Nutrients, pigments, silicate and experimental data collected aboard the OCEANUS during cruise OC1504A in the North Pacific Ocean from 2015-04-19 to 2015-05-06

Dataset: MUSiCC OC1504A - Nutrients, CTD, and silicon biogeochemical dataThese data include nutrient, pigment, silica and experimental data collected aboard the OCEANUS during cruise OC1504A in the North Pacific Ocean along the California Coast from 2015-04-19 to 2015-05-06. The water samples were collected by CTDs. Silica production rates were characterized by delivering incremental increases in silicic acid (Si) along with a radioactive isotope of silicon (32Si). This is an extremely sensitive assay and can determine the maximum production rates of the community being studied and the degree that its growth is being limited by lack of Si. These data were collected by Mark Brzezinski from the University of California at Santa Barbara as part of Linking Physiological and Molecular Aspects of Diatom Silicification. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/650831NSF Division of Ocean Sciences (NSF OCE) OCE-133438

Different iron storage strategies among bloom-forming diatoms

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 115(52), (2018): E12275-E12284. doi: 10.1073/pnas.1805243115.Diatoms are prominent eukaryotic phytoplankton despite being limited by the micronutrient iron in vast expanses of the ocean. As iron inputs are often sporadic, diatoms have evolved mechanisms such as the ability to store iron that enable them to bloom when iron is resupplied and then persist when low iron levels are reinstated. Two iron storage mechanisms have been previously described: the protein ferritin and vacuolar storage. To investigate the ecological role of these mechanisms among diatoms, iron addition and removal incubations were conducted using natural phytoplankton communities from varying iron environments. We show that among the predominant diatoms, Pseudo-nitzschia were favored by iron removal and displayed unique ferritin expression consistent with a long-term storage function. Meanwhile, Chaetoceros and Thalassiosira gene expression aligned with vacuolar storage mechanisms. Pseudo-nitzschia also showed exceptionally high iron storage under steady-state high and low iron conditions, as well as following iron resupply to iron-limited cells. We propose that bloom-forming diatoms use different iron storage mechanisms and that ferritin utilization may provide an advantage in areas of prolonged iron limitation with pulsed iron inputs. As iron distributions and availability change, this speculated ferritin-linked advantage may result in shifts in diatom community composition that can alter marine ecosystems and biogeochemical cycles.We thank the captain and crew of the R/V Melville and the CCGS J. P. Tully as well as the participants of the IRNBRU (MV1405) cruise for the California-based data, particularly K. Ellis [University of North Carolina (UNC)], T. Coale (University of California, San Diego), F. Kuzminov (Rutgers), H. McNair [University of California, Santa Barbara (UCSB)], and J. Jones (UCSB). W. Burns (UNC), S. Haines (UNC), and S. Bargu (Louisiana State University) assisted with sample processing and analysis. This work was funded by the National Science Foundation Grants OCE-1334935 (to A.M.), OCE-1334632 (to B.S.T.), OCE-1333929 (to K.T.), OCE-1334387 (to M.A.B.), OCE-1259776 (to K.W.B), and DGE-1650116 (Graduate Research Fellowship to R.H.L).2019-06-1

