Biology subjects

Garcia-Gonzalez, J.

Publications and source records attributed to Garcia-Gonzalez, J..

11 recordsLinked to original sources

bioRxiv2026

In vivo imaging uncovers an abundant but rarely active pool of plant ARP2/3 complexes associated with exocyst complex subunit

The ARP2/3 complex generates branched actin networks that regulate membrane dynamics across eukaryotes. In plants, ARP2/3 is activated primarily by the WAVE/SCAR complex and is essential for cell morphogenesis, yet its spatiotemporal behavior in living cells remains poorly understood. Using high-resolution live-cell microscopy, we found that, in addition to their previously reported stable accumulation at three-way cell junctions and peroxisomes, WAVE/SCAR and ARP2/3 subunits also form abundant, highly dynamic, short-lived assemblies in the cortical cytoplasm, with lifetimes of only a few seconds. Genetic and colocalization analyses further revealed that only a minority of observed complexes are fully assembled and active, indicating that plant cells maintain a large pool of partially assembled or inactive ARP2/3 structures. Our data indicate that microtubules influence the abundance of cortical assemblies, whereas actin primarily affects their dynamics. Importantly, our analysis demonstrated a spatial and functional association between dynamic ARP2/3 foci and exocytotic events at the plasma membrane. Together, our findings suggest that the cytoplasm of plant epidermal cells contains a large reservoir of ARP2/3 complexes whose localized activation is tightly regulated and associated with membrane trafficking.

plant biology↗

bioRxiv2026

A plasmodesmata-specific exocyst complex regulates symplastic connectivity by affecting callose turnover

Plasmodesmata are intercellular channels that mediate symplastic communication between plant cells. Molecular transport through these channels is critically regulated by dynamic callose deposition and degradation, yet the secretory mechanisms that deliver regulatory components to plasmodesmata remain poorly understood. Here, we identify and characterize a non-canonical plasmodesmata-associated module of the exocyst, an evolutionarily conserved protein complex involved in secretory vesicle tethering and exocytosis. Exocyst subunits EXO70G1, SEC15A, EXO84C, and SEC10A specifically accumulate at plasmodesmata, whereas the canonical exocyst subunits EXO70A1 and SEC8 do not. Genetic and interaction analyses show that EXO70G1 acts as a landmark for recruiting SEC15A and EXO84C to plasmodesmata, revealing a distinct mode of exocyst targeting at these membrane domains. EXO70G1-dependent exocyst targeting to plasmodesmata depends on phosphoinositides and sphingolipids, consistent with the specialized lipid environment of plasmodesmal membranes. Loss of EXO70G1 results in increased callose accumulation and reduced symplastic transport, and strongly enhances developmental defects of a callose-overproducing mutant. In addition, exo70G1 mutants display enhanced resistance to bacterial pathogen Pseudomonas syringae, linking reduced plasmodesmal permeability to anti-bacterial defense. Cross-species analysis further indicates that plasmodesmata association is a derived feature of the EXO70G clade, present in angiosperms but absent from non-angiosperm EXO70 homologs. Together, our findings show that exocyst diversification in plants has generated a specialized trafficking module - plasmodesmata-associated exocyst - that links vesicle delivery to callose homeostasis at plasmodesmata, thereby regulating intercellular communication, development, and immunity. TeaserA specialized secretion module of the exocyst complex regulates plant cell-to-cell connectivity by controlling callose turnover at plasmodesmata

