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Sullivan W. Remarkable chromosomes and karyotypes: A top 10 list. Mol Biol Cell 2024; 35:pe1. [PMID: 38517328 PMCID: PMC11064663 DOI: 10.1091/mbc.e23-12-0498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/23/2024] [Accepted: 03/01/2024] [Indexed: 03/23/2024] Open
Abstract
Chromosomes and karyotypes are particularly rich in oddities and extremes. Described below are 10 remarkable chromosomes and karyotypes sprinkled throughout the tree of life. These include variants in chromosome number, structure, and dynamics both natural and engineered. This versatility highlights the robustness and tolerance of the mitotic and meiotic machinery to dramatic changes in chromosome and karyotype architecture. These examples also illustrate that the robustness comes at a cost, enabling the evolution of chromosomes that subvert mitosis and meiosis.
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Affiliation(s)
- William Sullivan
- Department of MCD Biology, University of California, Santa Cruz, CA 95064
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Ayarza E, Cavada G, Arévalo T, Molina A, Berríos S. Quantitative analysis of Robertsonian chromosomes inherited by descendants from multiple Rb heterozygotes of Mus m. Domesticus. Front Cell Dev Biol 2022; 10:1050556. [PMID: 36506103 PMCID: PMC9732535 DOI: 10.3389/fcell.2022.1050556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/14/2022] [Indexed: 11/26/2022] Open
Abstract
Robertsonian translocation is the most common chromosomal rearrangement in mammals, and represents the type of chromosomal change that most effectively contributes to speciation in natural populations. Rb translocations involve double-strand DNA breaks at the centromere level in two telocentric chromosomes, followed by repair ligation of the respective long arms, creating a metacentric Rb chromosome. Many different chromosomal races have been described in Mus musculus domesticus that show reduced chromosome numbers due to the presence of Rb metacentric chromosomes. The crossroads between ancestral telocentrics and the new metacentric chromosomes should be resolved in the meiotic cells of the heterozygote individuals, which form trivalents. The preferential segregation of metacentric chromosomes to the egg during female meiosis I has been proposed to favor their fixation and eventual conversion of a telocentric karyotype to a metacentric karyotype. This biased segregation, a form of meiotic drive, explains the karyotype changes in mammalian species that have accumulated Rb fusions. We studied and compared the number of Rb chromosomes inherited by the offspring of multiple Rb heterozygous of M. domesticus in reciprocal crosses. We did not find that the Rb chromosomes were inherited preferentially with respect to the telocentric chromosomes; therefore, we found no evidence for the meiotic drive, nor was there a random distribution of Rb chromosomes inherited by the descendants.
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Affiliation(s)
- Eliana Ayarza
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Gabriel Cavada
- Instituto de Salud Poblacional, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Tamara Arévalo
- Programa Genética Humana, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Alam Molina
- Programa Genética Humana, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Soledad Berríos
- Programa Genética Humana, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile,*Correspondence: Soledad Berríos,
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Al-Yazeedi T, Xu EL, Kaur J, Shakes DC, Pires-daSilva A. Lagging X chromatids specify the orientation of asymmetric organelle partitioning in XX spermatocytes of Auanema rhodensis. Genetics 2022; 222:6762860. [PMID: 36255260 PMCID: PMC9713428 DOI: 10.1093/genetics/iyac159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/13/2022] [Indexed: 12/14/2022] Open
Abstract
The unequal partitioning of molecules and organelles during cell division results in daughter cells with different fates. An extreme example is female meiosis, in which consecutive asymmetric cell divisions give rise to 1 large oocyte and 2 small polar bodies with DNA and minimal cytoplasm. Here, we test the hypothesis that during an asymmetric cell division during spermatogenesis of the nematode Auanema rhodensis, the late segregating X chromatids orient the asymmetric partitioning of cytoplasmic components. In previous studies, the secondary spermatocytes of wild-type XO males were found to divide asymmetrically to generate functional spermatids that inherit components necessary for sperm viability and DNA-containing residual bodies that inherit components to be discarded. Here we extend that analysis to 2 novel contexts. First, the isolation and analysis of a strain of mutant XX pseudomales revealed that such animals have highly variable patterns of X-chromatid segregation. The pattern of late segregating X chromatids nevertheless predicted the orientation of organelle partitioning. Second, while wild-type XX hermaphrodites were known to produce both 1X and 2X sperm, here, we show that spermatocytes within specific spermatogonial clusters exhibit 2 different patterns of X-chromatid segregation that correlate with distinct patterns of organelle partitioning. Together this analysis suggests that A. rhodensis has coopted lagging X chromosomes during anaphase II as a mechanism for determining the orientation of organelle partitioning.
