Biology subjects

Santos, J. C.

Publications and source records attributed to Santos, J. C..

15 recordsLinked to original sources

bioRxiv2026

From diet to defense: serpin duplication and gene-expression evolution as putative contributors to poison-frog alkaloid sequestration

Diverse organisms use toxins as antipredator defenses. Although many taxa synthesize their toxins, dietary toxin acquisition is less documented, particularly in vertebrates. In poison frogs (Dendrobatidae), efficient sequestration of dietary alkaloids evolved at least three times from ancestors that bore at most trace concentrations of skin alkaloids. Yet molecular mechanisms underlying poison-frog sequestration remain poorly understood. We used two approaches to address this. First, we performed a broad phylogenetic analysis of the serpinA gene family, which includes serpina1-like/alkaloid-binding globulin (ABG), the putative dendrobatid alkaloid transporter, and biliverdin-binding serpins (BBSs), which bind and spectrally tune biliverdin in blue-green arboreal frogs. Second, we used an evolutionarily narrower but discovery-oriented liver gene-expression analysis, contrasting seven populations from two sequestering Epipedobates species, the most recent origin of sequestration among dendrobatids (<15 mya), with two trace-accumulating lineages, Silverstoneia and Hyloxalus. Phylogenetic analyses revealed extensive diversification of ABGs and BBS-like genes in Dendrobatidae, forming two and five major clades, respectively. These expansions reveal broader ligand-binding serpin diversity than previously recognized and indicate that alkaloid sequestration may involve multiple ABG paralogs. Gene-expression analyses revealed 23 candidate genes associated with small-molecule transport, xenobiotic metabolism, and immune response, including serpina1-like, which was overexpressed in Epipedobates. A co-expression network analysis independently placed 20 of the 23 candidates into four key modules (enriched for differentially-expressed genes, containing [≥]1 candidate, and correlated with sequestration). Our findings point to ligand-binding-protein diversification and coordinated gene-expression changes as major contributors to the evolution of alkaloid defenses in poison frogs.

evolutionary biology↗

bioRxiv2025

Caecilians maintain a functional long-wavelength-sensitive cone opsin gene despite signatures of relaxed selection and more than 200 million years of fossoriality

Vision is tuned to animals ecologies, evolving in response to specific light environments and visual needs. Transitions to fossorial lifestyles impose strong selective pressures favoring adaptations for underground life, such as increased skull ossification and reduced eye protrusion. Fossoriality may simultaneously relax constraints on vision leading to diminished visual capabilities. Caecilians (Gymnophiona)--specialized, fossorial amphibians--possess reduced eyes covered by skin or bone. For years, these traits, along with the presence of a single photoreceptor expressing one functional opsin gene, have been interpreted as evidence of limited vision, including an inability to focus or perceive color. Our results challenge these assumptions: we identified the long-wavelength-sensitive (LWS) opsin gene in 13 species of caecilians spanning 8 of 10 recognized families. Molecular evidence indicates that LWS is intact and transcribed in the eye of at least one species (Caecilia orientalis). However, the specific photoreceptor type expressing LWS remains uncertain, as our survey of cone phototransduction genes revealed a mosaic of losses, and anatomical observations from five families did not conclusively identify cone-like cells, though they revealed highly organized retinae even in families with vestigial eyes. Altogether, our results suggest that vision in caecilians may be underestimated and the role of light perception in their ecology is possible. TEASER TEXTThe colonization of low-light environments exerts selective pressure to enhance non-visual senses while relaxing selection on vision, often leading to opsin gene loss. We present compelling evidence for the retention of a cone opsin gene (LWS) in caecilians--a fossorial amphibian lineage with a 200-million-year history of burrowing and reduced eyes. Despite signs of relaxed selection, LWS appears functional, echoing patterns in other low-light-adapted vertebrates. Additionally, the loss of key cone phototransduction genes and absence of clear cone cells raises the possibility of LWS expression in rods or a functional change in its use. Our study provides an evolutionary framework for investigating LWS retention in fossorial vertebrates.

