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NASA NTRSDate not supplied

Multi-Omics Analysis of Mouse Retina Following Low Dose Radiation and/or Hindlimb Unloading

Rodent models have been used as analogs for studying the effects of spaceflight. NASA’s GeneLab provides access to omics datasets generated from spaceflight and ground-based experiments allowing for additional retrospective analysis. We used GeneLab’s GLDS-203, a dataset generated by researchers at Loma Linda University to study the impact of prolonged unloading and/or low-dose radiation on mouse retina. The purpose of this study was to understand the effect of gamma radiation and/or hindlimb unloading on mice retinas through a multi-omics analysis. In the experiment that generated the omics data, mice were irradiated with gamma-ray and/or subjected to hindlimb unloading for 21 days and multi-omics analysis was performed at 7 days, 1 month, or 4 months post exposure. In the current study, for each of the three timepoints, we compared epigenomic profiles for retinas from exposed mice against timepoint-matched controls. We identified a total of 5,271 differentially methylated loci (DML) and 321 differentially methylated regions (DMR; using a sliding window and step size of 500 bp) with methylation difference > 10% and q-value < 0.05 (sliding linear model corrected p-value) across the nine exposure groups. Highest correlation in methylation difference was seen for significant DMLs (q-value < 0.05) across different conditions at same post exposure timepoint (Figure 1).The location of DMLs and DMRs were characterized with respect to CpG islands and shores, putative promoters, gene body, and intergenic regions (Table 1). We analyzed RNA-seq counts and performed gene set enrichment analysis using differential expression results from comparing each exposure group to its timepoint-matched control group. Significant pathways (adjusted p-value <0.05) enriched in all three microgravity-only groups were related to morphogenesis of a branching epithelium, skeletal muscle cell differentiation, and response to fibroblast growth factor. Common processes across all timepoints in the radiation-only groups were retina homeostasis, synaptic vesicle exocytosis-endocytosis, and chemotaxis. In the combination groups, regulation of trans-synaptic signaling, and Rho protein signal transduction were enriched at all three timepoints. Processes related to purine nucleotide metabolism were enriched in all nine exposure groups, with activation at 1 month, and suppression at 7 days and 4 months. A total of 14 genes contained at least one DML and were differentially expressed at adjusted p-value < 0.05, including genes implicated in cataract development (Sipa1l3, Crybb3) and those involved in cytoskeletal organization (Plec, Flnb, Eef1a1). This analysis is part of a larger effort to understand the molecular mechanisms following spaceflight exposures that can help translate effects observed in animal models to human impacts.

Prachi Kothiyal↗
NASA NTRSDate not supplied

MULTI-OMICS ANALYSIS OF THE IMPACT OF CHRONIC LOW-DOSE RADIATION AND HINDLIMB SUSPENSION ON MURINE BRAIN AND RETINA

The space environment includes hazards like radiation and microgravity which can adversely affect biological systems. We assessed multi-omics multi-tissue NASA GeneLab datasets where 6-month-old female mice were gamma irradiated (IR) and/or hindlimb unloaded (HLU) for 21 days. Whole transcriptome shotgun sequencing (RNA-Seq) and reduced representation bisulfite sequencing (RRBS) of brain and retina samples collected at 4 months post-exposure was performed to better characterize the retinal and neurological responses to spaceflight. We compared epigenomic and transcriptomic profiles within each exposure group for both tissue types to identify correlation (Pearson’s correlation test; p-value < 0.05) between gene expression and DNA methylation levels that may be related to transcriptional regulation. We then obtained genes with methylation-expression correlation that also showed differences in mean expression or dispersion between exposed and control groups (adjusted p-value < 0.25; relaxed to denote ‘hypothesis’) in the brain (37 genes in HLU, 4 in IR, and 156 in HLU+IR) or retina (92 genes in HLU, 1 in IR, and 55 in HLU+IR). Enriched Gene Ontology (GO) terms for these genes are listed in Table 1 for HLU and HLU+IR for both tissue types. No enriched terms and only a few genes were detected with IR-only exposure in the brain (Chmp1a, Limd1, Rab40b, Ubc) and retina (retinoblastoma binding protein Rbbp7). Cellular components related to synapse were enriched in both tissue types. Previous analysis of differentially expressed genes in the retina after 1 month of HLU+IR showed enrichment in the somatodendritic compartment of the neuron, which was also observed in the brain 4 months post-exposure. Interestingly, genes related to ubiquitination showed correlation between methylation and expression and were differentially expressed or dispersed in different exposure groups indicating that this pathway may play an important role in multi-stressor response (Figure 1). The current multi-omics and multi-tissue analysis interrogates the epigenomic and transcriptomic impacts of radiation and hindlimb unloading, in isolation and in combination, on the retina and the brain. The results provide insight into the adaptive response to individual spaceflight hazard analogs and their interplay, as well as hypotheses to be further tested for understanding spaceflight-induced neurological and vision effects.

