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Marinov GK, Chen X, Swaffer MP, Xiang T, Grossman AR, Greenleaf WJ. Genome-wide distribution of 5-hydroxymethyluracil and chromatin accessibility in the Breviolum minutum genome. Genome Biol 2024; 25:115. [PMID: 38711126 PMCID: PMC11071213 DOI: 10.1186/s13059-024-03261-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 04/28/2024] [Indexed: 05/08/2024] Open
Abstract
BACKGROUND In dinoflagellates, a unique and extremely divergent genomic and nuclear organization has evolved. The highly unusual features of dinoflagellate nuclei and genomes include permanently condensed liquid crystalline chromosomes, primarily packaged by proteins other than histones, genes organized in very long unidirectional gene arrays, a general absence of transcriptional regulation, high abundance of the otherwise very rare DNA modification 5-hydroxymethyluracil (5-hmU), and many others. While most of these fascinating properties are originally identified in the 1970s and 1980s, they have not yet been investigated using modern genomic tools. RESULTS In this work, we address some of the outstanding questions regarding dinoflagellate genome organization by mapping the genome-wide distribution of 5-hmU (using both immunoprecipitation-based and basepair-resolution chemical mapping approaches) and of chromatin accessibility in the genome of the Symbiodiniaceae dinoflagellate Breviolum minutum. We find that the 5-hmU modification is preferentially enriched over certain classes of repetitive elements, often coincides with the boundaries between gene arrays, and is generally correlated with decreased chromatin accessibility, the latter otherwise being largely uniform along the genome. We discuss the potential roles of 5-hmU in the functional organization of dinoflagellate genomes and its relationship to the transcriptional landscape of gene arrays. CONCLUSIONS Our results provide the first window into the 5-hmU and chromatin accessibility landscapes in dinoflagellates.
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Affiliation(s)
- Georgi K Marinov
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA.
| | - Xinyi Chen
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Matthew P Swaffer
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Tingting Xiang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - William J Greenleaf
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA.
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, 94305, USA.
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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2
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Wang H, Wu P, Xiong L, Kim HS, Kim JH, Ki JS. Nuclear genome of dinoflagellates: Size variation and insights into evolutionary mechanisms. Eur J Protistol 2024; 93:126061. [PMID: 38394997 DOI: 10.1016/j.ejop.2024.126061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024]
Abstract
Recent progress in high-throughput sequencing technologies has dramatically increased availability of genome data for prokaryotes and eukaryotes. Dinoflagellates have distinct chromosomes and a huge genome size, which make their genomic analysis complicated. Here, we reviewed the nuclear genomes of core dinoflagellates, focusing on the genome and cell size. Till now, the genome sizes of several dinoflagellates (more than 25) have been measured by certain methods (e.g., flow cytometry), showing a range of 3-250 pg of genomic DNA per cell. In contrast to their relatively small cell size, their genomes are huge (about 1-80 times the human haploid genome). In the present study, we collected the genome and cell size data of dinoflagellates and compared their relationships. We found that dinoflagellate genome size exhibits a positive correlation with cell size. On the other hand, we recognized that the genome size is not correlated with phylogenetic relatedness. These may be caused by genome duplication, increased gene copy number, repetitive non-coding DNA, transposon expansion, horizontal gene transfer, organelle-to-nucleus gene transfer, and/or mRNA reintegration into the genome. Ultimate verification of these factors as potential causative mechanisms would require sequencing of more dinoflagellate genomes in the future.
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Affiliation(s)
- Hui Wang
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, Hengyang Medical School, University of South China, Hengyang 421001, China; Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea
| | - Peiling Wu
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, Hengyang Medical School, University of South China, Hengyang 421001, China
| | - Lu Xiong
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, Hengyang Medical School, University of South China, Hengyang 421001, China
| | - Han-Sol Kim
- Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea
| | - Jin Ho Kim
- Department of Earth and Marine Science, College of Ocean Sciences, Jeju National University, Jeju 63243, Republic of Korea
| | - Jang-Seu Ki
- Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea; Department of Biotechnology, Sangmyung University, Seoul 03016, Republic of Korea.
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Carnicer O, Hu YY, Ebenezer V, Irwin AJ, Finkel ZV. Genomic architecture constrains macromolecular allocation in dinoflagellates. Protist 2023; 174:125992. [PMID: 37738738 DOI: 10.1016/j.protis.2023.125992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/21/2023] [Accepted: 09/11/2023] [Indexed: 09/24/2023]
Abstract
Dinoflagellate genomes have a unique architecture that may constrain their physiological and biochemical responsiveness to environmental stressors. Here we quantified how nitrogen (N) starvation influenced macromolecular allocation and C:N:P of three photosynthetic marine dinoflagellates, representing different taxonomic classes and genome sizes. Dinoflagellates respond to nitrogen starvation by decreasing cellular nitrogen, protein and RNA content, but unlike many other eukaryotic phytoplankton examined RNA:protein is invariant. Additionally, 2 of the 3 species exhibit increases in cellular phosphorus and very little change in cellular carbon with N-starvation. As a consequence, N starvation induces moderate increases in C:N, but extreme decreases in N:P and C:P, relative to diatoms. Dinoflagellate DNA content relative to total C, N and P is much higher than similar sized diatoms, but similar to very small photosynthetic picoeukaryotes such as Ostreococcus. In aggregate these results indicate the accumulation of phosphate stores may be an important strategy employed by dinoflagellates to meet P requirements associated with the maintenance and replication of their large genomes.
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Affiliation(s)
- Olga Carnicer
- Department of Oceanography, Dalhousie University, Halifax, Canada
| | - Ying-Yu Hu
- Department of Oceanography, Dalhousie University, Halifax, Canada
| | - Vinitha Ebenezer
- Department of Oceanography, Dalhousie University, Halifax, Canada
| | - Andrew J Irwin
- Department of Mathematics & Statistics, Dalhousie University, Halifax, Canada
| | - Zoe V Finkel
- Department of Oceanography, Dalhousie University, Halifax, Canada.
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Marinov GK, Chen X, Swaffer MP, Xiang T, Grossman AR, Greenleaf WJ. Genome-wide distribution of 5-hydroxymethyluracil and chromatin accessibility in the Breviolum minutum genome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.18.558303. [PMID: 37781619 PMCID: PMC10541103 DOI: 10.1101/2023.09.18.558303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
In dinoflagellates, a unique and extremely divergent genomic and nuclear organization has evolved. The highly unusual features of dinoflagellate nuclei and genomes include permanently condensed liquid crystalline chromosomes, primarily packaged by proteins other than histones, genes organized in very long unidirectional gene arrays, a general absence of transcriptional regulation, high abundance of the otherwise very rare DNA modification 5-hydroxymethyluracil (5-hmU), and many others. While most of these fascinating properties were originally identified in the 1970s and 1980s, they have not yet been investigated using modern genomic tools. In this work, we address some of the outstanding questions regarding dinoflagellate genome organization by mapping the genome-wide distribution of 5-hmU (using both immunoprecipitation-based and basepair-resolution chemical mapping approaches) and of chromatin accessibility in the genome of the Symbiodiniaceae dinoflagellate Breviolum minutum. We find that the 5-hmU modification is preferentially enriched over certain classes of repetitive elements, often coincides with the boundaries between gene arrays, and is generally correlated with decreased chromatin accessibility, the latter otherwise being largely uniform along the genome. We discuss the potential roles of 5-hmU in the functional organization of dinoflagellate genomes and its relationship to the transcriptional landscape of gene arrays.
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Affiliation(s)
- Georgi K Marinov
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Xinyi Chen
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA
| | | | - Tingting Xiang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, USA
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, USA
| | - William J Greenleaf
- Department of Genetics, Stanford University, Stanford, California 94305, USA
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, California 94305, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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5
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Zaheri B, Morse D. An overview of transcription in dinoflagellates. Gene 2022; 829:146505. [PMID: 35447242 DOI: 10.1016/j.gene.2022.146505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 02/18/2022] [Accepted: 04/14/2022] [Indexed: 11/25/2022]
Abstract
Dinoflagellates are a vital diverse family of unicellular algae widespread in various aquatic environments. Typically large genomes and permanently condensed chromosomes without histones make these organisms unique among eukaryotes in terms of chromatin structure and gene expression. Genomic and transcriptomic sequencing projects have provided new insight into the genetic foundation of dinoflagellate behaviors. Genes in tandem arrays, trans-splicing of mRNAs and lower levels of transcriptional regulation compared to other eukaryotes all contribute to the differences seen. Here we present a general overview of transcription in dinoflagellates based on previously described work.
