1
|
Kindelay SM, Maggert KA. Insights into ribosomal DNA dominance and magnification through characterization of isogenic deletion alleles. Genetics 2024; 227:iyae063. [PMID: 38797870 DOI: 10.1093/genetics/iyae063] [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: 03/12/2024] [Accepted: 04/02/2024] [Indexed: 05/29/2024] Open
Abstract
The major loci for the large primary ribosomal RNA (rRNA) genes (35S rRNAs) exist as hundreds to thousands of tandem repeats in all organisms and dozens to hundreds in Drosophila. The highly repetitive nature of the ribosomal DNA (rDNA) makes it intrinsically unstable, and many conditions arise from the reduction in or magnification of copy number, but the conditions under which it does so remain unknown. By targeted DNA damage to the rDNA of the Y chromosome, we created and investigated a series of rDNA alleles. We found that complete loss of rDNA leads to lethality after the completion of embryogenesis, blocking larval molting and metamorphosis. We find that the resident retrotransposons-R1 and R2-are regulated by active rDNA such that reduction in copy number derepresses these elements. Their expression is highest during the early first instar, when loss of rDNA is lethal. Regulation of R1 and R2 may be related to their structural arrangement within the rDNA, as we find they are clustered in the flanks of the nucleolus organizing region (NOR; the cytological appearance of the rDNA). We assessed the complex nucleolar dominance relationship between X- and Y-linked rDNA using a histone H3.3-GFP reporter construct and incorporation at the NOR and found that dominance is controlled by rDNA copy number as at high multiplicity the Y-linked array is dominant, but at low multiplicity the X-linked array becomes derepressed. Finally, we found that multiple conditions that disrupt nucleolar dominance lead to increased rDNA magnification, suggesting that the phenomena of dominance and magnification are related, and a single mechanism may underlie and unify these two longstanding observations in Drosophila.
Collapse
Affiliation(s)
- Selina M Kindelay
- Genetics Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ, 85721, USA
| | - Keith A Maggert
- Genetics Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ, 85721, USA
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721, USA
| |
Collapse
|
2
|
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 PMCID: PMC11226059 DOI: 10.1371/journal.pgen.1011329] [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: 10/13/2023] [Revised: 07/05/2024] [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 center 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 co-orienting these separated kinetochores. 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.
Collapse
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
| |
Collapse
|
3
|
Mikhalchenko A, Gutierrez NM, Frana D, Safaei Z, Van Dyken C, Li Y, Ma H, Koski A, Liang D, Lee SG, Amato P, Mitalipov S. Induction of somatic cell haploidy by premature cell division. SCIENCE ADVANCES 2024; 10:eadk9001. [PMID: 38457500 PMCID: PMC10923512 DOI: 10.1126/sciadv.adk9001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 01/31/2024] [Indexed: 03/10/2024]
Abstract
Canonical mitotic and meiotic cell divisions commence with replicated chromosomes consisting of two sister chromatids. Here, we developed and explored a model of premature cell division, where nonreplicated, G0/G1-stage somatic cell nuclei are transplanted to the metaphase cytoplasm of mouse oocytes. Subsequent cell division generates daughter cells with reduced ploidy. Unexpectedly, genome sequencing analysis revealed proper segregation of homologous chromosomes, resulting in complete haploid genomes. We observed a high occurrence of somatic genome haploidization in nuclei from inbred genetic backgrounds but not in hybrids, emphasizing the importance of sequence homology between homologs. These findings suggest that premature cell division relies on mechanisms similar to meiosis I, where genome haploidization is facilitated by homologous chromosome interactions, recognition, and pairing. Unlike meiosis, no evidence of recombination between somatic cell homologs was detected. Our study offers an alternative in vitro gametogenesis approach by directly reprogramming diploid somatic cells into haploid oocytes.
Collapse
Affiliation(s)
- Aleksei Mikhalchenko
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Nuria Marti Gutierrez
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Daniel Frana
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Zahra Safaei
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Crystal Van Dyken
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Ying Li
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Hong Ma
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Amy Koski
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Dan Liang
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
- Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No 218 Jixi Road, Hefei, 230022 Anhui, China
| | - Sang-Goo Lee
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Paula Amato
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR, USA
| | - Shoukhrat Mitalipov
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| |
Collapse
|
4
|
Lee L, Rosin LF. Uncharted territories: Solving the mysteries of male meiosis in flies. PLoS Genet 2024; 20:e1011185. [PMID: 38489251 PMCID: PMC10942038 DOI: 10.1371/journal.pgen.1011185] [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] [Indexed: 03/17/2024] Open
Abstract
The segregation of homologous chromosomes during meiosis typically requires tight end-to-end chromosome pairing. However, in Drosophila spermatogenesis, male flies segregate their chromosomes without classic synaptonemal complex formation and without recombination, instead compartmentalizing homologs into subnuclear domains known as chromosome territories (CTs). How homologs find each other in the nucleus and are separated into CTs has been one of the biggest riddles in chromosome biology. Here, we discuss our current understanding of pairing and CT formation in flies and review recent data on how homologs are linked and partitioned during meiosis in male flies.
Collapse
Affiliation(s)
- LingSze Lee
- 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
| | - 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
| |
Collapse
|
5
|
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.
Collapse
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.
| |
Collapse
|
6
|
Tian Y, Liu L, Gao J, Wang R. Homologous chromosome pairing: The linchpin of accurate segregation in meiosis. J Cell Physiol 2024; 239:3-19. [PMID: 38032002 DOI: 10.1002/jcp.31166] [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: 09/09/2023] [Revised: 11/13/2023] [Accepted: 11/20/2023] [Indexed: 12/01/2023]
Abstract
Meiosis is a specialized cell division that occurs in sexually reproducing organisms, generating haploid gametes containing half the chromosome number through two rounds of cell division. Homologous chromosomes pair and prepare for their proper segregation in subsequent divisions. How homologous chromosomes recognize each other and achieve pairing is an important question. Early studies showed that in most organisms, homologous pairing relies on homologous recombination. However, pairing mechanisms differ across species. Evidence indicates that chromosomes are dynamic and move during early meiotic stages, facilitating pairing. Recent studies in various model organisms suggest conserved mechanisms and key regulators of homologous chromosome pairing. This review summarizes these findings and compare similarities and differences in homologous chromosome pairing mechanisms across species.
Collapse
Affiliation(s)
- Yuqi Tian
- Center for Cell Structure and Function, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan, China
| | - Libo Liu
- Center for Cell Structure and Function, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan, China
| | - Jinmin Gao
- Center for Cell Structure and Function, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan, China
| | - Ruoxi Wang
- Center for Cell Structure and Function, College of Life Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, Shandong Normal University, Jinan, China
| |
Collapse
|
7
|
Huang Y, Liu Y, Guo X, Fan C, Yi C, Shi Q, Su H, Liu C, Yuan J, Liu D, Yang W, Han F. New insights on the evolution of nucleolar dominance in newly resynthesized hexaploid wheat Triticum zhukovskyi. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:1298-1315. [PMID: 37246611 DOI: 10.1111/tpj.16320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/11/2023] [Accepted: 05/23/2023] [Indexed: 05/30/2023]
Abstract
Nucleolar dominance (ND) is a widespread epigenetic phenomenon in hybridizations where nucleolus transcription fails at the nucleolus organizer region (NOR). However, the dynamics of NORs during the formation of Triticum zhukovskyi (GGAu Au Am Am ), another evolutionary branch of allohexaploid wheat, remains poorly understood. Here, we elucidated genetic and epigenetic changes occurring at the NOR loci within the Am , G, and D subgenomes during allopolyploidization by synthesizing hexaploid wheat GGAu Au Am Am and GGAu Au DD. In T. zhukovskyi, Au genome NORs from T. timopheevii (GGAu Au ) were lost, while the second incoming NORs from T. monococcum (Am Am ) were retained. Analysis of the synthesized T. zhukovskyi revealed that rRNA genes from the Am genome were silenced in F1 hybrids (GAu Am ) and remained inactive after genome doubling and subsequent self-pollinations. We observed increased DNA methylation accompanying the inactivation of NORs in the Am genome and found that silencing of NORs in the S1 generation could be reversed by a cytidine methylase inhibitor. Our findings provide insights into the ND process during the evolutionary period of T. zhukovskyi and highlight that inactive rDNA units may serve as a 'first reserve' in the form of R-loops, contributing to the successful evolution of T. zhukovskyi.
Collapse
Affiliation(s)
- Yuhong Huang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yang Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xianrui Guo
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Chaolan Fan
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Congyang Yi
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qinghua Shi
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Handong Su
- Huazhong Agricultural University, Hubei, 430070, China
| | - Chang Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jing Yuan
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Dengcai Liu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, China
| | - Wuyun Yang
- Crop Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, China
| | - Fangpu Han
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| |
Collapse
|
8
|
Solé M, Pascual Á, Anton E, Blanco J, Sarrate Z. The courtship choreography of homologous chromosomes: timing and mechanisms of DSB-independent pairing. Front Cell Dev Biol 2023; 11:1191156. [PMID: 37377734 PMCID: PMC10291267 DOI: 10.3389/fcell.2023.1191156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/01/2023] [Indexed: 06/29/2023] Open
Abstract
Meiosis involves deep changes in the spatial organisation and interactions of chromosomes enabling the two primary functions of this process: increasing genetic diversity and reducing ploidy level. These two functions are ensured by crucial events such as homologous chromosomal pairing, synapsis, recombination and segregation. In most sexually reproducing eukaryotes, homologous chromosome pairing depends on a set of mechanisms, some of them associated with the repair of DNA double-strand breaks (DSBs) induced at the onset of prophase I, and others that operate before DSBs formation. In this article, we will review various strategies utilised by model organisms for DSB-independent pairing. Specifically, we will focus on mechanisms such as chromosome clustering, nuclear and chromosome movements, as well as the involvement of specific proteins, non-coding RNA, and DNA sequences.
Collapse
Affiliation(s)
| | | | | | - Joan Blanco
- *Correspondence: Joan Blanco, ; Zaida Sarrate,
| | | |
Collapse
|
9
|
Hyden B, Zou J, Wilkerson DG, Carlson CH, Robles AR, DiFazio SP, Smart LB. Structural variation of a sex-linked region confers monoecy and implicates GATA15 as a master regulator of sex in Salix purpurea. THE NEW PHYTOLOGIST 2023; 238:2512-2523. [PMID: 36866707 DOI: 10.1111/nph.18853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 02/21/2023] [Indexed: 05/19/2023]
Abstract
The Salicaceae, including Populus and Salix, are dioecious perennials that utilize different sex determination systems. This family provides a useful system to better understand the evolution of dioecy and sex chromosomes. Here, a rare monoecious genotype of Salix purpurea, 94003, was self- and cross-pollinated and progeny sex ratios were used to test hypotheses on possible mechanisms of sex determination. To delimit genomic regions associated with monoecious expression, the 94003 genome sequence was assembled and DNA- and RNA-Seq of progeny inflorescences was performed. Based on alignments of progeny shotgun DNA sequences to the haplotype-resolved monoecious 94003 genome assembly and reference male and female genomes, a 1.15 Mb sex-linked region on Chr15W was confirmed to be absent in monecious plants. Inheritance of this structural variation is responsible for the loss of a male-suppressing function in what would otherwise be genetic females (ZW), resulting in monoecy (ZWH or WWH ), or lethality, if homozygous (WH WH ). We present a refined, two-gene sex determination model for Salix purpurea, mediated by ARR17 and GATA15 that is different from the single-gene ARR17-mediated system in the related genus Populus.
