Cnidarian Pattern Recognition Receptor Repertoires Reflect Both Phylogeny and Life History Traits

Pattern recognition receptors (PRRs) are evolutionarily ancient and crucial components of innate immunity, recognizing danger-associated molecular patterns (DAMPs) and activating host defenses. Basal non-bilaterian animals such as cnidarians must rely solely on innate immunity to defend themselves from pathogens. By investigating cnidarian PRR repertoires we can gain insight into the evolution of innate immunity in these basal animals. Here we utilize the increasing amount of available genomic resources within Cnidaria to survey the PRR repertoires and downstream immune pathway completeness within 15 cnidarian species spanning two major cnidarian clades, Anthozoa and Medusozoa. Overall, we find that anthozoans possess prototypical PRRs, while medusozoans appear to lack these immune proteins. Additionally, anthozoans consistently had higher numbers of PRRs across all four classes relative to medusozoans, a trend largely driven by expansions in NOD-like receptors and C-type lectins. Symbiotic, sessile, and colonial cnidarians also have expanded PRR repertoires relative to their non-symbiotic, mobile, and solitary counterparts. Interestingly, cnidarians seem to lack key components of mammalian innate immune pathways, though similar to PRR numbers, anthozoans possess more complete immune pathways than medusozoans. Together, our data indicate that anthozoans have greater immune specificity than medusozoans, which we hypothesize to be due to life history traits common within Anthozoa. Overall, this investigation reveals important insights into the evolution of innate immune proteins within these basal animals

Cellular Responses in Sea Fan Corals: Granular Amoebocytes React to Pathogen and Climate Stressors

BACKGROUND: Climate warming is causing environmental change making both marine and terrestrial organisms, and even humans, more susceptible to emerging diseases. Coral reefs are among the most impacted ecosystems by climate stress, and immunity of corals, the most ancient of metazoans, is poorly known. Although coral mortality due to infectious diseases and temperature-related stress is on the rise, the immune effector mechanisms that contribute to the resistance of corals to such events remain elusive. In the Caribbean sea fan corals (Anthozoa, Alcyonacea: Gorgoniidae), the cell-based immune defenses are granular acidophilic amoebocytes, which are known to be involved in wound repair and histocompatibility. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate for the first time in corals that these cells are involved in the organismal response to pathogenic and temperature stress. In sea fans with both naturally occurring infections and experimental inoculations with the fungal pathogen Aspergillus sydowii, an inflammatory response, characterized by a massive increase of amoebocytes, was evident near infections. Melanosomes were detected in amoebocytes adjacent to protective melanin bands in infected sea fans; neither was present in uninfected fans. In naturally infected sea fans a concurrent increase in prophenoloxidase activity was detected in infected tissues with dense amoebocytes. Sea fans sampled in the field during the 2005 Caribbean Bleaching Event (a once-in-hundred-year climate event) responded to heat stress with a systemic increase in amoebocytes and amoebocyte densities were also increased by elevated temperature stress in lab experiments. CONCLUSIONS/SIGNIFICANCE: The observed amoebocyte responses indicate that sea fan corals use cellular defenses to combat fungal infection and temperature stress. The ability to mount an inflammatory response may be a contributing factor that allowed the survival of even infected sea fan corals during a stressful climate event

Experimental transmission of Stony Coral Tissue Loss Disease results in differential microbial responses within coral mucus and tissue

