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  • 1
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    Combined carbonate carbon isotopic and cellular ultrastructural studies of individual benthic foraminifera : method description (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 25 (2010): PA2211, doi:10.1029/2009PA001846.
    Description: Carbon isotopes of foraminiferal tests provide a widely used proxy for past oceanographic environmental conditions. This proxy can be calibrated using live specimens, which are reliably identified with observations of cell ultrastructure. Observations of ultrastructures can also be used for studies of biological characteristics such as diet and presence of symbionts. Combining biological and isotopic studies on individual foraminifera could provide novel information, but standard isotopic methods destroy ultrastructures by desiccating specimens and observations of ultrastructure require removal of carbonate tests, preventing isotope measurements. The approach described here preserves cellular ultrastructure during isotopic analyses by keeping the foraminifera in an aqueous buffer (Phosphate Buffered Saline (PBS)). The technique was developed and standardized with 36 aliquots of NBS-19 standard of similar weight to foraminiferal tests (5 to 123 μg). Standard errors ranged from ± 0.06 to ± 0.85‰ and were caused by CO2 contaminants dissolved in the PBS. The technique was used to measure δ13C values of 96 foraminifera, 10 of which do not precipitate carbonate tests. Calcareous foraminiferal tests had corrected carbon isotope ratios of −8.5 to +3.2‰. This new technique allows comparisons of isotopic compositions of tests made by foraminifera known to be alive at the time of collection with their biological characteristics such as prey composition and presence or absence of putative symbionts. The approach may be applied to additional biomineralizing organisms such as planktonic foraminifera, pteropods, corals, and coccolithophores to elucidate certain biological controls on their paleoceanographic proxy signatures.
    Description: Support was provided by NSF grants OCE‐0550396 (to J.B.M.), OCE‐0551001 (to J.M.B.), and OCE‐ 0550401 (to A.E.R.).
    Keywords: Foraminifera ; Ultrastructure ; Carbon isotopes
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
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    Metazoans of redoxcline sediments in Mediterranean deep-sea hypersaline anoxic basins (2016)
    BioMed Central
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    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in BMC Biology 13 (2015): 105, doi:10.1186/s12915-015-0213-6
    Description: The deep-sea hypersaline anoxic basins (DHABs) of the Mediterranean (water depth ~3500 m) are some of the most extreme oceanic habitats known. Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB haloclines and brines, loriciferans are the only metazoan reported to inhabit the anoxic DHAB brines. Our goal was to further investigate metazoan communities in DHAB haloclines and brines. We report observations from sediments of three DHAB (Urania, Discovery, L’Atalante) haloclines, comparing these to observations from sediments underlying normoxic waters of typical Mediterranean salinity. Due to technical difficulties, sampling of the brines was not possible. Morphotype analysis indicates nematodes are the most abundant taxon; crustaceans, loriciferans and bryozoans were also noted. Among nematodes, Daptonema was the most abundant genus; three morphotypes were noted with a degree of endemicity. The majority of rRNA sequences were from planktonic taxa, suggesting that at least some individual metazoans were preserved and inactive. Nematode abundance data, in some cases determined from direct counts of sediments incubated in situ with CellTrackerTM Green, was patchy but generally indicates the highest abundances in either normoxic control samples or in upper halocline samples; nematodes were absent or very rare in lower halocline samples. Ultrastructural analysis indicates the nematodes in L’Atalante normoxic control sediments were fit, while specimens from L’Atalante upper halocline were healthy or had only recently died and those from the lower halocline had no identifiable organelles. Loriciferans, which were only rarely encountered, were found in both normoxic control samples as well as in Discovery and L’Atalante haloclines. It is not clear how a metazoan taxon could remain viable under this wide range of conditions. We document a community of living nematodes in normoxic, normal saline deep-sea Mediterranean sediments and in the upper halocline portions of the DHABs. Occurrences of nematodes in mid-halocline and lower halocline samples did not provide compelling evidence of a living community in those zones. The possibility of a viable metazoan community in brines of DHABs is not supported by our data at this time.
    Description: Supported by NSF grants OCE-0849578 to VPE and JMB, OCE-1061391 to JMB and VPE, and The Investment in Science Fund at WHOI.
