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Evolution of pigment synthesis pathways ..

Rausher and his colleagues are continuing their studies to explore the detailed pigment synthesis pathways of other morning glory species, including white-flowered and other red-flowered species. Such studies, said Rausher, could reveal yet more insights into how evolutionary pressures affected the biological machinery of pigment production.

Evolution of pigment synthesis pathway by gene and …

Spr is involved in both the de novo synthesis of H4bioterin and the production of pteridine pigment after the split between both component pathways (Figure ). Interestingly, the spr gene is found to be duplicated as result of the FSGD in zebrafish, stickleback and Tetraodon. It might be possible that each of the spr paralogs has become specialized for one component pathway, but expression data for duplicated teleost spr genes are not available at present. Sprb paralogs might have been lost quite recently in medaka as well as in Tetraodon after its split from Takifugu. This is a good example for the former observation that anciently duplicated genes still can be lost after millions of years [].

Evolution of pigment synthesis pathways by gene and genome ..

Evolution of pigment synthesis pathways by gene ..

Background. Coloration and color patterning belong to the most diverse phenotypic traits in animals. Particularly, teleost fishes possess more pigment cell types than any other group of vertebrates. As the result of an ancient fish-specific genome duplication (FSGD), teleost genomes might contain more copies of genes involved in pigment cell development than tetrapods. No systematic genomic inventory allowing to test this hypothesis has been drawn up so far for pigmentation genes in fish, and almost nothing is known about the evolution of these genes in different fish lineages. Results. Using a comparative genomic approach including phylogenetic reconstructions and synteny analyses, we have studied two major pigment synthesis pathways in teleost fish, the melanin and the pteridine pathways, with respect to different types of gene duplication. Genes encoding three of the four enzymes involved in the synthesis of melanin from tyrosine have been retained as duplicates after the FSGD. In the pteridine pathway, two cases of duplicated genes originating from the FSGD as well as several lineage-specific gene duplications were observed. In both pathways, genes encoding the rate-limiting enzymes, tyrosinase and GTP-cyclohydrolase I (GchI), have additional paralogs in teleosts compared to tetrapods, which have been generated by different modes of duplication. We have also observed a previously unrecognized diversity of gchI genes in vertebrates. In addition, we have found evidence for divergent resolution of duplicated pigmentation genes, i.e., differential gene loss in divergent teleost lineages, particularly in the tyrosinase gene family. Conclusion. Mainly due to the FSGD, teleost fishes apparently have a greater repertoire of pigment synthesis genes than any other vertebrate group. Our results support an important role of the FSGD and other types of duplication in the evolution of pigmentation in fish.

N2 - Background. Coloration and color patterning belong to the most diverse phenotypic traits in animals. Particularly, teleost fishes possess more pigment cell types than any other group of vertebrates. As the result of an ancient fish-specific genome duplication (FSGD), teleost genomes might contain more copies of genes involved in pigment cell development than tetrapods. No systematic genomic inventory allowing to test this hypothesis has been drawn up so far for pigmentation genes in fish, and almost nothing is known about the evolution of these genes in different fish lineages. Results. Using a comparative genomic approach including phylogenetic reconstructions and synteny analyses, we have studied two major pigment synthesis pathways in teleost fish, the melanin and the pteridine pathways, with respect to different types of gene duplication. Genes encoding three of the four enzymes involved in the synthesis of melanin from tyrosine have been retained as duplicates after the FSGD. In the pteridine pathway, two cases of duplicated genes originating from the FSGD as well as several lineage-specific gene duplications were observed. In both pathways, genes encoding the rate-limiting enzymes, tyrosinase and GTP-cyclohydrolase I (GchI), have additional paralogs in teleosts compared to tetrapods, which have been generated by different modes of duplication. We have also observed a previously unrecognized diversity of gchI genes in vertebrates. In addition, we have found evidence for divergent resolution of duplicated pigmentation genes, i.e., differential gene loss in divergent teleost lineages, particularly in the tyrosinase gene family. Conclusion. Mainly due to the FSGD, teleost fishes apparently have a greater repertoire of pigment synthesis genes than any other vertebrate group. Our results support an important role of the FSGD and other types of duplication in the evolution of pigmentation in fish.

