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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Functional Characterization of Four Putative δ1-Pyrroline-5-Carboxylate Reductases from Bacillus subtilis

In most living organisms, the amino acid proline is synthesized starting from both glutamate and ornithine. In prokaryotes, in the absence of an ornithine cyclodeaminase that has been identified to date only in a small number of soil and plant bacteria, these pathways share the last step, the reduction of δ1-pyrroline-5-carboxylate (P5C) catalyzed by P5C reductase (EC 1.5.1.2). In several species, multiple forms of P5C reductase have been reported, possibly reflecting the dual function of proline. Aside from its common role as a building block of proteins, proline is indeed also involved in the cellular response to osmotic and oxidative stress conditions. Genome analysis of Bacillus subtilis identifies the presence of four genes (ProH, ProI, ProG, and ComER) that, based on bioinformatic and phylogenic studies, were defined as respectively coding a putative P5C reductase. Here we describe the cloning, heterologous expression, functional analysis and small-angle X-ray scattering studies of the four affinity-purified proteins. Results showed that two of them, namely ProI and ComER, lost their catalytic efficiency or underwent subfunctionalization. In the case of ComER, this could be likely explained by the loss of the ability to form a dimer, which has been previously shown to be an essential structural feature of the catalytically active P5C reductase. The properties of the two active enzymes are consistent with a constitutive role for ProG, and suggest that ProH expression may be beneficial to satisfy an increased need for proline.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Methyl jasmonate effects on sugarbeet root responses to postharvest dehydration

Background: Sugarbeet (Beta vulgaris L.) roots are stored under conditions that cause roots to dehydrate, which increases postharvest losses. Although exogenous jasmonate applications can reduce drought stress in intact plants, their ability to alleviate the effects of dehydration in postharvest sugarbeet roots or other stored plant products is unknown. Research was conducted to determine whether jasmonate treatment could mitigate physiological responses to dehydration in postharvest sugarbeet roots. Methods: Freshly harvested sugarbeet roots were treated with 10 µM methyl jasmonate (MeJA) or water and stored under dehydrating and non-dehydrating storage conditions. Changes in fresh weight, respiration rate, wound healing, leaf regrowth, and proline metabolism of treated roots were investigated throughout eight weeks in storage. Results: Dehydrating storage conditions increased root weight loss, respiration rate, and proline accumulation and prevented leaf regrowth from the root crown. Under dehydrating conditions, MeJA treatment reduced root respiration rate, but only in severely dehydrated roots. MeJA treatment also hastened wound-healing, but only in the late stages of barrier formation. MeJA treatment did not impact root weight loss or proline accumulation under dehydrating conditions or leaf regrowth under non-dehydrating conditions. Both dehydration and MeJA treatment affected expression of genes involved in proline metabolism. In dehydrated roots, proline dehydrogenase expression declined 340-fold, suggesting that dehydration-induced proline accumulation was governed by reducing proline degradation. MeJA treatment altered proline biosynthetic and catabolic gene expression, with greatest effect in nondehydrated roots. Overall, MeJA treatment alleviated physiological manifestations of dehydration stress in stored roots, although the beneficial effects were small. Postharvest jasmonate applications, therefore, are unlikely to significantly reduce dehydrationrelated storage losses in sugarbeet roots.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Self-Assembled Thermoresponsive Molecular Brushes as Nanoreactors for Asymmetric Aldol Addition in Water

The manipulation and tunability of self-assembled block copolymers through external stimuli presents an attractive strategy to develop smart polymer-based nanoreactors as supports for non-orthogonal tandem catalysis. We report on thermoresponsive core-shell micelles based on poly[norbornene-poly(2-methyl-2-oxazoline-block-2-propyl-2-oxazoline)]-graft-poly[norbornene L-proline] (P[NB-P(MeOx-b-PropOx)]-graft-P[NB-L-proline]) as catalyst supports for L-proline. These molecular brushes exhibit large differences in lower critical solution temperature behavior and nanostructure size in water depending on the chain-lengths and proline connectivity. L-Proline-mediated aldol reactions expose the efficiency by which the molecular brushes self-assemble into micelles. Molecular brushes with an extended backbone show higher activity and selectivity, suggesting better core-shell segregation of the micelles and exclusion of water from the catalytic site. Catalytic efficiencies are not improved above the cloud point temperature, the catalytic be-havior is rather sensitive to conformational changes of the polymer chains.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Impact of Hydrogen Bonds on CO 2 Binding in Eutectic Solvents: An Experimental and Computational Study toward Sorbent Design for CO 2 Capture

