Project description:Microarray technology provides a powerful tool for gene discovery studies, but the development of microarrays for individual species can be expensive and time-consuming. In this study, we test the suitability of a Danio rerio oligonucleotide microarray for application in a species with few genomic resources, the coral reef fish Pomacentrus moluccensis. Coral reef fishes are expected to experience rising sea surface temperatures due to climate change. How well tropical reef fish species will respond to these increased temperatures and which genes are important for resistance and adaptation to elevated temperatures is not known. Microarray technology may help identify candidate genes for thermal stress resistance in coral reef fishes. Results from a comparative genomic DNA hybridisation experiment and direct sequence comparisons indicate that for most genes there is significant sequence similarity between P. moluccensis and D. rerio, suggesting that the D. rerio array is applicable to P. moluccensis. Heterologous microarray experiments on heat-stressed P. moluccensis identified changes in transcript abundance at 120 gene loci, with many genes involved in protein processing, transcription, and cell growth. Changes in transcript abundance for a selection of candidate genes were confirmed by quantitative real-time PCR. We have demonstrated that heterologous microarrays can be successfully employed to study non-model organisms. Such a strategy thus greatly enhances the applicability of microarray technology to the field of environmental and functional genomics and will be useful for investigating the molecular basis of thermal adaptation in coral reef fishes. Keywords: stress response, comparative genomic hybridization (CGH)
Project description:The Crown-of-Thorns starfish (COTS), Acanthaster planci, is a highly fecund predator of reef-building corals distributed throughout the Indo-Pacific. COTS population outbreaks cause substantial loss of coral cover, diminishing the integrity and resilience of the reef ecosystems thus increasing their susceptibility to climate change. We sequenced genomes of A. planci from the Great Barrier Reef, Australia (GBR) and Okinawa, Japan (OKI) to guide identification of species-specific peptide communication with potential applications in mitigation strategies. The genome-encoded proteins excreted and secreted into the surrounding seawater by COTS forming aggregations and by those escaping the predatory giant triton snail, Charonia tritonis, were identified LC-MS/MS.
Project description:This experiment assessed the natural gene expression variation present between colonies of the Indo-Pacific reef-building coral Acropora millepora, and additionally explored whether gene expression differed between two different intron haplotypes according to intron 4-500 in a carbonic anhydrase homolog. This study found no correspondence between host genotype and transcriptional state, but found significant intercolony variation, detecting 488 representing unique genes or 17% of the total genes analyzed. Such transcriptomic variation could be the basis upon which natural selection can act. Underlying variation could potentially allow reef corals to respond to different environments. Whether this source of variation and the genetic responses of corals and its symbionts will allow coral reefs to cope to the rapid pace of global change remains unknown. A. millepora colonies were brought to a common garden in the reef lagoon, i.e. under the same environmental conditions. This common garden combined with acclimatization removes environmental effects on the physiology of the coral colonies. For the comparison of the two intron haplotypes, we applied a multiple dye-swap microarray design for the two groups of coral colonies (N=3 per group) defined based on the two genotypes resolved with the use of intron 4-500 (Fig. 1). To also examine the intra-haplotype variation we added a loop design nested to the above multiple dye-swap design, where three samples per colony were included. Colonies 1, 2, and 3 are of intron 4-500 haplotype 1; colonies 4, 5, and 6 are haplotype 2.
Project description:Microarray technology provides a powerful tool for gene discovery studies, but the development of microarrays for individual species can be expensive and time-consuming. In this study, we test the suitability of a Danio rerio oligonucleotide microarray for application in a species with few genomic resources, the coral reef fish Pomacentrus moluccensis. Coral reef fishes are expected to experience rising sea surface temperatures due to climate change. How well tropical reef fish species will respond to these increased temperatures and which genes are important for resistance and adaptation to elevated temperatures is not known. Microarray technology may help identify candidate genes for thermal stress resistance in coral reef fishes. Results from a comparative genomic DNA hybridisation experiment and direct sequence comparisons indicate that for most genes there is significant sequence similarity between P. moluccensis and D. rerio, suggesting that the D. rerio array is applicable to P. moluccensis. Heterologous microarray experiments on heat-stressed P. moluccensis identified changes in transcript abundance at 120 gene loci, with many genes involved in protein processing, transcription, and cell growth. Changes in transcript abundance for a selection of candidate genes were confirmed by quantitative real-time PCR. We have demonstrated that heterologous microarrays can be successfully employed to study non-model organisms. Such a strategy thus greatly enhances the applicability of microarray technology to the field of environmental and functional genomics and will be useful for investigating the molecular basis of thermal adaptation in coral reef fishes. Keywords: stress response, comparative genomic hybridization (CGH) Common reference design [Stress response_P. moluccensis]: four individual treatment fish (heat-stressed) are contrasted in four microarray hybridisations against a pooled control consisting of four fish kept at ambient temperature. All eight fish employed in this analysis were wild-captured and are biological replicates. The experiment included dye-swap, i.e. stressed fish were labelled red in two hybridisations and green in the other two hybridisations. Common reference design [CGH_P. moluccensis and D. rerio]: four individual P. moluccensis gDNA samples are contrasted in four microarray hybridisations against a pooled gDNA sample consisting of three D. rerio. The experiment included dye-swaps.