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Affiliation(s)
- Bahareh Zaheri
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, 4101 Sherbrooke est, Université de Montréal, Montréal H1X 2B2, Canada
| | - David Morse
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, 4101 Sherbrooke est, Université de Montréal, Montréal H1X 2B2, Canada.
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O’Brown ZK, Greer EL. N6-methyladenine: A Rare and Dynamic DNA Mark. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1389:177-210. [DOI: 10.1007/978-3-031-11454-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Dai Y, Yuan BF, Feng YQ. Quantification and mapping of DNA modifications. RSC Chem Biol 2021; 2:1096-1114. [PMID: 34458826 PMCID: PMC8341653 DOI: 10.1039/d1cb00022e] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 05/20/2021] [Indexed: 12/13/2022] Open
Abstract
Apart from the four canonical nucleobases, DNA molecules carry a number of natural modifications. Substantial evidence shows that DNA modifications can regulate diverse biological processes. Dynamic and reversible modifications of DNA are critical for cell differentiation and development. Dysregulation of DNA modifications is closely related to many human diseases. The research of DNA modifications is a rapidly expanding area and has been significantly stimulated by the innovations of analytical methods. With the recent advances in methods and techniques, a series of new DNA modifications have been discovered in the genomes of prokaryotes and eukaryotes. Deciphering the biological roles of DNA modifications depends on the sensitive detection, accurate quantification, and genome-wide mapping of modifications in genomic DNA. This review provides an overview of the recent advances in analytical methods and techniques for both the quantification and genome-wide mapping of natural DNA modifications. We discuss the principles, advantages, and limitations of these developed methods. It is anticipated that new methods and techniques will resolve the current challenges in this burgeoning research field and expedite the elucidation of the functions of DNA modifications.
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Affiliation(s)
- Yi Dai
- Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University Wuhan 430072 P. R. China +86-27-68755595 +86-27-68755595
| | - Bi-Feng Yuan
- Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University Wuhan 430072 P. R. China +86-27-68755595 +86-27-68755595
- School of Health Sciences, Wuhan University Wuhan 430071 China
| | - Yu-Qi Feng
- Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University Wuhan 430072 P. R. China +86-27-68755595 +86-27-68755595
- School of Health Sciences, Wuhan University Wuhan 430071 China
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8
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Affiliation(s)
- Bi-Feng Yuan
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry and Sauvage Center for Molecular Sciences, Wuhan University, Wuhan 430072, P.R. China
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9
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Omics Analysis for Dinoflagellates Biology Research. Microorganisms 2019; 7:microorganisms7090288. [PMID: 31450827 PMCID: PMC6780300 DOI: 10.3390/microorganisms7090288] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/20/2019] [Accepted: 08/21/2019] [Indexed: 01/13/2023] Open
Abstract
Dinoflagellates are important primary producers for marine ecosystems and are also responsible for certain essential components in human foods. However, they are also notorious for their ability to form harmful algal blooms, and cause shellfish poisoning. Although much work has been devoted to dinoflagellates in recent decades, our understanding of them at a molecular level is still limited owing to some of their challenging biological properties, such as large genome size, permanently condensed liquid-crystalline chromosomes, and the 10-fold lower ratio of protein to DNA than other eukaryotic species. In recent years, omics technologies, such as genomics, transcriptomics, proteomics, and metabolomics, have been applied to the study of marine dinoflagellates and have uncovered many new physiological and metabolic characteristics of dinoflagellates. In this article, we review recent application of omics technologies in revealing some of the unusual features of dinoflagellate genomes and molecular mechanisms relevant to their biology, including the mechanism of harmful algal bloom formations, toxin biosynthesis, symbiosis, lipid biosynthesis, as well as species identification and evolution. We also discuss the challenges and provide prospective further study directions and applications of dinoflagellates.
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10
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Gornik SG, Hu I, Lassadi I, Waller RF. The Biochemistry and Evolution of the Dinoflagellate Nucleus. Microorganisms 2019; 7:microorganisms7080245. [PMID: 31398798 PMCID: PMC6723414 DOI: 10.3390/microorganisms7080245] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/05/2019] [Accepted: 08/07/2019] [Indexed: 12/14/2022] Open
Abstract
Dinoflagellates are known to possess a highly aberrant nucleus-the so-called dinokaryon-that exhibits a multitude of exceptional biological features. These include: (1) Permanently condensed chromosomes; (2) DNA in a cholesteric liquid crystalline state, (3) extremely large DNA content (up to 200 pg); and, perhaps most strikingly, (4) a deficit of histones-the canonical building blocks of all eukaryotic chromatin. Dinoflagellates belong to the Alveolata clade (dinoflagellates, apicomplexans, and ciliates) and, therefore, the biological oddities observed in dinoflagellate nuclei are derived character states. Understanding the sequence of changes that led to the dinokaryon has been difficult in the past with poor resolution of dinoflagellate phylogeny. Moreover, lack of knowledge of their molecular composition has constrained our understanding of the molecular properties of these derived nuclei. However, recent advances in the resolution of the phylogeny of dinoflagellates, particularly of the early branching taxa; the realization that divergent histone genes are present; and the discovery of dinoflagellate-specific nuclear proteins that were acquired early in dinoflagellate evolution have all thrown new light nature and evolution of the dinokaryon.
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Affiliation(s)
- Sebastian G Gornik
- Centre for Organismal Studies (COS), Universität Heidelberg, 69120 Heidelberg, Germany.
| | - Ian Hu
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Imen Lassadi
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Ross F Waller
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
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Verma A, Barua A, Ruvindy R, Savela H, Ajani PA, Murray SA. The Genetic Basis of Toxin Biosynthesis in Dinoflagellates. Microorganisms 2019; 7:E222. [PMID: 31362398 PMCID: PMC6722697 DOI: 10.3390/microorganisms7080222] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 07/23/2019] [Accepted: 07/27/2019] [Indexed: 02/07/2023] Open
Abstract
In marine ecosystems, dinoflagellates can become highly abundant and even dominant at times, despite their comparatively slow growth rates. One factor that may play a role in their ecological success is the production of complex secondary metabolite compounds that can have anti-predator, allelopathic, or other toxic effects on marine organisms, and also cause seafood poisoning in humans. Our knowledge about the genes involved in toxin biosynthesis in dinoflagellates is currently limited due to the complex genomic features of these organisms. Most recently, the sequencing of dinoflagellate transcriptomes has provided us with valuable insights into the biosynthesis of polyketide and alkaloid-based toxin molecules in dinoflagellate species. This review synthesizes the recent progress that has been made in understanding the evolution, biosynthetic pathways, and gene regulation in dinoflagellates with the aid of transcriptomic and other molecular genetic tools, and provides a pathway for future studies of dinoflagellates in this exciting omics era.
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Affiliation(s)
- Arjun Verma
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia.
| | - Abanti Barua
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia
- Department of Microbiology, Noakhali Science and Technology University, Chittagong 3814, Bangladesh
| | - Rendy Ruvindy
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia
| | - Henna Savela
- Finnish Environment Institute, Marine Research Centre, 00790 Helsinki, Finland
| | - Penelope A Ajani
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia
| | - Shauna A Murray
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia
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12
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Li C, Wong JTY. DNA Damage Response Pathways in Dinoflagellates. Microorganisms 2019; 7:E191. [PMID: 31284474 PMCID: PMC6680887 DOI: 10.3390/microorganisms7070191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/29/2019] [Accepted: 07/01/2019] [Indexed: 12/17/2022] Open
Abstract
Dinoflagellates are a general group of phytoplankton, ubiquitous in aquatic environments. Most dinoflagellates are non-obligate autotrophs, subjected to potential physical and chemical DNA-damaging agents, including UV irradiation, in the euphotic zone. Delay of cell cycles by irradiation, as part of DNA damage responses (DDRs), could potentially lead to growth inhibition, contributing to major errors in the estimation of primary productivity and interpretations of photo-inhibition. Their liquid crystalline chromosomes (LCCs) have large amount of abnormal bases, restricted placement of coding sequences at the chromosomes periphery, and tandem repeat-encoded genes. These chromosome characteristics, their large genome sizes, as well as the lack of architectural nucleosomes, likely contribute to possible differential responses to DNA damage agents. In this study, we sought potential dinoflagellate orthologues of eukaryotic DNA damage repair pathways, and the linking pathway with cell-cycle control in three dinoflagellate species. It appeared that major orthologues in photoreactivation, base excision repair, nucleotide excision repair, mismatch repair, double-strand break repair and homologous recombination repair are well represented in dinoflagellate genomes. Future studies should address possible differential DNA damage responses of dinoflagellates over other planktonic groups, especially in relation to possible shift of life-cycle transitions in responses to UV irradiation. This may have a potential role in the persistence of dinoflagellate red tides with the advent of climatic change.
