Phosphorus supply affects long-term carbon accumulation in mid-latitude ombrotrophic peatlands

Ombrotrophic peatlands are a globally important carbon store and depend on atmospheric nutrient deposition to balance ecosystem productivity and microbial decomposition. Human activities have increased atmospheric nutrient fluxes, but the impacts of variability in phosphorus supply on carbon sequestration in ombrotrophic peatlands are unclear. Here, we synthesise phosphorus, nitrogen and carbon stoichiometric data in the surface and deeper layers of mid-latitude Sphagnum-dominated peatlands across Europe, North America and Chile. We find that long-term elevated phosphorus deposition and accumulation strongly correlate with increased organic matter decomposition and lower carbon accumulation in the catotelm. This contrasts with literature that finds short-term increases in phosphorus supply stimulates rapid carbon accumulation, suggesting phosphorus deposition imposes a threshold effect on net ecosystem productivity and carbon burial. We suggest phosphorus supply is an important, but overlooked, factor governing long-term carbon storage in ombrotrophic peatlands, raising the prospect that post-industrial phosphorus deposition may degrade this carbon sink

Structure Activity Relationships of α_v Integrin Antagonists for Pulmonary Fibrosis by Variation in Aryl Substituents

Antagonism of α_vβ₆ is emerging as a potential treatment of idiopathic pulmonary fibrosis based on strong target validation. Starting from an α_vβ₃ antagonist lead and through simple variation in the nature and position of the aryl substituent, the discovery of compounds with improved α_vβ₆ activity is described. The compounds also have physicochemical properties commensurate with oral bioavailability and are high quality starting points for a drug discovery program. Compounds <b>33S</b> and <b>43E1</b> are pan α_v antagonists having <i>ca.</i> 100 nM potency against α_vβ_3, α_vβ_5, α_vβ₆, and α_vβ₈ in cell adhesion assays. Detailed structure activity relationships with these integrins are described which also reveal substituents providing partial selectivity (defined as at least a 0.7 log difference in pIC₅₀ values between the integrins in question) for α_vβ₃ and α_vβ₅