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Raina JB, Clode PL, Cheong S, Bougoure J, Kilburn MR, Reeder A, Forêt S, Stat M, Beltran V, Thomas-Hall P, Tapiolas D, Motti CM, Gong B, Pernice M, Marjo CE, Seymour JR, Willis BL, Bourne DG. Subcellular tracking reveals the location of dimethylsulfoniopropionate in microalgae and visualises its uptake by marine bacteria. eLife 2017; 6. [PMID: 28371617 PMCID: PMC5380433 DOI: 10.7554/elife.23008] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 03/02/2017] [Indexed: 11/30/2022] Open
Abstract
Phytoplankton-bacteria interactions drive the surface ocean sulfur cycle and local climatic processes through the production and exchange of a key compound: dimethylsulfoniopropionate (DMSP). Despite their large-scale implications, these interactions remain unquantified at the cellular-scale. Here we use secondary-ion mass spectrometry to provide the first visualization of DMSP at sub-cellular levels, tracking the fate of a stable sulfur isotope (34S) from its incorporation by microalgae as inorganic sulfate to its biosynthesis and exudation as DMSP, and finally its uptake and degradation by bacteria. Our results identify for the first time the storage locations of DMSP in microalgae, with high enrichments present in vacuoles, cytoplasm and chloroplasts. In addition, we quantify DMSP incorporation at the single-cell level, with DMSP-degrading bacteria containing seven times more 34S than the control strain. This study provides an unprecedented methodology to label, retain, and image small diffusible molecules, which can be transposable to other symbiotic systems. DOI:http://dx.doi.org/10.7554/eLife.23008.001 Sulfur is an essential element for many organisms and environmental processes. Every year, organisms including microalgae produce more than one billion tons of a sulfur-containing compound called DMSP. Some of this DMSP is released into seawater, where it acts as a key nutrient for microscopic organisms and as a foraging cue to attract fish. DMSP is also the precursor of a gas that helps to form clouds. Despite DMSP’s potential large-scale effects, it is still not clear what role it plays in the organisms that produce it, or how it is transferred from the microalgae that produce it to the bacteria that use it. It is thought that DMSP could potentially protect the cells from sudden changes in the amount of salt in the seawater (salinity) or from other damage, such as oxidative stress – a build-up of harmful chemicals inside cells. In a controlled setting using artificial seawater, Raina et al. used high-resolution imaging and chemical analysis to track the journey of DMSP from microalgae to recipient bacteria. The results show that similar to land plants, algae store DMSP in the compartments that regulate cell pressure and photosynthesis. The presence of DMSP in these locations also supports its proposed role in protecting cells from changes in salinity or oxidative damage. A future step will be to identify the genes involved in producing DMSP in microalgae. This knowledge could be used to create mutants that are either incapable of producing this molecule or that overproduce it. In combination with the high-resolution imaging techniques described here, this will allow researchers to fully understand the role that DMSP plays in these organisms. DOI:http://dx.doi.org/10.7554/eLife.23008.002
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Affiliation(s)
- Jean-Baptiste Raina
- AIMS@JCU, James Cook University, Townsville, Australia.,Australian Institute of Marine Science, Townsville, Australia.,Climate Change Cluster, University of Technology Sydney, Sydney, Australia.,ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia.,College of Science and Engineering, James Cook University, Townsville, Australia
| | - Peta L Clode
- The Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Crawley, Australia.,Oceans Institute, The University of Western Australia, Crawley, Australia
| | - Soshan Cheong
- Mark Wainwright Analytical Centre, University of New South Wales, Kensington, Australia
| | - Jeremy Bougoure
- The Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Crawley, Australia.,School of Earth and Environment, The University of Western Australia, Crawley, Australia
| | - Matt R Kilburn
- The Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Crawley, Australia
| | - Anthony Reeder
- The Centre for Microscopy Characterisation and Analysis, The University of Western Australia, Crawley, Australia
| | - Sylvain Forêt
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia.,Research School of Biology, Australian National University, Canberra, Australia
| | - Michael Stat
- Trace and Environmental DNA Laboratory, Department of Environment and Agriculture, Curtin University, Perth, Australia
| | - Victor Beltran
- Australian Institute of Marine Science, Townsville, Australia
| | | | - Dianne Tapiolas
- Australian Institute of Marine Science, Townsville, Australia
| | - Cherie M Motti
- AIMS@JCU, James Cook University, Townsville, Australia.,Australian Institute of Marine Science, Townsville, Australia
| | - Bill Gong
- Mark Wainwright Analytical Centre, University of New South Wales, Kensington, Australia
| | - Mathieu Pernice
- Climate Change Cluster, University of Technology Sydney, Sydney, Australia
| | - Christopher E Marjo
- Mark Wainwright Analytical Centre, University of New South Wales, Kensington, Australia
| | - Justin R Seymour
- Climate Change Cluster, University of Technology Sydney, Sydney, Australia
| | - Bette L Willis
- AIMS@JCU, James Cook University, Townsville, Australia.,ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia.,College of Science and Engineering, James Cook University, Townsville, Australia
| | - David G Bourne
- Australian Institute of Marine Science, Townsville, Australia.,College of Science and Engineering, James Cook University, Townsville, Australia
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Kotula L, Khan HA, Quealy J, Turner NC, Vadez V, Siddique KHM, Clode PL, Colmer TD. Salt sensitivity in chickpea (Cicer arietinum L.): ions in reproductive tissues and yield components in contrasting genotypes. PLANT, CELL & ENVIRONMENT 2015; 38:1565-77. [PMID: 25615287 DOI: 10.1111/pce.12506] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 01/04/2015] [Indexed: 05/22/2023]
Abstract
The reproductive phase in chickpea (Cicer arietinum L.) is affected by salinity, but little is known about the underlying cause. We investigated whether high concentrations of Na(+) and Cl(-) in the reproductive structures influence reproductive processes. Chickpea genotypes contrasting in tolerance were subjected to 0, 35 or 50 mm NaCl applied to soil in pots. Flower production and abortion, pod number, percentage of empty pods, seed number and size were evaluated. The concentrations of Na(+) , K(+) and Cl(-) were measured in various plant tissues and, using X-ray microanalysis, in specific cells of developing reproductive structures. Genotypic variation in reproductive success measured as seed yield in saline conditions was associated with better maintenance of flower production and higher numbers of filled pods (and thus seed number), whereas seed size decreased in all genotypes. Despite the variation in reproductive success, the accumulation of Na(+) and Cl(-) in the early reproductive tissues of developing pods did not differ between a tolerant (Genesis836) and a sensitive (Rupali) genotype. Similarly, salinity tolerance was not associated with the accumulation of salt ions in leaves at the time of reproduction or in seeds at maturity.
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Affiliation(s)
- Lukasz Kotula
- School of Plant Biology (M084), Faculty of Science, The University of Western Australia, Crawley, Western Australia, 6009, Australia
| | - Hammad A Khan
- School of Plant Biology (M084), Faculty of Science, The University of Western Australia, Crawley, Western Australia, 6009, Australia
- The UWA Institute of Agriculture (M082), The University of Western Australia, Crawley, Western Australia, 6009, Australia
| | - John Quealy
- School of Plant Biology (M084), Faculty of Science, The University of Western Australia, Crawley, Western Australia, 6009, Australia
- Centre for Plant Genetics and Breeding (M080), The University of Western Australia, Crawley, Western Australia, 6009, Australia
| | - Neil C Turner
- The UWA Institute of Agriculture (M082), The University of Western Australia, Crawley, Western Australia, 6009, Australia
- Centre for Plant Genetics and Breeding (M080), The University of Western Australia, Crawley, Western Australia, 6009, Australia
| | - Vincent Vadez
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Greater Hyderabad, Telangana, 502 324, India
| | - Kadambot H M Siddique
- The UWA Institute of Agriculture (M082), The University of Western Australia, Crawley, Western Australia, 6009, Australia
| | - Peta L Clode
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, Western Australia, 6009, Australia
| | - Timothy D Colmer
