Lazarev, A. | Search bioRxiv

bioRxiv2024

X-ray Diffraction Reveals Periodicity in Murine Neocortex

BackgroundSensory experience impacts brain development. In the mouse somatosensory cortex, sensory deprivation via whisker trimming induces reductions in the perineuronal net (PNN), the size of neuronal cell bodies, the size and orientation of dendritic arbors, the density of dendritic spines, and the level of myelination, among other effects. New MethodsHere, we measured the X-ray diffraction patterns of mouse brain tissue to establish a novel method for examining nanoscale brain structures. Two groups of mice were examined: a control group and one that underwent 30 days of whisker-trimming from birth - an established method of sensory deprivation that affects the mouse barrel cortex (whisker sensory processing region of the primary somatosensory cortex). Mice were perfused, and primary somatosensory cortices (barrel cortex) were isolated for immunocytochemistry and X-ray diffraction imaging. ResultsX-ray images were characterized using a specially developed machine-learning approach, and the clusters that correspond to the two groups are well separated in the space of the principal components. The obtained values for sensitivity/specificity are 1/0.93, and the receiver operator curve classifier is 0.99. ConclusionsWe hypothesize that such separation is related to the development of different nanoscale structural components in the brains of control and sensory deprived mice. The effects of these nanoscale structural formations can be seen in PNN and other micro- and macro-scale structures and assemblies.

neuroscience↗

bioRxiv2019

Quantitative high-resolution imaging of live microbial cells at high hydrostatic pressure

The majority of the Earths microbial biomass exists in the Deep Biosphere, in the deep ocean and within the Earths crust. While other physical parameters in these environments, such as temperature or pH, can differ substantially, they are all under high-pressures. Beyond emerging genomic information, little is known about the molecular mechanisms underlying the ability of these organisms to survive and grow at pressures that can reach over 1000-fold pressure on the Earths surface. The mechanisms of pressure adaptation are also important to in food safety, with the increasing use of high-pressure food processing. Advanced imaging represents an important tool for exploring microbial adaptation and response to environmental changes. Here we describe implementation of a high-pressure sample chamber with a 2-photon scanning microscope system allowing for the first time, quantitative high-resolution two-photon imaging at 100 MPa of living microbes from all three kingdoms of life. We adapted this setup for Fluorescence Lifetime Imaging Microscopy with Phasor analysis (FLIM/Phasor) and investigated metabolic responses to pressure of live cells from mesophilic yeast and bacterial strains, as well as the piezophilic archaeon, Archaeoglobus fulgidus. We also monitored by fluorescence intensity fluctuation-based methods (scanning Number and Brightness (sN&B) and Raster scanning Imaging Correlation Spectroscopy (RICS)) the effect of pressure on the chromosome-associated protein HU and on the ParB partition protein in E. coli, revealing partially reversible dissociation of ParB foci and concomitant nucleoid condensation. SIGNIFICANCEThe majority of the Earths microbial biomass exists in high-pressure environments where pressures can reach over 100 MPa. The molecular mechanisms that allow microbes to flourish under such extreme conditions remain to be discovered. The high pressure, high resolution imaging system presented here revealed pressure dependent changes in metabolism and protein interactions in live microbial cells, demonstrating great promise for understanding deep life.

microbiology↗