Black Périgord truffles (Tuber melanosporum) are the highest-priced edible fungus in the world due to their unique flavour, rarity, short growing season, difficulty in mass cultivating, and short shelf-life. The current industrial practices have not been effective in extending truffle shelf-life while preserving its aroma profiles. This study aimed to determine the effectiveness of several preservation methods on Australian-grown black Périgord truffles, which include assessing the changes in the volatile organic compounds (VOCs) of truffles treated with edible coatings, antimicrobial agents, or antioxidants such as chitosan, gum Arabic, kafirin, natamycin, tocopherol, vitamin C, and citric acid at the interval of 0, 7, and 14 days of storage. The study also aimed to assess the capability of gamma-cyclodextrin (γ-CD) in encapsulating truffle VOCs at the intervals of 0, 14, and 28 days of storage. Among all the edible coatings, chitosan-treated truffles had the least change in VOCs, especially the black truffle aroma volatile markers, 2-methyl-1-butanal, 2,4-dithiapentane, and dimethyl sulphide. Chitosan also resulted in no significant changes (P < 0.05) in the carbon dioxide emissions of truffle. The PCA plots showed that chitosan-coated samples displayed the least changes. The sole application of antimicrobial agents or antioxidants was ineffective in delaying the deterioration process. On the other hand, the results show that γ-CD was able to encapsulate 30 truffle’s VOCs, which included 3-methyl-1-butanal, 2-methyl-1-butanol, dimethyl sulphide, and 2,4-dithiapentane with no significant changes over the storage period.

Climate change and extreme climatic events, such as marine heatwaves (MHWs), are threatening seagrass ecosystems. Metabolomics can be used to gain insight into early stress responses in seagrasses and help to develop targeted management and conservation measures.We used metabolomics to understand the temporal and mechanistic response of leaf metabolism in seagrasses to climate change. Two species, temperate Posidonia australis and tropical Halodule uninervis, were exposed to a combination of future warming, simulated MHW with subsequent recovery period, and light deprivation in a mesocosm experiment.The leaf metabolome of P. australis was altered under MHW exposure at ambient light while H. uninervis was unaffected. Light deprivation impacted both seagrasses, with combined effects of heat and low light causing greater alterations in leaf metabolism. There was no MHW recovery in P. australis. Conversely, the heat-resistant leaf metabolome of H. uninervis showed recovery of sugars and intermediates of the tricarboxylic acid cycle under combined heat and low light exposure, suggesting adaptive strategies to long-term light deprivation.Overall, this research highlights how metabolomics can be used to study the metabolic pathways of seagrasses, identifies early indicators of environmental stress and analyses the effects of environmental factors on plant metabolism and health.

Osteoclasts are giant bone-digesting cells that harbor specialized lysosome-related organelles termed secretory lysosomes (SLs). SLs store cathepsin K and serve as a membrane precursor to the ruffled border, the osteoclast's 'resorptive apparatus'. Yet, the molecular composition and spatiotemporal organization of SLs remains incompletely understood. Here, using organelle-resolution proteomics, we identify member a2 of the solute carrier 37 family (Slc37a2) as a SL sugar transporter. We demonstrate in mice that Slc37a2 localizes to the SL limiting membrane and that these organelles adopt a hitherto unnoticed but dynamic tubular network in living osteoclasts that is required for bone digestion. Accordingly, mice lacking Slc37a2 accrue high bone mass owing to uncoupled bone metabolism and disturbances in SL export of monosaccharide sugars, a prerequisite for SL delivery to the bone-lining osteoclast plasma membrane. Thus, Slc37a2 is a physiological component of the osteoclast's unique secretory organelle and a potential therapeutic target for metabolic bone diseases.

