Mary C. Boyce

Fire in forested catchments significantly alters organic matter fluxes by generating dissolved organic matter (DOM) different from that generated under non-fire conditions. Elucidating the composition of DOM is key to understanding its persistence in the post-fire environment. This laboratory study aimed to establish a relationship between DOM quantity and quality with aspects of fire regime. Soil and litter samples were collected from areas with different burn histories (described as Time Since Last Fire – TSLF). Each sample was subjected to burn temperature treatments simulating different burn severity regimes in a muffle furnace (at 250°C – low severity, 350°C – moderate severity, and 500°C – high severity), and compared with reference unburned samples. Leachates were extracted from the control and treated samples. Analysis of DOC concentrations and characterization of DOM using fluorescence spectroscopy in the extracted leachates support the hypothesis that moderate burn severity generated the highest concentrations of DOM. For forest litter, increasing burn temperature reduced mean DOC from 7.93, 4.48, 0.64, and 0.53 mg/L per g of litter across unburned, 250°C, 350°C, and 500°C treatments respectively. Similarly, for soil, the mean DOC concentration ranged from 0.56, 1.30, 1.09, and 0.24 mg/L per g of soil. Simple organic compounds are lost during thermal degradation, enriching condensed aromatic compounds in both litter and soil samples indicated by increasing relative concentration of C1 (humic-like DOM constituents) at all burn temperatures. However, such phenomena could not be identified using commonly applied bulk normalised absorbance measurements such as SUVA 254 . In addition, in recently burned areas, soil at moderate burn severity generated high DOC concentrations dominated by labile DOM, while such an effect was not observed with litter. The results of this work show for the first time that management burns, which are widely used in southwestern Australia, will have a greater influence on DOM than previously realized.

<div> Fire in forested catchments significantly alters organic matter fluxes by generating dissolved organic matter (DOM) different from that generated under non-fire conditions. Elucidating the composition of DOM is key to understanding its persistence in the post-fire environment. This laboratory study aimed to establish a relationship between DOM quantity and quality with aspects of fire regime. Soil and litter samples were collected from areas with different burn histories (described as Time Since Last Fire – TSLF). Each sample was subjected to burn temperature treatments simulating different burn severity regimes in a muffle furnace (at 250°C – low severity, 350°C – moderate severity, and 500°C – high severity), and compared with reference unburned samples. Leachates were extracted from the control and treated samples. Analysis of DOC concentrations and characterization of DOM using fluorescence spectroscopy in the extracted leachates support the hypothesis that moderate burn severity generated the highest concentrations of DOM. For forest litter, increasing burn temperature reduced mean DOC from 7.93, 4.48, 0.64, and 0.53 mg/L per g of litter across unburned, 250°C, 350°C, and 500°C treatments respectively. Similarly, for soil, the mean DOC concentration ranged from 0.56, 1.30, 1.09, and 0.24 mg/L per g of soil. Simple organic compounds are lost during thermal degradation, enriching condensed aromatic compounds in both litter and soil samples indicated by increasing relative concentration of C1 (humic-like DOM constituents) at all burn temperatures. However, such phenomena could not be identified using commonly applied bulk normalised absorbance measurements such as SUVA₂₅₄. In addition, in recently burned areas, soil at moderate burn severity generated high DOC concentrations dominated by labile DOM, while such an effect was not observed with litter. The results of this work show for the first time that management burns, which are widely used in southwestern Australia, will have a greater influence on DOM than previously realized. </div>

The circle size corresponds to the relative concentration and magnitude of DOM quantity and quality; the blue, yellow, and red circle represents the lowest, medium, and highest concentration/value, respectively.