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Affiliation(s)
- Chongping Li
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China.
- Division of Life Science, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China.
| | - Joseph Tin Yum Wong
- Division of Life Science, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China.
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Boháčová S, Ludvíková L, Poštová Slavětínská L, Vaníková Z, Klán P, Hocek M. Protected 5-(hydroxymethyl)uracil nucleotides bearing visible-light photocleavable groups as building blocks for polymerase synthesis of photocaged DNA. Org Biomol Chem 2019; 16:1527-1535. [PMID: 29431832 DOI: 10.1039/c8ob00160j] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Nucleosides, nucleotides and 2'-deoxyribonucleoside triphosphates (dNTPs) containing 5-(hydroxymethyl)uracil protected with photocleavable groups (2-nitrobenzyl-, 6-nitropiperonyl or 9-anthrylmethyl) were prepared and tested as building blocks for the polymerase synthesis of photocaged oligonucleotides and DNA. Photodeprotection (photorelease) reactions were studied in detail on model nucleoside monophosphates and their photoreaction quantum yields were determined. Photocaged dNTPs were then tested and used as substrates for DNA polymerases in primer extension or PCR. DNA probes containing photocaged or free 5-hydroxymethylU in the recognition sequence of restriction endonucleases were prepared and used for the study of photorelease of caged DNA by UV or visible light at different wavelengths. The nitropiperonyl-protected nucleotide was found to be a superior building block because the corresponding dNTP is a good substrate for DNA polymerases, and the protecting group is efficiently cleavable by irradiation by UV or visible light (up to 425 nm).
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Affiliation(s)
- Soňa Boháčová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo namesti 2, CZ-16610 Prague 6, Czech Republic.
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Riaz S, Sui Z, Niaz Z, Khan S, Liu Y, Liu H. Distinctive Nuclear Features of Dinoflagellates with A Particular Focus on Histone and Histone-Replacement Proteins. Microorganisms 2018; 6:E128. [PMID: 30558155 PMCID: PMC6313786 DOI: 10.3390/microorganisms6040128] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 11/29/2018] [Accepted: 12/11/2018] [Indexed: 11/30/2022] Open
Abstract
Dinoflagellates are important eukaryotic microorganisms that play critical roles as producers and grazers, and cause harmful algal blooms. The unusual nuclei of dinoflagellates "dinokaryon" have led researchers to investigate their enigmatic nuclear features. Their nuclei are unusual in terms of their permanently condensed nucleosome-less chromatin, immense genome, low protein to DNA ratio, guanine-cytosine rich methylated DNA, and unique mitosis process. Furthermore, dinoflagellates are the only known group of eukaryotes that apparently lack histone proteins. Over the course of evolution, dinoflagellates have recruited other proteins, e.g., histone-like proteins (HLPs), from bacteria and dinoflagellates/viral nucleoproteins (DVNPs) from viruses as histone substitutes. Expression diversity of these nucleoproteins has greatly influenced the chromatin structure and gene expression regulation in dinoflagellates. Histone replacement proteins (HLPs and DVNPs) are hypothesized to perform a few similar roles as histone proteins do in other eukaryotes, i.e., gene expression regulation and repairing DNA. However, their role in bulk packaging of DNA is not significant as low amounts of proteins are associated with the gigantic genome. This review intends to summarize the discoveries encompassing unique nuclear features of dinoflagellates, particularly focusing on histone and histone replacement proteins. In addition, a comprehensive view of the evolution of dinoflagellate nuclei is presented.
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Affiliation(s)
- Sadaf Riaz
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China.
- Department of Microbiology, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan.
| | - Zhenghong Sui
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China.
| | - Zeeshan Niaz
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China.
- Department of Microbiology, Hazara University, Mansehra 21120, Pakistan.
| | - Sohrab Khan
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China.
- Department of Microbiology, Hazara University, Mansehra 21120, Pakistan.
| | - Yuan Liu
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China.
| | - Haoxin Liu
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China.
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Roy S, Jagus R, Morse D. Translation and Translational Control in Dinoflagellates. Microorganisms 2018; 6:microorganisms6020030. [PMID: 29642465 PMCID: PMC6027434 DOI: 10.3390/microorganisms6020030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 12/24/2022] Open
Abstract
Dinoflagellates are unicellular protists that feature a multitude of unusual nuclear features, including large genomes, packaging of DNA without histones, and multiple gene copies organized as tandem gene arrays. Furthermore, all dinoflagellate mRNAs experience trans-splicing with a common 22-nucleotide splice leader (SL) sequence. These features challenge some of the concepts and assumptions about the regulation of gene expression derived from work on model eukaryotes such as yeasts and mammals. Translational control in the dinoflagellates, based on extensive study of circadian bioluminescence and by more recent microarray and transcriptome analyses, is now understood to be a crucial element in regulating gene expression. A picture of the translation machinery of dinoflagellates is emerging from the recent availability of transcriptomes of multiple dinoflagellate species and the first complete genome sequences. The components comprising the translational control toolkit of dinoflagellates are beginning to take shape and are outlined here.
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Affiliation(s)
- Sougata Roy
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, 4101 Sherbrooke East, Montréal, QC H1X 2B2, Canada.
| | - Rosemary Jagus
- Institute of Marine & Environmental Technology, University of Maryland Center for Environmental Science701 E. Pratt St., Baltimore, MD 21202, USA.
| | - David Morse
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, 4101 Sherbrooke East, Montréal, QC H1X 2B2, Canada.
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Carell T, Kurz MQ, Müller M, Rossa M, Spada F. Non-canonical Bases in the Genome: The Regulatory Information Layer in DNA. Angew Chem Int Ed Engl 2018; 57:4296-4312. [DOI: 10.1002/anie.201708228] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Indexed: 01/06/2023]
Affiliation(s)
- Thomas Carell
- Center for Integrated Protein Science; Department of Chemistry; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 81377 Munich Germany
| | - Matthias Q. Kurz
- Center for Integrated Protein Science; Department of Chemistry; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 81377 Munich Germany
| | - Markus Müller
- Center for Integrated Protein Science; Department of Chemistry; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 81377 Munich Germany
| | - Martin Rossa
- Center for Integrated Protein Science; Department of Chemistry; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 81377 Munich Germany
| | - Fabio Spada
- Center for Integrated Protein Science; Department of Chemistry; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 81377 Munich Germany
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Janoušková M, Vaníková Z, Nici F, Boháčová S, Vítovská D, Šanderová H, Hocek M, Krásný L. 5-(Hydroxymethyl)uracil and -cytosine as potential epigenetic marks enhancing or inhibiting transcription with bacterial RNA polymerase. Chem Commun (Camb) 2017; 53:13253-13255. [DOI: 10.1039/c7cc08053k] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
5-(Hydroxymethyl)uracil and -cytosine in DNA templates regulate transcription by bacterial RNA polymerase depending on the promoter, indicating that they may act as epigenetic marks.
