1
|
X Chromosome Inactivation during Grasshopper Spermatogenesis. Genes (Basel) 2021; 12:genes12121844. [PMID: 34946793 PMCID: PMC8700825 DOI: 10.3390/genes12121844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/14/2021] [Accepted: 11/17/2021] [Indexed: 12/13/2022] Open
Abstract
Regulation of transcriptional activity during meiosis depends on the interrelated processes of recombination and synapsis. In eutherian mammal spermatocytes, transcription levels change during prophase-I, being low at the onset of meiosis but highly increased from pachytene up to the end of diplotene. However, X and Y chromosomes, which usually present unsynapsed regions throughout prophase-I in male meiosis, undergo a specific pattern of transcriptional inactivation. The interdependence of synapsis and transcription has mainly been studied in mammals, basically in mouse, but our knowledge in other unrelated phylogenetically species is more limited. To gain new insights on this issue, here we analyzed the relationship between synapsis and transcription in spermatocytes of the grasshopper Eyprepocnemis plorans. Autosomal chromosomes of this species achieve complete synapsis; however, the single X sex chromosome remains always unsynapsed and behaves as a univalent. We studied transcription in meiosis by immunolabeling with RNA polymerase II phosphorylated at serine 2 and found that whereas autosomes are active from leptotene up to diakinesis, the X chromosome is inactive throughout meiosis. This inactivation is accompanied by the accumulation of, at least, two repressive epigenetic modifications: H3 methylated at lysine 9 and H2AX phosphorylated at serine 139. Furthermore, we identified that X chromosome inactivation occurs in premeiotic spermatogonia. Overall, our results indicate: (i) transcription regulation in E. plorans spermatogenesis differs from the canonical pattern found in mammals and (ii) X chromosome inactivation is likely preceded by a process of heterochromatinization before the initiation of meiosis.
Collapse
|
2
|
Meiotic Executioner Genes Protect the Y from Extinction. Trends Genet 2020; 36:728-738. [PMID: 32773168 DOI: 10.1016/j.tig.2020.06.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 01/24/2023]
Abstract
The Y has been described as a wimpy degraded relic of the X, with imminent demise should it lose sex-determining function. Why then has it persisted in almost all mammals? Here we present a novel mechanistic explanation for its evolutionary perseverance: the persistent Y hypothesis. The Y chromosome bears genes that act as their own judge, jury, and executioner in the tightly regulated meiotic surveillance pathways. These executioners are crucial for successful meiosis, yet need to be silenced during the meiotic sex chromosome inactivation window, otherwise germ cells die. Only rare transposition events to the X, where they remain subject to obligate meiotic silencing, are heritable, posing strong evolutionary constraint for the Y chromosome to persist.
Collapse
|
3
|
Activity and inactivity of moth sex chromosomes in somatic and meiotic cells. Chromosoma 2019; 128:533-545. [PMID: 31410566 DOI: 10.1007/s00412-019-00722-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/17/2019] [Accepted: 08/06/2019] [Indexed: 10/26/2022]
Abstract
Moths and butterflies (Lepidoptera) are the most species-rich group of animals with female heterogamety, females mostly having a WZ, males a ZZ sex chromosome constitution. We studied chromatin conformation, activity, and inactivity of the sex chromosomes in the flour moth Ephestia kuehniella and the silkworm Bombyx mori, using immunostaining with anti-H3K9me2/3, anti-RNA polymerase II, and fluoro-uridine (FU) labelling of nascent transcripts, with conventional widefield fluorescence microscopy and 'spatial structured illumination microscopy' (3D-SIM). The Z chromosome is euchromatic in somatic cells and throughout meiosis. It is transcriptionally active in somatic cells and in the postpachaytene stage of meiosis. The W chromosome in contrast is heterochromatic in somatic cells as well as in meiotic cells at pachytene, but euchromatic and transcriptionally active like all other chromosomes at postpachytene. As the W chromosomes are apparently devoid of protein-coding genes, their transcripts must be non-coding. We found no indication of 'meiotic sex chromosome inactivation' (MSCI) in the two species.
Collapse
|
4
|
Abstract
The evolution of heteromorphic sex chromosomes has occurred independently many times in different lineages. The differentiation of sex chromosomes leads to dramatic changes in sequence composition and function and guides the evolutionary trajectory and utilization of genes in pivotal sex determination and reproduction roles. In addition, meiotic recombination and pairing mechanisms are key in orchestrating the resultant impact, retention and maintenance of heteromorphic sex chromosomes, as the resulting exposure of unpaired DNA at meiosis triggers ancient repair and checkpoint pathways. In this review, we summarize the different ways in which sex chromosome systems are organized at meiosis, how pairing is affected, and differences in unpaired DNA responses. We hypothesize that lineage specific differences in meiotic organization is not only a consequence of sex chromosome evolution, but that the establishment of epigenetic changes on sex chromosomes contributes toward their evolutionary conservation.
