A Solvable Sequence Evolution Model and Genomic Correlations

We study a minimal model for genome evolution whose elementary processes are single site mutation, duplication and deletion of sequence regions and insertion of random segments. These processes are found to generate long-range correlations in the composition of letters as long as the sequence length is growing, i.e., the combined rates of duplications and insertions are higher than the deletion rate. For constant sequence length, on the other hand, all initial correlations decay exponentially. These results are obtained analytically and by simulations. They are compared with the long-range correlations observed in genomic DNA, and the implications for genome evolution are discussed.Comment: 4 pages, 4 figure

Grooming behaviour of honey bees (Hymenoptera: Apidae) on varroa (Mesostigmata: Varroidae)

Resumen: Entre los factores que pueden ayudar a disminuir y controlar la población de Varroa destructor en colonias de Apis mellifera está el comportamiento de acicalamiento. Este comportamiento consiste en la capacidad de la abeja de detectar, morder y eliminar los parásitos en etapa forética. En esta investigación se analizó la presencia del comportamiento de acicalamiento en colonias de abejas a través de la observación de ácaros dañados. Para ello se utilizaron seis colonias de abejas de la especie A. mellifera en colmenas tipo Langstroth, las cuales se evaluaron diariamente durante 30 días en abril y mayo del año 2008. Las muestras correspondieron a la caída diaria de ácaros a placas de metal con vaselina, ubicada en el piso de cada colmena por un periodo de 24 horas. Los resultados indicaron 95% de varroas caídas muertas y 5% vivas de un total de 2.005 varroas. Se encontró un 49% de ácaros con daños y 51% sin daños. Con base en lo observado existe la posibilidad de elegir colonias con comportamiento de acicalamiento de importancia como daño dorsal y daño completo sobre el acaro, lo cual puede ser muy útil para estudiar selección de abejas y diseñar estrategias de manejo integrado del ácaro V. destructor

Remote experiments for STEM education and engagement in rural schools: The case of project R3

Rural schools tend not to have enough laboratory and experimentation equipment, which can be an obstacle that hinders student learning in Science, Technology, Engineering, and Mathematics (STEM) areas. Moreover, this loss of competencies can reduce their employment opportunities while society itself is deprived of that human capital. Remote laboratories have emerged as a way of countering the effects of insufficient investment in equipment or the inability to acquire the latter. By way of example, the goal of Project R3, which is presented in this article, is to reduce the absence or shortage of laboratories in the rural world via the use of remote experimentation. Specifically, this article presents the experience, the results, and the main conclusions of Project R3 during its first year of life. It is worth noting that Project R3 has been deployed not only in rural but also in urban environments, making it possible to compare learning results and satisfaction levels for students in both spheres and identify those experiments that provide the best learning experience and are most popular among pupils and teachers. The main objective is that from the local analysis (the Project has only been conducted in Spain) it might be possible to draw conclusions of a global nature that might be extrapolated to other countries in the European Union with similar socio-demographics. Initial results are in the direction of certifying that student achievement and satisfaction are higher in rural than in urban environments

Propuesta de evaluación como proceso de revisión metodológica del aprendizaje. Uso de la rúbrica

Fil: Mansilla, Lilyán del V. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Geomorfología & Cátedra de Ambiente Físico; Argentina.Fil: Regis, Liliana B. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Geomorfología & Cátedra de Ambiente Físico; Argentina.El aprendizaje es el núcleo fundamental de la acción educativa. Valorar el aprendizaje del alumno en el proceso y en las competencias alcanzadas constituye uno de los aspectos más relevantes de la enseñanza. Desde la perspectiva de la evaluación formadora, multicultural, participativa y consensuada, centrada en el aprendizaje, se consideran diferentes técnicas e instrumentos. Estas herramientas de evaluación se definen como procedimientos y actividades realizadas por los alumnos con el fin de recoger información y medir el logro de los aprendizajes esperados en una determinada área del conocimiento. La rúbrica o matriz es un instrumento de evaluación que consiste en una tabla de doble entrada donde se establecen niveles de desempeños, logros de los objetivos y competencias de los estudiantes, sobre aspectos determinados y con criterios específicos. Las rúbricas son guías precisas que valoran los aprendizajes y productos realizados. El presente trabajo permite conocer la experiencia del uso de la rúbrica como instrumento de evaluación en el trabajo práctico de campo de la asignatura Geomorfología, de la carrera de Geología de la Universidad Nacional de Córdoba, República Argentina. El ajuste de la metodología se llevó a cabo durante el primer y segundo año de su aplicación, con resultados muy satisfactorios a lo largo de nueve años.La importancia en el uso de este instrumento de evaluación, ha sido eje fundamental en nuestra experiencia, consistió en constituir un elemento patrón y de normalización cuando son varios los docentes involucrados en las acciones de evaluación de una determinada materia o actividad práctica. La rúbrica permitió a los docentes consensuar y establecer criterios y parámetros de evaluación, y alcanzar un valor mínimo de subjetividad personal en una tarea colectiva.La importancia de esta propuesta de evaluación radica en la coincidencia de los resultados obtenidos cuando esaplicada por distintos docentes. Se reconoce la utilidad y el potencial de la rúbrica, no sólo como instrumento de evaluación sino también como proceso de revisión metodológica del aprendizaje.Considerando la trascendencia de evaluar los conocimientos y habilidades desarrollados en un trabajo Prácticode Campo, se pretende mediante la presente publicación, difundir una herramienta que agiliza y optimiza la tarea de evaluación de una actividad habitual en la carrera.Fil: Mansilla, Lilyán del V. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Geomorfología & Cátedra de Ambiente Físico; Argentina.Fil: Regis, Liliana B. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Geomorfología & Cátedra de Ambiente Físico; Argentina.Otras Ciencias de la Educació

