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Dedukh D, Marta A, Myung RY, Ko MH, Choi DS, Won YJ, Janko K. A cyclical switch of gametogenic pathways in hybrids depends on the ploidy level. Commun Biol 2024; 7:424. [PMID: 38589507 PMCID: PMC11001910 DOI: 10.1038/s42003-024-05948-6] [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: 07/01/2023] [Accepted: 02/21/2024] [Indexed: 04/10/2024] Open
Abstract
The cellular and molecular mechanisms governing sexual reproduction are conserved across eukaryotes. Nevertheless, hybridization can disrupt these mechanisms, leading to asexual reproduction, often accompanied by polyploidy. In this study, we investigate how ploidy level and ratio of parental genomes in hybrids affect their reproductive mode. We analyze the gametogenesis of sexual species and their diploid and triploid hybrids from the freshwater fish family Cobitidae, using newly developed cytogenetic markers. We find that diploid hybrid females possess oogonia and oocytes with original (diploid) and duplicated (tetraploid) ploidy. Diploid oocytes cannot progress beyond pachytene due to aberrant pairing. However, tetraploid oocytes, which emerge after premeiotic genome endoreplication, exhibit normal pairing and result in diploid gametes. Triploid hybrid females possess diploid, triploid, and haploid oogonia and oocytes. Triploid and haploid oocytes cannot progress beyond pachytene checkpoint due to aberrant chromosome pairing, while diploid oocytes have normal pairing in meiosis, resulting in haploid gametes. Diploid oocytes emerge after premeiotic elimination of a single-copied genome. Triploid hybrid males are sterile due to aberrant pairing and the failure of chromosomal segregation during meiotic divisions. Thus, changes in ploidy and genome dosage may lead to cyclical alteration of gametogenic pathways in hybrids.
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Affiliation(s)
- Dmitrij Dedukh
- Laboratory of Non-Mendelian Evolution, Institute of Animal Physiology and Genetics of the CAS, Liběchov, Czech Republic.
| | - Anatolie Marta
- Laboratory of Non-Mendelian Evolution, Institute of Animal Physiology and Genetics of the CAS, Liběchov, Czech Republic
| | - Ra-Yeon Myung
- Division of EcoScience, Ewha Womans University, Seoul, South Korea
| | | | - Da-Song Choi
- Division of EcoScience, Ewha Womans University, Seoul, South Korea
| | - Yong-Jin Won
- Division of EcoScience, Ewha Womans University, Seoul, South Korea
| | - Karel Janko
- Laboratory of Non-Mendelian Evolution, Institute of Animal Physiology and Genetics of the CAS, Liběchov, Czech Republic.
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic.
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Dudzik A, Dedukh D, Crochet PA, Rozenblut-Kościsty B, Rybka H, Doniol-Valcroze P, Choleva L, Ogielska M, Chmielewska M. Cytogenetics of the Hybridogenetic Frog Pelophylax grafi and Its Parental Species Pelophylax perezi. Genome Biol Evol 2023; 15:evad215. [PMID: 38015654 PMCID: PMC10715190 DOI: 10.1093/gbe/evad215] [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: 07/21/2023] [Revised: 11/10/2023] [Accepted: 11/19/2023] [Indexed: 11/30/2023] Open
Abstract
Hybrid taxa from the genus Pelophylax can propagate themselves in a modified way of sexual reproduction called hybridogenesis ensuring the formation of clonal gametes containing the genome of only one parental (host) species. Pelophylax grafi from South-Western Europe is a hybrid composed of P. ridibundus and P. perezi genomes and it lives with a host species P. perezi (P-G system). Yet it is unknown, whether non-Mendelian inheritance is fully maintained in such populations. In this study, we characterize P. perezi and P. grafi somatic karyotypes by using comparative genomic hybridization, genomic in situ hybridization, fluorescent in situ hybridization, and actinomycin D-DAPI. Here, we show the homeology of P. perezi and P. grafi somatic karyotypes to other Pelophylax taxa with 2n = 26 and equal contribution of ridibundus and perezi chromosomes in P. grafi which supports F1 hybrid genome constitution as well as a hemiclonal genome inheritance. We show that ridibundus chromosomes have larger regions of interstitial (TTAGGG)n repeats flanking the nucleolus organizing region on chromosome no. 10 and a high quantity of AT pairs in the centromeric regions. In P. perezi, we found species-specific sequences in metaphase chromosomes and marker structures in lampbrush chromosomes. Pericentromeric RrS1 repeat sequence was present in perezi and ridibundus chromosomes, but the blocks were stronger in ridibundus. Various cytogenetic techniques applied to the P-G system provide genome discrimination between ridibundus and perezi chromosomal sets. They could be used in studies of germ-line cells to explain patterns of clonal gametogenesis in P. grafi and broaden the knowledge about reproductive strategies in hybrid animals.
