ORCID Profile
0000-0002-5140-457X
Current Organisation
University of Western Australia
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Animal Physiology - Biophysics | Zoology | Animal Neurobiology | Animal Structure and Function
Horticultural Crops not elsewhere classified | Honey | Expanding Knowledge in the Biological Sciences |
Publisher: Springer Science and Business Media LLC
Date: 09-2020
Publisher: Elsevier BV
Date: 03-2019
Publisher: The Royal Society
Date: 09-2018
DOI: 10.1098/RSOS.181163
Abstract: The honeybee Apis mellifera is one of many animal species for which empirical evidence of a magnetic sense has been provided. The underlying mechanisms postulated for magnetoreception in bees are varied, but most point towards the abdomen as the most likely anatomical region for its location, partly owing to the large accumulation of iron in trophocyte cells that comprise the honeybee fat body. Using a multi-modal imaging and analysis approach, we have investigated iron in the honeybee, with a particular focus on the abdomen and the utility of such techniques as applied to magnetoreception. Abdominal iron is shown to accumulate rapidly, reaching near maximum levels only 5 days after emerging from the comb and is associated with the accumulation of iron within the fat body. While fat body iron could be visualized, no regions of interest, other than perhaps the fat body itself, were identified as potential sites for magnetoreceptive cells. If an iron-based magnetoreceptor exists within the honeybee abdomen the large accumulation of iron in the fat body is likely to impede its discovery.
Publisher: American Chemical Society (ACS)
Date: 27-10-2011
DOI: 10.1021/NN2022149
Abstract: Polymer nanoparticles are widely used as a highly generalizable tool to entrap a range of different drugs for controlled or site-specific release. However, despite numerous studies examining the kinetics of controlled release, the biological behavior of such nanoparticles remains poorly understood, particularly with respect to endocytosis and intracellular trafficking. We synthesized polyethylenimine-decorated polymer nanospheres (ca. 100-250 nm) of the type commonly used for drug release and used correlated electron microscopy, fluorescence spectroscopy and microscopy, and relaxometry to track endocytosis in neural cells. These capabilities provide insight into how polyethylenimine mediates the entry of nanoparticles into neural cells and show that polymer nanosphere uptake involves three distinct steps, namely, plasma membrane attachment, fluid-phase as well as clathrin- and caveolin-independent endocytosis, and progressive accumulation in membrane-bound intracellular vesicles. These findings provide detailed insight into how the intracellular delivery of nanoparticles is mediated by polyethylenimine, which is presently the most commonly used nonviral gene transfer agent. This fundamental knowledge may also assist in the preparation of next-generation nonviral vectors.
Publisher: Springer Science and Business Media LLC
Date: 23-12-2019
DOI: 10.1038/S41598-019-56202-7
Abstract: Seeds of Australian species of the seagrass genus Posidonia are covered by a membranous wing that we hypothesize plays a fundamental role in seed establishment in sandy, wave swept marine environments. Dimensions of the seed and membrane were quantified under electron microscopy and micro-CT scans, and used to model rotational, drag and lift forces. Seeds maintain contact with the seabed in the presence of strong turbulence: the larger the wing, the more stable the seed. Wing surface area increases from P. sinuosa P. australis P.coriacea correlating with their ability to establish in increasingly energetic environments. This unique seed trait in a marine angiosperm corresponds to adaptive pressures imposed on seagrass species along 7,500 km of Australia’s coastline, from open, high energy coasts to calmer environments in bays and estuaries.
Publisher: Frontiers Media SA
Date: 26-11-2020
DOI: 10.3389/FNANA.2020.560534
Abstract: There is currently a limited understanding of the morphological and functional organization of the olfactory system in cartilaginous fishes, particularly when compared to bony fishes and terrestrial vertebrates. In this fish group, there is a clear paucity of information on the characterization, density, and distribution of olfactory receptor neurons (ORNs) within the sensory olfactory epithelium lining the paired olfactory rosettes, and their functional implications with respect to the hydrodynamics of incurrent water flow into the nares. This imaging study examines the brownbanded bamboo shark Chiloscyllium punctatum (Elasmobranchii) and combines immunohistochemical labeling using antisera raised against five G-protein α-subunits (Gα s/olf , Gα q/ 11 / 14 , Gα i– 1 / 2 / 3 , Gα i– 3 , Gα o ) with light and electron microscopy, to characterize the morphological ORN types present. Three main ORNs (“long”, “microvillous” and “crypt-like”) are confirmed and up to three additional microvilli-bearing types are also described “Kappe-like” (potential or homologous “Kappe” as in teleosts), “pear-shaped” and “teardrop-shaped” cells. These morphotypes will need to be confirmed molecularly in the future. Using X-ray diffusible iodine-based contrast-enhanced computed tomography (diceCT), high-resolution scans of the olfactory rosettes, olfactory bulbs (OBs), peduncles, and telencephalon reveal a lateral segregation of primary olfactory inputs within the OBs, with distinct medial and lateral clusters of glomeruli, suggesting a potential somatotopic organization. However, most ORN morphotypes are found to be ubiquitously distributed within the medial and lateral regions of the olfactory rosette, with at least three microvilli-bearing ORNs labeled with anti-Gα o found in significantly higher densities in lateral lamellae [in lateral lamellae] and on the anterior portion of lamellae (facing the olfactory cavity). These microvilli-bearing ORN morphotypes (microvillous, “Kappe-like,” “pear-shaped,” and “teardrop-shaped”) are the most abundant across the olfactory rosette of this species, while ciliated ORNs are less common and crypt cells are rare. Spatial simulations of the fluid dynamics of the incurrent water flow into the nares and within the olfactory cavities indicate that the high densities of microvilli-bearing ORNs located within the lateral region of the rosette are important for s ling incoming odorants during swimming and may determine subsequent tracking behavior.
