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1. Species origin affects the rate of response to inter‐annual growing season precipitation and nutrient addition in four Australian native grasslands

   https://doi.org/10.1111/jvs.12450  

   Morgan, John W. ; Dwyer, John M. ; Price, Jodi N. ; Prober, Suzanne M. ; Power, Sally A. ; Firn, Jennifer ; Moore, Joslin L. ; Wardle, Glenda M. ; Seabloom, Eric W. ; Borer, Elizabeth T. ; et al ( August 2016 , Journal of Vegetation Science)

   Predicted increases in temperature and changes to precipitation are expected to alter the amount of plant available nutrients, in turn, altering rates of primary production and exotic plant invasions. However, it remains unclear whether increased responses occur in wetter than average years, even in low fertility and low rainfall regions.

   Four Australian grasslands, including sites in arid Western Australia, semi‐arid Victoria, alpine Victoria and sub‐tropical Queensland.

   Using identical nutrient addition experiments, we use 6‐years of biomass, cover and species richness data to examine how rates of biomass production and native and exotic cover and richness are affected by growing season precipitation [proportion of yearly growing season precipitation (GSP) to long‐term meanGSP] and nutrient (N, P, K and micronutrients) addition.

   Rates of grassland productivity strongly increased with increasingGSP.GSPincreased rates of native cover but not native or exotic richness, nor rates of exotic cover change. We detected no significantNPKeffect on rates of grassland productivity, exotic cover or exotic richness change. In contrast,NPKaddition decreased rates of native cover change and fertilized plots had significantly fewer native species. We did not detect a significant interaction betweenNPKandGSP_.

   Grassland productivity was more strongly predicted by variation in growing season precipitation than by nutrient addition, suggesting it will vary with future changes in rainfall. Response to nutrients, however, depend on species origin, suggesting that increasing soil nutrient availability due to anthropogenic activities is likely to lead to negative effects on native species richness and cover.

    

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2. Dietary protein content and digestibility influences discrimination of amino acid nitrogen isotope values in a terrestrial omnivorous mammal

   https://doi.org/10.1002/rcm.9073  

   Whiteman, John P. ; Rodriguez Curras, Mauriel ; Feeser, Kelli L. ; Newsome, Seth D. ( April 2021 , Rapid Communications in Mass Spectrometry)

   Ecologists increasingly determine the δ¹⁵N values of amino acids (AA) in animal tissue; “source” AA typically exhibit minor variation between diet and consumer, while “trophic” AA have increased δ¹⁵N values in consumers. Thus, trophic‐source δ¹⁵N offsets (i.e., Δ¹⁵N_T‐S) reflect trophic position in a food web. However, even minor variations in δ¹⁵N_{source AA}values may influence the magnitude of offset that represents a trophic step, known as the trophic discrimination factor (i.e., TDF_T‐S). Diet digestibility and protein content can influence the δ¹⁵N values of bulk animal tissue, but the effects of these factors on AA Δ¹⁵N_T‐Sand TDF_T‐Sin mammals are unknown.

   We fed captive mice (Mus musculus) either (A) a low‐fat, high‐fiber diet with low, intermediate, or high protein; or (B) a high‐fat, low‐fiber diet with low or intermediate protein. Mouse muscle and dietary protein were analyzed for bulk tissue δ¹⁵N using elemental analyzer‐isotope ratio mass spectrometry (EA‐IRMS), and were also hydrolyzed into free AA that were analyzed for δ¹⁵N using gas chromatography‐combustion‐IRMS.

   As dietary protein increased, Δ¹⁵N_{Consumer‐Diet}slightly declined for bulk muscle tissue in both experiments; increased for AA in the low‐fat, high‐fiber diet (A); and remained the same or decreased for AA in the high‐fat, low‐fiber diet (B). The effects of dietary protein on Δ¹⁵N_T‐Sand on TDF_T‐Svaried by AA but were consistent between variables.

   Diets were less digestible and included more protein in Experiment A than in Experiment B. As a result, the mice in Experiment A probably oxidized more AA, resulting in greater Δ¹⁵N_{Consumer‐Diet}values. However, the similar responses of Δ¹⁵N_T‐Sand of TDF_T‐Sto diet variation suggest that if diet samples are available, Δ¹⁵N_T‐Saccurately tracks trophic position. If diet samples are not available, the patterns presented here provide a basis to interpret Δ¹⁵N_T‐Svalues. The trophic‐source offset of Pro‐Lys did not vary across diets, and therefore may be more reliable for omnivores than other offsets (e.g., Glu‐Phe).

