scholarly journals Fast chromosomal evolution and karyotype instability: recurrent chromosomal rearrangements in the peach potato aphidMyzus persicae(Hemiptera: Aphididae)

2015 ◽  
Vol 116 (3) ◽  
pp. 519-529 ◽  
Author(s):  
Gian Carlo Manicardi ◽  
Andrea Nardelli ◽  
Mauro Mandrioli
Keyword(s):  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
Karyotype Instability

scholarly journals Chromosomal Evolution in the Lizard Genus Varanus (Reptilia)

1975 ◽  
Vol 28 (1) ◽  
pp. 89 ◽  
Author(s):  
Max Kinga ◽  
Dennis King
Keyword(s):  
Chromosome Number ◽  
Pericentric Inversion ◽  
Sex Chromosome ◽  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
Size Groups ◽  
Sex Chromosome System

The karyotypes have been determined of 16 of the 32 species of the genus Varanus, including animals from Africa, Israel, Malaya and Australia. A constant chromosome number of 2n = 40 was observed. The karyotype is divided into eight pairs of large chromosomes and 12 pairs of microchromosomes. A series of chromosomal rearrangements have become established in both size groups of the karyotype and are restricted to centromere shifts, probably caused by pericentric inversion. Species could be placed in one of six distinct karyotype groups which are differentiated by these rearrangements and whose grouping does not always correspond with the current taxonomy. An unusual sex chromosome system of the ZZjZW type was present in a number of the species examined.

Extraordinary and extensive karyotypic variation: A 48-fold range in chromosome number in the gall-inducing scale insect Apiomorpha (Hemiptera: Coccoidea: Eriococcidae)

Genome ◽  
2000 ◽  
Vol 43 (2) ◽  
pp. 255-263 ◽  
Author(s):  
Lyn G Cook
Keyword(s):  
Chromosome Number ◽  
Chromosomal Rearrangements ◽  
Chromosomal Polymorphism ◽  
Chromosomal Evolution ◽  
Scale Insect ◽  
Closely Related Species ◽  
Host Genus ◽  
Species Complexes ◽  
Species Groups ◽  
Karyotypic Variation

Chromosome number reflects strong constraints on karyotype evolution, unescaped by the majority of animal taxa. Although there is commonly chromosomal polymorphism among closely related taxa, very large differences in chromosome number are rare. This study reports one of the most extensive chromosomal ranges yet reported for an animal genus. Apiomorpha Rübsaamen (Hemiptera: Coccoidea: Eriococcidae), an endemic Australian gall-inducing scale insect genus, exhibits an extraordinary 48-fold variation in chromosome number with diploid numbers ranging from 4 to about 192. Diploid complements of all other eriococcids examined to date range only from 6 to 28. Closely related species of Apiomorpha usually have very different karyotypes, to the extent that the variation within some species- groups is as great as that across the entire genus. There is extensive chromosomal variation among populations within 17 of the morphologically defined species of Apiomorpha indicating the existence of cryptic species-complexes. The extent and pattern of karyotypic variation suggests rapid chromosomal evolution via fissions and (or) fusions. It is hypothesized that chromosomal rearrangements in Apiomorpha species may be associated with these insects' tracking the radiation of their speciose host genus, Eucalyptus. Key words: Apiomorpha, cytogenetics, chromosomal evolution, holocentric.

scholarly journals Genome-Wide Amplifications Caused by Chromosomal Rearrangements Play a Major Role in the Adaptive Evolution of Natural Yeast

Genetics ◽  
2003 ◽  
Vol 165 (4) ◽  
pp. 1745-1759 ◽  
Author(s):  
Juan J Infante ◽  
Kenneth M Dombek ◽  
Laureana Rebordinos ◽  
Jesús M Cantoral ◽  
Elton T Young
Keyword(s):  
Adaptive Evolution ◽  
Chromosomal Rearrangements ◽  
Sexual Isolation ◽  
Chromosomal Evolution ◽  
Double Strand Breaks ◽  
Chromosomal Dna ◽  
Strand Breaks ◽  
Yeast Strains ◽  
Gross Chromosomal Rearrangements ◽  
Flor Yeast

