Short-range regulatory chromatin loops in plants Gagliardi, Delfina; Manavella, Pablo Andrés In all eukaryotic organisms, gene expression correlates with the condensation state of the chromatin. Highly packed genome regions, known as heterochromatins, are associated with repressed loci, whereas euchromatic regions represent a relaxed state of the chromatin actively transcribed. However, even in these active regions, associations between chromatin domains dynamically modify genome topology and alter gene expression. Long-range interaction within and between chromosomes determines chromatin domains that help to coordinate transcriptional events. On the other hand, short-range chromatin interactions emerged as dynamic mechanisms regulating the expression of specific loci. Our current capacity to decipher genome topology at high resolution allowed us to identify numerous cases of short-range regulatory chromatin interactions, which are reviewed in this Insight article.

Solidification, macrostructure and shrinkage formation of ductile and compacted irons Boeri, Roberto Enrique; López, Marcos Gabriel; Tenaglia, Nicolás Emanuel; Massone, Juan Miguel This manuscript summarizes recent investigation of the authors into the solidification and shrinkage defect formation of ductile and compacted graphite cast irons. The study makes use of the DAAS (direct austempering after solidification) technique, developed earlier by some of the authors, to reveal the solidification grains. In addition, color metallography is used to reveal the microsegregation pattern. The formation of shrinkage defects is related to both the solidification macrostructure and the microsegregation pattern. The examination of the macrostructure shows that large solidification grains, composed by dendritic austenite and graphite, characterize the solidification of compacted graphite irons of carbon equivalent values ranging from hypoeutectic to hypereutectic. Similar results are observed for ductile iron, but in this case, the hypereutectic irons display a finer macrostructure. The characteristics of the primary austenite dendrites are revealed by the microsegregation pattern, which is exposed by the color etching reagent. This pattern also clarifies the nature of the interaction between the growing austenite and the compact and spheroidal graphite particles. The microshrinkage cavities in both ductile and compacted graphite irons form at the interior of the austenite grains, where fluid feeding cannot compensate the contraction of the last-to-freeze portions of the melt. Schematics of the solidification of ductile and compacted irons are proposed, accounting for the experimental observations.

Discovering the biogeographic history using predefined areas and explicit geographical data in the South American Liolaemus elongatus group (Iguania: Liolaemidae) Ruiz, Maria Soledad; Portelli, Sabrina Noelia; Hibbard, Thomas Nathaniel; Quinteros, Andres Sebastian The genus Liolaemus includes 268 species, classified in two subgenera, Eulaemus and Liolaemus sensu stricto. The latter is formed by 12 monophyletic groups; one of them being the Liolaemus elongatus group, distributed in South America. We studied the biogeographic history of the L. elongatus group. We obtained a phylogenetic hypothesis recovering five main clades: the L. punmahuida, L. elongatus sensu stricto, L. kriegi, L. petrophilus and L. capillitas clades. Based on that hypothesis we obtained a time calibrated tree. The ancestral ranges were estimated applying three methodologies: DEC, DEC+j (using predefined areas) and GEM (using explicit geographical data). Our results show that the ancestral area of the L. elongatus group was located in central Argentina, and its divergence began around 11.5 Mya. From here, a combination of events (founder events and/or vicariances) led the species to their current distribution. Despite their differences, DEC+j and GEM show congruent results.

Transgression of cooperative helping norms outweighs children's intergroup bias González Gadea, María Luz; Santamaria Garcia, Hernando; Aragón, Irina; Santamaría García, José; Herrera, Eduar; Ibañez, Agustin Mariano; Sigman, Mariano Some forms of cooperative helping do not bind people from a moral perspective but ensure the functioning of social groups. Here, we have assessed how children coordinate such nonobligatory social concerns with group identity concerns. We have performed three studies (3–11-years-old; N = 393) aimed at testing children's peer preferences and resource allocation toward neutral individuals that engage in helping and hindering behaviors toward in-group and out-group peers. In Study 1, we have found that, in helping contexts, children prioritized group concerns and exhibited in-group favoritism. In hindering contexts, they privileged helping norms and did not exhibit out-group derogation. In Studies 2 and 3, we have confirmed that transgressions of cooperative helping norms outweighed intergroup bias. Our results suggest that, when cooperative helping norms conflict with group identity concerns, helping norms take priority. When these principles are coextensive and not in conflict, children give priority to group concerns.

