Neurospora mutants beginning with A and B

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Arginine (arg)
Aromatic Amino Acids (aro)
Band (bd)

an: anaerobic

Segregates 1:1. Not mapped.

Reported to be facultatively anaerobic, growing weakly anaerobically on enriched medium. Prototrophic and indistinguishable from the wild type under aerobic conditions. Not glucose repressed. The anaerobic culture is aconidial, with reduced cytochrome oxidase and malate dehydrogenase activities and mitochondrial changes. Ethanol is produced. Obtained by filtration enrichment with recycling. (492, 493) The symbol An+ has been used in reference 493 to specify the mutant phenotype. and An- has been used to specify the wild phenotype.

ANT-1: (antimycin-sensitive strain)
Symbol used to designate double-mutant strain azs;has (311). Not a locus designation. (Also called alx-1.) See azs and has.

aod-1: alternate oxidase deficient-1
IV. Left of trp-4 (23%) (1051).

The alternate oxidase system is not induced when cytochrome-mediated, cyanide-sensitive respiration is inhibited. In four aod-1 mutants, a mitochondrial peptide of Mr = 35,000 is induced as in the wild type; in a fifth mutant, it is absent. Recessive. Strains carrying aod-1 plus either [mi-1] or [mi-3] are viable. (82,1051) Called aod-B (82). Three alleles originally called aod-1, aod-2, and aod-3 are now called aod-1-1, aod-1-2, and aod-1-3, respectively (1051).

aod-2: alternate oxidase deficient-2
II. Linked to arg-5 (7%), thr-3 (16%), and trp-3 (36%) (82, 1051).

The alternate oxidase system is not induced when cytochrome-mediated, cyanide-sensitive respiration is inhibited. A mitochondrial polypeptide (Mr, 35,000) is not induced as in the wild type. Recessive. Strains carrying aod-2 plus either[ mi-1] or [mi-3] are viable (82, 1051). Called aod-A (82). The allele originally called aod-4 is now called aod-2-1 (1051).

apu: accumulation of purines
Not linked to ad-7 (VR), mt, or aza-1 (IL).

Excretes purines. Obtained among prototrophic revertants of the mutant ad-7 (ad-7 blocks the first step in de novo purine synthesis). Secretion assayed by cross-feeding on plates seeded with ad-3A conidia. Purine secretion by the mutant apu occurs later, and the colony size is larger than with strains carrying aza-1 allele 67-12 (4 days versus 36 h; 25 C). (525).

arg: arginine
For details of the arginine biosynthetic pathway, see Fig. 10. The most comprehensive reference on biosynthetic pathway mutants is 238. Arginine mutants have been used extensively for studies of compartmentation (see references 223, 233, 242, and 245) and for studies of control of flux through the arginine pathway (356 and references therein; also see the ota entry). Crossing is inhibited by high arginine levels; 0.1 or 0.2 mg of arginine per ml of crossing medium is satisfactory. Lysine and arginine show competitive inhibition, and all arginine auxotrophs are inhibited by lysine. Lysine resistance is conferred on arg-1 mutants by probable transport mutation lysR, q.v. Crosses of strains involving both requirements can usually be handled by adjusting the ratio. Medium containing 0.8 mg of L-arginine hydrochloride and 1.6 mg of L-lysine hydrochloride per ml is recommended for crosses (P. St. Lawrence, personal communication). Leaky arginine mutants (e.g., arg-2, arg-3, arg-13) are less leaky on nitrate medium (238) or canavanine plus lysine (876). Leakiness of germinating ascospores of arg-1 and arg-3 strains is prevented by 0.05 mg of lysine per ml with no canavanine (D. Newmeyer, unpublished data). Some arg genes were originally called cit or orn. For degradative or related steps in arginine metabolism, see aga, ota, spe, and ure.

