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Aphids and Ants, Mutualistic Species, Share a Mariner Element with an Unusual Location on Aphid Chromosomes. Genes (Basel) 2021; 12:genes12121966. [PMID: 34946915 PMCID: PMC8701394 DOI: 10.3390/genes12121966] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/07/2021] [Accepted: 12/07/2021] [Indexed: 12/20/2022] Open
Abstract
Aphids (Hemiptera, Aphididae) are small phytophagous insects. The aim of this study was to determine if the mariner elements found in the ant genomes are also present in Aphis fabae and Aphis hederae genomes and the possible existence of horizontal transfer events. Aphids maintain a relationship of mutualism with the ants. The close contact between these insects could favour horizontal transfer events of transposable elements. Myrmar mariner element isolated from Myrmica ruginodis and Tapinoma ibericum ants have also been found in the two Aphis species: A. fabae and A. hederae (Afabmar-Mr and Ahedmar-Mr elements). Besides, Afabmar-Mr could be an active transposon. Myrmar-like elements are also present in other insect species as well as in one Crustacean species. The phylogenetic study carried out with all Myrmar-like elements suggests the existence of horizontal transfer. Most aphids have 2n = 8 with a XX-X0 sex determination system. Their complicated life cycle is mostly parthenogenetic with sexual individuals only in autumn. The production of X0 males, originated by XX females which produce only spermatozoa with one X chromosome, must necessarily occur through specialized cytogenetic and molecular mechanisms which are not entirely known. In both aphid species, the mariner elements are located on all chromosomes, including the X chromosomes. However, on the two X chromosomes, no positive signals are detected in their small DAPI-negative telomere regions. The rDNA sites are located, as in the majority of Aphids species, on one of the telomere regions of each X chromosome. The hybridization patterns obtained by double FISH demonstrate that Afabmar-Mr and Ahedmar-Mr elements do not hybridize at the rDNA sites of their host species. Possible causes for the absence of these transposons in the rDNA genes are discussed, probably related with the X chromosome biology.
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Manicardi GC, Mandrioli M, Blackman RL. The cytogenetic architecture of the aphid genome. Biol Rev Camb Philos Soc 2014; 90:112-25. [PMID: 24593177 DOI: 10.1111/brv.12096] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 02/04/2014] [Accepted: 02/07/2014] [Indexed: 12/28/2022]
Abstract
In recent years aphids, with their well-defined polyphenism, have become favoured as model organisms for the study of epigenetic processes. The availability of the pea aphid (Acyrthosiphon pisum) genome sequence has engendered much research aimed at elucidating the mechanisms by which the phenotypic plasticity of aphids is inherited and controlled. Yet so far this research effort has paid little attention to the cytogenetic processes that play a vital part in the organisation, expression and inheritance of the aphid genome. Aphids have holocentric chromosomes, which have very different properties from the chromosomes with localised centromeres that are found in most other organisms. Here we review the diverse forms of aphid chromosome behaviour that occur during sex determination and male and female meiosis, often in response to environmental changes and mediated by endocrine factors. Remarkable differences occur, even between related species, that could have significant effects on the inheritance of all or parts of the genome. In relation to this, we review the particular features of the distribution of heterochromatin, rDNA genes and other repetitive DNA in aphid chromosomes, and discuss the part that these may play in the epigenetic modification of chromatin structure and function.
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Affiliation(s)
- Gian Carlo Manicardi
- Department of Life Sciences, University of Modena and Reggio Emilia, Besta Building, via Amendola 2, 42122, Reggio Emilia, Italy
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MONTI VALENTINA, MANDRIOLI MAURO, RIVI MARCO, MANICARDI GIANCARLO. The vanishing clone: karyotypic evidence for extensive intraclonal genetic variation in the peach potato aphid, Myzus persicae (Hemiptera: Aphididae). Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2011.01812.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Monti V, Giusti M, Bizzaro D, Manicardi GC, Mandrioli M. Presence of a functional (TTAGG)(n) telomere-telomerase system in aphids. Chromosome Res 2011; 19:625-33. [PMID: 21667174 DOI: 10.1007/s10577-011-9222-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/18/2011] [Accepted: 05/20/2011] [Indexed: 11/28/2022]
Abstract
The structure of the telomeres of four aphid species (Acyrthosiphon pisum, Megoura viciae, Myzus persicae and Rhopalosiphum padi) was evaluated by Southern blotting and fluorescent in situ hybridization, revealing that each chromosomal end consists of a (TTAGG)(n) repeat. The presence of a telomerase coding gene has been verified successively in the A. pisum genome, revealing that aphid telomerase shares sequence identity ranging from 12% to 18% with invertebrate and vertebrate homologues, and possesses the two main domains involved in telomerase activity. Interestingly, telomerase expression has been verified in different somatic tissues suggesting that, in aphids, telomerase activity is not as restricted as in human cells. The study of telomeres in a M. persicae strain with a variable chromosome number showed that aphid telomerase can initiate the de novo synthesis of telomere sequences at internal breakpoints, resulting in the stabilization of chromosomal fragments.
