Person:
Sánchez Jiménez, Abel

First Name

Abel

Last Name

Sánchez Jiménez

URI

https://hdl.handle.net/20.500.14352/74359

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Biológicas

Department

Biodiversidad, Ecología y Evolución

Area

Matemática Aplicada

Identifiers

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Search Results

Now showing 1 - 10 of 13

Phytoestrogen Metabolism by Adult Human Gut Microbiota
(Molecules, 2016) Gaya, Pilar; Medina, Margarita; Sánchez Jiménez, Abel; Landete, José María
Phytoestrogens are plant-derived polyphenols with a structure similar to human estrogens. The three main groups of phytoestrogens, isoflavones, ellagitannins, and lignans, are transformed into equol, urolithins, and enterolignans, respectively, by bacteria. These metabolites have more estrogenic/antiestrogenic and antioxidant activities than their precursors, and they are more bioavailable. The aim of this study was to analyze the metabolism of isoflavones, lignans and ellagitannins by gut microbiota, and to study the possible correlation in the metabolism of these three groups of phytoestrogens. In vitro fermentation experiments were performed with feces samples from 14 healthy adult volunteers, and metabolite formation was measured by HPLC-PAD and HPLC-ESI/MS. Only the microbiota of one subject produced equol, while most of them showed production of O-desmethylangolensin (O-DMA). Significant inter-subject differences were observed in the metabolism of dihydrodaidzein and dihydrogenistein, while the glucoside isoflavones and their aglycones showed less variability, except for glycitin. Most subjects produced urolithins M-5 and E. Urolithin D was not detected, while uroltithin B was found in half of the individuals analyzed, and urolithins A and C were detected in two and four subjects, respectively. Enterolactone was found in all subjects, while enterodiol only appeared in five. Isoflavone metabolism could be correlated with the metabolism of lignans and ellagitannins. However, the metabolism of ellagitannins and lignans could not be correlated. This the first study where the metabolism of the three groups together of phytoestrogen, isoflavones, lignans, and ellagitannins by gut microbiota is analyzed.
Complexity of river ciliate communities at a national park highlights the need for microbial conservation
(Aquatic Conservation: Marine and Freshwater Ecosystems, 2018) Quintela Alonso, Pablo; Pérez‐Uz, Blanca; Sánchez Jiménez, Abel; Murciano Cespedosa, Antonio; Centeno, Juan D.; García-Rodríguez, Manuel; Montero, Esperanza; Muñoz Araújo, Benito; Olmedo Salinas, Cristina; Refoyo Román, Pablo; Velasco González, Ismael; Martín Cereceda, María Mercedes
1.Microorganisms play pivotal roles in aquatic ecosystems. Free‐living protists are the main components of the eukaryotic microbial communities at the base of freshwater ecosystems. Ciliate grazing channels a large proportion of organic matter into multicellular organisms. Surprisingly, ciliates and other microorganisms are neglected in global conservation schemes. 2. Interstitial ciliates were sampled in three sites of varying human pressure on the River Manzanares (La Pedriza National Park, Spain). Abundances of trophic groups and species were adjusted to a generalized linear model (GLM Poisson regression). 3.Ciliate communities were rich in species (74 morphotypes) and although traditional microscopy retrieved a high number of species that appeared only once or in low numbers, rarefaction analyses estimated much larger species richness. These results illustrate that rarefaction assays are a useful first step for exploring the extent of the ciliate cryptic diversity in freshwater ecosystems. 4.Benthic ciliate communities changed significantly, both spatially and at a short temporal scale. The fluctuating nature of the community was manifested by the presence of many ephemeral species at the same river site, revealing a complex and transient community structure. No significant short‐term changes were observed in the physical–chemical properties. Therefore, even slight differences in the abiotic variables may cause rapid shifts of ciliate species. 5.Overall, human pressure had an effect on the interstitial (or benthic) ciliates that resulted in a reduction of species richness and their abundance.
Influencia de la temperatura sobre la asimetría de pilancones en ambiente granítico. Aplicación de un modelo de regresión lineal
(Boletín de la Sociedad Geológica Mexicana, 2017) García Rodríguez, Manuel; Sánchez Jiménez, Abel; Murciano Cespedosa, Antonio; Pérez Uz, María Blanca; Martín Cereceda, María Mercedes
Las pilas representan un tipo de forma presente en casi todos los ambientes climáticos. El trabajo estudia el papel de los ciclos térmicos como un agente importante del modelado y asimetría que presentan las paredes de las pilas en un clima Mediterrá- neo templado - frío. El estudio se ha realizado en el macizo granítico de la Pedriza de Manzanares, zona protegida de gran valor ambiental, incluida en el Parque Nacional de la Sierra de Guadarrama (Madrid, España). El análisis de la variabilidad térmica mediante modelos de regresión perió- dica múltiple, pone de manifiesto la influencia de los ciclos diario y anual en función de las orientaciones norte y sur de las paredes de las pilas. Un modelo matemático de regresión lineal muestra cómo la variabilidad térmica diaria influye en la alteración de las paredes de las pilas, generando superficies planas o de concavidad más o menos pronunciada. El trabajo también establece relaciones entre el grado de alteración de las diferentes partes de las pilas, con la presencia de líquenes y dureza relativa de la roca. Los resultados avalan la hipótesis de relación causal entre la variabilidad térmica y alteración de las paredes de las pilas según su orientación norte o sur.
