Technology
A modified polymerase chain reaction (PCR) technique in which a specific primer can amplify its corresponding allele only; this allows for the determination of the presence or absence of a single, specific allele during genotype testing.
Diagnostic Methods
Technology
A technique designed to rapidly enrich and amplify targets derived from samples that yield low levels of nucleic acids, such as formalin-fixed paraffin-embedded (FFPE) tissues, for use in next-generation sequencing. Briefly, total nucleic acid or genomic DNA (gDNA) is isolated from fresh or FFPE tissues. Total nucleic acid is converted to double-stranded cDNA (dscDNA) and cleaned by solid-phase reversible immobilization (SPRI). Then the dscDNA or gDNA is subjected to end repair, adenylation and ligation with a universal half-functional adapter. The modified DNA sample is then subjected to two rounds of nested low-cycle PCR, where the first round uses target gene-specific primers and the second round uses nested target gene-specific primers that are 5' tagged with a common sequencing adapter. The resulting target amplicon library is cleaned using SPRI and is suitable for use in next generation genomic assays.
Diagnostic Methods
Technology
A molecular cytogenetic method combining chromosomal comparative genomic hybridization technique and microarray to detect chromosomal aberrations and changes in DNA copy numbers in the genome, using oligonucleotides immobilized on a solid support as targets for hybridization.
Diagnostic Methods
Technology
A molecular genetic technique that isolates and sequences chromosomal regions that are rich in open chromatin. First, nuclei are harvested from a cellular sample. Then a hyperactive Tn5 transposase is added to the nuclei where it excises non-nucleosomal DNA strands and ligates co-administered high-throughput sequencing adapters (tagmentation). The tagged DNA fragments are isolated, amplified by PCR and sequenced. The number of reads for specific region of DNA correlate with increased chromatin accessibility and this method can identify regions of transcription factor and nucleosome binding.
Diagnostic Methods
Technology
A spectrometric method that determines the type and concentration of metal elements in a sample, based upon the principle that each elemental metal absorbs a particular wavelength of ultraviolet light when exposed to heat.
Diagnostic Methods
Technology
Several related technologies for imaging and measuring surfaces on a fine scale, down to the level of molecules and groups of atoms. These technologies share the concept of scanning an extremely sharp tip (3-50 nm radius of curvature) across the object surface. The tip is mounted on a flexible cantilever, allowing the tip to follow the surface profile. When the tip moves in proximity to the investigated object, forces of interaction between the tip and the surface influence the movement of the cantilever. Various interactions can be studied depending on the specific mechanics of the probe. Specialized sensors detect and record the movements of the cantilever, providing an image with resolution at the atomic level.
Diagnostic Methods
Technology
A DNA sequencing technique that can differentiate cytosine from 5-methylcytosine in a DNA sample. First, a denatured DNA sample is treated with bisulfite which converts non-methylated cytosine to uracil. Next, the sample is amplified using a PCR method that does not discriminate between non-methylated and methylated sequences. The amplified DNA is subjected to nucleotide sequencing. The resulting sequence is compared to an identical control sample of DNA that was not treated with bisulfite. Unmethylated cytosines will be displayed as cytosines in the control sample and as thymines in the bisulfite-treated sample.
Diagnostic Methods
Technology
An electrophoresis procedure, in which a sample is introduced into a capillary tube and the components are separated by the application of high voltage. Due to the large surface to volume ratio, cooling is more efficient, allowing use of higher voltages. As a result, separation occurs more quickly and sensitivity is increased. The technique allows for separation of proteins, nucleic acids, and carbohydrates.
Diagnostic Methods
Technology
General term referring to the maintenance of cell strains or lines in the laboratory.
Diagnostic Methods
Technology
A molecular genetic technique that combines chromatin immunoprecipitation (ChIP) with massively parallel DNA sequencing to map the binding sites of DNA-associated proteins in a sample of cells. First, crosslinked protein-DNA complexes are isolated using ChIP. Next, the crosslinks are broken, the proteins are removed and the purified DNA is modified with adaptor oligonucleotides to facilitate massively parallel DNA sequencing. Following sequencing, the DNA sequences that are obtained can be mapped to their genomic locations.
Diagnostic Methods
Technology
A technique that utilizes immunoprecipitation to find protein-DNA interactions in a biological sample. First, the sample is treated causing the formation of protein-chromatin crosslinks. Then, the sample is sheared to separate individual protein-DNA complexes. Finally, an antibody directed against a protein of interest is applied and the protein-DNA complexes are immunoprecipitated.
Diagnostic Methods
Technology
A laboratory procedure that combines the sequence-specific detection aspects of FISH with the simple detection methods of immunohistochemistry. Briefly, sequence-specific probes are hybridized to cells fixed on slides and the sequestered probe is visualized by a peroxidase reaction. It has the advantage of being a less costly assay that does not require fluorescence microscopy with results that are stable over time.
Diagnostic Methods