oak : oak
VR. Between un-9 (7%) and T(DBL9), his-6 (6%) (1593).
Conidia form in dense balls above trunklike adherent hyphal aggregates. These may sometimes stand alone on an agar surface rather than lying prone, with a shape suggesting a tiny tree.
oar1 : 3-oxyacyl-[acyl carrier protein] reductase 1
Cloned and sequenced: EMBL/GenBank AF042860.
Nuclear gene encoding mitochondrial protein 3-oxyacyl-[acyl carrier protein] reductase-1 (EC 188.8.131.52) (251).
oli : oligomycin resistant
VIIR. Between for, frq, and un-10 by chromosomal walk (1094). Linked to frq-1 (<2%) (537).
Cloned and sequenced: Swissprot ATP9_NEUCR, EMBL V00864, PIR S07173, LWNCA, S43893, GenBank V00864, NCATP1, EST NC1A8 (2152).
Encodes the ATP synthase DCCD-binding subunit of the membrane proton channel F0 (subunit c according to current nomenclature, previously designated subunit 9) (1863). The amino acid sequence (81 residues) of the purified polypeptide shows extensive homology with the corresponding proteolipid in yeast where, in contrast to Neurospora, it is the product of a mitochondrial gene (1866, 2171). An alternative form of this subunit (considered nonfunctional) is encoded by a Neurospora mitochondrial gene (937; see Appendix 4); the transcript of this gene accumulates rapidly during conidial germination (183). Specific single-amino-acid substitutions have been identified for three mutants (1865). The characterization of the cDNA encoding the precursor polypeptide yielded the first reported sequence of a cleaved N-terminal mitochondrial signal peptide (2152). oli mutants are resistant to oligomycin and defective in energy transduction (594). Mutants are selected effectively using the double mutant azs; has (called ANT-1), which is deficient in both SHAM-sensitive and azide-sensitive alternate oxidase pathways. Scored on 5 mg/ml oligomycin in liquid medium at 3 days, 30ºC (596). A slightly altered period of circadian rhythm cosegregates and reverts with oli (536, 537). Also called atp-9, prl-1.
opi-1 : overproduction of inositol-1
IVR. Linked to cot-1 (9%), T(IV;V)R2355 in alcoy. Unlinked to inl (1807).
Isolated as slow-growing suppressors of 89601, an allele that produces defective myoinositol-1-phosphate synthase (EC 184.108.40.206). The opi -1 mutant enhances synthesis of the defective enzyme by increasing the level of its residual activity and enabling the opi-1; inl double-mutant strain to grow slowly. In opi-1; inl+, the enzyme is overexpressed and inositol is excreted (1807). For an allele-specific partial suppressor of another allele, see su(inl).
os : osmotic sensitive
Unable to grow on media with elevated osmotic pressure. Scorable on solid or liquid media plus 4% NaCl (1.4 M). Most mutant alleles result in a characteristic abnormal morphology, having sticky, close-cropped aerial hyphae that tend to rupture and bleed. Morphology is influenced by humidity. When conidia are produced, they are sticky and do not shake loose. Intense pigment of aggregated hyphae has led to some os mutants initially being called “flame” or “overproduction of carotenoids.” os strains are useful for obtaining protoplasts (1881) and are reported to be efficient as recipients for DNA-mediated transformation in media of high osmolarity (2245). In addition to the numerous loci designated os, cut is a typical osmotic mutant. Osmotic sensitivity is correlated with resistance to dicarboximide fungicides (788, 790). os-1, os-2, os-4, and os-5 are resistant whereas cut is not (788). smco-2 (an sc allele), smco-8, and smco-9 are osmotic-sensitive and resistant to dicarboximide fungicides (789). Mutants sor-4 T9, os-8, and os-9 are osmotic-sensitive but do not show the typical os morphology. An os-1 mutant forms protoplasts that grow and divide in special liquid media (1881), but os-2, os-4, and os-5 do not (1844).
os-1 : osmotic-1
IR. Between nic-1 (10%; 29%), T(UK2-26)R and prd-4 (2%), arg-13 (1%; 4%) (56, 1548, 1585, 1592).
Cloned and sequenced: EMBL/GenBank U53189, U50263.
