Biology subjects

Diaz, A.

Publications and source records attributed to Diaz, A..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

Genome-wide screen overexpressing mycobacteriophage Amelie genes identifies multiple inhibitors of mycobacterial growth

The genome sequences of thousands of bacteriophages have been determined and functions for many of the encoded genes have been assigned based on homology to characterized sequences. However, functions have not been assigned to more than two-thirds of the identified phage genes as they have no recognizable sequence features. Recent genome-wide overexpression screens have begun to identify bacteriophage genes that encode proteins that reduce or inhibit bacterial growth. This study describes the construction of a plasmid-based overexpression library of 76 genes encoded by Cluster K1 mycobacteriophage Amelie, which is genetically similar to Cluster K phages Waterfoul and Hammy recently described in similar screens and closely related to phages that infect clinically important mycobacteria. 26 out of the 76 genes evaluated in our screen, encompassing 34% of the genome, reduced growth of the host bacterium Mycobacterium smegmatis to various degrees. More than one-third of these 26 toxic genes have no known function, and 10 of the 26 genes almost completely abolished host growth upon overexpression. Notably, while several of the toxic genes identified in Amelie shared homologs with other Cluster K phages recently screened, this study uncovered eight previously unknown gene families that exhibit cytotoxic properties, thereby broadening the repertoire of known phage-encoded growth inhibitors. This work, carried out under the HHMI-supported SEA-GENES project (Science Education Alliance Gene-function Exploration by a Network of Emerging Scientists), underscores the importance of comprehensive overexpression screens in elucidating genome-wide patterns of phage gene function and novel interactions between phages and their hosts.

microbiology↗

bioRxiv2024

Gradations in protein dynamics captured by experimental NMR are not well represented by AlphaFold2 models and other computational metrics

The advent of accurate methods to predict the fold of proteins initiated by AlphaFold2 is rapidly changing our understanding of proteins and helping their design. However, these methods are mainly trained on protein structures determined with X-ray diffraction, where the protein is packed in crystals at often cryogenic temperatures. They can therefore only reliably cover well-folded parts of proteins that experience few, if any, conformational changes. Experimentally, solution nuclear magnetic resonance (NMR) is the experimental method of choice to gain insight into protein dynamics at near physiological conditions. Computationally, methods such as molecular dynamics and Normal Mode Analysis (NMA) allow the estimation of a proteins intrinsic flexibility based on a single protein structure. This work addresses, on a large scale, the relationships for proteins between the AlphaFold2 pLDDT metric, the observed dynamics in solution from NMR metrics, interpreted MD simulations, and the computed dynamics with NMA from single AlphaFold2 models and NMR ensembles. We observe that these metrics agree well for rigid residues that adopt a single well-defined conformation, which are clearly distinct from residues that exhibit dynamic behavior and adopt multiple conformations. This direct order/disorder categorisation is reflected in the correlations observed between the parameters, but becomes very limited when considering only the likely dynamic residues. The gradations of dynamics observed by NMR in flexible protein regions are therefore not represented by these computational approaches. Our results are interactively available for each protein from https://bio2byte.be/af_nmr_nma/.

bioinformatics↗

bioRxiv2023

3D-Imaging of synapses in neuronal tissues with synchrotron X-ray ptychography

Maps of dense subcellular features in biological tissue are the key to understanding the structural basis of organ function. Electron microscopy provides the necessary resolution, yet - as electrons penetrate samples for only a few 100s of nm - requires physical sectioning or ablation, which strongly challenges anatomical investigations of entire organs such as mammalian brains. As demonstrated for the engineering and physical sciences, X-ray nanotomography represents a promising alternative for ultrastructural 3d imaging without physical sectioning1-15. Leveraging the high brilliance of 4th generation synchrotron X-ray sources, it has the potential to non-destructively image mm3-sized samples at ultrastructural resolution within a few days16. A fundamental barrier to application to the life sciences is that, when irradiated with high-intensity X-rays, biological samples deform and ultimately disintegrate, prohibiting reaching sufficient resolution. Here, we introduce a combination of engineering solutions which defeat this barrier for X-ray ptychography17, a coherent diffractive X-ray imaging technique. The solutions include a cryogenic sample stage with high stability, high-precision interferometric positioners and tailored non-rigid tomographic reconstruction algorithms18. Furthermore, adapting an epoxy resin developed for the nuclear and aerospace industry, we demonstrate radiation resistance to X-ray doses exceeding 1010 Gy. The resulting sub-40 nm isotropic resolution makes it possible to densely resolve axon bundles, boutons, dendrites and reliably identify synapses without physical sectioning. Moreover, we validated the X-ray technique using the current gold standard, namely focused ion beam scanning electron microscopy (FIB-SEM)19,20 to demonstrate intact ultrastructure in tissue volumes first imaged by X-rays. This unlocks the potential of X-ray tomography for high-resolution tissue imaging, coinciding with the transformative advancements of next-generation synchrotrons worldwide21.

