Table 1.

Summary of mutant screening.

Mutagen	Condition	Survival rate (%)	No. of colonies screened	No. of mutantsa (occurrence %)	Strains used in this study
NTG	1 mg mL−1, 4 min	—b	1248	5 (0.4)
	1 mg mL−1, 7 min	—	846	7 (0.8)
	1 mg mL−1, 10 min	11	480	9 (1.9)	N9D9, N10E6
	2 mg mL−1, 10 min	15	384	0 (0)
	1 mg mL−1, 20 min	0.8	576	9 (1.6)	N3H4, N4H4, N6F4, N7C9
	Total		3534	30 (0.8)
GR	772 Gy	39	2168	6 (0.3)	G1G7, G17D5, G21E10
	1158 Gy	5	1080	13 (1.2)	G23C4, G23D3, G26C1
	Total		3248	19 (0.6)

^aMutants that showed a clear phenotype in the second screening.

^bNot determined.