evolutionary biology↗

bioRxiv2025

SEPSIS-INDUCED LIPID DROPLET ACCUMULATION ENHANCES ANTIBACTERIAL INNATE IMMUNITY

Lipid droplets (LDs) are lipid-rich organelles recognized as central players in lipid homeostasis, signaling, and inflammation. While their functions in inflammation are well-documented, the role of LDs in antibacterial immunity and infection resistance remains less understood. In this study, we investigated triglyceride synthesis and LD accumulation in the context of antibacterial innate immunity during sepsis. Our results show that LD accumulation is part of immunometabolic reprogramming in E. coli-infected macrophages. Pharmacological inhibition or genetic knockdown of DGAT1, a key enzyme in triglyceride synthesis, reduced LD formation, bacterial clearance, and pro-inflammatory responses (nitric oxide, PGE2, CCL2, IL-6, IFN-{beta}). Notably, DGAT1 inhibition impaired the expression of several interferon-stimulated genes (ISGs), including viperin, iNOS, cathelicidin, and IGTP, in E. coli-infected macrophages. In a sepsis model, DGAT1 inhibition reduced sepsis-induced LD accumulation in peritoneal cells and decreased levels of CCL2, IFN-{beta}, nitric oxide, and lipid mediators (PGE2, LTB4, and RvD1). Furthermore, DGAT1 inhibition accelerated sepsis-related mortality, coinciding with elevated bacterial loads in the peritoneum and bloodstream at 6 and 24 hours post-sepsis. Our results demonstrate that tryglicerides synthesis and LDs are critical regulators of infection resistance, contributing to both bacterial clearance and the coordination of a protective proinflammatory response during sepsis.

immunology↗

bioRxiv2024

Ninjurin-1 mediated plasma membrane rupture is a two-step process requiring cell swelling

Ninjurin-1 (NINJ1) executes cell lysis by polymerizing into filaments, yet how these form membrane lesions is unknown. Integrating cell-based assays with molecular dynamics simulations, we demonstrate that NINJ1-driven membrane rupture starts with the lateral association of NINJ1 dimers into double filaments. Subsequently, swelling of necrotic cells increases plasma membrane tension, leading to separation of the filament interface and NINJ1 lesion opening. Inhibiting cell swelling prevents this increase in tension, blocking NINJ1-mediated plasma membrane rupture without disrupting NINJ1 oligomerization, implicating membrane tension as key for opening NINJ1 lesions. The NINJ1 homolog NINJ2 oligomerizes but fails to form membrane lesions during cell death due to the greater stability of its dimer. Finally, using atomic force microscopy of NINJ1-containing proteoliposomes, we show that NINJ1 forms large pores by stabilizing membrane edges. In summary, our findings support a model whereby membrane tension drives a zipper-like opening of NINJ1 double filaments, initiating necrotic cell lysis.

immunology↗

bioRxiv2024

Passive accumulation of alkaloids in putatively non-toxic frogs challenges paradigms of the origins of acquired chemical defenses

