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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Effects of adopting new precession, nutation and equinox corrections on the terrestrial reference frame

The effects of adopting new definitive precession and equinox corrections on the terrestrial reference frame was investigated. It is noted that: (1) the effect on polar motion is a diurnal periodic term with an amplitude increasing linearly in time whole on UT1 it is a linear term; (2) general principles are given to determine the effects of small rotations of the frame of a conventional inertial reference system (CIS) on the frame of the conventional terrestrial reference system (CTS); (3) seven CTS options are presented, one of which is necessary to accommodate such rotation. Accommodating possible future changes in the astronomical nutation is discussed. The effects of differences which may exist between the various CTS's and CIS's on Earth rotation parameters (ERP) and how these differences can be determined are examined. It is shown that the CTS differences can be determined from observations made at the same site, while the CIS differences by comparing the ERP's determined by the different techniques during the same time period.

Zhu, S. Y.↗
NASA NTRS1982

Effects of adopting new precession, nutation and equinox corrections on the terrestrial reference frame

The effect of adopting definitive precession and equinox corrections on the terrestrial reference frame was investigated. It is noted that the effect on polar motion is a diurnal periodic term with an amplitude increasing linearly in time whole on UT1 it is a linear term: general principles are given to determine the effects of small rotations of the frame of a conventional inertial reference system (CIS) on the frame of the conventional terrestrial reference system (CTS); seven CTS options are presented, one of which is necessary to accommodate such rotation. Accommodating possible future changes in the astronomical nutation is discussed. The effects of differences which may exist between the various CTS's and CIS's on Earth rotation parameters (ERP) and how these differences can be determined are examined. It is shown that the CTS differences can be determined from observations made at the same site. The CIS differences by comparing the ERP's are determined by the different techniques during the same time period.

Zhu, S. Y.↗
NASA NTRS1983

The effect of earth orientation errors in baseline determination

Baselines estimated from certain space techniques are susceptible to systematic errors affecting the relative coordinates. The set of parameters that describes the continuously changing relative orientation of the conventional terrestrial (CTS) and inertial (CIS) reference frames is one source of error. As a result of these errors, the coordinates of each terminal station may actually refer to a slightly different coordinate system and therefore errors will result when these coordinates are used to compute the length between the stations. The present paper examines the expected magnitudes of these errors and their possible presence in current solutions. To test for the presence of such errors, some of the NASA/GSFC preliminary SL5 monthly baseline variations during 1979-1981 were analyzed. It is found that the present level of accuracy and stability of the available parameters linking the CTS and CIS is unsatisfactory for centimeter level baseline length determinations. It is noted that the available options are either the use of strictly simultaneous SLR data sets or the improvement of the parameters linking the CTS and CIS.

Pavlis, E. C.↗
NASA NTRS1985

Conformational properties, torsional potential, and vibrational force field for methacryloyl fluoride - An ab initio investigation

The structure, torsional potentials, vibrational spectra, and harmonic force fields for s-cis and s-trans isomers of methacryloyl fluoride are examined to understand the conformational properties of the molecules and their relationship to macroscopic polymer properties. The structure is found to be in good agreement with experiment. It is shown by calculations that the energy difference between the cis and the transisomers is less than 1 kcal/mol at both the split valence and the split valence polarized levels, with the trans form favored. Analysis of the torsional potentials indicates that a rigid rotor model provides a reasonable description of the motion of the COF group in the molecule. The torsional barrier to interconvert the s-trans to the s-cis form is found to be 7.0 kcal/mol. A fit of the data to a three-term Fourier series shows that it is possible to reproduce the experimentally derived barrier, even though a direct determination indicates that the barrier is higher.

