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Beckett SJ, Demory D, Coenen AR, Casey JR, Dugenne M, Follett CL, Connell P, Carlson MCG, Hu SK, Wilson ST, Muratore D, Rodriguez-Gonzalez RA, Peng S, Becker KW, Mende DR, Armbrust EV, Caron DA, Lindell D, White AE, Ribalet F, Weitz JS. Disentangling top-down drivers of mortality underlying diel population dynamics of Prochlorococcus in the North Pacific Subtropical Gyre. Nat Commun 2024; 15:2105. [PMID: 38453897 PMCID: PMC10920773 DOI: 10.1038/s41467-024-46165-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 02/16/2024] [Indexed: 03/09/2024] Open
Abstract
Photosynthesis fuels primary production at the base of marine food webs. Yet, in many surface ocean ecosystems, diel-driven primary production is tightly coupled to daily loss. This tight coupling raises the question: which top-down drivers predominate in maintaining persistently stable picocyanobacterial populations over longer time scales? Motivated by high-frequency surface water measurements taken in the North Pacific Subtropical Gyre (NPSG), we developed multitrophic models to investigate bottom-up and top-down mechanisms underlying the balanced control of Prochlorococcus populations. We find that incorporating photosynthetic growth with viral- and predator-induced mortality is sufficient to recapitulate daily oscillations of Prochlorococcus abundances with baseline community abundances. In doing so, we infer that grazers in this environment function as the predominant top-down factor despite high standing viral particle densities. The model-data fits also reveal the ecological relevance of light-dependent viral traits and non-canonical factors to cellular loss. Finally, we leverage sensitivity analyses to demonstrate how variation in life history traits across distinct oceanic contexts, including variation in viral adsorption and grazer clearance rates, can transform the quantitative and even qualitative importance of top-down controls in shaping Prochlorococcus population dynamics.
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Affiliation(s)
- Stephen J Beckett
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Department of Biology, University of Maryland, College Park, MD, USA.
| | - David Demory
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Sorbonne Université, CNRS, USR 3579, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, Banyuls-sur-Mer, France.
| | - Ashley R Coenen
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - John R Casey
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Mathilde Dugenne
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Sorbonne Université, CNRS, UMR 7093, Laboratoire d'Océanographie de Villefranche-sur-Mer (LOV), Villefranche-sur-Mer, France
| | - Christopher L Follett
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Paige Connell
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
- Biology Department, San Diego Mesa College, San Diego, CA, USA
| | - Michael C G Carlson
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
- Department of Biological Sciences, California State University, Long Beach, CA, USA
| | - Sarah K Hu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Oceanography, Texas A&M University, College Station, TX, USA
| | - Samuel T Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Daniel Muratore
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Santa Fe Institute, Santa Fe, NM, USA
| | | | - Shengyun Peng
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Adobe, San Jose, CA, USA
| | - Kevin W Becker
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Daniel R Mende
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Laboratory of Applied Evolutionary Biology, Department of Medical Microbiology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | | | - David A Caron
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Debbie Lindell
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Angelicque E White
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, HI, USA
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - François Ribalet
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Joshua S Weitz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Department of Biology, University of Maryland, College Park, MD, USA.
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA.
- Institut de Biologie, École Normale Supérieure, Paris, France.
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2
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Turk-Kubo KA, Mills MM, Arrigo KR, van Dijken G, Henke BA, Stewart B, Wilson ST, Zehr JP. UCYN-A/haptophyte symbioses dominate N 2 fixation in the Southern California Current System. ISME Commun 2021; 1:42. [PMID: 36740625 PMCID: PMC9723760 DOI: 10.1038/s43705-021-00039-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 02/07/2023]
Abstract
The availability of fixed nitrogen (N) is an important factor limiting biological productivity in the oceans. In coastal waters, high dissolved inorganic N concentrations were historically thought to inhibit dinitrogen (N2) fixation, however, recent N2 fixation measurements and the presence of the N2-fixing UCYN-A/haptophyte symbiosis in nearshore waters challenge this paradigm. We characterized the contribution of UCYN-A symbioses to nearshore N2 fixation in the Southern California Current System (SCCS) by measuring bulk community and single-cell N2 fixation rates, as well as diazotroph community composition and abundance. UCYN-A1 and UCYN-A2 symbioses dominated diazotroph communities throughout the region during upwelling and oceanic seasons. Bulk N2 fixation was detected in most surface samples, with rates up to 23.0 ± 3.8 nmol N l-1 d-1, and was often detected at the deep chlorophyll maximum in the presence of nitrate (>1 µM). UCYN-A2 symbiosis N2 fixation rates were higher (151.1 ± 112.7 fmol N cell-1 d-1) than the UCYN-A1 symbiosis (6.6 ± 8.8 fmol N cell-1 d-1). N2 fixation by the UCYN-A1 symbiosis accounted for a majority of the measured bulk rates at two offshore stations, while the UCYN-A2 symbiosis was an important contributor in three nearshore stations. This report of active UCYN-A symbioses and broad mesoscale distribution patterns establishes UCYN-A symbioses as the dominant diazotrophs in the SCCS, where heterocyst-forming and unicellular cyanobacteria are less prevalent, and provides evidence that the two dominant UCYN-A sublineages are separate ecotypes.