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Affiliation(s)
- Anna Dudzik
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Dmitrij Dedukh
- Laboratory of Non-Mendelian Evolution, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic
| | | | - Beata Rozenblut-Kościsty
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Hanna Rybka
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | | | - Lukáš Choleva
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Maria Ogielska
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Magdalena Chmielewska
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
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Dedukh D, Maslova A, Al-Rikabi A, Padutsch N, Liehr T, Krasikova A. Karyotypes of water frogs from the Pelophylax esculentus complex: results of cross-species chromosomal painting. Chromosoma 2023; 132:329-342. [PMID: 38001396 DOI: 10.1007/s00412-023-00812-8] [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: 08/08/2023] [Revised: 11/01/2023] [Accepted: 11/07/2023] [Indexed: 11/26/2023]
Abstract
Amphibian species have the largest genome size enriched with repetitive sequences and relatively similar karyotypes. Moreover, many amphibian species frequently hybridize causing nuclear and mitochondrial genome introgressions. In addition, hybridization in some amphibian species may lead to clonality and polyploidization. All such events were found in water frogs from the genus Pelophylax. Among the species within the genus Pelophylax, P. esculentus complex is the most widely distributed and well-studied. This complex includes two parental species, P. ridibundus and P. lessonae, and their hybrids, P. esculentus, reproducing hemiclonally. Parental species and their hybrids have similar but slightly polymorphic karyotypes, so their precise identification is still required. Here, we have developed a complete set of 13 chromosome painting probes for two parental species allowing the precise identification of all chromosomes. Applying chromosomal painting, we identified homologous chromosomes in both parental species and orthologous chromosomes in their diploid hemiclonal hybrids. Comparative painting did not reveal interchromosomal exchanges between the studied water frog species and their hybrids. Using cross-specific chromosome painting, we detected unequal distribution of the signals along chromosomes suggesting the presence of species-specific tandem repeats. Application of chromosomal paints to the karyotypes of hybrids revealed differences in the intensity of staining for P. ridibundus and P. lessonae chromosomes. Thus, both parental genomes have a divergence in unique sequences. Obtained chromosome probes may serve as a powerful tool to unravel chromosomal evolution in phylogenetically related species, identify individual chromosomes in different cell types, and investigate the elimination of chromosomes in hybrid water frogs.
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Affiliation(s)
- Dmitrij Dedukh
- Laboratory of Cell Nucleus Structure and Dynamics, Saint-Petersburg State University, Saint-Petersburg, Russia
- Laboratory of Non-Mendelian Evolution, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic
| | - Antonina Maslova
- Laboratory of Cell Nucleus Structure and Dynamics, Saint-Petersburg State University, Saint-Petersburg, Russia
| | - Ahmed Al-Rikabi
- Jena University Hospital, Institute of Human Genetics, Friedrich Schiller University, Jena, Germany
| | - Niklas Padutsch
- Jena University Hospital, Institute of Human Genetics, Friedrich Schiller University, Jena, Germany
| | - Thomas Liehr
- Jena University Hospital, Institute of Human Genetics, Friedrich Schiller University, Jena, Germany
| | - Alla Krasikova
- Laboratory of Cell Nucleus Structure and Dynamics, Saint-Petersburg State University, Saint-Petersburg, Russia.
