Adult People with Hemophilia A Have Low Annualized Bleeding Rate, However the Arthropathy Remains a Burden: A Retrospective Cohort Study.

Congenital Hemophilia A is a complex disease to treat, especially in places without access to hemophilia treatment centers (HTCs). The primary aim of this study was to analyze the outcomes of a cohort of adult people with congenital hemophilia A in an HTC localized in the Bajio region of Mexico. Observational retrospective study of a cohort of 82 adult people with congenital hemophilia A treated in a tertiary-level hospital in the Bajio region of Mexico, between June 2022 and June 2023. The median age of the patients was 29.5 years, 60.9% with severe hemophilia A, 53.6% were under some factor VIII prophylaxis regimen, and 52.4% had home therapy. The median annualized bleeding rate (ABR) was one bleed/year (IQR 0-3 bleeds/year) including a median of zero joint bleeds/year (IQR 0-3 bleeds/year). The presence of high-response inhibitors was detected in 8.5%, with an overall incidence of inhibitors of 14.6% of the cohort. Univariate analysis showed that inhibitors (OR 21.10; CI 95% 1.20-370.3; P = 0.03) and clinical arthropathy (OR 6.14; CI 95% 2.13-17.68; P = 0.001) were significantly higher in severe hemophilia. Clinically significant arthropathy was found in 71.9% of patients. Ultrasonography of the target joints showed that mainly cartilage degeneration was affected. Blood transfusion-associated viral infections were detected in 10.9% of patients. In our HTC, current treatment with hemostatic agents allows adequate control of ABR with acceptable inhibitor rates. However, we still have joint damage in most patients, which is partly explained by the fact that prophylaxis was introduced only in recent years.

Quality of life, craniomandibular function, and psychosocial factors related to pain and movement in patients with head and neck cancer.

PURPOSE: To describe the characteristics of and the associations between health-related quality of life, pain, craniomandibular function, and psychosocial factors related to pain and fear of movement in patients with head and neck cancer. METHODS: Seventy-eight patients diagnosed with HNC were recruited. Measurements of the maximum mouth opening range and pressure pain thresholds on the masseter muscle and the distal phalanx of the thumb were conducted, as well as a battery of self-report questionnaires were administrated, including the QoL Questionnaire (EORT QLQ-H&N35), Numeric Rating Scale (NRS), Pain Catastrophizing Scale (PCS), the Spanish translation of the Tampa Scale for Kinesiophobia for Temporomandibular Disorders (TSK-TMD), and the short version of the Craniofacial Pain and Disability Inventory (CF-PDI-11). RESULTS: The study sample (66.7% men, mean age 60.12 [11.95] years) experienced a moderate impact on their QoL levels (57.68 [18.25] EORT QLQ-H&N35) and high kinesiophobia values (20.49 [9.11] TSK-TMD). Pain was present in 41% of the patients, but only 3.8% reported severe pain. 26.4% had a restricted mouth opening range, and 34.62% showed significant catastrophism levels. There were strong positive correlations between EORT QLQ-H&N35 and CF-PDI-11 (r = 0.81), between NRS and CF-PDI-11 (r = 0.74), and between PCS and CF-PDI-11 (r = 0.66). CONCLUSION: Patients with HNC experience negative effects in their QoL, related to their impairment in craniomandibular function. Fear of movement, pain intensity, and catastrophism are associated with poorer functionality; relationships that should be considered when attempting to improve health care.

Beyond the acute phase: a comprehensive literature review of long-term sequelae resulting from infectious diseases.

