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Osipov YA, Posukh OV, Kalashnikova DA, Antoshina PA, Laktionov PP, Skrypnik PA, Belyakin SN, Singh PB. H3K9 and H4K20 methyltransferases are directly involved in the heterochromatinization of the paternal chromosomes in male Planococcus citri embryos. Chromosoma 2023; 132:317-328. [PMID: 37700063 DOI: 10.1007/s00412-023-00809-3] [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: 05/01/2023] [Revised: 08/11/2023] [Accepted: 08/30/2023] [Indexed: 09/14/2023]
Abstract
Using a new method for bulk preparation of early stage embryos, we have investigated the role played by putative Planococcus citri H3K9 and H4K20 histone methyl transferases (HMTases) in regulating heterochromatinization of the imprinted paternal chromosomal set in male embryos. We found that H3K9 and H420 HMTases are required for heterochromatinization of the paternal chromosomes. We present evidence that both HMTases maintain the paternal "imprint" during the cleavage divisions when both parental chromosome sets are euchromatic. A testable model that accommodates our findings is proposed.
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Affiliation(s)
- Yakov A Osipov
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 2, Novosibirsk, 630090, Russian Federation
- Institute of Molecular and Cellular Biology SD RAS, Lavrentyev Ave., 8/2, 630090, Novosibirsk, Russian Federation
| | - Olga V Posukh
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 2, Novosibirsk, 630090, Russian Federation
- Institute of Molecular and Cellular Biology SD RAS, Lavrentyev Ave., 8/2, 630090, Novosibirsk, Russian Federation
| | - Darya A Kalashnikova
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 2, Novosibirsk, 630090, Russian Federation
- Institute of Molecular and Cellular Biology SD RAS, Lavrentyev Ave., 8/2, 630090, Novosibirsk, Russian Federation
| | - Polina A Antoshina
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 2, Novosibirsk, 630090, Russian Federation
- Institute of Molecular and Cellular Biology SD RAS, Lavrentyev Ave., 8/2, 630090, Novosibirsk, Russian Federation
| | - Petr P Laktionov
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 2, Novosibirsk, 630090, Russian Federation
- Institute of Molecular and Cellular Biology SD RAS, Lavrentyev Ave., 8/2, 630090, Novosibirsk, Russian Federation
| | - Polina A Skrypnik
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 2, Novosibirsk, 630090, Russian Federation
- Institute of Molecular and Cellular Biology SD RAS, Lavrentyev Ave., 8/2, 630090, Novosibirsk, Russian Federation
| | - Stepan N Belyakin
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 2, Novosibirsk, 630090, Russian Federation.
| | - Prim B Singh
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 2, Novosibirsk, 630090, Russian Federation.
- Nazarbayev University School of Medicine, 5/1 Kerei, Zhanibek Khandar Street, 010000, Nur-Sultan, Kazakhstan.
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2
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Gerbi SA. Non-random chromosome segregation and chromosome eliminations in the fly Bradysia (Sciara). Chromosome Res 2022; 30:273-288. [PMID: 35793056 PMCID: PMC10777868 DOI: 10.1007/s10577-022-09701-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 05/10/2022] [Accepted: 05/23/2022] [Indexed: 11/03/2022]
Abstract
Mendelian inheritance is based upon random segregation of homologous chromosomes during meiosis and perfect duplication and division of chromosomes in mitosis so that the entire genomic content is passed down to the daughter cells. The unusual chromosome mechanics of the fly Bradysia (previously called Sciara) presents many exceptions to the canonical processes. In male meiosis I, there is a monopolar spindle and non-random segregation such that all the paternal homologs move away from the single pole and are eliminated. In male meiosis II, there is a bipolar spindle and segregation of the sister chromatids except for the X dyad that undergoes non-disjunction. The daughter cell that is nullo-X degenerates, whereas the sperm has two copies of the X. Fertilization restores the diploid state, but there are three copies of the X chromosome, of which one or two of the paternally derived X chromosomes will be eliminated in an early cleavage division. Bradysia (Sciara) coprophila also has germ line limited L chromosomes that are eliminated from the soma. Current information and the molecular mechanisms for chromosome imprinting and eliminations, which are just beginning to be studied, will be reviewed here.
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Affiliation(s)
- Susan A Gerbi
- Department of Molecular Biology, Cell Biology and Biochemistry, Division of Biology and Medicine, Brown University, 185 Meeting Street, Sidney Frank Hall Room 260, Providence, RI, 02912, USA.
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3
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Mammalian X-chromosome inactivation: proposed role in suppression of the male programme in genetic females. J Genet 2022. [DOI: 10.1007/s12041-022-01363-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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4
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Kohli S, Gulati P, Narang A, Maini J, Shamsudheen KV, Pandey R, Scaria V, Sivasubbu S, Brahmachari V. Genome and transcriptome analysis of the mealybug Maconellicoccus hirsutus: Correlation with its unique phenotypes. Genomics 2021; 113:2483-2494. [PMID: 34022346 DOI: 10.1016/j.ygeno.2021.05.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 04/02/2021] [Accepted: 05/17/2021] [Indexed: 11/27/2022]
Abstract
Mealybugs are aggressive pests with world-wide distribution and are suitable for the study of different phenomena like genomic imprinting and epigenetics. Genomic approaches facilitate these studies in absence of robust genetics in this system. We sequenced, de novo assembled, annotated Maconellicoccus hirsutus genome. We carried out comparative genomics it with four mealybug and eight other insect species, to identify expanded, specific and contracted gene classes that relate to pesticide and desiccation resistance. We identified horizontally transferred genes adding to the mutualism between the mealybug and its endosymbionts. Male and female transcriptome analysis indicates differential expression of metabolic pathway genes correlating with their physiology and the genes for sexual dimorphism. The significantly lower expression of endosymbiont genes in males relates to the depletion of endosymbionts in males during development.
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Affiliation(s)
- Surbhi Kohli
- Dr.B.R.Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - Parul Gulati
- Dr.B.R.Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - Ankita Narang
- Dr.B.R.Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India.
| | - Jayant Maini
- Dr.B.R.Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India
| | - K V Shamsudheen
- CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Rajesh Pandey
- CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Vinod Scaria
- CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | | | - Vani Brahmachari
- Dr.B.R.Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India.