Honey bees provide essential environmental services, pollinating both agricultural and natural ecosystems that are crucial for human health. However, these pollination services are under threat by outbreaks of the bacterial honey bee disease American foulbrood (AFB). Caused by the bacterium, Paenibacillus larvae, AFB kills honey bee larvae, converting the biomass to a foul smelling, spore-laden mass. Due to the bacterium's tough endospores, which are easily spread and extremely persistent, AFB management requires the destruction of infected colonies in many countries. AFB detection remains a significant problem for beekeepers: diagnosis is often slow, relying on beekeepers visually identifying symptoms in the colony and molecular confirmation. Delayed detection can result in large outbreaks during high-density beekeeping pollination events, jeopardising livelihoods and food security. In an effort to improve diagnostics, we investigated volatile compounds associated with AFB-diseased brood in vitro and in beehive air. Using Solid Phase Microextraction and Gas Chromatography Mass-Spectrometry, we identified 40 compounds as volatile biomarkers for AFB infections, including 16 compounds previously unreported in honey bee studies. In the field, we detected half of the biomarkers in situ (in beehive air) and demonstrated their sensitivity and accuracy for diagnosing AFB. The most sensitive volatile biomarker, 2,5-dimethylpyrazine, was exclusively detected in AFB-disease larvae and hives, and was detectable in beehives with <10 AFB-symptomatic larvae. These, to our knowledge, previously undescribed biomarkers are prime candidates to be targeted by a portable sensor device for rapid and non-invasive diagnosis of AFB in beehives.

Monitoring of seagrasses has mainly relied on traditional seagrass metrics (e.g., biomass), which deliver reliable information about mortality but are unable to inform about impacts on seagrass health at the very early stages of stress exposure. Metabolomics is a novel molecular technique which can be used for early stress-detection in plants and also for unravelling the underlying mechanisms of stress response. In the Swan-Canning Estuary, south-west Australia, the seagrass Halophila ovalis is impacted by seasonal changes in sediment-and nutrient-stress. To date, it is unknown how H. ovalis responds to these seasonal stressors on a molecular level. Here, we used a combined approach of traditional seagrass metrics and metabolomics to create a holistic picture of seasonal influences on seagrass condition. Leaf samples of H. ovalis were collected from six different locations in the Swan-Canning Estuary in both summer and spring. We detected strong differences in metabolite profiles and relative metabolite abundance between seasons, with growth- and/or development-related metabolites being up-regulated in spring and stress-related (secondary) metabolites being up-regulated in summer. Metabolites were mostly related to leaf δ13C signatures, a metric that has been previously associated with variation in light and pH in the Swan-Canning. We demonstrate that a holistic approach which includes metabolomics into ecological monitoring can help to improve our understanding of the mechanisms underlying molecular (stress) responses in seagrasses which is crucial knowledge for management and conservation measures locally and globally.

SummaryBlack Périgord truffle (Tuber melanosporum) is one of the most expensive fungi in the world that appreciated by gourmets. Studies have indicated the impact of growing location and soil microorganisms on the aroma profile of truffle. The aroma profile of West Australian black Périgord truffle (Tuber melanosporum) has not been previously reported, which was studied over a 14 day storage period. Sixty‐four compounds were identified in all truffle samples. Significant changes (P > 0.05) were observed in 11 key volatiles (carbon dioxide, acetaldehyde, 2‐butanone, 3‐methyl‐1‐butanal, toluene, 2‐butenal, formic acid 2‐methyl butyl ester, 3‐methyl‐1‐butanol, 6‐methyl‐2‐heptanol, 3‐octanol and dimethyl sulfoxide) over time. Comparison of these results against published aroma profile of European grown black Périgord truffle identified number of significant similarities and differences were also detected. Dimethyl sulfoxide, a compound previously identified in European grown white truffle (Tuber magnatum), was detected. Principle component analysis (PCA) showed that the major changes in the truffle aroma profile took place in the first 7 days of storage.

