Adhesive pad differentiation in Drosophila melanogaster depends on the Polycomb group gene Su(z)2

Abstract

The ability of many insects to walk on vertical smooth surfaces such as glass or even on the ceiling has fascinated biologists for ages and has led to the discovery of highly specialized adhesive organs located at the distal end of the animals' legs. So far, research has primarily focused on structural and ultrastructural investigations leading to a deeper understanding of adhesive organ functionality and to the development of new bioinspired materials. Genetic approaches, e.g. the analysis of mutants, to achieve a better understanding of adhesive organ differentiation, have not been used so far. Here, we describe the first Drosophila melanogaster mutant that develops malformed adhesive organs, resulting in a complete loss of climbing ability on vertical smooth surfaces. Interestingly, these mutants fail to make close contact between the setal tips and the smooth surface, a crucial condition for wet adhesion mediated by capillary forces. Instead, these flies walk solely on their claws. Moreover, we were able to show that the mutation is caused by a P-element insertion into the Su(z)2 gene locus. Remobilization of the P-element restores climbing ability. Furthermore, we provide evidence that the P-element insertion results in an artificial Su(z)2 transcript, which most likely causes a gain of function mutation. We presume that this transcript causes deregulation of yet unknown target genes involved in pulvilli differentiation. Our results nicely demonstrate that the genetically treatable model organism Drosophila is highly suitable for future investigations on adhesive organ differentiation.

The exceptional attachment ability of the ectoparasitic bee louse Braula coeca (Diptera, Braulidae) on the honeybee

“…The ventral face of the pulvilli is covered with setae known to be essential to generate adhesion on smooth surfaces due to capillary forces and van der Waals forces (Langer et al, 2004). Interestingly, each pulvillus has approximately 120–150 setae, while the closely related fruit fly D. melanogaster shows only about 30 setae per pulvillus (Hüsken et al, 2015). An increase in setal density leads to a higher real contact area with the substrate and higher attachment strength, given that the spatulate tips of the setae have similar dimensions.…”

Framework with cytoskeletal actin filaments forming insect footpad hairs inspires biomimetic adhesive device design

“…Drosophila melanogaster is a very useful model insect to study the mechanism of the development of footpads owing to the availability of several advanced genetic tools. The Drosophila melanogaster footpad houses many hairs, the tips of which have a spatula-like microstructure 9,10 . Recently, a mutant of the Polycomb group gene Su(z)2 with malformed adhesive pad structures was reported to affect the insect's climbing ability 10 .…”

“…The Drosophila melanogaster footpad houses many hairs, the tips of which have a spatula-like microstructure 9,10 . Recently, a mutant of the Polycomb group gene Su(z)2 with malformed adhesive pad structures was reported to affect the insect's climbing ability 10 . However, the molecular and cellular mechanisms underlying footpad formation remain largely unknown.…”

Drosophila pericardial nephrocyte ultrastructure changes during ageing

“…Preparation of Drosophila tissue for SEM has been previously described (Hüsken et al, 2015). After preparation, tissue was incubated in 100% ethanol then critical point dried (Balzer Union CPD010, Wiesbaden, Germany).…”