Publisher: American Geophysical Union (AGU)
Date: 2018
DOI: 10.1002/2017GC007287
Publisher: The Royal Society
Date: 07-07-2021
Abstract: Sexually antagonistic coevolution can drive the evolution of male traits that harm females, and female resistance to those traits. While males have been found to vary their harmfulness to females in response to social cues, plasticity in female resistance traits remains to be examined. Here, we ask whether female seed beetles Callosobruchus maculatus are capable of adjusting their resistance to male harm in response to the social environment. Among seed beetles, male genital spines harm females during copulation and females might resist male harm via thickening of the reproductive tract walls. We develop a novel micro computed tomography imaging technique to quantify female reproductive tract thickness in three-dimensional space, and compared the reproductive tracts of females from populations that had evolved under high and low levels of sexual conflict, and for females reared under a social environment that predicted either high or low levels of sexual conflict. We find little evidence to suggest that females can adjust the thickness of their reproductive tracts in response to the social environment. Neither did evolutionary history affect reproductive tract thickness. Nevertheless, our novel methodology was capable of quantifying fine-scale differences in the internal reproductive tracts of in idual females, and will allow future investigations into the internal organs of insects and other animals.
Publisher: Trans Tech Publications, Ltd.
Date: 05-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.71-73.235
Abstract: The composition and distribution of elements within cells of two species of Fe and S oxidising microbes utilising S, Fe2+ or chalcopyrite (CuFeS2) as an energy source were compared to determine possible sites of oxidation and function of intracellular granules. The bacterium Acidithiobacillus ferrooxidans and the archaeon Metallosphaera hakonensis were examined using energy filtered transmission electron microscopy (EFTEM), TEM energy dispersive X-ray spectroscopy (EDS), Scanning TEM (STEM) and electron energy-loss spectroscopy (EELS). Both species have intracellular granules and we show that these store Fe, S and P. The microbes slowly lost Fe from granules when switched to an Fe-free medium. EELS showed that the Fe in the granules of both species was consistent with Fe3+. Both microbes sometimes contain Cu and Si on their walls and intracellularly. Si concentrations have been shown to affect bioleach performance, so element deposition on the microbial catalyst may be a reason for this. Bands of Fe and S were present close to, or in, the cell membrane of M. hakonensis, as might be expected for the site of oxidation, and S also occurred throughout the cytoplasm. These are the first element maps of M. hakonensis, and these early results demonstrate that advanced characterisation and microanalysis techniques can provide insights into microbial processes involved in bioleaching.
Publisher: Mineralogical Society of America
Date: 02-2019
DOI: 10.2138/AM-2019-6733
Publisher: Public Library of Science (PLoS)
Date: 16-05-2013
Publisher: Wiley
Date: 2009
DOI: 10.1002/SCA.20141
Abstract: Chitons are marine molluscs that mineralize their teeth by the process of matrix-mediated biomineralization. The teeth develop in a continuous manner forming hard minerals, including magnetite, making analysis of the matrix within these mineralized regions difficult. This article describes the use of charge contrast imaging techniques, rarely applied to biological s les, to simultaneously image the organic and mineral phases within the teeth of these animals. Resulting evidence demonstrates the power of this technique in delivering architectural information concerning both the matrix and mineral phases, without the need for removal of the hard mineralized material.
Publisher: Public Library of Science (PLoS)
Date: 27-11-2013
Publisher: Oxford University Press (OUP)
Date: 30-04-2019
DOI: 10.1093/JXB/ERZ200
Abstract: Molecular modelling, histochemistry, and micro-computed tomography reveal that the apoplastic pore size is dynamically regulated during bud burst in grapevine, and associated with oxygenation of the meristematic core.
Publisher: Elsevier BV
Date: 06-2016
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CH12161
Abstract: Activators regenerated by electron-transfer atom-transfer radical polymerization, catalyzed by tris(2-pyridylmethyl)amine/CuBr2 and Na{Cu(Gly3)}, was used to synthesize poly(2-hydroxyethyl methacrylate) sponges from 80 : 20 H2O/2-hydroxyethyl methacrylate mixtures. Polymerization-induced phase separations resulted in sponges having morphologies based on agglomerated polymer droplets. During the synthesis of poly(2-hydroxyethyl methacrylate) sponges, first-order kinetics were observed up to a maximum of ~50 % conversion regardless of the catalyst used. The morphologies of the sponges were dependent on the rate of polymerization, slower polymerization rates resulting in polymers with larger morphological features (pores and polymer droplets).
Publisher: MDPI AG
Date: 14-03-2022
Abstract: This article compares measurements of particle shape parameters from three-dimensional (3D) X-ray micro-computed tomography (μCT) and two-dimensional (2D) dynamic image analysis (DIA) from the optical microscopy of a coastal bioclastic calcareous sand from Western Australia. This biogenic sand from a high energy environment consists largely of the shells and tests of marine organisms and their clasts. A significant difference was observed between the two imaging techniques for measurements of aspect ratio, convexity, and sphericity. Measured values of aspect ratio, sphericity, and convexity are larger in 2D than in 3D. Correlation analysis indicates that sphericity is correlated with convexity in both 2D and 3D. These results are attributed to inherent limitations of DIA when applied to platy sand grains and to the shape being, in part, dependent on the biology of the grain rather than a purely random clastic process, like typical siliceous sands. The statistical data has also been fitted to Johnson Bounded Distribution for the ease of future use. Overall, this research demonstrates the need for high-quality 3D microscopy when conducting a micromechanical analysis of biogenic calcareous sands.
