[1] Characterizing flow patterns and mixing of fossil fuel-derived CO 2 is important for effectively using atmospheric measurements to constrain emissions inventories. Here we used measurements and a model of atmospheric radiocarbon ( 14 C) to investigate the distribution and fluxes of atmospheric fossil fuel CO 2 across the state of California. We sampled 14 C in annual C 3 grasses at 128 sites and used these measurements to test a regional model that simulated anthropogenic and ecosystem CO 2 fluxes, transport in the atmosphere, and the resulting D 14 C of annual grasses (D g ). Average measured D g levels in Los Angeles, San Francisco, the Central Valley, and the North Coast were 27.7 ± 20.0, 44.0 ± 10.9, 48.7 ± 1.9, and 59.9 ± 2.5%, respectively, during the 2004-2005 growing season. Model predictions reproduced regional patterns reasonably well, with estimates of 27.6 ± 2.4, 39.4 ± 3.9, 46.8 ± 3.0, and 59.3 ± 0.2% for these same regions and corresponding to fossil fuel CO 2 mixing ratios (C f ) of 13.7, 6.1, 4.8, and 0.3 ppm. D g spatial heterogeneity in Los Angeles and San Francisco was higher in the measurements than in the predictions, probably from insufficient spatial resolution in the fossil fuel inventories (e.g., freeways are not explicitly included) and transport (e.g., within valleys). We used the model to predict monthly and annual transport patterns of fossil fuel-derived CO 2 within and out of California. Fossil fuel CO 2 emitted in Los Angeles and San Francisco was predicted to move into the Central Valley, raising C f above that expected from local emissions alone. Annually, about 21, 39, 35, and 5% of fossil fuel emissions leave the California airspace to the north, east, south, and west, respectively, with large seasonal variations in the proportions. Positive correlations between westward fluxes and Santa Ana wind conditions were observed. The southward fluxes over the Pacific Ocean were maintained in a relatively coherent flow within the marine boundary layer, while the eastward fluxes were more vertically dispersed. Our results indicate that state and continental scale atmospheric inversions need to consider areas where mixing ratio measurements are sparse (e.g., over the ocean to the south and west of California), transport within and across the marine boundary layer, and terrestrial boundary layer dynamics. Radiocarbon measurements can be very useful in constraining these estimates.

Protein disulfide isomerase (PDI) is the archetypal enzyme involved in the formation and reshuffling of disulfide bonds in the endoplasmic reticulum (ER). PDI achieves its redox function through two highly conserved thioredoxin domains, and PDI can also operate as an ER chaperone. The substrate specificities and the exact functions of most other PDI family proteins remain important unsolved questions in biology. Here, we characterize a new and striking member of the PDI family, which we have named protein disulfide isomeraselike protein of the testis (PDILT). PDILT is the first eukaryotic SXXC protein to be characterized in the ER. Our experiments have unveiled a novel, glycosylated PDI-like protein whose tissue-specific expression and unusual motifs have implications for the evolution, catalytic function, and substrate selection of thioredoxin family proteins. We show that PDILT is an ER resident glycoprotein that liaises with partner proteins in disulfide-dependent complexes within the testis. PDILT interacts with the oxidoreductase Ero1␣, demonstrating that the N-terminal cysteine of the CXXC sequence is not required for binding of PDI family proteins to ER oxidoreductases. The expression of PDILT, in addition to PDI in the testis, suggests that PDILT performs a specialized chaperone function in testicular cells. PDILT is an unusual PDI relative that highlights the adaptability of chaperone and redox function in enzymes of the endoplasmic reticulum.

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Crustal deformation models show incompatibility between inferred fault geometry and geologic slip rates where model and geologic slip rates disagree. We do not know if the impact of these incompatibilities is limited to near sites or have wider effect on the fault system deformation. Here, we investigate the roles of structural position of sites and uncertainty of slip rates using one suite of mechanical models that limits the dextral slip rates to within the range of observed slip rates at the sites of geologic investigations and another suite that explores the impact of each slip rate site on each other and on the nearby fault system. The suites of models employ two viable configurations for the southern San Andreas fault: with and without an active northern slip pathway around the San Gorgonio Pass. While the Active Northern Pathway model has greater mismatch to geologic slip rates < 16ka, it produces lesser off-fault deformation than the Inactive Northern Pathway model. The impact of strike-slip rate sites on the system depends on their structural positions. Sites along segmented faults may have lesser impact than either sites along the same fault segment or sites at fault branches. Consequently, inaccuracies in the slip rates used for seismic hazard assessment may have differing impacts depending on location of the slip rates. Fault branches along strike-slip faults warrant detailed investigation because these areas have high spatial variability of slip rate and accrue nearby off-fault deformation, affecting our ability to accurately assess seismic hazard of the region.