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Cardoso AL, Venturelli NB, da Cruz I, de Sá Patroni FM, de Moraes D, de Oliveira RA, Benavente R, Martins C. Meiotic behavior, transmission and active genes of B chromosomes in the cichlid Astatotilapia latifasciata: new clues about nature, evolution and maintenance of accessory elements. Mol Genet Genomics 2022; 297:1151-1167. [PMID: 35704117 DOI: 10.1007/s00438-022-01911-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 05/24/2022] [Indexed: 12/23/2022]
Abstract
Supernumerary B chromosomes (Bs) are dispensable genetic elements widespread in eukaryotes and are poorly understood mainly in relation to mechanisms of maintenance and transmission. The cichlid Astatotilapia latifasciata can harbor Bs in a range of 0 (named B -) and 1-2 (named B +). The B in A. latifasciata is rich in several classes of repetitive DNA sequences, contains protein coding genes, and affects hosts in diverse ways, including sex-biased effects. To advance in the knowledge about the mechanisms of maintenance and transmission of B chromosomes in A. latifasciata, here, we studied the meiotic behavior in males and transmission rates of A. latifasciata B chromosome. We also analyzed structurally and functionally the predicted B chromosome copies of the cell cycle genes separin-like, tubb1-like and kif11-like. We identified in the meiotic structure relative to the B chromosome the presence of proteins associated with Synaptonemal Complex organization (SMC3, SYCP1 and SYCP3) and found that the B performs self-pairing. These data suggest that isochromosome formation was a step during B chromosome evolution and this element is in a stage of diversification of the two arms keeping the self-pairing behavior to protect the A chromosome complement of negative effects of recombination. Moreover, we observed no occurrence of B-drive and confirmed the presence of cell cycle genes copies in the B chromosome and their transcription in encephalon, muscle and gonads, which can indicates beneficial effects to hosts and contribute to B maintenance.
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Affiliation(s)
- Adauto Lima Cardoso
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, Sao Paulo State University, UNESP, Botucatu, SP, 18618-689, Brazil
| | - Natália Bortholazzi Venturelli
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, Sao Paulo State University, UNESP, Botucatu, SP, 18618-689, Brazil
| | - Irene da Cruz
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074, Würzburg, Germany
| | - Fábio Malta de Sá Patroni
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, Sao Paulo State University, UNESP, Botucatu, SP, 18618-689, Brazil
| | - Diogo de Moraes
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, Sao Paulo State University, UNESP, Botucatu, SP, 18618-689, Brazil
| | - Rogério Antonio de Oliveira
- Department of Biostatistics, Plant Biology, Parasitology and Zoology, Institute of Biosciences at Botucatu, Sao Paulo State University, UNESP, Botucatu, Brazil
| | - Ricardo Benavente
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, 97074, Würzburg, Germany
| | - Cesar Martins
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, Sao Paulo State University, UNESP, Botucatu, SP, 18618-689, Brazil.
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B Chromosomes’ Sequences in Yellow-Necked Mice Apodemus flavicollis—Exploring the Transcription. Life (Basel) 2021; 12:life12010050. [PMID: 35054443 PMCID: PMC8781039 DOI: 10.3390/life12010050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 11/17/2022] Open
Abstract
B chromosomes (Bs) are highly polymorphic additional chromosomes in the genomes of many species. Due to the dispensability of Bs and the lack of noticeable phenotypic effects in their carriers, they were considered genetically inert for a long time. Recent studies on Bs in Apodemus flavicollis revealed their genetic composition, potential origin, and spatial organization in the interphase nucleus. Surprisingly, the genetic content of Bs in this species is preserved in all studied samples, even in geographically distinct populations, indicating its biological importance. Using RT-PCR we studied the transcription activity of three genes (Rraga, Haus6, and Cenpe) previously identified on Bs in A. flavicollis. We analysed mRNA isolated from spleen tissues of 34 animals harboring different numbers of Bs (0–3).The products of transcriptional activity of the analysed sequences differ in individuals with and without Bs. We recorded B-genes and/or genes from the standard genome in the presence of Bs, showing sex-dependent higher levels of transcriptional activity. Furthermore, the transcriptional activity of Cenpe varied with the age of the animals differently in the group with and without Bs. With aging, the amount of product was only found to significantly decrease in B carriers. The potential biological significance of all these differences is discussed in the paper.
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Caballero-López V, Lundberg M, Sokolovskis K, Bensch S. Transposable elements mark a repeat-rich region associated with migratory phenotypes of willow warblers (Phylloscopus trochilus). Mol Ecol 2021; 31:1128-1141. [PMID: 34837428 DOI: 10.1111/mec.16292] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 10/26/2021] [Accepted: 11/16/2021] [Indexed: 11/30/2022]
Abstract
The genetic basis of bird migration has been the focus of several studies. Two willow warbler subspecies (Phylloscopus trochilus trochilus and Phylloscopus trochilus acredula) follow different migratory routes to wintering grounds in Africa. Their breeding populations overlap in contact areas or "migratory divides" located in central Scandinavia and in eastern Poland. Earlier analyses demonstrated that the genetic differences between these two migratory phenotypes are few and cluster on chromosomes 1 and 5. In addition, an amplified fragment length polymorphism-derived biallelic marker (known as WW2) presents steep clines across both migratory divides but failed to be mapped in the genome. Here, we characterize the WW2 marker and describe its two variants (WW2 ancestral and WW2 derived) as portions of long terminal repeat retrotransposons originating from an ancient infection by an endogenous retrovirus. We used quantitative polymerase chain reaction techniques to quantify copy numbers of the WW2 derived variant in the two subspecies and their hybrids. This, together with genome analyses revealed that WW2 derived variants are much more abundant in P. t. acredula and appear embedded in a large repeat-rich region (>12 Mbp), not associated with the divergent regions of chromosomes 1 or 5. However, it might interact with genetic elements controlling migration direction. Testing this hypothesis further will require knowing the exact location of this region, such as by obtaining more complete genome assemblies preferably in combination with techniques like fluorescence in situ hybridization applied to a willow warbler karyotype, and finally to investigate the copy number of this marker in hybrids with known migratory tracks.
