Cuticle Refraction Microscopy: A Rapid and Simple Method for Imaging Drosophila Wing Topography, an Alternative Readout of Wing Planar Cell Polarity

Abstract

The polarity of hairs on the adult Drosophila wing provides information about the planar cell polarity (PCP) signaling events that occur during pupal wing development. We have recently shown that PCP signaling also determines the orientation of cuticle ridges that traverse the surface of the adult wing membrane; a feature we call the wing membrane topography. Although hair polarity is uniform across the wild-type wing, ridge orientation differs between the anterior and posterior wing. Consequently, mapping wing topography can provide additional information about PCP signaling, rather than simply confirming observations of wing hair polarity. Wing membrane ridges can be imaged using scanning electron microscopy, however, significant preparation time and operator expertise are required. Here, we describe cuticle refraction microscopy, a rapid and simple light microscopy method for imaging Drosophila wing topography.

Methods for studying planar cell polarity

“…For cases when it is hard to judge in which direction a hair points, it can be helpful to study the specimen in varying focal planes, and to compare with a sample with known polarity. For studying wing ridge polarity, as described by Collier and colleagues (Doyle et al, 2008; Hogan et al, 2011), cuticle refraction microscopy is useful (Neff et al, 2012). …”

Insect Wing Membrane Topography Is Determined by the Dorsal Wing Epithelium

“…To facilitate our studies of Drosophila wing topography, we developed a technique (CRM) that allows us to visualize Drosophila wing membrane ridges using light microscopy (Doyle et al 2008; Neff et al 2012). Using the CRM method, we found that membrane ridges are visible in light micrographs as bright lines against a dark background.…”

“…Our cuticle refraction microscopy (CRM) imaging protocol has been described in detail previously (Doyle et al 2008; Neff et al 2012). In brief, adult Drosophila wings were removed and laid gently on top of a thin layer of clear nail polish.…”