Construction of a PAC contig overlying the HAPPY map. One end of the HAPPY map of chromosome VI, spanning ∼135 kb, is shown (thin horizontal line). Heavy horizontal lines indicate PAC clones, with sizes given in kbp (clones are not to scale). (•) The marker order derived from the contig (not all markers can be ordered); (◼) The clone is positive for those markers. There are no first-rate marker inversions on the HAPPY map above a distance of ∼20 kb. The second-rate marker (2cr1135) is ∼50 kb from its expected position (max. 95 kb, i.e., length of clone 1h1). The total length of the contig is between 140 kb (clones 1d7 plus 3a1) and 285 kb (clones 18b10, 1h1 plus 18h9), depending on the degree of overlap.
