Application

As a result of its high specificity, the padlock probe has found clinical and research applications in several genetic assays, including in situ hybridization and SNP detection. The padlock probe was initially designed to analyze chromosomes in a cell undergoing interphase or meta-phase.[2] Because of its ability to lock onto target DNA, a glass slide can be washed under stringent conditions (above the melting temperature), therefore lowering background signal and improving detection sensitivity. With the aid of fluorescent reporter molecules, such as biotin or digoxigenin, the bound padlock probes attached to interphase or metaphase chromosomes can be visualized under a microscope.[2] Two fluorescent-labeled padlock probes have been used to detect human centromeric alpha satellite DNA of chromosome 13 and 21, which contains multiple repeats.[11] Two chromosomes were individually visualized under a microscope. Furthermore, the padlock probe can detect a single nucleotide difference in two satellite sequences.[11] Although the padlock probe alone is adequate to detect a repeat motif, it is insufficient to detect a single-copy gene sequence in situ because of low signal intensity.

Single-nucleotide polymorphisms of genomic DNA are considered to be the most common form of genetic variations, occurring in approximately every 250-2000 bases. With the availability of large SNP databases, detection of specific sets of SNPs will allow for identification of disease-associated polymorphisms to correlate therapies with clinical outcomes and drug effect as well as parentage and forensic testing. The padlock probe offers a significant advantage to detect SNPs. For ligation to occur, both ends must perfectly hybridize to the target at juxtaposition (Fig. 1B). The discrimination of SNPs by ligation was approximately 1:100 to 1:1000 in a mixture of mutant alleles in an excess of wild-type alleles.[12] For RNA targets, the discrimination by ligation ranged from 20- to 200-fold.[10]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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