Project description:Corals especially the reef-building species are very important to marine ecosystems. Proteomics has been used for researches on coral diseases, bleaching and responses to the environment change. Corals especially the reef-building species are very important to marine ecosystems. Proteomics has been used for researches on coral diseases, bleaching and responses to the environment change. In the present study, five protocols were compared for protein extraction from stony corals.
Project description:Scleractinian corals acquire autotrophic nutrients via the photosynthetic activity of their symbionts and the subsequent transfer of photosynthates. Zooplankton predation by the animal (heterotrophy) is an additional food source. Under stress events, corals loose their symbionts, a phenomena known as bleaching, which eventually leads to starvation, unless corals increase their heterotrophic capacities. Molecular mechanisms by which heterotrophy sustains metabolism in stressed corals remain elusive. Here for the first time, we identify specific genes expressed in heterotrophically fed and unfed corals maintained under normal and light-stress conditions inducing bleaching. Physiological parameters and gene expression profiling showed ominously that fed corals better resisted the stress than unfed corals, by presenting less oxidative damage and protein/DNA degradation. Light stressed and unfed/starved corals (HLS) up-regulated by 140 and 13 times two genes (CP2U1 and CP1A2), which belong to the Cytochrome P450 superfamily, while these genes remained almost unchanged in fed corals (HLF). Other genes of redox regulation, DNA damage response, molecular chaperones, and protein degradation were also up-regulated in HLS corals, presenting higher bleaching, and strong decrease of the photosynthesis performance compared to HLF corals. Several pivotal genes associated with the calcification apparatus such as carbonic anhydrases, calcium-transporting ATPase, calcium channel subunit, and bone morphogenetic proteins (BMPs), were significantly down-regulated only in HLS corals. A parallel decrease in the calcification rates of these later corals was also observed. All together, these results show clearly that heterotrophy helps preventing oxidative stress in corals, and thus avoid the cascade of metabolic problems downstream this stress.
Project description:Black corals, ecologically important cnidarians found from shallow to deep ocean depths, form a strong yet flexible skeleton of sclerotized chitin and other biomolecules including proteins. The structure and mechanical properties of the chitin component of the skeleton have been well-characterized. However, the protein component has remained a mystery. Here we used liquid chromatography-tandem mass spectrometry to sequence proteins extracted from two species of common Red Sea black corals following either one or two cleaning steps. We detected hundreds of proteins between the two corals, nearly 70 of which are each others’ reciprocal best BLAST hit. Unlike stony corals, only a few of the detected proteins were moderately acidic (biased toward aspartic and/or glutamic acid residues) suggesting less of a role for these types of proteins in black coral skeleton formation as compared to stony corals. No distinct chitin binding domains were found in the proteins, but proteins annotated as having a role in protein and chitin modifications were detected. Our results support the integral role of proteins in black coral skeleton formation, structure, and function.