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Affiliation(s)
- Kendra A Turk-Kubo
- Ocean Sciences Department, University of California at Santa Cruz, Santa Cruz, CA, USA.
| | - Matthew M Mills
- Earth System Science, Stanford University, Stanford, CA, USA
| | - Kevin R Arrigo
- Earth System Science, Stanford University, Stanford, CA, USA
| | - Gert van Dijken
- Earth System Science, Stanford University, Stanford, CA, USA
| | - Britt A Henke
- Ocean Sciences Department, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - Brittany Stewart
- Ocean Sciences Department, University of California at Santa Cruz, Santa Cruz, CA, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Samuel T Wilson
- Center for Microbial Oceanography: Research and Education, University of Hawai'i at Manoa, Honolulu, HI, USA
| | - Jonathan P Zehr
- Ocean Sciences Department, University of California at Santa Cruz, Santa Cruz, CA, USA
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3
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Gradoville MR, Cabello AM, Wilson ST, Turk-Kubo KA, Karl DM, Zehr JP. Light and depth dependency of nitrogen fixation by the non-photosynthetic, symbiotic cyanobacterium UCYN-A. Environ Microbiol 2021; 23:4518-4531. [PMID: 34227720 PMCID: PMC9291983 DOI: 10.1111/1462-2920.15645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 11/28/2022]
Abstract
The symbiotic cyanobacterium UCYN‐A is one of the most globally abundant marine dinitrogen (N2)‐fixers, but cultures have not been available and its biology and ecology are poorly understood. We used cultivation‐independent approaches to investigate how UCYN‐A single‐cell N2 fixation rates (NFRs) and nifH gene expression vary as a function of depth and photoperiod. Twelve‐hour day/night incubations showed that UCYN‐A only fixed N2 during the day. Experiments conducted using in situ arrays showed a light‐dependence of NFRs by the UCYN‐A symbiosis, with the highest rates in surface waters (5–45 m) and lower rates at depth (≥ 75 m). Analysis of NFRs versus in situ light intensity yielded a light saturation parameter (Ik) for UCYN‐A of 44 μmol quanta m−2 s−1. This is low compared with other marine diazotrophs, suggesting an ecological advantage for the UCYN‐A symbiosis under low‐light conditions. In contrast to cell‐specific NFRs, nifH gene‐specific expression levels did not vary with depth, indicating that light regulates N2 fixation by UCYN‐A through processes other than transcription, likely including host–symbiont interactions. These results offer new insights into the physiology of the UCYN‐A symbiosis in the subtropical North Pacific Ocean and provide clues to the environmental drivers of its global distributions.
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Affiliation(s)
- Mary R Gradoville
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Ana M Cabello
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA.,Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, Fuengirola, Málaga, Spain
| | - Samuel T Wilson
- Department of Oceanography, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Kendra A Turk-Kubo
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
| | - David M Karl
- Department of Oceanography, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Jonathan P Zehr
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
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4
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Wilson ST, Caffin M, White AE, Karl DM. Evaluation of argon-induced hydrogen production as a method to measure nitrogen fixation by cyanobacteria. J Phycol 2021; 57:863-873. [PMID: 33450056 DOI: 10.1111/jpy.13129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 11/14/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
The production of dihydrogen (H2 ) is an enigmatic yet obligate component of biological dinitrogen (N2 ) fixation. This study investigates the effect on H2 production by N2 fixing cyanobacteria when they are exposed to either air or a gas mixture consisting of argon, oxygen, and carbon dioxide (Ar:O2 :CO2 ). In the absence of N2 , nitrogenase diverts the flow of electrons to the production of H2 , which becomes a measure of Total Nitrogenase Activity (TNA). This method of argon-induced hydrogen production (AIHP) is much less commonly used to infer rates of N2 fixation than the acetylene reduction (AR) assay. We provide here a full evaluation of the AIHP method and demonstrate its ability to achieve high-resolution measurements of TNA in a gas exchange flow-through system. Complete diel profiles of H2 production were obtained for N2 fixing cyanobacteria despite the absence of N2 that broadly reproduced the temporal patterns observed by the AR assay. Comparison of H2 production under air versus Ar:O2 :CO2 revealed the efficiency of electron usage during N2 fixation and place these findings in the broader context of cell metabolism. Ultimately, AIHP is demonstrated to be a viable alternative to the AR assay with several additional merits that provide an insight into cell physiology and promise for successful field application.
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Affiliation(s)
- Samuel T Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai'i at Manoa, Honolulu, Hawai'i, USA
| | - Mathieu Caffin
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai'i at Manoa, Honolulu, Hawai'i, USA
| | - Angelicque E White
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai'i at Manoa, Honolulu, Hawai'i, USA
| | - David M Karl
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai'i at Manoa, Honolulu, Hawai'i, USA
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5
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Zhang Y, Ryan JP, Hobson BW, Kieft B, Romano A, Barone B, Preston CM, Roman B, Raanan BY, Pargett D, Dugenne M, White AE, Freitas FH, Poulos S, Wilson ST, DeLong EF, Karl DM, Birch JM, Bellingham JG, Scholin CA. A system of coordinated autonomous robots for Lagrangian studies of microbes in the oceanic deep chlorophyll maximum. Sci Robot 2021; 6:6/50/eabb9138. [PMID: 34043577 DOI: 10.1126/scirobotics.abb9138] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 12/14/2020] [Indexed: 12/31/2022]
Abstract
The deep chlorophyll maximum (DCM) layer is an ecologically important feature of the open ocean. The DCM cannot be observed using aerial or satellite remote sensing; thus, in situ observations are essential. Further, understanding the responses of microbes to the environmental processes driving their metabolism and interactions requires observing in a reference frame that moves with a plankton population drifting in ocean currents, i.e., Lagrangian. Here, we report the development and application of a system of coordinated robots for studying planktonic biological communities drifting within the ocean. The presented Lagrangian system uses three coordinated autonomous robotic platforms. The focal platform consists of an autonomous underwater vehicle (AUV) fitted with a robotic water sampler. This platform localizes and drifts within a DCM community, periodically acquiring samples while continuously monitoring the local environment. The second platform is an AUV equipped with environmental sensing and acoustic tracking capabilities. This platform characterizes environmental conditions by tracking the focal platform and vertically profiling in its vicinity. The third platform is an autonomous surface vehicle equipped with satellite communications and subsea acoustic tracking capabilities. While also acoustically tracking the focal platform, this vehicle serves as a communication relay that connects the subsea robot to human operators, thereby providing situational awareness and enabling intervention if needed. Deployed in the North Pacific Ocean within the core of a cyclonic eddy, this coordinated system autonomously captured fundamental characteristics of the in situ DCM microbial community in a manner not possible previously.