plant biology↗

bioRxiv2026

The molecular architecture of the Arabidopsis callose synthase complex

ABSTRACTCallose synthase is responsible for the targeted deposition of the {beta}-1,3-glucan polymer, callose which underlines essential plant developmental processes, including cell division, pathogen defense or cell-cell communication. The architecture of the callose synthase complex (CALSC) as well as the molecular mechanisms of callose synthesis remain unknown. Here we report an integrative characterisation of the Arabidopsis CALS complex, with the most enriched subunits, CALS1, CALS2 and CALS3, forming its core. Structurally, CALSC assembles into a trimer, requiring the plant-specific Bag domain to mediate inter-subunit associations. The biological importance of CALSC assembly is highlighted by the simultaneous loss of CALS1 and CALS3, which abolishes plasmodesmal callose deposition and affects symplastic transport. Site-directed mutagenesis and molecular dynamics simulations depict the topology of the CALS1 active site in detail, including the components of the enzymatic reaction. We pinpoint the translocating tunnel through which the nascent glucan is delivered and mechanistically confirm the role of transmembrane helix 8 in regulating glucan export. Our work provides unprecedented insight into the molecular architecture of the CALSC and the distinct changes from maturation to activity at the plasma membrane, while showcasing the mechanisms involved in callose synthesis at the molecular level.

plant biology↗

bioRxiv2025

Independent roles of Arp2/3 complex and RIC4 protein in the control of epidermal cell shape

The aim of this study was to determine whether RIC4, a CRIB domain-containing protein that functions as an effector of ROP GTPases, and the Arp2/3 complex, an actin nucleator, functionally cooperate in controlling the shape of Arabidopsis cotyledon epidermal cells. The combination of KO mutants demonstrated that loss of RIC4 and loss of the Arp2/3 complex result in completely opposite epidermal cell shape phenotypes. The double KO mutation is phenotypically similar to the Arp2/3 mutation, and the effect of RIC4 loss is completely eliminated. Analysis of overexpression revealed that excess RIC4 significantly suppresses the formation of pavement cell lobes. However, RIC4 does not require an active Arp2/3 complex for this effect. Our data further show that overexpression of RIC4 has a specific actin stabilization effect in cotyledon epidermal cells. However, we could not demonstrate that actin stabilization is directly related to the cell shape changes that RIC4 overexpression induces. In conclusion, RIC4 and the Arp2/3 complex do not share the same signaling pathway in their function in the control of cotyledon epidermal cell shape.

plant biology↗

bioRxiv2025

Analysing the Role of KIN10 in Directional Root Growth Regulation in Arabidopsis thaliana

Root growth directionality is critical for plant survival, optimizing anchorage and resource acquisition. While the role of hormonal signaling in root gravitropism is well established, the contribution of metabolic status remains less understood. Here, we investigate the function of the catalytic SnRK1 subunit KIN10 in integrating carbon availability with root growth regulation in Arabidopsis thaliana. A combination of growth phenotyping, transcriptomics, and hormonomic profiling suggest that KIN10 loss disrupts energy-linked developmental processes. Compared to wild-type Col-0, kin10 displayed reduced sensitivity to glucose-induced root growth inhibition. Transcriptomic analysis of kin10 roots revealed widespread reprogramming of metabolic and hormonal pathways, with significant changes in secondary metabolism, cell wall remodeling, and hormone-related gene expression. Hormone profiling further indicated that KIN10 modulates auxin and jasmonate pathways in a carbon source- and organ-dependent manner, especially under sucrose supplementation. Our results demonstrate that KIN10 plays a central role in integrating energy status with developmental and environmental signaling.

plant biology↗

bioRxiv2023

Pleiotropic contribution of rbfox1 to psychiatric and neurodevelopmental phenotypes in a zebrafish model

