1
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Oliveira JIN, Cabral-de-Mello DC, Valente GT, Martins C. Transcribing the enigma: the B chromosome as a territory of uncharted RNAs. Genetics 2024; 227:iyae026. [PMID: 38513121 DOI: 10.1093/genetics/iyae026] [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: 12/11/2023] [Accepted: 02/10/2024] [Indexed: 03/23/2024] Open
Abstract
B chromosomes are supernumerary elements found in several groups of eukaryotes, including fungi, plants, and animals. Typically, these chromosomes either originate from their hosts through errors in meiosis or interspecifically through horizontal transfer. While many B chromosomes are primarily heterochromatic and possess a low number of coding genes, these additional elements are still capable of transcribing sequences and exerting influence on the expression of host genes. How B chromosomes escape elimination and which impacts can be promoted in the cell always intrigued the cytogeneticists. In pursuit of understanding the behavior and functional impacts of these extra elements, cytogenetic studies meet the advances of molecular biology, incorporating various techniques into investigating B chromosomes from a functional perspective. In this review, we present a timeline of studies investigating B chromosomes and RNAs, highlighting the advances and key findings throughout their history. Additionally, we identified which RNA classes are reported in the B chromosomes and emphasized the necessity for further investigation into new perspectives on the B chromosome functions. In this context, we present a phylogenetic tree that illustrates which branches either report B chromosome presence or have functional RNA studies related to B chromosomes. We propose investigating other unexplored RNA classes and conducting functional analysis in conjunction with cytogenetic studies to enhance our understanding of the B chromosome from an RNA perspective.
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Affiliation(s)
| | - Diogo C Cabral-de-Mello
- Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro 13506-900, Brazil
| | - Guilherme T Valente
- Applied Biotechnology Laboratory, Clinical Hospital of Botucatu Medical School, Botucatu 18618-687, Brazil
| | - Cesar Martins
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, São Paulo State University (UNESP), Botucatu 18618-689, Brazil
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2
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Rajpal VR, Sharma S, Sehgal D, Sharma P, Wadhwa N, Dhakate P, Chandra A, Thakur RK, Deb S, Rama Rao S, Mir BA, Raina SN. Comprehending the dynamism of B chromosomes in their journey towards becoming unselfish. Front Cell Dev Biol 2023; 10:1072716. [PMID: 36684438 PMCID: PMC9846793 DOI: 10.3389/fcell.2022.1072716] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Investigated for more than a century now, B chromosomes (Bs) research has come a long way from Bs being considered parasitic or neutral to becoming unselfish and bringing benefits to their hosts. B chromosomes exist as accessory chromosomes along with the standard A chromosomes (As) across eukaryotic taxa. Represented singly or in multiple copies, B chromosomes are largely heterochromatic but also contain euchromatic and organellar segments. Although B chromosomes are derived entities, they follow their species-specific evolutionary pattern. B chromosomes fail to pair with the standard chromosomes during meiosis and vary in their number, size, composition and structure across taxa and ensure their successful transmission through non-mendelian mechanisms like mitotic, pre-meiotic, meiotic or post-meiotic drives, unique non-disjunction, self-pairing or even imparting benefits to the host when they lack drive. B chromosomes have been associated with cellular processes like sex determination, pathogenicity, resistance to pathogens, phenotypic effects, and differential gene expression. With the advancements in B-omics research, novel insights have been gleaned on their functions, some of which have been associated with the regulation of gene expression of A chromosomes through increased expression of miRNAs or differential expression of transposable elements located on them. The next-generation sequencing and emerging technologies will further likely unravel the cellular, molecular and functional behaviour of these enigmatic entities. Amidst the extensive fluidity shown by B chromosomes in their structural and functional attributes, we perceive that the existence and survival of B chromosomes in the populations most likely seem to be a trade-off between the drive efficiency and adaptive significance versus their adverse effects on reproduction.
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Affiliation(s)
- Vijay Rani Rajpal
- Department of Botany, Hansraj College, University of Delhi, Delhi, India,*Correspondence: Vijay Rani Rajpal, , ; Soom Nath Raina,
| | - Suman Sharma
- Department of Botany, Ramjas College, University of Delhi, Delhi, India
| | - Deepmala Sehgal
- Syngenta, International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico
| | - Prashansa Sharma
- Department of Botany, Hansraj College, University of Delhi, Delhi, India
| | - Nikita Wadhwa
- University School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India
| | | | - Atika Chandra
- Department of Botany, Maitreyi College, University of Delhi, New Delhi, India
| | - Rakesh Kr. Thakur
- Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India
| | - Sohini Deb
- Department of Biotechnology and Bioinformatics, North Eastern Hill University, Shillong, Meghalaya, India
| | - Satyawada Rama Rao
- Department of Biotechnology and Bioinformatics, North Eastern Hill University, Shillong, Meghalaya, India
| | - Bilal Ahmad Mir
- Department of Botany, University of Kashmir, Srinagar, India
| | - Soom Nath Raina
- Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India,*Correspondence: Vijay Rani Rajpal, , ; Soom Nath Raina,
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3
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Goes CAG, Silva DMZDA, Utsunomia R, Nascimento NFD, Yasui GS, Senhorini JA, Hashimoto DT, Artoni RF, Foresti F, Porto-Foresti F. Sex-Dependent Inheritance of B Chromosomes in Psalidodon paranae (Teleostei, Characiformes) Revealed by Directed Crossings. Zebrafish 2021; 18:363-368. [PMID: 34935496 DOI: 10.1089/zeb.2021.0053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
B chromosomes are additional dispensable elements to the standard chromosomal set of an organism. In most cases, their transmission differs from Mendelian patterns, leading to their accumulation or extinction. The present study aimed to describe, for the first time, the transmission pattern of B chromosome in a population of Psalidodon paranae through directed crosses, as well as to analyze the populational dynamics of B chromosome. Our results revealed the possible elimination of B chromosome in crossings where only females were B-carriers, with a mean transmission rate (kB) of 0.149; however, kB was significantly higher in crossings involving male B-carriers (kB = 0.328-0.450). Moreover, we observed an increase in the frequency of B chromosomes in the natural population of P. paranae in the last two decades. These apparently contradictory results can make sense if the B chromosome provides adaptive advantages to their carriers. Here, we observed a differential transmission of B chromosomes in each sex of parental individuals, with higher transmission rates in crossing involving males B-carriers, in addition to describe the temporal changes of B chromosome frequency in P. paranae.