Prachi Kothiyal↗
NASA NTRS2023

Stratigraphic Change from Ca-Sulfate to Mg-Sulfate in the Sedimentary Bedrock of Gale Crater, Mars: Recent Results from Curiosity’s APXS

Curiosity’s APXS instrument has been quantifying sulfates over >30 km of traverse in Gale crater. The rover recently arrived at sedimentary strata where orbital data predicted hydrated Mg-sulfates that may record a change to a drier paleoenvironment. The sequence of strata is in the Marker Band Valley (MBV), the ~10-m-thick, metal-rich Marker Band (MB), and strata above the MB. Here, we report recent sulfate observations by the APXS and provide constraints on the occurrence of Mg-sulfate and the implications for paleoenvironment interpretations. In sedimentary strata below the MBV, Mg-sulfate enrichment (~5-10 wt%) is generally limited to larger diagenetic nodules (~1-3 cm). Ca is positively correlated with S at proportions consistent with Ca-sulfate addition to the bedrock matrix. S variation is thus controlled primarily by Ca-sulfate, which increases ~30% in transitional units below the MBV. The MBV contains the first evidence of Mg-sulfate enrichment in the bedrock matrix, confirmed by the detection of crystalline Mg-sulfate by CheMin. The MBV bedrock has the same overall bulk composition as the underlying Mt. Sharp gp. strata, but with an additional ~5-15 wt% Mg-sulfate. The MB has contrasting sulfate content: (1) targets with very high concentrations of MnO (1.5 wt%), FeO (47 wt%), and Zn (2.2 wt%) are depleted in S and (2) targets with lower metal content have evidence of Mg-sulfate addition. Strata above the MB have a bulk composition that is distinct from other rocks in Gale. For example, the bedrock has molar Fe/Mn (50-60) and Cr/Ti (0.4-0.7) similar to basaltic soil, but ~3X higher Zn and high Ge (50 ppm). Median SO3 above the MB (15 wt%) is higher than the MBV (14 wt%) as well as strata below the MBV (~8 wt%). S does not correlate with Ca or Mg above the MBV. MgO (~9 wt%) is higher than below the MBV (~5 wt%) and the SO3/MgO (1.7) is in the same range as the Mg-sulfate-bearing MBV, suggesting Mg-sulfate enrichment. APXS data indicate that the MBV and above the MB preserve a relatively sharp vertical transition (~5-10 m) from Ca-sulfate to Mg-sulfate in the rock matrix. The sharp contacts with the sulfate-depleted MB and the notable change in bulk composition above the MB may indicate a complex depositional and/or diagenetic history under conditions where enrichments in the highly soluble Mg-sulfates were ultimately preserved.

Jeffrey Allan Berger↗
NASA NTRS1976

A status of progress for the Laser Isotope Separation (LIS) process

An overview of the Laser Isotope Separation (LIS) methodology is given together with illustrations showing a simplified version of the LIS technique, an example of the two-photon photoionization category, and a diagram depicting how the energy levels of various isotope influence the LIS process. Applications were proposed for the LIS system which, in addition to enriching uranium, could in themselves develop into programs of tremendous scope and breadth. These include the treatment of radioactive wastes from light-water nuclear reactors, enriching the deuterium isotope to make heavy-water, and enriching the light isotopes of such elements as titanium for aerospace weight-reducing programs. Economic comparisons of the LIS methodology with the current method of gaseous diffusion indicate an overwhelming advantage; the laser process promises to be 1000 times more efficient. The technique could also be utilized in chemical reactions with the tuned laser serving as a universal catalyst to determine the speed and direction of a chemical reaction.

