MINICHROMOSOMES DERIVED FROM THE HUMAN Y-CHROMOSOME BY TELOMERE DIRECTED CHROMOSOME BREAKAGE

We have used telomeric DNA to break two acrocentric derivatives of the human Y chromosome into mini-chromosomes that are small enough to be size-fractionated by pulsed-field gel electrophoresis. One of the mini -chromosomes is about 7 Mb in size and sequence-tagged site analysis o f this molecule suggests that it corresponds to a simple truncation of the short arm of the Y chromosome. Five of the mini-chromosomes are d erived from the long arm, are all rearranged by more than a simple tru ncation, and range in size from 4.0 Mb to 9 Mb. We have studied the mi totic stabilities of these mini-chromosomes and shown that they are st ably maintained by cells proliferating in culture for about 100 cell d ivisions.