SEARCH · Search NASA

Results for “STEM”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9

All sources NASA NTRS DOE OSTI

DOE OSTI2018

Promoting hepatogenic differentiation of human mesenchymal stem cells using a novel laminin-containing gelatin cryogel scaffold

Highlights: • The gelatin cryogel was optimized for stability in cell culture medium during stem cell differentiation. • The optimized gelatin cryogel improved with the laminin, the main component of basal lamina. • The novel scaffold with laminin efficiently enhanced differentiation of mesenchymal stem cells toward hepatocyte lineage. Liver transplantation is the only definitive treatment currently available for acute and chronic liver failure. However, this approach has been restricted by complications including rejection and infection. Tissue engineering approaches using stem cell-derived functional hepatic cells offer a potential alternative. Using biologically compatible scaffolds is an important complementary key to achieve optimal construct for hepatic replacement. In the present study, to optimize the differentiation of human adipose-derived mesenchymal stem cells (ADMSCs) toward hepatocyte-like cells, a previously described gelatin cryogel was optimized and improved by laminin, the major component of basal lamina. The ADMSCs seeded on the scaffold displayed increased attachment in the presence of laminin and the MTT assay showed good compatibility for cell proliferation. The differentiation of stem cells were evaluated using glycogen staining, urea secretion measurement, hepatocyte specific cell surface analysis and gene expression analysis. The results of tests indicated that laminin protein and gelatin cryogel 3D scaffold, each on its own, enhanced hepatogenic differentiation of ADMSCs. However, when laminin immobilized on the gelatin cryogel surface, the differentiation was promoted significantly and the resulting cells showed striking similarity to HepG2 in terms of expressing studied hepatocyte markers.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2020

STEM Characterization of Dislocation Loops in Irradiated FCC Alloys

In this study, we demonstrate the methodology systematically developed for dislocation loop (perfect and faulted loops) imaging and analysis in irradiated face-centered-cubic (FCC) alloys using scanning transmission electron microscopy (STEM). On-zone [001] STEM imaging was identified as the preferred choice for its accuracy and effectiveness based on the comparison with other dislocation loop imaging techniques including: (i) on-zone STEM imaging using other major low-index zone axes, (ii) kinematic two-beam conditions bright field imaging near the [001] zone axis in conventional TEM (CTEM) mode, and (iii) Rel-Rod CTEM dark-field (DF) imaging near the [011] zone axis. The effect of STEM collection angle on the contrast formation of dislocation loops was also investigated. The developed method was confirmed by imaging all populations of perfect and faulted loops of types a/2$\langle$110$\rangle${110} and a/3$\langle$111$\rangle${111} found in an ion irradiated Ni40Fe40Cr20 alloy. The proposed STEM-based technique can easily identify said loops with a size greater than 10 nm without any assumptions such as those commonly made using the conventional Rel-Rod CTEM-DF technique. The recommended methodology in this study is developed as a quick and convenient tool that can be generally applied to irradiated FCC-based materials due to their common crystallography.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2013

Mechanisms of permanent loss of olfactory receptor neurons induced by the herbicide 2,6-dichlorobenzonitrile: Effects on stem cells and noninvolvement of acute induction of the inflammatory cytokine IL-6