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Affiliation(s)
| | - Max Lundberg
- Department of Biology, Lund University, Lund, Sweden
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A supernumerary "B-sex" chromosome drives male sex determination in the Pachón cavefish, Astyanax mexicanus. Curr Biol 2021; 31:4800-4809.e9. [PMID: 34496222 DOI: 10.1016/j.cub.2021.08.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/30/2021] [Accepted: 08/09/2021] [Indexed: 01/30/2023]
Abstract
Sex chromosomes are generally derived from a pair of classical type-A chromosomes, and relatively few alternative models have been proposed up to now.1,2 B chromosomes (Bs) are supernumerary and dispensable chromosomes with non-Mendelian inheritance found in many plant and animal species3,4 that have often been considered as selfish genetic elements that behave as genome parasites.5,6 The observation that in some species Bs can be either restricted or predominant in one sex7-14 raised the interesting hypothesis that Bs could play a role in sex determination.15 The characterization of putative B master sex-determining (MSD) genes, however, has not yet been provided to support this hypothesis. Here, in Astyanax mexicanus cavefish originating from Pachón cave, we show that Bs are strongly male predominant. Based on a high-quality genome assembly of a B-carrying male, we characterized the Pachón cavefish B sequence and found that it contains two duplicated loci of the putative MSD gene growth differentiation factor 6b (gdf6b). Supporting its role as an MSD gene, we found that the Pachón cavefish gdf6b gene is expressed specifically in differentiating male gonads, and that its knockout induces male-to-female sex reversal in B-carrying males. This demonstrates that gdf6b is necessary for triggering male sex determination in Pachón cavefish. Altogether these results bring multiple and independent lines of evidence supporting the conclusion that the Pachón cavefish B is a "B-sex" chromosome that contains duplicated copies of the gdf6b gene, which can promote male sex determination in this species.
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Silva DMZDA, Araya-Jaime C, Yamashita M, Vidal MR, Oliveira C, Porto-Foresti F, Artoni RF, Foresti F. Meiotic self-pairing of the Psalidodon (Characiformes, Characidae) iso-B chromosome: A successful perpetuation mechanism. Genet Mol Biol 2021; 44:e20210084. [PMID: 34617950 PMCID: PMC8495774 DOI: 10.1590/1678-4685-gmb-2021-0084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 08/14/2021] [Indexed: 11/22/2022] Open
Abstract
B chromosomes are non-essential additional genomic elements present in several animal and plant species. In fishes, species of the genus Psalidodon (Characiformes, Characidae) harbor great karyotype diversity, and multiple populations carry different types of non-essential B chromosomes. This study analyzed how the dispensable supernumerary B chromosome of Psalidodon paranae behaves during meiosis to overcome checkpoints and express its own meiosis-specific genes. We visualized the synaptonemal complexes of P. paranae individuals with zero, one, or two B chromosomes using immunodetection with anti-medaka SYCP3 antibody and fluorescence in situ hybridization with a (CA)15 microsatellite probe. Our results showed that B chromosomes self-pair in cells containing only one B chromosome. In cells with two identical B chromosomes, these elements remain as separate synaptonemal complexes or close self-paired elements in the nucleus territory. Overall, we reveal that B chromosomes can escape meiotic silencing of unsynapsed chromatin through a self-pairing process, allowing expression of their own genes to facilitate regular meiosis resulting in fertile individuals. This behavior, also seen in other congeneric species, might be related to their maintenance throughout the evolutionary history of Psalidodon.
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Affiliation(s)
| | - Cristian Araya-Jaime
- Universidad de La Serena, Instituto de Investigación
Multidisciplinar en Ciencia y Tecnología, La Serena, Chile
- Universidad de La Serena, Departamento de Biología, Laboratorio de
Genética y Citogenética Vegetal, La Serena, Chile
| | - Masakane Yamashita
- Hokkaido University, Faculty of Science, Department of Biological
Sciences, Laboratory of Reproductive & Developmental Biology, Sapporo,
Japan
| | - Mateus Rossetto Vidal
- Universidade Estadual Paulista (UNESP), Instituto de Biociências de
Botucatu, Departamento de Biologia Estrutural e Funcional, Botucatu, SP,
Brazil
| | - Claudio Oliveira
- Universidade Estadual Paulista (UNESP), Instituto de Biociências de
Botucatu, Departamento de Biologia Estrutural e Funcional, Botucatu, SP,
Brazil
| | - Fábio Porto-Foresti
- Universidade Estadual Paulista (UNESP), Faculdade de Ciências,
Departamento de Ciências Biológicas, Bauru, SP, Brazil
| | - Roberto Ferreira Artoni
- Universidade Federal de São Carlos (UFSCAR), Departamento de
Genética e Evolução, São Carlos, SP, Brazil
- Universidade Estadual de Ponta Grossa (UEPG), Departamento de
Biologia Estrutural, Molecular e Genética, Ponta Grossa, PR, Brazil
| | - Fausto Foresti
- Universidade Estadual Paulista (UNESP), Instituto de Biociências de
Botucatu, Departamento de Biologia Estrutural e Funcional, Botucatu, SP,
Brazil
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Abstract
Female meiotic drive is the phenomenon where a selfish genetic element alters chromosome segregation during female meiosis to segregate to the egg and transmit to the next generation more frequently than Mendelian expectation. While several examples of female meiotic drive have been known for many decades, a molecular understanding of the underlying mechanisms has been elusive. Recent advances in this area in several model species prompts a comparative re-examination of these drive systems. In this review, we compare female meiotic drive of several animal and plant species, highlighting pertinent similarities.
