Tryptophan hydroxylase Is Required for Eye Melanogenesis in the Planarian Schmidtea mediterranea.
Melanins are ubiquitous and biologically important pigments, yet the molecular mechanisms that regulate their synthesis and biochemical composition are not fully understood. Here we present a study that supports a role for serotonin in melanin synthesis in the planarian Schmidtea mediterranea. We ch...
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doaj-1401709bf73648b39dc05d2dd77e9d652020-11-25T01:56:05ZengPublic Library of Science (PLoS)PLoS ONE1932-62032015-01-01105e012707410.1371/journal.pone.0127074Tryptophan hydroxylase Is Required for Eye Melanogenesis in the Planarian Schmidtea mediterranea.Bramwell G LambrusOlivier Cochet-EscartinJiarong GaoPhillip A NewmarkEva-Maria S CollinsJames J CollinsMelanins are ubiquitous and biologically important pigments, yet the molecular mechanisms that regulate their synthesis and biochemical composition are not fully understood. Here we present a study that supports a role for serotonin in melanin synthesis in the planarian Schmidtea mediterranea. We characterize the tryptophan hydroxylase (tph) gene, which encodes the rate-limiting enzyme in serotonin synthesis, and demonstrate by RNA interference that tph is essential for melanin production in the pigment cups of the planarian photoreceptors. We exploit this phenotype to investigate the biological function of pigment cups using a quantitative light-avoidance behavioral assay. Planarians lacking eye pigment remain phototactic, indicating that eye pigmentation is not essential for light avoidance in S. mediterranea, though it improves the efficiency of the photophobic response. Finally, we show that the eye pigmentation defect observed in tph knockdown animals can be rescued by injection of either the product of TPH, 5-hydroxytryptophan (5-HTP), or serotonin. Together, these results highlight a role for serotonin in melanogenesis, perhaps as a regulatory signal or as a pigment substrate. To our knowledge, this is the first example of this relationship to be reported outside of mammalian systems.http://europepmc.org/articles/PMC4446096?pdf=render |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Bramwell G Lambrus Olivier Cochet-Escartin Jiarong Gao Phillip A Newmark Eva-Maria S Collins James J Collins |
spellingShingle |
Bramwell G Lambrus Olivier Cochet-Escartin Jiarong Gao Phillip A Newmark Eva-Maria S Collins James J Collins Tryptophan hydroxylase Is Required for Eye Melanogenesis in the Planarian Schmidtea mediterranea. PLoS ONE |
author_facet |
Bramwell G Lambrus Olivier Cochet-Escartin Jiarong Gao Phillip A Newmark Eva-Maria S Collins James J Collins |
author_sort |
Bramwell G Lambrus |
title |
Tryptophan hydroxylase Is Required for Eye Melanogenesis in the Planarian Schmidtea mediterranea. |
title_short |
Tryptophan hydroxylase Is Required for Eye Melanogenesis in the Planarian Schmidtea mediterranea. |
title_full |
Tryptophan hydroxylase Is Required for Eye Melanogenesis in the Planarian Schmidtea mediterranea. |
title_fullStr |
Tryptophan hydroxylase Is Required for Eye Melanogenesis in the Planarian Schmidtea mediterranea. |
title_full_unstemmed |
Tryptophan hydroxylase Is Required for Eye Melanogenesis in the Planarian Schmidtea mediterranea. |
title_sort |
tryptophan hydroxylase is required for eye melanogenesis in the planarian schmidtea mediterranea. |
publisher |
Public Library of Science (PLoS) |
series |
PLoS ONE |
issn |
1932-6203 |
publishDate |
2015-01-01 |
description |
Melanins are ubiquitous and biologically important pigments, yet the molecular mechanisms that regulate their synthesis and biochemical composition are not fully understood. Here we present a study that supports a role for serotonin in melanin synthesis in the planarian Schmidtea mediterranea. We characterize the tryptophan hydroxylase (tph) gene, which encodes the rate-limiting enzyme in serotonin synthesis, and demonstrate by RNA interference that tph is essential for melanin production in the pigment cups of the planarian photoreceptors. We exploit this phenotype to investigate the biological function of pigment cups using a quantitative light-avoidance behavioral assay. Planarians lacking eye pigment remain phototactic, indicating that eye pigmentation is not essential for light avoidance in S. mediterranea, though it improves the efficiency of the photophobic response. Finally, we show that the eye pigmentation defect observed in tph knockdown animals can be rescued by injection of either the product of TPH, 5-hydroxytryptophan (5-HTP), or serotonin. Together, these results highlight a role for serotonin in melanogenesis, perhaps as a regulatory signal or as a pigment substrate. To our knowledge, this is the first example of this relationship to be reported outside of mammalian systems. |
url |
http://europepmc.org/articles/PMC4446096?pdf=render |
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