Arginine biosynthesis and catabolism are controlled in a major way by compartmentation (reviewed in references 237 and 245). Acetyl glutamate kinase and acetyl glutamate synthase are feedback regulated by arginine (1148: C.P. Chang and R.L. Weiss, personal communication). With one exception, the enzymes of arginine biosynthesis are not repressed below levels that occur in minimal medium when arginine is added to cultures. The exception is carbamylphosphate synthetase A, the small subunit of which is repressed fivefold. When cultures are limited for arginine, all but one biosynthetic enzyme increase concomitantly by about three to fivefold; the carbamyl-phosphate synthetase A small subunit increases as much as 20-fold (223, 242). These "derepressions" can also be brought about by starvation for other amino acids such as tryptophan, lysine, and histidine (137, 1131; reviewed in reference 642); they require the normal product of the cpc-1 locus (61). See cpc-1. The catabolic enzymes arginase and ornithine aminotransferase are present without induction and are elevated only two- to fivefold in response to nitrogen limitation or the addition of arginine (but not ornithine) to the medium. These enzymes are not affected by mutations at the nit-2 or cpc-1 locus.

FIG. 10. Biosynthetic pathways for arginine, proline, polyamines. and associated intermediary metabolism, showing sites of gene action in biosynthesis and arginine catabolism (238. 241, 452, 569, 657, 696, 697, 1009, 1105, 1177, and references therein). Carbamyl phosphate for pyrimidine synthesis is made as a separate pool by a distinct enzyme (see pyr-3. Fig. 20). Interchange between the two pools occurs only in certain mutant combinations. ATP, Adenosine triphosphate.

arg-1: arginine-1
IL. Between ad-5 (1%) and eth-1 (<1%) (816). (751).

Uses arginine but not precursors (1010). Lacks argininosuccinate synthetase (752) (Fig. 10.). Interallelic crosses produce perithecia, but most ascospores are white and inviable (751). Leaky arg-1 mutants are frequent among those selected as citrulline-resistant variants of arg-12s;pyr-3. Most of these show interallelic complementation, and many are transport deficient (1075). arg-1 mutants do not grow well on some complex complete media unless extra arginine is added.

arg-2: arginine-2
IVR. Right of col-4 (<1 to 2%). Between T(S1229) breakpoints, but not between T(S4342) breakpoints; hence, left of arg-14 and pyr-3 (1 to 3%). (101, 692, 695, 808, 876, 991).

Uses citrulline or arginine (1010). Specifies the small component of arginine-specific carbamyl-phosphate synthetase A, a two-component enzyme (242). This component enables the enzyme to use glutamine as a nitrogen donor (233, 243). (The large component is specified by arg-3.) (See Fig. 10..) For regulation and compartmentation, see reference 242. The arginine/citrulline requirement can be suppressed by pyr-3 (CPS+ ACT-) mutations (236, 876); see pyr-3. Leakiness is prevented by canavanine; lysine overcomes the side effects of canavanine (876). Strains with some (all?) of the alleles can grow on minimal medium in 30% CO2, (108). Leakiness is decreased if CO2, is removed or if uridine is added (880). Translocation T(IL;IVR)MEP24 is inseparable from arg-2 (R.H. Davis, personal communication).

arg-3: arginine-3
IL. Between eth-1 (1%) and csp-1 (1%) (816, 972). Between the T(39311) breakpoints; hence, left of the centromere and of sn (1 to 6%) (174, 798). (1005).

Uses citrulline or arginine (1010). Structural gene for the large component of arginine-specific carbamyl-phosphate synthetase A, a two-component enzyme (242, 243). This component can form carbamyl phosphate in vitro, using ammonia as the nitrogen donor (231, 243). (The small component is specified by arg-2.) (See Fig. 10..) For regulation and compartmentation, see reference 242. The arginine/citruiline requirement can be suppressed by pyr-3 (CPS+ ACT-) (236, 658); see pyr-3. Strains carrying allele 30300 can grow on minimal media in 40% CO2 (108, 191). Translocation MEP35 is inseparable from arg-3 (R.H. Davis, personal communication; PB) Called cit-1.

arg-4: arginine-4
VR. Between sp (1 to 11%) and inl (2 to 4%) (812, 976). (D.G. Catcheside, cited in reference 812).

Uses ornithine, citrulline, or arginine (1010). Lacks acetylornithine-glutamate transacetylase (acetylornithine acetyltransferase) (249, 1106) (Fig. 10.). Weakly suppresses CPS- ATC+ pyr-3 mutants (see reference 660). Alleles 21502 and 34105 (later called arg-4 and arg-7) were originally thought to be genetically distinct because they complemented each other (1005), but an intercross produced no recombinants (R.W. Barratt, cited in reference 660). Both lack the same enzyme (249, 1106).

arg-5: arginine-5
IIR. Right of T(ALS176); hence, right of the centromere. Left of aro-3 (428, 808; D.G. Catcheside, cited in reference 812). (789). Listed incorrectly in I by Houlahan et al. (482) because linkage of arg-5 to albino in T(I;11)4637 al-1 had been shown previously (1005).

