Biology subjects

Suarez, A.

Publications and source records attributed to Suarez, A..

9 recordsLinked to original sources

bioRxiv2026

The fidelity of mRNA translation as a novel regulatory layer for brain development

Although the fidelity of mRNA translation is essential for maintaining proteome integrity, whether translation error rates vary across cell types and developmental stages in vivo remains largely unexplored. Here, we generate a gain-of-activity dual-luciferase knock-in reporter mouse that enables quantitative monitoring of translation errors in vivo. Using this system, we systematically characterize the spatiotemporal dynamics of translation fidelity across mammalian development. Mature organs exhibit lower error rates than pluripotent embryonic stem cells. Translation fidelity diverges sharply among organs, becoming progressively established during embryonic development, with brain and muscle displaying the highest accuracy. To determine functional significance, we experimentally increased translation errors during cerebral organoid formation and in vitro neuronal differentiation. Elevated error rates reduced neuronal output by impairing neuronal maturation without altering neural progenitor populations. Consistently, differentiated neurons display uniformly elevated fidelity across multiple classes of translation errors, including stop codon readthrough, amino acid misincorporation, and ribosomal frameshifting. These findings demonstrate that translation fidelity is not a fixed intrinsic property of the translation machinery but is developmentally regulated and required for efficient neuronal differentiation. Together, our results identify translation fidelity as a developmentally tuned, tissue-specific dimension of gene expression in vivo.

developmental biology↗

bioRxiv2025

Dopamine supports reward prediction to constrain reward seeking

Reward predictions not only promote reward pursuit, they also shape how reward is pursed. Such predictions are supported by environmental cues that signal reward availability and probability. Such cues trigger dopamine release in the nucleus accumbens core (NAc). Thus, here we used dopamine sensor fiber photometry, cell-type and pathway-specific optogenetic inhibition, Pavlovian cue-reward conditioning, and test of cue-induced reward-pursuit strategy in male and female rats, to ask whether cue-evoked phasic dopamine release is shaped by reward prediction to support reward pursuit. We found that cue-evoked NAc core dopamine is positively shaped by reward prediction and inversely relates to and predicts instrumental reward seeking. Cues that predicted imminent reward with high probability triggered a large NAc dopamine response and this was associated checking for the expected reward in the delivery location, rather than instrumental reward seeking. Cues that predicted reward with low probability elicited less dopamine and this was associated with a bias towards seeking, rather than check for reward. Correspondingly, inhibition of cue-evoked NAc dopamine increased instrumental reward-seeking and decreased reward-checking behavior. Thus, transient, cue-evoked NAc core dopamine release supports reward prediction to shape reward-pursuit strategy. SIGNIFICANCE STATEMENTCues that signal reward availability can cause us to pursue reward. To ensure this is adaptive, we use the predictions these cues enable to help us decide how to pursue reward. When reward prediction is low, well seek out new reward opportunities. When it is high, well exploit the expected reward by checking for it in its usual location. Here we discovered that transient, cue-evoked nucleus accumbens dopamine fluctuations support reward predictions to shape how reward is pursued. The data show that dopamine can actually constrain reward seeking and promoting reward checking when reward is predicted strongly and imminently. These results provide new information on how dopamine shapes behavior in the moment and help understand the link between motivational and dopamine disruptions in psychiatric conditions such as addictions and depression.

neuroscience↗

bioRxiv2024

Cooperation maximizes biodiversity

Cooperation, the mutual benefit that individuals of different species obtain when they interact together, is ubiquitous in nature. Despite their importance, most of all current ecological theories have been formalized focusing on negative interactions such as competition or predation. The role of cooperation, or other types of positive interactions including facilitation and mutualism, has not been fully addressed, or, if so, always in combination with negative interactions. This fact limits our understanding of the unique features by which cooperation as opposed to competition promotes biodiversity. To address this gap, we introduce here cooperation into structural stability, a general framework to understand how species interactions and environmental variability determine the long-term persistence of species within communities. Compared to a pure competitive case, cooperation promotes three distinctive features. First, cooperation increases the opportunities for species to coexist. This feature increases the persistence of species with contrasted phylogenetic, functional, and demographic strategies that the environment would otherwise filter. Second, cooperation creates intertwined biodiversity where the existence of some species begets the presence of others. Third, cooperation promotes multistability by changing the dynamics of community assembly due to variations in environmental conditions. In conclusion, we present a fully operational framework to understand the unique ecological roles of cooperation in nature. It indicates that cooperation as opposed to competition maximizes the maintenance of biodiversity.

