Biogeosciences, 17, 995–1011, 2020 https://doi.org/10.5194/bg-17-995-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. SiR-actin-labelled granules in foraminifera: patterns, dynamics, and hypotheses Jan Golen´ 1, Jarosław Tyszka1, Ulf Bickmeyer2, and Jelle Bijma2 1ING PAN – Institute of Geological Sciences, Polish Academy of Sciences, Research Centre in Kraków, Biogeosystem Modelling Group, Senacka 1, 31-002 Kraków, Poland 2AWI – Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany Correspondence: Jan Golen´ (
[email protected]) Received: 10 May 2019 – Discussion started: 23 May 2019 Revised: 23 December 2019 – Accepted: 8 January 2020 – Published: 25 February 2020 Abstract. Recent advances in fluorescence imaging facilitate is based on the assumption that actin granules are analogous actualistic studies of organisms used for palaeoceanographic to tubulin paracrystals responsible for efficient transport of reconstructions. Observations of cytoskeleton organisation tubulin. Actin patches transported in that manner are most and dynamics in living foraminifera foster understanding of likely involved in maintaining shape, rapid reorganisation, morphogenetic and biomineralisation principles. This paper and elasticity of pseudopodial structures, as well as in adhe- describes the organisation of a foraminiferal actin cytoskele- sion to the substrate. Finally, our comparative studies suggest ton using in vivo staining based on fluorescent SiR-actin. that a large proportion of SiR-actin-labelled granules prob- Surprisingly, the most distinctive pattern of SiR-actin stain- ably represent fibrillar vesicles and elliptical fuzzy-coated ing in foraminifera is the prevalence of SiR-actin-labelled vesicles often identified in transmission electron microscope granules (ALGs) within pseudopodial structures.