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Oliveira JIN, Cabral-de-Mello DC, Valente GT, Martins C. Transcribing the enigma: the B chromosome as a territory of uncharted RNAs. Genetics 2024; 227:iyae026. [PMID: 38513121 DOI: 10.1093/genetics/iyae026] [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: 12/11/2023] [Accepted: 02/10/2024] [Indexed: 03/23/2024] Open
Abstract
B chromosomes are supernumerary elements found in several groups of eukaryotes, including fungi, plants, and animals. Typically, these chromosomes either originate from their hosts through errors in meiosis or interspecifically through horizontal transfer. While many B chromosomes are primarily heterochromatic and possess a low number of coding genes, these additional elements are still capable of transcribing sequences and exerting influence on the expression of host genes. How B chromosomes escape elimination and which impacts can be promoted in the cell always intrigued the cytogeneticists. In pursuit of understanding the behavior and functional impacts of these extra elements, cytogenetic studies meet the advances of molecular biology, incorporating various techniques into investigating B chromosomes from a functional perspective. In this review, we present a timeline of studies investigating B chromosomes and RNAs, highlighting the advances and key findings throughout their history. Additionally, we identified which RNA classes are reported in the B chromosomes and emphasized the necessity for further investigation into new perspectives on the B chromosome functions. In this context, we present a phylogenetic tree that illustrates which branches either report B chromosome presence or have functional RNA studies related to B chromosomes. We propose investigating other unexplored RNA classes and conducting functional analysis in conjunction with cytogenetic studies to enhance our understanding of the B chromosome from an RNA perspective.
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Affiliation(s)
| | - Diogo C Cabral-de-Mello
- Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro 13506-900, Brazil
| | - Guilherme T Valente
- Applied Biotechnology Laboratory, Clinical Hospital of Botucatu Medical School, Botucatu 18618-687, Brazil
| | - Cesar Martins
- Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, São Paulo State University (UNESP), Botucatu 18618-689, Brazil
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COSTA MARIAKÁTIAMATIOTTIDA, SILVA ANELISEFERNANDESE, ACOSTA RIULERCORRÊA, ZEFA EDISON. Sperberacris, a new Neotropical genus of Gomphocerinae (Orthoptera: Acridoidea: Acrididae) from State of Alagoas, Brazil with chromosome complement. Zootaxa 2023; 5228:73-80. [PMID: 37044664 DOI: 10.11646/zootaxa.5228.1.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Indexed: 01/11/2023]
Abstract
Sperberacris, a new Neotropical genus of Amblytropidiini. Sperberacris muriciensis n. sp. (type species) from the municipality of Murici, State of Alagoas, Brazil is described. The new genus differs from other tribe congenera by the epiproct suboval, furculae divided into four long sclerotized lobes, cerci curved inward, apex truncated and sclerotized at the tip and convex bridge of the epiphallus with two large black sclerotized spots. The new species presents a diploid number of 2n = 23, X0♂/24, XX♀, and the karyotype is made up of telo/acrocentric chromosomes, with one dot-like B chromosome occurring in some nuclei. Morphological descriptions are provided along with illustrations emphasizing the most significant diagnostic features of external morphology and male genitalia. Information on type specimens, material examined, and distribution provided.
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Melo AS, Cruz GAS, Félix AP, Rocha MF, Loreto V, Moura RC. Wide dispersion of B chromosomes in Rhammatocerus brasiliensis (Orthoptera, Acrididae). Genet Mol Biol 2020; 43:e20190077. [PMID: 32542305 PMCID: PMC7295183 DOI: 10.1590/1678-4685-gmb-2019-0077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 07/16/2019] [Indexed: 01/01/2023] Open
Abstract
The grasshopper Rhammatocerus brasiliensis shows polymorphism of B chromosomes, but the magnitude of B-chromosome occurrence and the factors that may contribute to their dispersion in the species remain unknown thus far. The present study analyzed the occurrence and dispersion of B chromosomes in R. brasiliensis individuals from 21 populations widely distributed in the Brazilian Northeast. The genetic connectivity between 10 populations was verified through analysis of ISSR markers from 200 individuals. Of the 21 populations, 19 presented individuals with one B chromosome, three with two, and one with three B chromosomes. The B chromosome is of medium size and constitutive heterochromatin (CH) located in the pericentromeric region. A variant B chromosome was observed in three populations, similar in size to that of chromosome X, gap and CH, and located in the terminal region. B chromosome frequencies in different populations varied from 0% to 18,8%, mean 8,5%. The wide distribution of the B chromosome is likely a consequence of the positive gene flow among the analyzed populations. B-chromosome occurrence in populations of R. brasiliensis possibly follows the population genetic structure of the species and, owing to the existence of a variant, its origin may not be recent.