<div> Fire in forested catchments significantly alters organic matter fluxes by generating dissolved organic matter (DOM) different from that generated under non-fire conditions. Elucidating the composition of DOM is key to understanding its persistence in the post-fire environment. This laboratory study aimed to establish a relationship between DOM quantity and quality with aspects of fire regime. Soil and litter samples were collected from areas with different burn histories (described as Time Since Last Fire – TSLF). Each sample was subjected to burn temperature treatments simulating different burn severity regimes in a muffle furnace (at 250°C – low severity, 350°C – moderate severity, and 500°C – high severity), and compared with reference unburned samples. Leachates were extracted from the control and treated samples. Analysis of DOC concentrations and characterization of DOM using fluorescence spectroscopy in the extracted leachates support the hypothesis that moderate burn severity generated the highest concentrations of DOM. For forest litter, increasing burn temperature reduced mean DOC from 7.93, 4.48, 0.64, and 0.53 mg/L per g of litter across unburned, 250°C, 350°C, and 500°C treatments respectively. Similarly, for soil, the mean DOC concentration ranged from 0.56, 1.30, 1.09, and 0.24 mg/L per g of soil. Simple organic compounds are lost during thermal degradation, enriching condensed aromatic compounds in both litter and soil samples indicated by increasing relative concentration of C1 (humic-like DOM constituents) at all burn temperatures. However, such phenomena could not be identified using commonly applied bulk normalised absorbance measurements such as SUVA₂₅₄. In addition, in recently burned areas, soil at moderate burn severity generated high DOC concentrations dominated by labile DOM, while such an effect was not observed with litter. The results of this work show for the first time that management burns, which are widely used in southwestern Australia, will have a greater influence on DOM than previously realized. </div>

Soil (n = 30) and litter (n = 30) samples were subjected to different treatments unburned and burned at 250°C, 350°C, and 500°C, generating 120 leachates each from soil and litter samples.

Summary of DOM quantitative indicators and DOM optical properties - the optical properties are adapted from Spiegel et al. [<a href="/article/info:doi/10.1371/journal.pwat.0000561#pwat.0000561.ref046" target="_blank">46</a>].

DOC represents DOC concentration mg/L per g of litter, TOC – total organic carbon, SUVA – SUVA₂₅₄, E2/E3 – absorption coefficient, FI – fluorescence index, BIX – Biological index, HIX – humification index,‌‌ C1 to C4 are DOM constituents determined by PARAFAC modelling.

Box plots showing the effect of burn temperature and TSLF (1 year vs 5 years) on DOM optical properties: SUVA₂₅₄ (for litter and soil, (Fig 3A) and (Fig 3B)), and then absorption coefficients E2/E3 ratio, and fluorescence indices – FI, BIX and HIX respectively for litter (Fig 3C, Fig 3E, Fig 3G and Fig 3I), and soil‌‌ (Fig 3D, Fig 3F, Fig 3H and Fig 3J).

Box plots showing variation of DOC concentration (mg/L per g of soil/litter sample) in leachate from litter and soil across different TSLF (time 1 is < 1 year and time 5 is > 5 years) and different burn temperatures.

<div> Fire in forested catchments significantly alters organic matter fluxes by generating dissolved organic matter (DOM) different from that generated under non-fire conditions. Elucidating the composition of DOM is key to understanding its persistence in the post-fire environment. This laboratory study aimed to establish a relationship between DOM quantity and quality with aspects of fire regime. Soil and litter samples were collected from areas with different burn histories (described as Time Since Last Fire – TSLF). Each sample was subjected to burn temperature treatments simulating different burn severity regimes in a muffle furnace (at 250°C – low severity, 350°C – moderate severity, and 500°C – high severity), and compared with reference unburned samples. Leachates were extracted from the control and treated samples. Analysis of DOC concentrations and characterization of DOM using fluorescence spectroscopy in the extracted leachates support the hypothesis that moderate burn severity generated the highest concentrations of DOM. For forest litter, increasing burn temperature reduced mean DOC from 7.93, 4.48, 0.64, and 0.53 mg/L per g of litter across unburned, 250°C, 350°C, and 500°C treatments respectively. Similarly, for soil, the mean DOC concentration ranged from 0.56, 1.30, 1.09, and 0.24 mg/L per g of soil. Simple organic compounds are lost during thermal degradation, enriching condensed aromatic compounds in both litter and soil samples indicated by increasing relative concentration of C1 (humic-like DOM constituents) at all burn temperatures. However, such phenomena could not be identified using commonly applied bulk normalised absorbance measurements such as SUVA₂₅₄. In addition, in recently burned areas, soil at moderate burn severity generated high DOC concentrations dominated by labile DOM, while such an effect was not observed with litter. The results of this work show for the first time that management burns, which are widely used in southwestern Australia, will have a greater influence on DOM than previously realized. </div>