Laskowski, B. C.↗
NASA NTRS1987

Reactions of Atomic Oxygen (O(3P)) with Polybutadienes and Related Polymers

Thin films of the following polymers were exposed at ambient temperature to ground-state oxygen atoms (O(3P)), generated by a radio-frequency glow discharge in O2: cis- and trans-1,4-polybutadienes (CB and TB), amorphous 1,2-polybutadiene (VB), polybutadienes with different 1,4/1,2 contents, trans polypentenamer (TP), cis and trans polyoctenamers (CO and TO), and ethylene-propylene rubber (EPM). Transmission infrared spectra of CB and TB films revealed extensive surface recession, or etching, unaccompanied by any microstructural changes within the films, demonstrating that the reactions were confined to the surface layers. Contrary to the report by Rabek, Lucki, and Ranby (1979), there was no O(3P)-induced cis-trans isomerization in CB or TB. From weight-loss measurements, etch rates for polybutadienes were found to be markedly dependent on vinyl content, decreasing by two orders of magnitude from CB (2% 1,2) to structures with 30 to 40% 1,2 double bonds, thereafter increasing by half an order of magnitude to VB (97% 1,2). Relative etch rates for EMP and the polyalkenamers were in the order: EMP is greater than CO (or TO) is greater than TP is greater than CB. The sole non-elastomer examined, TB, had an etch rate about six times that of CB, ascribable to a morphology difference. Cis/trans content had a negligible effect on the etch rate of the polyalkenamers. Mechanisms involving crosslinking through units are proposed for the unexpected protection imparted to polybutadienes by the 1,2 double bonds.

Golub, Morton A.↗
NASA NTRS1986

Enhanced Raman spectroscopic study of rotational isomers on metal surfaces

Surfaced-enhanced Raman spectroscopy has been used to study rotational isomers of succinonitrile and N-methyl-thioacetamide on Cu and Ag surfaces. Both the gauche and trans conformers of succinonitrile are found to chemisorb on the metal surface. The doubly degenerate nu(C-triple bond-N) in the free molecules is removed when succinonitrile adsorbs on copper, which indicates that the two (C-triple bond-N) groups are no longer chemically equivalent. Both conformers are found to coordinate to the copper surface through the pi system of one of the two (C-triple bond-N) groups. In the case of N-methyl-thioacetamide, the population of the cis isomer is greatly increased on Cu and Ag surfaces. This is probably due to surface-induced cis-trans isomerization, in which the predominant trans isomer is converted to the cis isomer.

Loo, B. H.↗
NASA NTRS1996

Towards the Synthesis and Identification of Tetrahedral N4

Tetrahedral (Td)-N4 has attracted attention as a high energy density material candidate. Although computational studies have shown Td-N4 to be a stable structure on the ground-state potential energy surface, it has yet to be experimentally observed. This study investigates possible synthetic pathways via excited state surfaces. Preliminary results include a comparison of vertical excitation energies from Td-N4 using CIS, CIS(D), CIS(3), LRCCSD, CASSCF, CASPT2, and MRCI ab initio methods. Previous studies have predicted weak IR vibrational intensities. Therefore, alternative detection schemes of Td-N4 are also investigated, such as UV and vibrational Raman spectroscopy.

Dateo, Christopher E.↗
NASA NTRS2013

Comparative Study of Vibration Condition Indicators for Detecting Cracks in Spur Gears

This paper reports the results of an empirical study on the tooth breakage failure mode in spur gears. Of four dominant gear failure modes (breakage, wear, pitting, and scoring), tooth breakage is the most precipitous and often leads to catastrophic failures. The cracks were initiated using a fatigue tester and a custom-designed single-tooth bending fixture to simulate over-load conditions, instead of traditional notching using wire electrical discharge machining (EDM). The cracks were then propagated on a dynamometer. The ground truth of damage level during crack propagation was monitored with crack-propagation sensors. Ten crack propagations have been performed to compare the existing condition indicators (CIs) with respect to their: ability to detect a crack, ability to assess the damage, and sensitivity to sensor placement. Of more than thirty computed CIs, this paper compares five commonly used: raw RMS, FM0, NA4, raw kurtosis, and NP4. The performance of combined CIs was also investigated, using linear, logistic, and boosted regression trees based feature fusion.

Nanadic, Nenad↗
NASA NTRS2013

NASA Technology Evaluation for Environmental Risk Mitigation Remediation Technology Collaboration Development

