Project Title: The ecophysiology of dimethylsulphoniopropionate (DMSP) in coral reef ecosystems: from cells to the community
Supervisors: Prof Peter Ralph, Dr Katherina Petrou and Jean-Baptiste Raina
PhD conferred: 2017
Email Contact: Peter.Ralph@uts.edu.au
Dimethylsulphoniopropionate (DMSP) represents a major fraction of organic sulphur within marine phytoplankton and is involved in the transfer of sulphur through the marine food web. The importance of DMSP in the biogeochemical cycle is largely attributed to its role as a precursor of volatile dimethylsulphide (DMS) which contributes significantly to the global sulphur cycle. The production of DMSP is mainly restricted to a few classes of marine macro and microalgae and Dinoflagellates are among the biggest producers of DMSP.
In coral reef ecosystems, the presence and functional role(s) of DMSP have only started to be investigated and the underlying physiological function(s) and regulation of DMSP in corals remains undetermined. The exact functions of DMSP and DMS in corals are unknown; however, given their uses in other taxa, these compounds might be involved in stress responses through properties ranging from antibacterial to antioxidant. One proposed physiological function of DMSP is to alleviate cellular oxidative stress. The relatively high concentration of DMSP and DMS in Symbiodinium and other marine algae strongly suggests that these compounds have an antioxidant potential as ROS scavengers. The production and conversion, or ‘turnover’, of DMSP can result in four different antioxidant compounds; dimethylsulphide (DMS), acrylate, dimethylsulphoxide (DMSO) and methanesulphonic acid (MSNA), which together can operate as a highly effective antioxidant system. This project investigates the role of dimethylsulphoniopropionate (DMSP) in coral health and coral reef ecology, specifically; it aims to bring new knowledge of the role of DMSP in coral physiology in response to bleaching.
1. To determine a physiological and biochemical link between DMSP and ROS production in corals under physiological stress
a) Measuring DSMP and ROS regulation in the coral holobiont under osmotic stress
b) Developing and using coral tissue cultures to understand the physiological and biochemical processes at the host-symbiont interface (single-cell)
2. To examine the role of DMSP production in the molecular and physiological response of the coral holobiont to bleaching conditions
a) Examining and evaluating the coral holobiont response to thermal stress
b) Investigating thermal stress responses at the host-symbiont interface (single-cell)
Gardner SG, Nielsen DA, Petrou K, Larkum AWD, Ralph PJ (2014) Characterisation of coral explants: a model organism for cnidarian–dinoflagellate studies. Coral Reefs. DOI 10.1007/s00338-014-1240-4