Microbial colonization of halite from the hyper-arid Atacama Desert studied by Raman spectroscopy

17 páginas, ilustraciones y tablas estadísticas.The hyper-arid core of the Atacama Desert (Chile) is the driest place on Earth and is considered a close analogue to the extremely arid conditions on the surface of Mars. Microbial life is very rare in soils of this hyper-arid region, and autotrophic microorganisms are virtually absent. Instead, photosynthetic micro-organisms have successfully colonized the interior of halite crusts, which are widespread in the Atacama Desert. These endoevaporitic colonies are an example of life that has adapted to the extreme dryness by colonizing the interior of rocks that provide enhanced moisture conditions. As such, these colonies represent a novel example of potential life on Mars. Here, we present non-destructive Raman spectroscopical identification of these colonies and their organic remnants. Spectral signatures revealed the presence of UV-protective biomolecules as well as light-harvesting pigments pointing to photosynthetic activity. Compounds of biogenic origin identified within these rocks differed depending on the origins of specimens from particular areas in the desert, with differing environmental conditions. Our results also demonstrate the capability of Raman spectroscopy to identify biomarkers within rocks that have a strong astrobiological potential.Grant Agency of Charles University in Prague, grant no. 83007, and by grant MSM0021620855 from the Ministry of Education of the Czech Republic. This work was also supported by grants CGL2006-04658 and CGL2007-62875/BOS from the Ministry of Science and Innovation and grant PIE-631A from the CSIC (Spanish Research Council).Peer reviewe

Chains of magnetite crystals in the meteorite ALH84001: Evidence of biological origin

The presence of magnetite crystal chains, considered missing evidence for the biological origin of magnetite in ALH84001 [Thomas-Keprta, K. L., Bazylinski, D. A., Kirschvink, J. L., Clemett, S. J., McKay, D. S., Wentworth, S. J., Vali, H., Gibson, E. K., Jr., & Romanek, C. S. (2000) Geochim. Cosmochim. Acta 64, 4049–4081], is demonstrated by high-power stereo backscattered scanning electron microscopy. Five characteristics of such chains (uniform crystal size and shape within chains, gaps between crystals, orientation of elongated crystals along the chain axis, flexibility of chains, and a halo that is a possible remnant of a membrane around chains), observed or inferred to be present in magnetotactic bacteria but incompatible with a nonbiological origin, are shown to be present. Although it is unlikely that magnetotactic bacteria were ever alive in ALH84001, decomposed remains of such organisms could have been deposited in cracks in the rock while it was still on the surface on Mars

Búsqueda de tratamientos eficaces para evitar el biodeterioro del Patrimonio Cultural construido en piedra

Las Jornadas tuvieron lugar los días 9 y 10 de marzo de 2022 en el Salón de Actos Museo Nacional de Ciencias Naturales y fueron organizadas en homenaje a Rafael Araujo Armero (1960-2021).Los procesos de biodeterioro ponen en riesgo nuestro Patrimonio Cultural y pueden llegar a suponer pérdidas de incalculable valor histórico-artístico, pero también económico. Su diagnóstico, así como el desarrollo de estrategias de tratamiento eficaces para evitar o disminuir sus efectos, sigue siendo a día de hoy un reto. Los tratamientos que se aplican en intervenciones realizadas en construcciones singulares o en obras de restauración, implican generalmente la combinación de tratamientos físicos (limpieza mecánica), junto con tratamientos químicos basados principalmente en el uso de biocidas. Sin embargo, los primeros pueden afectar a la conservación del patrimonio tratado y los segundos al medioambiente. El objetivo de este proyecto es la búsqueda de protocolos de tratamiento eficaces para evitar y frenar procesos de biodeterioro pero que, además, conlleven un mínimo riesgo patrimonial y medioambiental. Para ello, hemos puesto en marcha un experimento en las canteras de Redueña (Madrid), en el que se testan diferentes tratamientos donde se evaluará su eficacia a través de la combinación de microscopía electrónica y metabarcoding. En los ensayos se combinan: 1) pre-tratamientos con y sin limpieza mecánica con un desinfectante y 2) aplicación de distintos biocidas de nueva generación de protección en película de la Empresa Thor Especialidad S.A. La observación de las parcelas tratadas muestra que las combinaciones que implican tratamientos de limpieza mecánica son más efectivos independientemente del biocida utilizado y que el efecto de los biocidas se mantiene al menos después de un año. Esperamos que los análisis en curso nos permitan valorar los efectos específicos sobre distintos taxones y el grado de recolonización a lo largo del tiempo de ensayo

Early evolution and ecology of camouflage in insects

Taxa within diverse lineages select and transport exogenous materials for the purposes of camouflage. This adaptive behavior also occurs in insects, most famously in green lacewing larvae who nestle the trash among setigerous cuticular processes, known as trash-carrying, rendering them nearly undetectable to predators and prey, as well as forming a defensive shield. We report an exceptional discovery of a green lacewing larva in Early Cretaceous amber from Spain with specialized cuticular processes forming a dorsal basket that carry a dense trash packet. The trash packet is composed of trichomes of gleicheniacean ferns, which highlight the presence of wildfires in this early forest ecosystem. This discovery provides direct evidence of an early acquisition of a sophisticated behavioral suite in stasis for over 110 million years and an ancient plant–insect interaction

