DIGITAL COUNTING OF INDIVIDUAL MOLECULES BY STOCHASTIC ATTACHMENT OF DIVERSE LABELS
Compositions, methods and kits are disclosed for high-sensitivity single molecule digital counting by the stochastic labeling of a collection of identical molecules by attachment of a diverse set of labels. Each copy of a molecule randomly chooses from a non-depleting reservoir of diverse labels. Detection may be by a variety of methods including hybridization based or sequencing. Molecules that would otherwise be identical in information content can be labeled to create a separately detectable product that is unique or approximately unique in a collection. This stochastic transformation relaxes the problem of counting molecules from one of locating and identifying identical molecules to a series of binary digital questions detecting whether preprogrammed labels are present. The methods may be used, for example, to estimate the number of separate molecules of a given type or types within a sample.
1 . A method, comprising:
(a) providing a surface comprising a population of beads, wherein the beads comprise a plurality of oligonucleotides, wherein an oligonucleotide of the plurality of oligonucleotides comprises:
a primer site,
a unique identifier sequence, and
a probe configured to label a target nucleic acid of a sample;
(b) contacting the sample comprising target nucleic acids with the surface;
(c) labeling the target nucleic acid with the probe, thereby generating a modified target nucleic acid; and
(d) determining a location of the target nucleic acid upon sequencing an amplicon generated using the modified target nucleic acid.
2 . The method of claim 1 , wherein she surface is a rigid surface or semi-rigid surface of a substrate.
3 . The method of claim 1 , wherein the surface is substantially flat.
4 . The method of claim 1 , wherein the population of beads is coupled to a rigid surface.
5 . The method of claim 1 , wherein the sample comprises a plurality of cells.
6 . The method of claim 1 , wherein the unique identifier sequence comprises a stochastic sequence.
7 . The method of claim 1 , wherein the target nucleic acid comprises a messenger RNA (mRNA) sequence.
8 . The method of claim 1 , wherein the probe comprises a complementary sequence configured to hybridize with a portion of the target nucleic acid.
9 . The method of claim 1 , wherein a ratio between a) a first number of diverse oligonucleotides of the plurality of oligonucleotides and b) a second number of target nucleic acids, is greater than 10.
10 . The method of claim 1 , wherein the plurality of oligonucleotides comprises at least 10,000 different sequences.
11 . The method of claim 1 , wherein the sample comprises a single cell.
12 . The method of claim 1 , wherein the sample comprises a tumor cell.
13 . The method of claim 1 , further comprising characterizing a status of a tissue upon determining a level of expression of the target nucleic acid in the sample.
14 . A kit comprising:
a population of solid supports at a surface,
wherein the population of solid supports comprises a plurality of oligonucleotides, and wherein an oligonucleotide of the plurality of oligonucleotides comprises a sequence from which a location on the solid support can be determined, and wherein the oligonucleotide comprises:
a primer site,
a unique identifier sequence, and
a probe configured to label a target nucleic acid of a sample.
15 . The kit of claim 14 , wherein the surface is a rigid surface or semi-rigid surface of a substrate.
16 . The kit of claim 14 , wherein the surface is substantially flat.
17 . The kit of claim 14 , wherein the unique identifier sequence comprises a stochastic sequence.
18 . The kit of claim 14 , wherein a ratio between a) a first number of diverse oligonucleotides of the plurality of oligonucleotides and b) a second number of target nucleic acids of a sample to be processed using the kit, is greater than 10.
19 . The kit of claim 14 , wherein the target nucleic acid comprises mRNA.
20 . The kit of claim 14 , further comprising reagents for generating amplicons from the target nucleic acid.
21 . The kit of claim 14 , further comprising one or more reagents for generating a sequencing library from the sample.
22 . The kit of claim 14 , wherein the plurality of oligonucleotides has a spacing of at least 10 4 molecules per micron 2 .