FGSC #8964

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Reporting Genes: a^m33 arg-3 ad-3A

Species: crassa

Allele: m33, 30300, Y112M13

Alternate Strain Number: 1814

Depositor: DDP

Linkage Group: Il, L, R

Mating Type: a

Species Number: 10

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
a^m33	IL. Between un-3 (0.04 to 0.1%) and un-16 ( < 1%) (488, 758; D. D. Perkins, unpublished data). (609) Opposite mating types are essential for a complex of events associated with sexual reproduction and morphogenesis: attraction of trichogyne to cells of opposite mating type (39, 93); pickup and transport of the nucleus to the ascogonium; growth and development of the perithecium; proliferation of heterokaryotic ascogenous hyphae; conjugate nuclear divisions in precrozier and crozier cells; karyogamy. Mating type alleles also act as vegetative incompatibility genes during the vegetative phase. A+a combinations are unable to form stable heterokaryons (66, 384, 830, 914). Vegetative fusion is usually followed by cell death (384), but some A+a heterokaryons grow slowly (252, 412, 422). Heterozygous A/a duplications are highly abnormal, with inhibited growth and spider-like morphology (761. 804). Incompatibility in heterokaryons or duplications is relieved by spontaneous deletion of either allele (252, 756). Vegetative incompatibility is not expressed during the sexual phase after fertilization. Both manifestations of vegetative incompatibility are suppressed by tol, but sexual compatibility is not affected (755). The vegetative incompatibility is normally suppressed in N. tetrasperma (668) and N. sitophila (674, 804). Extensive efforts have failed to separate the sexual and vegetative traits by genetic recombination (758). Null mutants selected by loss of vegetative incompatibility usually lose both sexual and vegetative functions simultaneously (one exception), and both functions are usually restored simultaneously in revertants selected for restoration of fertility (one null mutant gives atypical revertants) (252, 411, 412).Only two mating type alleles, A and a, are known. These are apparently homologous throughout the genus Neurospora (820) and perhaps in related genera (770). Nothing is known about the genetics of the five true-homothallic species of Neurospora, which closely resemble N. crassa in karyotype and meiotic behavior, including the fusion of two haploid nuclei in the penultimate cell of the crozier to form the zygote nucleus (855). In the early literature, A was called + (plus) or A, and a was called - (minus) or B (e.g., reference 286). The locus may also be designated mt, mating type (e.g., reference 808), and is usually referred to as mt in the present paper.	IL	B
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
arg-3	Uses citrulline or arginine.	IL	B