Movies about diatoms and their movements

详细

Diatoms are unique unicellular photosynthetic organisms that have siliceous frustules around their cell membrane. Diatom cells are capable of independent movements in the aquatic medium, which is important for their life strategy. This article summarizes my main observations on the movements of diatoms, including some hypotheses. The material is presented in the form of six video films.

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Brief biography J.R. BERTRAND

J. BETRAND born on 15.03.1931 in St. Benoit sur Loire France

Address: 42 rue de Malvoisine, 45800 Saint Jean de Braye, France

E-Mail: j.r.bertrand@orange.fr

Amateur microscopist from 1942 to 1986.

Profession: engineer in industrial mechanics from 1960 to 1985.

Independent researcher from 1986 to now (2022)

Member of the Association des Diatomistes de Langue Française (ADLaF)

Member of the International Society for Diatom Research until 2015

Specialist in diatom movements from 1990 to 2005

Specialist in pond ecology from 2007 to 2017.

Specialist in diatoms on lichens from 2015 to present.

Taught diatoms in a French public service Agence de l’Eau; DREAL (3 years)

Taught general microscopy at the Natural History Museum of Orléans (12 years)

By Clother Coste <cloter@wanadoo.fr>

*Corresponding author.

E-mail address: j.r.bertrand@orange.fr (J.R. Bertrand)

The video films showing the movements of various diatom cells were created during the preparation of a series of works in this field. Files are available at http://limnolfwbiol.com/index.php/LFWB/article/view/994/684 under Creative Commons Attribution 4.0 International Public License. There are six videos:

1. “Bertrand1990 1 L’Equilibre.avi” (Bertrand, 1990; 1991a).

The characteristic shape of the diatom Rhoicosphenia abbreviata would seem to not allow apical and transapical movements. This study demonstrates with the help of analyses of graphical statics that the forces involved explain and confirm the reality of the observed movements.

2. “Bertrand1991 2. Synthase-Mouvements.avi” (Bertrand, 1991b; 1992).

This film shows all possible movements of raphid diatoms performed in the aquatic environment as well as a synthetic table showing the relationship with substrates. Apical, and transapical movements, horizontal, vertical, polar and conical rotations of 12 species are shown. The totality of all possibilities is executed by Gomphonema acuminatum.

3. «Bertrand1994 3 Cymbella triangulum.avi» (Bertrand, 1994a; Bertrand and Coste, 1994).

This video shows for the first time the diatom Cymbella triangulum, new to the European continent. Its movements, dimensions, morphology and ecological preferences are described.

4. “Bertrand1994 4 Cocconeis pediculus.avi” (Bertrand, 1994b; 1995a).

This video shows how easily the diatom Cocconeis pediculus performs a transapical movement despite the cylindrical-concave shape in the apical direction of its hypovalve. The diatom generally uses this particular geometry to position itself tightly on supports such as green algae of the genus Cladophora.

5. “Bertrand1995 Les Diatomees.avi” (Bertrand, 1995b).

This documentary introduces the microscopic world of diatoms, unsuspected by most people. How to find them, how to observe them, their delicate beauty, their way of life, their usefulness, and how they inspired artists.

6. “Bertrand1999 Les Diatomees.avi” (Bertrand, 1999).

This video traces the search for the causes of diatom movements to the absence of rigid supports, i.e., just using the surface tension of water. It shows the researcher’s background, calculations, thoughts and the means implemented to try to propose a credible hypothesis.

A summary of my theories of diatom motility is given in Bertrand (2021).

Conflict of interest

The authors declare that they have no competing interests.