The enthusiastic feedback from early users is a testament to the value of long reads in genomic analysis and discovery. Early access projects have revealed the critical importance of the extended read lengths for a variety of applications including de novo sequencing and assembly of whole genomes, comprehensive transcriptome profiling, metagenomic characterization of environmental samples, and more. The long, accurate reads were found to be particularly powerful for resolving highly repetitive regions within complex genomes, resulting in significantly improved assemblies.
"We are thrilled with the performance of the GS FLX+ System in our laboratory," said Chris Wright, Assistant Director of the High-Throughput Sequencing and Genotyping Unit at the University of Illinois Urbana-Champaign. "Our customers are already benefiting from the long reads in a variety of genome sequencing and resequencing projects carried out during beta testing and early access. We are looking forward to the commercial release of the system and to having our two instruments running full time to meet the demand." Alvaro Hernandez, Director of the lab, added that a significant portion of their work involves de novo sequencing of genomes and transcriptomes from non-model species. "The very long reads of the GS FLX+ System allow for accurate assembly of genes and their splicing variants, which is still a challenge with short read technologies", he explained.
Researchers from Pennsylvania State University have already used the extra-long reads to better characterize genetic diversity within the critically endangered Tasmanian devil, a species which is threatened by a transmissible cancer known as Devil Facial Tumor Disease (DFTD). The study, published online this week in the Proceeding of National Academy of Sciences, used a combination of the new GS FLX+ System's long reads, GS FLX Titanium paired end reads and short read data to sequence and assemble the 3.2 billion base pair genomes of two Tasmanian devils, one with natural resistance to some DFTD strains, and the other who had contracted the disease in the wild(1).
"A defining part of this project was the ability to generate on the GS FLX+ System the long, accurate reads needed to develop a full understanding of the genetic makeup of the Tasmanian devil," explained Stephan Schuster, senior author and Professor of Biochemistry and Molecular Biology at Penn State University. "The longer stretches of DNA from "long reads" are critical to span repeat elements and build a comprehensive and accurate assembly of the genome for such a unique species." The comparative genome approach has been used to develop a theoretical model to predict which Tasmanian devils would need to be kept in captivity to maximize chances of preserving enough genetic diversity for the species to survive. This approach may be extended to other endangered species.
The new GS FLX+ System is available as a new instrument or as an on-site upgrade to an existing GS FLX Instrument and features a redesigned reagent compartment to accommodate the larger reagent volume of the new GS FLX Titanium Sequencing Kit XL+. An increase in the number of sequencing flow cycles, along with chemistry and software optimization, enable read lengths up to 1,000 bp (700 bp mode). The instrument is also fully backward-compatible with the existing GS FLX Titanium Sequencing Kit XLR70.
"Our team has worked tirelessly to drive forward the performance of our system and achieve true Sanger-like read lengths and accuracy," said Christopher McLeod, President and CEO of 454 Life Sciences. "The response from our early users and the life science community as a whole has been overwhelmingly positive. We look forward to rolling out this upgrade to our user base worldwide and continuing to demonstrate the value of long read sequencing."
For more information on the new GS FLX+ System, visit www.454.com.
(1) Miller W et al. Genetic diversity and population structure of the endangered marsupial Sarcophilus harrissi (Tasmanian devil). (2011) PNAS ePub.
For life science research only. Not for use in diagnostic procedures.
454, 454 LIFE SCIENCES, 454 SEQUENCING, GS FLX and GS FLX TITANIUM are trademarks of Roche.
All other product names and trademarks are the property of their respective owners.