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Olaya I, Burgess SM, Rog O. Formation and resolution of meiotic chromosome entanglements and interlocks. J Cell Sci 2024; 137:jcs262004. [PMID: 38985540 PMCID: PMC11267460 DOI: 10.1242/jcs.262004] [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: 07/12/2024] Open
Abstract
Interactions between parental chromosomes during the formation of gametes can lead to entanglements, entrapments and interlocks between unrelated chromosomes. If unresolved, these topological constraints can lead to misregulation of exchanges between chromosomes and to chromosome mis-segregation. Interestingly, these configurations are largely resolved by the time parental chromosomes are aligned during pachytene. In this Review, we highlight the inevitability of topologically complex configurations and discuss possible mechanisms to resolve them. We focus on the dynamic nature of a conserved chromosomal interface - the synaptonemal complex - and the chromosome movements that accompany meiosis as potential mechanisms to resolve topological constraints. We highlight the advantages of the nematode Caenorhabditis elegans for understanding biophysical features of the chromosome axis and synaptonemal complex that could contribute to mechanisms underlying interlock resolution. In addition, we highlight advantages of using the zebrafish, Danio rerio, as a model to understand how entanglements and interlocks are avoided and resolved.
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Affiliation(s)
- Iván Olaya
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
- Integrative Genetics and Genomics Graduate Group, University of California Davis, Davis, CA 95616, USA
| | - Sean M. Burgess
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
| | - Ofer Rog
- School of Biological Sciences and Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA
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Xiang Y, Tsuchiya D, Yu Z, Zhao X, McKinney S, Unruh J, Slaughter B, Lake CM, Hawley RS. Multiple reorganizations of the lateral elements of the synaptonemal complex facilitate homolog segregation in Bombyx mori oocytes. Curr Biol 2024; 34:352-360.e4. [PMID: 38176417 DOI: 10.1016/j.cub.2023.12.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/29/2023] [Accepted: 12/07/2023] [Indexed: 01/06/2024]
Abstract
Although Lepidopteran females build a synaptonemal complex (SC) in pachytene, homologs do not crossover, necessitating an alternative method of homolog conjunction. In Bombyx mori oocytes, the SC breaks down at the end of pachytene, and homolog associations are maintained by a large oocyte-specific structure, which we call the bivalent bridge (BB), connecting paired homologs. The BB is derived from at least some components of the SC lateral elements (LEs). It contains the HORMAD protein HOP1 and the LE protein SYCP2 and is formed by the fusion of the two LE derivatives. As diplotene progresses, the BB increases in width and acquires a layered structure with a thick band of HOP1 separating two layers of SYCP2. The HOP1 interacting protein, PCH2, joins the BB in mid-diplotene, and by late-diplotene, it lies in the middle of the HOP1 filament. This structure is maintained through metaphase I. SYCP2 and PCH2 are lost at anaphase I, and the BB no longer connects the separating homologs. However, a key component of the BB, HOP1, remains at the metaphase I plate. These changes in organization of the BB occur simultaneously with the movement of the kinetochore protein, DSN1, from within the BB at mid-diplotene to the edge of the homologs facing the poles by metaphase I. We view these data in context of models in which SC components and regulators can be repurposed to achieve different functions, a fascinating example of evolution achieving homolog conjunction in an alternative way with recycling of SC proteins.
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Affiliation(s)
- Youbin Xiang
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - Dai Tsuchiya
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - Zulin Yu
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - Xia Zhao
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - Sean McKinney
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - Jay Unruh
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - Brian Slaughter
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - Cathleen M Lake
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA
| | - R Scott Hawley
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, MO 66160, USA.
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Rosin LF, Gil J, Drinnenberg IA, Lei EP. Oligopaint DNA FISH reveals telomere-based meiotic pairing dynamics in the silkworm, Bombyx mori. PLoS Genet 2021; 17:e1009700. [PMID: 34319984 PMCID: PMC8351950 DOI: 10.1371/journal.pgen.1009700] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/09/2021] [Accepted: 07/07/2021] [Indexed: 12/04/2022] Open
Abstract
Accurate chromosome segregation during meiosis is essential for reproductive success. Yet, many fundamental aspects of meiosis remain unclear, including the mechanisms regulating homolog pairing across species. This gap is partially due to our inability to visualize individual chromosomes during meiosis. Here, we employ Oligopaint FISH to investigate homolog pairing and compaction of meiotic chromosomes and resurrect a classical model system, the silkworm Bombyx mori. Our Oligopaint design combines multiplexed barcoding with secondary oligo labeling for high flexibility and low cost. These studies illustrate that Oligopaints are highly specific in whole-mount gonads and on meiotic squashes. We show that meiotic pairing is robust in both males and females and that pairing can occur through numerous partially paired intermediate structures. We also show that pairing in male meiosis occurs asynchronously and seemingly in a transcription-biased manner. Further, we reveal that meiotic bivalent formation in B. mori males is highly similar to bivalent formation in C. elegans, with both of these pathways ultimately resulting in the pairing of chromosome ends with non-paired ends facing the spindle pole. Additionally, microtubule recruitment in both C. elegans and B. mori is likely dependent on kinetochore proteins but independent of the centromere-specifying histone CENP-A. Finally, using super-resolution microscopy in the female germline, we show that homologous chromosomes remain associated at telomere domains in the absence of chiasma and after breakdown and modification to the synaptonemal complex in pachytene. These studies reveal novel insights into mechanisms of meiotic homolog pairing both with or without recombination.
