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Cassar N, Tang W, Gabathuler H, Huang K. Method for High Frequency Underway N 2 Fixation Measurements: Flow-Through Incubation Acetylene Reduction Assays by Cavity Ring Down Laser Absorption Spectroscopy (FARACAS). Anal Chem 2018; 90:2839-2851. [PMID: 29338196 DOI: 10.1021/acs.analchem.7b04977] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Because of the difficulty in resolving the large variability of N2 fixation with current methods which rely on discrete sampling, the development of new methods for high-resolution measurements is highly desirable. We present a new method for high-frequency measurements of aquatic N2 fixation by continuous flow-through incubations and spectral monitoring of the acetylene (C2H2, a substrate analog for N2) reduction to ethylene (C2H4). In this method, named Flow-through Incubation Acetylene Reduction Assays by Cavity Ring-Down Laser Absorption Spectroscopy (FARACAS), dissolved C2H2 is continuously admixed with seawater upstream of a continuous-flow stirred-tank reactor (CFSR) in which C2H2 reduction takes place. Downstream of the flow-through incubator, the C2H4 gas is stripped using a bubble column contactor and circulated with a diaphragm pump into a wavelength-scanned cavity ring down laser absorption spectrometer (CRDS). Our method provides high-resolution and precise mapping of aquatic N2 fixation, its diel cycle, and its response to environmental gradients, and can be adapted to measure other biological processes. The short-duration of the flow-through incubations without preconcentration of cells minimizes potential artifacts such as bottle containment effects while providing near real-time estimates for adaptive sampling. We expect that our new method will improve the characterization of the biogeography and kinetics of aquatic N2 fixation rates.
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Affiliation(s)
- Nicolas Cassar
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States.,Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM) , Brest, France
| | - Weiyi Tang
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States
| | | | - Kuan Huang
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States
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Ferreira D, Stal LJ, Moradas-Ferreira P, Mendes MV, Tamagnini P. THE RELATION BETWEEN N2 FIXATION AND H2 METABOLISM IN THE MARINE FILAMENTOUS NONHETEROCYSTOUS CYANOBACTERIUM LYNGBYA AESTUARII CCY 9616(1). JOURNAL OF PHYCOLOGY 2009; 45:898-905. [PMID: 27034220 DOI: 10.1111/j.1529-8817.2009.00714.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The marine filamentous nonheterocystous nitrogen-fixing cyanobacterium Lyngbya aestuarii (F. K. Mert.) Liebman ex Gomont CCY 9616 was grown under diazotrophic and nondiazotrophic conditions and under an alternating 16:8 light:dark (L:D) regime. Nitrogenase activity appeared just before the onset of the dark period, reaching its maximum 1-2 h in the dark, subsequently decreasing to zero at the beginning of the following light period. Nitrogenase activity was only detected at low levels of O2 (5%) and when the culture was grown in the absence of combined nitrogen. Quantitative reverse transcriptase-PCR (RT-PCR) analysis of one of the structural genes encoding nitrogenase, nifK, showed that the highest levels of transcription preceded the maximum activity of nitrogenase by 2-4 h. nifK transcription was not completely abolished during the remaining time of the 24 h cycle. Even in the presence of nitrate, when nitrogenase activity was undetectable, nifK was still transcribed. The H2 -uptake activity seemed to follow the nitrogenase, but the transcription of hupL (gene encoding the large subunit of uptake hydrogenase) preceded the nifK transcription. However, H2 -uptake and hupL transcription occurred throughout the 24 h cycle as well as under nondiazotrophic conditions, albeit at much lower levels. The hoxH transcript levels (a structural gene coding for the bidirectional hydrogenase) were similar under diazotrophic or nondiazotrophic conditions but slightly higher during the dark period. All three enzymes investigated are involved in H2 metabolism. It is concluded that the uptake hydrogenase is mainly responsible for H2 uptake. Nevertheless, uptake hydrogenase and nitrogenase do not seem to be coregulated.
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Affiliation(s)
- Daniela Ferreira
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, PortugalDepartment of Marine Microbiology, NIOO-KNAW, PO Box 140, 4400 AC Yerseke, the NetherlandsIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Largo Abel Salazar 2, 4099-003 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, Portugal
| | - Lucas J Stal
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, PortugalDepartment of Marine Microbiology, NIOO-KNAW, PO Box 140, 4400 AC Yerseke, the NetherlandsIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Largo Abel Salazar 2, 4099-003 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, Portugal
| | - Pedro Moradas-Ferreira
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, PortugalDepartment of Marine Microbiology, NIOO-KNAW, PO Box 140, 4400 AC Yerseke, the NetherlandsIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Largo Abel Salazar 2, 4099-003 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, Portugal
| | - Marta V Mendes
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, PortugalDepartment of Marine Microbiology, NIOO-KNAW, PO Box 140, 4400 AC Yerseke, the NetherlandsIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Largo Abel Salazar 2, 4099-003 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, Portugal
| | - Paula Tamagnini
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, PortugalDepartment of Marine Microbiology, NIOO-KNAW, PO Box 140, 4400 AC Yerseke, the NetherlandsIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Largo Abel Salazar 2, 4099-003 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, PortugalIBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal Faculdade de Ciências, Universidade do Porto, Departamento de Botânica, Edifício FC4, Rua do Campo Alegre, s/nº 4169-007 Porto, Portugal
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