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Hockens C, Lorenzi H, Wang TT, Lei EP, Rosin LF. Chromosome segregation during spermatogenesis occurs through a unique center-kinetic mechanism in holocentric moth species. PLoS Genet 2024; 20:e1011329. [PMID: 38913752 DOI: 10.1371/journal.pgen.1011329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 06/03/2024] [Indexed: 06/26/2024] Open
Abstract
Precise regulation of chromosome dynamics in the germline is essential for reproductive success across species. Yet, the mechanisms underlying meiotic chromosomal events such as homolog pairing and chromosome segregation are not fully understood in many species. Here, we employ Oligopaint DNA FISH to investigate mechanisms of meiotic homolog pairing and chromosome segregation in the holocentric pantry moth, Plodia interpunctella, and compare our findings to new and previous studies in the silkworm moth, Bombyx mori, which diverged from P. interpunctella over 100 million years ago. We find that pairing in both Bombyx and Plodia spermatogenesis is initiated at gene-rich chromosome ends. Additionally, both species form rod shaped cruciform-like bivalents at metaphase I. However, unlike the telomere-oriented chromosome segregation mechanism observed in Bombyx, Plodia can orient bivalents in multiple different ways at metaphase I. Surprisingly, in both species we find that kinetochores consistently assemble at non-telomeric loci toward the centers of chromosomes regardless of where chromosome centers are located in the bivalent. Additionally, sister kinetochores do not seem to be paired in these species. Instead, four distinct kinetochores are easily observed at metaphase I. Despite this, we find clear end-on microtubule attachments and not lateral microtubule attachments connecting these separated kinetochores to the meiotic spindle. These findings challenge the classical view of segregation where paired, poleward-facing kinetochores are required for accurate homolog separation in meiosis I. Our studies here highlight the importance of exploring fundamental processes in non-model systems, as employing novel organisms can lead to the discovery of novel biology.
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Affiliation(s)
- Clio Hockens
- Unit on Chromosome Dynamics, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hernan Lorenzi
- TriLab Bioinformatics Group, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tricia T Wang
- Unit on Chromosome Dynamics, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Elissa P Lei
- Nuclear Organization and Gene Expression Section; Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Leah F Rosin
- Unit on Chromosome Dynamics, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
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Boman J, Wiklund C, Vila R, Backström N. Meiotic drive against chromosome fusions in butterfly hybrids. Chromosome Res 2024; 32:7. [PMID: 38702576 PMCID: PMC11068667 DOI: 10.1007/s10577-024-09752-0] [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: 02/02/2024] [Revised: 04/21/2024] [Accepted: 04/30/2024] [Indexed: 05/06/2024]
Abstract
Species frequently differ in the number and structure of chromosomes they harbor, but individuals that are heterozygous for chromosomal rearrangements may suffer from reduced fitness. Chromosomal rearrangements like fissions and fusions can hence serve as a mechanism for speciation between incipient lineages, but their evolution poses a paradox. How can rearrangements get fixed between populations if heterozygotes have reduced fitness? One solution is that this process predominantly occurs in small and isolated populations, where genetic drift can override natural selection. However, fixation is also more likely if a novel rearrangement is favored by a transmission bias, such as meiotic drive. Here, we investigate chromosomal transmission distortion in hybrids between two wood white (Leptidea sinapis) butterfly populations with extensive karyotype differences. Using data from two different crossing experiments, we uncover that there is a transmission bias favoring the ancestral chromosomal state for derived fusions, a result that shows that chromosome fusions actually can fix in populations despite being counteracted by meiotic drive. This means that meiotic drive not only can promote runaway chromosome number evolution and speciation, but also that it can be a conservative force acting against karyotypic change and the evolution of reproductive isolation. Based on our results, we suggest a mechanistic model for why chromosome fusion mutations may be opposed by meiotic drive and discuss factors contributing to karyotype evolution in Lepidoptera.