Choline-based amino acid ionic liquids with anions glycinate, β-alaninate, phenylalaninate, and prolinate were synthesized and mixed with ethylene glycol to form lower-viscosity benign eutectic solvents for CO 2 capture. The highest capacity measured was 0.7 moles of CO 2 per mole of ionic liquid (2 moles CO 2 per kg solvent) for a 1 to 2 mole ratio mixture of choline prolinate to ethylene glycol at 1 bar of CO 2 and 25 °C. Under 5000 ppm of CO 2 , half of this capacity was realized. Here, through a combined study of quantitative 13 C NMR spectroscopy, molecular dynamics simulations and density functional theory calculations, we show that hydrogen bonding in the eutectic solvent prevents proton-transfer between prolinate anions upon CO 2 absorption, which occurs in the absence of ethylene glycol and deactivates binding sites. Blocking this proton transfer leads to a higher binding capacity compared to neat choline prolinate. This work demonstrates the impact of hydrogen bonding on the CO 2 binding mechanism and energetics, as well as physical and thermal properties in eutectic solvents, thus addressing an unmet need and informing future studies on the development of benign sorbents for capturing CO 2 from dilute streams.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Bacillus anthracis Prolyl 4-Hydroxylase Interacts with and Modifies Elongation Factor Tu

Prolyl hydroxylation is a very common post-translational modification and plays many roles in eukaryotes such as collagen stabilization, hypoxia sensing, and controlling protein transcription and translation. There is a growing body of evidence that suggests that prokaryotes contain prolyl 4-hydroxylases (P4Hs) homologous to the hypoxia-inducible factor (HIF) prolyl hydroxylase domain (PHD) enzymes that act on elongation factor Tu (EFTu) and are likely involved in the regulation of bacterial translation. Recent biochemical and structural studies with a PHD from Pseudomonas putida (PPHD) determined that it forms a complex with EFTu and hydroxylates a prolyl residue of EFTu. Moreover, while animal, plant, and viral P4Hs act on peptidyl proline, most prokaryotic P4Hs have been known to target free l-proline; the exceptions include PPHD and a P4H from Bacillus anthracis (BaP4H) that modifies collagen-like proline-rich peptides. Here we use biophysical and mass spectrometric methods to demonstrate that BaP4H recognizes full-length BaEFTu and a BaEFTu 9-mer peptide for site-specific proline hydroxylation. Using size-exclusion chromatography coupled small-angle X-ray scattering (SEC–SAXS) and binding studies, we determined that BaP4H forms a 1:1 heterodimeric complex with BaEFTu. The SEC–SAXS studies reveal dissociation of BaP4H dimeric subunits upon interaction with BaEFTu. While BaP4H is unusual within bacteria in that it is structurally and functionally similar to the animal PHDs and collagen P4Hs, respectively, this work provides further evidence of its promiscuous substrate recognition. Lastly, it is possible that the enzyme might have evolved to hydroxylate a universally conserved protein in prokaryotes, similar to the PHDs, and implies a functional role in B. anthracis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Hydrogen bonds are a primary driving force for de novo protein folding

The protein-folding mechanism remains a major puzzle in life science. Purified soluble activation-induced cytidine deaminase (AID) is one of the most difficult proteins to obtain. Starting from inclusion bodies containing a C-terminally truncated version of AID (residues 1–153; AID 153 ), an optimized in vitro folding procedure was derived to obtain large amounts of AID 153 , which led to crystals with good quality and to final structural determination. Interestingly, it was found that the final refolding yield of the protein is proline residue-dependent. The difference in the distribution of cis and trans configurations of proline residues in the protein after complete denaturation is a major determining factor of the final yield. A point mutation of one of four proline residues to an asparagine led to a near-doubling of the yield of refolded protein after complete denaturation. It was concluded that the driving force behind protein folding could not overcome the cis -to- trans proline isomerization, or vice versa , during the protein-folding process. Furthermore, it was found that successful refolding of proteins optimally occurs at high pH values, which may mimic protein folding in vivo . It was found that high pH values could induce the polarization of peptide bonds, which may trigger the formation of protein secondary structures through hydrogen bonds. It is proposed that a hydrophobic environment coupled with negative charges is essential for protein folding. Combined with our earlier discoveries on protein-unfolding mechanisms, it is proposed that hydrogen bonds are a primary driving force for de novo protein folding.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Antioxidant metabolism variation associated with alkali-salt tolerance in thirty switchgrass (Panicum virgatum) lines

