title: Gene expression patterns during the early stages of chemically induced larval metamorphosis and settlement of the coral Acropora millepora.
abstract: The morphogenetic transition of motile coral larvae into sessile primary polyps is triggered and genetically programmed upon exposure to environmental biomaterials, such as crustose coralline algae (CCA) and bacterial biofilms. Although the specific chemical cues that trigger coral larval morphogenesis are poorly understood there is much more information available on the genes that play a role in this early life phase. Putative chemical cues from natural biomaterials yielded defined chemical samples that triggered different morphogenetic outcomes: an extract derived from a CCA-associated Pseudoalteromonas bacterium that induced metamorphosis, characterized by non-attached metamorphosed juveniles; and two fractions of the CCA Hydrolithon onkodes (Heydrich) that induced settlement, characterized by attached metamorphosed juveniles. In an effort to distinguish the genes involved in these two morphogenetic transitions, competent larvae of the coral Acropora millepora were exposed to these predictable cues and the expression profiles of 47 coral genes of interest (GOI) were investigated after only 1 hour of exposure using multiplex RT-qPCR. Thirty-two GOI were differentially expressed, indicating a putative role during the early regulation of morphogenesis. The most striking differences were observed for immunity-related genes, hypothesized to be involved in cell recognition and adhesion, and for fluorescent protein genes. Principal component analysis of gene expression profiles resulted in separation between the different morphogenetic cues and exposure times, and not only identified those genes involved in the early response but also those which influenced downstream biological changes leading to larval metamorphosis or settlement.
authors.affiliation: Australian Institute of Marine Science, Townsville, Australia.
authors.forename: Nachshon
authors.initials: N
authors.lastname: Siboni
authors.affiliation: Australian Institute of Marine Science, Townsville, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Abrego
authors.affiliation: Australian Institute of Marine Science, Townsville, Australia.
authors.forename: Cherie A
authors.initials: CA
authors.lastname: Motti
authors.affiliation: School of Biological, Earth and Environmental Sciences, Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, Australia.
authors.forename: Jan
authors.initials: J
authors.lastname: Tebben
authors.affiliation: Australian Institute of Marine Science, Townsville, Australia; School of Biological, Earth and Environmental Sciences, Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, Australia.
authors.forename: Tilmann
authors.initials: T
authors.lastname: Harder
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000235:genetics*; D057894:Coral Reefs; D020869:Gene Expression Profiling; D008675:Metamorphosis, Biological / Q000235:genetics / Q000502:physiology*