Dorothy Newmeyer

Map construction in Neurospora crassa.

Publisher Summary In this chapter linkage and centromere data from neurospora crassa have been compiled from all published material, as well as unpublished sources. Tetrad data from gene–centromere and gene–gene intervals have been placed on a uniform basis for mapping by computing map lengths from second-division segregation frequencies and tetratype segregation frequencies, respectively. Maps of the seven linkage groups have been constructed from tetrad data. Seventy-five loci are shown. Confidence limits are indicated for the position of each locus. Two sets of maps are presented, the first is completely uncorrected for multiple crossovers and the second is corrected by means of the mapping function. A few additional genes have been assigned to specific linkage groups on the basis of random isolates. The use of random isolates for mapping is also discussed.

New markers and map sequences inNeurospora crassa, with a description of mapping by duplication coverage, and of multiple translocation stocks for testing linkage

Thirty previously unmapped markers have been located; 13 are at newly designated loci. Numerous sequences for previously mapped genes have also been determined. A revised map of linkage group I is presented. The order from conventional mapping has been confirmed by testing recessive markers in IL for coverage by duplications. Assignment of new mutants to linkage groups is greatly facilitated by using gene-tagged multiple translocation strains for linkage detection; these “alcoy” tester strains and procedures for using them are described. Recent mapping data of other workers are compiled. Distal markers are now known for all but one of the 14 chromosome arms, but extensive map segments are still devoid of markers.

Giant ascospores and abnormal croziers in a mutant of Neurospora crassa

In crosses heterozygous for a dominant mutant, Banana ( Ban ), nearly all asci delimit a single large banana-shaped ascospore instead of eight normal spores. Ascus development and its nuclear divisions are normal until after the third division. In the Ban + / Ban ascus, the eight nuclei do not become realigned in single file but remain across the axis, and a single large ascospore wall is delimited enclosing them all. During wall formation, the spindle pole bodies greatly decrease in size. The nuclei then divide once, or rarely twice, so that the Banana ascospores contain 16 or 32 nuclei. After the first 40 to 60 asci per perithecium are formed, the croziers stop making new asci. Instead, the nuclei in most ascogenous cells divide several times mitotically and synchronously; all nuclei in an affected crozier are found at the same stage of mitosis. Some ascogenous cells, however, make very large nuclei, sometimes with more than one nucleolus. The multinucleate and giant-nucleate cells eventually degenerate, and new asci subsequently develop and make Banana ascospores. It has been shown, with the aid of mei-3 which blocks meiosis, that the supernumerary mitoses in the croziers do not depend on the delimitation of Banana ascopores. Ban is linked to mating type and is probably left of leu-3. Ban strains have abnormal vegetative morphology and are female sterile.

Arginine synthesis in Neurospora crassa; Genetic studies.

SUMMARY: Nine mutants of Neurospora crassa which require arginine as a nutrient but cannot use citrulline were obtained from various sources. These fall into two classes, according to location in linkage group I or VII. (Enzymic tests, reported elsewhere, indicate that the two classes of mutants affect the enzymes which control the two reactions between citrulline and arginine.) Heterokaryon tests between mutants of the same group were negative, and crosses between mutants of the same group were semi-sterile, most of the aseospores being non-viable. Crosses between the five group I mutants produced no arg + progeny, and separate mapping tests on four of them indicate that they are either allelic or closely linked. All crosses between the group VII mutants gave many arg+ progeny. For the one pair of mutants which was studied in detail, origin of the arg + by means other than crossing-over (or gene conversion) has been virtually eliminated. However, mapping studies place the two mutants only 0-6 units apart. It is concluded that the high arg + frequency is due to selection, and that the mutants might be pseudoalleles.

An annotated pedigree of Neurospora crassa laboratory wild types, showing the probable origin of the nucleolus satellite and showing that certain stocks are not authentic.