Collapse
Affiliation(s)
- Brennan Hyden
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
| | - Junzhu Zou
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
- Research Institute of Forestry, Chinese Academy of Forestry, Dongxiaofu No. 1, Haidian District, Beijing, 100091, China
| | - Dustin G Wilkerson
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
| | - Craig H Carlson
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
- Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, USDA-ARS, Fargo, ND, 58102, USA
| | - Ayiana Rivera Robles
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
| | - Stephen P DiFazio
- Department of Biology, West Virginia University, Morgantown, WV, 26506, USA
| | - Lawrence B Smart
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
| |
Collapse
|
10
|
Flynn JM, Hu KB, Clark AG. Three recent sex chromosome-to-autosome fusions in a Drosophila virilis strain with high satellite DNA content. Genetics 2023; 224:iyad062. [PMID: 37052958 PMCID: PMC10213488 DOI: 10.1093/genetics/iyad062] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 12/02/2022] [Accepted: 04/07/2023] [Indexed: 04/14/2023] Open
Abstract
The karyotype, or number and arrangement of chromosomes, has varying levels of stability across both evolution and disease. Karyotype changes often originate from DNA breaks near the centromeres of chromosomes, which generally contain long arrays of tandem repeats or satellite DNA. Drosophila virilis possesses among the highest relative satellite abundances of studied species, with almost half its genome composed of three related 7 bp satellites. We discovered a strain of D. virilis that we infer recently underwent three independent chromosome fusion events involving the X and Y chromosomes, in addition to one subsequent fission event. Here, we isolate and characterize the four different karyotypes we discovered in this strain which we believe demonstrates remarkable genome instability. We discovered that one of the substrains with an X-autosome fusion has an X-to-Y chromosome nondisjunction rate 20 × higher than the D. virilis reference strain (21% vs 1%). Finally, we found an overall higher rate of DNA breakage in the substrain with higher satellite DNA compared to a genetically similar substrain with less satellite DNA. This suggests that satellite DNA abundance may play a role in the risk of genome instability. Overall, we introduce a novel system consisting of a single strain with four different karyotypes, which we believe will be useful for future studies of genome instability, centromere function, and sex chromosome evolution.
Collapse
Affiliation(s)
- Jullien M Flynn
- Department of Molecular Biology and Genetics, Cornell University, Biotechnology Building Room 227, Ithaca, NY 14853, USA
| | - Kevin B Hu
- Department of Molecular Biology and Genetics, Cornell University, Biotechnology Building Room 227, Ithaca, NY 14853, USA
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Biotechnology Building Room 227, Ithaca, NY 14853, USA
| |
Collapse
|
11
|
Kindelay SM, Maggert KA. Under the magnifying glass: The ups and downs of rDNA copy number. Semin Cell Dev Biol 2023; 136:38-48. [PMID: 35595601 PMCID: PMC9976841 DOI: 10.1016/j.semcdb.2022.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/27/2022] [Accepted: 05/09/2022] [Indexed: 11/22/2022]
Abstract
The ribosomal DNA (rDNA) in Drosophila is found as two additive clusters of individual 35 S cistrons. The multiplicity of rDNA is essential to assure proper translational demands, but the nature of the tandem arrays expose them to copy number variation within and between populations. Here, we discuss means by which a cell responds to insufficient rDNA copy number, including a historical view of rDNA magnification whose mechanism was inferred some 35 years ago. Recent work has revealed that multiple conditions may also result in rDNA loss, in response to which rDNA magnification may have evolved. We discuss potential models for the mechanism of magnification, and evaluate possible consequences of rDNA copy number variation.
Collapse
Affiliation(s)
- Selina M Kindelay
- Genetics Graduate Interdisciplinary Program, The University of Arizona, Tucson, AZ 85724, USA
| | - Keith A Maggert
- Genetics Graduate Interdisciplinary Program, The University of Arizona, Tucson, AZ 85724, USA; Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, AZ 85724, USA.
| |
Collapse
|
12
|
Vacarizas J, Taguchi T, Mezaki T, Manalili SE, Kawakami R, Kubota S. Cytogenetic evidence and dmrt linkage indicate male heterogamety in a non-bilaterian animal. PLoS One 2023; 18:e0285851. [PMID: 37200254 DOI: 10.1371/journal.pone.0285851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 05/02/2023] [Indexed: 05/20/2023] Open
Abstract
The diversity of sex determination systems in animals suggests that sex chromosomes evolve independently across different lineages. However, the present data on these systems is largely limited and represented mainly by bilaterian animals. Sex chromosomes and sex determination system based on cytogenetic evidence remain a mystery among non-bilaterians, the most basal animals. Here, we investigated the sex determination system of a non-bilaterian (Goniopora djiboutiensis) based on karyotypic analysis and identification of locus of dmrt1, a known master sex-determining gene in many animals. Results showed that among the three isolated dmrt genes, GddmrtC was sperm-linked. Fluorescence in situ hybridization revealed that 47% of the observed metaphase cells contained the GddmrtC locus on the shorter chromosome of the heteromorphic pair, whereas the other 53% contained no GddmrtC locus and pairing of the longer chromosome of the heteromorphic pair was observed. These findings provided the cytogenetic evidence for the existence of the Y sex chromosome in a non-bilaterian animal and supports male heterogamety as previously reported in other non-bilaterian species using RAD sequencing. The Y chromosome-specific GddmrtC sequence was most homologous to the vertebrate dmrt1, which is known for its role in male sex determination and differentiation. Our result on identification of putative sex chromosomes for G. djiboutiensis may contribute into understanding of the possible genetic sex determination systems in non-bilaterian animals.
Collapse
Affiliation(s)
- Joshua Vacarizas
- Kuroshio Science Program, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi, Japan
| | - Takahiro Taguchi
- Department of Nutrition, Faculty of Health Science, Kochi Gakuen University, Asahitenjin-Cho, Kochi, Japan
| | - Takuma Mezaki
- Kuroshio Biological Research Foundation, Otsuki, Hata County, Kochi, Japan
| | - Sam Edward Manalili
- Agriculture and Marine Science Program, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi, Japan
| | - Rei Kawakami
- Agriculture and Marine Science Program, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi, Japan
| | - Satoshi Kubota
- Kuroshio Science Unit, Multidisciplinary Science Cluster, Kochi University, Nankoku, Kochi, Japan
| |
Collapse
|
13
|
Homologous chromosomes are stably conjoined for Drosophila male meiosis I by SUM, a multimerized protein assembly with modules for DNA-binding and for separase-mediated dissociation co-opted from cohesin. PLoS Genet 2022; 18:e1010547. [DOI: 10.1371/journal.pgen.1010547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/20/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
For meiosis I, homologous chromosomes must be paired into bivalents. Maintenance of homolog conjunction in bivalents until anaphase I depends on crossovers in canonical meiosis. However, instead of crossovers, an alternative system achieves homolog conjunction during the achiasmate male meiosis of Drosophila melanogaster. The proteins SNM, UNO and MNM are likely constituents of a physical linkage that conjoins homologs in D. melanogaster spermatocytes. Here, we report that SNM binds tightly to the C-terminal region of UNO. This interaction is homologous to that of the cohesin subunits stromalin/Scc3/STAG and α-kleisin, as revealed by sequence similarities, structure modeling and cross-link mass spectrometry. Importantly, purified SU_C, the heterodimeric complex of SNM and the C-terminal region of UNO, displayed DNA-binding in vitro. DNA-binding was severely impaired by mutational elimination of positively charged residues from the C-terminal helix of UNO. Phenotypic analyses in flies fully confirmed the physiological relevance of this basic helix for chromosome-binding and homolog conjunction during male meiosis. Beyond DNA, SU_C also bound MNM, one of many isoforms expressed from the complex mod(mdg4) locus. This binding of MNM to SU_C was mediated by the MNM-specific C-terminal region, while the purified N-terminal part common to all Mod(mdg4) isoforms multimerized into hexamers in vitro. Similarly, the UNO N-terminal domain formed tetramers in vitro. Thus, we suggest that multimerization confers to SUM, the assemblies composed of SNM, UNO and MNM, the capacity to conjoin homologous chromosomes stably by the resultant multivalent DNA-binding. Moreover, to permit homolog separation during anaphase I, SUM is dissociated by separase, since UNO, the α-kleisin-related protein, includes a separase cleavage site. In support of this proposal, we demonstrate that UNO cleavage by tobacco etch virus protease is sufficient to release homolog conjunction in vivo after mutational exchange of the separase cleavage site with that of the bio-orthogonal protease.
Collapse
|
14
|
Rubin T, Macaisne N, Vallés AM, Guilleman C, Gaugué I, Dal Toe L, Huynh JR. Premeiotic pairing of homologous chromosomes during Drosophila male meiosis. Proc Natl Acad Sci U S A 2022; 119:e2207660119. [PMID: 36375065 PMCID: PMC9704699 DOI: 10.1073/pnas.2207660119] [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: 05/12/2022] [Accepted: 10/07/2022] [Indexed: 11/15/2022] Open
Abstract
In the early stages of meiosis, maternal and paternal chromosomes pair with their homologous partner and recombine to ensure exchange of genetic information and proper segregation. These events can vary drastically between species and between males and females of the same species. In Drosophila, in contrast to females, males do not form synaptonemal complexes (SCs), do not recombine, and have no crossing over; yet, males are able to segregate their chromosomes properly. Here, we investigated the early steps of homolog pairing in Drosophila males. We found that homolog centromeres are not paired in germline stem cells (GSCs) and become paired in the mitotic region before meiotic entry, similarly to females. Surprisingly, male germline cells express SC proteins, which localize to centromeres and promote pairing. We further found that the SUN/KASH (LINC) complex and microtubules are required for homolog pairing as in females. Chromosome movements in males, however, are much slower than in females and we demonstrate that this slow dynamic is compensated in males by having longer cell cycles. In agreement, slowing down cell cycles was sufficient to rescue pairing-defective mutants in female meiosis. Our results demonstrate that although meiosis differs significantly between males and females, sex-specific cell cycle kinetics integrate similar molecular mechanisms to achieve proper centromere pairing.