Publisher: Springer International Publishing
Date: 2015
Publisher: Frontiers Media SA
Date: 03-12-2014
Publisher: Environmental Health Perspectives
Date: 06-2015
DOI: 10.1289/EHP.1409149
Publisher: The Company of Biologists
Date: 2020
DOI: 10.1242/JEB.210195
Abstract: Visual systems play a vital role in guiding the behaviour of animals. Understanding the visual information animals are able to acquire is therefore key to understanding their visually-mediated decision making. Compound eyes, the dominant eye type in arthropods, are inherently low-resolution structures. Their ability to resolve spatial detail depends on s ling resolution (interommatidial angle) and the quality of ommatidial optics. Current techniques for estimating interommatidial angles are difficult, and generally require in vivo measurements. Here, we present a new method for estimating interommatidial angles based on the detailed analysis of 3D Micro-CT images of fixed s les. Using custom-made MATLAB software we determine the optical axes of in idual ommatidia and project these axes into the three-dimensional space around the animal. The combined viewing directions of all ommatidia, estimated from geometrical optics, allow us to estimate interommatidial angles and map the animal's s ling resolution across its entire visual field. The resulting topographic representations of visual acuity match very closely the previously published data obtained from both fiddler and grapsid crabs. However, the new method provides additional detail that was not previously detectable and reveals that fiddler crabs, rather than having a single horizontal visual streak as is common in flat world inhabitants, likely have two parallel streaks located just above and below the visual horizon. A key advantage of our approach is that it can be used on appropriately preserved specimens allowing the technique to be applied to animals such as deep-sea crustaceans that are inaccessible or unsuitable for in vivo approaches.
Publisher: American Geophysical Union (AGU)
Date: 12-2017
DOI: 10.1002/2017GC007278
Publisher: Wiley
Date: 05-2009
DOI: 10.1002/JMOR.10705
Abstract: A detailed investigation of the stylus canal situated within the iron mineralized major lateral teeth of the chiton Acanthopleura hirtosa was undertaken in conjunction with a row-by-row examination of cusp mineralization. The canal is shown to contain columnar epithelial tissue similar to that surrounding the mineralized cusps, including the presence of iron rich particles characteristic of the iron storage protein ferritin. Within the tooth core, a previously undescribed internal pathway or plume is evident above the stylus canal, between the junction zone and mineralizing posterior face of the cusp. Plume formation coincides with the appearance of iron in the superior epithelium and the onset of mineralization at tooth row 13. The plume persists during the delivery of phosphorous and calcium into the tooth core, and is the final region of the cusp to become mineralized. The presence of the stylus canal was confirmed in a further 18 chiton species, revealing that the canal is common to polyplacophoran molluscs. These new data strongly support the growing body of evidence highlighting the importance of the junction zone for tooth mineralization in chiton teeth, and indicate that the chemical and structural environment within the tooth cusp is under far greater biological control than previously considered.
Publisher: Frontiers Media SA
Date: 31-05-2021
DOI: 10.3389/FSURG.2021.662530
Abstract: Background: The etiology of Meniere's disease (MD) and endolymphatic hydrops believed to underlie its symptoms remain unknown. One reason may be the exceptional complexity of the human inner ear, its vulnerability, and surrounding hard bone. The vestibular organ contains an endolymphatic duct system (EDS) bridging the different fluid reservoirs. It may be essential for monitoring hydraulic equilibrium, and a dysregulation may result in distension of the fluid spaces or endolymphatic hydrops. Material and Methods: We studied the EDS using high-resolution synchrotron phase contrast non-invasive imaging (SR-PCI), and micro-computed tomography (micro-CT). Ten fresh human temporal bones underwent SR-PCI. One bone underwent micro-CT after fixation and staining with Lugol's iodine solution (I 2 KI) to increase tissue resolution. Data were processed using volume-rendering software to create 3D reconstructions allowing orthogonal sectioning, cropping, and tissue segmentation. Results: Combined imaging techniques with segmentation and tissue modeling demonstrated the 3D anatomy of the human saccule, utricle, endolymphatic duct, and sac together with connecting pathways. The utricular duct (UD) and utriculo-endolymphatic valve (UEV or Bast's valve) were demonstrated three-dimensionally for the first time. The reunion duct was displayed with micro-CT. It may serve as a safety valve to maintain cochlear endolymph homeostasis under certain conditions. Discussion: The thin reunion duct seems to play a minor role in the exchange of endolymph between the cochlea and vestibule under normal conditions. The saccule wall appears highly flexible, which may explain occult hydrops occasionally preceding symptoms in MD on magnetic resonance imaging (MRI). The design of the UEV and connecting ducts suggests that there is a reciprocal exchange of fluid among the utricle, semicircular canals, and the EDS. Based on the anatomic framework and previous experimental data, we speculate that precipitous vestibular symptoms in MD arise from a sudden increase in endolymph pressure caused by an uncontrolled endolymphatic sac secretion. A rapid rise in UD pressure, mediated along the fairly wide UEV, may underlie the acute vertigo attack, refuting the rupture/K + -intoxication theory.
Publisher: The Royal Society
Date: 09-2015
Abstract: Behavioural studies underpin the weight of experimental evidence for the existence of a magnetic sense in animals. In contrast, studies aimed at understanding the mechanistic basis of magnetoreception by determining the anatomical location, structure and function of sensory cells have been inconclusive. In this review, studies attempting to demonstrate the existence of a magnetoreceptor based on the principles of the magnetite hypothesis are examined. Specific attention is given to the range of techniques, and main animal model systems that have been used in the search for magnetite particulates. Anatomical location/cell rarity and composition are identified as two key obstacles that must be addressed in order to make progress in locating and characterizing a magnetite-based magnetoreceptor cell. Avenues for further study are suggested, including the need for novel experimental, correlative, multimodal and multidisciplinary approaches. The aim of this review is to inspire new efforts towards understanding the cellular basis of magnetoreception in animals, which will in turn inform a new era of behavioural research based on first principles.
