Grazing-activated chemical defence in a unicellular marine alga

摘要: Marine plankton use a variety of defences against predators, some which affect trophic structure and biogeochemistry1. We have previously shown2 that, during grazing by the protozoan Oxyrrhis marina on alga Emiliania huxleyi, dimethylsulphoniopropionate (DMSP) from prey is converted to dimethyl sulphide (DMS) when lysis ingested cells initiates mixing algal DMSP enzyme lyase. Such mechanism similar macrophyte defence reactions3,4. Here we show that this reaction deters herbivores, presumably through production highly concentrated acrylate, has antimicrobial activity5. Protozoan predators differ in their ability ingest survive with high-activity lyase, but all grazers preferentially select strains low activity offered mixtures. This system involves investment chemical precursor, DMSP, not self-toxic other useful metabolic functions. believe first report grazing-activated unicellular microorganisms.