NASA is committed to finding solutions to agency cleanup problems that are better, cheaper, and more effective than the status quo. Unfortunately, some potential solutions involve innovative technologies for which NASA remediation managers may not have a high level of understanding or confidence. Since 2004, NASA's Stennis Space Center (SSC) in Mississippi has been pumping groundwater contaminated with trichloroethylene (TCE) and other halogenated volatile organic compounds (HVOC) from their cleanup location designated "Area G" through extraction wells to an aboveground treatment system. Over time, however, the effectiveness of this treatment strategy has diminished and an alternative approach is needed. In 2012, professionals from NASA's Principal Center for Technology Evaluation for Environmental Risk Mitigation (TEERM) introduced SSC managers to an innovative technology for enhancing the performance of SSC's existing pump and treat system. The technology, generally referred to as in situ chemical oxidation (ISCO), involves slowly and continuously injecting a strong but safe chemical oxidant into the groundwater. Treatment is enhanced by a "surfactant-type effect" which causes residual contamination from saturated soil to be released into the dissolved-phase where it can be readily oxidized. Any dissolved-phase contamination that was not oxidized can be collected by the extraction well network and treated aboveground. SSC was not familiar with the technology so to increase their confidence, TEERM identified a contractor who was willing to demonstrate their product and process at a significantly reduced price. An initial, small-scale demonstration of ISCO began at sse in March 2012 and completed in August 2012. This successful demonstration was followed by three larger-scale ISCO demonstrations between August and December 2012. The contractor's innovative Continuous Injection System (CIS) incorporated "green" and sustainable technologies and practices. A slow injection rate was maintained autonomously by the CIS, eliminating the need for multiple mobilizations of personnel and powered equipment. The CIS was calibrated to deliver only as much reagent as the formation would accept without "short circuiting", minimizing material waste. Public utility water pressure was used to mix, dilute, and inject the reagent. NASA personnel were trained to operate and maintain the system and remote monitoring and injection control capabilities were developed, further reducing the need for contractor mobilizations to the site. An integrated solar photovoltaic panel was used to power the control valves and web monitoring telemetry. SSC provided hydrogen peroxide for the process using their existing supplier for the aboveground pump and treat systems. The only consumable required from the contractor was their proprietary activator to catalyze SSC's peroxide.

Romeo, James↗
NASA NTRS2014

Investigation of Spiral Bevel Gear Condition Indicator Validation via AC-29-2C Using Fielded Rotorcraft HUMS Data

This report presents the analysis of gear condition indicator data collected on a helicopter when damage occurred in spiral bevel gears. The purpose of the data analysis was to use existing in-service helicopter HUMS flight data from faulted spiral bevel gears as a Case Study, to better understand the differences between HUMS data response in a helicopter and a component test rig, the NASA Glenn Spiral Bevel Gear Fatigue Rig. The reason spiral bevel gear sets were chosen to demonstrate differences in response between both systems was the availability of the helicopter data and the availability of a test rig that was capable of testing spiral bevel gear sets to failure. The objective of the analysis presented in this paper was to re-process helicopter HUMS data with the same analysis techniques applied to the spiral bevel rig test data. The damage modes experienced in the field were mapped to the failure modes created in the test rig. A total of forty helicopters were evaluated. Twenty helicopters, or tails, experienced damage to the spiral bevel gears in the nose gearbox. Vibration based gear condition indicators data was available before and after replacement. The other twenty tails had no known anomalies in the nose gearbox within the time frame of the datasets. These twenty tails were considered the baseline dataset. The HUMS gear condition indicators evaluated included gear condition indicators (CI) Figure of Merit 4 (FM4), Root Mean Square (RMS) or Diagnostic Algorithm 1 (DA1) and +/- 3 Sideband Index (SI3). Three additional condition indicators, not currently calculated on-board, were calculated from the archived data. These three indicators were +/- 1 Sideband Index (SI1), the DA1 of the difference signal (DiffDA1) and the peak-to-peak of the difference signal (DP2P). Results found the CI DP2P, not currently available in the on-board HUMS, performed the best, responding to varying levels of damage on thirteen of the fourteen helicopters evaluated. Two additional CIs also not in the on-board system, DiffDA1and SI1, also performed well responding to twelve and ten of the fourteen helicopters evaluated respectively. Of the three CIs currently available in the MSPU, DA1, FM4 and SI3, SI3, responded to eight, DA1 responded to six and FM4 responded to four of the fourteen helicopters evaluated. FM4, the poorest performing CI, was not as responsive to damage as the other five CIs. Conversely, when compared to the other two, it was the only CI that responded to damage on two helicopters. CI response could not be correlated to specific failure modes due to limited pictures and subjective descriptions found within the TDA. Flight regime did affect CI response to some gear faults. Due to the range of operating conditions for each regime, more studies are required to determine their sensitivity to regimes.