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Affiliation(s)
- Yanwu Zhang
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA.
| | - John P Ryan
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - Brett W Hobson
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - Brian Kieft
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - Anna Romano
- University of Hawai'i at Mānoa, Honolulu, HI, USA
| | | | | | - Brent Roman
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - Ben-Yair Raanan
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - Douglas Pargett
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | | | | | | | - Steve Poulos
- University of Hawai'i at Mānoa, Honolulu, HI, USA
| | | | | | - David M Karl
- University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - James M Birch
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
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6
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Wilson ST, Hawco NJ, Armbrust EV, Barone B, Björkman KM, Boysen AK, Burgos M, Burrell TJ, Casey JR, DeLong EF, Dugenne M, Dutkiewicz S, Dyhrman ST, Ferrón S, Follows MJ, Foreman RK, Funkey CP, Harke MJ, Henke BA, Hill CN, Hynes AM, Ingalls AE, Jahn O, Kelly RL, Knapp AN, Letelier RM, Ribalet F, Shimabukuro EM, Tabata RKS, Turk-Kubo KA, White AE, Zehr JP, John S, Karl DM. Kīlauea lava fuels phytoplankton bloom in the North Pacific Ocean. Science 2019; 365:1040-1044. [DOI: 10.1126/science.aax4767] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/17/2019] [Indexed: 11/02/2022]
Affiliation(s)
- Samuel T. Wilson
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Nicholas J. Hawco
- Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | | | - Benedetto Barone
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Karin M. Björkman
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Angela K. Boysen
- School of Oceanography, University of Washington, Seattle, WA 98195, USA
| | - Macarena Burgos
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Timothy J. Burrell
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - John R. Casey
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Edward F. DeLong
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Mathilde Dugenne
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Stephanie Dutkiewicz
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sonya T. Dyhrman
- Department of Earth and Environmental Sciences, Columbia University, Palisades, NY 10964, USA
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
| | - Sara Ferrón
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Michael J. Follows
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Rhea K. Foreman
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Carolina P. Funkey
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Matthew J. Harke
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
| | - Britt A. Henke
- Department of Ocean Sciences, University of California, Santa Cruz, CA 95064, USA
| | - Christopher N. Hill
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Annette M. Hynes
- School of Oceanography, University of Washington, Seattle, WA 98195, USA
| | - Anitra E. Ingalls
- School of Oceanography, University of Washington, Seattle, WA 98195, USA
| | - Oliver Jahn
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Rachel L. Kelly
- Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Angela N. Knapp
- Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USA
| | - Ricardo M. Letelier
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Francois Ribalet
- School of Oceanography, University of Washington, Seattle, WA 98195, USA
| | - Eric M. Shimabukuro
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Ryan K. S. Tabata
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Kendra A. Turk-Kubo
- Department of Ocean Sciences, University of California, Santa Cruz, CA 95064, USA
| | - Angelicque E. White
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
| | - Jonathan P. Zehr
- Department of Ocean Sciences, University of California, Santa Cruz, CA 95064, USA
| | - Seth John
- Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - David M. Karl
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai‘i at Manoa, Honolulu, HI 96822, USA
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7
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Robidart JC, Magasin JD, Shilova IN, Turk-Kubo KA, Wilson ST, Karl DM, Scholin CA, Zehr JP. Effects of nutrient enrichment on surface microbial community gene expression in the oligotrophic North Pacific Subtropical Gyre. ISME J 2018; 13:374-387. [PMID: 30254320 DOI: 10.1038/s41396-018-0280-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 07/26/2018] [Accepted: 08/26/2018] [Indexed: 11/09/2022]
Abstract
Marine microbial communities are critical for biogeochemical cycles and the productivity of ocean ecosystems. Primary productivity in the surface ocean is constrained by nutrients which are supplied, in part, by mixing with deeper water. Little is known about the time scales, frequency, or impact of mixing on microbial communities. We combined in situ sampling using the Environmental Sample Processor and a small-scale mixing experiment with lower euphotic zone water to determine how individual populations respond to mixing. Transcriptional responses were measured using the MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories) microarray, which targets all three domains of life and viruses. The experiment showed that mixing substantially affects photosynthetic taxa as expected, but surprisingly also showed that populations respond differently to unfiltered deep water which contains particles (organisms and detritus) compared to filtered deep water that only contains nutrients and viruses, pointing to the impact of biological interactions associated with these events. Comparison between experimental and in situ population transcription patterns indicated that manipulated populations can serve as analogs for natural populations, and that natural populations may be frequently or continuously responding to nutrients from deeper waters. Finally, this study also shows that the microarray approach, which is complementary to metatranscriptomic sequencing, is useful for determining the physiological status of in situ microbial communities.
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Affiliation(s)
- J C Robidart
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA.,National Oceanography Centre, Southampton, UK
| | - J D Magasin
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA
| | - I N Shilova
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA.,Second Genome, South San Francisco, CA, USA
| | - K A Turk-Kubo
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA
| | - S T Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA.,Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - D M Karl
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA.,Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - C A Scholin
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - J P Zehr
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA.
