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de Oliveira TD, de Freitas TR. Investigating the evolutionary dynamics of diploid number variation in Ctenomys (Ctenomyidae, Rodentia). Genet Mol Biol 2024; 46:e20230180. [PMID: 38315881 PMCID: PMC10842476 DOI: 10.1590/1678-4685-gmb-2023-0180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 12/22/2023] [Indexed: 02/07/2024] Open
Abstract
Contrary to predictions from classical hybrid sterility models of chromosomal speciation, some organisms display high rates of karyotype variation. Ctenomys are the current mammals with the greatest interspecific and intraspecific chromosomal variation. A large number of species have been studied cytogenetically. The diploid numbers of chromosomes range from 2n = 10 to 2n = 70. Here, we analyzed karyotype evolution in Ctenomys using comparative phylogenetic methods. We found a strong phylogenetic signal with chromosome number. This refutes the chromosomal megaevolution model, which proposes the independent accumulation of multiple chromosomal rearrangements in each closely related species. We found that Brownian motion (BM) described the observed characteristic changes more thoroughly than the Ornstein-Uhlenbeck and Early-Burst models. This suggests that the evolution of chromosome numbers occurs by a random walk along phylogenetic clades. However, our data indicate that the BM model alone does not fully characterize the chromosomal evolution of Ctenomys.
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Affiliation(s)
- Thays Duarte de Oliveira
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Animal, Porto Alegre, RS, Brazil
| | - Thales R.O. de Freitas
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Biologia Animal, Porto Alegre, RS, Brazil
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Genética e Biologia Molecular, Porto Alegre, RS, Brazil
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Borisov YM, Kalinin AA, Borisova ZZ, Krischuk IA, Sheftel BI. Karyological Differentiation of Populations of Mice Apodemus peninsulae of the Northern and Southern Baikal Regions by Additional Chromosomes. RUSS J GENET+ 2021. [DOI: 10.1134/s102279542106003x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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Vujošević M, Rajičić M, Blagojević J. B Chromosomes in Populations of Mammals Revisited. Genes (Basel) 2018; 9:E487. [PMID: 30304868 PMCID: PMC6210394 DOI: 10.3390/genes9100487] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 10/01/2018] [Accepted: 10/03/2018] [Indexed: 01/23/2023] Open
Abstract
The study of B chromosomes (Bs) started more than a century ago, while their presence in mammals dates since 1965. As the past two decades have seen huge progress in application of molecular techniques, we decided to throw a glance on new data on Bs in mammals and to review them. We listed 85 mammals with Bs that make 1.94% of karyotypically studied species. Contrary to general view, a typical B chromosome in mammals appears both as sub- or metacentric that is the same size as small chromosomes of standard complement. Both karyotypically stable and unstable species possess Bs. The presence of Bs in certain species influences the cell division, the degree of recombination, the development, a number of quantitative characteristics, the host-parasite interactions and their behaviour. There is at least some data on molecular structure of Bs recorded in nearly a quarter of species. Nevertheless, a more detailed molecular composition of Bs presently known for six mammalian species, confirms the presence of protein coding genes, and the transcriptional activity for some of them. Therefore, the idea that Bs are inert is outdated, but the role of Bs is yet to be determined. The maintenance of Bs is obviously not the same for all species, so the current models must be adapted while bearing in mind that Bs are not inactive as it was once thought.
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Affiliation(s)
- Mladen Vujošević
- Institute for Biological Research "Siniša Stanković", Department of Genetic Research, University of Belgrade, Bulevar despota Stefana 142, Belgrade 11060, Serbia.
| | - Marija Rajičić
- Institute for Biological Research "Siniša Stanković", Department of Genetic Research, University of Belgrade, Bulevar despota Stefana 142, Belgrade 11060, Serbia.
| | - Jelena Blagojević
- Institute for Biological Research "Siniša Stanković", Department of Genetic Research, University of Belgrade, Bulevar despota Stefana 142, Belgrade 11060, Serbia.