rotorcraft↗
NASA NTRS2015

Lunar COTS: An Economical and Sustainable Approach to Reaching Mars

The NASA COTS (Commercial Orbital Transportation Services) Program was a very successful program that developed and demonstrated cost-effective development and acquisition of commercial cargo transportation services to the International Space Station (ISS). The COTS acquisition strategy utilized a newer model than normally accepted in traditional procurement practices. This new model used Space Act Agreements where NASA entered into partnerships with industry to jointly share cost, development and operational risks to demonstrate new capabilities for mutual benefit. This model proved to be very beneficial to both NASA and its industry partners as NASA saved significantly in development and operational costs while industry partners successfully expanded their market share of the global launch transportation business. The authors, who contributed to the development of the COTS model, would like to extend this model to a lunar commercial services program that will push development of technologies and capabilities that will serve a Mars architecture and lead to an economical and sustainable pathway to transporting humans to Mars. Over the past few decades, several architectures for the Moon and Mars have been proposed and studied but ultimately halted or not even started due to the projected costs significantly exceeding NASA's budgets. Therefore a new strategy is needed that will fit within NASA's projected budgets and takes advantage of the US commercial industry along with its creative and entrepreneurial attributes. The authors propose a new COTS-like program to enter into partnerships with industry to demonstrate cost-effective, cis-lunar commercial services, such as lunar transportation, lunar ISRU operations, and cis-lunar propellant depots that can enable an economical and sustainable Mars architecture. Similar to the original COTS program, the goals of the proposed program, being notionally referred to as Lunar Commercial Orbital Transfer Services (LCOTS) program will be to: 1) reduce development and operational costs by sharing costs with industry; 2) create new markets in cis-lunar space to further reduce operational costs; and 3) enable NASA to develop an affordable and economical exploration Mars architecture. The paper will describe a plan for a proposed LCOTS program, its potential impact to an eventual Mars architecture and its many benefits to NASA, commercial space industry and the US economy.

Lunar ISRU↗
NASA NTRS2019

Lunar Hydrogen Infrastructure

This presentation uses recent developments and discoveries to provide a high-level technical overview of a hydrogen-based energy infrastructure that supports sustained exploration of the moon. Combining creative orbital mechanics, robotic mining and process automation techniques, humanity can use lunar resources to generate the necessary propellant to support the transportation of cargo and humans between multiple points in the cis-lunar space. Robotic systems could collect water by either directly collecting the water entrained in the lunar regolith or by processing minerals found in the lunar regolith. These robotic systems could then electrolyze the water to generate high quality hydrogen and oxygen propellant and capitalize on the very low temperatures (< 15 Kelvin) in permanently shadowed regions (PSR) to maintain these propellants in a cryogenic state. Uncrewed service vehicles could distribute this lunar-generated resource throughout the cis-lunar space to intermediary waystations, like the Gateway. These platforms enable larger payloads into Low Earth Orbit (LEO) by providing the propellant necessary to travel through the cis-lunar space without requiring launch mass to lift the propellant and supporting tankage into LEO from the Earth's surface. Delivering 1 kg to LEO from the lunar surface reduces the propellant mass of the launch vehicle from Earth by 7 kg to 11.3 kg, depending on the final destination. By leveraging resources among multiple nations and corporations, this exploration infrastructure potentially can be both fiscally self-supporting and enable more organizations to sustain a human presence on the moon.

Lunar Architecture↗
DOE OSTI2016

Utilizing Semantic Big Data for realizing a National-scale Infrastructure Vulnerability Analysis System

Critical Infrastructure systems(CIs) such as energy, water, transportation and communication are highly interconnected and mutually dependent in complex ways. Robust modeling of CIs interconnections is crucial to identify vulnerabilities in the CIs. We present here a national-scale Infrastructure Vulnerability Analysis System (IVAS) vision leveraging Se- mantic Big Data (SBD) tools, Big Data, and Geographical Information Systems (GIS) tools. We survey existing ap- proaches on vulnerability analysis of critical infrastructures and discuss relevant systems and tools aligned with our vi- sion. Next, we present a generic system architecture and discuss challenges including: (1) Constructing and manag- ing a CI network-of-networks graph, (2) Performing analytic operations at scale, and (3) Interactive visualization of ana- lytic output to generate meaningful insights. We argue that this architecture acts as a baseline to realize a national-scale network based vulnerability analysis system.