Publisher: Royal Society of Chemistry (RSC)
Date: 15-01-2013
DOI: 10.1039/C3NR32979H
Abstract: It has been recently reported that for some suspensions of magnetic nanoparticles the transverse proton relaxation rate, R(2), is dependent on the time that the s le is exposed to an applied magnetic field. This time dependence has been linked to the formation of linear aggregates or chains in an applied magnetic field via numerical modeling. It is widely known that chain formation occurs in more concentrated ferrofluids systems and that this has an affect on the ferrofluid properties. In this work we examine the relationships between colloidal stability, the formation of these linear structures, and changes observed in the proton transverse relaxation rate of aqueous suspensions of magnetic particles. A series of iron oxide nanoparticles with varying stabilizing ligand brush lengths were synthesized. These systems were characterized with dynamic light scattering, transmission electron microscopy, dark-field optical microscopy, and proton transverse relaxation rate measurements. The dark field optical microscopy and R(2) measurements were made in similar magnetic fields over the same time scale so as to correlate the reduction of the transverse relaxivity with the formation of linear aggregates. Our results indicate that varying the ligand length has a direct effect on the colloidal arrangement of the system in a magnetic field, producing differences in the rate and size of chain formation, and hence systematic changes in transverse relaxation rates over time. With increasing ligand brush length, attractive inter-particle interactions are reduced, which results in slower aggregate formation and shorter linear aggregate length. These results have implications for the stabilization, characterization and potentially the toxicity of magnetic nanoparticle systems used in biomedical applications.
Publisher: American Society of Civil Engineers
Date: 21-03-2019
Publisher: ASTM International
Date: 08-04-2019
DOI: 10.1520/GTJ20180286
Publisher: Oxford University Press (OUP)
Date: 07-2009
DOI: 10.1017/S1431927609093672
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.BIOMATERIALS.2015.10.001
Abstract: Following neurotrauma, oxidative stress is spread via the astrocytic syncytium and is associated with increased aquaporin 4 (AQP4), inflammatory cell infiltration, loss of neurons and glia and functional deficits. Herein we evaluate multimodal polymeric nanoparticles functionalized with an antibody to an extracellular epitope of AQP4, for targeted delivery of an anti-oxidant as a therapeutic strategy following partial optic nerve transection. Using fluorescence microscopy, spectrophotometry, correlative nanoscale secondary ion mass spectrometry (NanoSIMS) and transmission electron microscopy, in vitro and in vivo, we demonstrate that functionalized nanoparticles are coated with serum proteins such as albumin and enter both macrophages and astrocytes when administered to the site of a partial optic nerve transection in rat. Antibody functionalized nanoparticles synthesized to deliver the antioxidant resveratrol are effective in reducing oxidative damage to DNA, AQP4 immunoreactivity and preserving visual function. Non-functionalized nanoparticles evade macrophages more effectively and are found more diffusely, including in astrocytes, however they do not preserve the optic nerve from oxidative damage or functional loss following injury. Our study highlights the need to comprehensively investigate nanoparticle location, interactions and effects, both in vitro and in vivo, in order to fully understand functional outcomes.
Publisher: Springer Science and Business Media LLC
Date: 04-2012
DOI: 10.1038/NATURE11046
Abstract: Understanding the molecular and cellular mechanisms that mediate magnetosensation in vertebrates is a formidable scientific problem. One hypothesis is that magnetic information is transduced into neuronal impulses by using a magnetite-based magnetoreceptor. Previous studies claim to have identified a magnetic sense system in the pigeon, common to avian species, which consists of magnetite-containing trigeminal afferents located at six specific loci in the rostral subepidermis of the beak. These studies have been widely accepted in the field and heavily relied upon by both behavioural biologists and physicists. Here we show that clusters of iron-rich cells in the rostro-medial upper beak of the pigeon Columbia livia are macrophages, not magnetosensitive neurons. Our systematic characterization of the pigeon upper beak identified iron-rich cells in the stratum laxum of the subepidermis, the basal region of the respiratory epithelium and the apex of feather follicles. Using a three-dimensional blueprint of the pigeon beak created by magnetic resonance imaging and computed tomography, we mapped the location of iron-rich cells, revealing unexpected variation in their distribution and number--an observation that is inconsistent with a role in magnetic sensation. Ultrastructure analysis of these cells, which are not unique to the beak, showed that their subcellular architecture includes ferritin-like granules, siderosomes, haemosiderin and filopodia, characteristics of iron-rich macrophages. Our conclusion that these cells are macrophages and not magnetosensitive neurons is supported by immunohistological studies showing co-localization with the antigen-presenting molecule major histocompatibility complex class II. Our work necessitates a renewed search for the true magnetite-dependent magnetoreceptor in birds.
Publisher: Public Library of Science (PLoS)
Date: 18-06-2014
Publisher: Wiley
Date: 31-05-2013
DOI: 10.1002/APP.38034
Publisher: Elsevier BV
Date: 09-2009
Publisher: Elsevier BV
Date: 04-2020
Publisher: American Society for Microbiology
Date: 15-06-2010
DOI: 10.1128/AEM.03085-09
Abstract: One of soil microbiology's most intriguing puzzles is how so many different bacterial species can coexist in small volumes of soil when competition theory predicts that less competitive species should decline and eventually disappear. We provide evidence supporting the theory that low pore connectivity caused by low water potential (and therefore low water content) increases the ersity of a complex bacterial community in soil. We altered the pore connectivity of a soil by decreasing water potential and increasing the content of silt- and clay-sized particles. Two textures were created, without altering the chemical properties or mineral composition of the soil, by adding silt- and clay-sized particles of quartz to a quartz-based sandy soil at rates of 0% (sand) or 10% (silt+clay). Both textures were incubated at several water potentials, and the effect on the active bacterial communities was measured using terminal restriction fragment length polymorphism (TRFLP) of bacterial 16S rRNA. Bacterial richness and ersity increased as water potential decreased and soil became drier ( P 0.012), but they were not affected by texture ( P 0.553). Bacterial ersity increased at water potentials of ≤2.5 kPa in sand and ≤4.0 kPa in silt+clay, equivalent to ≤56% water-filled pore space (WFPS) in both textures. The bacterial community structure in soil was affected by both water potential and texture ( P 0.001) and was correlated with WFPS (sum of squared correlations [δ 2 ] = 0.88, P 0.001). These findings suggest that low pore connectivity is commonly experienced by soil bacteria under field conditions and that the theory of pore connectivity may provide a fundamental principle to explain the high ersity of bacteria in soil.