Rain-Fed Granite Rock Basins Accumulate a High Diversity of Dormant Microbial Eukaryotes
(Microbial Ecology, 2019) Velasco González, Ismael; Sánchez Jiménez, Abel; Singer, David; Murciano Cespedosa, Antonio; Díez-Hermano, Sergio; Lara, Enrique; Martín-Cereceda, Mercedes
Rain fed granite rock basins are ancient geological landforms of worldwide distribution and structural simplicity. They support habitats that can switch quickly from terrestrial to aquatic along the year. Diversity of animals and plants, and the connexion between communities in different basins have been widely explored in these habitats, but hardly any research has been carried out on microorganisms. The aim of this study is to provide the first insights on the diversity of eukaryotic microbial communities from these environments. Due to the ephemeral nature of these aquatic environments, we predict that the granitic basins should host a high proportion of dormant microeukaryotes. Based on an environmental DNA diversity survey, we reveal diverse communities with representatives of all major eukaryotic taxonomic supergroups, mainly composed of a diverse pool of low abundance OTUs. Basin communities were very distinctive, with alpha and beta diversity patterns non-related to basin size or spatial distance respectively. Dissimilarity between basins was mainly characterised by turnover of OTUs. The strong microbial eukaryotic heterogeneity observed among the basins may be explained by a complex combination of deterministic factors (diverging environment in the basins), spatial constraints, and randomness including founder effects. Most interestingly, communities contain organisms that cannot coexist at the same time because of incompatible metabolic requirements, thus suggesting the existence of a pool of dormant organisms whose activity varies along with the changing environment. These organisms accumulate in the pools, which turns granitic rock into high biodiversity microbial islands whose conservation and study deserve further attention.
Cognitive Neural Network Driving DoF-Scalable Limbs in Time-Evolving Situations
(2018) Calvo Tapia, Carlos; Villacorta Atienza, José Antonio; Kastalskiy, Innokentiy; Díez Hermano, Sergio; Sánchez Jiménez, Abel; Makarov Slizneva, Valeriy
Object handling and manipulation are vital skills for humans and autonomous humanoid robots. The fundamental bases of how our brain solves such tasks remain largely unknown. Here we develop a novel approach that addresses the problem of limb movements in time-evolving situations at an abstract cognitive level. We exploit the concept of generalized cognitive maps constructed in the so-called handspace by a neural network simulating a wave simultaneously exploring different subject actions independently on the number of objects in the workspace. We show that the approach is scalable to limbs with minimalistic and redundant numbers of degrees of freedom (DoF). It also allows biasing the effort of reaching a target among different DoF.
Effects of spike anticipation on the spiking dynamics of neural networks
(Frontiers in Computational Neuroscience, 2015) Santos Sierra, Daniel de; Sánchez Jiménez, Abel; García-Vellisca, A.; Navas, Adrian; Villacorta Atienza, Jose A.
Synchronization is one of the central phenomena involved in information processing in living systems. It is known that the nervous system requires the coordinated activity of both local and distant neural populations. Such an interplay allows to merge different information modalities in a whole processing supporting high-level mental skills as understanding, memory, abstraction, etc. Though, the biological processes underlying synchronization in the brain are not fully understood there have been reported a variety of mechanisms supporting different types of synchronization both at theoretical and experimental level. One of the more intriguing of these phenomena is the anticipating synchronization, which has been recently reported in a pair of unidirectionally coupled artificial neurons under simple conditions (Pyragiene and Pyragas, 2013), where the slave neuron is able to anticipate in time the behavior of the master one. In this paper, we explore the effect of spike anticipation over the information processing performed by a neural network at functional and structural level. We show that the introduction of intermediary neurons in the network enhances spike anticipation and analyse how these variations in spike anticipation can significantly change the firing regime of the neural network according to its functional and structural properties. In addition we show that the interspike interval (ISI), one of the main features of the neural response associated with the information coding, can be closely related to spike anticipation by each spike, and how synaptic plasticity can be modulated through that relationship. This study has been performed through numerical simulation of a coupled system of Hindmarsh–Rose neurons.