<div> Fire in forested catchments significantly alters organic matter fluxes by generating dissolved organic matter (DOM) different from that generated under non-fire conditions. Elucidating the composition of DOM is key to understanding its persistence in the post-fire environment. This laboratory study aimed to establish a relationship between DOM quantity and quality with aspects of fire regime. Soil and litter samples were collected from areas with different burn histories (described as Time Since Last Fire – TSLF). Each sample was subjected to burn temperature treatments simulating different burn severity regimes in a muffle furnace (at 250°C – low severity, 350°C – moderate severity, and 500°C – high severity), and compared with reference unburned samples. Leachates were extracted from the control and treated samples. Analysis of DOC concentrations and characterization of DOM using fluorescence spectroscopy in the extracted leachates support the hypothesis that moderate burn severity generated the highest concentrations of DOM. For forest litter, increasing burn temperature reduced mean DOC from 7.93, 4.48, 0.64, and 0.53 mg/L per g of litter across unburned, 250°C, 350°C, and 500°C treatments respectively. Similarly, for soil, the mean DOC concentration ranged from 0.56, 1.30, 1.09, and 0.24 mg/L per g of soil. Simple organic compounds are lost during thermal degradation, enriching condensed aromatic compounds in both litter and soil samples indicated by increasing relative concentration of C1 (humic-like DOM constituents) at all burn temperatures. However, such phenomena could not be identified using commonly applied bulk normalised absorbance measurements such as SUVA₂₅₄. In addition, in recently burned areas, soil at moderate burn severity generated high DOC concentrations dominated by labile DOM, while such an effect was not observed with litter. The results of this work show for the first time that management burns, which are widely used in southwestern Australia, will have a greater influence on DOM than previously realized. </div>

Summarizes litter and soil properties before combustion. Superscripts indicate difference between Year 1 and Year 5 based on independent t-tests, conducted separately for litter and soil. No superscript is shown if results were not significant (p < 0.05).

Shows the relative percentage of four different DOM components (C1 to C4) identified using PARAFAC modelling. Different columns and rows show the relative percentage of DOM components among various burn treatments and TSLF.

Vegetable oils are increasingly valued for their nutritional and industrial applications, which has driven interest in underutilised tree oil crops such as Allanblackia parviflora.This study aimed to evaluate the relative influence of tree morphology, location, and ecological zone on the oil stability properties and fatty acid composition of A. parviflora seed and kernel oils in Ghana, with implications for domestication and breeding.Oils were extracted from kernel (dehulled seed) and whole seed samples obtained from 157 trees across 16 communities spanning three ecological zones.Free fatty acid content and peroxide values were determined, and their relationships with tree morphological traits, oil yield, soil properties, community, and ecological zone were assessed.Free fatty acid values ranged from 0.12% -0.50% (mean 0.37%) for kernel oils and 0.12% -0.69% (mean 0.53%) for seed oils, while peroxide values ranged from 1.59 -4.00 meq/kg (mean 2.11 meq/kg) and 2.00 -6.00 meq/kg (mean 3.84 meq/kg), respectively.Although substantial tree-to-tree variation was observed, oil stability indices were not significantly influenced by tree morphology, soil properties, community, or ecological zone.These findings indicate that A. parviflora oil quality is relatively stable across ecological and morphological gradients, suggesting that individual tree selection rather than site-specific factors may be more critical for breeding and domestication programmes.The results provide a scientific basis for selecting superior trees to enhance the commercialisation and sustainable development of A. parviflora as a highvalue indigenous oil crop.