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5
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Singh PB, Shloma VV, Belyakin SN. Maternal regulation of chromosomal imprinting in animals. Chromosoma 2019; 128:69-80. [PMID: 30719566 PMCID: PMC6536480 DOI: 10.1007/s00412-018-00690-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/24/2018] [Accepted: 12/28/2018] [Indexed: 11/29/2022]
Abstract
Chromosomal imprinting requires an epigenetic system that "imprints" one of the two parental chromosomes such that it results in a heritable (cell-to-cell) change in behavior of the "imprinted" chromosome. Imprinting takes place when the parental genomes are separate, which occurs during gamete formation in the respective germ-lines and post-fertilization during the period when the parental pro-nuclei lie separately within the ooplasm of the zygote. In the mouse, chromosomal imprinting is regulated by germ-line specific DNA methylation. But the methylation machinery in the respective germ-lines does not discriminate between imprinted and non-imprinted regions. As a consequence, the mouse oocyte nucleus contains over a thousand oocyte-specific germ-line differentially methylated regions (gDMRs). Upon fertilization, the sperm provides a few hundred sperm-specific gDMRs of its own. Combined, there are around 1600 imprinted and non-imprinted gDMRs in the pro-nuclei of the newly fertilized zygote. It is a remarkable fact that beginning in the maternal ooplasm, there are mechanisms that manage to preserve DNA methylation at ~ 26 known imprinted gDMRs in the face of the ongoing genome-wide DNA de-methylation that characterizes pre-implantation development. Specificity is achieved through the binding of KRAB-zinc finger proteins to their cognate recognition sequences within the gDMRs of imprinted genes. This in turn nucleates the assembly of localized heterochromatin-like complexes that preserve methylation at imprinted gDMRs through recruitment of the maintenance methyl transferase Dnmt1. These studies have shown that a germ-line imprint may cause parent-of-origin-specific behavior only if "licensed" by mechanisms that operate post-fertilization. Study of the germ-line and post-fertilization contributions to the imprinting of chromosomes in classical insect systems (Coccidae and Sciaridae) show that the ooplasm is the likely site where imprinting takes place. By comparing molecular and genetic studies across these three species, we suggest that mechanisms which operate post-fertilization play a key role in chromosomal imprinting phenomena in animals and conserved components of heterochromatin are shared by these mechanisms.
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Affiliation(s)
- Prim B Singh
- Nazarbayev University School of Medicine, 5/1 Kerei, Zhanibek Khandar Street, Astana, Z05K4F4, Kazakhstan.
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov str. 2, Novosibirsk, 630090, Russian Federation.
| | - Victor V Shloma
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov str. 2, Novosibirsk, 630090, Russian Federation
- Genomics Laboratory, Institute of Molecular and Cellular Biology SD RAS, Lavrentyev ave, 8/2, Novosibirsk, 630090, Russian Federation
| | - Stepan N Belyakin
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov str. 2, Novosibirsk, 630090, Russian Federation
- Genomics Laboratory, Institute of Molecular and Cellular Biology SD RAS, Lavrentyev ave, 8/2, Novosibirsk, 630090, Russian Federation
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Singh PB, Belyakin SN. L Chromosome Behaviour and Chromosomal Imprinting in Sciara Coprophila. Genes (Basel) 2018; 9:genes9090440. [PMID: 30177635 PMCID: PMC6162386 DOI: 10.3390/genes9090440] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 08/29/2018] [Accepted: 08/29/2018] [Indexed: 12/31/2022] Open
Abstract
The retention of supernumerary chromosomes in the germ-line of Sciara coprophila is part of a highly-intricate pattern of chromosome behaviours that have fascinated cytogeneticists for over 80 years. Germ-line limited (termed L or "limited") chromosomes are cytologically heterochromatic and late-replicating, with more recent studies confirming they possess epigenetic hallmarks characteristic of constitutive heterochromatin. Little is known about their genetic constitution although they have been found to undergo cycles of condensation and de-condensation at different stages of development. Unlike most supernumeraries, the L chromosomes in S. coprophila are thought to be indispensable, although in two closely related species Sciara ocellaris and Sciara reynoldsi the L chromosomes, have been lost during evolution. Here, we review what we know about L chromosomes in Sciara coprophila. We end by discussing how study of the L chromosome condensation cycle has provided insight into the site and timing of both the erasure of parental "imprints" and also the placement of a putative "imprint" that might be carried by the sperm into the egg.
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Affiliation(s)
- Prim B Singh
- Nazarbayev University School of Medicine, 5/1 Kerei, Zhanibek Khandar Street, Astana Z05K4F4, Kazakhstan.
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov str. 2, Novosibirsk 630090, Russia.
| | - Stepan N Belyakin
- Epigenetics Laboratory, Department of Natural Sciences, Novosibirsk State University, Pirogov str. 2, Novosibirsk 630090, Russia.
- Genomics laboratory, Institute of Molecular and Cellular Biology SB RAS, Lavrentyev ave, 8/2, Novosibirsk 630090, Russia.
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7
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8
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Heterochromatin and the molecular mechanisms of ‘parent-of-origin’ effects in animals. J Biosci 2016; 41:759-786. [DOI: 10.1007/s12038-016-9650-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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9
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Abstract
Differentiated sex chromosomes in mammals and other vertebrates evolved independently but in strikingly similar ways. Vertebrates with differentiated sex chromosomes share the problems of the unequal expression of the genes borne on sex chromosomes, both between the sexes and with respect to autosomes. Dosage compensation of genes on sex chromosomes is surprisingly variable - and can even be absent - in different vertebrate groups. Systems that compensate for different gene dosages include a wide range of global, regional and gene-by-gene processes that differ in their extent and their molecular mechanisms. However, many elements of these control systems are similar across distant phylogenetic divisions and show parallels to other gene silencing systems. These dosage systems cannot be identical by descent but were probably constructed from elements of ancient silencing mechanisms that are ubiquitous among vertebrates and shared throughout eukaryotes.
