engleski

Long-range organisation of holocentromeres

The centromere is a specific region of every eukaryotic chromosome essential for efficient segregation of chromosomes during cellular division. The main role of the centromere is organization of kinetochore protein attachment to the chromosomes as well as the kinetochore attachment to the spindle apparatus. Regarding centromere architecture, the majority of species have monocentric chromosomes characterized by a single regional centromere. In contrast, holocentric chromosomes, with the centromere function distributed at multiple sites along the chromosome length, were observed in some nematode, insect, and plant species. In general, centromere is determined by a centromere variant of histone protein (CenH3) and centromeric DNA. Recent ChIP-seq analyses in nematode Meloidogyna incognita revealed cluster-like organization of CenH3 domains in holocentromere. The centromeric clusters are composed of divergent tandem repeats which share a completely conserved 19 bp-long box [1]. In order to disclose the long-range organisation of M. incognita holocentromere, we have performed whole genome sequencing with the Pacific Biosystems High-Fidelity (HiFi) technology [2]. We have obtained 535, 322 reads containing 8, 700, 000 base pairs (50x coverage of the genome). The reads were assembled into contigs using HiCanu [3]. In order to disclose the patterns of sequences that lie in-between centromeric clusters we performed extensive bioinformatics analyses and found that these large regions are highly conserved. Moreover, we found that the regions surrounding the centromeric tandem repeats represent dispersed repetitive sequences highly similar in size and composition. In conclusion, consistent with the polycentromere model, M. incognita centromere is organized in a form of short tandem arrays embedded in environment composed of dispersed non-centromeric repeats.

holocentromere ; nematode ; bionformatics

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