Master Strain E of Aspergillus nidulans, which carries genetic markers in all eight linkage groups, is frequently used in crosses to map new genes. The strain carries the facA303 mutation in linkage group V, which makes it unable to use acetate as a carbon source. A new marker conferring resistance to p-fluorophenylalanine (120 ug/ml) was identified in linkage V of this strain. The observed recombination frequency between fpa resistance and facA303 was about 17%. The existence of two mutations in linkage group V of Master Strain E presents alternatives for the genetic analysis of new mutants. Thanks are due to Professor John Clutterbuck for sending us a new sample of Master Strain E.
M. Orbach - Dept. of Plant Pathology, University of Arizona, Tucson, AZ 85721
I published size estimates for the chromosome DNAs of strain 74-OR23-1A in 1988 (MCB 8:1469-1473) based on the relative sizes of the N. crassa aceto-orcein stained pachytene chromosomes combined with Schizosaccharomyces pombe chromosome size markers. The sizes of the S. pombe chromosome chromosomes have now been more accurately measured as 3.5, 4.6 and 5.7 mb, causing a change in the N. crassa size estimates. The revised Neurospora chromosome sizes are:
Chromosome Band Linkage Group Size (former estimate) 1 I 10.3 Mb (12.6 Mb) 2 V 9.2 Mb (10.9 Mb) 3 IV 5.7 Mb (7 Mb) 4 III 5.1 Mb (6 Mb) 5 II 4.6 Mb (4.6 Mb) 6 VI,VII 4.0 Mb (4.0 Mb)H. Liu and T.J. Schmidhauser - Dept. of Medical Biochemistry, Southern Illinois University, Carbondale, IL, 62901-4409
We probed colony blots of the Orbach/Sachs library with a tub-2 specific probe from pSV50. Positive wells were confirmed by use of the tub-2 probe on a southern blot of digests of plasmid DNA isolated from each positive well. The tub-2 containing isolates are G14:11C, G15:1E, G15:3C, X15:4H and X18:12D.
P.A. Hubbard and C.H. Wilson - Fungal Genetics Stock Center, Dept. of Microbiology, University of Kansas Medical Center, Kansas City, KS 66160-7420
In 1980, D.R. Stadler deposited several temperature sensitive methionine mutants at FGSC (see Neurospora Newslett. 28:18). One of them, met(29T) (FGSC 3761), appears to be an occurrence of cys-3. It responds to cysteine and methionine, maps to LG II, and forms asci in which four spores fail to darken. A cross of met(29T) to cys-3 yielded mostly non-viable spores. 20/100 spores germinated within 10 days of being shot. These germinants grew on minimal medium at 25 C and on minimal + methionine at 34 C, but not on unsupplemented medium at the higher temperature.