We explored the mechanisms underlying the differential effects of two olfactory toxicants, the herbicide 2,6-dichlorobenzonitrile (DCBN) and the anti-thyroid drug methimazole (MMZ), on olfactory receptor neuron (ORN) regeneration in mouse olfactory epithelium (OE). DCBN, but not MMZ, induced inflammation-like pathological changes in OE, and DCBN increased interleukin IL-6 levels in nasal-wash fluid to much greater magnitude and duration than did MMZ. At 24 h after DCBN injection, the population of horizontal basal cells (HBCs; reserve, normally quiescent OE stem cells) lining the DMM became severely depleted as some of them detached from the basal lamina, and sloughed into the nasal cavity along with the globose basal cells (GBCs; heterogeneous population of stem and progenitor cells), neurons, and sustentacular cells of the neuroepithelium. In contrast, the layer of HBCs remained intact in MMZ-treated mice, as only the mature elements of the neuroepithelium were shed. Despite the respiratory metaplasia accompanying the greater severity of the DCBN lesion, residual HBCs that survived intoxication were activated by the injury and contributed to the metaplastic respiratory epithelium, as shown by tracing their descendants in a K5CreEr{sup T2}::fl(stop)TdTomato strain of mice in which recombination causes HBCs to express TdTomato in advance of the lesion. But, contrary to published observations with MMZ, the HBCs failed to form ORNs. A role for IL-6 in suppressing ORN regeneration in DCBN-treated mice was rejected by the failure of the anti-inflammatory drug dexamethasone to prevent the subsequent respiratory metaplasia in the DMM, suggesting that other factors lead to HBC neuro-incompetence. - Highlights: • The herbicide dichlobenil (DCBN) can damage olfactory epithelium stem cells. • Another olfactory toxicant, methimazole, leaves the olfactory stem cells intact. • DCBN, but not methimazole, induces a prolonged increase in nasal IL-6 levels. • Dexamethasone inhibits DCBN-induced IL-6 production, but not the stem cell loss.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

4-Acetylantroquinonol B inhibits colorectal cancer tumorigenesis and suppresses cancer stem-like phenotype

4-Acetylantroquinonol B (4-AAQB), closely related to the better known antroquinonol, is a bioactive isolate of the mycelia of Antrodia camphorata, a Taiwanese mushroom with documented anti-inflammatory, hypoglycemic, vasorelaxative, and recently demonstrated, antiproliferative activity. Based on its traditional use, we hypothesized that 4-AAQB may play an active role in the suppression of cellular transformation, tumor aggression and progression, as well as chemoresistance in colorectal carcinoma (CRC). In this study, we investigated the antiproliferative role of 4-AAQB and its underlying molecular mechanism. We also compared its anticancer therapeutic potential with that of antroquinonol and the CRC combination chemotherapy of choice — folinic acid, fluorouracil and oxaliplatin (FOLFOX). Our results showed that 4-AAQB was most effective in inhibiting tumor proliferation, suppressing tumor growth and attenuating stemness-related chemoresistance. 4-AAQB negatively regulates vital oncogenic and stem cell maintenance signal transduction pathways, including the Lgr5/Wnt/β-catenin, JAK–STAT, and non-transmembrane receptor tyrosine kinase signaling pathways, as well as inducing a dose-dependent downregulation of ALDH and other stemness related factors. These results were validated in vivo, with animal studies showing 4-AAQB possessed comparable tumor-shrinking ability as FOLFOX and potentiates ability of the later to reduce tumor size. Thus, 4-AAQB, a novel small molecule, projects as a potent therapeutic agent for monotherapy or as a component of standard combination chemotherapy. - Highlights: • 4-Acetylantroquinonol B (4-AAQB) suppressed tumor cell proliferation. • 4-AAQB regulates oncogenic and stem cell maintenance signal pathways. • 4-AAQB negatively regulates Lgr5/Wnt/β-catenin and JAK–STAT pathways. • 4-AAQB reduced ALDH and other stemness related factor expression. • In vivo, 4-AAQB has comparable tumor-shrinking ability as FOLFOX.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

The HPV16 E7 oncoprotein increases the expression of Oct3/4 and stemness-related genes and augments cell self-renewal

Oct3/4 is a transcription factor involved in maintenance of the pluripotency and self-renewal of stem cells. The E7 oncoprotein and 17β-estradiol (E{sub 2}) are key factors in cervical carcinogenesis. In the present study, we aimed to investigate the effect of the HPV16 E7 oncoprotein and E{sub 2} on the expression pattern of Oct3/4, Sox2, Nanog and Fgf4. We also determined whether the E7 oncoprotein is associated with cell self-renewal. The results showed that Oct3/4, Sox2, Nanog and Fgf4 were upregulated by the E7 oncoprotein in vivo and in vitro and implicate E{sub 2} in the upregulation of these factors in vivo. We also demonstrated that E7 is involved in cell self-renewal, suggesting that the HPV16 E7 oncoprotein upregulates Oct3/4, Sox2, Nanog and Fgf4 expression to maintain the self-renewal capacity of cancer stem cells. -- Graphical abstract: The HPV16 E7 oncoprotein and 17β-estradiol are involved in the upregulation of Oct3/4, Sox2, Nanog and Fgf4 expression to maintain the self-renewal ability of cancer stem cells in cervical cancer. - Highlights: •The HPV16 E7 oncoprotein enhances cellular proliferation and dedifferentiation. •The E7 oncoprotein induces stemness-related genes expression in vivo and in vitro. •The 17β-estradiol induces stemness-related genes expression in vivo. •The HPV16 E7 oncoprotein is involved in the cell self-renewal of cancer cells.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