Understanding the origins of novel, complex phenotypes is a major goal in evolutionary biology. Poison frogs of the family Dendrobatidae have evolved the novel ability to acquire alkaloids from their diet for chemical defense at least three times. However, taxon sampling for alkaloids has been biased towards colorful species, without similar attention paid to inconspicuous ones that are often assumed to be undefended. As a result, our understanding of how chemical defense evolved in this group is incomplete. Here we provide new data showing that, in contrast to previous studies, species from each undefended poison frog clade have measurable yet low amounts of alkaloids. We confirm that undefended dendrobatids regularly consume mites and ants, which are known sources of alkaloids. Thus, our data suggest that diet is insufficient to explain the defended phenotype. Our data support the existence of a phenotypic intermediate between toxin consumption and sequestration -- passive accumulation -- that differs from sequestration in that it involves no derived forms of transport and storage mechanisms yet results in low levels of toxin accumulation. We discuss the concept of passive accumulation and its potential role in the origin of chemical defenses in poison frogs and other toxin-sequestering organisms. In light of ideas from pharmacokinetics we incorporate new and old data from poison frogs into an evolutionary model that could help explain the origins of acquired chemical defenses in animals and provide insight into the molecular processes that govern the fate of ingested toxins. ResumenComprender los origenes de fenotipos novedosos y complejos es un objetivo central en biologia evolutiva. Las ranas venenosas de la familia Dendrobatidae han desarrollado una novedosa habilidad para adquirir alcaloides de su dieta como defensas quimicas, al menos tres veces. Sin embargo, el muestreo de taxones en busca de alcaloides ha estado sesgado hacia las especies coloridas, sin prestar atencion similar a las poco conspicuas que a menudo se presume, no tienen defensas. Como resultado, nuestra comprension de como evolucionan las defensas quimicas en este grupo es incompleta. Aqui, proporcionamos nuevos datos que muestran que, en contraste con estudios anteriores, las especies de cada clado de ranas venenosas no defendidas tienen cantidades bajas pero cuantificables de alcaloides. Confirmamos que los dendrobatidos no defendidos consumen regularmente acaros y hormigas, que son fuentes conocidas de alcaloides. Por lo tanto, nuestros datos sugieren que la dieta es insuficiente para explicar el fenotipo defendido. Nuestros datos respaldan la existencia de un fenotipo intermedio entre consumo y secuestro de toxinas (acumulacion pasiva), que difiere del secuestro en que no implica formas derivadas de mecanismos de transporte y almacenamiento, pero da lugar a bajos niveles de acumulacion de toxinas. Discutimos el concepto de acumulacion pasiva y su potencial rol en el origen de defensas quimicas en ranas venenosas y otros organismos que secuestran toxinas. Considerando ideas de farmacocinetica, incorporamos datos nuevos y antiguos de ranas venenosas dentro de un modelo evolutivo que podria ayudar a explicar los origenes de defensas quimicas adquiridas en animales, y proporcionar una vision de los procesos moleculares que regulan el destino de las toxinas ingeridas.

evolutionary biology↗

bioRxiv2023

The high infectivity of the SARS-CoV-2 Omicron variant is associated with an exclusive S477N spike receptor-binding domain mutation

The spike glycoprotein receptor-binding domain (RBD) of SARS-CoV-2 facilitates viral binding to the ACE2 receptor and mediates viral infectivity. The Delta and Omicron variants of concern are the most infectious strains, presenting mutated amino acid residues in their spike RBD. The Omicron variant quickly dominated the COVID-19 pandemic, indicating its greater spreadability. Omicrons spreading might be associated with mutational substitutions at spike RBD residues. We employed in silico molecular dynamics (MD) simulation of the spike RBD-ACE2 interaction to compare the impact of specific mutations of the Delta and Omicron variants. The MD of the spike-ACE2 interaction showed the following: i) the amino acid profile involved in the spike-ACE2 interaction differs between Delta and Omicron; ii) the Omicron variant establishes several additional interactions, highlighting the spike RBD (S477), which is a flexible mutational residue. Since the S477N mutation is exclusive to Omicron, which may initiate binding with ACE2, the increased infectivity of Omicron might be associated not only with a mutated RBD but also with unmutated (e.g., G476 and L492) residues, initiating binding due to the influence of the N477 mutation. Compared to previous variants, Omicrons N477 residue represents a novelty within the spike-ACE2 interaction dynamics interface.