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Variation and Evolution of the Meiotic Requirement for Crossing Over in Mammals. Genetics 2016; 205:155-168. [PMID: 27838628 PMCID: PMC5223500 DOI: 10.1534/genetics.116.192690] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 11/03/2016] [Indexed: 01/08/2023] Open
Abstract
The segregation of homologous chromosomes at the first meiotic division is dependent on the presence of at least one well-positioned crossover per chromosome. In some mammalian species, however, the genomic distribution of crossovers is consistent with a more stringent baseline requirement of one crossover per chromosome arm. Given that the meiotic requirement for crossing over defines the minimum frequency of recombination necessary for the production of viable gametes, determining the chromosomal scale of this constraint is essential for defining crossover profiles predisposed to aneuploidy and understanding the parameters that shape patterns of recombination rate evolution across species. Here, I use cytogenetic methods for in situ imaging of crossovers in karyotypically diverse house mice (Mus musculus domesticus) and voles (genus Microtus) to test how chromosome number and configuration constrain the distribution of crossovers in a genome. I show that the global distribution of crossovers in house mice is thresholded by a minimum of one crossover per chromosome arm, whereas the crossover landscape in voles is defined by a more relaxed requirement of one crossover per chromosome. I extend these findings in an evolutionary metaanalysis of published recombination and karyotype data for 112 mammalian species and demonstrate that the physical scale of the genomic crossover distribution has undergone multiple independent shifts from one crossover per chromosome arm to one per chromosome during mammalian evolution. Together, these results indicate that the chromosomal scale constraint on crossover rates is itself a trait that evolves among species, a finding that casts light on an important source of crossover rate variation in mammals.
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Rudra M, Bahadur M. Heterochromatin variation among the populations of Mus terricolor Blyth, 1851 (Rodentia, Muridae) chromosome type I. COMPARATIVE CYTOGENETICS 2013; 7:139-151. [PMID: 24260696 PMCID: PMC3833757 DOI: 10.3897/compcytogen.v7i2.4136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 04/09/2013] [Indexed: 06/02/2023]
Abstract
Twenty five to thirty specimens each from ten populations of Mus terricolor of the Terai and the Dooars regions of the Darjeeling foothills of West Bengal were cytogenetically analyzed using C-banding. Results showed intra- and inter- population variation of C-band positive heterochromatin ranging from very large blocks to minute amounts or even complete absence of heterochromatin. Large blocks of centromeric C-bands were found in Bidhan Nagar, Garidhura, Malbazar, Nagrakata and Maynaguri populations in most of the autosomes, while the rest of the populations had large blocks of C-bands on a few autosomes only. Such intra- and inter- population variation may be due to accumulation of C-positive heterochromatin, which has not got fixed homogeneously in all autosome pairs. X-chromosomes invariably possess a C-banded short arm a telomeric C-band at the distal end of the long arm in all populations. The entire Y-chromosome was C-band positive with slight population differences in staining intensity. The results suggest quantitative as well as qualitative variation of C-positive heterochromatin.
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Affiliation(s)
- Mahua Rudra
- Genetics and Molecular Biology Laboratory, Department of Zoology, University of North Bengal, Siliguri-734013, West Bengal, India
| | - Min Bahadur
- Genetics and Molecular Biology Laboratory, Department of Zoology, University of North Bengal, Siliguri-734013, West Bengal, India
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7
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Romanenko SA, Volobouev V. Non-Sciuromorph rodent karyotypes in evolution. Cytogenet Genome Res 2012; 137:233-45. [PMID: 22699115 DOI: 10.1159/000339294] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Rodents are, taxonomically, the most species-rich mammalian order. They display a series of special genomic features including the highest karyotypic diversity, frequent occurrence of complex intraspecies chromosome variability, and a variety of unusual chromosomal sex determination mechanisms not encountered in other mammalian taxa. Rodents also have an abundance of cytochemically heterogeneous heterochromatin. There are also instances of extremely rapid karyotype reorganization and speciation not accompanied by significant genetic differentiation. All these peculiarities make it clear that a detailed study of rodent genomic evolution is indispensable to understand the mode and tempo of mammalian evolution. The aim of this review is to update the data obtained by classical and molecular cytogenetics as well as comparative genomics in order to outline the range of old and emerging problems that remain to be resolved.
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Affiliation(s)
- S A Romanenko
- Institute of Molecular and Cellular Biology, SB RAS, Novosibirsk, Russia.
