Allen
Andrew E.
Allen
Andrew E.
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ArticleDissolved and particulate trace metal micronutrients under the McMurdo Sound seasonal sea ice : basal sea ice communities as a capacitor for iron(Frontiers Media, 2013-10-30) Noble, Abigail E. ; Moran, Dawn M. ; Allen, Andrew E. ; Saito, Mak A.Dissolved and particulate metal concentrations are reported from three sites beneath and at the base of the McMurdo Sound seasonal sea ice in the Ross Sea of Antarctica. This dataset provided insight into Co and Mn biogeochemistry, supporting a previous hypothesis for water column mixing occurring faster than scavenging. Three observations support this: first, Mn-containing particles with Mn/Al ratios in excess of the sediment were present in the water column, implying the presence of bacterial Mn-oxidation processes. Second, dissolved and labile Co were uniform with depth beneath the sea ice after the winter season. Third, dissolved Co:PO3−4 ratios were consistent with previously observed Ross Sea stoichiometry, implying that over-winter scavenging was slow relative to mixing. Abundant dissolved Fe and Mn were consistent with a winter reserve concept, and particulate Al, Fe, Mn, and Co covaried, implying that these metals behaved similarly. Elevated particulate metals were observed in proximity to the nearby Islands, with particulate Fe/Al ratios similar to that of nearby sediment, consistent with a sediment resuspension source. Dissolved and particulate metals were elevated at the shallowest depths (particularly Fe) with elevated particulate P/Al and Fe/Al ratios in excess of sediments, demonstrating a sea ice biomass source. The sea ice biomass was extremely dense (chl a >9500 μg/L) and contained high abundances of particulate metals with elevated metal/Al ratios. A hypothesis for seasonal accumulation of bioactive metals at the base of the McMurdo Sound sea ice by the basal algal community is presented, analogous to a capacitor that accumulates iron during the spring and early summer. The release and transport of particulate metals accumulated at the base of the sea ice by sloughing is discussed as a potentially important mechanism in providing iron nutrition during polynya phytoplankton bloom formation and could be examined in future oceanographic expeditions.
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DatasetResults from metal limitation experiments (Cu, Zn, Fe, Mn) conducted in the prymensiophyte Phaeocystis globosa carried out in the Kustka and Allen labs at Rutgers in Newark, NJ from 2007-2011(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-02-22) Allen, Andrew EResults from metal limitation experiments (Cu, Zn, Fe, Mn) conducted in the prymensiophyte Phaeocystis globosa carried out in the Kustka and Allen labs at Rutgers in Newark, NJ from 2007-2011 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/3669
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DatasetResults from trace metal controlled diel microarray experiments with diatoms carried out in the Kustka and Allen labs at Rutgers in Newark, NJ from 2007-2011(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-02-22) Allen, Andrew EResults from trace metal controlled diel microarray experiments with diatoms carried out in the Kustka and Allen labs at Rutgers in Newark, NJ from 2007-2011. Ten diel microarray experiments were completed (seven for P. tricornutum encompassing three Fe concentrations, and three for T. pseudonana encompassing two Fe concentrations). 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/3667
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ArticleMethionine synthase interreplacement in diatom cultures and communities : implications for the persistence of B12 use by eukaryotic phytoplankton(Association for the Sciences of Limnology and Oceanography, 2013-07) Bertrand, Erin M. ; Moran, Dawn M. ; McIlvin, Matthew R. ; Hoffman, Jeffrey M. ; Allen, Andrew E. ; Saito, Mak A.Three proteins related to vitamin B12 metabolism in diatoms were quantified via selected reaction monitoring mass spectrometry: B12-dependent and B12-independent methionine synthase (MetH, MetE) and a B12 acquisition protein (CBA1). B12-mediated interreplacement of MetE and MetH metalloenzymes was observed in Phaeodactylum tricornutum where MetH abundance was highest (0.06 fmol µg−1 protein) under high B12 and MetE abundance increased to 3.25 fmol µg−1 protein under low B12 availability. Maximal MetE abundance was 60-fold greater than MetH, consistent with the expected ∼ 50–100-fold larger turnover number for MetH. MetE expression resulted in 30-fold increase in nitrogen and 40-fold increase in zinc allocated to methionine synthase activity under low B12. CBA1 abundance was 6-fold higher under low-B12 conditions and increased upon B12 resupply to starved cultures. While biochemical pathways that supplant B12 requirements exist and are utilized by organisms such as land plants, B12 use persists in eukaryotic phytoplankton. This study suggests that retention of B12 utilization by phytoplankton results in resource conservation under conditions of high B12 availability. MetE and MetH abundances were also measured in diatom communities from McMurdo Sound, verifying that both these proteins are expressed in natural communities. These protein measurements are consistent with previous studies suggesting that B12 availability influences Antarctic primary productivity. This study illuminates controls on expression of B12-related proteins, quantitatively assesses the metabolic consequences of B12 deprivation, and demonstrates that mass spectrometry–based protein measurements yield insight into the functioning of marine microbial communities.
