The Genomics and Informatics Facilities Core located in 68-322 recently acquired a new Pacific Biosciences Sequel sequencer (Figure 1). This new sequencer compliments the already existing Illumina instrumentation in the core by focusing on long read and high quality consensus methodologies. The Sequel uses advanced optics to visualize sequencing reactions on single molecules in real time. This real time visualization allows for very long reads (10s of kilobases) as well as the ability to perform rolling circle sequencing, allowing for repeated measurements of the same position, resulting in extremely high accuracy. The ability to measure not only the incorporated base, but the length of time required for incorporation also allows the instrument to begin to examine epigenetic modifications.
Several features of the Sequel are of particular interest to the environmental health community. First, long read sequencing allows the possibility of phasing mutations or crossing chromosomal rearrangements that may have been caused by environmental damage. Additionally, circular consensus sequencing allows for high precision with error rates below one in a million that may be sufficient to characterize mutation signatures. This same consensus data can also be used to detect epigenetic modifications to the DNA – inherited changes to the sequence through the addition of covalent modifications that can be altered by the environment.
The purchase of the sequencer was a collaborative effort and could not be done without the generous support of CEHS, as well as the MIT Vice President of Research, the Simons Foundation, the departments of Biological Engineering and Chemistry, and professors John Essigmann, Mary Gehring, Chris Burge and Mike Birnbaum.
For additional information on the Pacific Biosciences Sequel, contact Dr. Stuart Levine (slevine@mit.edu)