New genome assembly using SMRT sequencing technology provides novel clues into evolutionary history of lowland gorilla

For the first time, an advanced sequencing technology has been developed that allows missing genes and missing forms of genetic variation to be discovered. The genome of the Western lowland gorilla has been sequenced and assembled using the novel approach.

The assembly has provided a new biological insight into the species, which is just second only to chimps in its evolutionary closeness to humans. Study’s lead researcher Evan Eichler from University of Washington said that earlier genome assemblies for the gorilla and other mammals have been incomplete and misleading.

In the current research work, the team has assessed DNA in a blood sample of a female Western lowland gorilla from Chicago’s Lincoln Park Zoo. They have used Single Molecule, Real-Time (SMRT) sequencing technology. The team has also included assembly tools called Falcon and QUIVER and other techniques to generate long sequence reads.

The researchers said that the long reads allowed them to cross most of the repeat regions of the gorilla genome. The team came up with a new gorilla genome assembly, which was larger and had fewer pieces.

Rather than 400,000 fragments, there are now 1,800 pieces. The average size of the genome fragment was 800 times larger with almost 90% of all gaps in the original assembly closed. The researchers noticed that the additional sequencing information has significantly improved gene annotation for the species of gorilla.

The team has also come to know about the thousands of protein- and peptide-coding segments and regulatory elements that were missed in the first genome assembly. Patterns of genetic variation with the gorilla genome can provide evidence of how disease, climate change and human activity can affect lowland gorilla populations.

“Sequencing technology and computational biology have now advanced to the stage where individual laboratories can generate high quality genomes of mammals. This capability has the promise to revolutionize our understanding of genome evolution and species biology”, affirmed Eichler and his team.

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