Collapse
Affiliation(s)
- Thomas Rubin
- Center for Interdisciplinary Research in Biology, CNRS UMR 7241, INSERM U1050, Collège de France and Paris Sciences & Lettres Research University, 75231 Paris Cedex 05, France
| | | | - Ana Maria Vallés
- Center for Interdisciplinary Research in Biology, CNRS UMR 7241, INSERM U1050, Collège de France and Paris Sciences & Lettres Research University, 75231 Paris Cedex 05, France
| | - Clara Guilleman
- Center for Interdisciplinary Research in Biology, CNRS UMR 7241, INSERM U1050, Collège de France and Paris Sciences & Lettres Research University, 75231 Paris Cedex 05, France
| | - Isabelle Gaugué
- Department of Genetics and Developmental Biology, CNRS UMR 3215, INSERM U934, Institut Curie, 75005 Paris, France
| | - Laurine Dal Toe
- Center for Interdisciplinary Research in Biology, CNRS UMR 7241, INSERM U1050, Collège de France and Paris Sciences & Lettres Research University, 75231 Paris Cedex 05, France
| | - Jean-René Huynh
- Center for Interdisciplinary Research in Biology, CNRS UMR 7241, INSERM U1050, Collège de France and Paris Sciences & Lettres Research University, 75231 Paris Cedex 05, France
| |
Collapse
|
15
|
Kabakci Z, Yamada H, Vernizzi L, Gupta S, Weber J, Sun MS, Lehner CF. Teflon promotes chromosomal recruitment of homolog conjunction proteins during Drosophila male meiosis. PLoS Genet 2022; 18:e1010469. [PMID: 36251690 PMCID: PMC9612826 DOI: 10.1371/journal.pgen.1010469] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/27/2022] [Accepted: 10/10/2022] [Indexed: 11/05/2022] Open
Abstract
Meiosis in males of higher dipterans is achiasmate. In their spermatocytes, pairing of homologs into bivalent chromosomes does not include synaptonemal complex and crossover formation. While crossovers preserve homolog conjunction until anaphase I during canonical meiosis, an alternative system is used in dipteran males. Mutant screening in Drosophila melanogaster has identified teflon (tef) as being required specifically for alternative homolog conjunction (AHC) of autosomal bivalents. The additional known AHC genes, snm, uno and mnm, are needed for the conjunction of autosomal homologs and of sex chromosomes. Here, we have analyzed the pattern of TEF protein expression. TEF is present in early spermatocytes but cannot be detected on bivalents at the onset of the first meiotic division, in contrast to SNM, UNO and MNM (SUM). TEF binds to polytene chromosomes in larval salivary glands, recruits MNM by direct interaction and thereby, indirectly, also SNM and UNO. However, chromosomal SUM association is not entirely dependent on TEF, and residual autosome conjunction occurs in tef null mutant spermatocytes. The higher tef requirement for autosomal conjunction is likely linked to the quantitative difference in the amount of SUM protein that provides conjunction of autosomes and sex chromosomes, respectively. During normal meiosis, SUM proteins are far more abundant on sex chromosomes compared to autosomes. Beyond promoting SUM recruitment, TEF has a stabilizing effect on SUM proteins. Increased SUM causes excess conjunction and consequential chromosome missegregation during meiosis I after co-overexpression. Similarly, expression of SUM without TEF, and even more potently with TEF, interferes with chromosome segregation during anaphase of mitotic divisions in somatic cells, suggesting that the known AHC proteins are sufficient for establishment of ectopic chromosome conjunction. Overall, our findings suggest that TEF promotes alternative homolog conjunction during male meiosis without being part of the final physical linkage between chromosomes. Sexual reproduction depends on meiosis, a special cell division that generates haploid cells. Haploid cells have only one set of chromosomes in contrast to the diploid precursor cell, which has two sets. Haploid cells can differentiate into gametes. Fusion of two gametes during fertilization recreates the diploid state. Meiosis is distinct in males and females to produce two distinct types of compatible gametes, sperm and egg. In the fly Drosophila melanogaster, sex-specific differences are particularly pronounced. While pairing of homologous chromosomes into bivalents early in meiosis proceeds in a canonical manner in females, males use an alternative system. This system maintains homolog pairing, replacing crossovers that result from homologous recombination during canonical meiosis. Four genes (snm, uno, mnm and tef) are known to be required specifically for alternative homolog conjunction in males. Here, we demonstrate that the TEF protein binds directly to MNM. Thereby, TEF promotes the recruitment of MNM and consequentially SNM and UNO to chromosomes. However, while SNM, UNO and MNM remain on bivalent chromosomes until they are separated apart during the first meiotic division, TEF disappears prematurely, suggesting that it is not part of the final physical linkage between homologous chromosomes.
Collapse
Affiliation(s)
- Zeynep Kabakci
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Hiro Yamada
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Luisa Vernizzi
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Samir Gupta
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Joe Weber
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Michael Shoujie Sun
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Christian F. Lehner
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
- * E-mail:
| |
Collapse
|
16
|
Bowman JL, Arteaga-Vazquez M, Berger F, Briginshaw LN, Carella P, Aguilar-Cruz A, Davies KM, Dierschke T, Dolan L, Dorantes-Acosta AE, Fisher TJ, Flores-Sandoval E, Futagami K, Ishizaki K, Jibran R, Kanazawa T, Kato H, Kohchi T, Levins J, Lin SS, Nakagami H, Nishihama R, Romani F, Schornack S, Tanizawa Y, Tsuzuki M, Ueda T, Watanabe Y, Yamato KT, Zachgo S. The renaissance and enlightenment of Marchantia as a model system. THE PLANT CELL 2022; 34:3512-3542. [PMID: 35976122 PMCID: PMC9516144 DOI: 10.1093/plcell/koac219] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 06/21/2022] [Indexed: 05/07/2023]
Abstract
The liverwort Marchantia polymorpha has been utilized as a model for biological studies since the 18th century. In the past few decades, there has been a Renaissance in its utilization in genomic and genetic approaches to investigating physiological, developmental, and evolutionary aspects of land plant biology. The reasons for its adoption are similar to those of other genetic models, e.g. simple cultivation, ready access via its worldwide distribution, ease of crossing, facile genetics, and more recently, efficient transformation, genome editing, and genomic resources. The haploid gametophyte dominant life cycle of M. polymorpha is conducive to forward genetic approaches. The lack of ancient whole-genome duplications within liverworts facilitates reverse genetic approaches, and possibly related to this genomic stability, liverworts possess sex chromosomes that evolved in the ancestral liverwort. As a representative of one of the three bryophyte lineages, its phylogenetic position allows comparative approaches to provide insights into ancestral land plants. Given the karyotype and genome stability within liverworts, the resources developed for M. polymorpha have facilitated the development of related species as models for biological processes lacking in M. polymorpha.
Collapse
Affiliation(s)
| | - Mario Arteaga-Vazquez
- Instituto de Biotecnología y Ecología Aplicada, Universidad Veracruzana, Xalapa VER 91090, México
| | - Frederic Berger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna 1030, Austria
| | - Liam N Briginshaw
- School of Biological Sciences, Monash University, Melbourne VIC 3800, Australia
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, Monash University, Melbourne VIC 3800, Australia
| | - Philip Carella
- Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK
| | - Adolfo Aguilar-Cruz
- Instituto de Biotecnología y Ecología Aplicada, Universidad Veracruzana, Xalapa VER 91090, México
| | - Kevin M Davies
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North 4442, New Zealand
| | - Tom Dierschke
- School of Biological Sciences, Monash University, Melbourne VIC 3800, Australia
| | - Liam Dolan
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna 1030, Austria
| | - Ana E Dorantes-Acosta
- Instituto de Biotecnología y Ecología Aplicada, Universidad Veracruzana, Xalapa VER 91090, México
| | - Tom J Fisher
- School of Biological Sciences, Monash University, Melbourne VIC 3800, Australia
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, Monash University, Melbourne VIC 3800, Australia
| | - Eduardo Flores-Sandoval
- School of Biological Sciences, Monash University, Melbourne VIC 3800, Australia
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, Monash University, Melbourne VIC 3800, Australia
| | - Kazutaka Futagami
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
| | | | - Rubina Jibran
- The New Zealand Institute for Plant & Food Research Limited, Auckland 1142, New Zealand
| | - Takehiko Kanazawa
- Division of Cellular Dynamics, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan
- The Department of Basic Biology, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8585, Japan
| | - Hirotaka Kato
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
- Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Jonathan Levins
- School of Biological Sciences, Monash University, Melbourne VIC 3800, Australia
| | - Shih-Shun Lin
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan
| | - Hirofumi Nakagami
- Basic Immune System of Plants, Max-Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Ryuichi Nishihama
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Facundo Romani
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | | | - Yasuhiro Tanizawa
- Department of Informatics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Masayuki Tsuzuki
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
| | - Takashi Ueda
- Division of Cellular Dynamics, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi 444-8585, Japan
- The Department of Basic Biology, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8585, Japan
| | - Yuichiro Watanabe
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
| | - Katsuyuki T Yamato
- Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Wakayama 649-6493, Japan
| | - Sabine Zachgo
- Division of Botany, School of Biology and Chemistry, Osnabrück University, Osnabrück 49076, Germany
| |
Collapse
|
17
|
Billmyre KK. Chromosome-specific behaviors during early meiosis. Curr Top Dev Biol 2022; 151:127-154. [PMID: 36681468 DOI: 10.1016/bs.ctdb.2022.05.002] [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: 01/25/2023]
Abstract
Inheriting the wrong number of chromosomes is one of the leading causes of infertility and birth defects in humans. However, in many organisms, individual chromosomes vary dramatically in both organization, sequence, and size. Chromosome segregation systems must be capable of accounting for these differences to reliably segregate chromosomes. During gametogenesis, meiosis ensures that all chromosomes segregate properly into gametes (i.e., egg or sperm). Interestingly, not all chromosomes exhibit the same dynamics during meiosis, which can lead to chromosome-specific behaviors and defects. This review will summarize some of the chromosome-specific meiotic events that are currently known and discuss their impact on meiotic outcomes.
Collapse
|
18
|
Vernizzi L, Lehner CF. Dispersive forces and resisting spot welds by alternative homolog conjunction govern chromosome shape in Drosophila spermatocytes during prophase I. PLoS Genet 2022; 18:e1010327. [PMID: 35895750 PMCID: PMC9359577 DOI: 10.1371/journal.pgen.1010327] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 08/08/2022] [Accepted: 07/05/2022] [Indexed: 11/19/2022] Open
Abstract
The bivalent chromosomes that are generated during prophase of meiosis I comprise a pair of homologous chromosomes. Homolog pairing during prophase I must include mechanisms that avoid or eliminate entanglements between non-homologous chromosomes. In Drosophila spermatocytes, non-homologous associations are disrupted by chromosome territory formation, while linkages between homologous chromosomes are maintained by special conjunction proteins. These proteins function as alternative for crossovers that link homologs during canonical meiosis but are absent during the achiasmate Drosophila male meiosis. How and where within bivalents the alternative homolog conjunction proteins function is still poorly understood. To clarify the rules that govern territory formation and alternative homolog conjunction, we have analyzed spermatocytes with chromosomal aberrations. We examined territory formation after acute chromosome cleavage by Cas9, targeted to the dodeca satellite adjacent to the centromere of chromosome 3 specifically in spermatocytes. Moreover, we studied territory organization, as well as the eventual orientation of chromosomes during meiosis I, in spermatocytes with stable structural aberrations, including heterozygous reciprocal autosomal translocations. Our observations indicate that alternative homolog conjunction is applied in a spatially confined manner. Comparable to crossovers, only a single conjunction spot per chromosome arm appears to be applied usually. These conjunction spots resist separation by the dispersing forces that drive apart homologous pericentromeric heterochromatin and embedded centromeres within territories, as well as the distinct chromosomal entities into peripheral, maximally separated territories within the spermatocyte nucleus. Already the primordial eukaryote appears to have used meiosis for sexual reproduction, because this sophisticated process follows a canonical program in lineages ranging from unicellular organisms to plants and animals. The maternal and paternal copies of a particular chromosome, i.e., the homologs, are first physically linked into a bivalent before the first meiotic division. Linkage is essential for error-free chromosome segregation. In canonical meiosis, linkage is achieved by crossovers. These are regulated so that each chromosome pair is linked, but only by very few crossovers. Surprisingly, crossovers are absent during meiosis in males of the fruit fly Drosophila melanogaster. Instead, an alternative homolog conjunction system is used. It is not yet clear how this functions. Here, we demonstrate that the alternative chromosome glue appears to be applied in a locally restricted manner rather than all along the paired homologs. Just two spots of glue appear to conjoin the two homologous chromosomes usually, with one spot linking the left and another the right chromosome arm. Thus, number and location of linkages appear to be similar as crossovers, raising the possibility of mechanistic similarities in the establishment of the two distinct types of homolog linkage.