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Affiliation(s)
- Caio Augusto Gomes Goes
- Departamento de Ciências Biológicas, Faculdade de Ciências, Universidade Estadual Paulista (UNESP) "Júlio de Mesquita Filho," Bauru, Brazil
| | | | - Ricardo Utsunomia
- Departamento de Genética, Instituto de Ciências Biológicas e da Saúde, ICBS, Universidade Federal Rural do Rio de Janeiro, Seropédica, Brazil
| | | | - George Shigueki Yasui
- Centro nacional de Pesquisa e Conservação da Biota Aquática Continental (CEPTA-ICMBIO), Pirassununga, Brazil
| | - José Augusto Senhorini
- Centro nacional de Pesquisa e Conservação da Biota Aquática Continental (CEPTA-ICMBIO), Pirassununga, Brazil
| | - Diogo Teruo Hashimoto
- Centro de Aquicultura da UNESP, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Jaboticabal, Brazil
| | - Roberto Ferreira Artoni
- Departamento de Biologia Estrutural, Molecular e Genética, Setor de Ciências Biológicas e da Saúde, Universidade Estadual de Ponta Grossa, Ponta Grossa, Brazil
| | - Fausto Foresti
- Departamento de Biologia Estrutural e Funcional, Instituto de Biociências, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu, Brazil
| | - Fábio Porto-Foresti
- Departamento de Ciências Biológicas, Faculdade de Ciências, Universidade Estadual Paulista (UNESP) "Júlio de Mesquita Filho," Bauru, Brazil
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4
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Serrano-Freitas ÉA, Silva DMZA, Ruiz-Ruano FJ, Utsunomia R, Araya-Jaime C, Oliveira C, Camacho JPM, Foresti F. Satellite DNA content of B chromosomes in the characid fish Characidium gomesi supports their origin from sex chromosomes. Mol Genet Genomics 2019; 295:195-207. [PMID: 31624915 DOI: 10.1007/s00438-019-01615-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 10/01/2019] [Indexed: 12/28/2022]
Abstract
The origin of supernumerary (B) chromosomes is clearly conditioned by their ancestry from the standard (A) chromosomes. Sequence similarity between A and B chromosomes is thus crucial to determine B chromosome origin. For this purpose, we compare here the DNA sequences from A and B chromosomes in the characid fish Characidium gomesi using two main approaches. First, we found 59 satellite DNA (satDNA) families constituting the satellitome of this species and performed FISH analysis for 18 of them. This showed the presence of six satDNAs on the B chromosome: one shared with sex chromosomes and autosomes, two shared with sex chromosomes, one shared with autosomes and two being B-specific. This indicated that B chromosomes most likely arose from the sex chromosomes. Our second approach consisted of the analysis of five repetitive DNA families: 18S and 5S ribosomal DNA (rDNA), the H3 histone gene, U2 snDNA and the most abundant satDNA (CgoSat01-184) on DNA obtained from microdissected B chromosomes and from B-lacking genomes. PCR and sequence analysis of these repetitive sequences was successful for three of them (5S rDNA, H3 histone gene and CgoSat01-184), and sequence comparison revealed that DNA sequences obtained from the B chromosomes displayed higher identity with C. gomesi genomic DNA than with those obtained from other Characidium species. Taken together, our results support the intraspecific origin of B chromosomes in C. gomesi and point to sex chromosomes as B chromosome ancestors, which raises interesting prospects for future joint research on the genetic content of sex and B chromosomes in this species.