Establishing Earth's Minimoon Population through Characterization of Asteroid 2020 CD3

We report on our detailed characterization of Earth's second known temporary natural satellite, or minimoon, asteroid 2020 CD3. An artificial origin can be ruled out based on its area-to-mass ratio and broadband photometry, which suggest that it is a silicate asteroid belonging to the S or V complex in asteroid taxonomy. The discovery of 2020 CD3 allows for the first time a comparison between known minimoons and theoretical models of their expected physical and dynamical properties. The estimated diameter of 1.2(-0.2)(+0.4) m and geocentric capture approximately a decade after the first known minimoon, 2006.RH120, are in agreement with theoretical predictions. The capture duration of 2020 CD3 of at least 2.7 yr is unexpectedly long compared to the simulation average, but it is in agreement with simulated minimoons that have close lunar encounters, providing additional support for the orbital models. 2020 CD3's atypical rotation period, significantly longer than theoretical predictions, suggests that our understanding of meter-scale asteroids needs revision. More discoveries and a detailed characterization of the population can be expected with the forthcoming Vera C. Rubin Observatory Legacy Survey of Space and Time.Peer reviewe

Recurrent Cometary Activity in Near-Earth Object (3552) Don Quixote

International audienceWe report on observations of activity in near-Earth object (3552) Don Quixote using the Spitzer Space Telescope and ground-based telescopes around its 2018 perihelion passage. Spitzer observations obtained six months before perihelion show extended emission around the target's nucleus that is most likely caused by molecular band emission from either CO2 or CO, but we find no significant emission from dust. Ground-based optical observations taken close to perihelion reveal for the first time activity in the optical wavelengths, which we attribute to solar light reflected from dust particles. IRAM millimeter radio observations taken around the same time are unable to rule out CO as the driver of the molecular band emission observed with Spitzer. The comparison of the gas activity presented here with observations performed during Don Quixote's previous apparition suggests that activity in Don Quixote is recurrent. We conclude that (3552) Don Quixote is most likely a weakly active comet

Haloterrigena sp. Strain SGH1, a Bacterioruberin-Rich, Perchlorate-Tolerant Halophilic Archaeon Isolated From Halite Microbial Communities, Atacama Desert, Chile

An extreme halophilic archaeon, strain SGH1, is a novel microorganism isolated from endolithic microbial communities colonizing halites at Salar Grande, Atacama Desert, in northern Chile. Our study provides structural, biochemical, genomic, and physiological information on this new isolate living at the edge of the physical and chemical extremes at the Atacama Desert. SGH1 is a Gram-negative, red-pigmented, non-motile unicellular coccoid organism. Under the transmission electron microscope, strain SGH1 showed an abundant electro-dense material surrounding electron-lucent globular structures resembling gas vacuoles. Strain SGH1 showed a 16S rRNA gene sequence with a close phylogenetic relationship to the extreme halophilic archaea Haloterrigena turkmenica and Haloterrigena salina and has been denominated Haloterrigena sp. strain SGH1. Strain SGH1 grew at 20–40°C (optimum 37°C), at salinities between 15 and 30% (w/v) NaCl (optimum 25%) and growth was improved by addition of 50 mM KCl and 0.5% w/v casamino acids. Growth was severely restricted at salinities below 15% NaCl and cell lysis is avoided at a minimal 10% NaCl. Maximal concentrations of magnesium chloride and sodium or magnesium perchlorates that supported SGH1 growth were 0.5 and 0.15M, respectively. Haloterrigena sp. strain SGH1 accumulates bacterioruberin (BR), a C xanthophyll, as the major carotenoid. Total carotenoids in strain SGH1 amounted to nearly 400 μg BR per gram of dry biomass. Nearly 80% of total carotenoids accumulated as geometric isomers of BR: all-trans-BR (50%), 5-cis-BR (15%), 9-cis-BR (10%), 13-cis-BR (4%); other carotenoids were dehydrated derivatives of BR. Carotenogenesis in SGH1 was a reversible and salt-dependent process; transferring BR-rich cells grown in 25% (w/v) NaCl to 15% (w/v) NaCl medium resulted in depigmentation, and BR content was recovered after transference and growth of unpigmented cells to high salinity medium. Methanol extracts and purified BR isomers showed an 8–9-fold higher antioxidant activity than Trolox or β-carotene. Both, plasma membrane integrity and mitochondrial membrane potential measurements under acute 18-h assays showed that purified BR isomers were non-toxic to cultured human THP-1 cells.This work was supported by Grant CeBiB FB-0001, Comisión Nacional de Investigación Científica y Tecnológica (CONICYT), Chile, Semillero de Investigación, Grant SI-5305 by Universidad de Antofagasta, Chile, and Grant PGC2018-094076-B-I00 from Ministry of Science, Innovation and Universities (MCIU/AEI) (Spain) and FEDER (UE) to JW and CA. We acknowledge the support given by grant FONDEQUIP EQM-120137.With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI