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Thanks to all our undergraduate students who helped with the experiments: the BU Marine students for conducting the heat experiment, and our undergraduate students in Tom's lab for NF-κB characterization. Funding: NSF to Sarah and Tom. (16/16)

our work suggests coral immunity underlies C- versus D-hosting phenotypes, revealing a cost paid through host immunity. Hosting thermotolerant algal symbionts comes with costs, particularly when stressors are severe or sustained.(15/16)

We reanalyzed gene expression data from other coral species (Pocillopora grandis, Acropora tenuis). Same story: D-hosting corals showed constitutive immune activation.(14/16)

Maintaining lab colonies of the same species with different algal partners is technically challenging. Our experiment used three coral genotypes (2 D-hosting, 1 C-hosting), so we tested whether baseline transcriptomic differences persist across species. (13/16)

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D-hosting corals experienced greater tissue loss and died, while C-hosting corals survived without significant impact. So the elevated immunity does not confer higher survival.(12/16)

Both algal types exhibited distinct heat stress responses. But would these immune differences hold under a different threat? To test this, we challenged corals with the pathogen Vibrio to determine whether baseline immune status translates to survival. (11/16)

Alternatively, could the phenotypes under stress be driven by microbiome changes or pathogen load in D-hosting corals? We sequenced microbiomes & found no changes under heat. this raises the possibility that tissue loss is driven by the host's own immune response, rather than by its microbes(10/16)

It is fascinating that different types manifested different phenotypes. But why does this happen? Using transcriptomics, we identified distinct inflammatory strategies: D-hosting corals showed sustained, elevated inflammatory signaling, while C-hosting corals showed moderate responses.(9/16)

while C-hosting corals bleached but kept their tissue intact. thanks to our BU Marine Program students for helping with the heat stress experiment.(8/16)

Do these baseline immune differences matter physiologically under heat stress? We conducted a heat-challenge tank experiment on corals hosting different algal types and found that D-hosting corals retained photosynthesis (thermotolerant!) but suffered massive tissue loss,(7/16)

So despite 600 million years of divergence, this immune TF has retained striking functional similarity to its human counterpart. thanks to our undergraduate students in Gilmore's lab, and Dr. Wei Wang for collecting all data in these experiments.(6/16)

Immunostaining further revealed that full-length Pa-NF-κB localizes to the cytoplasm, while a C-terminally truncated form localizes to the nucleus (fascinating!). This mirrors the truncation-dependent activation mechanism that regulates NF-κB family members across animals.(5/16)

our Aiptasia NF-κB antibody cross-reacts with the pocillopora (Pa) homolog, so we characterized Pa-NF-κB's molecular properties. Pa-NF-κB retains conserved DNA-binding activity and is phosphorylated by IKK, the same regulatory mechanism that controls NF-κB activation in humans. (4/16)

First, are there baseline immune differences between C- and D-hosting corals? Using transcriptomics and western blotting of an immune transcription factor (TF) NF-κB, we found that D-hosting corals have elevated expression of immune genes and higher NF-κB protein levels.(3/16)

Building on Tom's previous findings on nfkb and immune suppression in coral-algae symbiosis, we wanted to know if hosting different algal types (Cladocopium/C vs. Durusdinium/D) changes a coral's immune state. (2/16)

We reanalyzed gene expression data from other coral species (Pocillopora grandis, Acropora tenuis). Same story: D-hosting corals showed constitutive immune activation.(14/16)

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D-hosting corals experienced greater tissue loss and died, while C-hosting corals survived without significant impact. So the elevated immunity does not confer higher survival.(12/16)

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while C-hosting corals bleached but kept their tissue intact. thanks to our BU Marine Program students for helping with the heat stress experiment.(8/16)

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