Dna sequencing

Abstract

Provided herein is technology relating to sequencing nucleic acids and particularly, but not exclusively, to methods, compositions, and systems for sequencing a nucleic acid using two or more labels and signal ratios to distinguish bases.

We claim: 
     
         1 . A composition comprising a plurality of a nucleotide base wherein a first portion of the plurality is labeled with a first label and a second portion of the plurality is labeled with a second label. 
     
     
         2 . The composition of  claim 1  further comprising a second plurality of a second nucleotide base wherein a third portion of the second plurality is labeled with the first label and a fourth portion of the second plurality is labeled with the second label and a first ratio of the first portion relative to the second portion is different than a second ratio of the third portion relative to the fourth portion. 
     
     
         3 . The composition of  claim 2  further comprising a third plurality of a third nucleotide base and a fourth plurality of a fourth nucleotide base, wherein a fifth portion of the third plurality is labeled with the first label and a sixth portion of the third plurality is labeled with the second label, and a seventh portion of the fourth plurality is labeled with the first label and an eighth portion of the fourth plurality is labeled with the second label and a third ratio of the fifth portion relative to the sixth portion is different than a ratio of the seventh portion relative to the eighth portion and the third and the fourth ratios are both different than the first and the second ratios. 
     
     
         4 . The composition of  claim 3  wherein the first nucleotide base is A, the second nucleotide base is C, the third nucleotide base is G, and the fourth nucleotide base is T. 
     
     
         5 . The composition of  claim 1  wherein the label is a fluorescent moiety. 
     
     
         6 . The composition of  claim 1  further comprising a target nucleic acid, a sequencing primer, and a polymerase. 
     
     
         7 . The composition of  claim 1  further comprising a nucleic acid comprising the nucleotide base. 
     
     
         8 . A system for sequencing a nucleic acid, wherein the system comprises:
 a) a composition comprising a plurality of a nucleotide base wherein a first portion of the plurality is labeled with a first label and a second portion of the plurality is labeled with a second label; and   b) a calibration oligonucleotide.   
     
     
         9 . The system of  claim 8  further comprising a sequencing apparatus. 
     
     
         10 . The system of  claim 8  further comprising a processor configured to associate a signal ratio with a nucleotide base. 
     
     
         11 . The system of  claim 8  further comprising an output functionality to provide a nucleotide sequence of the nucleic acid. 
     
     
         12 . The system of  claim 8  further comprising a second plurality of a second nucleotide base, a third plurality of a third nucleotide base, and a fourth plurality of a fourth nucleotide base, wherein a third portion of the second plurality is labeled with the first label and a fourth portion of the second plurality is labeled with the second label, a fifth portion of the third plurality is labeled with the first label and a sixth portion of the third plurality is labeled with the second label, and a seventh portion of the fourth plurality is labeled with the first label and an eighth portion of the fourth plurality is labeled with the second label and a first ratio of the first portion relative to the second portion, a second ratio of the third portion to the fourth portion, a third ratio of the fifth portion to the sixth portion, and a fourth ratio of the seventh portion to the eighth portion are different from one another. 
     
     
         13 . The system of  claim 8  further comprising a functionality to detect the first label and the second label. 
     
     
         14 . The system of  claim 12  further comprising a functionality to differentiate the nucleotide base, the second nucleotide base, the third nucleotide base, and the fourth nucleotide base from one another. 
     
     
         15 . A kit for sequencing a nucleic acid, wherein the kit comprises:
 a) a composition comprising a plurality of a nucleotide base wherein a first portion of the plurality is labeled with a first label and a second portion of the plurality is labeled with a second label; and   b) a calibration oligonucleotide.   
     
     
         16 . The kit of  claim 15  further comprising a second plurality of a second nucleotide base, a third plurality of a third nucleotide base, and a fourth plurality of a fourth nucleotide base, wherein a third portion of the second plurality is labeled with the first label and a fourth portion of the second plurality is labeled with the second label, a fifth portion of the third plurality is labeled with the first label and a sixth portion of the third plurality is labeled with the second label, and a seventh portion of the fourth plurality is labeled with the first label and an eighth portion of the fourth plurality is labeled with the second label and a first ratio of the first portion relative to the second portion, a second ratio of the third portion to the fourth portion, a third ratio of the fifth portion to the sixth portion, and a fourth ratio of the seventh portion to the eighth portion are different from one another.