Collapse
Affiliation(s)
- Tasman Daish
- Comparative Genome Biology Laboratory, Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Frank Grützner
- Comparative Genome Biology Laboratory, Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia.
| |
Collapse
|
5
|
Gainey DP, Kim JY, Maroja LS. Mapping reduced introgression loci to the X chromosome of the hybridizing field crickets, Gryllus firmus and G. pennsylvanicus. PLoS One 2018; 13:e0208498. [PMID: 30566487 PMCID: PMC6300192 DOI: 10.1371/journal.pone.0208498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 11/18/2018] [Indexed: 11/19/2022] Open
Abstract
The genomic architecture of barriers to gene exchange during the speciation process is poorly understood. The genomic islands model suggests that loci associated with barriers to gene exchange prevent introgression of nearby genomic regions via linkage disequilibrium. But few analyses of the actual genomic location of non-introgressing loci in closely related species exist. In a previous study Maroja et al. showed that in the hybridizing field crickets, Gryllus firmus and G. pennsylvanicus, 50 non-introgressing loci are localized on two autosomal regions and the X chromosome, but they were not able to map the loci along the X chromosome because they used a male informative cross. Here, we localize the introgressing and non-introgressing loci on the X chromosome, and reveal that all X-linked non-introgressing loci are restricted to a 50-cM region with 10 of these loci mapped to a single location. We discuss the implications of this finding to speciation.
Collapse
Affiliation(s)
- D. Patrick Gainey
- Department of Biology, Williams College, Williamstown, Massachusetts, United States of America
| | - Jeremiah Y. Kim
- Department of Biology, Williams College, Williamstown, Massachusetts, United States of America
| | - Luana S. Maroja
- Department of Biology, Williams College, Williamstown, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
6
|
Argyridou E, Parsch J. Regulation of the X Chromosome in the Germline and Soma of Drosophila melanogaster Males. Genes (Basel) 2018; 9:genes9050242. [PMID: 29734690 PMCID: PMC5977182 DOI: 10.3390/genes9050242] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/27/2018] [Accepted: 04/27/2018] [Indexed: 12/22/2022] Open
Abstract
During the evolution of heteromorphic sex chromosomes, the sex-specific Y chromosome degenerates, while the X chromosome evolves new mechanisms of regulation. Using bioinformatic and experimental approaches, we investigate the expression of the X chromosome in Drosophila melanogaster. We observe nearly complete X chromosome dosage compensation in male somatic tissues, but not in testis. The X chromosome contains disproportionately fewer genes with high expression in testis than the autosomes, even after accounting for the lack of dosage compensation, which suggests that another mechanism suppresses their expression in the male germline. This is consistent with studies of reporter genes and transposed genes, which find that the same gene has higher expression when autosomal than when X-linked. Using a new reporter gene that is expressed in both testis and somatic tissues, we find that the suppression of X-linked gene expression is limited to genes with high expression in testis and that the extent of the suppression is positively correlated with expression level.
Collapse
Affiliation(s)
- Eliza Argyridou
- Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Grosshaderner Str. 2, 82152 Planegg-Martinsried, Germany.
| | - John Parsch
- Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Grosshaderner Str. 2, 82152 Planegg-Martinsried, Germany.
| |
Collapse
|
7
|
Cassone BJ, Kay RGG, Daugherty MP, White BJ. Comparative Transcriptomics of Malaria Mosquito Testes: Function, Evolution, and Linkage. G3 (BETHESDA, MD.) 2017; 7:1127-1136. [PMID: 28159865 PMCID: PMC5386861 DOI: 10.1534/g3.117.040089] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 01/31/2017] [Indexed: 01/05/2023]
Abstract
Testes-biased genes evolve rapidly and are important in the establishment, solidification, and maintenance of reproductive isolation between incipient species. The Anopheles gambiae complex, a group of at least eight isomorphic mosquito species endemic to Sub-Saharan Africa, is an excellent system to explore the evolution of testes-biased genes. Within this group, the testes are an important tissue in the diversification process because hybridization between species results in sterile hybrid males, but fully fertile females. We conducted RNA sequencing of A. gambiae and A. merus carcass and testes to explore tissue- and species-specific patterns of gene expression. Our data provides support for transcriptional repression of X-linked genes in the male germline, which likely drives demasculinization of the X chromosome. Testes-biased genes predominately function in cellular differentiation and show a number of interesting patterns indicative of their rapid evolution, including elevated dN/dS values, low evolutionary conservation, poor annotation in existing reference genomes, and a high likelihood of differential expression between species.
