Project description:Comparative Genome Hybridization of Ectocarpus siliculosus strains 371 (freshwater ecotype), 524 (copper-tolerant strain), and 568 (female strain), as well as E. fasciculatus strain 395 against the sequenced genome strain (32).
Project description:Reference reference hybridization with Ectocarpus siliculosus (strain Es 32) genomic DNA; Quality control for submission E-TABM-766
Project description:In UV sexual systems, sex is determined during the haploid phase of the life cycle and males have a V chromosome whereas females have a U chromosome. Previous work in the model Ectocarpus revealed that the V chromosome has a dominant role in male sex determination and the female developmental program being a ‘default’ program, triggered in the absence of the male master sex determination gene(s). Here, we describe the identification of a genetically male giant kelp strain presenting phenotypic features typical of a female, despite lacking the U-specific region. The conversion to the female developmental program is however incomplete, because gametes of this feminised male are unable to produce the sperm-attracting pheromone lamoxiren. We identify the transcriptomic pathways underlying the male and female specific developmental programs and show that the phenotypic feminisation of the variant strain is associated with both feminisation and de-masculinisation of gene expression patterns. Importantly, the feminisation phenotype was associated with the dramatic downregulation of two V-specific genes including a candidate sex-determining gene on the V-specific region. Our results reveal the transcriptional changes associated with sexual differentiation in a UV system with extensive sexual dimorphism, disentangling the role of sex-linked genes and autosomal gene expression in the initiation of the male and female developmental programs. Overall, the data presented here imply that the U-specific region in the giant kelp is not required to initiate the female developmental program, but is critical to produce fully functional eggs, arguing against the idea that female is the ‘default’ sex in this species.
Project description:The aim of the experiment is to identify Ectocarpus siliculosus (strain Ec32) genes which are up- or down-regulated by auxin. RNAs were extracted from sporophytes treated with auxin NAA 5.10-6M for 30min or 3h, and labelled either with Cy3 or Cy5. Biological triplicates were performed.
Project description:The aim of this study was to analyze genome-wide patterns of histone post-translational modifications (PTMs) and nucleosome distribution during the sporophyte and gametophyte generations of the life cycle of the brown alga Ectocarpus. Analysis of the results of this experiment along with those generated by a second experiment “Genome-wide analysis of chromatin states of Ectocarpus sporophytes and gametophytes, experiment 1” indicated that the histone PTMs H3K4me2, H3K4me3, H3K9ac, H3K14ac and H3K27ac are associated with the transcriptional start sites (TSSs) of actively expressed genes, H3K36me3 preferentially marks gene bodies and is associated with gene activation, H4K20me3 marks transposons and is associated with gene repression, probably through the silencing of transposons in introns. H3K79me2 occurs in zones corresponding to about a third of the genome. These zones often span several genes and genes within H3K79me2 zones exhibit lower levels of transcript abundance.
Project description:The aim of this study was to analyze genome-wide patterns of histone post-translational modifications (PTMs) and nucleosome distribution during the sporophyte and gametophyte generations of the life cycle of the brown alga Ectocarpus. Analysis of the results of this experiment along with those generated by a second experiment “Genome-wide analysis of chromatin states of Ectocarpus sporophytes and gametophytes, experiment 2” indicated that the histone PTMs H3K4me2, H3K4me3, H3K9ac, H3K14ac and H3K27ac are associated with the transcriptional start sites (TSSs) of actively expressed genes, H3K36me3 preferentially marks gene bodies and is associated with gene activation, H4K20me3 marks transposons and is associated with gene repression, probably through the silencing of transposons in introns. H3K79me2 occurs in zones corresponding to about a third of the genome. These zones often span several genes and genes within H3K79me2 zones exhibit lower levels of transcript abundance.
Project description:Here, we set out to understand the extent and nature of epigenomic changes associated with sexual differentiation in the brown alga Ectocarpus, which has a well described UV system. Five histone modifications, H3K4me3, H3K27Ac, H3K9Ac, H3K36me3, H4K20me3, were quantified in near-isogenic male and female lines, leading to the identification of 13 different chromatin states across the Ectocarpus genome that showed different patterns of enrichment at transcribed, silent, housekeeping or narrowly-expressed genes. Chromatin states were strongly correlated with levels of gene expression indicating a relationship between the assayed marks and gene transcription. The relative proportion of each chromatin state across the genome remained stable in males and females, but a subset of genes exhibited different chromatin states in the two sexes. In particular, males and females displayed distinct patterns of histone modifications at sex-biased genes, indicating that chromatin state transitions occur preferentially at genes involved in sex-specific pathways. Finally, our results reveal the unique chromatin landscape of the U and V sex chromosomes compared to autosomes. Taken together, our observations reveal a role for histone modifications in sex determination and sexual differentiation in a UV sexual system, and suggest that the mechanisms of epigenetic regulation of genes on the U/V sex chromosomes may differ from those operating on autosomal genes.