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Affiliation(s)
- Frances E. Clark
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Takashi Akera
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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7
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Abstract
Chromosome size and morphology vary within and among species, but little is known about the proximate or ultimate causes of these differences. Cichlid fish species in the tribe Oreochromini share an unusual giant chromosome that is ∼3 times longer than the other chromosomes. This giant chromosome functions as a sex chromosome in some of these species. We test two hypotheses of how this giant sex chromosome may have evolved. The first hypothesis proposes that it evolved by accumulating repetitive elements as recombination was reduced around a dominant sex determination locus, as suggested by canonical models of sex chromosome evolution. An alternative hypothesis is that the giant sex chromosome originated via the fusion of an autosome with a highly repetitive B chromosome, one of which carried a sex determination locus. We test these hypotheses using comparative analysis of chromosome-scale cichlid and teleost genomes. We find that the giant sex chromosome consists of three distinct regions based on patterns of recombination, gene and transposable element content, and synteny to the ancestral autosome. The WZ sex determination locus encompasses the last ∼105 Mb of the 134-Mb giant chromosome. The last 47 Mb of the giant chromosome shares no obvious homology to any ancestral chromosome. Comparisons across 69 teleost genomes reveal that the giant sex chromosome contains unparalleled amounts of endogenous retroviral elements, immunoglobulin genes, and long noncoding RNAs. The results favor the B chromosome fusion hypothesis for the origin of the giant chromosome.
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Affiliation(s)
- Matthew A Conte
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Frances E Clark
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Reade B Roberts
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - Luohao Xu
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Wenjing Tao
- Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), School of Life Sciences, Southwest University, Chongqing, China
| | - Qi Zhou
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
- MOE Laboratory of Biosystems Homeostasis & Protection, Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Deshou Wang
- Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), School of Life Sciences, Southwest University, Chongqing, China
| | - Thomas D Kocher
- Department of Biology, University of Maryland, College Park, MD, USA
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Martins C, Jehangir M. A genomic glimpse of B chromosomes in cichlids. Genes Genomics 2021; 43:199-208. [PMID: 33547625 DOI: 10.1007/s13258-021-01049-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 01/11/2021] [Indexed: 01/25/2023]
Abstract
BACKGROUND B chromosomes (Bs) are extra karyotype elements in addition to A chromosomes and are found in all major eukaryotic taxa. Among hundreds of investigated species, cichlid fishes have emerged as an interesting group of model and have contributed to unravel the complex biology of B chromosome. OBJECTIVE We review the current state of knowledge on B chromosome investigation in cichlid fish and discuss the recent genomic advances over gene and sequences hunting on Bs and their impact on the current concept of B chromosomes. RESULTS The Bs of cichlids have been under the subject of classical cytogenetics and high scale DNA, RNA and epigenetics analysis and a list of B chromosome genes and functional sequences has been generated. B chromosomes of cichlids are restricted to females in some species and are enriched with genes, relics of genes, transposable elements and sequences transcribing for many significant biological functions. Diverse potentially functional sequences have been described in the B chromosome of cichlids and could influence important biological characteristics as well seems to affect transcription and epigenetic modifications of the whole genome. CONCLUSION One of the most enigmatic characteristics of Bs in cichlids is their genic content related to cell cycle and chromosome structure, and their influence over sex rates. The relationship of Bs with cell cycle and sex determination looks like to be connected with the drive of the Bs during cell divisions.
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Affiliation(s)
- Cesar Martins
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, São Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil.
| | - Maryam Jehangir
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, São Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil
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Feller AF, Ogi V, Seehausen O, Meier JI. Identification of a novel sex determining chromosome in cichlid fishes that acts as XY or ZW in different lineages. HYDROBIOLOGIA 2021; 848:3727-3745. [PMID: 34720170 PMCID: PMC8550731 DOI: 10.1007/s10750-021-04560-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 02/02/2021] [Accepted: 02/23/2021] [Indexed: 05/02/2023]
Abstract
UNLABELLED Sex determination systems are highly conserved among most vertebrates with genetic sex determination, but can be variable and evolve rapidly in some. Here, we study sex determination in a clade with exceptionally high sex chromosome turnover rates. We identify the sex determining chromosomes in three interspecific crosses of haplochromine cichlid fishes from Lakes Victoria and Malawi. We find evidence for different sex determiners in each cross. In the Malawi cross and one Victoria cross the same chromosome is sex-linked but while females are the heterogametic sex in the Malawi species, males are the heterogametic sex in the Victoria species. This chromosome has not previously been reported to be sex determining in cichlids, increasing the number of different chromosomes shown to be sex determining in cichlids to 12. All Lake Victoria species of our crosses are less than 15,000 years divergent, and we identified different sex determiners among them. Our study provides further evidence for the diversity and evolutionary flexibility of sex determination in cichlids, factors which might contribute to their rapid adaptive radiations. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s10750-021-04560-7.
