Biology subjects

Scandola, C.

Publications and source records attributed to Scandola, C..

3 recordsLinked to original sources

bioRxiv2025

Intracellular amorphous calcium carbonate biomineralization in methanotrophic gammaproteobacteria was acquired by horizontal gene transfer from cyanobacteria

Some bacteria genetically control the biomineralization of intracellular amorphous calcium carbonates (iACC) with potential implications for microbial physiology, evolution, bioremediation and biogeochemical cycling. Until now, this capacity has been documented in Cyanobacteria, the giant gammaproteobacterium Achromatium and a few magnetotactic Pseudomonadota and Nitrospirota. Here, we report the discovery of iACC biomineralization in members of the Methylococcaceae, a family of aerobic methanotrophic Gammaproteobacteria. A homolog of the ccyA gene, previously considered a diagnostic marker for iACC formation in Cyanobacteria, was identified in several Methylococcaceae genomes, based on a search of the conserved C-terminal (GlyZip)3 domain of the encoded calcyanin protein, with a sequence coverage higher than 60% and an E-value lower than 1e-20. Moreover, two cultivated strains, Methylococcus geothermalis and Methylococcus mesophilus, whose genomes contained the ccyA gene, were consistently shown to form iACC granules. The ccyA genes of Methylococcaceae and Microcystis share higher sequence similarity (47%) than with other Cyanobacteria (around 30%) within their common (GlyZip)3 domain, suggesting horizontal gene transfer (HGT) from an ancestral Microcystis-like cyanobacterium to Methylococcaceae. This finding extends the known taxonomic distribution of ccyA and suggests that the capability to biomineralize iACC was acquired by HGT, possibly in environments such as those close to the oxyclines of lakes, where Cyanobacteria and Methylococcaceae commonly co-exist. The discovery of iACC in methane-oxidizing Methylococcaceae highlights a previously unrecognized coupling between calcium carbonate biomineralization and methane cycling in aquatic environments, suggesting that iACC formation may play an overlooked role in microbial carbon storage and local geochemical regulation.

microbiology↗

bioRxiv2024

Megakaryocytes build a cage of extracellular matrix that controls their maturation and anchoring to the vascular niche

Megakaryocytes, the progenitor cells of blood platelets, play a crucial role in hemostasis by residing in the bone marrow and ensuring continuous platelet production. Unlike other hematopoietic cells, megakaryocytes do not enter the blood circulation intact. They remain anchored within the bone marrow while extending cytoplasmic protrusions called proplatelets through the sinusoidal endothelial barrier. These proplatelets subsequently fragment into functional platelets. This unique process of intravasation facilitates efficient platelet production while maintaining the megakaryocyte cell body within the bone marrow niche, thus preventing potential thrombotic complications. How the extracellular matrix (ECM) influences the delicate balance between megakaryocyte retention and proplatelet extension remains largely unknown. Here, we investigate the spatial organization and functional role of ECM components in the megakaryocyte vascular niche. Our findings reveal that laminin and collagen IV form three-dimensional (3D) ECM cages encompassing megakaryocytes and anchor them to the sinusoidal basement membrane. Gene deletion shows the existence of laminin 4 in the ECM cage that is necessary to maintain megakaryocyte-sinusoid interactions. Notably, megakaryocytes actively contribute to the ECM cage assembly; {beta}1/{beta}3 integrin knockout weakens these structures, increasing intravasation and entire megakaryocyte entry into circulation. The retention of megakaryocytes by these 3D ECM cages depends on dynamic remodeling processes. Inhibition of ECM proteolysis results in denser cage formation, increasing the frequence of immature megakaryocytes with impaired demarcation membrane system (DMS) development. Thus, the ECM cage represents a novel concept of an active and dynamic 3D microenvironment that is continuously remodeled and essential for maintaining megakaryocyte perivascular positioning. This specific microarchitecture guides megakaryocyte maturation and intravasation, underscoring the critical role of ECM microarchitecture and dynamics in megakaryocyte function. Key PointsO_LIMegakaryocytes form a three-dimensional (3D) cage composed of laminin and collagen IV connected to the basement membrane surrounding them. This microarchitecture stabilizes megakaryocytes within their vascular niche. C_LIO_LI{beta}1/{beta}3 integrins and MMP are key ECM cage regulators that assist megakaryocyte maturation and intravasation at the bone marrow-blood interface. C_LI

physiology↗

bioRxiv2024

Beta-1,6-glucan plays a central role in the structure and remodeling of the bilaminate fungal cell wall

The cell wall of human fungal pathogens plays critical roles as an architectural scaffold and as a target and modulator of the host immune response. Although the cell wall of the pathogenic yeast Candida albicans is intensively studied, one of the major fibrillar components in its cell wall, {beta}-1,6- glucan, has been largely neglected. Here, we show that {beta}-1,6-glucan is essential for bilayered cell wall organization, cell wall integrity and filamentous growth. For the first time, we show that {beta}-1,6- glucan production compensates the defect in mannan elongation in the outer layer of the cell wall. In addition, {beta}-1,6-glucan dynamics are also coordinated by host environmental stimuli and stresses with wall remodeling, where the regulation of {beta}-1,6-glucan structure and chain length is a crucial process. As we point out that {beta}-1,6-glucan is exposed at the yeast surface and modulate immune response, {beta}-1,6-glucan must be considered a key factor in host-pathogen interactions.

microbiology↗