Aerial Load Transportation with Multiple Quadrotors Based on a Kinematic Controller and a Neural SMC Dynamic Compensation Rossomando, Francisco Guido; Rosales, Claudio Dario; Gimenez, Javier; Salinas, Lucio Rafael; Soria, Carlos; Sarcinelli Filho, Mario; Carelli Albarracin, Ricardo Oscar A novel formation control to transport a cable-suspended payload with two quadrotors is presented. The control structure is based on a layered scheme combining a kinematic null-space based controller and a neural sliding mode controller. The null-space controller is designed to generate velocity references to the quadrotors in the formation, whereas the neural sliding mode controller receives such reference velocities and performs a dynamic compensation for possible parametric uncertainties as well as for the dynamic perturbations caused by the load attached to the quadrotors. The stability of the closed-loop control system thus implemented is also proven with basis on the theory of Lyapunov. Very detailed dynamic models for the quadrotors, the flexible cables, and the payload are included in a highly realistic scenario. To close the work, numerical simulations are presented, whose results demonstrate a good performance of the proposed controller.

Cranial Anatomy and Paleoneurology of the Extinct Sloth Catonyx tarijensis (Xenarthra, Mylodontidae) From the Late Pleistocene of Oruro, Southwestern Bolivia Boscaini, Alberto; Iurino, Dawid A.; Mamani Quispe, Bernardino; Andrade Flores, Rubén; Sardella, Raffaele; Pujos, François Roger Francis; Gaudin, Timothy Extinct scelidotheriine sloths are among the most peculiar fossil mammals from South America. In recent decades, the external cranial anatomy of Pleistocene scelidotheres such as Scelidotherium, Catonyx, and Valgipes has been the subject of numerous studies, but their endocranial anatomy remains almost completely unknown. Today, computed tomographic (CT) scanning methodologies permit the exploration of previously inaccessible anatomical areas through a completely non-destructive process. For this reason, we undertook an analysis of the external and internal cranial anatomy of Catonyx tarijensis from the late Pleistocene of the Department of Oruro, in southwestern Bolivia. One particularly well-preserved specimen allowed detailed observation of all the main cranial osteological features, including the ear region and an almost complete hyoid apparatus, previously unknown for this taxon. Moreover, CT-scanning and subsequent elaboration of digital models of this specimen allowed observation of the brain cavity and cranial sinuses, and reconstruction of the trajectory of the main cranial nerves for the first time in an extinct scelidotheriine sloth. Additionally, we recovered the first three-dimensional reconstructions of the nasal cavity and the turbinates of an extinct sloth. In contrast to the usual depiction, the combined information from the external and internal anatomy suggests reduced lingual protrusion in Catonyx tarijensis, or at least a consistently more limited protrusion of the tongue in comparison with other mylodontid sloths such as Glossotherium robustum. The new morphological information recovered from this extinct sloth is compared with the available information for both extant and extinct forms, providing insights in the paleobiology of the extinct species. The present study reveals the importance of applying these novel non-destructive techniques to elucidate the evolutionary history of sloths.