Uses ornithine, citrulline, or arginine (1010). Structural gene for acetylornithine transaminase (696) (Fig. 10.). Sideramine production is completely blocked in the triple mutant arg-5;ota;aga when ornithine is absent. Used to study iron transport (1146, 1147). Called orn-1.

arg-6: arginine-6
IR. Right of T(T54M94) and al-2 (1 to 2%). Left of hom (1%), al-1 (<1 to 4%), and T(4637) (797, 808). (1005).

Uses ornithine, citrulline, or arginine (1010). Probably bifunctional, specifying arginine-sensitive acetylglutamate kinase (238) and N-acetylglutamyl-phosphate reductase (J. Cybis and R.H. Davis, cited in reference 238). Probably the structural gene for both enzymes (R.H. Davis, E. Wolf, and R.L. Weiss, personal communication) (Fig. 10.). L-Methionine may inhibit (D.D. Perkins, unpublished data). Possible allele: su(pro-3) (1129). Called orn-2.

arg-7: arginine-7
Same as arg-4, q.v. Called orn-3.

arg-8: arginine-8
See pro-3.

arg-9: arginine-9
See pro-4.

arg-10: arginine-10
VIIR. Between arg-11 (1 to 2%) and nt (1 to 12%) (751, 789).

Uses arginine but not precursors (751). Lacks argininosuccinate lyase (341) (Fig. 10.). Accumulates argininosuccinate on limiting arginine (341). Viable ascospores from interallelic crosses are rare, but the viable ones are often arg+, whereas most arg- ascospores remain colorless and inviable (751). All arg-10 mutants tested showed spasmodic growth in growth tubes at low arginine concentrations (O.J. Gillie, personal communication). arg-10 mutants do not grow well on some complete media unless extra arginine is added.

arg-11: arginine-11
VIIR. Left of arg-10 (1 to 2%) (789).

Requires arginine or citruiline, plus low levels of a purine and a pyrimidine (290, 754, 1006). Inhibited by guanidine, sarcosine, and serocyamine (1005). Complements arg-10 fully in heterokaryons (754). The relation of this mutation to arginine biosynthesis or metabolism is obscure. Growth requirements vary markedly with CO2 concentration and inoculum size. At 0% CO2 or with small inocula, the requirement for all three supplements is absolute; with increasing CO2 concentration or inoculum size, pyrimidine and then purine can be omitted; at 30% CO2, all three supplements can be omitted. (108, 192, 754) Growth rate and morphology are highly variable among progeny from arg-11 x wild type crosses (754). Grows spasmodically in growth tubes (O.J. Gillie, personal communication). Allele 44601 formerly called un and adg (290, 482).

arg-12: arginine-12
IIR. Right of pe (1 to 5%). Left of the T(NM177) right breakpoint and of aro-1 (<1%) (389, 808, 1052). (1160).

Uses citrulline or arginine. Structural gene for ornithine carbamyl transferase (230, 244, 1160) (Fig. 10.). Leaky allele arg-12s was discovered as a suppressor of a pyr-3 mutant and initially called s (483). It reduces ornithine carbamyl transferase activity over 98% without imposing any arginine requirement. arg-12s suppresses the pyrimidine requirement of pyr-3 strains that lack only pyrimidine-specific carbamyl-phosphate synthetase. This is because arg-12s strains accumulate arginine-specific carbamyl phosphate, which can then be used for pyrimidine synthesis (236); see pyr-3. Nonleaky arg-12 alleles cannot cause such suppression because the exogenous arginine that is required for growth results in repression of the arginine-specific carbamyl-phosphate synthetase (236). Mutations at all other arginine biosynthesis loci can be obtained efficiently as tight double mutations, using arg-12s as starting material (238). Double mutants pro4;arg-12s and pro-3;arg-12s are prototrophic. The double mutant arg-5 arg-12s cannot use exogenous ornithine (see references 234, 241).

arg-13: arginine-13
IR. Between os-1 (1%) and so (2 to 12%) (816). (660)

Responds well to arginine or citrulline and poorly to ornithine (238, 660). Acts as a suppressor of the pyrimidine requirement of CPS-ACT+ mutations of pyr-3 (660). Leaky on minimal medium; scoring cleared by addition of lysine. Interallelic crosses are sterile. Formerly called arg(RU3).

arg-14: arginine-14
IVR. Right of the T(S4342) left breakpoint and of arg-2 (1%). Left of T(NM152) and pyr-3 (1%) (238).

