Suppression of Ribosomal Function Triggers Innate Immune Signaling through Activation of the NLRP3 Inflammasome

Some inflammatory stimuli trigger activation of the NLRP3 inflammasome by inducing efflux of cellular potassium. Loss of cellular potassium is known to potently suppress protein synthesis, leading us to test whether the inhibition of protein synthesis itself serves as an activating signal for the NLRP3 inflammasome. Murine bone marrow-derived macrophages, either primed by LPS or unprimed, were exposed to a panel of inhibitors of ribosomal function: ricin, cycloheximide, puromycin, pactamycin, and anisomycin. Macrophages were also exposed to nigericin, ATP, monosodium urate (MSU), and poly I:C. Synthesis of pro-IL-ß and release of IL-1ß from cells in response to these agents was detected by immunoblotting and ELISA. Release of intracellular potassium was measured by mass spectrometry. Inhibition of translation by each of the tested translation inhibitors led to processing of IL-1ß, which was released from cells. Processing and release of IL-1ß was reduced or absent from cells deficient in NLRP3, ASC, or caspase-1, demonstrating the role of the NLRP3 inflammasome. Despite the inability of these inhibitors to trigger efflux of intracellular potassium, the addition of high extracellular potassium suppressed activation of the NLRP3 inflammasome. MSU and double-stranded RNA, which are known to activate the NLRP3 inflammasome, also substantially inhibited protein translation, supporting a close association between inhibition of translation and inflammasome activation. These data demonstrate that translational inhibition itself constitutes a heretofore-unrecognized mechanism underlying IL-1ß dependent inflammatory signaling and that other physical, chemical, or pathogen-associated agents that impair translation may lead to IL-1ß-dependent inflammation through activation of the NLRP3 inflammasome. For agents that inhibit translation through decreased cellular potassium, the application of high extracellular potassium restores protein translation and suppresses activation of the NLRP inflammasome. For agents that inhibit translation through mechanisms that do not involve loss of potassium, high extracellular potassium suppresses IL-1ß processing through a mechanism that remains undefined

The 28 November 2020 landslide, tsunami, and outburst flood – a hazard cascade associated with rapid deglaciation at Elliot Creek, British Columbia, Canada

We describe and model the evolution of a recent landslide, tsunami, outburst flood, and sediment plume in the southern Coast Mountains, British Columbia, Canada. On November 28, 2020, about 18 million m3 of rock descended 1,000 m from a steep valley wall and traveled across the toe of a glacier before entering a 0.6 km2 glacier lake and producing >100-m high run-up. Water overtopped the lake outlet and scoured a 10-km long channel before depositing debris on a 2-km2 fan below the lake outlet. Floodwater, organic debris, and fine sediment entered a fjord where it produced a 60+km long sediment plume and altered turbidity, water temperature, and water chemistry for weeks. The outburst flood destroyed forest and salmon spawning habitat. Physically based models of the landslide, tsunami, and flood provide real-time simulations of the event and can improve understanding of similar hazard cascades and the risk they pose

Scouting for girls? Gender and the Scout Movement in Britain

This article was published in the journal, Gender, Place and Culture [© Taylor & Francis (Routledge)] and the definitive version is available at: http://dx.doi.org/10.1080/0966369X.2011.583342This article brings a feminist geopolitics to bear upon an analysis of the Boy Scout Movement in Britain in order to illustrate how an emphasis upon seemingly banal, embodied practices such as dressing, writing and crafting can provide a counter-view to prevailing notions of the elite, organisational `scripting' of individualised, geopolitical identities. Here, these practices undertaken by girls are understood not as subversive, or even transgressive, in the face of broader-scale constructions of the self and the collective body, but rather as related moments in the emergence of a complex, tension-ridden `movement' that exceed specific attempts at fixity along the lines of gender. Using archival data, this article examines various embodied practices by `girl scouts' that were made possible by such attempts at fixity but which also, in turn, opened up new spaces of engagement and negotiation. A cumulative shift from a determinedly masculine to a co-educational organisation over the course of the twentieth century thus reflects complex geographies of gender, national identity and citizenship and offers a historical contribution to the feminist geopolitics literature

Hemoglobin binding and catalytic heme extraction by IsdB NEAT domains

The Isd (Iron-regulated surface determinant) system is a multi-protein transporter that enables bacterium Staphylococcus aureus to take up iron from hemoglobin (Hb) during human infection. In this system, IsdB is a cell wall-anchored surface protein that contains 2 NEAT domains, one of which binds heme. IsdB rapidly extracts heme from Hb and transfers it to IsdA for relay into the bacterial cell. Using a series of recombinant IsdB constructs which included at least one NEAT domain, we demonstrated that both domains are required to bind Hb with high affinity (KD = 0.42 ± 0.05 µM) and to extract heme from Hb. Moreover, IsdB only extracted heme from oxidized metHb although it also bound oxyHb and the Hb-CO complex. In a reconstituted model of the biological heme relay pathway, IsdB catalyzed heme transfer from metHb to IsdA with a Km for metHb of 0.75 ± 0.07 µN and a kcat of 0.22 ± 0.01 s-¹. The latter is consistent with the transfer of heme from metHb to IsdB as being the rate-limiting step. With both NEAT domains and the linker region present in a single contiguous polypeptide, high affinity Hb binding was achieved, rapid heme uptake was observed, and multiple turnovers of heme extraction from metHb and transfer to IsdA were carried out, representing all known Hb-heme uptake functions of the full-length IsdB protein.Science, Faculty ofMicrobiology and Immunology, Department ofReviewedFacultyGraduat