Table 1.

Survival after 24 h in Aminopterin plus Sulfanilamide medium

Relevant genotype	% survival, 24 h	SD	t-Test
(A) BY4741 backgrounda
Wild-type	22.8	8.7
ung1	36.0	6.6	0.05
apn1 (6 h)	1.1	0.06	0.001b
apn1 (24 h)	0.08	0.008	8.8 × 10−8
apn2	39.3	18	0.25
pol32	33.3	21	0.49
rad27	2.3	0.6	2.6 × 10−7
dpb3	13.3	0.6	9.0 × 10−4
dpb4	9.3	4.9	0.014
(B) SSL204 backgroundc
Wild-type	10.8	4.4
ung1	11.2	5.4	0.9
apn1	0.03	0.01	<0.05
rad27	11.0	5.8	0.95
(C) apn1 combination mutants in SSL204 backgroundd
apn1 ung1	12.7	1.5	0.005
apn1 ntg1 ntg2	0.04	0.01	0.54
apn1 rev3 (12 h)e	0.10	0.01	0.82
apn1 apn2	0.09	0.04	0.33

^aVarious mutants in the uracil-BER pathway in the BY4741 background were treated with aminopterin and sulfanilamide as described in Materials and Methods. Following a 24 h exposure, portions of the culture were collected and plated to rich YPD medium. Colonies were counted after 4 days. Survival is reported as the number of colony forming units per milliliter at 24 h/colony forming units per milliliter at time zero. apn1 mutants were assessed at earlier time points given the lack of sufficient survivors at 24 h.

^bCompared with wild-type at 6 h.

^cAminopterin sensitivity was determined as described above for mutants generated in the SSL204.

^dAminopterin sensitivity of apn1 mutant strains bearing mutations in additional DNA repair genes.

^eCompared with apn1 at 12 h.