Modificaciones de la histona H3 y su relación con el silenciamiento y la eliminación cromosómica en un ave

DEL PRIORE LUCIA ; PIGOZZI M.I.

Chascomús

Congreso; XV Jornadas Anuales de Sociedad Argentina de Biología, ?A 60 años de la descripción de la estructura del ADN?; 2013

Sociedad Argentina de Biología

In our laboratory we reported the first case of a germline-restricted chromosome in a bird (Taeniopygia guttata, zebra finch). This chromosome is eliminated during male meiosis and its chromatin is enriched with proteins related to gene silencing. In the present work we report a similar case of chromosome elimination in the Bengalese finch (Lonchura domestica), a related species to zebra finch. Using immunolabeling on chromosome spreads from the testis we analyzed molecular modifications of the chromatin related to chromosome condensation and segregation. We found that before elimination the chromatin of the restricted chromosome (RC) is enriched with di- and tri-methylated H3 at lysine 9. During metaphase I, the RC is devoid of H3K9me2 but H3K9me3 persists. In addition, the phosphorylated histone H3 at serine 10, a mark for chromosome condensation during mitosis and meiosis, is absent from the RC during metaphase I, while the chromosomes of the regular set are strongly labeled. It is proposed that the change of methylation status of the RC is part of the signals leading to its elimination during the first meiotic division. The deficiency in H3 phosphorylation may have a role to inactivate the RC centromere, in agreement with similar data reported in other organisms showing chromosome elimination.