ecology↗

bioRxiv2023

AAGGG repeat expansions trigger RFC1-independent synaptic dysregulation in human CANVAS Neurons

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a late onset, recessively inherited neurodegenerative disorder caused by biallelic, non-reference pentameric AAGGG(CCCTT) repeat expansions within the second intron of replication factor complex subunit 1 (RFC1). To investigate how these repeats cause disease, we generated CANVAS patient induced pluripotent stem cell (iPSC) derived neurons (iNeurons) and utilized calcium imaging and transcriptomic analysis to define repeat-elicited gain-of-function and loss-of-function contributions to neuronal toxicity. AAGGG repeat expansions do not alter neuronal RFC1 splicing, expression, or DNA repair pathway functions. In reporter assays, AAGGG repeats are translated into pentapeptide repeat proteins that selectively accumulate in CANVAS patient brains. However, neither these proteins nor repeat RNA foci were detected in iNeurons, and overexpression of these repeats in isolation did not induce neuronal toxicity. CANVAS iNeurons exhibit defects in neuronal development and diminished synaptic connectivity that is rescued by CRISPR deletion of a single expanded allele. These phenotypic deficits were not replicated by knockdown of RFC1 in control neurons and were not rescued by ectopic expression of RFC1. These findings support a repeat-dependent but RFC1-independent cause of neuronal dysfunction in CANVAS, with important implications for therapeutic development in this currently untreatable condition. SummaryHuman CANVAS neurons exhibit transcriptional and functional synaptic defects that are corrected by heterozygous repeat deletion but are independent of the gene within which they reside--RFC1.

neuroscience↗

bioRxiv2021

Cooperation enhances structural stability in mutualistic systems

Dynamical systems on graphs allow to describe multiple phenomena from different areas of Science. In particular, many complex systems in Ecology are studied by this approach. In this paper we analize the mathematical framework for the study of the structural stability of each stationary point, feasible or not, introducing a generalization for this concept, defined as Global Structural Stability. This approach would fit with the proper mathematical concept of structural stability, in which we find a full description of the complex dynamics on the phase space due to nonlinear dynamics. This fact can be analyzed as an informational field grounded in a global attractor whose structure can be completely characterized. These attractors are stable under perturbation and suppose the minimal structurally stable sets. We also study in detail, mathematically and computationally, the zones characterizing different levels of biodiversity in bipartite graphs describing mutualistic antagonistic systems of population dynamics. In particular, we investigate the dependence of the region of maximal biodiversity of a system on its connectivity matrix. On the other hand, as the network topology does not completely determine the robustness of the dynamics of a complex network, we study the correlation between structural stability and several graph measures. A systematic study on synthetic and biological graphs is presented, including 10 mutualistic networks of plants and seed-dispersal and 1000 random synthetic networks. We compare the role of centrality measures and modularity, concluding the importance of just cooperation strength among nodes when describing areas of maximal biodiversity. Indeed, we show that cooperation parameters are the central role for biodiversity while other measures act as secondary supporting functions. Author summaryWe introduce the concept of Global Structural Stability as a proper mathematical concept to fully understand biodiversity in some ecological systems. Our concept retakes the definitions in the classical works of R. Thom [1] and Andronov-Pontryagin [2]. Moreover, there exists a close relation between the structure of a complex network, described as a graph, and its associated dynamics. Mutualistic networks introduce cooperation links between two groups of species, as plant and pollinators or seed-dispersal. The understanding of organizational aspects leading to maximizing biodiversity is one of the more important research areas in Theoretical and Applied Ecology. In this work we introduce a systematic study on different graph measures in order to identify optimal organization for maximal biodiversity (defined as structural stability). Our results conclude that, for mutualistic systems, the strength in cooperation parameters are the core fact, i.e., cooperation is the real fact optimizing biodiversity among other possible structural configurations.

ecology↗

bioRxiv2021

SARS-CoV-2 RBD-Tetanus toxoid conjugate vaccine induces a strong neutralizing immunity in preclinical studies