Collapse
Affiliation(s)
- Luisa Vernizzi
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Christian F. Lehner
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
- * E-mail:
| |
Collapse
|
19
|
Kotov AA, Bazylev SS, Adashev VE, Shatskikh AS, Olenina LV. Drosophila as a Model System for Studying of the Evolution and Functional Specialization of the Y Chromosome. Int J Mol Sci 2022; 23:ijms23084184. [PMID: 35457001 PMCID: PMC9031259 DOI: 10.3390/ijms23084184] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/06/2022] [Accepted: 04/07/2022] [Indexed: 02/07/2023] Open
Abstract
The Y chromosome is one of the sex chromosomes found in males of animals of different taxa, including insects and mammals. Among all chromosomes, the Y chromosome is characterized by a unique chromatin landscape undergoing dynamic evolutionary change. Being entirely heterochromatic, the Y chromosome as a rule preserves few functional genes, but is enriched in tandem repeats and transposons. Due to difficulties in the assembly of the highly repetitive Y chromosome sequence, deep analyses of Y chromosome evolution, structure, and functions are limited to a few species, one of them being Drosophila melanogaster. Despite Y chromosomes exhibiting high structural divergence between even closely related species, Y-linked genes have evolved convergently and are mainly associated with spermatogenesis-related activities. This indicates that male-specific selection is a dominant force shaping evolution of Y chromosomes across species. This review presents our analysis of current knowledge concerning Y chromosome functions, focusing on recent findings in Drosophila. Here we dissect the experimental and bioinformatics data about the Y chromosome accumulated to date in Drosophila species, providing comparative analysis with mammals, and discussing the relevance of our analysis to a wide range of eukaryotic organisms, including humans.
Collapse
|
20
|
Stocker AJ, Schiffer M, Gorab E, Hoffmann A. Chromosome Comparisons of Australian Scaptodrosophila Species. INSECTS 2022; 13:insects13040364. [PMID: 35447805 PMCID: PMC9024860 DOI: 10.3390/insects13040364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/31/2022] [Accepted: 04/05/2022] [Indexed: 01/27/2023]
Abstract
The Scaptodrosophila represent a diverse group of Diptera closely related to Drosophila. Although they have radiated extensively in Australia, they have been the focus of few studies. Here, we characterized the karyotypes of 12 Scaptodrosophila species from several species groups and showed that they have undergone similar types of karyotypic change to those seen in Drosophila. This includes heterochromatin amplification involved in length changes of the sex and ‘dot’ chromosomes as well as the autosomes, particularly in the coracina group of species. Numerous weak points along the arms of the polytene chromosomes suggest the presence of internal repetitive sequence DNA, but these regions did not C-band in mitotic chromosomes, and their analysis will depend on DNA sequencing. The nucleolar organizing regions (NORs) are at the same chromosome positions in Scaptodrosophila as in Drosophila, and the various mechanisms responsible for changing arm configurations also appear to be the same. These chromosomal studies provide a complementary resource to other investigations of this group, with several species currently being sequenced.
Collapse
Affiliation(s)
- Ann Jacob Stocker
- Pest and Environmental Adaptation Research Group, School of Biosciences, Bio21 Institute, University of Melbourne, Parkville, VIC 3010, Australia;
- Correspondence:
| | - Michele Schiffer
- Daintree Rainforest Observatory, James Cook University, Cape Tribulation, QLD 4873, Australia;
| | - Eduardo Gorab
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, Cidade Universitária, São Paulo 05508-090, SP, Brazil;
| | - Ary Hoffmann
- Pest and Environmental Adaptation Research Group, School of Biosciences, Bio21 Institute, University of Melbourne, Parkville, VIC 3010, Australia;
| |
Collapse
|
21
|
Chang CH, Gregory LE, Gordon KE, Meiklejohn CD, Larracuente AM. Unique structure and positive selection promote the rapid divergence of Drosophila Y chromosomes. eLife 2022; 11:e75795. [PMID: 34989337 PMCID: PMC8794474 DOI: 10.7554/elife.75795] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 12/18/2021] [Indexed: 02/06/2023] Open
Abstract
Y chromosomes across diverse species convergently evolve a gene-poor, heterochromatic organization enriched for duplicated genes, LTR retrotransposons, and satellite DNA. Sexual antagonism and a loss of recombination play major roles in the degeneration of young Y chromosomes. However, the processes shaping the evolution of mature, already degenerated Y chromosomes are less well-understood. Because Y chromosomes evolve rapidly, comparisons between closely related species are particularly useful. We generated de novo long-read assemblies complemented with cytological validation to reveal Y chromosome organization in three closely related species of the Drosophila simulans complex, which diverged only 250,000 years ago and share >98% sequence identity. We find these Y chromosomes are divergent in their organization and repetitive DNA composition and discover new Y-linked gene families whose evolution is driven by both positive selection and gene conversion. These Y chromosomes are also enriched for large deletions, suggesting that the repair of double-strand breaks on Y chromosomes may be biased toward microhomology-mediated end joining over canonical non-homologous end-joining. We propose that this repair mechanism contributes to the convergent evolution of Y chromosome organization across organisms.
Collapse
Affiliation(s)
- Ching-Ho Chang
- Department of Biology, University of RochesterRochesterUnited States
| | - Lauren E Gregory
- Department of Biology, University of RochesterRochesterUnited States
| | - Kathleen E Gordon
- School of Biological Sciences, University of Nebraska-LincolnLincolnUnited States
| | - Colin D Meiklejohn
- School of Biological Sciences, University of Nebraska-LincolnLincolnUnited States
| | | |
Collapse
|
22
|
Vernizzi L, Lehner CF. Bivalent individualization during chromosome territory formation in Drosophila spermatocytes by controlled condensin II protein activity and additional force generators. PLoS Genet 2021; 17:e1009870. [PMID: 34669718 PMCID: PMC8559962 DOI: 10.1371/journal.pgen.1009870] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/01/2021] [Accepted: 10/11/2021] [Indexed: 12/12/2022] Open
Abstract
Reduction of genome ploidy from diploid to haploid necessitates stable pairing of homologous chromosomes into bivalents before the start of the first meiotic division. Importantly, this chromosome pairing must avoid interlocking of non-homologous chromosomes. In spermatocytes of Drosophila melanogaster, where homolog pairing does not involve synaptonemal complex formation and crossovers, associations between non-homologous chromosomes are broken up by chromosome territory formation in early spermatocytes. Extensive non-homologous associations arise from the coalescence of the large blocks of pericentromeric heterochromatin into a chromocenter and from centromere clustering. Nevertheless, during territory formation, bivalents are moved apart into spatially separate subnuclear regions. The condensin II subunits, Cap-D3 and Cap-H2, have been implicated, but the remarkable separation of bivalents during interphase might require more than just condensin II. For further characterization of this process, we have applied time-lapse imaging using fluorescent markers of centromeres, telomeres and DNA satellites in pericentromeric heterochromatin. We describe the dynamics of the disruption of centromere clusters and the chromocenter in normal spermatocytes. Mutations in Cap-D3 and Cap-H2 abolish chromocenter disruption, resulting in excessive chromosome missegregation during M I. Chromocenter persistence in the mutants is not mediated by the special system, which conjoins homologs in compensation for the absence of crossovers in Drosophila spermatocytes. However, overexpression of Cap-H2 precluded conjunction between autosomal homologs, resulting in random segregation of univalents. Interestingly, Cap-D3 and Cap-H2 mutant spermatocytes displayed conspicuous stretching of the chromocenter, as well as occasional chromocenter disruption, suggesting that territory formation might involve forces unrelated to condensin II. While the molecular basis of these forces remains to be clarified, they are not destroyed by inhibitors of F actin and microtubules. Our results indicate that condensin II activity promotes chromosome territory formation in co-operation with additional force generators and that careful co-ordination with alternative homolog conjunction is crucial.
Collapse
Affiliation(s)
- Luisa Vernizzi
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Christian F. Lehner
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| |
Collapse
|
23
|
Huang W, Liu Z, Rong YS. Dynamic localization of DNA topoisomerase I and its functional relevance during Drosophila development. G3-GENES GENOMES GENETICS 2021; 11:6298592. [PMID: 34544118 PMCID: PMC8661406 DOI: 10.1093/g3journal/jkab202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 06/09/2021] [Indexed: 11/23/2022]
Abstract
DNA topoisomerase I (Top1) maintains chromatin conformation during transcription. While Top1 is not essential in simple eukaryotic organisms such as yeast, it is required for the development of multicellular organisms. In fact, tissue and cell-type-specific functions of Top1 have been suggested in the fruit fly Drosophila. A better understanding of Top1’s function in the context of development is important as Top1 inhibitors are among the most widely used anticancer drugs. As a step toward such a better understanding, we studied its localization in live cells of Drosophila. Consistent with prior results, Top1 is highly enriched at the nucleolus in transcriptionally active polyploid cells, and this enrichment responds to perturbation of transcription. In diploid cells, we uncovered evidence for Top1 foci formation at genomic regions not limited to the active rDNA locus, suggestive of novel regulation of Top1 recruitment. In the male germline, Top1 is highly enriched at the paired rDNA loci on sex chromosomes suggesting that it might participate in regulating their segregation during meiosis. Results from RNAi-mediated Top1 knockdown lend support to this hypothesis. Our study has provided one of the most comprehensive descriptions of Top1 localization during animal development.
Collapse
Affiliation(s)
- Wuqiang Huang
- School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong Province, 510275, China.,Hengyang College of Medicine, University of South China, Hengyang 421001, China
| | - Zhiping Liu
- School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong Province, 510275, China
| | - Yikang S Rong
- Hengyang College of Medicine, University of South China, Hengyang 421001, China
| |
Collapse
|
24
|
Cytogenetic markers using single-sequence probes reveal chromosomal locations of tandemly repetitive genes in scleractinian coral Acropora pruinosa. Sci Rep 2021; 11:11326. [PMID: 34059722 PMCID: PMC8167085 DOI: 10.1038/s41598-021-90580-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/13/2021] [Indexed: 02/04/2023] Open
Abstract
The short and similar sized chromosomes of Acropora pose a challenge for karyotyping. Conventional methods, such as staining of heterochromatic regions, provide unclear banding patterns that hamper identification of such chromosomes. In this study, we used short single-sequence probes from tandemly repetitive 5S ribosomal RNA (rRNA) and core histone coding sequences to identify specific chromosomes of Acropora pruinosa. Both the probes produced intense signals in fluorescence in situ hybridization, which distinguished chromosome pairs. The locus of the 5S rDNA probe was on chromosome 5, whereas that of core histone probe was on chromosome 8. The sequence of the 5S rDNA probe was composed largely of U1 and U2 spliceosomal small nuclear RNA (snRNA) genes and their interspacers, flanked by short sequences of the 5S rDNA. This is the first report of a tandemly repetitive linkage of snRNA and 5S rDNA sequences in Cnidaria. Based on the constructed tentative karyogram and whole genome hybridization, the longest chromosome pair (chromosome 1) was heteromorphic. The probes also hybridized effectively with chromosomes of other Acropora species and population, revealing an additional core histone gene locus. We demonstrated the applicability of short-sequence probes as chromosomal markers with potential for use across populations and species of Acropora.