Germination fitness of two temperate epiphytic ferns shifts under increasing temperatures and forest fragmentation
(PLoS ONE, 2018) Gabriel Y Galán Moris, José María; Murciano Cespedosa, Antonio; Sirvent, Laure; Sánchez Jiménez, Abel; Watkins, James E.
Ferns are an important component of ecosystems around the world. Studies of the impacts that global changes may have on ferns are scarce, yet emerging studies indicate that some species may be particularly sensitive to climate change. The lack of research in this subject is much more aggravated in the case of epiphytes, and especially those that live under temperate climates. A mathematical model was developed for two temperate epiphytic ferns in order to predict potential impacts on spore germination kinetics, in response to different scenarios of global change, coming from increasing temperature and forest fragmentation. Our results show that an increasing temperature will have a negative impact over the populations of these temperate epiphytic ferns. Under unfragmented forests the germination percentage was comparatively less influenced than in fragmented patches. This study highlight that, in the long term, populations of the studied epiphytic temperate ferns may decline due to climate change. Overall, epiphytic fern communities will suffer changes in diversity, richness and dominance. Our study draws attention to the role of ferns in epiphytic communities of temperate forests, emphasizing the importance of considering these plants in any conservation strategy, specifically forest conservation. From a methodological point of view, the model we propose could be easily used to dynamically monitor the status of ecosystems, allowing the quick prediction of possible future scenarios, which is a crucial issue in biodiversity conservation decision-making.
Data from: Germination fitness of two temperate epiphytic ferns shifts under increasing temperatures and forest fragmentation
(2018) Gabriel y Galán, Jose María; Murciano Cespedosa, Antonio; Sirvent, Laure; Sánchez Jiménez, Abel; Watkins, James E.
Ferns are an important component of ecosystems around the world. Studies of the impacts that global changes may have on ferns are scarce, yet emerging studies indicate that some species may be particularly sensitive to climate change. The lack of research in this subject is much more aggravated in the case of epiphytes, and especially those that live under temperate climates. A mathematical model was developed for two temperate epiphytic ferns in order to predict potential impacts on spore germination kinetics, in response to different scenarios of global change, coming from increasing temperature and forest fragmentation. Our results show that an increasing temperature will have a negative impact over the populations of these temperate epiphytic ferns. Under unfragmented forests the germination percentage was comparatively less influenced than in fragmented patches. This study highlight that, in the long term, populations of the studied epiphytic temperate ferns may decline due to climate change. Overall, epiphytic fern communities will suffer changes in diversity, richness and dominance. Our study draws attention to the role of ferns in epiphytic communities of temperate forests, emphasizing the importance of considering these plants in any conservation strategy. Derived from our results, it seems that it would be more practical to focus attention to forest conservation. From a methodological point of view, the model we propose could be easily used to dynamically monitor the status of ecosystems, allowing the quick prediction of possible future scenarios, which is a crucial issue in biodiversity conservation decision-making.
Analysis of gene expression of bifidobacteria using as the reporter an anaerobic fluorescent protein
(Biotechnology Letters, 2015) Montenegro-Rodríguez, Cynthia; Peirotén, Angela; Sánchez Jiménez, Abel; Arqués Orobón, Juan Luis; Landete, José María
To determine the effectiveness of evoglow-Pp1 as a reporter to study gene expression in bifidobacteria. To choose a strong and constitutive promoter to track fluorescently labelled bifidobacteria in environments under anaerobic conditions. Results The elongation factor P (EF-P) promoter from Bifidobacterium longum CECT 4551 produced the highest emission of fluorescence signal and was therefore able to produce the highest gene expression of the promoters studied. The promoters from B. longum CECT 4551 showed different fluorescence signal intensities which, in descending order, were: EF-P, initiation factor IF-2, elongation factor G, elongation factor Tu, elongation factor Nus A, elongation factor Ts and 30S ribosomal protein S12. Conclusions The consistency of the methods employed (fluorescence imaging system, fluorescence microscopy, fluorimetry and flow cytometry) showed that the construction pNZ:Prom.GFPana contained the anaerobic fluorescent protein evoglow-Pp1 could be exploited as a tool for analysing the gene expression in bifidobacteria strains.
Codificación de la información dependiente de la frecuencia en las neuronas asociadas a vibrisas del complejo sensorial del trigémino de la rata
(2015) Sánchez Jiménez, Abel; Panetos Petrova, Fivos; Pérez de Vargas Luque, Alberto