    Keywords: Athalassohaline ; Bryozoa ; CellTrackerTM Green ; Discovery ; L’Atalante ; Loricifera ; Meiofauna ; Nematoda ; Ultrastructure ; Urania
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
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    Intracellular isotope localization in Ammonia sp. (Foraminifera) of oxygen-depleted environments : results of nitrate and sulfate labeling experiments (2016)
    Frontiers Media
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 7 (2016): 163, doi:10.3389/fmicb.2016.00163.
    Description: Some benthic foraminiferal species are reportedly capable of nitrate storage and denitrification, however, little is known about nitrate incorporation and subsequent utilization of nitrate within their cell. In this study, we investigated where and how much 15N or 34S were assimilated into foraminiferal cells or possible endobionts after incubation with isotopically labeled nitrate and sulfate in dysoxic or anoxic conditions. After 2 weeks of incubation, foraminiferal specimens were fixed and prepared for Transmission Electron Microscopy (TEM) and correlative nanometer-scale secondary ion mass spectrometry (NanoSIMS) analyses. TEM observations revealed that there were characteristic ultrastructural features typically near the cell periphery in the youngest two or three chambers of the foraminifera exposed to anoxic conditions. These structures, which are electron dense and ~200–500 nm in diameter and co-occurred with possible endobionts, were labeled with 15N originated from 15N-labeled nitrate under anoxia and were labeled with both 15N and 34S under dysoxia. The labeling with 15N was more apparent in specimens from the dysoxic incubation, suggesting higher foraminiferal activity or increased availability of the label during exposure to oxygen depletion than to anoxia. Our results suggest that the electron dense bodies in Ammonia sp. play a significant role in nitrate incorporation and/or subsequent nitrogen assimilation during exposure to dysoxic to anoxic conditions.
    Description: This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan (Young Scientists B No. 22740340 and Scientific Research C No. 24540504 to HN), an Invitation Fellowship for Research in Japan to JB by Japan Society for the Promotion of Science (JSPS), the Robert W. Morse Chair for Excellence in Oceanography at WHOI to JB, and The Investment in Science Fund at WHOI to JB.
    Keywords: Foraminifer ; Nitrate ; NanoSIMS ; Electron dense body ; Endobionts ; Ultrastructure ; Denitrification
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
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    Images of cellular ultrastructure of benthic foraminifera from Arctic seeps (2021)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-10-21
    Description: Dissociation of methane hydrates due to ocean warming releases methane, a powerful greenhouse gas, to the atmosphere. Dissociation of gas hydrates may have led to rapid and dramatic environmental changes in the past. Thus, understanding the impact of those events requires information about their timing and magnitudes. While the foraminiferal fossil record provides a powerful tool to understand past environmental conditions, seep-endemic foraminifera are unknown, which limits evaluation of seep-specific information. However, geographically widespread benthic foraminifera do inhabit seep sites, as documented widely in the literature, and may provide information useful to the understanding of past methane releases. In an effort to better understand how benthic foraminifera inhabit this chemosynthesis-based ecosystem, and if they faithfully record the methane emissions, we conducted a multipronged analysis of foraminifera associated with a gas hydrate emission site in the Arctic. Our goal was to simultaneously assess, in single representative calcareous benthic foraminiferal individuals, the cell biology, test stable carbon isotope ratio, and carbonate microstructure (e.g., wall thickness, survey for authigenic overgrowths), from samples collected south of Svalbard, or on Vestnesa Ridge, west of Svalbard). Serially, each specimen was scanned with microCT (computerized tomography) to assess test characteristics, then the test dissolved by acidification while capturing gas to measure stable carbon isotope ratio via continuous-flow mass spectrometry, and finally the remaining soft parts embedded and examined for cell ultrastructure with a Transmission Electron Microscope (TEM). TEM). Data from isotopic analyses, microCT scans and TEM imaging are presented here.
    Description: This project was funded by NSF (WHOI)OCE-1634469 NSF (UFL)OCE-1634248 Norwegian Research Council223259
    Keywords: Methane seep ; Arctic ; Storfjordrenna ; Vestnesa ; Lomvi ; Benthic foraminifera ; MicroCT scan ; Stable carbon isotopes of calcite ; Ultrastructure ; TEM ; Cytology
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
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  • 5
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    Effects of lead pollution on Ammonia parkinsoniana (foraminifera) : ultrastructural and microanalytical approaches (2015)
    PAGEPress
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in European Journal of Histochemistry 59 (2015): 2460, doi:10.4081/ejh.2015.2460.
