Nano-imaging trace elements at organelle levels in substantia nigra overexpressing α-synuclein to model Parkinson’s disease

Abstract

Sub-cellular trace element quantifications of nano-heterogeneities in brain tissues offer unprecedented ways to explore at elemental level the interplay between cellular compartments in neurodegenerative pathologies. We designed a quasi-correlative method for analytical nanoimaging of the substantia nigra, based on transmission electron microscopy and synchrotron X-ray fluorescence. It combines ultrastructural identifications of cellular compartments and trace element nanoimaging near detection limits, for increased signal-to-noise ratios. Elemental composition of different organelles is compared to cytoplasmic and nuclear compartments in dopaminergic neurons of rat substantia nigra. They exhibit 150-460 ppm of Fe, with P/Zn/Fe-rich nucleoli in a P/S-depleted nuclear matrix and Ca-rich rough endoplasmic reticula. Cytoplasm analysis displays sub-micron Fe/S-rich granules, including lipofuscin. Following AAV-mediated overexpression of α-synuclein protein associated with Parkinson's disease, these granules shift towards higher Fe concentrations. This effect advocates for metal (Fe) dyshomeostasis in discrete cytoplasmic regions, illustrating the use of this method to explore neuronal dysfunction in brain diseases.

A single dose of lipopolysaccharide elicits autofluorescence in the mouse brain

“…The virus injection potential to induce AF was not evaluated in this study. However, lipofuscin may be a part of the innate immune defense system and that viral infection may induce AF ( Lemelle et al, 2020 ). Future studies, we will seek to determine the correlation between viruses, AF, and neurodegeneration.…”

Atomic spectrometry update – a review of advances in X-ray fluorescence spectrometry and its special applications

“…In-line holograms were collected with a pixel size of 40 nm and a eld of view of 80 mm. The XRF nanotomograms corresponded to a relatively course resolution (120-130 nm) and limited number of observation angles (30) collected using the y-scan approach. Apart from the nanoscale spatial resolution achieved, an especially interesting aspect of this study was the quantitative nature of the 3D elemental distributions of Ca (0-0.4 M), Cl (0-0.1 M), Fe (0-2 mM), K (0-0.2 M), Mn (0-0.8 mM), P (0-0.3 M), S (0-0.12 M) and Zn (0-1.0 mM).…”

“…An impressive quasi-correlative approach for analytical nanoimaging was presented by Lemelle et al 30 for research on Parkinson's disease. Trace-element distributions were established for subcellular structures inside neuronal cell bodies located in the substantia nigra tissue.…”

Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages

“…The use of synchrotron-based XRF for bioimaging of brain tissues at the nanoscale in Parkinson’s disease models was reported by Lemelle and co-workers. 130 The nano-imaging beam line at the European Synchrotron Radiation Facility was utilised to determine the elemental levels in the substantia nigra brain region. The workers applied a semi-quantitative calibration approach to estimate Ca, Fe, P, S and Zn in the acquired images from control rat brains and those overexpressing alpha-synuclein to model Parkinson’s disease.…”