Project description:Coral disease is one of the major causes of reef degradation and therefore of concern to management and conservation efforts. Dark Spot Syndrome (DSS) was described in the early 1990’s as brown or purple amorphous areas of tissue on a coral and has since become one of the most prevalent diseases reported on Caribbean reefs. It has been identified in a number of coral species, but there is debate as to whether it is in fact the same disease in different corals. Further, it is questioned whether these macroscopic signs are in fact diagnostic of an infectious disease, since they can also be caused by physical injury in some species. The most commonly affected species in the Caribbean is the massive starlet coral Siderastrea siderea. We sampled this species in two geographic locations, Dry Tortugas National Park and Virgin Islands National Park. Tissue biopsies were collected from both healthy colonies with normal pigmentation and those with dark spot lesions. Microbial-community DNA was extracted from coral samples (mucus, tissue, and skeleton), amplified using bacterial-specific primers, and applied to PhyloChip™ G3 microarrays to examine the bacterial diversity associated with this coral. Samples were also screened for the presence of a fungal ribotype that has recently been implicated as a causative agent of DSS in another coral species, however the amplicon pools were overwhelmed by coral 18S rRNA genes from S. siderea. Unlike a similar study on a white-plague-like disease, S. siderea samples did not cluster consistently based on health state (i.e., normal versus dark spot). Various bacteria, including Cyanobacteria and Vibrios, were observed to have increased relative abundance in the discolored tissue, but the patterns were not consistent across all DSS samples. Overall, our findings do not support the hypothesis that DSS in S. siderea is linked to a bacterial pathogen or pathogens. This dataset provides the most comprehensive overview to date of the bacterial community associated with the healthy scleractinian coral S. siderea. 17 samples, coral tissue punches from healthy and also from dark-spot-affected Siderastrea Siderea coral in the Virgin Islands and the Dry Tortugas National Parks was collected for comparison of associated bacterial communities
Project description:Coral disease is one of the major causes of reef degradation and therefore of concern to management and conservation efforts. Dark Spot Syndrome (DSS) was described in the early 1990’s as brown or purple amorphous areas of tissue on a coral and has since become one of the most prevalent diseases reported on Caribbean reefs. It has been identified in a number of coral species, but there is debate as to whether it is in fact the same disease in different corals. Further, it is questioned whether these macroscopic signs are in fact diagnostic of an infectious disease, since they can also be caused by physical injury in some species. The most commonly affected species in the Caribbean is the massive starlet coral Siderastrea siderea. We sampled this species in two geographic locations, Dry Tortugas National Park and Virgin Islands National Park. Tissue biopsies were collected from both healthy colonies with normal pigmentation and those with dark spot lesions. Microbial-community DNA was extracted from coral samples (mucus, tissue, and skeleton), amplified using bacterial-specific primers, and applied to PhyloChip™ G3 microarrays to examine the bacterial diversity associated with this coral. Samples were also screened for the presence of a fungal ribotype that has recently been implicated as a causative agent of DSS in another coral species, however the amplicon pools were overwhelmed by coral 18S rRNA genes from S. siderea. Unlike a similar study on a white-plague-like disease, S. siderea samples did not cluster consistently based on health state (i.e., normal versus dark spot). Various bacteria, including Cyanobacteria and Vibrios, were observed to have increased relative abundance in the discolored tissue, but the patterns were not consistent across all DSS samples. Overall, our findings do not support the hypothesis that DSS in S. siderea is linked to a bacterial pathogen or pathogens. This dataset provides the most comprehensive overview to date of the bacterial community associated with the healthy scleractinian coral S. siderea.
2014-09-30 | GSE60622 | GEO
Project description:Xisha Islands
| PRJNA967315 | ENA
Project description:Foraminiferal 18S rRNA sequences from Xisha sediments
| PRJNA937323 | ENA
Project description:High-throughput sequencing of intestinal contents of nine herbivorous coral reef fishes from Xisha Islands, China
Project description:Iron-rich pelagic aggregates (iron snow) were collected directly onto silicate glass filters using an electronic water pump installed below the redoxcline. RNA was extracted and library preparation was done using the NEBNext Ultra II directional RNA library prep kit for Illumina. Data was demultiplied by GATC sequencing company and adaptor was trimmed by Trimgalore. After trimming, data was processed quality control by sickle and mRNA/rRNA sequences were sorted by SortmeRNA. mRNA sequences were blast against NCBI-non redundant protein database and the outputs were meganized in MEGAN to do functional analysis. rRNA sequences were further sorted against bacterial/archeal 16S rRNA, eukaryotic 18S rRNA and 10,000 rRNA sequences of bacterial 16S rRNA, eukaryotic 18S rRNA were subset to do taxonomy analysis.
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: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:The declining health of coral reefs worldwide is likely to intensify in response to continued anthropogenic disturbance from coastal development, pollution, and climate change. In response to these stresses, reef-building corals may exhibit bleaching, which marks the breakdown in symbiosis between coral and zooxanthellae. Mass coral bleaching due to elevated water temperature can devastate coral reefs on a large geographic scale. In order to understand the molecular and cellular basis of bleaching in corals, we have measured gene expression changes associated with thermal stress and bleaching using a cDNA microarray containing 1,310 genes of the Caribbean coral Montastraea faveolata. In a first experiment, we identified differentially expressed genes by comparing experimentally bleached M. faveolata fragments to control non-heat-stressed fragments. We also identified differentially expressed genes during a time course experiment with four time points across nine days. Results suggest that thermal stress and bleaching in M. faveolata affect the following processes: oxidative stress, Ca2+ homeostasis, cytoskeletal organization, cell death, calcification, metabolism, protein synthesis, heat shock protein activity, and transposon activity. These results represent the first large-scale transcriptomic study focused on revealing the cellular foundation of thermal stress-induced coral bleaching. We postulate that oxidative stress in thermal-stressed corals causes a disruption of Ca2+ homeostasis, which in turn leads to cytoskeletal and cell adhesion changes, decreased calcification, and the initiation of cell death via apoptosis and necrosis. Keywords: thermal stress response; coral bleaching 5 control and 5 heat-stressed RNA samples were hybridized in a 5-replicate dye-swap design (10 total hyb's).