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Romanenko SA, Perelman PL, Trifonov VA, Graphodatsky AS. Chromosomal evolution in Rodentia. Heredity (Edinb) 2012; 108:4-16. [PMID: 22086076 PMCID: PMC3238120 DOI: 10.1038/hdy.2011.110] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 10/06/2011] [Accepted: 10/07/2011] [Indexed: 11/08/2022] Open
Abstract
Rodentia is the most species-rich mammalian order and includes several important laboratory model species. The amount of new information on karyotypic and phylogenetic relations within and among rodent taxa is rapidly increasing, but a synthesis of these data is currently lacking. Here, we have integrated information drawn from conventional banding studies, recent comparative painting investigations and molecular phylogenetic reconstructions of different rodent taxa. This permitted a revision of several ancestral karyotypic reconstructions, and a more accurate depiction of rodent chromosomal evolution.
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Affiliation(s)
- S A Romanenko
- Institute of Molecular and Cellular Biology, SB RAS, Novosibirsk, Russia.
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Graphodatsky AS, Trifonov VA, Stanyon R. The genome diversity and karyotype evolution of mammals. Mol Cytogenet 2011; 4:22. [PMID: 21992653 PMCID: PMC3204295 DOI: 10.1186/1755-8166-4-22] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/12/2011] [Indexed: 01/30/2023] Open
Abstract
The past decade has witnessed an explosion of genome sequencing and mapping in evolutionary diverse species. While full genome sequencing of mammals is rapidly progressing, the ability to assemble and align orthologous whole chromosome regions from more than a few species is still not possible. The intense focus on building of comparative maps for companion (dog and cat), laboratory (mice and rat) and agricultural (cattle, pig, and horse) animals has traditionally been used as a means to understand the underlying basis of disease-related or economically important phenotypes. However, these maps also provide an unprecedented opportunity to use multispecies analysis as a tool for inferring karyotype evolution. Comparative chromosome painting and related techniques are now considered to be the most powerful approaches in comparative genome studies. Homologies can be identified with high accuracy using molecularly defined DNA probes for fluorescence in situ hybridization (FISH) on chromosomes of different species. Chromosome painting data are now available for members of nearly all mammalian orders. In most orders, there are species with rates of chromosome evolution that can be considered as 'default' rates. The number of rearrangements that have become fixed in evolutionary history seems comparatively low, bearing in mind the 180 million years of the mammalian radiation. Comparative chromosome maps record the history of karyotype changes that have occurred during evolution. The aim of this review is to provide an overview of these recent advances in our endeavor to decipher the karyotype evolution of mammals by integrating the published results together with some of our latest unpublished results.
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MITSAINAS GEORGEP, ROVATSOS MICHAILTH, RIZOU ELENII, GIAGIA-ATHANASOPOULOU EVAB. Sex chromosome variability outlines the pathway to the chromosomal evolution in Microtus thomasi (Rodentia, Arvicolinae). Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2008.01161.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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GARCIA L, PONSÀ M, EGOZCUE J, GARCIA M. Comparative chromosomal analysis and phylogeny in four Ctenomys species (Rodentia, Octodontidae). Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2000.tb01671.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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GARCIA L, PONSÀ M, EGOZCUE J, GARCIA M. Cytogenetic variation in Ctenomys perrensi (Rodentia, Octodontidae). Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2000.tb01281.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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ORTELLS MARCELOOSCAR, BARRANTES GEORGINAELIDA. A study of genetic distances and variability in several species of the genus Ctenomys (Rodentia: Octodontidae) with special references to a probable causal role of chromosomes in speciation. Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.1994.tb01009.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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NEVO EVIATAR, CORTI MARCO, HETH GIORA, BEILES AVIGDOR, SIMSON SHIMON. Chromosomal polymorphisms in subterranean mole rats: origins and evolutionary significance. Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.1988.tb00447.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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Volker M, Sonnenberg R, Ráb P, Kullmann H. Karyotype differentiation in Chromaphyosemion killifishes (Cyprinodontiformes, Nothobranchiidae). III: extensive karyotypic variability associated with low mitochondrial haplotype differentiation in C. bivittatum. Cytogenet Genome Res 2007; 116:116-26. [PMID: 17268189 DOI: 10.1159/000097429] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Accepted: 05/22/2006] [Indexed: 11/19/2022] Open