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Affiliation(s)
- Martina Janoušková
- Dept. of Molecular Genetics of Bacteria
- Institute of Microbiology of the Czech Academy of Sciences
- CZ-14220 Prague 4
- Czech Republic
| | - Zuzana Vaníková
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences
- 16610 Prague 6
- Czech Republic
| | - Fabrizia Nici
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences
- 16610 Prague 6
- Czech Republic
| | - Soňa Boháčová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences
- 16610 Prague 6
- Czech Republic
| | - Dragana Vítovská
- Dept. of Molecular Genetics of Bacteria
- Institute of Microbiology of the Czech Academy of Sciences
- CZ-14220 Prague 4
- Czech Republic
| | - Hana Šanderová
- Dept. of Molecular Genetics of Bacteria
- Institute of Microbiology of the Czech Academy of Sciences
- CZ-14220 Prague 4
- Czech Republic
| | - Michal Hocek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences
- 16610 Prague 6
- Czech Republic
- Dept. of Organic Chemistry
- Faculty of Science, Charles University in Prague
| | - Libor Krásný
- Dept. of Molecular Genetics of Bacteria
- Institute of Microbiology of the Czech Academy of Sciences
- CZ-14220 Prague 4
- Czech Republic
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O'Brown ZK, Greer EL. N6-Methyladenine: A Conserved and Dynamic DNA Mark. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 945:213-246. [PMID: 27826841 DOI: 10.1007/978-3-319-43624-1_10] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Chromatin, consisting of deoxyribonucleic acid (DNA) wrapped around histone proteins, facilitates DNA compaction and allows identical DNA codes to confer many different cellular phenotypes. This biological versatility is accomplished in large part by posttranslational modifications to histones and chemical modifications to DNA. These modifications direct the cellular machinery to expand or compact specific chromatin regions and mark regions of the DNA as important for cellular functions. While each of the four bases that make up DNA can be modified (Iyer et al. 2011), this chapter will focus on methylation of the sixth position on adenines (6mA), as this modification has been poorly characterized in recently evolved eukaryotes, but shows promise as a new conserved layer of epigenetic regulation. 6mA was previously thought to be restricted to unicellular organisms, but recent work has revealed its presence in metazoa. Here, we will briefly describe the history of 6mA, examine its evolutionary conservation, and evaluate the current methods for detecting 6mA. We will discuss the enzymes that bind and regulate this mark and finally examine known and potential functions of 6mA in eukaryotes.
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Affiliation(s)
- Zach Klapholz O'Brown
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | - Eric Lieberman Greer
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA. .,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
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20
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Rosic N, Ling EYS, Chan CKK, Lee HC, Kaniewska P, Edwards D, Dove S, Hoegh-Guldberg O. Unfolding the secrets of coral-algal symbiosis. ISME JOURNAL 2015; 9:844-56. [PMID: 25343511 DOI: 10.1038/ismej.2014.182] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 08/05/2014] [Accepted: 08/25/2014] [Indexed: 11/09/2022]
Abstract
Dinoflagellates from the genus Symbiodinium form a mutualistic symbiotic relationship with reef-building corals. Here we applied massively parallel Illumina sequencing to assess genetic similarity and diversity among four phylogenetically diverse dinoflagellate clades (A, B, C and D) that are commonly associated with corals. We obtained more than 30,000 predicted genes for each Symbiodinium clade, with a majority of the aligned transcripts corresponding to sequence data sets of symbiotic dinoflagellates and <2% of sequences having bacterial or other foreign origin. We report 1053 genes, orthologous among four Symbiodinium clades, that share a high level of sequence identity to known proteins from the SwissProt (SP) database. Approximately 80% of the transcripts aligning to the 1053 SP genes were unique to Symbiodinium species and did not align to other dinoflagellates and unrelated eukaryotic transcriptomes/genomes. Six pathways were common to all four Symbiodinium clades including the phosphatidylinositol signaling system and inositol phosphate metabolism pathways. The list of Symbiodinium transcripts common to all four clades included conserved genes such as heat shock proteins (Hsp70 and Hsp90), calmodulin, actin and tubulin, several ribosomal, photosynthetic and cytochrome genes and chloroplast-based heme-containing cytochrome P450, involved in the biosynthesis of xanthophylls. Antioxidant genes, which are important in stress responses, were also preserved, as were a number of calcium-dependent and calcium/calmodulin-dependent protein kinases that may play a role in the establishment of symbiosis. Our findings disclose new knowledge about the genetic uniqueness of symbiotic dinoflagellates and provide a list of homologous genes important for the foundation of coral-algal symbiosis.
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Affiliation(s)
- Nedeljka Rosic
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Edmund Yew Siang Ling
- University of Queensland Centre for Clinical Research, The University of Queensland, Herston, Queensland, Australia
| | - Chon-Kit Kenneth Chan
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Hong Ching Lee
- The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Paulina Kaniewska
- 1] School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia [2] Australian Institute of Marine Science, Townsville, Queensland, Australia
| | - David Edwards
- 1] School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland, Australia [2] School of Plant Biology, University of Western Australia, Perth, Western Australia, Australia [3] Australian Centre for Plant Functional Genomics, The University of Queensland, St Lucia, Queensland, Australia
| | - Sophie Dove
- 1] School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia [2] ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Queensland, Australia
| | - Ove Hoegh-Guldberg
- 1] School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia [2] ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Queensland, Australia [3] Global Change Institute and ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Queensland, Australia
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21
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Vaníková Z, Hocek M. Polymerase Synthesis of Photocaged DNA Resistant against Cleavage by Restriction Endonucleases. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201402370] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Vaníková Z, Hocek M. Polymerase synthesis of photocaged DNA resistant against cleavage by restriction endonucleases. Angew Chem Int Ed Engl 2014; 53:6734-7. [PMID: 24850380 DOI: 10.1002/anie.201402370] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 04/23/2014] [Indexed: 12/12/2022]
Abstract
5-[(2-Nitrobenzyl)oxymethyl]-2'-deoxyuridine 5'-O-triphosphate was used for polymerase (primer extension or PCR) synthesis of photocaged DNA that is resistant to the cleavage by restriction endonucleases. Photodeprotection of the caged DNA released 5-hydroxymethyluracil-modified nucleic acids, which were fully recognized and cleaved by restriction enzymes.
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Affiliation(s)
- Zuzana Vaníková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences & IOCB Research Center, Flemingovo nám. 2, 16610 Prague 6 (Czech Republic) http://www.uochb.cas.cz/hocekgroup
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Roy S, Letourneau L, Morse D. Cold-induced cysts of the photosynthetic dinoflagellate Lingulodinium polyedrum have an arrested circadian bioluminescence rhythm and lower levels of protein phosphorylation. PLANT PHYSIOLOGY 2014; 164:966-977. [PMID: 24335505 PMCID: PMC3912119 DOI: 10.1104/pp.113.229856] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 12/09/2013] [Indexed: 06/03/2023]
Abstract
Dinoflagellates are microscopic, eukaryotic, and primarily marine plankton. Temporary cyst formation is a well-known physiological response of dinoflagellate cells to environmental stresses. However, the molecular underpinnings of cold-induced cyst physiology have never been described. Cultures of the photosynthetic dinoflagellate Lingulodinium polyedrum readily form temporary cysts when placed at low (8°C±1°C) temperature and excyst to form normal motile cells following a return to normal temperature (18°C±1°C). The normal circadian bioluminescence rhythm and the expected changes in Luciferin Binding Protein abundance were arrested in L. polyedrum cysts. Furthermore, after excystment, the bioluminescence rhythm initiates at a time corresponding to zeitgeber 12, independent of the time when the cells encysted. Phosphoprotein staining after two-dimensional polyacrylamide gel electrophoresis, as well as column-based phosphoprotein enrichment followed by liquid chromatography tandem mass spectrometry, showed cyst proteins are hypophosphorylated when compared with those from motile cells, with the most marked decreases found for predicted Casein Kinase2 target sites. In contrast to the phosphoproteome, the cyst proteome is not markedly different from motile cells, as assessed by two-dimensional polyacrylamide gel electrophoresis. In addition to changes in the phosphoproteome, RNA sequencing revealed that cysts show a significant decrease in the levels of 132 RNAs. Of the 42 RNAs that were identified by sequence analysis, 21 correspond to plastid-encoded gene products and 11 to nuclear-encoded cell wall/plasma membrane components. Our data are consistent with a model in which the highly reduced metabolism in cysts is achieved primarily by alterations in the phosphoproteome. The stalling of the circadian rhythm suggests temporary cysts may provide an interesting model to address the circadian system of dinoflagellates.