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Affiliation(s)
- Leah F. Rosin
- 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
| | - Jose Gil
- Institut Curie, PSL Research University, CNRS, Paris, France; Sorbonne Université, Institut Curie, CNRS, Paris, France
| | - Ines A. Drinnenberg
- Institut Curie, PSL Research University, CNRS, Paris, France; Sorbonne Université, Institut Curie, CNRS, Paris, France
| | - 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
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Abstract
Recombination and pairing are prominent features of meiosis where they play an important role in increasing genetic diversity. In most organisms recombination also plays mechanical roles in mediating pairing of homologous chromosomes during prophase and in ensuring regular segregation of homologous pairs at the first meiotic division. The laboratory directed by D. von Wettstein identified six key steps in the meiotic process: (1) Recombination mediated processes occur in physical and functional linkage with the synaptonemal complex (SC), a highly conserved, meiosis-specific structure that links homologous axes along their lengths. (2) The pairing process involves formation and resolution of chromosomal entanglements/interlockings. (3) The SC normally forms specifically between homologous chromosomes, but in unusual situations can form between nonhomologous chromosomes or regions resulting in two-phase SC formation. (4) In hexaploid common wheat, extensive multivalents form with multiple, pairing partner shifts, indicating homology recognition and SC formation among homoeologs as well as homologs. (5) Linkage between recombination and the SC is revealed by crossover-correlated nodules localized in the SC central region. (6) Modified SCs sometimes play a direct role in homolog segregation, providing the required connection between homologs in absence of crossovers/chiasmata.
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Harris SE, Braselton JP, Miller CE. Chromosomal Number ofSorosphaera Veronicae(Plasmodiophoromycetes) Based on Ultrastructural Analysis of Synaptonemal Complexes. Mycologia 2018. [DOI: 10.1080/00275514.1980.12021267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Hernández-Hernández A, Masich S, Fukuda T, Kouznetsova A, Sandin S, Daneholt B, Höög C. The central element of the synaptonemal complex in mice is organized as a bilayered junction structure. J Cell Sci 2016; 129:2239-49. [PMID: 27103161 DOI: 10.1242/jcs.182477] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 04/14/2016] [Indexed: 01/25/2023] Open
Abstract
The synaptonemal complex transiently stabilizes pairing interactions between homologous chromosomes during meiosis. Assembly of the synaptonemal complex is mediated through integration of opposing transverse filaments into a central element, a process that is poorly understood. We have, here, analyzed the localization of the transverse filament protein SYCP1 and the central element proteins SYCE1, SYCE2 and SYCE3 within the central region of the synaptonemal complex in mouse spermatocytes using immunoelectron microscopy. Distribution of immuno-gold particles in a lateral view of the synaptonemal complex, supported by protein interaction data, suggest that the N-terminal region of SYCP1 and SYCE3 form a joint bilayered central structure, and that SYCE1 and SYCE2 localize in between the two layers. We find that disruption of SYCE2 and TEX12 (a fourth central element protein) localization to the central element abolishes central alignment of the N-terminal region of SYCP1. Thus, our results show that all four central element proteins, in an interdependent manner, contribute to stabilization of opposing N-terminal regions of SYCP1, forming a bilayered transverse-filament-central-element junction structure that promotes synaptonemal complex formation and synapsis.
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Affiliation(s)
| | - Sergej Masich
- Department of Cell and Molecular Biology, Karolinska Institutet Berzelius väg 35, Stockholm 171 77, Sweden
| | - Tomoyuki Fukuda
- Department of Cell and Molecular Biology, Karolinska Institutet Berzelius väg 35, Stockholm 171 77, Sweden Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Anna Kouznetsova
- Department of Cell and Molecular Biology, Karolinska Institutet Berzelius väg 35, Stockholm 171 77, Sweden
| | - Sara Sandin
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Bertil Daneholt
- Department of Cell and Molecular Biology, Karolinska Institutet Berzelius väg 35, Stockholm 171 77, Sweden
| | - Christer Höög
- Department of Cell and Molecular Biology, Karolinska Institutet Berzelius väg 35, Stockholm 171 77, Sweden
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Zabelina V, Klymenko V, Tamura T, Doroshenko K, Liang H, Sezutsu H, Sehnal F. Genome engineering and parthenocloning in the silkworm, Bombyx mori. J Biosci 2015; 40:645-55. [DOI: 10.1007/s12038-015-9548-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Synaptonemal complex extension from clustered telomeres mediates full-length chromosome pairing in Schmidtea mediterranea. Proc Natl Acad Sci U S A 2014; 111:E5159-68. [PMID: 25404302 DOI: 10.1073/pnas.1420287111] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the 1920s, József Gelei proposed that chromosome pairing in flatworms resulted from the formation of a telomere bouquet followed by the extension of synapsis from telomeres at the base of the bouquet, thus facilitating homolog pairing in a processive manner. A modern interpretation of Gelei's model postulates that the synaptonemal complex (SC) is nucleated close to the telomeres and then extends progressively along the full length of chromosome arms. We used the easily visible meiotic chromosomes, a well-characterized genome, and RNAi in the sexual biotype of the planarian Schmidtea mediterranea to test that hypothesis. By identifying and characterizing S. mediterranea homologs of genes encoding synaptonemal complex protein 1 (SYCP1), the topoisomerase-like protein SPO11, and RAD51, a key player in homologous recombination, we confirmed that SC formation begins near the telomeres and progresses along chromosome arms during zygotene. Although distal regions pair at the time of bouquet formation, pairing of a unique interstitial locus is not observed until the formation of full-length SC at pachytene. Moreover, neither full extension of the SC nor homologous pairing is dependent on the formation of double-strand breaks. These findings validate Gelei's speculation that full-length pairing of homologous chromosomes is mediated by the extension of the SC formed near the telomeres. S. mediterranea thus becomes the first organism described (to our knowledge) that forms a canonical telomere bouquet but does not require double-strand breaks for synapsis between homologous chromosomes. However, the initiation of SC formation at the base of the telomere bouquet, which then is followed by full-length homologous pairing in planarian spermatocytes, is not observed in other species and may not be conserved.
