Biology subjects

Leonardi, A.

Publications and source records attributed to Leonardi, A..

4 recordsLinked to original sources

bioRxiv2024

Illuminating root-soil mechanics

Soil compaction and escalating global drought increase soil strength and stiffness. It remains unclear which plant root biomechanical mechanisms/traits enable growth in these harsh conditions. Here, we combine synchrotron X-ray computed tomography with spatially resolved X-ray diffraction to characterize the biomechanics of a replica root-soil system. We map the strain field around the root tip, finding strong agreement with finite element simulations, thereby demonstrating a promising new in-vivo measurement protocol.

biophysics↗

bioRxiv2024

Evaluation of Autophagy in conjunctival fibroblasts

Vernal keratoconjunctivitis (VKC) is a serious eye allergy characterized by poorly understood pathogenic mechanisms and a lack of effective treatments. Autophagy, a process involved in both triggering and suppressing immune and inflammatory responses, plays a role in VKCs pathophysiology. Understanding autophagys involvement in VKC could lead to new treatment possibilities, such as utilizing specific topical substances to induce or inhibit autophagy and prevent severe complications of this eye condition. In our current protocol, we present a robust methodology established in our laboratory for studying autophagy in primary conjunctival fibroblasts. We assess autophagy through techniques like immunocytochemistry, immunoblotting, and qPCR.

cell biology↗

bioRxiv2020

A Cyclic Phosphoramidate Prodrug of 2-deoxy-2-fluoro-2-C-methylguanosine for the Treatment of Dengue Infection

Monophosphate prodrug analogs of 2-deoxy-2-fluoro-2-C-methylguanosine have been reported as potent inhibitors of hepatitis C virus (HCV) RNA-dependent RNA polymerase. These prodrugs also display potent anti-dengue activities in cellular assays although their prodrug moieties were designed to produce high levels of triphosphate in the liver. Since peripheral blood mononuclear cells (PBMCs) are one of the major targets of dengue virus, different prodrug moieties were designed to effectively deliver 2-deoxy-2-fluoro-2-C-methylguanosine monophosphate prodrugs and their corresponding triphosphates into PBMCs after oral administration. We identified a cyclic phosphoramidate prodrug 17 demonstrating a well-balanced anti-dengue cellular activity and in vitro stability profiles. In dogs, oral administration of 17 resulted in high PBMC triphosphate level, exceeding TP50 (the intracellular triphosphate concentration at which 50% of virus replication is inhibited) at 10 mg/kg. Compound 17 demonstrated 1.6- and 2.2 log viremia reduction in the dengue mouse model at 100 and 300 mg/kg twice daily, respectively. At 100 mg/kg twice daily, the terminal triphosphate concentration in PBMCs reached above TP50, defining for the first time the minimum efficacious dose for a nucleos(t)ide prodrug. In the two-week dog toxicity studies at 30 to 300 mg/kg/day, no observed adverse effect level (NOAEL) could not be achieved due to pulmonary inflammation and hemorrhage. The preclinical safety results suspended further development of 17. Nevertheless, present work has proven the concept that an efficacious monophosphate nucleoside prodrug could be developed for the potential treatment of dengue infection.

microbiology↗

bioRxiv2019

Epitranscriptomic regulation of the response to the air pollutant naphthalene in mouse lungs: from the perspectives of specialized translation and tolerance linked to the writer ALKBH8

BackgroundThe epitranscriptomic writer Alkylation Repair Homolog 8 (ALKBH8) is a tRNA methyltransferase that modifies the wobble uridine of selenocysteine tRNA to promote the specialized translation, via stop codon recoding, of proteins that contain selenocysteine. Corresponding selenoproteins play critical roles in protecting against reactive oxygen species and environmental stress. Using a novel animal model deficient in Alkbh8, we have investigated the importance of epitranscriptomic systems in the response to naphthalene (NA), an abundant polycyclic aromatic hydrocarbon, glutathione depleter and lung toxicant found in tobacco smoke, gasoline and mothballs.\n\nObjectivesOur goal was to define the molecular reprogramming of Alkbh8 deficient (Alkbh8def) mice and evaluate the roles that the epitranscriptomic writer ALKBH8 and selenoproteins play in mitigating NA-induced toxicity and lung dysfunction.\n\nMethodsWe performed basal lung analysis and NA exposure studies using WT, Alkbh8def and Cyp2abfgs-null mice, the latter of which lack the cytochrome P450 enzymes required for NA bioactivation. We characterized gene expression, molecular markers of damage, viability and tolerance to NA.\n\nResultsUnder basal conditions, lungs from Alkbh8def mice have increased oxidation-reduction potential (ORP) and 8-isoprostane levels, and have reprogrammed at the molecular level to display increased stress response transcripts. In addition, the ALKBH8 writer deficient lungs have a decreased GSH/GSSG ratio. Alkbh8def mice are more sensitive to NA than WT, showing higher susceptibility to lung damage both at the cellular and molecular levels. WT mice develop a tolerance to NA after 3 days, defined as resistance to a high challenging dose after repeated exposures, which is absent in Alkbh8def mice, with writer deficient not surviving NA exposure.\n\nDiscussionWe conclude that the epitranscriptomic writer ALKBH8 plays a protective role against NA-induced lung dysfunction and promotes NA tolerance. Our work provides an early example of how epitranscriptomic systems can regulate the response to environmental stress in vivo.

molecular biology↗