I continue to watch the YouTube “Assembly” playlist from the Oxford Nanopore Technologies (ONT) channel. Tonight, I watched session #8! Ian Henderson from the University of Cambridge in the UK presented at the Nanopore Community Meeting 2021. The session was titled “Assembling the centromeres – the ‘black holes’ of the genome.” Henderson said the centromeres are the regions of the chromosome that assemble the complex that binds to the microtubules. The ‘centromere paradox’ is that they are some of the fastest evolving parts of the genome yet have a conserved function. The centromeres have been studied in several model organisms. Henderson has studied the centromere sequences in the plant Arabidopsis thaliana. Due to their repetitive sequences, these areas of the chromosome have been difficult to sequence. Using ONT and PacBio HiFi reads, the genome of the plant was improved. These genome assemblies revealed the architecture of the centromeres. There are highly repetitive arrays of repeats. The centromeres in the Arabidopsis genome have higher-order repetitive sequences than those found in the human genome. The centromeres in the plant are also invaded by ATHILA retrotransposons. The Nanopore data has provided insights into the Arabidopsis epigenome using Deepsignal-plant. Henderson and the team will continue working to learn about the structure of Arabidopsis centromeres and about the forces of selection connected to these fast-evolving regions of the genome.