Uses arginine, citrulline, or ornithine. Point mutants selected as tight double mutants by using arg-12s (238). Allele S1229 is inseparable from translocation T(S1229). (54, 55, 808)

arg(CD-15), arg(CD-55)
See cpc-1.

Allelic with am, q.v.

argR: arginine resistant.
IVR. Right of pyr-2 (14%) (566). Probably allelic with pmb (565, 566).

Growth of the double mutant lys-1;argR is resistant to the normal inhibition by L-arginine (566).

aro: aromatic
Used for genes concerned with biosynthesis of aromatic amino acids and p-aminobenzoic acid. All aro strains except aro-6, aro-7, and aro-8 are auxotrophs requiring a mixture of p-aminobenzoic acid, tyrosine, tryptophan, and phenylalanine. The first step in the pathway is catalyzed by three isozymes subject to feedback inhibition by different end products of the branched pathway. These isozymes are specified by different widely separated genes (aro-6, aro-7, aro-8). The second. third, fourth, fifth, and sixth steps are specified by a cluster gene that produces a single transcript (for reviews, see references 387 and 1130). The final step before branching is specified by a unifunctional gene (aro-3) which is separate from the aro cluster gene, although linked to it at a distance. See Fig. 11. for the pathway and sites of gene action. The third and fourth steps are paralleled by similar reactions in the quinate catabolic pathway (see Fig. 21). Thus, the aro-9 enzyme can be replaced by the qa-2 enzyme and, under appropriate conditions, the aro-1 enzyme can be replaced by the qa-3 enzyme. Supplement levels: 40 to 80 mg each of tyrosine, tryptophan, and phenylalanine per liter and 0.25 mg of p-aminobenzoic acid per liter (178, 428). Also called arom.

aro-1, -9, -5, 4, -2: aromatic cluster gene
IIR. Right of T(NM177) and arg-12 (<1%). Left of ff-1 (4 to 6%) (808,1052: A. Kruszewska, personal communication). (47) For intracluster map see references 387 and 885.

Structural gene for the aromatic biosynthetic pathway leading to tryptophan, tyrosine, phenylalanine, and p-aminobenzoic acid (Fig. 11.). Multifunctional cluster gene (370) specifying five enzymes (370, 389, 1130). Clustering of functions discovered by Gross and Fein (428). For reviews, see references 387 and 665. The order of regions that specify the five functions is still conveniently represented by the symbols established when it was thought that five separate genes were involved:

(arg-12) aro-1 aro-9 aro-5 aro-4 aro-2 (ace-1)

aro-1 specifies dehydroshikimate reductase; aro-2, dehydroquinate synthetase; aro-4, 3-enolpyruvyl shikimic acid-5-phosphate synthetase; aro-5, shikimate kinase; and aro-9, biosynthetic dehydroquinase. These symbols actually represent five domains of the pentafunctional polypeptide, which may be separated in purification, owing to proteolysis. The native enzyme is a dimer of the pentafunctional chains (370, 627). In some contexts, it may be preferable to designate the entire cluster gene as a single locus, aro. Mutations exist that block individual steps; in addition, there are polar mutations that eliminate more than one function. There are some discrepancies between genetic mapping and mapping by polarity (reviewed in reference 665). however, various kinds of evidence agree that transcription begins at the aro-2 end (145, 387). aro-1, aro-2, and aro-9 mutants can use shikimate (0.3 mg/ml) as an alternative to the mixture of four aromatic amino acids (shown for aro-1 by Tatum [1055]). Mutations that block different individual steps complement with each other (389). Complementation between alleles that block the same single step has been detected only for aro-2 and aro-1 (139, 389). Polar mutants are divided into six classes (A through F) based chiefly on their complementation behavior (389); types D, E, and F are semicolonial and have yellowish-orange conidia (144). Single-function aro-9 mutants were obtained by selecting in a strain of genotype qa-1, which is noninducible for catabolic dehydroquinase activity (885). Translocation T(II;III)C161 aro (called arom-2) is inseparable from the aro-1 cluster, and T(II;III)C161 strains lack several activities (428). aro(p) indicates polar mutations in the aro cluster. Noncomplementing alleles M26, M1039, M1065, M1108, M1162, M1172, and Y306M54 (abbreviated M54) are suppressible by nonsense suppressors ("supersuppressors") (1449 145, 957).

