Light-Mediated Control of Rhodopsin Movement in Mosquito Photoreceptors

in white-eyed Drosophila maintained under artificial light. Here we tested whether protein levels at rhabdoms change significantly in the highly pigmented lateral eyes of wild-caught Limulus polyphemus maintained in natural diurnal illumination and whether these changes are under circadian control. We found that rhabdomeral levels of opsins (Ops1-2), the G protein activated by rhodopsin (G q α) and arrestin change significantly from day to night and that nighttime levels of each protein at rhabdoms are significantly influenced by signals from the animalʼs central circadian clock. Clock input at night increases Ops1-2 and G q α and decreases arrestin levels at rhabdoms. Clock input is also required for a rapid decrease in rhabdomeral Ops1-2 beginning at sunrise. We found further that dark adaptation during the day and the night are not equivalent. During daytime dark adaptation, when clock input is silent, the increase of Ops1-2 at rhabdoms is small and G q α levels do not increase. However, increases in Ops1-2 and G q α at rhabdoms are enhanced during daytime dark adaptation by treatments that elevate cAMP in photoreceptors, suggesting that the clock influences dark-adaptive increases in Ops1-2 and G q α at Limulus rhabdoms by activating cAMP-dependent processes. The circadian regulation of Ops1-2 and G q α levels at rhabdoms probably has a dual role: to increase retinal sensitivity at night and to protect photoreceptors from light damage during the day.

Section: Rhops1-2 Levels Are Regulated By Complex Interactions Betweesupporting

confidence: 71%

Opsin1-2, Gqα and arrestin levels at Limulus rhabdoms are controlled by diurnal light and a circadian clock

Battelle

Kempler

Parker

et al. 2013

“…Horridge et al, 1981;Fleissner, 1982). Lightinduced movement of visual pigment and circadian changes in visual pigment levels have been demonstrated in mosquito photoreceptors (Hu et al, 2012). Differing secondary green sensitivity in the locust might, therefore, not be phase dependent, but daytime dependent.…”

Section: Phase-dependent Differences In Spectral Sensitivitymentioning

confidence: 99%

Opsin expression, physiological characterization and identification of photoreceptor cells in the dorsal rim area and main retina of the desert locust,Schistocerca gregaria

Schmeling

Wakakuwa

Tegtmeier

et al. 2014

For compass orientation many insects rely on the pattern of sky polarization, but some species also exploit the sky chromatic contrast. Desert locusts, Schistocerca gregaria, detect polarized light through a specialized dorsal rim area (DRA) in their compound eye. To better understand retinal mechanisms underlying visual navigation, we compared opsin expression, spectral and polarization sensitivities and response-stimulus intensity functions in the DRA and main retina of the locust. In addition to previously characterized opsins of long-wavelength-absorbing (Lo1) and blue-absorbing visual pigments (Lo2), we identified an opsin of an ultraviolet-absorbing visual pigment (LoUV). DRA photoreceptors exclusively expressed Lo2, had peak spectral sensitivities at 441 nm and showed high polarization sensitivity (PS 1.3-31.7). In contrast, ommatidia in the main eye co-expressed Lo1 and Lo2 in five photoreceptors, expressed Lo1 in two proximal photoreceptors, and Lo2 or LoUV in one distal photoreceptor. Correspondingly, we found broadband blueand green-peaking spectral sensitivities in the main eye and one narrowly tuned UV peaking receptor. Polarization sensitivity in the main retina was low (PS 1.3-3.8). V-log I functions in the DRA were steeper than in the main retina, supporting a role in polarization vision. Desert locusts occur as two morphs, a day-active gregarious and a night-active solitarious form. In solitarious locusts, sensitivities in the main retina were generally shifted to longer wavelengths, particularly in ventral eye regions, supporting a nocturnal lifestyle at low light levels. The data support the role of the DRA in polarization vision and suggest trichromatic colour vision in the desert locust.

“…Aaop1 is the major rhodopsin of the adult compound eye because it is expressed in all R1-R6 photoreceptors and most R8 photoreceptors (Hu et al, 2012). We made use of a larval whole-mount preparation to determine the onset of Aaop1 rhodopsin expression in the developing compound eye.…”

Section: Rhodopsin Expression In the Developing Adult Eyementioning

confidence: 99%

“…Three of these groups are labeled as long-wavelength (>500 nm), short-wavelength (400-500 nm), and UV-sensitive rhodopsin (<400 nm), and two of these groups contain uncharacterized family members. We previously characterized the patterns of rhodopsin expression in the adult Aedes compound eye (Hu et al, 2009(Hu et al, , 2011(Hu et al, , 2012(Hu et al, , 2014. These studies revealed features of the visual system in Aedes that were not predicted from study of other invertebrate models.…”

Section: Introductionmentioning

confidence: 99%

“…One noteworthy feature is the daily cycle of rhodopsin movement from the cytoplasm into the photosensitive rhabdomeric membranes at dusk and then back into the cytoplasm at dawn (Hu et al, 2012). The increased rhodopsin content within the rhabdom at night will increase light sensitivity, which is probably a valuable photoreceptor adaptation for acquisition of visual information in the dim light conditions where mosquitoes are most active.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Expression and light-triggered movement of rhodopsins in the larval visual system of mosquitoes

Rocha

Kimler

Leming

et al. 2015

During the larval stages, the visual system of the mosquito Aedes aegypti contains five stemmata, often referred to as larval ocelli, positioned laterally on each side of the larval head. Here we show that stemmata contain two photoreceptor types, distinguished by the expression of different rhodopsins. The rhodopsin Aaop3 (GPROP3) is expressed in the majority of the larval photoreceptors. There are two small clusters of photoreceptors located within the satellite and central stemmata that express the rhodopsin Aaop7 (GPROP7) instead of Aaop3. Electroretinogram analysis of transgenic Aaop7 Drosophila indicates that Aaop3 and Aaop7, both classified as longwavelength rhodopsins, possess similar but not identical spectral properties. Light triggers an extensive translocation of Aaop3 from the photosensitive rhabdoms to the cytoplasmic compartment, whereas light-driven translocation of Aaop7 is limited. The results suggest that these photoreceptor cell types play distinct roles in larval vision. An additional component of the larval visual system is the adult compound eye, which starts to develop at the anterior face of the larval stemmata during the 1st instar stage. The photoreceptors of the developing compound eye show rhodopsin expression during the 4th larval instar stage, consistent with indications from previous reports that the adult compound eye contributes to larval and pupal visual capabilities.