Biology subjects

Gallardo, J.

Publications and source records attributed to Gallardo, J..

3 recordsLinked to original sources

bioRxiv2026

Protease-driven remodeling of stabilization networks during adenovirus assembly

At least thirteen different proteins form the adenovirus virion, including those bound to the dsDNA genome in the core. To produce infectious particles, the adenovirus protease (AVP) cleaves many of these proteins during genome packaging, using the viral genome as a cofactor. Here, we determine high-resolution structures of two types of adenovirus particles devoid of genome and core proteins and stalled at different AVP processing stages. We find that the N-terminal regions of penton base and internal minor coat protein IIIa are disordered when the core is absent and uncleaved packaging protein L1 52/55 kDa is present, likely enabling correction of early assembly errors at the vertex. Assignment of previously unmodeled densities reveals that proteins IIIa and VIII form long-range bridges linking vertex capsomers to the facet center before proteolytic maturation. Cleavage by AVP remodels these connections, diminishing capsid-wide stabilizing interactions and promoting the metastable state that prepares the mature virion for uncoating. Significance statementAdenoviruses cause disease and are major platforms for gene delivery, yet how their capsids are built and primed for infection remains incompletely understood. High-resolution cryo-EM structures of empty particles arrested at successive proteolytic maturation stages show previously unrecognized interactions that regulate capsid stability. Uncleaved packaging protein L1 52/55 kDa induces disorder at the icosahedral vertex during early assembly, likely facilitating error correction, while minor coat proteins IIIa and VIII serve as transient scaffolds stabilizing the capsid before proteolytic remodeling. Maturation thereby converts a stable assembly intermediate into a metastable particle ready for uncoating. These findings reveal how structural plasticity of minor coat proteins coordinates adenovirus assembly, maturation, and infectivity.

microbiology↗

bioRxiv2026

Co-limitation by stable, dynamic and directional habitat features shapes climate vulnerability in an alpine specialist

Alpine ecosystems are among the most climate sensitive on Earth, yet logistical challenges and detection biases often impede robust assessment of alpine dependent species. We investigated habitat associations and density patterns of the Sierra Nevada subspecies of the Gray-crowned Rosy-Finch (Leucosticte tephrocotis dawsoni), an alpine obligate and regional endemic, over five breeding seasons from 2018 to 2022 using hierarchical distance sampling and mark-recapture distance sampling to explicitly account for imperfect detection and spatial heterogeneity. Density estimates tracked annual snowpack variation, ranging from 4.77 individuals/km{superscript 2} in a low snow year to 12.08 individuals/km{superscript 2} in a high snow year. Abundance was highest near persistent snow patches that provide foraging habitat and near cliffs that provide nesting substrate, and declined sharply above approximately 10% woody cover, with densities approaching zero beyond approximately 25%, indicating a steep ecological threshold. In contrast, the proportion of surveyed blocks with detections remained relatively stable across years. Together, these patterns indicate a three timescale co-limitation framework in which breeding habitat is shaped by static features (cliffs), dynamic annual drivers (snowpack), and longer-term directional change (woody encroachment). By linking population density to climate sensitive habitat features, this study provides a high-resolution abundance-based baseline for long term monitoring and offers a framework for evaluating climate vulnerability in alpine and other resource-limited systems. Open Research StatementData necessary to replicate the analyses and results presented in this manuscript will be archived in the Dryad Digital Repository upon acceptance, with no embargo on the material. The R code associated with this manuscript is not novel. All analyses use publicly available packages and functions without modification, including mrds (v2.3.0), unmarked (v1.2.5), tidyverse (v2.0.0), MuMIn (v1.47.5), and standard ggplot2 visualization tools. All code is properly cited within the manuscript and publicly available through CRAN. Complete analysis scripts will be archived in Dryad alongside the data upon acceptance to facilitate full reproducibility of results.

ecology↗

bioRxiv2024

Local Synthesis of Reticulon-1C Lessens the Outgrowth of Injured Axons by Controlling Spastin Activity

The regenerative potential of developing cortical axons depends on intrinsic mechanisms, such as axon-autonomous protein synthesis, that are still not fully understood. An emerging factor in this regenerative response is the bi-directional interplay between microtubule dynamics and the axonal endoplasmic reticulum (ER). We hypothesize that locally synthesized ER proteins regulate microtubule dynamics and the regeneration of cortical axons. RNA data-mining identified the ER-shaping protein Reticulon-1 as a relevant candidate across eight axonal transcriptomes. Using microfluidic chambers, we demonstrate that local knockdown of Reticulon-1 synthesis increases the outgrowth of injured cortical axons while reducing their distal tubulin levels. Furthermore, we show by live-cell imaging that axonal Reticulon-1 knockdown restores the microtubule growth rate and track length modified by injury. Interestingly, local inhibition of the microtubule- severing protein Spastin prevents the axonal knockdown-mediated effects over outgrowth and tubulin levels. We demonstrate that the Reticulon-1C isoform is locally synthesized within axons and support its isoform-specific role in attenuating Spastin-mediated microtubule severing. These findings uncover a mechanism by which axonal protein synthesis finely controls microtubule dynamics and outgrowth upon injury.

neuroscience↗