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8
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Abstract
Mass production of plastics started nearly 70 years ago and the production rate is expected to double over the next two decades. While serving many applications because of their durability, stability and low cost, plastics have deleterious effects on the environment. Plastic is known to release a variety of chemicals during degradation, which has a negative impact on biota. Here, we show that the most commonly used plastics produce two greenhouse gases, methane and ethylene, when exposed to ambient solar radiation. Polyethylene, which is the most produced and discarded synthetic polymer globally, is the most prolific emitter of both gases. We demonstrate that the production of trace gases from virgin low-density polyethylene increase with time, with rates at the end of a 212-day incubation of 5.8 nmol g-1 d-1 of methane, 14.5 nmol g-1 d-1 of ethylene, 3.9 nmol g-1 d-1 of ethane and 9.7 nmol g-1 d-1 of propylene. Environmentally aged plastics incubated in water for at least 152 days also produced hydrocarbon gases. In addition, low-density polyethylene emits these gases when incubated in air at rates ~2 times and ~76 times higher than when incubated in water for methane and ethylene, respectively. Our results show that plastics represent a heretofore unrecognized source of climate-relevant trace gases that are expected to increase as more plastic is produced and accumulated in the environment.
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Affiliation(s)
- Sarah-Jeanne Royer
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, School of Ocean and Earth Science & Technology, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
- * E-mail: (SJR); (DMK)
| | - Sara Ferrón
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, School of Ocean and Earth Science & Technology, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Samuel T. Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, School of Ocean and Earth Science & Technology, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - David M. Karl
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, School of Ocean and Earth Science & Technology, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
- * E-mail: (SJR); (DMK)
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9
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Wilson ST, Aylward FO, Ribalet F, Barone B, Casey JR, Connell PE, Eppley JM, Ferrón S, Fitzsimmons JN, Hayes CT, Romano AE, Turk-Kubo KA, Vislova A, Armbrust EV, Caron DA, Church MJ, Zehr JP, Karl DM, DeLong EF. Coordinated regulation of growth, activity and transcription in natural populations of the unicellular nitrogen-fixing cyanobacterium Crocosphaera. Nat Microbiol 2017; 2:17118. [DOI: 10.1038/nmicrobiol.2017.118] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 06/23/2017] [Indexed: 01/01/2023]
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10
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Eichner MJ, Klawonn I, Wilson ST, Littmann S, Whitehouse MJ, Church MJ, Kuypers MM, Karl DM, Ploug H. Chemical microenvironments and single-cell carbon and nitrogen uptake in field-collected colonies of Trichodesmium under different pCO 2. ISME J 2017; 11:1305-1317. [PMID: 28398346 PMCID: PMC5437350 DOI: 10.1038/ismej.2017.15] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/19/2016] [Accepted: 01/09/2017] [Indexed: 11/20/2022]
Abstract
Gradients of oxygen (O2) and pH, as well as small-scale fluxes of carbon (C), nitrogen (N) and O2 were investigated under different partial pressures of carbon dioxide (pCO2) in field-collected colonies of the marine dinitrogen (N2)-fixing cyanobacterium Trichodesmium. Microsensor measurements indicated that cells within colonies experienced large fluctuations in O2, pH and CO2 concentrations over a day–night cycle. O2 concentrations varied with light intensity and time of day, yet colonies exposed to light were supersaturated with O2 (up to ~200%) throughout the light period and anoxia was not detected. Alternating between light and dark conditions caused a variation in pH levels by on average 0.5 units (equivalent to 15 nmol l−1 proton concentration). Single-cell analyses of C and N assimilation using secondary ion mass spectrometry (SIMS; large geometry SIMS and nanoscale SIMS) revealed high variability in metabolic activity of single cells and trichomes of Trichodesmium, and indicated transfer of C and N to colony-associated non-photosynthetic bacteria. Neither O2 fluxes nor C fixation by Trichodesmium were significantly influenced by short-term incubations under different pCO2 levels, whereas N2 fixation increased with increasing pCO2. The large range of metabolic rates observed at the single-cell level may reflect a response by colony-forming microbial populations to highly variable microenvironments.
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Affiliation(s)
- Meri J Eichner
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Isabell Klawonn
- Department of Ecology, Environment and Plant Sciences, University of Stockholm, Stockholm, Sweden
| | - Samuel T Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA
| | - Sten Littmann
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Martin J Whitehouse
- Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden
| | - Matthew J Church
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA
| | - Marcel Mm Kuypers
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - David M Karl
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA
| | - Helle Ploug
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
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11
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Rouco M, Haley ST, Alexander H, Wilson ST, Karl DM, Dyhrman ST. Variable depth distribution of Trichodesmium clades in the North Pacific Ocean. Environ Microbiol Rep 2016; 8:1058-1066. [PMID: 27753237 DOI: 10.1111/1758-2229.12488] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 10/04/2016] [Indexed: 06/06/2023]
Abstract
Populations of nitrogen-fixing cyanobacteria in the genus Trichodesmium are critical to ocean ecosystems, yet predicting patterns of Trichodesmium distribution and their role in ocean biogeochemistry is an ongoing challenge. This may, in part, be due to differences in the physiological ecology of Trichodesmium species, which are not typically considered independently in field studies. In this study, the abundance of the two dominant Trichodesmium clades (Clade I and Clade III) was investigated during a survey at Station ALOHA in the North Pacific Subtropical Gyre (NPSG) using a clade-specific qPCR approach. While Clade I dominated the Trichodesmium community, Clade III abundance was >50% in some NPSG samples, in contrast to the western North Atlantic where Clade III abundance was always <10%. Clade I populations were distributed down to depths >80 m, while Clade III populations were only observed in the mixed layer and found to be significantly correlated with depth and temperature. These data suggest active niche partitioning of Trichodesmium species from different clades, as has been observed in other cyanobacteria. Tracking the distribution and physiology of Trichodesmium spp. would contribute to better predictions of the physiological ecology of this biogeochemically important genus in the present and future ocean.
