Large-scale isolation of human 1p36-specific P1 clones and their use for fluorescence in situ hybridization.

A series of 80 microclone probes derived from the chromosomal region 1p36 was used to isolate corresponding clones from the ICRF human P1 library (see Francis et al., this issue). Hybridization screenings were performed using probe pools on high-density filter grids. A total of 87 P1 clones specific for 1p36 were isolated. This large-scale approach allowed a detailed evaluation of the complexity, quality, and utility of this library. The isolated P1 clones were used both for size determination by pulsed-field gel electrophoresis and as probes for fluorescence in situ hybridization (FISH) analysis. FISH of P1 clones is shown to be both easy and efficient to perform on metaphase chromosomes and interphase nuclei. This observation is expected to reveal new avenues for diagnosis of disease-related chromosomal changes. The use of P1 clones as a tool in clinical and tumor interphase cytogenetics is discussed and compared with FISH data of other long insert clones such as cosmids and YAC clones.