Carmen Ascaso

Museo Nacional de Ciencias Naturales

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Jacek Wierzchoś

Museo Nacional de Ciencias Naturales

167

Asunción de los Rı́os

Museo Nacional de Ciencias Naturales

101

Virginia Souza‐Egipsy

Instituto de Estructura de la Materia

Sergio Pérez‐Ortega

Real Jardín Botánico

Leopoldo G. Sancho

Universidad Complutense de Madrid

Octavio Artieda

Universidad de Extremadura

M. Oujja

Instituto de Química Física Blas Cabrera

Marta Castillejo

Instituto de Química Física Blas Cabrera

Mikel Sanz

National University of Distance Education

Alfonso F. Dávila

Ames Research Center

Cooperative Institutions

Consejo Superior de Investigaciones Científicas

Universidad Complutense de Madrid

Centro de Astrobiología

Museo Nacional de Ciencias Naturales

Centre National de la Recherche Scientifique

Unidades Centrales Científico-Técnicas

Universidad Autónoma de Madrid

Universitat de Barcelona

Instituto de Geociencias

Instituto Nacional de Técnica Aeroespacial

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Papers

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Evaluation of portable Raman instrumentation for detection of traces of life in rocks ¿ implication for astrobiological prospecting of Mars

Petr Vítek Jan Jehlička Howell G. M. Edwards Ian Hutchinson Carmen Ascaso

Prospecting

Instrumentation

Life on Mars

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Citations (0)

Control de líquenes y microorganismos endolíticos mediante biocidas y láser.

Mariela Speranza Mikel Sanz M. Oujja Asunción de los Rı́os Jacek Wierzchoś

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Physical Interactions of two Rhizomorph‐forming Lichens with their Rock Substrate

Botanica Acta (1994)

William B. Sanders Carmen Ascaso Jacek Wierzchoś

Abstract Samples of a calcareous conglomerate rock colonized by Squamarina cartilaginea and a siliceous schist colonized by Acarospora scotica were cut and examined with SEM‐backscattered electron imaging. Both species produce extensive rhizomorphs ( sensu lato ), whose component hyphae interpenetrated, separated, and incorporated substrate particles in the course of development. Rhizomorph expansion and contraction associated with hydration cycles could also detach adherent fragments within the substrate. In S. cartilaginea , rhizomorphs and associated hyphae also directly penetrated the calcareous substrate matrix, probably by chemical dissolution. Those of A. scotica appeared to penetrate the schist mainly by forcing their way between the fine, angular, somewhat flattened particles which comprises the substrate. The orientation of these particles influenced the form of developing rhizomorphs and the subsequent pattern of substrate exfoliation. Lichen compounds of potential biode‐teriorative significance occurred within the squamules of both species but were not detectable in their rhizomorphs. Lichenized photobionts were abundant within the substrate; their developmental relationship to epilithic squamules could be demonstrated in the case of A. scotica .

Sensu

10.1111/j.1438-8677.1994.tb00818.x

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Citations (36)

Journal of Phycology (1996)

Carlos García‐Ferris Asunción de los Rı́os Carmen Ascaso J. Moreno

ABSTRACT Growth of Euglena gracilis Z Pringsheim under photoheterotrophic conditions in a nitrogen‐deprived medium resulted in progressive loss of chloroplastic material until total bleaching of the cells occurred. Biochemical analysis and ultrastructural observation of the first stages of the starvation process demonstrated an early lag phase (from 0 to 9 h) in which cells increased in size, followed by a period of cell division, apparently supported by the mobilization of some chloroplastic proteins such as the photosynthetic CO 2 ‐fixing enzyme ribulose‐1,5‐bisphosphate carboxylase/oxygenase. The degradation of the enzyme started after 9 h of starvation and was preceded by a transient concentration of this protein in pyrenoidal structures. Protein nitrogen and photosynthetic pigments as well as number of chloroplasts per cell decreased during proliferation through mere distribution among daughter cells. However, after 24 h, when cell division had almost ceased, there was a slow but steady decline of photosynthetic pigments. This was paralleled by observable ultrastructural changes including progressive loss of chloroplast structure and accumulation of paramylon granules and lipid globules in the cytoplasm. These findings reinforce the role of chloroplastic materials as a nitrogen source during starvation of E. gracilis in a carbon‐rich medium. The excess of ribulose‐1,5‐bisphosphate carboxylase/oxygenase acts as a first reservoir that, once exhausted, is superseded by the generalized disassembly of the photosynthetic structures, if the adverse environment persists more than 24 h.