Progesterone for the treatment of central nervous system disorders: the many signaling roads for a single molecule Gonzalez, Susana Laura Central nervous system (CNS) injuries and neurodegenerative diseases show a broad spectrum of common pathophysiological processes, including oxidative stress, neuroinflammation, excitotoxicity, demyelination and neurotransmission dysfunctions. Over the past decades, valuable experimental investigations have helped to clarify the role and timing of these multiple molecular and cellular mechanisms in each of these particular disorders, which usually overlap and critically contribute to long-term disability. However, up to now, no definite cures or effective disease-modifying therapies are available for any of these conditions. This has led to an active search of novel therapeutic approaches, including the repositioning of existing drugs for new indications, as a valid approach to promptly move candidate molecules to clinical trials. Progesterone, a steroid with a crucial role in the reproductive function in mammals, stands as one of these promising repositioning molecules to modulate the complex array of cellular and molecular events observed in several of these central nervous system diseases (Stein and Sayeed, 2019). Indeed, a great number of preclinical studies have provided solid basis for supporting a protective effect of progesterone in stroke, traumatic brain injury, spinal cord trauma, central and peripheral neuropathies, multiple sclerosis, and Alzheimer’s and Parkinson’s disease (González et al., 2019, 2020). Notwithstanding this remarkable number of studies exploring the beneficial effects of progesterone in CNS disorders, few of them offer a deeper look at the different receptors and complex signaling cascades involved. This perspective aims at expanding our view on the variety of receptors and signaling pathways that might be involved in progesterone-mediated actions in the nervous system as part of a rational strategy to promote a successful translation of steroid-based therapies for the treatment of neurological diseases.

Contribuciones para una crítica de la economía político-libidinal Exposto, Emiliano; Rodriguez Varela, Gabriel El ensayo examina la relación inmanente entre deseo inconsciente y valor en la sociedad productora de mercancías. La hipótesis es la siguiente: el valor es el sujeto del trabajo inconsciente del deseo en el capitalismo. Es en ese marco que se formula la categoría crítica deseo del Valor. La cual, entendida como proceso relacional específicamente moderno, refiere a la dinámica inconsciente de la producción social alienada a la forma abstracta del capital.; The essay examines the immanent relationship between unconscious desire and value in the commodity-producing society. The hypothesis is as follows: value is the subject of the unconscious work of desire in capitalism. It is within that framework that the critical desire category of Value is formulated. Which, understood as a specifically modern relational process, refers to the unconscious dynamics of social production alienated from the abstract form of capital.

Análisis morfométrico de cenizas volcánicas por microscopía holográfica digital; Morphometric análisis of vulcanic ashes by digital holografic microscopy Martinez, María Florencia; Monaldi, Andrea Carolina; Romero, Gladis Graciela; Blanc, Adriana Verónica; Baez, Walter Ariel Las cenizas volcánicas presentan formas, texturas y tamaños altamente irregulares. Estas características influyen en su comportamiento aerodinámico, velocidad de sedimentación y dispersión, distancias de desplazamiento, etc. En particular, su morfología brinda información sobre los mecanismos de fragmentación que ocurren durante una erupción, distintos estilos eruptivos, propiedades del magma y es una herramienta de gran utilidad para el modelado de plumas volcánicas. En este trabajo se aborda el estudio morfológico de cenizas volcánicas empleando microscopía holográfica digital. A partir del cálculo de parámetros de tamaño y forma, se lleva a cabo una caracterización morfológica-textural y granulométrica en dos y tres dimensiones de las muestras y una clasificación según el mecanismo de fragmentación del proceso eruptivo.; Volcanic ashes features, such as their shapes, textures and sizes, influence their aerodynamic behavior, travel distances, sedimentation and dispersion rates. In particular, their morphology provides information about the fragmentation mechanisms during an eruption, different eruptive styles, magma properties and also is a valuable tool for modeling volcanic plumes. In this work, digital holographic microscopy is used in order to perform a morphological analysis of ashes. A morphological, textural and granulometric 2D and 3D characterization is developed through the calculation of shape and size parameters along with a classification according to the fragmentation mechanism of the eruptive process.

