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Pre-genomic era: finding your own clones. Imagine initial cDNA or PCR fragment probe hybridizes to clones 3, 9, 16, 22. GENOME. 1. 2. 3. 23. CHROMOSOMES. YACs. or. BACs (map). Plasmid Sub-clones. Gridded (arrayed/ordered) library. 18,000 BACs for Drosophila. 300,000 BACs for Humans.
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Imagine initial cDNA or PCR fragment probe hybridizes to clones 3, 9, 16, 22
GENOME 1 2 3 23 CHROMOSOMES YACs or BACs (map) Plasmid Sub-clones
18,000 BACs for Drosophila 300,000 BACs for Humans
STS- Sequence Tagged Site Mapping Probe or PCR product STS
Sub-clone into smaller segments and map Or use primer walking- NOT EFFICIENT Instead use shotgun sequencing Plasmids Sequence >700nt from each end
Virtual DNA (sequence) Assembly
Shotgun Sequencing 2 or 3 libraries of Different size fragments
Mates: read-pairs 2kb library of clones 10kb library of clones
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GENOME 1 2 3 23 CHROMOSOMES YACs or BACs (map) Plasmid Sub-clones Don’t map Sequence ends Assemble sequence of BAC
Mates: read-pairs 2kb library of clones 10kb library of clones 150kb library of clones
Cosmids, YACs ordered C. Elegans 100Mb Drosophila 120Mb BACs ordered- STS mapping + fingerprinting Whole Genome shotgun Human 3, 200Mb BACs ordered- fingerprinting Whole Genome shotgun
1. 454 sequencing Amplify single DNA molecules on single beads Sequence each DNA/bead by stepwise Incorporation of A, G,C or T in mini-wells
bead Aqueous microsphere
BEAMing: PCR on beads compartmentalized in a water-oil emulsion. Millions of primers attached to each bead, Producing millions of copies of bead-attached Templates from one original template molecule Anneal primer for sequencing and load DNA polymerase and SSB after enriching For template-loaded beads
Attached oligomers were pre-labeld red or green, then mixed and emulsified. See single beads in aqueous microspheres in oil.
BEAMing = beads, amplification, emulsion, magnetics = cloning DNA molecules via PCR on beads No template or bead Aqueous microspheres Had one template Had another template No template No bead Remove oil
Big beads- Template, primer, DNA polymerase Small beads- ATP sulfurylase, Luciferase Solution- One dNTP Luciferin, APS
Destroy old nucleoside triphosphate substrate before adding new one APS = adenosine phosphosulfate
2. Solexa/Illumina sequencing Intelligent Bio-Systems (Jue, Turro… Columbia) Amplification in situ on glass surface of flow cell (PCR that keeps different DNAs separate- “micro-cloning” Sequencing with reversible fluorescent terminator dNTPs (one nucleotide at a time)
3. Applied Biosystems SOLiD sequencing Shendure, Church et al. Webinar: http://appliedbiosystems.cnpg.com/lsca/webinar/rhodes/chemistry/20070618/ Shendure, J., Porreca, G.J., Reppas, N.B., Lin, X., McCutcheon, J.P., Rosenbaum, A.M., Wang, M.D., Zhang, K., Mitra, R.D., and Church, G.M. 2005. Accurate multiplex polony sequencing of an evolved bacterial genome. Science 309: 1728-1732. Polony (polymerase colony) by emulsion PCR or similar on beads (BEAMing) Attach beads to glass slide for sequencing Sequence by ligation!
AA CC GG TT AT TA CG GC