The malaria parasite, Plasmodium falciparum, develops and multiplies in the human erythrocyte. It needs to synthesize considerable amounts of phospholipids (PLs), principally phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS). Several metabolic pathways coexist for their de novo biosynthesis, involving a dozen enzymes. Given the importance of these PLs for the survival of the parasite, we sought to determine their sources and to understand the connections and dependencies between the multiple pathways. We used three deuterated precursors (choline-d9, ethanolamine-d4, and serine-d3) to follow and quantify simultaneously their incorporations in the intermediate metabolites and the final PLs by LC/MS/MS. We show that PC is mainly derived from choline, itself provided by lysophosphatidylcholine contained in the serum. In the absence of choline, the parasite is able to use both other precursors, ethanolamine and serine. PE is almost equally synthesized from ethanolamine and serine, with both precursors being able to compensate for each other. Serine incorporated in PS is mainly derived from the degradation of host cell hemoglobin by the parasite. P. falciparum thus shows an unexpected adaptability of its PL synthesis pathways in response to different disturbances. These data provide new information by mapping the importance of the PL metabolic pathways of the malaria parasite and could be used to design future therapeutic approaches.
Ancient texts described that one of the most impressive ritual practices of the Celts during the Iron Age was to remove the heads of enemies killed in battle and to embalm them for display in front of the victors dwellings. An archaeological settlement excavation site in Le Cailar, in southern France, has revealed a considerable number of examples of this practice. It was documented by Classical authors and later by the archaeological recording of iconographic representations and skeletal remains of human heads. Weapons were also exhibited alongside the severed heads. Here we report the results of chemical investigations for the characterization of the biomarkers of embalming that are likely to be present in eleven fragments of these human cranial remains. These results may lead to answers to some of the archaeometric questions related to the subject of embalming in 3rd century BC Transalpine Gaul, thus advancing the knowledge of these ritual practices, documented by Greek Classical authors as part of the wider research into the proto-historic societies of the Mediterranean coastal region.
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