Structural gene for a putative histidine kinase osmosensor (by homology to bacteria and yeast) (1844). Sensitive to high osmotic pressure. Resistant to dicarboximide fungicides (788). Readily scored by morphology on nonmoist slants or by failure to grow on media with 4% NaCl. Most os-1 alleles form no or few conidia. Alleles NM233t and NM204t are heat-sensitive (25 vs 34ºC). Cell-wall pores are 4 times larger in os-1 than in wild type. The os-1 mutant also has a higher exclusion threshold and a 30-fold higher galactosamine:glucosamine ratio (2105, 2106). Forms protoplasts in media of high osmolarity (609, 824). Allele B135 is an essential genotypic component of the wall-less strain slime (607). Heat-sensitive allele NM233t forms protoplasts following the incubation of macroconidia in liquid medium with polyoxin B; it then resembles the slime strain. The protoplasts divide stably at 37ºC in the absence of the enzyme with a 7.5-hr redoubling time, and they show good regeneration upon return to permissive temperature (1879, 1881); (1,3)-b-glucan and chitin polymers are secreted rather than being incorporated into a cell wall (1844). Complementation can occur between alleles (1352). Allele Y256M209 was called flm-1. An os-1 allele initially called nik-1 was identified using PCR primers designed to amplify the histidine kinase consensus regions (31). The nik-1 null mutant obtained by RIP was phenotypically os-like. Allelism of nik-1 with os-1 was subsequently inferred from the identity of the two DNA sequences (1844).
os-2 : osmotic-2
IVR. Right of cot-1 (4%) (1592, 1828).
Cloned and sequenced (2301).
Readily scored by osmotic sensitivity or morphology. Resistant to dicarboximide fungicides (788). Transformants with os-2+ become sensitive to phenylpyrrole fungicides (2301). T(V44o) is inseparable from os-2 (1578).
os-3 : osmotic-3
IR. Reported to be right of nic-2 (4%) (1304).
Because of stock loss and ambiguity, validity as a separate locus cannot be confirmed (1305, 1559).
os-4 : osmotic-4
IR. Between sn (3%) and T(AR173)L, T(AR190); hence left of un-2, his-2. [Data are for allele Y256M233 (1559, 1578, 2072).]
Readily scored by osmotic sensitivity or morphology. Resistant to dicarboximide fungicides (788). Allele Y256M223, originally called flm-2, is preferred as a marker to NM201o, on which the locus designation was based initially (1559).
os-5 : osmotic-5
IR. Linked to al-2 (<1%). Between T(UK1-35), T(STL76) and Tp(T54M94)R, arg-6 (1%), al-1 (1%) (1559, 1578, 1580).
Scorable by osmotic sensitivity or morphology. Resistant to dicarboximide fungicides (788). A modifier gene mod(os-5) restores normal morphology and osmotic sensitivity while retaining high fungicide resistance (786).
os-6 : osmotic-6
Linked to os-1 (4%), os-7 (6%) (1352).
An osmotic-sensitive mutant obtained among Inl+ transformants (1352). Recombination and complementation evidence showed it to be nonallelic with os-1. Orientation with respect to the centromere was not determined (1305). Because tests for allelism with os-3, os-4, and os-5 were made using tester strains that were later shown to be of dubious validity, it remains uncertain whether os-6 actually represents a new locus.
os-7 : osmotic-7
Linked to os-1 (11%), os-6 (6%) (1352).
An osmotic-sensitive mutant obtained among Inl+ transformants (1352). Recombination and complementation evidence showed it to be nonallelic with os-1. Orientation with respect to the centromere was not determined (1352). Because tests for allelism with os-3, os-4, and os-5 were made using tester strains that were later shown to be of dubious validity, it remains uncertain whether os-7 actually represents a new locus.
os-8 : osmotic-8
IIIR. Between ad-2 and trp-1 (283, 1381).
Fails to grow on 4% NaCl, but morphology and conidiation appear normal. Conidia do not shake loose when a slant is tapped, but os-8 does not have the defects responsible for failed conidial separation in csp or eas. Both osmotic sensitivity and conidial separation are recessive (281-283, 1381). Called SS-931.
os-9 : osmotic-9
VIR. Between ad-1, del and trp-2 (154, 254).
