Spike train statistics and Gibbs distributions

This paper is based on a lecture given in the LACONEU summer school, Valparaiso, January 2012. We introduce Gibbs distribution in a general setting, including non stationary dynamics, and present then three examples of such Gibbs distributions, in the context of neural networks spike train statistics: (i) Maximum entropy model with spatio-temporal constraints; (ii) Generalized Linear Models; (iii) Conductance based Inte- grate and Fire model with chemical synapses and gap junctions.Comment: 23 pages, submitte

Hyperharmonic analysis for the study of high-order information-theoretic signals

Network representations often cannot fully account for the structural richness of complex systems spanning multiple levels of organisation. Recently proposed high-order information-theoretic signals are well-suited to capture synergistic phenomena that transcend pairwise interactions; however, the exponential-growth of their cardinality severely hinders their applicability. In this work, we combine methods from harmonic analysis and combinatorial topology to construct efficient representations of high-order information-theoretic signals. The core of our method is the diagonalisation of a discrete version of the Laplace–de Rham operator, that geometrically encodes structural properties of the system. We capitalise on these ideas by developing a complete workflow for the construction of hyperharmonic representations of high-order signals, which is applicable to a wide range of scenarios

¿Pueden los programas de entrenamiento de resistencia con banda elástica mitigar el aumento de peso durante las vacaciones y mejorar la fuerza de agarre de las manos en mujeres mayores?

Este estudio evaluó el efecto del entrenamien- to con ejercicios de resistencia (EER) sobre la composición corpo- ral y la fuerza muscular en 16 mujeres adultas mayores durante las vacaciones de verano (70, 5 ± 8, 4 años; Rango 60-87). Las sesio- nes de ejercicio se llevaron a cabo durante doce semanas, dos ve- ces por semana, con 60 minutos de ejercicio por sesión. Se evaluó el índice de masa corporal (IMC), el porcentaje de masa grasa (% MG, por bioimpedancia) y la fuerza de presión con un dinamómetro manual antes y después de la intervención. Las participantes mos- traron un aumento significativo en el IMC (p< 0, 05), % de MG (p<0, 001) y un incremento significativo en la fuerza prensil (p <0, 05). El programa de EER podría ser una estrategia importante para mejorar la fuerza de mujeres adultas mayores durante el periodo estival. El EER se sugiere combinarlo con otras variables, como ejercicios aeróbicos con intensidad gradualmente creciente y una intervención nutricional, para mantener un peso constante durante los períodos de vacaciones. This study evaluated the effect of resistance exercise training (RET) on body composition and muscle strength in 16 older women during summer holidays (70.5 ± 8.4 years old; Range 60-87). Exercise sessions were carried out for twelve weeks, two sessions per week, with 60 minutes of exercise per session. We measured body mass index (BMI), fat mass percentage (FM%, by bioimpedance) and grip strength with a dynamometer before and after the intervention. The participants showed a significant increase in BMI (p<0.05), FM% (p<0.001), and a significant gain in grip strength (p<0.05). The RET program could be an important strategy for improving strength for older women, but we would suggest combining it with other interventions, such as aerobic exercises with gradually increasing intensity and nutrition interventions, in order to maintain a steady weight during holiday periods

The Clostridium difficile Exosporium Cysteine (CdeC)-Rich Protein Is Required for Exosporium Morphogenesis and Coat Assembly

Clostridium difficile is an important nosocomial pathogen that has become a major cause of antibiotic-associated diarrhea. There is a general consensus that C. difficile spores play an important role in C. difficile pathogenesis, contributing to infection, persistence, and transmission. Evidence has demonstrated that C. difficile spores have an outermost layer, termed the exosporium, that plays some role in adherence to intestinal epithelial cells. Recently, the protein encoded by CD1067 was shown to be present in trypsin-exosporium extracts of C. difficile 630 spores. In this study, we renamed the CD1067 protein Clostridium difficile exosporium cysteine-rich protein (CdeC) and characterized its role in the structure and properties of C. difficile spores. CdeC is expressed under sporulation conditions and localizes to the C. difficile spore. Through the construction of an ΔcdeC isogenic knockout mutant derivative of C. difficile strain R20291, we demonstrated that (i) the distinctive nap layer is largely missing in ΔcdeC spores; (ii) CdeC is localized in the exosporium-like layer and is accessible to IgGs; (iii) Δ cdeC spores were more sensitive to lysozyme, ethanol, and heat treatment than wild-type spores; and (iv) despite the almost complete absence of the exosporium layer, Δ cdeC spores adhered at higher levels than wild-type spores to intestinal epithelium cell lines (i.e., HT-29 and Caco-2 cells). Collectively, these results indicate that CdeC is essential for exosporium morphogenesis and the correct assembly of the spore coat of C. difficile.Keywords: Spore surface, Subtilis, Infection, Germination, Culture, Gene, Caco-2, Bacterial spores, Identification, Bacillus anthracis exosporium

Entry of spores into intestinal epithelial cells contributes to recurrence of Clostridioides difficile infection

Indexación ScopusClostridioides difficile spores produced during infection are important for the recurrence of the disease. Here, we show that C. difficile spores gain entry into the intestinal mucosa via pathways dependent on host fibronectin-α5β1 and vitronectin-αvβ1. The exosporium protein BclA3, on the spore surface, is required for both entry pathways. Deletion of the bclA3 gene in C. difficile, or pharmacological inhibition of endocytosis using nystatin, leads to reduced entry into the intestinal mucosa and reduced recurrence of the disease in a mouse model. Our findings indicate that C. difficile spore entry into the intestinal barrier can contribute to spore persistence and infection recurrence, and suggest potential avenues for new therapies. © 2021, The Author(s).https://www-nature-com.recursosbiblioteca.unab.cl/articles/s41467-021-21355-

Biodiversity of Arbuscular Mycorrhizal Fungi in South America: A Review

Identification of species is crucial in understanding how diversity changes affect ecosystemic processes. Particularly, soil microbial are key factors of ecosystemic functioning .Among soil microbes, arbuscular mycorrhizal fungi (AMF, phylum Glomeromycota) are worldwide distributed and form symbiotic associations with almost 80% of the vascular plants of the earth, except for one species, Geosiphon pyriformis, which associates with the cyanobacteria Nostoc. AMF comprise around 300 morphologically defined or 350–1000 molecularly defined taxa. Since AMF associate with aboveground community, their occurrence and composition can influence ecosystemic processes either through affecting plant community composition and thus its processes rates, or soil microbial communities, which are directly involved in nutrient cycling. Soil microorganisms are considered a potentially suitable target for studying regional and local effects on diversity. The symbiosis with AMF not only increases nutrient uptake by the plant of mainly phosphorus (P) and nitrogen (N) in exchange for plant-assimilated carbon (C), but also improves the tolerance of plants to various biotic and abiotic stresses such as pathogens, salinity, and drought