Chytridiomycosis causes catastrophic organism-wide metabolic dysregulation including profound failure of cellular energy pathways

Chytridiomycosis is among several recently emerged fungal diseases of wildlife that have caused decline or extinction of naive populations. Despite recent advances in understanding pathogenesis, host response to infection remains poorly understood. Here we modelled a total of 162 metabolites across skin and liver tissues of 61 frogs from four populations (three long-exposed and one naive to the fungus) of the Australian alpine tree frog (Litoria verreauxii alpina) throughout a longitudinal exposure experiment involving both infected and negative control individuals. We found that chytridiomycosis dramatically altered the organism-wide metabolism of clinically diseased frogs. Chytridiomycosis caused catastrophic failure of normal homeostatic mechanisms (interruption of biosynthetic and degradation metabolic pathways), and pronounced dysregulation of cellular energy metabolism. Key intermediates of the tricarboxylic acid cycle were markedly depleted, including in particular a-ketoglutarate and glutamate that together constitute a key nutrient pathway for immune processes. This study was the first to apply a non-targeted metabolomics approach to a fungal wildlife disease and specifically to dissect the host-pathogen interface of Bd-infected frogs. The patterns of metabolite accumulation we have identified reveal whole-body metabolic dysfunction induced by a fungal skin infection, and these findings have broad relevance for other fungal diseases

Dissecting the role of G-protein signalling in primary metabolism in the wheat pathogen Stagonospora nodorum

Mutants of the wheat pathogenic fungus Stagonospora nodorum lacking G-protein subunits display a variety of phenotypes including melanization defects, primary metabolic changes and a decreased ability to sporulate. To better understand the causes of these phenotypes, Stagonospora nodorum strains lacking a Gα, Gβ or Gγ subunit were compared to a wild-type strain using metabolomics. Agar plate growth at 22 °C revealed a number of fundamental metabolic changes and highlighted the influential role of these proteins in glucose utilization. A further characterization of the mutants was undertaken during prolonged storage at 4 °C, conditions known to induce sporulation in these sporulation-deficient signalling mutants. The abundance of several compounds positively correlated with the onset of sporulation including the dissacharide trehalose, the tryptophan degradation product tryptamine and the secondary metabolite alternariol; metabolites all previously associated with sporulation. Several other compounds decreased or were absent during sporulation. The levels of one such compound (Unknown_35.27_2194_319) decreased from being one of the more abundant compounds to absence during pycnidial maturation. This study has shed light on the role of G-protein subunits in primary metabolism during vegetative growth and exploited the cold-induced sporulation phenomenon in these mutants to identify some key metabolic changes that occur during asexual reproduction

Human Milk Lipidomics: Current Techniques and Methodologies

Human milk contains a complex combination of lipids, proteins, carbohydrates, and minerals, which are essential for infant growth and development. While the lipid portion constitutes only 5% of the total human milk composition, it accounts for over 50% of the infant’s daily energy intake. Human milk lipids vary throughout a feed, day, and through different stages of lactation, resulting in difficulties in sampling standardization and, like blood, human milk is bioactive containing endogenous lipases, therefore appropriate storage is critical in order to prevent lipolysis. Suitable sample preparation, often not described in studies, must also be chosen to achieve the aims of the study. Gas chromatography methods have classically been carried out to investigate the fatty acid composition of human milk lipids, but with the advancement of other chromatographic techniques, such as liquid and supercritical fluid chromatography, as well as mass spectrometry, intact lipids can also be characterized. Despite the known importance, concise and comprehensive analysis of the human milk lipidome is limited, with gaps existing in all areas of human milk lipidomics, discussed in this review. With appropriate methodology and instrumentation, further understanding of the human milk lipidome and the influence it has on infant outcomes can be achieved