Collapse
|
25
|
Ávila Herrera IM, Král J, Pastuchová M, Forman M, Musilová J, Kořínková T, Šťáhlavský F, Zrzavá M, Nguyen P, Just P, Haddad CR, Hiřman M, Koubová M, Sadílek D, Huber BA. Evolutionary pattern of karyotypes and meiosis in pholcid spiders (Araneae: Pholcidae): implications for reconstructing chromosome evolution of araneomorph spiders. BMC Ecol Evol 2021; 21:75. [PMID: 33941079 PMCID: PMC8091558 DOI: 10.1186/s12862-021-01750-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 01/25/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Despite progress in genomic analysis of spiders, their chromosome evolution is not satisfactorily understood. Most information on spider chromosomes concerns the most diversified clade, entelegyne araneomorphs. Other clades are far less studied. Our study focused on haplogyne araneomorphs, which are remarkable for their unusual sex chromosome systems and for the co-evolution of sex chromosomes and nucleolus organizer regions (NORs); some haplogynes exhibit holokinetic chromosomes. To trace the karyotype evolution of haplogynes on the family level, we analysed the number and morphology of chromosomes, sex chromosomes, NORs, and meiosis in pholcids, which are among the most diverse haplogyne families. The evolution of spider NORs is largely unknown. RESULTS Our study is based on an extensive set of species representing all major pholcid clades. Pholcids exhibit a low 2n and predominance of biarmed chromosomes, which are typical haplogyne features. Sex chromosomes and NOR patterns of pholcids are diversified. We revealed six sex chromosome systems in pholcids (X0, XY, X1X20, X1X2X30, X1X2Y, and X1X2X3X4Y). The number of NOR loci ranges from one to nine. In some clades, NORs are also found on sex chromosomes. CONCLUSIONS The evolution of cytogenetic characters was largely derived from character mapping on a recently published molecular phylogeny of the family. Based on an extensive set of species and mapping of their characters, numerous conclusions regarding the karyotype evolution of pholcids and spiders can be drawn. Our results suggest frequent autosome-autosome and autosome-sex chromosome rearrangements during pholcid evolution. Such events have previously been attributed to the reproductive isolation of species. The peculiar X1X2Y system is probably ancestral for haplogynes. Chromosomes of the X1X2Y system differ considerably in their pattern of evolution. In some pholcid clades, the X1X2Y system has transformed into the X1X20 or XY systems, and subsequently into the X0 system. The X1X2X30 system of Smeringopus pallidus probably arose from the X1X20 system by an X chromosome fission. The X1X2X3X4Y system of Kambiwa probably evolved from the X1X2Y system by integration of a chromosome pair. Nucleolus organizer regions have frequently expanded on sex chromosomes, most probably by ectopic recombination. Our data suggest the involvement of sex chromosome-linked NORs in achiasmatic pairing.
Collapse
Affiliation(s)
- Ivalú M. Ávila Herrera
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Jiří Král
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Markéta Pastuchová
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Martin Forman
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Jana Musilová
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
- Research Team of Plant Stress Biology and Biotechnology, Division of Crop Genetics and Breeding, Crop Research Institute, Drnovská 507/73, 161 00 Prague 6, Czech Republic
| | - Tereza Kořínková
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
- Prague 1, Czech Republic
| | - František Šťáhlavský
- Invertebrate Zoology Unit, Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 44 Prague 2, Czech Republic
| | - Magda Zrzavá
- Laboratory of Molecular Cytogenetics, Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
- Laboratory of Molecular Cytogenetics, Department of Molecular Biology and Genetics, Institute of Entomology, Biology Centre CAS, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Petr Nguyen
- Laboratory of Molecular Cytogenetics, Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
- Laboratory of Molecular Cytogenetics, Department of Molecular Biology and Genetics, Institute of Entomology, Biology Centre CAS, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Pavel Just
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
- Invertebrate Zoology Unit, Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 44 Prague 2, Czech Republic
| | - Charles R. Haddad
- Research Group of Arachnid Systematics and Ecology, Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300 Republic of South Africa
| | - Matyáš Hiřman
- Invertebrate Zoology Unit, Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 44 Prague 2, Czech Republic
| | - Martina Koubová
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - David Sadílek
- Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
- Invertebrate Zoology Unit, Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 44 Prague 2, Czech Republic
| | - Bernhard A. Huber
- Arachnida Section, Alexander Koenig Zoological Research Museum, Adenauerallee 160, 53113 Bonn, Germany
| |
Collapse
|
26
|
Kostmann A, Kratochvíl L, Rovatsos M. First Report of Sex Chromosomes in Plated Lizards (Squamata: Gerrhosauridae). Sex Dev 2021; 14:60-65. [PMID: 33647904 DOI: 10.1159/000513764] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/11/2020] [Indexed: 11/19/2022] Open
Abstract
Squamate reptiles show high diversity in sex determination ranging from environmental sex determination to genotypic sex determination with varying degrees of differentiation of sex chromosomes. Unfortunately, we lack even basic information on sex determination mode in several lineages of squamates, which prevents full understanding of their diversity and evolution of sex determination. One of the reptilian lineages with missing information on sex determination is the family Gerrhosauridae, commonly known as the plated lizards. Several species of gerrhosaurids have been studied in the past by conventional cytogenetic methods, but sex-specific differences were not identified. In this study, we applied both conventional and molecular cytogenetic methods to metaphases from both sexes of the Peters' keeled plated lizard (Tracheloptychus petersi). We identified accumulations of rDNA loci in a pair of microchromosomes in metaphases from males, but only in a single microchromosome in females. The restriction of the observed heterozygosity to females suggests a putative ZZ/ZW system of sex chromosomes, which represents the first report of sex chromosomes in a gerrhosaurid lizard. The lack of sex-specific signals in all other cytogenetic methods implies that the sex chromosomes of T. petersi are poorly differentiated in sequence content.
Collapse
Affiliation(s)
- Alexander Kostmann
- Department of Ecology, Faculty of Science, Charles University, Prague, Czechia
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czechia
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, Prague, Czechia,
| |
Collapse
|
27
|
Miller DE. The Interchromosomal Effect: Different Meanings for Different Organisms. Genetics 2020; 216:621-631. [PMID: 33158985 PMCID: PMC7648586 DOI: 10.1534/genetics.120.303656] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 09/15/2020] [Indexed: 11/18/2022] Open
Abstract
The term interchromosomal effect was originally used to describe a change in the distribution of exchange in the presence of an inversion. First characterized in the 1920s by early Drosophila researchers, it has been observed in multiple organisms. Nearly half a century later, the term began to appear in the human genetics literature to describe the hypothesis that parental chromosome differences, such as translocations or inversions, may increase the frequency of meiotic chromosome nondisjunction. Although it remains unclear if chromosome aberrations truly affect the segregation of structurally normal chromosomes in humans, the use of the term interchromosomal effect in this context persists. This article explores the history of the use of the term interchromosomal effect and discusses how chromosomes with structural aberrations are segregated during meiosis.
Collapse
Affiliation(s)
- Danny E Miller
- Department of Pediatrics, Division of Genetic Medicine, University of Washington and Seattle Children's Hospital, Seattle, WA 98105
| |
Collapse
|
28
|
Adams EE, He Q, McKee BD. How noncrossover homologs are conjoined and segregated in Drosophila male meiosis I: Stable but reversible homolog linkers require a novel Separase target protein. PLoS Genet 2020; 16:e1008997. [PMID: 33002007 PMCID: PMC7529219 DOI: 10.1371/journal.pgen.1008997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Elsie E. Adams
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Qiutao He
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Bruce D. McKee
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, United States of America
- Genome Science and Technology Program, University of Tennessee, Knoxville, Tennessee, United States of America
| |
Collapse
|
29
|
Weber J, Kabakci Z, Chaurasia S, Brunner E, Lehner CF. Chromosome separation during Drosophila male meiosis I requires separase-mediated cleavage of the homolog conjunction protein UNO. PLoS Genet 2020; 16:e1008928. [PMID: 33001976 PMCID: PMC7529252 DOI: 10.1371/journal.pgen.1008928] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/10/2020] [Indexed: 12/11/2022] Open
Abstract
Regular chromosome segregation during the first meiotic division requires prior pairing of homologous chromosomes into bivalents. During canonical meiosis, linkage between homologous chromosomes is maintained until late metaphase I by chiasmata resulting from meiotic recombination in combination with distal sister chromatid cohesion. Separase-mediated elimination of cohesin from chromosome arms at the end of metaphase I permits terminalization of chiasmata and homolog segregation to opposite spindle poles during anaphase I. Interestingly, separase is also required for bivalent splitting during meiosis I in Drosophila males, where homologs are conjoined by an alternative mechanism independent of meiotic recombination and cohesin. Here we report the identification of a novel alternative homolog conjunction protein encoded by the previously uncharacterized gene univalents only (uno). The univalents that are present in uno null mutants at the start of meiosis I, instead of normal bivalents, are segregated randomly. In wild type, UNO protein is detected in dots associated with bivalent chromosomes and most abundantly at the localized pairing site of the sex chromosomes. UNO is cleaved by separase. Expression of a mutant UNO version with a non-functional separase cleavage site restores homolog conjunction in a uno null background. However, separation of bivalents during meiosis I is completely abrogated by this non-cleavable UNO version. Therefore, we propose that homolog separation during Drosophila male meiosis I is triggered by separase-mediated cleavage of UNO.
Collapse
Affiliation(s)
- Joe Weber
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Zeynep Kabakci
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Soumya Chaurasia
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Erich Brunner
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| | - Christian F. Lehner
- Department of Molecular Life Science (DMLS), University of Zurich, Zurich, Switzerland
| |
Collapse
|
30
|
Mixing and Matching Chromosomes during Female Meiosis. Cells 2020; 9:cells9030696. [PMID: 32178277 PMCID: PMC7140621 DOI: 10.3390/cells9030696] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/08/2020] [Accepted: 03/11/2020] [Indexed: 01/17/2023] Open
Abstract
Meiosis is a key event in the manufacturing of an oocyte. During this process, the oocyte creates a set of unique chromosomes by recombining paternal and maternal copies of homologous chromosomes, and by eliminating one set of chromosomes to become haploid. While meiosis is conserved among sexually reproducing eukaryotes, there is a bewildering diversity of strategies among species, and sometimes within sexes of the same species, to achieve proper segregation of chromosomes. Here, we review the very first steps of meiosis in females, when the maternal and paternal copies of each homologous chromosomes have to move, find each other and pair. We explore the similarities and differences observed in C. elegans, Drosophila, zebrafish and mouse females.
Collapse
|
31
|
Hylton CA, Hansen K, Bourgeois A, Tomkiel Dean JE. Sex Chromosome Pairing Mediated by Euchromatic Homology in Drosophila Male Meiosis. Genetics 2020; 214:605-616. [PMID: 31915134 PMCID: PMC7054017 DOI: 10.1534/genetics.119.302936] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/03/2020] [Indexed: 01/15/2023] Open
Abstract
Diploid germline cells must undergo two consecutive meiotic divisions before differentiating as haploid sex cells. During meiosis I, homologs pair and remain conjoined until segregation at anaphase. Drosophila melanogaster spermatocytes are unique in that the canonical events of meiosis I including synaptonemal complex formation, double-strand DNA breaks, and chiasmata are absent. Sex chromosomes pair at intergenic spacer sequences within the ribosomal DNA (rDNA). Autosomes pair at numerous euchromatic homologies, but not at heterochromatin, suggesting that pairing may be limited to specific sequences. However, previous work generated from genetic segregation assays or observations of late prophase I/prometaphase I chromosome associations fail to differentiate pairing from maintenance of pairing (conjunction). Here, we separately examined the capability of X euchromatin to pair and conjoin using an rDNA-deficient X and a series of Dp(1;Y) chromosomes. Genetic assays showed that duplicated X euchromatin can substitute for endogenous rDNA pairing sites. Segregation was not proportional to homology length, and pairing could be mapped to nonoverlapping sequences within a single Dp(1;Y) Using fluorescence in situ hybridization to early prophase I spermatocytes, we showed that pairing occurred with high fidelity at all homologies tested. Pairing was unaffected by the presence of X rDNA, nor could it be explained by rDNA magnification. By comparing genetic and cytological data, we determined that centromere proximal pairings were best at segregation. Segregation was dependent on the conjunction protein Stromalin in Meiosis, while the autosomal-specific Teflon was dispensable. Overall, our results suggest that pairing may occur at all homologies, but there may be sequence or positional requirements for conjunction.
