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.
2009-12-07 | GSE11709 | GEO
Project description:ddRAD-Seq of Lord Howe Island staghorn ferns
| PRJNA647467 | ENA
Project description:Soil and root metabarcoding on Lord Howe Island
Project description:Scleractinian corals are the major builders of the complex structural framework of coral reefs. They live in tropical waters around the globe where they are frequently exposed to potentially harmful ultraviolet radiation (UVR). Coral eggs and early embryonic stages are thought to be the most sensitive life stages of corals to UVR given that they are highly buoyant and remain near the sea surface for prolonged periods of time. Here we analyzed gene expression changes in different larval stages of the Caribbean coral Montastraea faveolata to natural levels of UVR using high-density cDNA microarrays (10,930 clones). We found that larvae exhibit low sensitivity to natural levels of UVR during most time points analyzed as reflected by comparatively few transcriptomic changes in response to UVR. However, we identified a time window of high UVR sensitivity that coincides with the motile planula stage and the onset of larval competence. These processes have been shown to be affected upon UVR exposure, and the transcriptional changes we identified explain these observations well. Our analysis of differentially expressed genes indicates that UVR induces a stress response and affects the expression of neurogenesis-related genes that can be linked to swimming and settlement behavior at later stages. Taken together, our study provides further data to the impact of natural levels of UVR on coral larvae. Furthermore, our results might allow a better prediction of settlement and recruitment rates after coral spawning events based on UVR climate data.
Project description:Scleractinian corals are the major builders of the complex structural framework of coral reefs. They live in tropical waters around the globe where they are frequently exposed to potentially harmful ultraviolet radiation (UVR). Coral eggs and early embryonic stages are thought to be the most sensitive life stages of corals to UVR given that they are highly buoyant and remain near the sea surface for prolonged periods of time. Here we analyzed gene expression changes in different larval stages of the Caribbean coral Montastraea faveolata to natural levels of UVR using high-density cDNA microarrays (10,930 clones). We found that larvae exhibit low sensitivity to natural levels of UVR during most time points analyzed as reflected by comparatively few transcriptomic changes in response to UVR. However, we identified a time window of high UVR sensitivity that coincides with the motile planula stage and the onset of larval competence. These processes have been shown to be affected upon UVR exposure, and the transcriptional changes we identified explain these observations well. Our analysis of differentially expressed genes indicates that UVR induces a stress response and affects the expression of neurogenesis-related genes that can be linked to swimming and settlement behavior at later stages. Taken together, our study provides further data to the impact of natural levels of UVR on coral larvae. Furthermore, our results might allow a better prediction of settlement and recruitment rates after coral spawning events based on UVR climate data. Gamete capture and larval rearing Montastraea faveolata gametes were captured and reared as described in Voolstra et al. 2009 (2009a). Briefly, gametes from 10 colonies were captured during a spawning event on the night of the 10th of September 2009 at approximately 22:00 hours using collecting nets attached to plastic enclosures at “La Bocana Chica” (20º50´N, 86º52´W) located in the “Parque Nacional Arrecife de Puerto Morelos”. Within 10 minutes the gametes were brought to the research vessel “Carybdea”, where they were placed in 5 µm filtered sea water (FSW), large zooplankton was removed, and the egg-sperm mixture was mixed gently to enhance the process of fertilization during transportation to the research station (Unidad Académica Puerto Morelos). After 1 hour, the egg-sperm mixture was repeatedly washed with 5 µm FSW to ensure that all unused sperm and remaining zooplankton were removed. The embryos were placed in round, bottomless, incubation bins fitted with 100 µm mesh, which were housed in abundant 5 µm FSW. Fertilization success, measured 6 hours after the washing procedure, was estimated at 95% by counting the number of eggs undergoing division as a proportion of the total number of eggs (dividing + non-dividing). Experimental procedure After 12 hours, the majority of the embryos were in the late blastula stage. A subsample of embryos was taken from different incubation bins and divided into twelve 1 liter containers with 5 µm FSW added to the brim. Each container held approximately 3,000 embryos. All of the containers were placed in 800 L fiber glass aquaria filled with flowing sea water and exposed to natural solar radiation from 9am to 3pm (6h) at 29ºC and 3.5% salinity. Six of the containers were placed under a sheet of 6mm thick Plexiglass G UVT that has a full width at half maximum (FWHM) at 282 nm and is therefore transparent to UVR. The other six containers were placed under a sheet of 4 mm thick Plexiglass G UF-3 that has a FWHM at 390 nm and is therefore opaque to UVR. At the end of the exposure period, the embryos were harvested and preserved in RNAlater (Ambion), placed at 4ºC for 24 hours to ensure infiltration of the fixative and frozen at -80ºC until further processing. The same exposure and fixation procedures were repeated on 36 hours old embryos (late gastrula stage), on 60 hours old non-motile, floating larvae, on 84 hours old motile planulae, and on 132 hours old planulae that are motile, diving, and ready for settlement.
Project description: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. Methodology/ Principal Findings: Of approximately 5600 unique genes represented on the microarrays, 1084 were differentially expressed (P <0.05) in comparisons between four different stages of coral development, spanning key developmental transitions. Genes of likely relevance to the processes of settlement, metamorphosis, calcification and interaction with symbionts were characterised further and their spatial expression patterns investigated using whole-mount in situ hybridisation. Conclusions/Significance: 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. A second conclusion is that 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. Keywords: developmental
Project description:The potential to adapt to a changing climate depends in part upon the standing genetic variation present in wild populations. In corals, the dispersive larval phase is particularly vulnerable to the effects of environmental stress. Larval survival and response to stress during dispersal and settlement will play a key role in the persistence of coral populations. To test the hypothesis that larval transcription profiles reflect population specific responses to thermal stress, symbiont-free gametes of the scleractinian coral Montastraea faveolata were collected from Florida and Mexico and raised under normal and elevated temperatures. These populations have been shown to exchange larvae frequently enough to prevent significant differentiation of neutral loci. Differences among thousands of genes were simultaneously characterized using microarrays, allowing investigation of gene expression patterns among wild populations under stressful environmental conditions. Results show site-specific signatures of gene expression in larvae of a reef-building coral from different parts of its range (despite low genetic divergence), and reveal both local and general components of stress response during later stages of larval development. These results provide evidence of site-specific variation in the face of gene flow, which may represent functional genetic variation in different subpopulations, and support the idea that coral host genomes may indeed house the adaptive potential needed to deal with changing environmental conditions.
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.