Biology subjects

Gonzalez, A. G.

Publications and source records attributed to Gonzalez, A. G..

5 recordsLinked to original sources

bioRxiv2026

Zinc isotope fractionation in native and cloned mosses: implications for standardized pollution biomonitoring

Mosses are widely used as biomonitors of atmospheric trace-metal deposition, but metal retention by the moss itself may modify source-related isotope signatures. Here, controlled Zn adsorption experiments, stable Zn isotope measurements, surface acid-base characterization, and Zn K-edge X-ray absorption spectroscopy (XAS) were combined to investigate Zn2+ retention and isotope fractionation in four native moss taxa and in vitro-cultivated Sphagnum palustre clones. Zn2+ adsorption was strongly pH-dependent, consistent with progressive deprotonation of reactive surface sites. Moss-associated Zn2+ was slightly enriched in heavy isotopes relative to the coexisting solution, with {Delta}66Znmoss-solution generally ranging from +0.001 to +0.009 per cent, but no systematic relationship was observed between isotopic fractionation and the fraction of Zn2+ adsorbed. Linear-combination fitting of X-ray Absorption Near-Edge Structure (XANES) indicated predominantly cellulose-like, O-rich coordination environments, with variable phosphate and minor acetate contributions and only small nominal Zn-S fractions. Extended X-ray Absorption Fine Structure (EXAFS) showed first-shell Zn-O distances of approximately 1.96 - 2.05 Angstrom and coordination numbers of about 3.6 - 7.6, confirming substantial structural heterogeneity among samples. Importantly, {Delta}66Znmoss-solution was not correlated with either Zn-O distance or coordination number, indicating that the net isotope effect cannot be described by a single bulk structural parameter. Native and cultivated Sphagnum showed comparable isotopic offsets within analytical uncertainty despite differences in surface properties and adsorption capacity. These results indicate that Zn isotope fractionation in mosses reflects the integrated response of multiple binding environments and support the use of standardized Sphagnum clones in isotope-based biomonitoring.

plant biology↗

bioRxiv2025

Linking biosurface reactivity and photosynthesis to investigate Sphagnum mosses as peatland engineers

O_LISphagnum mosses regulate peatland carbon cycling, hydrology, nutrient dynamics, and structure. We investigated the link between Sphagnum surface chemistry and photosynthetic efficiency, and the combined effects of pH and waterlogging on photosynthesis, key mechanisms for peatland functioning but still poorly understood. C_LIO_LIWe quantified biosorption potential and functional groups in 20 field collected and in 4 axenically cloned Sphagnum species via titrations. Gas exchange and chlorophyll fluorescence measurements were performed in 5 representative species under submerged conditions across a pH gradient. C_LIO_LIThe 20 Sphagnum species share a basic surface chemistry, but they differ in surface charge and functional group abundance, with an overall greater biosorption potential in the subgenera Acutifolia and Sphagnum. Photosynthesis is species- and pH-dependent, influenced by surface functional-group composition, with phosphoryl and carboxyl groups enhancing CO2 assimilation. Sphagnum palustre emerges as a generalist, stress-tolerant species, maintaining stable photosynthesis and photoprotection across pH ranges. In-vitro cultivation reduces surface reactivity and interspecific differentiation but preserves fundamental Sphagnum surface chemistry. C_LIO_LIThese results highlight the interplay between chemical reactivity, photosynthetic performance, and ecological adaptation in Sphagnum. Sphagnum chemical traits and photosynthetic plasticity enable survival under variable pH, waterlogging, and nutrient conditions, with clones providing reliable models for research and applications. C_LI

plant biology↗

bioRxiv2022

Methylene blue, Mycophenolic acid, Posaconazole, and Niclosamide inhibit SARS-CoV-2Omicron variant BA.1 infection of human airway epithelial explant cultures

