Complexity management of genomic DNA
View Patent ↗The presently claimed invention provides for novel methods and kits for reducing the complexity of a nucleic acid sample by providing non-gel based methods for size fractionation. In a preferred embodiment, size fractionation can be accomplished by varying conditions or reagents of a PCR reaction to amplify fragments of specific size ranges. The invention further provides for analysis of the above sample by hybridization to an array, which may be specifically designed to interrogate the desired fragments for particular characteristics, such as, for example, the presence or absence of a polymorphism.
1. A method of reducing the complexity of a first nucleic acid sample to produce a second nucleic acid sample comprising:
fragmenting a first nucleic acid sample to produce double-stranded fragments;
ligating one or more adaptors to the double-stranded fragments;
digesting the adaptor ligated double-stranded fragments with an exonuclease that catalyzes the removal of mononucleotides from the 3′ termini of duplex DNA but not the 5′ termini or an exonuclease that catalyzes the removal of mononucleotides from the 5′ termini of duplex DNA but not the 3′ termini, wherein said exonuclease preferentially degrades duplex DNA, to produce single-stranded half molecules;
adding a homopolymeric tail to the 3′ end of the single stranded half molecules, hybridizing a primer to the homopolymeric tail, and extending the primer to generate double-stranded half fragments from the single-stranded half molecules;
amplifying a plurality of the double-stranded fragments by a polymerase chain reaction (PCR), and
modulating the size of the amplified fragments by varying one or more reaction conditions or reagents to reduce the complexity of the first nucleic acid sample.
2. The method of claim 1 wherein the reaction condition or reagent varied is chosen from the group consisting of: extension time, annealing time, primer concentration, primer length, presence or absence of 3′ to 5′ exonuclease activity, and concentration of nucleotide analogues.
3. The method of claim 1 wherein the adaptors are designed so that the 5′ and 3′ ends of the amplified fragments are complementary to one another.
4. The method of claim 3 wherein the complementarity is at least 10 bases long and is within 50 bases of the ends of the fragments.
5. The method of claim 3 wherein the complementarity is at least 10 bases long and is within 100 bases of the ends of the fragments.
6. The method of claim 1 where the reaction condition varied is the extension time of the PCR.
7. The method of claim 6 where the extension time is 2-5 seconds.
8. The method of claim 6 where the extension time is 5-10 seconds.
9. The method of claim 6 where the extension time is 10-30 seconds.
10. The method of claim 1 where the reaction condition varied is primer concentration.
11. The method of claim 10 where the primer concentration is 0.1-1 μM.
12. The method of claim 10 where the primer concentration is 0.1-10 μM.
13. The method of claim 10 where the primer concentration is 0.5 to 2.0 μM.
14. The method of claim 10 where the primer concentration is 0.3 to 5 μM.
15. The method of claim 1 where the reaction condition varied is primer length.
16. The method of claim 15 where the primer length is 10 to 100 bases.
17. The method of claim 15 where the primer length is 15 to 50 bases.
18. The method of claim 15 where the primer length is 20 to 35 bases.
19. The method of claim 1 where the reaction condition varied is the presence or absence of a 3′ to 5′ exonuclease activity.
20. The method of claim 1 where the reaction condition varied is the inclusion of one or more strand terminating nucleotides.
21. The method of claim 20 wherein the strand terminating nucleotides are selected from the following dideoxyribonucleotide triphosphates: ddATP, ddTTP, ddGTP, ddCTP and ddUTP.
22. The method of claim 21 wherein the ratio of dNTP to ddNTP is 100 to 1.
23. The method of claim 21 wherein the ratio of dNTP to ddNTP is 1000 to 1.
24. The method of claim 1 further comprising the step of fractionating the fragments according to size by gel filtration chromatography prior to amplification.
25. The method of claim 1 wherein the step of fragmenting the first nucleic acid sample comprises digestion with at least one restriction enzyme.
26. The method of claim 1 wherein the step of fragmenting the first nucleic acid sample comprises digestion with a restriction enzyme that has a six base recognition sequence.
27. The method of claim 1 wherein the adaptor sequences comprise PCR primer template sequences.
28. The method of claim 1 wherein the second nucleic acid sample comprises at least 0.01% of the first nucleic acid sample.
29. The method of claim 1 wherein the second nucleic acid sample comprises at least 0.5% of the first nucleic acid sample.
30. The method of claim 1 wherein the second nucleic acid sample comprises at least 3% of the first nucleic acid sample.
31. The method of claim 1 wherein the second nucleic acid sample comprises at least 12% of the first nucleic acid sample.
32. The method of claim 1 wherein the second nucleic acid sample comprises at least 50% of the first nucleic acid sample.
33. The method of claim 1 wherein the first nucleic acid sample is genomic DNA, DNA, cDNA derived from RNA or mRNA.
34. The method of claim 1 wherein the size range of a substantial amount of the amplified fragments is 100 to 1000 base pairs.
35. The method of claim 1 wherein the size range of a substantial amount of the amplified fragments is 200 to 1200 base pairs.
36. The method of claim 1 wherein the size range of a substantial amount of the amplified fragments is 400 to 800 base pairs.
37. A method ofreducing the complexity of a first nucleic acid sample to produce a second nucleic acid sample whereby the second nucleic acid sample is obtainable by:
fragmenting the first nucleic acid sample to produce double-stranded fragments;
ligating adaptor sequences to both ends of the double-stranded fragments such that the 5′ and 3′ ends of the adaptor-ligated double-stranded fragments are complementary to one another;
digesting the adaptor ligated double-stranded fragments with an exonuclease that catalyzes the removal of mononucleotides from the 3′ termini of duplex DNA but not the 5′ termini or an exonuclease that catalyzes the removal of mononucleotides from the 5′ termini of duplex DNA but not the 3′ termini, wherein said exonuclease peferentially degrades duplex DNA, to produce single stranded half molecules;
adding a homopolymeric tail to the 3′ end of the single stranded half molecules, hybridizing a primer to the homopolymeric tail, and extending the primer to generate double stranded half fragments from the single stranded half molecules; and,
amplifying a subset of the double-stranded half fragments by a polymerase chain reaction (PCR) wherein a subset of fragments of a specific size range are preferentially amplified by varying the PCR primer concentration.
38. The method of claim 37 where the primer concentration is 0.1-1 μM.
39. The method of claim 37 where the primer concentration is 0.1-10 μM.
40. The method of claim 37 where the primer concentration is 0.5 to 2.0 μM.
41. The method of claim 37 where the primer concentration is 0.3 to 0.5 μM.
42. The method of claim 1 wherein said exonuclease is selected from the group consisting of exonuclease III, T7 exonuclease and Lambda exonuclease.
43. The method of claim 37 wherein said exonuclease is selected from the group consisting of exonuclease III, T7 exonuclease and Lambda exonuclease.