Limits...
How Hox genes can shed light on the place of echinoderms among the deuterostomes.

David B, Mooi R - Evodevo (2014)

Bottom Line: Synthesis of available data helps to explain morphogenesis along the anterior/posterior axis of echinoderms, delineating the origins and fate of that axis during ontogeny.From this, it is easy to distinguish between 'seriality' along echinoderm rays and true A/P axis phenomena such as colinearity within the somatocoels, and the ontogenetic outcomes of the unique translocation and inversion of the anterior Hox class found within the Echinodermata.An up-to-date summary and integration of the disparate lines of research so far produced on the relationship between Hox genes and pattern formation for all deuterostomes allows for development of a phylogeny and scenario for the evolution of deuterostomes in general, and the Echinodermata in particular.

View Article: PubMed Central - HTML - PubMed

Affiliation: UMR CNRS 6282 Biogéosciences, Université de Bourgogne, 21000 Dijon, France.

ABSTRACT

Background: The Hox gene cluster ranks among the greatest of biological discoveries of the past 30 years. Morphogenetic patterning genes are remarkable for the systems they regulate during major ontogenetic events, and for their expressions of molecular, temporal, and spatial colinearity. Recent descriptions of exceptions to these colinearities are suggesting deep phylogenetic signal that can be used to explore origins of entire deuterostome phyla. Among the most enigmatic of these deuterostomes in terms of unique body patterning are the echinoderms. However, there remains no overall synthesis of the correlation between this signal and the variations observable in the presence/absence and expression patterns of Hox genes.

Results: Recent data from Hox cluster analyses shed light on how the bizarre shift from bilateral larvae to radial adults during echinoderm ontogeny can be accomplished by equally radical modifications within the Hox cluster. In order to explore this more fully, a compilation of observations on the genetic patterns among deuterostomes is integrated with the body patterning trajectories seen across the deuterostome clade.

Conclusions: Synthesis of available data helps to explain morphogenesis along the anterior/posterior axis of echinoderms, delineating the origins and fate of that axis during ontogeny. From this, it is easy to distinguish between 'seriality' along echinoderm rays and true A/P axis phenomena such as colinearity within the somatocoels, and the ontogenetic outcomes of the unique translocation and inversion of the anterior Hox class found within the Echinodermata. An up-to-date summary and integration of the disparate lines of research so far produced on the relationship between Hox genes and pattern formation for all deuterostomes allows for development of a phylogeny and scenario for the evolution of deuterostomes in general, and the Echinodermata in particular.

No MeSH data available.


Related in: MedlinePlus

Arrangement of the Hox cluster in major deuterostome clades.Evx and Mox genes, located in the vicinity of the Hox cluster, are also indicated. Tree topology is a synthesis of [17,23], and [113] for echinoderm clades. Terminals are based on data from taxa as follows: derived vertebrates on Mus (mouse); basal vertebrates on Lethenteron (lamprey); larvacean urochordates on Oikopleura; ascidian urochordates on Ciona; cephalochordates on Branchiostoma (amphioxus); hemichordates on Saccoglossus (acorn worm); crinoids on a combination of Metacrinus (sea lily) and Oxycomanthus (feather star); asteroids on a combination of Asterias and Patiriella (starfish); ophiuroids on Stegophiura (brittle star); holothuroids on Holothuria (sea cucumber); and echinoids on Strongylocentrotus (purple sea urchin). Note that for echinoderms, the alignments for the anterior class are shown in the recently discovered translocated, inverted condition. The nature of the lines through the complex on the right denotes the position of genes on a single (one continuous line), on few (several broken lines), or on many (no line) chromosomes. Putative arrangements are shown by dashed lines.
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Figure 2: Arrangement of the Hox cluster in major deuterostome clades.Evx and Mox genes, located in the vicinity of the Hox cluster, are also indicated. Tree topology is a synthesis of [17,23], and [113] for echinoderm clades. Terminals are based on data from taxa as follows: derived vertebrates on Mus (mouse); basal vertebrates on Lethenteron (lamprey); larvacean urochordates on Oikopleura; ascidian urochordates on Ciona; cephalochordates on Branchiostoma (amphioxus); hemichordates on Saccoglossus (acorn worm); crinoids on a combination of Metacrinus (sea lily) and Oxycomanthus (feather star); asteroids on a combination of Asterias and Patiriella (starfish); ophiuroids on Stegophiura (brittle star); holothuroids on Holothuria (sea cucumber); and echinoids on Strongylocentrotus (purple sea urchin). Note that for echinoderms, the alignments for the anterior class are shown in the recently discovered translocated, inverted condition. The nature of the lines through the complex on the right denotes the position of genes on a single (one continuous line), on few (several broken lines), or on many (no line) chromosomes. Putative arrangements are shown by dashed lines.

Mentions: Even a cursory survey among several non-echinoderm deuterostomes attests to the diversity of their Hox cluster organization, likely adding considerable complexity to their history (Figure 2).