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Affiliation(s)
- Valentina Monti
- Dipartimento di Biologia, Università di Modena e Reggio Emilia, Via Campi 213/D, 41125 Modena, Italy
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Monti V, Manicardi GC, Mandrioli M. Cytogenetic and molecular analysis of the holocentric chromosomes of the potato aphid Macrosiphum euphorbiae (Thomas, 1878). COMPARATIVE CYTOGENETICS 2011; 5:163-72. [PMID: 24260627 PMCID: PMC3833776 DOI: 10.3897/compcytogen.v5i3.1724] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 07/19/2011] [Indexed: 05/08/2023]
Abstract
Cytogenetic and molecular investigations on the holocentric chromosomes of the aphid Macrosiphum euphorbiae (Thomas, 1878)have been carried out using silver staining and C-banding (followed by chromomycin A3 and DAPI staining) in order to improve our knowledge about the structure of aphid chromosomes. The C-banding pattern is peculiar since only the two X chromosomes and a single pair of autosomes presented heterochromatic bands. Silver staining and FISH with the 28S rDNA probe localized the rDNA genes on one telomere of each X chromosome that were also brightly fluorescent after chromomycin A3 staining of C-banded chromosomes, whereas all other heterochromatic bands were DAPI positive. Interestingly, a remarkable nucleolar organizing region (NOR) heteromorphism was present making the two X chromosomes easily distinguishable. Southern blotting and FISH assessed the presence of the (TTAGG)n repeat at the ends of all the Macrosiphum euphorbiae chromosomes. Karyotype analysis showed that all males possessed the X chromosome with the larger amount of rDNA suggesting a non-Mendelian inheritance of the two X chromosomes.
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Affiliation(s)
- Valentina Monti
- Dipartimento di Biologia, Università di Modena e Reggio Emilia, Via Campi 213/D, 41125 Modena, Italy
- Dipartimento di Scienze Agrarie e degli Alimenti, Università di Modena e Reggio Emilia, Via Amendola 2, 42100 Reggio Emilia, Italy
| | - Gian Carlo Manicardi
- Dipartimento di Scienze Agrarie e degli Alimenti, Università di Modena e Reggio Emilia, Via Amendola 2, 42100 Reggio Emilia, Italy
| | - Mauro Mandrioli
- Dipartimento di Biologia, Università di Modena e Reggio Emilia, Via Campi 213/D, 41125 Modena, Italy
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Monti V, Manicardi GC, Mandrioli M. Distribution and molecular composition of heterochromatin in the holocentric chromosomes of the aphid Rhopalosiphum padi (Hemiptera: Aphididae). Genetica 2010; 138:1077-84. [DOI: 10.1007/s10709-010-9493-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 08/27/2010] [Indexed: 11/24/2022]
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Bressa MJ, Larramendy ML, Papeschi AG. Heterochromatin characterization in five species of Heteroptera. Genetica 2005; 124:307-17. [PMID: 16134342 DOI: 10.1007/s10709-005-4524-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The amount, composition and location of heterochromatin in Athaumastus haematicus (Stål, 1859), Leptoglossus impictus (Stål, 1859), Phthia picta (Drury, 1770) (Coreidae), Largus rufipennis Laporte, 1832 (Largidae) and Jadera sanguinolenta (Fabricius, 1775) (Rhopalidae) are analyzed by C-banding and DAPI/ CMA fluorescent banding. As the rule for Heteroptera the possession of holokinetic chromosomes and a pre-reductional type of meiosis cytogenetically characterize these five species. Besides, all of them (except L. rufipennis) present a pair of m chromosomes. C-banding technique reveals the absence of constitutive heterochromatin in A. haematicus, scarce C-positive blocks in L. impictus and J. sanguinolenta, and C-positive heterochromatin terminally located in P. picta and L. rufipennis. All C-bands are DAPI bright, except for a DAPI dull/CMA bright band at one telomeric end of the X chromosome in L. rufipennis, which probably corresponds to a nucleolar organizing region. The results of the banding techniques are analyzed in relation to the chiasma frequency and distribution in the five species, and it is concluded that there should exist some constraints to the acquisition and/ or accumulation of heterochromatin in their karyotypes.
