Review and Recommendations for Experimentations in Earth Orbit and Beyond

The space environment is regularly used for experiments addressing astrobiology research goals. The specific conditions prevailing in Earth orbit and beyond, notably the radiative environment (photons and energetic particles) and the possibility to conduct long-duration measurements, have been the main motivations for developing experimental concepts to expose chemical or biological samples to outer space, or to use the reentry of a spacecraft on Earth to simulate the fall of a meteorite. This paper represents an overview of past and current research in astrobiology conducted in Earth orbit and beyond, with a special focus on ESA missions such as Biopan, STONE (on Russian FOTON capsules) and EXPOSE facilities (outside the International Space Station). The future of exposure platforms is discussed, notably how they can be improved for better science return, and how to incorporate the use of small satellites such as those built in cubesat format

Halorubrum chaoviator sp. nov., a haloarchaeon isolated from sea salt in Baja California, Mexico, Western Australia and Naxos, Greece

hree halophilic isolates, strains Halo-G*T, AUS-1 and Naxos II, were compared. Halo-G* was isolated from an evaporitic salt crystal from Baja California, Mexico, whereas AUS-1 and Naxos II were isolated from salt pools in Western Australia and the Greek island of Naxos, respectively. Halo-G*T had been exposed previously to conditions of outer space and survived 2 weeks on the Biopan facility. Chemotaxonomic and molecular comparisons suggested high similarity between the three strains. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the strains clustered with Halorubrum species, showing sequence similarities of 99.2–97.1 %. The DNA–DNA hybridization values of strain Halo-G*T and strains AUS-1 and Naxos II are 73 and 75 %, respectively, indicating that they constitute a single species. The DNA relatedness between strain Halo-G*T and the type strains of 13 closely related species of the genus Halorubrum ranged from 39 to 2 %, suggesting that the three isolates constitute a different genospecies. The G+C content of the DNA of the three strains was 65.5–66.5 mol%. All three strains contained C20C20 derivatives of diethers of phosphatidylglycerol, phosphatidylglyceromethylphosphate and phosphatidylglycerolsulfate, together with a sulfated glycolipid. On the basis of these results, a novel species that includes the three strains is proposed, with the name Halorubrum chaoviator sp. nov. The type strain is strain Halo-G*T (=DSM 19316T =NCIMB 14426T =ATCC BAA-1602T)

Survival of lichens and bacteria exposed to outer space conditions - Results of the Lithopanspermia experiments

n the space experiments Lithopanspermia, experimental support was provided to the likelihood of the lithopanspermia concept that considers a viable transport of microorganisms between the terrestrial planets by means of meteorites. The rock colonising lichens Rhizocarpon geographicum and Xanthoria elegans, the vagrant lichen Aspicilia fruticulosa, and endolithic and endoevaporitic communities of cyanobacteria and bacteria with their natural rock substrate were exposed to space for 10 days onboard the Biopan facility of the European Space Agency (ESA). Biopan was closed during launch and re-entry. In addition, in the Stone facility, one sample of R. geographicum on its natural granitic substrate was attached at the outer surface of the re-entry capsule close to the stagnation point, only protected by a thin cover of glass textolite. Post-flight analysis, which included determination of the photosynthetic activity, LIVE/DEAD staining, and germination capacity of the ascospores, demonstrated that all three lichen were quite resistant to outer space conditions, which include the full spectrum of solar extraterrestrial electromagnetic radiation or selected wavelength ranges. This high resistance of the lichens to space appears to be due to their symbiotic nature and protection by their upper pigmented layer, the cortex. In contrast, the rock- or halite-inhabiting bacteria were severely damaged by the same exposure. After atmospheric re-entry, the granite of the Stone sample was transformed into a glassy, nearly homogenous material, with several friction striae. None of the lichen cells survived this re-entry process. The data suggest that lichens are suitable candidates for testing the concept of lithopanspermia, because they are extremely resistant to the harsh environment of outer space. The more critical event is the atmospheric re-entry after being captured by a planet. Experiments simulating the re-entry process of a microbe-carrying meteoroid did not show any survivors

BioPAN: a web-based tool to explore mammalian lipidome metabolic pathways on LIPID MAPS.