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Affiliation(s)
- Érica A Serrano-Freitas
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, UNESP, Distrito de Rubião Junior, Botucatu, SP, 18618-970, Brazil.,Centro de Ciências Biológicas e da Saúde, Fundação Educacional de Penápolis, Funepe, Penápolis, SP, 16303-180, Brazil
| | - Duílio M Z A Silva
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, UNESP, Distrito de Rubião Junior, Botucatu, SP, 18618-970, Brazil.
| | - Francisco J Ruiz-Ruano
- Departamento de Genética, Universidad de Granada, 18071, Granada, Spain.,Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, 75236, Uppsala, Sweden
| | - Ricardo Utsunomia
- Departamento de Genética, Instituto de Ciências Biológicas e da Saúde, ICBS, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, 23897-000, Brazil
| | - Cristian Araya-Jaime
- Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena, 1720256, La Serena, Chile.,Laboratorio de Genética y Citogenética Vegetal, Departamento de Biología, Universidad de La Serena, 1720256, La Serena, Chile
| | - Claudio Oliveira
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, UNESP, Distrito de Rubião Junior, Botucatu, SP, 18618-970, Brazil
| | | | - Fausto Foresti
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, UNESP, Distrito de Rubião Junior, Botucatu, SP, 18618-970, Brazil
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5
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Park D, Kim JH, Kim NS. De novo transcriptome sequencing and gene expression profiling with/without B-chromosome plants of Lilium amabile. Genomics Inform 2019; 17:e27. [PMID: 31610623 PMCID: PMC6808634 DOI: 10.5808/gi.2019.17.3.e27] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 03/23/2019] [Indexed: 11/20/2022] Open
Abstract
Supernumerary B chromosomes were found in Lilium amabile (2n = 2x = 24), an endemic Korean lily that grows in the wild throughout the Korean Peninsula. The extra B chromosomes do not affect the host-plant morphology; therefore, whole transcriptome analysis was performed in 0B and 1B plants to identify differentially expressed genes. A total of 154,810 transcripts were obtained from over 10 Gbp data by de novo assembly. By mapping the raw reads to the de novo transcripts, we identified 7,852 differentially expressed genes (log2FC > |10|), in which 4,059 and 3,794 were up-and down-regulated, respectively, in 1B plants compared to 0B plants. Functional enrichment analysis revealed that various differentially expressed genes were involved in cellular processes including the cell cycle, chromosome breakage and repair, and microtubule formation; all of which may be related to the occurrence and maintenance of B chromosomes. Our data provide insight into transcriptomic changes and evolution of plant B chromosomes and deliver an informative database for future study of B chromosome transcriptomes in the Korean lily.
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Affiliation(s)
- Doori Park
- Department of Molecular Biosciences, Kangwon National University, Chuncheon 24341, Korea
| | - Jong-Hwa Kim
- Department of Horticulture, Kangwon National University, Chuncheon 24341, Korea.,Oriental Bio-herb Research Institute, Kangwon National University, Chuncheon 24341, Korea
| | - Nam-Soo Kim
- Department of Molecular Biosciences, Kangwon National University, Chuncheon 24341, Korea.,Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon 24341, Korea
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6
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Jehangir M, Ahmad SF, Cardoso AL, Ramos E, Valente GT, Martins C. De novo genome assembly of the cichlid fish Astatotilapia latifasciata reveals a higher level of genomic polymorphism and genes related to B chromosomes. Chromosoma 2019; 128:81-96. [PMID: 31115663 DOI: 10.1007/s00412-019-00707-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/27/2019] [Accepted: 05/07/2019] [Indexed: 12/15/2022]
Abstract
Supernumerary B chromosomes (Bs) are accessory elements to the regular chromosome set (As) and have been observed in a huge diversity of eukaryotic species. Although extensively investigated, the biological significance of Bs remains enigmatic. Here, we present de novo genome assemblies for the cichlid fish Astatotilapia latifasciata, a well-known model to study Bs. High coverage data with Illumina sequencing was obtained for males and females with 0B (B-), 1B, and 2B (B+) chromosomes to provide information regarding the diversity among these genomes. The draft assemblies comprised 771 Mb for the B- genome and 781 Mb for the B+ genome. Comparative analysis of the B+ and B- assemblies reveals syntenic discontinuity, duplicated blocks and several insertions, deletions, and inversions indicative of rearrangements in the B+ genome. Hundreds of transposable elements and 1546 protein coding sequences were annotated in the duplicated B+ regions. Our work contributes a list of thousands of genes harbored on the B chromosome, with functions in several biological processes, including the cell cycle.
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Affiliation(s)
- Maryam Jehangir
- Department of Morphology, Institute of Bioscience at Botucatu, São Paulo State University - UNESP, Botucatu, SP, 18618-689, Brazil
| | - Syed F Ahmad
- Department of Morphology, Institute of Bioscience at Botucatu, São Paulo State University - UNESP, Botucatu, SP, 18618-689, Brazil
| | - Adauto L Cardoso
- Department of Morphology, Institute of Bioscience at Botucatu, São Paulo State University - UNESP, Botucatu, SP, 18618-689, Brazil
| | - Erica Ramos
- Department of Morphology, Institute of Bioscience at Botucatu, São Paulo State University - UNESP, Botucatu, SP, 18618-689, Brazil
| | - Guilherme T Valente
- Bioprocess and Biotechnology Department, Agronomical Science Faculty, Sao Paulo State University - UNESP, Botucatu, SP, Brazil
| | - Cesar Martins
- Department of Morphology, Institute of Bioscience at Botucatu, São Paulo State University - UNESP, Botucatu, SP, 18618-689, Brazil.
