PNA probes hybridize in a sequence-specific manner to DNA and RNA by obeying Watson-Crick base-paring rules. However, because of their structure, PNAs have significant advantages compared with DNA probes, as outlined below:
• Higher sensitivity: PNA binds stronger and faster to complementary RNA or DNA, thereby facilitating the development of more rapid and sensitive diagnostic tests. Where DNA probes often require overnight incubation, reactions with PNA are completed within a few hours.
• Higher specificity: PNA probes are particularly well suited for discriminating closely related sequences, even single nucleotide differences, thus making PNA-based assays 100% definitive.
• Robust assays: PNA is a synthetic molecule resistant to nucleases and proteases. It is extremely stable in prepackaged kit formats, as well as during the actual assay when in contact with the sample.
• Novel assay formats: The unique properties of PNA enable the development of assay formats that go above and beyond the possibilities of DNA probes, thereby reducing the complexity related to the performance of molecular diagnostic tests.
• No target limitation: The noncharged backbone allows PNA probes to hybridize under conditions that are destabilizing to DNA and RNA. Attributes that enable PNA probes to access targets, such as highly structured rRNA and double-stranded DNA, are known to be inaccessible to DNA probes.
• In situ hybridization: The hydrophobic nature of PNA relative to DNA makes PNA probes superior for in situ hybridization assays where the probes must penetrate the hydrophobic cell wall prior to hybridization.
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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.