Cell Dynamics of Sex Comb Morphogenesis in Drosophila melanogaster

Yunlong Liang, Ellen W. Larsen, Juan Nicolas Malagon

Abstract


The sex comb (SC) of Drosophila melanogaster is a linear arrangement of bristles found on the basitarsus of male forelegs, and has long been considered an excellent model for studying evolutionary developmental biology. Although many of its developmental regulators have been discovered, how they are translated into cell dynamics and eventually SC morphology still remain unclear. Previous studies have demonstrated the dramatic remodeling of tarsal epithelium proximal and distal to SC during SC development displays a variety of cellular processes characteristic of systems modulated by surface mechanics. To explore the possibility of modulation of surface tension as the mechanism underlying SC ontogeny, we examined the effect of varying SC length on the cell dynamics of epithelial cells in the presumptive SC field. Confocal time series of SC morphogenesis in four lines of flies with increasingly longer SC were obtained and analyzed with ImageJ. Apical cell surface dimensions were measured and cell positions relative to landmark bristles were tracked. Our results demonstrated that changes in epithelial cell size and shape are closely correlated with the size of the SC being rotated. Furthermore, we showed that changes in cell position within the epithelium over time appeared to be random, and that cell intercalation is perhaps not actively contributing to SC rotation in contrast to what was previously believed. In summary, our findings provide evidence of association between epithelial remodeling and the size of SC. This study paves the way for future experiments in investigating the modulation of surface tension as the mechanism underlying SC morphogenesis.

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