Chinthavali, Supriya↗
DOE OSTI2012

Hydrothermal syntheses, structures and characterizations of two luminescent cadmium(II) complexes with p-xylenediphosphonic acid and N-donor ligands

Two novel cadmium diphosphonates [Cd(cis-H{sub 4}BDPP)(2,2 Prime -bipy){sub 2}]{center_dot}(trans-H{sub 2}BDPP)]{sub n} (1) and [Cd(trans-H{sub 2}BDPP)(phen)]{sub n} (2) (H{sub 4}BDPP=p-xylenediphosphonic acid, phen=1,10-phenanthroline, 2,2 Prime -bipy=2,2 Prime -bipyridine) were hydrothermally synthesized from p-xylenediphosphonic acid and CdSO{sub 4}{center_dot}3H{sub 2}O with phen or 2,2 Prime -bipy as second ligand components and characterized by means of elemental analyses, IR, TG analysis, luminescence spectroscopy and single crystal X-ray diffraction. Compound 1 consists of a novel one-dimensional (1D) sinusoidal [Cd(cis-H{sub 4}BDPP)(2,2 Prime -bipy){sub 2}] chains and trans-H{sub 2}BDPP anions. Compound 2 possesses a three-dimensional architecture built from double zigzag -Cd-O-P-O-Cd- chains pillared by trans-p-xylylenediphosphonate ligands from four different directions. There are hexagonal channels running along the c-axis and the coordinated phen ligands suspend in the hexagonal channels. The results indicate that p-xylenediphosphonic acid can adopt varied coordination modes and conformations in the formation of the complexes and the influence of the N-donor ligands on the structure of the complexes is discussed. - Graphical abstract: Two new cadmium diphosphonates were obtained by using two different auxiliary ligands. The influence of the N-donor ligands on the structure of the complexes is discussed. Highlights: Black-Right-Pointing-Pointer The first example of cadmium(II)-p-xylenediphosphonates templated by second ligand. Black-Right-Pointing-Pointer The role of size of the auxiliary ligand on the structure of cadmium p-xylenediphosphonates. Black-Right-Pointing-Pointer The cis and trans configurations of p-xylenediphosphonates exist in the same crystal structure. Black-Right-Pointing-Pointer Three-dimensional 4-connected framework with PtS network topology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Groundwater Transport of Organic Compounds in Old Salvage Yard, Oak Ridge, TN - 12089

In 1950's and early 1960's during production of nuclear weapons at the US Department of Energy Y-12 National Security Complex in Oak Ridge TN, volatile organic compounds (VOCs) as well as heavy metals, nitrates, and radionuclides were released to the environment. Field investigations revealed that much of this contamination is still present in soil, bedrock, and groundwater. Operational buildings and old disposal facilities at the site have been identified as major sources of contamination. The Old Salvage Yard (OSY) on the western side of the site has long been characterized as the major source of VOC contamination in soil and groundwater. In order to analyze the fate and transport of VOC contamination- including tetrachloroethene (PCE), 1,2- dichloroethene (1,2-DCE), cis-1,2-dichloroethene (cis-1,2-DCE) and vinyl chloride (VC) - in groundwater and soil at the vicinity of OSY, an integrated surface and subsurface flow and transport model has been developed for the Y-12 NSC using the hydrodynamic and transport numerical package, MIKE-SHE. Hydrogeological characteristics of the site such as hydraulic conductivity, and transport parameters such as partitioning coefficients were varied in an effort to delineate subsurface flow and transport pathways, potential downstream impacts on Upper East Fork Poplar Creek, and the potential risk to industrial workers involved in related Decontamination and Decommissioning (D and D) activities. The simulation results were compared with the analytical modeling results previously performed by McLane Environmental Inc. using SESOIL-AT123D. Specific simulations have been performed to investigate the effect of possible remedial action (removing the contaminated surface soil layers) on the fate and transport of VOCs. The results of the MIKE-SHE reported here can be considered as an upper limit for the predicted concentrations. Based on MIKE-SHE results, PCE, 1,2 DCE, cis-1,2-DCE, and VC are sources in soil with potential to equal or exceed industrial groundwater hazard and risk levels at the vicinity of OSY. VOC contaminants in soil and groundwater will decay below industrial groundwater risk and hazard levels within approximately 20 years. Excavation of surface soil layers at the site will considerably reduce the concentration of VOCs in groundwater and the possibility of migration of VOCs to surface waters. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

A Catabolic Powerhouse for Biorefineries: Characterization and Engineering Erwinia spp. Strain LJJL01 to Produce Bioproducts

