Molecular architecture of meiotic chromosomes

Abstract: Faithful chromosome segregation at each cell division is essential as the formation of cells with an abnormal number of chromosomes (aneuploid cells) can result in infertility, developmental defects or cancer. Aneuploidy occurs in approximately 20% of all conceptions, causing infertility and embryo death. Chromosomal disorders are the most common known cause of mental retardation, e.g. Downs syndrome, affecting 0,3% of all newborns. Meiosis is a highly specialized germ cell specific cell division that generates genetically diverse haploid gametes. The aim of this thesis was to study the functions of a set of structural and regulatory proteins that are associated with the meiotic chromosomes. Mammalian meiotic chromosomes at meiosis I are organised and supported by several protein structures including synaptonemal and cohesin complexes. The synaptonernal complex (SC), formed only in meiosis, promotes synapsis and recombination between the homologues. The SC is composed of two axial elements (AEs) and the central element (CE) connected by transverse filaments (TFs). The AEs are composed Of Sycp2 and Sycp3whereas the TFs are formed by Sycp1 The cohesin complexes are formed by Smc1