RBFOX1 is a highly pleiotropic gene that contributes to several psychiatric and neurodevelopmental disorders. Both rare and common variants in RBFOX1 have been associated with several psychiatric conditions, but the mechanisms underlying the pleiotropic effects of RBFOX1 are not yet understood. Here we found that, in zebrafish, rbfox1 is expressed in spinal cord, mid- and hindbrain during developmental stages. In adults, expression is restricted to specific areas of the brain, including telencephalic and diencephalic regions with an important role in receiving and processing sensory information and in directing behaviour. To investigate the effect of rbfox1 deficiency on behaviour, we used rbfox1sa15940, a rbfox1 loss-of-function line. We found that rbfox1sa15940 mutants present hyperactivity, thigmotaxis, decreased freezing behaviour and altered social behaviour. We repeated these behavioural tests in a second rbfox1 loss-of-function line with a different genetic background, rbfox1del19, and found that rbfox1 deficiency affects behaviour similarly in this line, although there were some differences. rbfox1del19 mutants present similar thigmotaxis, but stronger alterations in social behaviour and lower levels of hyperactivity than rbfox1sa15940 fish. Taken together, these results suggest that rbfox1 deficiency leads to multiple behavioural changes in zebrafish that might be modulated by environmental, epigenetic and genetic background effects, and that resemble phenotypic alterations present in Rbfox1-deficient mice and in patients with different psychiatric conditions. Our study thus highlights the evolutionary conservation of rbfox1 function in behaviour and paves the way to further investigate the mechanisms underlying rbfox1 pleiotropy on the onset of neurodevelopmental and psychiatric disorders.

genetics↗

bioRxiv2023

BridgePRS: A powerful trans-ancestry Polygenic Risk Score method

Polygenic Risk Scores (PRS) have huge potential to contribute to biomedical research and to a future of precision medicine, but to date their calculation relies largely on Europeanancestry GWAS data. This global bias makes most PRS substantially less accurate in individuals of non-European ancestry. Here we present BridgePRS, a novel Bayesian PRS method that leverages shared genetic effects across ancestries to increase the accuracy of PRS in non-European populations. The performance of BridgePRS is evaluated in simulated data and real UK Biobank (UKB) data across 19 traits in African, South Asian and East Asian ancestry individuals, using both UKB and Biobank Japan GWAS summary statistics. BridgePRS is compared to the leading alternative, PRS-CSx, and two single-ancestry PRS methods adapted for trans-ancestry prediction. PRS trained in the UK Biobank are then validated out-of-cohort in the independent Mount Sinai (New York) BioMe Biobank. Simulations reveal that BridgePRS performance, relative to PRS-CSx, increases as uncertainty increases: with lower heritability, higher polygenicity, greater between-population genetic diversity, and when causal variants are not present in the data. Our simulation results are consistent with real data analyses in which BridgePRS has better predictive accuracy in African ancestry samples, especially in out-of-cohort prediction (into BioMe), which shows a 60% boost in mean R2 compared to PRS-CSx (P = 2 x 10-6). BridgePRS performs the full PRS analysis pipeline, is computationally efficient, and is a powerful method for deriving PRS in diverse and under-represented ancestry populations.

genetics↗

bioRxiv2022

RaPiD-chamber: Easy to self-assemble live-imaging chamber with adjustable LEDs allows to track small differences in dynamic plant movement adaptation on tissue level

Plants rely on fine-tuning organ movement to ensure their survival and productivity. Even subtle loss of directional growth orchestration can result in a huge impact when the plant is impaired to adapt to an ever-changing environment, where it is exposed to manifold exogenous stimuli simultaneously. We present a newly designed chamber to obtain live images to track organ growth and movement differences, called RaspberyPi Dark Chambers (RaPiD-chamber). The RaPiD-chamber is easy to self-assemble and cost-efficient and allows to monitor the continuous growth of etiolated seedlings, as well as their response to light of different wavelengths and from chosen positions. We tested the advice by comparing hypocotyl elongation rate and response to unilateral white and blue light exposure of Arabidopsis thaliana Col0. Additionally, we compared the elongation rate of etiolated hypocotyls between Col0 and kin10, a mutant lacking the catalytic subunit of the cellular signaling hub SUCROSE NON-FERMENTING RELATED KINASE 1 (SnRK1). kin10 is known for its diminished ability to control hypocotyl elongation. As a case study, we compared the growth dynamics of etiolated Col0 versus kin10. Without further energy source supplementation to the growth medium, the mutant cannot keep up with hypocotyl elongation. Additionally, continuous observation of the dark-grown seedlings allowed us to determine a shift in the dynamics of apical hook angle formation for the mutant.