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Affiliation(s)
- Mónica Rouco
- Lamont-Doherty Earth Observatory, Columbia University, NY, USA
- Department of Earth and Environmental Sciences, Columbia University, NY, USA
| | - Sheean T Haley
- Lamont-Doherty Earth Observatory, Columbia University, NY, USA
| | - Harriet Alexander
- MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering, Cambridge, MA, 02139, USA
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA
| | - Samuel T Wilson
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, 96822, USA
| | - David M Karl
- Department of Oceanography, Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, 96822, USA
| | - Sonya T Dyhrman
- Lamont-Doherty Earth Observatory, Columbia University, NY, USA
- Department of Earth and Environmental Sciences, Columbia University, NY, USA
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12
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Braun A, Boudoire F, Bora DK, Faccio G, Hu Y, Kroll A, Mun BS, Wilson ST. Biological components and bioelectronic interfaces of water splitting photoelectrodes for solar hydrogen production. Chemistry 2014; 21:4188-99. [PMID: 25504590 DOI: 10.1002/chem.201405123] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Indexed: 11/09/2022]
Abstract
Artificial photosynthesis (AP) is inspired by photosynthesis in nature. In AP, solar hydrogen can be produced by water splitting in photoelectrochemical cells (PEC). The necessary photoelectrodes are inorganic semiconductors. Light-harvesting proteins and biocatalysts can be coupled with these photoelectrodes and thus form bioelectronic interfaces. We expand this concept toward PEC devices with vital bio-organic components and interfaces, and their integration into the built environment.
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Affiliation(s)
- Artur Braun
- Laboratory for High Performance Ceramics, Empa. Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland).
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Robidart JC, Church MJ, Ryan JP, Ascani F, Wilson ST, Bombar D, Marin R, Richards KJ, Karl DM, Scholin CA, Zehr JP. Ecogenomic sensor reveals controls on N2-fixing microorganisms in the North Pacific Ocean. ISME J 2014; 8:1175-85. [PMID: 24477197 DOI: 10.1038/ismej.2013.244] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/28/2013] [Accepted: 12/02/2013] [Indexed: 11/09/2022]
Abstract
Nitrogen-fixing microorganisms (diazotrophs) are keystone species that reduce atmospheric dinitrogen (N2) gas to fixed nitrogen (N), thereby accounting for much of N-based new production annually in the oligotrophic North Pacific. However, current approaches to study N2 fixation provide relatively limited spatiotemporal sampling resolution; hence, little is known about the ecological controls on these microorganisms or the scales over which they change. In the present study, we used a drifting robotic gene sensor to obtain high-resolution data on the distributions and abundances of N2-fixing populations over small spatiotemporal scales. The resulting measurements demonstrate that concentrations of N2 fixers can be highly variable, changing in abundance by nearly three orders of magnitude in less than 2 days and 30 km. Concurrent shipboard measurements and long-term time-series sampling uncovered a striking and previously unrecognized correlation between phosphate, which is undergoing long-term change in the region, and N2-fixing cyanobacterial abundances. These results underscore the value of high-resolution sampling and its applications for modeling the effects of global change.
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Affiliation(s)
- Julie C Robidart
- 1] Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA [2] Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA [3] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA
| | - Matthew J Church
- 1] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA [2] Department of Oceanography, University of Hawaii, Honolulu, HI, USA
| | - John P Ryan
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - François Ascani
- 1] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA [2] Department of Oceanography, University of Hawaii, Honolulu, HI, USA
| | - Samuel T Wilson
- 1] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA [2] Department of Oceanography, University of Hawaii, Honolulu, HI, USA
| | - Deniz Bombar
- 1] Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA [2] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA
| | - Roman Marin
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - Kelvin J Richards
- 1] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA [2] Department of Oceanography, University of Hawaii, Honolulu, HI, USA
| | - David M Karl
- 1] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA [2] Department of Oceanography, University of Hawaii, Honolulu, HI, USA
| | - Christopher A Scholin
- 1] Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA [2] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA
| | - Jonathan P Zehr
- 1] Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA [2] Center for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, HI, USA
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14
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Martínez A, Ventouras LA, Wilson ST, Karl DM, Delong EF. Metatranscriptomic and functional metagenomic analysis of methylphosphonate utilization by marine bacteria. Front Microbiol 2013; 4:340. [PMID: 24324460 PMCID: PMC3840354 DOI: 10.3389/fmicb.2013.00340] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 10/29/2013] [Indexed: 11/16/2022] Open
Abstract
Aerobic degradation of methylphosphonate (MPn) by marine bacterioplankton has been hypothesized to contribute significantly to the ocean's methane supersaturation, yet little is known about MPn utilization by marine microbes. To identify the microbial taxa and metabolic functions associated with MPn-driven methane production we performed parallel metagenomic, metatranscriptomic, and functional screening of microcosm perturbation experiments using surface water collected in the North Pacific Subtropical Gyre. In nutrient amended microcosms containing MPn, a substrate-driven microbial succession occurred. Initially, the addition of glucose and nitrate resulted in a bloom of Vibrionales and a transcriptional profile dominated by glucose-specific PTS transport and polyhydroxyalkanoate biosynthesis. Transcripts associated with phosphorus (P) acquisition were also overrepresented and suggested that the addition of glucose and nitrate had driven the community to P depletion. At this point, a second community shift occurred characterized by the increase in C-P lyase containing microbes of the Vibrionales and Rhodobacterales orders. Transcripts associated with C-P lyase components were among the most highly expressed at the community level, and only C-P lyase clusters were recovered in a functional screen for MPn utilization, consistent with this pathway being responsible for the majority, if not all, of the methane accumulation we observed. Our results identify specific bacterioplankton taxa that can utilize MPn aerobically under conditions of P limitation using the C-P lyase pathway, and thereby elicit a significant increase in the dissolved methane concentration.