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Affiliation(s)
- Maria José Bressa
- Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Ciudad Autónoma de Buenos Aires, Int. Güiraldes y Costanera Norte, C1428EHA Argentina.
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Criniti A, Simonazzi G, Cassanelli S, Ferrari M, Bizzaro D, Manicardi GC. X-linked heterochromatin distribution in the holocentric chromosomes of the green apple aphid Aphis pomi. Genetica 2005; 124:93-8. [PMID: 16011007 DOI: 10.1007/s10709-004-8154-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chromatin organization in the holocentric chromosomes of the green apple aphid Aphis pomi has been investigated at a cytological level after C-banding, NOR, Giemsa, fluorochrome staining and fluorescent in situ hybridization (FISH). C-banding technique showed that heterochromatic bands are exclusively located on X chromosomes. This data represents a peculiar feature that clearly contradicts the equilocal distribution of heterochromatin typical of monocentric chromosomes. Moreover, silver staining and FISH carried out with a 28S rDNA probe localized rDNA genes on one telomere of each X chromosome; CMA3 staining reveals that these silver positive telomeres are the only GC-rich regions among A. pomi heterochromatin, whereas all other C-positive bands are DAPI positive thus containing AT-rich DNA.
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Affiliation(s)
- A Criniti
- Dipartimento di Scienze Agrarie, Università di Modena e Reggio Emilia, Reggio Emilia, Italia
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Mandrioli M, Ganassi S, Bizzaro D, Manicardi GC. Cytogenetic Analysis of the Holocentric Chromosomes of the Aphid Schizaphis Graminum. Hereditas 2004. [DOI: 10.1111/j.1601-5223.1999.t01-1-00185.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Grozeva S, Kuznetsova VG, Nokkala S. Patterns of chromosome banding in four nabid species (Heteroptera, Cimicomorpha, Nabidae) with high chromosome number karyotypes. Hereditas 2004; 140:99-104. [PMID: 15061786 DOI: 10.1111/j.1601-5223.2004.01782.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Male Nabis (Aspilaspis) indicus (Stål), N. (A.) viridulus Spinola, Himacerus (Himacerus) mirmicoides (O. Costa) (2n=32+XY) and Prostemma guttula (Fabricius) (2n=26+XY) were studied using C-banding, silver nitrate staining and base-specific fluorochrome (DAPI and CMA(3)) staining. N. indicus differed from N. viridulus in distribution pattern of C-bands, which were telomeric in the former while interstitial in the latter. H. mirmicoides showed interstitial C-bands in the majority of autosomes. P. guttula had no conspicuous C-bands in other chromosomes, but only in the Y, which was totally heterochromatic. C-heterochromatin was labelled with DAPI, indicating that it was AT-rich. In every species, both X and Y chromosomes were NOR-bearing, and the NOR regions were GC-rich. In H.mirmicoides and P. guttula, NORs showed sub-median location in the X and distal in the Y, such a pattern being probably common in Nabidae. The present paper provides new information on the genome organization and new cytological markers useful for a better insight into karyotype evolution of nabid species.
