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

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.

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Comparative Cytogenetic Analysis of Three Eumeninae Species (Hymenoptera, Vespidae)

Cytogenetic and Genome Research ◽

10.1159/000515082 ◽

2021 ◽

pp. 1-10

Author(s):

Mara G. Tavares ◽

Gisele A. Teixeira

Keyword(s):

Chromosome Number ◽

Chromosomal Evolution ◽

Ribosomal Genes ◽

Molecular Techniques ◽

Rdna Site ◽

Structural Rearrangements ◽

Fluorochrome Staining ◽

Haploid Chromosome Number ◽

Molecular Cytogenetic ◽

Chromosomal Polymorphisms

Eumeninae represents the largest subfamily within Vespidae, with 3,600 species described. Of these, only 18 have been cytogenetically analysed. In the present study, we used both classical and molecular techniques to characterise and compare the karyotypes of 3 Eumeninae species, namely, Ancistrocerus sp., Pachodynerus grandis, and Pachodynerus nasidens. Ancistrocerus sp. presented a haploid chromosome number of n = 12, with the first 2 chromosomes of the karyotype being almost entirely heterochromatic and much larger than the remaining chromosomes. The 2 Pachodynerus species presented the same chromosome number (n = 11 and 2n = 22) but displayed different karyotypic formulae. Additionally, chromosomal polymorphisms were observed in the analysed P. nasidens female. In the 3 species, heterochromatin was located in one of the chromosome arms. Fluorochrome staining revealed a balanced composition of AT and GC bases within the chromatin for each of the 3 species, except for few regions that were visibly GC-rich. All species had a single 18S rDNA site that co-localised with GC-rich regions; however, this localisation varied from species to species and not all GC-rich regions corresponded to ribosomal genes. Based on the cytogenetic data obtained here, we discuss the possible numerical/structural rearrangements that may be involved in the karyotypic evolution of the 3 studied species. In addition to the first description of the molecular cytogenetic characteristics of the Eumeninae subfamily and the genus Pachodynerus, this study also provides a relevant contribution towards the discussion of chromosomal evolution in Eumeninae wasps.

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Comparative cytogenetics of Serrasalmidae (Teleostei: Characiformes): The relationship between chromosomal evolution and molecular phylogenies

PLoS ONE ◽

10.1371/journal.pone.0258003 ◽

2021 ◽

Vol 16 (10) ◽

pp. e0258003

Author(s):

Ramon Marin Favarato ◽

Leila Braga Ribeiro ◽

Alber Campos ◽

Jorge Ivan Rebelo Porto ◽

Celeste Mutuko Nakayama ◽

...

Keyword(s):

Chromosome Number ◽

Chromosomal Rearrangements ◽

5S Rdna ◽

Chromosomal Evolution ◽

Comparative Cytogenetics ◽

Molecular Cytogenetic ◽

The Family ◽

Identification Of Species ◽

Molecular Cytogenetic Techniques ◽

The Relationship

Serrasalmidae has high morphological and chromosomal diversity. Based on molecular hypotheses, the family is currently divided into two subfamilies, Colossomatinae and Serrasalminae, with Serrasalminae composed of two tribes: Myleini (comprising most of pacus species) and Serrasalmini (represented by Metynnis, Catoprion, and remaining piranha’s genera). This study aimed to analyze species of the tribes Myleini (Myloplus asterias, M. lobatus, M. rubripinnis, M. schomburgki, and Tometes camunani) and Serrasalmini (Metynnis cuiaba, M. hypsauchen, and M. longipinnis) using classical and molecular cytogenetic techniques in order to understand the chromosomal evolution of the family. The four species of the genus Myloplus and T. camunani presented 2n = 58 chromosomes, while the species of Metynnis presented 2n = 62 chromosomes. The distribution of heterochromatin occurred predominantly in pericentromeric regions in all species. Tometes camunani and Myloplus spp. presented only one site with 5S rDNA. Multiple markers of 18S rDNA were observed in T. camunani, M. asterias, M. lobatus, M. rubripinnis, and M. schomburgkii. For Metynnis, however, synteny of the 18S and 5S rDNA was observed in the three species, in addition to an additional 5S marker in M. longipinnis. These data, when superimposed on the phylogeny of the family, suggest a tendency to increase the diploid chromosome number from 54 to 62 chromosomes, which occurred in a nonlinear manner and is the result of several chromosomal rearrangements. In addition, the different karyotype formulas and locations of ribosomal sequences can be used as cytotaxonomic markers and assist in the identification of species.

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Molecular Cytogenetic Analysis of Cucumis Wild Species Distributed in Southern Africa: Physical Mapping of 5S and 45S rDNA with DAPI

Cytogenetic and Genome Research ◽

10.1159/000433572 ◽

2015 ◽

Vol 146 (1) ◽

pp. 80-87 ◽

Cited By ~ 6

Author(s):

Kouhei Yagi ◽

Magdalena Pawełkowicz ◽

Paweł Osipowski ◽

Ewa Siedlecka ◽

Zbigniew Przybecki ◽

...