Image Segmentation by Image Foresting Transform with Non-smooth Connectivity Functions

Abstract-Image segmentation, such as to extract an object from a background, is very useful for medical and biological image analysis. In this work, we propose new methods for interactive segmentation of multidimensional images, based on the Image Foresting Transform (IFT), by exploiting for the first time non-smooth connectivity functions (NSCF) with a strong theoretical background. The new algorithms provide global optimum solutions according to an energy function of graph cut, subject to high-level boundary constraints (polarity and shape), or consist in a sequence of paths' optimization in residual graphs. Our experimental results indicate substantial improvements in accuracy in relation to other state-of-the-art methods, by allowing the customization of the segmentation to a given target object

Chitosan as Source for Pesticide Formulations

Late blight and wilt caused by the oomycete, Phytophthora infestans, and the fungus, Fusarium solani f. sp. eumartii, respectively, are severe diseases in Solanaceae crops worldwide. Although traditional approaches to control plant diseases have mainly relied on toxic chemical compounds, current studies are focused to identify more sustainable options. Finding alternatives, a low molecular weight chitosan (LMWCh) obtained from biomass of Argentine Sea’s crustaceans was assayed. In an attempt to characterize the action of LMWCh alone or in combination with the synthetic fungicide Mancozeb, the antimicrobial properties of LMWCh were assayed. In a side-by-side comparison with the SYTOX Green nucleic acid stain and the nitric oxide–specific probe, diaminofluorescein-FM diacetate (DAF-FM DA), yielded a similar tendency, revealing LMWCh-mediated cell death. The efficacy of LMWCh, Mancozeb, and the mixture LMWCh–Mancozeb was in turn tested. A synergistic effect in the reduction of F. eumartii spore germination was measured in the presence of subinhibitory dosis of 0.025 mg ml−1 LMWCh and 0.008 mg ml−1 Mancozeb. This mixture was efficient to increase the effectiveness of the single treatments in protecting against biotic stress judged by a drastic reduction of lesion area in P. infestans–inoculated tissues and activation of the potato defense responses

Image Segmentation by Image Foresting Transform with Non-smooth Connectivity Functions

Abstract-In the framework of the Image Foresting Transform (IFT), there is a class of connectivity functions that were vaguely explored, which corresponds to the non-smooth connectivity functions (NSCF). These functions are more adaptive to cope with the problems of field inhomogeneity, which are common in MR images of 3 Tesla. In this work, we investigate the NSCF from the standpoint of theoretical and experimental aspects. We formally classify several non-smooth functions according to a proposed diagram representation. Then, we investigate some theoretical properties for some specific regions of the diagram. Our analysis reveals that many NSCFs are, in fact, the result of a sequence of optimizations, each of them involving a maximal set of elements, in a well-structured way. Our experimental results indicate that substantial improvements can be obtained by NSCFs in the 3D segmentation of MR images of 3 Tesla, when compared to smooth connectivity functions

Inhibition of the sodium-dependent HCO₃ - transporter SLC4A4, produces a cystic fibrosis-like airway disease phenotype

\ua9 2022, eLife Sciences Publications Ltd. All rights reserved. Bicarbonate secretion is a fundamental process involved in maintaining acid-base homeostasis. Disruption of bicarbonate entry into airway lumen, as has been observed in cystic fibrosis, produces several defects in lung function due to thick mucus accumulation. Bicarbonate is critical for correct mucin deployment and there is increasing interest in understanding its role in airway physiology, particularly in the initiation of lung disease in children affected by cystic fibrosis, in the absence of detectable bacterial infection. The current model of anion secretion in mammalian airways consists of CFTR and TMEM16A as apical anion exit channels, with limited capacity for bicarbonate transport compared to chloride. However, both channels can couple to SLC26A4 anion exchanger to maximise bicarbonate secretion. Nevertheless, current models lack any details about the identity of the basolateral protein(s) responsible for bicarbonate uptake into airway epithelial cells. We report herein that the electrogenic, sodium-dependent, bicarbonate cotransporter, SLC4A4, is expressed in the basolateral membrane of human and mouse airways, and that it’s pharmacological inhibition or genetic silencing reduces bicarbonate secretion. In fully differentiated primary human airway cells cultures, SLC4A4 inhibition induced an acidification of the airways surface liquid and markedly reduced the capacity of cells to recover from an acid load. Studies in the Slc4a4-null mice revealed a previously unreported lung phenotype, characterized by mucus accumulation and reduced mucociliary clearance. Collectively, our results demonstrate that the reduction of SLC4A4 function induced a CF-like phenotype, even when chloride secretion remained intact, highlighting the important role SLC4A4 plays in bicarbonate secretion and mammalian airway function

Endocardial Approach for Substrate Ablation in Brugada Syndrome: Epicardial, Endocardial or Transmural Substrate?