Abstract The relative importance of gross chromosomal rearrangements to adaptive evolution has not been precisely defined. The Saccharomyces cerevisiae flor yeast strains offer significant advantages for the study of molecular evolution since they have recently evolved to a high degree of specialization in a very restrictive environment. Using DNA microarray technology, we have compared the genomes of two prominent variants of S. cerevisiae flor yeast strains. The strains differ from one another in the DNA copy number of 116 genomic regions that comprise 38% of the genome. In most cases, these regions are amplicons flanked by repeated sequences or other recombination hotspots previously described as regions where double-strand breaks occur. The presence of genes that confer specific characteristics to the flor yeast within the amplicons supports the role of chromosomal rearrangements as a major mechanism of adaptive evolution in S. cerevisiae. We propose that nonallelic interactions are enhanced by ethanol- and acetaldehyde-induced double-strand breaks in the chromosomal DNA, which are repaired by pathways that yield gross chromosomal rearrangements. This mechanism of chromosomal evolution could also account for the sexual isolation shown among the flor yeast.

scholarly journals Chromosomal distribution of the retroelements Rex 1, Rex 3 and Rex 6 in species of the genus Harttia and Hypostomus (Siluriformes: Loricariidae)

2019 ◽  
Vol 17 (2) ◽  
Author(s):  
Josiane B. Traldi ◽  
Roberto L. Lui ◽  
Juliana de F. Martinez ◽  
Marcelo R. Vicari ◽  
Viviane Nogaroto ◽  
...  
Keyword(s):  
Transposable Elements ◽  
Physical Mapping ◽  
Genome Organization ◽  
Chromosomal Rearrangements ◽  
Chromosome Mapping ◽  
Chromosomal Evolution ◽  
Chromosomal Distribution ◽  
Chromosome Markers ◽  
Molecular Domestication

ABSTRACT The transposable elements (TE) have been widely applied as physical chromosome markers. However, in Loricariidae there are few physical mapping analyses of these elements. Considering the importance of transposable elements for chromosomal evolution and genome organization, this study conducted the physical chromosome mapping of retroelements (RTEs) Rex1, Rex3 and Rex6 in seven species of the genus Harttia and four species of the genus Hypostomus, aiming to better understand the organization and dynamics of genomes of Loricariidae species. The results showed an intense accumulation of RTEs Rex1, Rex3 and Rex6 and dispersed distribution in heterochromatic and euchromatic regions in the genomes of the species studied here. The presence of retroelements in some chromosomal regions suggests their participation in various chromosomal rearrangements. In addition, the intense accumulation of three retroelements in all species of Harttia and Hypostomus, especially in euchromatic regions, can indicate the participation of these elements in the diversification and evolution of these species through the molecular domestication by genomes of hosts, with these sequences being a co-option for new functions.

scholarly journals Distribution of GC-rich heterochromatin and ribosomal genes in three fungus-farming ants (Myrmicinae, Attini, Attina): insights on chromosomal evolution

2021 ◽  
Vol 15 (4) ◽  
pp. 413-428
Author(s):  
Gisele Amaro Teixeira ◽  
Luísa Antônia Campos Barros ◽  
Hilton Jeferson Alves Cardoso de Aguiar ◽  
Denilce Meneses Lopes
Keyword(s):  
Chromosomal Rearrangements ◽  
Taxonomic Revision ◽  
Chromosomal Evolution ◽  
Ribosomal Genes ◽  
Common Origin ◽  
Rdna Site ◽  
Rdna Genes ◽  
Molecular Cytogenetic ◽  
Cytogenetic Data ◽  
Molecular Cytogenetic Techniques

