The chemical armament of reef-building corals: inter- and intra-specific variation and the identification of an unusual actinoporin in Stylophora pistilata

Hanit Ben-Ari,Daniel Sher,Moran Paz

doi:10.1038/s41598-017-18355-1

Hanit Ben-Ari, Daniel Sher + Show 1 more

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https://doi.org/10.1038/s41598-017-18355-1

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Journal: Scientific Reports	Publication Date: Jan 10, 2018
Citations: 28	License type: open-access

Affiliation: University of Haifa

Abstract

Corals, like other cnidarians, are venomous animals that rely on stinging cells (nematocytes) and their toxins to catch prey and defend themselves against predators. However, little is known about the chemical arsenal employed by stony corals, despite their ecological importance. Here, we show large differences in the density of nematocysts and whole-body hemolytic activity between different species of reef-building corals. In the branched coral Stylophora pistillata, the tips of the branches exhibited a greater hemolytic activity than the bases. Hemolytic activity and nematocyst density were significantly lower in Stylophora that were maintained for close to a year in captivity compared to corals collected from the wild. A cysteine-containing actinoporin was identified in Stylophora following partial purification and tandem mass spectrometry. This toxin, named Δ-Pocilopotoxin-Spi1 (Δ-PCTX-Spi1) is the first hemolytic toxin to be partially isolated and characterized in true reef-building corals. Loss of hemolytic activity during chromatography suggests that this actinoporin is only one of potentially several hemolytic molecules. These results suggest that the capacity to employ offensive and defensive chemicals by corals is a dynamic trait within and between coral species, and provide a first step towards identifying the molecular components of the coral chemical armament.

Highlights

Coral reefs are the largest biogenic structures on Earth: they reach sizes of >1000 km, form extreme “hotspots” of biodiversity, and provide numerous ecosystem, community and economic resources
The use of chemical armament is considered critical to the survival of the producing organism. As well as their delivery systems, are often considered to be under strong selective pressure (e.g.39,79,80), and it is reasonable to hypothesize that differences in the potency of the chemical armament may Protein Pool name number m.2523 1 m.1230 1 m.7445 1 m.2226 1 m.12035 1 m.24455 1 m.6423 1 m.2128 1 m.1877 1 m.1271 1 m.20013 1 m.21014 1 m.2523 2 m.2226 2 m.1027 2 m.1230 2 m.6423 2 m.7409 2 m.11815 2 m.2523 3 m.3179 3 m.1594 3 m.11815 3 m.24936 3 m
We provide the first quantitative measurements of two aspects of the chemical armament of reef-building corals, namely the density of the nematocysts and the hemolytic activity of the coral tissue

Summary

Introduction

Coral reefs are the largest biogenic structures on Earth: they reach sizes of >1000 km, form extreme “hotspots” of biodiversity, and provide numerous ecosystem, community and economic resources. As a result of anthropogenic stress and global climate change, hermatypic corals are increasingly facing challenges such as loss of zooxanthellae due to bleaching[1,2], increased microbial loads[3,4,5,6,7,8], competition with macroalgae[9], and the potential for nutrient limitation and loss of exoskeleton due to ocean acidification[10] Under each of these scenarios, reef-building corals may need to rely even more on offensive or defensive chemicals to survive in a changing world[2,11]. Early studies described widespread, albeit highly variable, toxicity in corals[40,41], and these organisms catch prey[2,12,42], defend themselves from predators[43], resist microbial infections[5,6,44] and are involved in fierce chemically-mediated competition for space[20,45,46]

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