Novel retinal photoreceptors

Soni, Bobby G.; Philp, Alisdair R.; Foster, Russell G.; Knox, Barry E.

doi:10.1038/27794

Cited by 119 publications

(66 citation statements)

References 4 publications

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“…This suggests that non-retinal opsins may require specialized conditions or proteins for proper folding. Recently, fish VA-opsin, expressed in Cos I cells, was shown to bind 11-cisretinal and undergo bleaching when exposed to light (62). The max of VA-opsin (465 nm) is very similar to that shown here for P-opsin.…”

Section: Discussionsupporting

confidence: 60%

Light-dependent Activation of Rod Transducin by Pineal Opsin

Max¹,

Surya²,

Takahashi³

et al. 1998

Journal of Biological Chemistry

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The pineal gland expresses a unique member of the opsin family (P-opsin; Max, M., McKinnon, P. J., Seidenman, K. J., Barrett, R. K., Applebury, M. L., Takahashi, J. S., and Margolskee, R. F. (1995) Science 267, 1502-1506) that may play a role in circadian entrainment and photo-regulation of melatonin synthesis. To study the function of this protein, an epitope-tagged P-opsin was stably expressed in an embryonic chicken pineal cell line. When incubated with 11-cis-retinal, a light-sensitive pigment was formed with a max at 462 ؎ 2 nm. P-opsin bleached slowly in the dark (t 1/2 ‫؍‬ 2 h) in the presence of 50 mM hydroxylamine. Purified P-opsin in dodecyl maltoside activated rod transducin in a light-dependent manner, catalyzing the exchange of more than 300 mol of GTP␥S (guanosine 5-O-(3-thiotriphosphate))/mol of P-opsin. The initial rate for activation (75 mol of GTP␥S bound/mol of P-opsin/min at 7 M) increased with increasing concentrations of transducin. The addition of egg phosphatidylcholine to P-opsin had little effect on the activation kinetics; however, the intrinsic rate of decay in the absence of transducin was accelerated. These results demonstrate that P-opsin is an efficient catalyst for activation of rod transducin and suggest that the pineal gland may contain a rodlike phototransduction cascade.

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Section: Discussionsupporting

confidence: 60%

Light-dependent Activation of Rod Transducin by Pineal Opsin

Max¹,

Surya²,

Takahashi³

et al. 1998

Journal of Biological Chemistry

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“…Accordingly, speciesto-species variations in tissue expression of AANAT-1 or AANAT-2 might reflect unique species-and tissue-dependent requirements for acetylation of serotonin and perhaps other arylalkylamines. Such biochemical and genetic variation is consistent with the anatomical and molecular diversity of these tissues (15,(32)(33)(34) and the important phototransduction roles the pineal gland and retina play in survival.…”

Section: Two Aanat Genes Explains Paradoxical Results In Pike-mentioning

confidence: 58%

Two Arylalkylamine N-Acetyltransferase Genes Mediate Melatonin Synthesis in Fish

Coon

Bégay

Deurloo

et al. 1999

Journal of Biological Chemistry

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Serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AANAT, EC 2.3.1.87) is the first enzyme in the conversion of serotonin to melatonin. Large changes in AANAT activity play an important role in the daily rhythms in melatonin production. Although a single AANAT gene has been found in mammals and the chicken, we have now identified two AANAT genes in fish. These genes are designated AANAT-1 and AANAT-2; all known AANATs belong to the AANAT-1 subfamily. Pike AANAT-1 is nearly exclusively expressed in the retina and AANAT-2 in the pineal gland. The abundance of each mRNA changes on a circadian basis, with retinal AANAT-1 mRNA peaking in late afternoon and pineal AANAT-2 mRNA peaking 6 h later. The pike AANAT-1 and AANAT-2 enzymes (66% identical amino acids) exhibit marked differences in their affinity for serotonin, relative affinity for indoleethylamines versus phenylethylamines and temperature-activity relationships. Two AANAT genes also exist in another fish, the trout. The evolution of two AANATs may represent a strategy to optimally meet tissue-related requirements for synthesis of melatonin: pineal melatonin serves an endocrine role and retinal melatonin plays a paracrine role.Melatonin is synthesized in two vertebrate tissues, the pineal gland and the retina (1-5). Production of melatonin is almost always under control of a circadian clock, with the highest levels occurring at night (6 -10). The pineal gland produces circulating melatonin, which serves as an endocrine signal of the night period. This signal of night length is important in circadian and seasonal physiology (11,12). In contrast, retinal melatonin functions as a paracrine signal within the retina to enhance retinal functioning under low light conditions. This is done by shifting the positions of the rods and cones and regulating the turnover rates of the photoreceptive apparatuses of the rods and cones and surrounding pigment epithelium (5,13,14).The enzyme which controls the circadian pattern of melatonin synthesis (serotonin 3 N-acetylserotonin 3 melatonin) is serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase; AANAT 1 ; E.C. 2.3.1.87) (15). Rhythms in AANAT activity in most vertebrates are driven by circadian clocks; light acts to reset and entrain these clocks. Light also acts independently via a downstream mechanism to turn off AANAT activity by initiating AANAT proteolysis (16).It has been generally thought that a single AANAT gene is expressed in both the pineal gland and retina. AANATs from various species are characterized by three highly conserved peptide sequences (C/c-1, D/c-1, and D/c-2; see Fig. 1) that have been proposed to be involved in arylalkylamine binding (15,17).The single AANAT gene hypothesis is consistent with the results from studies in mammals and the chicken, but not with those from studies in teleosts (bony fishes). Biochemical investigations of the Northern pike indicate that pineal and retinal AANAT have distinctly different affinities toward arylalkylamine substrates and different te...

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“…Discovered originally in teleosts [77], this photopigment is also found in many vertebrate classes [66] ( figure 5). Although the function of VA opsin in non-avian species is unknown, there is strong evidence to suggest that this pigment plays a critical role in regulating seasonal breeding in birds via direct hypothalamic photosensitive cells located deep in the brain [78,79].…”

Section: Loss Of Visual and Extra-ocular Photoreception And Photorecementioning

confidence: 99%

The nocturnal bottleneck and the evolution of activity patterns in mammals

et al. 2013

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In 1942, Walls described the concept of a 'nocturnal bottleneck' in placental mammals, where these species could survive only by avoiding daytime activity during times in which dinosaurs were the dominant taxon. Walls based this concept of a longer episode of nocturnality in early eutherian mammals by comparing the visual systems of reptiles, birds and all three extant taxa of the mammalian lineage, namely the monotremes, marsupials (now included in the metatherians) and placentals (included in the eutherians). This review describes the status of what has become known as the nocturnal bottleneck hypothesis, giving an overview of the chronobiological patterns of activity. We review the ecological plausibility that the activity patterns of (early) eutherian mammals were restricted to the night, based on arguments relating to endothermia, energy balance, foraging and predation, taking into account recent palaeontological information. We also assess genes, relating to light detection (visual and non-visual systems) and the photolyase DNA protection system that were lost in the eutherian mammalian lineage. Our conclusion presently is that arguments in favour of the nocturnal bottleneck hypothesis in eutherians prevail.

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Novel retinal photoreceptors

Cited by 119 publications

References 4 publications

Light-dependent Activation of Rod Transducin by Pineal Opsin

Light-dependent Activation of Rod Transducin by Pineal Opsin

Two Arylalkylamine N-Acetyltransferase Genes Mediate Melatonin Synthesis in Fish

The nocturnal bottleneck and the evolution of activity patterns in mammals

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