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Affiliation(s)
- Asunción Martínez
- Division of Biological Engineering, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology Cambridge, MA, USA ; Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawaii Honolulu, HI, USA
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15
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Wilson ST, del Valle DA, Robidart JC, Zehr JP, Karl DM. Dissolved hydrogen and nitrogen fixation in the oligotrophic North Pacific Subtropical Gyre. Environ Microbiol Rep 2013; 5:697-704. [PMID: 24115620 PMCID: PMC4271820 DOI: 10.1111/1758-2229.12069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Revised: 04/26/2013] [Accepted: 05/05/2013] [Indexed: 06/02/2023]
Abstract
The production of hydrogen (H2) is an inherent component of biological dinitrogen (N2) fixation, and there have been several studies quantifying H2 production relative to N2 fixation in cultures of diazotrophs. However, conducting the relevant measurements for a field population is more complex as shown by this study of N2 fixation, H2 consumption and dissolved H2 concentrations in the oligotrophic North Pacific Ocean. Measurements of H2 oxidation revealed microbial consumption of H2 was equivalent to 1-7% of ethylene produced during the acetylene reduction assay and 11-63% of (15)N2 assimilation on a molar scale. Varying abundances of Crocosphaera and Trichodesmium as revealed by nifH gene abundances broadly corresponded with diel changes observed in both N2 fixation and H2 oxidation. However, no corresponding changes were observed in the dissolved H2 concentrations which remained consistently supersaturated (147-560%) relative to atmospheric equilibrium. The results from this field study allow the efficiency of H2 cycling by natural populations of diazotrophs to be compared to cultured representatives. The findings indicate that dissolved H2 concentrations may depend not only on the community composition of diazotrophs but also upon relevant environmental parameters such as light intensity or the presence of other H2-metabolizing microorganisms.
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Affiliation(s)
- Samuel T Wilson
- Department of Oceanography, School of Ocean and Earth Science and Technology, University of HawaiiHonolulu, HI, USA
- Center for Microbial Oceanography: Research and Education, University of HawaiiHonolulu, HI, USA
| | - Daniela A del Valle
- Department of Oceanography, School of Ocean and Earth Science and Technology, University of HawaiiHonolulu, HI, USA
- Center for Microbial Oceanography: Research and Education, University of HawaiiHonolulu, HI, USA
| | - Julie C Robidart
- Center for Microbial Oceanography: Research and Education, University of HawaiiHonolulu, HI, USA
- Ocean Sciences Department, University of California, Santa CruzCA, USA
| | - Jonathan P Zehr
- Center for Microbial Oceanography: Research and Education, University of HawaiiHonolulu, HI, USA
- Ocean Sciences Department, University of California, Santa CruzCA, USA
| | - David M Karl
- Department of Oceanography, School of Ocean and Earth Science and Technology, University of HawaiiHonolulu, HI, USA
- Center for Microbial Oceanography: Research and Education, University of HawaiiHonolulu, HI, USA
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Wilson ST, Kolber ZS, Tozzi S, Zehr JP, Karl DM. NITROGEN FIXATION, HYDROGEN CYCLING, AND ELECTRON TRANSPORT KINETICS IN TRICHODESMIUM ERYTHRAEUM (CYANOBACTERIA) STRAIN IMS101(1). J Phycol 2012; 48:595-606. [PMID: 27011075 DOI: 10.1111/j.1529-8817.2012.01166.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This study describes the relationships between dinitrogen (N2 ) fixation, dihydrogen (H2 ) production, and electron transport associated with photosynthesis and respiration in the marine cyanobacterium Trichodesmium erythraeum Ehrenb. strain IMS101. The ratio of H2 produced:N2 fixed (H2 :N2 ) was controlled by the light intensity and by the light spectral composition and was affected by the growth irradiance level. For Trichodesmium cells grown at 50 μmol photons · m(-2) · s(-1) , the rate of N2 fixation, as measured by acetylene reduction, saturated at light intensities of 200 μmol photons · m(-2) · s(-1) . In contrast, net H2 production continued to increase with light levels up to 1,000 μmol photons · m(-2) · s(-1) . The H2 :N2 ratios increased monotonically with irradiance, and the variable fluorescence measured using a fast repetition rate fluorometer (FRRF) revealed that this increase was accompanied by a progressive reduction of the plastoquinone (PQ) pool. Additions of 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), an inhibitor of electron transport from PQ pool to PSI, diminished both N2 fixation and net H2 production, while the H2 :N2 ratio increased with increasing level of PQ pool reduction. In the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), nitrogenase activity declined but could be prolonged by increasing the light intensity and by removing the oxygen supply. These results on the coupling of N2 fixation and H2 cycling in Trichodesmium indicate how light intensity and light spectral quality of the open ocean can influence the H2 :N2 ratio and modulate net H2 production.