neuroscience↗

bioRxiv2023

Combining evolution and protein language modelsfor an interpretable cancer driver mutationprediction with D2Deep

The mutations driving cancer are being increasingly exposed through tumor-specific genomic data. However, differentiating between cancer-causing driver mutations and random passenger mutations remains challenging. State-of-the-art homology-based predictors contain built-in biases and are often ill-suited to the intricacies of cancer biology. Protein Language Models have successfully addressed various biological problems but have not yet been tested on the challenging task of cancer driver mutation prediction at large scale. Additionally, they often fail to offer result interpretation, hindering their effective use in clinical settings. The AI-based D2Deep method we introduce here addresses these challenges by combining two powerful elements: i) a non-specialized protein language model that captures the makeup of all protein sequences and ii) protein-specific evolutionary information that encompasses functional requirements for a particular protein. D2Deep relies exclusively on sequence information, outperforms state-of-the-art predictors and captures intricate epistatic changes throughout the protein caused by mutations. These epistatic changes correlate with known mutations in the clinical setting and can be used for the interpretation of results. The model is trained on a balanced, somatic training set and so effectively mitigates biases related to hotspot mutations compared to state-of-the-art techniques. The versatility of D2Deep is illustrated by its performance on non-cancer mutation prediction, where most variants still lack known consequences. D2Deep predictions and confidence scores are available via https://tumorscope.be/d2deep to help with clinical interpretation and mutation prioritization.

bioinformatics↗

bioRxiv2023

Tumor-wide RNA splicing aberrations generate immunogenic public neoantigens

T-cell-mediated immunotherapies are limited by the extent to which cancer-specific antigens are homogenously expressed throughout a tumor. We reasoned that recurrent splicing aberrations in cancer represent a potential source of tumor-wide and public neoantigens, and to test this possibility, we developed a novel pipeline for identifying neojunctions expressed uniformly within a tumor across diverse cancer types. Our analyses revealed multiple neojunctions that recur across patients and either exhibited intratumor heterogeneity or, in some cases, were tumor-wide. We identified CD8+ T-cell clones specific for neoantigens derived from tumor-wide and conserved neojunctions in GNAS and RPL22, respectively. TCR-engineered CD8+ T-cells targeting these mutations conferred neoantigen-specific tumor cell eradication. Furthermore, we revealed that cancer-specific dysregulation in splicing factor expression leads to recurrent neojunction expression. Together, these data reveal that a subset of neojunctions are both intratumorally conserved and public, providing the molecular basis for novel T-cell-based immunotherapies that address intratumoral heterogeneity.

cancer biology↗

bioRxiv2023

Risk of urban Mayaro virus (Alphavirus: Togaviridae) transmission: is Aedes aegypti a competent vector?

Mayaro virus (MAYV) is an emerging pathogen endemic in Latin America and is the causative agent of fever and polyarthritis. Urban transmission depends on its ability to be transmitted by Aedes aegypti and to be amplified by humans. The aim of this study was to evaluate the susceptibility to infection and transmission and the presence of barriers to infection in different populations of Ae. aegypti for MAYV. Ae. aegypti eggs were collected from Cordoba, Buenos Aires and Rosario Cities (Argentina). Females were infected with five viral loads of MAYV strain (1 to 6 log10 PFU/ml) and maintained for 8 days. The presence of infectious viral particles in body, legs, and saliva was detected by plaquing assay in Vero cell monolayers. Through a bibliographic search, Ae. aegypti population data from Peru were incorporated and tested with different viral doses of MAYV. We build dose-response curves for Ae. aegypti populations to estimate infection (IR), dissemination (DR) and transmission (TR) based on MAYV viral loads detected in humans to estimate transmission risk occurring in an urban environment. The overall IR and DR were significantly associated with the viral doses and were not significantly affected by population origin. We found IR ranging for 3 to 84% (ID50% were higher than 5.5 log10 PFU/ml) and a DR reached 78% (DD50% higher than 6.0 log10 PFU/ml). The percentage of dissemination based on the infected mosquitoes ranged from 60 to 86% while the percentage of transmission based on disseminated mosquitoes ranged from 11 to 60%. Our results indicate that Ae. aegypti populations are not competent vectors for MAYV because they need higher viral doses than those developed by humans (3.9 - 4.5 log10 PFU/ml) to become infected. Only a very low proportion of infected mosquitoes with high 5 log10 PFU/ml are capable of transmitting it.