FIG. 11. Biosynthetic pathways of the aromatic amino acids, showing sites of action to the aro, trp, pt, phe, tyr, and T genes (98, 147, 201, 259, 316, 387, 437, 473, 519, 546, 1126, 1167). The conversion of chorismate to p-aminobenzoate has not been demonstrated in Neurospora. In the conversion of tyrosine to melanin, the later steps are nonenzymatic. The gene products of trp-1 and trp-2 form an enzyme aggregate with three properties; a given trp-1 mutation may block one or more of the reactions. aro-9+ activity (biosynthetic dehydroquinase) can be replaced by the product of qa-2+, the equivalent gene in the catabolic pathway (885). Pretyrosine accumulates when other pathways are blocked (see phe-2). PRPP, 5-Phosphoribosyl pyrophosphate.

aro-1: aromatic-1
Part of the aro cluster gene in IIR. See aro cluster gene.

Specifies dehydroshikimate reductase (Fig. 11.) (389, 428). Accumulates dehydroshikimate, which induces dehydroshikimate dehydrase in the catabolic pathway (428). Suppressed by the mutant qa-4, which lacks dehydroshikimate dehydrase; this allows induction of the catabolic enzyme quinate (shikimate) dehydrogenase, which substitutes for the biosynthetic enzyme dehydroshikimate reductase (147). A lag in growth of the mutant aro-1 on shikimate occurs with sucrose or glucose as the carbon source. This is overcome by substituting 1% glutamate for the sugar (505).

aro-2: aromatic-2
Part of the aro cluster gene in IIR. See aro cluster gene.

Specifies dehydroquinate synthetase (389) (Fig. 11.). aro-2 point mutants should not be confused with strain C161 (arom-2 in reference 428), which lacks several activities specified by the aro cluster, including the aro-2 function (428); the C161 mutation is inseparable from translocation T(IIR;III)C161 (808).

aro-3: aromatic-3
IIR. Right of arg-5 (1 to 3%). Left of T(NM177) and of nuc-2 (428, 671; L. Garnjobst, personal communication). Not closely linked to the aro cluster gene.

Specifies chorismate synthetase (369, 389) (Fig 11). Requires a mixture of p-aminobenzoic acid, tyrosine, tryptophan, and phenylalanine for growth. Shows interallelic complementation (389). Leaky, giving hazy growth on minimal medium at 4 days, 34 C; tests should be scored promptly (D.D. Perkins, unpublished data).

aro-4: aromatic-4
Part of the aro cluster gene in IIR. See aro cluster gene.

Specifies 3-enolpyruvate shikimic acid-5-phosphate synthetase (389) (Fig. 11.).

aro-5: aromatic-5
Part of the aro cluster gene in IIR. See aro cluster gene. Specifies shikimate kinase (389) (Fig. 11.).

aro-6: aromatic-6
VIL. Between ad-8 (8%) and lys-5 (3%) (437).

Grows on minimal medium except when both tryptophan and phenylalanine are present to inhibit the alternate syntheses (437). Structural gene for 3-deoxy-D-arabinoheptulosonic acid-7-phosphate synthase (Tyr), one of the three isozymes inhibitable by tyrosine, phenylalanine, and tryptophan, respectively (Fig. 11.). Both activity-negative and allosteric inhibition-negative alleles have been found (436).

aro-7: aromatic-7
I. Between arg-1 (4%) and his-3 (1 to 2%) (437).

Grows on minimal medium except when both tyrosine and tryptophan are present (437). Structural gene for 3-deoxy-D-arabinoheptulosonic acid-7-phosphate synthase (Phe), one of the three isozymes inhibitable by tyrosine, phenylalanine, and tryptophan, respectively (Fig. 11.). Both activity-negative and allosteric inhibition negative alleles have been found (436).

aro-8: aromatic-8
IR. Between so (7 to 11%) and R (4%) (437, 1093).