Collapse
Affiliation(s)
- Bryan J Cassone
- Department of Biology, Brandon University, Manitoba R7A 6A9, Canada
| | - Raissa G G Kay
- Department of Entomology, University of California, Riverside, California 92521
- Graduate Program in Genetics, Genomics, and Bioinformatics, University of California, Riverside, California 92521
| | - Matthew P Daugherty
- Department of Entomology, University of California, Riverside, California 92521
| | - Bradley J White
- Department of Entomology, University of California, Riverside, California 92521
| |
Collapse
|
8
|
Post-meiotic B chromosome expulsion, during spermiogenesis, in two grasshopper species. Chromosoma 2017; 126:633-644. [PMID: 28190081 DOI: 10.1007/s00412-017-0627-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 01/29/2017] [Accepted: 01/31/2017] [Indexed: 10/20/2022]
Abstract
Most supernumerary (B) chromosomes are parasitic elements carrying out an evolutionary arms race with the standard (A) chromosomes. A variety of weapons for attack and defense have evolved in both contending elements, the most conspicuous being B chromosome drive and A chromosome drive suppression. Here, we show for the first time that most microspermatids formed during spermiogenesis in two grasshopper species contain expulsed B chromosomes. By using DNA probes for B-specific satellite DNAs in Eumigus monticola and Eyprepocnemis plorans, and also 18S rDNA in the latter species, we were able to count the number of B chromosomes in standard spermatids submitted to fluorescence in situ hybridization, as well as visualizing B chromosomes inside most microspermatids. In E. plorans, the presence of B-carrying microspermatids in 1B males was associated with a significant decrease in the proportion of B-carrying standard spermatids. The fact that this decrease was apparent in elongating spermatids but not in round ones demonstrates that meiosis yields 1:1 proportions of 0B and 1B spermatids and hence that B elimination takes place post-meiotically, i.e., during spermiogenesis, implying a 5-25% decrease in B transmission rate. In E. monticola, the B chromosome is mitotically unstable and B number varies between cells within a same individual. A comparison of B frequency between round and elongating spermatids of a same individual revealed a significant 12.3% decrease. We conclude that B chromosome elimination during spermiogenesis is a defense weapon of the host genome to get rid of parasitic chromosomes.
Collapse
|
9
|
Viera A, Parra MT, Rufas JS, Page J. Transcription reactivation during the first meiotic prophase in bugs is not dependent on synapsis. Chromosoma 2016; 126:179-194. [DOI: 10.1007/s00412-016-0577-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 01/21/2016] [Accepted: 01/28/2016] [Indexed: 10/22/2022]
|
10
|
Gómez R, Van Damme K, Gosálvez J, Morán ES, Colbourne JK. Male meiosis in Crustacea: synapsis, recombination, epigenetics and fertility in Daphnia magna. Chromosoma 2015; 125:769-87. [PMID: 26685998 PMCID: PMC5023733 DOI: 10.1007/s00412-015-0558-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 10/28/2015] [Accepted: 11/09/2015] [Indexed: 11/28/2022]
Abstract
We present the first detailed cytological study of male meiosis in Daphnia (Crustacea: Branchiopoda: Cladocera)—an aquatic microcrustacean with a cyclical parthenogenetic life cycle. Using immunostaining of the testes in Daphnia magna for baseline knowledge, we characterized the different stages of meiotic division and spermiogenesis in relation to the distribution of proteins involved in synapsis, early recombination events and sister chromatid cohesion. We also studied post-translational histone modifications in male spermatocytes, in relation to the dynamic chromatin progression of meiosis. Finally, we applied a DNA fragmentation test to measure sperm quality of D. magna, with respect to levels of inbreeding. As a proxy for fertility, this technique may be used to assess the reproductive health of a sentinel species of aquatic ecosystems. Daphnia proves to be a model species for comparative studies of meiosis that is poised to improve our understanding of the cytological basis of sexual and asexual reproduction.
Collapse
Affiliation(s)
- Rocío Gómez
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049, Madrid, Spain. .,Environmental Genomics Group. School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK. .,Chromosome Dynamics Group. School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK.
