05 May 2021

05 May 2021

Review status: this preprint is currently under review for the journal BG.

Fluorescent double labelling of F-actin in Foraminifera: evaluation of granular pattern F-actin organisation in reticulopodia

Jan Goleń, Jarosław Tyszka, and Karolina Godos Jan Goleń et al.
  • ING PAN – Institute of Geological Sciences, Polish Academy of Sciences, Research Centre in Kraków, Biogeosystem Modelling Group, Senacka 1, 31-002 Kraków, Poland

Abstract. This paper presents novel results of experiments focused on actin cytoskeleton organisation in pseudopodial structures of foraminifera. The main aim of this research was to test the hypotheses proposed to explain the previously reported granular pattern of F-actin labelling in several species of foraminifera with SiR-actin fluorescent probe. These hypotheses include the possibility that SiR-actin enhances the F-actin polymerisation or that it binds to other than F-actin compounds within foraminiferal cells, resulting in capturing the staining artefacts. The series of replicated experiments conducted on small miliolid Quinqueloculina sp. included double staining of F-actin with SiR-actin and phalloidin-based probes, complemented with observations of reticulopodia under the polarised light to identify the granules showing birefringence. All of performed experiments demonstrate highly congruent results expressed in SiR-actin and phalloidin co-labelling patterns, especially pronounced with the small granular objects (SiR-actin labelled granules or ALGs). Furthermore, the birefringence strongly tends to characterise primarily areas stained with both of the probes. These results rule out staining artefacts and support existence of actin cytoskeleton associated with micrometre-size motile granules. We discuss possible implications of this granular pattern that facilitates efficient formation and fast reorganization of extended granuloreticulopodia and other pseudopodial structures. If this is the case, they are one of the key evolutionary adaptations of these organisms that most likely predates the evolution of the foraminiferal tests that started in the early Palaeozoic.

Jan Goleń et al.

Status: open (until 16 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Jan Goleń et al.

Video supplement

Movie S2. Z-stack of granuloreticulopodia of Quinqueloculina sp. Goleń, Jan; Tyszka, Jarosław; Godos, Karolina

Movie S1. Fixation of granuloreticulopodia of Amphistegina lessonii d’Orbigny Goleń, Jan; Tyszka, Jarosław; Godos, Karolina

Jan Goleń et al.


Total article views: 143 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
119 20 4 143 9 1 2
  • HTML: 119
  • PDF: 20
  • XML: 4
  • Total: 143
  • Supplement: 9
  • BibTeX: 1
  • EndNote: 2
Views and downloads (calculated since 05 May 2021)
Cumulative views and downloads (calculated since 05 May 2021)

Viewed (geographical distribution)

Total article views: 101 (including HTML, PDF, and XML) Thereof 101 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 14 May 2021
Short summary
We present images of foraminiferal pseudopodia stained with two different actin-labelling fluorescent probes (SiR-actin and Phalloidin Atto 488) showing very similar staining patterns. The highest intensity of fluorescence in both channels is observed in micrometre-sized granules. These observations allow for rejection the staining artefacts hypotheses and support the possibility that these granules contain physiologically functional form of actin cytoskeleton in foraminifera.