Abstract
We investigated chromosomal evolution in the African killifish species Chromaphyosemion bivittatum using a combination of cytogenetic and phylogenetic methods. Specimens from five populations were examined by conventional Giemsa staining as well as sequential chromosome banding with 4',6-diamidino-2-phenylindole (DAPI), chromomycin A(3) (CMA(3)), AgNO(3)-staining and C-banding. The cytogenetic analysis revealed variability in 2n ranging from 2n = 29 to 2n = 36 and in NF ranging from NF = 38 to NF = 44. Two populations showed an extensive chromosomal polymorphism (2n = 29-34, NF = 44 and 2n = 32-34, NF = 38-42, respectively). Karyotypic variability within and among populations was mainly due to Robertsonian translocations and heterochromatin additions, and chromosome banding patterns suggested that both types of chromosomal rearrangements were related to the presence of AT-rich heterochromatin. A phylogenetic analysis of the partial mitochondrial (mt) cytochrome b gene, using specimens from eleven populations, revealed a low degree of haplotype differentiation, which suggested a relatively recent divergence of the populations examined. This finding conformed to the low degree of morphological differentiation observed among C. bivittatum populations and might indicate fast chromosomal evolution. The high karyotypic variability may be caused by an elevated chromosomal mutation rate as well as certain aspects of the mating system and population dynamics of C. bivittatum facilitating the fixation of new chromosomal variants.
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Affiliation(s)
- M Volker
- Institut fur Evolutionsbiologie und Okologie, Rheinische Friedrich-Wilhelms-Universitat Bonn, Germany.
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Völker M, Sonnenberg R, Ráb P, Kullmann H. Karyotype differentiation in Chromaphyosemion killifishes (Cyprinodontiformes, Nothobranchiidae). II: cytogenetic and mitochondrial DNA analyses demonstrate karyotype differentiation and its evolutionary direction in C. riggenbachi. Cytogenet Genome Res 2006; 115:70-83. [PMID: 16974086 DOI: 10.1159/000094803] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Accepted: 02/21/2006] [Indexed: 11/19/2022] Open
Abstract
African killifishes of the genus Chromaphyosemion show a high degree of phenotypic and karyotypic diversity. The latter is especially pronounced in C. riggenbachi, a morphologically defined species restricted to a small distribution area in Cameroon. This study presents a detailed reconstruction of karyotype differentiation within C. riggenbachi using conventional Giemsa staining and sequential chromosome banding as well as a phylogenetic analysis based on part of the mitochondrial (mt) cytochrome b gene from eleven populations. The cytogenetic analysis revealed differences in chromosome morphology, banding patterns and/or diploid chromosome number (2n) among all populations examined. Diploid number ranged from 2n = 20 to 2n = 36 and varied mainly among populations, while C-banding patterns and NOR phenotypes showed fixed differences among populations as well as some variability within populations. The mtDNA analysis disclosed five clearly differentiated haplotype groups. Mapping the karyotype data onto the mtDNA dendrogram revealed a decrease in 2n from the most basal to the most derived groups, thus demonstrating a reduction of 2n during their evolutionary history. Our results indicate that karyotype differentiation involved Robertsonian fusions as well as non-Robertsonian processes. Causes of the high karyotypic variability may include an elevated chromosomal mutation rate as well as certain features of the ecology and mating system that could facilitate the fixation of chromosomal rearrangements. The pattern of karyotype and haplotype differentiation and the results of previous crossing experiments suggest incipient speciation in C. riggenbachi.
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Affiliation(s)
- M Völker
- Institut für Evolutionsbiologie und Okologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany.