Sublineages of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) Omicron variants continue to amass mutations in the spike (S) glycoprotein, which leads to immune evasion and rapid spread of the virus across the human population. Here we demonstrate the susceptibility of the Omicron variant BA.1 (B.1.1.529.1) to four repurposable drugs, Methylene blue (MB), Mycophenolic acid (MPA), Posaconazole (POS), and Niclosamide (Niclo) in post-exposure treatments of primary human airway cell cultures. MB, MPA, POS, and Niclo are known to block infection of human nasal and bronchial airway epithelial explant cultures (HAEEC) with the Wuhan strain, and four variants of concern (VoC), Alpha (B.1.1.7), Beta (B.1.351), Gamma (B.1.1.28), Delta (B.1.617.2) (1, 2). Our results not only show broad anti-coronavirus effects of MB, MPA, POS and Niclo, but also demonstrate that the Omicron variant BA.1 (B.1.1.529.1) sheds infectious virus from HAEEC over at least 15 days, and maintains both intracellular and extracellular viral genomic RNA without overt toxicity, suggesting viral persistence. The data underscore the broad effects of MB, MPA, POS, and Niclo against SARS-CoV-2 and the currently circulating VoC, and reinforce the concept of repurposing drugs in clinical trials against COVID-19.

microbiology↗

bioRxiv2021

A tomato prolyl-4-hydroxylase causes relocation of abscission zone and alters abscission kinetics

The detachment of organs is controlled by highly regulated molecular mechanisms. The position of the tomato abscission zone (AZ) is defined by the ratio of the proximal to distal part of the pedicel. In this study, the ratio was altered due to a shift in the position of the AZ which was attributed to shorter and longer pedicels of SlP4H3 RNAi and OEX lines due to changes on cell division and expansion in AZ and distal part. This might be associated with LM2- and JIM8-AGPs which increased in OEX and decreased in RNAi lines throughout the pedicel. The JIM13 AGPs were downregulated in the flower AZ of OEX lines, pointing to a role on abscission regulation. In addition, Co-IP in flower AZ with SlP4H3-GFP fusion proteins showed interaction with LM2-, JIM13- and JIM8-epitopes suggesting proline hydroxylation by SlP4H3. The lower content of methyl-esterified HGs and higher of demethyl-esterified HGs in the AZs of RNAi lines might be responsible for increased rigidity of the AZ cell walls, accounting for the higher force required for AZ tissue detachment to occur. Moreover, ethylene-induced flower abscission was accelerated in the RNAi lines and delayed in OEX lines, while exactly the opposite response was observed in the red ripe fruit AZs. This was partly attributed to alterations in the expression of cell wall hydrolases. Overall, these results indicate that P4Hs might regulate molecular and structural features of cell walls in the AZ as well as abscission progression by regulating the structure and function of AGPs. Sentence SummaryAlterations on the expression of tomato prolyl 4 hydroxylase 3 shifts the position of the pedicel abscission zone and alters ethylene induced abscission progression according to the developmental context of the pedicel.

plant biology↗

bioRxiv2019

The Rab5-Rab11 endosomal pathway is required for BDNF-induced CREB transcriptional regulation in neurons.

Brain-derived neurotrophic factor (BDNF) is a key regulator of the morphology and connectivity of central neurons. We have previously shown that BDNF/TrkB signaling regulates the activity and mobility of the GTPases Rab5 and Rab11, which in turn determine the post-endocytic sorting of signaling TrkB receptors. Moreover, altered Rab5 or Rab11 activity inhibits BDNF-induced dendritic branching. Whether Rab5 or Rab11 activity is important for local events only, or also for regulating nuclear signaling and gene expression, is unknown. Here, we investigated whether BDNF-induced signaling cascades were altered when early and recycling endosomes were disrupted by the expression of dominant negative mutants of Rab5 and Rab11. The activities of both Rab5 and Rab11 were required for sustained activity of Erk1/2 and nuclear CREB phosphorylation and for increased transcription of BDNF-dependent genes containing CRE-binding sites that include activity-regulated genes such as Arc, Dusp1, c-fos and Egr1 and growth and survival genes such as Atf3 and Nf1. Based on our results, we propose that the early and recycling endosomes provide a platform for the integration of neurotrophic signaling from the plasma membrane to the nucleus in neurons and that this mechanism likely regulates neuronal plasticity and neuronal survival. Significance StatementBDNF is a soluble neurotrophic factor that regulates plastic changes in the brain, including dendritic growth, by binding to its plasma membrane receptor TrkB. BDNF/TrkB activates signaling cascades leading to activation of CREB, a key transcription factor regulating circuit development and learning and memory. Our results uncover the cellular mechanisms that central neurons use to integrate the signaling of plasma membrane receptors with nuclear transcriptional responses. We found that the endosomal pathway is required for the signaling cascade initiated by BDNF and its receptors in the plasma membranes to modulate BDNF-dependent gene expression and neuronal dendritic growth mediated by the CREB transcription factor in the nucleus.

cell biology↗