Cyanobacteria are gaining considerable interest as a method of supporting the long-term presence of humans on the Moon and settlements on Mars due to their ability to produce oxygen and their ...potential as bio-factories for space biotechnology/synthetic biology and other applications. Since many unknowns remain in our knowledge to bridge the gap and move cyanobacterial bioprocesses from Earth to space, we investigated cell division resumption on the rehydration of dried
sp. CCMEE 029 accumulated DNA damage while exposed to space vacuum, Mars-like conditions, and Fe-ion radiation. Upon rehydration, the monitoring of the
gene showed that cell division was arrested until DNA damage was repaired, which took 48 h under laboratory conditions. During the recovery, a progressive DNA repair lasting 48 h of rehydration was revealed by PCR-stop assay. This was followed by overexpression of the ftsZ gene, ranging from 7.5- to 9-fold compared to the non-hydrated samples. Knowing the time required for DNA repair and cell division resumption is mandatory for deep-space experiments that are designed to unravel the effects of reduced/microgravity on this process. It is also necessary to meet mission requirements for dried-sample implementation and real-time monitoring upon recovery. Future experiments as part of the lunar exploration mission Artemis and the lunar gateway station will undoubtedly help to move cyanobacterial bioprocesses beyond low Earth orbit. From an astrobiological perspective, these experiments will further our understanding of microbial responses to deep-space conditions.
A genome-wide investigation of the anhydrobiotic cyanobacterium
Chroococcidiopsis
sp. CCMEE 029 identified three genes coding superoxide dismutases (SODs) annotated as MnSODs (SodA2.1 and SodA2.2) ...and Cu/ZnSOD (SodC) as suggested by the presence of metal-binding motifs and conserved sequences. Structural bioinformatics analysis of the retrieved sequences yielded modeled MnSODs and Cu/ZnSOD structures that were fully compatible with their functional role. A
signal
-
peptide bioinformatics
prediction identified a Tat signal peptide at the N-terminus of the SodA2.1 that highlighted its transport across the thylakoid/cytoplasmic membranes and release in the periplasm/thylakoid lumen. Homologs of the Tat transport system were identified in
Chroococcidiopsis
sp. CCMEE 029, and the molecular docking simulation confirmed the interaction between the signal peptide of the SodA2.1 and the modeled TatC receptor, thus supporting the SodA2.1 translocation across the thylakoid/cytoplasmic membranes. No signal peptide was predicted for the MnSOD (SodA2.2) and Cu/ZnSOD, thus suggesting their occurrence as cytoplasmic proteins. No FeSOD homologs were identified in
Chroococcidiopsis
sp. CCMEE 029, a feature that might contribute to its desiccation tolerance since iron produces hydroxyl radical
via
the Fenton reaction. The overall-overexpression in response to desiccation of the three identified SOD-coding genes highlighted the role of SODs in the antioxidant enzymatic defense of this anhydrobiotic cyanobacterium. The periplasmic MnSOD protected the cell envelope against oxidative damage, the MnSOD localized in the thylakoid lumen scavengered superoxide anion radical produced during the photosynthesis, while the cytoplasmic MnSOD and Cu/ZnSOD reinforced the defense against reactive oxygen species generated at the onset of desiccation. Results contribute to decipher the desiccation-tolerance mechanisms of this cyanobacterium and allow the investigation of its oxidative stress response during future space experiments in low Earth orbit and beyond.
Deserts represent extreme habitats where photosynthetic life is restricted to the lithic niche. The ability of rock-inhabiting cyanobacteria to modify their photosynthetic apparatus and harvest ...far-red light (near-infrared) was investigated in 10 strains of the genus
Chroococcidiopsis
, previously isolated from diverse endolithic and hypolithic desert communities. The analysis of their growth capacity, photosynthetic pigments, and
apcE2
-gene presence revealed that only
Chroococcidiopsis
sp. CCMEE 010 was capable of far-red light photoacclimation (FaRLiP). A total of 15 FaRLiP genes were identified, encoding paralogous subunits of photosystem I, photosystem II, and the phycobilisome, along with three regulatory elements. CCMEE 010 is unique among known FaRLiP strains by undergoing this acclimation process with a significantly reduced cluster, which lacks major photosystem I paralogs
psaA
and
psaB
. The identification of an endolithic, extremotolerant cyanobacterium capable of FaRLiP not only contributes to our appreciation of this phenotype’s distribution in nature but also has implications for the possibility of oxygenic photosynthesis on exoplanets.
