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  • 1
    Publication Date: 2019-05-23
    Description: Recent advances in fluorescent imaging facilitate actualistic studies on organisms used for palaeoceanographic reconstructions. Observations of cytoskeleton organization and dynamics in living foraminifera foster understanding of morphogenetic and biomineralization principles. This paper describes the organisation of a foraminiferal actin cytoskeleton using in vivo staining based on fluorescent SiR-actin. Surprisingly, the most distinctive feature in the organisation of actin in Foraminifera is the prevalence of actin-labelled granules (ALGs) within pseudopodial structures. Fluorescent signal obtained from granules dominate over dispersed signal from the actin meshwork. Actin-labelled granules are small (around 1 µm in diameter) actin-rich organelles demonstrating a wide range of motility behaviours from almost stationary oscillating around certain points to exhibiting rapid motion. These structures are present both in Globothalamea (Amphistegina, Ammonia) and Tubothalamea (Quinqueloculina). They are found to be active in all kinds of pseudopodial ectoplasmic structures, including granuloreticulopodia, globopodia, and lamellipodia, as well as within the endoplasm itself. Two hypotheses regarding their function are proposed: (1) They are involved in endocytosis and intracellular transport of different kinds of cargo; (2) They transport prefabricated and/or recycled actin fibres to the sites where they are needed. These hypothesis are not mutually exclusive. The first hypothesis is based on the presence of similar actin structures in fungi, fungi-like protists and some plant cells. The later hypothesis is based on the assumption that actin granules are analogous to tubulin paracrystals responsible for efficient transport of tubulin. Actin patches transported in that manner are most likely involved in maintaining shape, rapid reorganization, and elasticity of pseudopodial structures, as well as in adhesion to the substrate. Finally, our comparative studies suggest that a large proportion of actin-labelled granules probably represent fibrillar vesicles and elliptical fuzzy coated vesicles often identified in TEM images. Correlative fluorescent electron microscopic observations are proposed to verify this interpretation.
    Print ISSN: 1810-6277
    Electronic ISSN: 1810-6285
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 2
    Publication Date: 2020-02-25
    Description: Recent advances in fluorescence imaging facilitate actualistic studies of organisms used for palaeoceanographic reconstructions. Observations of cytoskeleton organisation and dynamics in living foraminifera foster understanding of morphogenetic and biomineralisation principles. This paper describes the organisation of a foraminiferal actin cytoskeleton using in vivo staining based on fluorescent SiR-actin. Surprisingly, the most distinctive pattern of SiR-actin staining in foraminifera is the prevalence of SiR-actin-labelled granules (ALGs) within pseudopodial structures. Fluorescent signals obtained from granules dominate over dispersed signals from the actin meshwork. SiR-actin-labelled granules are small (around 1 µm in diameter) actin-rich structures, demonstrating a wide range of motility behaviours, from almost stationarily oscillating around certain points to exhibiting rapid motion. These labelled microstructures are present both in Globothalamea (Amphistegina, Ammonia) and Tubothalamea (Quinqueloculina). They are found to be active in all kinds of pseudopodial ectoplasmic structures, including granuloreticulopodia, globopodia, and lamellipodia, as well as within the endoplasm. Several hypotheses are set up to explain either specific or non-specific actin staining. Two hypotheses regarding their function are proposed if specific actin labelling is taken into account: (1) granules are involved in endocytosis and intracellular transport of different kinds of cargo, or (2) they transport prefabricated and/or recycled actin fibres to the sites where they are needed. These hypotheses are not mutually exclusive. The first hypothesis is based on the presence of similar actin structures in fungi, fungi-like protists, and some plant cells. The later hypothesis is based on the assumption that actin granules are analogous to tubulin paracrystals responsible for efficient transport of tubulin. Actin patches transported in that manner are most likely involved in maintaining shape, rapid reorganisation, and elasticity of pseudopodial structures, as well as in adhesion to the substrate. Finally, our comparative studies suggest that a large proportion of SiR-actin-labelled granules probably represent fibrillar vesicles and elliptical fuzzy-coated vesicles often identified in transmission electron microscope images.
    Print ISSN: 1726-4170
    Electronic ISSN: 1726-4189
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 3
    Publication Date: 2021-09-01
    Print ISSN: 0012-8252
    Electronic ISSN: 1872-6828
    Topics: Geography , Geosciences
    Published by Elsevier
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  • 4
    Publication Date: 1996-03-01
    Print ISSN: 0867-6046
    Electronic ISSN: 2084-6118
    Topics: Geography
    Published by De Gruyter
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  • 5
    Publication Date: 2019-05-27
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
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    In:  EPIC3Biogeosciences, 17(4), pp. 995-1011, ISSN: 1726-4189
    Publication Date: 2020-03-27
    Repository Name: EPIC Alfred Wegener Institut
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  • 7
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Biogeosciences 124 (2019): 2823-2850, doi:10.1029/2019JG005113.
    Description: Microscopy techniques have been widely applied to observe cellular ultrastructure. Most of these techniques, such as transmission electron microscopy, produce high‐resolution images, but they may require extensive preparation, hampering their application for in vivo examination. Other approaches, such as fluorescent and fluorogenic probes, can be applied not only to fixed specimens but also to living cells when the probes are nontoxic. Fluorescence‐based methods, which are generally relatively easy to use, allow visual and (semi)quantitative studies of the ultrastructural organization and processes of the cell under natural as well as manipulated conditions. To date, there are relatively few published studies on the nearly ubiquitous marine protistan group Foraminifera that have used fluorescent and fluorogenic probes, despite their huge potential. The aim of the present contribution is to document the feasible application of a wide array of these probes to foraminiferal biology. More specifically, we applied fluorescence‐based probes to study esterase activity, cell viability, calcium signaling, pH variation, reactive oxygen species, neutral and polar lipids, lipid droplets, cytoskeleton structures, Golgi complex, acidic vesicles, nuclei, and mitochondria in selected foraminiferal species.
    Description: The authors are very grateful to the Editor‐in‐Chief Miguel Goni and two anonymous reviewers for their thoughtful and valuable comments that have greatly improved the paper. Markus Raitzsch and Karina Kaczmarek from the AWI, Jakub Kordas from the ZOO Wrocław sp. z o. o. (Poland), and Max Janse from The Royal Burgers' Zoo (Arnhem, the Netherlands) are gratefully acknowledged. The authors declare that no competing interests exist. All the data are included within the paper or the supporting information accompanying it. The research for this paper was partially supported by the Ministero dell'Istruzione, dell'Università e della Ricerca (PRIN 2010‐2011 protocollo 2010RMTLYR) to R.C., the Japan Society for the Promotion of Science KAKENHI Grant (Numbers: JP18H06074, JP17H02978, JP19H02009, JP19H03045) to T.T. and Y.N., the WHOI Investment in Science Program to J.M.B, the Polish National Science Center (Grant DEC‐2015/19/B/ST10/01944) J.T. and J.G. and the Kuwait Foundation for the Advancement of Sciences (EM084C) to E.A‐E.
    Description: 2020-02-22
    Keywords: Protist ; Organelles ; Confocal laser scanning microscopy ; Probes ; Foraminifera
    Repository Name: Woods Hole Open Access Server
    Type: Article
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