Metabolomes and lipidomes of the infective stages of the gastrointestinal nematodes, Nippostrongylus brasiliensis and Trichuris muris

Soil-transmitted helminths, including hookworms and whipworms, infect billions of people worldwide. Their capacity to penetrate and migrate through their hosts’ tissues is influenced by the suite of molecules produced by the infective developmental stages. To facilitate a better understanding of the immunobiology and pathogenicity of human hookworms and whipworms, we investigated the metabolomes of the infective stage of Nippostrongylus brasiliensis third-stage larvae (L3) which penetrate the skin and Trichuris muris eggs which are orally ingested, using untargeted liquid chromatography–mass spectrometry (LC-MS). We identified 55 polar metabolites through Metabolomics Standard Initiative level-1 (MSI-I) identification from N. brasiliensis and T. muris infective stages, out of which seven were unique to excretory/secretory products (ESPs) of N. brasiliensis L3. Amino acids were a principal constituent (33 amino acids). Additionally, we identified 350 putative lipids, out of which 28 (all known lipids) were unique to N. brasiliensis L3 somatic extract and four to T. muris embryonated egg somatic extract. Glycerophospholipids and glycerolipids were the major lipid groups. The catalogue of metabolites identified in this study shed light on the biology, and possible therapeutic and diagnostic targets for the treatment of these critical infectious pathogens. Moreover, with the growing body of literature on the therapeutic utility of helminth ESPs for treating inflammatory diseases, a role for metabolites is likely but has received little attention thus far

Examining ozone susceptibility in the genus Musa (bananas)

Tropospheric ozone (O3) is a global air pollutant that adversely affects plant growth. Whereas the impacts of O3 have previously been examined for some tropical commodity crops, no information is available for the pantropical crop, banana (Musa spp.). To address this, we exposed Australia’s major banana cultivar, Williams, to a range of [O3] in open top chambers. In addition, we examined 46 diverse Musa lines growing in a common garden for variation in three traits that are hypothesised to shape responses to O3: (1) leaf mass per area; (2) intrinsic water use efficiency; and (3) total antioxidant capacity. We show that O3 exposure had a significant effect on the biomass of cv. Williams, with significant reductions in both pseudostem and sucker biomass with increasing [O3]. This was accompanied by a significant increase in total antioxidant capacity and phenolic concentrations in older, but not younger, leaves, indicating the importance of cumulative O3 exposure. Using the observed trait diversity, we projected O3 tolerance among the 46 Musa lines growing in the common garden. Of these, cv. Williams ranked as one of the most O3-tolerant cultivars. This suggests that other genetic lines could be even more susceptible, with implications for banana production and food security throughout the tropics

Diverse organ-specific localisation of a chemical defence, cyanogenic glycosides, in flowers of eleven species of Proteaceae.

Floral chemical defence strategies remain under-investigated, despite the significance of flowers to plant fitness. We used cyanogenic glycosides (CNglycs)-constitutive secondary metabolites that deter herbivores by releasing hydrogen cyanide, but also play other metabolic roles-to ask whether more apparent floral tissues and those most important for fitness are more defended as predicted by optimal defence theories, and what fine-scale CNglyc localisation reveals about function(s)? Florets of eleven species from the Proteaceae family were dissected to quantitatively compare the distribution of CNglycs within flowers and investigate whether distributions vary with other floral/plant traits. CNglycs were identified and their localisation in florets was revealed by matrix-assisted laser desorption ionisation mass spectrometry imaging (MALDI-MSI). We identified extremely high CNglyc content in floral tissues of several species (>1% CN), highly tissue-specific CNglyc distributions within florets, and substantial interspecific differences in content distributions, not all consistent with optimal defence hypotheses. Four patterns of within-flower CNglyc allocation were identified: greater tissue-specific allocations to (1) anthers, (2) pedicel (and gynophore), (3) pollen presenter, and (4) a more even distribution among tissues with higher content in pistils. Allocation patterns were not correlated with other floral traits (e.g. colour) or taxonomic relatedness. MALDI-MSI identified differential localisation of two tyrosine-derived CNglycs, demonstrating the importance of visualising metabolite localisation, with the diglycoside proteacin in vascular tissues, and monoglycoside dhurrin across floral tissues. High CNglyc content, and diverse, specific within-flower localisations indicate allocations are adaptive, highlighting the importance of further research into the ecological and metabolic roles of floral CNglycs

Divergent responses of above- and below-ground chemical defence to nitrogen and phosphorus supply in waratahs (Telopea speciosissima)

Plant nutrition can affect the allocation of resources to plant chemical defences, yet little is known about how phosphorus (P) supply, and relative nitrogen (N) and P supply, affect chemical defences, especially in species with intrinsically conservative nutrient use adapted to P-impoverished soils. Waratah (Telopea speciosissima (Sm.) R.Br.), like other Proteaceae, is adapted nutrient-poor soils. It was identified as having cyanogenic glycosides (CNglycs) throughout the plant. T. speciosissima seedlings were grown for 15 weeks under two N and P concentrations. CNglycs (N-based defence) and nutrients were quantified in above- and below-ground organs; foliar carbon (C)-based phenolics and tannins were also quantified. CNglyc concentrations in roots were on average 51-fold higher than in above-ground tissues and were affected by both N and P supply, whereas foliar CNglyc concentrations only responded to N supply. Leaves had high concentrations of C-based defences, which increased under low N, and were not correlated with N-based defences. Greater root chemical defence against herbivores and pathogens may be important in a non-mycorrhizal species that relies on basal resprouting following disturbance. The differing responses of secondary chemistry in above- and below-ground organs to P and N demonstrate the importance of broadening the predominantly foliar focus of plant defence studies

Anti-inflammatory properties of novel galloyl glucosides isolated from the Australian tropical plant Uromyrtus metrosideros

Two new galloyl glucosides, galloyl-lawsoniaside A (4) and uromyrtoside (6), were isolated from the polar fraction of Uromyrtus metrosideros leaf extract along with another four previously identified phytochemicals (1, 2, 3, and 5). The structures of these six compounds were characterised using low and high-resolution mass spectrometry (L/HRMS) and 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy. These compounds were not toxic to human peripheral blood mononuclear cells (PBMCs) at 10 μg/mL over 24 h, yet showed significant in vitro suppression of proinflammatory cytokines involved in the pathogenesis of inflammatory bowel disease (IBD). Specifically, the release of interferon γ (IFN-γ), interleukin (IL)-17A, and IL-8 from phorbol myristate acetate/ionomycin (P/I) and anti-CD3/anti-CD28-activated cells were significantly suppressed by compounds 4 and 5. Interestingly, no effect on tumour necrosis factor (TNF) release was observed. These results show that the newly characterised compound 4 has promising cytokine suppressive properties, which could be further investigated as a candidate for IBD treatment