Soil salinization is a major factor limiting crop growth and development in many areas. Switchgrass (Panicum virgatum L.) is an important warm-season grass species used for biofuel production. The objective of this study was to investigate antioxidant metabolism, proline,and protein variation associated with alkali-salt tolerance among 30 switchgrass lines and identify metabolic markers for evaluating alkali-salt tolerance of switchgrass lines. The grass lines were transplanted into plastic pots containing fine sand. When the plants reached E5 developmental stage, they were subjected to either alkali-salt stress treatment (150 mM Na + and pH of 9.5) or control (no alkali-salt stress) for 20 d. The 30 switchgrass lines differed in alkali-salt tolerance as determined by the level of leaf malondialdehyde (MDA), antioxidant enzyme activity [(superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX)], proline and protein. Alkali-salt stress increased MDA, proline, SOD, reduced CAT activity, but its effect on protein and APX varied depending on lines. Wide variations in the five parameters existed among the 30 lines. In general, the lines with higher CAT activity and lower proline content under alkali-salt stress had less MDA, exhibiting better alkali-salt tolerance. Among the five parameters, CAT can be considered as valuable metabolic markers for assessment of switchgrass tolerance to alkali-salt stress.

09 BIOMASS FUELS↗
DOE OSTI2018

Photodissociative Cross-Linking of Non-covalent Peptide-Peptide Ion Complexes in the Gas Phase

We report a gas-phase UV photodissociation study investigating non-covalent interactions between neutral hydrophobic pentapeptides and peptide ions incorporating a diazirine-tagged photoleucine residue. Phenylalanine (Phe) and proline (Pro) were chosen as the conformation-affecting residues that were incorporated into a small library of neutral pentapeptides. Gas-phase ion-molecule complexes of these peptides with photo-labeled pentapeptides were subjected to photodissociation. Selective photocleavage of the diazirine ring at 355 nm formed short-lived carbene intermediates that underwent cross-linking by insertion into H–X bonds of the target peptide. The cross-link positions were established from collision-induced dissociation tandem mass spectra (CID-MS{sup 3}) providing sequence information on the covalent adducts. Effects of the amino acid residue (Pro or Phe) and its position in the target peptide sequence were evaluated. For proline-containing peptides, interactions resulting in covalent cross-links in these complexes became more prominent as proline was moved towards the C-terminus of the target peptide sequence. The photocross-linking yields of phenylalanine-containing peptides depended on the position of both phenylalanine and photoleucine. Density functional theory calculations were used to assign structures of low-energy conformers of the (GLPMG + GLL*LK + H){sup +} complex. Born-Oppenheimer molecular dynamics trajectory calculations were used to capture the thermal motion in the complexes within 100 ps and determine close contacts between the incipient carbene and the H–X bonds in the target peptide. This provided atomic-level resolution of potential cross-links that aided spectra interpretation and was in agreement with experimental data. .

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2018

Arabidopsis calcium-dependent protein kinase AtCPK1 plays a positive role in salt/drought-stress response

Highlights: • AtCPK1 enhances Arabidopsis tolerance to salt or drought stress. • Overexpressing AtCPK1 increases proline and decreases H{sub 2}O{sub 2}, MDA accumulation. • Cpk1 mutant shows increased H{sub 2}O{sub 2} and MDA and decreased proline accumulation. • Overexpressing AtCPK1 up regulates some stress-inducible genes expression. The calcium-dependent protein kinases (CDPKs) play vital roles in plant response to various environmental stimuli. Here, we investigated the function of Arabidopsis AtCPK1 in response to salt and drought stress. The loss-of-function cpk1 mutant displayed hypersensitive to salt and drought stress, whereas overexpressing AtCPK1 in Arabidopsis plants significantly enhanced the resistance to salt or drought stress. The reduced or elevated tolerance of cpk1 mutant and AtCPK1-overexpressing lines was confirmed by the changes of proline, malondialdehyde (MDA) and H{sub 2}O{sub 2}. Real-time PCR analysis revealed that the expression of several stress-inducible genes (RD29A, COR15A, ZAT10, APX2) down-regulated in cpk1 mutant and up-regulated in AtCPK1-overexpressing plants. These results are likely to indicate that AtCPK1 positively regulates salt and drought stress in Arabidopsis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Structure‐based control of the rate limitation of photosynthetic electron transport