Euglena gracilis

Ribulose

Euglena

Ribulose 1,5-bisphosphate

10.1111/j.0022-3646.1996.00953.x

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Citations (44)

Influence of wavelength on the laser removal of lichens colonizing heritage stone

Applied Surface Science (2016)

Mikel Sanz M. Oujja Carmen Ascaso Sergio Pérez‐Ortega Virginia Souza‐Egipsy

Thallus

Crustose

10.1016/j.apsusc.2016.12.032

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Citations (30)

In situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert

Frontiers in Microbiology (2015)

Alfonso F. Dávila Ian Hawes Jonathan Araya Diego R. Gelsinger Jocelyne DiRuggiero

The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlled laboratory experiments, we show that this endolithic community is capable of carbon fixation both through oxygenic photosynthesis and potentially ammonia oxidation. We also present evidence that photosynthetic activity is finely tuned to moisture availability and solar insolation and can be sustained for days, and perhaps longer, after a wetting event. This is the first demonstration of in situ active metabolism in the hyperarid core of the Atacama Desert, and it provides the basis for proposing a self-contained, endolithic community that relies exclusively on non-rainfall sources of water. Our results contribute to an increasing body of evidence that even in hyperarid environments active metabolism, adaptation, and growth can occur in highly specialized microhabitats.

Halite

Desert climate

Microbial mat

Limnology

10.3389/fmicb.2015.01035

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Citations (42)

Subcellular Localization of the Major Pneumococcal Autolysin: A Peculiar Mechanism of Secretion in Escherichia coli

Journal of Biological Chemistry (1989)

Eduardo Dı́az Ernesto Garcı́a Carmen Ascaso Eduardo Méndez R. López

The major pneumococcal autolysin (N-acetylmuramoyl-L-alanine amidase) has been localized in the cellular envelope of Streptococcus pneumoniae and Escherichia coli by using immunocytochemical labeling on ultrathin sections and whole-mounted cells.Cell fractionation experiments in E. coli confirmed the peripheral localization of the pneumococcal amidase and suggested that this enzyme is weakly bound to the outer face of the cytoplasmic membrane.This interaction does not depend on the presence of choline but represents an intrinsic property of the amidase.The autolysin, that is synthesized without any N-terminal signal sequence (Garcia, P., Garcia, J. L., Garcia, E., and Lopez, R. (1986) Gene (Amst.)43, 265-272) was not processed during translocation.A new regulatory mechanism that might be specific for bacterial autolysins is discussed.

Autolysin

10.1016/s0021-9258(19)85077-9

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Citations (50)

Innovative approaches to accurately assess the effectiveness of biocide-based treatments to fight biodeterioration of Cultural Heritage monuments

The Science of The Total Environment (2023)

Mar Villar‐dePablo Carmen Ascaso Esther Rodríguez-Pérez M. Urizal Jacek Wierzchoś

The development of diagnostic methods to accurately assess the effects of treatments on lithobiont colonization remains a challenge for the conservation of Cultural Heritage monuments. In this study, we tested the efficacy of biocide-based treatments on microbial colonization of a dolostone quarry, in the short and long-term, using a dual analytical strategy. We applied a metabarcoding approach to characterize fungal and bacterial communities over time, integrated with microscopy techniques to analyze the interactions of microorganisms with the substrate and evaluate the effectiveness. These communities were dominated by the bacterial phyla Actinobacteriota, Proteobacteria and Cyanobacteria, and the fungal order Verrucariales, which include taxa previously reported as biodeteriogenic agents and observed here associated with biodeterioration processes. Following the treatments, changes over time in the abundance profiles depend on taxa. While Cyanobacteriales, Cytophagales and Verrucariales decreased in abundance, other groups, such as Solirubrobacteriales, Thermomicrobiales and Pleosporales increased. These patterns could be related not only to the specific effects of the biocide on the different taxa, but also to different recolonization abilities of those organisms. The different susceptibility to treatments could be associated with the inherent cellular properties of different taxa, but differences in biocide penetration to endolithic microhabitats could be involved. Our results demonstrate the importance of both removing epilithic colonization and applying biocides to act against endolithic forms. Recolonization processes could also explain some of the taxon-dependent responses, especially in the long-term. Taxa showing resistance, and those benefiting from nutrient accumulation in the form of cellular debris following treatments, may have an advantage in colonizing treated areas, pointing to the need for long-term monitoring of a wide range of taxa. This study highlights the potential utility of combining metabarcoding and microscopy to analyze the effects of treatments and design appropriate strategies to combat biodeterioration and establish preventive conservation protocols.

Biocide

10.1016/j.scitotenv.2023.165318

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Citations (7)

Study of lichens with different state of hydration by the combination of low temperature scanning electron and confocal laser scanning microscopies.

PubMed (1999)

Asunción de los Rı́os Carmen Ascaso Jacek Wierzchoś

Pyrenoid

Thallus

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Citations (25)

Influence of wavelength on the laser removal of lichens colonizing heritage stone-Associated dataset

Zenodo (CERN European Organization for Nuclear Research) (2019)

Mikel Sanz M. Oujja Carmen Ascaso Sergio Pérez‐Ortega Virginia Souza‐Egipsy

A number of techniques were employed to detect morphological and chemical changes on the irradiated surfaces. Stereomicroscopy was used to describe morphological and colour changes. Scanning electron microscopy (SEM) at low vacuum served to analyse the effects on the surface of the lichens, while SEM-BSE of the polished transversal cross sections was applied to assess effects inside the crust and in the lithic substrate. FT-Raman spectroscopy was employed to detect possible structural and chemical changes.

10.5281/zenodo.3531701

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Citations (0)