Carotenoids are promising targets in our quest to search for life on Mars due to their biogenic origin and easy detection by Raman spectroscopy, especially with a 532 nm excitation thanks to ...resonance effects. Ionizing radiations reaching the surface and subsurface of Mars are however detrimental for the long-term preservation of biomolecules. We show here that desiccation can protect carotenoid Raman signatures in the desert cyanobacterium
sp. CCMEE 029 even after high-dose gamma irradiation. Indeed, while the height of the carotenoids Raman peaks was considerably reduced in hydrated cells exposed to gamma irradiation, it remained stable in dried cells irradiated with the highest tested dose of 113 kGy of gamma rays, losing only 15-20% of its non-irradiated intensity. Interestingly, even though the carotenoid Raman signal of hydrated cells lost 90% of its non-irradiated intensity, it was still detectable after exposure to 113 kGy of gamma rays. These results add insights into the preservation potential and detectability limit of carotenoid-like molecules on Mars over a prolonged period of time and are crucial in supporting future missions carrying Raman spectrometers to Mars' surface.
The survival limits of the desert cyanobacterium
Chroococcidiopsis
were challenged by rewetting dried biofilms and dried biofilms exposed to 1.5 × 10
3
kJ/m
2
of a Mars-like UV, after 7 years of ...air-dried storage. PCR-stop assays revealed the presence of DNA lesions in dried biofilms and an increased accumulation in dried-UV-irradiated biofilms. Different types and/or amounts of DNA lesions were highlighted by a different expression of
uvrA, uvrB, uvrC, phrA,
and
uvsE
genes in dried-rewetted biofilms and dried-UV-irradiated-rewetted biofilms, after rehydration for 30 and 60 min. The up-regulation in dried-rewetted biofilms of
uvsE
gene encoding an UV damage endonuclease, suggested that UV-damage DNA repair contributed to the repair of desiccation-induced damage. While the
phrA
gene encoding a photolyase was up-regulated only in dried-UV-irradiated-rewetted biofilms. Nucleotide excision repair genes were over-expressed in dried-rewetted biofilms and dried-UV-irradiated-rewetted biofilms, with
uvrC
gene showing the highest increase in dried-UV-irradiated-rewetted biofilms. Dried biofilms preserved intact mRNAs (at least of the investigated genes) and 16S ribosomal RNA that the persistence of the ribosome machinery and mRNAs might have played a key role in the early phase recovery. Results have implications for the search of extra-terrestrial life by contributing to the definition of habitability of astrobiologically relevant targets such as Mars or planets orbiting around other stars.
Unraveling how long life can persist under extreme dryness and what kind of environmental extremes can be faced by dried microorganisms is relevant to understand Mars habitability and to search for ...life on planets with transient liquid water availability. Because trehalose and sucrose stabilize dried anhydrobiotes, an in silico survey of the genome of the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 was performed to identify pathways for trehalose and sucrose biosynthesis. The expression of the identified genes was induced in response to desiccation, and trehalose and sucrose accumulation was detected in dried cells. This adaptation strategy enabled viability and biomarker permanence under extreme dryness and Mars-like UV flux. Chroococcidiopsis survivors were scored in 7-year dried biofilms mixed with phyllosilicatic Mars regolith simulant and exposed to 5.5 × 103 kJ/m2 of a Mars-like UV flux. No survivors occurred after exposure to 5.5 × 105 kJ/m2 although, in dead cells, photosynthetic pigments, and nucleic acids, both DNA and RNA, were still detectable. This suggests that dried biofilms mixed with phyllosilicatic Martian regolith simulant are suitable candidates to identify biosignatures embedded in planetary analog minerals as planned in the future BioSignatures and habitable Niches (BioSigN) space mission to be performed outside the International Space Station.