| | - Kay Van Damme
- Environmental Genomics Group. School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Jaime Gosálvez
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049, Madrid, Spain
| | - Eugenio Sánchez Morán
- Chromosome Dynamics Group. School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - John K Colbourne
- Environmental Genomics Group. School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| |
Collapse
|
11
|
Banaei-Moghaddam AM, Martis MM, Macas J, Gundlach H, Himmelbach A, Altschmied L, Mayer KF, Houben A. Genes on B chromosomes: Old questions revisited with new tools. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:64-70. [DOI: 10.1016/j.bbagrm.2014.11.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/20/2014] [Accepted: 11/21/2014] [Indexed: 12/21/2022]
|
12
|
Abstract
In several different taxa, there is indubitable evidence of transcriptional silencing of the X and Y chromosomes in male meiotic cells of spermatogenesis. However, the so called meiotic sex chromosome inactivation (MSCI) has been recently a hot bed for debate in Drosophila melanogaster. This review covers cytological and genetic observations, data from transgenic constructs with testis-specific promoters, global expression profiles obtained from mutant, wild-type, larvae and adult testes as well as from cells of different stages of spermatogenesis. There is no dispute on that D. melanogaster spermatogenesis presents a down-regulation of X chromosome that does not result from the lack of dosage compensation. However, the issue is currently focused on the level of reduction of X-linked expression, the precise time it occurs and how many genes are affected. The deep examination of data and experiments in this review exposes the limitations intrinsic to the methods of studying MSCI in D. melanogaster. The current methods do not allow us to affirm anything else than the X chromosome down-regulation in meiosis (MSCI). Therefore, conclusion about level, degree or precise timing is inadequate until new approaches are implemented to know the details of MSCI or other processes involved for D. melanogaster model.
Collapse
Affiliation(s)
- Maria D Vibranovski
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil 05508
| |
Collapse
|
13
|
Milani D, Cabral-de-Mello DC. Microsatellite organization in the grasshopper Abracris flavolineata (Orthoptera: Acrididae) revealed by FISH mapping: remarkable spreading in the A and B chromosomes. PLoS One 2014; 9:e97956. [PMID: 24871300 PMCID: PMC4037182 DOI: 10.1371/journal.pone.0097956] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 04/27/2014] [Indexed: 12/12/2022] Open
Abstract
With the aim of acquiring deeper knowledge about repetitive DNAs chromosomal organization in grasshoppers, we used fluorescent in situ hybridization (FISH) to map the distribution of 16 microsatellite repeats, including mono-, di-, tri- and tetra-nucleotides, in the chromosomes of the species Abracris flavolineata (Acrididae), which harbors B chromosome. FISH revealed two main patterns: (i) exclusively scattered signals, and (ii) scattered and specific signals, forming evident blocks. The enrichment was observed in both euchromatic and heterochromatic areas and only the motif (C)30 was absent in heterochromatin. The A and B chromosomes were enriched with all the elements that were mapped, being observed in the B chromosome more distinctive blocks for (GA)15 and (GAG)10. For A complement distinctive blocks were noticed for (A)30, (CA)15, (CG)15, (GA)15, (CAC)10, (CAA)10, (CGG)10, (GAA)10, (GAC)10 and (GATA)8. These results revealed an intense spreading of microsatellites in the A. flavolineata genome that was independent of the A+T or G+C enrichment in the repeats. The data indicate that the microsatellites compose the B chromosome and could be involved in the evolution of this element in this species, although no specific relationship with any A chromosome was observed to discuss about its origin. The systematic analysis presented here contributes to the knowledge of repetitive DNA chromosomal organization among grasshoppers including the B chromosomes.
Collapse
Affiliation(s)
- Diogo Milani
- UNESP - Univ Estadual Paulista, Instituto de Biociências/IB, Departamento de Biologia, Rio Claro, São Paulo, Brazil
| | | |
Collapse
|
14
|
Ruíz-Estévez M, López-León MD, Cabrero J, Camacho JPM. Ribosomal DNA is active in different B chromosome variants of the grasshopper Eyprepocnemis plorans. Genetica 2013; 141:337-45. [PMID: 24008810 DOI: 10.1007/s10709-013-9733-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Accepted: 08/31/2013] [Indexed: 11/26/2022]
Abstract
B chromosomes are considered to be genetically inert elements. However, some of them are able to show nucleolus organizer region (NOR) activity, as detected by both cytological and molecular means. The grasshopper Eyprepocnemis plorans shows a B chromosome polymorphism characterized by the existence of many B variants. One of them, B24, shows NOR activity in about half of B-carrying males in the Torrox population. Molecular data have suggested the recent origin for B chromosomes in this species, and on this basis it would be expected that NOR activity was widespread among the different B variants. Here we test this hypothesis in four different B chromosome variants (B1, B2, B5, and B24) from 11 natural populations of the grasshopper E. plorans covering the south and east of the Iberian Peninsula plus the Balearic Islands. We used two different approaches: (1) the cytological observation of nucleoli attached to the distal region of the B chromosome (where the rDNA is located), and (2) the molecular detection of the rDNA transcripts carrying an adenine insertion characteristic of B chromosome ITS2 sequences. The results showed NOR expression not only for B24 but also for the B1 and B2 variants. However, the level of B-NOR expression in these latter variants, measured by the proportion of cells showing nucleoli attached to the B chromosomes, was much lower than that previously reported for B24. This suggests the possibility that structural or genetic background conditions are enhancing the expressivity of the rDNA in the B24 variant.
