Evolution, Development and Function of Vertebrate Cone Oil Droplets

Toomey, Matthew B.; Corbo, Joseph C.

doi:10.3389/fncir.2017.00097

Cited by 66 publications

(55 citation statements)

References 162 publications

(304 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This finding contrasts with the discovery of hundreds of differentially expressed genes between cone subtypes in developing chicken retina (33). The greater degree of transcriptomic divergence between avian cone subtypes might be attributable to the greater number of structural differences between subtypes, including the presence/absence of intracellular organelles such as oil droplets and paraboloids (34,35). Additionally, avian cone subtypes show differences in oil droplet pigmentation which is mediated by the differential expression of carotenoid-metabolizing enzymes and transporters (34,36,37).…”

Section: B Amentioning

confidence: 79%

“…The greater degree of transcriptomic divergence between avian cone subtypes might be attributable to the greater number of structural differences between subtypes, including the presence/absence of intracellular organelles such as oil droplets and paraboloids (34,35). Additionally, avian cone subtypes show differences in oil droplet pigmentation which is mediated by the differential expression of carotenoid-metabolizing enzymes and transporters (34,36,37). An alternative interpretation of our findings is that analysis of whole retina (rather than sorted cone subtypes) may have limited our ability to detect red cone-specific genes.…”

Section: B Amentioning

confidence: 99%

See 1 more Smart Citation

Thyroid hormone receptors mediate two distinct mechanisms of long-wavelength vision

Volkov

Kim-Han

Saunders

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

Thyroid hormone (TH) signaling plays an important role in the regulation of long-wavelength vision in vertebrates. In the retina,thyroid hormone receptor β(thrb) is required for expression of long-wavelength-sensitive opsin (lws) in red cone photoreceptors, while in retinal pigment epithelium (RPE), TH regulates expression of a cytochrome P450 enzyme,cyp27c1, that converts vitamin A1into vitamin A2to produce a red-shifted chromophore. To better understand how TH controls these processes, we analyzed the phenotype of zebrafish with mutations in the three known TH nuclear receptor transcription factors (thraa,thrab,and thrb). We found that no single TH nuclear receptor is required for TH-mediated induction ofcyp27c1but that deletion of all three (thraa−/−;thrab−/−;thrb−/−) completely abrogates its induction and the resulting conversion of A1- to A2-based retinoids. In the retina, loss ofthrbresulted in an absence of red cones at both larval and adult stages without disruption of the underlying cone mosaic. RNA-sequencing analysis revealed significant down-regulation of only five genes in adultthrb−/−retina, of which three (lws1,lws2, andmiR-726) occur in a single syntenic cluster. In thethrb−/−retina, retinal progenitors destined to become red cones were transfated into ultraviolet (UV) cones and horizontal cells. Taken together, our findings demonstrate cooperative regulation ofcyp27c1by TH receptors and a requirement forthrbin red cone fate determination. Thus, TH signaling coordinately regulates both spectral sensitivity and sensory plasticity.

show abstract

Section: B Amentioning

confidence: 79%

Section: B Amentioning

confidence: 99%

Thyroid hormone receptors mediate two distinct mechanisms of long-wavelength vision

Volkov

Kim-Han

Saunders

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…For example, MSP of blue-throated hummingbirds (Lampornis clemenciae) revealed the presence of the five typical oil droplet types found in birds, including the transparent type usually found in the UVS/VS cone type (62). In general, each oil droplet type is associated with a specific cone photoreceptor (i.e., the four single color cone types and the double cone) in birds (7,79). Their presence in hummingbirds therefore hints at a four-color cone-type system, although the MSP analysis (62) did not explicitly link oil droplets to their cone types and visual pigments.…”