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Huntley, N., Brandt, M., Becker, C., Miller, C., Meiling, S., Correa, A., Holstein, D., Muller, E., Mydlarz, L., Smith, T., & Apprill, A. Experimental transmission of Stony Coral Tissue Loss Disease results in differential microbial responses within coral mucus and tissue. ISME Communications, 2(1), (2022): 46, https://doi.org/10.1038/s43705-022-00126-3.Stony coral tissue loss disease (SCTLD) is a widespread and deadly disease that affects nearly half of Caribbean coral species. To understand the microbial community response to this disease, we performed a disease transmission experiment on US Virgin Island (USVI) corals, exposing six species of coral with varying susceptibility to SCTLD. The microbial community of the surface mucus and tissue layers were examined separately using a small subunit ribosomal RNA gene-based sequencing approach, and data were analyzed to identify microbial community shifts following disease acquisition, potential causative pathogens, as well as compare microbiota composition to field-based corals from the USVI and Florida outbreaks. While all species displayed similar microbiome composition with disease acquisition, microbiome similarity patterns differed by both species and mucus or tissue microhabitat. Further, disease exposed but not lesioned corals harbored a mucus microbial community similar to those showing disease signs, suggesting that mucus may serve as an early warning detection for the onset of SCTLD. Like other SCTLD studies in Florida, Rhodobacteraceae, Arcobacteraceae, Desulfovibrionaceae, Peptostreptococcaceae, Fusibacter, Marinifilaceae, and Vibrionaceae dominated diseased corals. This study demonstrates the differential response of the mucus and tissue microorganisms to SCTLD and suggests that mucus microorganisms may be diagnostic for early disease exposure.This work was funded by an International Coral Reef Society student grant to N.H., National Science Foundation (NSF) VI EPSCoR 0814417 and 1946412 and NSF (Biological Oceanography) award numbers 1928753 to MEB and TBS, 1928609 to AMSC, 1928817 to EMM, 19228771 to LDM, 1927277 to DMH as well as 1928761 and 1938112 to AA, NSF EEID award number 2109622 to MEB, AA, LDM, and AMSC, and a NOAA OAR Cooperative Institutes award to AA (#NA19OAR4320074). Samples were collected under permit #DFW19057U authorized by the Department of Planning and Natural Resources Coastal Zone Management

Alphaflexivirus genomes in stony coral tissue loss disease-affected, disease-exposed, and disease-unexposed coral colonies in the U.S. Virgin Islands

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Veglia, A., Beavers, K., Van Buren, E., Meiling, S., Muller, E., Smith, T., Holstein, D., Apprill, A., Brandt, M., Mydlarz, L., & Correa, A. Alphaflexivirus genomes in stony coral tissue loss disease-affected, disease-exposed, and disease-unexposed coral colonies in the U.S. Virgin Islands. Microbiology Resource Announcements, 11(2), (2022): e01199–e01121, https://doi.org/10.1128/mra.01199-21.Stony coral tissue loss disease (SCTLD) is decimating Caribbean corals. Here, through the metatranscriptomic assembly and annotation of two alphaflexivirus-like strains, we provide genomic evidence of filamentous viruses in SCTLD-affected, -exposed, and -unexposed coral colonies. These data will assist in clarifying the roles of viruses in SCTLD.This work was supported by the National Science Foundation (Biological Oceanography) award numbers 1928753 to M.E.B. and T.B.S., 1928609 to A.M.S.C., 1928817 to E.M.M., 19228771 to L.D.M., 1927277 to D.M.H., and 1928761 to A.A., as well as by VI EPSCoR (NSF numbers 0814417 and 1946412)

Variable species responses to experimental stony coral tissue loss disease (SCTLD) exposure