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4
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Chmielewska M, Kaźmierczak M, Rozenblut-Kościsty B, Kolenda K, Dudzik A, Dedukh D, Ogielska M. Genome elimination from the germline cells in diploid and triploid male water frogs Pelophylax esculentus. Front Cell Dev Biol 2022; 10:1008506. [PMID: 36313575 PMCID: PMC9615423 DOI: 10.3389/fcell.2022.1008506] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 08/31/2022] [Indexed: 11/18/2022] Open
Abstract
Hybridogenesis is a hemiclonal reproductive strategy in diploid and triploid hybrids. Our study model is a frog P. esculentus (diploid RL and triploids RLL and RRL), a natural hybrid between P. lessonae (LL) and P. ridibundus (RR). Hybridogenesis relies on elimination of one genome (L or R) from gonocytes (G) in tadpole gonads during prespermatogenesis, but not from spermatogonial stem cells (SSCs) in adults. Here we provide the first comprehensive study of testis morphology combined with chromosome composition in the full spectrum of spermatogenic cells. Using genomic in situ hybridization (GISH) and FISH we determined genomes in metaphase plates and interphase nuclei in Gs and SSCs. We traced genomic composition of SSCs, spermatocytes and spermatozoa in individual adult males that were crossed with females of the parental species and gave progeny. Degenerating gonocytes (24%–39%) and SSCs (18%–20%) led to partial sterility of juvenile and adult gonads. We conclude that elimination and endoreplication not properly completed during prespermatogenesis may be halted when gonocytes become dormant in juveniles. After resumption of mitotic divisions by SSCs in adults, these 20% of cells with successful genome elimination and endoreplication continue spermatogenesis, while in about 80% spermatogenesis is deficient. Majority of abnormal cells are eliminated by cell death, however some of them give rise to aneuploid spermatocytes and spermatozoa which shows that hybridogenesis is a wasteful process.
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Affiliation(s)
- Magdalena Chmielewska
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
- *Correspondence: Magdalena Chmielewska,
| | - Mikołaj Kaźmierczak
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
- Department of Medicine Biology, The Cardinal Wyszyński National Institute of Cardiology, Warsaw, Poland
| | - Beata Rozenblut-Kościsty
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Krzysztof Kolenda
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Anna Dudzik
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
| | - Dmitrij Dedukh
- Laboratory of Non-Mendelian Evolution, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic
| | - Maria Ogielska
- Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
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Pustovalova E, Choleva L, Shabanov D, Dedukh D. The high diversity of gametogenic pathways in amphispermic water frog hybrids from Eastern Ukraine. PeerJ 2022; 10:e13957. [PMID: 36032956 PMCID: PMC9415524 DOI: 10.7717/peerj.13957] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 08/06/2022] [Indexed: 01/20/2023] Open
Abstract
Interspecific hybridization can disrupt canonical gametogenic pathways, leading to the emergence of clonal and hemiclonal organisms. Such gametogenic alterations usually include genome endoreplication and/or premeiotic elimination of one of the parental genomes. The hybrid frog Pelophylax esculentus exploits genome endoreplication and genome elimination to produce haploid gametes with chromosomes of only one parental species. To reproduce, hybrids coexist with one of the parental species and form specific population systems. Here, we investigated the mechanism of spermatogenesis in diploid P. esculentus from sympatric populations of P. ridibundus using fluorescent in situ hybridization. We found that the genome composition and ploidy of germ cells, meiotic cells, and spermatids vary among P. esculentus individuals. The spermatogenic patterns observed in various hybrid males suggest the occurrence of at least six diverse germ cell populations, each with a specific premeiotic genome elimination and endoreplication pathway. Besides co-occurring aberrant cells detected during meiosis and gamete aneuploidy, alterations in genome duplication and endoreplication have led to either haploid or diploid sperm production. Diploid P. esculentus males from mixed populations of P. ridibundus rarely follow classical hybridogenesis. Instead, hybrid males simultaneously produce gametes with different genome compositions and ploidy levels. The persistence of the studied mixed populations highly relies on gametes containing a genome of the other parental species, P. lessonae.
