Nucleic acid probes for in situ hybridization
The invention provides nucleic acid hybridization probes having improved detectability that include a plurality of first segments consecutively complementary to a target nucleic acid sequence and, between neighboring first segments, a nucleic acid spacer segment which is not complementary to the target nucleic acid sequence and which may include labeled nucleic acid residues. Also provided by the invention are methods for making the probes, methods for using the probes, and compositions of matter that include the probes hybridized to target nucleic acid molecules.
1. A method for preparing a nucleic acid hybridization probe composition for a nucleic acid target of interest, comprising the steps of:
providing an in vitro mixture of
(a) a DNA construct comprising an RNA promoter operably linked to a template DNA sequence, wherein the template sequence encodes a non-naturally occurring linear nucleic acid molecule having a 5′ end and a 3′ end and comprising
a series of first nucleic acid segments consecutively complementary to a preselected nucleic acid target sequence, and
between each adjacent pair of first nucleic acid segments, a spacer nucleic acid segment,
wherein the spacer segments are not substantially complementary to the preselected nucleic acid target sequence, and
wherein the spacer segments are not substantially complementary to the first segments,
(b) a mixture of different ribonucleoside triphosphates wherein at least some of said ribonucleoside triphosphates are chemically labeled;
(c) an RNA polymerase capable of transcribing an RNA molecule comprising residues of the chemically labeled ribonucleoside triphosphates from the template under control of the promoter;
incubating said mixture under conditions permissive for transcription of the RNA molecule by the RNA polymerase, wherein said RNA molecule is thereby transcribed in quantity; and
partially fragmenting the quantity of RNA molecule obtained by transcription in the incubating step to obtain a fragmented nucleic acid hybridization probe composition.
2. The method of claim 1 , wherein the chemically labeled ribonucleoside triphosphates comprise a hapten label.
3. The method of claim 2 , wherein the hapten label is selected from the group consisting of biotin and digoxigenin.
4. The method of claim 1 , wherein the chemically labeled ribonucleoside triphosphates comprise a fluorescent label.
5. The method of claim 1 , wherein the chemically labeled ribonucleoside triphosphates comprise an allyl amine group label.
6. A method for preparing a nucleic acid hybridization probe composition for a nucleic acid target of interest, comprising the steps of:
providing an in vitro mixture of
(a) a nucleic acid template molecule, wherein the template sequence encodes a non-naturally occurring linear nucleic acid molecule having a 5′ end and a 3′ end and including
a series of first nucleic acid segments consecutively complementary to a preselected nucleic acid target sequence, and
between each adjacent pair of first nucleic acid segments, a spacer nucleic acid segment,
wherein the spacer segments are not substantially complementary to the preselected nucleic acid target sequence;
(b) a template-directed nucleic acid polymerase capable of synthesizing a nucleic acid molecule comprising residues of chemically labeled nucleoside triphosphates and complementary to at least part of the template using the template molecule, and
(c) a mixture of different nucleoside triphosphates wherein at least some of said nucleoside triphosphates are chemically labeled;
incubating said mixture under conditions permissive for template-directed nucleic acid synthesis by the polymerase, wherein said nucleic acid molecule including residues of the chemically labeled nucleoside triphosphates and complementary to at least part of the template is thereby synthesized in quantity by the polymerase using the template; and
partially fragmenting the quantity of the synthesized nucleic acid molecule comprising residues of chemically labeled nucleoside triphosphates and complementary to at least part of the template to obtain a fragmented nucleic acid hybridization probe composition.
7. The method of claim 6 , wherein the chemically labeled ribonucleoside triphosphates comprise a hapten label.
8. The method of claim 7 , wherein the hapten label is selected from the group consisting of biotin and digoxigenin.
9. The method of claim 6 , wherein the chemically labeled ribonucleoside triphosphates comprise a fluorescent label.
10. The method of claim 6 , wherein the chemically labeled ribonucleoside triphosphates comprise an allyl amine group label.