Telomere and LINE-like elements at the termini of the Chlorella chromosome I.

The telomeres of Chlorella chromosomes consisted of 5'-TTTAGGG repeats, which are exactly the same as those of higher plants. This sequence was reiterated approximately 70 times at both termini of chromosome I. Subtelomeric sequences next to the telomeres were totally different between the right and left arms. On the left-side subtelomeric region, polyA associated LINE (long interspersed element)-like elements were found tandemly repeated just next to the telomeric repeats. It is very interesting to compare this unique structure with telomeres of Drosophila, where a transposable element play a major role in forming telomerase-generated repeats. We propose a mechanism of transposon-mediated healing of a broken chromosomal end that would operate in the unicellular green alga Chlorella.