Infectious diseases have consistently served as pivotal influences on numerous civilizations, inducing morbidity, mortality, and consequently redirecting the course of history. Their impact extends far beyond the acute phase, characterized by the majority of symptom presentations, to a multitude of adverse events and sequelae that follow viral, parasitic, fungal, or bacterial infections. In this context, myriad sequelae related to various infectious diseases have been identified, spanning short to long-term durations. Although these sequelae are known to affect thousands of individuals individually, a comprehensive evaluation of all potential long-term effects of infectious diseases has yet to be undertaken. We present a comprehensive literature review delineating the primary sequelae attributable to major infectious diseases, categorized by systems, symptoms, and duration. This compilation serves as a crucial resource, illuminating the long-term ramifications of infectious diseases for healthcare professionals worldwide. Moreover, this review highlights the substantial burden that these sequelae impose on global health and economies, a facet often overshadowed by the predominant focus on the acute phase. Patients are frequently discharged following the resolution of the acute phase, with minimal long-term follow-up to comprehend and address potential sequelae. This emphasizes the pressing need for sustained vigilance, thorough patient monitoring, strategic health management, and rigorous research to understand and mitigate the lasting economic and health impacts of infectious diseases more fully.

Ultrastructural analysis reveals mitochondrial placement independent of synapse placement in fine caliber C. elegans neurons.

Neurons rely on mitochondria for an efficient supply of ATP and other metabolites. However, while neurons are highly elongated, mitochondria are discrete and limited in number. Due to the slow rates of diffusion over long distances it follows that neurons would benefit from an ability to control the distribution of mitochondria to sites of high metabolic activity, such as synapses. It is assumed that neurons' possess this capacity, but ultrastructural data over substantial portions of a neuron's extent that would allow for tests of such hypotheses are scarce. Here, we mined the Caenorhabditis elegans electron micrographs of John White and Sydney Brenner and found systematic differences in average mitochondrial length (ranging from 1.3 to 2.4 µm), volume density (3.7% to 6.5%) and diameter (0.18 to 0.24 µm) between neurons of different neurotransmitter type and function, but found limited differences in mitochondrial morphometrics between axons and dendrites of the same neurons. Analyses of distance intervals found mitochondria to be distributed randomly with respect to presynaptic specializations, and an indication that mitochondria were displaced from postsynaptic specializations. Presynaptic specializations were primarily localized to varicosities, but mitochondria were no more likely to be found in synaptic varicosities than non-synaptic varicosities. Consistently, mitochondrial volume density was no greater in varicosities with synapses. Therefore, beyond the capacity to disperse mitochondria throughout their length, at least in C. elegans, fine caliber neurons manifest limited sub-cellular control of mitochondrial size and distribution.

Mitochondrial phosphagen kinases support the volatile power demands of motor nerve terminals.

Motor neurons are the longest neurons in the body, with axon terminals separated from the soma by as much as a meter. These terminals are largely autonomous with regard to their bioenergetic metabolism and must burn energy at a high rate to sustain muscle contraction. Here, through computer simulation and drawing on previously published empirical data, we determined that motor neuron terminals in Drosophila larvae experience highly volatile power demands. It might not be surprising then, that we discovered the mitochondria in the motor neuron terminals of both Drosophila and mice to be heavily decorated with phosphagen kinases - a key element in an energy storage and buffering system well-characterized in fast-twitch muscle fibres. Knockdown of arginine kinase 1 (ArgK1) in Drosophila larval motor neurons led to several bioenergetic deficits, including mitochondrial matrix acidification and a faster decline in the cytosol ATP to ADP ratio during axon burst firing. KEY POINTS: Neurons commonly fire in bursts imposing highly volatile demands on the bioenergetic machinery that generates ATP. Using a computational approach, we built profiles of presynaptic power demand at the level of single action potentials, as well as the transition from rest to sustained activity. Phosphagen systems are known to buffer ATP levels in muscles and we demonstrate that phosphagen kinases, which support such phosphagen systems, also localize to mitochondria in motor nerve terminals of fruit flies and mice. By knocking down phosphagen kinases in fruit fly motor nerve terminals, and using fluorescent reporters of the ATP:ADP ratio, lactate, pH and Ca2+ , we demonstrate a role for phosphagen kinases in stabilizing presynaptic ATP levels. These data indicate that the maintenance of phosphagen systems in motor neurons, and not just muscle, could be a beneficial initiative in sustaining musculoskeletal health and performance.

Bioinformatic analysis predicts that ethanol exposure during early development causes alternative splicing alterations of genes involved in RNA post-transcriptional regulation.

