1,721,073 research outputs found
Desert cyanobacteria under space and planetary simulations: a tool for searching for life beyond Earth and supporting human space exploration
No full text
Subcellular integrities in Chroococcidiopsis sp. CCMEE 029 survivors after prolonged desiccation revealed by molecular probes and genome stability assays
No full textDesiccation-tolerant cells must either protect their cellular components from desiccation-induced damage and/or repair it upon rewetting. Subcellular damage to the anhydrobiotic cyanobacterium Chroococcidiopsis sp. CCMEE 029 stored in the desiccated state for 4 years was evaluated at the single-cell level using fluorescent DNA strand breakage labelling, membrane integrity and potential related molecular probes, oxidant-sensing fluorochrome and redox dye. Covalent modifications of dried genomes were assessed by testing their suitability as PCR template. Results suggest that desiccation survivors avoid/and or limit genome fragmentation and genome covalent modifications, preserve intact plasma membranes and phycobiliprotein autofluorescence, exhibit spatially-reduced ROS accumulation and dehydrogenase activity upon rewetting. Damaged cells undergo genome fragmentation, loss of plasma membrane potential and integrity, phycobiliprotein bleaching, whole-cell ROS accumulation and lack respiratory activity upon rewetting. The co-occurrence of live and dead cells within dried aggregates of Chroococcidiopsis confirms that desiccation resistance is not a simple process and that subtle modifications to the cellular milieu are required to dry without dying. It rises also intriguing questions about the triggers of dead cells in response to drying. The capability of desiccation survivors to avoid and/or reduce subcellular damage, shows that protection mechanisms are relevant in the desiccation tolerance of this cyanobacterium
Challenging the Survival Thresholds of a Desert Cyanobacterium under Laboratory Simulated and Space Conditions
No full textKnowledge of the limit of life’s adaptability to extreme environments is essential for identifying potentially habitable niches in planets and moons in our Solar System or in planetary systems around other stars. Dryness is one of the main life-threatening factors since water removal causes membrane phase transition and production of reactive oxygen species that cause lipid peroxidation, protein oxidation and DNA damage, which are lethal to most organisms. Anhydrobiotic cyanobacteria of the genus Chroococcidiopsis possess a remarkable resistance to desiccation and radiation; as such they have extended the limits of life as we know it in several new directions. Investigating the threshold of such resistance can help us in understanding not only the limits of life on Earth but also in assessing the potential habitability of Mars, of icy moons, and of exoplanets characterized by high doses of radiation and transient availability of liquid water. New insights have been provided by experiments exposing cyanobacteria to laboratory simulations that mimic planetary conditions, and also to real space conditions
Plasmid stability in dried cells of the desert cyanobacterium Chroococcidiopsis and its potential for GFP imaging of survivors on Earth and in space.
No full textLoss of topological relationships in a Pleurocapsalean cyanobacterium (Chroococcidiopsis sp.) with partially inactivated ftsZ
No full textWhen inactivation of the cell division gene ftsZ was attempted in the Pleurocapsalean cyanobacterium Chroococcidiopsis CCMEE 029 via homologous recombination by using a both-ends truncated ftsZ fragment cloned into the suicide mobilizable plasmid pRL271, the scored transconjugants invariably died upon restreaking. The integration of plasmid pRL271-FZ into the transconjugants genome by single crossover events, leading to the generation of two mutated copies of ftsZ, characterized by whole plasmid in-between, was assessed by colony PCR. Heteroplasmic ftsZ mutants occurred mostly as cell aggregations, lacking the regularity of successive division planes. Their aberrant topology was resolved by electron transmission microscopy as resulting from the irregular clustering of distinct aggregates. These results suggested that FtsZ is essential in this cyanobacterium able of binary and multiple division and that its partial inactivation results in an impaired coordination in time and space of successive divisions undertaken by single cells
