Browsing by Author "Call, M"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Are mangrove carbon exports old or modern? A multiple radio- and stable isotope analysis
    (University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-09) Maher, DT; Call, M; Santos, IR; Sanders, CJ; Schulz, KG; Jenkinson, A; Jacobsen, GE
    Not provided to ANSTO Library.
  • Thumbnail Image
    Item
    Behaviour of single transmembrane peptides during in meso crystallization from the contrast-matched lipidic cubic phase of monoolein
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) van't Hag, L; de Campo, L; Tran, N; Sokolova, AV; Trenker, R; Call, M; Garvey, CJ; Leung., A; Darwish, TA; Krause-Heuer, AM; Knott, RB; Meikle, T; Gras, S; Drummond, CJ; Mezzenga, R; Conn, C
    In meso membrane protein crystallization within a lipidic mesophase has revolutionized the structural biology of integral membrane proteins (IMPs). High-resolution structures of these proteins are crucial to understanding fundamental cellular processes at a molecular level, and can lead to new and improved treatments for a wide range of diseases via rational drug design. However, overall success rates of the promising in meso crystallization technique remain low because of a fundamental lack of understanding about factors that promote crystal growth. In particular, to date, two decades from invention of the method, the protein-eye-view of the in meso crystallization mechanism had not been solved. We have investigated this for the first time using small-angle neutron scattering (SANS). Contrast-matching between the scattering of the lipid membrane formed by MO and the aqueous solution was used to isolate and track the scattering of single-transmembrane peptides during the growth of protein crystals in meso. No peptide enrichment was observed at the flat points of the diamond cubic QIID phase of MO in contrast to suggestions in several modeling studies. During in meso crystallization of the DAP12 peptide a decrease in form factor and a transient fluid lamellar Lα phase could be observed providing direct evidence for the proposed crystallization mechanism. Synthesis of fully deuterated MO was required for this purpose and scattering of this new material in various solvents and under a range of conditions will be described, specifically regarding the effect of the relative scattering length densities (SLD) of the headgroup, acyl chain and solvent, which can advance the use of neutron scattering with other self-assembly materials. © The Authors.
  • No Thumbnail Available
    Item
    Blue carbon oxidation revealed by radiogenic and stable isotopes in a mangrove system
    (American Geophysical Union, 2017-05-8) Maher, DT; Santos, IR; Schulz, KG; Call, M; Jacobsen, GE; Sanders, CJ
    Mangroves are among the most carbon-rich ecosystems on Earth and can sequester carbon in sediments over long timescales. Here we assess whether century-old buried carbon may be remineralized and exported by measuring Δ14C in the exported dissolved inorganic carbon (DIC) as well as sediment Δ14C profiles in a subtropical mangrove. Pore water exchange released isotopically depleted, old DIC to surface waters. Keeling plots revealed that the source of DIC to surface waters had a δ13C-DIC value of −29.4 ±1.9‰ and Δ14C-DIC value of −73±9‰. The respired and exported carbon comes from an average depth of ~40 cm, equivalent to ~100 years of sediment accumulation. Therefore, century-old sequestered carbon is still susceptible to remineralization and tidal export to the coastal ocean via pore water exchange or submarine groundwater discharge. We suggest that the timescales over which blue carbon burial is assessed should consider carbon losses via pore water exchange. © 2017. American Geophysical Union