Publisher: Springer Science and Business Media LLC
Date: 28-01-2021
DOI: 10.1038/S41598-020-79739-4
Abstract: Aggregates of corundum crystals with skeletal to hopper morphology occur in pyroclastic rocks erupted from Cretaceous basaltic volcanoes on Mt Carmel, N. Israel. The rapid growth of the crystals trapped volumes of the parental Al 2 O 3 -supersaturated melt phenocrysts of tistarite (Ti 2 O 3 ) in the trapped melts indicate crystallization at oxygen fugacities 6–7 log units below the Iron-Wüstite buffer ( f O 2 = ΔIW − 6 to − 7), induced by fluxes of mantle-derived CH 4 -H 2 fluids. Cathodoluminescence images reveal growth zoning within the in idual crystals of the aggregates, related to the substitution of Ti 3+ in the corundum structure. Ti contents are 0.3 wt% initially, then increase first linearly, then exponentially, toward adjacent melt pockets to reach values 2 wt%. Numerical modelling indicates that the first skeletal crystals grew in an open system, from a moving magma. The subsequent linear increase in Ti reflects growth in a partially closed system, with decreasing porosity the exponential increase in Ti close to melt pockets reflects closed-system growth, leading to dramatic increases in incompatible-element concentrations in the residual melts. We suggest that the corundum aggregates grew in melt/fluid conduits diffusion modelling implies timescales of days to years before crystallization was terminated by explosive eruption. These processes probably operate in explosive volcanic systems in several tectonic settings.
Publisher: American Malacological Society
Date: 07-2008
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.JBIOMECH.2013.12.030
Abstract: Human tooth enamel exhibits a unique microstructure able to sustain repeated mechanical loading during dental function. Although notable advances have been made towards understanding the mechanical characteristics of enamel, challenges remain in the testing and interpretation of its mechanical properties. For ex le, enamel was often tested under dry conditions, significantly different from its native environment. In addition, constant load, rather than indentation depth, has been used when mapping the mechanical properties of enamel. In this work, tooth specimens are prepared under hydrated conditions and their stiffnesses are measured by depth control across the thickness of enamel. Crystal arrangement is postulated, among other factors, to be responsible for the size dependent indentation modulus of enamel. Supported by a simple structure model, effective crystal orientation angle is calculated and found to facilitate shear sliding in enamel under mechanical contact. In doing so, the stress build-up is eased and structural integrity is maintained.
Publisher: Copernicus GmbH
Date: 31-03-2017
Abstract: Abstract. The shells of two marine bivalve species (Fulvia tenuicostata and Soletellina biradiata) endemic to south Western Australia have been characterised using a combined crystallographic, spectroscopic and geochemical approach. Both species have been described previously as purely aragonitic however, this study identified the presence of three phases, namely aragonite, calcite and Mg-calcite, using XRD analysis. Data obtained via confocal Raman spectroscopy, electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) show correlations between Mg ∕ S and Mg ∕ P in F. tenuicostata and between Sr ∕ S and S ∕ Ba in S. biradiata. The composition of the organic macromolecules that constitute the shell organic matrix (i.e. the soluble phosphorus-dominated and/or insoluble sulfur-dominated fraction) influences the incorporation of Mg, Sr and Ba into the crystal lattice. Ionic substitution, particularly Ca2+ by Mg2+ in calcite in F. tenuicostata, appears to have been promoted by the combination of both S- and P-dominated organic macromolecules. The elemental composition of these two marine bivalve shells is species specific and influenced by many factors, such as crystallographic structure, organic macromolecule composition and environmental setting. In order to reliably use bivalve shells as proxies for paleoenvironmental reconstructions, both the organic and inorganic crystalline material need to be characterised to account for all influencing factors and accurately describe the vital effect.
Publisher: Wiley
Date: 19-01-2020
Publisher: American Society of Mechanical Engineers
Date: 17-06-2018
Abstract: Calcareous sediments are prominent throughout the low-latitudinal offshore environment and have been known to be problematic for offshore foundation systems. These fascinating soils consist largely of the skeletal remains of single-celled marine organisms (plankton and zooplankton) and can be as geologically complex as their onshore siliceous counter parts. To enable an adequate understanding of their characteristics, in particular, their intra-granular micro-structure, it is important that geotechnical engineers do not forget about the multifaceted biological origins of these calcareous sediments and the different geological processes that created them. In this paper, the 3D models of soils grains generated from micro-computed tomography scans, scanning electeron microscope images, and optical microscope images of two calcareous sediments from two different depositional environments are presented and their geotechnical implications discussed. One is a coastal bioclastic sediment from Perth, Western Australia that is geologically similar to carbonate sediments typically used in micro-mechanics and particle crushing studies in the literature. The other is a hemipelagic sediment from a region of the North West Shelf of Australia that has historically been geotechnically problematic for engineers. The results show there is a marked difference between coastal bioclastic and hemipelagic sediments in terms of geological context and the associated particle micro-structures. This brings into question whether a coastal bioclastic calcareous sediment is a good micro-mechanical substitute for a hemipelagic one.
Publisher: Elsevier BV
Date: 10-2010
Publisher: Cambridge University Press (CUP)
Date: 05-2008
DOI: 10.1017/S0025315408000842
Abstract: Eight species of polydorid polychaetes were found to inhabit mollusc shells from south-western Australian waters. Numerous in iduals of Polydora uncinata were extracted for the first time from the shells of both land-based cultured abalone Haliotis laevigata and H. roei , as well as from natural subtidal H. roei and Chlamys australis . Shells of the oyster Saccostrea commercialis cultured in sea-based systems were infested by Boccardia knoxi which was first recorded in these waters. Polydora aura, Dipolydora giardi, D. armata, D. aciculata and Boccardia proboscidea were common among shells of various natural intertidal and subtidal molluscs. A small number of P. haswelli were extracted from their self-excavated burrows in shells of cultured oysters. Boccardia knoxi and D. aciculata were redescribed based on the newly collected materials. Polydora uncinata and B. knoxi exhibited similar larval development patterns (exolecithotrophy and adelphophagy), iteroparity and longer life span, suggesting a high reproductive potential. This study suggests that further monitoring of polydorid species is needed not only from the viewpoint of marine biology but also to survey the risk invasive species pose to commercially important molluscs in this region and worldwide.
