Restoration of IFNγR Subunit Assembly, IFNγ Signaling and Parasite Clearance in Leishmania donovani Infected Macrophages: Role of Membrane Cholesterol

Despite the presence of significant levels of systemic Interferon gamma (IFNγ), the host protective cytokine, Kala-azar patients display high parasite load with downregulated IFNγ signaling in Leishmania donovani (LD) infected macrophages (LD-MØs); the cause of such aberrant phenomenon is unknown. Here we reveal for the first time the mechanistic basis of impaired IFNγ signaling in parasitized murine macrophages. Our study clearly shows that in LD-MØs IFNγ receptor (IFNγR) expression and their ligand-affinity remained unaltered. The intracellular parasites did not pose any generalized defect in LD-MØs as IL-10 mediated signal transducer and activator of transcription 3 (STAT3) phosphorylation remained unaltered with respect to normal. Previously, we showed that LD-MØs are more fluid than normal MØs due to quenching of membrane cholesterol. The decreased rigidity in LD-MØs was not due to parasite derived lipophosphoglycan (LPG) because purified LPG failed to alter fluidity in normal MØs. IFNγR subunit 1 (IFNγR1) and subunit 2 (IFNγR2) colocalize in raft upon IFNγ stimulation of normal MØs, but this was absent in LD-MØs. Oddly enough, such association of IFNγR1 and IFNγR2 could be restored upon liposomal delivery of cholesterol as evident from the fluorescence resonance energy transfer (FRET) experiment and co-immunoprecipitation studies. Furthermore, liposomal cholesterol treatment together with IFNγ allowed reassociation of signaling assembly (phospho-JAK1, JAK2 and STAT1) in LD-MØs, appropriate signaling, and subsequent parasite killing. This effect was cholesterol specific because cholesterol analogue 4-cholestene-3-one failed to restore the response. The presence of cholesterol binding motifs [(L/V)-X1–5-Y-X1–5-(R/K)] in the transmembrane domain of IFNγR1 was also noted. The interaction of peptides representing this motif of IFNγR1 was studied with cholesterol-liposome and analogue-liposome with difference of two orders of magnitude in respective affinity (KD: 4.27×10−9 M versus 2.69×10−7 M). These observations reinforce the importance of cholesterol in the regulation of function of IFNγR1 proteins. This study clearly demonstrates that during its intracellular life-cycle LD perturbs IFNγR1 and IFNγR2 assembly and subsequent ligand driven signaling by quenching MØ membrane cholesterol

Effects of nutrients and processing on the nutritionally important metabolites of Ulva sp. (Chlorophyta)

© 2018 Elsevier B.V. In consideration that, fatty acids bound within phospholipids may exhibit greater levels of bioavailability than neutral lipids, we investigated the effect of nutrient starvation on the phospholipid content and composition of cultivated Ulva biomass. Furthermore, we explored the simultaneous effects on the pigment and phenolic profiles and then correlation analysis to anti-oxidant and anti-inflammatory activity. High nutrient cultivation (nitrogen replete) provided a biomass with desirable n-6/n-3 (0.3) and 18:2n-6/18:3n-3 (0.5) ratios and beneficial 18:4n-3, 20:5n-3, 22:5n-3 fatty acids. These fatty acids dominated the abundant neutral lipid fraction, which comprised 62% of the lipid extract. The remaining phospholipids (38%) were characterised by high 16:0 (49.6%), 18:1n-7 (14.6%) and 18:3n-3 (13.6%) fatty acids. Nutrient-depleted samples had a 3-fold higher total fatty acid (TFA) content (12.05 mg·g−1 d.w, p < 0.0001) compared to nutrient replete samples (3.35 mg·g−1 d.w.). This occurred mostly within the neutral fraction, which represented 88% of the total lipids and the fatty acids 16:0 (4.02 ± 0.15 mg·g−1), 18:1n-7 (1.79 ± 0.06 mg·g−1), 18:2n-6 (2.30 ± 0.08 mg·g−1) and 18:3n-3 (1.09 ± 0.03 mg·g−1 d.w). Nutrient replete biomass yielded 1.5 mg·g−1 total chlorophyll, 0.1 mg·g−1 carotenoids and 1.6 mg·g−1 phenolics, whilst low nutrient growth conditions reduced the presence of pigments by 98%, phenolics by 34% and anti-oxidant activity by 87%. Significantly higher yields of pigment and phenolics were obtained using 95% ethanol for the extraction process, whilst acetone extracts were characterised by a higher proportion of carotenoids. All extracts from cultivated Ulva samples inhibited nitric oxide (NO) (≥81%) with acetone extracts demonstrating higher inhibition (94–97%) than 95% ethanol extracts (81–90%) with no significant effects observed between the two treatments. Thus, Ulva cultivated under high nutrients offers a sustainable source of potential biomass for n-3 PUFA, pigments and phenolics with attributable anti-oxidant and anti-inflammatory activity

Parameters affecting the analytical profile of fatty acids in the macroalgal genus Ulva.

