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  • Dissolved organic carbon  (2)
  • evolution  (2)
  • 05.04. Instrumentation and techniques of general interest  (1)
  • Oxford University Press  (3)
  • Cambridge University Press  (2)
  • 2020-2023  (5)
  • 1
    Publication Date: 2022-10-26
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Xu, L., Roberts, M., Elder, K., Hansman, R., Gagnon, A., & Kurz, M. Radiocarbon in dissolved organic carbon by UV oxidation: an update of procedures and blank characterization at NOSAMS. Radiocarbon, 64(1), (2022): 195-199, https://doi.org/10.1017/rdc.2022.4.
    Description: This note describes improvements of UV oxidation method that is used to measure carbon isotopes of dissolved organic carbon (DOC) at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS). The procedural blank is reduced to 2.6 ± 0.6 μg C, with Fm of 0.42 ± 0.10 and δ13C of –28.43 ± 1.19‰. The throughput is improved from one sample per day to two samples per day.
    Description: We gratefully acknowledge support from the U.S. National Science Foundation, via NSF-OCE-1755125.
    Keywords: Blank ; Dissolved organic carbon ; Radiocarbon ; UV-oxidation
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Xu, X., Li, G., Li, C., Zhang, J., Wang, Q., Simmons, D. K., Chen, X., Wijesena, N., Zhu, W., Wang, Z., Wang, Z., Ju, B., Ci, W., Lu, X., Yu, D., Wang, Q., Aluru, N., Oliveri, P., Zhang, Y. E., Martindale, M. Q., & Liu, J. Evolutionary transition between invertebrates and vertebrates via methylation reprogramming in embryogenesis. National Science Review, 6(5), (2019):993-1003, doi:10.1093/nsr/nwz064.
    Description: Major evolutionary transitions are enigmas, and the most notable enigma is between invertebrates and vertebrates, with numerous spectacular innovations. To search for the molecular connections involved, we asked whether global epigenetic changes may offer a clue by surveying the inheritance and reprogramming of parental DNA methylation across metazoans. We focused on gametes and early embryos, where the methylomes are known to evolve divergently between fish and mammals. Here, we find that methylome reprogramming during embryogenesis occurs neither in pre-bilaterians such as cnidarians nor in protostomes such as insects, but clearly presents in deuterostomes such as echinoderms and invertebrate chordates, and then becomes more evident in vertebrates. Functional association analysis suggests that DNA methylation reprogramming is associated with development, reproduction and adaptive immunity for vertebrates, but not for invertebrates. Interestingly, the single HOX cluster of invertebrates maintains unmethylated status in all stages examined. In contrast, the multiple HOX clusters show dramatic dynamics of DNA methylation during vertebrate embryogenesis. Notably, the methylation dynamics of HOX clusters are associated with their spatiotemporal expression in mammals. Our study reveals that DNA methylation reprogramming has evolved dramatically during animal evolution, especially after the evolutionary transitions from invertebrates to vertebrates, and then to mammals.
    Description: This work was supported by the National Key Research and Development Program of China (2018YFC1003303), the Strategic Priority Research Program of the CAS (XDB13040200), the National Natural Science Foundation of China (91519306, 31425015), the Youth Innovation Promotion Association of the CAS and the Key Research Program of Frontier Sciences, CAS (QYZDY-SSW-SMC016).
    Keywords: DNA methylation ; evolution ; development ; reprogramming
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2022-10-26
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Druffel, E., Beaupre, S., Grotheer, H., Lewis, C., McNichol, A., Mollenhauer, G., & Walker, B. Marine organic carbon and radiocarbon – present and future challenges. Radiocarbon, (2022): 1-17, https://doi.org/10.1017/RDC.2021.105.
    Description: We discuss present and developing techniques for studying radiocarbon in marine organic carbon (C). Bulk DOC (dissolved organic C) Δ14C measurements reveal information about the cycling time and sources of DOC in the ocean, yet they are time consuming and need to be streamlined. To further elucidate the cycling of DOC, various fractions have been separated from bulk DOC, through solid phase extraction of DOC, and ultrafiltration of high and low molecular weight DOC. Research using 14C of DOC and particulate organic C separated into organic fractions revealed that the acid insoluble fraction is similar in 14C signature to that of the lipid fraction. Plans for utilizing this methodology are described. Studies using compound specific radiocarbon analyses to study the origin of biomarkers in the marine environment are reviewed and plans for the future are outlined. Development of ramped pyrolysis oxidation methods are discussed and scientific questions addressed. A modified elemental analysis (EA) combustion reactor is described that allows high particulate organic C sample throughput by direct coupling with the MIniCArbonDAtingSystem.
