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Tracking sulphur in algal cells

3 April 2017

The cells used in the study are from microalgae called Symbiodinium that lives in symbiosis with reef-building corals

The cells used in this study are from microalgae called Symbiodinium that live in symbiosis with reef-building corals

Scientists studying the role of DMSP, an important sulphur compound, in marine microorganisms, have developed a method for visualising this molecule in algal cells that they believe will have far reaching implications beyond the field of environmental microbial ecology.

Sulphur is an essential element for many organisms and environmental processes, especially in our oceans where interactions between microscopic organisms produce large amounts of DMSP that ultimately helps support marine food webs and influences local climatic processes.

Lead author of the study Dr Jean-Baptiste Raina from UTS Climate Change Cluster (C3) said that despite the large scale effects of DMSP, scientists still don’t fully understand the role it plays in the organisms that produce it or how it is transferred to the bacteria that consume it.

Now after 4 years of method development Dr Raina, together with a diverse group of colleagues from seven different Australian universities have refined a method giving the first look at DMSP in algal cells and tracking its journey and fate in recipient bacteria. Using a suite of chemical analysis and cutting edge high-resolution imaging techniques, the study shows that algae store DMSP in the cell compartments that regulate cell pressure and photosynthesis.

“DMSP is highly likely located in the chloroplasts and cytoplasm of the cells and this would confirm the hypothesis that this compound acts as an antioxidant, protecting the cells from a build-up of harmful chemicals,” Dr Raina says.

“Determining DMSP location in the cells is a huge step forward to understanding the role it plays in these organisms.”

This work started while Dr Raina was doing his PhD at James Cook University and the Australian Institute of Marine Science in Townsville.

 “I’ve been working on this molecule for nearly 10 years, and the ability to access high-resolution imaging instruments in Perth and Sydney has been a game changer. The method we used enables the preservation of small water-soluble molecules in samples. It is very exciting because this procedure can be applied to many systems and can be used as a template to identify and localise other elusive molecules, in the biomedical field for example.”

Dr Jean-Baptiste Raina is an ARC DECRA Fellow and a member of UTS C3 Ocean Microbes and Healthy Oceans Research Program

NanoSIMS image of the distribution of sulphur molecules in Symbiodinium cells

NanoSIMS image of the distribution of sulphur molecules in Symbiodinium cells.

Funding:
Australian Research Council (DE160100636), ANNiMS and AMMRF Centre for Microscopy, Characterisation and Analysis (UWA)

Publication details:

Subcellular tracking reveals the location of dimethylsulfoniopropionate in microalgae and visualises its uptake by marine bacteria Jean-Baptiste Raina et al eLIFE;6:e23008. DOI: 10.7554/eLife.23008