HETEROGENEITY IN TELOMERE LENGTH OF HUMAN-CHROMOSOMES

Vertebrate chromosomes terminate in variable numbers of T(2)AG(3) nucl eotide repeats, In order to study telomere repeats at individual chrom osomes, we developed novel, quantitative fluorescence in situ hybridiz ation procedures using labeled (C(3)TA(2))(3) peptide nucleic acid and digital imaging microscopy. Telomere fluorescence intensity values fr om metaphase chromosomes of cultured human hematopoietic cells decreas ed with the replication history of the cells, varied up to six-fold wi thin a metaphase, and were similar between sister chromatid telomeres. Surprisingly, telomere fluorescence intensity values within normal ad ult bone marrow metaphases did not show a normal distribution, suggest ing that a minimum number of repeats at each telomere is required and/ or maintained during normal hematopoiesis.