The Lantern Vol. 3, No. 2, March 1935

• Puppets of Propaganda • Reluctance • Reflections From My Diary • Reverie • Bash Turner Enters the Limelight • The College Students\u27 Obligation • The Schwenkfelders • Love\u27s Desire • Verse • On the Squirt of a Grapefruit • Pioneers! • Whither Fraternities? • Mary Peters: A Book Review • Different as Night and Day • Ode to an Alley Cathttps://digitalcommons.ursinus.edu/lantern/1005/thumbnail.jp

Multi-omic detection of Mycobacterium leprae in archaeological human dental calculus

Mineralized dental plaque (calculus) has proven to be an excellent source of ancient biomolecules. Here we present a Mycobacterium leprae genome (6.6-fold), the causative agent of leprosy, recovered via shotgun sequencing of sixteenth-century human dental calculus from an individual from Trondheim, Norway. When phylogenetically placed, this genome falls in branch 3I among the diversity of other contemporary ancient strains from Northern Europe. Moreover, ancient mycobacterial peptides were retrieved via mass spectrometry-based proteomics, further validating the presence of the pathogen. Mycobacterium leprae can readily be detected in the oral cavity and associated mucosal membranes, which likely contributed to it being incorporated into this individual's dental calculus. This individual showed some possible, but not definitive, evidence of skeletal lesions associated with early-stage leprosy. This study is the first known example of successful multi-omics retrieval of M. leprae from archaeological dental calculus. Furthermore, we offer new insights into dental calculus as an alternative sample source to bones or teeth for detecting and molecularly characterizing M. leprae in individuals from the archaeological record.publishedVersio

Pharmacological validation of N-myristoyltransferase as a drug target in <i>Leishmania donovani</i>

Visceral leishmaniasis (VL), caused by the protozoan parasites Leishmania donovani and L. infantum, is responsible for ~30,000 deaths annually. Available treatments are inadequate and there is a pressing need for new therapeutics. N-Myristoyltransferase (NMT) remains one of the few genetically validated drug targets in these parasites. Here, we sought to pharmacologically validate this enzyme in Leishmania. A focused set of 1,600 pyrazolyl sulfonamide compounds was screened against L. major NMT in a robust high-throughput biochemical assay. Several potent inhibitors were identified with marginal selectivity over the human enzyme. There was little correlation between the enzyme potency of these inhibitors and their cellular activity against L. donovani axenic amastigotes and this discrepancy could be due to poor cellular uptake due to the basicity of these compounds. Thus, a series of analogues were synthesised with less basic centres. Although most of these compounds continued to suffer from relatively poor anti-leishmanial activity, our most potent inhibitor of LmNMT (DDD100097, Ki 0.34 nM), showed modest activity against L. donovani intracellular amastigotes (EC50 2.4 µM) and maintained a modest therapeutic window over the human enzyme. Two un-biased approaches, namely screening against our cosmid-based overexpression library and thermal proteome profiling (TPP), confirm that DDD100097 (compound 2) acts on-target within parasites. Oral dosing with compound 2 resulted in a 52% reduction in parasite burden in our mouse model of VL. Thus, NMT is now a pharmacologically validated target in Leishmania. The challenge in finding drug candidates remains to identify alternative strategies to address the drop-off in activity between enzyme inhibition and in vitro activity while maintaining sufficient selectivity over the human enzyme, both issues that continue to plague studies in this area

Multicentre study on the reproducibility of MALDI-TOF MS for nontuberculous mycobacteria identification

The ability of MALDI-TOF for the identification of nontuberculous mycobacteria (NTM) has improved recently thanks to updated databases and optimized protein extraction procedures. Few multicentre studies on the reproducibility of MALDI-TOF have been performed so far, none on mycobacteria. The aim of this study was to evaluate the reproducibility of MALDI-TOF for the identification of NTM in 15 laboratories in 9 European countries. A total of 98 NTM clinical isolates were grown on Lowenstein-Jensen. Biomass was collected in tubes with water and ethanol, anonymized and sent out to the 15 participating laboratories. Isolates were identified using MALDI Biotyper (Bruker Daltonics). Up to 1330 MALDI-TOF identifications were collected in the study. A score >= 1.6 was obtained for 100% of isolates in 5 laboratories (68.2-98.6% in the other). Species-level identification provided by MALDI-TOF was 100% correct in 8 centres and 100% correct to complex-level in 12 laboratories. In most cases, the misidentifications obtained were associated with closely related species. The variability observed for a few isolates could be due to variations in the protein extraction procedure or to MALDI-TOF system status in each centre. In conclusion, MALDI-TOF showed to be a highly reproducible method and suitable for its implementation for NTM identification

Multi-omic detection of <i>Mycobacterium leprae</i> in archaeological human dental calculus

Mineralized dental plaque (calculus) has proven to be an excellent source of ancient biomolecules. Here we present a Mycobacterium leprae genome (6.6-fold), the causative agent of leprosy, recovered via shotgun sequencing of sixteenth-century human dental calculus from an individual from Trondheim, Norway. When phylogenetically placed, this genome falls in branch 3I among the diversity of other contemporary ancient strains from Northern Europe. Moreover, ancient mycobacterial peptides were retrieved via mass spectrometry-based proteomics, further validating the presence of the pathogen. Mycobacterium leprae can readily be detected in the oral cavity and associated mucosal membranes, which likely contributed to it being incorporated into this individual's dental calculus. This individual showed some possible, but not definitive, evidence of skeletal lesions associated with early-stage leprosy. This study is the first known example of successful multi-omics retrieval of M. leprae from archaeological dental calculus. Furthermore, we offer new insights into dental calculus as an alternative sample source to bones or teeth for detecting and molecularly characterizing M. leprae in individuals from the archaeological record.publishedVersio

Co-Transport of Polycyclic Aromatic Hydrocarbons by Motile Microorganisms Leads to Enhanced Mass Transfer under Diffusive Conditions.

The environmental chemodynamics of hydrophobic organic chemicals (HOCs) are often rate-limited by diffusion in stagnant boundary layers. This study investigated whether motile microorganisms can act as microbial carriers that enhance mass transfer of HOCs through diffusive boundary layers. A new experimental system was developed that allows (1) generation of concentration gradients of HOCs under the microscope, (2) exposure and direct observation of microorganisms in such gradients, and (3) quantification of HOC mass transfer. Silicone O-rings were integrated into a Dunn chemotaxis chamber to serve as sink and source for polycyclic aromatic hydrocarbons (PAHs). This resulted in stable concentration gradients in water (>24 h). Adding the model organism <i>Tetrahymena pyriformis</i> to the experimental system enhanced PAH mass transfer up to hundred-fold (benzo­[a]­pyrene). Increasing mass transfer enhancement with hydrophobicity indicated PAH co-transport with the motile organisms. Fluorescence microscopy confirmed such transport. The effective diffusivity of <i>T. pyriformis</i>, determined by video imaging microscopy, was found to exceed molecular diffusivities of the PAHs up to four-fold. Cell-bound PAH fractions were determined to range from 28% (naphthalene) to 92% (pyrene). Motile microorganisms can therefore function as effective carriers for HOCs under diffusive conditions and might significantly enhance mobility and availability of HOCs