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7
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Dhar MK, Kour J, Kaul S. Origin, Behaviour, and Transmission of B Chromosome with Special Reference to Plantago lagopus. Genes (Basel) 2019; 10:E152. [PMID: 30781667 PMCID: PMC6410184 DOI: 10.3390/genes10020152] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 11/30/2022] Open
Abstract
B chromosomes have been reported in many eukaryotic organisms. These chromosomes occur in addition to the standard complement of a species. Bs do not pair with any of the A chromosomes and they have generally been considered to be non-essential and genetically inert. However, due to tremendous advancements in the technologies, the molecular composition of B chromosomes has been determined. The sequencing data has revealed that B chromosomes have originated from A chromosomes and they are rich in repetitive elements. In our laboratory, a novel B chromosome was discovered in Plantago lagopus. Using molecular cytogenetic techniques, the B chromosome was found to be composed of ribosomal DNA sequences. However, further characterization of the chromosome using next generation sequencing (NGS) etc. revealed that the B chromosome is a mosaic of sequences derived from A chromosomes, 5S ribosomal DNA (rDNA), 45S rDNA, and various types of repetitive elements. The transmission of B chromosome through the female sex track did not follow the Mendelian principles. The chromosome was found to have drive due to which it was perpetuating in populations. The present paper attempts to summarize the information on nature, transmission, and origin of B chromosomes, particularly the current status of our knowledge in P. lagopus.
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Affiliation(s)
- Manoj K Dhar
- Genome Research Laboratory, School of Biotechnology, University of Jammu, Jammu-180006, India.
| | - Jasmeet Kour
- Genome Research Laboratory, School of Biotechnology, University of Jammu, Jammu-180006, India.
| | - Sanjana Kaul
- Genome Research Laboratory, School of Biotechnology, University of Jammu, Jammu-180006, India.
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8
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Ahmad SF, Martins C. The Modern View of B Chromosomes Under the Impact of High Scale Omics Analyses. Cells 2019; 8:E156. [PMID: 30781835 PMCID: PMC6406668 DOI: 10.3390/cells8020156] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 02/10/2019] [Accepted: 02/12/2019] [Indexed: 12/11/2022] Open
Abstract
Supernumerary B chromosomes (Bs) are extra karyotype units in addition to A chromosomes, and are found in some fungi and thousands of animals and plant species. Bs are uniquely characterized due to their non-Mendelian inheritance, and represent one of the best examples of genomic conflict. Over the last decades, their genetic composition, function and evolution have remained an unresolved query, although a few successful attempts have been made to address these phenomena. A classical concept based on cytogenetics and genetics is that Bs are selfish and abundant with DNA repeats and transposons, and in most cases, they do not carry any function. However, recently, the modern quantum development of high scale multi-omics techniques has shifted B research towards a new-born field that we call "B-omics". We review the recent literature and add novel perspectives to the B research, discussing the role of new technologies to understand the mechanistic perspectives of the molecular evolution and function of Bs. The modern view states that B chromosomes are enriched with genes for many significant biological functions, including but not limited to the interesting set of genes related to cell cycle and chromosome structure. Furthermore, the presence of B chromosomes could favor genomic rearrangements and influence the nuclear environment affecting the function of other chromatin regions. We hypothesize that B chromosomes might play a key function in driving their transmission and maintenance inside the cell, as well as offer an extra genomic compartment for evolution.
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Affiliation(s)
- Syed Farhan Ahmad
- Department of Morphology, Institute of Biosciences at Botucatu, Sao Paulo State University (UNESP), CEP 18618689, Botucatu, SP, Brazil.
| | - Cesar Martins
- Department of Morphology, Institute of Biosciences at Botucatu, Sao Paulo State University (UNESP), CEP 18618689, Botucatu, SP, Brazil.
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9
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Gene expression changes elicited by a parasitic B chromosome in the grasshopper Eyprepocnemis plorans are consistent with its phenotypic effects. Chromosoma 2019; 128:53-67. [PMID: 30617552 DOI: 10.1007/s00412-018-00689-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 01/16/2023]
Abstract
Parasitism evokes adaptive physiological changes in the host, many of which take place through gene expression changes. This response can be more or less local, depending on the organ or tissue affected by the parasite, or else systemic when the parasite affects the entire host body. The most extreme of the latter cases is intragenomic parasitism, where the parasite is present in all host nuclei as any other genomic element. Here, we show the molecular crosstalk between a parasitic chromosome (also named B chromosome) and the host genome, manifested through gene expression changes. The transcriptome analysis of 0B and 1B females of the grasshopper Eyprepocnemis plorans, validated by a microarray experiment performed on four B-lacking and five B-carrying females, revealed changes in gene expression for 188 unigenes being consistent in both experiments. Once discarded B-derived transcripts, there were 46 differentially expressed genes (30 up- and 16 downregulated) related with the adaptation of the host genome to the presence of the parasitic chromosome. Interestingly, the functions of these genes could explain some of the most important effects of B chromosomes, such as nucleotypic effects derived from the additional DNA they represent, chemical defense and detoxification, protein modification and response to stress, ovary function, and regulation of gene expression. Collectively, these changes uncover an intimate host-parasite interaction between A and B chromosomes during crucial steps of gene expression and protein function.
