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Multiple heterochromatin diversification events in the genome of fungus-farming ants: insights from repetitive sequences. Chromosoma 2022; 131:59-75. [PMID: 35325297 DOI: 10.1007/s00412-022-00770-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/18/2022] [Accepted: 02/21/2022] [Indexed: 11/03/2022]
Abstract
A substantial portion of the eukaryotic genome includes repetitive DNA, which is important for its stability, regulation, and architecture. Fungus-farming ant genomes show remarkable structural rearrangement rates that were necessary for the establishment of their agriculture-based lifestyle, highlighting the relevance of this peculiar group in understanding the repetitive portion of ant genome. Chromosomal banding studies are in accordance with genomic data because they show that repetitive heterochromatic sequences of basal and derivative Attina species are GC-rich, an uncommon trait in Formicidae. To understand the evolutionary dynamics of heterochromatin in Attina, we compared GC-rich heterochromatin patterns between the Paleoattina and Neoattina clades of this subtribe. To this end, we hybridized the Mrel-C0t probe (highly and moderately repetitive DNA) obtained from Mycetomoellerius relictus, Neoattina with GC-rich heterochromatin, in karyotypes of Paleoattina and Neoattina species. Additionally, we mapped the repetitive sequences (GA)15 and (TTAGG)6 in species of the two clades to investigate their organization and evolutionary patterns in the genome of Attina. The Mrel-C0t probe marked the heterochromatin in M. relictus, in other Mycetomoellerius spp., and in species of Mycetarotes, Cyphomyrmex, and Sericomyrmex (Neoattina). In Mycetomoellerius urichii, only pericentromeric heterochromatin was marked with Mrel-C0t. No marking was observed in Paleoattina species or in Atta and Acromyrmex (Neoattina). These results indicated that different evolutionary events led to heterochromatin differentiation in Attina. The most likely hypothesis is that GC-rich heterochromatin arose in the common ancestor of the two clades and accumulated various changes throughout evolution. The sequences (GA)15 and (TTAGG)6 located in euchromatin and telomeres, respectively, showed more homogeneous results among the species.
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da Silva MJ, de Araújo Vieira AP, Galvão Cipriano FM, Dos Santos Cândido MR, de Oliveira EHC, Gimenez Pinheiro T, da Silva EL. The Karyotype of Salvator merianae (Squamata, Teiidae): Analyses by Classical and Molecular Cytogenetic Techniques. Cytogenet Genome Res 2020; 160:94-99. [PMID: 32062647 DOI: 10.1159/000506140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/17/2020] [Indexed: 12/28/2022] Open
Abstract
In this study, we analyzed the karyotype of Salvator merianae (Teiidae) from the Brazilian semiarid region using different cytogenetic markers. Chromosomes were examined by classical (Giemsa and AgNOR staining) and molecular (FISH with ribosomal, telomeric, and microsatellite probes) cytogenetic approaches. S. merianae showed a diploid chromosome number of 2n = 38 (10 biarmed macrochromosomes + 28 microchromosomes). No sex-linked chromosome heteromorphisms were observed. Clusters of 18S/28S rDNA were localized in the terminal region of the long arm of pair 2. In addition to the typical telomeric signals, (TTAGGG)n repeats were detected in the pericentromeric region of some macrochromosome pairs, which might indicate the occurrence of chromosomal rearrangements via chromosome fusions. Hybridization signals of the microsatellite probes (GA)n, (GAA)n, and (GAG)n were uniformly distributed across all chromosomes, while (CA)n, (CAA)n, and (CAC)n produced brighter signals in the telomeric and pericentromeric regions of specific chromosome pairs. The comparison with previous studies demonstrates that, despite the wide distribution of S. merianae, the macrostructure organization of the karyotype remained unchanged, showing stability in diploid number and chromosome morphology.
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Almeida BRRD, Milhomem-Paixão SSR, Noronha RCR, Nagamachi CY, Costa MJRD, Pardal PPDO, Coelho JS, Pieczarka JC. Karyotype diversity and chromosomal organization of repetitive DNA in Tityus obscurus (Scorpiones, Buthidae). BMC Genet 2017; 18:35. [PMID: 28412934 PMCID: PMC5392961 DOI: 10.1186/s12863-017-0494-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 03/25/2017] [Indexed: 01/22/2023] Open
Abstract
Background Holocentric chromosomes occur in approximately 750 species of eukaryotes. Among them, the genus Tityus (Scorpiones, Buthidae) has a labile karyotype that shows complex multivalent associations during male meiosis. Thus, taking advantage of the excellent model provided by the Buthidae scorpions, here we analyzed the chromosomal distribution of several repetitive DNA classes on the holocentric chromosomes of different populations of the species Tityus obscurus Gervais, 1843, highlighting their involvement in the karyotypic differences found among them. Results This species shows inter- and intrapopulational karyotype variation, with seven distinct cytotypes: A (2n = 16), B (2n = 14), C (2n = 13), D (2n = 13), E (2n = 12), F (2n = 12) and G (2n = 11). Furthermore, exhibits achiasmatic male meiosis and lacks heteromorphic sex chromosomes. Trivalent and quadrivalent meiotic associations were found in some cytotypes. In them, 45S rDNAs were found in the terminal portions of two pairs, while TTAGG repeats were found only at the end of the chromosomes. In the cytotype A (2n = 16), the U2 snRNA gene mapped to pair 1, while the H3 histone cluster and C0t-1 DNA fraction was terminally distributed on all pairs. Mariner transposons were found throughout the chromosomes, with the exception of one individual of cytotype A (2n = 16), in which it was concentrated in heterochromatic regions. Conclusions Chromosomal variability found in T. obscurus are due to rearrangements of the type fusion/fission and reciprocal translocations in heterozygous. These karyotype differences follow a geographical pattern and may be contributing to reproductive isolation between populations analyzed. Our results also demonstrate high mobility of histone H3 genes. In contrast, other multigene families (45S rDNA and U2 snRNA) have conserved distribution among individuals. The accumulation of repetitive sequences in distal regions of T. obscurus chromosomes, suggests that end of chromosome are not covered by the kinetochore.
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Affiliation(s)
- Bruno Rafael Ribeiro de Almeida
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil
| | - Susana Suely Rodrigues Milhomem-Paixão
- Instituto Federal de Educação, Ciência e Tecnologia de Goiás, Campus Valparaíso de Goiás, BR-040, km 6, Avenida Saia Velha, S/N, Área 8, Parque Esplanada V, 72876-601, Valparaíso de Goiás, Goiás, Brazil
| | - Renata Coelho Rodrigues Noronha
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil
| | - Cleusa Yoshiko Nagamachi
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil
| | - Marlyson Jeremias Rodrigues da Costa
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil
| | - Pedro Pereira de Oliveira Pardal
- Laboratório de Entomologia Médica e Artrópodes Peçonhentos, Núcleo de Medicina Tropical, Universidade Federal do Pará, Avenida Generalíssimo Deodoro, 92, 66055-240, Belém, Pará, Brazil
| | - Johne Souza Coelho
- Laboratório de Entomologia Médica e Artrópodes Peçonhentos, Núcleo de Medicina Tropical, Universidade Federal do Pará, Avenida Generalíssimo Deodoro, 92, 66055-240, Belém, Pará, Brazil
| | - Julio Cesar Pieczarka
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Avenida Augusto Corrêa, n°01, Av. Perimetral, s/n. Guamá, 66075-900, Belém, Pará, Brazil.
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