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Microarray analysis identifies candidate genes for key roles in coral development.

Grasso LC, Maindonald J, Rudd S, Hayward DC, Saint R, Miller DJ, Ball EE - BMC Genomics (2008)

Bottom Line: Of 5081 unique peptide coding genes, 1084 were differentially expressed (P <or= 0.05) in comparisons between four different stages of coral development, spanning key developmental transitions.One surprising finding is that some of these genes have clear counterparts in higher animals but are not present in the closely-related sea anemone Nematostella.Secondly, coral-specific processes (i.e. traits which distinguish corals from their close relatives) may be analogous to similar processes in distantly related organisms.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for the Molecular Genetics of Development, Research School of Biological Sciences, Australian National University, Canberra, Australia. lauretta.grasso@anu.edu.au

ABSTRACT

Background: Anthozoan cnidarians are amongst the simplest animals at the tissue level of organization, but are surprisingly complex and vertebrate-like in terms of gene repertoire. As major components of tropical reef ecosystems, the stony corals are anthozoans of particular ecological significance. To better understand the molecular bases of both cnidarian development in general and coral-specific processes such as skeletogenesis and symbiont acquisition, microarray analysis was carried out through the period of early development - when skeletogenesis is initiated, and symbionts are first acquired.

Results: Of 5081 unique peptide coding genes, 1084 were differentially expressed (P

Conclusion: This study is the first large-scale investigation of developmental gene expression for any cnidarian, and has provided candidate genes for key roles in many aspects of coral biology, including calcification, metamorphosis and symbiont uptake. One surprising finding is that some of these genes have clear counterparts in higher animals but are not present in the closely-related sea anemone Nematostella. Secondly, coral-specific processes (i.e. traits which distinguish corals from their close relatives) may be analogous to similar processes in distantly related organisms. This first large-scale application of microarray analysis demonstrates the potential of this approach for investigating many aspects of coral biology, including the effects of stress and disease.

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Scanning electron micrographs of developmental stages in the Acropora millepora lifecycle. At spawning egg-sperm bundles are released by the colony and float to the surface, where they break up into individual eggs and sperm. Upon release and fertilization of the egg, cell division first produces a spherical bundle of cells which then flattens to form a cellular bilayer called the prawnchip (PC). Following gastrulation the spherical gastrula elongates to a pear shape as cilia develop. Further elongation produces a motile presettlement planula larvae (PL), possessing a highly differentiated endo- and ectoderm and an oral pore. Upon receipt of an appropriate cue, the larva settles and metamorphoses, forming the primary polyp (PO). Following calcification, symbiont uptake, and growth and branching, the adult colony is formed (A). The stages labelled with yellow letters represent those from which RNA was extracted, labelled and hybridized to the slides. Stages circled in red are those from which ESTs were spotted onto the slides.
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Figure 1: Scanning electron micrographs of developmental stages in the Acropora millepora lifecycle. At spawning egg-sperm bundles are released by the colony and float to the surface, where they break up into individual eggs and sperm. Upon release and fertilization of the egg, cell division first produces a spherical bundle of cells which then flattens to form a cellular bilayer called the prawnchip (PC). Following gastrulation the spherical gastrula elongates to a pear shape as cilia develop. Further elongation produces a motile presettlement planula larvae (PL), possessing a highly differentiated endo- and ectoderm and an oral pore. Upon receipt of an appropriate cue, the larva settles and metamorphoses, forming the primary polyp (PO). Following calcification, symbiont uptake, and growth and branching, the adult colony is formed (A). The stages labelled with yellow letters represent those from which RNA was extracted, labelled and hybridized to the slides. Stages circled in red are those from which ESTs were spotted onto the slides.

Mentions: Information and resources relevant to microarray studies on corals have recently been summarised [8]. Few precedents exist for the approach used here; the most directly relevant previous study is an array experiment comparing symbiotic and aposymbiotic sea anemones [9]. To gain insights into the molecular bases of coral development, including nematocyst formation, metamorphosis, and the processes of symbiont uptake and calcification, developmental microarray experiments were carried out using 12000 spot cDNA arrays representing 5081 Acropora millepora unigenes which, based on the EST sequence, are predicted to give rise to a bona fide protein. Four stages of coral development were compared, spanning the major transitions of gastrulation and metamorphosis (Figure 1). These comparisons, which constitute the most comprehensive analysis of the development of any cnidarian to date, provide insights into the overall dynamics of the transcriptome during development as well as candidate genes for roles in metamorphosis, calcification and symbiont uptake. Spatial expression patterns were determined for many of the candidate genes identified in the array experiments. Comparisons with Nematostella, Hydra and other animals imply that nominally coral specific processes are executed by both conserved and novel (taxon-specific) genes, and suggest some intriguing parallels with other systems.