Collapse
Affiliation(s)
- Mercedes Ruíz-Estévez
- Departamento de Genética, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain
| | | | | | | |
Collapse
|
15
|
Bueno D, Palacios-Gimenez OM, Cabral-de-Mello DC. Chromosomal Mapping of Repetitive DNAs in the Grasshopper Abracris flavolineata Reveal Possible Ancestry of the B Chromosome and H3 Histone Spreading. PLoS One 2013; 8:e66532. [PMID: 23826099 PMCID: PMC3694960 DOI: 10.1371/journal.pone.0066532] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 05/06/2013] [Indexed: 11/18/2022] Open
Abstract
Supernumerary chromosomes (B chromosomes) occur in approximately 15% of eukaryote species. Although these chromosomes have been extensively studied, knowledge concerning their specific molecular composition is lacking in most cases. The accumulation of repetitive DNAs is one remarkable characteristic of B chromosomes, and the occurrence of distinct types of multigene families, satellite DNAs and some transposable elements have been reported. Here, we describe the organization of repetitive DNAs in the A complement and B chromosome system in the grasshopper species Abracris flavolineata using classical cytogenetic techniques and FISH analysis using probes for five multigene families, telomeric repeats and repetitive C0t-1 DNA fractions. The 18S rRNA and H3 histone multigene families are highly variable and well distributed in A. flavolineata chromosomes, which contrasts with the conservation of U snRNA genes and less variable distribution of 5S rDNA sequences. The H3 histone gene was an extensively distributed with clusters occurring in all chromosomes. Repetitive DNAs were concentrated in C-positive regions, including the pericentromeric region and small chromosomal arms, with some occurrence in C-negative regions, but abundance was low in the B chromosome. Finally, the first demonstration of the U2 snRNA gene in B chromosomes in A. flavolineata may shed light on its possible origin. These results provide new information regarding chromosomal variability for repetitive DNAs in grasshoppers and the specific molecular composition of B chromosomes.
Collapse
Affiliation(s)
- Danilo Bueno
- Universidade Estadual Paulista (UNESP), Instituto de Biociências/IB, Departamento de Biologia, Rio Claro, São Paulo, Brazil
| | | | | |
Collapse
|
16
|
Staiber W. Germ line-limited and somatic chromosomes of Acricotopus lucidus differ in distribution and timing of alterations of histone modifications in male gonial mitosis and meiosis. Chromosome Res 2012; 20:717-34. [PMID: 22911004 DOI: 10.1007/s10577-012-9308-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 07/27/2012] [Accepted: 08/01/2012] [Indexed: 01/22/2023]
Abstract
Special chromosomes limited to the germ line (=Ks) and exceptional genetic events such as elimination mitoses and a monopolar migration of the Ks in the last gonial mitosis are specific features of the complex chromosome cycle occurring in the chironomid Acricotopus lucidus. In the male, this unequal differential gonial mitosis results in a regular spermatocyte possessing all the Ks in addition to the somatic chromosomes (=Ss) and an aberrant spermatocyte containing only Ss. During evolution, the Ks have developed from the Ss and are composed of euchromatic S-homologous sections and heterochromatic segments. Less is known about the function and the transcriptional activity of the Ks. Specific post-translational histone modifications are known to be associated with transcriptionally active and inactive states of the chromatin. In an immunofluorescence study, the distribution of the following acetylated (ac), methylated (me) and phosphorylated (ph) amino acids in the histones H3 and H4 was analysed in Ks and Ss in male gonial mitoses and meiosis of A. lucidus, namely H3K18ac and H4K8ac, H3K4me3 and H3K9me3, H3S10ph, H3S28ph and H3T3ph. Ks and Ss clearly differ in the distribution of H3S28ph in gonial and meiotic metaphases. The H3S28ph mark covered the entire Ss, while the Ks showed this label only on their pericentromeric heterochromatin bands containing germ line-specific repetitive DNA sequences. A differential timing in the dephosphorylation of H3S10ph, H3S28ph and H3T3ph between Ks and Ss within the same cell was detected in the last gonial mitosis. The dephosphorylation occurred earlier in the Ks migrating first to the pole, than in the later equally segregating Ss. A programmed rapid histone deacetylation and dephosphorylation happened in the unseparated Ss of the aberrant spermatocyte at metaphase I in the connected primary spermatocyte, which correlated with the beginning of a permanent inactivation of these Ss in a metaphase-like condensed state. In meiosis, phosphorylated H3T3 could be detected only in metaphase II chromosomes at the inner centromeres of the attached sister chromatids. The H3T3ph labelling at this region was recently reported to be essential in mitosis for correct deposition of components of the chromosomal passenger complex and so for proper alignment, sister chromatid cohesion and segregation of chromosomes (Wang et al., Science 330:231-235, 2010; Curr Biol 21:1061-1069, 2011). Importantly, in spermatocytes, the euchromatic sections of the Ks were strongly acetylated at H3K18 and H4K8, and trimethylated at H3K4 during meiosis I and II, while the euchromatin of the meiotic Ss was hypoacetylated and hypomethylated at these sites. This result suggests a silencing of the Ss during spermatocyte meiosis. The high levels of active histone modifications detected in the euchromatic K sections support the idea that the Ks of A. lucidus are transcriptionally active in the germ line.