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Connallon T, Clark AG. Sex-differential selection and the evolution of X inactivation strategies. PLoS Genet 2013; 9:e1003440. [PMID: 23637618 PMCID: PMC3630082 DOI: 10.1371/journal.pgen.1003440] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 02/24/2013] [Indexed: 11/25/2022] Open
Abstract
X inactivation—the transcriptional silencing of one X chromosome copy per female somatic cell—is universal among therian mammals, yet the choice of which X to silence exhibits considerable variation among species. X inactivation strategies can range from strict paternally inherited X inactivation (PXI), which renders females haploid for all maternally inherited alleles, to unbiased random X inactivation (RXI), which equalizes expression of maternally and paternally inherited alleles in each female tissue. However, the underlying evolutionary processes that might account for this observed diversity of X inactivation strategies remain unclear. We present a theoretical population genetic analysis of X inactivation evolution and specifically consider how conditions of dominance, linkage, recombination, and sex-differential selection each influence evolutionary trajectories of X inactivation. The results indicate that a single, critical interaction between allelic dominance and sex-differential selection can select for a broad and continuous range of X inactivation strategies, including unequal rates of inactivation between maternally and paternally inherited X chromosomes. RXI is favored over complete PXI as long as alleles deleterious to female fitness are sufficiently recessive, and the criteria for RXI evolution is considerably more restrictive when fitness variation is sexually antagonistic (i.e., alleles deleterious to females are beneficial to males) relative to variation that is deleterious to both sexes. Evolutionary transitions from PXI to RXI also generally increase mean relative female fitness at the expense of decreased male fitness. These results provide a theoretical framework for predicting and interpreting the evolution of chromosome-wide expression of X-linked genes and lead to several useful predictions that could motivate future studies of allele-specific gene expression variation. With the exception of its most primitive members, mammal species practice X inactivation, where one copy of each X chromosome pair is silenced in each cell of the female body. The particular copy of the X that is silenced nevertheless shows considerable variability among species, and the evolutionary causes for this variability remain unclear. Here, we show that X inactivation strategies are likely to evolve in response to the sex-differential fitness properties of X-linked genetic variation. Genetic variation with similar effects on male and female fitness will generally favor the evolution of random X inactivation, potentially including preferential inactivation of the maternally inherited X chromosome. Variation with opposing fitness effects in each sex (“sexually antagonistic” variation, which includes mutations that both decrease female fitness and enhance male fitness) selects for preferential or complete inactivation of the paternally inherited X. Paternally biased X inactivation patterns appear to be common in nature, which suggests that sexually antagonistic genetic variation might be an important factor underlying the evolution of X inactivation. The theory provides a conceptual framework for understanding the evolution of X inactivation strategies and generates several novel predictions that may soon be tested with modern genome sequencing technologies.
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Affiliation(s)
- Tim Connallon
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America.
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11
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OBATA Y. Study on the Mechanism of Maternal Imprinting During Oocyte Growth. J Reprod Dev 2011; 57:1-8. [DOI: 10.1262/jrd.10-195e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Yayoi OBATA
- Department of BioScience, Tokyo University of Agriculture
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12
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13
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Bongiorni S, Pasqualini B, Taranta M, Singh PB, Prantera G. Epigenetic regulation of facultative heterochromatinisation in Planococcus citri via the Me(3)K9H3-HP1-Me(3)K20H4 pathway. J Cell Sci 2007; 120:1072-80. [PMID: 17327272 DOI: 10.1242/jcs.03412] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Using RNA interference (RNAi) we have conducted a functional analysis of the HP1-like chromobox gene pchet2 during embryogenesis of the mealybug Planococcus citri. Knocking down pchet2 expression results in decondensation of the male-specific chromocenter that normally arises from the developmentally-regulated facultative heterochromatinisation of the paternal chromosome complement. Together with the disappearance of the chromocenter the staining levels of two associated histone modifications, tri-methylated lysine 9 of histone H3 [Me(3)K9H3] and tri-methylated lysine 20 of histone H4 [Me(3)K20H4], are reduced to undetectable levels. Embryos treated with double-stranded RNA (dsRNA) targeting pchet2 also exhibit chromosome abnormalities, such as aberrant chromosome condensation, and also the presence of metaphases that contain 'lagging' chromosomes. We conclude that PCHET2 regulates chromosome behavior during metaphase and is a crucial component of a Me(3)K9H3-HP1-Me(3)K20H4 pathway involved in the facultative heterochromatinisation of the (imprinted) paternal chromosome set.
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Affiliation(s)
- Silvia Bongiorni
- Department of Agrobiologia e Agrochimica, University of Tuscia, 01100 Viterbo, Italy
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14
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Affiliation(s)
- Susan A Gerbi
- Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA.
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15
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Holmquist GP, Ashley T. Chromosome organization and chromatin modification: influence on genome function and evolution. Cytogenet Genome Res 2006; 114:96-125. [PMID: 16825762 DOI: 10.1159/000093326] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Accepted: 12/15/2005] [Indexed: 11/19/2022] Open
Abstract
Histone modifications of nucleosomes distinguish euchromatic from heterochromatic chromatin states, distinguish gene regulation in eukaryotes from that of prokaryotes, and appear to allow eukaryotes to focus recombination events on regions of highest gene concentrations. Four additional epigenetic mechanisms that regulate commitment of cell lineages to their differentiated states are involved in the inheritance of differentiated states, e.g., DNA methylation, RNA interference, gene repositioning between interphase compartments, and gene replication time. The number of additional mechanisms used increases with the taxon's somatic complexity. The ability of siRNA transcribed from one locus to target, in trans, RNAi-associated nucleation of heterochromatin in distal, but complementary, loci seems central to orchestration of chromatin states along chromosomes. Most genes are inactive when heterochromatic. However, genes within beta-heterochromatin actually require the heterochromatic state for their activity, a property that uniquely positions such genes as sources of siRNA to target heterochromatinization of both the source locus and distal loci. Vertebrate chromosomes are organized into permanent structures that, during S-phase, regulate simultaneous firing of replicon clusters. The late replicating clusters, seen as G-bands during metaphase and as meiotic chromomeres during meiosis, epitomize an ontological utilization of all five self-reinforcing epigenetic mechanisms to regulate the reversible chromatin state called facultative (conditional) heterochromatin. Alternating euchromatin/heterochromatin domains separated by band boundaries, and interphase repositioning of G-band genes during ontological commitment can impose constraints on both meiotic interactions and mammalian karyotype evolution.
