Ultrastructural Observation of Cytokinesis and Plasmodesmata Formation in Brown Algae

Nagasato, Chikako; Yonamine, Rina; Motomura, Taizo

doi:10.1007/978-1-0716-1744-1_16

Cited by 3 publications

(1 citation statement)

References 21 publications

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“…They diverged from the ancestors of other extant multicellular organisms at the root of the eukaryotic tree at least 1 billion years ago and emerged as complex multicellular organisms relatively recently, around 250 million years ago (Burki et al, 2020; Kawai et al, 2015). Being evolutionarily distinct from animals, fungi, plants and other algae, brown algae possess unique biological mechanisms (Charrier et al, 2019; Nagasato et al, 2022; Terauchi et al, 2015). They have evolved diverse complex embryonic patterns.…”

Section: Introductionmentioning

confidence: 99%

MUM, a maternal unknown message, inhibits early establishment of the medio-lateral axis in the embryo of the kelpSaccharina latissima

Boscq,

Billoud,

Theodorou

et al. 2024

Preprint

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Brown algae are multicellular photosynthetic organisms that have evolved independently of plants and other algae. Apart from studies on the polarisation of the Fucus zygote in the 1990s, little is known about the mechanisms controlling the embryogenesis of these organisms. Here, we studied the determinism of embryogenesis in the kelp Saccharina latissima, focusing on the formation of its body axes. This alga initially develops an oblong embryo formed of a cell monolayer, which subsequently thickens; growth axes are then established in temporally distinct stages, starting with the formation of a dominant apico-basal axis. Our experiments focused on the role of the stalk, an empty cell that retains the embryo attached to the maternal tissue, in the development of the growth axes in mature embryos. In response to the removal of the stalk, the embryos developed as a monolayered disc rather than an elongated blade, demonstrating that attachment to the stalk inhibits the formation of the medio-lateral axis at the onset of embryogenesis. In addition, compared with embryos attached to the stalk, the cells of detached embryos were smaller and displayed an altered shape. The topology of the tissue was also disrupted, as cells had a higher number of cell neighbours. Observation of cell division patterns just after removal of the stalk showed that the stalk represses longitudinal cell divisions, thereby reinforcing the establishment of the main apico-basal axis. This unique quantitative study of brown algal embryogenesis revealed that, in kelps, a signal from maternal tissue (MUM for maternal unknown message) is necessary for the establishment of growth axes at the onset of embryogenesis and of the organisation of growing embryonic tissues. In addition, we discovered that, although the stalk persists for several weeks until the embryo reaches at least 500 cells, MUM is emitted in the first 4 days after fertilisation only, before the embryo reaches the 8-cell stage. Finally, transplantation experiments indicated that MUM does not diffuse in seawater, but requires contact between the embryo and the stalk. The potential chemical or mechanical nature of MUM is discussed.

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Section: Introductionmentioning

confidence: 99%

MUM, a maternal unknown message, inhibits early establishment of the medio-lateral axis in the embryo of the kelpSaccharina latissima

Boscq,

Billoud,

Theodorou

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

MUM, a maternal unknown message, inhibits early establishment of the medio-lateral axis in the embryo of the kelp Saccharina latissima

Boscq,

Billoud,

Theodorou

et al. 2024

Development

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Brown algae are multicellular photosynthetic organisms that have evolved independently of plants and other algae. Here, we studied the determinism of body axis formation in the kelp Saccharina latissima. Following microdissection of the embryo, we showed that the stalk, an empty cell that retains the embryo on the maternal tissue represses longitudinal cell divisions in the early embryo, thereby reinforcing the establishment of the initial apico-basal axis. In addition, it promotes cell growth and controls cell shape and arrangement in the flat, oblong embryo composed of cells aligned in rows and columns. Although the stalk persists for several weeks until the embryo reaches at least 500 cells, proper embryogenesis requires connection to maternal tissue only during the first 4 days after fertilisation, i.e. before the embryo reaches the 8-cell stage. Transplantation experiments indicated that the maternal signal is not diffused in seawater, but requires contact between the embryo and the maternal tissue. This first global quantitative study of brown algal embryogenesis highlights the role of MUM, an unknown maternal message, in the control of growth axes and tissue patterning in kelp embryos. please edit family name

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Plasmodesmata of Brown Algae (Phaeophyceae): Structure, Localization and Functions

Kudryavtseva

2023

Botanicheskii Zhurnal

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The present review outlines the history of the study of plasmodesmata in brown algae, describes their ultrastructure, which differs from that of other groups of algae and land plants, presents variants of localization of plasmodesmata in different members of Phaeophyceae – from a scattered location to arrangement into pit fields; the functions performed by plasmodesmata in the thalli of brown algae are listed. Possible prospects for further study of these structures are specified.

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Ultrastructural Observation of Cytokinesis and Plasmodesmata Formation in Brown Algae

Cited by 3 publications

References 21 publications

MUM, a maternal unknown message, inhibits early establishment of the medio-lateral axis in the embryo of the kelpSaccharina latissima

MUM, a maternal unknown message, inhibits early establishment of the medio-lateral axis in the embryo of the kelpSaccharina latissima

MUM, a maternal unknown message, inhibits early establishment of the medio-lateral axis in the embryo of the kelp Saccharina latissima

Plasmodesmata of Brown Algae (Phaeophyceae): Structure, Localization and Functions

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