An annotated pedigree of Neurospora crassa laboratory wild types, showing the probable origin of the nucleolus satellite and showing that certain stocks are not authentic. This regular paper is available in Fungal Genetics Reports: https://newprairiepress.org/fgr/vol34/iss1/14 Newmeyer, D., D.D. Perkins

Neurospora mutants sensitive both to mutagens and to histidine

SummaryPrevious work in this and other laboratories showed that histidine strongly inhibits growth of mutants at ten out of 20 known mutagen-sensitivity loci in Neurospora, and that nine of the histidine-sensitive mutants disturb meiosis when homozygous. These and other results suggested that histidine affects recombination or DNA repair. Current work with the histidine-sensitive mutant uvs-6 shows that it is also inhibited by several other metabolites but none of them is as effective as histidine. On minimal medium without histidine or other inhibitors, uvs-6 first grows normally, then slows drastically and begins stop-start growth. Conidia from stop-start uvs-6 mycelia produce rejuvenated cultures. The stop-start growth, UV-sensitivity, histidine-sensitivity, and recessive meiotic characters of uvs-6 segregated together in crosses, and reverted together. In tests on other mutagen-sensitive mutants, sensitivity to histidine was strongly correlated with stop-start growth and with sensitivity to other metabolites. Histidine induces premature stop-start growth in at least two mutants. Several possible explanations for the histidine-sensitivity have been excluded.

Genes influencing the conversion of citrulline to argininosuccinate in Neurospora crassa.

SUMMARY: The enzymic conversion of citrulline argininosuccinate arginine in wild-type Neurospora crassa has been shown to be essentially like that in mammalian tissues in all respects tested. The enzymes responsible for the two reactions (condensing enzyme and argininosuccinase) have been partially separated. Five mutants at the arg-1 locus have normal arginino-succinase and little or no condensing activity. The lack of condensing activity appears to be due to a simple absence of enzyme, alternatives such as inhibitor production or increased ATPase competition having been ruled out. Small amounts of apparent condensing activity, detected in the substrate-disappearance assay, were shown to be due to side reactions. When grown at the usual high arginine concentrations, three mutants at the arg-10 locus, which are known to lack argininosuccinase, have normal condensing activity. However, when arg-10 strains are grown at low arginine concentrations, the resulting extracts have very little condensing activity. This also appears to be due to a simple loss of condensing enzyme. It has not been determined whether the low activity is a specific secondary effect of arg-10 on the condensing enzyme, or whether it is merely a non-specific effect of the inadequate supplementation, which might cause reductions in many enzyme activities. Despite its very low condensing activity in vitro, arg-10 grown at low arginine concentrations must be active at some time in vivo, since its mycelium accumulates argininosuccinate but not citrulline. In contrast, an arg-1 arg-10 double mutant, grown at low arginine concentrations, must be inactive in vivo, since it accumulates citrulline but not argininosuccinate. It is concluded that arg-1 is probably the primary locus controlling the synthesis of condensing enzyme.