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Gallardo MH, González CA, Cebrián I. Molecular cytogenetics and allotetraploidy in the red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae). Genomics 2006; 88:214-21. [PMID: 16580173 DOI: 10.1016/j.ygeno.2006.02.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 02/08/2006] [Accepted: 02/14/2006] [Indexed: 11/24/2022]
Abstract
The theoretical impossibility of polyploidy in mammals was overturned by the discovery of tetraploidy in the red vizcacha rat, Tympanoctomys barrerae (2n = 102). As a consequence of genome duplication, remarkably increased cell dimensions are observed in the spermatozoa and in different somatic cell lines of this species. Locus duplication had been previously demonstrated by in situ PCR and Southern blot analysis of single-copy genes. Here, we corroborate duplication of loci in multiple-copy (major rDNAs) and single-copy (Hoxc8) genes by fluorescence in situ hybridization. We also demonstrate that nucleolar dominance, a large-scale epigenetic silencing phenomenon characteristic of allopolyploids, explains the presence of only one Ag-NOR chromosome pair in T. barrerae. Nucleolar dominance, together with the chromosomal heteromorphism detected in the G-banding pattern and synaptonemal complexes of the species' diploid-like meiosis, consistently indicates allotetraploidy. Allotetraploidization can coherently explain the peculiarities of gene silencing, cell dimensions, and karyotypic features of T. barrerae that remain unexplained by assuming diploidy and a large genome size attained by the dispersion of repetitive sequences.
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Affiliation(s)
- M H Gallardo
- Instituto de Ecología y Evolución, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
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Hafner MS, Spradling TA, Light JE, Hafner DJ, Demboski JR. SYSTEMATIC REVISION OF POCKET GOPHERS OF THE CRATOGEOMYS GYMNURUS SPECIES GROUP. J Mammal 2004. [DOI: 10.1644/ber-122.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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19
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Slamovits CH, Cook JA, Lessa EP, Rossi MS. Recurrent amplifications and deletions of satellite DNA accompanied chromosomal diversification in South American tuco-tucos (genus Ctenomys, Rodentia: Octodontidae): a phylogenetic approach. Mol Biol Evol 2001; 18:1708-19. [PMID: 11504851 DOI: 10.1093/oxfordjournals.molbev.a003959] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We investigated the relationship between satellite copy number and chromosomal evolution in tuco-tucos (genus Ctenomys), a karyotypically diverse clade of rodents. To explore phylogenetic relationships among 23 species and 5 undescribed forms, we sequenced the complete mitochondrial cytochrome b genes of 27 specimens and incorporated 27 previously published sequences. We then used quantitative dot-blot techniques to assess changes in the copy number of the major Ctenomys satellite DNA (satDNA), named RPCS. Our analysis of the relationship between variation in copy number of RPCS and chromosomal changes employed a maximum-likelihood approach to infer the copy number of the satellite RPCS in the ancestors of each clade. We found that amplifications and deletions of RPCS were associated with extensive chromosomal rearrangements even among closely related species. In contrast, RPCS copy number stability was observed within clades characterized by chromosomal stability. This example reinforces the suspected role of amplification, deletion, and intragenomic movement of satDNA in promoting extensive chromosomal evolution.
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Affiliation(s)
- C H Slamovits
- Laboratorio de Fisiología y Biología Molecular, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias Biológicas, Pabellón II, Buenos Aires, Argentina
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Smolen MJ, Bickham JW. Chromosomal variation in pocket gophers (Geomys) detected by sequential G-, R-, and C-band analyses. Chromosome Res 1994; 2:343-53. [PMID: 7981938 DOI: 10.1007/bf01552793] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The chromosomes of six taxa, representing five species of Geomys (G. attwateri, G. breviceps, G. personatus, G. texensis, G. bursarius) were analysed for variation in G-band, R-band, sequential R-/DAPI-AMD, and sequential R-/C-band patterns. Eleven chromosomes had structural rearrangements resulting from deletion/addition events. Fission/fusion rearrangements occurred in two chromosomes, and a pericentric inversion was confirmed in only one chromosome. Eighteen of 34 autosomes had constitutive heterochromatin, with variation in its presence or absence, position, and quantity. The heterochromatic differences were seen both among species and between two subspecies of G. personatus. Chromomycin A3 fluorescent staining identified G-C rich regions in 31 of the autosomes with 29 showing variation in their presence or absence, position, and quantity, and identified a high degree of cryptic variation. The X chromosome was highly variable, with differences attributable to structural rearrangements and variation in chromomycin bright-staining regions.