Prenatal ethanol exposure is associated with neurodevelopmental defects and long-lasting cognitive deficits, which are grouped as fetal alcohol spectrum disorders (FASD). The molecular mechanisms underlying FASD are incompletely characterized. Alternative splicing, including the insertion of microexons (exons of less than 30 nucleotides in length), is highly prevalent in the nervous system. However, whether ethanol exposure can have acute or chronic deleterious effects in this process is poorly understood. In this work, we used the bioinformatic tools VAST-TOOLS, rMATS, MAJIQ, and MicroExonator to predict alternative splicing events affected by ethanol from available RNA sequencing data. Experimental protocols of ethanol exposure included human cortical tissue development, human embryoid body differentiation, and mouse development. We found common genes with predicted differential alternative splicing using distinct bioinformatic tools in different experimental designs. Notably, Gene Ontology and KEGG analysis revealed that the alternative splicing of genes related to RNA processing and protein synthesis was commonly affected in the different ethanol exposure schemes. In addition, the inclusion of microexons was also affected by ethanol. This bioinformatic analysis provides a reliable list of candidate genes whose splicing is affected by ethanol during nervous system development. Furthermore, our results suggest that ethanol particularly modifies the alternative splicing of genes related to post-transcriptional regulation, which probably affects neuronal proteome complexity and brain function.

Early-life nutrition interacts with developmental genes to shape the brain and sleep behavior in Drosophila melanogaster.

The mechanisms by which the genotype interacts with nutrition during development to contribute to the variation of complex behaviors and brain morphology of adults are not well understood. Here we use the Drosophila Genetic Reference Panel to identify genes and pathways underlying these interactions in sleep behavior and mushroom body morphology. We show that early-life nutritional restriction effects on sleep behavior and brain morphology depends on the genotype. We mapped genes associated with sleep sensitivity to early-life nutrition, which were enriched for protein-protein interactions responsible for translation, endocytosis regulation, ubiquitination, lipid metabolism, and neural development. By manipulating the expression of candidate genes in the mushroom bodies (MBs) and all neurons, we confirm that genes regulating neural development, translation and insulin signaling contribute to the variable response of sleep and brain morphology to early-life nutrition. We show that the interaction between differential expression of candidate genes with nutritional restriction in early life resides in the MBs or other neurons and that these effects are sex-specific. Natural variations in genes that control the systemic response to nutrition and brain development and function interact with early-life nutrition in different types of neurons to contribute to the variation of brain morphology and adult sleep behavior.

Factorial analysis and gender invariance of GPIUS2 scale and evaluation ofCaplan’s cognitive-behavioral model of problematic Internet use in adolescents / Análisis factorial e invarianza de género de la escala GPIUS2 y evaluación del modelo cognitivo-conductual de Caplan del uso problemático de Internet en adolescentes

Caplan's (2010) revised cognitive-behavioral model of Problem-atic Internet Use (PIU) has become one of the most promising theoretical frameworks on such behavior in the last decade. The Generalized Prob-lematic Internet Use Scale (GPIUS2) (Caplan, 2010) has been adapted and validated for use with Spanish adolescents, but gender invariance has not been tested yet in this country. The present study focuses on three objec-tives: to confirm the factorial structure of GPIUS2, to analyze gender in-variance, and to test Caplan’s theoretical model, in a sample of Spanish ad-olescents. A cross-sectional study was carried out. The sample was com-posed of 909 participants from Spain, agedbetween 12 and 18 years (Mean age= 14.2, SD= 1.6). The results indicated a good fit of the GPIUS2 fac-tor structure and gender factorial invariance. Moreover, the cognitive-behavioral model fit the data. GPIUS2 has a very good structure and pre-sents gender factorial invariance, which favors its application in Spanish adolescent population. This study supports the cognitive-behavioral model of PIU.(AU)