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Affiliation(s)
- Anna F. Feller
- Division of Aquatic Ecology & Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
| | - Vera Ogi
- Division of Aquatic Ecology & Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
| | - Ole Seehausen
- Division of Aquatic Ecology & Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
| | - Joana I. Meier
- Division of Aquatic Ecology & Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ UK
- St John’s College, University of Cambridge, St John’s Street, Cambridge, CB2 1TP UK
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Ranucci L, Fernandes CA, Borin-Carvalho LA, Martins-Santos IC, Portela-Castro ALBD. Occurrence of euchromatic B chromosomes in natural populations of Moenkhausia bonita and M. forestii (Pisces: Characidae). NEOTROPICAL ICHTHYOLOGY 2021. [DOI: 10.1590/1982-0224-2021-0056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ABSTRACT Moenkhausia is a highly specious genus among the Characidae, composed of 96 valid species. Only twelve species have a known karyotype. Thus, here are presented the first cytogenetic data of two allopatric populations of Moenkhausia bonita and one of M. forestii, both belonging to the upper Paraná River basin (PR) with discussion on the evolutionary and cytotaxonomic aspects of the genus. The two species presented 2n = 50 chromosomes but different karyotype formulas and occurrence of 1-2 B chromosomes. These elements are small metacentrics in M. bonita and small acrocentrics in M. forestii. In both species, B chromosomes were euchromatic. Ag-NOR sites were found in pair 3 (metacentric), coinciding with fluorescent in situ hybridization (FISH) by the 18S rDNA probe in both species. However, the species differed in terms of the number and position of 5S rDNA sites. Heterochromatic blocks, mapped in M. bonita showed the least amount of heterochromatin in the terminal and pericentromeric regions, while the M. forestii karyotype revealed a greater amount of interstitial heterochromatic blocks. The karyotype distinctions between the two species, including the morphology of B chromosomes, may contribute as a reference in the taxonomic studies in this group.
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Affiliation(s)
| | - Carlos A. Fernandes
- Universidade Estadual de Maringá, Brazil; Universidade Estadual de Maringá, Brazil
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11
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Tao W, Conte MA, Wang D, Kocher TD. Network architecture and sex chromosome turnovers: Do epistatic interactions shape patterns of sex chromosome replacement? Bioessays 2020; 43:e2000161. [PMID: 33283342 DOI: 10.1002/bies.202000161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 11/04/2020] [Accepted: 11/05/2020] [Indexed: 11/11/2022]
Abstract
Recent studies have revealed an astonishing diversity of sex chromosomes in many vertebrate lineages, prompting questions about the mechanisms of sex chromosome turnover. While there is considerable population genetic theory about the evolutionary forces promoting sex chromosome replacement, this theory has not yet been integrated with our understanding of the molecular and developmental genetics of sex determination. Here, we review recent data to examine four questions about how the structure of gene networks influences the evolution of sex determination. We argue that patterns of epistasis, arising from the structure of genetic networks, may play an important role in regulating the rates and patterns of sex chromosome replacement.
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Affiliation(s)
- Wenjing Tao
- Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing, China
| | - Matthew A Conte
- Department of Biology, University of Maryland, College Park, Maryland, USA
| | - Deshou Wang
- Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing, China
| | - Thomas D Kocher
- Department of Biology, University of Maryland, College Park, Maryland, USA
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12
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Svardal H, Salzburger W, Malinsky M. Genetic Variation and Hybridization in Evolutionary Radiations of Cichlid Fishes. Annu Rev Anim Biosci 2020; 9:55-79. [PMID: 33197206 DOI: 10.1146/annurev-animal-061220-023129] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Evolutionary radiations are responsible for much of the variation in biodiversity across taxa. Cichlid fishes are well known for spectacular evolutionary radiations, as they have repeatedly evolved into large and phenotypically diverse arrays of species. Cichlid genomes carry signatures of past events and, at the same time, are the substrate for ongoing evolution. We survey genome-wide data and the available literature covering 438 cichlid populations (412 species) across multiple radiations to synthesize information about patterns and sharing of genetic variation. Nucleotide diversity within species is low in cichlids, with 92% of surveyed populations having less diversity than the median value found in other vertebrates. Divergence within radiations is also low, and a large proportion of variation is shared among species due to incomplete lineage sorting and widespread hybridization. Population genetics therefore provides a suitable conceptual framework for evolutionary genomic studies of cichlid radiations. We focus in detail on the roles of hybridization in shaping the patterns of genetic variation and in promoting cichlid diversification.
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Affiliation(s)
- Hannes Svardal
- Department of Biology, University of Antwerp, 2020 Antwerp, Belgium; .,Naturalis Biodiversity Center, 2333 Leiden, The Netherlands
| | - Walter Salzburger
- Zoological Institute, University of Basel, 4051 Basel, Switzerland; ,
| | - Milan Malinsky
- Zoological Institute, University of Basel, 4051 Basel, Switzerland; ,
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Structure and Sequence of the Sex Determining Locus in Two Wild Populations of Nile Tilapia. Genes (Basel) 2020; 11:genes11091017. [PMID: 32872430 PMCID: PMC7563666 DOI: 10.3390/genes11091017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/15/2020] [Accepted: 08/27/2020] [Indexed: 12/30/2022] Open
Abstract
In domesticated strains of the Nile tilapia, phenotypic sex has been linked to genetic variants on linkage groups 1, 20 and 23. This diversity of sex-loci might reflect a naturally polymorphic sex determination system in Nile tilapia, or it might be an artefact arising from the process of domestication. Here, we searched for sex-determiners in wild populations from Kpandu, Lake Volta (Ghana-West Africa), and from Lake Koka (Ethiopia-East Africa) that have not been subjected to any genetic manipulation. We analysed lab-reared families using double-digest Restriction Associated DNA sequencing (ddRAD) and analysed wild-caught males and females with pooled whole-genome sequencing (WGS). Strong sex-linked signals were found on LG23 in both populations, and sex-linked signals with LG3 were observed in Kpandu samples. WGS uncovered blocks of high sequence coverage, suggesting the presence of B chromosomes. We confirmed the existence of a tandem amh duplication in LG23 in both populations and determined its breakpoints between the oaz1 and dot1l genes. We found two common deletions of ~5 kb in males and confirmed the presence of both amhY and amh∆Y genes. Males from Lake Koka lack both the previously reported 234 bp deletion and the 5 bp frameshift-insertion that creates a premature stop codon in amh∆Y.
