Long Read Genetic Sequencing Gives Insight Into Gorilla Genome

Long read genetic sequencing technology has been applied to the Western Lowland Gorilla, a level of quality now comparable to the human and mouse genomes. The new technique is a combination of Single Molecule, Real Time (SMRT) sequencing technology, assembly tools Falcon and QUIVER and other techniques to produce longer sequence reads. This new and accurate sequenced genome has the potential to give us more insight into human disease and how our ancestors split from the other ape species.

Previous assembly of the gorilla genome was roughly 400,000 broken pieces of short stretches of sequence called "reads." The reads were originally pieced together with assembly technology that left numerous gaps at the sites of large sequence repeats. University of Washington professor of genome sciences and lead researcher Evan Eichler comments that, "Some assemblies can be like Swiss cheese, with a lot of missing biological information in the gaps." Essentially, bioinformatic technology is now advancing to the point of more sophisticated genome sequencing for all species. This research in particular completes the picture of overall genetic comparison among apes.

The new long read genome sequence for the gorilla was assembled from 1,800 fragments as opposed to the previous 400,000 fragmented genome. Average size of the fragments were a reported 800 times larger and approximately 90 percent of the gaps in the original were closed. Scientists found "tens of thousands" of new structural variants of introns and exons and dissimilarities in genes between humans and gorillas that code for: sensory perception, keratin production, insulin regulation, immunity, reproduction and cell signaling. Researchers also found that humans are closer to the gorilla in some ways more than the chimpanzee, for example ear shape and hearing perception.

Overall, longer read sequencing technology gives a greater insight into genetic variation. Genome sequencing being done on gorillas and other animals can contribute to medical research. While the long read sequencing is still extremely expensive ($80,000) further advances in technology and cost reduction is expected to allow the technique to be available in medical diagnosis in years to come.

Above, a zoo gorilla sits and observes his surroundings.

Credit: Alice C. Gray