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Chen JE, Li JY, You ZY, Liu LL, Liang JS, Ma YY, Chen M, Zhang HR, Jiang ZD, Zhong BX. Proteome Analysis of Silkworm, Bombyx mori, Larval Gonads: Characterization of Proteins Involved in Sexual Dimorphism and Gametogenesis. J Proteome Res 2013; 12:2422-38. [DOI: 10.1021/pr300920z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jin-e Chen
- College of
Animal Sciences, Zhejiang University, Hangzhou
310058, PR China
- Institute
of Sericultural Research, Zhejiang Academy of Agricultural Sciences, Hangzhou
310021, PR China
| | - Jian-ying Li
- College of
Animal Sciences, Zhejiang University, Hangzhou
310058, PR China
- Institute
of Developmental and
Regenerative Biology, Hangzhou Normal University, Hangzhou 310036, PR China
| | - Zheng-ying You
- College of
Animal Sciences, Zhejiang University, Hangzhou
310058, PR China
| | - Li-li Liu
- College of Life Sciences, Zhejiang University, Hangzhou 310058, PR China
| | - Jian-she Liang
- College of Environmental and
Resource Sciences, Zhejiang University,
Hangzhou 310058, PR China
| | - Ying-ying Ma
- Zhejiang California International
NanoSystems Institute (ZCNI), Zhejiang University, Hangzhou 310029, PR China
| | - Ming Chen
- College of Life Sciences, Zhejiang University, Hangzhou 310058, PR China
| | - Hua-rong Zhang
- Zhejiang California International
NanoSystems Institute (ZCNI), Zhejiang University, Hangzhou 310029, PR China
| | - Zhen-dong Jiang
- College of
Animal Sciences, Zhejiang University, Hangzhou
310058, PR China
| | - Bo-xiong Zhong
- College of
Animal Sciences, Zhejiang University, Hangzhou
310058, PR China
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Houtsmuller AB, Oud JL, Voort HTM, Baarslag MW, Krol JJ, Mosterd B, Mans A, Brakenhoff GJ, Nanninga N. Image processing techniques for 3-D chromosome analysis. J Microsc 2011. [DOI: 10.1111/j.1365-2818.1990.tb02997.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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GRANDI GILBERTO, CHICCA MILVIA. Oogenesis in supplementary reproductives ofReticulitermes lucifugusRossi (Isoptera Rhinotermitidae): an ultrastructural study. INVERTEBR REPROD DEV 2010. [DOI: 10.1080/07924259.1999.9652368] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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13
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Abstract
The nature of recombination modifiers was investigated in Bombyx mori lines selected for high (H) and low (L) recombination rates between the p(S) and Y loci in chromosome 2. Since the mean recombination rates for the H x L and L x H F(1) crosses were approximately intermediate between those of high and low lines, the cytoplasmic maternal effect and difference in the activity of recombination modifiers between marked and unmarked second chromosomes were not detected. The H x (L x H), H x (H x L), L x (L x H) and L x (H x L) backcrosses indicated the presence of additive and dominance effects of marked and unmarked second chromosomes and the remaining chromosomes.--Recombination rates between the p(S) and Y loci in chromosome 2 and half-nonrecombination rates between the pe and re loci in chromosome 5 of high and low lines indicated that these recombination modifiers caused changes in the recombination frequency between p(S) and Y in chromosome 2, but not between pe and re in chromosome 5.--There were no differences in viability between individuals having the second chromosomes of the recombinant types [p(S) +, p(Y) (H); p(S) +, + Y (L)] and those of the nonrecombinant types [p(S) Y, p + (H); p(S) Y, + + (L)] in both high and low lines. Mean recombination rates measured in cis [p(S) Y/p + (H); p(S) Y/+ + (L)] and trans [p(S) +/p Y (H); p(S) +/+ Y (L)] males were the same in the high but not in the low line. No segregation of a single recombination modifier was indicated by the distribution of recombination rates measured in trans males [p(S) +/p Y (H); p(S) +/+ Y (L)] of high and low lines. Accordingly, the recombination modifiers distributed on chromosome 2 in the heterozygous condition were not gross chromosomal aberrations, but polygenic factors in the low line.
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Affiliation(s)
- H Ebinuma
- Laboratory of Sericultural Science, Faculty of Agriculture, University of Tokyo, Bunkyo-ku, Tokyo, 113 Japan
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14
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Koszul R, Kleckner N. Dynamic chromosome movements during meiosis: a way to eliminate unwanted connections? Trends Cell Biol 2009; 19:716-24. [PMID: 19854056 DOI: 10.1016/j.tcb.2009.09.007] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Revised: 09/15/2009] [Accepted: 09/22/2009] [Indexed: 01/14/2023]
Abstract
Dramatic chromosome motion is a characteristic of mid-prophase of meiosis that is observed across broadly divergent eukaryotic phyla. Although the specific mechanisms underlying chromosome motions vary among organisms studied to date, the outcome is similar in all cases: vigorous back-and-forth movement (as fast as approximately 1mum/sec for budding yeast), led by chromosome ends (or near-end regions), and directed by cytoskeletal components via direct association through the nuclear envelope. The exact role(s) of these movements remains unknown, although an idea gaining currency is that movement serves as a stringency factor, eliminating unwanted inter-chromosomal associations or entanglements that have arisen as part of the homolog pairing process and, potentially, unwanted associations of chromatin with the nuclear envelope. Turbulent chromosome movements observed during bipolar orientation of chromosomes for segregation could also serve similar roles during mitosis. Recent advances shed light on the contribution of protein complexes involved in the meiotic movements in chromosome dynamics during the mitotic program.
