Grazing-activated chemical defence in a unicellular marine alga

Abstract

Our data establish a pathway for DMSP biosynthesis in marine algae. This pathway has no steps in common with that in higher plants, which proceeds via SMM and 3-dimethylsulphoniopropionaldehyde 6,7 . DMSP biosynthesis must therefore have evolved independently at least twice. Our results have two other implications. The first stems from the finding that a transaminase reaction stands at the head of the DMSP pathway; this may help explain why nitrogen deficiency enhances DMSP production 12,23,30 . Depletion of cellular amino acids would favour the transamination reaction, thereby promoting DMSP synthesis when nitrogen is limiting. Second, our results suggest that DMSP may not be the only precursor of the DMS produced by living algae: DMSHB is another potential precursor in vivo. In support of this possibility, we have obtained preliminary evidence for extensive catabolism of supplied DMSHB to DMS in Tetraselmis sp. and E. huxleyi.

Annual cycle of dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) related to phytoplankton succession in the Southern North Sea

“…Similarly, the biogenic production of DMSO is specific and generally correlated to DMSP production (Hatton and Wilson, 2007). There are different sources of specific variability in DMSP and DMSO production including growth stage, salinity, temperature, nutrient limitation and light related to several potential physiological functions of these molecules as osmoregulator (Vairavamurthy et al, 1985), cryoprotectant (Kirst et al, 1991), antioxidant (Sunda et al, 2002), methyl donor , grazing deterrent (Wolfe et al, 1997) and overflow mechanism in nitrogen-limiting conditions (Stefels, 2000). DMSP is also a source of carbon (C) and S for heterotrophic organisms (Kiene and Linn, 2000a) and acts as a chemical cue for higher trophic level organisms (Steinke et al, 2002).…”

The hydrography and biology of a bloom of the coccolithophorid Emiliania huxleyi in the northern North Sea

“…Evidence on the possible effects of E. huxleyi blooms on zooplankton populations is not clear. On the one hand Nejstgaard et al (1997) report active feeding and reproduction by zooplankton in mesocosm experiments, whereas Wolfe et al (1997) provide evidence of chemical defence against grazing. The present results are not sufficient to determine whether there was an effect of the bloom on the zooplankton population.…”

Dimethylsulfoniopropionate, superoxide dismutase and glutathione as stress response indicators in three corals under short-term hyposalinity stress

“…However, the underlying physiological function(s) and regulation of DMSP in corals is still unknown [5,6]. In marine algae, DMSP has been proposed to function as an osmolyte [7], a cryoprotectant [8,9], an overflow mechanism for intracellular sulfur [10], a herbivore deterrent [11,12], as well as a chemical attractant, acting as a foraging cue for herbivorous fishes [13], phytoplankton [14], bacteria [15,16] and sea birds [17]. It has also been suggested to form an antiviral defence mechanism [18] and most recently has been shown to act as a trigger for dinoflagellate parasitoid activation [19].…”