Comparative epigenetic influence of autologous versus fetal bovine serum on mesenchymal stem cells through in vitro osteogenic and adipogenic differentiation

Mesenchymal stem cells (MSCs) derived from bone marrow (BM) represents a useful source of adult stem cells for cell therapy and tissue engineering. MSCs are present at a low frequency in the BM; therefore expansion is necessary before performing clinical studies. Fetal bovine serum (FBS) as a nutritional supplement for in vitro culture of MSCs is a suitable additive for human cell culture, but not regarding subsequent use of these cells for clinical treatment of human patients due to the risk of viral and prion transmission as well as xenogeneic immune responses after transplantation. Recently, autologous serum (AS) has been as a supplement to replace FBS in culture medium. We compared the effect of FBS versus AS on the histone modification pattern of MSCs through in vitro osteogenesis and adipogenesis. Differentiation of stem cells under various serum conditions to a committed state involves global changes in epigenetic patterns that are critically determined by chromatin modifications. Chromatin immunoprecipitation (ChIP) coupled with real-time PCR showed significant changes in the acetylation and methylation patterns in lysine 9 (Lys9) of histone H3 on the regulatory regions of stemness (Nanog, Sox2, Rex1), osteogenic (Runx2, Oc, Sp7) and adipogenic (Ppar-γ, Lpl, adiponectin) marker genes in undifferentiated MSCs, FBS and AS. All epigenetic changes occurred in a serum dependent manner which resulted in higher expression level of stemness genes in undifferentiated MSCs compared to differentiated MSCs and increased expression levels of osteogenic genes in AS compared to FBS. Adipogenic genes showed greater expression in FBS compared to AS. These findings have demonstrated the epigenetic influence of serum culture conditions on differentiation potential of MSCs, which suggest that AS is possibly more efficient serum for osteogenic differentiation of MSCs in cell therapy purposes. - Highlights: • Bone marrow derived MSC could proliferate in AS as well as in FBS. • Different serum conditions influence epigentic patterns of genes. • Osteogenic genes specifically up-regulate in AS in response to differentiation signals.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

Polymer microfiber meshes facilitate cardiac differentiation of c-kit{sup +} human cardiac stem cells

Electrospun microfiber meshes have been shown to support the proliferation and differentiation of many types of stem cells, but the phenotypic fate of c-kit{sup +} human cardiac stem cells (hCSCs) have not been explored. To this end, we utilized thin (~5 µm) elastomeric meshes consisting of aligned 1.7 µm diameter poly (ester-urethane urea) microfibers as substrates to examine their effect on hCSC viability, morphology, proliferation, and differentiation relative to cells cultured on tissue culture polystyrene (TCPS). The results showed that cells on microfiber meshes displayed an elongated morphology aligned in the direction of fiber orientation, lower proliferation rates, but increased expressions of genes and proteins majorly associated with cardiomyocyte phenotype. The early (NK2 homeobox 5, Nkx2.5) and late (cardiac troponin I, cTnI) cardiomyocyte genes were significantly increased on meshes (Nkx=2.5 56.2±13.0, cTnl=2.9±0.56,) over TCPS (Nkx2.5=4.2±0.9, cTnl=1.6±0.5, n=9, p<0.05 for both groups) after differentiation. In contrast, expressions of smooth muscle markers, Gata6 and myosin heavy chain (SM-MHC), were decreased on meshes. Immunocytochemical analysis with cardiac antibody exhibited the similar pattern of above cardiac differentiation. We conclude that aligned microfiber meshes are suitable for guiding cardiac differentiation of hCSCs and may facilitate stem cell-based therapies for treatment of cardiac diseases. - Highlights: • First study to characterize c-kit{sup +} human cardiac stem cells on microfiber meshes. • Microfiber meshes seem reducing cell proliferation, but no effect on cell viability. • Microfiber meshes facilitate the elongation of human cardiac stem cells in culture. • Cardiac but not smooth muscle differentiation were enhanced on microfiber meshes. • Microfiber meshes may be used as cardiac patches in cell-based cardiac therapy.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2017

