Phys Sci Res Assoc, Earth & Planetary Sciences
Ph.D., University of Hawaii at Manoa, Geology and Geophysics (2015)
B.A., Astronomy, University of Southern California (2008)
Glucose dissociates DDX21 dimers to regulate mRNA splicing and tissue differentiation.
2023; 186 (1): 80
Glucose is a universal bioenergy source; however, its role in controlling protein interactions is unappreciated, as are its actions during differentiation-associated intracellular glucose elevation. Azido-glucose click chemistry identified glucose binding to a variety of RNA binding proteins (RBPs), including the DDX21 RNA helicase, which was found to be essential for epidermal differentiation. Glucose bound the ATP-binding domain of DDX21, altering protein conformation, inhibiting helicase activity, and dissociating DDX21 dimers. Glucose elevation during differentiation was associated with DDX21 re-localization from the nucleolus to the nucleoplasm where DDX21 assembled into larger protein complexes containing RNA splicing factors. DDX21 localized to specific SCUGSDGC motif in mRNA introns in a glucose-dependent manner and promoted the splicing of key pro-differentiation genes, including GRHL3, KLF4, OVOL1, and RBPJ. These findings uncover a biochemical mechanism of action for glucose in modulating the dimerization and function of an RNA helicase essential for tissue differentiation.
View details for DOI 10.1016/j.cell.2022.12.004
View details for PubMedID 36608661
- Nanoscale isotopic evidence resolves origins of giant Carlin-type ore deposits GEOLOGY 2022; 50 (6): 660-664
Fine-grained material associated with a large sulfide returned from Comet81P/Wild 2
METEORITICS & PLANETARY SCIENCE
2019; 54 (5): 1069-1091
In a consortium analysis of a large particle captured from the coma of comet 81P/Wild 2 by the Stardust spacecraft, we report the discovery of a field of fine-grained material (FGM) in contact with a large sulfide particle. The FGM was partially located in an embayment in the sulfide. As a consequence, some of the FGM appears to have been protected from damage during hypervelocity capture in aerogel. Some of the FGM particles are indistinguishable in their characteristics from common components of chondritic-porous interplanetary dust particles (CP-IDPs), including glass with embedded metals and sulfides (GEMS) and equilibrated aggregates (EAs). The sulfide exhibits surprising Ni-rich lamellae, which may indicate that this particle experienced a long-duration heating event after its formation but before incorporation into Wild 2.
View details for DOI 10.1111/maps.13265
View details for Web of Science ID 000468026900006
View details for PubMedID 31080342
View details for PubMedCentralID PMC6505703
TECHNIQUE FOR COMPARISON OF MICRO-CAI CONCENTRATIONS IN 81P/WILD2 FINE-GRAINED MATERIAL AND PRIMITIVE METEORITE MATRICES
WILEY. 2018: 6301
View details for Web of Science ID 000438212400335
Low-temperature aqueous alteration on the CR chondrite parent body: Implications from in situ oxygen-isotope analyses
GEOCHIMICA ET COSMOCHIMICA ACTA
2018; 222: 230-252
The presence of hydrated minerals in chondrites indicates that water played an important role in the geologic evolution of the early Solar System; however, the process of aqueous alteration is still poorly understood. Renazzo-like carbonaceous (CR) chondrites are particularly well-suited for the study of aqueous alteration. Samples range from being nearly anhydrous to fully altered, essentially representing snapshots of the alteration process through time. We studied oxygen isotopes in secondary-minerals from six CR chondrites of varying hydration states to determine how aqueous fluid conditions (including composition and temperature) evolved on the parent body. Secondary minerals analyzed included calcite, dolomite, and magnetite. The O-isotope composition of calcites ranged from δ18O ≈ 9 to 35 ‰, dolomites from δ18O ≈ 23 to 27 ‰, and magnetites from δ18O ≈ -18 to 5 ‰. Calcite in less-altered samples showed more evidence of fluid evolution compared to heavily altered samples, likely reflecting lower water/rock ratios. Most magnetite plotted on a single trend, with the exception of grains from the extensively hydrated chondrite MIL 090292. The MIL 090292 magnetite diverges from this trend, possibly indicating an anomalous origin for the meteorite. If magnetite and calcite formed in equilibrium, then the relative 18O fractionation between them can be used to extract the temperature of co-precipitation. Isotopic fractionation in Al Rais carbonate-magnetite assemblages revealed low precipitation temperatures (~60°C). Assuming that the CR parent body experienced closed-system alteration, a similar exercise for parallel calcite and magnetite O-isotope arrays yields "global" alteration temperatures of ~55 to 88 °C. These secondary mineral arrays indicate that the O-isotopic composition of the altering fluid evolved upon progressive alteration, beginning near the Al Rais water composition of Δ17O ~ 1 ‰ and δ18O ~ 10 ‰, and becoming increasingly 16O-enriched toward a final fluid composition of Δ17O ~ -1.2 ‰ and δ18O ~ -15 ‰.
View details for DOI 10.1016/j.gca.2017.10.007
View details for Web of Science ID 000424972200014
View details for PubMedID 29713092
View details for PubMedCentralID PMC5921071
- Insights into solar nebula formation of pyrrhotite from nanoscale disequilibrium phases produced by H2S sulfidation of Fe metal AMERICAN MINERALOGIST 2017; 102 (9): 1881-1893
OXYGEN BUFFERING IN HIGH PRESSURE SOLID MEDIA ASSEMBLIES: NEW APPROACH ENABLING STUDY OF fO(2) FROM IW-4 TO IW+4.5.
WILEY. 2017: A285
View details for Web of Science ID 000418552900283
- Mn-53-(53) Cr radiometric dating of secondary carbonates in CR chondrites: Timescales for parent body aqueous alteration GEOCHIMICA ET COSMOCHIMICA ACTA 2017; 201: 224-244
O-ISOTOPE MAPPING OF FINE-GRAINED MATERIAL COLLECTED FROM COMET 81P/WILD 2.
WILEY-BLACKWELL. 2016: A262
View details for Web of Science ID 000388662400120
- Petrography and classification of NWA 7402: A new sulfide-rich unequilibrated ordinary chondrite CHEMIE DER ERDE-GEOCHEMISTRY 2016; 76 (1): 111-116
(MN)-M-53-(CR)-C-53 DATING OF SECONDARY DOLOMITE IN A RENAZZO (CR CHONDRITE) DARK INCLUSION
View details for Web of Science ID 000358591900157
- Mn-53-Cr-53 dating of aqueously formed carbonates in the CM2 lithology of the Sutter's Mill carbonaceous chondrite METEORITICS & PLANETARY SCIENCE 2014; 49 (11): 2104-2117
- Identification and characterization of science-rich landing sites for lunar lander missions using integrated remote sensing observations ADVANCES IN SPACE RESEARCH 2012; 50 (12): 1647-1665