Restitution of Human Remains and Landscape Resignification Curtoni, Rafael Pedro; Heider, Guillermo; Chaparro, Maria Gabriela; Tuninetti, Ángel The restitution of human remains is a process wherein diverse agencies and meanings emerge. In Argentina there has been a significant increase of these processes, as well as claims of human bodies, during the early twenty-first century, allowing the appearance of new actors, the reconfiguration of public policies, and varied academic approaches. This article deals with a seldom-studied phenomenon-resignification of the territory as a consequence of a restitution-focusing on a recent example that involved the Rankülche Nation, an Indigenous nation in central Argentina, and its relationship with the government of La Pampa province, with scientists, and with members of the local community.

Emotional stress induces structural plasticity in Bergmann glial cells via an AC5–CPEB3–GluA1 pathway Bender, Crhistian Luis; Sun, Xingxing; Farooq, Muhammad; Yang, Qian; Davison, Caroline; Maroteaux, Matthieu; Huang, Yi Shuian; Ishikawa, Yoshihiro; Liu, Siqiong June Stress alters brain function by modifying the structure and function of neurons and astrocytes. The fine processes of astrocytes are critical for the clearance of neurotransmitters during synaptic transmission. Thus, experience-dependent remodeling of glial processes is anticipated to alter the output of neural circuits. However, the molecular mechanisms that underlie glial structural plasticity are not known. Here we show that a single exposure of male and female mice to an acute stress produced a long-lasting retraction of the lateral processes of cerebellar Bergmann glial cells. These cells express the GluA1 subunit of AMPA-type glutamate receptors, and GluA1 knockdown is known to shorten the length of glial processes. We found that stress reduced the level of GluA1 protein and AMPA receptor-mediated currents in Bergmann glial cells, and these effects were absent in mice devoid of CPEB3, a protein that binds to GluA1 mRNA and regulates GluA1 protein synthesis. Administration of a b-adrenergic receptor blocker attenuated the reduction in GluA1, and deletion of adenylate cyclase 5 prevented GluA1 suppression. Therefore, stress suppresses GluA1 protein synthesis via an adrenergic/adenylyl cyclase/CPEB3 pathway, and reduces the length of astrocyte lateral processes. Our results identify a novel mechanism for GluA1 subunit plasticity in non-neuronal cells and suggest a previously unappreciated role for AMPA receptors in stress-induced astrocytic remodeling.

De “culpables” a “víctimas”: expansión y profesionalización del sistema de salud en la provincia Mendoza a fines del siglo XIX y principios del XX; From “culprits” to “victims:” the expansion and professionalization of the healthcare system in the province of Mendoza in the late nineteenth and early twentieth century Luis, Natalia Mabel; Aguerregaray Castiglione, Rosana Ignacia Entre fines del siglo XIX y comienzos del XX, la provincia de Mendoza presentabaun estado sanitario marcado por el crecimiento demográfico y urbanístico, laescasez de los servicios públicos y la destrucción de la antigua ciudad colonial comoconsecuencia del terremoto de 1861, lo que propiciaba un ambiente favorable para eldesarrollo de diversas enfermedades infectocontagiosas. El objetivo de este artículo esindagar cómo se fue profesionalizando y expandiendo el sistema de salud en la provinciade Mendoza a fines del siglo XIX e inicios del XX, y cómo esos factores, junto conlas representaciones sobre la enfermedad que predominaban en el discurso de la elitegobernante, incidieron en las políticas públicas para combatir las dolencias de la época.Para ello se consultaron diversos documentos escritos y fotográficos que permitieronanalizar las modificaciones del discurso y las políticas públicas implementadas.; From the late 19th century to the beginning of the 20th, the province of Mendoza presented problematic sanitary conditions due to rapid demographic and urban growth, the scarcity of public services, and the poor state of the old colonial city (destroyed by the 1861 earthquake), which facilitated the spread of various infectious diseases. The objective of this article is to inquire into the ways in which the healthcare system in the province of Mendoza both expanded and became increasingly professionalized from the late 19th to early 20th century. We explore how these factors, along with the predominant social representations of disease that permeated the discourses of governing elites, influenced public policy aimed at combating the diseases of the time. To that end, we consulted a wide range of written documents and photographic material that allowed us to analyze changes in discourse as well as public policy