Grows on minimal medium except when both phenylalanine and tyrosine are present (437). Probably the structural gene for 3-deoxy-D-arabinoheptulosonic acid-7-phosphate synthase (Trp), one of three isozymes inhibitable by tyrosine, phenylalanine, and tryptophan, respectively (Fig. 11.). Both activity-negative and allosteric inhibition-negative alleles have been found (436).

aro-9: aromatic-9
Part of the aro cluster gene in IIR. See aro cluster gene.

Specifies biosynthetic dehydroquinase (885) (Fig. 11.). Requires shikimic acid or a mixture of four aromatic acid products when a qa mutation is present that eliminates catabolic dehydroquinase. The single mutant aro-9; qa+ grows on minimal medium without supplement. Single-function aro-9 mutants were first obtained by selecting for aro auxotrophs in a strain carrying qa-1, a regulatory mutant which lacks catabolic dehydroquinase activity (885) (Fig. 11.). Conversely, aro-9 is used to select qa-1 and qa-2 mutants (883, 885).


Symbol used for polar mutations that affect several enzymes of the aro cluster gene. See aro-1, -9, -5, 4, and -2.

arom: aromatic
Changed to aro.

ars: aryl sulfatase
VII. Right of thi-3 (2 to 5%). Left of met-7 (<1%) and ile-1 (1%) (666, 725).

Aryl sulfatase structural gene (667). Scored by color reaction with p-nitrophenyl sulfate. Because the enzyme is repressed in the wild type by traces of inorganic sulfate and other compounds present in all normal agars, screening on plates is carried out with an eth-1R cys-11 background, in which ars+ colonies have detectable, derepressed activity (666). Scoring of crosses does not require this special background if the germinated spores are grown with cysteic acid (1 mM) as the sole sulfur source (MgCl2 replacing MgSO4). Scoring method (725). Reversion (699). Mutants lacking aryl sulfatase were first isolated in N. crassa (666), and the gene was later shown to be allelic with a "natural" aryl sulfataseless gene introgressed into N. crassa from one isolate of N. tetrasperma and with a gene which codes for an electrophoretic variant enzyme in another natural isolate of N. tetrasperma (667). Regulation reviewed (642).

asc: ascus development
Symbol used by (253, 254) for recessive mutations affecting ascus (or ascospore) development. Numerous mutations have been given this symbol. Only those mapped are listed here. Five remaining unmapped recessive mutations complement each other and mei-1. Some are barren; others result in much ascospore abortion. See also mei.

IVR. Possibly allelic with mei-1, q.v.

IVR. Possibly allelic with mei-1, q.v.

asc(DL879): ascus development
II. Linked to arg-5 (3%) (253).

Impaired meiosis in homozygous crosses. Recessive. Seventy percent of the ascospores abort and the total ascospore number is reduced, as are pachytene pairing and recombination (254). Viable ascospores are usually disomic for one or more linkage groups. Not tested for allelism with mus-7, which maps in the same region. Crosses homozygous for mus-7 are barren.

asco: ascospore maturation
An allele of lys-5, q.v. Photograph (1012).

Ascospore color mutants, autonomous
See asco, bs, per, ts, ws, cys-3, lys-5, and pan-2. For examples of applications, see references 3149 529, 586, 737, 822, 1013. cys-3 may be best for demonstrating patterns in asci (858; D.D. Perkins, unpublished data).

asn: asparagine
VR. Right of inv (4 to 9%). Left of gran, pl (1 to 9%), and pyr-6 (6%) (156, 158, 698, 1036). (1054)

Requires asparagine for growth; no response to aspartic acid (1054). Lacks asparagine synthetase. Complementation between alleles (K.G. MacPhee, R.E. Nelson, and S.M. Schuster, personal communication via 1980 Neurospora Information Conference). May be inhibited by histidine (D.D. Perkins, unpublished data). Symbol changed from asp (807).

asp: aspartate
V. Between at (0 to 3%) and per-1 (16 to 26%) (819, PB). (812)

Growth aided by aspartate or glutamate. Some response also to homoserine or leucine (290). Grows adoptively on minimal medium; adapts more rapidly at 25°C than at 36°C. Inhibited by alanine; 0.5 mg of alanine per ml of test medium aids scoring. Symbol changed from aspt (807). The symbol asp was originally used for asparagine. In 1973, new symbols were adopted to conform to bacterial usage for amino acid auxotrophs (807), with asn used for asparagine and asp used for aspartate.

aspt: aspartate
Changed to asp.

at: attenuated
V. Right of cyt-9 (5%) and lys-1 (2 to 10%). Left of asp (0 to 3%) (819, PB).