- School of Plant Biology (M084), Faculty of Science, The University of Western Australia, Crawley, Western Australia, 6009, Australia
- The UWA Institute of Agriculture (M082), The University of Western Australia, Crawley, Western Australia, 6009, Australia
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Häusler S, Weber M, de Beer D, Ionescu D. Spatial distribution of diatom and cyanobacterial mats in the Dead Sea is determined by response to rapid salinity fluctuations. Extremophiles 2014; 18:1085-94. [PMID: 25138278 DOI: 10.1007/s00792-014-0686-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/24/2014] [Indexed: 10/24/2022]
Abstract
Cyanobacteria and diatom mats are ubiquitous in hypersaline environments but have never been observed in the Dead Sea, one of the most hypersaline lakes on Earth. Here we report the discovery of phototrophic microbial mats at underwater freshwater seeps in the Dead Sea. These mats are either dominated by diatoms or unicellular cyanobacteria and are spatially separated. Using in situ and ex situ O2 microsensor measurements we show that these organisms are photosynthetically active in their natural habitat. The diatoms, which are phylogenetically associated to the Navicula genus, grew in culture at salinities up to 40 % Dead Sea water (DSW) (14 % total dissolved salts, TDS). The unicellular cyanobacteria belong to the extremely halotolerant Euhalothece genus and grew at salinities up to 70 % DSW (24.5 % TDS). As suggested by a variable O2 penetration depth measured in situ, the organisms are exposed to drastic salinity fluctuations ranging from brackish to DSW salinity within minutes to hours. We could demonstrate that both phototrophs are able to withstand such extreme short-term fluctuations. Nevertheless, while the diatoms recover better from rapid fluctuations, the cyanobacteria cope better with long-term exposure to DSW. We conclude that the main reason for the development of these microbial mats is a local dilution of the hypersaline Dead Sea to levels allowing growth. Their spatial distribution in the seeping areas is a result of different recovery rates from short or long-term fluctuation in salinity.
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Affiliation(s)
- Stefan Häusler
- Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28211, Bremen, Germany
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Lyon BR, Lee PA, Bennett JM, DiTullio GR, Janech MG. Proteomic analysis of a sea-ice diatom: salinity acclimation provides new insight into the dimethylsulfoniopropionate production pathway. PLANT PHYSIOLOGY 2011; 157:1926-41. [PMID: 22034629 PMCID: PMC3327215 DOI: 10.1104/pp.111.185025] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Dimethylsulfoniopropionate (DMSP) plays important roles in oceanic carbon and sulfur cycling and may significantly impact climate. It is a biomolecule synthesized from the methionine (Met) pathway and proposed to serve various physiological functions to aid in environmental stress adaptation through its compatible solute, cryoprotectant, and antioxidant properties. Yet, the enzymes and mechanisms regulating DMSP production are poorly understood. This study utilized a proteomics approach to investigate protein changes associated with salinity-induced DMSP increases in the model sea-ice diatom Fragilariopsis cylindrus (CCMP 1102). We hypothesized proteins associated with the Met-DMSP biosynthesis pathway would increase in relative abundance when challenged with elevated salinity. To test this hypothesis axenic log-phase cultures initially grown at a salinity of 35 were gradually shifted to a final salinity of 70 over a 24-h period. Intracellular DMSP was measured and two-dimensional gel electrophoresis was used to identify protein changes at 48 h after the shift. Intracellular DMSP increased by approximately 85% in the hypersaline cultures. One-third of the proteins increased under high salinity were associated with amino acid pathways. Three protein isoforms of S-adenosylhomo-cysteine hydrolase, which synthesizes a Met precursor, increased 1.8- to 2.1-fold, two isoforms of S-adenosyl Met synthetase increased 1.9- to 2.5-fold, and S-adenosyl Met methyltransferase increased by 2.8-fold, suggesting active methyl cycle proteins are recruited in the synthesis of DMSP. Proteins from the four enzyme classes of the proposed algal Met transaminase DMSP pathway were among the elevated proteins, supporting our hypothesis and providing candidate genes for future characterization studies.
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