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Affiliation(s)
- Jesper Boman
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden.
| | - Christer Wiklund
- Department of Zoology: Division of Ecology, Stockholm University, Stockholm, Sweden
| | - Roger Vila
- Institut de Biologia Evolutiva (CSIC-Univ. Pompeu Fabra), Passeig Marítim de La Barceloneta 37-49, 08003, Barcelona, Spain
| | - Niclas Backström
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
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Gerton JL. A working model for the formation of Robertsonian chromosomes. J Cell Sci 2024; 137:jcs261912. [PMID: 38606789 PMCID: PMC11057876 DOI: 10.1242/jcs.261912] [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] [Indexed: 04/13/2024] Open
Abstract
Robertsonian chromosomes form by fusion of two chromosomes that have centromeres located near their ends, known as acrocentric or telocentric chromosomes. This fusion creates a new metacentric chromosome and is a major mechanism of karyotype evolution and speciation. Robertsonian chromosomes are common in nature and were first described in grasshoppers by the zoologist W. R. B. Robertson more than 100 years ago. They have since been observed in many species, including catfish, sheep, butterflies, bats, bovids, rodents and humans, and are the most common chromosomal change in mammals. Robertsonian translocations are particularly rampant in the house mouse, Mus musculus domesticus, where they exhibit meiotic drive and create reproductive isolation. Recent progress has been made in understanding how Robertsonian chromosomes form in the human genome, highlighting some of the fundamental principles of how and why these types of fusion events occur so frequently. Consequences of these fusions include infertility and Down's syndrome. In this Hypothesis, I postulate that the conditions that allow these fusions to form are threefold: (1) sequence homology on non-homologous chromosomes, often in the form of repetitive DNA; (2) recombination initiation during meiosis; and (3) physical proximity of the homologous sequences in three-dimensional space. This Hypothesis highlights the latest progress in understanding human Robertsonian translocations within the context of the broader literature on Robertsonian chromosomes.
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Nazari V, Lukhtanov VA, Naderi A, Fric ZF, Dincă V, Vila R. More hidden diversity in a cryptic species complex: a new subspecies of Leptideasinapis (Lepidoptera, Pieridae) from Northern Iran. COMPARATIVE CYTOGENETICS 2023; 17:113-128. [PMID: 37304150 PMCID: PMC10252139 DOI: 10.3897/compcytogen.17.102830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 04/05/2023] [Indexed: 06/13/2023]
Abstract
A new subspecies of Leptideasinapis from Northern Iran, discovered by means of DNA barcoding, is described as Leptideasinapistabarestanassp. nov. The new subspecies is allopatric with respect to other populations of L.sinapis and is genetically distinct, appearing as a well-supported sister clade to all other populations in COI-based phylogenetic reconstructions. Details on karyotype, genitalia, ecology and behaviour for the new subspecies are given and a biogeographical speciation scenario is proposed.
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Affiliation(s)
- Vazrick Nazari
- Department of Biology, University of Padova, Padova, ItalyUniversity of PadovaPadovaItaly
| | - Vladimir A. Lukhtanov
- Department of Karyosystematics, Zoological Institute of Russian Academy of Science, Universitetskaya nab. 1, 199034 St. Petersburg, RussiaZoological Institute of Russian Academy of ScienceSt. PetersburgRussia
| | - Alireza Naderi
- National Natural History Museum & Genetic Resources, Tehran, IranNational Natural History Museum & Genetic ResourcesTehranIran
| | - Zdenek Faltýnek Fric
- Department of Biodiversity and Conservation Biology, Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech RepublicInstitute of Entomology, Biology Centre of the Czech Academy of SciencesČeské BudějoviceCzech Republic
| | - Vlad Dincă
- Ecology and Genetics Research Unit, University of Oulu, Oulu, FinlandUniversity of OuluOuluFinland
- Research Institute of the University of Bucharest (ICUB), University of Bucharest, Bucharest, RomaniaUniversity of BucharestBucharestRomania
| | - Roger Vila
- Institut de Biologia Evolutiva (CSIC – Universitat Pompeu Fabra), Barcelona, SpainUniversitat Pompeu FabraBarcelonaSpain
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Pazhenkova EA, Lukhtanov VA. Whole-Genome Analysis Reveals the Dynamic Evolution of Holocentric Chromosomes in Satyrine Butterflies. Genes (Basel) 2023; 14:437. [PMID: 36833364 PMCID: PMC9956908 DOI: 10.3390/genes14020437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/01/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Butterfly chromosomes are holocentric, i.e., lacking a localized centromere. Potentially, this can lead to rapid karyotypic evolution through chromosome fissions and fusions, since fragmented chromosomes retain kinetic activity, while fused chromosomes are not dicentric. However, the actual mechanisms of butterfly genome evolution are poorly understood. Here, we analyzed chromosome-scale genome assemblies to identify structural rearrangements between karyotypes of satyrine butterfly species. For the species pair Erebia ligea-Maniola jurtina, sharing the ancestral diploid karyotype 2n = 56 + ZW, we demonstrate a high level of chromosomal macrosynteny and nine inversions separating these species. We show that the formation of a karyotype with a low number of chromosomes (2n = 36 + ZW) in Erebia aethiops was based on ten fusions, including one autosome-sex chromosome fusion, resulting in a neo-Z chromosome. We also detected inversions on the Z sex chromosome that were differentially fixed between the species. We conclude that chromosomal evolution is dynamic in the satyrines, even in the lineage that preserves the ancestral chromosome number. We hypothesize that the exceptional role of Z chromosomes in speciation may be further enhanced by inversions and sex chromosome-autosome fusions. We argue that not only fusions/fissions but also inversions are drivers of the holocentromere-mediated mode of chromosomal speciation.