bioinformatics↗

bioRxiv2023

Deep Divergences Among Cryptic Clades of Epipedobates Poison Frogs

Poison frogs (Dendrobatidae) are famous for their aposematic species, having a combination of diverse color patterns and defensive skin toxins, yet most species in this family are inconspicuously colored and considered non-aposematic. Epipedobates is among the youngest genus-level clades of Dendrobatidae that includes both aposematic and inconspicuous species. Using Sanger-sequenced mitochondrial and nuclear markers, we demonstrate deep genetic divergences among inconspicuous species of Epipedobates but relatively shallow genetic divergences among conspicuous species. Our phylogenetic analysis includes broad geographic sampling of the inconspicuous lineages typically identified as E. boulengeri and E. espinosai, which reveals two putative new species, one in west-central Colombia (E. sp. 1) and the other in north-central Ecuador (E. aff. espinosai). We conclude that E. darwinwallacei is a junior subjective synonym of E. espinosai. We also clarify the geographic distributions of inconspicuous Epipedobates species including the widespread E. boulengeri. We provide a qualitative assessment of the phenotypic diversity in each nominal species, with a focus on the color and pattern of inconspicuous species. We conclude that Epipedobates contains eight known valid species, six of which are inconspicuous. A relaxed molecular clock analysis suggests that the most recent common ancestor of Epipedobates is [~]11.1 million years old, which nearly doubles previous estimates. Last, genetic information points to a center of species diversity in the Choco at the southwestern border of Colombia with Ecuador. A Spanish translation this text is available in the supplementary materials on the publishers website (biorxiv does not allow posting in non-English languages).

evolutionary biology↗

bioRxiv2022

Diurnality shapes the visual opsin genes of colorful Neotropical frogs

Amphibians are ideal for studying visual system evolution because their biphasic (aquatic and terrestrial) life history and ecological diversity expose them to a broad range of visual conditions. Here we evaluate signatures of selection on visual opsin genes across Neotropical anurans and focus on three diurnal clades that are well-known for the concurrence of conspicuous colors and chemical defense (i.e., aposematism): poison frogs (Dendrobatidae), Harlequin toads (Bufonidae: Atelopus), and pumpkin toadlets (Brachycephalidae: Brachycephalus). We found evidence of positive selection on 44 amino acid sites in LWS, SWS1, SWS2, and RH1 opsin genes, of which one in LWS and two in RH1 have been previously identified as spectral tuning sites in other vertebrates. Given that anurans have mostly nocturnal habits, the patterns of selection revealed new sites that might be important in spectral tuning for frogs, potentially for adaptation to diurnal habits and for color-based intraspecific communication. Furthermore, we provide evidence that SWS2, normally expressed in rod cells in amphibians, has likely been lost in the ancestor of Dendrobatidae, suggesting that under low-light levels, dendrobatids have inferior wavelength discrimination compared to other frogs. This loss might follow the origin of diurnal activity in dendrobatids and could have implications for their chemical ecology, biodiversity, and behavior. Our analyses show that assessments of opsin diversification in understudied groups could expand our understanding of the role of sensory system evolution in ecological adaptation.

evolutionary biology↗

bioRxiv2022

GPR183 mediates the capacity of the novel CD47-CD19 bispecific antibody TG-1801 to heighten ublituximab-umbralisib (U2) anti-lymphoma activity

Targeted therapies have considerably improved the survival rate of B-cell non-Hodgkin lymphoma (B-NHL) patients in the last decade; however, most subtypes remain incurable. TG-1801, a bispecific antibody that targets CD47 selectively on CD19+ B-cells, is under clinical evaluation in relapsed/refractory B-NHL patients either as a single-agent or in combination with ublituximab, a CD20 antibody, which is also being combined with the PI3K{delta}/CK1e inhibitor, umbralisib ("U2"-regimen). In this study, we demonstrated that TG-1801 potentiates ublituximab-mediated antibody-dependent cell death (ADCC) and antibody-dependent cell phagocytosis (ADCP), leading to an additive anti-tumour effect of the TG-1801/U2 combination in B-NHL co-cultures. Accordingly, in a B-NHL xenotransplant model, the triplet achieved a 93% tumour growth inhibition, with 40% of the animals remaining tumour-free 35 days after the last dosing. Transcriptomic analysis further uncovered the upregulation of the G protein-coupled receptor, GPR183, as a crucial event associated with TG-1801/U2 synergism, while pharmacological blockade or genetic depletion of this factor impaired ADCP initiation, as well as cytoskeleton remodelling and cell migration, in B-NHL cultures exposed to the drug combination. Thus, our results set the preclinical rationale and support a combination strategy of TG-1801 with PI3K{delta}- and CD20-targeting agents in patients with B-NHL.

