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Duval KL, Artis AR, Goll MG. The emerging H3K9me3 chromatin landscape during zebrafish embryogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.05.582530. [PMID: 38496550 PMCID: PMC10942377 DOI: 10.1101/2024.03.05.582530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
The structural organization of eukaryotic genomes is contingent upon the fractionation of DNA into transcriptionally permissive euchromatin and repressive heterochromatin. However, we have a limited understanding of how these distinct states are first established during animal embryogenesis. Histone 3 lysine 9 trimethylation (H3K9me3) is critical to heterochromatin formation and bulk establishment of this mark is thought to help drive large-scale remodeling of an initially naive chromatin state during animal embryogenesis. However, a detailed understanding of this process is lacking. Here, we leverage CUT&RUN to define the emerging H3K9me3 landscape of the zebrafish embryo with high sensitivity and temporal resolution. Despite the prevalence of DNA transposons in the zebrafish genome, we found that LTR transposons are preferentially targeted for embryonic H3K9me3 deposition, with different families exhibiting distinct establishment timelines. High signal-to-noise ratios afforded by CUT&RUN revealed new, emerging sites of low-amplitude H3K9me3 that initiated before the major wave of zygotic genome activation (ZGA). Early sites of establishment predominated at specific subsets of transposons and were particularly enriched for transposon sequences with maternal piRNAs and pericentromeric localization. Notably, the number of H3K9me3 enriched sites increased linearly across blastula development, while quantitative comparison revealed a >10-fold genome-wide increase in H3K9me3 signal at established sites over just 30 minutes at the onset of ZGA. Continued maturation of the H3K9me3 landscape was observed beyond the initial wave of bulk establishment.
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Affiliation(s)
| | - Ashley R. Artis
- Department of Genetics, University of Georgia, Athens, GA, USA
| | - Mary G. Goll
- Department of Genetics, University of Georgia, Athens, GA, USA
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Wilson CA, Postlethwait JH. A maternal-to-zygotic-transition gene block on the zebrafish sex chromosome. G3 (BETHESDA, MD.) 2024; 14:jkae050. [PMID: 38466753 PMCID: PMC11075544 DOI: 10.1093/g3journal/jkae050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 02/22/2024] [Accepted: 03/01/2024] [Indexed: 03/13/2024]
Abstract
Wild zebrafish (Danio rerio) have a ZZ/ZW chromosomal sex-determination system with the major sex locus on the right arm of chromosome-4 (Chr4R) near the largest heterochromatic block in the genome, suggesting that Chr4R transcriptomics might differ from the rest of the genome. To test this hypothesis, we conducted an RNA-seq analysis of adult ZW ovaries and ZZ testes in the Nadia strain and identified 4 regions of Chr4 with different gene expression profiles. Unique in the genome, protein-coding genes in a 41.7 Mb section (Region-2) were expressed in testis but silent in ovary. The AB lab strain, which lacks sex chromosomes, verified this result, showing that testis-biased gene expression in Region-2 depends on gonad biology, not on sex-determining mechanism. RNA-seq analyses in female and male brains and livers validated reduced transcripts from Region-2 in somatic cells, but without sex specificity. Region-2 corresponds to the heterochromatic portion of Chr4R and its content of genes and repetitive elements distinguishes it from the rest of the genome. Region-2 lacks protein-coding genes with human orthologs; has zinc finger genes expressed early in zygotic genome activation; has maternal 5S rRNA genes, maternal spliceosome genes, a concentration of tRNA genes, and a distinct set of repetitive elements. The colocalization of (1) genes silenced in ovaries but not in testes that are (2) expressed in embryos briefly at the onset of zygotic genome activation; (3) maternal-specific genes for translation machinery; (4) maternal-specific spliceosome components; and (5) adjacent genes encoding miR-430, which mediates maternal transcript degradation, suggest that this is a maternal-to-zygotic-transition gene regulatory block.
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4
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Almeida MV, Blumer M, Yuan CU, Sierra P, Price JL, Quah FX, Friman A, Dallaire A, Vernaz G, Putman ALK, Smith AM, Joyce DA, Butter F, Haase AD, Durbin R, Santos ME, Miska EA. Dynamic co-evolution of transposable elements and the piRNA pathway in African cichlid fishes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.01.587621. [PMID: 38617250 PMCID: PMC11014572 DOI: 10.1101/2024.04.01.587621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
East African cichlid fishes have diversified in an explosive fashion, but the (epi)genetic basis of the phenotypic diversity of these fishes remains largely unknown. Although transposable elements (TEs) have been associated with phenotypic variation in cichlids, little is known about their transcriptional activity and epigenetic silencing. Here, we describe dynamic patterns of TE expression in African cichlid gonads and during early development. Orthology inference revealed an expansion of piwil1 genes in Lake Malawi cichlids, likely driven by PiggyBac TEs. The expanded piwil1 copies have signatures of positive selection and retain amino acid residues essential for catalytic activity. Furthermore, the gonads of African cichlids express a Piwi-interacting RNA (piRNA) pathway that target TEs. We define the genomic sites of piRNA production in African cichlids and find divergence in closely related species, in line with fast evolution of piRNA-producing loci. Our findings suggest dynamic co-evolution of TEs and host silencing pathways in the African cichlid radiations. We propose that this co-evolution has contributed to cichlid genomic diversity.