Publisher: Cold Spring Harbor Laboratory
Date: 22-11-2018
DOI: 10.1101/476879
Abstract: The physiological constraints on bud burst in woody perennials, including the prerequisite for vascular development remain unresolved. Both light and tissue oxygen status have emerged as important cues for vascular development in other systems, however, light requirement appears to be facultative in grapevine, and the information related to the spatial variability of oxygen in buds is unclear. Here, we analysed apoplastic development at early stages of grapevine bud burst and combined molecular modelling with histochemical techniques to determine the pore size of cell walls in grapevine buds. The data demonstrate that quiescent grapevine buds were impermeable to apoplastic dyes (acid fuchsin and eosin Y) until after bud burst was established. The molecular exclusion size was calculated to be 2.1 nm, which would exclude most macromolecules except simple sugars and phytohormones. In vivo experiments show that grapevine buds were able to resume growth even following excision from the cane, and that the outer scales of grapevine buds may participate in the biochemical repression of bud burst. Furthermore, we demonstrate that the tissue oxygen partial pressure data correlated well with structural heterogeneity within the bud and differences in tissue density. These data consolidate evidence that the meristematic core becomes rapidly oxygenated during bud burst. Taken together, and when put in the context of earlier studies, these data provide solid evidence that the physiological and biochemical events that initiate bud burst reside within the bud, and question the role of long distance signalling in this developmental transition. The apoplastic pore size between the grapevine bud and the mother vine is dynamically regulated in the transition to bud burst. The molecular exclusion size of the apoplastic connection between the bud and cane is calculated 2.1 nm prior to the initiation of bud burst. The structural heterogeneity of the bud explains the spatial variance in tissue oxygen status, and the meristematic core is oxygenated during the initiation of bud burst. Long distance maternal signals are not a requirement for bud burst.
Publisher: Elsevier BV
Date: 08-2019
Publisher: Frontiers Media SA
Date: 07-04-2021
DOI: 10.3389/FNEUR.2021.663722
Abstract: Background: Reports vary on the incidence of vestibular dysfunction and dizziness in patients following cochlear implantation (CI). Disequilibrium may be caused by surgery at the cochlear base, leading to functional disturbances of the vestibular receptors and endolymphatic duct system (EDS) which are located nearby. Here, we analyzed the three-dimensional (3D) anatomy of this region, aiming to optimize surgical approaches to limit damage to the vestibular organ. Material and Methods: A total of 22 fresh-frozen human temporal bones underwent synchrotron radiation phase-contrast imaging (SR-PCI). One temporal bone underwent micro-computed tomography (micro-CT) after fixation and staining with Lugol's iodine solution (I 2 KI) to increase tissue contrast. We used volume-rendering software to create 3D reconstructions and tissue segmentation that allowed precise assessment of anatomical relationships and topography. Macerated human ears belonging to the Uppsala collection were also used. Drilling and insertion of CI electrodes was performed with metric analyses of different trajectories. Results and Conclusions: SR-PCI and micro-CT imaging demonstrated the complex 3D anatomy of the basal region of the human cochlea, vestibular apparatus, and EDS. Drilling of a cochleostomy may disturb vestibular organ function by injuring the endolymphatic space and disrupting fluid barriers. The saccule is at particular risk due to its proximity to the surgical area and may explain immediate and long-term post-operative vertigo. Round window insertion may be less traumatic to the inner ear, however it may affect the vestibular receptors.
Publisher: Oxford University Press (OUP)
Date: 16-03-2009
DOI: 10.1017/S1431927609090230
Abstract: The cusp epithelium is a specialized branch of the superior epithelium that surrounds the developing teeth of chitons and is responsible for delivering the elements required for the formation of biominerals within the major lateral teeth. These biominerals are deposited within specific regions of the tooth in sequence, making it possible to conduct a row by row examination of cell development in the cusp epithelium as the teeth progress from the unmineralized to the mineralized state. Cusp epithelium from the chiton Acanthopleura hirtosa was prepared using conventional chemical and microwave assisted tissue processing, for observation by light microscopy, conventional transmission electron microscopy (TEM) and energy filtered TEM. The onset of iron mineralization within the teeth, initiated at row 13, is associated with a number of dramatic changes in the ultrastructure of the apical cusp cell epithelium. Specifically, the presence of ferritin containing siderosomes, the position and number of mitochondria, and the structure of the cell microvilli are each linked to aspects of the mineralization process. These changes in tissue development are discussed in context with their influence over the physiological conditions within both the cells and extracellular compartment of the tooth at the onset of iron mineralization.
Publisher: Cambridge University Press (CUP)
Date: 05-2008
DOI: 10.1017/S0025315408000969
Abstract: A cold-shock technique was used to determine radula production rates for the chitons Acanthopleura hirtosa and Plaxiphora albida , and for the limpet Patelloida alticostata , which replaced their radular teeth at rates of 0.40, 0.36 and 0.51 rows d −1 , respectively. These rates are far slower than those determined previously for non-iron-mineralizing molluscs, suggesting that the improved working life of the teeth afforded by iron-mineralization acts to significantly reduce replacement rates. In addition, inductively coupled plasma-atomic emission spectroscopy has been used to determine the quantity of iron and other elements comprising the radula of each species. These data, used in conjunction with the radula production rates, reveal that A. hirtosa , Plaxiphora albida and Patelloida alticostata have daily radula mineralization requirements for iron of 3.06, 4.12 and 0.55 μg, respectively. Such information is vital for continuing studies related to the cellular delivery of ions and subsequent biomineralization of the tooth cusps in chitons and limpets.
