Uhl, R. | Search bioRxiv

bioRxiv2025

Probing the zooarchaeological record across time and space for ancient pathogens

Zoonoses are among the greatest threats to human health, with many zoonotic pathogens believed to have emerged during prehistory. Palaeomicrobiological investigations of the zooarchaeological record hold potential to uncover the reservoirs, host ranges, and host adaptations of zoonotic pathogens but face challenges in identifying promising specimens and pathogen DNA preservation. We performed palaeopathological and genetic examinations of 346 skeletal elements from domesticated and wild animals collected from 34 Eurasian sites dating across the last six millennia. We identified 68 signatures of ancient (opportunistic) pathogens, including the important zoonotic pathogen Salmonella enterica, and found support that palaeopathological lesions provide guidance for specimen selection. For two pathogen species, Erysipelothrix rhusiopathiae and Streptococcus lutetiensis, we confirmed their ancient authenticity using phylogenetics, showcasing an approach to explore the relationship between ancient low-coverage genomes and their modern-day relatives. Our work presents a pathway to understanding prehistoric zoonotic diseases by integrating zooarchaeological, palaeopathological, and genetic data.

microbiology↗

bioRxiv2018

Fast, multicolor 3-D imaging of brain organoids with a new single-objective two-photon virtual light-sheet microscope

Human inducible pluripotent stem cells (hiPSCs) hold a large potential for disease modeling. hiPSC-derived human astrocyte and neuronal cultures permit investigations of neural signaling pathways with subcellular resolution. Combinatorial cultures, and three-dimensional (3-D) embryonic bodies enlarge the scope of investigations to multi-cellular phenomena. A the highest level of complexity, brain organoids that - in many aspects - recapitulate anatomical and functional features of the developing brain permit the study of developmental and morphological aspects of human disease. An ideal microscope for 3-D tissue imaging at these different scales would combine features from both confocal laser-scanning and light-sheet microscopes: a micrometric optical sectioning capacity and sub-micrometric spatial resolution, a large field of view and high frame rate, and a low degree of invasiveness, i.e., ideally, a better photon efficiency than that of a confocal microscope. In the present work, we describe such an instrument that belongs to the class of two-photon (2P) light-sheet microsocpes. Its particularity is that - unlike existing two- or three-lens designs - it is using a single, low-magnification, high-numerical aperture objective for the generation and scanning of a virtual light sheet. The microscope builds on a modified Nipkow-Petran spinning-disk scheme for achieving wide-field excitation. However, unlike the common Yokogawa design that uses a tandem disk, our concept combines micro lenses, dichroic mirrors and detection pinholes on a single disk. This design, advantageous for 2P excitation circumvents problems arising with the tandem disk from the large wavelength-difference between the infrared excitation light and visible fluorescence. 2P fluorescence excited in by the light sheet is collected by the same objective and imaged onto a fast sCMOS camera. We demonstrate three-dimensional imaging of TO-PRO3-stained embryonic bodies and of brain organoids, under control conditions and after rapid (partial) transparisation with triethanolamine and /ormamide (RTF) and compare the performance of our instrument to that of a confocal microscope having a similar numerical aperture. 2P-virtual light-sheet microscopy permits one order of magnitude faster imaging, affords less photobleaching and permits better depth penetration than a confocal microscope with similar spatial resolution.

biophysics↗