The 2.5 Å structure of the cytochrome (cyt) b 6 f complex provides a basis for control of the rate‐limiting electron transfer step of oxygenic photosynthesis associated with the plastoquinol/quinone exchange pathway. Here, a structural change was made at a site containing two proline residues which border the intra‐cyt pathway for plastoquinol/quinone exchange. The proline side chains confer a larger aperture for passage of plastoquinol/quinone. Change of these prolines to alanine in the cyanobacterium Synechococcus sp. PCC 7002 results in attenuation of this rate‐limiting step, observed by a two‐fold reduction in the rate of cell growth, O 2 evolution, and plastoquinol‐mediated reduction of cyt f . This study demonstrates modification by site‐directed mutagenesis of photosynthetic energy transduction based on rational application of information in the atomic structure.

Ness, Jillian↗
DOE OSTI2020

Coupling of Ca 2+ and voltage activation in BK channels through the αB helix/voltage sensor interface

Large-conductance Ca 2+ and voltage-activated K + (BK) channels control membrane excitability in many cell types. BK channels are tetrameric. Each subunit is composed of a voltage sensor domain (VSD), a central pore-gate domain, and a large cytoplasmic domain (CTD) that contains the Ca 2+ sensors. While it is known that BK channels are activated by voltage and Ca 2+ , and that voltage and Ca 2+ activations interact, less is known about the mechanisms involved. In this work we explore these mechanisms by examining the gating contribution of an interface formed between the VSDs and the αB helices located at the top of the CTDs. Proline mutations in the αB helix greatly decreased voltage activation while having negligible effects on gating currents. Analysis with the Horrigan, Cui, and Aldrich model indicated a decreased coupling between voltage sensors and pore gate. Proline mutations decreased Ca 2+ activation for both Ca 2+ bowl and RCK1 Ca 2+ sites, suggesting that both high-affinity Ca 2+ sites transduce their effect, at least in part, through the αB helix. Mg 2+ activation also decreased. The crystal structure of the CTD with proline mutation L390P showed a flattening of the first helical turn in the αB helix compared to wild type, without other notable differences in the CTD, indicating that structural changes from the mutation were confined to the αB helix. These findings indicate that an intact αB helix/VSD interface is required for effective coupling of Ca 2+ binding and voltage depolarization to pore opening and that shared Ca 2+ and voltage transduction pathways involving the αB helix may be involved.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Biophysical investigation of type A PutAs reveals a conserved core oligomeric structure

Many enzymes form homooligomers, yet the functional significance of self-association is seldom obvious. Herein, we examine the connection between oligomerization and catalytic function for proline utilization A (PutA) enzymes. PutAs are bifunctional enzymes that catalyze both reactions of proline catabolism. Type A PutAs are the smallest members of the family, possessing a minimal domain architecture consisting of N-terminal proline dehydrogenase and C-terminal l-glutamate-γ-semialdehyde dehydrogenase modules. Type A PutAs form domain-swapped dimers, and in one case (Bradyrhizobium japonicum PutA), two of the dimers assemble into a ring-shaped tetramer. Whereas the dimer has a clear role in substrate channeling, the functional significance of the tetramer is unknown. To address this question, we performed structural studies of four-type A PutAs from two clades of the PutA tree. The crystal structure of Bdellovibrio bacteriovorus PutA covalently inactivated by N-propargylglycine revealed a fold and substrate-channeling tunnel similar to other PutAs. Small-angle X-ray scattering (SAXS) and analytical ultracentrifugation indicated that Bdellovibrio PutA is dimeric in solution, in contrast to the prediction from crystal packing of a stable tetrameric assembly. SAXS studies of two other type A PutAs from separate clades also suggested that the dimer predominates in solution. To assess whether the tetramer of B. japonicum PutA is necessary for catalytic function, a hot spot disruption mutant that cleanly produces dimeric protein was generated. The dimeric variant exhibited kinetic parameters similar to the wild-type enzyme. These results implicate the domain-swapped dimer as the core structural and functional unit of type A PutAs.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Structural and biophysical characterization of Rv3716c, a hypothetical protein from Mycobacterium tuberculosis