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Transcription and Maturation of mRNA in Dinoflagellates. Microorganisms 2013; 1:71-99. [PMID: 27694765 PMCID: PMC5029490 DOI: 10.3390/microorganisms1010071] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/10/2013] [Accepted: 10/14/2013] [Indexed: 01/17/2023] Open
Abstract
Dinoflagellates are of great importance to the marine ecosystem, yet scant details of how gene expression is regulated at the transcriptional level are available. Transcription is of interest in the context of the chromatin structure in the dinoflagellates as it shows many differences from more typical eukaryotic cells. Here we canvas recent transcriptome profiles to identify the molecular building blocks available for the construction of the transcriptional machinery and contrast these with those used by other systems. Dinoflagellates display a clear paucity of specific transcription factors, although surprisingly, the rest of the basic transcriptional machinery is not markedly different from what is found in the close relatives to the dinoflagellates.
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Symbiodinium transcriptomes: genome insights into the dinoflagellate symbionts of reef-building corals. PLoS One 2012; 7:e35269. [PMID: 22529998 PMCID: PMC3329448 DOI: 10.1371/journal.pone.0035269] [Citation(s) in RCA: 165] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Accepted: 03/13/2012] [Indexed: 12/20/2022] Open
Abstract
Dinoflagellates are unicellular algae that are ubiquitously abundant in aquatic environments. Species of the genus Symbiodinium form symbiotic relationships with reef-building corals and other marine invertebrates. Despite their ecologic importance, little is known about the genetics of dinoflagellates in general and Symbiodinium in particular. Here, we used 454 sequencing to generate transcriptome data from two Symbiodinium species from different clades (clade A and clade B). With more than 56,000 assembled sequences per species, these data represent the largest transcriptomic resource for dinoflagellates to date. Our results corroborate previous observations that dinoflagellates possess the complete nucleosome machinery. We found a complete set of core histones as well as several H3 variants and H2A.Z in one species. Furthermore, transcriptome analysis points toward a low number of transcription factors in Symbiodinium spp. that also differ in the distribution of DNA-binding domains relative to other eukaryotes. In particular the cold shock domain was predominant among transcription factors. Additionally, we found a high number of antioxidative genes in comparison to non-symbiotic but evolutionary related organisms. These findings might be of relevance in the context of the role that Symbiodinium spp. play as coral symbionts. Our data represent the most comprehensive dinoflagellate EST data set to date. This study provides a comprehensive resource to further analyze the genetic makeup, metabolic capacities, and gene repertoire of Symbiodinium and dinoflagellates. Overall, our findings indicate that Symbiodinium possesses some unique characteristics, in particular the transcriptional regulation in Symbiodinium may differ from the currently known mechanisms of eukaryotic gene regulation.
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Murray SA, Wiese M, Stüken A, Brett S, Kellmann R, Hallegraeff G, Neilan BA. sxtA-based quantitative molecular assay to identify saxitoxin-producing harmful algal blooms in marine waters. Appl Environ Microbiol 2011; 77:7050-7. [PMID: 21841034 PMCID: PMC3187097 DOI: 10.1128/aem.05308-11] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 07/29/2011] [Indexed: 11/20/2022] Open
Abstract
The recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal blooms in situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the gene sxtA that encodes a unique enzyme putatively involved in the sxt pathway in marine dinoflagellates, sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producing Alexandrium and Gymnodinium catenatum and was not detected in the non-STX-producing Alexandrium species, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However, sxtA4 was also detected in the non-STX-producing strain of Alexandrium tamarense, Tasmanian ribotype. We investigated the copy number of sxtA4 in three strains of Alexandrium catenella and found it to be relatively constant among strains. Using our novel method, we detected and quantified sxtA4 in three environmental blooms of Alexandrium catenella that led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring.
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Affiliation(s)
- Shauna A Murray
- Sydney Institute of Marine Sciences, Chowder Bay Road, Mosman, NSW 2088, Australia.
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Lin S. Genomic understanding of dinoflagellates. Res Microbiol 2011; 162:551-69. [PMID: 21514379 DOI: 10.1016/j.resmic.2011.04.006] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 03/02/2011] [Indexed: 10/18/2022]
Abstract
The phylum of dinoflagellates is characterized by many unusual and interesting genomic and physiological features, the imprint of which, in its immense genome, remains elusive. Much novel understanding has been achieved in the last decade on various aspects of dinoflagellate biology, but most remarkably about the structure, expression pattern and epigenetic modification of protein-coding genes in the nuclear and organellar genomes. Major findings include: 1) the great diversity of dinoflagellates, especially at the base of the dinoflagellate tree of life; 2) mini-circularization of the genomes of typical dinoflagellate plastids (with three membranes, chlorophylls a, c1 and c2, and carotenoid peridinin), the scrambled mitochondrial genome and the extensive mRNA editing occurring in both systems; 3) ubiquitous spliced leader trans-splicing of nuclear-encoded mRNA and demonstrated potential as a novel tool for studying dinoflagellate transcriptomes in mixed cultures and natural assemblages; 4) existence and expression of histones and other nucleosomal proteins; 5) a ribosomal protein set expected of typical eukaryotes; 6) genetic potential of non-photosynthetic solar energy utilization via proton-pump rhodopsin; 7) gene candidates in the toxin synthesis pathways; and 8) evidence of a highly redundant, high gene number and highly recombined genome. Despite this progress, much more work awaits genome-wide transcriptome and whole genome sequencing in order to unfold the molecular mechanisms underlying the numerous mysterious attributes of dinoflagellates.
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Affiliation(s)
- Senjie Lin
- Department of Marine Sciences, University of Connecticut, Groton, CT 06340, USA.
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Litosh VA, Wu W, Stupi BP, Wang J, Morris SE, Hersh MN, Metzker ML. Improved nucleotide selectivity and termination of 3'-OH unblocked reversible terminators by molecular tuning of 2-nitrobenzyl alkylated HOMedU triphosphates. Nucleic Acids Res 2011; 39:e39. [PMID: 21227920 PMCID: PMC3064798 DOI: 10.1093/nar/gkq1293] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We describe a novel 3′-OH unblocked reversible terminator with the potential to improve accuracy and read-lengths in next-generation sequencing (NGS) technologies. This terminator is based on 5-hydroxymethyl-2′-deoxyuridine triphosphate (HOMedUTP), a hypermodified nucleotide found naturally in the genomes of numerous bacteriophages and lower eukaryotes. A series of 5-(2-nitrobenzyloxy)methyl-dUTP analogs (dU.I–dU.V) were synthesized based on our previous work with photochemically cleavable terminators. These 2-nitrobenzyl alkylated HOMedUTP analogs were characterized with respect to incorporation, single-base termination, nucleotide selectivity and photochemical cleavage properties. Substitution at the α-methylene carbon of 2-nitrobenzyl with alkyl groups of increasing size was discovered as a key structural feature that provided for the molecular tuning of enzymatic properties such as single-base termination and improved nucleotide selectivity over that of natural nucleotides. 5-[(S)-α-tert-Butyl-2-nitrobenzyloxy]methyl-dUTP (dU.V) was identified as an efficient reversible terminator, whereby, sequencing feasibility was demonstrated in a cyclic reversible termination (CRT) experiment using a homopolymer repeat of ten complementary template bases without detectable UV damage during photochemical cleavage steps. These results validate our overall strategy of creating 3′-OH unblocked reversible terminator reagents that, upon photochemical cleavage, transform back into a natural state. Modified nucleotides based on 5-hydroxymethyl-pyrimidines and 7-deaza-7-hydroxymethyl-purines lay the foundation for development of a complete set of four reversible terminators for application in NGS technologies.
