Project description:Two known settlement/metamorphosis inducing stimuli (crustose coralline algae, and ethanolic extract of crustose coralline algae) and one stimulus which just induces metamorphosis (LWamide) were used to stimulate competent planula larvae of the coral Acropora millepora. Samples were taken 0.5h, 4h and 12h post induction isolate the genes controlling settlement and metamorphosis in this coral.
Project description:Similar to many marine invertebrates, scleractinian corals experience a dramatic morphological transformation, as well as a habitat switch, upon settlement and metamorphosis. At this time, planula larvae transform from non-calcifying, demersal, motile organisms into sessile, calcifying, benthic juvenile polyps. We performed a gene expression microarray analysis between planulae, aposymbiotic primary polyps, and symbiotic adult tissue to elucidate the molecular mechanisms underlying coral metamorphosis and early stages of calcification in the Robust/Short clade scleractinian coral Montastraea faveolata. Among the annotated genes, the most abundant upregulated transcripts in the planula stage are involved in protein synthesis, chromatin assembly and mitochondrial metabolism; the polyp stage, morphogenesis, protein catabolism and organic matrix synthesis; and the adult stage, sexual reproduction, stress response and symbiosis. Additionally, our results indicate that metamorphosis in M. faveolata planulae is likely regulated by: 1) a mechanism that resembles that described for hydrozoan cnidarians involving the neuropeptide LWamide; and 2) conserved cell adhesion and apoptosis mechanisms. Our results also suggest that calicoblast differentiation pathways may be regulated by transforming growth factors from the BMP family and Notch signalling pathway. We also present evidence showing that the planula and adult transcriptomes are more similar to each other than to the polyp trancriptome. Lastly, our results point to a large number of uncharacterized adult coral-specific genes likely involved in coral-specific functions such as symbiosis and calcification.