cancer biology↗

bioRxiv2021

Optogenetic activators of apoptosis, necroptosis and pyroptosis for probing cell death dynamics and bystander cell responses

Targeted and specific induction of cell death in individual or groups of cells holds the potential for new insights into the response of tissues or organisms to different forms of death. Here we report the development of optogenetically-controlled cell death effectors (optoCDEs), a novel class of optogenetic tools that enables light-mediated induction of three types of programmed cell death (PCD) - apoptosis, pyroptosis and necroptosis - using Arabidopsis thaliana photosensitive protein Cryptochrome2. OptoCDEs enable rapid and highly specific induction of PCD in human, mouse and zebrafish cells and are suitable for a wide range of applications, such as sub-lethal cell death induction or precise elimination of single cells or cell populations in vitro and in vivo. As the proof-of-concept, we utilize optoCDEs to assess the differences in the neighboring cell response to apoptotic or necrotic PCD, revealing a new role for shingosine-1-phosphate signaling in regulating the efferocytosis of apoptotic cell by epithelia.

cell biology↗

bioRxiv2021

The AIRE G228W mutation results in a longer-lasting AIRE-SIRT1 interaction

The autoimmune regulator (AIRE) protein functions as a tetramer, interacting with partner proteins to form the "AIRE complex," which relieves RNA Pol II stalling in the chromatin of medullary thymic epithelial cells (mTECs). AIRE is the primary mTEC transcriptional controller, promoting the expression of a large set of peripheral tissue antigen genes implicated in the negative selection of self-reactive thymocytes. Under normal conditions, the SIRT1 protein temporarily interacts with AIRE and deacetylates K residues of the AIRE SAND domain. Once the AIRE SAND domain is deacetylated, the binding with SIRT1 is undone, allowing the AIRE complex to proceed downstream with the RNA Pol II to the elongation phase of transcription. Considering that the in silico and in vitro binding of the AIRE SAND domain with SIRT1 provides a powerful model system for studying the dominant SAND G228W mutation mechanism, which causes the autoimmune polyglandular syndrome-1, we integrated computational molecular modeling, docking, dynamics between the whole SAND domain with SIRT1, and surface plasmon resonance using a peptide harboring the 211 to 230 residues of the SAND domain, to compare the structure and energetics of binding/release between AIRE G228 (wild-type) and W228 (mutant) SAND domain to SIRT1. We observed that the G228W mutation in the SAND domain negatively influences the AIRE-SIRT1 interaction. The disturbed interaction might cause a disruption in the binding of the AIRE SAND domain with the SIRT1 catalytic site, impairing the AIRE complex to proceed downstream with RNA Pol II.

immunology↗

bioRxiv2021

The high infectivity of SARS-CoV-2 B.1.1.7 is associated with increased interaction force between Spike-ACE2 caused by the viral N501Y mutation

The Spike glycoprotein receptor-binding domain (RBD) of SARS-CoV-2 mediates the viral particles binding to the angiotensin-converting enzyme 2 (ACE2) receptor on the surface of human cells. Therefore, Spike-ACE2 interaction is a crucial determining factor for viral infectivity. A new phylogenetic group of SARS-CoV-2 (lineage B.1.1.7) has been recently identified in the COVID-19 Genomics UK Consortium dataset, which features an amino acid substitution in the Spike RBD (N501Y mutation). Infections with the SARS-CoV-2 lineage B.1.1.7 have been overgrowing in recent weeks in the United Kingdom, indicating an even greater spread capacity than that seen with previous strains of the novel coronavirus. We hypothesized that this rapid spreading/infectivity of the B.1.1.7 lineage might be due to changes in the interaction force between the mutant Spike RBD and ACE2. This study employed in silico methods involving mutagenesis (N501Y mutation) and interface analysis focusing on the Spike RDB-ACE2 interaction. The results showed that the SARS-CoV-2 N501Y mutant (lineage B.1.1.7) establishes a more significant number of interactions relating to the mutant residue Y501 (Spike RDB) with residues Y41 and K353 (ACE2). This finding shows that the increased infectivity of SARS-CoV-2 lineage B.1.1.7 is associated with the interaction force between the Spike RBD Y501 mutant residue with the ACE2 receptor, which in this strain is increased.