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10
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Clark FE, Conte MA, Kocher TD. Genomic Characterization of a B Chromosome in Lake Malawi Cichlid Fishes. Genes (Basel) 2018; 9:E610. [PMID: 30563180 PMCID: PMC6316868 DOI: 10.3390/genes9120610] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 11/28/2018] [Accepted: 11/30/2018] [Indexed: 12/19/2022] Open
Abstract
B chromosomes (Bs) were discovered a century ago, and since then, most studies have focused on describing their distribution and abundance using traditional cytogenetics. Only recently have attempts been made to understand their structure and evolution at the level of DNA sequence. Many questions regarding the origin, structure, function, and evolution of B chromosomes remain unanswered. Here, we identify B chromosome sequences from several species of cichlid fish from Lake Malawi by examining the ratios of DNA sequence coverage in individuals with or without B chromosomes. We examined the efficiency of this method, and compared results using both Illumina and PacBio sequence data. The B chromosome sequences detected in 13 individuals from 7 species were compared to assess the rates of sequence replacement. B-specific sequence common to at least 12 of the 13 datasets were identified as the "Core" B chromosome. The location of B sequence homologs throughout the genome provides further support for theories of B chromosome evolution. Finally, we identified genes and gene fragments located on the B chromosome, some of which may regulate the segregation and maintenance of the B chromosome.
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Affiliation(s)
- Frances E Clark
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
| | - Matthew A Conte
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
| | - Thomas D Kocher
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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11
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Jetybayev IY, Bugrov AG, Dzuybenko VV, Rubtsov NB. B Chromosomes in Grasshoppers: Different Origins and Pathways to the Modern B s. Genes (Basel) 2018; 9:genes9100509. [PMID: 30340429 PMCID: PMC6209997 DOI: 10.3390/genes9100509] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/30/2018] [Accepted: 10/17/2018] [Indexed: 01/05/2023] Open
Abstract
B chromosomes (Bs) were described in most taxa of eukaryotes and in around 11.9% of studied Orthopteran species. In some grasshopper species, their evolution has led to many B chromosome morphotypes. We studied the Bs in nine species (Nocaracris tardus, Nocaracris cyanipes, Aeropus sibiricus, Chorthippus jacobsoni, Chorthippus apricarius, Bryodema gebleri, Asiotmethis heptapotamicus songoricus, Podisma sapporensis, and Eyprepocnemis plorans), analyzing their possible origin and further development. The studied Bs consisted of C-positive or C-positive and C-negative regions. Analyzing new data and considering current hypotheses, we suggest that Bs in grasshoppers could arise through different mechanisms and from different chromosomes of the main set. We gave our special attention to the Bs with C-negative regions and suggest a new hypothesis of B chromosome formation from large or medium autosomes. This hypothesis includes dissemination of repetitive sequences and development of intercalary heterochromatic blocks in euchromatic chromosome arm followed by deletion of euchromatic regions located between them. The hypothesis is based on the findings of the Eyprepocnemis plorans specimens with autosome containing numerous intercalary repeat clusters, analysis of C-positive Bs in Eyprepocnemis plorans and Podisma sapporensis containing intercalary and terminal C-negative regions, and development of heterochromatic neo-Y chromosome in some Pamphagidae grasshoppers.
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Affiliation(s)
- Ilyas Yerkinovich Jetybayev
- The Federal Research Center Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Lavrentjev Ave., 10, 630090 Novosibirsk, Russia.
- Institute of Systematics and Ecology of Animals, Russian Academy of Sciences, Siberian Branch, Frunze str. 11, 630091 Novosibirsk, Russia.
| | - Alexander Gennadievich Bugrov
- Institute of Systematics and Ecology of Animals, Russian Academy of Sciences, Siberian Branch, Frunze str. 11, 630091 Novosibirsk, Russia.
- Novosibirsk State University, Pirogov str., 2, 630090 Novosibirsk, Russia.
| | | | - Nikolay Borisovich Rubtsov
- The Federal Research Center Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Lavrentjev Ave., 10, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogov str., 2, 630090 Novosibirsk, Russia.
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12
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Transcription of a B chromosome CAP-G pseudogene does not influence normal Condensin Complex genes in a grasshopper. Sci Rep 2017; 7:17650. [PMID: 29247237 PMCID: PMC5732253 DOI: 10.1038/s41598-017-15894-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/02/2017] [Indexed: 11/08/2022] Open
Abstract
Parasitic B chromosomes invade and persist in natural populations through several mechanisms for transmission advantage (drive). They may contain gene-derived sequences which, in some cases, are actively transcribed. A further interesting question is whether B-derived transcripts become functional products. In the grasshopper Eyprepocnemis plorans, one of the gene-derived sequences located on the B chromosome shows homology with the gene coding for the CAP-G subunit of condensin I. We show here, by means of fluorescent in situ hybridization coupled with tyramide signal amplification (FISH-TSA), that this gene is located in the distal region of the B24 chromosome variant. The DNA sequence located in the B chromosome is a pseudogenic version of the CAP-G gene (B-CAP-G). In two Spanish populations, we found active transcription of B-CAP-G, but it did not influence the expression of CAP-D2 and CAP-D3 genes coding for corresponding condensin I and II subunits, respectively. Our results indicate that the transcriptional regulation of the B-CAP-G pseudogene is uncoupled from the standard regulation of the genes that constitute the condensin complex, and suggest that some of the B chromosome known effects may be related with its gene content and transcriptional activity, thus opening new exciting avenues for research.