Keyword(s):

Cytogenetic Analysis ◽

Chromosomal Rearrangements ◽

Evolutionary Relationship ◽

Chromosomal Evolution ◽

Rdna Site ◽

45S Rdna ◽

Polyploid Evolution ◽

Molecular Cytogenetic ◽

Rdna Sites ◽

Cucumis Species

Wild Cucumis species have been divided into Australian/Asian and African groups using morphological and phylogenetic characteristics, and new species have been described recently. No molecular cytogenetic information is available for most of these species. The crossability between 5 southern African Cucumis species (C. africanus, C. anguria, C. myriocarpus, C. zeyheri, and C. heptadactylus) has been reported; however, the evolutionary relationship among them is still unclear. Here, a molecular cytogenetic analysis using FISH with 5S and 45S ribosomal DNA (rDNA) was used to investigate these Cucumis species based on sets of rDNA-bearing chromosomes (rch) types I, II and III. The molecular cytogenetic and phylogenetic results suggested that at least 2 steps of chromosomal rearrangements may have occurred during the evolution of tetraploid C. heptadactylus. In step 1, an additional 45S rDNA site was observed in the chromosome (type III). In particular, C. myriocarpus had a variety of rch sets. Our results suggest that chromosomal rearrangements may have occurred in the 45S rDNA sites. We propose that polyploid evolution occurred in step 2. This study provides insights into the chromosomal characteristics of African Cucumis species and contributes to the understanding of chromosomal evolution in this genus.

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Application of molecular cytogenetic techniques to clarify apparently balanced complex chromosomal rearrangements in two patients with an abnormal phenotype: case report

Molecular Cytogenetics ◽

10.1186/1755-8166-2-15 ◽

2009 ◽

Vol 2 (1) ◽

pp. 15 ◽

Cited By ~ 12

Author(s):

Paula JP de Vree ◽

Marleen EH Simon ◽

Marieke F van Dooren ◽

Gerda HT Stoevelaar ◽

José TW Hilkmann ◽

...

Keyword(s):

Case Report ◽

Chromosomal Rearrangements ◽

Molecular Cytogenetic ◽

Abnormal Phenotype ◽

Complex Chromosomal Rearrangements ◽

Molecular Cytogenetic Techniques

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Microstructural chromosome reorganization in the genus Trichomycterus (Siluriformes: Trichomycteridae)

Neotropical Ichthyology ◽

10.1590/1982-0224-20150084 ◽

2016 ◽

Vol 14 (2) ◽

Cited By ~ 5

Author(s):

Maria Lígia M. de Oliveira ◽

Ricardo Utsunomia ◽

José Carlos Pansonato-Alves ◽

Priscilla C. Scacchetti ◽

Cleberson C. Primo ◽

...

Keyword(s):

Chromosome Number ◽

Constitutive Heterochromatin ◽

Genomic Structure ◽

5S Rdna ◽

Ribosomal Genes ◽

Molecular Cytogenetic ◽

Rdna Sites ◽

Karyotype Formula ◽

Molecular Cytogenetic Techniques ◽

Genomic Reorganization

Trichomycterus is a specious fish genus within Trichomycterinae and displays remarkable karyotype diversity. However, knowledge about their genomic structure and location of repetitive sequence is still limited. In order to better understand the karyotype diversification, we analyzed nine species of Trichomycterus using classical and molecular cytogenetic techniques. Results revealed a conserved diploid chromosome number of 2n=54 chromosomes in all analyzed species, although remarkable differences on the constitutive heterochromatin distribution were observed. In addition, while the 18S rDNA showed a conserved distribution pattern, the 5S rDNA sites showed a quite diverse location considering the analyzed species. Remarkably, both ribosomal genes were co-located in all species, except in T . iheringi , suggesting that co-localization is probably an ancestral condition in Trichomycterus . Finally, three analyzed species showed heterochromatic B chromosomes, reinforcing the intense genomic reorganization occurring in Trichomycterus . Our results showed that chromosomal variations are not restricted to differences in karyotype formula as previously proposed, but also to modifications on the microstructural level of resolution.

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Distribution of Telomeric Sequences (TTAGGG)n in Rearranged Chromosomes of Phyllotine Rodents (Cricetidae, Sigmodontinae)

Cytogenetic and Genome Research ◽

10.1159/000444602 ◽

2015 ◽

Vol 147 (4) ◽

pp. 247-252 ◽

Cited By ~ 5

Author(s):

Cecilia Lanzone ◽

Carolina Labaroni ◽

Natalia Suárez ◽

Daniela Rodríguez ◽

Macarena L. Herrera ◽

...