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Affiliation(s)
- G P Holmquist
- Biology Department, City of Hope Medical Center, Duarte, CA, USA.
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Khosla S, Mendiratta G, Brahmachari V. Genomic imprinting in the mealybugs. Cytogenet Genome Res 2006; 113:41-52. [PMID: 16575162 DOI: 10.1159/000090814] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2005] [Accepted: 08/08/2005] [Indexed: 11/19/2022] Open
Abstract
The coccid insects (Hemiptera; Sternorrhyncha; Aphidiformes; Coccoidea; Pseudococcidae) are well suited to study not only the mechanisms of genomic imprinting but also facultative heterochromatization, a phenomenon well exemplified by inactivation of the X chromosome in female mammals. Coccids show sex-specific heterochromatization of an entire set of chromosomes and transcriptional silencing of all the paternally contributed chromosomes in males. Thus, genomic imprinting and the resultant differential regulation operate on 50% of the genome in contrast to the single X chromosome in female mammals. A significant insight into the phenomenon of genomic imprinting has come from very elegant cytological analysis of the coccid system. Recently, efforts have been made to dissect out at the molecular level the phenomenon of genomic imprinting in these insects. The present review summarizes both of these aspects. In light of the accruing experimental evidence for chromatin-based differences in the maternal and paternal genomes, it appears that the mealybug system may provide evidence for stable maintenance of chromatin code not only through mitosis but also through meiosis.
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Affiliation(s)
- S Khosla
- Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.
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17
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Mohan KN, Chandra HS. Isolation and analysis of sequences showing sex-specific cytosine methylation in the mealybug Planococcus lilacinus. Mol Genet Genomics 2005; 274:557-68. [PMID: 16283386 DOI: 10.1007/s00438-005-0004-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Accepted: 04/20/2005] [Indexed: 10/25/2022]
Abstract
Genomic libraries of Planococcus lilacinus, a mealybug in which paternal chromosomes are facultatively heterochromatic and inactive in sons but not in daughters, were probed with subtraction probes in order to estimate the number of sequences displaying sex-specific cytosine methylation in CpG dinucleotides. Sequences showing male-specific methylation were found to occur approximately 2.5 times more often than those showing female-specific methylation. In order to directly isolate sequences showing sex-specific CpG methylation, we employed methylation-specific arbitrarily primed (MS-AP) polymerase chain reaction (PCR) and identified 72 sex-specific products, of which 51 were from males and 21 from females. Amplification of bisulfite-modified DNA and subsequent Southern hybridization showed that in 33 out of these 72 sex-specific products, there was differential methylation of homologous sequences; i.e., both methylated and unmethylated copies of the same sequence occurred in one sex whereas only unmethylated copies were present in the opposite sex. Sequencing of bisulfite-modified DNA showed an interspersion of CpG and non-CpG methylation among the sex-specifically methylated sequences. Sequences showing male-specific CpG methylation are organized as transcriptionally silent chromatin in males but not in females, whereas those showing female-specific CpG methylation are organized as transcriptionally silent chromatin in females but not in males. The sequences identified in this study that show differential methylation in males, but are unmethylated in females, may prove useful in the study of imprinting in the mealybug system.
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Affiliation(s)
- K Naga Mohan
- Centre for Human Genetics, G 04, International Technology Park, Whitefield Road, Bangalore 560066, India.
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18
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Sakharova NY, Chailakhyan LM. Some theoretical problems of cloning in the light of comparative analysis of early development in mammals. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2003; 392:432-4. [PMID: 14650878 DOI: 10.1023/a:1026188107779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- N Yu Sakharova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, pr. Nauki, Pushchino, Moscow Oblast, 142292 Russia
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Abstract
Sexual reproduction results from the fusion of gametes in which the chromatin configuration of maternal and paternal chromosomes is distinct at fertilization. Although many of the differences are erased during successive cellular divisions and chromatin modifications, some are retained in both somatic and germline cells. These epigenetic modifications can confer different characteristics on maternal and paternal chromosomes and such differences can be selected during any process that has the ability to distinguish between homologues. The end result of these selective forces are parental origin effects, writ large. The range of effects observed, including transcriptional imprinting and effects on chromosome segregation and heterochromatization, reflects the diversity of selective forces in operation. However, a closer look at these effects suggests that parental origin-dependent differences in chromatin structure might be subject to some common forces and that these forces may explain many of the "nontranscriptional" parental origin effects observed in mammals.
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Affiliation(s)
- Elena de la Casa-Esperón
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
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20
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Kathirvel PK, Singh PB. Maternal regulation of imprinting. J Biosci 2002; 27:437-8. [PMID: 12381858 DOI: 10.1007/bf02705031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Paramasivam K Kathirvel
- Nuclear Reprogramming Laboratory, Division of Gene Expression and Development, Roslin Institute (Edinburgh), Midlothian, Scotland, EH25 0PS, UK
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Devajyothi C, Brahmachari V. Modulation of DNA methyltransferase during the life cycle of a mealybug Planococcus lilacinus. FEBS Lett 2001. [DOI: 10.1016/0014-5793(89)80705-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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22
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Khosla S, Augustus M, Brahmachari V. Sex-specific organisation of middle repetitive DNA sequences in the mealybug Planococcus lilacinus. Nucleic Acids Res 1999; 27:3745-51. [PMID: 10471745 PMCID: PMC148631 DOI: 10.1093/nar/27.18.3745] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Differential organisation of homologous chromosomes is related to both sex determination and genomic imprinting in coccid insects, the mealybugs. We report here the identification of two middle repetitive sequences that are differentially organised between the two sexes and also within the same diploid nucleus. These two sequences form a part of the male-specific nuclease-resistant chromatin (NRC) fraction of a mealybug Planococcus lilacinus. To understand the phenomenon of differential organisation we have analysed the components of NRC by cloning the DNA sequences present, deciphering their primary sequence, nucleosomal organisation, genomic distri-bution and cytological localisation. Our observations suggest that the middle repetitive sequences within NRC are functionally significant and we discuss their probable involvement in male-specific chromatin organisation.
