Faculty Opinions recommendation of OUROBOROS is a master regulator of the gametophyte to sporophyte life cycle transition in the brown alga Ectocarpus.

Field material of Herpodiscus durvillaeae, a New Zealand endemic parasitic brown alga growing in the thalli of Durvillaea antarctica, was studied in the laboratory. Pale zoids released from diminutive gametophytes, which were attached to the walls of unilocular sporangia and vegetative filaments of Herpodiscus, acted as isogametes. A heteromorphic life cycle with alternation of an endophytic parasitic sporophyte and a diminutive gametophyte is thus proposed for H. durvillaeae, and taxonomic implications of this life history are discussed. Key words: Herpodiscus durvillaeae, sexuality, life history, Phaeophyceae, Durvillaea antarctica, parasite.

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THE EFFECT OF TWO DIFFERENT PHOTOPERIODS ON THE OCCURRENCE OF MACRO-AND MICRO-THALLI IN THE LIFE CYCLE OF THE BROWN ALGA COLPOMENIA SINUOSA FROM THE FRENCH MEDITERRANEAN COAST

Cyclic Phenomena in Marine Plants and Animals ◽

10.1016/b978-0-08-023217-1.50068-0 ◽

1979 ◽

pp. 471

Author(s):

B. Caram

Keyword(s):

Life Cycle ◽

Brown Alga ◽

Mediterranean Coast

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Histone modifications during the life cycle of the brown alga Ectocarpus

Genome Biology ◽

10.1186/s13059-020-02216-8 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Simon Bourdareau ◽

Leila Tirichine ◽

Bérangère Lombard ◽

Damarys Loew ◽

Delphine Scornet ◽

...

Keyword(s):

Life Cycle ◽

Histone Modifications ◽

Brown Alga ◽

Land Plant ◽

Transcription Start ◽

Post Translational Modifications ◽

Transcription Start Sites ◽

Genomic Regions ◽

Active Genes

Abstract Background Brown algae evolved complex multicellularity independently of the animal and land plant lineages and are the third most developmentally complex phylogenetic group on the planet. An understanding of developmental processes in this group is expected to provide important insights into the evolutionary events necessary for the emergence of complex multicellularity. Here, we focus on mechanisms of epigenetic regulation involving post-translational modifications of histone proteins. Results A total of 47 histone post-translational modifications are identified, including a novel mark H2AZR38me1, but Ectocarpus lacks both H3K27me3 and the major polycomb complexes. ChIP-seq identifies modifications associated with transcription start sites and gene bodies of active genes and with transposons. H3K79me2 exhibits an unusual pattern, often marking large genomic regions spanning several genes. Transcription start sites of closely spaced, divergently transcribed gene pairs share a common nucleosome-depleted region and exhibit shared histone modification peaks. Overall, patterns of histone modifications are stable through the life cycle. Analysis of histone modifications at generation-biased genes identifies a correlation between the presence of specific chromatin marks and the level of gene expression. Conclusions The overview of histone post-translational modifications in the brown alga presented here will provide a foundation for future studies aimed at understanding the role of chromatin modifications in the regulation of brown algal genomes.

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Convergent recruitment of life cycle regulators to direct sporophyte development in two eukaryotic supergroups

10.1101/460436 ◽

2018 ◽

Author(s):

Alok Arun ◽

Susana M. Coelho ◽

Akira F. Peters ◽

Simon Bourdareau ◽

Laurent Peres ◽

...

Keyword(s):

Transcription Factors ◽

Life Cycle ◽

Amino Acid ◽

Green Algae ◽

Brown Alga ◽

Land Plants ◽

Developmental Program ◽

Cycle Regulation ◽

Sporophyte Development ◽

Green Lineage

AbstractThree amino acid loop extension homeodomain transcription factors (TALE HD TFs) act as life cycle regulators in green algae and land plants. In mosses these regulators are required for the deployment of the sporophyte developmental program. We demonstrate that mutations in either of two TALE HD TF genes, OUROBOROS or SAMSARA, in the brown alga Ectocarpus result in conversion of the sporophyte generation into a gametophyte. The OUROBOROS and SAMSARA proteins heterodimerise in a similar manner to TALE HD TF life cycle regulators in the green lineage. These observations demonstrate that TALE-HD-TF-based life cycle regulation systems have an extremely ancient origin, and that these systems have been independently recruited to regulate sporophyte developmental programs in at least two different complex multicellular eukaryotic supergroups, Archaeplastida and Chromalveolata.

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