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Meiling, S. S., Muller, E. M., Lasseigne, D., Rossin, A., Veglia, A. J., MacKnight, N., Dimos, B., Huntley, N., Correa, A. M. S., Smith, T. B., Holstein, D. M., Mydlarz, L. D., Apprill, A., & Brandt, M. E. Variable species responses to experimental stony coral tissue loss disease (SCTLD) exposure. Frontiers in Marine Science, 8, (2021): 670829, https://doi.org/10.3389/fmars.2021.670829.Stony coral tissue loss disease (SCTLD) was initially documented in Florida in 2014 and outbreaks with similar characteristics have since appeared in disparate areas throughout the northern Caribbean, causing significant declines in coral communities. SCTLD is characterized by focal or multifocal lesions of denuded skeleton caused by rapid tissue loss and affects at least 22 reef-building species of Caribbean corals. A tissue-loss disease consistent with the case definition of SCTLD was first observed in the U.S. Virgin Islands (USVI) in January of 2019 off the south shore of St. Thomas at Flat Cay. The objective of the present study was to characterize species susceptibility to the disease present in St. Thomas in a controlled laboratory transmission experiment. Fragments of six species of corals (Colpophyllia natans, Montastraea cavernosa, Orbicella annularis, Porites astreoides, Pseudodiploria strigosa, and Siderastrea siderea) were simultaneously incubated with (but did not physically contact) SCTLD-affected colonies of Diploria labyrinthiformis and monitored for lesion appearance over an 8 day experimental period. Paired fragments from each corresponding coral genotype were equivalently exposed to apparently healthy colonies of D. labyrinthiformis to serve as controls; none of these fragments developed lesions throughout the experiment. When tissue-loss lesions appeared and progressed in a disease treatment, the affected coral fragment, and its corresponding control genet, were removed and preserved for future analysis. Based on measures including disease prevalence and incidence, relative risk of lesion development, and lesion progression rates, O. annularis, C. natans, and S. siderea showed the greatest susceptibility to SCTLD in the USVI. These species exhibited earlier average development of lesions, higher relative risk of lesion development, greater lesion prevalence, and faster lesion progression rates compared with the other species, some of which are considered to be more susceptible based on field observations (e.g., P. strigosa). The average transmission rate in the present study was comparable to tank studies in Florida, even though disease donor species differed. Our findings suggest that the tissue loss disease affecting reefs of the USVI has a similar epizootiology to that observed in other regions, particularly Florida.This work was supported by the National Science Foundation (Biological Oceanography) award number 1928753 to MB and TS, 1928609 to AC, 1928817 to EM, 19228771 to LM, 1927277 to DH, and 1928761 to AA as well as by VI EPSCoR (NSF #0814417 and NSF #1946412)

Deciphering coral disease dynamics: integrating host, microbiome, and the changing environment

Diseases of tropical reef organisms is an intensive area of study, but despite significant advances in methodology and the global knowledge base, identifying the proximate causes of disease outbreaks remains difficult. The dynamics of infectious wildlife diseases are known to be influenced by shifting interactions among the host, pathogen, and other members of the microbiome, and a collective body of work clearly demonstrates that this is also the case for the main foundation species on reefs, corals. Yet, among wildlife, outbreaks of coral diseases stand out as being driven largely by a changing environment. These outbreaks contributed not only to significant losses of coral species but also to whole ecosystem regime shifts. Here we suggest that to better decipher the disease dynamics of corals, we must integrate more holistic and modern paradigms that consider multiple and variable interactions among the three major players in epizootics: the host, its associated microbiome, and the environment. In this perspective, we discuss how expanding the pathogen component of the classic host-pathogen-environment disease triad to incorporate shifts in the microbiome leading to dysbiosis provides a better model for understanding coral disease dynamics. We outline and discuss issues arising when evaluating each component of this trio and make suggestions for bridging gaps between them. We further suggest that to best tackle these challenges, researchers must adjust standard paradigms, like the classic one pathogen-one disease model, that, to date, have been ineffectual at uncovering many of the emergent properties of coral reef disease dynamics. Lastly, we make recommendations for ways forward in the fields of marine disease ecology and the future of coral reef conservation and restoration given these observations

Complementary approaches to diagnosing marine diseases: a union of the modern and the classic

Linking marine epizootics to a specific aetiology is notoriously difficult. Recent diagnostic successes show that marine disease diagnosis requires both modern, cutting-edge technology (e.g. metagenomics, quantitative realtime PCR) and more classic methods (e.g. transect surveys, histopathology and cell culture). Here, we discuss how this combination of traditional and modern approaches is necessary for rapid and accurate identification of marine diseases, and emphasize how sole reliance on any one technology or technique may lead disease investigations astray. We present diagnostic approaches at different scales, from the macro (environment, community, population and organismal scales) to the micro (tissue, organ, cell and genomic scales). We use disease case studies from a broad range of taxa to illustrate diagnostic successes from combining traditional and modern diagnostic methods. Finally, we recognize the need for increased capacity of centralized databases, networks, data repositories and contingency plans for diagnosis and management of marine disease.Keywords: marine epizootics, aetiology, marine disease, diagnosticsKeywords: marine epizootics, aetiology, marine disease, diagnostic