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Affiliation(s)
- S Khosla
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560 012, India
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23
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Affiliation(s)
- G Herrick
- Department of Oncological Sciences, University of Utah, Salt Lake City 84132, USA
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24
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Lloyd VK, Sinclair DA, Grigliatti TA. Genomic imprinting and position-effect variegation in Drosophila melanogaster. Genetics 1999; 151:1503-16. [PMID: 10101173 PMCID: PMC1460573 DOI: 10.1093/genetics/151.4.1503] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Genomic imprinting is a phenomenon in which the expression of a gene or chromosomal region depends on the sex of the individual transmitting it. The term imprinting was first coined to describe parent-specific chromosome behavior in the dipteran insect Sciara and has since been described in many organisms, including other insects, plants, fish, and mammals. In this article we describe a mini-X chromosome in Drosophila melanogaster that shows genomic imprinting of at least three closely linked genes. The imprinting of these genes is observed as mosaic silencing when the genes are transmitted by the male parent, in contrast to essentially wild-type expression when the same genes are maternally transmitted. We show that the imprint is due to the sex of the parent rather than to a conventional maternal effect, differential mitotic instability of the mini-X chromosome, or an allele-specific effect. Finally, we have examined the effects of classical modifiers of position-effect variegation on the maintenance and the establishment of the imprint. Factors that modify position-effect variegation alter the somatic expression but not the establishment of the imprint. This suggests that chromatin structure is important in maintenance of the imprint, but a separate mechanism may be responsible for its initiation.
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Affiliation(s)
- V K Lloyd
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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25
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Gadagkar R. How to gain the benefits of sexual reproduction without paying the cost: a worm shows the way. Trends Ecol Evol 1998; 13:220-1. [PMID: 21238274 DOI: 10.1016/s0169-5347(98)01391-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- R Gadagkar
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012, India; Animal Behaviour Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India
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26
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Tapscott SJ, Klesert TR, Widrow RJ, Stöger R, Laird CD. Fragile-X syndrome and myotonic dystrophy: parallels and paradoxes. Curr Opin Genet Dev 1998; 8:245-53. [PMID: 9610417 DOI: 10.1016/s0959-437x(98)80148-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Fragile-X syndrome and myotonic dystrophy are caused by triplet repeat expansions embedded in CpG islands in the transcribed non-coding regions of the FMR1 and the DMPK genes, respectively. Although initial reports emphasized differences in the mechanisms by which the expanded triplet repeats caused these diseases, results published in the past year highlight remarkable parallels in the likely molecular etiologies. At both loci, expansion is associated with altered chromatin, aberrant methylation, and suppressed expression of the adjacent FMR1 and DMAHP genes, implicating epigenetic mediation of these genetic diseases.
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Affiliation(s)
- S J Tapscott
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
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27
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Abstract
A handful of autosomal genes in the mammalian genome are inherited in a silent state from one of the two parents, and in a fully active form from the other, thereby rendering the organism functionally hemizygous for imprinted genes. To date 19 imprinted genes have been identified; 5 are expressed from the maternal chromosome while the rest are expressed from the paternal chromosome. Allele-specific methylation of CpG residues, established in one of the germlines and maintained throughout embryogenesis, has been clearly implicated in the maintenance of imprinting in somatic cells. Although the function of imprinting remains a subject of some debate, the process is thought to have an important role in regulating the rate of fetal growth.
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Affiliation(s)
- M S Bartolomei
- Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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28
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Khosla S, Kantheti P, Brahmachari V, Chandra HS. A male-specific nuclease-resistant chromatin fraction in the mealybug Planococcus lilacinus. Chromosoma 1996; 104:386-92. [PMID: 8575251 DOI: 10.1007/bf00337228] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In mealybugs, chromatin condensation is related to both genomic imprinting and sex determination. The paternal chromosomal complement is condensed and genetically inactive in sons but not in daughters. During a study of chromatin organization in Planococcus lilacinus, digestion with micrococcal nuclease showed that 3% to 5% of the male genome is resistant to the enzyme. This Nuclease Resistant Chromatin (NRC) apparently has a nucleosomal organization. Southern hybridization of genomic DNA suggests that NRC sequences are present in both sexes and occur throughout the genome. Cloned NRC DNA is A+T-rich with stretches of adenines similar to those present in mouse alpha-satellite sequences. NRC DNA also contains sequence motifs that are typically associated with the nuclear matrix. Salt-fractionation experiments showed that NRC sequences are matrix associated. These observations are discussed in relation to the unusual cytological features of mealybug chromosomes, including the possible existence of multiple centres of inactivation.
