Transcriptional variation has been studied but post-transcriptional modification due to RNA editing has not been investigated in Plasmodium. We investigated developmental stage-specific RNA editing in selected genes in Plasmodium falciparum 3D7. We detected extensive amination- and deamination-type RNA editing at 8, 16, 24, 32, 40, and 46 h in tightly synchronized Plasmodium. Most of the editing events were observed in 8 and 16 h ring-stage parasites. Extensive A-to-G deamination-type editing was detected more during the 16 h ring stage (25%) than the 8 h ring stage (20%). Extensive U-to-C amination-type editing was detected more during the 16 h ring stage (31%) than the 8 h ring stage (22%). In 28S, rRNA editing converted the loop structure to the stem structure. The hemoglobin binding activity of PF3D7_0216900 was also altered due to RNA editing. Among the expressed 28S rRNA genes, PF3D7_0532000 and PF3D7_0726000 expression was higher. Increased amounts of the transcripts of these two genes were found, particularly PF3D7_0726000 in the ring stage and PF3D7_0532000 in the trophozoite and schizont stages. Adenosine deaminase (ADA) expression did not correlate with the editing level. This first experimental report of RNA editing will help to identify the editing machinery that might be useful for antimalarial drug discovery and malaria control.

2,3-Butanedione (BD) is a reactive diketone in artificial butter flavors that is thought to cause bronchiolitis obliterans in workers in microwave popcorn manufacturing. Bronchiolitis obliterans is generally not diagnosed until irreversible damage has occurred; therefore a biomarker of early exposure is needed. The potential systemic uptake of BD from inhalation exposure has not been evaluated. The objective here was to evaluate the systemic exposure of BD and binding to hemoglobin and albumin. [(14)C]BD was administered to male Harlan Sprague Dawley rats (100 mg/kg, intratracheal instillation) and B6C3F1/N mice (157 mg/kg, oropharyngeal aspiration). Blood and plasma was collected 24 h after administration and analyzed for (14)C content. At 24h, 0.88±0.07% of the administered dose was in rat blood, 0.66±0.06% in rat plasma, 0.38±0.13% in mouse blood and 0.17±0.05% in mouse plasma. Albumin binding in rats was 269±24.2 ng equiv./mg, which accounts for 38% of the radioactivity in plasma. In mice, binding was 85.0±22.3 ng equiv./mg albumin, which accounts for 51% of the radioactivity in plasma. The binding to hemoglobin in rats was 38.2±17.6 ng equiv./mg, and to globin was 29.1±3.96 ng equiv./mg. In mice, the binding to hemoglobin was 16.2±9.0 ng equiv./mg. The site(s) of adduction on hemoglobin and albumin was investigated by mass spectrometry. In rat globin, arginine adducts were detected at R-30 and R-104 of the beta chain in vitro and in vivo. In rat albumin, adducts were detected in vitro on R-219/221, R-360, and R-368, and in vivo on a variety of arginine residues. This study demonstrated that BD enters the systemic circulation and reacts with arginine on hemoglobin and albumin. These results indicate that hemoglobin and albumin adducts may be useful as biomarkers of BD exposure in humans.

Oxygen is essential for normal aerobic metabolism in mammals. Hypoxia is the presence of lower than normal oxygen content and pressure in the cell. Causes of hypoxia include hypoxemia (low blood oxygen content and pressure), impaired oxygen delivery, and impaired cellular oxygen uptake/utilization. Many compensatory mechanisms exist at the global, regional, and cellular levels to allow cells to function in a hypoxic environment. Clinical management of tissue hypoxia usually focuses on global hypoxemia and oxygen delivery. As we move into the future, the clinical focus needs to change to assessing and managing mission-critical regional hypoxia to avoid unnecessary and potential toxic global strategies. We also need to focus on understanding and better harnessing the body\'s own adaptive mechanisms to hypoxia.