Cytogenetic studies on fungus-farming ants have shown remarkable karyotype diversity, suggesting different chromosomal rearrangements involved in karyotype evolution in some genera. A notable cytogenetic characteristic in this ant group is the presence of GC-rich heterochromatin in the karyotypes of some ancient and derivative species. It was hypothesized that this GC-rich heterochromatin may have a common origin in fungus-farming ants, and the increase in species studied is important for understanding this question. In addition, many genera within the subtribe Attina have few or no cytogenetically studied species; therefore, the processes that shaped their chromosomal evolution remain obscure. Thus, in this study, we karyotyped, through classical and molecular cytogenetic techniques, the fungus-farming ants Cyphomyrmex transversus Emery, 1894, Sericomyrmex maravalhas Ješovnik et Schultz, 2017, and Mycetomoellerius relictus (Borgmeier, 1934), to provide insights into the chromosomal evolution in these genera and to investigate the presence the GC-rich heterochromatin in these species. Cyphomyrmex transversus (2n = 18, 10m + 2sm + 6a) and S. maravalhas (2n = 48, 28m + 20sm) showed karyotypes distinct from other species from their genera. Mycetomoellerius relictus (2n = 20, 20m) presented the same karyotype as the colonies previously studied. Notably, C. transversus presented the lowest chromosomal number for the genus and a distinct karyotype from the other two previously observed for this species, showing the existence of a possible species complex and the need for its taxonomic revision. Chromosomal banding data revealed GC-rich heterochromatin in all three species, which increased the number of genera with this characteristic, supporting the hypothesis of a common origin of GC-rich heterochromatin in Attina. Although a single chromosomal pair carries rDNA genes in all studied species, the positions of these rDNA clusters varied. The rDNA genes were located in the intrachromosomal region in C. transversus and M. relictus, and in the terminal region of S. maravalhas. The combination of our molecular cytogenetic data and observations from previous studies corroborates that a single rDNA site located in the intrachromosomal region is a plesiomorphic condition in Attina. In addition, cytogenetic data obtained suggest centric fission events in Sericomyrmex Mayr, 1865, and the occurrence of inversions as the origin of the location of the ribosomal genes in M. relictus and S. maravalhas. This study provides new insights into the chromosomal evolution of fungus-farming ants.

scholarly journals Comparative cytogenetic analyses in Ancistrus species (Siluriformes: Loricariidae)

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Larissa Glugoski ◽  
Geize Deon ◽  
Stephane Schott ◽  
Marcelo R. Vicari ◽  
Viviane Nogaroto ◽  
...  
Keyword(s):  
Chromosomal Rearrangements ◽  
5S Rdna ◽  
Chromosomal Evolution ◽  
Sister Group ◽  
Fusion Event ◽  
Rdna Cluster ◽  
Strand Breaks ◽  
Rdna Sites ◽  
Cytogenetic Analyses ◽  
Ribosomal Dnas

ABSTRACT Ancistrus is a specious genus of armored catfishes that has been extensively used for cytogenetic studies in the last 17 years. A comparison of the extensive karyotypic plasticity within this genus is presented with new cytogenetic analysis for Ancistrus cf. multispinis and Ancistrus aguaboensis. This study aims to improve our understanding of chromosomal evolution associated with changes in the diploid number (2n) and the dispersion of ribosomal DNAs (rDNAs) within Ancistrus. Ancistrus cf. multispinis and A. aguaboensis exhibit 2n of 52 and 50 chromosomes, respectively. Given that A. cf. multispinis shares a 2n = 52 also found in Pterygoplichthyini, the sister group for Ancistrini, a Robertsonian (Rb) fusion event is proposed for the 2n reduction in A. aguaboensis. 5S rDNAs pseudogenes sites have already been associated with Rb fusion in Ancistrus and our analysis suggests that the 2n reduction in A. aguaboensis was triggered by double strand breaks (DSBs) and chromosomal rearrangements at 5S rDNA sites. The presence of evolutionary breakpoint regions (EBRs) into rDNA cluster is proposed to explain part of the Rb fusion in Ancistrus. Cytogenetic data presented extends the diversity already documented in Ancistrus to further understand the role of chromosomal rearrangements in the diversification of Ancistrini.

RFLP Maps Based on a Common Set of Clones Reveal Modes of Chromosomal Evolution in Potato and Tomato.

