Biology subjects

Siracusa, F.

Publications and source records attributed to Siracusa, F..

4 recordsLinked to original sources

bioRxiv2025

Achieving Micrometer-Scale 4D X-ray tomography of Living Leaf Tissue in the Laboratory

A methodology for achieving micrometer-scale 4D X-ray lab microscopy of living leaf tissue was developed to overcome challenges associated with delicate tissues, radiation damage, and motion artifacts during in vivo imaging. The study focused on optimizing laboratory based X-ray micro-computed tomography (microCT) parameters to balance high-resolution imaging with minimized physiological stress and radiation dose quantification. Assessing the dose-safe imaging window required comparing vertical and horizontal leaf mounting setups. Results demonstrated that the horizontal setup provided greater stability, preventing tissue degradation and maintaining sample viability during continuous acquisitions lasting up to 22 hours ([~]15600 Gy). MicroCT capacities were clearly able to resolve microstructures at the cellular level, achieving a pixel size down to 1 {micro}m. Furthermore, this optimized methodology confirmed the ability to track the spatiotemporal dynamics of applied compounds such as iohexol and aggregated nanoparticles within the leaf tissue. This work establishes that accessible laboratory based microCT enables the in vivo 4D monitoring of anatomical and physiological changes in living plants.

plant biology↗

bioRxiv2025

3D X-ray microscopy lights up nanoparticles in plants

The discovery of novel plant fertilization strategies heavily relies on our capabilities to probe physiological processes in living plants with sub-cellular precision. State-of-the-art microscopy techniques are in general limited to surface investigation or they require elaborated tissue preparation and often destruction. X-ray microscopy has the potential to resolve some of these limitations by generating micro-to nanometer-scale 3D images deep into the tissue. We introduce experimental designs and the quantitative analysis methodologies, pioneering nanoscale ({approx}150 nm resolution) in-vivo 3D microscopy of plant tissue. We show the first direct in-vivo visualization of foliar-applied untagged nanoparticulate fertilizers deep under the leaf surface, not accessible by other microscopy methods. Ultimately, our approach provides the means for a direct observation of nanoparticle transport and dissolution in living plant tissue, a step critical for developing sustainable plant fertilization approaches.

plant biology↗

bioRxiv2019

Stromal cell-contact dependent PI3K and APRIL induced NF-κB signaling complement each other to prevent mitochondrial- and endoplasmic reticulum stress induced cell death of bone marrow plasma cells

Persistence of long-lived, memory plasma cells in the bone marrow depends on survival factors available in the bone marrow, provided in niches organized by stromal cells. Here we describe that ex vivo we can prevent apoptosis of bone marrow plasma cells by supplying direct cell contact with stromal cells and the soluble cytokine APRIL. Integrin-mediated contact of bone marrow plasma cells with stromal cells activates the PI3K signaling pathway, leading to critical inactivation of FoxO1/3 and preventing the activation of mitochondrial stress-associated effector caspases 3 and 7. Likely, inhibition of PI3K signaling in vivo ablates bone marrow plasma cells. APRIL signaling, via the NF-{kappa}B pathway, blocks activation of the endoplasmic reticulum stress-associated initiator caspase 12. Thus, stromal cell-contact induced PI3K and APRIL-induced NF-{kappa}B signaling provide necessary and complementary signals to maintain bone marrow memory plasma cells.

immunology↗

bioRxiv2019

Discrete populations of isotype-switched memory B lymphocytes are maintained in murine spleen and bone marrow

Here we describe tissue-resident memory B lymphocytes of spleen and bone marrow. Single cell transcriptomes and B cell receptor repertoires identify several exclusive populations of isotype-switched memory B cells (Bsm) in murine spleen and bone marrow, and one interconnected population of 10-20%. A population of marginal zone-like Bsm is located exclusively in the spleen while a novel population of quiescent Bsm is located exclusively in the bone marrow. Cells of two further populations, present in both, spleen and bone marrow, differ in repertoire between the two organs, i.e. are resident as well. Finally, another interconnected population of Bsm of the B1 lineage is present in spleen and bone marrow. In the bone marrow, all Bsm individually dock onto VCAM1+ stromal cells, resting in terms of activation, proliferation and mobility. The discrete B cell memory of bone marrow may be key to rapid secondary humoral responses to systemic antigens.

immunology↗