Characterization of Chromosome Ends in the Filamentous Fungus Neurospora crassa

Telomeres and subtelomere regions have vital roles in cellular homeostasis and call facilitate niche adaptation. However, information oil telomere/subtelomere structure is still limited to a small number of organisms. Prior to initiation of this project, the Neurospora crassa genome assembly contained only 3 of the 14 telomeres. The missing telomeres were identified through bioinformatic mining of raw sequence data front the genome project and from clones in new cosmid and plasmid libraries. Their chromosomal locations were assigned oil the basis of paired-end read information and/or by RFLP mapping. One telomere is attached to the ribosomal repeat array. The remaining chromosome ends have atypical structures in that they lack distinct subtelomere domains or other sequence features that are associated with telomeres in other organisms. Many of the chromosome ends terminate in highly AT-rich sequences that appear to be products of repeat-induced point. mutation, although most are not currently repeated Se(sequences. Several chromosome terminin in the standard Oak Ridge wild-type strain were compared to their counterparts in all exotic wild type, Mauriceville. This revealed that the sequences immediately adjacent. to the telomeres are usually genome specific. Finally, despite the absence of many features typically found in the telemere regions of other organisms, the Neurospora chromosome termini still retain the dynamic nature that is characteristic of chromosome ends.