Nano-architecture of gustatory chemosensory bristles and trachea in Drosophila wings

Abstract

In the Drosophila wing anterior margin, the dendrites of gustatory neurons occupy the interior of thin and long bristles that present tiny pores at their extremities. Many attempts to measure ligand-evoked currents in insect wing gustatory neurons have been unsuccessful for technical reasons. The functions of this gustatory activity therefore remain elusive and controversial. To advance our knowledge on this understudied tissue, we investigated the architecture of the wing chemosensory bristles and wing trachea using Raman spectroscopy and fluorescence microscopy. We hypothesized that the wing gustatory hair, an open-ended capillary tube, and the wing trachea constitute biological systems similar to nano-porous materials. We present evidence that argues in favour of the existence of a layer or a bubble of air beneath the pore inside the gustatory hair. We demonstrate that these hollow hairs and wing tracheal tubes fulfil conditions for which the physics of fluids applied to open-ended capillaries and porous materials are relevant. We also document that the wing gustatory hair and tracheal architectures are capable of trapping volatile molecules from the environment, which might increase the efficiency of their spatial detection by way of wing vibrations or during flight.

Bristles reduce the force required to ‘fling’ wings apart in the smallest insects

“…Because insect wing bristles are not well studied, their physiological or mechanical importance remains a mystery. Bristles on insect wings could serve many different functions: reducing the weight of the insect (Sunada et al, 2002), providing an aerodynamic benefit (Davidi and Weihs, 2012;Santhanakrishnan et al, 2014), enhancing electrostatic charges to help in dispersal, similar to what has been suggested for spiders (Gorham, 2013 preprint), helping to fold and unfold the wings (Ellington, 1980), or acting as mechanosensory structures, similar to those in Drosophila (Valmalette et al, 2015). The last two roles, however, are not universal as most parasitoid wasps do not have hinges for folding and unfolding the bristles and it is not clear that all bristles are innervated.…”

The pleiotropic effects of Innexin genes expressed in Drosophila glia encompass wing chemosensory sensilla

“…First, in this report, we made the choice to investigate the adult wing tissue due to its extreme reduction in cellular types. The great advantages of wing tissue reside in the quasi‐exclusive presence of mechano‐ and chemosensilla along with few epithelial cells surrounding the veins, embedded in inert material made of chitin (Valmalette et al, ). This highly enriched material in sensilla with very little cellular contaminants allowed us to explore the presence and roles of innexin proteins at the interface glial cell/neuron.…”

“…Our data, corroborated by numerous studies, suggest a cascade of intra‐ and intercellular metabolic events after the opening of the channels in olfactory or gustatory cells (Getahun, Olsson, Lavista‐Llanos, Hansson, & Wicher, ; Ueno & Kidokoro, ; Ueno et al, ; Wicher et al, ). The Drosophila wing bristle microarchitecture has hampered the effort of electrophysiology studies, which explains that this tissue is up to date little studied (Valmalette et al, ). Ogre/Inx2 complex that make the gap junction assemblage have been described to coordinate synchronous calcium spikes in glial cells (Speder & brand, ).…”

A simple method for imaging axonal transport in aging neurons using the adult Drosophila wing

“…These can be used to correlate changes in transport processes with alterations in neuronal protein homeostasis. Expression of genetically encoded calcium sensors28,29, in combination with mechanical or chemical stimulation of wing margin bristles21,30, is a promising method for assessing neuronal activity during ageing and how it is altered by perturbations that influence transport. It should also be possible to use established fluorescent sensors of other cellular processes, such as oxidative stress31,32, in wing neurons.…”