El modelo cognitivo-conductual revisado de Caplan (2010) so-bre el Uso Problemático de Internet (UPI) es uno de los marcos teóricos más prometedores sobre dicho comportamiento en la última década. La Escala Uso Problemático de Internet Generalizado(GPIUS2) (Caplan, 2010) ha sido adaptada y validada para su uso con adolescentes españoles, pero aún no se ha comprobado su invarianza de género en España. El pre-sente estudio se centra en tres objetivos: confirmar la estructura factorial de la escala GPIUS2, analizar la invarianza de género de dicha escala y poner a prueba el modelo teórico de Caplan en una muestra de adolescentes espa-ñoles. Se realizó un estudio transversal. La muestra estuvo compuesta por 909 participantes de España, con edades comprendidas entre los 12 y los 18 años (Edad media= 14.2, DT= 1.6). Los resultados indicaron un buen ajuste de la estructura factorial del GPIUS2 e invarianza factorial en fun-ción del género. Además, el modelo cognitivo-conductual mostró un buen ajuste de los datos. La GPIUS2 tiene una muy buena estructura y presenta invarianza factorial para el género, lo que favorece su aplicación en la po-blación adolescente española. Este estudio apoya el modelo cognitivo-conductual en el UPI.(AU)

Lipophorin receptors regulate mushroom body development and complex behaviors in Drosophila.

BACKGROUND: Drosophila melanogaster lipophorin receptors (LpRs), LpR1 and LpR2, are members of the LDLR family known to mediate lipid uptake in a range of organisms from Drosophila to humans. The vertebrate orthologs of LpRs, ApoER2 and VLDL-R, function as receptors of a glycoprotein involved in development of the central nervous system, Reelin, which is not present in flies. ApoER2 and VLDL-R are associated with the development and function of the hippocampus and cerebral cortex, important association areas in the mammalian brain, as well as with neurodevelopmental and neurodegenerative disorders linked to those regions. It is currently unknown whether LpRs play similar roles in the Drosophila brain. RESULTS: We report that LpR-deficient flies exhibit impaired olfactory memory and sleep patterns, which seem to reflect anatomical defects found in a critical brain association area, the mushroom bodies (MB). Moreover, cultured MB neurons respond to mammalian Reelin by increasing the complexity of their neurite arborization. This effect depends on LpRs and Dab, the Drosophila ortholog of the Reelin signaling adaptor protein Dab1. In vitro, two of the long isoforms of LpRs allow the internalization of Reelin, suggesting that Drosophila LpRs interact with human Reelin to induce downstream cellular events. CONCLUSIONS: These findings demonstrate that LpRs contribute to MB development and function, supporting the existence of a LpR-dependent signaling in Drosophila, and advance our understanding of the molecular factors functioning in neural systems to generate complex behaviors in this model. Our results further emphasize the importance of Drosophila as a model to investigate the alterations in specific genes contributing to neural disorders.

Autocrine/Paracrine Slit-Robo Signaling Controls Optic Lobe Development in Drosophila melanogaster.

Cell segregation mechanisms play essential roles during the development of the central nervous system (CNS) to support its organization into distinct compartments. The Slit protein is a secreted signal, classically considered a paracrine repellent for axonal growth through Robo receptors. However, its function in the compartmentalization of CNS is less explored. In this work, we show that Slit and Robo3 are expressed in the same neuronal population of the Drosophila optic lobe, where they are required for the correct compartmentalization of optic lobe neuropils by the action of an autocrine/paracrine mechanism. We characterize the endocytic route followed by the Slit/Robo3 complex and detected genetic interactions with genes involved in endocytosis and actin dynamics. Thus, we report that the Slit-Robo3 pathway regulates the morphogenesis of the optic lobe through an atypical autocrine/paracrine mechanism in addition to its role in axon guidance, and in association with proteins of the endocytic pathway and small GTPases.

Dlg Is Required for Short-Term Memory and Interacts with NMDAR in the Drosophila Brain.

