Contribuições a elucidação da estrutura, origem e evolução de neo-sistemas cromossômicos de determinação sexual em gafanhotos utilizando como modelo espécies dos gêneros Chlorus, Dichromatos e Eurotettix (Melanoplinae; Acrididae)

• Autor(a) principal: Palacios-Gimenez, Octavio Manuel [UNESP]
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/108677
• topic: Animal genetics; Genetica animal; Gafanhoto; Cromossomos sexuais; DNA; Histonas; Citogenética animal; Morfologias (Animais)

Sex chromosomes have been evolved independently from a pair of homologous autosomes and several lineages share common characteristics, representing fascinating examples of evolutionary convergence. Some of those features include accumulation of various kinds of repetitive DNAs, recombination constraint, loss or gain of genes that derived in the genetic and morphological differentiation among the sex chromosomes X and Y or Z and W. In Orthoptera, sex chromosome systems commonly found in the most studies species is the type X0♂/XX♀; however, in the subfamily Melanoplinae, derived variants neo-XY or neo-X1X2Y evolved several times by repeated autosome-sex chromosome Robtersonian fusions (Rb-fusions). Thus, the aim of this study was to analyze sex chromosome systems in Melanoplinae using as model species of the phylogenetically related genera Chlorus, Eurotettix and Dichromatos, in addition Ronderosia bergi. For this proposes it was integrated classical cytogenetic analysis, cytogenetic mapping for distinct repetitive DNAs and microdisssected sex chromosomes and immunolocalization for distinct histone modifications. Moreover in R. bergi the microdissected chromosomes were used as source for specific amplification of multigene families in order to address the specific variation of these sequences in the sex chromosomes. Concerning to the phylogenetically related genera, our data indicate a non-spreading of heterochromatic blocks and pool of repetitive DNAs (C0t-1 DNA) in the sex chromosomes, but the spreading of multigene families among the neo-sex chromosomes of Eurotettix and Dichromatos was remarkable, particularly for 5S rDNA. These results also suggest a common origin and subsequent differential accumulation of repetitive DNAs in the sex chromosomes of Dichromatos and an independent origin of the sex chromosomes of the neo-XY and neo-X1X2Y systems intragenerically. In the species R. bergi, our data supports the argument that the...