Collapse
Affiliation(s)
- Wolfgang Staiber
- Institute of Genetics (240), University of Hohenheim, Stuttgart, Germany.
| |
Collapse
|
17
|
Ruiz-Estévez M, Cabrero J, Camacho JPM. B-chromosome ribosomal DNA is functional in the grasshopper Eyprepocnemis plorans. PLoS One 2012; 7:e36600. [PMID: 22570730 PMCID: PMC3343036 DOI: 10.1371/journal.pone.0036600] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/09/2012] [Indexed: 11/19/2022] Open
Abstract
B-chromosomes are frequently argued to be genetically inert elements, but activity for some particular genes has been reported, especially for ribosomal RNA (rRNA) genes whose expression can easily be detected at the cytological level by the visualization of their phenotypic expression, i.e., the nucleolus. The B(24) chromosome in the grasshopper Eyprepocnemis plorans frequently shows a nucleolus attached to it during meiotic prophase I. Here we show the presence of rRNA transcripts that unequivocally came from the B(24) chromosome. To detect these transcripts, we designed primers specifically anchoring at the ITS-2 region, so that the reverse primer was complementary to the B chromosome DNA sequence including a differential adenine insertion being absent in the ITS2 of A chromosomes. PCR analysis carried out on genomic DNA showed amplification in B-carrying males but not in B-lacking ones. PCR analyses performed on complementary DNA showed amplification in about half of B-carrying males. Joint cytological and molecular analysis performed on 34 B-carrying males showed a close correspondence between the presence of B-specific transcripts and of nucleoli attached to the B chromosome. In addition, the molecular analysis revealed activity of the B chromosome rDNA in 10 out of the 13 B-carrying females analysed. Our results suggest that the nucleoli attached to B chromosomes are actively formed by expression of the rDNA carried by them, and not by recruitment of nucleolar materials formed in A chromosome nucleolar organizing regions. Therefore, B-chromosome rDNA in E. plorans is functional since it is actively transcribed to form the nucleolus attached to the B chromosome. This demonstrates that some heterochromatic B chromosomes can harbour functional genes.
Collapse
Affiliation(s)
| | | | - Josefa Cabrero
- Departamento de Genética, Universidad de Granada, Granada, Spain
| | | |
Collapse
|
18
|
Heard E, Turner J. Function of the sex chromosomes in mammalian fertility. Cold Spring Harb Perspect Biol 2011; 3:a002675. [PMID: 21730045 DOI: 10.1101/cshperspect.a002675] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The sex chromosomes play a highly specialized role in germ cell development in mammals, being enriched in genes expressed in the testis and ovary. Sex chromosome abnormalities (e.g., Klinefelter [XXY] and Turner [XO] syndrome) constitute the largest class of chromosome abnormalities and the commonest genetic cause of infertility in humans. Understanding how sex-gene expression is regulated is therefore critical to our understanding of human reproduction. Here, we describe how the expression of sex-linked genes varies during germ cell development; in females, the inactive X chromosome is reactivated before meiosis, whereas in males the X and Y chromosomes are inactivated at this stage. We discuss the epigenetics of sex chromosome inactivation and how this process has influenced the gene content of the mammalian X and Y chromosomes. We also present working models for how perturbations in sex chromosome inactivation or reactivation result in subfertility in the major classes of sex chromosome abnormalities.
Collapse
Affiliation(s)
- Edith Heard
- Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR3215 INSERM U934, 75248 Paris Cedex 05, France.
| | | |
Collapse
|
19
|
Sotero-Caio CG, de Souza MJ, Cabral-de-Mello DC, Brasileiro-Vidal AC, Guerra M. Phosphorylation of histone H3S10 in animal chromosomes: is there a uniform pattern? Cytogenet Genome Res 2011; 135:111-7. [PMID: 21893968 DOI: 10.1159/000330918] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/04/2011] [Indexed: 12/31/2022] Open
Abstract
Phosphorylation of serine 10 in histone H3 (H3S10ph) has been extensively analyzed and appears to be a conserved chromatin change associated with chromosome condensation in different eukaryotic organisms. In this work, we report the distribution of H3S10ph during meiosis in monocentric and holokinetic chromosomes of 6 insect species and in mitotic chromosomes of 7 mammalian species, aiming to investigate the labeling patterns in phylogenetically distant groups. The results indicated a very similar phosphorylation timing and distribution pattern among insects. The sex chromosomes of insects analyzed were always undercondensed and hypophosphorylated. Similarly, the micro chromosomes of the bug Pachylis aff pharaonis were also undercondensed and hypophosphorylated. Holokinetic chromosomes of bugs and monocentric chromosomes of grasshoppers and beetles displayed identical phosphorylation pattern in spite of the difference in the centromere type. Among mammals, a uniform chromosome phosphorylation was observed in marsupials, whereas bat chromosomes displayed a longitudinal banding pattern. These data indicate that, in general, the intensity of H3S10 phosphorylation in animal chromosomes is variable among the distinct chromosome types and associated with the degree of chromatin condensation at metaphase, but it may vary between different groups of animals.