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14
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Clark FE, Kocher TD. Changing sex for selfish gain: B chromosomes of Lake Malawi cichlid fish. Sci Rep 2019; 9:20213. [PMID: 31882583 PMCID: PMC6934658 DOI: 10.1038/s41598-019-55774-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 11/02/2019] [Indexed: 01/16/2023] Open
Abstract
B chromosomes are extra, non-essential chromosomes present in addition to the normal complement of A chromosomes. Many species of cichlid fish in Lake Malawi carry a haploid, female-restricted B chromosome. Here we show that this B chromosome exhibits drive, with an average transmission rate of 70%. The offspring of B-transmitting females exhibit a strongly female-biased sex ratio. Genotyping of these offspring reveals the B chromosome carries a female sex determiner that is epistatically dominant to an XY system on linkage group 7. We suggest that this sex determiner evolved to enhance the meiotic drive of the B chromosome. This is some of the first evidence that female meiotic drive can lead to the invasion of new sex chromosomes solely to benefit the driver, and not to compensate for skewed sex ratios.
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Affiliation(s)
- Frances E Clark
- Department of Biology, University of Maryland College Park, College Park, MD, 20742, USA.
| | - Thomas D Kocher
- Department of Biology, University of Maryland College Park, College Park, MD, 20742, USA
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15
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Gammerdinger WJ, Conte MA, Sandkam BA, Ziegelbecker A, Koblmüller S, Kocher TD. Novel Sex Chromosomes in 3 Cichlid Fishes from Lake Tanganyika. J Hered 2019; 109:489-500. [PMID: 29444291 DOI: 10.1093/jhered/esy003] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 01/18/2018] [Indexed: 12/12/2022] Open
Abstract
African cichlids are well known for their adaptive radiations, but it is now apparent that they also harbor an extraordinary diversity of sex chromosome systems. In this study, we sequenced pools of males and females from species in 3 different genera of cichlids from Lake Tanganyika. We then searched for regions that were differentiated following the patterns expected for sex chromosomes. We report 2 novel sex chromosomes systems, an XY system on LG19 in Tropheus sp. "black" and a ZW system on LG7 in Hemibates stenosoma. We also identify a ZW system on LG5 in Cyprichromis leptosoma that may be convergent with a system previously described in Lake Malawi cichlids. Our data also identify candidate single nucleotide polymorphisms for the blue/yellow tail color polymorphism observed among male C. leptosoma.
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Affiliation(s)
| | - Matthew A Conte
- Department of Biology, University of Maryland, College Park, MD, USA
| | | | | | - Stephan Koblmüller
- Institute of Zoology, University of Graz, Universitätsplatz, Graz, Austria
| | - Thomas D Kocher
- Department of Biology, University of Maryland, College Park, MD, USA
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16
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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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17
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Majtánová Z, Indermaur A, Nyom ARB, Ráb P, Musilova Z. Adaptive Radiation from a Chromosomal Perspective: Evidence of Chromosome Set Stability in Cichlid Fishes (Cichlidae: Teleostei) from the Barombi Mbo Lake, Cameroon. Int J Mol Sci 2019; 20:ijms20204994. [PMID: 31601021 PMCID: PMC6834198 DOI: 10.3390/ijms20204994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/04/2019] [Accepted: 10/07/2019] [Indexed: 12/11/2022] Open
Abstract
Cichlid fishes are the subject of scientific interest because of their rapid adaptive radiation, resulting in extensive ecological and taxonomic diversity. In this study, we examined 11 morphologically distinct cichlid species endemic to Barombi Mbo, the largest crater lake in western Cameroon, namely Konia eisentrauti, Konia dikume, Myaka myaka, Pungu maclareni, Sarotherodon steinbachi, Sarotherodon lohbergeri, Sarotherodon linnellii, Sarotherodon caroli, Stomatepia mariae, Stomatepia pindu, and Stomatepia mongo. These species supposedly evolved via sympatric ecological speciation from a common ancestor, which colonized the lake no earlier than one million years ago. Here we present the first comparative cytogenetic analysis of cichlid species from Barombi Mbo Lake using both conventional (Giemsa staining, C-banding, and CMA3/DAPI staining) and molecular (fluorescence in situ hybridization with telomeric, 5S, and 28S rDNA probes) methods. We observed stability on both macro and micro-chromosomal levels. The diploid chromosome number was 2n = 44, and the karyotype was invariably composed of three pairs of meta/submetacentric and 19 pairs of subtelo/acrocentric chromosomes in all analysed species, with the same numbers of rDNA clusters and distribution of heterochromatin. The results suggest the evolutionary stability of chromosomal set; therefore, the large-scale chromosomal rearrangements seem to be unlikely associated with the sympatric speciation in Barombi Mbo.
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Affiliation(s)
- Zuzana Majtánová
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 27721 Liběchov, Czech Republic.
| | - Adrian Indermaur
- Zoological Institute, University of Basel, 4051 Basel, Switzerland.
| | - Arnold Roger Bitja Nyom
- Department of Biological Sciences, University of Ngaoundéré, Ngaoundéré P.O Box 454, Cameroon.
