Significance: Hosts sequester iron as a strategy to limit pathogen acquisition of this essential nutrient in a process termed nutritional immunity. Due to their in vitro antimicrobial activity, iron-binding proteins transferrins are suspected to play a role in iron sequestration. However, little is known about the in vivo role of transferrins. Here, we found thatDrosophila melanogasterexhibits infection-induced hypoferremia mediated by Transferrin 1. Due to excessive iron in hemolymph,Transferrin 1(Tsf1)-deficient flies are hypersusceptible to certain infections. Our study reveals that nutritional immunity is an important, previously unrecognized arm of immune defense inDrosophila. Using fly and bacterial genetics, we show that Tsf1 mediates nutritional immunity by sequestering iron from the pathogens in vivo on the whole-organism level.

The sorption of thallium (Tl) onto manganese (Mn) oxides critically influences its environmental fate and geochemical cycling and is also of interest in water treatment. Combined quantitative and mechanistic understanding of Tl sorption onto Mn oxides, however, is limited. We investigated the uptake of dissolved Tl(I) by environmentally relevant phyllo- and tectomanganates and used X-ray absorption spectroscopy to determine the oxidation state and local coordination of sorbed Tl. We show that extremely strong sorption of Tl onto vacancy-containing layered δ-MnO₂ at low dissolved Tl(I) concentrations (log K_d ≥ 7.4 for ≤10^–8 M Tl(I); K_d in (L/kg)) is due to oxidative uptake of Tl and that less specific nonoxidative Tl uptake only becomes dominant at very high Tl(I) concentrations (>10^–6 M). Partial reduction of δ-MnO₂ induces phase changes that result in inhibited oxidative Tl uptake and lower Tl sorption affinity (log K_d 6.2–6.4 at 10^–8 M Tl(I)) and capacity. Triclinic birnessite, which features no vacancy sites, and todorokite, a 3 × 3 tectomanganate, bind Tl with lower sorption affinity than δ-MnO₂, mainly as hydrated Tl⁺ in interlayers (triclinic birnessite; log K_d 5.5 at 10^–8 M Tl(I)) or tunnels (todorokite). In cryptomelane, a 2 × 2 tectomanganate, dehydrated Tl⁺ replaces structural K⁺. The new quantitative and mechanistic insights from this study contribute to an improved understanding of the uptake of Tl by key Mn oxides and its relevance in natural and engineered systems.