Genetics ◽  
1988 ◽  
Vol 120 (4) ◽  
pp. 1095-1103
Author(s):  
M W Bonierbale ◽  
R L Plaisted ◽  
S D Tanksley
Keyword(s):  
Solanum Tuberosum L ◽  
Chromosomal Rearrangements ◽  
Interspecific Cross ◽  
Chromosomal Evolution ◽  
Basic Chromosome Number ◽  
Cdna Clones ◽  
Negative Effect ◽  
Intrachromosomal Rearrangements ◽  
Potato Genetics ◽  
Paracentric Inversions

Abstract Potato (Solanum tuberosum L.) and tomato (Lycopersicon esculentum) are members of the Solanaceae (nightshade family) and have the same basic chromosome number (x = 12). However, they cannot be cross-hybridized and, until now, it was unknown how conserved the gene order might be between these two species. We report herein the construction of a genetic linkage map of potato chromosomes based on genomic and cDNA clones from tomato. The potato map was drawn from segregation data derived from the interspecific cross S. phureja X (S. tuberosum X S. chacoense) (2n = 2x = 24), and consists of 135 markers defining 12 distinct linkage groups. Nearly all of the tomato probes tested hybridized to potato DNA, and in most cases, the copy number of the employed clones was the same in both species. Furthermore, all clones mapped to the same linkage group in both species. For nine chromosomes, the order of loci appears to be identical in the two species, while for the other three, intrachromosomal rearrangements are apparent, all of which appear to be paracentric inversions with one breakpoint at or near the centromere. These results are consistent with cytogenetic theory, previously untested in plants, which predicts that paracentric inversions will have the least negative effect on fitness and thus be the most likely form of chromosomal rearrangements to survive through evolutionary time. Linkage maps based on a common set of restriction fragment length polymorphism markers provide a basis for uniting the previously separate disciplines of tomato and potato genetics. Using these maps, it may now be possible to test theories about homologies or orthologies of other genes, including those coding for disease resistance and stress tolerances.

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

2017 ◽  
Vol 152 (2) ◽  
pp. 55-64 ◽  
Author(s):  
Victor Colomina ◽  
Josette Catalan ◽  
Janice Britton-Davidian ◽  
Frédéric Veyrunes
Keyword(s):  
Mammalian Species ◽  
Chromosomal Rearrangements ◽  
Replication Timing ◽  
Pericentromeric Region ◽  
Chromosomal Evolution ◽  
Telomeric Repeats ◽  
Telomeric Sequences ◽  
Interstitial Telomeric Sequences ◽  
Karyotypic Diversity ◽  
The One

Telomeres are ribonucleoprotein structures protecting the physical ends of eukaryotic chromosomes. However, telomeric sequences can also occur at non-terminal regions of chromosomes, forming the so-called interstitial telomeric sequences (ITSs). Some ITSs are considered as relics of past chromosomal rearrangements and as such provide important insights into karyotype evolution. By FISH, we explored the distribution of telomeric motifs in the genome of a complex of mammalian species that has long been recognized for its extraordinary karyotypic diversity: the African pygmy mice. This survey involved 5 species, representing 10 highly diverse karyotypes with or without autosomal and sex-autosome robertsonian (Rb) fusions. The study revealed that in species with an ancestral-like karyotype (i.e., no fusions; Mus mattheyi and M. indutus), only terminal telomeres were observed, whereas in species experiencing intense chromosomal evolution (e.g., M. minutoides, M. musculoides), a large amplification of telomeric repeats was also identified in the pericentromeric region of acrocentrics and most metacentrics. We concluded that (i) the mechanism of Rb fusion in the African pygmy mice is different than the one highlighted in the house mouse; (ii) the intensity of the ITS hybridization signal could be a signature of the age of formation of the Rb fusion; (iii) the large amplification of pericentromeric telomeric sequences in acrocentrics may mediate the formation of Rb fusions, and (iv) the ITSs on the sex-autosome fusion Rb(X.1) may participate to the insulation buffer between the sexual and autosomal arms to prevent X inactivation from spreading and silencing autosomal genes and allow the independent regulation of replication timing of both segments.

