Proteomic profiling of healthy and diseased hybrid soft corals Sinularia maxima × S. polydactyla

Abstract

Emerging diseases of marine invertebrates have been implicated as one of the major causes of the continuing decline in coral reefs worldwide. To date, most of the focus on marine diseases has been aimed at hard (scleractinian) corals, which are the main reef builders worldwide. However, soft (alcyonacean) corals are also essential components of tropical reefs, representing food, habitat and the 'glue' that consolidates reefs, and they are subject to the same stressors as hard corals. Sinularia maxima and S. polydactyla are the dominant soft corals on the shallow reefs of Guam, where they hybridize. In addition to both parent species, the hybrid soft coral population in Guam is particularly affected by Sinularia tissue loss disease. Using label-free shotgun proteomics, we identified differences in protein expression between healthy and diseased colonies of the hybrid S. maxima × S. polydactyla. This study provided qualitative and quantitative data on specific proteins that were differentially expressed under the stress of disease. In particular, metabolic proteins were down-regulated, whereas proteins related to stress and to symbiont photosynthesis were up-regulated in the diseased soft corals. These results indicate that soft corals are responding to pathogenesis at the level of the proteome, and that this label-free approach can be used to identify and quantify protein biomarkers of sub-lethal stress in studies of marine disease.

Advances in coral immunity ‘omics in response to disease outbreaks

“…Examination of differentially abundant proteins revealed a significant increase in fluorescent protein expression in diseased tissue. Fluorescent proteins are known to act as antioxidants, and this finding indicates a stimulated antioxidant immune response of the coral host (Palmer et al, 2009;Gochfeld et al, 2015). Proteins associated with symbiont photosynthesis and stress responses (e.g., heat shock proteins) were also up regulated in diseased tissue.…”

“…The first proteomic study of diseased soft corals examined Sinularia tissue-loss disease (STLD) (Gochfeld et al, 2015). Examination of differentially abundant proteins revealed a significant increase in fluorescent protein expression in diseased tissue.…”

Changes in physiological performance and protein expression in the larvae of the coral Pocillopora damicornis and their symbionts in response to elevated temperature and acidification

“…A few studies have investigated the molecular basis of how coral larvae host-symbiont interactions are affected by elevated temperature and pCO 2 . For example, a possible explanation for the effects of thermal and/or acidification stress on coral larvae was proposed in studies using RNA-seq (Meyer et al, 2011;Polato et al, 2010;Rivest et al, 2018), and proteome analysis was used to study individual responses of coral host and free-living species of Symbiodiniaceae to different environmental stressors (Gochfeld et al, 2015;Pollack et al, 2009). Protein expression changes during symbiosis establishment between the sea anemone Exaiptasia pallida and two symbiont types (Clades C and D) were quantified previously (Sproles et al, 2019); however, to date, very few studies have addressed coral host-symbiont protein expression changes due to climate change, with the exception of one recent study on the coral P. acuta (Mayfield et al, 2018).…”