Troubleshooting DNA Sequences: Guidelines and Suggestions .
Transcript of Troubleshooting DNA Sequences: Guidelines and Suggestions .
Troubleshooting DNA Sequences:
Guidelines and Suggestions
http://vermontcancer.org/dna
Biodesktop Workshops:
• Scheduled: 300 HSRF– Jan. 29th at 10-11AM (Friday)
• Rama Kocherlakota– Basics of submitting orders– Retrieving data– Creating a team to share data– Opportunity to provide input
SESSION OUTLINE:• Guidelines: Generic Set up and Profiles
• Impact of Template and primer ratio???
• Suggestions for different sample types and Sequence Context: Chemistry, Profile, Additives– Sample types: PCR, Plasmid, BAC, Cosmid, RNAi construct, Bisulfite
treated gDNA, gDNA– Sequence Context: GC Rich, Homopolymeric Runs, Repetitive Sequence
• Instrument and Processing Anomolies:
• Retreiving data off the biodesktop: How, What…..
• Sample Purification prior to Sequencing
• Troubleshooting Resources
Sequencing Instruments: AB 3100-Avant, 3130XL both
Capillary Based
• Advantages– Higher throughput– Can reinject samples– Higher separation
efficiency– Better resolution– No Plates!
• Disadvantages– Sensitive to charged
ions– Sensitive to
microparticulates or bubbles
Required Template Concentrations:
Template Type Required templateconcentration
Totalamount in Rxn
Double strandplasmid
50 ng/uL 375 ng
Large plasmid (>7Kb) 50 ng/uL 525 ng
Single strandplasmid
25 ng/uL 75 ng
PCR 0-200 bp
5 ng/uL 10 ng
200-500 bp 5 ng/uL 20 ng
500-1000 bp 5 ng/uL 40 ng
>1000 bp 5 ng/uL 45 ng
PCR (Exo-Sap) N/A 1-2 ul
BAC and gDNA 1ug/uL 1-2 ug
*This amount of template is needed for each primed sequencing reaction
Normal Conditions: Default Profile
AutoSeq1 Profile
• 96° 1min
• 96 ° 10 sec• 50 ° 5 sec 25x• 60 ° 4 min
C.S. Rxn conditions
DS plasmid-375 ng
PCR (5ng/100bp Product)
3.2 pmol Primer
1/8 dilution BDv3.1
Primer Titration: Plasmid
Template Titration: Plasmid
Template Titration: PCR ProductPCR Product Size=~720BP
70 ng added
30ng added
Template Concentration: It Can MatterSubmitting template at the
incorrect concentration
Submitted as:50 ng/ulWas:350 ng/ul
Diluted to:50 ng/ul
Sample Type: RNAi construct, BAC, Cosmid, gDNA, Bisulfite treated DNA
Different Sample Types May Require Different Template or primer
concentration, Chemistry, Profile, and additives
Sequencing RNAi Constructs:Auto Seq1 Profile, Chemistry (Default)
RNAi Construct:GC Rich Profile, 5% DMSO
RNAi Construct:Modified RXN Set-up, RNAi Profile
660 ng Template10 pMol Primer8ul BDT v.3.110% Betaine(Q Buffer)
98 c 5min
96 c 15 sec50 c 10 sec60 c 4 min
50X
RNAi Construct: testing to reduce costsAutoSeq1 (Default):
RNAi Construct:Default Chemistry, RNAi Profile:
RNAi Construct:BDTv3.1/dGTP Chemistry, GC RichProfile:
RNAi Construct:BDTv3.1/dGTP Chemistry, RNAi Profile:
RNAi Construct: LOR scores for three different approaches
AutoSeq1
GC Rich
RNAi
ThermalProfiles:
BAC’s, Cosmid’s, Genomic:
BAC DSRG Profile
• 96° 5min
• 96 ° 30 sec• 50 ° 20sec• 60 ° 4 min
C.S. Rxn conditions
DNA- 1ug
10 pmol Primer
straight BDv3.1
50X
BAC’s: Default set-up and AutoSeq1
BAC’s: Modified Set-up, BAC profile
BAC Sequencing: LOR scores for two different approaches
gDNA Sequencing: Not as easy as you may think!
1.3 Kb productgDNA = 500 ngFWD Primer: 500nMREV Primer: 100nM125 uM dNTP’sStraight Big Dye
Cycling:950C 30s
950C 15s500C 15 s 35-45600C 4 min
PCR and Cycle Sequencing combined:
Murphy, K., et.al., Clinical Chemistry 51:1 35-39 (2005)
Bisulfite Sequencing:Sequencing methylated gDNA
Default Set-up and Profile
Bisulfite Sequencing: Suggested Set-up and profile
BiSulSeq Profile: “ Vish”
• 95° 1min
• 96 ° 10 sec• 52 ° 10sec 30x• 60 ° 4 min
C.S. Rxn conditions
PCR 5ng/100 bp
3.2 pmol Primer
1/8 dilution BDv3.1
“Vish II”: 96c 1min, 25X of 96c 20s,50c 5s, 54c 4minChemistry BDT V1.1
Bisulfite Sequencing: Default Set-up and BiSulSeq Profile
“Vish Profile”
Cosmids:
BAC DSRG Profile
• 96° 5min
• 96 ° 30 sec• 50 ° 20sec• 60 ° 4 min
C.S. Rxn conditions
DNA- 1ug
10 pmol Primer
straight BDv3.1
50x
Sequence Context Constraints:
GC rich, Homoploymeric runs, Repetitive sequence (STR)
Run of G’s:Default Set-up and Profile (AutoSeq1)
Run of G’s:dGTP Chemistry, AutoSeq1 profile
GC Rich Template:Generic Set up, AutoSeq1 Profile
GC Rich Template:BDTv3.1/dGTP (3:1), GC Rich profile
Previous stop point
Repetititve Sequence: Template C Defaults
Stops
Repetititve Sequence: Template C BDT v3.1/dGTP (3:1) mix, GC Rich Profile
Repetititve Sequence: Template D BDT v3.1/dGTP (3:1) mix, GC Rich Profile
Lunatic!!