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Affiliation(s)
- Adriana S Melo
- Universidade de Pernambuco (UPE), Instituto de Ciências Biológicas, Laboratório de Biodiversidade e Genética de Insetos, Recife, PE, Brazil
| | - Geyner A S Cruz
- Universidade de Pernambuco (UPE), Instituto de Ciências Biológicas, Laboratório de Biodiversidade e Genética de Insetos, Recife, PE, Brazil
- Universidade de Pernambuco (UPE), Laboratório de Biodiversidade e Genética Evolutiva, Campus Petrolina, Petrolina, PE, Brazil
| | - Aline P Félix
- Universidade de Pernambuco (UPE), Instituto de Ciências Biológicas, Laboratório de Biodiversidade e Genética de Insetos, Recife, PE, Brazil
| | - Marília F Rocha
- Universidade de Pernambuco (UPE), Instituto de Ciências Biológicas, Laboratório de Biodiversidade e Genética de Insetos, Recife, PE, Brazil
| | - Vilma Loreto
- Universidade Federal de Pernambuco (UFPE), Departamento de Genética, Laboratório de Genética Animal e Humana e Citogenética, Recife, PE, Brazil
| | - Rita C Moura
- Universidade de Pernambuco (UPE), Instituto de Ciências Biológicas, Laboratório de Biodiversidade e Genética de Insetos, Recife, PE, Brazil
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Pine MB, Gallo RB, da Silva CRM, Pezenti LF, Domenico FCD, Loreto V, da Rosa R. Chromosome mapping in Abracris flavolineata (De Geer, 1773) (Orthoptera) from the Iguaçu National Park - Foz do Iguaçu, Paraná, Brazil. COMPARATIVE CYTOGENETICS 2017; 11:203-212. [PMID: 28919959 PMCID: PMC5596987 DOI: 10.3897/compcytogen.v11i2.10282] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 02/01/2017] [Indexed: 06/07/2023]
Abstract
In this paper, we present the cytomolecular analysis of a population of Abracris flavolineata collected in the largest fragment of the Brazilian Atlantic forest, the Iguaçu National Park. The diploid number in males was 23 (22+X0), with two large pairs (1-2), 7 medium (3-9), 2 small (10-11) and the X chromosome of medium size. Heterochromatic blocks were evident in the pericentromeric regions of all chromosomes. Heterogeneity in the distribution of heterochromatin was observed, with a predominance of DAPI+ blocks. However, some chromosomes showed CMA3+ blocks and other DAPI+/CMA3+ blocks. The 18S rDNA sites were distributed on the short arms of 5 pairs. In two of these pairs, such sites were in the same chromosome bearing 5S rDNA, and one of the bivalents, they were co-located. Histone H3 genes were found on one bivalent. The results added to the existing cytogenetic studies provided evidence of great karyotypic plasticity in the species. This pliancy may be the result of vicariant events related to the geographical distribution of different populations of A. flavolineata.