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DatasetResults from metal limitation experiments (Cu, Zn, Fe, Mn) conducted in the diatom T. pseudonana carried out in the Kustka and Allen labs at Rutgers in Newark, NJ from 2007-2011(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-02-22) Allen, Andrew EResults from metal limitation experiments (Cu, Zn, Fe, Mn) conducted in the diatom T. pseudonana carried out in the Kustka and Allen labs at Rutgers in Newark, NJ from 2007-2011 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/3668
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ArticleColony formation in Phaeocystis antarctica : connecting molecular mechanisms with iron biogeochemistry(Copernicus Publications on behalf of the European Geosciences Union, 2018-08-21) Bender, Sara J. ; Moran, Dawn M. ; McIlvin, Matthew R. ; Zheng, Hong ; McCrow, John P. ; Badger, Jonathan ; DiTullio, Giacomo R. ; Allen, Andrew E. ; Saito, Mak A.Phaeocystis antarctica is an important phytoplankter of the Ross Sea where it dominates the early season bloom after sea ice retreat and is a major contributor to carbon export. The factors that influence Phaeocystis colony formation and the resultant Ross Sea bloom initiation have been of great scientific interest, yet there is little known about the underlying mechanisms responsible for these phenomena. Here, we present laboratory and field studies on Phaeocystis antarctica grown under multiple iron conditions using a coupled proteomic and transcriptomic approach. P. antarctica had a lower iron limitation threshold than a Ross Sea diatom Chaetoceros sp., and at increased iron nutrition (>120pM Fe') a shift from flagellate cells to a majority of colonial cells in P. antarctica was observed, implying a role for iron as a trigger for colony formation. Proteome analysis revealed an extensive and coordinated shift in proteome structure linked to iron availability and life cycle transitions with 327 and 436 proteins measured as significantly different between low and high iron in strains 1871 and 1374, respectively. The enzymes flavodoxin and plastocyanin that can functionally replace iron metalloenzymes were observed at low iron treatments consistent with cellular iron-sparing strategies, with plastocyanin having a larger dynamic range. The numerous isoforms of the putative iron-starvation-induced protein (ISIP) group (ISIP2A and ISIP3) had abundance patterns coinciding with that of either low or high iron (and coincident flagellate or the colonial cell types in strain 1871), implying that there may be specific iron acquisition systems for each life cycle type. The proteome analysis also revealed numerous structural proteins associated with each cell type: within flagellate cells actin and tubulin from flagella and haptonema structures as well as a suite of calcium-binding proteins with EF domains were observed. In the colony-dominated samples a variety of structural proteins were observed that are also often found in multicellular organisms including spondins, lectins, fibrillins, and glycoproteins with von Willebrand domains. A large number of proteins of unknown function were identified that became abundant at either high or low iron availability. These results were compared to the first metaproteomic analysis of a Ross Sea Phaeocystis bloom to connect the mechanistic information to the in situ ecology and biogeochemistry. Proteins associated with both flagellate and colonial cells were observed in the bloom sample consistent with the need for both cell types within a growing bloom. Bacterial iron storage and B12 biosynthesis proteins were also observed consistent with chemical synergies within the colony microbiome to cope with the biogeochemical conditions. Together these responses reveal a complex, highly coordinated effort by P. antarctica to regulate its phenotype at the molecular level in response to iron and provide a window into the biology, ecology, and biogeochemistry of this group.
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DatasetDYEatom Metatranscriptome metadata from RV/Point Sur cruise PS1312 in the Monterey Bay area, June-July 2013(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-07-31) Thamatrakoln, Kimberlee ; Allen, Andrew EMetadata for assembled contigs and ORFS from metatranscriptome analysis from CTD casts in the Monterey Bay area on RV/Point Sur cruise PS1312, June-July 2013. Assembled contigs files are also available; see Supplemental Files. 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/768550