- Department of Management of Fisheries and Aquatic Ecosystems, University of Douala, Douala P.O Box 2701, Cameroon.
| | - Petr Ráb
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 27721 Liběchov, Czech Republic.
| | - Zuzana Musilova
- Department of Zoology, Faculty of Science, Charles University in Prague, 12844 Prague, Czech Republic.
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18
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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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19
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Favarato RM, Braga Ribeiro L, Ota RP, Nakayama CM, Feldberg E. Cytogenetic Characterization of Two Metynnis Species (Characiformes, Serrasalmidae) Reveals B Chromosomes Restricted to the Females. Cytogenet Genome Res 2019; 158:38-45. [DOI: 10.1159/000499954] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2018] [Indexed: 11/19/2022] Open
Abstract
Karyotypes and chromosomal characteristics with focus on B chromosomes of 2 species of the serrasalmid genus Metynnis, namely M. lippincottianus and M. maculatus, were examined using conventional (C-banding) and molecular (FISH mapping of minor and major rDNAs and Rex1, Rex3, and Rex6 retrotransposable elements) protocols. Both species possessed a diploid chromosome number of 2n = 62 and karyotypes composed of 32 metacentric + 28 submetacentric + 2 subtelocentric and 32 metacentric + 26 submetacentric + 4 subtelocentric, respectively; one small B element was found in the female genome of M. lippincottianus. C-banding revealed heterochromatin in the pericentromeric and terminal portions of all chromosomes of both species; the B chromosome was entirely heterochromatic. FISH showed 18S rDNA sites in 2 chromosome pairs in both species (pairs 19 and 22), and a large block in the B chromosome, while 5S rDNA signals were detected in the first pair of subtelocentric chromosomes in both species, moreover in M. maculatus an additional labeled pair 4 was observed. Mapping of the Rex1, Rex3, and Rex6 retrotransposable elements in the genomes of M. lippincottianus and M. maculatus indicated that they were dispersed throughout nearly all the chromosomes of the complement, except for the B chromosome of M. lippincottianus.
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20
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Cardoso AL, Fantinatti BEDA, Venturelli NB, Carmello BDO, de Oliveira RA, Martins C. Epigenetic DNA Modifications Are Correlated With B Chromosomes and Sex in the Cichlid Astatotilapia latifasciata. Front Genet 2019; 10:324. [PMID: 31031803 PMCID: PMC6474290 DOI: 10.3389/fgene.2019.00324] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 03/22/2019] [Indexed: 12/11/2022] Open
Abstract
Supernumerary B chromosomes are dispensable elements found in several groups of eukaryotes, and their impacts in host organisms are not clear. The cichlid fish Astatotilapia latifasciata presents one or two large metacentric B chromosomes. These elements affect the transcription of several classes of RNAs. Here, we evaluated the epigenetic DNA modification status of B chromosomes using immunocytogenetics and assessed the impact of B chromosome presence on the global contents of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) and the molecular mechanisms underlying these variations. We found that the B chromosome of A. latifasciata has an active pattern of DNA epimarks, and its presence promotes the loss of 5mC in gonads of females with B chromosome (FB+) and promotes the loss of 5hmC in the muscle of males with the B element (MB+). Based on the transcriptional quantification of DNA modification genes (dnmt, tet, and tdg) and their candidate regulators (idh genes, microRNAs, and long non-coding RNAs) and on RNA-protein interaction prediction, we suggest the occurrence of passive demethylation in gonads of FB+ and 5hmC loss by Tet inhibition or by 5hmC oxidation in MB+ muscle. We suggest that these results can also explain the previously reported variations in the transcription levels of several classes of RNA depending on B chromosome presence. The DNA modifications detected here are also influenced by sex. Although the correlation between B chromosomes and sex has been previously reported, it remains unexplained. The B chromosome of A. latifasciata seems to be active and impacts cell physiology in a very complex way, including at the epigenetic level.
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Affiliation(s)
- Adauto Lima Cardoso
- Integrative Genomics Laboratory, Department of Morphology, Institute of Biosciences, São Paulo State University - Universidade Estadual Paulista, Botucatu, Brazil
| | - Bruno Evaristo de Almeida Fantinatti
- Integrative Genomics Laboratory, Department of Morphology, Institute of Biosciences, São Paulo State University - Universidade Estadual Paulista, Botucatu, Brazil
| | - Natália Bortholazzi Venturelli
- Integrative Genomics Laboratory, Department of Morphology, Institute of Biosciences, São Paulo State University - Universidade Estadual Paulista, Botucatu, Brazil
| | - Bianca de Oliveira Carmello
- Integrative Genomics Laboratory, Department of Morphology, Institute of Biosciences, São Paulo State University - Universidade Estadual Paulista, Botucatu, Brazil
| | - Rogério Antonio de Oliveira
- Department of Biostatistics, Institute of Biosciences, São Paulo State University - Universidade Estadual Paulista, Botucatu, Brazil
| | - Cesar Martins
- Integrative Genomics Laboratory, Department of Morphology, Institute of Biosciences, São Paulo State University - Universidade Estadual Paulista, Botucatu, Brazil
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21
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Conte MA, Joshi R, Moore EC, Nandamuri SP, Gammerdinger WJ, Roberts RB, Carleton KL, Lien S, Kocher TD. Chromosome-scale assemblies reveal the structural evolution of African cichlid genomes. Gigascience 2019; 8:giz030. [PMID: 30942871 PMCID: PMC6447674 DOI: 10.1093/gigascience/giz030] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 01/11/2019] [Accepted: 03/07/2019] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND African cichlid fishes are well known for their rapid radiations and are a model system for studying evolutionary processes. Here we compare multiple, high-quality, chromosome-scale genome assemblies to elucidate the genetic mechanisms underlying cichlid diversification and study how genome structure evolves in rapidly radiating lineages. RESULTS We re-anchored our recent assembly of the Nile tilapia (Oreochromis niloticus) genome using a new high-density genetic map. We also developed a new de novo genome assembly of the Lake Malawi cichlid, Metriaclima zebra, using high-coverage Pacific Biosciences sequencing, and anchored contigs to linkage groups (LGs) using 4 different genetic maps. These new anchored assemblies allow the first chromosome-scale comparisons of African cichlid genomes. Large intra-chromosomal structural differences (∼2-28 megabase pairs) among species are common, while inter-chromosomal differences are rare (<10 megabase pairs total). Placement of the centromeres within the chromosome-scale assemblies identifies large structural differences that explain many of the karyotype differences among species. Structural differences are also associated with unique patterns of recombination on sex chromosomes. Structural differences on LG9, LG11, and LG20 are associated with reduced recombination, indicative of inversions between the rock- and sand-dwelling clades of Lake Malawi cichlids. M. zebra has a larger number of recent transposable element insertions compared with O. niloticus, suggesting that several transposable element families have a higher rate of insertion in the haplochromine cichlid lineage. CONCLUSION This study identifies novel structural variation among East African cichlid genomes and provides a new set of genomic resources to support research on the mechanisms driving cichlid adaptation and speciation.