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Kim S, Bachvaroff TR, Handy SM, Delwiche CF. Dynamics of actin evolution in dinoflagellates. Mol Biol Evol 2010; 28:1469-80. [PMID: 21149641 DOI: 10.1093/molbev/msq332] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dinoflagellates have unique nuclei and intriguing genome characteristics with very high DNA content making complete genome sequencing difficult. In dinoflagellates, many genes are found in multicopy gene families, but the processes involved in the establishment and maintenance of these gene families are poorly understood. Understanding the dynamics of gene family evolution in dinoflagellates requires comparisons at different evolutionary scales. Studies of closely related species provide fine-scale information relative to species divergence, whereas comparisons of more distantly related species provides broad context. We selected the actin gene family as a highly expressed conserved gene previously studied in dinoflagellates. Of the 142 sequences determined in this study, 103 were from the two closely related species, Dinophysis acuminata and D. caudata, including full length and partial cDNA sequences as well as partial genomic amplicons. For these two Dinophysis species, at least three types of sequences could be identified. Most copies (79%) were relatively similar and in nucleotide trees, the sequences formed two bushy clades corresponding to the two species. In comparisons within species, only eight to ten nucleotide differences were found between these copies. The two remaining types formed clades containing sequences from both species. One type included the most similar sequences in between-species comparisons with as few as 12 nucleotide differences between species. The second type included the most divergent sequences in comparisons between and within species with up to 93 nucleotide differences between sequences. In all the sequences, most variation occurred in synonymous sites or the 5' UnTranslated Region (UTR), although there was still limited amino acid variation between most sequences. Several potential pseudogenes were found (approximately 10% of all sequences depending on species) with incomplete open reading frames due to frameshifts or early stop codons. Overall, variation in the actin gene family fits best with the "birth and death" model of evolution based on recent duplications, pseudogenes, and incomplete lineage sorting. Divergence between species was similar to variation within species, so that actin may be too conserved to be useful for phylogenetic estimation of closely related species.
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Affiliation(s)
- Sunju Kim
- Smithsonian Environmental Research Center, Edgewater, Maryland, USA
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Telomere maintenance in liquid crystalline chromosomes of dinoflagellates. Chromosoma 2010; 119:485-93. [DOI: 10.1007/s00412-010-0272-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 03/11/2010] [Accepted: 03/11/2010] [Indexed: 10/19/2022]
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Kellmann R, Stüken A, Orr RJS, Svendsen HM, Jakobsen KS. Biosynthesis and molecular genetics of polyketides in marine dinoflagellates. Mar Drugs 2010; 8:1011-48. [PMID: 20479965 PMCID: PMC2866473 DOI: 10.3390/md8041011] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 03/17/2010] [Accepted: 03/26/2010] [Indexed: 11/20/2022] Open
Abstract
Marine dinoflagellates are the single most important group of algae that produce toxins, which have a global impact on human activities. The toxins are chemically diverse, and include macrolides, cyclic polyethers, spirolides and purine alkaloids. Whereas there is a multitude of studies describing the pharmacology of these toxins, there is limited or no knowledge regarding the biochemistry and molecular genetics involved in their biosynthesis. Recently, however, exciting advances have been made. Expressed sequence tag sequencing studies have revealed important insights into the transcriptomes of dinoflagellates, whereas other studies have implicated polyketide synthase genes in the biosynthesis of cyclic polyether toxins, and the molecular genetic basis for the biosynthesis of paralytic shellfish toxins has been elucidated in cyanobacteria. This review summarises the recent progress that has been made regarding the unusual genomes of dinoflagellates, the biosynthesis and molecular genetics of dinoflagellate toxins. In addition, the evolution of these metabolic pathways will be discussed, and an outlook for future research and possible applications is provided.
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Affiliation(s)
- Ralf Kellmann
- University of Bergen, Department of Molecular Biology, 5020 Bergen, Norway; E-Mail:
| | - Anke Stüken
- University of Oslo, Department of Biology, Centre for Ecological and Evolutionary Synthesis (CEES), 0316 Oslo, Norway; E-Mails:
(A.S.);
(K.S.J.)
- University of Oslo, Department of Biology, Microbial Evolution Research Group (MERG), 0316 Oslo, Norway; E-Mail:
| | - Russell J. S. Orr
- University of Oslo, Department of Biology, Microbial Evolution Research Group (MERG), 0316 Oslo, Norway; E-Mail:
| | - Helene M. Svendsen
- University of Bergen, Department of Molecular Biology, 5020 Bergen, Norway; E-Mail:
| | - Kjetill S. Jakobsen
- University of Oslo, Department of Biology, Centre for Ecological and Evolutionary Synthesis (CEES), 0316 Oslo, Norway; E-Mails:
(A.S.);
(K.S.J.)
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McEWAN MICHELLE, HUMAYUN RAHEEL, SLAMOVITS CLAUDIOH, KEELING PATRICKJ. Nuclear Genome Sequence Survey of the DinoflagellateHeterocapsa triquetra. J Eukaryot Microbiol 2008; 55:530-5. [DOI: 10.1111/j.1550-7408.2008.00357.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Bachvaroff TR, Place AR. From stop to start: tandem gene arrangement, copy number and trans-splicing sites in the dinoflagellate Amphidinium carterae. PLoS One 2008; 3:e2929. [PMID: 18698341 PMCID: PMC2488372 DOI: 10.1371/journal.pone.0002929] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Accepted: 07/21/2008] [Indexed: 11/19/2022] Open
Abstract
Dinoflagellate genomes present unique challenges including large size, modified DNA bases, lack of nucleosomes, and condensed chromosomes. EST sequencing has shown that many genes are found as many slightly different variants implying that many copies are present in the genome. As a preliminary survey of the genome our goal was to obtain genomic sequences for 47 genes from the dinoflagellate Amphidinium carterae. A PCR approach was used to avoid problems with large insert libraries. One primer set was oriented inward to amplify the genomic complement of the cDNA and a second primer set would amplify outward between tandem repeats of the same gene. Each gene was also tested for a spliced leader using cDNA as template. Almost all (14/15) of the highly expressed genes (i.e. those with high representation in the cDNA pool) were shown to be in tandem arrays with short intergenic spacers, and most were trans-spliced. Only two moderately expressed genes were found in tandem arrays. A polyadenylation signal was found in genomic copies containing the sequence AAAAG/C at the exact polyadenylation site and was conserved between species. Four genes were found to have a high intron density (>5 introns) while most either lacked introns, or had only one to three. Actin was selected for deeper sequencing of both genomic and cDNA copies. Two clusters of actin copies were found, separated from each other by many non-coding features such as intron size and sequence. One intron-rich gene was selected for genomic walking using inverse PCR, and was not shown to be in a tandem repeat. The first glimpse of dinoflagellate genome indicates two general categories of genes in dinoflagellates, a highly expressed tandem repeat class and an intron rich less expressed class. This combination of features appears to be unique among eukaryotes.
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Affiliation(s)
- Tsvetan R Bachvaroff
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland, United States of America.
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STEELE ROBERTE, RAE PETERMM. Comparison of DNAs ofCrypthecodinium cohnii-like Dinoflagellates from Widespread Geographic Locations*. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1980.tb05403.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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BEAM CARLA, HIMES MARION. Sexual Isolation and Genetic Diversification Among Some Strains ofCrypthecodinium cohnii-likeDinoflagellates Evidence of Speciation. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1977.tb01007.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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DAVIES W, JAKOBSEN KS, NORDBY Ø. Characterization of DNA from the DinoflagellateWoloszynskia bostoniensis1. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1988.tb04120.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rein KS, Snyder RV. The biosynthesis of polyketide metabolites by dinoflagellates. ADVANCES IN APPLIED MICROBIOLOGY 2006; 59:93-125. [PMID: 16829257 PMCID: PMC2668218 DOI: 10.1016/s0065-2164(06)59004-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA
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Erdner DL, Anderson DM. Global transcriptional profiling of the toxic dinoflagellate Alexandrium fundyense using Massively Parallel Signature Sequencing. BMC Genomics 2006; 7:88. [PMID: 16638123 PMCID: PMC1473201 DOI: 10.1186/1471-2164-7-88] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Accepted: 04/25/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dinoflagellates are one of the most important classes of marine and freshwater algae, notable both for their functional diversity and ecological significance. They occur naturally as free-living cells, as endosymbionts of marine invertebrates and are well known for their involvement in "red tides". Dinoflagellates are also notable for their unusual genome content and structure, which suggests that the organization and regulation of dinoflagellate genes may be very different from that of most eukaryotes. To investigate the content and regulation of the dinoflagellate genome, we performed a global analysis of the transcriptome of the toxic dinoflagellate Alexandrium fundyense under nitrate- and phosphate-limited conditions using Massively Parallel Signature Sequencing (MPSS). RESULTS Data from the two MPSS libraries showed that the number of unique signatures found in A. fundyense cells is similar to that of humans and Arabidopsis thaliana, two eukaryotes that have been extensively analyzed using this method. The general distribution, abundance and expression patterns of the A. fundyense signatures were also quite similar to other eukaryotes, and at least 10% of the A. fundyense signatures were differentially expressed between the two conditions. RACE amplification and sequencing of a subset of signatures showed that multiple signatures arose from sequence variants of a single gene. Single signatures also mapped to different sequence variants of the same gene. CONCLUSION The MPSS data presented here provide a quantitative view of the transcriptome and its regulation in these unusual single-celled eukaryotes. The observed signature abundance and distribution in Alexandrium is similar to that of other eukaryotes that have been analyzed using MPSS. Results of signature mapping via RACE indicate that many signatures result from sequence variants of individual genes. These data add to the growing body of evidence for widespread gene duplication in dinoflagellates, which would contribute to the transcriptional complexity of these organisms. The MPSS data also demonstrate that a significant number of dinoflagellate mRNAs are transcriptionally regulated, indicating that dinoflagellates commonly employ transcriptional gene regulation along with the post-transcriptional regulation that has been well documented in these organisms.