Delionback, L. M.↗
NASA NTRS1975

Heavy particle emission of unusual composition from the sun

Sustained emission of low energy (0.6-4 MeV/nuc) solar particles with a composition richer in iron than in oxygen is observed in three time periods of 1974. The relative abundances of Ne, Mg, Si, and S-Ca to O are also enhanced as compared to those of the sun and of solar cosmic rays. During all three periods, a large H-3/H-4 isotope ratio was also observed; for two cases, it is in the order of unity. On the other hand, the d/H-4 and the T/He-4 are less than 0.04 and 0.02 respectively. The solar activity during the time periods of the reported emission was low. At present, it is not clear whether the emission processes which yielded enriched heavy ions also produced the He-3 enhancement. It seems that any explanation of heavy ion enrichments in solar cosmic rays has to explain also the He-3 enrichment.

Hovestadt, D.↗
NASA NTRS1976

Extralunar sulfur in Apollo 16 and 17 lunar fines

An evaluation of Apollo 16 and 17 lunar fines data by the use of mixing models demonstrates evidence of extralunar sulfur in the fines. Fines are enriched in sulfur with respect to their component rocks. The enrichment of sulfur in 25 Apollo 16 and 17 fines samples shows a positive correlation with a CC-1 like meteoritic component as estimated from siderophilic element concentrations. Mixing models were calculated with variations in mare basalt sulfur concentration values to account for possible variability in mare basalt contribution due to reduction and sulfur loss during flow implacement. Implantation of sulfur by meteoritic processes provides a source for sulfur during regolith maturation and a mechanism for exposure related enrichment in S-34.

Cripe, J. D.↗
NASA NTRS1977

'Mysterite' - A late condensate from the solar nebula

An attempt is made to clarify the nature of 'mysterite', a material that had been postulated to explain the overabundance of Tl, Bi, and Ag in certain chondrites. Four dark clasts and a vein sample from the H6 chondrite Supuhee were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Rb, Re, Sb, Se, Te, Tl, and Zn. One of the clasts is enriched in all volatile elements, while the other four samples are enriched only in the siderophile volatiles Ag, Bi, and Tl. The enrichments range up to 100 times typical H6 chondrite abundances. The proportions of Ag, Bi, and Tl suggest the presence of at least two, Tl-rich and Tl-poor, varieties of mysterite. The former seems to dominate in Supuhee and Krymka, and the latter in Mezo-Madaras. Apparently mysterite is a late condensate from the solar nebula that collected volatiles left behind by earlier generations of chondrites. It was incorporated in Supuhee and perhaps in other chondrites (mainly of low petrologic types) during brecciation events.

Higuchi, H.↗
NASA NTRS1978

Noble gases in the Murchison meteorite - Possible relics of s-process nucleosynthesis

The Murchison carbonaceous chondrite contains a new type of xenon component, enriched by up to 50 percent in five of the nine stable xenon isotopes, mass numbers 128 to 132. This component is released at 1200 to 1600 C from a severely etched mineral fraction. Krypton shows a similar but smaller enrichment in the isotopes 80 and 82. Neon and helium released in the same interval also are quite anomalous, being highly enriched in the isotopes 22 and 3. These patterns are strongly suggestive of three nuclear processes believed to take place in red giants: the s process (neutron capture on a slow time scale), helium burning, and hydrogen shell burning. If this interpretation is correct, then primitive meteorites contain yet another kind of alien, presolar material: dust grains ejected from red giants.

Srinivasan, B.↗
NASA NTRS1975

Genetic relations between the moon and meteorites

The moon is shown to have an oxygen isotope distribution similar to that of the earth and the differentiated meteorites (achondrites, mesosiderites, pallasites, irons) but, according to the same criterion, the moon is unrelated to the ordinary chondrites or carbonaceous chondrites. The principal differences between the inferred chemical composition of the moon and that of chondritic meteorites is the depletion of volatile and semivolatile elements, the enrichment of uranium by a factor of 10-15, and the enrichment of the source regions of mare basalts in LIL elements by a factor of 5-10. The reported data support the theory that the moon was formed by the capture of differentiated meteorites. Volatile-element depletion and 'refractory' element enrichment are considered.