Controlling the global COVID-19 pandemic depends, among other measures, on developing preventive vaccines at an unprecedented pace. Vaccines approved for use and those in development intend to use neutralizing antibodies to block viral sites binding to the hosts cellular receptors. Virus infection is mediated by the spike glycoprotein trimer on the virion surface via its receptor binding domain (RBD). Antibody response to this domain is an important outcome of the immunization and correlates well with viral neutralization. Here we show that macromolecular constructs with recombinant RBD conjugated to tetanus toxoid induce a potent immune response in laboratory animals. Some advantages of the immunization with the viral antigen coupled to tetanus toxoid have become evident such as predominant IgG immune response due to affinity maturation and long-term specific B-memory cells. This paper demonstrates that subunit conjugate vaccines can be an alternative for COVID-19, paving the way for other viral conjugate vaccines based on the use of small viral proteins involved in the infection process.

immunology↗

bioRxiv2021

Surveillance of Shiga toxin-producing Escherichia coli associated bloody diarrhea in Argentina

In Argentina, the hemolytic uremic syndrome associated with Shiga toxin-producing Escherichia coli (STEC-HUS) infection is endemic, and reliable data about prevalence and risk factors are available since 2000. However, information about STEC-associated bloody diarrhea (BD) cases is limited. A prospective study was carried out in seven tertiary-hospitals and 18 Referral Units from different regions, aiming to determine (i) STEC-positive BD cases frequency in 714 children aged 1 to 9 years old; and (ii) rate of progression to HUS. The number and regional distribution of STEC-HUS cases assisted in the same hospitals and period was also assessed. A total of 29 (4.1%) STEC-positive BD cases were confirmed by Shiga Toxin Quik Chek (STQC) and/or mPCR. The highest frequencies were found in the Southern region (Neuquen, 8.7%; Bahia Blanca, 7.9%), in children between 12 and 23 month of age (8.8%), during summertime. Four (13.8%) cases progressed to HUS, three to five days after BD onset. Twenty-seven STEC-HUS children mainly under 5 years old (77.8%) were enrolled, 51.9% were female; 44% were Stx-positive by STQC and all by mPCR. The most common serotypes were O157:H7 and O145:H28 and prevalent genotypes were stx2a-only or associated, both among BD and HUS cases. Considering the endemic behavior of HUS and its impact on public health, it is important to have updated information about the epidemiology of the diarrheal disease for early recognition of infected patients and initiation of supportive treatment. Finally, it also gives the opportunity to respond to outbreak situations effectively and in timely manner.

microbiology↗

bioRxiv2020

Multi-Locus Molecular Phylogeny of Solenopsis (Hymenoptera: Formicidae)

The myrmicine ant genus Solenopsis is species-rich, globally distributed, and is often a common and ecologically important faunal element of the leaf litter. The genus is also well-known for containing several widely distributed tramp species and some of the worst invasive species in the World (the Red Imported Fire Ant, S. invicta, and the Tropical Fire Ant, S. geminata). Although not hyper-diverse and despite its ecological and economic importance, Solenopsis has long frustrated systematists due its lack of reliable diagnostic characters and no phylogenetic hypothesis exists to date. We present a preliminary multi-locus molecular phylogenetic analysis of Solenopsis to address this knowledge gap. Our analyses recover mostly well-supported phylogenetic hypothesis, which suggests Solenopsis arose in the Neotropics and spread to all other continents (except Antarctica). Importantly, it demonstrates problems with current systematic understanding of the genus, but provides an evolutionary framework upon which to build future research.

evolutionary biology↗

bioRxiv2017

Intracellular production of hydrogels and synthetic RNA granules by multivalent enhancers

Non-membrane bound, hydrogel-like entities, such as RNA granules, nucleate essential cellular functions through their unique physico-chemical properties. However, these intracellular hydrogels have not been as extensively studied as their extracellular counterparts, primarily due to technical challenges in probing these materials in situ. Here, by taking advantage of a chemically inducible dimerization paradigm, we developed iPOLYMER, a strategy for rapid induction of protein-based hydrogels inside living cells. A series of biochemical and biophysical characterizations, in conjunction with computational modeling, revealed that the polymer network formed in the cytosol resembles a physiological hydrogel-like entity that behaves as a size-dependent molecular sieve. We studied several properties of the gel and functionalized it with RNA binding motifs that sequester polyadenine-containing nucleotides to synthetically mimic RNA granules. Therefore, we here demonstrate that iPOLYMER presents a unique and powerful approach to synthetically reconstitute hydrogel-like structures including RNA granules in intact cells.

synthetic biology↗