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Affiliation(s)
- M J Smolen
- Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station 77843
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Leitinger B, Poletaeva II, Wolfer DP, Lipp HP. Swimming navigation, open-field activity, and extrapolation behavior of two inbred mouse strains with Robertsonian translocation of chromosomes 8 and 17. Behav Genet 1994; 24:273-84. [PMID: 7945157 DOI: 10.1007/bf01067194] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Female mice from inbred strains carrying a Robertsonian translocation (nine CBARb and eight C57BL/6Rb) were compared with animals from their respective strains (seven CBA and nine C57BL/6) first in open-field activity (two exposures of 10-min duration), then during 5 days (with six trials each) in Morris' swimming navigation test, and finally, in their ability to extrapolate the future position of a food reward being moved slowly out of their reach. ANOVA (strain and translocation) revealed significant effects of Robertsonian translocations (Rb) in swimming navigation, Rb mice being impaired primarily in the initial phases of acquisition and during the first trials of platform reversal and the impairment being stronger in C57BL/6 mice. In the open field, Rb mice were as active as the normal strains but showed significantly increased path tortuosity and moved slightly faster. In the extrapolation task, Rb mice showed above-chance levels in moving to the target indicated by the disappearance of the stimulus, while normal mice chose at chance levels, but the translocation effects were not statistically significant. These data indicate that telocentric fusion of chromosomes may entail behavioral alterations, perhaps by subtle changes in neurotransmitters or limbic circuitry. The expression of such alterations, however, can be remarkably strain dependent.
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Affiliation(s)
- B Leitinger
- Institute of Anatomy, University of Zürich, Switzerland
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Walker LI, Spotorno AE, Sans J. Genome size variation and its phenotypic consequences in Phyllotis rodents. Hereditas 1991; 115:99-107. [PMID: 1810909 DOI: 10.1111/j.1601-5223.1991.tb03542.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Constitutive heterochromatin and genome size were studied in Phyllotis darwini, three Phyllotis xanthopygus subspecies, and their interspecific laboratory hybrids. P. darwini, with no or only small C-bands, had the smallest genome size; P. xanthopygus rupestris and P. x. vaccarum, with large C-bands in all the chromosomes, had the largest; and P. x. xanthopygus, with heterochromatin only in a few chromosomes, showed intermediate genome size. To examine some phenotypic consequences of nuclear DNA content, we measured nuclear and cellular surfaces and volumes. Linear regression analyses showed that all these cellular characters had a highly significant direct relationship with genome size. Hybrids had always the expected intermediate parental characteristics. Previous results indicate that P. x. vaccarum should have longer mitotic cycles and lower reproductive capacity than P. darwini. Our findings suggest that the "nucleotypic DNA" hypothesis, which considers genome size as an adaptive feature in higher plants and lower vertebrates, could be extended to these mammals. The analysis of heterochromatin and nuclear DNA amounts of other phyllotine and akodontine rodents supports the idea that small C-bands and genomes are ancestral conditions, from which independent and parallel events occurred until large genomes were produced.
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Affiliation(s)
- L I Walker
- Departamento de Biología Celular y Genética, Facultad de Medicina, Universidad de Chile, Santiago
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23
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Heterochromatin accumulation, disposition and diversity in Gibasis karwinskyana (Commelinaceae). Chromosoma 1991. [DOI: 10.1007/bf00364557] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Chromosomal polymorphism and small karyotypic differentiation in a group of Ctenomys species from Central Argentina (Rodentia: Octodontidae). Genetica 1991. [DOI: 10.1007/bf00058530] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Apfelbaum LI, Massarini AI, Daleffe LE, Reig OA. Genetic variability in the subterranean rodents Ctenomys australis and Ctenomys porteousi (Rodentia:Octodontidae). BIOCHEM SYST ECOL 1991. [DOI: 10.1016/0305-1978(91)90067-a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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26
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Civitelli MV, Consentino P, Capanna E. Inter- and intra-individual chromosome variability in Thamnomys (Grammomys) gazellae (Rodentia, Muridae) B-chromosomes and structural heteromorphisms. Genetica 1989; 79:93-105. [PMID: 2599383 DOI: 10.1007/bf00057926] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The present paper reports intra- and inter-individual variability related to the occurrence of numerous B-chromosomes in Thamnomys (Grammomys) gazellae, a species of African Climber rat belonging to the 'dolichurus' group. The frequency of B-chromosomes in somatic and spermatogonial metaphases is investigated, together with their behaviour during meiosis. Moreover, G-banding makes it possible to identify a structural polymorphism resulting from a pericentric inversion in a large chromosome (no. 6). The distribution of the constitutive heterochromatin has been assessed by C-banding. The nucleolus organizer regions (NOR's) were located by means of silver staining in four chromosomal pairs (nos. 1, 2, 4, and 6). The karyotype of T. (G.) gazellae is compared with that of other taxa of the dolichurus group, particularly the Somaliland population which also exhibits the occurrence of B-chromosomes. The origin and significance of B-chromosomes is discussed.
