OBJECTIVETo explore the molecular spectra and mechanism of human hypoxanthine guanine phosphoribosyl transferase (HPRT) gene mutation induced by ethyluitrosourea (ENU).

METHODSSingle cell cloning culture, two-way screening, multiple PCR amplification and electrophoresis technique were used.

RESULTSWith dose of ENU increasing, cell plating efficiency reduced (in the group with 100-200 micro g/ml doses, P < 0.01) and mutation frequency increased (in the group with 12.5-200.0 micro g/ml doses, P < 0.05) significantly. There was no all exons deletion in spontaneous mutations, and only 7.7% of them were detected as single exon deletion. But, deletion was found in 79.7% of ENU-induced mutations (62.5%-89.4%, P < 0.01), and deletion mutations in all nine exons of HPRT gene. Most of ENU-induced mutations were chain deletion with multiple exons (88.1%).

CONCLUSIONSThe spectra in spontaneous mutations differed completely from ENU-induced ones. ENU was liable to cause bigger changes in genetic structure, which suggested a stronger ENU's mutagenesis.