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Affiliation(s)
- Samuel T Wilson
- Center for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USAOcean Sciences, University of California, Santa Cruz, California 95064, USACenter for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USA
| | - Zbigniew S Kolber
- Center for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USAOcean Sciences, University of California, Santa Cruz, California 95064, USACenter for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USA
| | - Sasha Tozzi
- Center for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USAOcean Sciences, University of California, Santa Cruz, California 95064, USACenter for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USA
| | - Jonathan P Zehr
- Center for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USAOcean Sciences, University of California, Santa Cruz, California 95064, USACenter for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USA
| | - David M Karl
- Center for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USAOcean Sciences, University of California, Santa Cruz, California 95064, USACenter for Microbial Oceanography: Research and Education, University of Hawaii, 1950 East-West Road, Honolulu, Hawaii 96822, USA
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17
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Wilson ST, Tozzi S, Foster RA, Ilikchyan I, Kolber ZS, Zehr JP, Karl DM. Hydrogen cycling by the unicellular marine diazotroph Crocosphaera watsonii strain WH8501. Appl Environ Microbiol 2010; 76:6797-803. [PMID: 20709832 PMCID: PMC2953037 DOI: 10.1128/aem.01202-10] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 08/07/2010] [Indexed: 11/20/2022] Open
Abstract
The hydrogen (H₂) cycle associated with the dinitrogen (N₂) fixation process was studied in laboratory cultures of the marine cyanobacterium Crocosphaera watsonii. The rates of H₂ production and acetylene (C₂H₂) reduction were continuously measured over the diel cycle with simultaneous measurements of fast repetition rate fluorometry and dissolved oxygen. The maximum rate of H₂ production was coincident with the maximum rates of C₂H₂ reduction. Theoretical stoichiometry for N₂ fixation predicts an equimolar ratio of H₂ produced to N₂ fixed. However, the maximum rate of net H₂ production observed was 0.09 nmol H₂ μg chlorophyll a (chl a)⁻¹ h⁻¹) compared to the N₂ fixation rate of 5.5 nmol N₂ μg chl a⁻¹ h⁻¹, with an H₂ production/N₂ fixation ratio of 0.02. The 50-fold discrepancy between expected and observed rates of H₂ production was hypothesized to be a result of H₂ reassimilation by uptake hydrogenase. This was confirmed by the addition of carbon monoxide (CO), a potent inhibitor of hydrogenase, which increased net H₂ production rates ∼40-fold to a maximum rate of 3.5 nmol H₂ μg chl a⁻¹ h⁻¹. We conclude that the reassimilation of H₂ by C. watsonii is highly efficient (> 98%) and hypothesize that the tight coupling between H₂ production and consumption is a consequence of fixing N₂ at nighttime using a finite pool of respiratory carbon and electrons acquired from daytime solar energy capture. The H₂ cycle provides unique insight into N₂ fixation and associated metabolic processes in C. watsonii.
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Affiliation(s)
- Samuel T Wilson
- Department of Oceanography, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822, USA.
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Fertuck EA, Jekal A, Song I, Wyman B, Morris MC, Wilson ST, Brodsky BS, Stanley B. Enhanced 'Reading the Mind in the Eyes' in borderline personality disorder compared to healthy controls. Psychol Med 2009; 39:1979-1988. [PMID: 19460187 PMCID: PMC3427787 DOI: 10.1017/s003329170900600x] [Citation(s) in RCA: 191] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Borderline personality disorder (BPD) is partly characterized by chronic instability in interpersonal relationships, which exacerbates other symptom dimensions of the disorder and can interfere with treatment engagement. Facial emotion recognition paradigms have been used to investigate the bases of interpersonal impairments in BPD, yielding mixed results. We sought to clarify and extend past findings by using the Reading the Mind in the Eyes Test (RMET), a measure of the capacity to discriminate the mental state of others from expressions in the eye region of the face. METHOD Thirty individuals diagnosed with BPD were compared to 25 healthy controls (HCs) on RMET performance. Participants were also assessed for depression severity, emotional state at the time of assessment, history of childhood abuse, and other Axis I and personality disorders (PDs). RESULTS The BPD group performed significantly better than the HC group on the RMET, particularly for the Total Score and Neutral emotional valences. Effect sizes were in the large range for the Total Score and for Neutral RMET performance. The results could not be accounted for by demographics, co-occurring Axis I or II conditions, medication status, abuse history, or emotional state. However, depression severity partially mediated the relationship between RMET and BPD status. CONCLUSIONS Mental state discrimination based on the eye region of the face is enhanced in BPD. An enhanced sensitivity to the mental states of others may be a basis for the social impairments in BPD.
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Affiliation(s)
- E A Fertuck
- Department of Psychiatry, Columbia University/New York State Psychiatric Institute, New York, NY 10032, USA.
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Comer SD, Collins ED, Wilson ST, Donovan MR, Foltin RW, Fischman MW. Effects of an alternative reinforcer on intravenous heroin self-administration by humans. Eur J Pharmacol 1998; 345:13-26. [PMID: 9593589 DOI: 10.1016/s0014-2999(97)01572-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Five heroin-dependent research volunteers, maintained on divided daily oral morphine doses, participated in an inpatient study designed to evaluate intravenous (i.v.) heroin self-administration when money ($10, $20 or $40) was concurrently available. Each morning participants received a single injection of heroin (placebo, 6.25, 12.5, 25, or 50 mg/70 kg, i.v.) and each afternoon, they had the opportunity to self-administer all or part of the morning dose. Participants responded under a progressive-ratio schedule (50, 100, ..., 2800) during a 10-trial self-administration task. During each trial, participants could respond for 1/10th of the sampled heroin dose or 1/10th of a single money value. The progressive-ratio value increased independently for each option. The total amount of heroin and/or money chosen during the self-administration task was administered at the end of the task. Heroin dose-dependently increased ratings of 'good drug effect' and 'high', impaired task performance and decreased pupil diameter and blood oxygen saturation. Heroin also dose-dependently increased progressive-ratio break point values, which varied as a function of the alternative money amount. Consistent with previous studies, the present results demonstrate that alternative reinforcers, depending on magnitude, are effective in reducing heroin use in opioid-dependent individuals.