The vertebrates' scaffold proteins of the Dlg-MAGUK family are involved in the recruitment, clustering, and anchoring of glutamate receptors to the postsynaptic density, particularly the NMDA subtype glutamate-receptors (NRs), necessary for long-term memory and LTP. In Drosophila, the only gene of the subfamily generates two main products, dlgA, broadly expressed, and dlgS97, restricted to the nervous system. In the Drosophila brain, NRs are expressed in the adult brain and are involved in memory, however, the role of Dlg in these processes and its relationship with NRs has been scarcely explored. Here, we show that the dlg mutants display defects in short-term memory in the olfactory associative-learning paradigm. These defects are dependent on the presence of DlgS97 in the Mushroom Body (MB) synapses. Moreover, Dlg is immunoprecipitated with NRs in the adult brain. Dlg is also expressed in the larval neuromuscular junction (NMJ) pre and post-synaptically and is important for development and synaptic function, however, NR is absent in this synapse. Despite that, we found changes in the short-term plasticity paradigms in dlg mutant larval NMJ. Together our results show that larval NMJ and the adult brain relies on Dlg for short-term memory/plasticity, but the mechanisms differ in the two types of synapses.

An Early Disturbance in Serotonergic Neurotransmission Contributes to the Onset of Parkinsonian Phenotypes in Drosophila melanogaster.

Parkinson's disease (PD) is a neurodegenerative disease characterized by motor symptoms and dopaminergic cell loss. A pre-symptomatic phase characterized by non-motor symptoms precedes the onset of motor alterations. Two recent PET studies in human carriers of mutations associated with familial PD demonstrate an early serotonergic commitment-alteration in SERT binding-before any dopaminergic or motor dysfunction, that is, at putative PD pre-symptomatic stages. These findings support the hypothesis that early alterations in the serotonergic system could contribute to the progression of PD, an idea difficult to be tested in humans. Here, we study some components of the serotonergic system during the pre-symptomatic phase in a well-characterized Drosophila PD model, Pink1B9 mutant flies. We detected lower brain serotonin content in Pink1B9 flies, accompanied by reduced activity of SERT before the onset of motor dysfunctions. We also explored the consequences of a brief early manipulation of the serotonergic system in the development of motor symptoms later in aged animals. Feeding young Pink1B9 flies with fluoxetine, a SERT blocker, prevents the loss of dopaminergic neurons and ameliorates motor impairment observed in aged mutant flies. Surprisingly, the same pharmacological manipulation in young control flies results in aged animals exhibiting a PD-like phenotype. Our findings support that an early dysfunction in the serotonergic system precedes and contributes to the onset of the Parkinsonian phenotype in Drosophila.

Machine learning to investigate superficial white matter integrity in early multiple sclerosis.

BACKGROUND AND PURPOSE: This study aims todetermine the sensitivity of superficial white matter (SWM) integrity as a metric to distinguish early multiple sclerosis (MS) patients from healthy controls (HC). METHODS: Fractional anisotropy and mean diffusivity (MD) values from SWM bundles across the cortex and major deep white matter (DWM) tracts were extracted from 29 early MS patients and 31 age- and sex-matched HC. Thickness of 68 cortical regions and resting-state functional-connectivity (RSFC) among them were calculated. The distribution of structural and functional metrics between groups were compared using Wilcoxon rank-sum test. Utilizing a machine learning method (adaptive boosting), 6 models were built based on: 1-SWM, 2-DWM, 3-SWM and DWM, 4-cortical thickness, or 5-RSFC measures. In model 6, all features from previous models were incorporated. The models were trained with nested 5-folds cross-validation. Area under the receiver operating characteristic curve (AUCroc ) values were calculated to evaluate classification performance of each model. Permutation tests were used to compare the AUCroc values. RESULTS: Patients had higher MD in SWM bundles including insula, inferior frontal, orbitofrontal, superior and medial temporal, and pre- and post-central cortices (p < .05). No group differences were found for any other MRI metric. The model incorporating SWM and DWM features provided the best classification (AUCroc = 0.75). The SWM model provided higher AUCroc (0.74), compared to DWM (0.63), cortical thickness (0.67), RSFC (0.63), and all-features (0.68) models (p < .001 for all). CONCLUSION: Our results reveal a non-random pattern of SWM abnormalities at early stages of MS even before pronounced structural and functional alterations emerge.

Effect of Kidney Transplantation on Accelerated Immunosenescence and Vascular Changes Induced by Chronic Kidney Disease.

