Characterization of extracellular vesicle miRNA identified in peripheral blood of chronic pancreatitis patients

Molecular and Cellular Biochemistry - Plasma-derived extracellular vesicles (EV) can serve as markers of cell damage/disease but can also have therapeutic utility depending on the nature of their...     

Lipidomic Analysis Links Mycobactin Synthase K to Iron Uptake and Virulence in M. tuberculosis

The prolonged survival of Mycobacterium tuberculosis (M. tb) in the host fundamentally depends on scavenging essential nutrients from host sources. M. tb scavenges non-heme iron using mycobactin and carboxymycobactin siderophores, synthesized by mycobactin synthases (Mbt). Although a general mechanism for mycobactin biosynthesis has been proposed, the biological functions of individual mbt genes remain largely untested. Through targeted gene deletion and global lipidomic profiling of intact bacteria, we identify the essential biochemical functions of two mycobactin synthases, MbtK and MbtN, in siderophore biosynthesis and their effects on bacterial growth in vitro and in vivo. The deletion mutant, ΔmbtN, produces only saturated mycobactin and carboxymycobactin, demonstrating an essential function of MbtN as the mycobactin dehydrogenase, which affects antigenicity but not iron uptake or M. tb growth. In contrast, deletion of mbtK ablated all known forms of mycobactin and its deoxy precursors, defining MbtK as the essential acyl transferase. The mbtK mutant showed markedly reduced iron scavenging and growth in vitro. Further, ΔmbtK was attenuated for growth in mice, demonstrating a non-redundant role of hydroxamate siderophores in virulence, even when other M. tb iron scavenging mechanisms are operative. The unbiased lipidomic approach also revealed unexpected consequences of perturbing mycobactin biosynthesis, including extreme depletion of mycobacterial phospholipids. Thus, lipidomic profiling highlights connections among iron acquisition, phospholipid homeostasis, and virulence, and identifies MbtK as a lynchpin at the crossroads of these phenotypes.     

The Early Neolithic site at Hoge Vaart, Almere, the Netherlands, with particular reference to non-diffusion of crop plants, and the significance of site function and sample location

The construction of a new motorway necessitated the excavation of an Early Neolithic site in the Dutch Flevopolder near the Hoge Vaart canal. In 1994-1996, an area of ca. 1700 m² was excavated in 0.5x0.5-m squares. The excavation revealed 150 surface hearths and more than a hundred deep hearth pits. The finds, mainly flint and pottery, as well as¹⁴C dates from charcoal demonstrated that the area had been used mainly during the Early Neolithic (ca. 4900–4500 cal. B.C.). The investigation of the Early Neolithic remains included detailed botanical analyses of 182 samples and hand-sorting by the excavation team, which included archaeobotanists, of tens of thousands of samples sieved over 2-mm-mesh sieves. No remains of cultivated plants were recognised among the 87 taxa (40 identified to species level) that were preserved, mainly in carbonised form. These results are compared with other Early Neolithic sites studied in the Netherlands, such as Swifterbant S3 and Schokland P14. The possible significance of site function and sample location as important factors influencing presence/absence of cultivated plant remains at a particular site is discussed.