microbiology↗

bioRxiv2023

Distinct human stem cell subpopulations drive adipogenesis and fibrosis in musculoskeletal injury

Fibroadipogenic progenitors (FAPs) maintain healthy skeletal muscle in homeostasis but drive muscle degeneration in chronic injuries by promoting adipogenesis and fibrosis. To uncover how these stem cells switch from a pro-regenerative to pro-degenerative role we perform single-cell mRNA sequencing of human FAPs from healthy and injured human muscles across a spectrum of injury, focusing on rotator cuff tears. We identify multiple subpopulations with progenitor, adipogenic, or fibrogenic gene signatures. We utilize full spectrum flow cytometry to identify distinct FAP subpopulations based on highly multiplexed protein expression. Injury severity increases adipogenic commitment of FAP subpopulations and is driven by the downregulation of DLK1. Treatment of FAPs both in vitro and in vivo with DLK1 reduces adipogenesis and fatty infiltration, suggesting that during injury, reduced DLK1 within a subpopulation of FAPs may drive degeneration. This work highlights how stem cells perform varied functions depending on tissue context, by dynamically regulating subpopulation fate commitment, which can be targeted improve patient outcomes after injury.

cell biology↗

bioRxiv2023

Effects of blood meal source and seasonality on reproductive traits of Culex quinquefasciatus (Diptera: Culicidae)

Host selection by mosquitoes is a keystone to understanding viral circulation and predicting future infection outbreaks. Culex mosquitoes frequently feed on birds during spring and early summer, shifting into mammals towards late summer and autumn. This host switch may be due to changes in mosquito fitness. The aim of this study was to assess if the interaction effect of blood meal source and seasonality may influence reproductive traits of Culex quinquefasciatus mosquitoes. For this purpose, Cx. quinquefasciatus mosquitoes were reared in simulated summer and autumn conditions and fed on two different hosts, chickens and mice, in a factorial design. Fecundity, fertility, and hatchability during two consecutive gonotrophic cycles were estimated. We found greater fecundity and fertility for mosquitoes fed upon birds than mammals. Fecundity and fertility did not vary between seasons for chicken-fed mosquitoes, whereas in autumn they decreased for mouse-fed mosquitoes. These traits decreased in the second gonotrophic cycle for mouse-fed mosquitoes, whereas they did not vary between cycles for chicken-fed mosquitoes. There was no statistically significant effect of blood meal source, seasonality or their interaction on hatchability, hence this variable was similar among treatments. Overall, these results indicate a statistically significant interaction effect of blood meal source and seasonality on fecundity and fertility. However, the pattern was opposite in relation to our hypothesis, suggesting that further studies are needed to confirm and expand our knowledge about mosquito biology and its relationship with seasonal host use shifting.

ecology↗

bioRxiv2023

Transcription factor Nrf1 regulates proteotoxic stress-induced autophagy

Cells exposed to proteotoxic stress invoke adaptive responses aimed at restoring proteostasis. Our previous studies have established a firm role for the transcription factor Nuclear factor erythroid derived 2-related factor 1 (Nrf1, also called NFE2L1) in responding to proteotoxic stress elicited by inhibition of cellular proteasome. Following proteasome inhibition, Nrf1 mediates new proteasome synthesis, thus enabling the cells to mitigate the proteotoxic stress. Here we report that under similar circumstances, multiple components of the autophagy lysosomal pathway (ALP) are transcriptionally upregulated in an Nrf1-dependent fashion, thus providing the cells with an additional route to cope with proteasome insufficiency. In response to proteasome inhibitors, Nrf1-deficient cells displayed profound defects in invoking autophagy and clearance of aggresomes. This phenomenon was also recapitulated in NGLY1 knockout cells (a model for NGLY1 disease) where Nrf1 is known to be non-functional. Overall, our results significantly expand the role of Nrf1 in shaping the cellular response to proteotoxic stress.

