Studies on nuclear architecture in the model grass Brachypodium distachyon and its close relatives

In large-genome eukaryotes, individual chromosomes occupy distinct three-dimensional areas known as chromosome territories (CTs). It is likely that relative positions of CTs in the nucleus correlates with the interactions between the genes on different chromosomes and in DNA repair processes. Epigenetic modification of histone proteins which influences chromatin condensation and transcriptional activity is another factor determining nuclear architecture, since the size and structure of individual CTs can depend on the transcriptional status of the genes it contains. In this work, we present the results of preliminary studies on different aspects of nuclear architecture in the model grass, Brachypodium distachyon and its close relatives. A chromosome painting approach was used to visualise the arrangement of CTs and associations between homo- and heterologous chromosomes. The distribution of centromeres and telomeres during mitotic and meiotic interphase were analysed using fluorescence in situ hybridisation revealing a correlation between the size of the nucleus and the occurrence of Rabl-like configurations in B. distachyon somatic cells. Moreover, immunolocalisation of methylated cytosine residues and epigenetically modified histones marking eu- and heterochromatic regions was used for investigating spatial distribution of transcriptionally active and inactive regions in interphase nuclei. This work was supported by the Polish Ministry of Science and Higher Education Grant N N303 570738. EB, NB and AB acknowledge scholarships from the UPGOW project co-financed by the European Social Fund.