Kidney transplantation is the best option for patients with end-stage renal disease. Despite the improvement in cardiovascular burden (leading cause of mortality among patients with chronic kidney disease), cardiovascular adverse outcomes related to the inflammatory process remain a problem. Thus, the aim of the present study was to characterize the immune profile and microvesicles of patients who underwent transplantation. We investigated the lymphocyte phenotype (CD3, CD4, CD8, CD19, and CD56) and monocyte phenotype (CD14, CD16, CD86, and CD54) in peripheral blood, and endothelium-derived microvesicles (annexin V+CD31+CD41-) in plasma of patients with advanced chronic kidney disease (n = 40), patients with transplantation (n = 40), and healthy subjects (n = 18) recruited from the University Hospital "12 de Octubre" (Madrid, Spain). Patients with kidney transplantation had B-cell lymphopenia, an impairment in co-stimulatory (CD86) and adhesion (CD54) molecules in monocytes, and a reduction in endothelium-derived microvesicles in plasma. The correlations between those parameters explained the modifications in the expression of co-stimulatory and adhesion molecules in monocytes caused by changes in lymphocyte populations, as well as the increase in the levels of endothelial-derived microvesicles in plasma caused by changes in lymphocyte and monocytes populations. Immunosuppressive treatment could directly or indirectly induce those changes. Nevertheless, the particular characteristics of these cells may partly explain the persistence of cardiovascular and renal alterations in patients who underwent transplantation, along with the decrease in arteriosclerotic events compared with advanced chronic kidney disease. In conclusion, the expression of adhesion molecules by monocytes and endothelial-derived microvesicles is related to lymphocyte alterations in patients with kidney transplantation.

Oxidative Stress in Patients with Advanced CKD and Renal Replacement Therapy: The Key Role of Peripheral Blood Leukocytes.

Oxidative stress plays a key role in the pathophysiology of chronic kidney disease (CKD). Most studies have investigated peripheral redox state focus on plasma, but not in different immune cells. Our study analyzed several redox state markers in plasma and isolated peripheral polymorphonuclear (PMNs) and mononuclear (MNs) leukocytes from advanced-CKD patients, also evaluating differences of hemodialysis (HD) and peritoneal dialysis (PD) procedures. Antioxidant (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH)) and oxidant parameters (xanthine oxidase (XO), oxidized glutathione (GSSG), malondialdehyde (MDA)) were assessed in plasma, PMNs and MNs from non-dialysis-dependent-CKD (NDD-CKD), HD and PD patients and healthy controls. Increased oxidative stress and damage were observed in plasma, PMNs and MNs from NDD-CKD, HD and PD patients (increased XO, GSSG and MDA; decreased SOD, CAT, GPX and GSH; altered GSSG/GSH balance). Several oxidative alterations were more exacerbated in PMNs, whereas others were only observed in MNs. Dialysis procedures had a positive effect on preserving the GSSG/GSH balance in PMNs. Interestingly, PD patients showed greater oxidative stress than HD patients, especially in MNs. The assessment of redox state parameters in PMNs and MNs could have potential use as biomarkers of the CKD progression.

Slit/Robo Signaling Regulates Multiple Stages of the Development of the Drosophila Motion Detection System.

Neurogenesis is achieved through a sequence of steps that include specification and differentiation of progenitors into mature neurons. Frequently, precursors migrate to distinct positions before terminal differentiation. The Slit-Robo pathway, formed by the secreted ligand Slit and its membrane bound receptor Robo, was first discovered as a regulator of axonal growth. However, today, it is accepted that this pathway can regulate different cellular processes even outside the nervous system. Since most of the studies performed in the nervous system have been focused on axonal and dendritic growth, it is less clear how versatile is this signaling pathway in the developing nervous system. Here we describe the participation of the Slit-Robo pathway in the development of motion sensitive neurons of the Drosophila visual system. We show that Slit and Robo receptors are expressed in different stages during the neurogenesis of motion sensitive neurons. Furthermore, we find that Slit and Robo regulate multiple aspects of their development including neuronal precursor migration, cell segregation between neural stem cells and daughter cells and formation of their connectivity pattern. Specifically, loss of function of slit or robo receptors in differentiated motion sensitive neurons impairs dendritic targeting, while knocking down robo receptors in migratory progenitors or neural stem cells leads to structural defects in the adult optic lobe neuropil, caused by migration and cell segregation defects during larval development. Thus, our work reveals the co-option of the Slit-Robo signaling pathway in distinct developmental stages of a neural lineage.

