Immunolocalization of the Synaptonemalcomplex in Astatotilapia latifasciata, Focusing on the Pairing of B Chromosome

B chromosome is known as a supernumerary chromosome, which can resemble the normal complement of chromosomes as well as be distinguished. One characteristic that distinguishes it from other chromosomes of the A complement is the fact that it does not follow Mendelian laws and does not have a defined pattern of meiotic and/or mitotic division. Meiosis is the cell division through which haploid cells originate from the initial division of diploid cells. To perform such reductional segregation, homologous chromosomes must recognize and align to its mate. This process is called chromosome pairing and it is stabilized by docking of the synaptonemal complex (SC) among homologs. The SC is formed by lateral elements (LE) and a central element (CE), being the protein SYCP3 one of the components present in LEs and the protein SYCP1 especially present in CE. Proteins are essential to the correct formation of SC, avoiding chromosomal abnormalities during meiosis. The objective of this work was to locate and understand how the B chromosome behaves during formation of the synaptonemal complex. Immunostaining was performed with antibodies against the synaptonemal complex proteins SYCP1 and SYCP3, and localization of the B chromosome made by means of Fluorescent in situ Hybridization with a specific probe. Results shows that the meiotic chromosomes in the species A. latifasciata are performing the correct pairing and chromosome B is autopairing.

Financial support: FAPESP, CAPES, CNPq