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Affiliation(s)
- Romain Koszul
- CNRS URA2171, Institut Pasteur, Unité de Génétique Moléculaire des Levures, 25 rue du Dr. Roux, 75015 Paris, France
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KOTIMÁKI MAIJA, HIIRSALMI HEIMO. Cytogenetic studies on Rubus arcticus, Rubus stellatus and their hybrids. Hereditas 2009. [DOI: 10.1111/j.1601-5223.1979.tb01645.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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LAANE MORTENM, WAHLSTRØM ROLF, MELLEM TORR. Scanning electron microscopy of nuclear division stages in Vicia faba and Haemanthus cinnabarinus. Hereditas 2009. [DOI: 10.1111/j.1601-5223.1977.tb01227.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Lake S. Recombination in the X-chromosome in hybrid females with and without a marked centromere from three inbred lines of Drosophila melanogaster. Hereditas 2008; 102:89-97. [PMID: 3921496 DOI: 10.1111/j.1601-5223.1985.tb00470.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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20
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NOKKALA SEPPO. Cytological characteristics of chromosome behaviour during female meiosis in Sphinx ligustri L. (Sphingidae, Lepidoptera). Hereditas 2008. [DOI: 10.1111/j.1601-5223.1987.tb00250.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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LIE THORE, LAANE MORTENM. Reconstruction analyses of synaptonemal complexes in haploid and diploid pachytene nuclei of Physarum polycephalum (Myxomycetes). Hereditas 2008. [DOI: 10.1111/j.1601-5223.1982.tb00043.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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22
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NOKKALA SEPPO, NOKKALA CHRISTINA. Achiasmatic male meiosis of collochore type in the heteropteran family Miridae. Hereditas 2008. [DOI: 10.1111/j.1601-5223.1986.tb00661.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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23
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Traut W, Sahara K, Marec F. Sex Chromosomes and Sex Determination in Lepidoptera. Sex Dev 2008; 1:332-46. [DOI: 10.1159/000111765] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 10/24/2007] [Indexed: 11/19/2022] Open
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Narukawa J, Yamamoto K, Ohtani T, Sugiyama S. Imaging of silkworm meiotic chromosome by atomic force microscopy. SCANNING 2007; 29:123-7. [PMID: 17455263 DOI: 10.1002/sca.20032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Although structural information of mitotic chromosomes has been accumulated, little information is available for meiotic chromosome structures. Here, we applied atomic force microscopy (AFM) to investigate the ultrastructures of the silkworm, Bombyx mori, meiotic pachytene chromosome in its native state with nanometer scale resolution. Two levels of DNA folding were observed on the meiotic chromosome surface, 50-70 nm granules, which were considered to be 30 nm chromatin fibers, and spherical protrusions of 400-600 nm, which were considered to be chromomeres and arranged on the surface of the chromosome parallel to the chromosome longitudinal axis. These observations suggested that AFM study is an excellent approach for obtaining information concerning the silkworm pachytene chromosome higher order structure.
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Affiliation(s)
- J Narukawa
- Insect Genome Research Unit, Division of Insect Sciences, National Institute of Agrobiological Science, Tsukuba, Ibaraki, Japan
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Yoshido A, Bando H, Yasukochi Y, Sahara K. The Bombyx mori karyotype and the assignment of linkage groups. Genetics 2005; 170:675-85. [PMID: 15802516 PMCID: PMC1450397 DOI: 10.1534/genetics.104.040352] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lepidopteran species have a relatively high number of small holocentric chromosomes (Bombyx mori, 2n = 56). Chromosome identification has long been hampered in this group by the high number and by the absence of suitable markers like centromere position and chromosome bands. In this study, we carried out fluorescence in situ hybridization (FISH) on meiotic chromosome complements using genetically mapped B. mori bacterial artificial chromosomes (BACs) as probes. The combination of two to four either green or red fluorescence-labeled probes per chromosome allowed us to recognize unequivocally each of the 28 bivalents of the B. mori karyotype by its labeling pattern. Each chromosome was assigned one of the already established genetic linkage groups and the correct orientation in the chromosome was defined. This facilitates physical mapping of any other sequence and bears relevance for the ongoing B. mori genome projects. Two-color BAC-FISH karyotyping overcomes the problem of chromosome recognition in organisms where conventional banding techniques are not available.
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Affiliation(s)
- Atsuo Yoshido
- Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
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Bhuiyan H, Schmekel K. Meiotic chromosome synapsis in yeast can occur without spo11-induced DNA double-strand breaks. Genetics 2005; 168:775-83. [PMID: 15514052 PMCID: PMC1448848 DOI: 10.1534/genetics.104.029660] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proper chromosome segregation and formation of viable gametes depend on synapsis and recombination between homologous chromosomes during meiosis. Previous reports have shown that the synaptic structures, the synaptonemal complexes (SCs), do not occur in yeast cells with the SPO11 gene removed. The Spo11 enzyme makes double-strand breaks (DSBs) in the DNA and thereby initiates recombination. The view has thus developed that synapsis in yeast strictly depends on the initiation of recombination. Synapsis in some other species (Drosophila melanogaster and Caenorhabditis elegans) is independent of recombination events, and SCs are found in spo11 mutants. This difference between species led us to reexamine spo11 deletion mutants of yeast. Using antibodies against Zip1, a SC component, we found that a small fraction (1%) of the spo11 null mutant cells can indeed form wild-type-like SCs. We further looked for synapsis in a spo11 mutant strain that accumulates pachytene cells (spo11Delta ndt80Delta), and found that the frequency of cells with apparently complete SC formation was 10%. Other phenotypic criteria, such as spore viability and homologous chromosome juxtaposition measured by FISH labeling of chromosomal markers, agree with several previous reports of the spo11 mutant. Our results demonstrate that although the Spo11-induced DSBs obviously promote synapsis in yeast, the presence of Spo11 is not an absolute requirement for synapsis.