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Affiliation(s)
- S Khosla
- Developmental Biology and Genetics Laboratory, Indian Institute of Science, Bangalore 560 012, India
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29
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Erickson RP. Recent advances in developmental genetics: growth factors and morphogens. Mol Reprod Dev 1995; 41:109-25. [PMID: 7619500 DOI: 10.1002/mrd.1080410116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- R P Erickson
- Department of Pediatrics, Steele Memorial Children's Research Center, University of Arizona College of Medicine, Tucson 85724, USA
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30
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Shibata H, Yoshino K, Muramatsu M, Plass C, Chapman VM, Hayashizaki Y. The use of restriction landmark genomic scanning to scan the mouse genome for endogenous loci with imprinted patterns of methylation. Electrophoresis 1995; 16:210-7. [PMID: 7774561 DOI: 10.1002/elps.1150160136] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Restriction landmark genomic scanning (RLGS) has been used to screen endogenous loci for imprinted patterns of methylation. The screening method is based upon the identification of genetic variation in RLGS profiles between different strains and determining whether specific variant landmarks are transmitted equally to the progeny of reciprocal F1 matings. The RLGS profiles of C57BL/6 (B6) and DBA/2 (D2) and their reciprocal hybrids were produced with two enzyme combinations that used NotI as the landmark enzyme and two combinations that used BssHII. An estimated 13% of the spots are either B5- or D2-specific in these tests, giving a total of nearly 1000 variant loci that were examined for imprinted methylation. Three candidate loci for imprinted regulation were identified in these analyses. We also used crosses of more genetically diverse parents to increase the number of variant loci screened. Interspecific crosses of B6 with the M. musculus strain PWK and intrasubspecific crosses between B6 and the M. molossinus strain MSM expanded the levels of variation between the parental strains in the cross to an estimated 31% and 26%, respectively. The RLGS patterns for one NotI combination and one BssHII profile were examined for each of these crosses, giving approximately 2000 additional loci that were screened for imprinted patterns of methylation. Eight loci with imprinted patterns of transmission were observed out of 3040 loci tested. The chromosomal locations for the three B6 and D2 specific loci, Irlgs 1-3, were identified using BXD recombinant inbred strain analysis. Irlgs 1 and 3 are B6- and D2-specific loci that had the same strain distribution pattern which mapped to the central region of chromosome 9.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H Shibata
- RIKEN Tsukuba Life Science Center, Ibaraki, Japan
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31
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Erickson RP, Lewis SE. The new human genetics. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1995; 25 Suppl 26:7-12. [PMID: 7789364 DOI: 10.1002/em.2850250604] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This overview for the special issue of Environmental and Molecular Mutagenesis devoted to recent advances in human genetics relevant to mutagenesis briefly surveys the advances in the field. We present the evidence that trinucleotide repeat expansion can cause anticipation in human inherited disease. The finding that transposons are active in humans, as they are in other organisms, is reviewed. We present an example of two different diseases being caused by mutations in one gene. The role of mitochondrial mutations and parent-specific gene origin effects ("imprinting") are briefly reviewed; fuller reviews are provided in other articles in this special issue. Finally, the relevance of epigenetic inheritance by protein-protein interaction is included.
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Affiliation(s)
- R P Erickson
- Angel Charity for Children-Wings for Genetic Research, Steele Memorial Children's Research Center, Department of Pediatrics, University of Arizona, Tucson, USA
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32
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Cassidy SB. Uniparental disomy and genomic imprinting as causes of human genetic disease. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1995; 25 Suppl 26:13-20. [PMID: 7789357 DOI: 10.1002/em.2850250605] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The existence of parent-of-origin differences in the expression of some genes, a process known as genomic imprinting, has been recognized and documented over the past several years. This epigenetic marking process results in the differential expression of normal genes depending upon whether they were inherited from the mother or the father. A number of human disorders have been identified as resulting from alterations in genomic imprinting. One process which can unmask genomic imprinting is uniparental disomy, in which both members of a chromosome pair are contributed by one sex parent. When uniparental disomy is present, genetic abnormality can result either from homozygosity of a single mutant allele which is present in two doses, or from the presence of two copies of an imprinted unexpressed gene or genes, rather than the usual one expressed and one unexpressed. Examples of human genetic disorders that are the consequence of genomic imprinting, and a discussion of current knowledge about the mechanisms of imprinting and the causes of uniparental disomy, are reviewed.
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Affiliation(s)
- S B Cassidy
- Department of Genetics, Case Western Reserve University, Cleveland, Ohio 44106-4955, USA
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33
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Moore T, Hurst LD, Reik W. Genetic conflict and evolution of mammalian X-chromosome inactivation. DEVELOPMENTAL GENETICS 1995; 17:206-11. [PMID: 8565327 DOI: 10.1002/dvg.1020170305] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The existence of parentally imprinted gene expression in the somatic tissues of mammals and plants can be explained by a theory of intragenomic genetic conflict, which is a logical extension of classical parent-offspring conflict theory. This theory unites conceptually the phenomena of autosomal imprinting and X-chromosome inactivation. We argue that recent experimental studies of X-chromosome inactivation and androgenetic development address previously published predictions of the conflict theory, and we discuss possible explanations for the occurrence of random X-inactivation in the somatic tissues of eutherians.
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Affiliation(s)
- T Moore
- Department of Development and Signalling, Babraham Institute, Cambridge, United Kingdom
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34
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Singh PB. Molecular mechanisms of cellular determination: their relation to chromatin structure and parental imprinting. J Cell Sci 1994; 107 ( Pt 10):2653-68. [PMID: 7876336 DOI: 10.1242/jcs.107.10.2653] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- P B Singh
- Department of Development and Signalling, Babraham Institute, Cambridge, UK
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35
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Pfeifer K, Tilghman SM. Allele-specific gene expression in mammals: the curious case of the imprinted RNAs. Genes Dev 1994; 8:1867-74. [PMID: 7525406 DOI: 10.1101/gad.8.16.1867] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- K Pfeifer
- Howard Hughes Medical Institute, Princeton University, New Jersey 08544
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36
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Moore TF, Whittingham DG. Imprinting of phosphoribosyltransferases during preimplantation development of the mouse mutant, Hprtb-m3. Development 1992; 115:1011-6. [PMID: 1451655 DOI: 10.1242/dev.115.4.1011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The measurement of the activity of the X-linked enzyme HPRT has been widely used as an indicator of X-chromosome activity during preimplantation development in the mouse. More recently, the concomitant measurement of the activity of the autosomally-encoded enzyme APRT has been used in an attempt to decrease the variability inherent in the measurement of enzyme activity from minute samples such as preimplantation embryos. In this study the use of the HPRT-deficient mouse mutant, Hprtb-m3, allowed the unequivocal identification of the parental origin of HPRT activity measured in embryos derived from crosses between wild-type mice, and mice which were homozygous or hemizygous for the Hprtb-m3 allele. Results were similar to those of a previous study, where oocyte-encoded HPRT activity accounted for about 10% of total HPRT activity at 76 hours post human chorionic gonadotrophin injection and the paternally-derived Hprt allele was shown to be transcriptionally active by the late 2-cell stage. In contrast to other studies, differential expression of the two Hprt alleles was detected during the preimplantation period, in embryos derived from crosses between wild-type and HPRT-deficient mice. Evidence was also found for the existence of an X-linked locus which influences the amount of APRT activity in the unfertilized oocyte. We propose that the expression pattern of this locus may be influenced by its parental origin.