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Affiliation(s)
- M V Civitelli
- Department of Animal and Human Biology, University of Rome La Sapienza, Italy
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Rubini M, Fontana F. Standard G-banded karyotype, constitutive heterochromatin and nucleolus organizer regions in the roe deer (Capreolus capreolus L.). Genetica 1988. [DOI: 10.1007/bf00057765] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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28
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Abstract
Many theoretical papers investigating the relationship between chromosomal change and speciation are found to have been based on erroneous data. For rather than considering those negatively heterotic, or at least potentially negatively heterotic rearrangements which can have a possible role in speciation, these papers have included substantial amounts of information on rearrangements which are not implicated in this process. Common forms of chromosomal repatterning such as heterochromatic addition and polymorphism are in this category. Their inclusion in theoretical studies, often cited as supporting or opposing a chromosomal involvement in speciation, invalidates these findings. A new approach is suggested.
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29
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Burgos M, Jim�nez R, Diaz de la Guardia R. Comparative study of G- and C-banded chromosomes of five species of Microtidae. Genetica 1986. [DOI: 10.1007/bf00058668] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Sharma T, Cheong N, Sen P, Sen S. Constitutive heterochromatin and evolutionary divergence of Mus dunni, M. booduga and M. musculus. Curr Top Microbiol Immunol 1986; 127:35-44. [PMID: 3731852 DOI: 10.1007/978-3-642-71304-0_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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31
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G-band homology and C-band variation in the Japanese mustelids,Mustela erminea nippon andM. sibirica itatsi. Genetica 1985. [DOI: 10.1007/bf02424566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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32
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Barros MA, Patton JL. Genome evolution in pocket gophers (genus Thomomys). III. Fluorochrome-revealed heterochromatin heterogeneity. Chromosoma 1985; 92:337-43. [PMID: 4053789 DOI: 10.1007/bf00327464] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Heterochromatin is a dominant component of the genome in the bottae group of the pocket gopher genus Thomomys, having had a major role in the karyotypic evolution of member species. Heterochromatin characteristics of two subspecies of T. bottae and one of T. umbrinus were examined with fluorochrome dyes identifying presumptive GC- and AT-rich regions. In two karyotype forms of T. b. fulvus and in T. umbrinus, chromatin that fluoresces brightly with chromomycin A3 is also C-band positive, although not all heterochromatin fluoresces. However, in T. b. bottae, only euchromatic regions fluoresce brightly with chromomycin. Fluorescence patterns produced with DAPI are the reverse of the chromomycin banding in all karyotypic forms. Heterochromatin in these taxa is thus highly differentiated, exhibiting heterogeneity in staining characteristics, and presumably in underlying DNA sequences, both across the genome within a given chromosomal complement as well as among the different karyotypic races and species of the bottae group of pocket gophers.
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33
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34
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35
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Sherwood SW, Patton JL. Genome evolution in pocket gophers (genus Thomomys). II. Variation in cellular DNA content. Chromosoma 1982; 85:163-79. [PMID: 7117027 DOI: 10.1007/bf00294963] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Cellular DNA content (2 C-value) was measured by fluorescence flow cytometry of chromomycin-A3 stained spleen cells in 2 subgenera, 5 species, and 21 subspecies of pocket gophers (genus Thomomys). The data indicate that, in Thomomys: (1) interspecific variation is extensive but, while some congeneric species differ by as much as 230%, others are identical in C-value: (2) intraspecific differentiation can be extensive with C-values differing by as much as 35%; and (3) populations of the same subspecies with apparently similar karyotypes can differ significantly in C-value. The implications of these results for hypotheses of the "adaptive" significance of C-value variation and genome evolution are discussed.
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