Advances in high throughput LC/MS based metabolomics: A review

Properly implemented, metabolic and lipidomic profiling can provide a deeper understanding of mammalian, plant and bacterial biology. These omics-tools have developed and matured over the last 40-years and are now being deployed to provide valuable information in epidemiological studies, drug toxicology and pharmacology, disease biology and progression and patient stratification. LC/MS has become the technology of choice for both metabolic and lipid profiling, due to its speed, sensitivity and structural elucidation capabilities. In the preceding two decades there have been many technological and methodological advances in LC/MS that have facilitated the evolution of the technology into a rugged, reliable, and easily deployed tool. These advances include, but are not limited to, improvements in chromatography (phases, columns, and delivery system), instruments for mass spectrometry, optimization of sample preparation, the introduction of ion mobility, data analysis tools, metabolite databases, harmonized protocols, and the more widespread use of quality control methods and reference standards/matrices. Here, recent developments and advances in high throughput liquid chromatography/high resolution mass spectrometry for metabolic phenotyping are described. These advances which may provide improved feature detection, increased laboratory efficiency and data quality, as well as “biomarker” identification, are discussed in relation to their potential application to the analysis of large clinical studies, or biobank collections

Influence of geographic origin on the sensory characteristics and wine composition of Vitis vinifera cv. Cabernet Sauvignon wines from Australia

The current study explores the relationship between sensory characteristics and wine composition of Cabernet Sauvignon wines in relation to Australian geographical indications (GIs). Descriptive sensory analysis was conducted to characterize the sensory attributes of commercially produced Cabernet Sauvignon wines from the Barossa Valley, Clare Valley, Coonawarra, Frankland River, Langhorne Creek, Mount Barker, Margaret River, McLaren Vale, Padthaway, and Wrattonbully GIs. Canonical variate analysis using the significant sensory attributes demonstrated that each GI could be distinguished from the others. A recently developed analytical method was used to analyze over 350 volatile compounds in the wines assessed, and measures of the major nonvolatile components were also determined. Compositional results were analyzed using partial least squares discriminant analysis to identify candidate components that were unique to certain GIs, including 2-isobutyl-3-methoxypyrazine, menthone, isomenthone, carvacrol, δ-octalactone, p-methylacetophenone, m-dimethoxybenzene, protein-precipitable tannin, and monomeric anthocyanins. Results demonstrate that Australian Cabernet Sauvignon wines have common sensory attributes related to geographic origin. The work also identifies a number of candidate components that are related to individual GIs which warrant further investigation. The study is the first to explore the concept of regionality in Cabernet Sauvignon wines from Australia

Fermentation-Guided Natural Products Isolation of a Grape Berry Triacylglyceride that Enhances Ethyl Ester Production

A full understanding of the origin, formation and degradation of volatile compounds that contribute to wine aroma is required before wine style can be effectively managed. Fractionation of grapes represents a convenient and robust method to simplify the grape matrix to enhance our understanding of the grape contribution to volatile compound production during yeast fermentation. In this study, acetone extracts of both Riesling and Cabernet Sauvignon grape berries were fractionated and model wines produced by spiking aliquots of these grape fractions into model grape juice must and fermented. Non-targeted SPME-GCMS analyses of the wines showed that several medium chain fatty acid ethyl esters were more abundant in wines made by fermenting model musts spiked with certain fractions. Further fractionation of the non-polar fractions and fermentation of model must after addition of these fractions led to the identification of a mixture of polyunsaturated triacylglycerides that, when added to fermenting model must, increase the concentration of medium chain fatty acid ethyl esters in wines. Dosage-response fermentation studies with commercially-available trilinolein revealed that the concentration of medium chain fatty acid ethyl esters can be increased by the addition of this triacylglyceride to model musts. This work suggests that grape triacylglycerides can enhance the production of fermentation-derived ethyl esters and show that this fractionation method is effective in segregating precursors or factors involved in altering the concentration of fermentation volatiles.Arts and Sciences, Irving K. Barber School of (Okanagan)Non UBCChemistry, Department of (Okanagan)ReviewedFacult

Origins of grape and wine aroma. Part 1. Chemical components and viticultural impacts

Wine is an ancient beverage and has been prized throughout time for its unique and pleasing favor. Wine favor arises from a mixture of hundreds of chemical components interacting with our sense organs, producing a neural response that is processed in th