Microarray analysis identifies candidate genes for key roles in coral development.

Grasso LC, Maindonald J, Rudd S, Hayward DC, Saint R, Miller DJ, Ball EE - BMC Genomics (2008)

Scanning electron micrographs of developmental stages in the Acropora millepora lifecycle. At spawning egg-sperm bundles are released by the colony and float to the surface, where they break up into individual eggs and sperm. Upon release and fertilization of the egg, cell division first produces a spherical bundle of cells which then flattens to form a cellular bilayer called the prawnchip (PC). Following gastrulation the spherical gastrula elongates to a pear shape as cilia develop. Further elongation produces a motile presettlement planula larvae (PL), possessing a highly differentiated endo- and ectoderm and an oral pore. Upon receipt of an appropriate cue, the larva settles and metamorphoses, forming the primary polyp (PO). Following calcification, symbiont uptake, and growth and branching, the adult colony is formed (A). The stages labelled with yellow letters represent those from which RNA was extracted, labelled and hybridized to the slides. Stages circled in red are those from which ESTs were spotted onto the slides.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2629781&req=5

Figure 1: Scanning electron micrographs of developmental stages in the Acropora millepora lifecycle. At spawning egg-sperm bundles are released by the colony and float to the surface, where they break up into individual eggs and sperm. Upon release and fertilization of the egg, cell division first produces a spherical bundle of cells which then flattens to form a cellular bilayer called the prawnchip (PC). Following gastrulation the spherical gastrula elongates to a pear shape as cilia develop. Further elongation produces a motile presettlement planula larvae (PL), possessing a highly differentiated endo- and ectoderm and an oral pore. Upon receipt of an appropriate cue, the larva settles and metamorphoses, forming the primary polyp (PO). Following calcification, symbiont uptake, and growth and branching, the adult colony is formed (A). The stages labelled with yellow letters represent those from which RNA was extracted, labelled and hybridized to the slides. Stages circled in red are those from which ESTs were spotted onto the slides.
Mentions: Information and resources relevant to microarray studies on corals have recently been summarised [8]. Few precedents exist for the approach used here; the most directly relevant previous study is an array experiment comparing symbiotic and aposymbiotic sea anemones [9]. To gain insights into the molecular bases of coral development, including nematocyst formation, metamorphosis, and the processes of symbiont uptake and calcification, developmental microarray experiments were carried out using 12000 spot cDNA arrays representing 5081 Acropora millepora unigenes which, based on the EST sequence, are predicted to give rise to a bona fide protein. Four stages of coral development were compared, spanning the major transitions of gastrulation and metamorphosis (Figure 1). These comparisons, which constitute the most comprehensive analysis of the development of any cnidarian to date, provide insights into the overall dynamics of the transcriptome during development as well as candidate genes for roles in metamorphosis, calcification and symbiont uptake. Spatial expression patterns were determined for many of the candidate genes identified in the array experiments. Comparisons with Nematostella, Hydra and other animals imply that nominally coral specific processes are executed by both conserved and novel (taxon-specific) genes, and suggest some intriguing parallels with other systems.

Bottom Line: Of 5081 unique peptide coding genes, 1084 were differentially expressed (P <or= 0.05) in comparisons between four different stages of coral development, spanning key developmental transitions.One surprising finding is that some of these genes have clear counterparts in higher animals but are not present in the closely-related sea anemone Nematostella.Secondly, coral-specific processes (i.e. traits which distinguish corals from their close relatives) may be analogous to similar processes in distantly related organisms.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for the Molecular Genetics of Development, Research School of Biological Sciences, Australian National University, Canberra, Australia. lauretta.grasso@anu.edu.au

ABSTRACT

Background: Anthozoan cnidarians are amongst the simplest animals at the tissue level of organization, but are surprisingly complex and vertebrate-like in terms of gene repertoire. As major components of tropical reef ecosystems, the stony corals are anthozoans of particular ecological significance. To better understand the molecular bases of both cnidarian development in general and coral-specific processes such as skeletogenesis and symbiont acquisition, microarray analysis was carried out through the period of early development - when skeletogenesis is initiated, and symbionts are first acquired.

Results: Of 5081 unique peptide coding genes, 1084 were differentially expressed (P

Conclusion: This study is the first large-scale investigation of developmental gene expression for any cnidarian, and has provided candidate genes for key roles in many aspects of coral biology, including calcification, metamorphosis and symbiont uptake. One surprising finding is that some of these genes have clear counterparts in higher animals but are not present in the closely-related sea anemone Nematostella. Secondly, coral-specific processes (i.e. traits which distinguish corals from their close relatives) may be analogous to similar processes in distantly related organisms. This first large-scale application of microarray analysis demonstrates the potential of this approach for investigating many aspects of coral biology, including the effects of stress and disease.

Show MeSH
Related in: MedlinePlus