The spectral sensitivity ofDrosophilaphotoreceptors

Abstract

14Drosophila melanogaster has long been a popular model insect species, due in large part to 15 the availability of genetic tools and is fast becoming the model for insect colour vision. Key 16 to understanding colour reception in Drosophila is in-depth knowledge of spectral inputs 17 and downstream neural processing. While recent studies have sparked renewed interest in 18 colour processing in Drosophila, photoreceptor spectral sensitivity measurements have yet 19 to be carried out in vivo. We have fully characterised the spectral input to the motion and 20 colour vision pathways, and directly measured the effects of spectral modulating factors, 21 screening pigment density and carotenoid-based ocular pigments. All receptor sensitivities 22 had significant shifts in spectral sensitivity compared to previous measurements. Notably, 23 the spectral range of the Rh6 visual pigment is substantially broadened and its peak 24 sensitivity is shifted by 92 nm from 508 to 600 nm. We propose that this deviation can be 25 explained by transmission of long wavelengths through the red screening pigment and by 26 the presence of the blue-absorbing filter in the R7y receptors. Further, we tested direct 27 interactions between photoreceptors and found evidence of interactions between inner and 28 outer receptors, in agreement with previous findings of cross-modulation between receptor 29 outputs in the lamina. 30

A visual pathway for skylight polarization processing inDrosophila

“…1A). This specialized array of polarization detectors covers the complete 180° range of orientations and, with a peak spectral sensitivity to UV light, is well-suited to sensing the patterns of polarized light in the sky (Feiler et al, 1992;Salcedo et al, 1999;Sharkey et al, 2020;Weir et al, 2016). A previous characterization of DRA R7/R8 in Drosophila established the spatial organization of their tunings, and their visual response properties (Weir et al, 2016).…”

Synaptic targets of photoreceptors specialized to detect color and skylight polarization in Drosophila

“…These connectivity patterns suggest roles in circadian entrainment and learning and memory, respectively (Figure 11Bii). Drosophila pale R8 cells are most sensitive to blue wavelengths (Sharkey et al 2020; Salcedo et al 1999; Schnaitmann et al 2018; Heath et al 2020), and the projections of aMe12 and ML-VPN1 demonstrate that blue light is processed and used by the central brain within one synapse. Little is known about the central processing of color in Drosophila (Longden 2016), but the detection of blue light plays an important role in the circadian avoidance of bright light (Lazopulo et al 2019).…”

The olfactory gating of visual preferences to human skin and colors in mosquitoes

“…This was further demonstrated by the ERG responses to long (red) wavelengths. Recent work in Drosophila has shown that photopigments provide a mechanism for flies to detect orange and red wavelengths 32 , and it is possible that similar processes play a role in mosquitoes.…”