Abstract: Methods and kits for labeling nucleic acids are provided. In the subject methods, an oligonucleotide tagged nucleic acid comprising an oligonucleotide tag is first generated. The oligonucleotide tagged nucleic acid is then contacted under hybridization conditions with a labeled oligonucleotide complementary to the oligonucleotide tag, yielding a labeled nucleic acid. The kits of the subject invention at least include a primer for use in enzymatically generating an oligonucleotide tagged target nucleic acid, where the primer generally at least includes an oligo dT region and the oligonucleotide tag, and a labeled oligonucleotide complementary to the oligonucleotide tag. The subject methods and kits find use in a variety of applications, and are particularly suited for use in gene expression analysis applications.

Abstract: A method of evaluating for the presence of a target polynucleotide in a sample, using an addressable array of multiple polynucleotide probes linked to a substrate. The sample is exposed to the array and a set of polynucleotide target probes, such that target polynucleotide which may be present will bind to a predetermined feature of the array through multiple target probes of the set by forming at respective target regions on a target molecule, simultaneous hybrids with anti-target regions of the multiple target probes. A binding pattern on the array is observed and the presence of the target polynucleotide evaluated based on the observed binding pattern. Kits using such arrays, and methods for selecting target probes are further provided.

Abstract: A computational method and system for predicting the hybridization potential for two polymers. A probe/target interaction matrix is prepared to contain indications of all possible probe/target subunit interaction stabilities. The probe/target interaction matrix is analyzed to create a list of possible single-fragment hybridizations. A graph is then generated with vertices representing fragments, and edges representing possible loops in one or both of the probe and target sequences that allow the pair of fragments interconnected by the edge to coexist within a multi-fragment cross-hybridization. Finally, the graph is analyzed to construct a list of all possible single-fragment and multi-fragment cross-hybridizations possible between the probe molecule and the target molecule. The different hybridizations are scored and sorted by score.

Abstract: Nucleic acid arrays that have background features, and methods for using the same, are provided. The subject nucleic acid arrays include both hybridization features and background features, where the background features provide a background signal in a hybridization assay that is made up of a feature substrate component, a nucleic acid probe component and a nucleic acid probe non-specific binding component. In practicing the subject methods, the arrays are contacted with a sample and signals are observed for both hybridization features and background features. The background feature signal is then subtracted from the hybridization feature signal to obtain a background corrected hybridization feature signal that is employed as the output of the assay, e.g., to determine the presence, either qualitatively or quantitatively, of the analyte target nucleic acid in the sample. Also provided are kits for use in practicing the subject methods.

Abstract: Methods for substantially improved detection and analysis in nucleic acid hybridization assays are described. The methods provide the reliable estimation of background signal which derives primarily from nonspecific hybridization. The invention is useful in chemical, biological, medical and diagnostic techniques, as well as for drug discovery.

Abstract: An apparatus, systems and method for locating nucleic acids in an array on a substrate have self-locating nucleic acid features. The nucleic acid features produce nucleotide-dependent location signals or optically detectable contrast between nucleotide-bound regions and non-nucleotide-bound regions of the substrate when scanned by an optical scanner. When used as analytical tools for monitoring gene expression and mutations in gene sequences, the nucleotide features are hybridized with nucleic acids of known or unknown sequences. The apparatus, systems and method locate both weakly and strongly hybridized nucleotide features on the substrate for identification of target nucleic acid sequences. The nucleotide feature signals or contrast are independent of the optical signals conventionally produced by the hybridized nucleotides. Therefore, the apparatus, systems and method locate all of the nucleotide features, hybridized or not, independently of the extent of hybridization.

Abstract: Methods are disclosed for predicting the potential of an oligonucleotide to hybridize to a target nucleotide sequence. A predetermined number of unique oligonucleotides is identified. The unique oligonucleotides are chosen to sample the entire length of a nucleotide sequence that is hybridizable with the target nucleotide sequence. At least one parameter that is independently predictive of the ability of each of the oligonucleotides of the set to hybridize to the target nucleotide sequence is determined and evaluated for each of the above oligonucleotides. A subset of oligonucleotides within the predetermined number of unique oligonucleotides is identified based on the evaluation of the parameter. Oligonucleotides in the subset are identified that are clustered along a region of the nucleotide sequence that is hybridizable to the target nucleotide sequence. The method may be carried out with the aid of a computer.

Abstract: Methods and kits for labeling nucleic acids are provided. In the subject methods, an oligonucleotide tagged nucleic acid comprising an oligonucleotide tag is first generated. The oligonucleotide tagged nucleic acid is then contacted under hybridization conditions with a labeled oligonucleotide complementary to the oligonucleotide tag, yielding a labeled nucleic acid. The kits of the subject invention at least include a primer for use in enzymatically generating an oligonucleotide tagged target nucleic acid, where the primer generally at least includes an oligo dT region and the oligonucleotide tag, and a labeled oligonucleotide complementary to the oligonucleotide tag. The subject methods and kits find use in a variety of applications, and are particularly suited for use in gene expression analysis applications.

Abstract: Viable bacteria may be detected in biological samples by exposing bacterial cultures obtained from the samples to transducing particles having a known host range. Such transducing particles carry a heterologous gene capable of altering the phenotype of the bacteria in a readily detectable manner. For example, the transducing particles may carry an ice nucleation gene and the alteration of phenotype may be detected using an ice nucleation assay. By employing a panel of phage, unknown bacteria may be typed based on the pattern of reactivity observed. The method is particularly useful for detecting viable bacteria which may have been debilitated by exposure to sterilizing conditions, such as in food processing. The method is also useful for tracking a target bacteria in the ambient environment.

Abstract: Viable bacteria may be detected in biological samples by exposing bacterial cultures obtained from the samples to transducing particles having a known host range. Such transducing particles carry a heterologous gene capable of altering the phenotype of the bacteria in a readily detectable manner. For example, the transducing particles may carry an ice nucleation gene and the alteration of phenotype may be detected using an ice nucleation assay. By employing a panel of phage, unknown bacteria nmay be typed based on the pattern of reactivity observed. The transducing particles may be prepared by introducing a synthetic transposable element carrying the heterologous gene to a host carrying a prophage having the desired host range. After transposition, the host may be induced to a lytic cycle to release the transducing particles carrying the heterologous gene.

Abstract: A novel method for carrying out immunoassays is described. The method involves use of a biological ice nucleating agent as a label. In particular, the method involves use of ice nucleating bacteria, or ice nucleating components derived therefrom, as a label.