Background: Radiofrequency ablation (RFA) in Brugada syndrome (BrS) has been performed both endocardially and epicardially. The substrate in BrS is thus unclear.Objectives: To investigate the functional endocardial substrate and its correlation with clinical, electrophysiological and ECG findings in order to guide an endocardial ablation.Methods: Thirteen patients (38.7±12.3 years old) with spontaneous type 1 ECG BrS pattern, inducible VF with programmed ventricular stimulation (PVS) and syncope without prodromes were enrolled. Before to endocardial mapping the patients underwent flecainide testing with the purpose of measuring the greatest ST-segment elevation for to be correlated with the size and location of substrate in the electro-anatomic map. Patients underwent endocardial bipolar and electro-anatomic mapping with the purpose of identify areas of abnormal electrograms (EGMs) as target for RFA and determine the location and size of the substrate.Results: When the greatest ST-segment elevation was in the 3rd intercostal space (ICS), the substrate was located upper in the longitudinal plane of the right ventricular outflow tract (RVOT) and a greatest ST-segment elevation in 4th ICS correspond with a location of substrate in lower region of longitudinal plane of RVOT. A QRS complex widening on its initial and final part, with prolonged transmural and regional depolarization time of RVOT corresponded to the substrate locateded in the anterior-lateral region of RVOT. A QRS complex widening rightwards and only prolonged transmural depolarization time corresponded with a substrate located in the anterior, anterior-septal or septal region of RVOT. RFA of endocardial substrate suppressed the inducibility and ECG BrS pattern during 34.7±15.5 months. After RFA, flecainide testing confirmed elimination of the ECG BrS pattern. Endocardial biopsy showed a correlation between functional and ultrastructural alterations in two patients.Keywords: Brugada syndrome; Radiofrequency catheter ablation; Electrocardiography; Mapping; Biopsy.Conclusion: Endocardial RFA can eliminate the BrS phenotype and inducibility during PVS.Fil: Tauber, Pablo E.. Centro Modelo del Corazón; Argentina. Gobierno de Tucumán. Ministerio de Salud. Hospital Centro de Salud "Zenón J. Santillán"; ArgentinaFil: Mansilla, Virginia. Centro Modelo del Corazón; ArgentinaFil: Brugada, Pedro. Free University of Brussels. Cardiovascular Division. Cardiovascular Institute; BélgicaFil: Sanchez, Sara Serafina del V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Honore, Stella Maris. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Elizari, Marcelo. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Chain Molina, Sergio. Centro Modelo del Corazón; ArgentinaFil: Albano, Félix A.. Gobierno de Tucumán. Ministerio de Salud. Hospital Centro de Salud "Zenón J. Santillán"; ArgentinaFil: Corbalán, Ricardo R.. Centro Modelo del Corazón; ArgentinaFil: Figueroa Castellanos, Federico. Clínica Mayo; ArgentinaFil: Alzugaray, Damián. Abbott; Argentin

A new approach for the treatment of CLL using chlorambucil/hydroxychloroquine-loaded anti-CD20 nanoparticles

Current approaches for the treatment of chronic lymphocytic leukemia (CLL) have greatly improved the prognosis for survival, but some patients remain refractive to these therapeutic regimens. Hence, in addition to reducing the long-term sideeffects of therapeutics for all leukemia patients, there is an urgent need for novel therapeutic strategies for difficult-to-treat leukemia cases. Due to the cytotoxicity of drugs, the major challenge currently is to deliver the therapeutic agents to neoplastic cells while preserving the viability of non-malignant cells. In this study, we propose a therapeutic approach in which high doses of hydroxychloroquine and chlorambucil were loaded into biodegradable polymeric nanoparticles coated with an anti-CD20 antibody.We first demonstrated the ability of the nanoparticles to target and internalize in tumor B-cells. Moreover, these nanoparticles could kill not only p53-mutated/deleted leukemia cells expressing a low amount of CD20, but also circulating primary cells isolated from chronic lymphocytic leukemia patients. The safety of these nanoparticles was also demonstrated in healthy mice, and their therapeutic effects were shown in a new model of aggressive leukemia. These results showed that anti-CD20 nanoparticles containing hydroxychloroquine and chlorambucil can be effective in controlling aggressive leukemia and provided a rationale for adopting this approach for the treatment of other B-cell disorders. [Figure not available: see fulltext.