[Use of specific DNA probes for mapping the ceruloplasmin gene on rat chromosomes by direct in situ hybridization].

Specific DNA-probes representing the fragments of chromosomal ceruplasmin gene (lambda RCp-1, lambda RCp-2, lambda RCp-3) and its cDNA copy of the corresponding mRNA were heavily labelled with 125J dCTP (the specific activity of the probes varying from 1.5 X 10(7) to 3.4 X 10(8) dpm). These probes were used for in situ hybridization on metaphase chromosomes. The total number of silver grains and their distribution along differentially stained chromosomes were determined in 653 metaphase plates from bone marrow cells of laboratory rats. The results of in situ hybridization were very similar for all four specific DNA-probes tested and allow to assign ceruplasmin gene to the q13 region of chromosome 7. The local increase of silver grain count over chromosome 15 was also registered and discussed.