Project description:For sessile organisms at high risk from climate change, phenotypic plasticity can be critical to rapid acclimation. Epigenetic markers like DNA methylation are hypothesized as mediators of plasticity; methylation is associated with the regulation of gene expression, can change in response to ecological cues, and is a proposed basis for the inheritance of acquired traits. Within reef-building corals, gene body methylation can change in response to ecological stressors. If coral DNA methylation is transmissible across generations, this could potentially facilitate rapid acclimation to environmental change. We investigated methylation heritability in Acropora, a stony reef-building coral. Two A. millepora and two A. selago adults were crossed, producing eight offspring crosses (four hybrid, two of each species). We used whole-genome bisulfite sequencing to identify methylated loci and allele-specific alignments to quantify per-locus inheritance. If methylation is heritable, differential methylation (DM) between the parents should equal DM between paired offspring alleles at a given locus. We found a mixture of heritable and non-heritable loci, with heritable portions ranging from 44% to 90% among crosses. Gene body methylation was more heritable than intergenic methylation, and most loci had a consistent degree of heritability between crosses (i.e., the deviation between parental and offspring DM were of similar magnitude and direction). Our results provide evidence that coral methylation can be inherited but that heritability is heterogenous throughout the genome. Future investigations into this heterogeneity and its phenotypic implications will be important to understanding the potential capability of intergenerational environmental acclimation in reef building corals."
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:This experiment assessed the natural gene expression variation present between colonies of the Indo-Pacific reef-building coral Acropora millepora, and additionally explored whether gene expression differed between two different intron haplotypes according to intron 4-500 in a carbonic anhydrase homolog. This study found no correspondence between host genotype and transcriptional state, but found significant intercolony variation, detecting 488 representing unique genes or 17% of the total genes analyzed. Such transcriptomic variation could be the basis upon which natural selection can act. Underlying variation could potentially allow reef corals to respond to different environments. Whether this source of variation and the genetic responses of corals and its symbionts will allow coral reefs to cope to the rapid pace of global change remains unknown.
Project description:Acclimatization through phenotypic plasticity represents a more rapid response to environmental change than adaptation and is vital to optimize organisms’ performance in different conditions. Generally, animals are less phenotypically plastic than plants, but reef-building corals exhibit plant-like properties. They are light-dependent with a sessile and moddular construction that facilitates rapid morphological changes within their lifetime. We induced phenotypic changes by altering light exposure in a reciprocal transplant experiment and found that coral plasticity is a colony trait emerging from comprehensive morphological and physiological changes within the colony. Plasticity in skeletal features optimized coral light harvesting and utilization and paralleled with significant methylome and transcriptome modifications. Network-associated responses resulted in the identification of hub genes and clusters associated to the change in phenotype: inter-partner recognition and phagocytosis, soft tissue growth and biomineralization. Furthermore, we identified hub genes putatively involved in animal photoreception-phototransduction. These findings fundamentally advance our understanding of how reef-building corals repattern the methylome and adjust a phenotype, revealing an important role of light sensing by the coral animal to optimize photosynthetic performance of the symbionts.
Project description:Acclimatization through phenotypic plasticity represents a more rapid response to environmental change than adaptation and is vital to optimize organisms’ performance in different conditions. Generally, animals are less phenotypically plastic than plants, but reef-building corals exhibit plant-like properties. They are light-dependent with a sessile and moddular construction that facilitates rapid morphological changes within their lifetime. We induced phenotypic changes by altering light exposure in a reciprocal transplant experiment and found that coral plasticity is a colony trait emerging from comprehensive morphological and physiological changes within the colony. Plasticity in skeletal features optimized coral light harvesting and utilization and paralleled with significant methylome and transcriptome modifications. Network-associated responses resulted in the identification of hub genes and clusters associated to the change in phenotype: inter-partner recognition and phagocytosis, soft tissue growth and biomineralization. Furthermore, we identified hub genes putatively involved in animal photoreception-phototransduction. These findings fundamentally advance our understanding of how reef-building corals repattern the methylome and adjust a phenotype, revealing an important role of light sensing by the coral animal to optimize photosynthetic performance of the symbionts.