FGSC #5301

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Reporting Genes: ad-3A ad-3B nic-2;cot-1

Species: crassa

Allele: B110 C94 43002 1-112-38

Alternate Strain Number: 74-OR51-5a

Depositor: FJD

Linkage Group: IR R R;IVR

Mating Type: a

Species Number: 10

Genetic Background: OR

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
ad-3A	IR. Between his-3 (1 to 2%) and ad-3B (0.1 to 0.7%) (271). Right of ure-4 (78). (482) Requires adenine or hypoxanthine (682). Blocked in interconversion of CAIR plus aspartate to SAICAR (348) (Fig. 8). Produces purple pigment, permitting direct visual selection (276, 682); see the ad-3B entry. Reduced interallelic fertility (407). No interallelic complementation (267; F.J. de Serres, personal communication). ad-3A and ad-3B are two genetically and functionally distinct loci separated by a short but functionally complex region of unknown but essential function (271, 407). They have been used intensively for quantitative genetic and molecular studies of mutation (for a review, see reference 35). Either forward mutation (e.g., reference 277) or reverse mutation (e.g., reference 772) can be measured precisely; the former is detected visually by purple pigment. Purple pigment has also been used to assess the effect of histidine and tryptophan on purine nucleotide synthesis (786). Alleles N23 and N24 have been used as mutagen testers. N23 reverts with agents that cause base pair substitutions; N24 reverts with agents that cause frameshifts (772). SK(ad-3A) is at or near ad-3A and may be a cryptic ad-3A allele. Does not require adenine. In SK(ad-3A)x ad-3Acrosses, the ad-3A progeny die; possibly SK(ad-3A) mutants fail to make enough adenine to support their growth (251). Translocations Y155M64 ad-3A (272; PB) and Y112M15 ad-3A(413) each have one breakpoint that is inseparable from ad-3A. Called complementation group A (264). "A" in the locus symbol does not refer to mating type.	IR	B
ad-3B	IR. Between ad-3A (0.1 to 0.7%) and nic-2 (3%) (271). (482) Uses adenine or hypoxanthine (682). Blocked in interconversion of AIR to CAIR (348) (Fig. 8). Produces purple pigment, permitting direct visual selection (276, 682). Pigment is secreted with low concentrations of adenine (e.g., 0.1 mM), not with high concentrations (2 mM) (276, 682, 785). Pigment production used to assess effect of histidine and tryptophan on purine nucleotide synthesis (786). Reduced interallelic fertility (264, 407). Complementation maps (268, 274). Relation of mutagens to complementation patterns (269). Mutants with non-polarized complementation patterns on the right side of the complementation map grow on minimal medium if supplied with CO2; other mutants do not respond to CO2, (270). Used extensively for mutagenesis (see ad-3A). Rearrangement T(I- >III)Y112M4i ad-3B, which has a breakpoint inseparable from ad-3B, was the first insertional translocation to be reported for fungi (266). Allele 7-017-0137 shows "fixed instability," mutating to an unstable prototrophic allele (41). Alleles 2-17-126, 12-21-28, and numerous others are supersuppressible (408, 749, 955). Called complementation group B.	IR	B
cot-1	IVR. Between pan-1 (2%) and his-4 (1 to 6%) (692, 812, 816). Extremely colonial at 34°C, but completely normal growth, morphology, and fertility at 25°C and below. Linear growth is maximum at 24°C (374). Becomes colonial at 32°C; colonies from ascospores or conidia are viable and continue to grow slowly with dense branching, but do not conidiate. They quickly resume normal growth when shifted to a permissive temperature (692, 1068). Recessive in duplications (808); apparent dominance in heterokaryons (374) may have resulted from a shift in nuclear ratios. Used in studies of septation and branching (202), growth-inhibiting mucopolysaccharide (878, 879), and sulfate transport (641). Cell wall analysis (374). Growth is stimulated by lysine or arginine (0.1 mM) on glucose media at high temperatures (615). Because of high viability and tightly restricted growth at restrictive temperatures and normality at 25°C, cot-1 mutants have valuable technical applications. For example, crosses homozygous for cot-1 have been used in combination with sorbose for experiments with rec genes, where high-density ascospore platings are required for precise quantitative analysis of intralocus recombination (e.g., references 165, 997, and 1070). In another application, when shifted up after initial growth at the permissive low temperature, cot-1hyphae assume a "bottle brush" appearance with small side branches (692). This has been used to select uvs mutants by subsurface survival on UV-irradiated plates containing p-aminobenzoic acid (938; D.E.A. Catcheside, personal communication). cot-1 conidia or ascospores from cot-1 x cot-1crosses are used for replication in a protocol involving transfer by filter paper (615). For suppressors of cot-1, see gul.	IVR	B
nic-2	IR. Between ad-3B (4%) and ace-7 (4 to 7%) (271, 578). (482) Grows on nicotinic acid, nicotinamide, or high concentrations of quinolinic acid (97, 1168). Cannot use kynurenine, hydroxykynurenine, or hydroxyanthranilic acid (96, 1168). Accumulates 3-hydroxyanthranilic acid (96) (Fig. 18). Aging cultures accumulate red-brown pigment in the medium. Used to study intralocus recombination (908). Translocations T(4540) and T(S1325)are inseparable from nic-2 (808, 908, 911).	IR	B