bioinformatics↗

bioRxiv2019

Much more than a clasp: Evolutionary pattern of amplexus diversity in anurans

The evolution and diversification of animal reproductive modes have been pivotal questions in behavioral ecology. Amphibians present the highest diversity of reproductive modes among vertebrates, involving various behavioral, physiological and morphological traits. One of such features is the amplexus, the clasp or embrace of males on females during reproduction, which is almost universal to anurans. Hypotheses about the origin amplexus are limited and have not been thoroughly tested, nor had they taken into account evolutionary relationships in most comparative studies. However, these considerations are crucial to understand the evolution of reproductive modes. Here, using an evolutionary framework, we reconstruct the ancestral state of amplexus in 686 anuran species; investigate whether the amplexus type is a conserved trait; and test whether sexual size dimorphism (SSD) could have influenced the amplexus type or male performance while clasping females. Overall, we found evidence of at least 35 evolutionary transitions in amplexus type across anurans. We also found that amplexus exhibits a high phylogenetic signal (it is conserved across Anura evolutionary history) and the amplexus type does not evolve in association with SSD. We discuss the implications of our findings on the diversity of amplexus types across anurans.

evolutionary biology↗

bioRxiv2019

Type-3 Secretion System-induced pyroptosis protects Pseudomonas against cell-autonomous immunity

Inflammasome-induced pyroptosis comprises a key cell-autonomous immune process against intracellular bacteria, namely the generation of dying cell structures. These so-called pore-induced intracellular traps (PITs) entrap and weaken intracellular microbes. However, the immune importance of pyroptosis against extracellular pathogens remains unclear. Here, we report that Type-3 secretion system (T3SS)-expressing Pseudomonas aeruginosa (P. aeruginosa) escaped PIT immunity by inducing a NLRC4 inflammasome-dependent macrophage pyroptosis response in the extracellular environment. To the contrary, phagocytosis of Salmonella Typhimurium promoted NLRC4-dependent PIT formation and the subsequent bacterial caging. Remarkably, T3SS-deficient Pseudomonas were efficiently sequestered within PIT-dependent caging, which favored exposure to neutrophils. Conversely, both NLRC4 and caspase-11 deficient mice presented increased susceptibility to T3SS-deficient P. aeruginosa challenge, but not to T3SS-expressing P. aeruginosa. Overall, our results uncovered that P. aeruginosa uses its T3SS to overcome inflammasome-triggered pyroptosis, which is primarily effective against intracellular invaders.\n\nImportanceAlthough innate immune components confer host protection against infections, the opportunistic bacterial pathogen Pseudomonas aeruginosa (P. aeruginosa) exploits the inflammatory reaction to thrive. Specifically the NLRC4 inflammasome, a crucial immune complex, triggers an Interleukin (IL)-1{beta} and -18 deleterious host response to P. aeruginosa. Here, we provide evidence that, in addition to IL-1 cytokines, P. aeruginosa also exploits the NLRC4 inflammasome-induced pro-inflammatory cell death, namely pyroptosis, to avoid efficient uptake and killing by macrophages. Therefore, our study reveals that pyroptosis-driven immune effectiveness mainly depends on P. aeruginosa localization. This paves the way toward our comprehension of the mechanistic requirements for pyroptosis effectiveness upon microbial infections and may initiate targeted approaches in order to ameliorate the innate immune functions to infections.\n\nGraphical abstractMacrophages infected with T3SS-expressing P. aeruginosa die in a NLRC4-dependent manner, which allows bacterial escape from PIT-mediated cell-autonomous immunity and neutrophil efferocytosis. However, T3SS-deficient P. aeruginosa is detected by both NLRC4 and caspase-11 inflammasomes, which promotes bacterial trapping and subsequent efferocytosis of P. aeruginosa-containing-PITs by neutrophils.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=64 SRC=\"FIGDIR/small/650333v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (15K):\norg.highwire.dtl.DTLVardef@17e05c4org.highwire.dtl.DTLVardef@aca55forg.highwire.dtl.DTLVardef@9d2853org.highwire.dtl.DTLVardef@1c275f9_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2019

