Efeitos de cromossomos B em vias de regulação da expressão gênica no ciclídeo Astatotilapia latifasciata
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2017-06-27
Autores
Cardoso, Adauto Lima [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Cromossomos supernumerários são polimorfismos numéricos frequentemente registrados em eucariotos, sendo que seus efeitos são pouco elucidados. Em alguns indivíduos da espécie Astatotilapia latifasciata pode-se identificar um ou dois cromossomos B, que são totalmente heterocromáticos e ricos em sequências repetitivas. Em vista de compreender sua origem, evolução e efeitos, este elemento vem sendo largamente explorado por técnicas integradas de citogenética, biologia molecular e genômica. Aqui, explorou-se o padrão de marcas epigenéticas do DNA deste cromossomo B e seus efeitos nas vias de metilação do DNA e de formação de tRFs. Usando-se imunocitogenética, ferramentas de bioinformática, quantificação global de 5mC e 5hmC e RT-qPCR, identificou-se que o cromossomo B de A. latifasciata possui padrão epigenético ativo e que não é um isocromossomo. Além disso, foram observados efeitos heterogêneos deste cromossomo na expressão de epi-miRNAs candidatos, de genes de modificações epigenéticas do DNA e de genes relacionados com a formação de tRFs. Como consequência, também foram registrados efeitos de cromossomos B nos níveis globais de 5mC e 5hmC e na formação de tRFs. Essas variações observadas parecem estar relacionadas com os mecanismos de manutenção do cromossomo B e estão em desacordo com a difundida ideia de que ele seja um elemento inerte.
Supernumerary B chromosomes are numerical polymorphisms frequently registered in eukaryotes, and their effects are not elucidated. In some individuals of the species Astatotilapia latifasciata one or two B isochromosomes can be identified, which are totally heterochromatic and enriched by repetitive sequences. In order to understand its origin, evolution and effects, this element has been widely explored by integrated techniques of cytogenetics, molecular biology and genomics. Here, the pattern of epigenetic marks of the DNA of this B chromosome and its effects on the pathways of DNA methylation and formation of tRFs. Using immunocytogenetics, bioinformatics tools, global quantification of 5mC and 5hmC and RT-qPCR, it was identified that the B chromosome of A. latifasciata has active epigenetic pattern and it is not an isochromosome. In addition, heterogeneous effects of this chromosome were observed in the expression of candidate epi-miRNAs, genes of epigenetic modifications of DNA and genes related to the formation of tRFs. As a consequence, effects of B chromosomes were also registered at the global levels of 5mC and 5hmC and in the formation of tRFs. These variations appear to be related to the maintenance mechanisms of chromosome B and are in opposition with the widespread idea that they are inert elements.
Supernumerary B chromosomes are numerical polymorphisms frequently registered in eukaryotes, and their effects are not elucidated. In some individuals of the species Astatotilapia latifasciata one or two B isochromosomes can be identified, which are totally heterochromatic and enriched by repetitive sequences. In order to understand its origin, evolution and effects, this element has been widely explored by integrated techniques of cytogenetics, molecular biology and genomics. Here, the pattern of epigenetic marks of the DNA of this B chromosome and its effects on the pathways of DNA methylation and formation of tRFs. Using immunocytogenetics, bioinformatics tools, global quantification of 5mC and 5hmC and RT-qPCR, it was identified that the B chromosome of A. latifasciata has active epigenetic pattern and it is not an isochromosome. In addition, heterogeneous effects of this chromosome were observed in the expression of candidate epi-miRNAs, genes of epigenetic modifications of DNA and genes related to the formation of tRFs. As a consequence, effects of B chromosomes were also registered at the global levels of 5mC and 5hmC and in the formation of tRFs. These variations appear to be related to the maintenance mechanisms of chromosome B and are in opposition with the widespread idea that they are inert elements.
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Cromossomo supernumerário, Epigenética, Modificações do DNA, MicroRNAs, Fragmentos de tRNA