Collapse
Affiliation(s)
- C G Sotero-Caio
- Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Recife, Brazil
| | | | | | | | | |
Collapse
|
20
|
Maine EM. Meiotic silencing in Caenorhabditis elegans. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 282:91-134. [PMID: 20630467 DOI: 10.1016/s1937-6448(10)82002-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In many animals and some fungi, mechanisms have been described that target unpaired chromosomes and chromosomal regions for silencing during meiotic prophase. These phenomena, collectively called "meiotic silencing," target sex chromosomes in the heterogametic sex, for example, the X chromosome in male nematodes and the XY-body in male mice, and also target any other chromosomes that fail to synapse due to mutation or chromosomal rearrangement. Meiotic silencing phenomena are hypothesized to maintain genome integrity and perhaps function in setting up epigenetic control of embryogenesis. This review focuses on meiotic silencing in the nematode, Caenorhabditis elegans, including its mechanism and function(s), and its relationship to other gene silencing processes in the germ line. One hallmark of meiotic silencing in C. elegans is that unpaired/unsynapsed chromosomes and chromosomal regions become enriched for a repressive histone modification, dimethylation of histone H3 on lysine 9 (H3K9me2). Accumulation and proper targeting of H3K9me2 rely on activity of an siRNA pathway, suggesting that histone methyltransferase activity may be targeted/regulated by a small RNA-based transcriptional silencing mechanism.
Collapse
Affiliation(s)
- Eleanor M Maine
- Department of Biology, Syracuse University, Syracuse, New York, USA
| |
Collapse
|
21
|
Schoenmakers S, Wassenaar E, Laven JSE, Grootegoed JA, Baarends WM. Meiotic silencing and fragmentation of the male germline restricted chromosome in zebra finch. Chromosoma 2010; 119:311-24. [PMID: 20162291 PMCID: PMC2875885 DOI: 10.1007/s00412-010-0258-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 12/21/2009] [Accepted: 01/11/2010] [Indexed: 11/30/2022]
Abstract
During male meiotic prophase in mammals, X and Y are in a largely unsynapsed configuration, which is thought to trigger meiotic sex chromosome inactivation (MSCI). In avian species, females are ZW, and males ZZ. Although Z and W in chicken oocytes show complete, largely heterologous synapsis, they too undergo MSCI, albeit only transiently. The W chromosome is already inactive in early meiotic prophase, and inactive chromatin marks may spread on to the Z upon synapsis. Mammalian MSCI is considered as a specialised form of the general meiotic silencing mechanism, named meiotic silencing of unsynapsed chromatin (MSUC). Herein, we studied the avian form of MSUC, by analysing the behaviour of the peculiar germline restricted chromosome (GRC) that is present as a single copy in zebra finch spermatocytes. In the female germline, this chromosome is present in two copies, which normally synapse and recombine. In contrast, during male meiosis, the single GRC is always eliminated. We found that the GRC in the male germline is silenced from early leptotene onwards, similar to the W chromosome in avian oocytes. The GRC remains largely unsynapsed throughout meiotic prophase I, although patches of SYCP1 staining indicate that part of the GRC may self-synapse. In addition, the GRC is largely devoid of meiotic double strand breaks. We observed a lack of the inner centromere protein INCENP on the GRC and elimination of the GRC following metaphase I. Subsequently, the GRC forms a micronucleus in which the DNA is fragmented. We conclude that in contrast to MSUC in mammals, meiotic silencing of this single chromosome in the avian germline occurs prior to, and independent of DNA double strand breaks and chromosome pairing, hence we have named this phenomenon meiotic silencing prior to synapsis (MSPS).