cell biology↗

bioRxiv2023

Jamestown Canyon Virus is transmissible by Aedes aegypti and is only moderately blocked by Wolbachia co-infection

Jamestown Canyon Virus (JCV), a negative-sense arbovirus, is increasingly common in the upper Midwest of the USA. Transmitted by a range of mosquito genera, JCV has at its primary amplifying host, white-tailed deer. Aedes aegypti is the major transmitter globally of the positive-sense viruses dengue (DENV), Zika, chikungunya, and Yellow Fever. Ae. aegyptis distribution, once confined to the tropics, is expanding, in part due to climate change. Wolbachia, an insect endosymbiont, limits the replication of co-infecting viruses inside insects. The release and spread of the symbiont into Ae. aegypti populations has been effective in reducing transmission of dengue and other viruses to humans. The mechanism of Wolbachia-mediated viral blocking in vectors is still poorly understood, however. Here we explored JCV infection potential in Ae. aegypti, the nature of the vectors immune response, and interactions with Wolbachia infection. We show that Ae. aegypti is highly competent for JCV, growing to substantial loads and rapidly reaching the saliva after an infectious blood meal. The mosquito immune system responds with strong induction of RNAi and JAK/STAT. Neither the direct effect of viral infection nor the energetic investment in immunity appears to affect mosquito longevity. Wolbachia infection blocked JCV only in the early stages of infection. Wolbachia-induced immunity was small compared to that of JCV, suggesting innate immune priming does not likely explain blocking. We propose two models to explain why Wolbachias blocking of negative-sense viruses like JCV may be less than that of positive-sense viruses, relating to the slowdown of host protein synthesis and the triggering of interferon-like factors like Vago. In conclusion, we highlight the risk for increased human disease with the predicted future overlap of Ae. aegypti and JCV ranges. We suggest that with moderate Wolbachia-mediated blocking and distinct biology, negative-sense viruses represent a fruitful comparator model to other viruses for understanding blocking mechanisms in mosquitoes. Author SummaryJamestown Canyon Virus (JCV), a newly emerging virus in North America, causes disease when it spills out of its wild mammal hosts into human populations via the bite of infected mosquitoes. We show that the mosquito Aedes aegypti, known for transmitting many viral pathogens to humans globally, and whose distribution is creeping northward in the USA toward regions where JCV is present, is likely able to transmit the virus. Wolbachia is an endosymbiotic bacterium being released in wild mosquito populations of mosquitoes because it limits the replication of human viruses inside the mosquito, limiting their transmission to humans. We show that Wolbachia has a limited ability to control the replication of JCV, which is likely because Wolbachia-induced antiviral response is quite weak, and unique aspects of negative-sense virus biology make them less susceptible to blocking. Our findings suggest that JCV may serve as a comparative model to positive-sense viruses like dengue in dissecting the mechanism of Wolbachia-mediated virus blocking. It also warns that shifting mosquito distributions, as expected under a changing climate, could bring JCV and Aedes mosquitoes into greater contact, potentially increasing the incidence of JCV in humans.

pathology↗

bioRxiv2023

Glioblastoma induces the recruitment and differentiation of hybrid neutrophils from skull bone marrow

Tumor-associated neutrophil (TAN) effects on glioblastoma biology remain under-characterized. We show here that hybrid neutrophils with dendritic features - including morphological complexity, expression of antigen presentation genes, and the ability to process exogenous peptide and stimulate MHCII-dependent T cell activation - accumulate intratumorally and suppress tumor growth in vivo. Trajectory analysis of patient TAN scRNA-seq identifies this phenotype as a polarization state which is distinct from canonical cytotoxic TANs and differentiates intratumorally from immature precursors absent in circulation. Rather, these hybrid-inducible immature neutrophils - which we identified in patient and murine glioblastomas - arise from local skull marrow. Through labeled skull flap transplantation and targeted ablation, we characterize calvarial marrow as a potent contributor of antitumoral myeloid APCs, including hybrid TANs and dendritic cells, which elicit T cell cytotoxicity and memory. As such, agents augmenting neutrophil egress from skull marrow - such as intracalvarial AMD3100 whose survival prolonging-effect in GBM we demonstrate - present therapeutic potential.

cancer biology↗

bioRxiv2023

Ecological and life-history traits and their relationship with West Nile virus and Saint Louis Encephalitis virus exposure risk.