Observational studies suggest higher intake of cruciferous vegetables (e.g., broccoli, cauliflower, kale) is associated with lower chronic disease risk (1,2) . Glucosinolates (GSL) and cysteine sulfoxides such as S- methyl cysteine sulfoxide (SMCSO) are sulfur-containing compounds found in high amounts in these vegetables (3) . Currently, no data exists on SMCSO levels in Australian-grown cruciferous vegetables and limited data exists for glucosinolates (GSL). The levels of SMCSO retained in cruciferous vegetables after various domestic cooking methods is unknown, and measurement of SMCSO and GSL levels in cooked Australian-grown cruciferous vegetables is limited. This study sought to (1) quantify SMCSO and GSL in Australian-grown cruciferous vegetables and (2) identify the most preferable cooking methods to retain levels in these vegetables. Using liquid chromatography mass spectrometry, we quantified SMCSO and ten GSL in seven cruciferous vegetables before and after steaming. We further quantified levels in broccoli before and after microwaving, stir-frying, and boiling. Each cooking method; steaming (3 minutes), microwaving (2 minutes), boiling (3 minutes), stir-frying (4 minutes); was chosen so vegetables remained firm and not overcooked to mimic healthy cooking recommendations (4) . Student t-tests were used to compare the differences in raw and steamed levels for all vegetables, and analysis of variance with Tukey post-hoc assessed the differences in raw and cooked broccoli (i.e., steamed, microwaved, boiled, stir-fried). Overall, SMCSO contributed greater dry weight (0.6–1.9%) than total GSL combined (0.3–1.2%). SMCSO levels from lowest to highest were Chinese cabbage &lt; white cabbage &lt; cauliflower &lt; kale &lt; red cabbage &lt; broccoli &lt; Brussels sprouts (6–19 mg/g dry weight [DW]) and GSL levels were cauliflower &lt; Chinese cabbage &lt; red cabbage &lt; kale &lt; broccoli &lt; white cabbage &lt; Brussels sprouts (3–12 mg/g DW). SMCSO increased after steaming (1–24%) in all vegetables except white cabbage (−31%), kale (−18%), and Chinese cabbage (−5%), but only reached statistical significance in Brussels sprouts (+16%, p &lt; 0.05). Most vegetables increased total GSL (ranging 1–34%) after steaming, except kale (−38%) and Chinese cabbage (−8%). Stir-frying and boiling broccoli led to significant losses in SMCSO (−34% and −50%, respectively) and in the two dominant GSL in broccoli; glucoraphanin (−47% and −52%, respectively) and glucobrassicin (−46% and –51%, respectively) (all p &lt; 0.05). We have quantified SMCSO and GSL levels in a selection of Australian-grown cruciferous vegetables (broccoli, kale, Brussels sprouts, cauliflower, red, white, and Chinese cabbages) before and after cooking. SMCSO and GSL levels were relatively stable after light steaming. Additionally, light steaming or microwaving were the most preferable methods to retain SMCSO and GSL levels in broccoli. Boiling or stir-frying broccoli were the least favourable. These results have important implications when estimating intake of these beneficial sulfur-containing compounds.

Seed or kernel cakes (meals) are by-products obtained after the oil has been extracted from plant seeds. Assessing the properties of seed cakes has, over the years, helped in finding an appropriate use for these seed by-products. This study sought to evaluate the protein content, total phenolic compounds (TPC), individual phenolic acids, and the phenolic profiles of Allanblackia parviflora seed and kernel cakes. Both seed and kernel cakes were bulk samples from different trees, representing their respective communities within three (3) ecological zones. The spatial variation of the seed and kernel cake characteristics was therefore evaluated. Protein content was determined by determining the total nitrogen percentage. TPC was determined using the Folin-Ciocalteau method. Individual phenolic acids were determined using both HPLC and LC-MS methods of analysis. The results obtained for kernel protein ranged from 7.8% to 11.4%, with a mean of 10.4%. The seed cake protein content ranged between 3.7% and 4.8%, with a mean of 4.3%. The total phenolic content (TPC) ranged from 35.6 - 61.1 mg GAE/g for kernel cake with a mean value of 53.3 mg GAE/g. Concerning seed cakes, TPC ranged from 22.9 - 44.8 mg GAE/g with a mean value of 35.7 mg GAE/g. Kernel protein and total phenolic content were higher than their respective seed cake protein and total phenolic content. The common individual phenolic acids used as standards were found not to be present in both seed and kernel cakes. However, two prominent peaks suspected to be phenolics appeared after our last standard had eluted. Results from this study suggest that Allanblackia parviflora kernel and seed cakes can be used to feed ruminants.

