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Teixeira GA, Travenzoli NM, Tavares MG. Chromosomal organization of different repetitive sequences in four wasp species of the genus Trypoxylon Latreille (Hymenoptera: Crabronidae) and insights into the composition of wasp telomeres. Genome 2024; 67:243-255. [PMID: 38593475 DOI: 10.1139/gen-2023-0132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
This study characterizes the chromosomal organization of DNA repetitive sequences and the karyotypic evolution in four representatives of the solitary wasp genus Trypoxylon using conventional and molecular cytogenetic techniques. Our findings present the first cytogenetic data for Trypoxylon rogenhoferi (2n = 30) and Trypoxylon albonigrum (2n = 32), while the karyotypes of Trypoxylon nitidum (2n = 30) and Trypoxylon lactitarse (2n = 30) were similar to those previously described. Fluorochrome staining and microsatellite distribution data revealed differences in the constitutive heterochromatin composition among species. Trypoxylon nitidum and T. albonigrum exhibited one major rDNA cluster, potentially representing an ancestral pattern for aculeate Hymenoptera, while T. rogenhoferi and T. lactitarse showed two pericentromeric rRNA gene sites, suggesting amplification events in their ancestral clade. The (TCAGG)n motif hybridized in the terminal regions of the chromosomes in all four Trypoxylon species, which may suggest that this sequence represents DNA telomeric repeat. Notably, the presence of this repetitive sequence in the centromeric regions of certain chromosome pairs in two species supports the hypothesis of chromosomal fusions or inversions in the ancestral karyotype of Trypoxylon. The study expands the chromosomal mapping data of repetitive sequences in wasps and offers insights into the dynamic evolutionary landscape of karyotypes in these insects.
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Affiliation(s)
| | - Natália Martins Travenzoli
- Departamento de Biologia Geral, Universidade Federal de Viçosa, Laboratório de Citogenética de Insetos, Viçosa, Minas Gerais 36570-900, Brazil
| | - Mara Garcia Tavares
- Departamento de Biologia Geral, Universidade Federal de Viçosa, Laboratório de Citogenética de Insetos, Viçosa, Minas Gerais 36570-900, Brazil
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Damasceno MTDS, Teixeira GA, Ferreira PC, Lod RB, Barros LAC, de Aguiar HJAC. Physical chromosomal mapping of major ribosomal genes in 15 ant species with a review of hypotheses regarding evolution of the number and position of NORs in ants. COMPARATIVE CYTOGENETICS 2024; 18:105-122. [PMID: 38966326 PMCID: PMC11222723 DOI: 10.3897/compcytogen.18.125235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 05/27/2024] [Indexed: 07/06/2024]
Abstract
Recently, hypotheses regarding the evolutionary patterns of ribosomal genes in ant chromosomes have been under discussion. One of these hypotheses proposes a relationship between chromosomal location and the number of rDNA sites, suggesting that terminal locations facilitate the dispersion of rDNA clusters through ectopic recombination during meiosis, while intrachromosomal locations restrict them to a single chromosome pair. Another hypothesis suggests that the multiplication of rDNA sites could be associated with an increase in the chromosome number in Hymenoptera due to chromosomal fissions. In this study, we physically mapped rDNA sites in 15 new ant species and also reviewed data on rDNA available since the revision by Teixeira et al. (2021a). Our objectives were to investigate whether the new data confirm the relationship between chromosomal location and the number of rDNA sites, and whether the increase in the chromosome number is significant in the dispersion of rDNA clusters in ant karyotypes. Combining our new data with all information on ant cytogenetics published after 2021, 40 new species and nine new genera were assembled. Most species exhibited intrachromosomal rDNA sites on a single chromosome pair, while three species showed these genes in terminal regions of multiple chromosome pairs. On one hand, the hypothesis that the chromosomal location of rDNA clusters may facilitate the dispersion of rDNA sites in the ant genome, as previously discussed, was strengthened, but, on the other hand, the hypothesis of chromosomal fission as the main mechanism for dispersion of ribosomal genes in ants is likely to be refuted. Furthermore, in certain genera, the location of rDNA sites remained similar among the species studied, whereas in others, the distribution of these genes showed significant variation between species, suggesting a more dynamic chromosomal evolution.