Host life-history traits can influence host-vector encounter rates, and so differentially determine the exposure risk of bird species. This modulation of host-virus encounters dynamics is especially important when facing "generalist" arboviruses like West Nile virus (WNV) and Saint Louis Encephalitis virus (SLEV). Using prevalence data collected by our laboratory since 2004, we tested several hypothesis that included birds ecological and life-history traits to determine which traits were better predictors of birds exposure risk to these arboviruses. By means of information-theoretic procedures and generalized mixed linear models, we observed that body mass was an important trait when predicting birds exposure risk to WNV and SLEV and migratory status significantly influenced birds exposure risk only to WNV. Our study highlights important traits to consider when studying the transmission system of these arboviruses, being useful to focus resources when characterizing viral transmission networks and discuss the repercussions of these traits over birds immune function throughout the pace of life syndrome and trade-offs theory.

ecology↗

bioRxiv2022

The lectin receptor Clec4F participates in the capture of circulating parasite mucins by Kupffer cells in cystic echinococcosis.

Cystic echinococcosis is caused by the larval stages (hydatids) of cestode parasites belonging to the species cluster Echinococcus granulosus sensu lato, with E. granulosus sensu stricto being the main infecting species. Hydatids are bladder-like structures that attain large sizes within various internal organs of livestock ungulates and humans. Hydatids are protected by the massive acellular laminated layer (LL), composed mainly by mucins. Parasite growth requires LL turnover, and abundant LL-derived particles are found at infection sites in infected humans, raising the question of how LL materials are dealt with by the hosts. In this article, we show that E. granulosus sensu stricto LL mucins injected into mice are taken up by Kupffer cells, the liver macrophages exposed to the vascular space. This uptake is largely dependent on the intact mucin glycans and on Clec4F, a C-type lectin receptor which in rodents is selectively expressed in Kupffer cells. This uptake mechanism operates on mucins injected both in soluble form i.v. and in particulate form i.p. In mice harbouring intraperitoneal infections by the same species, LL mucins were found essentially only at the infection site and in the liver, where they were taken up by Kupffer cells via Clec4F. Therefore, shed LL materials circulate in the host and Kupffer cells can act as a sink for these materials even when the parasite grows in sites other than the liver.

immunology↗

bioRxiv2022

Neotropical birds and mammals show divergent behaviour responses to human pressure

Human presence and habitat disturbance (together human pressure hereafter) can generate a deep fear in animals and this can influence their behaviour. Altered animal behaviour, such as shifts in diel activity patterns, affect many species and species interactions, which can induce changes in individual fitness, species-level population persistence, evolutionary dynamics, and ecosystem-level biodiversity. However, whether dial activity behavioural responses to human pressure are consistent among key functional groups has been poorly studied. For example, while medium to large mammal species tend to become more nocturnal in areas with high human pressure, its unclear if sympatric/co-occurring birds display similar or opposite patterns. This is an important knowledge gap because synchronous or opposing guild-level shifts can shape consequences for food-web dynamics (predation and competition), stability of interaction networks and ecosystem functioning. Here we used information from camera trapping along a gradient of human pressure in the Colombian Llanos region to assess diel activity changes in birds and mammals. We found that the diel activity of over 45% of the bird and 50% of the mammals assessed significantly changed where there was higher human pressures, with mammals becoming more nocturnal and birds more diurnal. The opposing behavioural responses to humans among vertebrate functional groups has significant repercussions for the fields of community ecology, including intraguild predation and competition, and may be a significant ecosystem-level conservation consideration.

ecology↗

bioRxiv2022

Evolution of CRISPR-associated Endonucleases as Inferred from Resurrected Proteins