Cell segregation and boundary formation during nervous system development.

The development of multicellular organisms involves three main events: differentiation, growth, and morphogenesis. These processes need to be coordinated for a correct developmental program to work. Mechanisms of cell segregation and the formation of boundaries during development play essential roles in this coordination, allowing the generation and maintenance of distinct regions in an organism. These mechanisms are also at work in the nervous system. The process of regionalization involves first the patterning of the developing organism through gradients and the expression of transcription factors in specific regions. Once different tissues have been induced, segregation mechanisms may operate to avoid cell mixing between different compartments. Three mechanisms have been proposed to achieve segregation: (1) differential affinity, which mainly involves the expression of distinct pools of adhesion molecules such as members of the cadherin superfamily; (2) contact inhibition, which is largely mediated by Eph-ephrin signaling; and (3) cortical tension, which involves the actomyosin cytoskeleton. In many instances, these mechanisms collaborate in cell segregation. In the last three decades, there have been several advances in our understanding of how cell segregation and boundaries participate in the development of the nervous system. Interestingly, as in other aspects of development, the molecular players are remarkably similar between vertebrates and invertebrates. Here we summarize the main concepts of cell segregation and boundary formation, focusing on the nervous system and highlighting the similarities between vertebrate and invertebrate model organisms.

Study of the release of endogenous amines in Drosophila brain in vivo in response to stimuli linked to aversive olfactory conditioning.

A highly challenging question in neuroscience is to understand how aminergic neural circuits contribute to the planning and execution of behaviors, including the generation of olfactory memories. In this regard, electrophysiological techniques like Local Field Potential or imaging methods have been used to answer questions relevant to cell and circuit physiology in different animal models, such as the fly Drosophila melanogaster. However, these techniques do not provide information on the neurochemical identity of the circuits of interest. Different approaches including fast scan cyclic voltammetry, allow researchers to identify and quantify in a timely fashion the release of endogenous neuroactive molecules, but have been only used in in vitro Drosophila brain preparations. Here, we report a procedure to record for the first time the release of endogenous amines -dopamine, serotonin and octopamine- in adult fly brain in vivo, by fast scan cyclic voltammetry. As a proof of principle, we carried out recordings in the calyx region of the Mushroom Bodies, the brain area mainly associated to the generation of olfactory memories in flies. By using principal component regression in normalized training sets for in vivo recordings, we detect an increase in octopamine and serotonin levels in response to electric shock and olfactory cues respectively. This new approach allows the study of dynamic changes in amine neurotransmission that underlie complex behaviors in Drosophila and shed new light on the contribution of these amines to olfactory processing in this animal model.

Slit neuronal secretion coordinates optic lobe morphogenesis in Drosophila.

The complexity of the nervous system requires the coordination of multiple cellular processes during development. Among them, we find boundary formation, axon guidance, cell migration and cell segregation. Understanding how different cell populations such as glial cells, developing neurons and neural stem cells contribute to the formation of boundaries and morphogenesis in the nervous system is a critical question in neurobiology. Slit is an evolutionary conserved protein essential for the development of the nervous system. For signaling, Slit has to bind to its cognate receptor Robo, a single-pass transmembrane protein. Although the Slit/Robo signaling pathway is well known for its involvement in axon guidance, it has also been associated to boundary formation in the Drosophila visual system. In the optic lobe, Slit is expressed in glial cells, positioned at the boundaries between developing neuropils, and in neurons of the medulla ganglia. Although it has been assumed that glial cells provide Slit to the system, the contribution of the neuronal expression has not been tested. Here, we show that, contrary to what was previously thought, Slit protein provided by medulla neurons is also required for boundary formation and morphogenesis of the optic lobe. Furthermore, tissue specific rescue using modified versions of Slit demonstrates that this protein acts at long range and does not require processing by extracellular proteases. Our data shed new light on our understanding of the cellular mechanisms involved in Slit function in the fly visual system morphogenesis.