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Affiliation(s)
- Hasanuzzaman Bhuiyan
- Department of Molecular Biology and Functional Genomics, Stockholm University, SE-106 91 Stockholm, Sweden
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27
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Wang YX, Marec F, Traut W. The Synaptonemal Complex Complement of the Wax Moth, Galleria Mellonella. Hereditas 2004. [DOI: 10.1111/j.1601-5223.1993.00113.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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28
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Kawamura N, Sahara K, Iizuka T. Preferential Pairing of Sex Chromosomes in the Tetraploid Silkworms (Bombyx Mori). Hereditas 2004. [DOI: 10.1111/j.1601-5223.1994.00073.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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29
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30
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Traut W, Clarke CA. Cytogenetics of a Moth Species with a Low Chromosome Number, Orgyia Thyellina. Hereditas 2004. [DOI: 10.1111/j.1601-5223.1996.00277.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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31
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Henderson KA, Keeney S. Tying synaptonemal complex initiation to the formation and programmed repair of DNA double-strand breaks. Proc Natl Acad Sci U S A 2004; 101:4519-24. [PMID: 15070750 PMCID: PMC384779 DOI: 10.1073/pnas.0400843101] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Indexed: 11/18/2022] Open
Abstract
During meiosis, homologous chromosomes recombine and become closely apposed along their lengths within the synaptonemal complex (SC). In part because Spo11 is required both to make the double-strand breaks (DSBs) that initiate recombination and to promote normal SC formation in many organisms, it is clear that these two processes are intimately coupled. The molecular nature of this linkage is not well understood, but it has been proposed that SC formation initiates locally at the sites of ongoing recombination and in particular at the subset of sites that will eventually give rise to crossovers. To test this hypothesis, we examined further the relationship between DSBs and SC formation in Saccharomyces cerevisiae. SCs were monitored in a series of spo11 missense mutants with varying DSB frequencies. Alleles that blocked DSB formation gave SC phenotypes indistinguishable from a deletion mutant, and partial loss-of-function mutations with progressively more severe DSB defects caused corresponding defects in SC formation. These results strongly correlate SC formation with Spo11 catalytic activity per se. Numbers of Zip3 complexes on chromosomes, thought to represent the sites of SC initiation, also declined when Spo11 activity decreased, but in a markedly nonlinear fashion: hypomorphic spo11 alleles caused larger defects in DSB formation than in Zip3 complex formation. This nonlinear response of Zip3 closely paralleled the response of crossover recombination products. The quantitative relationship between Zip3 foci, SC formation, and crossing over strongly implicates crossover-designated recombination intermediates as the sites of SC initiation.
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Affiliation(s)
- Kiersten A Henderson
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center and Weill Graduate School of Medical Sciences, Cornell University, New York, NY 10021, USA
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32
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Abstract
Development requires a precise program of gene expression to be carried out. Much work has focussed on the regulatory networks that control gene expression, for example in response to external cues. However, it is important to recognize that these regulatory events take place within the physical context of the nucleus, and that the physical position of a gene within the nuclear volume can have strong influences on its regulation and interactions. The first part of this review will summarize what is currently known about nuclear architecture, that is, the large-scale three-dimensional arrangement of chromosome loci within the nucleus. The remainder of the review will examine developmental processes from the point of view of the nucleus.
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Affiliation(s)
- Wallace F Marshall
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
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33
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Cowan CR, Carlton PM, Cande WZ. Reorganization and polarization of the meiotic bouquet-stage cell can be uncoupled from telomere clustering. J Cell Sci 2002; 115:3757-66. [PMID: 12235286 DOI: 10.1242/jcs.00054] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Striking cellular reorganizations mark homologous pairing during meiotic prophase. We address the interdependence of chromosomal and cellular polarization during meiotic telomere clustering, the defining feature of the bouquet stage, by examining nuclear positioning and microtubule and nuclear pore reorganization. Polarization of meiotic cellular architecture was coincident with telomere clustering: microtubules were focused on the nuclear surface opposite the telomere cluster, the nucleus was positioned eccentrically in the cell such that the telomeres faced the direction of nuclear displacement and nuclear pores were clustered in a single region of the nuclear surface opposite the telomeres. Treatment of pre-bouquet stage cells with colchicine inhibited telomere clustering. Asymmetric nuclear positioning and nuclear pore clustering were normal in the presence of unclustered telomeres resulting from colchicine treatment. Nuclear pores were positioned normally with respect to the cell cortex in the absence of telomere clustering, indicating that telomere positioning is not required for polarization. This work provides evidence of meiotic cell polarization and suggests that telomeres may be positioned relative to an asymmetry present in the cell at the time of bouquet formation.
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Affiliation(s)
- Carrie R Cowan
- Department of Plant and Microbial Biology, University of California - Berkeley, Berkeley, CA 94720-3200, USA
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34
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Abstract
The 'chromosomal bouquet' is a polarized chromosomal arrangement that is highly conserved among eukaryotes. There have been many hypotheses about its role in the pairing of meiotic chromosomes, but until recently these have been difficult to test.