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Affiliation(s)
- Matthew A Conte
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Rajesh Joshi
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, PO Box 5003, Ås, Norway
| | - Emily C Moore
- Department of Biological Sciences and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695, USA
| | | | | | - Reade B Roberts
- Department of Biological Sciences and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Sigbjørn Lien
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, PO Box 5003, Ås, Norway
| | - Thomas D Kocher
- Department of Biology, University of Maryland, College Park, MD 20742, USA
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22
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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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23
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Gammerdinger WJ, Kocher TD. Unusual Diversity of Sex Chromosomes in African Cichlid Fishes. Genes (Basel) 2018; 9:E480. [PMID: 30287777 PMCID: PMC6210639 DOI: 10.3390/genes9100480] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 09/26/2018] [Accepted: 10/01/2018] [Indexed: 11/30/2022] Open
Abstract
African cichlids display a remarkable assortment of jaw morphologies, pigmentation patterns, and mating behaviors. In addition to this previously documented diversity, recent studies have documented a rich diversity of sex chromosomes within these fishes. Here we review the known sex-determination network within vertebrates, and the extraordinary number of sex chromosomes systems segregating in African cichlids. We also propose a model for understanding the unusual number of sex chromosome systems within this clade.
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Affiliation(s)
- William J Gammerdinger
- Institute of Science and Technology (IST) Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
| | - Thomas D Kocher
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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24
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Coan RLB, Martins C. Landscape of Transposable Elements Focusing on the B Chromosome of the Cichlid Fish Astatotilapia latifasciata. Genes (Basel) 2018; 9:genes9060269. [PMID: 29882892 PMCID: PMC6027319 DOI: 10.3390/genes9060269] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 05/16/2018] [Accepted: 05/17/2018] [Indexed: 12/26/2022] Open
Abstract
B chromosomes (Bs) are supernumerary elements found in many taxonomic groups. Most B chromosomes are rich in heterochromatin and composed of abundant repetitive sequences, especially transposable elements (TEs). B origin is generally linked to the A-chromosome complement (A). The first report of a B chromosome in African cichlids was in Astatotilapia latifasciata, which can harbor 0, 1, or 2 Bs Classical cytogenetic studies found high a TE content on this B chromosome. In this study, we aimed to understand TE composition and expression in the A. latifasciata genome and its relation to the B chromosome. We used bioinformatics analysis to explore the genomic organization of TEs and their composition on the B chromosome. The bioinformatics findings were validated by fluorescent in situ hybridization (FISH) and real-time PCR (qPCR). A. latifasciata has a TE content similar to that of other cichlid fishes and several expanded elements on its B chromosome. With RNA sequencing data (RNA-seq), we showed that all major TE classes are transcribed in the brain, muscle, and male and female gonads. An evaluation of TE transcription levels between B- and B+ individuals showed that few elements are differentially expressed between these groups and that the expanded B elements are not highly transcribed. Putative silencing mechanisms may act on the B chromosome of A. latifasciata to prevent the adverse consequences of repeat transcription and mobilization in the genome.
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Affiliation(s)
- Rafael L B Coan
- Department of Morphology, Institute of Biosciences, São Paulo State University (UNESP), 18618-689 Botucatu, SP, Brazil.
| | - Cesar Martins
- Department of Morphology, Institute of Biosciences, São Paulo State University (UNESP), 18618-689 Botucatu, SP, Brazil.
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25
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Malimpensa GC, Traldi JB, Toyama D, Henrique-Silva F, Vicari MR, Moreira-Filho O. Chromosomal Mapping of Repeat DNA in Bergiaria westermanni (Pimelodidae, Siluriformes): Localization of 45S rDNA in B Chromosomes. Cytogenet Genome Res 2018; 154:99-106. [PMID: 29635248 DOI: 10.1159/000487652] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2017] [Indexed: 12/19/2022] Open
Abstract
The occurrence of repetitive DNA in autosomes and B chromosomes of Bergiaria westermanni was examined using conventional and molecular cytogenetic techniques. This species exhibited 2n = 56 chromosomes, with intra- and interindividual variation in the number of heterochromatic B chromosomes (from 0 to 4). The 5S rDNA was localized in pairs 1 and 5, and histone probes (H1, H3, and H4) and U2 small nuclear RNA were syntenic with 5S rDNA in pair 5. Histone sequences were also located in chromosome pair 14. The (GATA)n sequence was dispersed throughout the autosomes and B chromosomes, with clusters (microsatellite accumulation) in some chromosome regions. The telomeric probe revealed no signs of chromosomal rearrangements in the genome of B. westermanni. The 45S rDNA sites were detected in the terminal region of pair 27; these sites corresponded to a GC-rich heterochromatin block. In addition, 3 of the 4 B chromosomes also contained 45S rDNA copies. Silver nitrate staining in interphase nuclei provided indirect evidence of the expression of these rRNA genes in B chromosomes, indicating the probable origin of these elements. This report shows plasticity in the chromosomal localization of repeat DNA in B. westermanni and features a discussion of genomic diversification.
