FISH detection of ribosomal cistrons and assortment-distortion for X and B chromosomes in Dichroplus pratensis (Acrididae)
Assortment-distortion with respect to the X and NOR activity of a rare mitotically stable B chromosome (BN), was examined in 16 males of Dichroplus pratensis (Acrididae: Melanoplinae) from Argentine populations. In 1B individuals, the X and B associate preferentially during prophase I reaching a max...
| Autores: | , , |
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| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2004 |
| País: | Argentina |
| Recursos: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositório: | CONICET Digital (CONICET) |
| Idioma: | inglês |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/45612 |
| Acesso em linha: | http://hdl.handle.net/11336/45612 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Dichroplus Pratensis Acrididae: Melanoplinae B Chromosome Argentina https://purl.org/becyt/ford/1.6 https://purl.org/becyt/ford/1 |
| Resumo: | Assortment-distortion with respect to the X and NOR activity of a rare mitotically stable B chromosome (BN), was examined in 16 males of Dichroplus pratensis (Acrididae: Melanoplinae) from Argentine populations. In 1B individuals, the X and B associate preferentially during prophase I reaching a maximum level of association at zygotene. Frequency of X/B association remains relatively high up to diplotene-diakinesis and decreases steeply towards metaphase I. The percent X/B association at each stage is positively influenced by association at the previous stage, and interindividual variability in X/B association decreases as the frequency of association increases. Both chromosomes tended to preferentially orientate toward the same pole at MI (mean ratio of 16 individuals, 1.50:1) which determined an excess of XB and 00 second spermatocytes over X0 and 0B ones (1.39:1). No significant differences occurred between the MI, AI and MII assortment ratios. Fluorescent in situ hybridisation (FISH) confirmed that the B chromosome carries ribosomal genes and helped to establish that, during spermiogenesis, both the B and the normal NOR-bearing chromosome (S8) are clustered near the centriole adjunct region of spermatids. However, FISH failed to reveal the existence of inactive ribosomal cistrons in the X chromosome, as previously suggested, thus providing no support to a simple origin of the B from the X. |
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