Török A, Schiffer PH, Schnitzler CE, Ford K, Mullikin JC, Baxevanis AD, Bacic A, Frank U, Gornik SG. The cnidarian Hydractinia echinata employs canonical and highly adapted histones to pack its DNA.
Epigenetics Chromatin 2016;
9:36. [PMID:
27602058 PMCID:
PMC5011920 DOI:
10.1186/s13072-016-0085-1]
[Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/24/2016] [Indexed: 11/25/2022] Open
Abstract
Background
Cnidarians are a group of early branching animals including corals, jellyfish and hydroids that are renowned for their high regenerative ability, growth plasticity and longevity. Because cnidarian genomes are conventional in terms of protein-coding genes, their remarkable features are likely a consequence of epigenetic regulation. To facilitate epigenetics research in cnidarians, we analysed the histone complement of the cnidarian model organism Hydractinia echinata using phylogenomics, proteomics, transcriptomics and mRNA in situ hybridisations.
Results
We find that the Hydractinia genome encodes 19 histones and analyse their spatial expression patterns, genomic loci and replication-dependency. Alongside core and other replication-independent histone variants, we find several histone replication-dependent variants, including a rare replication-dependent H3.3, a female germ cell-specific H2A.X and an unusual set of five H2B variants, four of which are male germ cell-specific. We further confirm the absence of protamines in Hydractinia.
Conclusions
Since no protamines are found in hydroids, we suggest that the novel H2B variants are pivotal for sperm DNA packaging in this class of Cnidaria. This study adds to the limited number of full histone gene complements available in animals and sets a comprehensive framework for future studies on the role of histones and their post-translational modifications in cnidarian epigenetics. Finally, it provides insight into the evolution of spermatogenesis.
Electronic supplementary material
The online version of this article (doi:10.1186/s13072-016-0085-1) contains supplementary material, which is available to authorized users.
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