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Affiliation(s)
- Mariana Bozina Pine
- Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina (UEL), Londrina, Paraná, Brazil
| | - Raquel Bozini Gallo
- Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina (UEL), Londrina, Paraná, Brazil
| | | | - Larissa Forim Pezenti
- Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina (UEL), Londrina, Paraná, Brazil
| | | | - Vilma Loreto
- Departamento de Genética, CCB, Universidade Federal de Pernambuco, Recife, Brazil
| | - Renata da Rosa
- Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina (UEL), Londrina, Paraná, Brazil
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Grzywacz B, Chobanov DP, Maryańska-Nadachowska A, Karamysheva TV, Heller KG, Warchałowska-Śliwa E. A comparative study of genome organization and inferences for the systematics of two large bushcricket genera of the tribe Barbitistini (Orthoptera: Tettigoniidae: Phaneropterinae). BMC Evol Biol 2014; 14:48. [PMID: 24625118 PMCID: PMC3975230 DOI: 10.1186/1471-2148-14-48] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 02/24/2014] [Indexed: 11/20/2022] Open
Abstract
Background Poecilimon and Isophya are the largest genera of the tribe Barbitistini and among the most systematically complicated and evolutionarily intriguing groups of Palearctic tettigoniids. We examined the genomic organization of 79 taxa with a stable chromosome number using classical (C–banding, silver and fluorochrome staining) and molecular (fluorescence in situ hybridization with 18S rDNA and (TTAGG)n telomeric probes) cytogenetic techniques. These tools were employed to establish genetic organization and differences or similarities between genera or species within the same genus and determine if cytogenetic markers can be used for identifying some taxonomic groups of species. Results Differences between the karyotypes of the studied genera include some general changes in the morphology of the X chromosome in Isophya (in contrast to Poecilimon). The number of major rDNA clusters per haploid genome divided Poecilimon into two main almost equal groups (with either one or two clusters), while two rDNA clusters predominated in Isophya. In both genera, rDNA loci were preferentially located in the paracentromeric region of the autosomes and rarely in the sex chromosomes. Our results demonstrate a coincidence between the location of rDNA loci and active NORs and GC-rich heterochromatin regions. The C/DAPI/CMA3 bands observed in most Poecilimon chromosomes suggest the presence of more families of repetitive DNA sequences as compared to the heterochromatin patterns in Isophya. Conclusions The results show both differences and similarities in genome organization among species of the same genus and between genera. Previous views on the systematics and phylogenetic grouping of certain lineages are discussed in light of the present cytogenetic results. In some cases, variation of chromosome markers was observed to correspond with variation in other evolutionary traits, which is related to the processes of ongoing speciation and hybridization in zones of secondary contact. It was concluded that the physical mapping of rDNA sequences and heterochromatin may be used as an additional marker for understanding interspecific relationships in these groups and their routes of speciation.
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Affiliation(s)
- Beata Grzywacz
- Institute of Systematics and Evolution of Animals Polish Academy of Sciences, Sławkowska 17, Krakow 31-016, Poland.
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Warchałowska-Śliwa E, Grzywacz B, Maryańska-Nadachowska A, Karamysheva TV, Heller KG, Lehmann AW, Lehmann GUC, Chobanov DP. Molecular and classical chromosomal techniques reveal diversity in bushcricket genera of Barbitistini (Orthoptera). Genome 2013; 56:667-76. [PMID: 24299106 DOI: 10.1139/gen-2013-0119] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The cytogenetic characteristics of 17 species of bushcricket belonging to eight genera of the tribe Barbitistini were examined by fluorescence in situ hybridization with 18S rDNA and (TTAGGn) telomeric as probes and by C-banding, silver, and fluorochrome staining. These markers were used to understand chromosomal organization and evolutionary relationships between genera or species within the same genus. The number of 18S rDNA clusters per haploid genome that co-localized with active nucleolus organizer regions (NORs) ranged from one to five, with the most common pattern being the presence of one NOR-bearing chromosome. This ribosomal cistron was preferentially located in the paracentromeric region of autosomes and very rarely in the sex chromosome. The results demonstrated coincidence between the localization of major ribosomal genes and active NORs and the position of C-band and GC-rich regions. The rDNA/NOR distribution and the composition of chromosome heterochromatin proved to be good cytogenetic markers for distinguishing species and phylogenetic lines and for understanding the genomic differentiation and evolution of Barbitistini. A comparison of cytogenetic and morphological or behavioral traits suggests that morphological and behavioral specialization in this group was not followed by major karyotype modification (except for Leptophyes). However, the occurrence and distribution of different repetitive DNA sites tends to vary among the taxa.