El sistema universitario argentino: una lectura de sus transformaciones en el largo plazo 1983-2015; The Argentine university system: a long-term reading transformations (1983-2015) Buchbinder, Pablo Gabriel El objetivo del artículo es estudiar las transformaciones del sistemauniversitario argentino entre 1983 y 2015. Se analiza el crecimientodel número de estudiantes, la creación de nuevas instituciones y suefecto en la tasa de graduación. Se estudia además el papel de los factores institucionales y políticas para explicar la evolución y dinámicadel sistema; The objective of the article is to study the transformations of the Argentine university system between 1983 and 2015. The growth of the number of students, the creation of new institutions and their effect on the graduation rate is analyzed. The role of institutional and political factors to explain the evolution and dynamics of the system is also studied.

Violencia y autoridad en la escuela secundaria ¿Jóvenes "violentos" o adultos ausentes? Patierno, Nicolas El presente artículo es resultado de una investigación doctoral desarrollada entre los años 2011 y 2018, enfocada al estudio de lo que popular —y peligrosamente— se conoce como “violencia escolar”. La hipótesis que orienta este escrito supone que las expresiones juveniles que muchos educadores consideran “violentas” no son arrebatos cuyas causas puedan atribuirse únicamente a un individuo, sino que, en general, son manifestaciones (con un fuerte contenido “físico”), consecuencia de la autorregulación juvenil que sucede a la indiferencia de los adultos. El desarrollo de esta conjetura se sustenta sobre dos fuentes de información: una serie de entrevistas realizadas a docentes y alumnos de escuelas secundarias, y una minuciosa revisión de bibliografía especializada. Las conclusiones reivindican el lugar de la educación secundaria en el proceso de renuncia a la violencia, es decir, en la construcción de lazos sociales, el reconocimiento de un orden simbólico y el uso responsable del cuerpo.; This article is the result of a doctoral research project conducted between the years 2011 and 2018, focused on the stud of what is commonly-and dangerously-referred to as "school violence. " The hypothesis which orients this paper assumes that the youthful expressions which many educators consider "violent" are not isolated outbursts whose causes can be imputed to a single individual, but, in general, are manifestations (with a substantial "physical" component) produced by youths' self-regulation in response to the indifference of adults. Our proof of this hypothesis is based on two sources of information: a series of interviews with teachers and students at junior high schools and an exhaustive review of the specialized literature. The conclusions confirm the place of secondary education in the process of renouncing violence, in other words in the formation of social bonds, recognition of a symbolic order, and responsible use of the body.

Particularidades en el comportamiento del mercado de trabajo de Santiago del Estero. 1994-2007; Particularities of conducts in the labor market of Santiago del Estero 1994-2007 Gurmendi, Maria Noelia; Salvatierra, Rita Gabriela La provincia de Santiago del Estero constituye, dentro del país, una región conun peso marginal en la economía nacional (0,8% del PBi). se caracteriza por un secular rezago productivo, con una estructura en la producción con escasa participación industrial, lo que se traduce en un débil mercado de trabajo y en undeterioro social que afecta a un porcentaje importante de la población. en esta investigación se analiza el mercado de trabajo de los sectores productores de bienesy de servicios, los cuales exhiben particularidades y relaciones que ameritan unaexplicación científica. nuestro propósito reposa en develar los vínculos que estosmismos establecen, utilizando el PBG(Producto Bruto Geográfico) para Santiagodel Estero como indicador macroeconómico principal para explicar la lógica y dinámica con las que se movilizan los recursos entre los sectores a la luz de la teoría; he province of santiago del estero constitutes a region with a marginal weight in the national economy (0.8% of the country's Gdp) within the country. it is cha- racterized by a centuries-old productive lag, with a structure in production that has little industrial participation, which translates into a weak labor market and a social deterioration that affects a significant percentage of the population. this re- search analyzes the labor market of the sectors that produce goods and services, which exhibit particularities and relations that merit a scientific explanation. our purpose lies in disclosing the links that they establish, using the pBG (Gross Geo- graphic product) for santiago del estero as the main macroeconomic indicator, ex- plaining the logic and dynamics with which resources are mobilized between the sectors in the light of the theory.

