Effects of B chromosomes in the regulation of gene expression in the cichlid Astatotilapia latifasciata

Author(s)

Adauto Lima Cardoso

• Document type: Doctoral Thesis
• Press: Botucatu. 2017-08-23.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu
• Defense date: 2017-06-27
• Advisor: Cesar Martins

Abstract

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. (AU)

• FAPESP's process: 12/21546-9 - Immunocytogenetic analysis in the cichlid fish Astatotilapia latifasciata: epigenetic inferences and its contributions in understanding the biological role of B chromosomes
• Grantee: Adauto Lima Cardoso
• Support Opportunities: Scholarships in Brazil - Doctorate