DISSECTING THE CENTROMERE OF THE HUMAN Y-CHROMOSOME WITH CLONED TELOMERIC DNA

We have used telomeric DNA to break the human Y chromosome within the centromeric array of alphoid satellite DNA and have created two deriva tive chromosomes; one consists of the short arm and 140 kb of alphoid DNA, the other consists of the long arm and 480 kb of alphoid DNA. Bat h segregate accurately at mitosis. It is known that there is no large scale sequence duplication around the alphoid DNA and so the simplest interpretation of our results is that the sequence responsible for acc urate segregation is the alphoid DNA itself. Although the long arm acr ocentric derivative segregates accurately it lags with respect to the other chromosomes in about 10% of anaphase cells and thus additional s equences may be required for orderly segregation. The short arm acroce ntric chromosome is probably no larger than 12 Mb in size and thus our results also demonstrate that chromosomes of this size are capable of accurate segregation.