Patterns of dye coupling in the imaginal wing disk of Drosophila melanogaster

Abstract

Responses of developing tissues to experimental disruption demonstrate that cell interaction is important both in generating positional information and in controlling growth¹. However, the mechanism by which cells interact and the range over which the interactions are effective are not known. In the imaginai disks of Drosophila melanogaster, experiments on pattern regulation following surgical ablation suggest that the cell interactions are very local in nature; in fact, most of the data can be explained by assuming that cells interact only with their immediate neighbours². In contrast, studies of cell division patterns in the same tissue indicate that the ‘local’ proliferative response to an ablation extends over a distance of up to about eight cell diameters³. Still longer-range interactions have been proposed on the basis of theoretical considerations⁴. It is possible that the interactions are mediated by the transfer of small molecules through gap junctions, as gap junctions are abundant in imaginai disks at the appropriate developmental stages⁵. We have explored the range, timing and directionality of dye coupling between the cells of the wing disk as a test of the possible role of gap junctions in imaginai disk patterning. Our results indicate that interactions over different ranges are possible depending on the nature of the molecule being transferred.