Characterization of stem-like cells in a new astroblastoma cell line

Cell lines established from tumors are the most commonly used models in cancer research, and their use in recent years has enabled a greater understanding of the biology of cancer and the means to develop effective treatment strategies. Astroblastomas are uncommon neuroepithelial tumors of glial origin, predominantly affecting young people, mainly teenagers and children, predominantly females. To date, only a single study has reported that astroblastomas contain a large number of neural stem-like cells, which had only a partial proliferation capacity and differentiation. Our objective was to establish an astroblastoma cell line to investigate the presence of astroblastic cells and cancer stem-like cells. The migratory and invasion abilities of the cells were quantified with invasion and migration assays and compared to a glioblastoma cell line. The presence of stem cells was detected with surface-marker analysis by using flow cytometry, and measuring the differentiation ability with a differentiation assay and the self-renewal capacity with a sphere-forming assay. These characteristics may determine whether this novel cell line is a model for astroblastomas that may have stem-cell characteristics. With this novel cell line, scientists can investigate the molecular pathways underlying astroblastomas and develop new therapeutic strategies for patients with these tumors. - Highlights: • An establishment of a novel astroblastoma cell line was proposed. • The presence of astroblastic cells and cancer stem-like cells was investigated. • The molecular pathways underlying astroblastomas may be investigated. • New therapeutic strategies for patients with astroblastoma may be developed.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2021

Functional characterization of adult human trabecular meshwork stem cells

We earlier identified native human trabecular meshwork stem cells (TMSCs) based on two-parameters- high ABCG2 expression and high nucleus to cytoplasmic ratio. The TMSCs also expressed p75 and AnkyrinG. Based on the high expression of ABCG2 and p75, the TMSCs were identified to be located in the Schwalbe's line region of the TM. In continuation, the current study aimed at elucidating the functional characteristics of human TMSCs. Upon culturing, only a small proportion of TM cells (0.96 ± 0.21% in <30 years) expressing stem cell markers ABCG2 and p75 adhered to the culture dish. This proportion significantly reduced with ageing (0.32 ± 0.23% in 30–60 years and 0.35 ± 0.04% in >60 years). Characterization of the primary TM cultures identified 7.00 ± 1.80% of stem cells with label retaining property. Further, cultured cells had the ability to form TM spheres (0.82 ± 0.23%) which consisted of high ABCG2 and p75 positive cells. Upon dexamethasone induction, 86.00 ± 14.87% and 64.60 ± 7.24% of the cells derived from the TM spheres expressed myocilin and exhibited cross linked actin networks respectively, indicating differentiation of the TMSCs in the sphere to TM cells. In addition, the sphere derived TM cells also possessed phagocytic potential (13.28 ± 3.30%) equivalent to primary TM cells (16.33 ± 4.04%) which was evident upon internalization of zymosan particles. In conclusion, this study has established that a proportion of cultured TM cells had the label retaining property as well as sphere forming ability of adult stem cells. Thus, these results confirm the presence of adult stem cells in the human TM that might be responsible for the maintenance of tissue homeostasis.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2021

CPT2 downregulation triggers stemness and oxaliplatin resistance in colorectal cancer via activating the ROS/Wnt/β-catenin-induced glycolytic metabolism