Collapse
Affiliation(s)
- Christopher A Hylton
- Department of Biology, University of North Carolina, Greensboro, North Carolina 27402
| | - Katie Hansen
- Department of Biology, University of North Carolina, Greensboro, North Carolina 27402
| | - Andrew Bourgeois
- Department of Biology, University of North Carolina, Greensboro, North Carolina 27402
| | - John E Tomkiel Dean
- Department of Biology, University of North Carolina, Greensboro, North Carolina 27402
| |
Collapse
|
32
|
Taxiarchi C, Kranjc N, Kriezis A, Kyrou K, Bernardini F, Russell S, Nolan T, Crisanti A, Galizi R. High-resolution transcriptional profiling of Anopheles gambiae spermatogenesis reveals mechanisms of sex chromosome regulation. Sci Rep 2019; 9:14841. [PMID: 31619757 PMCID: PMC6795909 DOI: 10.1038/s41598-019-51181-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/25/2019] [Indexed: 12/20/2022] Open
Abstract
Although of high priority for the development of genetic tools to control malaria-transmitting mosquitoes, only a few germline-specific regulatory regions have been characterised to date and the presence of global regulatory mechanisms, such as dosage compensation and meiotic sex chromosome inactivation (MSCI), are mostly assumed from transcriptomic analyses of reproductive tissues or whole gonads. In such studies, samples include a significant portion of somatic tissues inevitably complicating the reconstruction of a defined transcriptional map of gametogenesis. By exploiting recent advances in transgenic technologies and gene editing tools, combined with fluorescence-activated cell sorting and RNA sequencing, we have separated four distinct cell lineages from the Anopheles gambiae male gonads: premeiotic, meiotic (primary and secondary spermatocytes) and postmeiotic. By comparing the overall expression levels of X-linked and autosomal genes across the four populations, we revealed a striking transcriptional repression of the X chromosome coincident with the meiotic phase, classifiable as MSCI, and highlighted genes that may evade silencing. In addition, chromosome-wide median expression ratios of the premeiotic population confirmed the absence of dosage compensation in the male germline. Applying differential expression analysis, we highlighted genes and transcript isoforms enriched at specific timepoints and reconstructed the expression dynamics of the main biological processes regulating the key stages of sperm development and maturation. We generated the first transcriptomic atlas of A. gambiae spermatogenesis that will expand the available toolbox for the genetic engineering of vector control technologies. We also describe an innovative and multidimensional approach to isolate specific cell lineages that can be used for the targeted analysis of other A. gambiae organs or transferred to other medically relevant species and model organisms.
Collapse
Affiliation(s)
- Chrysanthi Taxiarchi
- Department of Life Sciences, Imperial College London, London, UK
- Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Nace Kranjc
- Department of Life Sciences, Imperial College London, London, UK
| | - Antonios Kriezis
- Department of Life Sciences, Imperial College London, London, UK
| | - Kyros Kyrou
- Department of Life Sciences, Imperial College London, London, UK
| | | | - Steven Russell
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Tony Nolan
- Department of Life Sciences, Imperial College London, London, UK
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Andrea Crisanti
- Department of Life Sciences, Imperial College London, London, UK
| | - Roberto Galizi
- Department of Life Sciences, Imperial College London, London, UK.
| |
Collapse
|
33
|
Xu D, Sember A, Zhu Q, Oliveira EAD, Liehr T, Al-Rikabi ABH, Xiao Z, Song H, Cioffi MDB. Deciphering the Origin and Evolution of the X 1X 2Y System in Two Closely-Related Oplegnathus Species (Oplegnathidae and Centrarchiformes). Int J Mol Sci 2019; 20:E3571. [PMID: 31336568 PMCID: PMC6678977 DOI: 10.3390/ijms20143571] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/05/2019] [Accepted: 07/13/2019] [Indexed: 01/18/2023] Open
Abstract
Oplegnathus fasciatus and O. punctatus (Teleostei: Centrarchiformes: Oplegnathidae), are commercially important rocky reef fishes, endemic to East Asia. Both species present an X1X2Y sex chromosome system. Here, we investigated the evolutionary forces behind the origin and differentiation of these sex chromosomes, with the aim to elucidate whether they had a single or convergent origin. To achieve this, conventional and molecular cytogenetic protocols, involving the mapping of repetitive DNA markers, comparative genomic hybridization (CGH), and whole chromosome painting (WCP) were applied. Both species presented similar 2n, karyotype structure and hybridization patterns of repetitive DNA classes. 5S rDNA loci, besides being placed on the autosomal pair 22, resided in the terminal region of the long arms of both X1 chromosomes in females, and on the X1 and Y chromosomes in males. Furthermore, WCP experiments with a probe derived from the Y chromosome of O. fasciatus (OFAS-Y) entirely painted the X1 and X2 chromosomes in females and the X1, X2, and Y chromosomes in males of both species. CGH failed to reveal any sign of sequence differentiation on the Y chromosome in both species, thereby suggesting the shared early stage of neo-Y chromosome differentiation. Altogether, the present findings confirmed the origin of the X1X2Y sex chromosomes via Y-autosome centric fusion and strongly suggested their common origin.
Collapse
Affiliation(s)
- Dongdong Xu
- Key Lab of Mariculture and Enhancement of Zhejiang Province, Marine Fishery Institute of Zhejiang Province, Zhoushan 316100, China
- College of Fisheries, Zhejiang Ocean University, Zhoushan 316100, China
| | - Alexandr Sember
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21 Liběchov, Czech Republic
| | - Qihui Zhu
- Key Lab of Mariculture and Enhancement of Zhejiang Province, Marine Fishery Institute of Zhejiang Province, Zhoushan 316100, China
| | - Ezequiel Aguiar de Oliveira
- Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luiz Km. 235, C.P. 676, São Carlos SP 13565-905, Brazil
- Secretaria de Estado de Educação de Mato Grosso-SEDUC-MT, Cuiabá MT 78049-909, Brazil
| | - Thomas Liehr
- University Clinic Jena, Institute of Human Genetics, 07747 Jena, Germany
| | | | - Zhizhong Xiao
- Laboratory for Marine Biology and Biotechnology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China
| | - Hongbin Song
- Key Lab of Mariculture and Enhancement of Zhejiang Province, Marine Fishery Institute of Zhejiang Province, Zhoushan 316100, China
- College of Fisheries, Zhejiang Ocean University, Zhoushan 316100, China
| | - Marcelo de Bello Cioffi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luiz Km. 235, C.P. 676, São Carlos SP 13565-905, Brazil.
- University Clinic Jena, Institute of Human Genetics, 07747 Jena, Germany.
| |
Collapse
|
34
|
Ellison C, Bachtrog D. Recurrent gene co-amplification on Drosophila X and Y chromosomes. PLoS Genet 2019; 15:e1008251. [PMID: 31329593 PMCID: PMC6690552 DOI: 10.1371/journal.pgen.1008251] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 08/12/2019] [Accepted: 06/18/2019] [Indexed: 12/19/2022] Open
Abstract
Y chromosomes often contain amplified genes which can increase dosage of male fertility genes and counteract degeneration via gene conversion. Here we identify genes with increased copy number on both X and Y chromosomes in various species of Drosophila, a pattern that has previously been associated with sex chromosome drive involving the Slx and Sly gene families in mice. We show that recurrent X/Y co-amplification appears to be an important evolutionary force that has shaped gene content evolution of sex chromosomes in Drosophila. We demonstrate that convergent acquisition and amplification of testis expressed gene families are common on Drosophila sex chromosomes, and especially on recently formed ones, and we carefully characterize one putative novel X/Y co-amplification system. We find that co-amplification of the S-Lap1/GAPsec gene pair on both the X and the Y chromosome occurred independently several times in members of the D. obscura group, where this normally autosomal gene pair is sex-linked due to a sex chromosome-autosome fusion. We explore several evolutionary scenarios that would explain this pattern of co-amplification. Investigation of gene expression and short RNA profiles at the S-Lap1/GAPsec system suggest that, like Slx/Sly in mice, these genes may be remnants of a cryptic sex chromosome drive system, however additional transgenic experiments will be necessary to validate this model. Regardless of whether sex chromosome drive is responsible for this co-amplification, our findings suggest that recurrent gene duplications between X and Y sex chromosomes could have a widespread effect on genomic and evolutionary patterns, including the epigenetic regulation of sex chromosomes, the distribution of sex-biased genes, and the evolution of hybrid sterility.
Collapse
Affiliation(s)
- Christopher Ellison
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, United States of America
| | - Doris Bachtrog
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, United States of America
| |
Collapse
|
35
|
Sun MS, Weber J, Blattner AC, Chaurasia S, Lehner CF. MNM and SNM maintain but do not establish achiasmate homolog conjunction during Drosophila male meiosis. PLoS Genet 2019; 15:e1008162. [PMID: 31136586 PMCID: PMC6538143 DOI: 10.1371/journal.pgen.1008162] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/27/2019] [Indexed: 01/10/2023] Open
Abstract
The first meiotic division reduces genome ploidy. This requires pairing of homologous chromosomes into bivalents that can be bi-oriented within the spindle during prometaphase I. Thereafter, pairing is abolished during late metaphase I, and univalents are segregated apart onto opposite spindle poles during anaphase I. In contrast to canonical meiosis, homologous chromosome pairing does not include the formation of a synaptonemal complex and of cross-overs in spermatocytes of Drosophila melanogaster. The alternative pairing mode in these cells depends on mnm and snm. These genes are required exclusively in spermatocytes specifically for successful conjunction of chromosomes into bivalents. Available evidence suggests that MNM and SNM might be part of a physical linkage that directly conjoins chromosomes. Here this notion was analyzed further. Temporal variation in delivery of mnm and snm function was realized by combining various transgenes with null mutant backgrounds. The observed phenotypic consequences provide strong evidence that MNM and SNM contribute directly to chromosome linkage. Premature elimination of these proteins results in precocious bivalent splitting. Delayed provision results in partial conjunction defects that are more pronounced in autosomal bivalents compared to the sex chromosome bivalent. Overall, our findings suggest that MNM and SNM cannot re-establish pairing of chromosomes into bivalents if provided after a chromosome-specific time point of no return. When delivered before this time point, they fortify preformed linkages in order to preclude premature bivalent splitting by the disruptive forces that drive chromosome territory formation during spermatocyte maturation and chromosome condensation during entry into meiosis I.