Section: Methodsmentioning

confidence: 99%

Wild hummingbirds discriminate nonspectral colors

Stoddard

Eyster

Hogan

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Many animals have the potential to discriminate nonspectral colors. For humans, purple is the clearest example of a nonspectral color. It is perceived when two color cone types in the retina (blue and red) with nonadjacent spectral sensitivity curves are predominantly stimulated. Purple is considered nonspectral because no monochromatic light (such as from a rainbow) can evoke this simultaneous stimulation. Except in primates and bees, few behavioral experiments have directly examined nonspectral color discrimination, and little is known about nonspectral color perception in animals with more than three types of color photoreceptors. Birds have four color cone types (compared to three in humans) and might perceive additional nonspectral colors such as UV+red and UV+green. Can birds discriminate nonspectral colors, and are these colors behaviorally and ecologically relevant? Here, using comprehensive behavioral experiments, we show that wild hummingbirds can discriminate a variety of nonspectral colors. We also show that hummingbirds, relative to humans, likely perceive a greater proportion of natural colors as nonspectral. Our analysis of plumage and plant spectra reveals many colors that would be perceived as nonspectral by birds but not by humans: Birds’ extra cone type allows them not just to see UV light but also to discriminate additional nonspectral colors. Our results support the idea that birds can distinguish colors throughout tetrachromatic color space and indicate that nonspectral color perception is vital for signaling and foraging. Since tetrachromacy appears to have evolved early in vertebrates, this capacity for rich nonspectral color perception is likely widespread.

show abstract

“…Performance of diurnal birds is weakened in low light (Kelber & Lind 2010). Compared to nocturnal birds, diurnal birds have more colored oil dropletsspherical optical organelles within the sclera portion of the inner cone photoreceptor segment (Toomey & Corbo 2017). These droplets enhance color discrimination (Vorobyev 2003).…”

Section: Seasonal Pelage Color Changementioning

confidence: 99%

Seasonal pelage color change of two sympatric arboreal squirrel species in the subarctic region

Mitsuzuka

Kato

Oshida

2019

The European Zoological Journal

View full text Add to dashboard Cite

Some mammal species exhibit pelage color change with seasonal molt. Seasonal molt and pelage color change are beneficial to thermoregulation and concealment, associated with seasonal environmental change. The Eurasian red squirrel Sciurus vulgaris Linnaeus, 1758 and the Siberian flying squirrel Pteromys volans (Linnaeus, 1758) are arboreal and sympatrically distributed in the subarctic northern Eurasian Continent and Sakhalin and Hokkaido islands. We expect that diurnal S. vulgaris may demonstrate more conspicuous difference between summer and winter pelages than nocturnal P. volans, because of its protective coloration in each season. To test this conjecture, we investigated their seasonal pelage color change. To diminish the effect of geographic variation in pelage color, we chose S. vulgaris orientis Thomas, 1906 and P. volans orii (Kuroda, 1921), which are endemic subspecies of Hokkaido Island, Japan. We used skin and stuffed specimens and frozen materials and categorized them into two pelage groups (summer and winter pelages) based on collection date. Pelage color characteristics were measured with a spectrophotometer for lightness, redness and yellowness. Countershading was examined by comparing dorsal and ventral lightness. Both subspecies showed lighter winter pelage than summer pelage, suggesting their greyish-white winter pelage was beneficial to concealment from predators during winter. As we expected, seasonal changes of redness and yellowness were more clearly recognized in S. vulgaris than in P. volans. As S. vulgaris is diurnal and vulnerable to attack by diurnal avian predators, reddish and yellowish pelage patterns may be important for concealment. Because it is nocturnal, P. volans may not need this reddish and yellowish pelage. Sciurus vulgaris also had a remarkably counter-shaded body, indicating that its body may reduce predation risk from daytime visual predators. Differences in seasonal pelage color change of these two arboreal squirrels may be caused by their different circadian rhythms.

show abstract

Evolution, Development and Function of Vertebrate Cone Oil Droplets

Cited by 66 publications

References 162 publications

Thyroid hormone receptors mediate two distinct mechanisms of long-wavelength vision

Thyroid hormone receptors mediate two distinct mechanisms of long-wavelength vision

Wild hummingbirds discriminate nonspectral colors

Seasonal pelage color change of two sympatric arboreal squirrel species in the subarctic region

Contact Info

Product

Resources

About