Highlights: • CPT2 was downregulated in CRC. • CPT2 suppressed the proliferation and glycolytic metabolism in CRC cells. • CPT2 inhibited cancer stem cell properties and oxaliplatin resistance in CRC. • CPT2 attenuated CRC tumor growth and enhanced oxaliplatin sensitivity in vivo. • CPT2 functioned via suppressing ROS/Wnt/β-catenin pathway in CRC. Carnitine palmitoyltransferase 2 (CPT2) has been demonstrated to act as a tumor promotor or suppressor in different types of cancers. However, little is known about the effect of CPT2 on colorectal cancer (CRC). In the present study, we analyzed CPT2 expression in CRC tissues and cells. CPT2 was overexpressed in CRC cell lines (SW480 and RKO), and its effects and molecular mechanism on the proliferation, glycolysis, stemness, and oxaliplatin sensitivity were investigated. The xenograft experiment was used to confirm the influence of CPT2 on CRC tumorigenesis in vivo. We found that CPT2 expression was significantly downregulated in CRC patients, and its lower expression was associated with the poor prognosis, large tumor size, advanced TNM stage, and poor histological grade differentiation of patients. Upregulation of CPT2 significantly inhibited the proliferation, glycolytic metabolism, cancer stem cell properties, and oxaliplatin resistance in CRC cells. Also, the increase of CPT2 inhibited tumorigenesis, stemness and glycolysis, while enhanced oxaliplatin sensitivity in mouse models. Mechanistically, CPT2 functioned via suppressing the activation of Wnt/β-catenin pathway through repressing ROS production. In conclusion, our results demonstrated that CPT2 was decreased in CRC, and CPT2 downregulation could trigger stemness and oxaliplatin resistance in CRC via activating the ROS/Wnt/β-catenin-induced glycolytic metabolism. This study indicates that CPT2 is a potential therapeutic target for CRC.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2022

Automated Experiment in 4D-STEM: Exploring Emergent Physics and Structural Behaviors

Automated experiments in 4D scanning transmission electron microscopy (STEM) are implemented for rapid discovery of local structures, symmetry-breaking distortions, and internal electric and magnetic fields in complex materials. Deep kernel learning enables active learning of the relationship between local structure and 4D-STEM-based descriptors. With this, efficient and “intelligent” probing of dissimilar structural elements to discover desired physical functionality is made possible. This approach allows effective navigation of the sample in an automated fashion guided by either a predetermined physical phenomenon, such as strongest electric field magnitude, or in an exploratory fashion. Therefore, we verify the approach first on preacquired 4D-STEM data and further implement it experimentally on an operational STEM. The experimental discovery workflow is demonstrated using graphene and subsequently extended toward a lesser-known layered 2D van der Waals material, MnPS 3 . This approach establishes a pathway for physics-driven automated 4D-STEM experiments that enable probing the physics of strongly correlated systems and quantum materials and devices, as well as exploration of beam-sensitive materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2015

Structure-based discovery of NANOG variant with enhanced properties to promote self-renewal and reprogramming of pluripotent stem cells

NANOG (from Irish mythology Tír na nÓg) transcription factor plays a central role in maintaining pluripotency, cooperating with OCT4 (also known as POU5F1 or OCT3/4), SOX2, and other pluripotency factors. Although the physiological roles of the NANOG protein have been extensively explored, biochemical and biophysical properties in relation to its structural analysis are poorly understood. Here we determined the crystal structure of the human NANOG homeodomain (hNANOG HD) bound to an OCT4 promoter DNA, which revealed amino acid residues involved in DNA recognition that are likely to be functionally important. We generated a series of hNANOG HD alanine substitution mutants based on the protein–DNA interaction and evolutionary conservation and determined their biological activities. Some mutant proteins were less stable, resulting in loss or decreased affinity for DNA binding. Overexpression of the orthologous mouse NANOG (mNANOG) mutants failed to maintain self-renewal of mouse embryonic stem cells without leukemia inhibitory factor. These results suggest that these residues are critical for NANOG transcriptional activity. Interestingly, one mutant, hNANOG L122A, conversely enhanced protein stability and DNA-binding affinity. The mNANOG L122A, when overexpressed in mouse embryonic stem cells, maintained their expression of self-renewal markers even when retinoic acid was added to forcibly drive differentiation. When overexpressed in epiblast stem cells or human induced pluripotent stem cells, the L122A mutants enhanced reprogramming into ground-state pluripotency. These findings indicate that structural and biophysical information on key transcriptional factors provides insights into the manipulation of stem cell behaviors and a framework for rational protein engineering.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Linking stem rehydration kinetics to hydraulic traits using a novel method and mechanistic model