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Affiliation(s)
- T F Moore
- MRC Experimental Embryology and Teratology Unit, St. George's Hospital Medical School, London, UK
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37
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Affiliation(s)
- S M Gartler
- Department of Medicine, University of Washington, Seattle
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38
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Abstract
Genetic recombination has important consequences, including the familiar rules of Mendelian genetics. Here we present a new argument for the evolutionary function of recombination based on the hypothesis that meiotic drive systems continually arise to threaten the fairness of meiosis. These drive systems act at the expense of the fitness of the organism as a whole for the benefit of the genes involved. We show that genes increasing crossing over are favoured, in the process of breaking up drive systems and reducing the fitness loss to organisms.
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Affiliation(s)
- D Haig
- Department of Plant Sciences, University of Oxford, U.K
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39
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Abstract
The preferential retention of paternal tumor suppressor alleles in sporadic tumors and the failure to demonstrate genetic linkage between disease predisposition and tumor suppressor loci in familial cases indicates that genome imprinting may be involved in the genesis of some pediatric cancers. A genetic model that invokes the activity of modifier loci (imprinting genes) on alleles to be modified (imprinted genes) is able to account for these data. Genome imprinting may be viewed as a special case of dominance modification, differing from other examples only in that the modification of dominance is dependent on gamete-of-origin. Data from human pediatric tumors, transgenes in the mouse and variegating position-effects in Drosophila, indicate that the net effect of modifier loci is the inactivation of alleles at affected loci. Polymorphism at the level of the modifier loci will result in different degrees of modification between individuals. With respect to tumors, the most important mechanism by which these differences are manifested is cellular mosaicism for the expression of a modified allele. Such characteristics are reminiscent of the behavior of variegating position-effects in Drosophila and the application of this paradigm to human disease phenotypes provides both a mechanism by which differential genome imprinting may be accomplished as well as genetic models that may explain the clinical association of syntenic diseases, the association between tumor progression and specific chromosomal aneuploidy and the unusual inheritance characteristics of many diseases.
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Affiliation(s)
- C Sapienza
- Ludwig Institute for Cancer Research, Montreal, Canada
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40
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Singh PB, Miller JR, Pearce J, Kothary R, Burton RD, Paro R, James TC, Gaunt SJ. A sequence motif found in a Drosophila heterochromatin protein is conserved in animals and plants. Nucleic Acids Res 1991; 19:789-94. [PMID: 1708124 PMCID: PMC333712 DOI: 10.1093/nar/19.4.789] [Citation(s) in RCA: 216] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Modifiers of position-effect-variegation in Drosophila encode proteins that are thought to modify chromatin, rendering it heritably changed in its expressibility. In an attempt to identify similar modifier genes in other species we have utilized a known sequence homology, termed chromo box, between a suppressor of position-effect-variegation, Heterochromatin protein 1 (HP1), and a repressor of homeotic genes, Polycomb (Pc). A PCR generated probe encompassing the HP1 chromo box was used to clone full-length murine cDNAs that contain conserved chromo box motifs. Sequence comparisons, in situ hybridization experiments, and RNA Northern blot analysis suggest that the murine and human sequences presented in this report are homologues of the Drosophila HP1 gene. Chromo box sequences can also be detected in other animal species, and in plants, predicting a strongly conserved structural role for the peptide encoded by this sequence. We propose that epigenetic (yet heritable) changes in gene expressibility, characteristic of chromosomal imprinting phenomena, can largely be explained by the action of such modifier genes. The evolutionary conservation of the chromo box motif now enables the isolation and study of putative modifier genes in those animal and plant species where chromosomal imprinting has been described.
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Affiliation(s)
- P B Singh
- Department of Molecular Embryology, Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK
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41
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Laird CD. Possible erasure of the imprint on a fragile X chromosome when transmitted by a male. AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 38:391-5. [PMID: 2018078 DOI: 10.1002/ajmg.1320380247] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Although most males with the fragile-X [fra(X)] syndrome do not reproduce, there are 2 published pedigrees that include affected males who have daughters and who thus appear to have transmitted the fragile-X chromosome to their progeny. In addition, one published fra(X) pedigree includes an apparently normal male who expresses cytogenetically the fra(X) site at high frequency and who has 3 daughters. In the 6 daughters of these 3 males, there is little or no cytogenetic expression of the fra(X). I interpret these pedigrees within the context of my X-inactivation imprinting model of the fra(X) syndrome (Genetics 117:587-599): the cytogenetic manifestation of the imprinted state of the mutant fra(X) chromosome [high percentage of cytogenetic expression] is no longer present in daughters of imprinted males. I propose that the imprinted state is erased when an imprinted fragile-X chromosome is passed through a male. Such erasure in the gender opposite to the gender that established the imprint is in accord with other examples of chromosome imprinting in mammals. Additional data from unpublished fra(X) pedigrees are requested.
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Affiliation(s)
- C D Laird
- Department of Zoology, University of Washington, Seattle 98195
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42
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Peters J, Ball ST. Parental influences on expression of glucose-6-phosphate dehydrogenase, G6pd, in the mouse; a case of imprinting. Genet Res (Camb) 1990; 56:245-52. [PMID: 2272515 DOI: 10.1017/s0016672300035345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Glucose-6-phosphate dehydrogenase (G6PD) activity was measured in blood from heterozygotes for the normal allele G6pda and the low activity allele G6pda-mlNeu. In adult mice lower activity was found in G6pda/G6pda-mlNeu than in the reciprocal heterozygote G6pda-mlNeu/G6pda (the maternal allele being listed first). Thus, either the paternally derived allele was over-expressed or the maternally derived allele was under-expressed. By contrast, in younger mice the difference in G6PD activity in reciprocal crosses was less marked. The findings are interpreted in terms of differential imprinting of maternally and paternally inherited information. The explanation offered for age related differences is that, as a consequence of imprinting, either the paternal X-chromosome is preferentially reactivated, or cells in which the paternally derived allele is active are at a selective advantage, and proliferate better than those in which the maternally inherited allele is active.
