ISOLATION, MAPPING, DNA-SEQUENCE AND RFLPS STUDIES OF RANDOM SINGLE-COPY DNA SEGMENTS ON HUMAN X-CHROMOSOME

Using the total human/mouse DNA as the prober screening has been carri ed out three times with in situ plaque hybridization to obtain the sin gle-copy DNA sequence from the human X chromosome genomic library. The effective rate of screening is 1.45%. DNAs from clones containing sin gle-copy inserts have been analyzed by a panel of hybrid cells with or without human X chromosome. Three segments , designated by DXFD52,73, 75, are mapped to the X chromosome. DXFD52 has been precisely localize d on Xq12-q13 with in situ chromosomal hybridisation. DXFD52 has been partially sequenced. The results indicate that DXFD52 is a new isolate d single-copy segment on the X chromosome. Great progress in the RFLPs study with DXFD52 has been achieved in the population of Chongqing, S ichuan Province. The results show that the DXFD52 can be used to detec t the RFLP with Hind III, Bgl II, and Hinf I. DXFD52 will be a potenti al ''landmark'' for the construction of the complete linkage map of hu man genome and the analysis of genomic sequence. And also, the results provide the experience in the development of a useful DNA probe to be applied to diagnosing X-linked disorders.