Collapse
Affiliation(s)
- Michael Shoujie Sun
- Institute of Molecular Life Science (IMLS), University of Zurich, Zurich, Switzerland
| | - Joe Weber
- Institute of Molecular Life Science (IMLS), University of Zurich, Zurich, Switzerland
| | - Ariane C. Blattner
- Institute of Molecular Life Science (IMLS), University of Zurich, Zurich, Switzerland
| | - Soumya Chaurasia
- Institute of Molecular Life Science (IMLS), University of Zurich, Zurich, Switzerland
| | - Christian F. Lehner
- Institute of Molecular Life Science (IMLS), University of Zurich, Zurich, Switzerland
- * E-mail:
| |
Collapse
|
36
|
De novo assembly of a young Drosophila Y chromosome using single-molecule sequencing and chromatin conformation capture. PLoS Biol 2018; 16:e2006348. [PMID: 30059545 PMCID: PMC6117089 DOI: 10.1371/journal.pbio.2006348] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 08/30/2018] [Accepted: 07/04/2018] [Indexed: 01/27/2023] Open
Abstract
While short-read sequencing technology has resulted in a sharp increase in the number of species with genome assemblies, these assemblies are typically highly fragmented. Repeats pose the largest challenge for reference genome assembly, and pericentromeric regions and the repeat-rich Y chromosome are typically ignored from sequencing projects. Here, we assemble the genome of Drosophila miranda using long reads for contig formation, chromatin interaction maps for scaffolding and short reads, and optical mapping and bacterial artificial chromosome (BAC) clone sequencing for consensus validation. Our assembly recovers entire chromosomes and contains large fractions of repetitive DNA, including about 41.5 Mb of pericentromeric and telomeric regions, and >100 Mb of the recently formed highly repetitive neo-Y chromosome. While Y chromosome evolution is typically characterized by global sequence loss and shrinkage, the neo-Y increased in size by almost 3-fold because of the accumulation of repetitive sequences. Our high-quality assembly allows us to reconstruct the chromosomal events that have led to the unusual sex chromosome karyotype in D. miranda, including the independent de novo formation of a pair of sex chromosomes at two distinct time points, or the reversion of a former Y chromosome to an autosome.
Collapse
|
37
|
Almeida BRRD, Milhomem-Paixão SSR, Noronha RCR, Nagamachi CY, Costa MJRD, Pardal PPDO, Coelho JS, Pieczarka JC. Karyotype diversity and chromosomal organization of repetitive DNA in Tityus obscurus (Scorpiones, Buthidae). BMC Genet 2017; 18:35. [PMID: 28412934 PMCID: PMC5392961 DOI: 10.1186/s12863-017-0494-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 03/25/2017] [Indexed: 01/22/2023] Open
Abstract
Background Holocentric chromosomes occur in approximately 750 species of eukaryotes. Among them, the genus Tityus (Scorpiones, Buthidae) has a labile karyotype that shows complex multivalent associations during male meiosis. Thus, taking advantage of the excellent model provided by the Buthidae scorpions, here we analyzed the chromosomal distribution of several repetitive DNA classes on the holocentric chromosomes of different populations of the species Tityus obscurus Gervais, 1843, highlighting their involvement in the karyotypic differences found among them. Results This species shows inter- and intrapopulational karyotype variation, with seven distinct cytotypes: A (2n = 16), B (2n = 14), C (2n = 13), D (2n = 13), E (2n = 12), F (2n = 12) and G (2n = 11). Furthermore, exhibits achiasmatic male meiosis and lacks heteromorphic sex chromosomes. Trivalent and quadrivalent meiotic associations were found in some cytotypes. In them, 45S rDNAs were found in the terminal portions of two pairs, while TTAGG repeats were found only at the end of the chromosomes. In the cytotype A (2n = 16), the U2 snRNA gene mapped to pair 1, while the H3 histone cluster and C0t-1 DNA fraction was terminally distributed on all pairs. Mariner transposons were found throughout the chromosomes, with the exception of one individual of cytotype A (2n = 16), in which it was concentrated in heterochromatic regions. Conclusions Chromosomal variability found in T. obscurus are due to rearrangements of the type fusion/fission and reciprocal translocations in heterozygous. These karyotype differences follow a geographical pattern and may be contributing to reproductive isolation between populations analyzed. Our results also demonstrate high mobility of histone H3 genes. In contrast, other multigene families (45S rDNA and U2 snRNA) have conserved distribution among individuals. The accumulation of repetitive sequences in distal regions of T. obscurus chromosomes, suggests that end of chromosome are not covered by the kinetochore.
Collapse
Affiliation(s)
- Bruno Rafael Ribeiro de Almeida
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil
| | - Susana Suely Rodrigues Milhomem-Paixão
- Instituto Federal de Educação, Ciência e Tecnologia de Goiás, Campus Valparaíso de Goiás, BR-040, km 6, Avenida Saia Velha, S/N, Área 8, Parque Esplanada V, 72876-601, Valparaíso de Goiás, Goiás, Brazil
| | - Renata Coelho Rodrigues Noronha
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil
| | - Cleusa Yoshiko Nagamachi
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil
| | - Marlyson Jeremias Rodrigues da Costa
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil
| | - Pedro Pereira de Oliveira Pardal
- Laboratório de Entomologia Médica e Artrópodes Peçonhentos, Núcleo de Medicina Tropical, Universidade Federal do Pará, Avenida Generalíssimo Deodoro, 92, 66055-240, Belém, Pará, Brazil
| | - Johne Souza Coelho
- Laboratório de Entomologia Médica e Artrópodes Peçonhentos, Núcleo de Medicina Tropical, Universidade Federal do Pará, Avenida Generalíssimo Deodoro, 92, 66055-240, Belém, Pará, Brazil
| | - Julio Cesar Pieczarka
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil.
| |
Collapse
|
38
|
Co-segregation of sex chromosomes in the male black widow spider Latrodectus mactans (Araneae, Theridiidae). Chromosoma 2017; 126:645-654. [DOI: 10.1007/s00412-017-0628-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/07/2017] [Accepted: 02/13/2017] [Indexed: 10/20/2022]
|
39
|
Swenson JM, Colmenares SU, Strom AR, Costes SV, Karpen GH. The composition and organization of Drosophila heterochromatin are heterogeneous and dynamic. eLife 2016; 5:e16096. [PMID: 27514026 PMCID: PMC4981497 DOI: 10.7554/elife.16096] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 07/06/2016] [Indexed: 12/13/2022] Open
Abstract
Heterochromatin is enriched for specific epigenetic factors including Heterochromatin Protein 1a (HP1a), and is essential for many organismal functions. To elucidate heterochromatin organization and regulation, we purified Drosophila melanogaster HP1a interactors, and performed a genome-wide RNAi screen to identify genes that impact HP1a levels or localization. The majority of the over four hundred putative HP1a interactors and regulators identified were previously unknown. We found that 13 of 16 tested candidates (83%) are required for gene silencing, providing a substantial increase in the number of identified components that impact heterochromatin properties. Surprisingly, image analysis revealed that although some HP1a interactors and regulators are broadly distributed within the heterochromatin domain, most localize to discrete subdomains that display dynamic localization patterns during the cell cycle. We conclude that heterochromatin composition and architecture is more spatially complex and dynamic than previously suggested, and propose that a network of subdomains regulates diverse heterochromatin functions.
Collapse
Affiliation(s)
- Joel M Swenson
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Serafin U Colmenares
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Amy R Strom
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Sylvain V Costes
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Gary H Karpen
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| |
Collapse
|
40
|
Abstract
Nucleoli form around tandem arrays of a ribosomal gene repeat, termed nucleolar organizer regions (NORs). During metaphase, active NORs adopt a characteristic undercondensed morphology. Recent evidence indicates that the HMG-box-containing DNA-binding protein UBF (upstream binding factor) is directly responsible for this morphology and provides a mitotic bookmark to ensure rapid nucleolar formation beginning in telophase in human cells. This is likely to be a widely employed strategy, as UBF is present throughout metazoans. In higher eukaryotes, NORs are typically located within regions of chromosomes that form perinucleolar heterochromatin during interphase. Typically, the genomic architecture of NORs and the chromosomal regions within which they lie is very poorly described, yet recent evidence points to a role for context in their function. In Arabidopsis, NOR silencing appears to be controlled by sequences outside the rDNA (ribosomal DNA) array. Translocations reveal a role for context in the expression of the NOR on the X chromosome in Drosophila Recent work has begun on characterizing the genomic architecture of human NORs. A role for distal sequences located in perinucleolar heterochromatin has been inferred, as they exhibit a complex transcriptionally active chromatin structure. Links between rDNA genomic stability and aging in Saccharomyces cerevisiae are now well established, and indications are emerging that this is important in aging and replicative senescence in higher eukaryotes. This, combined with the fact that rDNA arrays are recombinational hot spots in cancer cells, has focused attention on DNA damage responses in NORs. The introduction of DNA double-strand breaks into rDNA arrays leads to a dramatic reorganization of nucleolar structure. Damaged rDNA repeats move from the nucleolar interior to form caps at the nucleolar periphery, presumably to facilitate repair, suggesting that the chromosomal context of human NORs contributes to their genomic stability. The inclusion of NORs and their surrounding chromosomal environments in future genome drafts now becomes a priority.
Collapse
Affiliation(s)
- Brian McStay
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland, Galway, Ireland
| |
Collapse
|
41
|
Meiotic behaviour of evolutionary sex-autosome translocations in Bovidae. Chromosome Res 2016; 24:325-38. [PMID: 27136937 DOI: 10.1007/s10577-016-9524-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 04/12/2016] [Accepted: 04/17/2016] [Indexed: 10/21/2022]
Abstract
The recurrent occurrence of sex-autosome translocations during mammalian evolution suggests common mechanisms enabling a precise control of meiotic synapsis, recombination and inactivation of sex chromosomes. We used immunofluorescence and FISH to study the meiotic behaviour of sex chromosomes in six species of Bovidae with evolutionary sex-autosome translocations (Tragelaphus strepsiceros, Taurotragus oryx, Tragelaphus imberbis, Tragelaphus spekii, Gazella leptoceros and Nanger dama ruficollis). The autosomal regions of fused sex chromosomes showed normal synapsis with their homologous counterparts. Synapsis in the pseudoautosomal region (PAR) leads to the formation of characteristic bivalent (in T. imberbis and T. spekii with X;BTA13/Y;BTA13), trivalent (in T. strepsiceros and T. oryx with X/Y;BTA13 and G. leptoceros with X;BTA5/Y) and quadrivalent (in N. dama ruficollis with X;BTA5/Y;BTA16) structures at pachynema. However, when compared with other mammals, the number of pachynema lacking MLH1 foci in the PAR was relatively high, especially in T. imberbis and T. spekii, species with both sex chromosomes involved in sex autosome translocations. Meiotic transcriptional inactivation of the sex-autosome translocations assessed by γH2AX staining was restricted to their gonosomal regions. Despite intraspecies differences, the evolutionary fixation of sex-autosome translocations among bovids appears to involve general mechanisms ensuring sex chromosome pairing, synapsis, recombination and inactivation.