Raymond W. Barratt, 1920-2002

Raymond W. Barratt 1920-2002 Creative Commons License This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License. This obituary is available in Fungal Genetics Reports: http://newprairiepress.org/fgr/vol50/iss1/9 20 Fungal Genetics Newsletter Obituaries Raymond W. Barratt 1920-2002 Raymond Barratt, who died of cancer in December, 2002, was a prominent player in the early development of fungal genetics. After early work with fungal plant pathogens at the Connecticut Agricultural Experiment Station, he switched to Neurospora and became Ed Tatums first graduate student at Yale. When the Tatum lab moved to Stanford in 1948, Ray continued as a Research Fellow, conducting his own research, supervising the laboratory, and becoming a teacher, helper, and friend to all the new students and postdocs. During this period he took the initiative in assigning gene names and formulating rules of genetic nomenclature for Neurospora (1) and in bringing together genetic and phenotypic information on all the known genes into what might be called the first Neurospora compendium, which included the first comprehensive maps (2). In 1954 he went to Dartmouth as a faculty member. He organized the Fungal Genetics Stock Center (FGSC), gathering Neurospora mutant and wild-type strains, obtaining funding from NSF, perfecting preservation methods, and periodically publishing stock lists in the Neurospora Newsletter (now Fungal Genetics Newsletter). The Newsletter, produced and distributed by FGSC, was founded with Rays help in 1961 following the first Neurospora Information Conference (now Fungal Genetics Conference), of which he was a co-organizer. He continued to direct the stock center for 25 years, during which it was expanded to include other filamentous fungi. In 1970 he resigned as chair of the Biology Department at Dartmouth and became Professor of Biology and Dean of Sciences at California State University, Humboldt, taking the stock center with him. Rays research, though limited, contributed significantly to progress at the time. From studies of morphological mutants (3) and chemical mutagens, he turned to gene-enzyme relations. He was fascinated with mutants having complex metabolic effects; for example, phe-1 (4), ilv (5), and am (6). He was attracted to am mutants because their growth requirement could be satisfied by any of numerous amino acids, and his most extensive studies were of the am gene, which specifies NADP-specific glutamate dehydrogenase. (Stud ies of am were begun independently and carried to culmination by John Fincham and his colleagues.) After his move to Dartmouth, Rays experimental contributions were limited by other responsibilities. He was a superb organizer, and the choice to direct the stock center and to assume various academic obligations at the expense of his research was no doubt made deliberately. The stock center was set up and run fastidiously, with help of the curator, Bill Ogata, who followed Ray from Stanford to D artmouth and later returned with him to California. FGSC proved to be a major asse t, consolidating the fungal genetics community and setting an example of quality control, genetic sophistication, and economical management. Ray reminisced in 1985 that his contribution to the field of fungal genetics through the stock center may well have been equal to what he would have accomplished had he continued in full time research. All those who work with Neurospora and other filamentous fungi owe Raymond Barratt a debt of gratitude, and those of us fortunate enough to have known him personally remember him with affection as a genial, enthusiastic, and always helpful colleague. Dorothy Newmeyer and David Perkins l. Barratt, R. W . 1954. Neurospora nomenclature in use at Stanford University. Microbial Genet. Bull. 9: 20-23. 2. Barratt, R. W., D. Newmeyer, D. D. Perkins, and L. Garnjobst. 1954. Map construction in Neurospora crassa . Advan. Genet. 6: 1-93. 3. Barratt, R. W., and L. Garnjobst. 1949. Genetics of a colonial microconidiating mutant strain of Neurospora crassa . Genetics 34: 351-369. 4. Barratt, R. W., R. C. Fuller, and S. W. Tanenbaum. 1956. Amino acid interrelationships in certain leucineand aromaticrequiring strains of Neurospora crassa . J. Bacteriol. 71: 108-114. 5. Adelberg, E. A., C. A. Coughlin, and R. W. Barratt. 1955. The biosynthesis of isoleucine and valine. II. Independence of the biosynthetic pathways in Neurospora. J . Biol. Chem. 216: 425-430. 6. Barratt, R. W. 1961. Studies on gene-protein relations with glutamic dehydrogenase in Neurospora crassa . Genetics. 46: 849-850. -1962. Altered proteins produced by mutation at the amination (am) locus in Neurospora. Genetics. 47: 941-942. -1963. Effect of environmental conditions on the NAD P-specific glutamic acid dehydrogenase in Neurospora crassa . J. Gen. Microbiol. 33: 33-42. Published by New Prairie Press, 2017

Genetically determined round ascospores

Genetically determined round ascospores Creative Commons License This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License. This research note is available in Fungal Genetics Reports: http://newprairiepress.org/fgr/vol19/iss1/6 Borry,E. G., D. Newmeyer, D. D. Perkins and B.C. Turner. Genetically determined rwnd ascorprer in N. crasm. In addition to the dominant gene 5 Round spore, discovered by M. B. Mitchell (1966 Neurorpora Newl. 10x5 ), two other genotypes ore now known to result in round spores. Because of their potential interest for studier of morphogeneris, these will be reported briefly, together with mne new cbrerwtions on R. a. Round spores frcm cot-2 x cot-2 (Newmeyer): All arcapares are round when cot-2 (colonial-temperature-sensitive, RlD36; Gorniobst and Tatm967 Genetics 57:579) is homozygcws. Ascorpores are~ormal in heterozygcu crwes. Ar noted by Gum

