Characterization of molecules in nanofluidics
Methods are provided for characterizing a sample comprising polynucleotide sequences. The methods can comprise labeling nucleic acid molecules of the sample, translocating the plurality of labeled sample nucleic acid molecules though one or more fluidic nanochannels, detecting physical counts of signals from the labeled sample nucleic acid molecule, and determining a copy number of a genome or a fragment or fragments thereof in the sample.
1. A method of characterizing a sample comprising polynucleotide sequences, the method comprising:
labeling a plurality of sample nucleic acid molecules, each of about 10 base pairs to about 500 base pairs, with at least a first label, wherein the sample nucleic acid molecules comprise polynucleotide sequences of a genome or a fragment or fragments thereof, wherein the polynucleotide sequences of the sample nucleic acid molecules are from the sample;
providing a plurality of labeled control nucleic acid molecules, each of about 10 base pairs to about 500 base pairs, wherein the control nucleic acid molecules comprise polynucleotide sequences of the genome or fragment or fragments thereof;
translocating the plurality of labeled sample nucleic acid molecules through one or more fluidic nanochannels having a length of at least 10 nm and a cross-sectional diameter of less than 1000 nm;
translocating the labeled control nucleic acid molecules through one or more fluidic nanochannels having a length of at least 10 nm and a cross-sectional diameter of less than 1000 nm;
detecting physical counts of signals from the labeled sample nucleic acid molecules, said signals comprising patterns characteristic of the genome or fragment or fragments thereof; detecting physical counts of signals from the labeled control nucleic acid molecules, said signals comprising patterns characteristic of the genome or fragment or fragments thereof; and
aligning the patterns to a reference of the genome or fragment or fragments thereof, thereby ascertaining:
a coverage depth for the sample nucleic acid molecules over the reference of the genome or fragment or fragments; and
a coverage depth for the control nucleic acid molecules over the reference genome or fragment or fragments; and
determining a copy number of the genome or fragment or fragments thereof in the sample.
2. The method of claim 1 , wherein the sample nucleic acid molecules are derived from maternal blood, and wherein the labeled control nucleic acid molecules are derived from a maternal sample other than blood.
3. The method of claim 1 , wherein the sample comprises fetal DNA.
4. The method of claim 1 , further comprising generating a histogram distribution to reflect coverage depth for the sample nucleic acid molecules.
5. The method of claim 1 , further comprising labeling control nucleic acid molecules so as to produce the labeled control molecules.
6. The method of claim 1 , wherein the signals from the labeled control nucleic acid molecules comprise an electronically or optically stored value or set of values.
7. The method of claim 1 , wherein the sample nucleic acid molecules comprise a sex chromosome or a least one fragment thereof, and wherein the labeled control nucleic acid molecules comprise an autosome or at least one fragment thereof.
8. The method of claim 1 , wherein the first label comprises at least one of a fluorescent label, a radioactive label, a magnetic label, or a non-optical label.
9. The method of claim 1 , wherein labeling the plurality of sample nucleic acid molecules comprises:
nicking one strand of a double-stranded DNA at a first sequence motif with a nicking endonuclease, thereby generating nicks on the double-stranded DNA; and
labeling the double-stranded DNA.
10. The method of claim 9 , further comprising repairing at least some of the nicks on the double-stranded DNA.
11. The method of claim 1 , wherein the plurality of labeled control nucleic acid molecules comprise a label that is different from the first label.
12. The method of claim 1 , wherein the plurality of labeled control nucleic acid molecules comprise a label that is the same as the first label.
13. The method of claim 1 , wherein labeling with the first label comprises tagging at least one sequence motif of the sample nucleic acid molecules with a methyltransferase.
14. The method of claim 1 , further comprising labeling the sample nucleic acid molecules with a non-sequence-specific label.
15. The method of claim 1 , wherein the labeled control molecules are from the sample, or wherein the labeled control molecules are from a different tissue of a same organism as the sample, or wherein the labeled control molecules are from a different organism than the sample.