Microbial decomposition of organic matter and wetting–drying promotes aggregation in artificial soil but porosity increases only in wet-dry condition

Aggregation is one of the key properties influencing the function of soils, including the soil’s potential to stabilise organic carbon and create habitats for micro-organisms. The mechanisms by which organic matter influences aggregation and alters the pore geometry remain largely unknown. We hypothesised that rapid microbial processing of organic matter and wetting and drying of soil promotes aggregation and changes in pore geometry. Using microcosms of silicate clays and sand with either rapidly decomposable glucose or slowly decomposable cellulose, the degree of aggregation (P < 0.001), was greater in glucose treatments than controls that did not receive added carbon or microbial inoculum. We link this to microbial activity through measurements in soil respiration, phospholipids and microbially derived carbon. Our results demonstrate that rapid microbial decomposition of organic matter and microbially derived carbon promote aggregation and the aggregation process was particularly strong in the wet-dry condition (alternating between 30 % and 15 % water content) with significant modification of porosity (P < 0.05) of the aggregates

Spectroscopic and Chemometric Investigations into the Modes of Action of Anti-Diabetic and Anti-Cancer Drugs

Metabolic disorders such as Diabetes Mellitus, as a result of added sugars in form of fructose in the Western diet, are reaching epidemic proportions and better understanding on how to treat individuals with such disorders is required. The use of vanadium-derived complexes as dietary supplements offers one such approach due to their purported antidiabetic and anti-cancer effects; however, their mode(s) of action are still not completely understood. Fourier-transform infrared (FTIR) microspectroscopy/imaging in combination with Chemometrics was used to gain insights into biochemical changes induced by sugars and vanadium treatments at the cellular level. The insulin-responsive cell lines 3T3-L1 mouse adipocyte and HepG2 (hepatocarcinoma) were used as they are representative models of diabetes and its complications. Interpretation of results revealed that vanadate-fructose treatments increased oxidative stress in all cell types and resulted in apoptotic pathways that were characterised by lipid synthesis and peroxidation, resulting in lipotoxicity. Increased cell viability at low vanadate concentration and glucose resulted in protein synthesis rather than de novo lipid synthesis. At higher concentrations of vanadate, protein aggregation and the possible transition of HepG2 cells from an epithelial to a mesenchymal phenotype occurred. These cells may revert back to an epithelial phenotype when treated with normal supplemented media. Synchrotron and laboratory based hyperspectral imaging studies revealed common biochemical processes in adipocytes associated with all treatments, where various membrane and interior lipid compositions partitioned and lipid/fatty acid compartmentalisation was observed in chemical images, providing insights into the way these cells store lipids and fatty acids into specialised compartments

Pursuing pademelon provenance: a pilot study using portable XRF to trace field-collection of museum mammal specimens

Abstract Internationally, the value and usefulness of museum zoological specimens are compromised when supporting contextual data are lost or disconnected from the specimen. In this pilot study, twelve Macropodidae Thylogale (pademelon) skins with known provenance from the Australian Museum (Sydney) were analysed using portable X-ray fluorescence spectroscopy and principal component analysis. Elemental composition of preservative residues was assessed to establish if common patterns existed and could be associated with particular field collectors. Specimens were differentiated, and the field collector deduced, based on elemental analysis of preservative residues on skins. Each of the nineteenth century field collectors, in this study, were found to have applied the same or similar preservatives to zoological specimens over a number of years, which showed a consistent pattern of practice. Additionally, the specimens obtained by each of the field collectors could be distinguished from one another based on the preservative residues. These discoveries provide exciting prospects for the use of X-ray fluorescence spectroscopy to couple museum specimens with unknown contextual data via their field collector and associated archival evidence, and hence, enable a considerable enhancement of their value as museum and research objects

Raman spectroscopy applied to understanding Prehistoric Obsidian Trade in the Pacific Region

Obsidian is a natural volcanic glass which is amorphous and isotropic. These characteristics allow it to be easily shaped as little force is required to produce conchoidal fractures of predictable forms and sizes. A class of obsidian artefacts known as 'stemmed tools' have been found in locations situated across lowland Papua New Guinea and have been approximately dated to the early and middle Holocene periods (c. 10 000-3400 BP). The fragile nature of these tools, and their rarity, mean that non-destructive techniques are highly desirable for chemical analysis. In this study Raman spectroscopy was used, in conjunction with multivariate analysis, to discriminate between the major geological sources of obsidian within the Pacific Region. Application of principle component analysis (PCA) to data collected from forty-three samples from three major geological sources revealed the presence of three distinct clusters. In addition, Raman spectra were collected from an obsidian stemmed tool housed at the Pitt Rivers Museum at the University of Oxford, United Kingdom. The locality of the stemmed tool was tentatively assigned to the New Britain obsidian source group. The results are helpful for tracking social interaction during an early period of Pacific Prehistory. Crow