Gene sequences in linkage group I

brt and Taturn, vegetative morphology of cot-2 is not completely normal ot 2S’C. b. Round spores from T(V+‘lI)EB4 (Barry, Perkins ): A mutation in T(V+Vli)E&( (less than 10%) of round arcorpores in heterorygous crosses. results in a mmll but significant number individual asci usually contain either rwnd rponr only or normal spores only, but sometimes variws ratios of round to non-round spores are fwnd in an oscus (e.~, 7r:lnr. 5r:3nr). The cbrerwtion of a number of intermediate shaped spores, rmnded but not fully spherical, also ruggert an incompletely penetmnt gene for the mutation. The spore mutation has not been separated from the tronrlocation in T(V+‘li)EB4. The mutation was discovered os D minority component of a culture of wild-type 74-ORB-la received at Stanford in 1961 from F. J.de Serves, and preserved on silica gel since that time. Cytologically, a distal segment of chromosome 2L can be seen frequently to be aryrmpred or abnormally Paired at pachynemo in crosses of Tramlocation by Normal. Genetically, CI short unmarked region of VR near al-3 is inserted into VII. When T(V-VlI)EB4 is crossed by Normal, one third of the viable progeny contain duplications, and mundarccrporer are also found when such duplication strains are crossed by Normal. c. Round sparer from RX + (Turner ): R normally results in 100% mund oscorporer in crosses where it ir heterozygovs (first shown by Mitchell 1966. ) R is the riihtmort known marker in I. with the right break points of in(iL-+iR)ARl6 and in(iL~iR)H4250, which it is not terminal, however, as shown by recombination are effectively at the IR tip. R results in peach-like morphology of vegetative cultures, which are female-sterile, producing no perithecia. recessive in R/r duplications (such as those from T(i-V:)NMl03 .) The vegetative>orphology of R is The expression of R in spores does wt depend on clilineor oscus. Spore; ire round when! is present in the flaccid nonlinear asci characteristic Ff erases where* (&) is homozygous (Perkins). A similar dominant Round-SF-we gene has been reported by Novak and S& (1969 Neurosporo Newrl. 15: 22) in N. tetm+ I emw, where it does not interfere with the characteristic delimitation of four rpores. Department of BotonyTUniveoity o North Cnmlim, Chapel Hill, North Carolina 27514 (BEG) and Department of Biologisol Sciences, Stanford University, Stanford, California 94305. Schroeder,A. 1.. F. J.de Serrer and M. E. Schupbochf A new UV-sensitive mutant in Neurospom, ““r-6 (ALS35 ), ha been A new ultraviolet-light-sensitive mutant in isolated using the CT r replica-plating methodxchroeder (1970 Mol. Gen.Genet. 107:291 As shown in the Table, this mutant maps between -9 Neurorpaa, “w-6. zcrisp and ol-2:olbino-2 in the right wm of linkage grwp I. The mutant is abwt 3.3 times more sensitive to UV than is wild type at the UV doses required to reduce both wild-type survival and uvs-6 survival to 37%. cuw~the wild type. A plot of log of per cent survival vs. UV dose giver an exponential curve for ““r-6 and 0 multi-hit The mutant is &O about B-fold more &sitive toY-myr than is wild type at the y-my doses required to reduce both wild-type survival and ws-6 ruwiwl to 37%. Zygote genotype and Parental Singles Singles Doubles Tot.1 progeny and Mmker isolation recombination (%) combinations Region I Region ii Regions I + ii percent germination numbers I i i + uvr-6 + 40 7 3 0 80 8 1 2 3 cr + al-2 2 6 2 2 0 80% ALS35 11 .2 6 .2 15300 -Genetics pmgrom,Warhington State University, Pullman, Washington 99163; Biology Division, Oak Ridge Notional Loborotory,‘* Oak Ridge, Tennessee 37830; and University of Tennessee-&k Ridge Graduate Schccl of Biomedical Sciences, 0o.k Ridge, Tennessee 37830. (’ Postdoctoral investigator supported by subcontract No. 3322 from the Biology Division of Oak Ridge Notional Laboratory to the University of Tennessee. ‘*Operated by the Union Carbide Corporation for the U.S. Atomic Energy Commission.)