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Lipids, with fatty acids (FA) as a crucial subset, have become a focal point for diverse medical, physiological, and ecological studies. However, a comprehensive assessment of the various pre-analytical FA extraction methods published in the scientific literature remains lacking. In this study, we examined the efficacy of seven well-established sample preparation methods, specifically focusing on their effectiveness in total lipid and fatty acid extraction and their impact on compound-specific stable hydrogen (δ 2 H) and carbon (δ 13 C) isotope values. We also considered the repercussions of FA removal efficacy on residual bulk tissue δ 2 H n analysis, because lipids typically have low δ 2 H values. Our findings showed that in most cases chloroform-based extraction methods outperformed those without chloroform. While discrepancies were not as evident for smaller organisms, such as plankton, marked variations were discernible in the extraction efficiencies for muscle and liver samples, which was also manifested in the residual bulk tissue δ 2 H n results. Notably, most extraction methods had little effect on specific δ 13 C or δ 2 H isotope values of FA; instead, an emphasis should be on using an extraction method that achieves optimal baseline peak separation of the chromatograms for C and H isotope measurements., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Lake ecosystems process and cycle organic substrates, thus serving as important bioreactors in the global carbon cycle. Climate change is predicted to increase extreme weather and precipitation events that can flush nutrients and organic matter from soils to streams and lakes. Here we report changes in stable isotopes (δ 2 H, δ 13 C, δ 15 N, or δ 18 O) of water, dissolved organic matter (DOM), seston, and zooplankton in a subalpine lake at short time resolution following an extreme precipitation event between early July to mid-August 2021. Water from excess precipitation and runoff remained in the lake epilimnion and coincided with increasing δ 13 C values of seston (-30 ‰ to -20 ‰), due to the input of carbonates and terrestrial organic matter. Particles settled into deeper lake layers after two days and contributed to the uncoupling of C and N cycling as the lake responded to this extreme precipitation event. Following the event, there was an increase in bulk δ 13 C values of zooplankton (from -35 ‰ to -32 ‰). Throughout this study, δ 13 C values of DOM remained stable throughout the water column (-29 ‰ to -28 ‰), while large isotopic fluctuations in DOM δ 2 H (-140 ‰ to -115 ‰) and δ 18 O (+9 ‰ to +15 ‰) values suggested DOM relocation and turnover. Integrating isotope hydrology, ecosystem ecology, and organic geochemistry offers an element-specific, detailed approach to investigating the impact of extreme precipitation events on freshwater ecosystems and particularly aquatic food webs., Competing Interests: Declaration of competing interest Travis B. Meador reports financial support was provided by Czech Science Foundation. Martin Kainz reports financial support was provided by State of Lower Austria., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Atopic dermatitis (AD) is an inflammatory skin disease in which epidermal barrier impairment, often owing to FLG null mutations, precedes immune hyperresponsiveness. Ichthyosis vulgaris is characterized by FLG null mutations and noninflamed dry skin. Netherton syndrome (NS), caused by SPINK5 null mutations, is characterized by generalized erythroderma with scaling and atopic manifestations. The goal of this work was to evaluate associations between specific skin disease features, such as ichthyotic and/or atopic manifestations, and the skin bacterial and fungal microbiota. Taxon diversity showed greater variation in the bacterial microbiota than in the fungal microbiota in the skin diseases. The relative abundances of Firmicutes (Staphylococcus) and Actinobacteria (Corynebacterium) were augmented in ichthyosis vulgaris, AD, and NS, whereas those of Proteobacteria/Enhydrobacter and Bacteroidetes were reduced, regardless of body site. Furthermore, proportions of Staphylococcus were correlated with transepidermal water loss and serum IgE levels. Nevertheless, the skin of patients with low to mild AD was overcolonized with Staphylococcus epidermidis and not with Staphylococcus aureus. Ascomycota were increased in both AD and NS, but from expansion of different fungal species. Finally, the expansion of pathologic bacteria in AD and NS might be supported by surrounding fungi. Thus, distinguishable bacterial and fungal skin dysbiosis in AD, NS, and ichthyosis vulgaris emphasizes disease-specific pathomechanisms., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)