Clayton, R. N.↗
NASA NTRS1978

Isotopic fractionation of silicon in Allende inclusions

The variations of Si-30/Si-28 and Si-29/Si-28 in Allende inclusions are large, and are due predominantly to mass-dependent fractionation effects. Gas-soild or gas-liquid condensation processes at high temperatures have sufficiently large fractionation factors to account for the heavy-isotope enrichments in coarse-grained inclusions. Heavy isotope depletions are found in some Allende samples, and apparently result from a late-stage condensation. Thus, the silicon isotopic compositions may be useful for determining the sequence of events in forming the Allende meteorite. The peculiar Allende inclusion, Cl, has a very large mass-fractionated enrichment of Si-30/Si-28, and in addition, perhaps a small nuclear enrichment of Si-29. Olivine from the unusual pallasite, Eagle Station, has normal silicon isotope abundances even though it has a large O-16 excess.

Clayton, R. N.↗
NASA NTRS1978

An experimental investigation of fractionation by sputter deposition

Artificial glass targets composed of elements varying widely in atomic weight were irradiated at an angle of incidence of 45 deg by 2-keV hydrogen ions at a current density of .33 mA/sq cm, and sputtered atoms were caught on a molybdenum film. Analyses of the sputter-deposited films and unsputtered target glasses were carried out by electron microprobe. The backward-sputtered component was found to be enriched in elements of low atomic weight, while the forward-sputtered component was enriched in heavy atoms. These results indicate that at the lunar surface lighter elements and isotopes would tend to be ejected in backward directions, escaping directly through the openings which admit bombarding ions without first striking an adjacent grain surface; heavy elements and isotopes would be forward-sputtered deeper into the soil and be preferentially retained, contributing to the reported enrichments of heavy elements and isotopes. Additional results show that the binding energy of an element in its oxide form influences the sticking coefficient of a sputtered atom; elements of low binding energy are likely to desorb, while elements of high binding energy tend to stick to the first bounce surface.

Paruso, D. M.↗
NASA NTRS1979

Plagiogranites as late-stage immiscible liquids in ophiolite and mid-ocean ridge suites - An experimental study

A study of relationships between basic and acidic rocks was made by fractionating primitive basalt at low pressure anhydrous conditions at various fugacities. Fractionally crystallized basalt became increasingly enriched in iron which became silicate liquid immiscible, producing Fe-enriched basaltic and granitic liquids. The latter is similar to plagiogranites found in mid-oceanic rift (MOR) regions, showing that silicate liquid immiscibility could be the petrogenic process which produces plagiogranites in some MOR regions and ophiolites. The major problem in considering plagiogranites as products of silicate liquid immiscibility is absence of any description of the Fe-enriched conjugate liquid in the ophiolite or MOR literature, and the identification of this magma is essential for a definite case of silicate liquid immiscibility.

Dixon, S.↗
NASA NTRS1980

Meteoritic material at four Canadian impact craters

Eleven impact melt and six basement rock samples from four craters were analyzed by neutron activation for Au, Co, Cr, Fe, Ge, Ir, Ni, Os, Pd, Re and Se. Wanapitei Lake, Ontario: the impact melts show uniform enrichments corresponding to 1-2% C1-chondrite material. Interelement ratios (Co/Cr, Ni/Cr, Ni/Ir) suggest that the impacting body was a C1-, C2-, or LL-chondrite. Nicholson Lake, North West Territory: Ni, Cr and Co are distinctly more enriched than Ir and Au which tentatively suggests an olivine-rich achondrite (nakhlite or ureilite). Gow Lake, Saskatchewan and Mistastin, Labrador: small enrichments in Ir and Ni; both the low Ir/Ni ratios and low Cr content suggest iron meteorites, but the signals are too weak for conclusive identification. A tentative comparison of meteoritic signatures at 10 large, greater than or equal to 4 km craters and their presumed celestial counterparts (13 Apollo and Amor asteroids) shows more irons and achondrites among known projectile types, and a preponderance of S-type objects, having no known meteoritic equivalent, among asteroids. It is not yet clear that these differences are significant, in view of the tentative nature of the crater identifications and the limited statistics.