Highlights: • The dimeric MtbRv3716c has a “tweezers” like structure with a head and two tails. • The spacing between the tails is appropriate to accommodate double helical DNA. • The N- and the proline rich C-terminal ends exhibit flexibility. • Packing of molecules in the crystal structure is mediated by Cd{sup 2+} ions. • The {sup 25}QQQ{sup 27} motif might be important for divalent metal ion binding. Latent tuberculosis (TB) is the main hurdle in reaching the goal of “Stop TB 2050”. Tuberculin skin and Interferon-gamma release assay tests used currently for the diagnosis of TB infection cannot distinguish between active disease and latent tuberculosis infection (LTBI) and hence new and sensitive protein markers need to be identified for the diagnosis. A protein Rv3716c from Mycobacterium tuberculosis (MtbRv3716c) has been identified as a potential surrogate marker for the diagnosis of LTBI. Here, we present characterization of MtbRv3716c (∼13 kDa) using both biophysical and X-Ray crystallographic methods. EMSA study showed that MtbRv3716c binds to double stranded DNA. X-ray diffraction data collected on a crystal of MtbRv3716c at 1.9 Å resolution was used for structure determination using the molecular replacement method. Significant electron density was not observed for the N-terminal 21 and C-terminal 41 residues in the final electron density map. The C- terminal disordered region is proline rich and displays characteristics of intrinsically disordered proteins. Although the crystal asymmetric unit contained a protomer, a tight dimer could be generated by the application of the crystal two-fold symmetry parallel to the b axis. Packing of dimers in the crystal is mediated by a cadmium ion (Cd{sup 2+}) occurring at the interface of two dimers. Molecular packing analysis reveals large cavities that are probably occupied by the disordered segments of the N- and C-termini. Structural comparison with other homologous hypothetical DNA binding proteins (PDB codes: 1PUG, 1YBX) highlights structural features that might be significant for DNA binding.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Identification and target-modifications of temporin-PE: A novel antimicrobial peptide in the defensive skin secretions of the edible frog, Pelophylax kl. esculentus

Highlights: • A novel temporin was isolated and identified from frog skin secretions. • An N-terminal coupled TAT was first applied in temporin family modification. • The C-terminal substitution of proline resulted in a significant improvement in the level of hemolysis. • Two temporin analogs exhibited anti-proliferative activity against cancer cells. A potent natural antimicrobial peptide named temporin-PE was identified and encoded from the skin secretions of Pelophylax kl. esculentus via “shotgun” cloning and LC-MS/MS fragmentation analysis. Target-modifications were carried out to further enhance the antimicrobial and anti-proliferative bioactivities, whilst decreasing the hemolytic effect. A range of bioassays demonstrated that replacing a proline with a tyrosine residue resulted in a loss of the bioactivity against Gram-negative bacteria, but dramatically improved the hemolytic and anti-proliferative activity, indicating the FLP- motif influences the hemolytic activity of temporins. Moreover, the coupling of TAT to the peptide dramatically improved its antimicrobial activity, indicating coupling TAT to these peptides could be considered as a potential tool to improve their antimicrobial activity. Overall, we have shown that targeted modifications of this natural antimicrobial peptide can adjust its bioactivities to help its development as an antibiotic or anti-proliferative agent.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Integrative analysis of rewired central metabolism in temozolomide resistant cells

Highlights: • Temozolomide (TMZ) resistant Neurospheroids (NSP) identified in U87MG cell line. • NSP shows varied dose response, two fold higher IC{sub 50} and 30% lower growth rate. • Altered Glucose and Glutamine uptake in U87MG and NSP shapes metabolic dynamics. • Differential mRNA levels of CAN genes & ABC transporters drive respiration/growth. • Integrative paradigm identifies potential metabolic drivers for TMZ resistance. An authenticated U87MG clonal glioblastoma cell line was investigated to identify a sub-population of neurospheroidal (NSP) cells within the main epithelial population (U87MG). The NSP cells sorted using Fluorescence Assisted Cell Sorting (FACS) showed varied morphology, 30% lower growth rates, 40% higher IC{sub 50} values for temozolomide drug and could differentiate into the glial cell type (NDx). Metabolite profiling using HR-LCMS identified glucose, glutamine and serine in both populations and tryptophan only in U87MG as growth limiting substrates. Glycine, alanine, glutamate and proline were secreted by U87MG, however proline and glycine were re-utilized in NSP. Exo-metabolite profiling and phenotypic microarrays identified differential metabolism of primary carbon sources glucose and derived pyruvate for U87MG; glutamine and derived glutamate metabolism in NSP. Differential mRNA abundance of AKT1, PTEN, PIK3CA controlling metabolism, drug efflux, nutrient transport and epigenetic control MDM2 are potentially critical in shaping DNA methylation effects of temozolomide. Our study provides a new insight into the combined effect of these factors leading to temozolomide resistance in NSP.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Impact of shading following installation of agrivoltaic systems on eco-physiological and biochemical attributes of “Howes” cranberry in Massachusetts