    

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3. Elevated zinc transporter ZnT3 in the dentate gyrus of mast cell‐deficient mice

   https://doi.org/10.1111/ejn.14575  

   Wiqas, Amen ; LeSauter, Joseph ; Taub, Alana ; Austin, Rachel Narehood ; Silver, Rae ( September 2019 , European Journal of Neuroscience)

   Zinc is important in neurogenesis, but excessive levels can cause apoptosis and other pathologies leading to cognitive impairments. Mast cells are present in many brain regions including the hippocampus, an area rich in vesicular zinc. Mast cells contain zinc‐rich granules and a well‐developed mechanism for uptake of zinc ions; both features point to the potential for a role in zinc homeostasis. Prior work using the Timm stain supported this hypothesis, as increased labile zinc was detected in the hippocampus of mast cell‐deficient mice compared to wild‐type mice while no differences in total zinc were found between the two genotypes in the whole brain or other tissues. The current report further examines differences in zinc homeostasis between wild‐type and mast cell‐deficient mice by exploring the zinc transporter ZnT3, which transports labile zinc into synaptic vesicles. The first study used immunocytochemistry to localize ZnT3 within the mossy fibre layer of the hippocampus to determine whether there was differential expression of ZnT3 in wild‐type versus mast cell‐deficient mice. The second study used inductively coupled plasma mass spectrometry (ICP‐MS) to determine total zinc content in the whole dentate gyrus of the two genotypes. The immunocytochemical results indicate that there are higher levels of ZnT3 localized to the mossy fibre layer of the dentate gyrus of mast cell‐deficient mice than in wild‐type mice. TheICP‐MSdata reveal no differences in total zinc in dentate gyrus as a whole. The results are consistent with the hypothesis that mast cells participate in zinc homeostasis at the level of synaptic vesicles.

    

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4. Dietary and plasma carotenoids are positively associated with alpha diversity in the fecal microbiota of pregnant women

   https://doi.org/10.1111/1750-3841.15586  

   Schmidt, Kristen M. ; Haddad, Eliot N. ; Sugino, Kameron Y. ; Vevang, Karin R. ; Peterson, Lisa A. ; Koratkar, Revati ; Gross, Myron D. ; Kerver, Jean M. ; Comstock, Sarah S. ( January 2021 , Journal of Food Science)

   Because microbes use carotenoids as an antioxidant for protection, dietary carotenoids could be associated with gut microbiota composition. We aimed to determine associations among reported carotenoid intake, plasma carotenoid concentrations, and fecal bacterial communities in pregnant women. Pregnant women (n= 27) were enrolled in a two‐arm study designed to assess feasibility of biospecimen collection and delivery of a practical nutrition intervention. Plasma and fecal samples were collected and women were surveyed with a 24‐hr dietary checklist and recalls. Plasma carotenoids were analyzed by HPLC using photodiode array detection. Fecal bacteria were analyzed by 16S rRNA DNA sequencing. Results presented are cross‐sectional from the 36‐week gestational study visit combined across both study arms due to lack of significant differences between intervention and usual care groups (n= 23 women with complete data). Recent intake of carotenoid‐containing foods included carrots, sweet potatoes, mangos, apricots, and/or bell peppers for 48% of women; oranges/orange juice (17%); egg (39%); tomato/tomato‐based sauces (52%); fruits (83%); and vegetables (65%). Average plasma carotenoid concentrations were 6.4 µg/dL α‐carotene (AC), 17.7 µg/dL β‐carotene (BC), 11.4 µg/dL cryptoxanthin, 39.0 µg/dL trans‐lycopene, and 29.8 µg/dL zeaxanthin and lutein. AC and BC concentrations were higher in women who recently consumed foods high in carotenoids. CR concentrations were higher in women who consumed oranges/orange juice. Microbiota α‐diversity positively correlated with AC and BC. Microbiota β‐diversity differed significantly across reported intake of carotenoid containing foods and plasma concentrations of AC. This may reflect an effect of high fiber or improved overall dietary quality, rather than a specific effect of carotenoids.

   Little is known about the association between the gut microbiome and specific dietary microconstituents, such as carotenoids, especially during pregnancy. This research demonstrates that a carotenoid‐rich diet during pregnancy supports a diverse microbiota, which could be one mechanism by which carotenoids promote health.

    

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5. Therapeutic citizens and clients: diverging healthcare practices in Malawi's prenatal clinics

   https://doi.org/10.1111/1467-9566.12841  

   Zhou, Amy ( January 2019 , Sociology of Health & Illness)

   This article examines howHIVpolicies and the funding priorities of global institutions affect practices in prenatal clinics and the quality of healthcare women receive. Data consist of observations at health centres in Lilongwe, Malawi and interviews with providers (N = 37). I argue that neoliberal ideology, which structures the global health field, produces a fragmented healthcare system on the ground. Findings show two kinds of healthcare practices within the same clinic: donor‐fundedNGOs took onHIVservices while government providers focused on prenatal care.NGOpractices were defined bysurveillance, where providers targeted pregnantHIV‐positive women and intensively monitored their adherence to drug treatment. In contrast, state‐led practices were defined byrationing. Government providers worked with all pregnant women, but with staff and resource shortages, they limited time and services for each patient in order to serve everyone. This paper builds on concepts of therapeutic citizenship and clientship by exploring how global health priorities produce different conditions, practices and outcomes ofNGOand state‐led care.

    

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