Currently no data exists on S -methyl-L-cysteine sulfoxide (SMCSO) levels in Australian-sourced vegetables and limited data exists for glucosinolates. The effect of various cooking methods on the retention of SMCSO and glucosinolates in Australian-sourced vegetables is also limited. This study measured SMCSO and ten glucosinolates in a selection of Australian-sourced Brassica vegetables, both raw and after steaming. We additionally measured SMCSO and glucosinolate levels in broccoli after microwaving, stir-frying and boiling. SMCSO contributed greater dry weight (0.6–1.9 %) than total glucosinolates combined (0.3–1.2 %) in these raw cruciferous vegetables. SMCSO levels from highest to lowest were: Brussels sprouts > broccoli > red cabbage > kale > cauliflower > white cabbage > Chinese cabbage; and glucosinolate levels were: Brussels sprouts > white cabbage > broccoli > kale > red cabbage > Chinese cabbage > cauliflower. Both SMCSO and the ten main glucosinolates quantified were relatively stable after light steaming across all vegetables measured, and after microwaving broccoli. Boiling and stir-frying broccoli led to significant losses in SMCSO and the two dominant glucosinolates, glucoraphanin and glucobrassicin (all p < 0.05). Mild steaming and/or microwaving were preferable in retaining SMCSO and glucosinolates, whilst boiling and stir-frying were least favorable. • S-methyl-L-cysteine sulfoxide (SMCSO) levels are highest in Brussels sprouts. • SMCSO and glucosinolates in Australian Brassica are similar to world levels. • SMCSO and glucosinolate levels are retained after light cooking (mild steaming, microwaving). • Boiling and stir-frying produce the greatest loss of SMCSO and glucosinolates.. • SMCSO constitutes a greater proportion of dry weight (0.6–1.9 %) than glucosinolates (0.3–1.2 %).

BACKGROUND: Higher cruciferous vegetable intake is associated with lower cardiovascular disease risk in observational studies. The pathways involved remain uncertain. We aimed to determine whether cruciferous vegetable intake (active) lowers 24-h brachial systolic blood pressure (SBP; primary outcome) compared to root and squash vegetables (control) in Australian adults with mildly elevated BP (SBP 120-160 mmHg inclusive). METHODS: In this randomized, controlled, crossover trial, participants completed two 2-week dietary interventions separated by a 2-week washout. Cruciferous vegetables were compared to root and squash vegetables (~ 300 g/day) consumed with lunch and dinner meals. Participants were blinded to which interventions were the active and control. Adherence was assessed using food diaries and biomarkers (S-methyl cysteine sulfoxide (SMCSO, active) and carotenoids (control)). Twenty-four-hour brachial ambulatory SBP and secondary outcomes were assessed pre- and post each intervention. Differences were tested using linear mixed effects regression. RESULTS: Eighteen participants were recruited (median (IQR) age: 68 (66-70); female: n = 16/18; mean ± SD clinic SBP: 135.9 ± 10.0 mmHg). For both interventions, 72% participants had 100% adherence (IQR: 96.4-100%). SMCSO and carotenoids were significantly different between interventions (mean difference active vs. control SMCSO: 22.93 mg/mL, 95%CI 15.62, 30.23, P < 0.0001; carotenoids: - 0.974 mg/mL, 95%CI - 1.525, - 0.423, P = 0.001). Twenty-four-hour brachial SBP was significantly reduced following the active vs. control (mean difference - 2.5 mmHg, 95%CI - 4.2, - 0.9, P = 0.002; active pre: 126.8 ± 12.6 mmHg, post: 124.4 ± 11.8 mmHg; control pre: 125.5 ± 12.1 mmHg, post: 124.8 ± 13.1 mmHg, n = 17), driven by daytime SBP (mean difference - 3.6 mmHg, 95%CI - 5.4, - 1.7, P < 0.001). Serum triglycerides were significantly lower following the active vs. control (mean difference - 0.2 mmol/L, 95%CI - 0.4, - 0.0, P = 0.047). CONCLUSIONS: Increased intake of cruciferous vegetables resulted in reduced SBP compared to root and squash vegetables. Future research is needed to determine whether targeted recommendations for increasing cruciferous vegetable intake benefits population health. TRIAL REGISTRATION: Clinical trial registry ACTRN12619001294145. https://www.anzctr.org.au.