Agrivoltaic (AV) systems, which integrate solar energy generation with crop production on the same piece of land, offer a sustainable solution for optimizing land-use efficiency. However, the impact of shading induced by solar panels on crop growth, physiology, and metabolic activities of cranberry is not known. Understanding these interactions is essential for assessing the feasibility of AV systems in cranberry production. In this study we evaluated eco-physiological and biochemical crop responses on a commercial ‘Howes’ cranberry bog grown under an agrivoltaics system using different row spacings in the year immediately following installation. Following installation of fixed tilt solar panels at a height of 3.0 m above the plant canopy, four shading treatments were evaluated: an uncovered control area and row spacings of 9.0 m, 7.0 m, and 5.0 m, corresponding to 30%, 35%, and 37% shading respectively. The shading effect was also evaluated at three different fruit developmental stages (green, blush, and full-red stage). Using microclimate sensors installed in the treatment areas, key eco-physiological and biochemical parameters, including leaf gas exchange, chlorophyll, anthocyanin, and antioxidant content, electrolyte leakage, proline and trehalose accumulation, were assessed. While moderate shading (30% and 35%) alleviated environmental stress, as reflected by improved leaf water status and reduced electrolyte leakage, these same treatments suppressed key physiological and metabolic functions, including photosynthetic activity, carbon reserve accumulation, and the biosynthesis of stress-related osmolytes and antioxidant compounds. Under higher shading (37%), these reductions were even more pronounced, indicating a potential threshold beyond which the benefits of shading are outweighed by declines in assimilate production and secondary metabolism. These findings highlight a trade-off between the stress-mitigating benefits of shading and the alterations in key physiological and metabolic processes under agrivoltaic systems. Minimizing these trade-offs by optimizing row spacing in agrivoltaics systems is critical to maintain cranberry physiological status. Since commercial cranberry is grown as a continuous plant canopy (no interrow spaces for equipment travel), damage caused by the installation process likely impacted crop response evaluated in the first year; multi-year studies are needed to fully understand the dynamics of a dual-use system. Notably, this work provides the first direct measurements of proline, trehalose content, and electrolyte leakage in cranberry grown under AV conditions, offering new insight into their physiological adjustments to shading.

14 SOLAR ENERGY↗
DOE OSTI2017

Formation of Methylamine and Ethylamine in Extraterrestrial Ices and Their Role as Fundamental Building Blocks of Proteinogenic α -amino Acids

The –CH–NH{sub 2} moiety represents the fundamental building block of all proteinogenic amino acids, with the cyclic amino acid proline being a special case (–CH–NH– in proline). Exploiting a chemical retrosynthesis, we reveal that methylamine (CH{sub 3}NH{sub 2}) and/or ethylamine (CH{sub 3}CH{sub 2}NH{sub 2}) are essential precursors in the formation of each proteinogenic amino acid. In the present study we elucidate the abiotic formation of methylamine and ethylamine from ammonia (NH{sub 3}) and methane (CH{sub 4}) ices exposed to secondary electrons generated by energetic cosmic radiation in cometary and interstellar model ices. Our experiments show that methylamine and ethylamine are crucial reaction products in irradiated ices composed of ammonia and methane. Using isotopic substitution studies we further obtain valuable information on the specific reaction pathways toward methylamine. The very recent identification of methylamine and ethylamine together with glycine in the coma of 67P/Churyumov–Gerasimenko underlines their potential to the extraterrestrial formation of amino acids.

79 ASTRONOMY AND ASTROPHYSICS↗