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Navarro-Domínguez B, Ruiz-Ruano FJ, Cabrero J, Corral JM, López-León MD, Sharbel TF, Camacho JPM. Protein-coding genes in B chromosomes of the grasshopper Eyprepocnemis plorans. Sci Rep 2017; 7:45200. [PMID: 28367986 PMCID: PMC5377258 DOI: 10.1038/srep45200] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 02/22/2017] [Indexed: 01/20/2023] Open
Abstract
For many years, parasitic B chromosomes have been considered genetically inert elements. Here we show the presence of ten protein-coding genes in the B chromosome of the grasshopper Eyprepocnemis plorans. Four of these genes (CIP2A, GTPB6, KIF20A, and MTG1) were complete in the B chromosome whereas the six remaining (CKAP2, CAP-G, HYI, MYCB2, SLIT and TOP2A) were truncated. Five of these genes (CIP2A, CKAP2, CAP-G, KIF20A, and MYCB2) were significantly up-regulated in B-carrying individuals, as expected if they were actively transcribed from the B chromosome. This conclusion is supported by three truncated genes (CKAP2, CAP-G and MYCB2) which showed up-regulation only in the regions being present in the B chromosome. Our results indicate that B chromosomes are not so silenced as was hitherto believed. Interestingly, the five active genes in the B chromosome code for functions related with cell division, which is the main arena where B chromosome destiny is played. This suggests that B chromosome evolutionary success can lie on its gene content.
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Affiliation(s)
| | - Francisco J. Ruiz-Ruano
- Departamento de Genética, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Josefa Cabrero
- Departamento de Genética, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - José María Corral
- Leibniz Institute for Plant Genetics and Crop Plant Research (IPK), D-06466 Gatersleben, Germany
- Department of Bioanalytics, Coburg University of Applied Sciences and Arts, Coburg, Germany
| | | | - Timothy F. Sharbel
- Leibniz Institute for Plant Genetics and Crop Plant Research (IPK), D-06466 Gatersleben, Germany
- Global Institute for Food Security, 110 Gymnasium Place, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 4J8, Canada
| | - Juan Pedro M. Camacho
- Departamento de Genética, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
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Ma W, Gabriel TS, Martis MM, Gursinsky T, Schubert V, Vrána J, Doležel J, Grundlach H, Altschmied L, Scholz U, Himmelbach A, Behrens SE, Banaei-Moghaddam AM, Houben A. Rye B chromosomes encode a functional Argonaute-like protein with in vitro slicer activities similar to its A chromosome paralog. THE NEW PHYTOLOGIST 2017; 213:916-928. [PMID: 27468091 DOI: 10.1111/nph.14110] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 06/18/2016] [Indexed: 05/21/2023]
Abstract
B chromosomes (Bs) are supernumerary, dispensable parts of the nuclear genome, which appear in many different species of eukaryote. So far, Bs have been considered to be genetically inert elements without any functional genes. Our comparative transcriptome analysis and the detection of active RNA polymerase II (RNAPII) in the proximity of B chromatin demonstrate that the Bs of rye (Secale cereale) contribute to the transcriptome. In total, 1954 and 1218 B-derived transcripts with an open reading frame were expressed in generative and vegetative tissues, respectively. In addition to B-derived transposable element transcripts, a high percentage of short transcripts without detectable similarity to known proteins and gene fragments from A chromosomes (As) were found, suggesting an ongoing gene erosion process. In vitro analysis of the A- and B-encoded AGO4B protein variants demonstrated that both possess RNA slicer activity. These data demonstrate unambiguously the presence of a functional AGO4B gene on Bs and that these Bs carry both functional protein coding genes and pseudogene copies. Thus, B-encoded genes may provide an additional level of gene control and complexity in combination with their related A-located genes. Hence, physiological effects, associated with the presence of Bs, may partly be explained by the activity of B-located (pseudo)genes.