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Affiliation(s)
| | | | - Jasmin Kaur
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Diane C Shakes
- Corresponding author: Department of Biology, William & Mary, Williamsburg, VA 23187, USA. (DCS)
| | - Andre Pires-daSilva
- Corresponding author: School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK (AP-dS)
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Spangenberg V, Losev M, Volkhin I, Smirnova S, Nikitin P, Kolomiets O. DNA Environment of Centromeres and Non-Homologous Chromosomes Interactions in Mouse. Cells 2021; 10:3375. [PMID: 34943883 PMCID: PMC8699862 DOI: 10.3390/cells10123375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 11/16/2022] Open
Abstract
Although the pericentromeric regions of chromosomes that are enriched in tandemly repeated satellite DNA represent a significant part of eukaryotic genomes, they remain understudied, which is mainly due to interdisciplinary knowledge gaps. Recent studies suggest their important role in genome regulation, karyotype stability, and evolution. Thus, the idea of satellite DNA as a junk part of the genome has been refuted. The integration of data regarding molecular composition, chromosome behaviour, and the details of the in situ organization of pericentromeric regions is of great interest. The objective of this work was a cytogenetic analysis of the interactions between pericentromeric regions from non-homologous chromosomes in mouse spermatocytes using immuno-FISH. We analysed two events: the associations between centromeric regions of the X chromosome and autosomes and the associations between the centromeric regions of the autosomal bivalents that form chromocenters. We concluded that the X chromosome forms temporary synaptic associations with different autosomes in early meiotic prophase I, which can normally be found until the pachytene-diplotene, without signs of pachytene arrest. These associations are formed between the satellite-DNA-rich centromeric regions of the X chromosome and different autosomes but do not involve the satellite-DNA-poor centromeric region of the Y chromosome. We suggest the hypothetical model of X chromosome competitive replacement from such associations during synaptic correction. We showed that the centromeric region of the X chromosome in association remains free of γH2Ax-dependent chromatin inactivation, while the Y chromosome is completely inactivated. This finding highlights the predominant role of associations between satellite DNA-rich regions of different chromosomes, including the X chromosome. We suppose that X-autosomal transient associations are a manifestation of an additional synaptic disorder checkpoint. These associations are normally corrected before the late diplotene stage. We revealed that the intense spreading conditions that were applied to the spermatocyte I nuclei did not lead to the destruction of stretched chromatin fibers of elongated chromocenters enriched in satellite DNA. The tight associations that we revealed between the pericentromeric regions of different autosomal bivalents and the X chromosome may represent the basis for a mechanism for maintaining the repeats stability in the autosomes and in the X chromosome. The consequences of our findings are discussed.
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Affiliation(s)
- Victor Spangenberg
- Vavilov Institute of General Genetics, Russian Academy of Sciences, 119991 Moscow, Russia; (M.L.); (I.V.); (S.S.); (P.N.); (O.K.)
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Gil-Fernández A, Ribagorda M, Martín-Ruiz M, López-Jiménez P, Laguna T, Gómez R, Parra MT, Viera A, Veyrunes F, Page J. Meiotic Behavior of Achiasmate Sex Chromosomes in the African Pygmy Mouse Mus mattheyi Offers New Insights into the Evolution of Sex Chromosome Pairing and Segregation in Mammals. Genes (Basel) 2021; 12:1434. [PMID: 34573416 PMCID: PMC8471055 DOI: 10.3390/genes12091434] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 02/07/2023] Open
Abstract
X and Y chromosomes in mammals are different in size and gene content due to an evolutionary process of differentiation and degeneration of the Y chromosome. Nevertheless, these chromosomes usually share a small region of homology, the pseudoautosomal region (PAR), which allows them to perform a partial synapsis and undergo reciprocal recombination during meiosis, which ensures their segregation. However, in some mammalian species the PAR has been lost, which challenges the pairing and segregation of sex chromosomes in meiosis. The African pygmy mouse Mus mattheyi shows completely differentiated sex chromosomes, representing an uncommon evolutionary situation among mouse species. We have performed a detailed analysis of the location of proteins involved in synaptonemal complex assembly (SYCP3), recombination (RPA, RAD51 and MLH1) and sex chromosome inactivation (γH2AX) in this species. We found that neither synapsis nor chiasmata are found between sex chromosomes and their pairing is notably delayed compared to autosomes. Interestingly, the Y chromosome only incorporates RPA and RAD51 in a reduced fraction of spermatocytes, indicating a particular DNA repair dynamic on this chromosome. The analysis of segregation revealed that sex chromosomes are associated until metaphase-I just by a chromatin contact. Unexpectedly, both sex chromosomes remain labelled with γH2AX during first meiotic division. This chromatin contact is probably enough to maintain sex chromosome association up to anaphase-I and, therefore, could be relevant to ensure their reductional segregation. The results presented suggest that the regulation of both DNA repair and epigenetic modifications in the sex chromosomes can have a great impact on the divergence of sex chromosomes and their proper transmission, widening our understanding on the relationship between meiosis and the evolution of sex chromosomes in mammals.
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Affiliation(s)
- Ana Gil-Fernández
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
| | - Marta Ribagorda
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
| | - Marta Martín-Ruiz
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
| | - Pablo López-Jiménez
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
| | - Tamara Laguna
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
| | - Rocío Gómez
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
| | - María Teresa Parra
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
| | - Alberto Viera
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
| | - Frederic Veyrunes
- Institut des Sciences de l’Evolution, ISEM UMR 5554 (CNRS/Université Montpellier/IRD/EPHE), 34090 Montpellier, France;
| | - Jesús Page
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (A.G.-F.); (M.R.); (M.M.-R.); (P.L.-J.); (T.L.); (R.G.); (M.T.P.); (A.V.)
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