The fatty acids (FA) of Ulva have potential to contribute to nutrition. However the large variability of FA profiles of Ulva species; thus the quality and quantity of FA in relation to nutrition is poorly defined. Herein we investigate the FA profile of 74 cultured Ulva samples crossing five culture regimes, six extraction regimes and four post-harvesting processes. This is compared alongside a comprehensive review of FA profiles of Ulva spp. With regard to the literature, Ulva is characterised by C16:0 (30.5±11.5%), C18:3 n-3 (14.5±6.3%), C18:4 n-3 (12.5±5.4%), C16:4 n-3 (8.9±4.8%) and C18:1 n-7 (10.1±4.0%). The investigated Ulva fell within the reported range of specific FA. High nutrient conditions showed the most desirable FA profile for health, along with the highest total FA content (56mgg(-1) dry weight equivalent) when extracted with an optimised protocol

Corrigendum to “Effects of nutrients and processing on the nutritionally important metabolites of Ulva sp. (Chlorophyta)” (Algal Research (2018) 35 (586–594), (S2211926418305678), (10.1016/j.algal.2018.09.016))

© 2019 Elsevier B.V. The authors wish to make the following corrigendum. Venus Shell Systems (VSS) provided the Ulva sp. used in this study. They are listed under the author affiliations, as well as in the Methods Section 2.1 as having provided the samples. To further clarify the involvement of the company we wish to make the following changes to the Conflicts of interest section. The company Venus Shell Systems (VSS), listed in the author affiliations, provided the cultivated Ulva sp. used in this study, obtained using a proprietary culture system. The authors declare that there was no significant financial support that could have influenced the outcome of the project. The research is free of bias and was conducted ethically in accord with the University of Wollongong's policy on external research collaboration. The authors would like to apologise for any inconvenience caused

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Fabrication and In Vitro Characterization of Electrochemically Compacted Collagen/Sulfated Xylorhamnoglycuronan Matrix for Wound Healing Applications

Skin autografts are in great demand due to injuries and disease, but there are challenges using live tissue sources, and synthetic tissue is still in its infancy. In this study, an electrocompaction method was applied to fabricate the densely packed and highly ordered collagen/sulfated xylorhamnoglycuronan (SXRGlu) scaffold which closely mimicked the major structure and components in natural skin tissue. The fabricated electrocompacted collagen/SXRGlu matrices (ECLCU) were characterized in terms of micromorphology, mechanical property, water uptake ability and degradability. The viability, proliferation and morphology of human dermal fibroblasts (HDFs) cells on the fabricated matrices were also evaluated. The results indicated that the electrocompaction process could promote HDFs proliferation and SXRGlu could improve the water uptake ability and matrices' stability against collagenase degradation, and support fibroblast spreading on the ECLCU matrices. Therefore, all these results suggest that the electrocompacted collagen/SXRGlu scaffold is a potential candidate as a dermal substitute with enhanced biostability and biocompatibility

Applications of seaweed extracts in Australian agriculture: past, present and future

A rapidly growing world population has highlighted the need to significantly increase food production in the context of a world with accelerating soil and water shortages as well as climatic stressors. This situation has generated new interest in the application of liquid seaweed extracts because of their potent plant growth-enhancing properties through metabolic benefits, triggering disease response pathways and increasing stress tolerance. The basis for these benefits is complex and poorly understood. Liquid seaweed extracts are complex and have been demonstrated to possess novel mechanisms for increasing crop productivity. The benefits of seaweed extracts to crops have previously been reviewed in the context of the northern hemisphere, but not in the context of Australia, its crops and unique stressors. This review considers the application of seaweed extracts in Australian agriculture by (i) introducing the history of the Australian liquid seaweed extract industry and (ii) focusing on evidence of Australian research related to seaweed extract composition, plant growth properties during plant establishment, pathogenic disease and new approaches to phenotyping the biological efficacy of seaweed extracts. This type of research is essential for future Australian agriculture to develop effective strategies for the use of liquid seaweed extracts