Archean phosphorus liberation induced by iron redox geochemistry.

The element phosphorus (P) is central to ecosystem growth and is proposed to be a limiting nutrient for life. The Archean ocean may have been strongly phosphorus-limited due to the selective binding of phosphate to iron oxyhydroxide. Here we report a new route to solubilizing phosphorus in the ancient oceans: reduction of phosphate to phosphite by iron(II) at low (<200 °C) diagenetic temperatures. Reduction of phosphate to phosphite was likely widespread in the Archean, as the reaction occurs rapidly and is demonstrated from thermochemical modeling, experimental analogs, and detection of phosphite in early Archean rocks. We further demonstrate that the higher solubility of phosphite compared to phosphate results in the liberation of phosphorus from ferruginous sediments. This phosphite is relatively stable after its formation, allowing its accumulation in the early oceans. As such, phosphorus, not as phosphate but as phosphite, could have been a major nutrient in early pre-oxygenated oceans.

Redox chemistry in the phosphorus biogeochemical cycle.

The element phosphorus (P) controls growth in many ecosystems as the limiting nutrient, where it is broadly considered to reside as pentavalent P in phosphate minerals and organic esters. Exceptions to pentavalent P include phosphine--PH3--a trace atmospheric gas, and phosphite and hypophosphite, P anions that have been detected recently in lightning strikes, eutrophic lakes, geothermal springs, and termite hindguts. Reduced oxidation state P compounds include the phosphonates, characterized by C-P bonds, which bear up to 25% of total organic dissolved phosphorus. Reduced P compounds have been considered to be rare; however, the microbial ability to use reduced P compounds as sole P sources is ubiquitous. Here we show that between 10% and 20% of dissolved P bears a redox state of less than +5 in water samples from central Florida, on average, with some samples bearing almost as much reduced P as phosphate. If the quantity of reduced P observed in the water samples from Florida studied here is broadly characteristic of similar environments on the global scale, it accounts well for the concentration of atmospheric phosphine and provides a rationale for the ubiquity of phosphite utilization genes in nature. Phosphine is generated at a quantity consistent with thermodynamic equilibrium established by the disproportionation reaction of reduced P species. Comprising 10-20% of the total dissolved P inventory in Florida environments, reduced P compounds could hence be a critical part of the phosphorus biogeochemical cycle, and in turn may impact global carbon cycling and methanogenesis.

An augmented passive immune therapy to treat fulminant bacterial infections.

In the early 1900s, passive immunization/antibody therapy was used to treat a variety of human ailments such as hypoimmunoglobulinemia, cancer and infectious disease. The advent of antibiotic therapy had relegated this type of therapy obsolete for treatment of infectious diseases. Emergence of multi-drug resistant pathogens along with novel monoclonal antibody production techniques has rekindled the interest in passive immunization (PI). An increase in the number of monoclonal antibody patent applications in the recent past suggests a renewed commercial interest in PI. Despite these developments, antibody therapy for infectious diseases has limitations including the need for large or frequent dosages. P4, a 28-amino acid peptide is a multi-lineage cellular activator. P4, along with infectious disease (i.e. Pathogen) specific immunoglobulin, has been shown in vitro and in vivo in mice to potentiate innate immunity. This review will discuss the progress made in passive antibody therapy, the challenges still to be surmounted, and the potential expanded role of an immune-potentiating peptide (bio-molecule) in the quest to utilize and revitalize passive immunization.