with the aid of the probes pgag lb19 seq id no 30 ppro e seq id no 32 and penv c15 seq id no 31 each of the probes is denatured and deposited on a hybond n membrane in an amount of 2 5 5 10 25 50 100 pg per deposit 0 5 mg of human dna are also deposited on the same membrane the membranes are dried for 2 hours under vacuum at 80 u00b0 c the membranes are then hybridized with the deposited probe the techniques for labeling the probes for hybridization and for washing the membranes are the same as for the southern blotting after autoradiography of the membranes levels of signal intensity which are proportional to the deposits on the membrane are observed after cutting out the hybridization zones scintillation counting is carried out by comparison between the dilution series for the probe deposited on the membrane and the result obtained with the human dna it is possible to evaluate the number of copies per haploid genome of each of the regions covered by the probes the number of endogenous gag is evaluated from 56 to 112 copies 76 the number of endogenous protease is evaluated from 166 to 334 copies 260 the number of endogenous env is evaluated at less than 52 copies 13 the screening of 10 6 clones of a human placental dna library clontech cat h15014b made it possible to count 144 clones recognized by the probe pgag lb19 and 64 clones recognized by the probe penv c15 13 clones hybridized conjointly with the probes penv c15 and pgag lb19 were isolated confirming the presence of several copies of a genome possessing both gag and env without consideration of functionality the nucleic material the nucleotide sequences and the peptides or.