roignant and Treisman, 2009;Kumar, 2011;Singh et al, 2012;Burgy-Roukala et al, 2013). These are twin of eyeless (toy), eyeless (ey), eyegone (eyg), twin of eyegone (toe), Optix, eyes absent (eya), sine oculis (so), dachshund (dac) and ophthalmosa (opt) (Bonini et al, 1993;Hanson et al, 1993;Cheyette et al, 1994;Mardon et al, 1994;Quiring et al, 1994;Seimiya and Gehring, 2000;Jang et al, 2003).…”

Cell proliferation control by Notch signalling during imaginal discs development in Drosophila

“…However, different reports have shown that the growth of the ventral region of the eye discs depends on the function of ventral genes like Lobe (L) and its downstream target Ser. The depletion of the function of these genes in the whole eye disc result in selective growth defects in the ventral half of the eye [38,91]. In addition, other reports suggest that ventral Notch clones show disrupted upd transcription.…”

Genomic Strategies for Terminal Cell Fate Specification

“…5.2(B3) is stereotypic, and is preserved throughout the eye, though it is represented in mirror image orientation on either side of the dorsal/ventral boundary which crosses the middle of the eye. The dorsal/ventral boundary is set up earlier, initially through expression of pannier in the dorsal compartment, which in turn activates the iroquois complex (Singh et al, 2012). In the orthogonal axis, comparing the right versus the left eye, the same ommatidial organization also presents mirror image symmetry.…”