High scale genomic analysis of repetitive elements focusing on B chromosomes of the cichlid fish Astatotilapia latifasciata

Author(s)

Rafael Luiz Buogo Coan

• Document type: Master's Dissertation
• Press: Botucatu. 2016-11-08.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu
• Defense date: 2016-09-26
• Advisor: Cesar Martins

Abstract

B chromosomes (B) are supernumerary elements found in many taxonomic groups. Their heterochromatic composition is related to abundance in repetitive sequences. Their origin is linked to the A chromosome complement (A), as a mosaic of sequences from A. The first report of a chromosome B in cichlids from the Great Lakes of East Africa was on Astatotilapia latifasciata, which can harbor 0, 1 or 2 B chromosomes. Classical cytogenetics studies found high content of repetitive elements on the species B chromosome. Therefore, the study of B chromosome repetitive content is key to understand their origin and perpetuation. A combination of next generation sequencing, fluorescent in situ hybridization (FISH) and real-time PCR reveled several expanded repetitive elements on B chromosome of A. latifasciata. DNA transposons, as Tc1-Mariner, and retrotransposons, such as Bel/Pao and Gypsy were found in higher proportion on the B chromosome. With RNA sequencing data (RNA-seq) we evaluated repetitive transcriptional levels between B- and B+ individuals. Although several elements have differential expression among groups, expanded B elements were equally transcribed. Presence of expanded repetitive sequences on B chromosome and their transcriptional profile brings information about B composition and dynamics. (AU)

• FAPESP's process: 14/16763-6 - High scale genomic analysis of repetitive elements focusing on B chromosomes of Astatotilapia latifasciata cichlid
• Grantee: Rafael Luiz Buogo Coan
• Support Opportunities: Scholarships in Brazil - Master