Conidia formed in small flecks or granular clumps on the agar surface, especially in the crescent at top of the slant (819). Growth and pigmentation slower than those of the wild type, but cover slant. Good marker. Most easily scored on minimal medium, on which conidiation is less profuse than on complete medium. Called morph(M111) in reference 819.

atr-1: aminotriazole resistant
IL. Right of In(H4250) and of suc (0/39). Left of the T(39311) right breakpoint (PB). (818)

Resistant to 0.5 mg of 3-amino-1,2,4-triazole per ml of solid medium (added before autoclaving). Not resistant to acriflavine. Abnormal vegetative morphology. Female sterile. Resistance is recessive in heterozygous duplications from T(39311) (PB). Allele RC2 obtained by M.L. Pall. Histidine in test media neutralizes the toxicity of aminotriazole. The mutants acr-2 (498), cpc (61), leu-1, and leu-2 (PB) are also resistant to 3-amino-1,2,4-triazole.

aur: aurescent
Name widely used for al-1 allele 34508 (IR); with strains carrying this allele only mature peripheral conidia and conidiophores become visibly pigmented. Pigment of al-1 mutants is said to be pale yellow (1039), but orange has been observed in 34508 strains (PB).

aza: azapurine resistant
The wild type is resistant to azapurines, but certain strains are sensitive. These sensitive strains were used for selecting azapurine-resistant mutants. Three loci are known. aza-1 and -2 mutants have been lost, but their described characteristics and map locations of the genes should allow recurrences to be recognized. They were selected by using azaadenine, but at least one allele at each locus resulted in resistance also to azaguanine. The aza-3 mutant was selected for resistance to azaguanine by a different procedure, and resistance to azaadenine has not been determined. The designation azapurine is proposed for all three loci.

aza-1: azapurine resistants
IL. Left of mating type (23%) (524).

Resistant to purine analogs 8-azaadenine and 2-6-diaminopurine. (One of four alleles also resulted in resistance to 8-azaguanine.) Obtained by selection in the mutant mts, which is inhibited by the analogs. Selected and scored by using 1 mg of 8-azaadenine per ml of medium. Resistance is recessive in heterokaryons. At least one allele results in purine secretion. Called azaadenine resistant. (524) Strains lost (K.K. Jha, personal communication).

aza-2: azapurine resistant-2
IL. Linked to mating type (2%), aza-1 (39%) (524).

Resistant to purine analogs 8-azaadenine and 8-azaguanine. (One of the alleles does not confer resistance to 2-6-diaminopurine.) Obtained and scored as described for aza-1. Resistance is recessive in heterokaryons. Called azaadenine resistant. (524) Strains lost (K.K. Jha, personal communication).

aza-3: azapurine resistant-3
III. Linked to trp-1 (14%) (462).

Resistant to purine analogs 8-azaguanine and 6-mercaptopurine. Obtained by selection on limiting adenine in an adenine auxotroph which is inhibited by the analogs. Selected and scored by using ad-3A ad-3B;ad-2 on medium with 2 gof adenine sulfate and 200 gof azaguanine per ml. Relative resistance of aza-3R and aza-3S strains to 8-azaadenine not determined. Resistance is recessive in heterokaryons. Hypoxanthine can be used as the sole purine supply (461, 462). Called azaguanine resistant.

azs: azide sensitive
Not mapped. Unlinked to has (311).

Cannot produce the inducible azide-sensitive respiratory pathway when grown in the presence of chloramphenicol (311). The double mutant azs;has has been used to obtain oligomycin-resistant (312) and succinic dehydrogenase-deficient (307) mutants. Obtained from strain ANT-1 (antimycin sensitive; also called alx-1), which segregates for has and azs (305, 308, 311).

Bm: mauve
IL. Left of nit-2 (30%) (395).

