Today is DNA Day, and we’re taking the opportunity to support the humane treatment of DNA. After all these years of harshly shearing these molecules and fragmenting them down to just a few hundred bases, can’t we agree that there are nicer ways to treat them? (Yeah, we know that for some applications, you really do need teeny tiny pieces of DNA. We get it.)
For many applications — particularly long-read sequencing and long-range technologies such as optical mapping — it’s actually better to leave DNA as intact as possible. Just a little gentle cleaving, and you wind up with extremely long DNA fragments that produce optimal results. By preserving these molecules as much as possible, we can detect large structural variants, phase distant SNPs, accurately count copy numbers, and much more.
Large input DNA is responsible for major advances in genomics, such as the most contiguous assemblies yet for humans and other mammals. These reference-grade assemblies have been tremendously useful for filling in blanks left by previous sequencing attempts using short reads, allowing scientists to discover new genomic elements — including entire genes — that had been missed with other approaches.
High molecular weight libraries are also being used for newer interrogations of the regions of DNA that touch when the molecule is folded in the nucleus. After decades of only studying DNA in linear order, we’re getting amazing new insights from approaches like proximity ligation mapping. Discoveries like this tell us that DNA is probably harboring even more fascinating secrets, and we just need to find the right ways of asking questions.
And perhaps it all begins with better treatment of your DNA molecules! We hope you’re celebrating DNA Day today. From all of us at Sage, happy HMW DNA to you!
Last week’s annual meeting of the American Association for Cancer Research offered some great perspectives on innovation in oncology, both in the clinic and in academic labs.
We were particularly impressed by former Vice President Joe Biden’s update on the Cancer Moonshot initiative, which he characterized as a bright spot in bringing people together and pushing research forward. For example, Amazon offered to host some extremely large cancer databases, and in less than a year the information has been accessed 80 million times. Biden’s optimism about the effort turned to frustration with the new administration’s proposed cuts to research funding. He said the “Draconian cuts” would be a massive setback, though he expressed doubt that the proposed budget would pass Congress.
The association also gave out some prestigious awards, such as the AACR Award for Lifetime Achievement in Cancer Research to Mina Bissell. The Lawrence Berkeley National Laboratory scientist has been a pioneer in breast cancer research, delivering some of the earliest findings that cells lose their native expression patterns when cultured in different conditions (she also discovered that cells can “remember” their original profile when native microenvironment conditions are restored). As strong supporters of improved sample prep, we see Bissell as a champion for the kind of reproducible research practices that are essential to life science.
One of the most exciting technical advances came from a team at Johns Hopkins University, where scientists developed an error-correction method for NGS results from liquid biopsies targeting cell-free DNA. The approach boosts accuracy with ultra high-coverage sequencing. We’re excited about this work because it dovetails nicely with our new SageHLS instrument for purification of extremely large DNA molecules, such as entire genes associated with cancer. In beta tests, scientists have successfully purified the BRCA1 and BRCA2 genes using the platform with the CATCH method (Cas9-assisted targeting of chromosome segments).
We congratulate all the scientists who presented at AACR and made such a strong showing for the terrific recent advances in cancer research!
Chris Boles is Chief Scientific Officer of Sage Science, where he’s been helping the R&D team develop the new SageHLS (that’s short for HMW Library System), a platform designed to rapidly purify high molecular weight DNA directly from samples. We caught up with him to learn more about it.
Q: What’s so important about having high molecular weight DNA?
A: Working with extremely long DNA has become a lost art in the life science community. Back in the early days of the Human Genome Project, every lab had to think about this as they worked with recombinant BACs, fosmids, Southern blots, and so on. But beginning with PCR in the early ’90s and continuing with short-read NGS since the early 2000s, life scientists have had the tools to do amazing things without the need for HMW DNA. Now, researchers are tackling repetitive genomic regions, long-range structural variation, and long-range phasing, and the need for high-quality, high molecular weight DNA has resurfaced.
Q: What are some of the long-range technologies that the SageHLS platform could be used with?
A: Really any system that requires DNA that is hundreds of kilobases to megabases in size. These include long-read sequencing platforms like PacBio or Oxford Nanopore, optical mapping technologies such as those from Bionano Genomics or Genomic Vision, and other long-range linkage analysis methods like the ones from 10x Genomics or Dovetail Genomics. The SageHLS can improve input DNA quality and size for all of these systems.