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Affiliation(s)
- Deana L Erdner
- Marine Science Institute, University of Texas at Austin, Port Aransas, Texas 78373, USA
| | - Donald M Anderson
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole MA 02543, USA
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Abstract
Background studies have shown that 6-methylaminopurine (m6A) and 5-methylcytosine (m5C), detected in DNA, are products of its post-synthetic modification. At variance with bacterial genomes exhibiting both, eukaryotic genomes essentially carry only m5C in m5CpG doublets. This served to establish that, although a slight extra-S phase asymmetric methylation occurs de novo on 5'-CpC-3'/3'GpG-5', 5'-CpT-3'/3'-GpA-5', and 5'-CpA-3'/3'-GpT-5' dinucleotide pairs, a heavy methylation during S involves Okazaki fragments and thus semiconservatively newly made chains to guarantee genetic maintenance of -CH3 patterns in symmetrically dimethylated 5'-m5CpG-3'/3'-Gpm5C-5' dinucleotide pairs. On the other hand, whilst inverse correlation was observed between bulk DNA methylation, in S, and bulk RNA transcription, in G1 and G2, probes of methylated DNA helped to discover the presence of coding (exon) and uncoding (intron) sequences in the eukaryotic gene. These achievements led to the search for a language that genes regulated by methylation should have in common. Such a deciphering, initially providing restriction minimaps of hypermethylatable promoters and introns vs. hypomethylable exons, became feasible when bisulfite methodology allowed the direct sequencing of m5C. It emerged that, while in lymphocytes, where the transglutaminase gene (hTGc) is inactive, the promoter shows two fully methylated CpG-rich domains at 5 and one fully unmethylated CpG-rich domain at 3' (including the site +1 and a 5'-UTR), in HUVEC cells, where hTGc is active, in the first CpG-rich domain of its promoter four CpGs lack -CH3: a result suggesting new hypotheses on the mechanism of transcription, particularly in connection with radio-induced DNA demethylation.
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Affiliation(s)
- P Volpe
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy.
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Hackett JD, Scheetz TE, Yoon HS, Soares MB, Bonaldo MF, Casavant TL, Bhattacharya D. Insights into a dinoflagellate genome through expressed sequence tag analysis. BMC Genomics 2005; 6:80. [PMID: 15921535 PMCID: PMC1173104 DOI: 10.1186/1471-2164-6-80] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Accepted: 05/29/2005] [Indexed: 11/10/2022] Open
Abstract
Background Dinoflagellates are important marine primary producers and grazers and cause toxic "red tides". These taxa are characterized by many unique features such as immense genomes, the absence of nucleosomes, and photosynthetic organelles (plastids) that have been gained and lost multiple times. We generated EST sequences from non-normalized and normalized cDNA libraries from a culture of the toxic species Alexandrium tamarense to elucidate dinoflagellate evolution. Previous analyses of these data have clarified plastid origin and here we study the gene content, annotate the ESTs, and analyze the genes that are putatively involved in DNA packaging. Results Approximately 20% of the 6,723 unique (11,171 total 3'-reads) ESTs data could be annotated using Blast searches against GenBank. Several putative dinoflagellate-specific mRNAs were identified, including one novel plastid protein. Dinoflagellate genes, similar to other eukaryotes, have a high GC-content that is reflected in the amino acid codon usage. Highly represented transcripts include histone-like (HLP) and luciferin binding proteins and several genes occur in families that encode nearly identical proteins. We also identified rare transcripts encoding a predicted protein highly similar to histone H2A.X. We speculate this histone may be retained for its role in DNA double-strand break repair. Conclusion This is the most extensive collection to date of ESTs from a toxic dinoflagellate. These data will be instrumental to future research to understand the unique and complex cell biology of these organisms and for potentially identifying the genes involved in toxin production.
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Affiliation(s)
- Jeremiah D Hackett
- Department of Biological Sciences and Roy J. Carver Center for Comparative Genomics, University of Iowa, Iowa City, IA 52242, USA
| | - Todd E Scheetz
- Department of Ophthalmology and Center for Bioinformatics and Computational Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Hwan Su Yoon
- Department of Biological Sciences and Roy J. Carver Center for Comparative Genomics, University of Iowa, Iowa City, IA 52242, USA
| | - Marcelo B Soares
- Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
- Departments of Biochemistry, Orthopaedics, Physiology, and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Maria F Bonaldo
- Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
| | - Thomas L Casavant
- Department of Electrical and Computer Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Debashish Bhattacharya
- Department of Biological Sciences and Roy J. Carver Center for Comparative Genomics, University of Iowa, Iowa City, IA 52242, USA
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Abstract
DNA methylation in lower eukaryotes, in contrast to vertebrates, can involve modification of adenine to N6-methyladenine (m6A). While DNA-[cytosine] methylation in higher eukaryotes has been implicated in many important cellular processes, the function(s) of DNA-[adenine] methylation in lower eukaryotes remains unknown. I have chosen to study the ciliate Tetrahymena thermophila as a model system, since this organism is known to contain m6A, but not m5C, in its macronuclear DNA. A BLAST analysis revealed an open reading frame (ORF) that appears to encode for the Tetrahymena DNA-[adenine] methyltransferase (MTase), based on the presence of motifs characteristic of the enzymes in prokaryotes. Possible biological roles for DNA-[adenine] methylation in Tetrahymena are discussed. Experiments to test these hypotheses have begun with the cloning of the gene. Orthologous ORFs are also present in three species of the malarial parasite Plasmodium. They are compared to one another and to the putative Tetrahymena DNA-[adenine] MTase. The gene from the human parasite P. falciparum has been cloned.
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Affiliation(s)
- S Hattman
- Department of Biology, University of Rochester, Rochester, NY 14627-0211, USA.
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Hackett JD, Anderson DM, Erdner DL, Bhattacharya D. Dinoflagellates: a remarkable evolutionary experiment. AMERICAN JOURNAL OF BOTANY 2004; 91:1523-34. [PMID: 21652307 DOI: 10.3732/ajb.91.10.1523] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In this paper, we focus on dinoflagellate ecology, toxin production, fossil record, and a molecular phylogenetic analysis of hosts and plastids. Of ecological interest are the swimming and feeding behavior, bioluminescence, and symbioses of dinoflagellates with corals. The many varieties of dinoflagellate toxins, their biological effects, and current knowledge of their origin are discussed. Knowledge of dinoflagellate evolution is aided by a rich fossil record that can be used to document their emergence and diversification. However, recent biogeochemical studies indicate that dinoflagellates may be much older than previously believed. A remarkable feature of dinoflagellates is their unique genome structure and gene regulation. The nuclear genomes of these algae are of enormous size, lack nucleosomes, and have permanently condensed chromosomes. This chapter reviews the current knowledge of gene regulation and transcription in dinoflagellates with regard to the unique aspects of the nuclear genome. Previous work shows the plastid genome of typical dinoflagellates to have been reduced to single-gene minicircles that encode only a small number of proteins. Recent studies have demonstrated that the majority of the plastid genome has been transferred to the nucleus, which makes the dinoflagellates the only eukaryotes to encode the majority of typical plastid genes in the nucleus. The evolution of the dinoflagellate plastid and the implications of these results for understanding organellar genome evolution are discussed.