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Affiliation(s)
- H Scherthan
- Department of Human Biology and Human Genetics, University of Kaiserslautern, D-67653 Kaiserslautern, Germany.
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35
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Tanaka N, Yokoyama T, Abe H, Tsuchida K, Ninagi O, Oshiki T. Cytogenetic analysis shows that the unusually large chromosome in the sex-limited pB silkworm (Bombyx mori) strain consists of three chromosomes. Hereditas 2001; 133:95-103. [PMID: 11338434 DOI: 10.1111/j.1601-5223.2000.t01-1-00095.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
We have discovered an inordinately large chromosome pair at the pachytene stage in the oocyte of the sex-limited pB (black larval marking) silkworm (Bombyx mori) strain (TWPB). We have analyzed the composition and arrangement of this large chromosome. A genetic linkage analysis shows that the large chromosome is made up of the W chromosome, the second chromosome fragment (pB fragment), and the fifth chromosome (linkage group) containing at least the region from map position 0.0 to 40.8. We also observed a sex heterochromatin body (SB) that we deduced to be made up of condensed W chromosomes. The number of SBs in each female nucleus among the sucking stomach cells of the TWPB strain was variable. Evidently, the W chromosome of the TWPB strain is attached to another chromosome. The composition of the W chromosome, the second chromosome fragment, and the fifth chromosome was studied through linkage analysis for these three chromosomes. We used two strains derived from the TWPB strain, the sex-limited pM (moricaud larval marking)-like (TWPML) and the autosomal pM-like (T5PML). The results show that the TWPML strain originates through a detachment of the fifth chromosome from the large chromosome of the TWPB strain, and the T5PML strain originates through a detachment of the W chromosome from that. Accordingly, the large chromosome of the TWPB strain is arranged in the order W chromosome--second chromosome fragment--fifth chromosome.
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Affiliation(s)
- N Tanaka
- Department of Biological Production, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwai-cho 3-5-8, Fuchu, Tokyo 183-8509, Japan.
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36
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Cowan CR, Carlton PM, Cande WZ. The polar arrangement of telomeres in interphase and meiosis. Rabl organization and the bouquet. PLANT PHYSIOLOGY 2001; 125:532-8. [PMID: 11161011 PMCID: PMC1539364 DOI: 10.1104/pp.125.2.532] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- C R Cowan
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA
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37
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Abstract
Meiotic chromosomes have been studied for many years, in part because of the fundamental life processes they represent, but also because meiosis involves the formation of homolog pairs, a feature which greatly facilitates the study of chromosome behavior. The complex events involved in homolog juxtaposition necessitate prolongation of prophase, thus permitting resolution of events that are temporally compressed in the mitotic cycle. Furthermore, once homologs are paired, the chromosomes are connected by a specific structure: the synaptonemal complex. Finally, interaction of homologs includes recombination at the DNA level, which is intimately linked to structural features of the chromosomes. In consequence, recombination-related events report on diverse aspects of chromosome morphogenesis, notably relationships between sisters, development of axial structure, and variations in chromatin status. The current article reviews recent information on these topics in an historical context. This juxtaposition has suggested new relationships between structure and function. Additional issues were addressed in a previous chapter (551).
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Affiliation(s)
- D Zickler
- Institut de Génétique et Microbiologie, Université Paris-Sud, Orsay, France.
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38
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Abstract
The leptotene/zygotene transition of meiosis, as defined by classical cytological studies, is the period when homologous chromosomes, already being discernible individualized entities, begin to be close together or touching over portions of their lengths. This period also includes the bouquet stage: Chromosome ends, which have already become integral components of the inner nuclear membrane, move into a polarized configuration, along with other nuclear envelope components. Chromosome movements, active or passive, also occur. The detailed nature of interhomologue interactions during this period, with special emphasis on the involvement of chromosome ends, and the overall role for meiosis and recombination of chromosome movement and, especially, the bouquet stage are discussed.
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Affiliation(s)
- D Zickler
- Institut de Génétique et Microbiologie, Université Paris-Sud, Orsay, France.
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39
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Wolf KW, Joshi HC. Distribution of gamma-tubulin differs in primary and secondary oocytes of Ephestia kuehniella (Pyralidae, Lepidoptera). Mol Reprod Dev 1996; 45:225-30. [PMID: 8914081 DOI: 10.1002/(sici)1098-2795(199610)45:2<225::aid-mrd16>3.0.co;2-#] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In a previous study, barrel-shaped spindles were found in metaphase I oocytes of Ephestia kuehniella (Pyralidae, Lepidoptera). Aster microtubules (MTs) were missing (Wolf, 1993: Cell Motil Cytoskeleton 24:200-204). This points to an acentriolar organization of the spindle apparatus. The present study was aimed at the question of whether gamma-tubulin, a newly detected member of the tubulin superfamily that has often been identified in microtubule-organizing centers, plays a role in the nucleation of MTs in meiotic spindles of the moth. To this end, the distribution of gamma-tubulin was examined in oocytes of E. kuehniella using an antibody against gamma-tubulin in combination with indirect immunofluorescence. The antibody evenly decorated spindle MTs in metaphase I oocytes of the moth. Enhanced staining of the spindle poles was not detectable. In subsequent stages of meiosis, gamma-tubulin was gradually lost from spindle MTs and was then found at the surface of the so-called elimination chromatin. Female meiosis in Lepidoptera is achiasmatic. The elimination chromatin, i.e., modified and persisting synaptonemal complexes, is believed to keep homologous chromosomes linked until the onset of anaphase I. In meiosis I of female Lepidoptera, the elimination chromatin persists at the spindle equator between the segregating chromatin masses. It is plausible to assume that gamma-tubulin is involved in spindle organization in the absence of canonical centrosomes. In MTs of metaphase II spindles of E. kuehniella, gamma-tubulin was no longer detectable with our immunological approach. This points to a far-reaching change in spindle organization during transition from meiosis I to meiosis II.