Evolution of pigment synthesis pathways by ..

Total Synthesis of the Ocular Age Pigment A2-E: A Convergent Pathway

In the present studies, we have analyzed genes involved in the biosynthesis of the dark pigment melanin, which is produced by melanophores [,], and of the pteridine pigments synthesized in xanthophores (reviewed in []). We find that the FSGD had a deep impact on the melanin synthesis pathway, with three out of four enzyme-encoding genes being duplicates in teleosts. The pteridine synthesis pathway has been affected to a lesser degree by the FSGD, with two of nine enzymes represented by two teleost-specific paralogs. Several cases of lineage-specific duplication were also observed in the pteridine pathway. In both pathways, genes encoding the rate-limiting enzymes are duplicated in teleosts compared to tetrapods, with different modes of duplication being involved.

A major step in chromatophore differentiation is the biosynthesis of the pigment displayed by the respective type of pigment cells. Although there are sporadic reports of duplicated genes for pigment synthesis enzymes in specific teleost lineages [-], no systematic genomic analysis has been performed so far to determine the complete set of duplicated pigmentation genes in fish and to better understand how pigment synthesis pathways as a whole have been affected by the FSGD.

The Ras/Raf Signaling Pathway Mediates PEDF Synthesis in Human Retinal Pigment Epithelial Cells
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20/12/2006 · BMC Evolutionary Biology

AB - Background. Coloration and color patterning belong to the most diverse phenotypic traits in animals. Particularly, teleost fishes possess more pigment cell types than any other group of vertebrates. As the result of an ancient fish-specific genome duplication (FSGD), teleost genomes might contain more copies of genes involved in pigment cell development than tetrapods. No systematic genomic inventory allowing to test this hypothesis has been drawn up so far for pigmentation genes in fish, and almost nothing is known about the evolution of these genes in different fish lineages. Results. Using a comparative genomic approach including phylogenetic reconstructions and synteny analyses, we have studied two major pigment synthesis pathways in teleost fish, the melanin and the pteridine pathways, with respect to different types of gene duplication. Genes encoding three of the four enzymes involved in the synthesis of melanin from tyrosine have been retained as duplicates after the FSGD. In the pteridine pathway, two cases of duplicated genes originating from the FSGD as well as several lineage-specific gene duplications were observed. In both pathways, genes encoding the rate-limiting enzymes, tyrosinase and GTP-cyclohydrolase I (GchI), have additional paralogs in teleosts compared to tetrapods, which have been generated by different modes of duplication. We have also observed a previously unrecognized diversity of gchI genes in vertebrates. In addition, we have found evidence for divergent resolution of duplicated pigmentation genes, i.e., differential gene loss in divergent teleost lineages, particularly in the tyrosinase gene family. Conclusion. Mainly due to the FSGD, teleost fishes apparently have a greater repertoire of pigment synthesis genes than any other vertebrate group. Our results support an important role of the FSGD and other types of duplication in the evolution of pigmentation in fish.

Enzymes involved in pteridine pigment synthesis

According to Rausher, the evolution of the color of the morning glory flower is an excellent model to study such changes. Flower colors are produced by various members of the group of plant compounds called anthocyanins. These pigment molecules are synthesized by specialized biochemical pathways found in many plant species.

DOPA and DHN pathway orchestrate melanin synthesis …

The researchers also found subtle changes in enzyme functions that would favor production of the red pigment pathway in the red-flowered plant. Importantly, the researchers found such subtle changes in both the enzyme controlling the branch point in the pigment synthesis pathway, and in an important downstream gene. The gene change transformed the enzyme from a "generalist" that could act on either color pigment to one that could aid only synthesis of the red pigment.

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