Collapse
Affiliation(s)
- Sam Schoenmakers
- Department of Obstetrics and Gynaecology, Erasmus MC-University Medical Center, PO BOX 2040, 3000 CA, Rotterdam, The Netherlands
| | | | | | | | | |
Collapse
|
22
|
Schoenmakers S, Wassenaar E, Hoogerbrugge JW, Laven JSE, Grootegoed JA, Baarends WM. Female meiotic sex chromosome inactivation in chicken. PLoS Genet 2009; 5:e1000466. [PMID: 19461881 PMCID: PMC2678266 DOI: 10.1371/journal.pgen.1000466] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 04/03/2009] [Indexed: 12/25/2022] Open
Abstract
During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW), whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription of Z- and W chromosomal genes during meiotic prophase. Herein, we show that the ZW pair is transiently silenced, from early pachytene to early diplotene using immunocytochemistry and gene expression analyses. We propose that ZW inactivation is most likely achieved via spreading of heterochromatin from the W on the Z chromosome. Also, persistent meiotic DNA double-strand breaks (DSBs) may contribute to silencing of Z. Surprisingly, gammaH2AX, a marker of DSBs, and also the earliest histone modification that is associated with XY body formation in mammalian and marsupial spermatocytes, does not cover the ZW during the synapsed stage. However, when the ZW pair starts to desynapse, a second wave of gammaH2AX accumulates on the unsynapsed regions of Z, which also show a reappearance of the DSB repair protein RAD51. This indicates that repair of meiotic DSBs on the heterologous part of Z is postponed until late pachytene/diplotene, possibly to avoid recombination with regions on the heterologously synapsed W chromosome. Two days after entering diplotene, the Z looses gammaH2AX and shows reactivation. This is the first report of meiotic sex chromosome inactivation in a species with female heterogamety, providing evidence that this mechanism is not specific to spermatogenesis. It also indicates the presence of an evolutionary force that drives meiotic sex chromosome inactivation independent of the final achievement of synapsis.
Collapse
Affiliation(s)
- Sam Schoenmakers
- Department of Reproduction and Development, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Evelyne Wassenaar
- Department of Reproduction and Development, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Jos W. Hoogerbrugge
- Department of Reproduction and Development, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Joop S. E. Laven
- Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - J. Anton Grootegoed
- Department of Reproduction and Development, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Willy M. Baarends
- Department of Reproduction and Development, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
- * E-mail:
| |
Collapse
|
23
|
Affiliation(s)
- Satoshi H. Namekawa
- Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jeannie T. Lee
- Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
24
|
Sex chromosomes and speciation in Drosophila. Trends Genet 2009; 24:336-43. [PMID: 18514967 DOI: 10.1016/j.tig.2008.04.007] [Citation(s) in RCA: 239] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 04/04/2008] [Accepted: 04/07/2008] [Indexed: 12/22/2022]
Abstract
Two empirical rules suggest that sex chromosomes play a special role in speciation. The first is Haldane's rule - the preferential sterility and inviability of species hybrids of the heterogametic (XY) sex. The second is the disproportionately large effect of the X chromosome in genetic analyses of hybrid sterility. Whereas the causes of Haldane's rule are well established, the causes of the 'large X-effect' have remained controversial. New genetic analyses in Drosophila confirm that the X is a hotspot for hybrid male sterility factors, providing a proximate explanation for the large X-effect. Several other new findings -- on faster X evolution, X chromosome meiotic drive and the regulation of the X chromosome in the male-germline -- provide plausible evolutionary explanations for the large X-effect.
Collapse
|
25
|
Quantitative analysis of NOR expression in a B chromosome of the grasshopper Eyprepocnemis plorans. Chromosoma 2008; 118:291-301. [PMID: 19048264 DOI: 10.1007/s00412-008-0197-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 11/06/2008] [Accepted: 11/12/2008] [Indexed: 10/21/2022]
Abstract
The B24 chromosome in the Torrox population of the grasshopper Eyprepocnemis plorans is recurrently attached to a nucleolus in diplotene cells, indicating the activity of its distally located ribosomal DNA (rDNA). The frequency of males expressing the B chromosome nucleolus organizer region (B-NOR) almost doubled in 4 years. The likelihood of expressing the B-NOR increased with the B number and, in males expressing it, about 20% of their cells showed a nucleolus attached to the B. When active, the B-NOR contributed more than 25% of total cell nucleolar area (NA). Within males expressing the B-NOR, total cell NA did not differ between cells showing the active or inactive B-NOR, suggesting that total cell NA is tightly regulated in this species. However, this parameter tended to increase in this population from 1999 to 2004, in parallel to the neutralization process which is taking place in this population. Finally, an analysis of A chromosome NOR interdependence for activity revealed a positive correlation among autosomes but a negative correlation between autosomes and the X chromosome, the manifestation of which depends on B-NOR activity. These results are discussed in the context of the nucleolus as a sensor of the stress caused by parasitic B chromosomes.
Collapse
|
26
|
The DNA-repair Ku70 protein is located in the nucleus and tail of elongating spermatids in grasshoppers. Chromosome Res 2007; 15:1093-100. [DOI: 10.1007/s10577-007-1183-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 10/18/2007] [Accepted: 10/18/2007] [Indexed: 01/10/2023]
|