Sex, War, and Disease: The Role of Parasite Infection on Weapon Development and Mating Success in a Horned Beetle (Gnatocerus cornutus)

While parasites and immunity are widely believed to play important roles in the evolution of male ornaments, their potential influence on systems where male weaponry is the object of sexual selection is poorly understood. We experimentally infect larval broad-horned flour beetles with a tapeworm and study the consequent effects on: 1) adult male morphology 2) male-male contests for mating opportunities, and 3) induction of the innate immune system. We find that infection significantly reduces adult male size in ways that are expected to reduce mating opportunities in nature. The sum of our morphological, competition, and immunological data indicate that during a life history stage where no new resources are acquired, males allocate their finite resources in a way that increases future mating potential

NCBI accession numbers for RNAseq data from five coral species experimentally exposed to Stony Coral Tissue Loss Disease (SCTLD) at the University of the Virgin Islands in 2019

Dataset: NCBI accession numbers for RNAseq data from five coral species experimentally exposed to SCTLDRaw RNA sequence data were obtained from a disease transmission experiment carried out at the University of the Virgin Islands in which five reef-building coral species, Colpophyllia natans, Orbicella annularis, Pseudodiploria strigosa, Porites astreoides, and Montastraea cavernosa, were exposed to Stony Coral Tissue Loss Disease (SCTLD) in mesocosms. Sequences were used to compare the differential expression of host and endosymbiont genes between disease states (control, disease-exposed, and disease-infected) and to elucidate a transcriptomic model of the holobiont response to SCTLD. This dataset includes National Center for Biotechnology Information (NCBI) accession numbers and related data for those five coral species examined in the experiment. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/881776NSF Division of Ocean Sciences (NSF OCE) OCE-192877

Physiological Chemistry of Pseudopterosin Biosynthesis in Symbiotic Dinoflagellates from the Soft Coral Pseudopterogorgia elisabethae

The pseudopterosins (Ps) are unique diterpene glycosides with potent anti­ inflammatory properties which were isolated from the gorgonian Pseudopterogorgia elisabethae. The relationship of the anti-inflammatory effects of Ps to their endogenous function in the coral-symbiont association is not known. In this study the biosynthetic origins and the potential endogenous physiological function of the Ps within the coral-symbiont complex are investigated.Significant levels of endogenous Ps A, B, C and D were identified within the dinoflagellate symbiont, Symbiodinium sp, isolated from P. elisabethae. Biosynthetic studies using tritiated geranylgeranyl bisphosphate, yielded radiochemically pure Ps A, 8, C and D and the first committed intermediate, elisabethatriene. The photosynthetic production of organic carbon in Symbiodinium sp. was traced with the aid of radiolabelled 14C02 uptake studies. Results indicated that photosynthate is a significant carbon source for the production of the pseudopterosins and their intermediates. Ps constitute 10-15% of the intracellular lipids of Symbiodinium sp. and are biosynthesized at a low daily rate. This is the first report of Ps biosynthesis occurs within the algal symbiont of P. elisabethae, and thus prompted further study of the physiological implications of this biosynthesis.In comparative physiological studies of Symbiodinium sp. isolated from P. elisabethae and in the free-living dinoflagellate Heterocapsa pygmaea, physical sonic injury induced a significant oxidative burst of highly reactive oxygen species (ROS). Symbiodinium sp. cells from P. elisabethae had an attenuated oxidative burst in response to these injuries when compared to H. pygmaea and other related Symbiodinium species. Exogenously added Ps inhibited ROS release in a dose­ dependant manner in physically stressed cells of H. pygmaea and Symbiodinium sp. isolated from P. americana. The reductions in ROS by Ps were not due to direct anti­-oxidant effect indicating that they may provide a protective role to the cell membrane.In studies with gorgonian corals, hydrogen peroxide was identified as signal molecule in response to physical and heat stress. In these experiments P. elisabethae also exhibited a muted stress response when compared to related gorgonian corals. Overall this study demonstrates that the biosynthetic production of Ps in Symbiodinium sp. cells from P. elisabethae occurs in sufficient quantities to confer beneficial effects to both symbiont and host cells