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Affiliation(s)
- J Peters
- MRC Radiobiology Unit, Chilton, Didcot, Oxon, U.K
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43
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Abstract
I propose that Huntington's disease (HD) is caused by dominant position-effect variegation, a phenomenon for which new information is available in Drosophila melanogaster. The essential features of this proposal are that (1) the HD mutation is the result of a chromosome alteration that inactivates transcription of a nearby structural gene or genes (cis-inactivation); the combination of this proposed chromosome alteration and the structural gene(s) is termed the HD allele; (2) there is pairing in some somatic cells between the HD and HD+ alleles on homologous chromosomes; (3) as a result of this somatic pairing, the HD mutation also inactivates transcription of the HD+ structural gene on the normal homologue (trans-inactivation), resulting in complete dominance of the mutation; (4) polymorphism for an X-linked recessive modifier of position-effect variegation means that the age of onset of symptoms of HD will depend on which parent the HD mutation was inherited from. The fully dominant nature of HD and the parental-source effect on the age of onset are thus both understandable within the genetic and epigenetic paradigm of position-effect variegation.
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Affiliation(s)
- C D Laird
- Department of Zoology, University of Washington, Seattle 98195
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44
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Affiliation(s)
- C Sapienza
- Ludwig Institute for Cancer Research, Montreal, Quebec, Canada
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45
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Expression of specific genes in early mouse embryos blocked by cytochalasin. ACTA ACUST UNITED AC 1987; 196:376-380. [DOI: 10.1007/bf00375775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/1987] [Accepted: 08/04/1987] [Indexed: 10/26/2022]
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Bücher T, Linke IM, Dünnwald M, West JD, Cattanach BM. Xce genotype has no impact on the effect of imprinting on X-chromosome expression in the mouse yolk sac endoderm. Genet Res (Camb) 1986; 47:43-8. [PMID: 3957037 DOI: 10.1017/s0016672300024496] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
SummaryThe effect of theXce(x-chromosome controlling element) genotype on the randomness ofX-chromosome inactivation in the mouse was studied by monitoring the expression of theX-linked locuspgk-1. The main aim was to test whether theXcegenotype modified the preferential expression of the maternally derivedX-chromosome in the yolk sac endoderm. Quantitative electrophoresis of phosphoglycerate kinase (PGK-1) was used to studyPgk-1expression in the foetus, yolk sac mesoderm and yolk sac endoderm at 13½ dayspost coitum. TheXcea/Xcecgenotype caused non-randomX-chromosome expression in the foetus and yolk sac mesoderm. However, there was no evidence that theXcegenotype moderates the preferential expression of the maternally derivedX-chromosome in the yolk sac endoderm, as reported by Rastan & Cattanach (1983).
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47
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48
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Lyon MF, Rastan S. Parental source of chromosome imprinting and its relevance for X chromosome inactivation. Differentiation 1984; 26:63-7. [PMID: 6714546 DOI: 10.1111/j.1432-0436.1984.tb01375.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In imprinting, homologous chromosomes behave differently during development according to their parental origin. Typically, paternally derived chromosomes are preferentially inactivated or eliminated. Examples of such phenomena include inactivation of the mammalian X chromosome, inactivation or elimination of one haploid chromosome set in male coccids, and elimination of paternal X chromosomes in the fly Sciara. It has generally been thought that the paternal chromosomes bear an imprint leading to their inactivation or elimination. However, alteration of the parental origin of chromosomes, as in the study of parthenogenotes in mammals and coccids, shows that passage of chromosomes through a male germ cell or fertilization is not essential for inactivation or elimination. It appears that neither chromosome set is programmed to resist or undergo inactivation. Instead the two sets differ in relative sensitivity, and the question is whether the maternal set have an imprint for resistance, or the paternal set one for susceptibility. Very early in development of mammals both X chromosomes are active. This makes it simpler to envisage the maternal X bearing an imprint for resistance to inactivation, which persists through the early developmental period. Similar considerations also apply in coccids and Sciara. Thus, imprinting should be regarded as a phenomenon conferred on the maternal chromosomes in the oocyte. This permits simpler models for the mechanism of X-inactivation, and weakens the case for evolution of X-inactivation from an earlier form of inactivation during male gametogenesis. One may speculate whether imprinting affects timing of gene action in development.
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49
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Vandeberg JL. Developmental aspects of X chromosome inactivation in eutherian and metatherian mammals. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1983; 228:271-86. [PMID: 6363606 DOI: 10.1002/jez.1402280211] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The single active X principle has served for two decades as a focal point for research on the cyclic activation and inactivation of gene loci. Differences in X chromosome inactivation patterns of eutherian and marsupial mammals provide probes for investigating the mechanisms of the X inactivation process. In eutherian mammals, the X chromosome is inactivated early in meiotic prophase in males and remains inactive throughout the rest of spermatogenesis. During meiosis in females, the inactive X chromosome is activated so that both X chromosomes are active in oocytes. During the early cleavage divisions of female embryos, the paternally derived X is activated. It and the maternally derived X remain active until differentiation begins in early embryogenesis. At that time, the paternally derived X is inactivated in cells that give rise to extraembryonic membranes, whereas a random process determines which X chromosome is inactivated in cells that give rise to the embryo itself. Although less is known about developmental aspects of X inactivation in female marsupials, it is clear that the paternal X is preferentially inactive in postembryonic somatic cells. Furthermore, the paternal X is partially active at some loci in some cell types, indicating that it is not regulated as a single unit. The successful adaptation of a small (80-150 g), fecund marsupial to simple laboratory conditions now enables extensive experimentation on the large number of marsupials at various developmental stages. This capability, coupled with the application of newly developed cellular and molecular techniques to questions about X chromosome inactivation, shows great promise for advancing our understanding of the mechanisms that control the cyclic behavior of X chromosome activity.
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The mealybug chromosome system I: Unusual methylated bases and dinucleotides in DNA of aPlanococcus species. J Biosci 1982. [DOI: 10.1007/bf02704646] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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