Background: Despite the recognized importance of hydraulic capacitance as a mechanism used by plants to maintain hydraulic functioning during high transpiration, characterizing the dynamics of capacitance remains a challenge. Methods: For this work, we used a novel ‘two-balance method’ to investigate relationships between stem rehydration kinetics and other hydraulic traits in multiple tree species, and we developed a model to explore stem rehydration kinetics further. Key Results: We found that: (1) rehydration time constants and the amount of water uptake occurring during rehydration differed significantly across species; (2) time constants did not change with declining water potential (Ψ), while water uptake increased at lower Ψ in some species; (3) longer time constants were associated with lower wood density, higher capacitance and less negative stem pressures causing 50 % loss of hydraulic conductivity (P 50 ); (4) greater water uptake occurred in stems with lower wood density and less negative P 50 values; and (5) the model could estimate the total hydraulic resistance of the rehydration path, which cannot be measured directly. Conclusions: Overall, the two-balance method can be used to examine rehydration dynamics quickly and thoroughly in detached woody stems. This method has the potential to improve our understanding of how capacitance functions across tree species, which is an often-overlooked component of whole-plant hydraulics.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2024

Cell‐type‐specific transcriptomics uncovers spatial regulatory networks in bioenergy sorghum stems

SUMMARY Bioenergy sorghum is a low‐input, drought‐resilient, deep‐rooting annual crop that has high biomass yield potential enabling the sustainable production of biofuels, biopower, and bioproducts. Bioenergy sorghum's 4–5 m stems account for ~80% of the harvested biomass. Stems accumulate high levels of sucrose that could be used to synthesize bioethanol and useful biopolymers if information about cell‐type gene expression and regulation in stems was available to enable engineering. To obtain this information, laser capture microdissection was used to isolate and collect transcriptome profiles from five major cell types that are present in stems of the sweet sorghum Wray. Transcriptome analysis identified genes with cell‐type‐specific and cell‐preferred expression patterns that reflect the distinct metabolic, transport, and regulatory functions of each cell type. Analysis of cell‐type‐specific gene regulatory networks (GRNs) revealed that unique transcription factor families contribute to distinct regulatory landscapes, where regulation is organized through various modes and identifiable network motifs. Cell‐specific transcriptome data was combined with known secondary cell wall (SCW) networks to identify the GRNs that differentially activate SCW formation in vascular sclerenchyma and epidermal cells. The spatial transcriptomic dataset provides a valuable source of information about the function of different sorghum cell types and GRNs that will enable the engineering of bioenergy sorghum stems, and an interactive web application developed during this project will allow easy access and exploration of the data ( https://mc‐lab.shinyapps.io/lcm‐dataset/ ).

09 BIOMASS FUELS↗

DOE OSTI2025

Tree architectural characteristics and stem and leaf functional traits for 17 individuals in the Central Amazon

Given recent increases in tree mortality rates in the Amazon forest following extreme drought and wind events, we tested if lower wood density and acquisitive plant functional traits were associated with increased growth and mortality for common co-occurring trees in the Central Amazon. Research was conducted at the ZF2 Research Station located north or Manaus, Brazil, managed by the Instituto Nacional de Pesquisas da Amazônia (INPA). Seventeen trees of different species with similar sizes but a range in wood density (WD) and wood traits were felled, then assessed for 27 different individual functional parameters, including whole tree architecture, stem xylem anatomical and hydraulic traits and leaf traits. Wood logs were collected at DBH, 50% stem length and at 100% stem length (at the base of the canopy). For wood anatomy samples, n=3-6 subsamples from each height. For leaf samples, 30 leaves were collected from the upper sunlit canopy. The methodology is detailed in the accompanying manuscript. The trait data are summarized in this file: "Trait_Summary.CSV". Summary Trait code abbreviations and units are described in this file: "Sample_Info_Traits_Summary.CSV". Stem traits measured along the bole from the base of the tree (DBH, diameter breast height), mid-stem, and base of the canopy are described in these files: "Sapwood_Area_height.CSV"; "Species_Info_height.CSV"; "Sample_Info_height.CSV"

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2015

Application of STEM characterization for investigating radiation effects in BCC Fe-based alloys

This paper provides a general overview of advanced scanning transmission electron microscopy (STEM) techniques used for characterization of irradiated BCC Fe-based alloys. Advanced STEM methods provide the high-resolution imaging and chemical analysis necessary to understand the irradiation response of BCC Fe-based alloys. The use of STEM with energy dispersive x-ray spectroscopy (EDX) for measurement of radiation-induced segregation (RIS) is described, with an illustrated example of RIS in proton- and self-ion irradiated T91. Aberration-corrected STEM-EDX for nanocluster/nanoparticle imaging and chemical analysis is also discussed, and examples are provided from ion-irradiated oxide dispersion strengthened (ODS) alloys. In conclusion, STEM techniques for void, cavity, and dislocation loop imaging are described, with examples from various BCC Fe-based alloys.