Genetic tools for desiccation, radiation-tolerant cyanobacteria of the genus Chroococcidiopsis
No full textCyanobacteria living in arid environments represent an unexplored source of novel and/or particularly efficient molecules which underlie survival of high radiation, prolonged desiccation and extreme temperatures. Members of the genus Chroococcidiopsis are often the only photosynthetic prokaryotes in extremely dry deserts such as the Dry Valleys in Antarctica and the Atacama Desert in Chile. Furthermore they can cope with stressors not so far encountered in nature, e.g. high doses of UV and ionizing radiation. Genetic tools are available for desert strains of the Chroococcidiopsis, including gene transfer and gene inactivation. Plasmids maintained in these cyanobacteria have been developed which make it possible to monitor gene expression and in vivo localization of proteins. The use of these genetic tools in combination with the foreseen availability of genomic sequences will contribute to unravelling the molecular basis of Chroococcidiopsis desiccation and radiation tolerance as well as its biotechnological exploitation
Anhydrobiotic rock-inhabiting cyanobacteria: potential for astrobiology and biotechnology
No full textMicrobial colonization of the salt deposits in the driest place of the Atacama Desert (Chile)
No full textThe Atacama Desert (Chile), one of the most arid places on Earth, shows hostile
conditions for the development of epilithic microbial communities. In this study, we report
the association of cyanobacteria (Chroococcidiopsis sp.) and bacteria belonging to
Actinobacteria and Beta-Gammaproteobacteria and Firmicutes phyla inhabiting the near
surface of salt (halite) deposits of the Salar Grande Basin, Atacama Desert (Chile). The halite
deposits were investigated by using optical, confocal and field emission scanning electron
microscopes, whereas culture-independent molecular techniques, 16S rDNA clone library,
alongside RFLP analysis and 16S rRNA gene sequencing were applied to investigate the
bacterial diversity. These microbial communities are an example of life that has adapted to
extreme environmental conditions caused by dryness, high irradiation, and metal concentrations.
Their adaptation is, therefore, important in the investigation of the environmental
conditions that might be expected for life outside of Earth
BOSS CYANO EXPERIMENT ON THE EXPOSE-R2 SPACE MISSION: ENHANCED SURVIVAL OF CHROOCOCCIDIOPSIS BIOFILMS TO SPACE AND SIMULATED MARS CONDITIONS COMPARED TO PLANKTONIC COUNTERPARTS
Full text linkThe Biofilm Organisms Surfing Space (BOSS) experiment is part of the EXPOSE-R2 space mission.
In one part of the BOSS experiment three Chroococcidiopsis desert stains (CCMEE 057, CCMEE 029
and CCMEE 064), were exposed to Low Earth Orbit (LEO) in the dried state either as biofilms or
multilayered planktonic samples. Cells were exposed for 16 months to space and Mars-like conditions
outside the International Space Station. Exposure parameters included temperature variations, ionizing
radiation, vacuum or simulated Martian atmosphere and pressure, and Mars-like solar UV irradiation. In
parallel to exposure in LEO, replicates of the experiment were performed on the ground: Some were kept
in the dark under ambient conditions, while others were exposed to stressors (extreme temperature cycles,
Mars-simulated atmosphere or vacuum, and UV
ux) mimicking those undergone during the EXPOSE-R2
space mission, based on data recorded in-
ight. Cyanobacteria were analyzed post-
ight using confocal
microscopy, PCR-based assays and colony forming ability tests. Results are consistent with previous
ground-based simulations of the mission1,2 and demonstrate an overall higher resistance of biofilms when
compared to planktonic as suggested by their increased viability and lower amounts of DNA damage.
1. Baqué, M., Scalzi, G., Rabbow, E., Rettberg, P. Billi, D. Biofilm and Planktonic Lifestyles
Differently Support the Resistance of the Desert Cyanobacterium Chroococcidiopsis Under Space and
Martian Simulations. Orig. life Evol. Biosph. 43, 377-389 (2013).
2. Baqué, M., de Vera, J.-P., Rettberg, P. Billi, D. The BOSS and BIOMEX space experiments on the
EXPOSE-R2 mission: Endurance of the desert cyanobacterium Chroococcidiopsis under simulated space
vacuum, Martian atmosphere, UVC radiation and temperature extremes. Acta Astronaut. 91, 180-186
(2013)
- …