The multiple fates of sinking particles in the North Atlantic Ocean

Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 29 (2015): 1471–1494, doi:10.1002/2014GB005037.The direct respiration of sinking organic matter by attached bacteria is often invoked as the dominant sink for settling particles in the mesopelagic ocean. However, other processes, such as enzymatic solubilization and mechanical disaggregation, also contribute to particle flux attenuation by transferring organic matter to the water column. Here we use observations from the North Atlantic Ocean, coupled to sensitivity analyses of a simple model, to assess the relative importance of particle-attached microbial respiration compared to the other processes that can degrade sinking particles. The observed carbon fluxes, bacterial production rates, and respiration by water column and particle-attached microbial communities each spanned more than an order of magnitude. Rates of substrate-specific respiration on sinking particle material ranged from 0.007 ± 0.003 to 0.173 ± 0.105 day−1. A comparison of these substrate-specific respiration rates with model results suggested sinking particle material was transferred to the water column by various biological and mechanical processes nearly 3.5 times as fast as it was directly respired. This finding, coupled with strong metabolic demand imposed by measurements of water column respiration (729.3 ± 266.0 mg C m−2 d−1, on average, over the 50 to 150 m depth interval), suggested a large fraction of the organic matter evolved from sinking particles ultimately met its fate through subsequent remineralization in the water column. At three sites, we also measured very low bacterial growth efficiencies and large discrepancies between depth-integrated mesopelagic respiration and carbon inputs.U.S. Environmental Protection Agency (EPA) STAR Grant Number: FP-91744301-0; National Science Foundation Grant Numbers OCE-1061883, EF-0424599, OCE-1155438, OCE-1059884, OCE-1031143; Gordon and Betty Moore Foundation Grant Numbers: 3301, 3789; Gordon and Betty Moore Foundation; Woods Hole Oceanographic Institution2016-03-2

Interrogating marine virus-host interactions and elemental transfer with BONCAT and nanoSIMS-based methods

While the collective impact of marine viruses has become more apparent over the last decade, a deeper understanding of virus-host dynamics and the role of viruses in nutrient cycling would benefit from direct observations at the single-virus level. We describe two new complementary approaches - stable isotope probing coupled with nanoscale secondary ion mass spectrometry (nanoSIMS) and fluorescence-based biorthogonal non-canonical amino acid tagging (BONCAT) - for studying the activity and biogeochemical influence of marine viruses. These tools were developed and tested using several ecologically relevant model systems (Emiliania huxleyi/EhV207, Synechococcus sp. WH8101/Syn1, and Escherichia coli/T7). By resolving carbon and nitrogen enrichment in viral particles, we demonstrate the power of nanoSIMS tracer experiments in obtaining quantitative estimates for the total number of viruses produced directly from a particular production pathway (by isotopically labeling host substrates). Additionally, we show through laboratory experiments and a pilot field study that BONCAT can be used to directly quantify viral production (via epifluorescence microscopy) with minor sample manipulation and no dependency on conversion factors. This technique can also be used to detect newly synthesized viral proteins. Together these tools will help fill critical gaps in our understanding of the biogeochemical impact of viruses in the ocean

Interrogating marine virus-host interactions and elemental transfer with BONCAT and nanoSIMS-based methods

While the collective impact of marine viruses has become more apparent over the last decade, a deeper understanding of virus-host dynamics and the role of viruses in nutrient cycling would benefit from direct observations at the single-virus level. We describe two new complementary approaches - stable isotope probing coupled with nanoscale secondary ion mass spectrometry (nanoSIMS) and fluorescence-based biorthogonal non-canonical amino acid tagging (BONCAT) - for studying the activity and biogeochemical influence of marine viruses. These tools were developed and tested using several ecologically relevant model systems (Emiliania huxleyi/EhV207, Synechococcus sp. WH8101/Syn1, and Escherichia coli/T7). By resolving carbon and nitrogen enrichment in viral particles, we demonstrate the power of nanoSIMS tracer experiments in obtaining quantitative estimates for the total number of viruses produced directly from a particular production pathway (by isotopically labeling host substrates). Additionally, we show through laboratory experiments and a pilot field study that BONCAT can be used to directly quantify viral production (via epifluorescence microscopy) with minor sample manipulation and no dependency on conversion factors. This technique can also be used to detect newly synthesized viral proteins. Together these tools will help fill critical gaps in our understanding of the biogeochemical impact of viruses in the ocean

Temperate infection in a virus–host system previously known for virulent dynamics