Soft elastomeric composite materials constituting of an elastomeric matrix with dilute concentrations of thin, relatively higher modulus interfacial layers are presented and demonstrated to exhibit enhanced strain energy storage together with a bi‐/multi‐linear elastic behavior and stress mitigation ‐ all with little to no weight penalty. In this study, the governing mechanism for these features is revealed to be the activation of wrinkling of the embedded interfacial layers upon reaching a critical strain, thereby amplifying energy storage in both the matrix and the interfacial layers. Furthermore, the energy storage in the composite is substantially greater than the sum of the energy storage of the isolated material constituents. The new features of the composite material behavior can be tailored by the concentration of the interfacial layers, and the elastic properties of the elastomeric matrix and interfacial layers. The results are demonstrated and validated through analytical derivations, finite‐element analysis, and experiments. The analytical expressions provide the ability to quantitatively design and predict the material performance. These soft‐layered composites point to opportunities for expanding these enhancements to networked interlayers, multifunctional interlayers, and viscoelastic elastomeric matrices for viscous damping together with energy storage.

Thermoplastic polyurethanes (TPU) are block copolymeric materials composed of plastomeric"hard"and elastomeric"soft"domains, by which they exhibit highly resilient yet dissipative large deformation features depending on volume fractions and microstructures of the two distinct domains. Here, we develop a new methodology to address the microscopic deformation mechanisms in TPU materials with highly disordered microstructures. We propose new micromechanical models for randomly dispersed (or occluded) as well as randomly continuous hard domains, each within a continuous soft structure as widely found in representative TPU materials over a wide range of volume fractions, v$_{\mathrm{hard}}$ = 26.9% to 52.2%. The micromechanical modeling results are compared to experimental data on the macroscopic large strain behaviors reported previously (Cho et al. 2017). We explore the role of the dispersed vs. continuous nature of the geometric features of the random microstructures on shape recovery and energy dissipation at the microstructural level in this important class of phase-separated copolymeric materials.

Short chain fatty acids (SCFAs) are produced in the gut as a result of microbial action on ingested dietary fiber and have been associated with several health benefits. Herein an undergraduate student experiment that uses gas chromatography equipped with either a flame ionization detector or mass spectrometer for the analysis and quantitation of SCFAs in synthetic fecal material is described. The experiment provides students with valuable sample preparation and instrument operation skills and provides an opportunity for students to perform quantitative analysis using the method of internal standards. Subsequently, the experiment provides an opportunity for students to consolidate their learning of the key theoretical concepts including chromatographic separation by gas chromatography, and methods for confirming analyte identity using each detector type. Due to recent global interest in gut health, the experiment is topical and of interest to students. The experiment is designed for upper-division undergraduate analytical chemistry students.