This study aimed to assess the effect of chitosan or gum Arabic edible coatings, with natamycin (200, 300, 400 mg/L) on the aroma profiles of Western Australian grown truffles at five storage intervals: 0, 7, 14, 21, and 28 days using solid-phase microextraction (SPME)-followed by gas chromatography-mass spectrometry (GC-MS). The population structure of the bacterial community of both untreated and chitosan-natamycin (400 mg/L) coated truffles were assessed using metagenomic sequencing analysis alongside GC-MS. The results demonstrated that all the coating treatments were able to have a positive impact in halting or delaying the changes of truffle aroma throughout the storage period, with chitosan-natamycin (400 mg/L) coating having the best preservation results compared to the other coatings. Only 9 volatile organic compounds (VOCs) were found to have significant changes in chitosan-natamycin (400 mg/L) coated truffles throughout the storage period compared to 11 VOCs in untreated controls. The result also demonstrated the gradual change of fresh truffle's bacteria communities over the storage period. Over 4 weeks of storage, the dominant bacterial classes of the truffles (α-Proteobacteria, Bacteroidia or Actinobacteria classes) were replaced by Bacteroidia, Actinobacteria, Deltaprotobacteria and γ-Proteobacteria classes. The preliminary results from this study show that edible coatings can affect the VOC and bacterial communities of the truffles which may have implications for future research into truffle preservation techniques.

Fetal glucocorticoid excess programs a range of detrimental outcomes in the adult phenotype, at least some of which may be due to altered adult adrenocortical function. In this study, we determined the effects of maternal dexamethasone treatment on offspring adrenal morphology and function, as well as the interactive effects of postnatal dietary omega-3 (n-3) fatty acids. This postnatal dietary intervention has been shown to alleviate many of the programming outcomes in this model, but whether this is via the effects on adrenal function is unknown. Dexamethasone acetate was administered to pregnant rats (0.75 microg/ml drinking water) from day 13 to term. Cross-fostered offspring were raised on either a standard or high-n-3 diet. Adrenal weight (relative to body weight) at 6 months of age was unaffected by prenatal dexamethasone, regardless of postnatal diet, and stereological analysis showed no effect of dexamethasone on the volumes of adrenal components (zona glomerulosa, zona fasciculata/reticularis or adrenal medulla). Expression of key steroidogenic genes (Cyp11a1 and Star) was unaffected by either prenatal dexamethasone or postnatal diet. In contrast, adrenal expression of Mc2r mRNA, which encodes the ACTH receptor, was higher in offspring of dexamethasone-treated mothers, an effect partially attenuated by the Hn3 diet. Moreover, stress-induced levels of plasma and urinary corticosterone and urinary aldosterone were elevated in offspring of dexamethasone-treated mothers, indicative of enhanced adrenal responsiveness. In conclusion, this study shows that prenatal exposure to dexamethasone does not increase basal adrenocortical activity but does result in a more stress-responsive adrenal phenotype, possibly via increased Mc2r expression.

The early-life environment, particularly in the fetus, is now recognised as an important determinant of several adult-onset diseases. Thus, increased frequencies of hypertension, obesity, dyslipidemia and type 2 diabetes, collectively referred to as the 'Metabolic Syndrome', have been linked to intrauterine growth retardation (IUGR), an assumed marker of a poor fetal environment. These links are thought to reflect 'developmental programming', the process by which various organ systems are affected during specific developmental periods of susceptibility such that consequent pathological effects emerge later in life. In our programming model of fetal glucocorticoid excess in the rat, we see consistent programming of high blood pressure, reduced insulin sensitivity in adult offspring (ref 1) and aberrant skeletal muscle gene expression (ref 2). Specifically, fetal glucocorticoid exposure programmed for elevated glucose transporter 4 (Glut4) and decreased uncoupling protein 3 (UCP3) mRNA in the gastrocnemius muscle of offspring at 6 months of age. AIM: This project aims to identify whether gastrocnemius morphology, in terms of myofibre crossectional size or proportion of fast to slow twitch fibres, is altered by fetal glucocorticoid excess. PROJECT: The task for this project is to investigate changes in the size and type of muscle fibres in the superficial gastrocnemius muscle from offspring of glucocorticoid-treated mothers. All tissues have already been collected; students will be required to cut, stain and conduct stereological analyses on these muscles. Histochemistry with NADH-TR will be used to differentiate fast and slow type myofibres within the gastrocnemius muscle (ref 3). The proportions of fast and slow twitch fibres will be compared for control and glucocorticoid-exposed offspring. Comparisons of myofibre size will be made using two different methods: 1) Unbiased stereological techniques to determine the average myofibre crossectional area 2) Image Pro analysis by outlining individual myofibres to calculate crossectional areas