Growth of chromosome ends in multiplying trypanosomes

Some of the genes for the variant surface glycoproteins of trypanosomes are located close to a discontinuity in the DNA, presumably a chromosome end. We show here that DNA fragments containing these telomeres increase in length in multiplying trypanosomes at a rate of about 10 base pairs per division. We argue that chromosome growth may not be restricted to trypanosomes and could explain the heterogeneity of telomeric DNA fragments observed in some other organisms.