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Affiliation(s)
- Monique Telcia dos Santos Damasceno
- Universidade Federal do Amapá, Campus Binacional – Oiapoque, n°3051, Bairro Universidade, Oiapoque, Amapá, 68980-000, BrazilUniversidade Federal do AmapáOiapoqueBrazil
- Programa de Pós-graduação em Biodiversidade Tropical, Universidade Federal do Amapá, Campus Marco Zero do Equador, Macapá, Amapá, 68.903-419, BrazilUniversidade Federal do AmapáMacapáBrazil
| | - Gisele Amaro Teixeira
- Universidade Federal do Amapá, Campus Binacional – Oiapoque, n°3051, Bairro Universidade, Oiapoque, Amapá, 68980-000, BrazilUniversidade Federal do AmapáOiapoqueBrazil
| | - Paulo Castro Ferreira
- Universidade Federal do Amapá, Campus Binacional – Oiapoque, n°3051, Bairro Universidade, Oiapoque, Amapá, 68980-000, BrazilUniversidade Federal do AmapáOiapoqueBrazil
- Programa de Pós-graduação em Biodiversidade Tropical, Universidade Federal do Amapá, Campus Marco Zero do Equador, Macapá, Amapá, 68.903-419, BrazilUniversidade Federal do AmapáMacapáBrazil
| | - Rodrigo Batista Lod
- Universidade Federal do Amapá, Campus Binacional – Oiapoque, n°3051, Bairro Universidade, Oiapoque, Amapá, 68980-000, BrazilUniversidade Federal do AmapáOiapoqueBrazil
- Programa de Pós-graduação em Biodiversidade Tropical, Universidade Federal do Amapá, Campus Marco Zero do Equador, Macapá, Amapá, 68.903-419, BrazilUniversidade Federal do AmapáMacapáBrazil
| | - Luísa Antônia Campos Barros
- Universidade Federal do Amapá, Campus Binacional – Oiapoque, n°3051, Bairro Universidade, Oiapoque, Amapá, 68980-000, BrazilUniversidade Federal do AmapáOiapoqueBrazil
| | - Hilton Jeferson Alves Cardoso de Aguiar
- Universidade Federal do Amapá, Campus Binacional – Oiapoque, n°3051, Bairro Universidade, Oiapoque, Amapá, 68980-000, BrazilUniversidade Federal do AmapáOiapoqueBrazil
- Programa de Pós-graduação em Biodiversidade Tropical, Universidade Federal do Amapá, Campus Marco Zero do Equador, Macapá, Amapá, 68.903-419, BrazilUniversidade Federal do AmapáMacapáBrazil
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Tavares MG, Teixeira GA. Cytogenetic characterization of solitary wasp Ancistrocerus flavomarginatus (Brèthes, 1906) (Hymenoptera, Vespidae) with insights into the chromosomal evolution in the genus. Genome 2023; 66:62-67. [PMID: 36645884 DOI: 10.1139/gen-2022-0095] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Cytogenetic studies have enabled the characterization of the chromosomal macrostructure and microstructure and have contributed to the understanding of the evolution of wasp karyotypes. However, studies on Eumeninae solitary wasps are scarce. In this study, we characterized the karyotype of Ancistrocerus flavomarginatus (Brèthes, 1906) and compared it with previous data from other Ancistrocerus (Wesmael, 1836) species to shed light on the chromosomal diversity of the genus. A chromosome number of 2n = 24 in females and n = 12 in males was observed. Comparing the A. flavomarginatus karyotype with that of another Ancistrocerus species showed variations in the morphology of some chromosomal pairs. The presence of two larger chromosome pairs, almost entirely heterochromatic, and the predominance of subtelocentric chromosomes with heterochromatic short arms in A. flavomarginatus support the occurrence of fissions in Ancistrocerus. A single site of ribosomal genes was observed in A. flavomarginatus, in addition to a size polymorphism of these rDNA clusters between the homologues of some analyzed females. This polymorphism may originate from duplications/deletions due to unequal crossing-over or amplification via transposable elements. The (GA)15 microsatellite is located exclusively in euchromatic regions. Our data show that different rearrangements seem to shape chromosomal evolution in Ancistrocerus species.