36 MATERIALS SCIENCE↗

DOE OSTI2024

HSQC spectra of lignin isolated from poplar stems

Here we present a curated dataset of two-dimensional heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectra of lignin isolated from stems of genetically engineered poplar through auxin signaling gene modification. The plants were grown in greenhouse with temperatures between 21 and 23 °C. Plants were harvested and the aboveground stems were cut off an approximately five-inch-long segment from the bottom end of the plant stem, debarked and air-dried for three weeks. The dried stem samples were Wiley milled (mesh size 20), Soxhlet-extracted with toluene/ethanol for 24 h to remove extractives. The extracted biomass was ball-milled in a Retsch PM100 planetary ball mill using a porcelain jar with ceramic balls at 600 rpm for 2 h (in 5 min on and 5 min off cycles to avoid excessive sample heating). The ball-milled materials were then subjected to enzymatic hydrolysis for 48 h followed by centrifugation and washing with deionized water. The solid residue was freeze-dried to recover the lignin. The dry stem lignin samples were dissolved in deuterated dimethyl sulfoxide (d6) and transferred into a 5 mm tube. 13C–1H HSQC experiments were performed in a Bruker Avance III HD 500 MHz NMR spectrometer operating at a frequency of 125.12 MHz for the 13C nucleus using a standard Bruker pulse sequence on a Prodigy platform cryoprobe. The NMR spectra were acquired under the following acquisition conditions: 230 ppm spectral width in F1 (13C) dimension with 256 data points and 12 ppm spectral width in F2 (1H) dimension with 2048 data points, a 90° pulse, a one bond C–H coupling constant of 145 Hz, a 1.0 s pulse delay, and 64 scans. Spectra were processed using the Bruker TopSpin 3.6 software. Additional meta data is embedded in the raw spectra figures.

HSQC, lignin, poplar, stems, CBI↗

NASA NTRS2018

CDKN1a/p21 Plays a Critical Role in Suppressing Stem Cell Regenerative Potential During Aging

Unloading during spaceflight is known to adversely affect mammalian physiology. Mechanical stimulation is required for repair and regeneration by stem cell lineages to maintain tissue health and mass. CDKN1a/p21 functions as a potent cell cycle arrest molecule and we previously found that CDKN1a/p21 was overexpressed in mouse bone during 15-days of spaceflight on STS-131 and localized to osteoprecursor cells in the femur. Therefore, we hypothesized that altered expression of CDKN1a/p21 leads to an arrest of bone formation during spaceflight in response to altered load. To study CDKN1a/p21 and its role in stem cell-based tissue regeneration, we use a CDKN1a/p21 knockout (KO) mouse to investigate the impact on bone structure, osteoprogenitor proliferation, and mineralized nodule formation. We have shown that bone marrow stem cells isolated from juvenile (11-week-old) and skeletally mature (18-week-old) KO mice have an increased bone formation potential as evidenced by increased proliferation and mineralization rates. In addition, we have shown that juvenile KO mice display significantly increased bone volume fraction (BV/TV) relative to wildtype (WT) mice, but not in skeletally mature KO mice, indicating increased resorption and bone turnover in adult mice. To more closely examine age differences in the KO mouse, we will study a wider spectrum of mice ranging from 4 weeks to 12 months in age. To do this, we will analyze differences in bone morphometric parameters using MicroCT and osteoblastogenesis assays. The pelvis, femur, and tibia are key in distributing weight and we expect to see altered remodeling and stem cell potential with age. In combination with histomorphometry, these results will help elucidate the complex mechanisms underlying bone tissue maintenance and stem cell regeneration.

stem cells↗