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Affiliation(s)
- Wei Ma
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
| | - Tobias Sebastian Gabriel
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
| | - Mihaela Maria Martis
- Institute of Bioinformatics and Systems Biology/Munich Information Center for Protein Sequences, Helmholtz Center Munich, German Research Center for Environmental Health, 85764, Neuherberg, Germany
- National Bioinformatics Infrastructure Sweden, Department of Clinical and Experimental Medicine, Linköping University, SE-558185, Linköping, Sweden
| | - Torsten Gursinsky
- Institute of Biochemistry and Biotechnology, Section Microbial Biotechnology, Faculty of Life Sciences, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle/Saale, Germany
| | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
| | - Jan Vrána
- Institute of Experimental Botany, Center of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, 78371, Olomouc, Czech Republic
| | - Jaroslav Doležel
- Institute of Experimental Botany, Center of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, 78371, Olomouc, Czech Republic
| | - Heidrun Grundlach
- Institute of Bioinformatics and Systems Biology/Munich Information Center for Protein Sequences, Helmholtz Center Munich, German Research Center for Environmental Health, 85764, Neuherberg, Germany
| | - Lothar Altschmied
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
| | - Uwe Scholz
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
| | - Axel Himmelbach
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
| | - Sven-Erik Behrens
- Institute of Biochemistry and Biotechnology, Section Microbial Biotechnology, Faculty of Life Sciences, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle/Saale, Germany
| | - Ali Mohammad Banaei-Moghaddam
- Department of Biochemistry, Institute of Biochemistry and Biophysics (IBB), University of Tehran, PO Box 13145-1384, Tehran, Iran
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
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Valente GT, Nakajima RT, Fantinatti BEA, Marques DF, Almeida RO, Simões RP, Martins C. B chromosomes: from cytogenetics to systems biology. Chromosoma 2016; 126:73-81. [PMID: 27558128 DOI: 10.1007/s00412-016-0613-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/10/2016] [Accepted: 08/15/2016] [Indexed: 01/01/2023]
Abstract
Though hundreds to thousands of reports have described the distribution of B chromosomes among diverse eukaryote groups, a comprehensive theory of their biological role has not yet clearly emerged. B chromosomes are classically understood as a sea of repetitive DNA sequences that are poor in genes and are maintained by a parasitic-drive mechanism during cell division. Recent developments in high-throughput DNA/RNA analyses have increased the resolution of B chromosome biology beyond those of classical and molecular cytogenetic methods; B chromosomes contain many transcriptionally active sequences, including genes, and can modulate the activity of autosomal genes. Furthermore, the most recent knowledge obtained from omics analyses, which is associated with a systemic view, has demonstrated that B chromosomes can influence cell biology in a complex way, possibly favoring their own maintenance and perpetuation.
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Affiliation(s)
- Guilherme T Valente
- Department of Bioprocess and Biotechnology, Agronomic Science School, UNESP - Sao Paulo State University, Botucatu, SP, 18610-307, Brazil
| | - Rafael T Nakajima
- Department of Morphology, Institute of Biosciences, UNESP - Sao Paulo State University, Sao Paulo, Botucatu, 18618-689, Brazil
| | - Bruno E A Fantinatti
- Department of Morphology, Institute of Biosciences, UNESP - Sao Paulo State University, Sao Paulo, Botucatu, 18618-689, Brazil
| | - Diego F Marques
- Department of Morphology, Institute of Biosciences, UNESP - Sao Paulo State University, Sao Paulo, Botucatu, 18618-689, Brazil
| | - Rodrigo O Almeida
- Department of Bioprocess and Biotechnology, Agronomic Science School, UNESP - Sao Paulo State University, Botucatu, SP, 18610-307, Brazil
| | - Rafael P Simões
- Department of Bioprocess and Biotechnology, Agronomic Science School, UNESP - Sao Paulo State University, Botucatu, SP, 18610-307, Brazil
| | - Cesar Martins
- Department of Morphology, Institute of Biosciences, UNESP - Sao Paulo State University, Sao Paulo, Botucatu, 18618-689, Brazil.
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Huang W, Du Y, Zhao X, Jin W. B chromosome contains active genes and impacts the transcription of A chromosomes in maize (Zea mays L.). BMC PLANT BIOLOGY 2016; 16:88. [PMID: 27083560 PMCID: PMC4833949 DOI: 10.1186/s12870-016-0775-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/11/2016] [Indexed: 05/03/2023]
Abstract
BACKGROUND The dispensable maize (Zea mays L.) B chromosome is highly heterochromatic and widely believed to be devoid of functional genes. Although low-copy B chromosome causes no obvious phenotype variation, its existence might influence A genome gene expression. Previous studies suggested that B chromosomes are evolved from standard chromosomes; therefore, they might contain genic regions showing homology with A chromosome sequences. RESULTS Our data suggested that maize B chromosome influences the A-genome transcription with stronger effect associated with an increase in copy number of B chromosome. In total 130 differently expressed genes were detected in comparison between with and without B chromosome lines. These differentially expressed genes are mainly involved in cell metabolism and nucleotide binding. Using Starter + B, we amplified ten B chromosome loci with high sequence similarity to A-genome genes. Fluorescence in situ hybridization (FISH) confirmed that at least four ~5 kb-sized genes are located on the B chromosome. In addition, through de novo assembly of the reads not unmapped to maize B73 reference genome together with PCR validation, we found three B-located LTR; in particular, one of them, the 3.2 kb comp75688, is expressed in a B-dosage dependent manner. CONCLUSION We found that in the presence of maize B chromosome, the transcription of A genome genes was altered, with more impact by the increase of the B chromosome number. The B-located transcriptionally active genes showed high similarity to their A-genome homologues, and retrotransposons on B chromosome also have partial homologous to A genome sequences. Our data shed more lights on the genome structure and evolution of the maize B chromosome.