Long-term management is needed for conserving plant diversity in a Wadden Sea salt marsh Chen, Qingqing; Bakker, Jan P.; Alberti, Juan; Smit, Christian Evaluation of long-term management regimes is important for guiding biodiversity conservation in salt marshes. However, such long-term experiments are sparse. Using a 46-year experiment in a salt marsh, we evaluated long-term effects of eight different management regimes (treatments; control, grazing, mowing, and their combinations) on the expansion of a late successional plant species (Elytrigia atherica), plant species richness and diversity, and community composition (species identities and dominance structure). Results show that E. atherica expanded strongly over time in the control treatment (without grazing or mowing) while plant species richness and diversity declined substantially. By contrast, E. atherica was greatly suppressed while plant species richness and diversity remained relatively unchanged in all other treatments except for the mowing, where species richness declined in the late season mowing treatment and plant diversity declined after 17 years in the both early and late season mowing treatment. Therefore, all management types except for the mowing were effective in conserving plant diversity. The trends for change in species identities reversed: change in species identities accumulated in the control treatment and exceeded that of other treatments 15 years after the start of the experiment. This suggests that results based on shorter-term (< 15 years) experiments may provide misleading conservation recommendations. Also, trends for change in dominance structure (taking abundance into account) were substantially different from those for species identities. Our results highlight the importance of long-term monitoring for guiding conservation management, and that monitoring should not only focus on the number of species but also community composition, to fully identify critical changes.

Cytochrome 450 metabolites of arachidonic acid (20-HETE, 11,12-EET and 14,15-EET) promote pheochromocytoma cell growth and tumor associated angiogenesis Cecilia, Colombero; Cárdenas, Sofía; Venara, Marcela Cristina; Martin, Ayelen; Pennisi, Patricia Alejandra; Barontini, Marta Beatriz; Nowicki, Susana The importance of cytochrome P450 (CYP)-derived arachidonic acid (AA) metabolites, 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) as tumor growth promotors has already been described in several cancer types. The aim of this study was to evaluate the role of these compounds in the biology of pheochromocytoma/paraganglioma. These tumors originate from chromaffin cells derived from adrenal medulla (pheochromocytomas) or extra-adrenal autonomic paraganglia (paragangliomas), and they represent the most common hereditary endocrine neoplasia. According to mutations in the driver genes, these tumors are divided in two clusters: pseudo-hypoxic and kinase-signaling EETs, but not 20-HETE, exhibited a potent ability to sustain growth in a murine pheochromocytoma cell line (MPC) in vitro, EETs promoted an increase in cell proliferation and a decrease in cell apoptosis. In a mouse model of pheochromocytoma, the inhibition of CYP-mediated AA metabolism using 1-aminobenzotriazol resulted in slower tumor growth, a decreased vascularization, and a lower final volume. Also, the expression of AA-metabolizing CYP monooxygenases was detected in tumor samples from human origin, being their apparent abundance and the production of both metabolites higher in tumors from the kinase-signaling cluster. This is the first evidence of the importance of CYP- derived AA metabolites in the biology and development of pheochromocytoma/paraganglioma tumors.

