Caracterização de pequenos RNAs não-codificantes (microRNAs e PIWI-interacting RNAs) na presença do cromossomo B do ciclídeo africano Astatotilapia latifasciata
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Data
2022-02-18
Autores
Nascimento-Oliveira, Jordana Inacio
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os supranumerários cromossomos B são elementos extras ao genoma encontrados em diversas espécies de eucariotos, desde fungos, plantas a animais. A origem independente nos mais diversos organismos também reflete a sua variedade quanto a número, morfologia e constituição. Desta forma, sabe-se que os cromossomos B são constituídos por DNA repetitivo, genes codificadores de proteína e genes que transcrevem RNAs não-codificantes (ncRNA). Os ncRNAs participam de uma infinidade de processos biológicos, desde os fundamentais como transcrição e tradução, até regulação durante o desenvolvimento embrionário e ciclo celular. Desta forma, conhecendo a baixa densidade de genes codificadores de proteínas nos cromossomos B, o presente estudo focou em caracterizar os ncRNAs, ainda pouco explorados e que trazem perspectivas interessantes no entendimento da origem e comportamento desse elemento extra. Foi utilizado como modelo de estudo o peixe Astatotilapia latifasciata, pertencente à família Cichlidae, modelo em estudos evolutivos. Dentre uma infinidade de classes de ncRNA optou-se por explorar a partir do RNAseq de A. latifascita os pequenos RNAs não-codificantes: microRNAs (miRNA) e PIWI- interacting RNAs (piRNA). Foram encontrados diversos miRNAs diferencialmente expressos em amostras com cromossomo B. Esses miRNAs tem como alvos diversos genes codificadores de proteínas e propõe-se que o cromossomo B, a partir da atuação dos miRNAs impacta em diversos processos biológicos. Adicionalmente, clusters de piRNAs presentes no cromossomo B foram detalhadamente descritos indicando o envolvimento deste elemento extra em arquitetar o silenciamento de elementos transponíveis. Complementarmente, essa tese adicionou dois objetivos suplementares. Uma revisão sobre as pesquisas de RNAs e cromossomos B é apresentada e fornece uma linha do tempo e principais resultados que foram reunidos em uma árvore filogenética representativa dos organismos com cromossomo B e estudos relacionando RNAs. Outrossim, essa tese encerra com reflexões sobre divulgação científica, relatando alguns dos trabalhos publicados ao longo do período e propondo diretrizes para a expansão da popularização da ciência e educação científica no nosso país.
The supernumerary B chromosomes are extra elements to the genome found in several eukaryotes species, from fungi, plants to animals. The polyphyletic origin in the most diverse organisms also reflects their variety in terms of number, morphology and constitution. Thus, it is known that the B chromosomes are composed by repetitive DNA, protein coding genes and genes that transcribed non-coding RNAs (ncRNAs). ncRNAs participate in several biological processes, from fundamental ones such as transcription and translation, to regulation during embryonic development and cell cycle. Thus, taking into account the low density of protein-coding genes in the B chromosomes, the present study focused on characterizing the ncRNAs, that are poorly explored and can bring interesting perspectives to understand the origin and behavior of this extra element. The African cichlid Astatotilapia latifasciata fish, a family model in evolutionary studies, was used as a study model. Among a multitude of ncRNA classes, it was decided to explore from the RNAseq of A. latifascita the small non-coding RNAs: microRNAs (miRNA) and PIWI-interacting RNAs (piRNA). Several miRNAs were found differentially expressed in samples with B chromosome. These miRNAs target several protein-coding genes and it is proposed that the B chromosome, under the action of miRNAs, impacts on several biological processes. Additionally, piRNA clusters present on the B chromosome were described in detail, indicating the involvement of this extra element in architecting the silencing of transposable elements. Completely, this thesis added two supplementary objectives. A review of the research on RNAs and B chromosomes is presented and provides a timeline and main results that have been brought together in a representative phylogenetic tree of organisms with B chromosome and RNA studies. Furthermore, this thesis ends with reflections on science outreach, reporting some of the works published throughout the period and proposing guidelines for the expansion of the popularization of science and scientific education in our country.
The supernumerary B chromosomes are extra elements to the genome found in several eukaryotes species, from fungi, plants to animals. The polyphyletic origin in the most diverse organisms also reflects their variety in terms of number, morphology and constitution. Thus, it is known that the B chromosomes are composed by repetitive DNA, protein coding genes and genes that transcribed non-coding RNAs (ncRNAs). ncRNAs participate in several biological processes, from fundamental ones such as transcription and translation, to regulation during embryonic development and cell cycle. Thus, taking into account the low density of protein-coding genes in the B chromosomes, the present study focused on characterizing the ncRNAs, that are poorly explored and can bring interesting perspectives to understand the origin and behavior of this extra element. The African cichlid Astatotilapia latifasciata fish, a family model in evolutionary studies, was used as a study model. Among a multitude of ncRNA classes, it was decided to explore from the RNAseq of A. latifascita the small non-coding RNAs: microRNAs (miRNA) and PIWI-interacting RNAs (piRNA). Several miRNAs were found differentially expressed in samples with B chromosome. These miRNAs target several protein-coding genes and it is proposed that the B chromosome, under the action of miRNAs, impacts on several biological processes. Additionally, piRNA clusters present on the B chromosome were described in detail, indicating the involvement of this extra element in architecting the silencing of transposable elements. Completely, this thesis added two supplementary objectives. A review of the research on RNAs and B chromosomes is presented and provides a timeline and main results that have been brought together in a representative phylogenetic tree of organisms with B chromosome and RNA studies. Furthermore, this thesis ends with reflections on science outreach, reporting some of the works published throughout the period and proposing guidelines for the expansion of the popularization of science and scientific education in our country.
Descrição
Palavras-chave
Genoma, Transcriptoma, RNAseq, Elementos transponíveis, Divulgação científica, Genome, Evolution, Transcriptome, Transposable elements, Science outreach