Telomere length measurement by Q-FISH.

Telomeres are essential functional elements of eukaryotic chromosomes involved in genome stability maintenance. The most important indicator of correct telomere function is telomere length maintenance within the range typical for each species. Telomere length can be estimated by the classical methodology based on Southern blot. However, this methodology is relatively crude and can provide estimate of average telomere length only. To overcome disadvantages of classical telomere length estimate, a new technique termed Q-FISH has been invented. Q-FISH provides estimate of telomere length in each individual chromosome with the resolution of 200 base pairs. In addition, Q-FISH may be used to estimate telomere length in species containing interstitial telomeric sites in their genomes. The classical methodology is non-informative in these cases. Finally, Q-FISH has been essential in estimating telomere length in the mouse, a species with ultra-long telomeres difficult to measure using classical methods. Principles of Q-FISH and its applications are briefly described in this article.