La. Klobutcher, DEVELOPMENTALLY EXCISED DNA-SEQUENCES IN EUPLOTES-CRASSUS CAPABLE OF FORMING G QUARTETS, Proceedings of the National Academy of Sciences of the United Statesof America, 92(6), 1995, pp. 1979-1983
Tens of thousands of DNA segments are eliminated by DNA breakage and r
ejoining events during the formation of a new macronucleus in the hypo
trichous ciliated protozoan Euplotes crassus. This study presents evid
ence for a class of eliminated sequences referred to as telomeric-repe
at-like internal eliminated sequences (TelIESs). TelIESs are shorter (
<50 bp) than most previously characterized IESs and their DNA sequence
s resemble the telomeric repeat sequences of the organism. The TelIESs
are excised during the developmental period of chromosome fragmentati
on/telomere addition, which is later than previously characterized IES
s. Additional studies demonstrate that oligonucleotides representing t
he TelIESs are, like telomeric repeats, capable of forming G-quartet s
tructures in vitro.