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  • 1
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 46 ( 2020-11-17), p. 28960-28970
    Abstract: Inhibition of the chemokine receptor CXCR4 in combination with blockade of the PD-1/PD-L1 T cell checkpoint induces T cell infiltration and anticancer responses in murine and human pancreatic cancer. Here we elucidate the mechanism by which CXCR4 inhibition affects the tumor immune microenvironment. In human immune cell-based chemotaxis assays, we find that CXCL12-stimulated CXCR4 inhibits the directed migration mediated by CXCR1, CXCR3, CXCR5, CXCR6, and CCR2, respectively, chemokine receptors expressed by all of the immune cell types that participate in an integrated immune response. Inhibiting CXCR4 in an experimental cancer medicine study by 1-wk continuous infusion of the small-molecule inhibitor AMD3100 (plerixafor) induces an integrated immune response that is detected by transcriptional analysis of paired biopsies of metastases from patients with microsatellite stable colorectal and pancreatic cancer. This integrated immune response occurs in three other examples of immune-mediated damage to noninfected tissues: Rejecting renal allografts, melanomas clinically responding to anti-PD1 antibody therapy, and microsatellite instable colorectal cancers. Thus, signaling by CXCR4 causes immune suppression in human pancreatic ductal adenocarcinoma and colorectal cancer by impairing the function of the chemokine receptors that mediate the intratumoral accumulation of immune cells.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
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  • 2
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 112, No. 14 ( 2015-04-07), p. 4245-4250
    Abstract: The Sample Analysis at Mars (SAM) investigation on the Mars Science Laboratory (MSL) Curiosity rover has detected oxidized nitrogen-bearing compounds during pyrolysis of scooped aeolian sediments and drilled sedimentary deposits within Gale crater. Total N concentrations ranged from 20 to 250 nmol N per sample. After subtraction of known N sources in SAM, our results support the equivalent of 110–300 ppm of nitrate in the Rocknest (RN) aeolian samples, and 70–260 and 330–1,100 ppm nitrate in John Klein (JK) and Cumberland (CB) mudstone deposits, respectively. Discovery of indigenous martian nitrogen in Mars surface materials has important implications for habitability and, specifically, for the potential evolution of a nitrogen cycle at some point in martian history. The detection of nitrate in both wind-drifted fines (RN) and in mudstone (JK, CB) is likely a result of N 2 fixation to nitrate generated by thermal shock from impact or volcanic plume lightning on ancient Mars. Fixed nitrogen could have facilitated the development of a primitive nitrogen cycle on the surface of ancient Mars, potentially providing a biochemically accessible source of nitrogen.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2015
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  • 3
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 120, No. 4 ( 2023-01-24)
    Abstract: Sonic hedgehog signaling regulates processes of embryonic development across multiple tissues, yet factors regulating context-specific Shh signaling remain poorly understood. Exome sequencing of families with polymicrogyria (disordered cortical folding) revealed multiple individuals with biallelic deleterious variants in TMEM161B , which encodes a multi-pass transmembrane protein of unknown function. Tmem161b null mice demonstrated holoprosencephaly, craniofacial midline defects, eye defects, and spinal cord patterning changes consistent with impaired Shh signaling, but were without limb defects, suggesting a CNS-specific role of Tmem161b. Tmem161b depletion impaired the response to Smoothened activation in vitro and disrupted cortical histogenesis in vivo in both mouse and ferret models, including leading to abnormal gyration in the ferret model. Tmem161b localizes non-exclusively to the primary cilium, and scanning electron microscopy revealed shortened, dysmorphic, and ballooned ventricular zone cilia in the Tmem161b null mouse, suggesting that the Shh-related phenotypes may reflect ciliary dysfunction. Our data identify TMEM161B as a regulator of cerebral cortical gyration, as involved in primary ciliary structure, as a regulator of Shh signaling, and further implicate Shh signaling in human gyral development.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2023
    detail.hit.zdb_id: 209104-5
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  • 4
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 115, No. 33 ( 2018-08-14)
    Abstract: The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2018
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  • 5
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2014
    In:  Proceedings of the National Academy of Sciences Vol. 111, No. 36 ( 2014-09-09), p. 13034-13039
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 111, No. 36 ( 2014-09-09), p. 13034-13039
    Abstract: Microbial rhodopsins are a diverse group of photoactive transmembrane proteins found in all three domains of life. A member of this protein family, Archaerhodopsin-3 (Arch) of halobacterium Halorubrum sodomense , was recently shown to function as a fluorescent indicator of membrane potential when expressed in mammalian neurons. Arch fluorescence, however, is very dim and is not optimal for applications in live-cell imaging. We used directed evolution to identify mutations that dramatically improve the absolute brightness of Arch, as confirmed biochemically and with live-cell imaging (in Escherichia coli and human embryonic kidney 293 cells). In some fluorescent Arch variants, the pK a of the protonated Schiff-base linkage to retinal is near neutral pH, a useful feature for voltage-sensing applications. These bright Arch variants enable labeling of biological membranes in the far-red/infrared and exhibit the furthest red-shifted fluorescence emission thus far reported for a fluorescent protein (maximal excitation/emission at ∼620 nm/730 nm).