Collapse
|
42
|
Blattner AC, Chaurasia S, McKee BD, Lehner CF. Separase Is Required for Homolog and Sister Disjunction during Drosophila melanogaster Male Meiosis, but Not for Biorientation of Sister Centromeres. PLoS Genet 2016; 12:e1005996. [PMID: 27120695 PMCID: PMC4847790 DOI: 10.1371/journal.pgen.1005996] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 03/28/2016] [Indexed: 12/25/2022] Open
Abstract
Spatially controlled release of sister chromatid cohesion during progression through the meiotic divisions is of paramount importance for error-free chromosome segregation during meiosis. Cohesion is mediated by the cohesin protein complex and cleavage of one of its subunits by the endoprotease separase removes cohesin first from chromosome arms during exit from meiosis I and later from the pericentromeric region during exit from meiosis II. At the onset of the meiotic divisions, cohesin has also been proposed to be present within the centromeric region for the unification of sister centromeres into a single functional entity, allowing bipolar orientation of paired homologs within the meiosis I spindle. Separase-mediated removal of centromeric cohesin during exit from meiosis I might explain sister centromere individualization which is essential for subsequent biorientation of sister centromeres during meiosis II. To characterize a potential involvement of separase in sister centromere individualization before meiosis II, we have studied meiosis in Drosophila melanogaster males where homologs are not paired in the canonical manner. Meiosis does not include meiotic recombination and synaptonemal complex formation in these males. Instead, an alternative homolog conjunction system keeps homologous chromosomes in pairs. Using independent strategies for spermatocyte-specific depletion of separase complex subunits in combination with time-lapse imaging, we demonstrate that separase is required for the inactivation of this alternative conjunction at anaphase I onset. Mutations that abolish alternative homolog conjunction therefore result in random segregation of univalents during meiosis I also after separase depletion. Interestingly, these univalents become bioriented during meiosis II, suggesting that sister centromere individualization before meiosis II does not require separase.
Collapse
Affiliation(s)
- Ariane C. Blattner
- Institute of Molecular Life Sciences (IMLS), University of Zurich, Zurich, Switzerland
| | - Soumya Chaurasia
- Institute of Molecular Life Sciences (IMLS), University of Zurich, Zurich, Switzerland
| | - Bruce D. McKee
- Department of Biochemistry, Cellular and Molecular Biology (BCMB), University of Tennessee, Knoxville, Tennessee, United States of America
| | - Christian F. Lehner
- Institute of Molecular Life Sciences (IMLS), University of Zurich, Zurich, Switzerland
| |
Collapse
|
43
|
Abstract
Production of gametes of halved ploidy for sexual reproduction requires a specialized cell division called meiosis. The fusion of two gametes restores the original ploidy in the new generation, and meiosis thus stabilizes ploidy across generations. To ensure balanced distribution of chromosomes, pairs of homologous chromosomes (homologs) must recognize each other and pair in the first meiotic division. Recombination plays a key role in this in most studied species, but it is not the only actor and particular chromosomal regions are known to facilitate the meiotic pairing of homologs. In this review, we focus on the roles of centromeres and in particular on the clustering and pairwise associations of nonhomologous centromeres that precede stable pairing between homologs. Although details vary from species to species, it is becoming increasingly clear that these associations play active roles in the meiotic chromosome pairing process, analogous to those of the telomere bouquet.
Collapse
Affiliation(s)
- Olivier Da Ines
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France; ,
| | - Charles I White
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France; ,
| |
Collapse
|
44
|
Blackmon H, Demuth JP. The fragile Y hypothesis: Y chromosome aneuploidy as a selective pressure in sex chromosome and meiotic mechanism evolution. Bioessays 2015. [DOI: 10.1002/bies.201500040] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Heath Blackmon
- Department of Biology; University of Texas at Arlington; Arlington TX USA
| | - Jeffery P. Demuth
- Department of Biology; University of Texas at Arlington; Arlington TX USA
| |
Collapse
|
45
|
Abstract
Meiosis entails sorting and separating both homologous and sister chromatids. The mechanisms for connecting sister chromatids and homologs during meiosis are highly conserved and include specialized forms of the cohesin complex and a tightly regulated homolog synapsis/recombination pathway designed to yield regular crossovers between homologous chromatids. Drosophila male meiosis is of special interest because it dispenses with large segments of the standard meiotic script, particularly recombination, synapsis and the associated structures. Instead, Drosophila relies on a unique protein complex composed of at least two novel proteins, SNM and MNM, to provide stable connections between homologs during meiosis I. Sister chromatid cohesion in Drosophila is mediated by cohesins, ring-shaped complexes that entrap sister chromatids. However, unlike other eukaryotes Drosophila does not rely on the highly conserved Rec8 cohesin in meiosis, but instead utilizes two novel cohesion proteins, ORD and SOLO, which interact with the SMC1/3 cohesin components in providing meiotic cohesion.
Collapse
Affiliation(s)
- Bruce D McKee
- Department of Biochemistry, Cellular & Molecular Biology; University of Tennessee; Knoxville TN USA ; Genome Science and Technology Program; University of Tennessee; Knoxville TN USA
| | | | | |
Collapse
|
46
|
Francisco FO, Lemos B. How do y-chromosomes modulate genome-wide epigenetic States: genome folding, chromatin sinks, and gene expression. J Genomics 2014; 2:94-103. [PMID: 25057325 PMCID: PMC4105431 DOI: 10.7150/jgen.8043] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The Y chromosomes of Drosophila melanogaster and D. simulans contain only a handful of protein-coding genes, which are related to sperm mobility and reproductive fitness. Despite low or absent protein coding polymorphism, the Drosophila Y chromosome has been associated with natural phenotypic variation, including variation in the expression of hundreds to thousands of genes located on autosomes and on the X chromosome. Polymorphisms present in the large blocks of heterochromatin and consisting of differences in the amounts and kinds of sequences for satellite DNA and transposable elements may be the source of this modulation. Here we review the evidence and discuss mechanisms for global epigenetic regulation by repetitious elements in the Y chromosome. We also discuss how the discovery of this new function impacts the current knowledge about Y chromosome origin, its current dynamics, and future fate.
Collapse
Affiliation(s)
- Flávio O Francisco
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
| | - Bernardo Lemos
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
| |
Collapse
|
47
|
Reduced rDNA copy number does not affect "competitive" chromosome pairing in XYY males of Drosophila melanogaster. G3-GENES GENOMES GENETICS 2014; 4:497-507. [PMID: 24449686 PMCID: PMC3962488 DOI: 10.1534/g3.113.008730] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The ribosomal DNA (rDNA) arrays are causal agents in X-Y chromosome pairing in meiosis I of Drosophila males. Despite broad variation in X-linked and Y-linked rDNA copy number, polymorphisms in regulatory/spacer sequences between rRNA genes, and variance in copy number of interrupting R1 and R2 retrotransposable elements, there is little evidence that different rDNA arrays affect pairing efficacy. I investigated whether induced rDNA copy number polymorphisms affect chromosome pairing in a "competitive" situation in which complex pairing configurations were possible using males with XYY constitution. Using a common normal X chromosome, one of two different full-length Y chromosomes, and a third chromosome from a series of otherwise-isogenic rDNA deletions, I detected no differences in X-Y or Y-Y pairing or chromosome segregation frequencies that could not be attributed to random variation alone. This work was performed in the context of an undergraduate teaching program at Texas A&M University, and I discuss the pedagogical utility of this and other such experiments.
Collapse
|
48
|
Da Ines O, Gallego ME, White CI. Recombination-independent mechanisms and pairing of homologous chromosomes during meiosis in plants. MOLECULAR PLANT 2014; 7:492-501. [PMID: 24375719 DOI: 10.1093/mp/sst172] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Meiosis is the specialized eukaryotic cell division that permits the halving of ploidy necessary for gametogenesis in sexually reproducing organisms. This involves a single round of DNA replication followed by two successive divisions. To ensure balanced segregation, homologous chromosome pairs must migrate to opposite poles at the first meiotic division and this means that they must recognize and pair with each other beforehand. Although understanding of the mechanisms by which meiotic chromosomes find and pair with their homologs has greatly advanced, it remains far from being fully understood. With some notable exceptions such as male Drosophila, the recognition and physical linkage of homologs at the first meiotic division involves homologous recombination. However, in addition to this, it is clear that many organisms, including plants, have also evolved a series of recombination-independent mechanisms to facilitate homolog recognition and pairing. These implicate chromosome structure and dynamics, telomeres, centromeres, and, most recently, small RNAs. With a particular focus on plants, we present here an overview of understanding of these early, recombination-independent events that act in the pairing of homologous chromosomes during the first meiotic division.
Collapse
Affiliation(s)
- Olivier Da Ines
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, 63171 Aubière, France
| | | | | |
Collapse
|
49
|
Christophorou N, Rubin T, Huynh JR. Synaptonemal complex components promote centromere pairing in pre-meiotic germ cells. PLoS Genet 2013; 9:e1004012. [PMID: 24367278 PMCID: PMC3868581 DOI: 10.1371/journal.pgen.1004012] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 10/24/2013] [Indexed: 11/18/2022] Open
Abstract
Mitosis and meiosis are two distinct cell division programs. During mitosis, sister chromatids separate, whereas during the first meiotic division, homologous chromosomes pair and then segregate from each other. In most organisms, germ cells do both programs sequentially, as they first amplify through mitosis, before switching to meiosis to produce haploid gametes. Here, we show that autosomal chromosomes are unpaired at their centromeres in Drosophila germline stem cells, and become paired during the following four mitosis of the differentiating daughter cell. Surprisingly, we further demonstrate that components of the central region of the synaptonemal complex are already expressed in the mitotic region of the ovaries, localize close to centromeres, and promote de novo association of centromeres. Our results thus show that meiotic proteins and meiotic organization of centromeres, which are key features to ensure reductional segregation, are laid out in amplifying germ cells, before meiosis has started. Meiosis is a special type of cell division occurring in germ cells to produce sexual gametes. Initially, germ cells contain two copies of each chromosome, one from the mother and one from the father, which are called homologs. During meiosis, cells divide twice to produce haploid gametes with only one copy of each chromosome. Each gamete receives exactly one copy of each chromosome, because homologs become associated, through a process called meiotic pairing, and then segregate from each other during the first round of division. In Drosophila, it was assumed that homologs were always paired in every cell type. Meiotic pairing was thus viewed as an extension of a pre-existing pairing. Here, we show that chromosomes II and III are not paired in germline stem cells, which produce germ cells throughout adult life. We further show that these chromosomes become paired during the four rounds of mitosis preceding the entry in meiosis. Surprisingly, meiotic proteins are expressed during these four rounds of mitosis and are required for homologs to pair. Our results thus show that, in Drosophila, meiosis starts during the preceding mitosis.
Collapse
Affiliation(s)
- Nicolas Christophorou
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France ; CNRS UMR3215; Inserm U934, Paris, France
| | - Thomas Rubin
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France ; CNRS UMR3215; Inserm U934, Paris, France
| | - Jean-René Huynh
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France ; CNRS UMR3215; Inserm U934, Paris, France
| |
Collapse
|
50
|
Y-chromosome evolution: emerging insights into processes of Y-chromosome degeneration. Nat Rev Genet 2013; 14:113-24. [PMID: 23329112 DOI: 10.1038/nrg3366] [Citation(s) in RCA: 497] [Impact Index Per Article: 45.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The human Y chromosome is intriguing not only because it harbours the master-switch gene that determines gender but also because of its unusual evolutionary history. The Y chromosome evolved from an autosome, and its evolution has been characterized by massive gene decay. Recent whole-genome and transcriptome analyses of Y chromosomes in humans and other primates, in Drosophila species and in plants have shed light on the current gene content of the Y chromosome, its origins and its long-term fate. Furthermore, comparative analysis of young and old Y chromosomes has given further insights into the evolutionary and molecular forces triggering Y-chromosome degeneration and into the evolutionary destiny of the Y chromosome.
Collapse
|