scholarly journals Karyotype description and evidence of multiple sex chromosome system X1X1X2X2/X1X2Y in Potamotrygon aff. motoro and P. falkneri (Chondrichthyes: Potamotrygonidae) in the upper Paraná River basin, Brazil

2011 ◽  
Vol 9 (1) ◽  
pp. 201-208 ◽  
Author(s):  
Vanessa Paes da Cruz ◽  
Cristiane Kioko Shimabukuro-Dias ◽  
Claudio Oliveira ◽  
Fausto Foresti
Keyword(s):  
Sex Chromosome ◽  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
Nucleolus Organizer ◽  
Banding Technique ◽  
Nucleolus Organizer Regions ◽  
Sex Chromosome System ◽  
Upper Paraná River ◽  
Upper Paraná River Basin ◽  
Almost All

Cytogenetic analysis of Potamotrygon aff. motoro and P. falkneri indicated the occurrence of an X1X1X2X2/X1X2 Y multiple sex chromosome system in both species, with 2n = 66 chromosomes for females and 2n = 65 chromosomes for males. The nucleolus organizer regions (NORs) identified using Ag-NOR technique showed that both species have multiple Ag-NORs (5 to 7 chromosomes stained). C-banding technique indicated the presence of heterochromatic blocks in the centromeric regions of almost all chromosomes in both species. Through this study there was evidence of heterogeneity in the karyotypes, which suggests that chromosomal rearrangements such as inversions and/or translocations occurred during the chromosomal evolution in two species of this genus.

scholarly journals Repetitive Elements Contribute to the Diversity and Evolution of Centromeres in the Fungal Genus Verticillium

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Michael F. Seidl ◽  
H. Martin Kramer ◽  
David E. Cook ◽  
Gabriel L. Fiorin ◽  
Grardy C. M. van den Berg ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Chromosomal Rearrangements ◽  
Rapid Evolution ◽  
Chromosomal Evolution ◽  
Repetitive Elements ◽  
Chromosomal Anomalies ◽  
Content Type ◽  
Genome Wide ◽  
Mitosis And Meiosis ◽  
Fungal Genus

ABSTRACT Centromeres are chromosomal regions that are crucial for chromosome segregation during mitosis and meiosis, and failed centromere formation can contribute to chromosomal anomalies. Despite this conserved function, centromeres differ significantly between and even within species. Thus far, systematic studies into the organization and evolution of fungal centromeres remain scarce. In this study, we identified the centromeres in each of the 10 species of the fungal genus Verticillium and characterized their organization and evolution. Chromatin immunoprecipitation of the centromere-specific histone CenH3 (ChIP-seq) and chromatin conformation capture (Hi-C) followed by high-throughput sequencing identified eight conserved, large (∼150-kb), AT-, and repeat-rich regional centromeres that are embedded in heterochromatin in the plant pathogen Verticillium dahliae. Using Hi-C, we similarly identified repeat-rich centromeres in the other Verticillium species. Strikingly, a single degenerated long terminal repeat (LTR) retrotransposon is strongly associated with centromeric regions in some but not all Verticillium species. Extensive chromosomal rearrangements occurred during Verticillium evolution, of which some could be linked to centromeres, suggesting that centromeres contributed to chromosomal evolution. The size and organization of centromeres differ considerably between species, and centromere size was found to correlate with the genome-wide repeat content. Overall, our study highlights the contribution of repetitive elements to the diversity and rapid evolution of centromeres within the fungal genus Verticillium. IMPORTANCE The genus Verticillium contains 10 species of plant-associated fungi, some of which are notorious pathogens. Verticillium species evolved by frequent chromosomal rearrangements that contribute to genome plasticity. Centromeres are instrumental for separation of chromosomes during mitosis and meiosis, and failed centromere functionality can lead to chromosomal anomalies. Here, we used a combination of experimental techniques to identify and characterize centromeres in each of the Verticillium species. Intriguingly, we could strongly associate a single repetitive element to the centromeres of some of the Verticillium species. The presence of this element in the centromeres coincides with increased centromere sizes and genome-wide repeat expansions. Collectively, our findings signify a role of repetitive elements in the function, organization, and rapid evolution of centromeres in a set of closely related fungal species.

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