FGSC #7856

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Reporting Genes: thi-1 met-6

Species: crassa

Allele: 56501 35809

Alternate Strain Number: 1834

Depositor: DDP

Linkage Group: IR IR

Mating Type: A

Species Number: 10

Genetic Background: SL

Opposite Mating Type: 7857

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
met-6	IR. Right of T(NM103), T(ALS182), and thi-1 (7 to 14%) (808, 1091, PB). Left of ad-9 (2 to 16%) (466, 723, 789). Adjoining or allelic with mac (722, 724). (125) Requires methionine; does not use precursors (718; N. H. Horowitz, cited in reference 1180). Strain(s) carrying allele 35809 lacks polyglutamate forms of folate and, thus, apparently lacks the coenzyme needed for transmethylating homocysteine (208, 886, 963, 964) (Fig. 17). An incorrect report that the mutant met-6 also lacks cystathionine-gamma-synthase (547) proved to be due to the methyl tetrahydrofolate being removed during preparation of extracts; methyl tetrahydrofolate is an activator of cystathionine-gamma-synthase (965). The relationships between met-6 (35809) and its probable alleles met (S2706) and mac (65108) are not clear. met (S2706) and mac both complement met-6 (35809), but do not complement each other, indicating that at least met (S2706) and mac are alleles. In a high-resolution recombination study with flanking markers, met-6 (35809) and met (S2706) behaved like alleles, but mac behaved atypically, although almost equally closely linked (724). The mac mutant is reported to differ from the others in causing an accessory requirement for adenine and possibly cystine (290), whereas met-6 (35809) and met (S2706) strains are stimulated by adenine only in a CO2-enriched atmosphere (G. Roberts, cited in reference 724). mac and met-6(35809) strains evidently lack different folylpolyglutamate synthetase activities (208, 886). Used to study polarity in intralocus recombination (722, 724). Polarity with respect to flanking markers is not reversed when the met-6 region is inverted relative to the centromere (722).	IR	B
thi-1	IR. Right of the T(4540) right breakpoint and cys-9 (13%). Left of T(NM103), T(ALS182), and met-6 (7 to 14%) (721, 808, 816, 1091). (482). Uses thiamine or precursors pyrimidine plus thiazole (1059). Adaptation to growth on minimal medium occurs after a lag; growth tests should, therefore, be scored early. Adaptation is not carried over via ascospores, conidia, or small mycelial fragments. Adaptive growth is paralleled by attainment of wild-type thiamine pyrophosphate and carboxylase levels. Apparently concerns utilization of intact thiamine rather than its biosynthesis. (302, 303). Allele 17084 is inseparable from translocation T(IR;VII)17084 (808).	IR	B