Sulfur containing compounds including glucosinolates (GLS), sulforaphane (SFN) and S-methyl-l-cysteine sulfoxide (SMCSO) have been proposed to be partly responsible for the beneficial health effects of cruciferous vegetables. As such, greater understanding of their measurements within foods is important to estimate intake in humans and to inform dietary intervention studies. Herein is described a simple and sensitive method for simultaneous analysis of 20 GLS, SFN and SMCSO by liquid chromatography mass spectrometry. Analytes were effectively retained and resolved on an Xbridge C18 column. Detection can be achieved using high resolution or unit resolution mass spectrometry; the latter making the method more applicable to large studies. Quantitative analysis using calibration standards was demonstrated for 10 GLS, SFN and SMCSO. A further 10 GLS were tentatively identified using high resolution mass spectrometry. The use of surrogate GLS standards was shown to be unreliable, with closely related GLS displaying significantly different ionisation efficiencies.

Thermoplastic polyurethanes (TPU) are block copolymeric materials composed of plastomeric "hard" and elastomeric "soft" domains, by which they exhibit highly resilient yet dissipative large deformation features depending on volume fractions and microstructures of the two distinct domains. Here, we develop a new methodology to address the microscopic deformation mechanisms in TPU materials with highly disordered microstructures. We propose new micromechanical models for randomly dispersed (or occluded) as well as randomly continuous hard domains, each within a continuous soft structure as widely found in representative TPU materials over a wide range of volume fractions, v$_{\mathrm{hard}}$ = 26.9% to 52.2%. The micromechanical modeling results are compared to experimental data on the macroscopic large strain behaviors reported previously (Cho et al. 2017). We explore the role of the dispersed vs. continuous nature of the geometric features of the random microstructures on shape recovery and energy dissipation at the microstructural level in this important class of phase-separated copolymeric materials.

Honey bee nutritional health depends on nectar and pollen, which provide the main source of carbohydrates, proteins and lipids to individual bees. During malnutrition, insect metabolism accesses fat body reserves. However, this process in bees and its repercussions at the colony level are poorly understood. Using untargeted lipidomics and gene expression analysis, we examined the effects of different feeding treatments (starvation, sugar feeding and sugar + pollen feeding) on bees and correlated them with colony health indicators. We found that nutritional stress led to an increase in unsaturated triacylglycerols and diacylglycerols, as well as a decrease in free fatty acids in the bee fat body. Here, we hypothesise that stored lipids are made available through a process where unsaturations change lipid's structure. Increased gene expression of three lipid desaturases in response to malnutrition supports this hypothesis, as these desaturases may be involved in releasing fatty acyl chains for lipolysis. Although nutritional stress was evident in starving and sugar-fed bees at the colony and physiological level, only starved colonies presented long-term effects in honey production.

As wildfires are of increasing concern in a warming world, there is a need to understand how fire temperatures affect solute concentrations of forest litter and soils in drinking water catchments. In addition, the concentrations are expected to be affected by time since the previous fire. We sampled soil and litter from recently (2 months) and less recently (4.5 years) burnt sites from jarrah forest in SW Australia. The samples were heated at 250°C, 350°C, and 500°C for 30min followed by leaching to determine solute compositions at these temperatures and in unburnt samples. At 250°C–350°C, we found increased concentrations of manganese (Mn), arsenic (As), total phosphorus (TP), phosphate (PO43-), ammonia (NH4+), potassium (K), calcium (Ca), mangesium (Mg), cobalt (Co), barium (Ba), sulphate (SO42-), alkalinity and dissolved organic carbon in soils, as well as of zinc (Zn), As, Ca, Ba, alkalinity, aluminium (Al) and chromium (Cr) in litter. At 350°C–500°C, divalent cations and organic carbon declined, while soils generated very high Al and Cr concentrations. The time following the fire was important, with the more recent fire generating higher concentrations. The elevated concentrations in 250°C–350°C were attributed to a decomposition of organic matter and mineral transformations, including CaCO3 formation. Based on thermodynamics, we propose a couple of burn severity indicators: activities of calcium and carbonates that are calculated from pH, alkalinity and Ca concentration. The indicators do not only show the degree of post-fire transformations, but they also inform on CaCO3 formation. Further studies include: (1) application to field data, (2) association with organic contaminants, and (3) validation in other geographical locations.