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Affiliation(s)
- Eleonora Pustovalova
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the CAS, v.v.i., Libechov, Czech Republic,Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic,Laboratory of Amphibian Population Ecology, Department of Zoology and Animal Ecology, School of Biology, V. N. Karazin Kharkiv National University, Kharkiv, Ukraine
| | - Lukaš Choleva
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the CAS, v.v.i., Libechov, Czech Republic,Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Dmytro Shabanov
- Laboratory of Amphibian Population Ecology, Department of Zoology and Animal Ecology, School of Biology, V. N. Karazin Kharkiv National University, Kharkiv, Ukraine
| | - Dmitrij Dedukh
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the CAS, v.v.i., Libechov, Czech Republic
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6
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Dedukh D, Altmanová M, Klíma J, Kratochvíl L. Premeiotic endoreplication is essential for obligate parthenogenesis in geckos. Development 2022; 149:274975. [PMID: 35388415 DOI: 10.1242/dev.200345] [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: 11/08/2021] [Accepted: 03/08/2022] [Indexed: 02/05/2023]
Abstract
Obligate parthenogenesis evolved in reptiles convergently several times, mainly through interspecific hybridization. The obligate parthenogenetic complexes typically include both diploid and triploid lineages. Offspring of parthenogenetic hybrids are genetic copies of their mother; however, the cellular mechanism enabling the production of unreduced cells is largely unknown. Here, we show that oocytes go through meiosis in three widespread, or even strongly invasive, obligate parthenogenetic complexes of geckos, namely in diploid and triploid Lepidodactylus lugubris, and triploid Hemiphyllodactylus typus and Heteronotia binoei. In all four lineages, the majority of oocytes enter the pachytene at the original ploidy level, but their chromosomes cannot pair properly and instead form univalents, bivalents and multivalents. Unreduced eggs with clonally inherited genomes are formed from germ cells that had undergone premeiotic endoreplication, in which appropriate segregation is ensured by the formation of bivalents made from copies of identical chromosomes. We conclude that the induction of premeiotic endoreplication in reptiles was independently co-opted at least four times as an essential component of parthenogenetic reproduction and that this mechanism enables the emergence of fertile polyploid lineages within parthenogenetic complexes.
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Affiliation(s)
- Dmitrij Dedukh
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21, Liběchov, Czech Republic
| | - Marie Altmanová
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21, Liběchov, Czech Republic.,Department of Ecology, Faculty of Science, Charles University, Viničná 7, 128 44, Prague, Czech Republic
| | - Jiří Klíma
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21, Liběchov, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, 128 44, Prague, Czech Republic
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7
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Dedukh D, Marta A, Janko K. Challenges and Costs of Asexuality: Variation in Premeiotic Genome Duplication in Gynogenetic Hybrids from Cobitis taenia Complex. Int J Mol Sci 2021; 22:ijms222212117. [PMID: 34830012 PMCID: PMC8622741 DOI: 10.3390/ijms222212117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/25/2021] [Accepted: 11/04/2021] [Indexed: 02/07/2023] Open
Abstract
The transition from sexual reproduction to asexuality is often triggered by hybridization. The gametogenesis of many hybrid asexuals involves premeiotic genome endoreplication leading to bypass hybrid sterility and forming clonal gametes. However, it is still not clear when endoreplication occurs, how many gonial cells it affects and whether its rate differs among clonal lineages. Here, we investigated meiotic and premeiotic cells of diploid and triploid hybrids of spined loaches (Cypriniformes: Cobitis) that reproduce by gynogenesis. We found that in naturally and experimentally produced F1 hybrids asexuality is achieved by genome endoreplication, which occurs in gonocytes just before entering meiosis or, rarely, one or a few divisions before meiosis. However, genome endoreplication was observed only in a minor fraction of the hybrid's gonocytes, while the vast majority of gonocytes were unable to duplicate their genomes and consequently could not proceed beyond pachytene due to defects in bivalent formation. We also noted that the rate of endoreplication was significantly higher among gonocytes of hybrids from natural clones than of experimentally produced F1 hybrids. Thus, asexuality and hybrid sterility are intimately related phenomena and the transition from sexual reproduction to asexuality must overcome significant problems with genome incompatibilities with a possible impact on reproductive potential.