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Affiliation(s)
- S Grozeva
- Institute of Zoology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
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Shimauti ELT, Fernandez MA. In Situ Restriction Endonucleases Digestion by on the Nucleolar Organizer Region(NOR) in Neuroblast Mitotic Chromosomes of Bradysia hygida(Diptera: Sciaridae). CYTOLOGIA 2002. [DOI: 10.1508/cytologia.67.347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Bongiorni S, Mazzuoli M, Masci S, Prantera G. Facultative heterochromatization in parahaploid male mealybugs: involvement of a heterochromatin-associated protein. Development 2001; 128:3809-17. [PMID: 11585806 DOI: 10.1242/dev.128.19.3809] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The behavior of chromosomes during development of the mealybug Planococcus citri provides one of the most dramatic examples of facultative heterochromatization. In male embryos, the entire haploid paternal chromosome set becomes heterochromatic at mid-cleavage. Male mealybugs are thus functionally haploid, owing to heterochromatization (parahaploidy). To understand the mechanisms underlying facultative heterochromatization in male mealybugs, we have investigated the possible involvement of an HP-1-like protein in this process. HP-1 is a conserved, nonhistone chromosomal protein with a proposed role in heterochromatinization in other species. It was first identified in Drosophila melanogaster as a protein enriched in the constitutive heterochromatin of polytene chromosome. Using a monoclonal antibody raised against the Drosophila HP-1 in immunoblot and immunocytological experiments, we provide evidence for the presence of an HP-1-like in Planococcus citri males and females. In males, the HP-1-like protein is preferentially associated with the male-specific heterochromatin. In the developing male embryos, its appearance precedes the onset of heterochromatization. In females, the HP-1-like protein displays a scattered but reproducible localization pattern along chromosomes. The results indicate a role for an HP-1-like protein in the facultative heterochromatization process.
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Affiliation(s)
- S Bongiorni
- Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, 01100 Viterbo, Italy
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Mandrioli M, Bizzaro D, Giusti M, Manicardi GC, Bianchi U. The role of rDNA genes in X chromosome association in the aphid Acyrthosiphon pisum. Genome 1999; 42:381-6. [PMID: 10382287 DOI: 10.1139/g98-145] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Silver staining of mitotic metaphases of the aphid A. pisum reveals the presence of argentophilic bridges connecting the two X chromosomes. The presence of nucleolar material connecting sex chromosomes seems to be quite a common phenomenon in organisms belonging to very different phyla, and suggests a role of nucleolar proteins in chromosome association and disjunction. In somatic cells of A. pisum, bridges connecting X chromosomes are detectable not only after silver staining but also after CMA3 staining. This finding suggests that GC rich DNA is involved in this type of association. Molecular analysis of rDNA intergenic spacers shows several 247 bp repeats containing short sequences having a high level of homology with the chi sequence of Escherichia coli and with the consensus core region of human hypervariable minisatellites. Moreover, each 247 bp repeat presents a perfect copy of a promoter sequence for polymerase I. These aphid repeats show structural homologies with a 240 bp repeat, which is considered to be responsible for sex chromosome pairing in Drosophila, not only in view of their common presence within rDNA spacers but also for their length and structure. The presence of chi sequences in the IGS of A. pisum, by promoting unequal crossing-over between rDNA genes, could thus give rise to the nucleolar organizing region (NOR) heteromorphism described in different aphid species. Although X pairing at NORs is fundamental in aphid male determination, the presence of heteromorphism of rDNA genes does not inhibit male determination in the A. pisum clone utilized for our experiments.
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Affiliation(s)
- M Mandrioli
- Dipartimento di Biologia Animale, Università di Modena, Italy
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Mandrioli M, Manicardi GC, Bizzaro D, Bianchi U. NOR heteromorphism within a parthenogenetic lineage of the aphid Megoura viciae. Chromosome Res 1999; 7:157-62. [PMID: 10328627 DOI: 10.1023/a:1009215721904] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In parthenogenetic females of a clone of the aphid Megoura viciae (Homoptera, Aphididae), more than 50% of the cells show heteromorphism between homologous NORs which are located on one telomeric region of the two X chromosomes. Using different techniques, such as staining with the CG-specific fluorochrome chromomycin A3, silver staining and in-situ hybridization with an rDNA probe, we have shown that the observed heteromorphism is due to an unequal distribution of ribosomal genes between homologous NOR regions. The total number of rDNA genes per individual aphid remained constant. Moreover, the analysis of cells from single embroys has shown that the observed heteromorphism is not only intraclonal but also intraindividual. These data, together with the finding of X chromosomes connected by chromatin bridges between their NORs, allow us to suggest that mitotic unequal crossing over could be the main cause of NOR heteomorphism in this taxon.