Oxytocin, Compulsion and Epilepsy: Insights from a Complex Behavioral and Neuronal Networks Association

Previously we have demonstrated that microinjection of oxytocin (OT) into the central nucleus of amygdala (CeA) induces hypergrooming in Wistar rats, a model of compulsion. The Wistar Audiogenic Rat (WAR) strain is a genetic model of generalized tonic-clonic seizures. Here we quantified grooming behavior in WAR, with grooming scores, flowcharts and directed graphs of syntactic and non-syntactic grooming chains, after bilateral administration of OT or saline (SAL) into the CeA and investigated the association between hypergrooming and imunohistochemistry of Fos activated compulsion networks and proposing a computational model of grooming behavior. The activated networks, driven from a CeA OT-dependent grooming pattern, in both Wistar and WAR were detected as Fos+ regions: orbitofrontal cortex, striatum, paraventricular nucleus of the hypothalamus, dentate gyrus, substantia nigra compacta and reticulata. In conclusion we can drive hypergrooming in WARs, defined previously as a model of ritualistic motor behavior in Wistar rats, with OT from CeA, a limbic structure and one of the principal amygdala complex outputs. Furthermore, our current pioneer behavioral and cellular description considers that hypergrooming (compulsion) in WARs is a comorbidity because: (1) WARs have the highest grooming scores, when exposed only to novelty (2) WARs have better grooming scores than Wistars after CeA-SAL, (3) WARs perform much better than Wistars in OT-CeA-dependent highly stereotyped behavioral sequences, detected by flowcharts as a combination of syntactic/non-syntactic grooming chains, (4) the behavioral sequences here demonstrated for grooming and hypergrooming can be modeled as quite reliable Markov chains and (5) with the exception of CeA-SAL injected animals, an exquisite map of brain Fos expression was detected in typical cortico-striatal-thalamic-basal ganglia-cortical circuit, among new areas, driven by OT-CeA.\n\nAuthor SummaryGrooming is a complex set of regular behavioral sequences in rodents that can be mimicked with several pharmacological or molecular biology interventions. We have demonstrated previously that microinjection of the brain peptide oxytocin into the amygdala, a limbic region, induces hypergrooming in Wistar rats, a model of compulsion. The Wistar Audiogenic Rat strain is a genetic model of generalized seizures, in fact a model of epilepsy. Here we quantified grooming behavior in Wistar Audiogenic Rats, using several behavioral tools such as grooming scores, behavioral sequences and graphs of grooming chains, after bilateral administration of the oxytocin or its control (saline) into the amygdala. We also investigated the association between hypergrooming and activation of compulsion networks, proposing a computational (virtual) model of grooming behavior. Basically we were able to detect activated networks, driven from amygdala and the consequent oxytocin-dependent grooming pattern in epileptic and control animals. Those circuits are composed of cortical and subcortical areas, usually associated to the expression of motor rituals or compulsions. In conclusion, we can drive hypergrooming in epileptic animals, as compared to the previously defined model of ritualistic/compulsive motor behavior in control, rats. We concluded that hypergrooming (compulsion) is endogenously present in epileptic animals as a co-existent event (comorbidity), because when they were exposed to novelty, they express better grooming scores than control animals. The behavioral sequences here demonstrated for grooming and hypergrooming can be simulated as chains, where associations can be predicted from probabilities. Finally, an exquisite map of brain-activated cells was detected in both epileptic animal and their controls, in typical cortico-subcortical structures associated with rituals, but driven from a region which control emotions.

neuroscience↗