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Affiliation(s)
- K W Wolf
- Johannes Gutenberg-Universität Mainz, Institut für Anthropologie, Germany
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40
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41
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Thomas HM, Thomas BJ. Meiosis of triploid Lolium. III. Synaptonemal complex formation in the two inverse autoallotriploids of L. temulentum and L. multiflorum, TTM and TMM. Heredity (Edinb) 1996. [DOI: 10.1038/hdy.1996.4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Sym M, Roeder GS. Zip1-induced changes in synaptonemal complex structure and polycomplex assembly. J Biophys Biochem Cytol 1995; 128:455-66. [PMID: 7860625 PMCID: PMC2199901 DOI: 10.1083/jcb.128.4.455] [Citation(s) in RCA: 139] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The yeast Zip1 protein is a component of the synaptonemal complex (SC), which is an elaborate macromolecular structure found along the lengths of chromosomes during meiosis. Mutations that increase the length of the predicted coiled coil region of the Zip1 protein show that Zip1 influences the width of the SC. Overexpression of the ZIP1 gene results in the formation of two distinct types of higher order structures that are found in the nucleus, but not associated with chromatin. One of these structures resembles the polycomplexes that have been observed in many organisms and are thought to be aggregates of SC components. The second type of structure, which we have termed "networks," does not resemble any previously identified SC-related structure. Assembly of both polycomplexes and networks can occur independently of the Hop1 or Red1 protein, which are thought to be SC components. Our results demonstrate that Zip1 is a structural component of the central region of the SC. More specifically, we speculate that Zip1 is a component of the transverse filaments that lie perpendicular to the long axis of the complex.
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Affiliation(s)
- M Sym
- Department of Biology, Yale University, New Haven, Connecticut 06520-8103
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43
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Havekes FW, de Jong JH, Heyting C, Ramanna MS. Synapsis and chiasma formation in four meiotic mutants of tomato (Lycopersicon esculentum). Chromosome Res 1994; 2:315-25. [PMID: 7921647 DOI: 10.1007/bf01552725] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Synapsis and chiasma formation were studied in pollen mother cells of four meiotic mutants of tomato. The four mutants displayed defects in the assembly of the synaptonemal complex (SC) covering the whole range from almost complete absence of synapsis to complete synapsis at pachytene. In three mutants, we found a good correlation between the number of bivalents connected by at least one tripartite SC segment at pachytene and the number of chiasmatic bivalents at metaphase I. We suggest that in tomato functional chiasmata are only formed in the context of the tripartite SC.
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Affiliation(s)
- F W Havekes
- Department of Genetics, Wageningen Agricultural University, The Netherlands
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44
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Wolf KW. The spindle apparatus in early embryonic divisions of Ephestia kuehniella Z. (Pyralidae, Lepidoptera) is formed by alignment of minispindles. ZYGOTE 1994; 2:87-95. [PMID: 7881921 DOI: 10.1017/s0967199400001805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Spindles were isolated from deposited eggs of the Mediterranean mealmoth, Ephestia kuehniella. Their structure and development were studied using anti-tubulin immunofluorescence. The microtubules were labelled with three different monoclonal antibodies. These were directed against beta-tubulin, tyrosinated alpha-tubulin and acetylated alpha-tubulin. Significant differences in the staining behaviour were not detected with the three antibodies. An unusual mode of spindle formation was observed during the first mitotic division after fusion of the pronuclei. Several of the ensuing embryonic divisions may show the same phenomenon. Prophase of these divisions was characterised by an irregular arrangement of microtubules in the nuclear area. The microtubular mass in the nuclear area increased concomitantly with chromosome condensation. Microtubular foci, comparable to the forming asters of canonical spindles, were not detected. The formation of an orderly pattern in the microtubule mass was signalled by the appearance of minispindles apparently developing around individual chromosomes. Several minispindles subsequently aligned and formed metaphase-like entities within the nuclear area. The metaphase-like entities, in turn, aligned with one another and gave rise to a conventional bipolar metaphase spindle with small asters. The further development of the spindle was conventional. The chromosomes migrated towards the spindle poles and finally daughter nuclei formed. The anaphase and telophase spindles possessed both a prominent array of interzone microtubules and asters. The events in prophase of early embryonic mitosis of E. kuehniella may represent a rare case of chromosome-induced spindle formation.
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Affiliation(s)
- K W Wolf
- Institut für Biologie der Medizinischen, Universität zu Lübeck, Germany
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45
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46
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Schmekel K, Wahrman J, Skoglund U, Daneholt B. The central region of the synaptonemal complex in Blaps cribrosa studied by electron microscope tomography. Chromosoma 1993; 102:669-81. [PMID: 8149808 DOI: 10.1007/bf00650893] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The synaptonemal complex (SC) in the beetle Blaps cribrosa contains a highly organized central element (CE), two flanking lateral elements (LEs), and a number of regularly spaced transverse filaments (TFs) crossing the central region. The CE is built like a ladder with two longitudinal components running in parallel and a number of regularly spaced transverse CE components, bridging the two longitudinal components. The CE is multi-layered with the ladders of the individual layers more or less in register. Essentially every TF originates in one of the LEs, crosses the CE through a transverse CE component and reaches the opposite LE; every transverse CE component in a given layer corresponds to one, and only one, TF. In a CE layer, short irregular pillars form the junctions between the transverse and longitudinal CE components. Adjacent pillars are connected to each other by fine fibrous bridges: the two pillars in the same transverse CE component are linked, and so are the pillars along each longitudinal component, and also more occasionally adjacent pillars in separate CE layers. It is proposed that a TF with the two associated short pillars represents the structural unit in the central region. The ordered structure of the CE is accomplished by linking adjacent pillars to each other into the well-defined three-dimensional organization of the CE.
