RT Journal Article SR Electronic T1 Acquisition of cell identity in the brown alga Ectocarpus: which of time, cell shape or position matters most? JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.08.21.457218 DO 10.1101/2021.08.21.457218 A1 Bernard Billoud A1 Denis Saint-Marcoux A1 Sabine Chenivesse A1 Carole Duchêne A1 Camille Noûs A1 Jane A. Langdale A1 Bénédicte Charrier YR 2021 UL http://biorxiv.org/content/early/2021/08/22/2021.08.21.457218.abstract AB During development, cells undergo simultaneous changes of different types that together depict cell “identity”. In the multicellular brown alga Ectocarpus sp., while ageing, cells change shape and relative position within the filament. Understanding how these factors act and interact to specify cell identity requires markers of cell identity and the ability to genetically separate age, shape and position. Here we used laser capture microdissection (LCM) to isolate specific cell types from young sporophytes of Ectocarpus, and performed differential RNA-seq analysis. Transcriptome profiles of cell types in the wild-type strain provided signatures of the five cell types that can be identified by shape and position. In two mutants, where the relationship between cell shape, position and age are altered, transcriptome signatures revealed that little differential expression could be identified when only shape was perturbed. More generally, although the two mutants are characterised by opposite morphological phenotypes, their transcriptomes were remarkably similar. We concluded that despite the robustness of cell differentiation during WT development, neither the shape nor the position of the cell could serve as a faithful gauge for tracking differentiation.Competing Interest StatementThe authors have declared no competing interest.