Fails to grow on medium with 4% sodium chloride, but growth is wild type on elevated levels of potassium chloride or glucose (1097a). Wild type morphology. Called SS-788 (252-254).
os-10 : osmotic-10
IV. Linked to cut (5%; 21%), col-4 (8%; 10%) (2000, 2001).
Fails to grow on medium with 4% sodium chloride. Morphologically wild type. Called SC-1018 (2001).
os-11 : osmotic-11
III. Linked to os-8 (19%) (154).
Fails to grow on medium with 4% sodium chloride, but growth is wild type on elevated levels of potassium chloride or glucose (1097a). Morphology resembles that of wild type. os-8, -9, -10, and -11 all originated from the same mutant hunt, using filtration enrichment in medium with 3% NaCl following UV irradiation of conidia. Called SS-18 (154).
osb : oxysterol-binding protein
Cloned and sequenced: EMBL/GenBank Y12693, GenBank NCOSBP.
Encodes oxysterol binding protein (1342).
osr-1 : oxidative phosphorylation stress response-1
IV. Linked to trp-4 (20%) (162).
Affects the stress response, which mediates the suppressiveness of those mitochondrial mutations that impair electron transport and result in senescence or respiratory deficiency. Suppressiveness is blocked because the stress response cannot be turned on in the osr-1 mutant (163).
osr-2 : oxidative phosphorylation stress response-2
II. Linked to arg-5 (£12%) (162).
Affects the stress response, which mediates the suppressiveness of those mitochondrial mutations that impair electron transport and result in senescence or respiratory deficiency. Suppressiveness is blocked because the stress response is turned on constitutively in the osr-2 mutant (163).
ota : ornithine transaminase
IIIR. Between ad-4 (15%) and tyr-1 (14%) (465). Linked to pro-4 (4%) [D. West, cited in ref. (108)].
Specifies ornithine transaminase (EC 220.127.116.11) (465) (Fig. 10). Conidiates somewhat less than wild type (232). Selected by its ability to use exogenous ornithine as a precursor for arginine in the double mutant arg-5 arg-12s. Catabolism of ornithine (to glutamic semialdehyde) is blocked, resulting in ornithine concentrations high enough to compensate for the low activity of the ornithine carbamyl transferase in arg-12s. The ota single mutant is prototrophic, but prevents the efficient use of ornithine or arginine as the sole nitrogen source (465). Used to study flux through the arginine biosynthetic pathway (752), the utilization of endogenous vs exogenous ornithine (453), and the compartmentalization of ornithine in the cell (209, 467). The triple mutant arg-12; ota; aga is used to look at deoxyhypusine and hypusine modification of a 21-kDa polypeptide (2261) that is the eIF5A precursor (see eif5a). Sideramine production is completely blocked in the absence of ornithine in the triple mutant arg-5; ota; aga, which is used to study iron transport (2227, 2229) and iron storage (1296, 1297).
ovc : overaccumulator of carotenoids
IV. Contradictory evidence places ovc (S20-16, FGSC 4503) either in IVR between col-4 (10%) and met-5 (14%) (836) or as an allele of cut in IVL (94). The met-5 strain (FGSC 141) used in ref. (836) contained an ovc-linked, deleterious, undefined mutation that may have led to apparent linkage in IVL that is spurious (1546). For this reason, and because of phenotypic similarity, location of ovc at the cut locus is favored.
Produces more photoinduced carotenoid pigments than wild type when incubated at temperatures above 6ºC, but about the same at 6ºC (836). Probably allelic with cut. Strain S20-16 (FGSC 4503) is indistinguishable from cut in increased pigmentation, osmotic sensitivity, and altered morphology of aerial hyphae (94). ovc makes some pigment in the dark (834), suggesting possible allelism with one of the unmapped ccb mutants, which overaccumulate carotenoid pigments in the light (1208).
oxD : D-amino acid oxidase
IVR. Between T(S1229)L, pdx-1 (0T/55 asci), T(S1229)L and T(B362)L, met-1 (3%). Not separated from cys-15 (111, 1490, 1580).
Lacks D-amino acid oxidase (EC 18.104.22.168) and is unable to use D-methionine as a sole sulfur source or to satisfy the growth requirement of met-1. Shows increased sensitivity to the toxic effects of D-phenylalanine and D-tyrosine (1490). Resistant to inhibition by D-ethionine (901). The strain of origin of allele oxD1 simultaneously became a cysteine auxotroph, cys-15, thought to be due to a closely linked coincident lesion (1490).
For alternate terminal oxidases, see aod, azs, has, cni-1.
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