Project description:Background. Coral reef communities are undergoing marked declines due to a variety of stressors including climate change, eutrophication, sedimentation, and disease. The sea fan coral, Gorgonia ventalina, is a tractable study system to investigate the hypothesis that stressors compromise immunity and lead to onset of disease. Functional studies in Gorgonia ventalina immunity indicate that several key pathways and cellular responses are involved in response to natural microbial invaders, although to date the functional and regulatory pathways remain largely un-neffectors, the primary line of defense in invertebrates. This study used short-read sequencing (Illumina GAIIx) to identify genes involved in the response of G. ventalina to a naturally occurring Aplanochytrium spp. parasite. Results. De novo assembly of the G. ventalina transcriptome yielded 90,230 contigs of which 40, 142 were annotated. RNA-Seq analysis revealed 210 differentially expressed genes in sea fans exposed to the Aplanochytrium parasite. Differentially expressed genes involved in immunity include pattern recognition molecules, anti-microbial peptides, wound repair, and reactive oxygen species. Gene enrichment analysis indicated eight biological processes were enriched representing 36 genes, largely involved with protein translation and energy production. Conclusions. This is the first report using high-throughput sequencing to characterize the host response of a coral to a natural pathogen. Furthermore, we have generated the first transcriptome for a soft coral species. G. ventalina is a non-model species for which few sequences had been previously described, and we were able to annotate a large number of genes and describe their potential roles in immune function. Expression analysis revealed genes important in invertebrate innate immune pathways, as well as those whose role is previously un-described in cnidarians. This resource will be valuable in characterizing G. ventalina immune response to infection and co-infection of pathogens in the context of environmental change.

Project description:The interplay among environment, demography, and host-parasite interactions is a challenging frontier. In the ocean, fundamental changes are occurring due to anthropogenic pressures, including increased disease outbreaks on coral reefs. These outbreaks include multiple parasites, calling into question how host immunity functions in this complex milieu. Our work investigates the interplay of factors influencing co-infection in the Caribbean sea fan octocoral, Gorgonia ventalina, using metrics of the innate immune response: cellular immunity and expression of candidate immune genes. We used existing copepod infections and live pathogen inoculation with the Aspergillus sydowii fungus, detecting increased expression of the immune recognition gene Tachylectin 5A (T5A) in response to both parasites. Cellular immunity increased by 8.16% in copepod infections compared to controls and single Aspergillus infections. We also detected activation of cellular immunity in reef populations, with a 13.6% increase during copepod infections. Cellular immunity was similar in the field and in the lab, increasing with copepod infections and not the fungus. Amoebocyte density and the expression of T5A and a matrix metalloproteinase (MMP) gene were also positively correlated across all treatments and colonies, irrespective of parasitic infection. We then assessed the scaling of immune metrics to population-level disease patterns and found random co-occurrence of copepods and fungus across 15 reefs in Puerto Rico. The results suggest immune activation by parasites may not alter parasite co-occurrence if factors other than immunity prevail in structuring parasite infection. We assessed non-immune factors in the field and found that sea fan colony size predicted infection by the copepod parasite. Moreover, the effect of infection on immunity was small relative to that of site differences and live coral cover, and similar to the effect of reproductive status. While additional immune data would shed light on the extent of this pattern, ecological factors may play a larger role than immunity in controlling parasite patterns in the wild. Parsing the effects of immunity and ecological factors in octocoral co-infection shows how disease depends on more than one host and one parasite and explores the application of co-infection research to a colonial marine organism.

Project description:Background. Coral reef communities are undergoing marked declines due to a variety of stressors including climate change, eutrophication, sedimentation, and disease. The sea fan coral, Gorgonia ventalina, is a tractable study system to investigate the hypothesis that stressors compromise immunity and lead to onset of disease. Functional studies in Gorgonia ventalina immunity indicate that several key pathways and cellular responses are involved in response to natural microbial invaders, although to date the functional and regulatory pathways remain largely un-neffectors, the primary line of defense in invertebrates. This study used short-read sequencing (Illumina GAIIx) to identify genes involved in the response of G. ventalina to a naturally occurring Aplanochytrium spp. parasite. Results. De novo assembly of the G. ventalina transcriptome yielded 90,230 contigs of which 40, 142 were annotated. RNA-Seq analysis revealed 210 differentially expressed genes in sea fans exposed to the Aplanochytrium parasite. Differentially expressed genes involved in immunity include pattern recognition molecules, anti-microbial peptides, wound repair, and reactive oxygen species. Gene enrichment analysis indicated eight biological processes were enriched representing 36 genes, largely involved with protein translation and energy production. Conclusions. This is the first report using high-throughput sequencing to characterize the host response of a coral to a natural pathogen. Furthermore, we have generated the first transcriptome for a soft coral species. G. ventalina is a non-model species for which few sequences had been previously described, and we were able to annotate a large number of genes and describe their potential roles in immune function. Expression analysis revealed genes important in invertebrate innate immune pathways, as well as those whose role is previously un-described in cnidarians. This resource will be valuable in characterizing G. ventalina immune response to infection and co-infection of pathogens in the context of environmental change. RNA seq experiment using Illumina GAIIx to compare sea fans exposed to an Aplanochytrium species compared to controls

Dataset Information

High ecological resilience of the sea fan Gorgonia ventalina during two severe hurricanes.

Publications

High ecological resilience of the sea fan <i>Gorgonia ventalina</i> during two severe hurricanes.

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