    Description: The responses of Ammonia parkinsoniana (Foraminifera) exposed to different concentrations of lead (Pb) were evaluated at the cytological level. Foraminifera-bearing sediments were placed in mesocosms that were housed in aquaria each with seawater of a different lead concentration. On the basis of transmission electron microscopy and environmental scanning electron microscopy coupled with energy dispersive spectrometer analyses, it was possible to recognize numerous morphological differences between untreated (i.e., control) and treated (i.e., lead enrichment) specimens. In particular, higher concentrations of this pollutant led to numerical increase of lipid droplets characterized by a more electron-dense core, proliferation of residual bodies, a thickening of the organic lining, mitochondrial degeneration, autophagosome proliferation and the development of inorganic aggregates. All these cytological modifications might be related to the pollutant-induced stress and some of them such as the thickening of organic lining might suggest a potential mechanism of protection adopted by foraminifera.
    Description: This research was partially supported by the PRIN 2010-2011 Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR) (protocollo 2010RMTLYR) to R.C. and by US NSF grant OCE-1219948 to J.M.B.
    Keywords: Foraminifera ; Pollution ; Ultrastructure ; Mesocosm
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
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    Benthic foraminiferal ultrastructural alteration induced by heavy metals (2018)
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Marine Micropaleontology 138 (2018): 83-89, doi:10.1016/j.marmicro.2017.10.009.
    Description: Heavy metals are known to cause deleterious effects on biota because of their toxicity, persistence and bioaccumulation. Here, we briefly document the ultrastructural changes observed in the miliolid foraminifer Pseudotriloculina rotunda (d'Orbigny in Schlumberger, 1893) and in the perforate calcareous species Ammonia parkinsoniana (d'Orbigny, 1839) induced by exposure to one of three heavy metals (zinc, lead, or mercury). The exposure of these two benthic foraminiferal species to the selected heavy metals appear to promote cytological alterations and organelle degeneration. These alterations include a thickening of the inner organic lining, an increase in number and size of lipid droplets, mitochondrial degeneration, and degradation vacuoles and residual body proliferation. Some of these alterations, including the thickening of the inner organic lining and the proliferation of lipids, might represent defense mechanisms against heavy metal-induced stress.
    Description: The research on Ammonia parkinsoniana was partially supported by the PRIN 2010-2011 Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR) (protocollo 2010RMTLYR) to RC. The research on Pseudotriloculina rotunda was supported by the Polytechnic University of Marche (PhD thesis of MPN).
    Keywords: Protist ; Pollution ; Miliolid ; Ultrastructure ; Cytoplasm ; Ammonia ; Pseudotriloculina
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 7
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    Innovative TEM-coupled approaches to study foraminiferal cells (2018)
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    Publication Date: 2022-05-26
    Description: © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Marine Micropaleontology 138 (2018): 90-104, doi:10.1016/j.marmicro.2017.10.002.
    Description: Transmission electron microscope (TEM) observation has revealed much about the basic cell biology of foraminifera. Yet, there remains much we do not know about foraminiferal cytology and physiology, especially for smaller benthic foraminifera, which inhabit a wide range of habitats. Recently, some TEM-coupled approaches have been developed to study correlative foraminiferal ecology and physiology in detail: Fluorescently Labeled Embedded Core (FLEC)-TEM for observing foraminiferal life-position together with their cytoplasmic ultrastructure, micro-X-ray computed tomography (CT)-TEM for observing and reconstructing foraminiferal cytoplasm in three dimensions (3D), and TEM-Nanometer-scale secondary ion mass spectrometry (NanoSIMS) for mapping of elemental and isotopic compositions at sub-micrometer resolutions with known ultrastructure. In this contribution, we review and illustrate these recent advances of TEM-coupled methods.
    Description: This work was financially supported by the Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan (Scientific Research (C) grant number 17K05697 to HN) and the Swiss National Science Foundation (grant no. 200021_149333). JMB’s contributions were funded by US NSF grants OCE-0551001 and OCE-1634469, the WHOI Robert W. Morse Chair for Excellence in Oceanography, and The Investment in Science Fund at WHOI. The micro-X-ray CT imaging was performed under the cooperative research program of Center for Advanced Marine Core Research (CMCR), Kochi University (accept No. 17A021).
    Keywords: Ultrastructure ; NanoSIMS ; Micro-X-ray CT ; Correlative microscopy ; Isotope mapping ; Microhabitat
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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