title: The genetics of colony form and function in Caribbean Acropora corals.
abstract: BACKGROUND
  Colonial reef-building corals have evolved a broad spectrum of colony morphologies based on coordinated asexual reproduction of polyps on a secreted calcium carbonate skeleton. Though cnidarians have been shown to possess and use similar developmental genes to bilaterians during larval development and polyp formation, little is known about genetic regulation of colony morphology in hard corals. We used RNA-seq to evaluate transcriptomic differences between functionally distinct regions of the coral (apical branch tips and branch bases) in two species of Caribbean Acropora, the staghorn coral, A. cervicornis, and the elkhorn coral, A. palmata.
  
  
  RESULTS
  Transcriptome-wide gene profiles differed significantly between different parts of the coral colony as well as between species. Genes showing differential expression between branch tips and bases were involved in developmental signaling pathways, such as Wnt, Notch, and BMP, as well as pH regulation, ion transport, extracellular matrix production and other processes. Differences both within colonies and between species identify a relatively small number of genes that may contribute to the distinct "staghorn" versus "elkhorn" morphologies of these two sister species.
  
  
  CONCLUSIONS
  The large number of differentially expressed genes supports a strong division of labor between coral branch tips and branch bases. Genes involved in growth of mature Acropora colonies include the classical signaling pathways associated with development of cnidarian larvae and polyps as well as morphological determination in higher metazoans.
authors.affiliation: Northeastern University, Marine Science Center, Nahant, MA, USA. lizhemond@gmail.com.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Hemond
authors.forename: Stefan T
authors.initials: ST
authors.lastname: Kaluziak
authors.forename: Steven V
authors.initials: SV
authors.lastname: Vollmer
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D019485:Bone Morphogenetic Proteins / Q000235:genetics; D020013:Calcium Signaling / Q000235:genetics; D002254:Carbonates / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing; D006863:Hydrogen-Ion Concentration; D008027:Light; D008903:Minerals / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics; D017423:Sequence Analysis, RNA; D013045:Species Specificity; D013312:Stress, Physiological / Q000235:genetics; D060449:Wnt Signaling Pathway / Q000235:genetics
chemical_list: D019485:Bone Morphogenetic Proteins; D002254:Carbonates; D008903:Minerals; D051880:Receptors, Notch