plant biology↗

bioRxiv2022

Behavioural analysis of loss of function zebrafish supports baz1b as master regulator of domestication

Domestication is associated with both morphological and behavioural phenotypic changes that differentiate domesticated species from their wild counterparts. Some of the traits are those purposely targeted by the selection process, whilst others co-occur as a result of selection. The combination of traits is referred to as the domestication syndrome and their shared characteristics has given rise to the neural crest domestication syndrome (NCDS) hypothesis. According to this hypothesis, the phenotypic changes are a consequence of a selection towards animals with mild underdevelopment of the neural crest. A similar mechanism is suggested to affect some species of "self-domesticated" animals, including humans. Recent research supports a role for BAZ1B, one of the haplo-insufficient genes in Williams syndrome (WS), in the evolution of craniofacial features of modern humans. Interestingly, WS recapitulates some of the traits observed in the domestication syndrome, including hypersociability and reduced facial bones. However, the evidence linking BAZ1B to behavioural phenotypes associated with domestication is presumptive. Here, we use zebrafish as a model to test the hypothesis that baz1b loss-of-function leads to both morphological and behavioural phenotypes associated with the domestication syndrome by influencing the development of the neural crest. Our research provides further evidence supporting the NCDS hypothesis and bazlbs role in this process.

animal behavior and cognition↗

bioRxiv2020

Behavioral effects of developmental exposure to JWH-018 in wild type and disrupted in schizophrenia 1 (disc1) mutant zebrafish

Synthetic cannabinoids can cause acute adverse psychological effects, but the potential impact when exposure happens before birth is unknown. Use of synthetic cannabinoids during pregnancy may affect fetal brain development, and such effects could be moderated by the genetic makeup of an individual. Disrupted in schizophrenia 1 (DISC1) is a gene with important roles in neurodevelopment which has been associated with psychiatric disorders in pedigree analyses. Using zebrafish as a model, we investigated (1) the behavioral impact of developmental exposure to JWH-018 (a common psychoactive synthetic cannabinoid) and (2) whether disc1 moderates the effects of JWH-018. As altered anxiety responses are seen in a several psychiatric disorders, we focused on zebrafish anxiety-like behavior. Zebrafish embryos were exposed to JWH-018 from one to six days post-fertilization. Anxiety-like behavior was assessed using forced light/dark and acoustic startle assays in larvae, and novel tank diving in adults. Compared to controls, developmentally exposed zebrafish larvae had impaired locomotion during the forced light/dark test, but anxiety levels and response to startle stimuli was unaltered. Adult zebrafish developmentally exposed to JWH-018 spent less time on the bottom of the tank, suggesting decreased anxiety. Loss-of-function in disc1 increased anxiety but did not alter sensitivity to JWH-018. Results suggest developmental exposure to JWH-018 has behavioral impact in zebrafish, which is not moderated by disc1.

molecular biology↗

bioRxiv2018

Population based forward genetic screen of mutagenized zebrafish identifies loci associated with nicotine preference and human smoking behavior

To facilitate smoking genetics research we determined whether a screen of mutagenized zebrafish for nicotine preference could predict loci affecting smoking behaviour. Of 30 ENU mutagenized families screened, two showed increased or decreased nicotine preference. Out of 25 inactivating mutations in the families, one in the slit3 gene segregated with increased nicotine preference in heterozygous individuals. Focussed SNP analysis of the human SLIT3 locus in cohorts from UK (n=863) and Finland (n=1715) identified two variants that predict cigarette consumption and likelihood of cessation. Characterisation of slit3 mutant larvae and adult fish revealed decreased sensitivity to the dopaminergic and serotonergic antagonist amisulpride, known to affect startle reflex that is correlated with addiction in humans, and increased htr1aa mRNA expression in mutant larvae. No effect on neuronal pathfinding was detected. These findings reveal a role for SLIT3 in development of pathways affecting responses to nicotine in zebrafish and smoking in humans.

genetics↗