Two anhydrobiotic strains of the cyanobacterium
, namely CCMEE 029 and CCMEE 171, isolated from the Negev Desert in Israel and from the Dry Valleys in Antarctica, were exposed to salty-ice ...simulations. The aim of the experiment was to investigate the cyanobacterial capability to survive under sub-freezing temperatures in samples simulating the environment of icy worlds. The two strains were mixed with liquid solutions having sub-eutectic concentration of Na
SO
, MgSO
and NaCl, then frozen down to different final temperatures (258 K, 233 K and 203 K) in various experimental runs. Both strains survived the exposure to 258 K in NaCl solution, probably as they migrated in the liquid veins between ice grain boundaries. However, they also survived at 258 K in Na
SO
and MgSO
-salty-ice samples-that is, a temperature well below the eutectic temperature of the solutions, where liquid veins should not exist anymore. Moreover, both strains survived the exposure at 233 K in each salty-ice sample, with CCMEE 171 showing an enhanced survivability, whereas there were no survivors at 203 K. The survival limit at low temperature was further extended when both strains were exposed to 193 K as air-dried cells. The results suggest that vitrification might be a strategy for microbial life forms to survive in potentially habitable icy moons, for example in Europa's icy crust. By entering a dried, frozen state, they could be transported from niches, which became non-habitable to new habitable ones, and possibly return to metabolic activity.
Abstract The Aurora proteins are a small family of serine/threonine kinase that function in various stages of mitosis. Current interest in Aurora kinase relates to its role in tumours, and its ...potential as a therapeutic target. In this work we studied the expression of Aurora kinases A and B and related genes in human mesothelioma tissues and in five mesothelioma cell lines. Moreover, we analyzed the effects of ZM447439 (ZM), an Aurora kinase inhibitor, on cellular growth. Results evidenced an over-expression of Aurora kinase A and related genes in human mesothelioma tissues and an over-expression of Aurora kinases A and B in all cell lines. Moreover, we demonstrated that ZM447439 was able to inhibit cell growth in all cell lines and that this inhibition was due to a specific effect as demonstrated by the reduction in the level of Histone H3 phosphorylation. Our findings support a role of Aurora kinase in mesothelioma and the possibility of using Aurora kinase inhibitors in therapeutic modalities.
To investigate the relationship between desiccation and the extent of protein oxidation in desert strains of
Chroococcidiopsis
a selection of 10 isolates from hot and cold deserts and the terrestrial ...cyanobacterium
Chroococcidiopsis thermalis
sp. PCC 7203 were exposed to desiccation (air-drying) and analyzed for survival. Strain CCMEE 029 from the Negev desert and the aquatic cyanobacterium
Synechocystis
sp. PCC 6803 were further investigated for protein oxidation after desiccation (drying over silica gel), treatment with H
2
O
2
up to 1 M and exposure to γ-rays up to 25 kGy. Then a selection of desert strains of
Chroococcidiopsis
with different survival rates after prolonged desiccation, as well as
Synechocystis
sp. PCC 6803 and
Chroococcidiopsis thermalis
sp. PCC 7203, were analyzed for protein oxidation after treatment with 10 and 100 mM of H
2
O
2
. Results suggest that in the investigated strains a tight correlation occurs between desiccation and radiation tolerance and avoidance of protein oxidation.
The mechanism of perchlorate resistance of the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 was investigated by assessing whether the pathways associated with its desiccation tolerance might ...play a role against the destabilizing effects of this chaotropic agent. During 3 weeks of growth in the presence of 2.4 mM perchlorate, an upregulation of trehalose and sucrose biosynthetic pathways was detected. This suggested that in response to the water stress triggered by perchlorate salts, these two compatible solutes play a role in the stabilization of macromolecules and membranes as they do in response to dehydration. During the perchlorate exposure, the production of oxidizing species was observed by using an oxidant‐sensing fluorochrome and determining the expression of the antioxidant defense genes, namely superoxide dismutases and catalases, while the presence of oxidative DNA damage was highlighted by the over‐expression of genes of the base excision repair. The involvement of desiccation‐tolerance mechanisms in the perchlorate resistance of this desert cyanobacterium is interesting since, so far, chaotropic‐tolerant bacteria have been identified among halophiles. Hence, it is anticipated that desert microorganisms might possess an unrevealed capability of adapting to perchlorate concentrations exceeding those naturally occurring in dry environments. Furthermore, in the endeavor of supporting future human outposts on Mars, the identified mechanisms might contribute to enhance the perchlorate resistance of microorganisms relevant for biologically driven utilization of the perchlorate‐rich soil of the red planet.
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