Comparative skin penetration profiles of formulations including ultradeformable liposomes as potential nanocosmeceutical carriers Izquierdo, María Cecilia; Lillo, Rolando Cristian Rodrigo; Bucci, Paula Lorena; Gomez, Gisela Eliane; Martínez, Luis; Alonso, Silvia del Valle; Calienni, Maria Natalia; Martinetti Montanari, Jorge Anibal Background: Ultradeformable liposomes are promising carriers for cosmeceutical actives as they can be loaded with molecules of different polarities, and they present unique penetration properties. Aims: While those features have already been tested, we wanted to know whether their special penetration properties could be maintained after incorporation in diverse cosmetic vehicles, including commercial products already in the market. Methods: Ultradeformable liposomes loaded with a lipophilic and a hydrophilic fluorescent probe were prepared by lipid film resuspension, followed by extrusion and incorporation to different vehicles and commercial products. Penetration was determined in human and pig skin by incubation, with the Saarbrücken penetration model, followed by the recovery of the probes or by fluorescence microscopy. Results: The incorporation of ultradeformable liposomes to cosmetic vehicles did not alter their penetration in most of the cases for human skin explants. Pig skin penetration presented significant differences compared with human explants. Conclusions: Ultradeformable liposomes could be useful as versatile cosmeceutical carriers in final product formulations.

Para la olla durante la pandemia: Economía popular y cuidados colectivos Fernandez Alvarez, Maria Ines; Pacífico, Florencia Daniela; Señoras, Dolores; Rognoli, Martín Cuatro millones de personas que forman parte la economía popular enfrentan un problema: si pierden la calle, no pueden trabajar; si no trabajan, no comen. La pandemia no solo ataca la salud pública, también refuerza desigualdades históricas y torna aún más precaria la vida en los barrios. Aunque las organizaciones conocen cómo es afrontar una crisis: lo hicieron en 1989, en 2001 y durante los cuatro años de Cambiemos. María Inés Fernández Álvarez, Florencia Pacífico y Dolores Señorans destacan que el Estado es vital para contrarrestar los efectos recesivos del aislamiento y dicen que hoy el desafío es fortalecer las redes de cuidado colectivo y generar formas de solidaridad aún en la distancia.

Neurochemical characterization of brainstem pro-opiomelanocortin cells Georgescu, Teodora; Lyons, David; Doslikova, Barbora; García, Ana Paula; Marston, Oliver; Burke, Luke K.; Chianese, Raffaella; Lam, Brian Y.H.; Yeo, Giles S.H.; Rochford, Justin J.; Garfield, Alastair S.; Heisler, Lora K. Genetic research has revealed pro-opiomelanocortin (POMC) to be a fundamental regulator of energy balance and body weight in mammals. Within the brain, POMC is primarily expressed in the arcuate nucleus of the hypothalamus (ARC), while a smaller population exists in the brainstem nucleus of the solitary tract (POMCNTS). We performed a neurochemical characterization of this understudied population of POMC cells using transgenic mice expressing green fluorescent protein (eGFP) under the control of a POMC promoter/enhancer (PomceGFP). Expression of endogenous Pomc mRNA in the nucleus of the solitary tract (NTS) PomceGFP cells was confirmed using fluorescence-activating cell sorting (FACS) followed by quantitative PCR. In situ hybridization histochemistry of endogenous Pomc mRNA and immunohistochemical analysis of eGFP revealed that POMC is primarily localized within the caudal NTS. Neurochemical analysis indicated that POMCNTS is not co-expressed with tyrosine hydroxylase (TH), glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), brain-derived neurotrophic factor (BDNF), nesfatin, nitric oxide synthase 1 (nNOS), seipin, or choline acetyltransferase (ChAT) cells, whereas 100% of POMCNTS is co-expressed with transcription factor paired-like homeobox2b (Phox2b). We observed that 20% of POMCNTS cells express receptors for adipocyte hormone leptin (LepRbs) using a PomceGFP:LepRbCre:tdTOM double-reporter line. Elevations in endogenous or exogenous leptin levels increased the in vivo activity (c-FOS) of a small subset of POMCNTS cells. Using ex vivo slice electrophysiology, we observed that this effect of leptin on POMCNTS cell activity is postsynaptic. These findings reveal that a subset of POMCNTS cells are responsive to both changes in energy status and the adipocyte hormone leptin, findings of relevance to the neurobiology of obesity.