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Affiliation(s)
- Dmitrij Dedukh
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the CAS, Rumburská 89, 277 21 Liběchov, Czech Republic;
- Correspondence: (D.D.); (K.J.)
| | - Anatolie Marta
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the CAS, Rumburská 89, 277 21 Liběchov, Czech Republic;
- Department of Zoology, Faculty of Science, Charles University in Prague, 128 00 Prague, Czech Republic
- Institute of Zoology, MD-2028, Academiei 1, 2001 Chisinau, Moldova
| | - Karel Janko
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the CAS, Rumburská 89, 277 21 Liběchov, Czech Republic;
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00 Ostrava, Czech Republic
- Correspondence: (D.D.); (K.J.)
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8
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Majtánová Z, Dedukh D, Choleva L, Adams M, Ráb P, Unmack PJ, Ezaz T. Uniparental Genome Elimination in Australian Carp Gudgeons. Genome Biol Evol 2021; 13:6137838. [PMID: 33591327 PMCID: PMC8245195 DOI: 10.1093/gbe/evab030] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2021] [Indexed: 12/15/2022] Open
Abstract
Metazoans usually reproduce sexually, blending the unique identity of parental genomes for the next generation through functional crossing-over and recombination in meiosis. However, some metazoan lineages have evolved reproductive systems where offspring are either full (clonal) or partial (hemiclonal) genetic replicas. In the latter group, the process of uniparental genome elimination selectively eliminates either the maternal or paternal genome from germ cells, and only one parental genome is selected for transmission. Although fairly common in plants, hybridogenesis (i.e., clonal haploidization via chromosome elimination) remains a poorly understood process in animals. Here, we explore the proximal cytogenomic mechanisms of somatic and germ cell chromosomes in sexual and hybrid genotypes of Australian carp gudgeons (Hypseleotris) by tracing the fate of each set during mitosis (in somatic tissues) and meiosis (in gonads). Our comparative study of diploid hybrid and sexual individuals revealed visually functional gonads in male and female hybrid genotypes and generally high karyotype variability, although the number of chromosome arms remains constant. Our results delivered direct evidence for classic hybridogenesis as a reproductive mode in carp gudgeons. Two parental sets with integral structure in the hybrid soma (the F1 constitution) contrasted with uniparental chromosomal inheritance detected in gonads. The inheritance mode happens through premeiotic genome duplication of the parental genome to be transmitted, whereas the second parental genome is likely gradually eliminated already in juvenile individuals. The role of metacentric chromosomes in hybrid evolution is also discussed.