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Affiliation(s)
- E Warchałowska-Śliwa
- a Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Kraków, Poland
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Anjos A, Loreto V, de Souza MJ. Chromosome mapping of ribosomal genes and histone H4 in the genus Radacridium (Romaleidae). Genet Mol Biol 2013; 36:336-40. [PMID: 24130439 PMCID: PMC3795169 DOI: 10.1590/s1415-47572013005000026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 03/12/2013] [Indexed: 11/22/2022] Open
Abstract
In this study, two species of Romaleidae grasshoppers, Radacridium mariajoseae and R.nordestinum, were analyzed after CMA3/DA/DAPI sequential staining and fluorescence in situ hybridization (FISH) to determine the location of the 18S and 5S rDNA and histone H4 genes. Both species presented karyotypes composed of 2n = 23, X0 with exclusively acrocentric chromosomes. CMA3+ blocks were detected after CMA3/DA/DAPI staining in only one medium size autosome bivalent and in the X chromosome in R. mariajoseae. On the other hand, all chromosomes, except the L1 bivalent, of R. nordestinum presented CMA3+ blocks. FISH analysis showed that the 18S genes are restricted to the X chromosome in R. mariajoseae, whereas these genes were located in the L2, S9 and S10 autosomes in R. nordestinum. In R. mariajoseae, the 5S rDNA sites were localized in the in L1 and L2 bivalents and in the X chromosome. In R. nordestinum, the 5S genes were located in the L2, L3, M4 and M5 pairs. In both species the histone H4 genes were present in a medium size bivalent. Together, these data evidence a great variability of chromosome markers and show that the 18S and 5S ribosomal genes are dispersed in the Radacridium genome without a significant correlation.
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Affiliation(s)
- Allison Anjos
- Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Recife, PE, Brazil
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Drosopoulou E, Nakou I, Síchová J, Kubíčková S, Marec F, Mavragani-Tsipidou P. Sex chromosomes and associated rDNA form a heterochromatic network in the polytene nuclei of Bactrocera oleae (Diptera: Tephritidae). Genetica 2012; 140:169-80. [PMID: 22825842 DOI: 10.1007/s10709-012-9668-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 07/11/2012] [Indexed: 10/28/2022]
Abstract
The olive fruit fly, Bactrocera oleae, has a diploid set of 2n = 12 chromosomes including a pair of sex chromosomes, XX in females and XY in males, but polytene nuclei show only five polytene chromosomes, obviously formed by five autosome pairs. Here we examined the fate of the sex chromosomes in the polytene complements of this species using fluorescence in situ hybridization (FISH) with the X and Y chromosome-derived probes, prepared by laser microdissection of the respective chromosomes from mitotic metaphases. Specificity of the probes was verified by FISH in preparations of mitotic chromosomes. In polytene nuclei, both probes hybridized strongly to a granular heterochromatic network, indicating thus underreplication of the sex chromosomes. The X chromosome probe (in both female and male nuclei) highlighted most of the granular mass, whereas the Y chromosome probe (in male nuclei) identified a small compact body of this heterochromatic network. Additional hybridization signals of the X probe were observed in the centromeric region of polytene chromosome II and in the telomeres of six polytene arms. We also examined distribution of the major ribosomal DNA (rDNA) using FISH with an 18S rDNA probe in both mitotic and polytene chromosome complements of B. oleae. In mitotic metaphases, the probe hybridized exclusively to the sex chromosomes. The probe signals localized a discrete rDNA site at the end of the short arm of the X chromosome, whereas they appeared dispersed over the entire dot-like Y chromosome. In polytene nuclei, the rDNA was found associated with the heterochromatic network representing the sex chromosomes. Only in nuclei with preserved nucleolar structure, the probe signals were scattered in the restricted area of the nucleolus. Thus, our study clearly shows that the granular heterochromatic network of polytene nuclei in B. oleae is formed by the underreplicated sex chromosomes and associated rDNA.