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Affiliation(s)
- M Mandrioli
- Dipartimento di Biologia Animale, Università di Modena, Italy
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Bongiorni S, Cintio O, Prantera G. The relationship between DNA methylation and chromosome imprinting in the coccid Planococcus citri. Genetics 1999; 151:1471-8. [PMID: 10101170 PMCID: PMC1460555 DOI: 10.1093/genetics/151.4.1471] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The phenomenon of chromosome, or genomic, imprinting indicates the relevance of parental origin in determining functional differences between alleles, homologous chromosomes, or haploid sets. In mealybug males (Homoptera, Coccoidea), the haploid set of paternal origin undergoes heterochromatization at midcleavage and remains so in most of the tissues. This different behavior of the two haploid sets, which depends on their parental origin, represents one of the most striking examples of chromosome imprinting. In mammals, DNA methylation has been postulated as a possible molecular mechanism to differentially imprint DNA sequences during spermatogenesis or oogenesis. In the present article we addressed the role of DNA methylation in the imprinting of whole haploid sets as it occurs in Coccids. We investigated the DNA methylation patterns at both the molecular and chromosomal level in the mealybug Planococcus citri. We found that in both males and females the paternally derived haploid set is hypomethylated with respect to the maternally derived one. Therefore, in males, it is the paternally derived hypomethylated haploid set that is heterochromatized. Our data suggest that the two haploid sets are imprinted by parent-of-origin-specific DNA methylation with no correlation with the known gene-silencing properties of this base modification.
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Affiliation(s)
- S Bongiorni
- Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, 01100 Viterbo, Italy
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Manicardi GC, Mandrioli M, Bizzaro D, Bianchi U. Patterns of DNase I sensitivity in the holocentric chromosomes of the aphid Megoura viciae. Genome 1998. [DOI: 10.1139/g97-112] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using the in situ nick translation technique, we looked for the presence of DNase I sensitive sites in Megoura viciae chromosomes, to study the distribution of active or potentially active genes in aphids, a group of insects possessing holocentric chromosomes. Cytological preparations obtained by the spreading of embryo cells were treated in situ with increasing concentrations (ranging from 5 to 200 ng/mL) of DNase I. At DNase I concentrations below 50 ng/mL, only one hypersensitive site was observed, and this was located on a telomeric region of the X chromosome that contains transcriptionally active nucleolar organizing regions, as assayed by silver staining. Interestingly, at intermediate concentrations of DNase, the incorporation of biotinylated nucleotide occurred uniformly throughout all chromosomes, whereas at concentrations above 100 ng/mL, a C-like banding pattern was produced. Our data differ from results obtained with mammalian, frog, and grasshopper chromosomes, where it was found that DNase I nicking is concentrated at the distal regions of all chromosomes.Key words: aphids, holocentric chromosomes, DNase I sensitivity, nick translation.
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Manicardi GC, Bizzaro D, Mandrioli M, Bianchi U. Silver staining as a new banding technique to identify aphid chromosomes. Chromosome Res 1998; 6:55-7. [PMID: 9510511 DOI: 10.1023/a:1009270525511] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The karyotype of the aphid Aphis sambuci has been studied by means of C-banding, fluorochrome staining and AgNO3 staining. Heterochromatic areas are confined exclusively to the X chromosomes. Interestingly, silver staining produces a clear-cut longitudinal differentiation of all chromosomes, which allows reliable identification of homologues.
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Affiliation(s)
- G C Manicardi
- Dipartimento di Biologia Animale, Università di Modena, Italy.
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Bizzaro D, Manicardi GC, Bianchi U. Chromosomal localization of a highly repeated EcoRI DNA fragment in Megoura viciae (Homoptera, Aphididae) by nick translation and fluorescence in situ hybridization. Chromosome Res 1996; 4:392-6. [PMID: 8871828 DOI: 10.1007/bf02257275] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To investigate the genome of the aphid Megoura viciae at molecular level, we have studied total DNA by agarose gel electrophoresis after cleavage with different restriction endonucleases. EcoRI digestion produced a highly repeated DNA fragment, about 600 pb long. The contribution of this EcoRI element to the total genome of M. viciae was estimated at about 6% by means of densitometric scanning of agarose gel photographs. The chromosomal localization of this fragment, investigated by fluorescent in situ hybridization (FISH), constantly showed one large and two narrower fluorescent bands located on the X chromosome, all corresponding to C-positive heterochromatic areas. These results are in full accordance with the data obtained by in situ nick translation experiments carried out after EcoRI digestion, and clearly demonstrate that a substantial amount of M. viciae heterochromatin consists of EcoRI fragments which are mainly located on the X chromosome. Using the EcoRI restriction fragment as a molecular probe may be a practical tool for the investigation of taxonomic and evolutionary relationships in this group of insects.
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Affiliation(s)
- D Bizzaro
- Dipartimento di Biologia Animale, Università di Modena, Italy
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