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Affiliation(s)
- Zuzana Majtánová
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic
| | - Dmitrij Dedukh
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic
| | - Lukáš Choleva
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic.,Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Mark Adams
- Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide, SA, Australia.,School of Biological Sciences, The University of Adelaide, SA, Australia
| | - Petr Ráb
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic
| | - Peter J Unmack
- Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, ACT, Australia
| | - Tariq Ezaz
- Centre for Conservation Ecology and Genetics, Institute for Applied Ecology, University of Canberra, ACT, Australia
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9
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Lukhtanov VA, Dincă V, Friberg M, Vila R, Wiklund C. Incomplete Sterility of Chromosomal Hybrids: Implications for Karyotype Evolution and Homoploid Hybrid Speciation. Front Genet 2020; 11:583827. [PMID: 33193715 PMCID: PMC7594530 DOI: 10.3389/fgene.2020.583827] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/14/2020] [Indexed: 11/17/2022] Open
Abstract
Heterozygotes for major chromosomal rearrangements such as fusions and fissions are expected to display a high level of sterility due to problems during meiosis. However, some species, especially plants and animals with holocentric chromosomes, are known to tolerate chromosomal heterozygosity even for multiple rearrangements. Here, we studied male meiotic chromosome behavior in four hybrid generations (F1–F4) between two chromosomal races of the Wood White butterfly Leptidea sinapis differentiated by at least 24 chromosomal fusions/fissions. Previous work showed that these hybrids were fertile, although their fertility was reduced as compared to crosses within chromosomal races. We demonstrate that (i) F1 hybrids are highly heterozygous with nearly all chromosomes participating in the formation of trivalents at the first meiotic division, and (ii) that from F1 to F4 the number of trivalents decreases and the number of bivalents increases. We argue that the observed process of chromosome sorting would, if continued, result in a new homozygous chromosomal race, i.e., in a new karyotype with intermediate chromosome number and, possibly, in a new incipient homoploid hybrid species. We also discuss the segregational model of karyotype evolution and the chromosomal model of homoploid hybrid speciation.
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Affiliation(s)
- Vladimir A Lukhtanov
- Department of Karyosystematics, Zoological Institute of Russian Academy of Sciences, Saint Petersburg, Russia
| | - Vlad Dincă
- Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland.,Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Spain
| | - Magne Friberg
- Biodiversity Unit, Department of Biology, Lund University, Lund, Sweden
| | - Roger Vila
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Spain
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10
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Wang J, Veronezi GMB, Kang Y, Zagoskin M, O'Toole ET, Davis RE. Comprehensive Chromosome End Remodeling during Programmed DNA Elimination. Curr Biol 2020; 30:3397-3413.e4. [PMID: 32679104 PMCID: PMC7484210 DOI: 10.1016/j.cub.2020.06.058] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/09/2020] [Accepted: 06/16/2020] [Indexed: 01/14/2023]
Abstract
Germline and somatic genomes are in general the same in a multicellular organism. However, programmed DNA elimination leads to a reduced somatic genome compared to germline cells. Previous work on the parasitic nematode Ascaris demonstrated that programmed DNA elimination encompasses high-fidelity chromosomal breaks and loss of specific genome sequences including a major tandem repeat of 120 bp and ~1,000 germline-expressed genes. However, the precise chromosomal locations of these repeats, breaks regions, and eliminated genes remained unknown. We used PacBio long-read sequencing and chromosome conformation capture (Hi-C) to obtain fully assembled chromosomes of Ascaris germline and somatic genomes, enabling a complete chromosomal view of DNA elimination. We found that all 24 germline chromosomes undergo comprehensive chromosome end remodeling with DNA breaks in their subtelomeric regions and loss of distal sequences including the telomeres at both chromosome ends. All new Ascaris somatic chromosome ends are recapped by de novo telomere healing. We provide an ultrastructural analysis of Ascaris DNA elimination and show that eliminated DNA is incorporated into double membrane-bound structures, similar to micronuclei, during telophase of a DNA elimination mitosis. These micronuclei undergo dynamic changes including loss of active histone marks and localize to the cytoplasm following daughter nuclei formation and cytokinesis where they form autophagosomes. Comparative analysis of nematode chromosomes suggests that chromosome fusions occurred, forming Ascaris sex chromosomes that become independent chromosomes following DNA elimination breaks in somatic cells. These studies provide the first chromosomal view and define novel features and functions of metazoan programmed DNA elimination.
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Affiliation(s)
- Jianbin Wang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
| | - Giovana M B Veronezi
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Yuanyuan Kang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Maxim Zagoskin
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Eileen T O'Toole
- Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Richard E Davis
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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