FGSC #2252

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Reporting Genes: al-1;arg-5;cot-1

Species: crassa

Allele: 15300;27947;C102(t)

Alternate Strain Number: RL3531-34

Depositor: RKL

Linkage Group: IR;IIR;IVR

Mating Type: A

Species Number: 10

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
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
arg-5	Uses ornithine, citrulline or arginine.	IIR	B
al-1	IR. Right of hom (<1%), arg-6 (<1 to 4%), T(T54M94), and al-2. Left of lys-3 (9%). (797, 808; D.D. Perkins, unpublished data). (482) Carotenoids abnormal. Strains carrying the various alleles differ widely in phenotype, ranging from white (e.g., 4637) and "aurescent" (pigment in peripheral conidia and conidiophores, 34508) to yellow mycelia and conidia (e.g., ALS4 and RES-25). See, for example, reference 1042. Strains carrying alleles ALS-14, RES-6, 34508, and RES-25 contain large amounts of phytoene (99 to 100% of the total neutral carotenoids), suggesting a lesion that affects phytoene dehydrogenase (398, 1039) (see Fig. 9). Strains carrying allele RWT-ylo accumulate zeta carotene and smaller amounts of neurosporene, suggesting a leaky block of the step between these intermediates (1071). It is not known whether phytoene dehydrogenase catalyzes the whole series of dehydrogenations or whether leakiness of this enzyme accounts for the different mutant phenotypes. For complementation tests, see references 500, 1039, and 1041. Fine-structure mapping (500, 1042). Translocation T(4637), inseparable from al-1, was the first albino mutation and one of the first chromosome rearrangements in Neurospora to be identified and studied (656). Allele 34508 called aur: aurescent.	IR	B