Wolf, R.↗
NASA NTRS1980

Direct thermal water splitting by concentrated solar radiation for hydrogen production. Phase O: Proof of concept experiment

The direct production of hydrogen from water and solar energy concentrated into a high temperature aperture is described. A solar powered reactor able to dissociate water vapor and to separate the reaction product at high temperature was developed, and direct water splitting has been achieved in a laboratory reactor. Water vapor and radiative heating from a carbon dioxide laser are fed into the reactor, and water vapor enriched in hydrogen and water vapor enriched in oxygen are produced. The enriched water vapors are separated through a separation membrane, a small disc of zirconium dioxide heated to a range of 1800 k to 2800 k. To avoid water vapor condensation within the reactor, the total pressure within the reactor was limited to 0.15 torr. A few modifications would enable the reactor to be operated at an increased pressure of a few torrs. More substantial modifications would allow for a reaction pressure of 0.1 atmosphere.

Genequand, P.↗
NASA NTRS1981

Performance calculations for 200-1000 MWe MHD/steam power plants

The effects of MHD generator length, level of oxygen enrichment, and oxygen production power on the performance of MHD/steam power plants ranging from 200 to 1000 MW in electrical output are investigated. The plants considered use oxygen enriched combustion air preheated to 1100 F. Both plants in which the MHD generator is cooled with low temperature and pressure boiler feedwater and plants in which the generator is cooled with high temperature and pressure boiler feedwater are considered. For plants using low temperature boiler feedwater for generator cooling the maximum thermodynamic efficiency is obtained with shorter generators and a lower level of oxygen enrichment compared to plants using high temperature boiler feedwater for generator cooling. The generator length at which the maximum plant efficiency occurs increases with power plant size for plants with a generator cooled by low temperature feedwater. Also shown is the relationship of the magnet stored energy requirement of the generator length and the power plant performance. Possible cost/performance tradeoffs between magnet cost and plant performance are indicated.

Staiger, P. J.↗
NASA NTRS1981

Hotspots, basalts, and the evolution of the mantle

It is noted that the trace element concentration patterns of continental and ocean island basalts and of mid-ocean ridge basalts are complementary. Estimates of the relative sizes of the source regions for these fundamentally different basalt types can be arrived at from the trace element enrichment-depletion patterns. Their combined volume occupies the greater part of the mantle above the 670 km discontinuity. It is pointed out that the source regions separated as a result of early mantle differentiation and crystal fractionation from the resulting melt. The mid-ocean ridge basalts source evolved from an eclogite cumulate that gave up its late-stage enriched fluids at various times to the shallower mantle and continental crust. The mid-ocean ridge basalts source is rich in garnet and clinopyroxene, while the continental and ocean island basalt source is a garnet peridotite that has experienced secondary enrichment. These relationships are found to be consistent with the evolution of a terrestrial magma ocean.

Anderson, D. L.↗
NASA NTRS1982

Comparative analysis of the conceptual design studies of potential early commercial MHD power plants (CSPEC)

A conceptual design study of the MHD/steam plant that incorporates the use of oxygen enriched air preheated in a metallic heat exchanger as the combustor oxidant showed that this plant is the most attractive for early commercial applications. The variation of performance and cost was investigated as a function of plant size. The contractors' results for the overall efficiencies are in reasonable agreement considering the slight differences in their plant designs. NASA LeRC is reviewing cost and performance results for consistency with those of previous studies, including studies of conventional steam plants. LeRC in house efforts show that there are still many tradeoffs to be considered for these oxygen enriched plants and considerable variations can be made in channel length and level of oxygen enrichment with little change in overall plant efficiency.

Sovie, R. J.↗
NASA NTRS1980

The lunar regolith - Comparative chemistry of the Apollo sites

In a grain-size study of various sections of the Apollo 17 drill core conducted by Laul et al. (1978, 1979), it was found that the fine fractions were consistently more enriched in highland material than the coarse fractions. Relative to the coarse fractions, the fine fractions contained 6-20% more KREEP material. In connection with these observations, an investigation was conducted to find out whether KREEP enrichment in fines occurs in soils from other sites. The investigation is also concerned with possibilities regarding any preferential lateral transport of the finest soil fractions relative to the coarser fractions. A description is presented of the chemical study of eight soils from five landing sites, taking into account also data on soil 70009 from the Apollo 17 drill core. Relative to the coarse fractions, no mare enrichment is found in the fines of highland soils. This argues strongly against preferential transport of fine fractions relative to coarse.

Laul, J. C.↗