Lipidomics increasingly describes the quantification using mass spectrometry of all lipids present in a biological sample.  As the power of lipidomics protocols increase, thousands of lipid molecular species from multiple categories can now be profiled in a single experiment.  Observed changes due to biological differences often encompass large numbers of structurally-related lipids, with these being regulated by enzymes from well-known metabolic pathways.  As lipidomics datasets increase in complexity, the interpretation of their results becomes more challenging.  BioPAN addresses this by enabling the researcher to visualise quantitative lipidomics data in the context of known biosynthetic pathways.  BioPAN provides a list of genes, which could be involved in the activation or suppression of enzymes catalysing lipid metabolism in mammalian tissues

Substrates of the \u3cem\u3eArabidopsis thaliana\u3c/em\u3e Protein Isoaspartyl Methyltransferase 1 Identified Using Phage Display and Biopanning

The role of protein isoaspartyl methyltransferase (PIMT) in repairing a wide assortment of damaged proteins in a host of organisms has been inferred from the affinity of the enzyme for isoaspartyl residues in a plethora of amino acid contexts. The identification of PIMT target proteins in plant seeds, where the enzyme is highly active and proteome long-lived, has been hindered by large amounts of isoaspartate-containing storage proteins. Mature seed phage display libraries circumvented this problem. Inclusion of the PIMT co-substrate, S-adenosylmethionine (AdoMet), during panning permitted PIMT to retain aged phage in greater numbers than controls lacking co-substrate or when PIMT protein binding was poisoned with S-adenosyl homocysteine. After four rounds, phage titer plateaued in AdoMet-containing pans, whereas titer declined in both controls. This strategy identified 17 in-frame PIMT target proteins, including a cupin-family protein similar to those identified previously using on-blot methylation. All recovered phage had at least one susceptible Asp or Asn residue. Five targets were recovered independently. Two in-frame targets were produced in Escherichia coli as recombinant proteins and shown by on-blot methylation to acquire isoAsp, becoming a PIMT target. Both gained isoAsp rapidly in solution upon thermal insult. Mutant analysis of plants deficient in any of three in-frame PIMT targets resulted in demonstrable phenotypes. An over-representation of clones encoding proteins involved in protein production suggests that the translational apparatus comprises a subgroup for which PIMT-mediated repair is vital for orthodox seed longevity. Impaired PIMT activity would hinder protein function in these targets, possibly resulting in poor seed performance

Fatty Acids and Parasitism: Towards a Better Understanding of Lipid Metabolism in Trypanosoma Brucei

Trypanosoma brucei is an extracellular eukaryotic parasite that causes sleeping sickness in humans and cattle. As an extracellular parasite, T. brucei relies on the host’s nutrients to satisfy its growth requirements. The parasite is unusual because it does not uptake most of the host’s lipid species. Instead, T. brucei prefers to perform de novo synthesis of most lipid species. One of the lipid species that T. brucei can both uptake and synthesize is fatty acids. In my thesis work, I investigated the dynamics of fatty acid uptake, metabolism, and utilization of T. brucei. My work starts by determining the nature of the fatty acid uptake of T. brucei using a biochemical approach. I discovered that the uptake of C12:0 fatty acid was not saturable. I then investigated the possibility of lipid remodeling under the knockdown of acetyl-CoA carboxylase (ACC), the key enzyme in T. brucei’s fatty acid de novo synthesis. I found that even though there was no significant change in the lipid group, the fatty acids utilized by the lipid group changed when we performed ACC knockdown. Finally, I investigated the possibility of exogenous fatty acids as a regulation mechanism for the abundance and activity of ACC. I found that although ACC abundance did not significantly change with exogenous fatty acid addition, T. brucei’s growth was affected by these fatty acids. This work helps to better understand the role of the T. brucei ACC in de novo synthesis of fatty acids and the uptake mechanisms of these important biomolecules

