Heterochromatin integrity affects chromosome reorganization after centromere dysfunction

The centromere is essential for the inheritance of genetic information on eukaryotic chromosomes. Epigenetic regulation of centromere identity has been implicated in genome stability, karyotype evolution and speciation. However, little is known regarding the manner in which centromere dysfunction affects the chromosomal architectures. Here we show that in the fission yeast Schizosaccharomyces pombe, the conditional deletion of the centromere produces survivors that carry either neocentromere-acquired chromosome at the sub-telomeric region or acentric chromosome rescued by inter-telomere fusion with other chromosome. The ratio of neocentromere formation to telomere fusion is considerably decreased by inactivation of genes involved in RNA interference (RNAi)-dependent heterochromatin formation. By affecting the modes of chromosomal reorganization, the genomic distribution of heterochromatin may influence the fate of karyotype evolution. Keywords: ChIP-chip Chromosomal distributions of Cnp1, Mis6-GFP, H3me2K9, Swi6, Mis12-GFP and Cnp3-GFP were examined by immunoprecipitating the chromatin using anti-Cnp1, anti-GFP, anti-H3me2K9 and anti-Swi6 antibodies from the fission yeast cells harboring functional centromere at either authentic or ectopic position in the chromosome I. Immunoprecipitated DNA and input DNA were amplified by LM-PCR and labeled with either Cy5 or Cy3 by random priming. Labeled DNA samples were mixed and hybridised onto commercially-distributed S. pombe oligo array from Agilent. Data processing was performed using Agilent scanner and softwares.