Repetititve Sequence: Template E BDT v3.1/dGTP (3:1) mix, GC Rich Profile
Repetititve Sequence: Template A BDT v3.1/dGTP (3:1) mix, GC Rich Profile
Not always a fix!
Repetititve Sequence: Template A BDT v1.1, Default Profile
Homopolymeric runs:
“Throw the Book”
Primer Location
Retrieving Data:• An email is sent notifying the user that data is ready.
The staff of the DNA facility has the ability to edit this message to include specific remarks about how your samples ran, so please look at this message!
• The format for the sequence data files: Well Location_template-primer, (A01_pGem-M13For).
In these messages, we often refer to your individual samples by the injection number (A01), not the full name.
Instructions
*
*
What is Phred?
• Basecaller (used by genome centers)• Provides quality score for each base • Generates two files
Need to look at the Chromatogram!! (.AB1 File)
Trace viewers:PC: Mac:
Chromas EditView Finch TV Finch TV
Instrument and Processing Related Anomolies:
AND Email notifications
Bad Injection message:One of your samples had a bad injection. It is being re-injected at no
charge and we will send the data to you when it is ready.
Example:
Causes SolutionsGenerally, this is due to incomplete excess dye clean up of the cycle sequence reaction.
If the DNA facility cleaned the reaction, we consider this an error on our part and we will repeat the cycle sequence reaction and the sequence run for free.If the clean up was done by the user, we charge for the sample, but we will be happy to help with troubleshooting if the problem continues.
Dye blobs can sometimes occur when the cycle sequence reaction was a very low signal.
Optimize the template and primer for a successful cycle sequence reaction.
Loss of Resolution: In the middle
Reinjection successful!
Timing of Reinjections:
C fluorophore degrading
Reinjections on Monday from a Friday run may need to be set-up again
Dye-Blob message:• Your sequence sample, injection number (A01) has a dye leak which interferes with the basecalling in
that region. These cannot be corrected with a reinjection of the sample. It is our policy to repeat the cycle sequence reaction and sequence run once for free to eliminate this problem. If the dye leak was not a problem for you we will not repeat the sample. If it is a problem, resubmit the sample on the BioDesktop and put “re-run for free due to a dye leak” in the comment section of the order form. Please make sure that we have enough template DNA to repeat the reaction.
Example:
Causes Solutions
Generally, this is due to incomplete excess dye clean up of the cycle sequence reaction.
If the DNA facility cleaned the reaction, we consider this an error on our part and we will repeat the cycle sequence reaction and the sequence run for free.If the clean up was done by the user, we charge for the sample, but we will be happy to help with troubleshooting if the problem continues.
Dye blobs can sometimes occur when the cycle sequence reaction was a very low signal.
Optimize the template and primer for a successful cycle sequence reaction.
Spike message:One of your samples had spikes. It is being re-injected at no charge
and we will send the data to you when it is ready.
Causes Solutions
This is generally believed to be a sequencing instrument artifact. It is caused when a small bubble or crystals in the polymer migrate through the capillary with the sample and cause a sharp peak of multicolors. These can mask the true data peaks.
Re-injection of the sample usually gets rid on the spike.
Example:
Template Purification:
What’s best for sample or sequence type
Impact of Purification Method on Sequence Quality: Gel Purified
Run 1
Run 2
PCR Product size= ~630BP
Impact of Purification Method on Sequence Quality: Enzyme Treated
Same sample: Exo1/SAP treated PCR Product
DNA Sequencing Troubleshooting Resources:
• VCC DNA Analysis Websitewww.vermontcancer.org/dna
• DSRG Sequencing Troubleshooting Web Resource www.abrf.org/index.cfm/stwr.home
• DNA Sequencing Resource: Nucleics http://www.nucleics.com/nucleics-dna-sequencing-site.html
• http://biowww.net/
• DNA Sequencing: Optimizing the Process and Analysis
• DNA Facility Staff
Conclusions: Successful Sequencing is Dependent on:
• Template Quality
• Template Quantity
• Upfront Identification of Sample Type
• Upfront identification of Sequence context constraints
• Read Email messages sent by facility staff
Acknowledgements:
VCC DNA Analysis Facility:
MaryLou Shane
Meghan Brown
Scott Tighe
To all users of the VCCDNA Analysis Facility
Special thanks to all the users who have providedtemplate for research studies and those who shared their data for this presentation
VersaDoc 4000MP:Keep in Mind these very important facts about X-Ray film vs CCD imagers:
1] X-Ray film exposures are not quantitative although many people believe they are, it is not the case. The dynamic range is so narrow, and is non-linear that to assume quantitative results can be very misleading. When a band is black, it is black! Please make note of the Gamma curve for X-Ray film.
2] The VersaDoc has a CCD imager in it. CCD’s are unique as they are true photon counters. The higher the bits, the higher the dynamic linear range. The VersaDoc uses a 16 bit CCD! That is what they were originally designed for, and that is why they are quantitative. Many reviewers also know this as well.3] Some people believe that CCD’s are not as sensitive as X-Ray film. This also is not the case. If you add the substrate to the blot and image immediately, the result is essentially the same. The difference people notice often comes from a time delay to walk to the imagers after you add substrate. That is why we suggest adding your substrate in the lab that the VersaDoc Imager is located in.