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Affiliation(s)
- K Schmekel
- Department of Cell and Molecular Biology (CMB), Medical Nobel Institute, Karolinska Institutet, Stockholm, Sweden
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47
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Schmekel K, Skoglund U, Daneholt B. The three-dimensional structure of the central region in a synaptonemal complex: a comparison between rat and two insect species, Drosophila melanogaster and Blaps cribrosa. Chromosoma 1993; 102:682-92. [PMID: 8149809 DOI: 10.1007/bf00650894] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The highly ordered central region of the synaptonemal complex (SC) in Blaps cribrosa has recently been studied by electron microscope tomography (EMT), and a simple three-dimensional model presented. Using the same experimental approach we have now compared the central region in Blaps with the central regions in Drosophila melanogaster and rat. In all three species, the SCs exhibit a central element (CE) flanked by two lateral elements (LEs). The central region between the two LEs is crossed by transverse filaments (TFs). The Blaps CE element is the most ordered one with a well-defined ladder-like structure with two longitudinal components bridged by a number of regularly spaced transverse components, the rungs of the ladder. At the junctions between the longitudinal and transverse components there are prominent dense structures. The CE is multi-layered with the ladders of the separate layers in approximate register. In Drosophila the transverse CE components are as distinct and well organized as in Blaps, while in rat they are present but are less frequent and less well ordered. The longitudinal CE components in Drosophila are often fragmented and even more so in rat. The tomographic analysis revealed that in all three species the central region contains the same structural units: a single TF associated with two short pillars (or globules), which correspond to the junction structures. A fibrous lattice connects the two pillars/globules on the same TF forming the transverse CE component and those on adjacent TFs forming the longitudinal CE component; fibers between pillars/globules also link consecutive CE layers together. In the longitudinal component the number of fibrous bridges between the pillars/globules is related to the conspicuousness of the longitudinal component, i.e. Blaps has most, Drosophila almost as many, and rat considerably fewer bridges. We conclude that the central region in rat, Drosophila and Blaps contains the same basic structural unit but the degree of order and concentration of the units differ: a higher density seems to be accompanied by a higher order within the CE.
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Affiliation(s)
- K Schmekel
- Department of Cell and Molecular Biology (CMB), Medical Nobel Institute, Karolinska Institutet, Stockholm, Sweden
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48
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Synaptonemal complexes in female and male meiotic prophase of Ephestia kuehniella (Lepidoptera). Heredity (Edinb) 1993. [DOI: 10.1038/hdy.1993.154] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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49
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Wolf KW, Mesa A. Synaptonemal polycomplexes in spermatids: a characteristic trait of Orthoptera? Chromosome Res 1993; 1:181-8. [PMID: 8156156 DOI: 10.1007/bf00710772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Spermatogenesis was analysed in a cricket, Eneoptera surinamensis (Gryllidae, Orthoptera), using ultrathin serial sections and transmission electron microscopy. Special attention was placed on documentation of the development and structure of synaptonemal polycomplexes (PCs) within spermatid nuclei. Pachytene spermatocytes showed the usual tripartite synaptonemal complexes in the nuclear lumen. PCs were situated close to chromosomes at the periphery of spindles in prometaphase I spermatocytes, where microtubule density was low. The PCs are probably incorporated into the daughter nuclei of both meiotic divisions by adhesion to chromosomes. Finally, PCs end up within spermatid nuclei. Analysis of serial sections through three nuclei of young spermatids revealed at least one PC within each. The PCs were intimately attached to an electron-dense spherical nuclear body. This topographical correlation was confirmed through inspection of random sections. The PCs may have an affinity to the spherical bodies. In more developed spermatids, PCs and nuclear bodies were missing. Disassembly products of the PCs may play a role in spermatid maturation. In a series of other Orthoptera species, PCs have been reported to occur in the cytoplasm or the nuclei of spermatids. In most other systematic groups, PCs do not form at all or disassemble earlier. The presence of PCs in young spermatids, therefore, seems to be typical of Orthoptera.
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Affiliation(s)
- K W Wolf
- Institut für Biologie der Medizinischen Universität, Lübeck, Germany
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50
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Schmekel K, Wahrman J, Daneholt B. Solitary and synaptonemal complex-associated recombination nodules in pro-nurse cells during oogenesis in Drosophila melanogaster. Chromosoma 1993; 102:396-402. [PMID: 8365349 DOI: 10.1007/bf00360404] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
An oocyte in Drosophila melanogaster originates from 1 of 16 cells comprising an ovarial syncytium. The two pro-oocytes proceed into the pachytene stage of meiosis, but only one develops further into a mature oocyte while the other reverts to a nurse cell. It is known that pro-nurse cells also enter meiosis, as they contain incomplete synaptonemal complexes (SCs). We now show that these cells also harbour recombination nodules (RNs). In cells that only occasionally contain SC segments, the RNs are typically not located close to distinct tripartite SC structures. Instead, these RNs are frequently associated with a spherical body of amorphous material and two to three, more or less parallel fibres, possibly representing SC material. The significance of the solitary RNs is discussed in relation to the present knowledge of the assembly and disassembly of the SC.
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Affiliation(s)
- K Schmekel
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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