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2014
    detail.hit.zdb_id: 209104-5
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  • 6
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 111, No. 23 ( 2014-06-10), p. 8553-8558
    Abstract: Susceptibility to chronic beryllium disease (CBD) is linked to certain HLA-DP molecules, including HLA-DP2. To elucidate the molecular basis of this association, we exposed mice transgenic (Tg) for HLA-DP2 to beryllium oxide (BeO) via oropharyngeal aspiration. As opposed to WT mice, BeO-exposed HLA-DP2 Tg mice developed mononuclear infiltrates in a peribronchovascular distribution that were composed of CD4 + T cells and included regulatory T (T reg ) cells. Beryllium-responsive, HLA-DP2–restricted CD4 + T cells expressing IFN-γ and IL-2 were present in BeO-exposed HLA-DP2 Tg mice and not in WT mice. Using Be-loaded HLA-DP2–peptide tetramers, we identified Be-specific CD4 + T cells in the mouse lung that recognize identical ligands as CD4 + T cells derived from the human lung. Importantly, a subset of HLA-DP2 tetramer-binding CD4 + T cells expressed forkhead box P3, consistent with the expansion of antigen-specific T reg cells. Depletion of T reg cells in BeO-exposed HLA-DP2 Tg mice exacerbated lung inflammation and enhanced granuloma formation. These findings document, for the first time to our knowledge, the development of a Be-specific adaptive immune response in mice expressing HLA-DP2 and the ability of T reg cells to modulate the beryllium-induced granulomatous immune response.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2014
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
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  • 7
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 49 ( 2020-12-08), p. 30949-30956
    Abstract: Mercury (Hg), a global contaminant, is emitted mainly in its elemental form Hg 0 to the atmosphere where it is oxidized to reactive Hg II compounds, which efficiently deposit to surface ecosystems. Therefore, the chemical cycling between the elemental and oxidized Hg forms in the atmosphere determines the scale and geographical pattern of global Hg deposition. Recent advances in the photochemistry of gas-phase oxidized Hg I and Hg II species postulate their photodissociation back to Hg 0 as a crucial step in the atmospheric Hg redox cycle. However, the significance of these photodissociation mechanisms on atmospheric Hg chemistry, lifetime, and surface deposition remains uncertain. Here we implement a comprehensive and quantitative mechanism of the photochemical and thermal atmospheric reactions between Hg 0 , Hg I , and Hg II species in a global model and evaluate the results against atmospheric Hg observations. We find that the photochemistry of Hg I and Hg II leads to insufficient Hg oxidation globally. The combined efficient photoreduction of Hg I and Hg II to Hg 0 competes with thermal oxidation of Hg 0 , resulting in a large model overestimation of 99% of measured Hg 0 and underestimation of 51% of oxidized Hg and ∼66% of Hg II wet deposition. This in turn leads to a significant increase in the calculated global atmospheric Hg lifetime of 20 mo, which is unrealistically longer than the 3–6-mo range based on observed atmospheric Hg variability. These results show that the Hg I and Hg II photoreduction processes largely offset the efficiency of bromine-initiated Hg 0 oxidation and reveal missing Hg oxidation processes in the troposphere.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 8
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 113, No. 24 ( 2016-06-14)
    Abstract: Prochlorococcus and Synechococcus are the two most abundant and widespread phytoplankton in the global ocean. To better understand the factors controlling their biogeography, a reference database of the high-resolution taxonomic marker p et B , encoding cytochrome b 6 , was used to recruit reads out of 109 metagenomes from the Tara Oceans expedition. An unsuspected novel genetic diversity was unveiled within both genera, even for the most abundant and well-characterized clades, and 136 divergent petB sequences were successfully assembled from metagenomic reads, significantly enriching the reference database. We then defined Ecologically Significant Taxonomic Units (ESTUs)—that is, organisms belonging to the same clade and occupying a common oceanic niche. Three major ESTU assemblages were identified along the cruise transect for Prochlorococcus and eight for Synechococcus . Although Prochlorococcus HLIIIA and HLIVA ESTUs codominated in iron-depleted areas of the Pacific Ocean, CRD1 and the yet-to-be cultured EnvB were the prevalent Synechococcus clades in this area, with three different CRD1 and EnvB ESTUs occupying distinct ecological niches with regard to iron availability and temperature. Sharp community shifts were also observed over short geographic distances—for example, around the Marquesas Islands or between southern Indian and Atlantic Oceans—pointing to a tight correlation between ESTU assemblages and specific physico-chemical parameters. Together, this study demonstrates that there is a previously overlooked, ecologically meaningful, fine-scale diversity within some currently defined picocyanobacterial ecotypes, bringing novel insights into the ecology, diversity, and biology of the two most abundant phototrophs on Earth.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2016
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