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Affiliation(s)
- S D Comer
- Division on Substance Abuse, New York State Psychiatric Institute, New York 10032, USA.
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20
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Blask DE, Wilson ST, Zalatan F. Physiological melatonin inhibition of human breast cancer cell growth in vitro: evidence for a glutathione-mediated pathway. Cancer Res 1997; 57:1909-14. [PMID: 9157984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Melatonin, the chief hormone secreted by the pineal gland, has been previously shown to inhibit human breast cancer cell growth at the physiological concentration of 1 nM in vitro. In this study, using the estrogen receptor (ER)-positive human breast tumor cell line MCF-7, we have shown that 10 microM L-buthionine-[S,R]-sulfoximine (L-BSO), an inhibitor of gamma-glutamylcysteine synthetase (the rate-limiting enzyme in glutathione synthesis), blocks the oncostatic action of 1 nM melatonin over a 5-day incubation, indicating that glutathione is required for melatonin action. The result was repeated with ZR75-1 cells, suggesting that the glutathione requirement is a general phenomenon among ER+ breast cancer cells. Addition of exogenous glutathione (1 microM) to L-BSO-treated groups restored the melatonin response in both cell lines. Further demonstration of the importance of glutathione was shown using the ER- breast tumor cell line HS578T, which is normally unresponsive to melatonin. Growth in this cell line was inhibited in the presence of 1 microM ethacrynic acid (an inhibitor of glutathione S-transferase) plus 1 nM melatonin, and this effect was blocked with 10 microM L-BSO. We also observed a steady decrease of intracellular glutathione in MCF-7 cells over a 5-day incubation, suggesting that these cells metabolize glutathione differently than do normal cells.
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Affiliation(s)
- D E Blask
- Bassett Research Institute, Cooperstown, New York 13326-1394, USA
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Abstract
Cultured MCF-7 human breast cancer cells were pre-exposed to either melatonin (232 ng/mL) or vehicle for 24 hrs prior to being washed and then re-exposed to either ethanol-vehicle or varying concentrations of tamoxifen (37.1 ng/mL, 3.71 micrograms/mL, 371 micrograms/mL) or melatonin (2.32 pg/mL, 232 ng/mL, 23.2 ng/mL) for 5 additional days. Only 371 ng/mL tamoxifen caused a 38% growth inhibition of cells pre-exposed to vehicle whereas all concentrations of tamoxifen inhibited the growth of melatonin pre-exposed cells by 28% to 61% in a dose-dependent manner. Melatonin pre-exposure, potentiated the inhibitory effect of only 232 ng/mL melatonin. Comparison of IC50 values indicate that tamoxifen is approximately a 100 times more potent inhibitor of breast cancer cell growth following the pretreatment of cells with a physiological concentration of melatonin. These results indicate that melatonin has the capability to augment the inhibitory actions of tamoxifen, and to a lesser extent itself, on human breast cancer cell growth.
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Affiliation(s)
- S T Wilson
- Mary Imogene Bassett Hospital, Research Institute, Cooperstown, New York 13326-1394
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22
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Blask DE, Lemus-Wilson AM, Wilson ST. Breast cancer: a model system for studying the neuroendocrine role of pineal melatonin in oncology. Biochem Soc Trans 1992; 20:309-11. [PMID: 1397617 DOI: 10.1042/bst0200309] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- D E Blask
- Mary Imogene Bassett Hospital, Research Institute, Cooperstown, New York 13326-1394
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23
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Blask DE, Pelletier DB, Hill SM, Lemus-Wilson A, Grosso DS, Wilson ST, Wise ME. Pineal melatonin inhibition of tumor promotion in the N-nitroso-N-methylurea model of mammary carcinogenesis: potential involvement of antiestrogenic mechanisms in vivo. J Cancer Res Clin Oncol 1991; 117:526-32. [PMID: 1744157 DOI: 10.1007/bf01613283] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The N-methyl-N-nitrosourea (NMU) model of hormone-responsive rat mammary carcinogenesis was used to address the hypothesis that melatonin (Mel), the principle hormone of the pineal gland, inhibits tumorigenesis by acting as an anti-promoting rather than an anti-initiating agent. Daily late-afternoon injections of Mel (500 micrograms/day), restricted to the initiation phase of NMU mammary tumorigenesis, were ineffective in altering tumor growth over a 20-week period. When Mel treatment was delayed for 4 weeks after NMU and then continued through the remainder of the promotion phase, only tumor number was significantly lower than in controls. However, when Mel injections encompassed the entire promotion phase, both tumor incidence and number were significantly lower than in the controls. Although elimination of the endogenous Mel signal via pinealectomy promoted tumor growth, the effect was not statistically significant. Serum levels of estradiol and tumor estrogen receptor content were unaltered by either Mel or pinealectomy. While Mel treatment failed to affect circulating prolactin levels, pinealectomy caused a two-fold increase in serum prolactin. The estradiol-stimulated recrudescence of tumors following ovariectomy was completely blocked by either 20, 100 or 500 micrograms Mel/day or tamoxifen (20 micrograms/day). Thus, Mel appears to be an anti-promoting hormone that may antagonize the tumor-promoting actions of estradiol in this model of mammary tumorigenesis.
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Affiliation(s)
- D E Blask
- Department of Anatomy, University of Arizona, Tucson 85724
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