Small non-coding RNAs (microRNAs and PIWI-interacting RNAs) characterization in the B chromosome presence in Astatotilapia latifasciata

Author(s)

Jordana Inacio Nascimento Oliveira

• Document type: Doctoral Thesis
• Press: Botucatu. 2022-03-15.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu
• Defense date: 2022-02-18
• Advisor: Cesar Martins

Abstract

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. (AU)

• FAPESP's process: 17/25193-7 - PiRNA actuation in transposable elements silencing on B chromosome presence of the Astatotilapia latifasciata (Cichlidae)
• Grantee: Jordana Inácio Nascimento Oliveira
• Support Opportunities: Scholarships in Brazil - Doctorate