How Hox genes can shed light on the place of echinoderms among the deuterostomes.

David B, Mooi R - Evodevo (2014)

Arrangement of the Hox cluster in major deuterostome clades.Evx and Mox genes, located in the vicinity of the Hox cluster, are also indicated. Tree topology is a synthesis of [17,23], and [113] for echinoderm clades. Terminals are based on data from taxa as follows: derived vertebrates on Mus (mouse); basal vertebrates on Lethenteron (lamprey); larvacean urochordates on Oikopleura; ascidian urochordates on Ciona; cephalochordates on Branchiostoma (amphioxus); hemichordates on Saccoglossus (acorn worm); crinoids on a combination of Metacrinus (sea lily) and Oxycomanthus (feather star); asteroids on a combination of Asterias and Patiriella (starfish); ophiuroids on Stegophiura (brittle star); holothuroids on Holothuria (sea cucumber); and echinoids on Strongylocentrotus (purple sea urchin). Note that for echinoderms, the alignments for the anterior class are shown in the recently discovered translocated, inverted condition. The nature of the lines through the complex on the right denotes the position of genes on a single (one continuous line), on few (several broken lines), or on many (no line) chromosomes. Putative arrangements are shown by dashed lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4066700&req=5

Figure 2: Arrangement of the Hox cluster in major deuterostome clades.Evx and Mox genes, located in the vicinity of the Hox cluster, are also indicated. Tree topology is a synthesis of [17,23], and [113] for echinoderm clades. Terminals are based on data from taxa as follows: derived vertebrates on Mus (mouse); basal vertebrates on Lethenteron (lamprey); larvacean urochordates on Oikopleura; ascidian urochordates on Ciona; cephalochordates on Branchiostoma (amphioxus); hemichordates on Saccoglossus (acorn worm); crinoids on a combination of Metacrinus (sea lily) and Oxycomanthus (feather star); asteroids on a combination of Asterias and Patiriella (starfish); ophiuroids on Stegophiura (brittle star); holothuroids on Holothuria (sea cucumber); and echinoids on Strongylocentrotus (purple sea urchin). Note that for echinoderms, the alignments for the anterior class are shown in the recently discovered translocated, inverted condition. The nature of the lines through the complex on the right denotes the position of genes on a single (one continuous line), on few (several broken lines), or on many (no line) chromosomes. Putative arrangements are shown by dashed lines.
Mentions: Even a cursory survey among several non-echinoderm deuterostomes attests to the diversity of their Hox cluster organization, likely adding considerable complexity to their history (Figure 2).

Bottom Line: Synthesis of available data helps to explain morphogenesis along the anterior/posterior axis of echinoderms, delineating the origins and fate of that axis during ontogeny.From this, it is easy to distinguish between 'seriality' along echinoderm rays and true A/P axis phenomena such as colinearity within the somatocoels, and the ontogenetic outcomes of the unique translocation and inversion of the anterior Hox class found within the Echinodermata.An up-to-date summary and integration of the disparate lines of research so far produced on the relationship between Hox genes and pattern formation for all deuterostomes allows for development of a phylogeny and scenario for the evolution of deuterostomes in general, and the Echinodermata in particular.

View Article: PubMed Central - HTML - PubMed

Affiliation: UMR CNRS 6282 Biogéosciences, Université de Bourgogne, 21000 Dijon, France.

ABSTRACT

Background: The Hox gene cluster ranks among the greatest of biological discoveries of the past 30 years. Morphogenetic patterning genes are remarkable for the systems they regulate during major ontogenetic events, and for their expressions of molecular, temporal, and spatial colinearity. Recent descriptions of exceptions to these colinearities are suggesting deep phylogenetic signal that can be used to explore origins of entire deuterostome phyla. Among the most enigmatic of these deuterostomes in terms of unique body patterning are the echinoderms. However, there remains no overall synthesis of the correlation between this signal and the variations observable in the presence/absence and expression patterns of Hox genes.

Results: Recent data from Hox cluster analyses shed light on how the bizarre shift from bilateral larvae to radial adults during echinoderm ontogeny can be accomplished by equally radical modifications within the Hox cluster. In order to explore this more fully, a compilation of observations on the genetic patterns among deuterostomes is integrated with the body patterning trajectories seen across the deuterostome clade.

Conclusions: Synthesis of available data helps to explain morphogenesis along the anterior/posterior axis of echinoderms, delineating the origins and fate of that axis during ontogeny. From this, it is easy to distinguish between 'seriality' along echinoderm rays and true A/P axis phenomena such as colinearity within the somatocoels, and the ontogenetic outcomes of the unique translocation and inversion of the anterior Hox class found within the Echinodermata. An up-to-date summary and integration of the disparate lines of research so far produced on the relationship between Hox genes and pattern formation for all deuterostomes allows for development of a phylogeny and scenario for the evolution of deuterostomes in general, and the Echinodermata in particular.

No MeSH data available.


Related in: MedlinePlus