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Affiliation(s)
- Elena Drosopoulou
- Department of Genetics, Development and Molecular Biology, School of Biology, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Oliveira NL, Cabral-de-Mello DC, Rocha MF, Loreto V, Martins C, Moura RC. Chromosomal mapping of rDNAs and H3 histone sequences in the grasshopper rhammatocerus brasiliensis (acrididae, gomphocerinae): extensive chromosomal dispersion and co-localization of 5S rDNA/H3 histone clusters in the A complement and B chromosome. Mol Cytogenet 2011; 4:24. [PMID: 22075079 PMCID: PMC3234176 DOI: 10.1186/1755-8166-4-24] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/10/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Supernumerary B chromosomes occur in addition to standard karyotype and have been described in about 15% of eukaryotes, being the repetitive DNAs the major component of these chromosomes, including in some cases the presence of multigene families. To advance in the understanding of chromosomal organization of multigene families and B chromosome structure and evolution, the distribution of rRNA and H3 histone genes were analyzed in the standard karyotype and B chromosome of three populations of the grasshopper Rhammatocerus brasiliensis. RESULTS The location of major rDNA was coincident with the previous analysis for this species. On the other hand, the 5S rDNA mapped in almost all chromosomes of the standard complement (except in the pair 11) and in the B chromosome, showing a distinct result from other populations previously analyzed. Besides the spreading of 5S rDNA in the genome of R. brasiliensis it was also observed multiple sites for H3 histone genes, being located in the same chromosomal regions of 5S rDNAs, including the presence of the H3 gene in the B chromosome. CONCLUSIONS Due to the intense spreading of 5S rRNA and H3 histone genes in the genome of R. brasiliensis, their chromosomal distribution was not informative in the clarification of the origin of B elements. Our results indicate a linked organization for the 5S rRNA and H3 histone multigene families investigated in R. brasiliensis, reinforcing previous data concerning the association of both genes in some insect groups. The present findings contribute to understanding the organization/evolution of multigene families in the insect genomes.
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Affiliation(s)
- Nathalia L Oliveira
- Departamento de Biologia, Instituto de Ciências Biológicas, UPE - Universidade de Pernambuco, Recife, Pernambuco, Brazil.
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Carvalho D, Rocha M, Loreto V, Silva A, Souza M. Ommexecha virens (Thunberg, 1824) and Descampsacris serrulatum (Serville, 1831) (Orthoptera, Ommexechidae): karyotypes, constitutive heterochromatin and nucleolar organizing regions. COMPARATIVE CYTOGENETICS 2011; 5:123-132. [PMID: 24260624 PMCID: PMC3833735 DOI: 10.3897/compcytogen.v5i2.960] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 05/19/2011] [Indexed: 06/02/2023]
Abstract
Chromosomes of Ommexecha virens and Descampsacris serrulatum (Ommexechidae) were analyzed through conventional staining, C-banding, base specific fluorochromes, silver nitrate impregnation (AgNO3), and fluorescent in situ hybridization (FISH) with probe for 45S rDNA. The two species presented diploid number 2n= 23,X0 in males and acrocentric autosomes, except the pair one that presented submetacentric morphology. The X chromosome has distinct morphology in the two analyzed species, being a medium acrocentric in Ommexecha virens and large submetacentric in Descampsacris serrulatum. The C-banding revealed pericentromeric blocks of constitutive heterochromatin (CH) in all the chromosomes of Descampsacris serrulatum. For Ommexecha virens it was evidenced that the blocks of CH are preferentially located in the pericentromeric area (however some bivalents presents additional blocks) or in different positions. The staining with CMA3/DA/DAPI showed GC rich CH blocks (CMA3+) in some chromosomes of the two species. The nucleolar organizer regions (NORs) were located in the bivalents L2, S9, S10 of Ommexecha virens and M5, M6, M7, S11 of Descampsacris serrulatum. The FISH for rDNA showed coincident results with the pattern of active NORs revealed by AgNO3. This work presents the first chromosomal data, obtained through differential cytogenetics techniques in Ommexechidae, contributing to a better characterization of karyotypic evolution for this grasshopper family.