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Affiliation(s)
- Wei Huang
- National Maize Improvement Center of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, 100193 China
| | - Yan Du
- National Maize Improvement Center of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, 100193 China
| | - Xin Zhao
- National Maize Improvement Center of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, 100193 China
| | - Weiwei Jin
- National Maize Improvement Center of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, 100193 China
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Utsunomia R, Silva DMZDA, Ruiz-Ruano FJ, Araya-Jaime C, Pansonato-Alves JC, Scacchetti PC, Hashimoto DT, Oliveira C, Trifonov VA, Porto-Foresti F, Camacho JPM, Foresti F. Uncovering the Ancestry of B Chromosomes in Moenkhausia sanctaefilomenae (Teleostei, Characidae). PLoS One 2016; 11:e0150573. [PMID: 26934481 PMCID: PMC4775049 DOI: 10.1371/journal.pone.0150573] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/17/2016] [Indexed: 11/19/2022] Open
Abstract
B chromosomes constitute a heterogeneous mixture of genomic parasites that are sometimes derived intraspecifically from the standard genome of the host species, but result from interspecific hybridization in other cases. The mode of origin determines the DNA content, with the B chromosomes showing high similarity with the A genome in the first case, but presenting higher similarity with a different species in the second. The characid fish Moenkhausia sanctaefilomenae harbours highly invasive B chromosomes, which are present in all populations analyzed to date in the Parana and Tietê rivers. To investigate the origin of these B chromosomes, we analyzed two natural populations: one carrying B chromosomes and the other lacking them, using a combination of molecular cytogenetic techniques, nucleotide sequence analysis and high-throughput sequencing (Illumina HiSeq2000). Our results showed that i) B chromosomes have not yet reached the Paranapanema River basin; ii) B chromosomes are mitotically unstable; iii) there are two types of B chromosomes, the most frequent of which is lightly C-banded (similar to euchromatin in A chromosomes) (B1), while the other is darkly C-banded (heterochromatin-like) (B2); iv) the two B types contain the same tandem repeat DNA sequences (18S ribosomal DNA, H3 histone genes, MS3 and MS7 satellite DNA), with a higher content of 18S rDNA in the heterochromatic variant; v) all of these repetitive DNAs are present together only in the paracentromeric region of autosome pair no. 6, suggesting that the B chromosomes are derived from this A chromosome; vi) the two B chromosome variants show MS3 sequences that are highly divergent from each other and from the 0B genome, although the B2-derived sequences exhibit higher similarity with the 0B genome (this suggests an independent origin of the two B variants, with the less frequent, B2 type presumably being younger); and vii) the dN/dS ratio for the H3.2 histone gene is almost 4–6 times higher for B chromosomes than for A chromosome sequences, suggesting that purifying selection is relaxed for the DNA sequences located on the B chromosomes, presumably because they are mostly inactive.
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Affiliation(s)
- Ricardo Utsunomia
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
- * E-mail:
| | | | | | - Cristian Araya-Jaime
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | - José Carlos Pansonato-Alves
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Priscilla Cardim Scacchetti
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | | | - Claudio Oliveira
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | | | - Fábio Porto-Foresti
- Departamento de Ciências Biológicas, Faculdade de Ciências, Universidade Estadual Paulista, Bauru, São Paulo, Brazil
| | | | - Fausto Foresti
- Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
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Ruiz-Estévez M, Ruiz-Ruano FJ, Cabrero J, Bakkali M, Perfectti F, López-León MD, Camacho JPM. Non-random expression of ribosomal DNA units in a grasshopper showing high intragenomic variation for the ITS2 region. INSECT MOLECULAR BIOLOGY 2015; 24:319-330. [PMID: 25565136 DOI: 10.1111/imb.12158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We analyse intragenomic variation of the ITS2 internal transcribed spacer of ribosomal DNA (rDNA) in the grasshopper Eyprepocnemis plorans, by means of tagged PCR 454 amplicon sequencing performed on both genomic DNA (gDNA) and RNA-derived complementary DNA (cDNA), using part of the ITS2 flanking coding regions (5.8S and 28S rDNA) as an internal control for sequencing errors. Six different ITS2 haplotypes (i.e. variants for at least one nucleotide in the complete ITS2 sequence) were found in a single population, one of them (Hap4) being specific to a supernumerary (B) chromosome. The analysis of both gDNA and cDNA from the same individuals provided an estimate of the expression efficiency of the different haplotypes. We found random expression (i.e. about similar recovery in gDNA and cDNA) for three haplotypes (Hap1, Hap2 and Hap5), but significant underexpression for three others (Hap3, Hap4 and Hap6). Hap4 was the most extremely underexpressed and, remarkably, it showed the lowest sequence conservation for the flanking 5.8-28S coding regions in the gDNA reads but the highest conservation (100%) in the cDNA ones, suggesting the preferential expression of mutation-free rDNA units carrying this ITS2 haplotype. These results indicate that the ITS2 region of rDNA is far from complete homogenization in this species, and that the different rDNA units are not expressed at random, with some of them being severely downregulated.
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Affiliation(s)
- M Ruiz-Estévez
- Departamento de Genética, Universidad de Granada, Granada, Spain
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Banaei-Moghaddam AM, Martis MM, Macas J, Gundlach H, Himmelbach A, Altschmied L, Mayer KF, Houben A. Genes on B chromosomes: Old questions revisited with new tools. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:64-70. [DOI: 10.1016/j.bbagrm.2014.11.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/20/2014] [Accepted: 11/21/2014] [Indexed: 12/21/2022]
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