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Affiliation(s)
- Elena A. Pazhenkova
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Vladimir A. Lukhtanov
- Department of Karyosystematics, Zoological Institute of Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, Russia
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Lukhtanov VA, Dantchenko AV, Balayan KV, Gagarina AV. Karyotype and DNA barcode of Polyommatus ( Agrodiaetus) cyaneus (Staudinger, 1899) from its type locality: implication for taxonomic and evolutionary research in Polyommatus blue butterflies (Lepidoptera, Lycaenidae). COMPARATIVE CYTOGENETICS 2020; 14:567-575. [PMID: 33244355 PMCID: PMC7686216 DOI: 10.3897/compcytogen.v14i4.59574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 11/10/2020] [Indexed: 06/11/2023]
Abstract
Chromosomal and molecular analyses of rapidly evolving organisms such as Polyommatus Latreille, 1804 blue butterflies are essential for understanding their taxonomy and evolutionary history, and the studies of populations from their type localities are crucially important for resolving problems of nomenclature and species identity. Here we present data on the topotypical population of the blue butterfly species described as Lycaena damone var. cyanea Staudinger, 1899. This taxon was described from Khankendi (Nagorno-Karabakh, Caucasus), and rediscovered at the type locality for the first time since it was collected there in 1869. The specimens were found on dry stony meadows with a predominance of Onobrychis radiata Bieberstein, 1810, on upper border of oak forests. Their haploid chromosome number (n) was established as n = 17. Chromosomal and mitochondrial DNA barcode analyses of the studied samples from type-locality provided an opportunity for the critical taxonomic re-examination of Caucasian species of the subgenus Agrodiaetus Hübner, 1822 of the genus Polyommatus Latreille, 1804. The obtained data support the interpretation of the P. (A.) cyaneus (Staudinger, 1899) and P. (A.) carmon (Herrich-Schäffer, 1851) as two different, not closely related species complexes as previously hypothesized by Hugo de Lesse. On the contrary, the treatment by Walter Forster who considered these taxa as two groups of conspecific populations was not supported by our data.
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Affiliation(s)
- Vladimir A. Lukhtanov
- Department of Karyosystematics, Zoological Institute of the Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, RussiaZoological Institute, Russian Academy of SciencesSt. PetersburgRussia
| | - Alexander V. Dantchenko
- Department of Karyosystematics, Zoological Institute of the Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, RussiaZoological Institute, Russian Academy of SciencesSt. PetersburgRussia
- Faculty of Chemistry, Lomonosov Moscow State University, GSP-1, Leninskiye Gory 1/11, Moscow119991, RussiaLomonosov Moscow State UniversityMoscowRussia
| | - Karine V. Balayan
- Yerevan Botanical Garden of the Institute of Botany of the NAS RA, Acharyan str. 1, Yerevan 0040, ArmeniaInstitute of Botany, NAS RAYerevanArmenia
| | - Anastasia V. Gagarina
- Department of Karyosystematics, Zoological Institute of the Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, RussiaZoological Institute, Russian Academy of SciencesSt. PetersburgRussia
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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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