Q: What kind of sample prep is required before loading the SageHLS?
A: In general, very little. We have focused initially on sample types that 1) are important for biomedical research, and 2) work well in SageHLS. These include white blood cells from whole blood, tissue culture cells, or bacterial cultures. For these sample types, only a few brief centrifugation steps are necessary to wash the cells and resuspend them in an isotonic gel loading buffer. The cassette reagents do the hard work of lysis and purification without mixing or shearing the HMW DNA.
Q: How does the new system work?
A: Users load their samples into a gel. Then the platform automatically performs cell lysis and contaminant removal. This happens very quickly, leaving megabase-sized DNA stuck in the agarose. Next, the DNA is lightly cleaved with a non-specific nuclease and retrieved from the gel through an automated elution process.
Q: What kind of results have you gotten from the SageHLS internally?
A: From mammalian WBC and tissue culture cells, we routinely obtain DNA ranging in size from 200 kilobases to 2 megabases. From input cell loads containing about 10 ug of DNA (about 1.5 million human cells), we recover 1 to 3 ug of DNA of this size, which is sufficient for even DNA-hungry applications like optical mapping.
Q: You’re already working on new uses for the SageHLS platform. Can you give us a sneak peek?
A: There are several improvements that should happen fairly quickly after launch. Next up is a process we call HLS-CATCH, which uses CRISPR/Cas9 technology to excise and isolate a genomic fragment of interest in a targeted fashion. We’re also working on several methods for making NGS libraries directly in the HLS cassettes so that we can integrate DNA extraction directly with NGS library construction. It will be interesting to learn from customers what else they want to do with the system.
The Sage Science team had a blast at this year’s AGBT conference in Hollywood, Fla. We thoroughly enjoyed the parties, the beach, and especially the excellent talks. We’d like to thank all of the attendees who made their way to our suite to check out the SageHLS instrument for extracting and purifying high molecular weight (HMW) DNA, which is now commercially available.
Following a trend that’s been gaining ground in the last few years, many AGBT talks and posters focused on technologies that require HMW DNA. There was lots of data from users of Oxford Nanopore and PacBio sequencers, long-range methods such as 10x Genomics, and scaffolding tools like Bionano Genomics or Dovetail Genomics. All of these platforms need much longer DNA than scientists ever had to produce for short-read sequencers, kicking off a new era of enhanced sample prep for working with incredibly large genetic fragments.
That’s why we developed the new SageHLS platform, which can extract DNA as long as 2 Mb directly from a sample. Chris Mason from Weill Cornell, whose lab worked with a beta version of the new instrument, gave a presentation at AGBT and spoke about his experience with it. (For the record, we would have loved his fast-paced, entertaining talk about sequencing in space even without the SageHLS shout-out.) Mason used the instrument with the CATCH method — that’s short for Cas9-assisted targeting of chromosome segments, from this Nature Communications paper — and said the approach will be important for things like measuring telomere length with great accuracy.
For more information, check out our AGBT poster with results from the SageHLS instrument.
The Sage Science team is casting off the shackles of winter and gearing up for a trip to sunny Florida for the annual Advances in Genome Biology and Technology meeting. We look forward to this conference each year — it’s a great opportunity to catch up with friends while we learn about the latest technology innovations in the field.
AGBT has a long tradition of technology talks and posters, and this year’s meeting should continue the trend. We’re delighted to see two plenary sessions as well as a concurrent session focused on technology, giving us ample opportunity to discover promising new tools and biological insights.
A major theme in recent AGBT meetings, and one that’s apparent again this year, is a focus on alternatives to short-read sequencing. While NGS platforms offer a great deal of useful information, there’s a growing awareness that they miss important genomic elements that are too long to be spanned by 300-base reads. We’ve seen loads of interest for long-range technologies that can extend information from NGS systems, genome mapping approaches, and of course single-molecule, long-read sequencing platforms.
With that in mind, we’ve developed our newest sample prep system to help scientists generate the high-quality, high molecular weight DNA required as input for these long-range methods. The SageHLS (that’s short for HMW Library System) will be on display in our AGBT suite #3281 for anyone who wants to check it out and learn how it can be used to purify DNA from 50 Kb to 2 Mb. We look forward to seeing you in Florida!