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.CUB.2018.11.032
Abstract: It is well established that an array of avian species sense the Earth's magnetic field and use this information for orientation and navigation. While the existence of a magnetic sense can no longer be disputed, the underlying cellular and biophysical basis remains unknown. It has been proposed that pigeons exploit a magnetoreceptor based on magnetite crystals (Fe3O4) that are located within the lagena [1], a sensory epithelium of the inner ear. It has been hypothesised that these magnetic crystals form a bed of otoconia that stimulate hair cells transducing magnetic information into a neuronal impulse. We performed a systematic high-sensitivity screen for iron in the pigeon lagena using synchrotron X-ray fluorescence microscopy coupled with the analysis of serial sections by transmission electron microscopy. We find no evidence for extracellular magnetic otoconia or intracellular magnetite crystals, suggesting that if an inner ear magnetic sensor does exist it relies on a different biophysical mechanism.
Publisher: Oxford University Press (OUP)
Date: 04-03-2011
DOI: 10.1017/S1431927610094547
Abstract: The teeth of the marine mollusk Acanthopleura hirtosa are an excellent ex le of a complex, organic, matrix-mediated biomineral, with the fully mineralized teeth comprising layers of iron oxide and iron oxyhydroxide minerals around a calcium apatite core. To investigate the relationship between the various mineral layers and the organic matrix fibers on which they grew, sections have been prepared from specific features in the teeth at controlled orientations using focused ion beam processing. Compositional and microstructural details of heterophase interfaces, and the fate of the organic matrix fibers within the mineral layers, can then be analyzed by a range of transmission electron microscopy (TEM) techniques. Energy-filtered TEM highlights the interlocking nature of the various mineral phases, while high-angle annular dark-field scanning TEM imaging demonstrates that the organic matrix continues to exist in the fully mineralized teeth. These new insights into the structure of this complex biomaterial are an important step in understanding the relationship between its structural and physical properties and may help explain its high strength and crack-resistance behavior.
Publisher: Oxford University Press (OUP)
Date: 08-2019
Publisher: Elsevier BV
Date: 07-2009
DOI: 10.1016/J.JSB.2009.03.003
Abstract: Understanding biomineralization processes provides a route to the formation of novel biomimetic materials with potential applications in fields from medicine to materials engineering. The teeth of chitons (marine molluscs) represent an excellent ex le of a composite biomineralized structure, comprising variable layers of iron oxide, iron oxyhydroxide and apatite. Previous studies of fully mineralized teeth using X-ray diffraction, Raman spectroscopy and scanning electron microscopy (SEM) have hinted at the underlying microstructure, but have lacked the resolution to provide vital information on fine scale structure, particularly at interfaces. While transmission electron microscopy (TEM) is capable of providing this information, difficulties in producing suitable s les from the hard, complex biocomposite have hindered progress. To overcome this problem we have used focused ion beam (FIB) processing to prepare precisely oriented sections across interfaces in fully mineralized teeth. In particular, the composite structure is found to be more complex than previously reported, with additional phases (goethite and amorphous apatite) and interface detail observed. This combination of FIB processing and TEM analysis has enabled us to investigate the structural and compositional properties of this complex biocomposite at higher resolution than previously reported and has the potential to significantly enhance future studies of biomineralization in these animals.
Publisher: Oxford University Press (OUP)
Date: 2014
DOI: 10.1039/C3MT00336A
Abstract: Nanoscale secondary ion mass spectrometry demonstrates that subsets of Ca microdomains rapidly decrease after central nervous system injury.
Publisher: Humana Press
Date: 02-12-2014
DOI: 10.1007/978-1-62703-776-1_31
Abstract: The techniques of electron energy-loss spectroscopy (EELS) and energy-filtered TEM (EFTEM) are routinely applied in the physical sciences to map the distribution of elements at the nanoscale. EELS can also provide details of the bonding/valence of elements through variations in the fine structure of elemental peaks in the spectrum. While applications of these techniques in biology are less prevalent, their ability to detect both the light elements (e.g., C, N, O, P, S) that form the building blocks of biological systems and heavier elements (e.g., metals) makes them potentially important techniques for investigating local chemical variations in tissues and cells. Successful application of EELS and EFTEM in biology requires both an understanding of the techniques themselves and expertise in specimen preparation. Care must be taken to avoid the diffusion of elements during the preparation process to avoid artifacts in the resulting element maps. The power of the techniques is demonstrated here using tissue from a marine mollusc (chiton).
Publisher: Wiley
Date: 31-10-2012
DOI: 10.1002/JNR.22784
Abstract: CNS injury is often localized but can be followed by more widespread secondary degenerative events that usually result in greater functional loss. Using a partial transection model in rat optic nerve (ON). we recently demonstrated in vivo increases in the oxidative stress-associated enzyme MnSOD 5 min after injury. However, mechanisms by which early oxidative stress spreads remain unclear. In the present study, we assessed ion distributions, additional oxidative stress indicators, and ion channel immunoreactivity in ON in the first 24 hr after partial transection. Using nanoscale secondary ion mass spectroscopy (NanoSIMS), we demonstrate changes in the distribution pattern of Ca ions following partial ON transection. Regions of elevated Ca ions in normal ON in vivo rapidly decrease following partial ON transection, but there is an increasingly punctate distribution at 5 min and 24 hr after injury. We also show rapid decreases in catalase activity and later increases in immunoreactivity of the advanced glycation end product carboxymethyl lysine in astrocytes. Increased oxidative stress in astrocytes is accompanied by significantly increased immunoreactivity of the AMPA receptor subunit GluR1 and aquaporin 4 (AQP4). Taken together, the results indicate that Ca ion changes and oxidative stress are early events following partial ON injury that are associated with changes in GluR1 AMPA receptor subunits and altered ionic balance resulting from increased AQP4.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CC42098A
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.MSEC.2013.08.011
Abstract: A monomer that contained the RGD ligand motif was synthesized and copolymerized with 2-hydroxyethyl methacrylate using polymerization-induced phase separation methods to form poly(2-hydroxyethyl methacrylate)-based hydrogel sponges. The sponges had morphologies of aggregated polymer droplets and interconnected pores, the pores having dimensions in the order of 10 μm typical of PHEMA sponges. RGD-containing moieties appeared to be evenly distributed through the polymer droplets. Compared to PHEMA sponges that were not functionalized with RGD, the new sponges containing RGD allowed greater invasion by human corneal epithelial cells, by advancing the attachment of cells to the surface of the polymer droplets.
