Drosophila Glue: A Promising Model for Bioadhesion

Abstract

The glue produced by Drosophila larvae to attach themselves to a substrate for several days and resist predation until the end of metamorphosis represents an attractive model to develop new adhesives for dry environments. The adhesive properties of this interesting material have been investigated recently, and it was found that it binds as well as strongly adhesive commercial tapes to various types of substrates. This glue hardens rapidly after excretion and is made of several proteins. In D. melanogaster, eight glue proteins have been identified: four are long glycosylated mucoproteins containing repeats rich in prolines, serines and threonines, and four others are shorter proteins rich in cysteines. This protein mix is produced by the salivary glands through a complex packaging process that is starting to be elucidated. Drosophila species have adapted to stick to various substrates in diverse environmental conditions and glue genes appear to evolve rapidly in terms of gene number, number of repeats and sequence of the repeat motifs. Interestingly, besides its adhesive properties, the glue may also have antimicrobial activities. We discuss future perspectives and avenues of research for the development of new bioadhesives mimicking Drosophila fly glue.

Keywords: Drosophila; Sgs; bioadhesion; biomimetism; evolution; fly; glue; glycoprotein; mucin; salivary gland.

Figure 1

Distribution of Drosophila glue papers by year of publication and research topic. Five research topics are distinguished: (A) glue gene expression (70 articles), (B) glue gene identification (15 articles), (C) glue secretion (12 articles), (D) glue of other Drosophila species (12 articles), (E) salivary gland physiology (7 articles), (F) glue ultrastructure and adhesion (3 articles).

Figure 2

Drosophila pupae attached to various substrates. (A–C) D. melanogaster pupa attached with its own glue to a glass slide. Three pictures were taken of the same individual: (A) side view, (B) dorsal view, (C) ventral view throughout the glass slide. Anterior is up. White prints correspond to glue tracks on the glass slide or secretion from the larva before pupation. (D) Schematic transverse section of part of a D. melanogaster pupa attached to a glass slide with its own glue. Drawing based on confocal microscopy sections of Sgs3:GFP pupae obtained as in [21]. (E) First centimeters of soil made of wood chips from Bassevelle, France, where a Drosophila pupa (arrowhead) was found in July 2018. (F) Array of D. hydei pupae naturally attached to the plug within a laboratory vial. (G) Cluster of D. acanthoptera (Cornell University Drosophila Species Stock Center, stock #15090-1693.00) pupae found on the plastic wall of a laboratory vial. Scale bar is 1 mm in all panels except panel D, where it is 100 µm.