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Affiliation(s)
- Mara Garcia Tavares
- Laboratory of Insect Cytogenetics, Department of General Biology, CCB, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Gisele Amaro Teixeira
- Laboratory of Insect Cytogenetics, Department of General Biology, CCB, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
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Teixeira GA, Jacintho GDF, de Aguiar HJAC, Lopes DM, Barros LAC. Cytogenetic Analysis of the Fungus-Farming Ant Cyphomyrmex rimosus (Spinola, 1851) (Formicidae: Myrmicinae: Attini) Highlights Karyotypic Variation. Cytogenet Genome Res 2023; 162:579-586. [PMID: 36848876 DOI: 10.1159/000529607] [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: 09/19/2022] [Accepted: 02/03/2023] [Indexed: 03/01/2023] Open
Abstract
The fungus-farming ant genus Cyphomyrmex (subtribe Attina, clade Neoattina) comprises 23 described species that are widely distributed throughout the Neotropics. Species within Cyphomyrmex have taxonomic issues such as Cyphomyrmex rimosus (Spinola, 1851) which is likely a species complex. Cytogenetics is a useful tool for evolutionary studies and understanding species with dubious taxonomy. In this study, we characterized the karyotype of C. rimosus from Viçosa, Minas Gerais State, southeastern Brazil using classical and molecular cytogenetic techniques to enrich the chromosomal information about Cyphomyrmex. The karyotype of C. rimosus from the rainforest of southeastern Brazil (2n = 22, 18m + 4sm) notably contrasts with that previously described for this species in Panama (2n = 32). This intraspecific chromosomal variation suggests the existence of a species complex within this taxon according to the previous hypothesis derived from morphological analysis. We detected GC-rich heterochromatic regions in C. rimosus and, using repetitive DNA probes, showed that this heterochromatin shares repetitive sequences with other Neoattina species already studied, enhancing the importance of this specific genome region in the understanding of Attina evolution. Mapping of microsatellite (GA)15 on C. rimosus was restricted to the euchromatic regions of all chromosomes. The single intrachromosomal rDNA sites observed in C. rimosus follow the general genomic organization trend of ribosomal genes in Formicidae. Our study extends the data of chromosome mapping on Cyphomyrmex and reinforces the importance of cytogenetic studies in different localities to better understand taxonomic issues in widely distributed taxa such as C. rimosus.
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Affiliation(s)
- Gisele Amaro Teixeira
- Programa de Pós-graduação em Biologia Celular e Estrutural, Universidade Federal de Viçosa, Viçosa, Brazil
- Laboratório de Citogenética de Insetos, Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Gabriela de Figueiredo Jacintho
- Laboratório de Citogenética de Insetos, Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Brazil
- Programa de Pós-graduação em Entomologia, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Hilton Jeferson Alves Cardoso de Aguiar
- Universidade Federal do Amapá, Campus Binacional - Oiapoque, Bairro Universidade, Oiapoque, Brazil
- Programa de Pós-graduação em Biodiversidade Tropical, Universidade Federal do Amapá, Macapá, Brazil
| | - Denilce Meneses Lopes
- Programa de Pós-graduação em Biologia Celular e Estrutural, Universidade Federal de Viçosa, Viçosa, Brazil
- Laboratório de Citogenética de Insetos, Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Brazil
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Teixeira GA, Barros LAC, Silveira LI, Orivel J, Lopes DM, Aguiar HJAC. Karyotype conservation and genomic organization of repetitive sequences in the leaf-cutting ant Atta cephalotes (Linnaeus, 1758) (Formicidae: Myrmicinae). Genome 2022; 65:525-535. [PMID: 35973225 DOI: 10.1139/gen-2021-0129] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Leaf-cutting ants are among the New World's most conspicuous and studied ant species due to their notable ecological and economic role. Cytogenetic studies carried out in Atta show remarkable karyotype conservation among the species. We performed classical cytogenetics and physical mapping of repetitive sequences in the leaf-cutting ant Atta cephalotes, the type species of the genus. Our goal was to test the karyotype conservation in Atta and to start to understand the genomic organization and diversity regarding repetitive sequences in leaf-cutting ants. Atta cephalotes showed 2n=22 (18m+2sm+2st) chromosomes. The heterochromatin followed a centromeric pattern, and the GC-rich regions and 18S rDNA clusters were co-located interstitially in the 4th metacentric pair. These cytogenetic characteristics were observed in other Atta species that had previously been studied, confirming the karyotype conservation in Atta. Evolutionary implications regarding the conservation of the chromosome number in leaf-cutting ants are discussed. Telomeric motif (TTAGG)n was detected in A. cephalotes as observed in other ants. Five out of the 11 microsatellites showed a scattered distribution exclusively on euchromatic areas of the chromosomes. Repetitive sequences mapped on the chromosomes of A. cephalotes are the first insights into genomic organization and diversity in leaf-cutting ants, useful in further comparative studies.