Colonies are mauve on special dye medium where the wild type is blue (395).

bal: balloon
II. Right of T(AR179) and, hence, of thr-2 and thr-3. Left of T(ALS176) and arg-5 (1 to 7%,) (789, 808, 812, PB). Probably left of the centromere (428; L. Garnjobst, personal communication).

Forms a smooth, slow-growing hemispherical colony (789). Glucose-6-phosphate dehydrogenase deficiency (948, 949, 952). (col-2 and fr mutants are also deficient in glucose-6-phosphate dehydrogenase.) Reduced NADPH level (110). Reduced linolenate level (115). Reduced amount of peptides in the cell wall (1165). Fully female fertile, which is uncommon for colonial mutants having such restricted growth. Morphology is subject to alteration by modifiers that are commonly present in laboratory stocks, resulting in spreading growth and conidiation. See su(bal). Photograph (112, 946, 948). Allele C-1405 formerly called mel-2 (717, 812)

Ban: Banana
IL. Left of mt (14%); probably left of leu-3 (859).

Each ascus delimits a single giant ascospore that encloses all four meiotic products and their mitotic derivatives. Dominant and almost completely penetrant. Mature giant ascospores are germinable and usually give rise to mixed cultures. In older perithecia, the prefusion nuclei in the croziers revert to mitosis, which is synchronized and favorable for cytological observation. Vegetative morphology is abnormal. Female sterile with no protoperithecia (859). Used in the study of Sk (Spore killer) (857)

bas: basic amino acid transport
Possibly allelic pmb, q.v. Called basa.

bat: basic amino acid transport
Allelic pmb, q.v. (248; R. Sadler and S. Ogilvie-Villa, unpublished data).

bd: band
IVR. Right of pan-1 (2%) (918).

Dense bands of conidia produced on appropriate solid medium (917, 918) at intervals of about 24 h. Conidiation enhanced even on slants Brody, unpublished data). Used extensively to study cirdacian rhythms (114, 329, 918). bd has no effect on underlying clock mechanism, but allows visible expression of rhythm (330). Grows at about 70% of the wild-type rate (S. Brody, unpublished data). CO2 inhibits conidiation and thus inhibits banding; bd mutants are much less sensitive than the wild type to this effect of CO2 (917). Biotin starvation leads to bd phenocopy in the wild type and increased persistence of banding in bd mutants (1132). Originally identified in a bd;inv strain called "timex" (916). bd alone is sufficient to cause banding (918). Used to study conidiation under nonstarvation conditions (928). The double mutant with csp eliminates conidial scatter (example: reference 114). Conveniently scored by conidial banding on agar in long tubes or large plates at 25°C in constant dark or in a dark-light cycle, but not in constant light (916).

See Bml.

bis: biscuit
Name changed to pk (peak), q.v. For nomenclature, see p. 270 of reference 816.

Probably allelic pmb, q.v.

Bml: Benomyl resistant
VIL. Linked to cys-2 (2%) and ylo-1 (2 to 3% probably between them (103, PB).

Resistant to the fungicide benomyl [methyl(butylcarbamol)benzimidazol-2-yl carbamate (102, 103). Resistance appears dominant in forced heterokaryons (103). Readily scored on 1 ug of benomyl per ml added before autoclaving (PB) or on less in filter-sterilized medium, where 0.2 ug/ml inhibits wild type (O.C. Yoder, personal communication). Called Ben (103); mbic (49). Renamed to avoid confusion with symbol used for benzene resistance (strain now lost).

bn: button
VII. Right of T(T54M50) and, hence, of thi-3 (2%) (789; D.D. Perkins, unpublished data).

Nonconidiating, restricted colonial growth (789). Germination may be better on minimal than on complex complete medium (D.D. Perkins, unpublished data).

bs-1: brown spore-1
IR. Linked to un-1 (9%). probably to the right (818)

Ascospores brown rather than black at maturity and viable. Expressed autonomously, allowing visual scoring in heterozygous asci (818). Used to study factors affecting second-division segregation frequencies (586). Translocation T(I;IV)NM139 bs has a similar, inseparable phenotype; the translocation-associated bs mutation is not allelic with bs-1, although one breakpoint is in IR proximal to al-2 (808).

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Last modified 4/24/96 KMC