NGS Expert Blog

30 years of PCR in various applications has revolutionised molecular biology. But PCR also has its drawbacks. One of them is the amplification of AT- or GC-rich DNA fragments. Naturally, researchers are often interested in sequencing and studying genomes with high GC or high AT content, like S. aureus with a AT content of 67% or Streptomyces coelicolor with a GC content of 72%.
But more and more NGS kit providers try to circumvent PCR in the library prep. Ashley Yeager has summarised the current status of PCR-free library preps including a comprehensive overview of the pro’s and con’s of both methods (BioTechniques).

Summarising the findings from Mrs. Yeager there is no clear champion in sight:

Library prep by using PCR methods
+ well-known lab procedure & good sequencing efficiency
- difficulties in amplifying GC- / AT-rich regions -> sequencing is biased

PCR-free library prep
+ good sequence read distribution & a more even genome coverage
- huge amounts of starting material needed & sequencing reaction is less efficient

Read the complete article under BioTechniques.

The Genomics Virtual Lab (GVL) project – using the computing resources from the NeCTAR Research Cloud – is an Australian Government project conducted as part of the “Super Science” initiative. It is developing infrastructure supporting genome informatics research.

Their Galaxy-based NGS and HTS tutorials are really excellent:

• RNA-seq tutorial
• Variant detection tutorial
• Variant detection (advanced) tutorial
• Genome assembly tutorial

You will love the precise explanations, the hands-on demonstration and the additional material like screenshots and in-depth information!

Newts have an extraordinary ability to regenerate tissues. For example, they can re-grow fully functional limbs after amputation. In addition, regeneration of parts of the central nervous system, the heart, and the lens has been characterized, making them an excellent model organism for studying regenerative processes. However, because of their enormous genome size (10 times that of human), the molecular mechanisms behind this amazing regenerative process are largely unknown.

A research group at the Max Plank Institute recently published a de novo assembly of the transcriptome of the urodelian amphibian Notophthalmus viridescens (Looso M. et al. ). The researchers combined 454, Illumina, and Sanger sequencing data from both normalized and non-normalized cDNA libraries. The resulted transcriptome comprises over 120,000 non-redundant transcripts. Homology search using BLAST led to annotation of 38,000 transcripts. Importantly, they found 800 transcripts, whose protein-coding potential was validated by mass spectrometry, that show no similarity to any know transcripts or show similarity to urodele-specific EST sequences. Some of these transcripts belong to novel protein families.

It is an interesting hypothesis that some of those newt-specific proteins may provide mechanistic insights into regeneration processes unique to these animals. Their work will definitely be an important resource for subsequent studies in tissue regeneration and may benefit future research in regenerative medicine.

With today’s press release I am happy to announce that AROS Applied Biotechnolgy A/S  is now a member of the Eurofins group.

Here is a short introduction of our new colleagues from AROS:

• AROS was founded in the year 2000
• AROS started as a spin off of from the Aarhus University Hospital and was the first service provider for Affymetrix in Europe
• AROS is based in Denmark and provides a long term experience in sample preparation, microarray analysis and next generation sequencing (NGS)
• Nowadays AROS has a leading position in NGS service for pharmaceutical research
• AROS is an Illumina reference lab for next generation sequencing
• The main focus in NGS is RNA-Seq and exome sequencing that is accomplished with the exome designs of the leading provider in this area (Illumina TruSeq Exome Enrichment, NimbleGen EZ Capture & Agilent SureSelect)

“AROS is an excellent fit […] with our focus on high-quality next-generation sequencing […]” (Dr. Gilles Martin) and therefore I am confident that this new alliance will help us both in further expanding our experience level in NGS and to benefit from our complementary strength.

I am sure you will hear more about the activities from AROS on our blog and hope you join me in welcoming AROS as a member of Eurofins.

Opinions differ as to whether next generation sequencing is already mature enough to be a useful tool in diagnostic routine.

Below you can find an interview of the cardiologists from the university of Heidelberg about their studies to integrate next generation sequencing into a diagnostic tool. Therefore they do collaborate with Siemens to receive best possible results that can be used by the doctors in the same way as current reports from other technologies.

Dear all,

Here is my second summary from 4th NGS Congress at London Heathrow end of 2012. It will bring to you some (hopefully) interesting new facts about sequencing with PacBio RS - the second long read technology present in the actual markets and also the only system delivering reads even longer than 10,000 bp…

Kevin Corcoran, Senior Vice President at Pacific Biosciences held an interesting and very nice talk about the most recent developments for the PacBio RS system. He also showed some nice detailed road maps about future aims and plans. One important thing actual to be mentioned is the launch of the new “XL Chemistry” – while still “C2 Chemistry” may be used as well. The other very interesting story is about “Stage Start” a new feature enabling a parallel start of all sequencing detection similar to the well-known “hot start” technology for PCR. Such detection of sequences better will start from a defined position for most of the libraries than starting from somewhere in the middle. Last but not least, I’m very keen to learn how the future “Photo Protected DNA Polymerases” may further develop – an idea being really very, very next-next-generation…

First of all I can summarize that applying “XL Chemistry” looks really interesting and this being true also in terms of Eurofins MWG Operon de novo sequencing and assembly focus.  This new feature of the PacBio RS machine may also open some new doors to other types of applications, while in general the need for extrem high data coverages may be reduced in parallel.