    Keywords: CSRA ; Dissolved organic carbon ; Methodology ; Organic carbon ; Radiocarbon
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
    Publication Date: 2022-08-26
    Description: This article has been accepted for publication in Geophysical Journal International ©: The Authors 2022. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Uploaded in accordance with the publisher's self-archiving policy.
    Description: Defining the regional variability of minimum magnitude for earthquake detection is crucial for planning seismic networks. Knowing the earthquake detection magnitude values is fundamental for the optimal location of new stations and to select the priority for reactivating the stations of a seismic network in case of a breakdown. In general, the assessment of earthquake detection is performed by analysing seismic noise with spectral or more sophisticated methods. Further, to simulate amplitude values at the recording sites, spectral methods require knowledge of several geophysical parameters including rock density, S-wave velocity, corner frequency, quality factor, site specific decay parameter and so on, as well as a velocity model for the Earth's interior. The simulation results are generally expressed in terms of Mw and therefore a further conversion must be done to obtain the values of local magnitude (ML), which is the parameter commonly used for moderate and small earthquakes in seismic catalogues. Here, the relationship utilized by a seismic network to determine ML is directly applied to obtain the expected amplitude [in mm, as if it were recorded by a Wood–Anderson (WA) seismometer] at the recording site, without any additional assumptions. The station detection estimates are obtained by simply considering the ratio of the expected amplitude with respect to the background noise, also measured in mm. The seismic noise level for the station is estimated starting from four waveforms (each signal lasting 1 min) sampled at various times of the day for a period of one week. The proposed method is tested on Italian seismic events occurring in 2019 by using the locations of 16.879 earthquakes recorded by 374 stations. The first results indicate that by evaluating the station noise level with 5-s windows, a representative sample of the variability in expected noise level is generated for every station, even if only 4 min of signal per day over a week of recordings is used. The method was applied to define the detection level of the Italian National Seismic Network (RSN). The RSN detection level represents a reference for the definition and application of guidelines in the field of monitoring of subsurface industrial activities in Italy. The proposed approach can be successfully applied to define the current performance of a local seismic network (managed by private companies) and to estimate the expected further improvements, requested to fulfil the guidelines with the installation of new seismic stations. This method has been tested in Italy and can be reproduced wherever the local magnitude ML, based on synthetic WA records, is used.
    Description: Published
    Description: 1283–1297
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: Time-series analysis ; Earthquake ground motions ; Seismic noise ; Induced seismicity ; 04.06. Seismology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2022-05-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Lamb, D. C., Hargrove, T. Y., Zhao, B., Wawrzak, Z., Goldstone, J. V., Nes, W. D., Kelly, S. L., Waterman, M. R., Stegeman, J. J., & Lepesheva, G. I. Concerning P450 evolution: structural analyses support bacterial origin of sterol 14α-demethylases. Molecular Biology and Evolution, (2020): msaa260, doi:10.1093/molbev/msaa260.
    Description: Sterol biosynthesis, primarily associated with eukaryotic kingdoms of life, occurs as an abbreviated pathway in the bacterium Methylococcus capsulatus. Sterol 14α-demethylation is an essential step in this pathway and is catalyzed by cytochrome P450 51 (CYP51). In M. capsulatus, the enzyme consists of the P450 domain naturally fused to a ferredoxin domain at the C-terminus (CYP51fx). The structure of M. capsulatus CYP51fx was solved to 2.7 Å resolution and is the first structure of a bacterial sterol biosynthetic enzyme. The structure contained one P450 molecule per asymmetric unit with no electron density seen for ferredoxin. We connect this with the requirement of P450 substrate binding in order to activate productive ferredoxin binding. Further, the structure of the P450 domain with bound detergent (which replaced the substrate upon crystallization) was solved to 2.4 Å resolution. Comparison of these two structures to the CYP51s from human, fungi, and protozoa reveals strict conservation of the overall protein architecture. However, the structure of an “orphan” P450 from nonsterol-producing Mycobacterium tuberculosis that also has CYP51 activity reveals marked differences, suggesting that loss of function in vivo might have led to alterations in the structural constraints. Our results are consistent with the idea that eukaryotic and bacterial CYP51s evolved from a common cenancestor and that early eukaryotes may have recruited CYP51 from a bacterial source. The idea is supported by bioinformatic analysis, revealing the presence of CYP51 genes in 〉1,000 bacteria from nine different phyla, 〉50 of them being natural CYP51fx fusion proteins.
    Description: The study was supported by National Institutes of Health (Grant No. R01 GM067871 to G.I.L.) and by a UK-USA Fulbright Scholarship and the Royal Society (to D.C.L.).
    Keywords: sterol biosynthesis ; evolution ; cytochrome P450 ; CYP51 redox partner ; crystallography
    Repository Name: Woods Hole Open Access Server
    Type: Article
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