Problems Associated With Telomere Length Measurement

The most authoritative recent review on telomere biology and papers describing the key discoveries mentioned above as well as methodological advances are listed in the reference list.[1-6] The classical method for telomere length measurement is based on Southern blot analysis. In a typical protocol, DNA is extracted from a cell sample and the resulting DNA mix is exposed to frequently cutting restriction enzymes, which will produce a series of DNA fragments, and those fragments containing telo-meres are called terminal restriction fragments (TRFs). Following gel electrophoresis these fragments are transferred onto a nylon membrane, which is then hybridized with the radioactively labeled telomeric DNA probe. Following autoradiography, telomeres are detected as a smear, the size of which can be measured against appropriate molecular weight markers. This method has some major disadvantages. First, it can only measure the average telomere length and the information about the size of individual telomeres is ignored. Individual telomeres, not the average telomere length, drive genomic instability associated with telomere dysfunction,[7] thus indicating that measuring only the average telomere length may not be appropriate. Second, the presence of degenerate telomeric sequences in subtelomeric regions of chromosomes may interfere with the accuracy of Southern blot-based telomere length measurements, i.e., sequences that do not form part of functional telomeres may also be measured.[8] Third, hybridization efficiency of DNA probes is never 100% because DNA probes used for hybridization and genomic DNA have the same electrical charge and this may cause a charge repulsion between molecules resulting in inefficient hybridization. Therefore, a new method more efficient than Southern blot was required to provide more accurate information about telomere length.

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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