Publisher: The Royal Society
Date: 09-2017
DOI: 10.1098/RSOS.170591
Abstract: Moisture-harvesting lizards, such as the Australian thorny devil Moloch horridus , have remarkable adaptations for inhabiting arid regions. Their microstructured skin surface, with channels in between overlapping scales, enables them to collect water by capillarity and passively transport it to the mouth for ingestion. We characterized this capillary water transport for live thorny devils using high-speed video analyses. Comparison with preserved specimens showed that live lizards are required for detailed studies of skin water transport. For thorny devils, there was no directionality in cutaneous water transport (unlike Phrynosoma ) as 7 µl water droplets applied to the skin were transported radially over more than 9.2 mm. We calculated the total capillary volume as 5.76 µl cm −2 (dorsal) and 4.45 µl cm −2 (ventral), which is reduced to 50% filling by the time transportation ceases. Using micro-computed tomography and scanning electron microscopy of shed skin to investigate capillary morphology, we found that the channels are hierarchically structured as a large channel between the scales that is sub- ided by protrusions into smaller sub-capillaries. The large channel quickly absorbs water whereas the sub-capillary structure extends the transport distance by about 39% and potentially reduces the water volume required for drinking. An adapted dynamics function, which closely reflects the channel morphology, includes that ecological role.
Publisher: MDPI AG
Date: 18-07-2021
DOI: 10.3390/MIN11070780
Abstract: Titanium oxynitrides (Ti(N,O,C)) are abundant in xenolithic corundum aggregates in pyroclastic ejecta of Cretaceous volcanoes on Mount Carmel, northern Israel. Petrographic observations indicate that most of these nitrides existed as melts, immiscible with coexisting silicate and Fe-Ti-C silicide melts some nitrides may also have crystallized directly from the silicide melts. The TiN phase shows a wide range of solid solution, taking up 0–10 wt% carbon and 1.7–17 wt% oxygen these have crystallized in the halite (fcc) structure common to synthetic and natural TiN. Nitrides coexisting with silicide melts have higher C/O than those coexisting with silicate melts. Analyses with no carbon fall along the TiN–TiO join in the Ti–N–O phase space, implying that their Ti is a mixture of Ti3+ and Ti2+, while those with 1–3 at.% C appear to be solid solutions between TiN and Ti0.75O. Analyses with at% C have higher Ti2+/Ti3+, reflecting a decrease in fO2. Oxygen fugacity was 6 to 8 log units below the iron–wüstite buffer, at or below the Ti2O3–TiO buffer. These relationships and coexisting silicide phases indicate temperatures of 1400–1100 °C. Ti oxynitrides are probably locally abundant in the upper mantle, especially in the presence of CH4–H2 fluids derived from the deeper metal-saturated mantle.
Publisher: AIP Publishing
Date: 09-12-2013
DOI: 10.1063/1.4842015
Abstract: The mechanical properties of human tooth enamel depend not only on test locations but also on the indentation depth. However, it remains uncertain what roles the depth-dependant properties play in mechanical performance of enamel. Here we reveal that a change in the mechanical properties of enamel, in particular its strength, with increasing indentation depth promotes inelastic deformation in material. In doing so, the severity and extent of stress concentration is reduced. Furthermore, we observed that following unloading, self-recovery occurs in enamel. These findings improve our understanding of the underlying mechanisms responsible for the remarkable resilience of enamel.
Publisher: Oxford University Press (OUP)
Date: 07-2009
DOI: 10.1017/S1431927609095877
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009
Publisher: Society for Neuroscience
Date: 29-05-2020
DOI: 10.1523/ENEURO.0076-20.2020
Abstract: Contrast-enhanced X-ray imaging provides a non-destructive and flexible approach to optimizing contrast in soft tissues, especially when incorporated with Lugol’s solution (aqueous I 2 KI), a technique currently referred to as diffusible iodine-based contrast-enhanced computed tomography (diceCT). This stain exhibits high rates of penetration and results in excellent contrast between and within soft tissues, including the central nervous system. Here, we present a staining method for optimizing contrast in the brain of a cartilaginous fish, the brownbanded bamboo shark, Chiloscyllium punctatum , and a bony fish, the common goldfish, Carassius auratus , using diceCT. The aim of this optimization procedure is to provide suitable contrast between neural tissue and background tissue(s) of the head, thereby facilitating digital segmentation and volumetric analysis of the central nervous system. Both species were scanned before staining and were rescanned at time (T) intervals, either every 48 h ( C. punctatum ) or every 24 h ( C. auratus ), to assess stain penetration and contrast enhancement. To compare stain intensities, raw X-ray CT data were reconstructed using air and water calibration phantoms that were scanned under identical conditions to the s les. Optimal contrast across the brain was achieved at T = 240 h for C. punctatum and T = 96 h for C. auratus . Higher resolution scans of the whole brain were obtained at the two optimized staining times for all the corresponding specimens. The use of diceCT provides a new and valuable tool for visualizing differences in the anatomic organization of both the central and peripheral nervous systems of fish.
Start Date: 2013
End Date: 12-2016
Amount: $375,000.00
Funder: Australian Research Council
View Funded Activity