What is the frequency of mutations induced spontaneously through Ethylnitrosourea (ENU) mutagenesis?
['The mutation frequency increased linearly with MNU or ENU concentration (0.01--2.0 mM); mean values were 2800 and 840 mutants per 10(6) clonable cells per mM, respectively', 'The mutation frequency induced by a 400 mg/kg dosage of ethylnitrosourea is 12 times the maximal mutation frequency achievable with a single exposure to x-rays and 36 times that reported for procarbazine, the most effective chemical mutagen previously known for mouse stem-cell spermatogonia', 'Specific locus tests designed to detect recessive mutations showed that ENU is the most efficient mutagen in mouse with an approximate mutation rate of 1 in 1,000 gametes.', 'Theoretical considerations and empirical analysis suggest that the per-base mutation frequency for a fractionated-dose treatment protocol is on the order of 1 sequence change per 10(5) bp', 'Unlike spontaneous chromosome damage, spontaneous mutant frequencies did not differ significantly among homozygous, heterozygous, and wild-type mice (3.2 x 10(-5), 3.1 x 10(-5), and 3.1 x 10(-5), respectively; P > 0.05)', 'The ENU-induced mutation frequency in Blmtm3Brd homozygous, heterozygous, and wild mice were 54 x 10(-5), 35 x 10(-5), and 25 x 10(-5) mutants/plaques, respectively', 'mutation frequencies per nucleotide based on mutant spectra from this study and published literature. We found this frequency in control spleen to be similar for lacI (3.8 +/- 0.7 x 10(-8)) and PhiX174 (3.1 +/- 1.2 x 10(-8)) at 6 weeks of age']
['Theoretical considerations and empirical analysis suggest that the per-base mutation frequency for a fractionated-dose treatment protocol is on the order of 1 sequence change per 10(5) bp.']
['1/100000']