Nonmodel microbial hosts can efficiently biotransform unconventional organic feedstocks into advanced bioproducts, leveraging their superior metabolic capabilities and resilience to process-relevant physicochemical conditions. In this study, we domesticated Erwinia spp. strain. LJJL01 (Er LJJL01) as a potent microbial chassis to advance the emerging biorefinery strategy for the valorization of lignin-rich biomass and plastic, thereby enabling the circular economy. The strain exhibits remarkable chemical tolerance and can biofunnel various substrates, including sugars, acids, polyols, and aromatics, in minimal salt media to produce native fine chemicals such as acetoin, 2,3-butanediol, and lactic acid. As a proof of concept, engineering this strain with advanced genetic tools enables the production of tailored high-value chemicals, such as cis,cis-muconate from plastic-derived terephthalate and polyhydroxybutyrate from lignocellulosic hydrolysate. We established Er LJJL01 as a potent microbial chassis for the green synthesis of bioproducts from unconventional organic feedstocks.

09 BIOMASS FUELS↗
DOE OSTI2019

Sensor-Enabled Alleviation of Product Inhibition in Chorismate Pyruvate-Lyase

Product inhibition is a frequent bottleneck in industrial enzymes, and testing mutations to alleviate product inhibition via traditional methods remains challenging as many variants need to be tested against multiple substrate and product concentrations. Further, traditional screening methods are conducted in vitro, and resulting enzyme variants may perform differently in vivo in the context of whole-cell metabolism and regulation. In this study, we address these two problems by establishing a high-throughput screening method to alleviate product inhibition in an industrially relevant enzyme, chorismate pyruvate-lyase (UbiC). First, we engineered a highly specific, genetically encoded biosensor for 4-hydroxybenzoate (4HB) in an industrially relevant host, Pseudomonas putida KT2440. We subsequently applied the biosensor to detect the activity of a heterologously expressed UbiC that converts chorismate into 4HB and pyruvate. By using benzoate as a product surrogate that inhibits UbiC without activating the biosensor, we were able to efficiently create and screen a diversified library for UbiC variants with reduced product inhibition. Introduction of the improved UbiC enzyme variant into an experimental production strain for the industrial precursor cis,cis-muconic acid (muconate), enabled a >2-fold yield improvement for glucose to muconate conversion when the new UbiC variant was expressed from a plasmid and a 60% yield increase when the same UbiC variant was genomically integrated into the strain. Overall, this work demonstrates that by coupling a library of enzyme variants to whole-cell catalysis and biosensing, variants with reduced product inhibition can be identified, and that this improved enzyme can result in increased titers of a downstream molecule of interest.

09 BIOMASS FUELS↗
DOE OSTI2022

An expanded role for the transcription factor WRINKLED1 in the biosynthesis of triacylglycerols during seed development

The transcription factor WRINKLED1 ( WRI1 ) is known as a master regulator of fatty acid synthesis in developing oilseeds of Arabidopsis thaliana and other species. WRI1 is known to directly stimulate the expression of many fatty acid biosynthetic enzymes and a few targets in the lower part of the glycolytic pathway. However, it remains unclear to what extent and how the conversion of sugars into fatty acid biosynthetic precursors is controlled by WRI 1. To shortlist possible gene targets for future in-planta experimental validation, here we present a strategy that combines phylogenetic foot printing of cis-regulatory elements with additional layers of evidence. Upstream regions of protein-encoding genes in A. thaliana were searched for the previously described DNA-binding consensus for WRI1, the ASML1/WRI1 (AW)-box. For about 900 genes, AW-box sites were found to be conserved across orthologous upstream regions in 11 related species of the crucifer family. For 145 select potential target genes identified this way, affinity of upstream AW-box sequences to WRI1 was assayed by Microscale Thermophoresis. This allowed definition of a refined WRI1 DNA-binding consensus. We find that known WRI1 gene targets are predictable with good confidence when upstream AW-sites are phylogenetically conserved, specifically binding WRI1 in the in vitro assay, positioned in proximity to the transcriptional start site, and if the gene is co-expressed with WRI1 during seed development. When targets predicted in this way are mapped to central metabolism, a conserved regulatory blueprint emerges that infers concerted control of contiguous pathway sections in glycolysis and fatty acid biosynthesis by WRI1. Several of the newly predicted targets are in the upper glycolysis pathway and the pentose phosphate pathway. Of these, plastidic isoforms of fructokinase ( FRK 3) and of phosphoglucose isomerase ( PGI 1) are particularly corroborated by previously reported seed phenotypes of respective null mutations.

59 BASIC BIOLOGICAL SCIENCES↗