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The nuclear-to-cytoplasmic ratio drives cellularization in the close animal relative Sphaeroforma arctica.
- Source :
-
Current biology : CB [Curr Biol] 2023 Apr 24; Vol. 33 (8), pp. 1597-1605.e3. Date of Electronic Publication: 2023 Mar 29. - Publication Year :
- 2023
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Abstract
- The ratio of nuclear content to cytoplasmic volume (N/C ratio) is a key regulator driving the maternal-to-zygotic transition in most animal embryos. Altering this ratio often impacts zygotic genome activation and deregulates the timing and outcome of embryogenesis. <superscript>1</superscript> <superscript>,</superscript> <superscript>2</superscript> <superscript>,</superscript> <superscript>3</superscript> Despite being ubiquitous across animals, little is known about when the N/C ratio evolved to control multicellular development. Such capacity either originated with the emergence of animal multicellularity or was co-opted from the mechanisms present in unicellular organisms. <superscript>4</superscript> An effective strategy to tackle this question is to investigate the close relatives of animals exhibiting life cycles with transient multicellular stages. <superscript>5</superscript> Among these are ichthyosporeans, a lineage of protists undergoing coenocytic development followed by cellularization and cell release. <superscript>6</superscript> <superscript>,</superscript> <superscript>7</superscript> <superscript>,</superscript> <superscript>8</superscript> During cellularization, a transient multicellular stage resembling animal epithelia is generated, offering a unique opportunity to examine whether the N/C ratio regulates multicellular development. Here, we use time-lapse microscopy to characterize how the N/C ratio affects the life cycle of the best-studied ichthyosporean model, Sphaeroforma arctica. We uncover that the last stages of cellularization coincide with a significant increase in the N/C ratio. Increasing the N/C ratio by reducing the coenocytic volume accelerates cellularization, whereas decreasing the N/C ratio by lowering the nuclear content halts it. Moreover, centrifugation and pharmacological inhibitor experiments suggest that the N/C ratio is locally sensed at the cortex and relies on phosphatase activity. Altogether, our results show that the N/C ratio drives cellularization in S. arctica, suggesting that its capacity to control multicellular development predates animal emergence.<br />Competing Interests: Declaration of interests The authors declare no competing interests.<br /> (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Subjects :
- Animals
Cell Nucleus
Cytosol
Genome
Eukaryota genetics
Mesomycetozoea genetics
Subjects
Details
- Language :
- English
- ISSN :
- 1879-0445
- Volume :
- 33
- Issue :
- 8
- Database :
- MEDLINE
- Journal :
- Current biology : CB
- Publication Type :
- Academic Journal
- Accession number :
- 36996815
- Full Text :
- https://doi.org/10.1016/j.cub.2023.03.019