Keyword(s):

Sex Chromosomes ◽

Chromosomal Evolution ◽

Robertsonian Translocations ◽

Telomeric Sequences ◽

Molecular Cytogenetic ◽

Interstitial Telomeric Sequences ◽

Robertsonian Rearrangements ◽

Recent Origin ◽

Chromosome Fusions ◽

Molecular Cytogenetic Techniques

Phyllotines are sigmodontine rodents endemic to South America with broad genetic variability, Robertsonian polymorphisms being the most frequent. Moreover, this taxon includes a species with multiple sex chromosomes, which is infrequent in mammals. However, molecular cytogenetic techniques have never been applied to phyllotines to elucidate their karyotypic evolution. We studied the chromosomes of 4 phyllotine species using FISH with a pantelomeric probe (TTAGGG)n. Graomys griseoflavus, Eligmodontia puerulus, and E. morgani are polymorphic for Robertsonian translocations, whereas Salinomys delicatus possesses XX/ XY1Y2 sex chromosomes. Telomeric signals were detected at both ends of all chromosomes of the studied species. In S. delicatus interstitial telomeric sequences (ITS) were observed in the 3 major chromosome pairs, which are equidistant from one of the telomeres in these chromosomes. These results suggest that ITS are important in the reshuffling of the highly derived karyotype of S. delicatus. Considering the phylogeny of phyllotines, the Robertsonian rearrangements of G. griseoflavus, E. puerulus, and E. morgani possibly represent chromosome fusions which have occurred independently. The pericentromeric regions of the biarmed chromosomes of these species do not contain telomeric sequences characteristic for strict fusions of recent origin, suggesting a common pattern of telomeric repeat loss during chromosomal evolution of these rodents.

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Analysis of multiple chromosomal rearrangements in the genome of Willisornis vidua using BAC-FISH and chromosome painting on a supposed conserved karyotype

BMC Ecology and Evolution ◽

10.1186/s12862-021-01768-y ◽

2021 ◽

Vol 21 (1) ◽

Cited By ~ 1

Author(s):

Talita Fernanda Augusto Ribas ◽

Julio Cesar Pieczarka ◽

Darren K. Griffin ◽

Lucas G. Kiazim ◽

Cleusa Yoshiko Nagamachi ◽

...

Keyword(s):

Chromosome Painting ◽

Diploid Number ◽

Chromosomal Rearrangements ◽

Large Degree ◽

Artificial Chromosome ◽

Gallus Gallus ◽

Phylogeographic Structure ◽

Molecular Cytogenetic ◽

Burhinus Oedicnemus ◽

Intrachromosomal Rearrangements

Abstract Background Thamnophilidae birds are the result of a monophyletic radiation of insectivorous Passeriformes. They are a diverse group of 225 species and 45 genera and occur in lowlands and lower montane forests of Neotropics. Despite the large degree of diversity seen in this family, just four species of Thamnophilidae have been karyotyped with a diploid number ranging from 76 to 82 chromosomes. The karyotypic relationships within and between Thamnophilidae and another Passeriformes therefore remain poorly understood. Recent studies have identified the occurrence of intrachromosomal rearrangements in Passeriformes using in silico data and molecular cytogenetic tools. These results demonstrate that intrachromosomal rearrangements are more common in birds than previously thought and are likely to contribute to speciation events. With this in mind, we investigate the apparently conserved karyotype of Willisornis vidua, the Xingu Scale-backed Antbird, using a combination of molecular cytogenetic techniques including chromosome painting with probes derived from Gallus gallus (chicken) and Burhinus oedicnemus (stone curlew), combined with Bacterial Artificial Chromosome (BAC) probes derived from the same species. The goal was to investigate the occurrence of rearrangements in an apparently conserved karyotype in order to understand the evolutionary history and taxonomy of this species. In total, 78 BAC probes from the Gallus gallus and Taeniopygia guttata (the Zebra Finch) BAC libraries were tested, of which 40 were derived from Gallus gallus macrochromosomes 1–8, and 38 from microchromosomes 9–28. Results The karyotype is similar to typical Passeriformes karyotypes, with a diploid number of 2n = 80. Our chromosome painting results show that most of the Gallus gallus chromosomes are conserved, except GGA-1, 2 and 4, with some rearrangements identified among macro- and microchromosomes. BAC mapping revealed many intrachromosomal rearrangements, mainly inversions, when comparing Willisornis vidua karyotype with Gallus gallus, and corroborates the fissions revealed by chromosome painting. Conclusions Willisornis vidua presents multiple chromosomal rearrangements despite having a supposed conservative karyotype, demonstrating that our approach using a combination of FISH tools provides a higher resolution than previously obtained by chromosome painting alone. We also show that populations of Willisornis vidua appear conserved from a cytogenetic perspective, despite significant phylogeographic structure.

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