Co-located hAT transposable element and 5S rDNA in an interstitial telomeric sequence suggest the formation of Robertsonian fusion in armored catfish

Author(s)

Glugoski, Larissa ^[1] ; Giuliano-Caetano, Lucia ^[2] ; Moreira-Filho, Orlando ^[3] ; Vicari, Marcelo R. ^[1] ; Nogaroto, Viviane ^[1]

Affiliation

^[1] Univ Estadual Ponta Grossa, Dept Biol Estrut Mol & Genet, Ave Carlos Cavalcanti 4748, BR-84030900 Ponta Grossa, Parana - Brazil

^[2] Univ Estadual Londrina, Dept Biol Geral, Rod Celso Garcia Cid, Pr 445 Km 380, BR-86057970 Londrina, PR - Brazil

^[3] Univ Fed Sao Carlos, Dept Genet & Evolucao, Rod Washington Luis, Km 235, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Gene; v. 650, p. 49-54, APR 15 2018.
• Web of Science Citations: 11

Abstract

Co-located 5S rDNA genes and interstitial telomeric sites (ITS) revealed the involvement of multiple 5S rDNA clusters in chromosome rearrangements of Loricariidae. Interstitial (TTAGGG)n vestiges, in addition to telomeric sites, can coincide with locations of chromosomal rearrangements, and they are considered to be hotspots for chromosome breaks. This study aimed the molecular characterization of 5S rDNA in two Rineloricaria latirostris populations and examination of roles of 5S rDNA in breakpoint sites and its in situ localization. Rineloricaria latirostris from Brazil's Das Pedras river (2n = 46 chromosomes) presented five pairs identified using a 5S rDNA probe, in addition to a pair bearing a co-located ITS/SS rDNA. Rineloricaria latirostris from the Piumhi river (2n = 48 chromosomes) revealed two pairs containing 5S rDNA, without ITS. A 702-bp amplified sequence, using 5S rDNA primers, revealed an insertion of the MT transposable element (TE), referred to as a degenerate 5S rDNA. Double-FISH (fluorescence in situ hybridization) demonstrated co-localization of 5S rDNA/degenerate 5S rDNA, 5S rDNA/hAT and ITS/5S rDNA from the Das Pedras river population. Piumhi river isolates possessed only 5S rDNA sites. We suggest that the degenerate 5S rDNA was generated by unequal crossing over, which was driven by invasion of hAT, establishing a breakpoint region susceptible to chromosome breakage, non-homologous recombination and Robertsonian (Rb) fusion. Furthermore, the presence of clusters of 5S rDNA at fusion points in other armored catfish species suggests its re-use and that these regions represent hotspots for evolutionary rearrangements within Loricariidae genomes. (AU)

• FAPESP's process: 17/24695-9 - DNA breakpoints and chromosomal rearrangements in Loricariidae fishes (Teleostei, Siluriformes): A cytogenetic and molecular approach
• Grantee: Orlando Moreira Filho
• Support Opportunities: Regular Research Grants