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Affiliation(s)
- Geovana C Malimpensa
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
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26
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Ruban A, Schmutzer T, Scholz U, Houben A. How Next-Generation Sequencing Has Aided Our Understanding of the Sequence Composition and Origin of B Chromosomes. Genes (Basel) 2017; 8:E294. [PMID: 29068386 PMCID: PMC5704207 DOI: 10.3390/genes8110294] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 10/18/2017] [Accepted: 10/24/2017] [Indexed: 12/21/2022] Open
Abstract
Accessory, supernumerary, or-most simply-B chromosomes, are found in many eukaryotic karyotypes. These small chromosomes do not follow the usual pattern of segregation, but rather are transmitted in a higher than expected frequency. As increasingly being demonstrated by next-generation sequencing (NGS), their structure comprises fragments of standard (A) chromosomes, although in some plant species, their sequence also includes contributions from organellar genomes. Transcriptomic analyses of various animal and plant species have revealed that, contrary to what used to be the common belief, some of the B chromosome DNA is protein-encoding. This review summarizes the progress in understanding B chromosome biology enabled by the application of next-generation sequencing technology and state-of-the-art bioinformatics. In particular, a contrast is drawn between a direct sequencing approach and a strategy based on a comparative genomics as alternative routes that can be taken towards the identification of B chromosome sequences.
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Affiliation(s)
- Alevtina Ruban
- Leibniz Institute of Plant Genetics and Crop Plant Research Gatersleben, 06466 Seeland, Germany.
| | - Thomas Schmutzer
- Leibniz Institute of Plant Genetics and Crop Plant Research Gatersleben, 06466 Seeland, Germany.
| | - Uwe Scholz
- Leibniz Institute of Plant Genetics and Crop Plant Research Gatersleben, 06466 Seeland, Germany.
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research Gatersleben, 06466 Seeland, Germany.
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27
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28
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Carmello BO, Coan RLB, Cardoso AL, Ramos E, Fantinatti BEA, Marques DF, Oliveira RA, Valente GT, Martins C. The hnRNP Q-like gene is retroinserted into the B chromosomes of the cichlid fish Astatotilapia latifasciata. Chromosome Res 2017; 25:277-290. [PMID: 28776210 DOI: 10.1007/s10577-017-9561-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/12/2017] [Accepted: 07/14/2017] [Indexed: 11/27/2022]
Abstract
B chromosomes are dispensable elements observed in many eukaryotic species, including the African cichlid Astatotilapia latifasciata, which might have one or two B chromosomes. Although there have been many studies focused on the biology of these chromosomes, questions about the evolution, maintenance, and potential effects of these chromosomes remain. Here, we identified a variant form of the hnRNP Q-like gene inserted into the B chromosome of A. latifasciata that is characterized by a high copy number and intron-less structure. The absence of introns and presence of transposable elements with a reverse transcriptase domain flanking hnRNP Q-like sequences suggest that this gene was retroinserted into the B chromosome. RNA-Seq analysis did not show that the B variant retroinserted copies are transcriptionally active. However, RT-qPCR results showed variations in the canonical hnRNP Q-like copy expression levels among exons, tissues, sex, and B presence/absence. Although the patterns of transcription are not well understood, the exons of the B retrocopies were overexpressed, and a bias for female B+ expression was also observed. These results suggest that retroinsertion is an additional and important mechanism contributing to B chromosome formation. Furthermore, these findings indicate a bias towards female differential expression of B chromosome sequences, suggesting that B chromosomes and sex determination are somehow associated in cichlids.
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Affiliation(s)
- Bianca O Carmello
- Institute of Biosciences, Department of Morphology, Sao Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil
| | - Rafael L B Coan
- Institute of Biosciences, Department of Morphology, Sao Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil
| | - Adauto L Cardoso
- Institute of Biosciences, Department of Morphology, Sao Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil
| | - Erica Ramos
- Institute of Biosciences, Department of Morphology, Sao Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil
| | - Bruno E A Fantinatti
- Institute of Biosciences, Department of Morphology, Sao Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil
| | - Diego F Marques
- Institute of Biosciences, Department of Morphology, Sao Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil
| | - Rogério A Oliveira
- Institute of Biosciences, Department of Biostatistics, Sao Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil
| | - Guilherme T Valente
- Institute of Biosciences, Agronomic Science School, Department of Bioprocess and Biotechnology, Sao Paulo State University (UNESP), Botucatu, SP, 18610-307, Brazil
| | - Cesar Martins
- Institute of Biosciences, Department of Morphology, Sao Paulo State University (UNESP), Botucatu, SP, 18618-689, Brazil.
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Peterson EN, Cline ME, Moore EC, Roberts NB, Roberts RB. Genetic sex determination in Astatotilapia calliptera, a prototype species for the Lake Malawi cichlid radiation. Naturwissenschaften 2017; 104:41. [DOI: 10.1007/s00114-017-1462-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/06/2017] [Accepted: 04/09/2017] [Indexed: 11/30/2022]
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