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Affiliation(s)
- D.B. Carvalho
- Departamento de Genética, Centro de Ciências Biológicas/CCB, Universidade Federal de Pernambuco/ UFPE, Av. Prof. Moraes Rego s/n, Recife, Pernambuco, Brasil CEP:50732-970
| | - M.F. Rocha
- Instituto de Ciências Biológicas/ICB, Universidade de Pernambuco /UPE, Recife, Pernambuco, Brasil
| | - V. Loreto
- Departamento de Genética, Centro de Ciências Biológicas/CCB, Universidade Federal de Pernambuco/ UFPE, Av. Prof. Moraes Rego s/n, Recife, Pernambuco, Brasil CEP:50732-970
| | - A.E.B. Silva
- Departamento de Botânica, Centro de Ciências Biológicas/CCB, Universidade Federal de Pernambuco/ UFPE
| | - M.J. Souza
- Departamento de Genética, Centro de Ciências Biológicas/CCB, Universidade Federal de Pernambuco/ UFPE, Av. Prof. Moraes Rego s/n, Recife, Pernambuco, Brasil CEP:50732-970
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de França Rocha M, de Melo NF, de Souza MJ. Comparative cytogenetic analysis of two grasshopper species of the tribe Abracrini (Ommatolampinae, Acrididae). Genet Mol Biol 2011; 34:214-9. [PMID: 21734819 PMCID: PMC3115312 DOI: 10.1590/s1415-47572011000200008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2010] [Accepted: 01/19/2011] [Indexed: 11/25/2022] Open
Abstract
The grasshopper species Orthoscapheus rufipes and Eujivarus fusiformis were analyzed using several cytogenetic techniques. The karyotype of O. rufipes, described here for the first time, had a diploid number of 2n = 23, whereas E. fusiformis had a karyotype with 2n = 21. The two species showed the same mechanism of sex determination (XO type) but differed in chromosome morphology. Pericentromeric blocks of constitutive heterochromatin (CH) were detected in the chromosome complement of both species. CMA3/DA/DAPI staining revealed CMA3-positive blocks in CH regions in four autosomal bivalents of O. rufipes and in two of E. fusiformis. The location of active NORs differed between the two species, occurring in bivalents M6 and S9 of O. rufipes and M6 and M7 of E. fusiformsi. The rDNA sites revealed by FISH coincided with the number and position of the active NORs detected by AgNO3 staining. The variability in chromosomal markers accounted for the karyotype differentiation observed in the tribe Abracrini.
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Affiliation(s)
- Marília de França Rocha
- Laboratório de Biodiversidade e Genética de Insetos, Instituto de Ciências Biológicas, Universidade de Pernambuco, Recife, PE, Brazil
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Mandrioli M, Azzoni P, Lombardo G, Manicardi GC. Composition and epigenetic markers of heterochromatin in the aphid Aphis nerii (Hemiptera: Aphididae). Cytogenet Genome Res 2011; 133:67-77. [PMID: 21273762 DOI: 10.1159/000323510] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2010] [Indexed: 11/19/2022] Open
Abstract
A detailed karyotype analysis of the oleander aphid Aphis nerii focusing on the distribution, molecular composition and epigenetic modifications of heterochromatin was done in order to better understand the structure and evolution of holocentric/holokinetic chromosomes in aphids. The female karyotype (2n = 8) consisted of 3 pairs of autosomes and a pair of X chromosomes that were the longest elements in the karyotype and carried a single, terminally located nucleolar organizer region. Males showed 2n = 7 chromosomes due to the presence of a single X chromosome. Heterochromatin was located in the X chromosomes only and consisted of 4 satellite DNAs that have been identified. A. nerii constitutive heterochromatin was enriched in mono-, di- and tri-methylated H3 histones and HP1 proteins but, interestingly, it lacked DNA methylation that was widespread in euchromatic chromosomal regions. These results suggest that aphid heterochromatin is assembled and condensed without any involvement of DNA methylation.
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Affiliation(s)
- M Mandrioli
- Dipartimento di Biologia, Università di Modena e Reggio Emilia, Modena, Italia.
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13
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Hemp C, Heller KG, Warchałowska-Śliwa E, Hemp A. A new genus and species of African Phaneropterinae (Orthoptera: Tettigoniidae), with data on its ecology, bioacoustics and chromosomes. ORG DIVERS EVOL 2010. [DOI: 10.1007/s13127-010-0013-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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