Currently “C2 Chemistry” is on the machine and running a 90 min video may deliver you about 20-50,000 reads and data outputs of 30-50 Mb – of course higher yields may be possible for “ideal” DNA samples. The average read length is about 3,000 bp (!), while the 95% percentile is about 8,000bp. With the new ”XL Chemistry” we got an average yield of about 40,000 reads per SMRT cell with an average read length of about 4,000bp (+30%). Overall, we are very pleased with these first results, especially since we see some good potential to further increase data yields using the new software pipeline started in parallel (Hierarchical Genome Assembly Process and Quiver).

— See picture 1: —

It is also important to mention two different ways of “How-to-deal” with the XL Chemistry. 1) ”XL chemistry for Polymerase binding”, but “C2 chemistry for sequencing”. This allows for longer reads at the same quality (currently we still do have a single error rate of 10% to 20 %, average maybe 15%). 2) “XL chemistry for Polymerase binding” AND ”XL chemistry for sequencing”. Such one can yield even longer reads, but unfortunately the error rate will also increase by a few %. Therefore this method is being recommended especially for de novo assembly or finishing genomes.

— See picture 2: —

Finally one real “next-next-gen” highlight was the presentation of a development at Pacific Biosciences scoping with the idea to protect the polymerase enzyme from being killed by the energy of the laser. A picture shows how this should work in principle - by setting in place a laser-light protecting sun-blocker - this story was really fascinating for me and I hope to see in future more than the very promising first data results …

— See picture 3: —

So over all Pacific BioSciences keeps also moving very fast in year 2013 and it will be very nice to see and learn how all these additional improvements and new features may  improve the overall data results of this fascinating very long read technology offering today real single reads longer than 10,000 bp.

Cheers now and see you on our next BLOG,
Axel

At the end of August, Mr. Hosono, the Japanese minister for the environment, announced, that the ministry aims to perform whole genome sequencing (WGS) of people who live around the disabled “Fukushima Daiichi Nuclear Power Station”. He said that the WGS project will not be able to relieve concerns immediately, but it will make an important provision for the future. According to Mr. Hosono the main target group for WGS will be children.

These genomic analyses face many problems including the aspect of experiments with humans, maintaining confidentiality, discovery of information according to need, and others. This story reminds me once more that NGS technologies start to have social impacts.

Recently, we have reported on the Studies of the Broad Institute, showing that the PacBio RS system was able to outdo MiSeq sequencing regarding validation of SNP analysis. Now Pacific Biosciences have taken another important step to further improve their product.

Pacific Biosciences have now launched a new Sample Loading Device for the PacBio RS, called MagBead Station.  As  Michael Hunkapiller, Ph.D. President and Chief Executive Officer of Pacific Biosciences told in their press release, they expect that with the new device, customers will  “be able to generate 10 kilobase-sized libraries using as little as one microgram of sample, a five to 10-fold improvement from where we were just a few months ago”. Also, because the new process is more robust, they expect that sequencing results will have higher overall consistency, allowing to run experiments also on challenging samples.

First experiences of early-access-customers seem to underline these expections:

As Patrick Hurban of Expression Analysis told InSequence, the new loading device allowed them to recover sequences also for “difficult” samples: “we’re much more confident on a sample-by-sample basis that we will be able to get good sequence”, he said. Also, they could confirm that the amount of library that needs to be loaded is now significantly lower. The new loading process also seems to favor longer DNA fragments over shorter ones, excluding short contaminating DNA fragments. This results in a greater percentage of long reads in a run. Also, the loading process now seems to work as efficiently for the large insert libraries as it does for the smaller insert libraries.

With the new loading device, about 50-60 % of the ZMWs are now active after loading. This is a great improvement compared to 30-45 % of active ZMWs before the upgrade.

When PacBio started on the market, I was impressed by the sophisticated new technology. However, the results of the first projects were rather disappointing. The new loading device now seems to greatly improve the sample loading step. However, the high error rates still remain a challenge, with about 15% for the time being. Pac Bio will need to solve those issues if they want to be successful on the market in the long run. However, it seems that by and by, PacBio is overcoming  its “childhood diseases”.

Six floors for Next Generation Sequencing in the middle of Manhatten – this is going to be exiting. Listen to the interview from Bio-IT World with Nancy Kelly, founding executive director of the New York Genome Center.

Just some days ago we discussed the dynamics in NGS and here we are with some news. Life Technologies Corporation announced that the new software v3.0 for the IonTorrent PGM consistently delivers 99.9% consensus accuracy for both short and long homopolymer regions and increases the frequency of correctly called insertions, deletions and homopolymer sequences by two-fold (Press Release LIFE).

In addition to the read accuracy also the read length increased with the launch of the new kit to 400 bp. The aim of the company is to improve their system further for microbial applications (PR LIFE).

But not only improvements in bacterial identification is on the priority list for LIFE’s RnD team but also more innovations in the area of diagnostics. A new AmpliSeq(TM) sample ID panel will increase the confidence during data analysis and a new kit is soon to be launched (PR LIFE).

I think from a customer’s perspective it is a good idea to further improve the technology in several areas since there could be some cross-linking innovations. But it also bears the risk that some competitors, focussing on a specific application, will adapt their system more quickly. But of course these are only speculations. So what is your opinion?