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Affiliation(s)
- Miguel Vasconcelos Almeida
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, UK
- Wellcome/CRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Moritz Blumer
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- These authors contributed equally
| | - Chengwei Ulrika Yuan
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, UK
- Wellcome/CRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- These authors contributed equally
| | - Pío Sierra
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Jonathan L. Price
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, UK
- Wellcome/CRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Fu Xiang Quah
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, UK
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Aleksandr Friman
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
- Biophysics Graduate Program, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - Alexandra Dallaire
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, UK
- Wellcome/CRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Comparative Fungal Biology, Royal Botanic Gardens Kew, Jodrell Laboratory, Richmond TW9 3DS, UK
| | - Grégoire Vernaz
- Wellcome/CRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- Present address: Zoological Institute, Department of Environmental Sciences, University of Basel, Vesalgasse 1, Basel, 4051, Switzerland
| | - Audrey L. K. Putman
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, UK
- Wellcome/CRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Alan M. Smith
- School of Natural Sciences, University of Hull, Hull, HU6 7RX, UK
| | - Domino A. Joyce
- School of Natural Sciences, University of Hull, Hull, HU6 7RX, UK
| | - Falk Butter
- Institute of Molecular Biology (IMB), Quantitative Proteomics, Ackermannweg 4, Mainz, 55128, Germany
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institute, Südufer, Greifswald, 17493, Germany
| | - Astrid D. Haase
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Richard Durbin
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- Wellcome Sanger Institute, Tree of Life, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - M. Emília Santos
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Eric A. Miska
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, UK
- Wellcome/CRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Wellcome Sanger Institute, Tree of Life, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
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Panyushev N, Selitskiy M, Melnichenko V, Lebedev E, Okorokova L, Adonin L. Dynamic Evolution of Repetitive Elements and Chromatin States in Apis mellifera Subspecies. Genes (Basel) 2024; 15:89. [PMID: 38254978 PMCID: PMC10815273 DOI: 10.3390/genes15010089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/07/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
In this study, we elucidate the contribution of repetitive DNA sequences to the establishment of social structures in honeybees (Apis mellifera). Despite recent advancements in understanding the molecular mechanisms underlying the formation of honeybee castes, primarily associated with Notch signaling, the comprehensive identification of specific genomic cis-regulatory sequences remains elusive. Our objective is to characterize the repetitive landscape within the genomes of two honeybee subspecies, namely A. m. mellifera and A. m. ligustica. An observed recent burst of repeats in A. m. mellifera highlights a notable distinction between the two subspecies. After that, we transitioned to identifying differentially expressed DNA elements that may function as cis-regulatory elements. Nevertheless, the expression of these sequences showed minimal disparity in the transcriptome during caste differentiation, a pivotal process in honeybee eusocial organization. Despite this, chromatin segmentation, facilitated by ATAC-seq, ChIP-seq, and RNA-seq data, revealed a distinct chromatin state associated with repeats. Lastly, an analysis of sequence divergence among elements indicates successive changes in repeat states, correlating with their respective time of origin. Collectively, these findings propose a potential role of repeats in acquiring novel regulatory functions.
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Affiliation(s)
- Nick Panyushev
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia; (N.P.); (M.S.)
- Bioinformatics Institute, 197342 St. Petersburg, Russia;
| | - Max Selitskiy
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia; (N.P.); (M.S.)
| | - Vasilina Melnichenko
- International Scientific and Research Institute of Bioengineering, ITMO University, 197101 St. Petersburg, Russia;
| | - Egor Lebedev
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia; (N.P.); (M.S.)
| | | | - Leonid Adonin
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia; (N.P.); (M.S.)
- Institute of Biomedical Chemistry, Group of Mechanisms for Nanosystems Targeted Delivery, 119121 Moscow, Russia
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Wilson CA, Postlethwait JH. A maternal-to-zygotic-transition gene block on the zebrafish sex chromosome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.06.570431. [PMID: 38106184 PMCID: PMC10723407 DOI: 10.1101/2023.12.06.570431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Wild zebrafish (Danio rerio) have a ZZ/ZW chromosomal sex determination system with the major sex locus on the right arm of chromosome-4 (Chr4R) near the largest heterochromatic block in the genome, suggesting the hypothesis that the Chr4R transcriptome might be different from the rest of the genome. We conducted an RNA-seq analysis of adult ZW ovaries and ZZ testes and identified four regions of Chr4 with different gene expression profiles. Unique in the genome, protein-coding genes in a 41.7 Mb section (Region-2) were expressed in testis but silent in ovary. The AB lab strain, which lacks sex chromosomes, verified this result, showing that testis-biased gene expression in Region-2 depends on gonad biology, not on sex-determining mechanism. RNA-seq analyses in female and male brain and liver validated few transcripts from Region-2 in somatic cells, but without sex-specificity. Region-2 corresponds to the heterochromatic portion of Chr4R and its content of genes and repetitive elements distinguishes it from the rest of the genome. In Region-2, protein-coding genes lack human orthologs; it has zinc finger genes expressed early in zygotic genome activation; it has maternal 5S rRNA genes, maternal spliceosome genes, a concentration of tRNA genes, and an distinct set of repetitive elements. The colocalization of 1) genes silenced in ovaries but not in testes that are 2) expressed in embryos briefly at the onset of zygotic genome activation; 3) maternal-specific genes for translation machinery; 4) maternal-specific spliceosome components; and 4) adjacent genes encoding miR-430, which mediates maternal transcript degradation, suggest that this is a Maternal-to-Zygotic-Transition Gene Regulatory Block.
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