Definition of exobiology experiments for future Mars missions

During the past year we have concentrated on two objectives. The first objective is ongoing and is to define the experimental parameters that are necessary to conduct autonomously a mineralogical analysis of the Martian surface in situ using differential thermal analysis coupled with gas chromatography (DTA/GC). The rationale in support of this objective is that proper interpretation of the mineralogical data from the DTA/GC can be used to better describe the present and past environments of Mars, leading to a better assessment of the probability of life evolving on Mars. To meet these objectives we have analyzed a number of samples collected from nature using the DTA/GC. One of the more significant findings was that in samples of desert varnish we detected magnetite and maghemite that may serve as potential biomarkers applicable to DTA/GC analyses of Martian surface material during landed missions. The second objective follows from the first and is to better understand microbe-environment interactions by determining the response of microbes to changes in their environment, including extreme desiccation and solar UV-radiation. The rationale behind this is to develop hypotheses regarding what may have happened to life that may have arose on Mars, and microbial life that may get to the surface of Mars via spacecraft, or meteors from Earth. To accomplish this objective we have exposed microbes, collected from NaCl and gypsum-halite crystals, to the space environment aboard the ESA-German Biopan facility for 15 days. The most significant finding was that these microbes survived the exposure better than others

Cyanobacteria from extreme deserts to space

The development of space technology makes possible the exposure of organisms and molecules to the space environ-ment by using the ESA Biopan and Expose facilities and NASA nanosatellites; the aim is to decipher the origin, evolu-tion and distribution of life on Earth and in the Universe. The study of microbial communities thriving in lithic habitats in cold and hot deserts is gathering appreciation when dealing with the limits of life as we know it, the identification of biosignatures for searching life beyond Earth and the validation of the (litho)-Panspermia theory. Cyanobacteria of the genus Chroococcidiopsis dominate rock-dwelling communities in extreme deserts that are considered terrestrial ana-logues of Mars, like the Dry Valleys in Antarctica, the Atacama Desert in Chile or the Mojave Desert in California. The extraordinary tolerance of these cyanobacteria towards desiccation, ionizing and UV radiation makes them suitable ex-perimental strains which have been already used in astrobiological experiments and already selected for future space missions. Evidence gained so far supports the use of desert cyanobacteria to develop life support systems and in-situ resource utilization for the human space exploration and settlement on the Moon or Mars

Extreme Shock Pressures: Recovery and Detection of Microfossils.

In this thesis an experimental method is utilised to test the viability and suitability of algal microfossils in the context of simulating the shock phase of lithopanspermia. Previously, the lunar surface has been suggested as a potential receptacle and store for ejected terrestrial material following a large impact on Earth. This has led to the moon being labelled in the literature as Earth’s attic. A two stage light-gas gun is used in a series of low velocity and hy pervelocity impacts. These shot range from 0.388 to 5.11 km s-1. These impact velocities experimentally map to computer simulations of ejecta originating from Earth and impacting the lunar surface. Here microfossils are loaded into a sabot and frozen. They are then fired using the light-gas gun at pre-defined velocities at a water bag target. Following the impact the water is filtered and the filtrate analysed under a scanning electron microscope. This thesis finds a shock pressure related size effect in terms of a number of size metrics. Peak shock pressure is calculated using the Planar Impact Approximation. With this, the maximum shock pressure induced by an impact was calculated to be 13.3 GPa. Microfossil fragments were recovered following each shot but intact examples became rarer as the shot velocity was ramped up. This study also provides a solution to a methodological problem arising from evacuation of a light-gas gun, and the consequential evaporation of liquids within a sabot. Thus a projectile design that can contain liquid at low pressure is made available here