The blooming cosmopolitan coccolithophore Emiliania huxleyi and its viruses (EhVs) are a model for density-dependent virulent dynamics. EhVs commonly exhibit rapid viral reproduction and drive host death in high-density laboratory cultures and mesocosms that simulate blooms. Here we show that this system exhibits physiology-dependent temperate dynamics at environmentally relevant E. huxleyi host densities rather than virulent dynamics, with viruses switching from a long-term non-lethal temperate phase in healthy hosts to a lethal lytic stage as host cells become physiologically stressed. Using this system as a model for temperate infection dynamics, we present a template to diagnose temperate infection in other virus–host systems by integrating experimental, theoretical, and environmental approaches. Finding temperate dynamics in such an established virulent host–virus model system indicates that temperateness may be more pervasive than previously considered, and that the role of viruses in bloom formation and decline may be governed by host physiology rather than by host–virus densities

Molecular insights into the function and regulation of diatom silicon transporters

Diatoms, a major group of primary producers in the ocean, are estimated to be responsible for over 40% of oceanic carbon fixation. As one of the predominant biosilicifying organisms in the world, diatoms are a model system for studying biological interactions with silicon. This research has focused on characterizing a novel family of transporters, called silicon transporters (SITs), that are specific for the uptake and efflux of silicon in diatoms. SIT sequences were isolated from evolutionarily diverse diatom species. Multi-gene copies were identified in most species, and phylogenetic analysis showed SITs grouped according to species. Structural analysis suggested SITs evolved through an internal gene duplication. Comparative sequence analysis revealed repeats of a conserved sequence motif, GXQ. A model of silicon transport consistent with known aspects of uptake was developed based on this motif. Analysis of SIT protein and mRNA expression, as well as measurements of uptake activity, was done on synchronously growing cultures of the diatom, Thalassiosira pseudonana. Immunoblot analysis using a newly developed SIT-specific antibody showed peaks in SIT protein levels correlated with active periods of silica incorporation. Quantitative PCR showed each T. pseudonana SIT (TpSIT1-3) peaked prior to cell wall synthesis. However, a disconnect between protein and mRNA levels suggested SITs were primarily regulated at the translational or post-translational level. In addition, rates of surge uptake suggested SIT activity was internally controlled by the rate of silica incorporation. Silicon uptake kinetics in diatoms were measured to determine the extent of nonsaturable uptake and the role of SITs. In all diatom species examined, a time-dependent transition from nonsaturable to saturable uptake kinetics was observed. In addition, both forms of uptake were affected by the SIT-specific antibody suggesting SITs were the predominant means of silicon uptake into the cell. Under some conditions, SITs had enormous flexibility in their rate of transport and appeared to act as selectivity gates rather than controlling agents in uptake. A model of diatom silicon uptake, consistent with this and previously published data, was developed based on the interplay between SITs, intracellular soluble silicon pools, and cell wall silica incorporatio

Bacteria and virus abundance data collected from the R/V Melville MV1405 along the California coastline during 2014

Dataset: IrnBru MV1405 - Bacteria and Virus AbundanceBacteria and virus abundance data collected from the R/V Melville MV1405 along the California coastline during 2014 For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/652259NSF Division of Ocean Sciences (NSF OCE) OCE-1333929, NSF Division of Ocean Sciences (NSF OCE) OCE-133438

Abundance of bacteria viruses and chlorophyll containing cells collected from the R/V Oceanus OC1504A in the Oregon/California Coastal Upwelling Zone, between 34-44N and 120-124W during 2015

Dataset: MUSiCC OC1504A - Bacteria Virus and Chlorophyll Containing Cell AbundanceAbundance of bacteria viruses and chlorophyll containing cells collected from the R/V Oceanus OC1504A in the Oregon/California Coastal Upwelling Zone, between 34-44N and 120-124W during 2015 For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/652223NSF Division of Ocean Sciences (NSF OCE) OCE-1333929, NSF Division of Ocean Sciences (NSF OCE) OCE-133438