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Affiliation(s)
- Jeremiah D Hackett
- Department of Biological Sciences and Center for Comparative Genomics, University of Iowa, Iowa City, Iowa 52242 USA
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Saldarriaga JF, “Max” Taylor F, Cavalier-Smith T, Menden-Deuer S, Keeling PJ. Molecular data and the evolutionary history of dinoflagellates. Eur J Protistol 2004. [DOI: 10.1016/j.ejop.2003.11.003] [Citation(s) in RCA: 173] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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van Leeuwen F, Kieft R, Cross M, Borst P. Biosynthesis and function of the modified DNA base beta-D-glucosyl-hydroxymethyluracil in Trypanosoma brucei. Mol Cell Biol 1998; 18:5643-51. [PMID: 9742081 PMCID: PMC109150 DOI: 10.1128/mcb.18.10.5643] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
beta-D-Glucosyl-hydroxymethyluracil, also called J, is a modified DNA base conserved among kinetoplastid flagellates. In Trypanosoma brucei, the majority of J is present in repetitive DNA but the partial replacement of thymine by J also correlates with transcriptional repression of the variant surface glycoprotein (VSG) genes in the telomeric VSG gene expression sites. To gain a better understanding of the function of J, we studied its biosynthesis in T. brucei and found that it is made in two steps. In the first step, thymine in DNA is converted into hydroxymethyluracil by an enzyme that recognizes specific DNA sequences and/or structures. In the second step, hydroxymethyluracil is glucosylated by an enzyme that shows no obvious sequence specificity. We identified analogs of thymidine that affect the J content of the T. brucei genome upon incorporation into DNA. These analogs were used to study the function of J in the control of VSG gene expression sites. We found that incorporation of bromodeoxyuridine resulted in a 12-fold decrease in J content and caused a partial derepression of silent VSG gene expression site promoters, suggesting that J might strengthen transcriptional repression. Incorporation of hydroxymethyldeoxyuridine, resulting in a 15-fold increase in the J content, caused a reduction in the occurrence of chromosome breakage events sometimes associated with transcriptional switching between VSG gene expression sites in vitro. We speculate that these effects are mediated by the packaging of J-containing DNA into a condensed chromatin structure.
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Affiliation(s)
- F van Leeuwen
- Division of Molecular Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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van Leeuwen F, Taylor MC, Mondragon A, Moreau H, Gibson W, Kieft R, Borst P. beta-D-glucosyl-hydroxymethyluracil is a conserved DNA modification in kinetoplastid protozoans and is abundant in their telomeres. Proc Natl Acad Sci U S A 1998; 95:2366-71. [PMID: 9482891 PMCID: PMC19348 DOI: 10.1073/pnas.95.5.2366] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The unusual DNA base beta-D-glucosyl-hydroxymethyluracil, called "J, " replaces approximately 0.5-1% of Thy in DNA of African trypanosomes but has not been found in other organisms thus far. In Trypanosoma brucei, J is located predominantly in repetitive DNA, and its presence correlates with the silencing of telomeric genes. Using antibodies specific for J, we have developed sensitive assays to screen for J in a range of organisms and have found that J is not limited to trypanosomes that undergo antigenic variation but is conserved among Kinetoplastida. In all kinetoplastids tested, including the human pathogens Leishmania donovani and Trypanosoma cruzi, J was found to be abundantly present in the (GGGTTA)n telomere repeats. Outside Kinetoplastida, J was found only in Diplonema, a small phagotrophic marine flagellate, in which we also identified 5-MeCyt. Fractionation of Diplonema DNA showed that the two modifications are present in a common genome compartment, which suggests that they may have a similar function. Dinoflagellates appear to contain small amounts of modified bases that may be analogs of J. The evolutionary conservation of J in kinetoplastid protozoans suggests that it has a general function, repression of transcription or recombination, or a combination of both. T. brucei may have recruited J for the control of genes involved in antigenic variation.
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Affiliation(s)
- F van Leeuwen
- Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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Yoshida M, Makino K, Morita H, Terato H, Ohyama Y, Ide H. Substrate and mispairing properties of 5-formyl-2'-deoxyuridine 5'-triphosphate assessed by in vitro DNA polymerase reactions. Nucleic Acids Res 1997; 25:1570-7. [PMID: 9092664 PMCID: PMC146632 DOI: 10.1093/nar/25.8.1570] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
5-Formyluracil (fU) is one of the thymine lesions produced by reactive oxygen radicals in DNA and its constituents. In this work, 5-formyl-2'-deoxyuridine 5'-triphosphate (fdUTP) was chemically synthesized and extensively purified by HPLC. The electron withdrawing 5-formyl group facilitated ionization of fU. Thus, p K a of the base unit of fdUTP was 8.6, significantly lower than that of parent thymine (p K a = 10.0 as dTMP). fdUTP efficiently replaced dTTP during DNA replication catalyzed by Escherichia coli DNA polymerase I (Klenow fragment), T7 DNA polymerase (3'-5'exonuclease free) and Taq DNA polymerase. fU-specific cleavage of the replication products by piperidine revealed that when incorporated as T, incorporation of fU was virtually uniform, suggesting minor sequence context effects on the incorporation frequency of fdUTP. fdUTP also replaced dCTP, but with much lower efficiency than that for dTTP. The substitution efficiency for dCTP increased with increasing pH from 7.2 to 9.0. The parallel correlation between ionization of the base unit of fdUTP (p K a = 8.6) and the substitution efficiency for dCTP strongly suggests that the base-ionized form of fdUTP is involved in mispairing with template G. These data indicate that fU can be specifically introduced into DNA as unique lesions by in vitro DNA polymerase reactions. In addition, fU is potentially mutagenic since this lesion is much more prone to form mispairing with G than parent thymine.
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Affiliation(s)
- M Yoshida
- Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606, Japan
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Cajigas A, Gayer M, Beam C, Steinberg JJ. Ozonation of DNA forms adducts: a 32P-DNA labeling and thin-layer chromatography technique to measure DNA environmental biomarkers. ARCHIVES OF ENVIRONMENTAL HEALTH 1994; 49:25-36. [PMID: 8117143 DOI: 10.1080/00039896.1994.9934411] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Little direct documented evidence of ozone's genotoxicity exists. Deoxyribonucleic acid (DNA) adducts are produced by environmental toxic agents, including ozone. We have described a modified thin-layer chromatography (TLC) technique that can assess adduct formation as a biomarker of ozone injury. This requires 32P-labeling DNA, digestion of deoxynucleotides (dNMPs), and separation in two-dimensional PEI-cellulose TLC. We have applied this technique to control DNAs, to control DNA in solution exposed to acute ambient ozone, and to control DNA exposed to acute bubbled-through ozone (2 ppm for 24 h). We detected stable DNA adducts, including hydroxymethyluracil (HMU), thymine glycol (TG), 8-hydroxyguanine (8-OHG), and demonstrated, as yet, unidentified adducts that may serve as a "fingerprint" pattern of DNA adduction. This technique quantifies low-molecular-mass DNA adducts, both in vivo and in vitro, with potential applications to environmental toxicology.
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Affiliation(s)
- A Cajigas
- Department of Pathology, Albert Einstein College of Medicine, New York, New York
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Gommers-Ampt JH, Teixeira AJ, van de Werken G, van Dijk WJ, Borst P. The identification of hydroxymethyluracil in DNA of Trypanosoma brucei. Nucleic Acids Res 1993; 21:2039-43. [PMID: 8502544 PMCID: PMC309462 DOI: 10.1093/nar/21.9.2039] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have previously reported the detection of two unusual nucleotides, pdJ and pdV, in the DNA of Trypanosoma brucei (Gommers-Ampt et al., 1991). pdJ was found to be a novel nucleotide and is possibly involved in the regulation of variant specific surface antigen gene expression in trypanosomes. Recent evidence suggests that V could be a precursor of J, making V a key compound in the study of the biosynthesis and function of J. We have therefore determined the structure of V and here we present proof that V is HOMeU. The identity is based on a detailed comparison of dV(p) with authentic HOMedU(p), showing: I) co-migration in three different liquid chromatography analyses II) identical UV absorbance characteristics III) identical behavior in acetyl-pentafluorobenzyl derivatization and subsequent Gas chromatography/Mass spectrometry (GC/MS). The GC/MS technique has not been used before to analyse HOMedU purified from biological material. Because of its high sensitivity, it may also be useful for the detection of the low amounts of HOMedU resulting from oxidative damage of DNA.
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Affiliation(s)
- J H Gommers-Ampt
- Division of Molecular Biology, The Netherlands Cancer Institute, Amsterdam
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