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OUP accepted manuscript. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Cardoso DC, Cristiano MP. Karyotype Diversity, Mode, and Tempo of the Chromosomal Evolution of Attina (Formicidae: Myrmicinae: Attini): Is There an Upper Limit to Chromosome Number? INSECTS 2021; 12:insects12121084. [PMID: 34940172 PMCID: PMC8707115 DOI: 10.3390/insects12121084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 12/02/2022]
Abstract
Simple Summary Ants are an important insect group that includes a considerable number of species. Along with this diversity in species, they also exhibit a wide variation in chromosome numbers, from 1 up to 60 chromosomes. DNA molecules can be counted in a specific stage of the cell life cycle and quantified. These DNA molecules are very tightly packed together with several proteins and are called chromosomes. Each species shows a specific number of chromosomes with different shapes and sizes, as well as different quantities of DNA. We can use such information (the number of chromosomes, shape of the chromosomes, and quantity of DNA) as morphological attributes to study evolution at the species level. In this study, we describe new karyotypes of several ant species. In addition, from previous studies, we have compiled all the available information regarding the chromosome number and DNA quantity in fungus-farming ant cells. Different processes, called rearrangements, can change chromosomes over time, producing new character states. Such states can be tracked, along with the species and groups of similar species, using their relationships to identify patterns. We use DNA sequences to reconstruct the relationships of fungus-farming ant species (molecular phylogeny). By comparing such phylogeny with the chromosome number and DNA quantity, we discuss the evolution of chromosomes and DNA quantity (or genome size), and the potential limits to these features across fungus-farming ants. Abstract Ants are an important insect group that exhibits considerable diversity in chromosome numbers. Some species show only one chromosome, as in the males of the Australian bulldog ant Myrmecia croslandi, while some have as many as 60 chromosomes, as in the males of the giant Neotropical ant Dinoponera lucida. Fungus-growing ants are a diverse group in the Neotropical ant fauna, engaged in a symbiotic relationship with a basidiomycete fungus, and are widely distributed from Nearctic to Neotropical regions. Despite their importance, new chromosome counts are scarcely reported, and the marked variation in chromosome number across species has been poorly studied under phylogenetic and genome evolutionary contexts. Here, we present the results of the cytogenetic examination of fungus-farming ants and compile the cytogenetic characteristics and genome size of the species studied to date to draw insights regarding the evolutionary paths of karyotype changes and diversity. These data are coupled with a fossil-calibrated phylogenetic tree to discuss the mode and tempo of chromosomal shifting, considering whether there is an upper limit for chromosome number and genome size in ants, using fungus-farming ants as a model study. We recognize that karyotypes are generally quite variable across fungus-farming ant phylogeny, mostly between genera, and are more numerically conservative within genera. A low chromosome number, between 10 and 12 chromosomes, seems to present a notable long-term evolutionary stasis (intermediate evolutionary stasis) in fungus-farming ants. All the genome size values were inside a limited spectrum below 1 pg. Eventual departures in genome size occurred with regard to the mean of 0.38 pg, indicating that there is a genome, and likely a chromosome, number upper limit.
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