Clustered regularly interspaced short palindromic repeats (CRISPR)-associated Cas9 protein is an effector that plays a major role in a prokaryotic adaptive immune system, by which invading DNA can be targeted and cut for inactivation. The Cas9 endonuclease is directed to target sites by a guide RNA (gRNA) where Cas9 can recognize specific sequences (PAMs) in foreign DNA, which then serve as an anchoring point for cleavage of the adjacent RNA-matching DNA region. Although the CRISPR-Cas9 system has been widely studied and repurposed for diverse applications (notably, genome editing), its origin and evolution remain to be elucidated. Here, we investigate the evolution of Cas9 from resurrected ancient nucleases (anCas) in extinct firmicutes species as old as 2600 myr to the current day. Surprisingly, we demonstrate that these ancient forms were much more flexible in their PAM and gRNA scaffold requirements compared to modern day Cas9 enzymes. In addition, anCas portrays a gradual paleoenzymatic adaptation from nickase to double-strand break activity, suggesting a mechanism by which ancient CRISPR systems could propagate when harboring Cas enzymes with minimal PAMs. The oldest anCas also exhibit high levels of activity with ssDNA and ssRNA targets, resembling Cas nucleases in related system types. Finally, we illustrate editing activity of the anCas enzymes in human cells. The prediction and characterization of anCas proteins uncovers an unexpected evolutionary trajectory leading to ancient enzymes with extraordinary properties.

evolutionary biology↗

bioRxiv2021

Identification of Cancer-Associated Fibroblasts in Glioblastoma and Defining Their Pro-tumoral Effects

Despite their identification in some cancers, pro-tumoral cancer-associated fibroblasts (CAFs) were presumed absent in glioblastoma given the lack of brain fibroblasts. Serial trypsinization of primary glioblastoma cultures yielded cells with CAF morphology, CAF transcriptomic profile, and mesenchymal lineage in single-cell RNA-seq. Glioblastoma CAFs were attracted to glioblastoma stem cells (GSCs) and CAFs enriched GSCs. We created a resource of inferred crosstalk by mapping expression of receptors to their cognate ligands, identifying PDGF-{beta} and TGF-{beta} as mediators of GSC effects on CAFs, and osteopontin and hepatocyte growth factor as mediators of CAF-induced GSC enrichment. Glioblastoma CAFs also induced M2 macrophage polarization by producing the EDA fibronectin variant. Glioblastoma CAFs were enriched in the subventricular zone which houses neural stem cells that produce GSCs. Including CAFs in GSC-derived xenografts induced in vivo growth. These findings are among the first to identify glioblastoma CAFs and their GSC interactions, making them an intriguing target.

cancer biology↗

bioRxiv2021

A Pan-Cancer Census of Dominant Tumor Immune Archetypes

Cancers display significant heterogeneity with respect to tissue of origin, driver mutations and other features of the surrounding tissue. It is likely that persistent tumors differentially engage inherent patterns-here Archetypes-of the immune system, to both benefit from a tumor immune microenvironment (TIME) and to disengage tumor-targeting. To discover dominant immune system archetypes, the Immunoprofiler Initiative (IPI) processed 364 individual tumors across 12 cancer types using standardized protocols. Computational clustering of flow cytometry and transcriptomic data obtained from cell sub compartments uncovered archetypes that exist across indications. These Immune composition-based archetypes differentiate tumors based upon unique immune and tumor gene-expression patterns. Archetypes discovered this way also tie closely to well-established classifications of tumor biology. The IPI resource provides a template for understanding cancer immunity as a collection of dominant patterns of immune infiltration and provides a rational path forward to learn how to modulate these patterns to improve therapy. O_FIG O_LINKSMALLFIG WIDTH=182 HEIGHT=200 SRC="FIGDIR/small/441344v1_ufig1.gif" ALT="Figure 1"> View larger version (77K): org.highwire.dtl.DTLVardef@55a5ccorg.highwire.dtl.DTLVardef@f8205corg.highwire.dtl.DTLVardef@1480b8org.highwire.dtl.DTLVardef@eb94e_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2020

Linking functional traits with tree growth and forest productivity in Quercus ilex forests along a climatic gradient

Plant functional traits are highly adaptable to changes in climatic factors and nutrient availability. However, the intraspecific plant response to abiotic factors and the overall effect on plant growth and productivity is still under debate. We studied forest productivity for 30 Quercus ilex subsp ballota forests in Spain along a broad climatic gradient of aridity (mean annual precipitation from 321 to 1582 mm). We used linear mixed models to quantify the effect of climatic and edaphic factors on functional traits, and to study the effect of functional traits and abiotic factors on the relative growth rate (RGR) of adult trees. Then we used piecewise structural equation models (SEMs) to determine the causal effect of intrinsic and extrinsic factors on forest productivity. Our results showed that forest productivity is positively affected by forest biomass and RGR, which are mainly affected by functional traits and tree biomass, respectively. In conclusion, intraspecific variability of functional traits have a significant effect on plant biomass and growth, which ultimately explain forest productivity in Quercus ilex.

ecology↗